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    • 专利摘要:
    PROCESS FOR PRODUCING A SAW RIBBON. The present invention relates to a process which is described for producing a saw band for use in a saw cord. Saw cords are used to cut hard and brittle materials. In the process, laser coating is used to form an abrasive layer on a small metal tube (204), or sleeve. The abrasive layer (220) comprises a metallic matrix material, onto which abrasive particles, such as diamond, cubic boron nitride or other hard cutting materials, are embedded. The metallic matrix material preferably comprises an active metal, which improves wetting and adhesion of the abrasive particles. Although the abrasive particles are relatively large - with a particle size greater than 100 (mi)m - they are evenly distributed throughout the abrasive layer. This is achieved by allowing the tube (204) to rotate relative to the laser coating system, possibly in combination with a relative axial movement, so that the coating path meshes with itself, forming an abrasive layer (220). Additionally, the process provides shaping of the saw band for improved geometric tolerances and centering. Production times are less than ten seconds per tape, and (...).
    公开号:BR112013022035B1
    申请号:R112013022035-0
    申请日:2012-03-02
    公开日:2021-07-06
    发明作者:Jan Vaneecke；Roland Groenen；Tom Baekelandt
    申请人:Nv Bekaert Sa；
    IPC主号:
    专利说明:

    TECHNICAL FIELD
    [0001] The present invention relates to a tape for use in a saw cord. These saw cords are used to cut hard and brittle materials, such as natural stone (marble, granite, rock, ...), artificial stone (concrete, masonry, ...), composite materials or crystalline materials (mono- or polycrystalline). TECHNICAL BACKGROUND
    [0002] Tapes having an outer abrasive layer of a metallic matrix, in which diamond powder is embedded, appear to have been first described in the early fifties of the previous century (see, for example, US patent 2,679,839, filed in 1952). These tapes are strung on a steel cord and are separated by means of springs (see U.S. Patent 2,679,839) or by means of a plastic material (see, for example, FR Patent 1,203,000, filed in 1958). The plastic material can also be injected between the tapes with the help of a mold (FR patent 1,203,000, first addition, filed in 1959). The ideas of directly fixing the wire to the steel cord, for example, by means of a pin (patent GB 759,505, filed in 1953), by means of welding (patent FR 1.265.542, first filed in 1960) or by means of stamping (US patent 3,598,101, first filed in 1968) have also been explored.
    [0003] Initially, these saw cords, when used in stationary saws, competed with oscillating blades saws (frames driven in alternating motion with parallel mounted steel blades, in which cutting parts containing diamond are mounted) and circular disc saws. The saw cord was made in a closed loop by splicing the steel cord, as, for example, described in U.S. Patent 2,773,495, filed in 1953). After tensioning the loop on two large motor driven wheels, the cord can be used like a saw. In the current state of the art machines, up to 80 loops are operated parallel to each other, to separate a block of stone into a series of slabs. In an alternative use, these diamond band saw cords began to appear in quarries in the early seventies of the previous century, when they were used for quarrying blocks.
    [0004] Several processes have been explored by which the abrasive material - largely diamond - can be fixed on the tapes. There is the process of affixing diamonds to a metallic tube by means of electrolytic or chemical nickel deposition (international patent application WO 2002/40207). There is also the process of embedding the abrasive particles in a strong weld, which is applied directly to the metallic glove, as described in U.S. Patent 7,089,925.
    [0005] The process became more successful through powder metallurgy (already described in U.S. patent 2,679,839). To this end, an annular abrasive element is made of diamond powder, which is intensively mixed with metallic powder and an optional organic wax to form a paste. The metallic powder mixture typically contains high melting point components such as cobalt, tungsten, iron and nickel, sometimes in combination with low melting point components such as copper, tin and silver to improve consolidation. Possibly, compounds such as tungsten carbide can be added to influence the hardness and wear of the tape. The mixture is placed in a mole. This preform is sintered into a high-density tape by applying pressure (by displacement pressure in the mold or by applying isostatic pressure by immersion in a fluid under high pressure) and temperature. Appropriate gases are applied to prevent powder oxidation during sintering.
    [0006] In the sintering process, the annular abrasive element is heated to a high temperature, followed by a slow cooling, that is, in a state of near thermal equilibrium. Although not all alloy components have the opportunity to melt, the addition of melting point lowering components will generate intermediate phases between the different components by diffusion. The metallographic cross section of this annular element therefore shows a globular and/or granular structure. In the classic tape sintering process, it is generally preferred that the grain sizes be small in order to obtain sufficient matrix material hardness. This grain size can be affected by varying the properties of the starting powders and their consolidation conditions. In any case, the grains remain visible in a suitably chemically etched metallographic cross section and no directional growth effects are visible. See, for example, "Powder Metallurgy Diamond Tools" by Janusz Konstanty, Chapter 5, 2005, Elsevier Science Title, ISBN 978-1-85617-440-4.
    [0007] The selection of metals, proportion and type of diamonds, and the pressure - temperature history are known for internal use by producers, which influence the quality of the final product.
    [0008] After sintering, the annular abrasive element is fixed in a metallic sleeve, slightly longer than the abrasive element, by means of a strong weld. The combination of the metallic glove and the abrasive element is called a tape. The need for a metal tube to fix the abrasive element therein can be eliminated by forming the abrasive element sufficiently precisely, as described in US patent application 2007/0194492 A1 .
    [0009] Sintered tapes have become technological leaders because: - they have a sufficiently thick abrasive layer; - in which the diamonds are set randomly by the layer; - the used matrix material wears like diamonds; - at the same time, the matrix material retains diamonds well; and - because tapes can be made reproducibly with close geometric tolerances.
    [00010] Then, the tapes are threaded onto a steel filament carrier cord ("steel cord"), and subsequently secured by springs or a plastic. This "threading step" is tedious and time-intensive. As the surface of the tapes is smooth, due to compression in a mold, the tapes must be treated" before they are used. This is usually done by using the saw cord initially at a low cutting speed, until the abrasive particles are released from the surface and cut better. This "treatment step" is time-consuming.
    [00011] Another process to produce the abrasive layers is currently producing its forays into the world of saw blades for stone cutting, ie laser coating. In laser coating, a stream of powder is fed into a high-intensity beam of a laser, which is focused on the substrate surface by means of a gas current vehicle. Dust is a mixture of metallic powder and abrasive particles (usually diamond). The powder melts and forms a molten metal deposit, which solidifies and fixes the abrasive particles.
    [00012] Patent application DE 195 20 149 A1 describes a process for laser coating an SB, in which by means of a cooled (or heated) mold, an almost final finish of an abrasive or wear-resistant surface can be formed. The coating is applied to the mold, after which the mold is removed. The application only discusses deposition on relatively bulky substrates such as a saw blade. The coating is done in a single layer.
    [00013] The international patent application WO 1999/18260 (patent EP 1027476) describes a cutting tool, formed on a steel substrate with an abrasive coating, comprising abrasive material embedded in a wetting agent containing a metallic matrix or metallic alloy, wherein between the abrasive coating and the steel substrate, a non-ferrous layer is present, which is substantially free of wetting agent. Although the summary mentions a saw handle as an example of a cutting tool, this is not further exemplified in the description.
    [00014] In laser coating, the low density of diamond relative to that of a molten metal causes the diamond to float in the metallic deposit, which causes a heterogeneous distribution of diamonds (see Figure 16 of "Herstellung diamanthaltiger, end- konturnaher, Metallmatriz-Verbundwerkstoffe durch Laserstrahlbes-crhichten" by A. Lang and HW Bergmann in "Material-Wissenschaften und Werkstofftechnologie", vol. 27 pages 215 - 226, 1996). One solution is to use finer abrasive particles in which buoyancy is slowed down by the viscosity of the metal deposit. But for many technological applications - notably stone cutting - fine diamond particles are an option.
    [00015] Another solution is described in the international patent application WO 1998/15672, in which a particular arrangement of a vertical substrate surface movement with a laser coating tool, in the horizontal direction, causes an elevation of the diamond particles, in the direction of the deposited layer. Again, the deposition is on one layer.
    [00016] The international patent application WO 02/06553 describes a process for producing saw ribbons, according to the laser coating process. No details are given of the metallographic structure resulting from the process, nor of the materials used. A pre- and post-processing of the resulting carrier tube is required to obtain the saw band.
    [00017] Although the processes described for producing a cutting tool by means of laser coating are sometimes suggested as being suitable for producing saw cord tapes, this was not common to all inventors. All patents describe the deposition of a laser coated abrasive layer onto a solid low carbon steel substrate (such as a saw wheel or tube). In these cases, a large heat sink is available to drain excess heat.
    [00018] The inventors considered and solved four major problems: - one problem is to drain heat sufficiently quickly from a tiny metallic glove less than one gram (!), so that it does not deform, or, in a total disaster, melts completely; on the other hand, sufficient heat must be provided so that it is possible to obtain a strong bond to the glove and form a dense abrasive layer; this is called the "heating problem"; - the "geometry problem", in which it is difficult to consistently produce tapes within geometric tolerances and with sufficient rounding and centering; this problem is particularly important, as during use, the saw cord must rotate to ensure an even wear of the abrasive layer; - the "particle distribution problem", in which it is difficult to have an even distribution of abrasive particles in the abrasive coating; this is important as, during use, the matrix material usually wears out gradually discovering the diamonds extending into the lowest radial part of the layer; if all diamonds are, for example, on the surface, they will wear out first and no diamonds extending into the lowest part will be available; - the treatment problem, which is the problem in which abrasive particles are buried under a layer of matrix material and lose their activity from the first use onwards. DESCRIPTION OF THE INVENTION
    [00019] The aim of the invention is, therefore, to overcome the problems encountered when applying the "laser coating technique" to produce saw ribbons for a saw cord. More specifically, the objects of the invention are to provide a solution to the "heating problem", "geometry problem", "particle distribution problem" and "treatment problem", separately or in combination. Another objective of the invention was to keep the number of processing steps as small as possible to reduce the total cost of the tape production process. Another object of the invention was to eliminate the need for a "ribbon threading step" in the production of a saw cord, ie to be able to produce a strip "in situ" on the steel cord. PRODUCTIVE PROCESS AND TOOL SELECTION SECTION
    [00020] The process will be clarified with references to Figures 1 to 3 and 10. The digit one hundred refers to the figure number, in which an item is introduced first.
    [00021] According to a first aspect of the invention, a production process for a tape is described. The process starts from a metallic tube 204, having an outside diameter OD. In the most extreme case, the tube can be a rod, but this is not preferred as it introduces an additional step of drilling a central hole after the tape has been produced. Therefore, the metal tube preferably has an internal diameter ID, slightly larger than the diameter of the steel cord. Next, "a sleeve" is a tube, which is shorter, as it were, by ten times the outer diameter of the tube. Therefore, "a glove" is a particular type of "tube". The size of current saw cords is standardized. Currently, the following types for the tape-carrying sleeve are particularly preferred: - 5 mm inner diameter, 7 mm outer diameter (ie wall thickness is 1 mm), length 11 mm, with a mass 1.6 gram total; including the abrasive layer the tape has a total diameter of about 9 to 11 mm; this is for use with a 4.95mm diameter steel cord; this size is particularly preferred for extracting blocks in quarries; and - 3.7 mm outside diameter, 5.0 mm outside diameter (i.e., 0.65 mm wall thickness), 11 mm length, with a total mass of 0.77 grams; this size is particularly preferred for plate cutting machines; the total outer diameter of the tape is about 7.2 mm (5.7 mm at the end of use); the steel cord has a diameter of 3.5 to 3.6 mm.
    [00022] For the future, gloves with even smaller diameters, such as, for example, an inner diameter of about 3.0, or even less than 2.5 mm, an outer diameter of at most 4.0 mm, with wall thicknesses less than 0,5 mm, a length equal to or less than 11 mm, with a weight less than 0,5 grams and an overall diameter less than 7,0 mm are considered; the steel cord will have a diameter less than 2.9.
    [00023] In each case, about 1 to 3 grams, sometimes 1 to 2 grams of abrasive layer need to be present on the glove. Naturally, the more abrasive layer load present, the longer the tape's service life. The sizes and masses mentioned above are indicative. The trend towards thinner overall diameters is for this reason. This makes the sleeves get smaller and smaller, and therefore the starting tube will have a smaller OD and wall thickness.
    [00024] The mass of the abrasive material in the tube is, after application of the process, greater than the mass of the tube or rod, covered by the abrasive layer. Or even more serious: the tube wall thickness is less than the abrasive layer thickness. It is to the inventors' credit that they discovered how thick the coating can be deposited on this minimal substrate.
    [00025] The tube is retained, at one or both ends, by means of a vise grip or a drill chuck or similar fastener 202. The tube is preferably rotatably mounted, and, optionally, the tube it can be displaced axially for at least the length of the abrasive layer (5 to 15 mm).
    [00026] In the process, use is made of a laser coating system 100, equipped with: - a high-intensity laser capable of releasing beams of at least 100 W, 1 kW or more of continuous or pulsating energy, preferably , with emission in the infrared region of the spectrum; Nd:YAG lasers (neodymium-doped yttrium-aluminum garnet) pumped by strobe lamps or solid state lasers or CO2 gas lasers are particularly suitable; the laser light is guided by waveguides and optical components 112 so that it has a focal point 103, which can be adjusted in the vicinity of the substrate surface; - a source of metallic matrix material 104, in the form of a powder, or a wire or a ribbon, which is fed into the focal point of the laser; the powder can be, for example, supplied in a carrier gas, preferably a non-oxidizing gas or an inert gas such as argon; and - a source of abrasive particles 102; these particles are preferably carried by a stream of carrier gas; preferably, the type of gas for driving the abrasive particles and for driving the metallic matrix material is the same; alternatively, and also preferred, is that the abrasive particle source 102 can be made simply by diffusion.
    [00027] Preferably, each of the sources of metal matrix powder 104, abrasive particles 102, or heat absorbed by means of the laser, can be modulated independently in time, and can occur by separate feed channels; the sources of abrasive matrix powder 104 and abrasive particles 102 can be combined in a single feed channel, although this is not necessary.
    [00028] A particularly preferred procedure is when the metal matrix material source and the source of abrasive particles are such that the average thickness of the formed track is between 0.1 and 5 times, or between 0.5 and 3 times, or between 1 and 3 times the average size of the abrasive particles. By "average thickness" is meant the arithmetic mean of at least 12 measurements in the radial direction, at regular angular intervals excluding the radii passing through the abrasive particles. The mass fluxes required for each of the respective sources of abrasive particles and metallic matrix material can be calculated from the densities of both constituents.
    [00029] Preferably, the carrier gas stream is directed by means of a laser cannon, as described in US patent 6,316,744, in which the gaseous flow is coaxial to the laser cannon and converges towards the focal point by a tapered annular mouthpiece. This laser cannon is also water cooled to prevent nozzle heating. The metallic matrix material can be fed through the laser cannon, while the abrasive is released by a separate gaseous stream, or simply by diffusion. Alternatively, the metallic matrix material can be released from a nozzle separate from the laser gun, while the abrasive particles are fed through the laser gun. Or both the abrasive particles and the metallic matrix material can be fed by the laser cannon. It is preferred that the source of abrasive particles and the source of metallic matrix material are separate as they do not have different powders - and therefore flow - properties.
    [00030] The laser light path is adjusted so that the focal point 103 is in the vicinity of the surface of the tube 110. A particularly preferred embodiment of the process is when the focal point 103 is formed slightly (3 to 10 mm) above the tube surface of metallic substrate. In this way, the matrix material is heated before striking the tube surface. The heated metallic matrix material then adheres better to the metallic tube 204.
    [00031] Thereby, a molten metal deposit 108 forms on the substrate tube. At the same time - or slightly later - the abrasive particles are hurled into the molten metal deposit by the abrasive particle source 102, driven by the carrier gas, or by gravity-assisted diffusion of the particles.
    [00032] Even before the laser coating system is fired, the metal tube is made to rotate around its axis. Alternatively, the laser cannon can be rotated around the axis of the stationary metal tube. Or both the tube and laser cannon may rotate relatively to each other. Naturally, the first alternative is particularly preferred, as this is the least complex. A relative rotational movement 209 between the metal tube and the laser coating system is thereby established.
    [00033] As soon as the laser coating system is started, a trail 206 of solidified metallic matrix material forms in the tube. A slight delay between laser ignition and arrival of the abrasive particles allows the molten metal deposit to be established, before the first abrasive particles are thrown into it. If the laser cannon is not moved axially relative to the metal tube, a track will be established that closes on itself. The material will - after a spin - be deposited on the already solidified material. This is particularly preferred if the laser gun's mouthpiece releases a sufficiently wide track, i.e. the track width "W" is approximately the length of the tape. Laser coating track profiles show a generally elliptical or rectangular distribution, so their widths can be easily established. Track width refers to the size of the laser spot, perpendicular to the direction of relative movement. Figure 10a shows a cross-section of a tape with a sleeve 1012 and with a single track spirally wound onto it, resulting in topcoat of subsequent layers 1004, 1004',...1004IV between each other.
    [00034] If the laser gun nozzle does not cover the width required for the ribbon, introducing a relative axial motion 211 is an option. Preferably, the axial displacement after a full rotation - the pitch - is equal to or less than the "W" width of the track. Preferably, the pitch is a fraction of the width "W", eg W/2, W/3, ... or, in general, W/Q (Q is a positive rational number). Therefore, the abrasive layer will be formed by at least "Q" layers, the first of which 206 is brought into contact with the metal tube throughout the layer, while the subsequent layers 208, 210, 212, 214, 216 .. will only have a maximum of 1/Q of their track width in contact with the metallic substrate, while the remaining part (Q - 1)/Q is at the top of an already formed track (the "overlay") . Increased overlap has beneficial effects on the distribution of abrasive particles in the abrasive layer (the "particle distribution problem"). Figure 10b shows a schematic cross section of this tape with tracks 1004, 1004', ..., 1004V axially displaced by W/3 or Q is 3.
    [00035] Another procedural procedure is when the optional translational move is done in a stepped move. First, the track is covered in a few turns of the tube, without relative axial movement, until enough material has accumulated in the starting section of the tape. Then, the laser cannon is moved axially through several gaps, each of said gaps covering a predefined length, at a predefined speed. Finally, the movement of the laser cannon is stopped again and some overlapping spins are made at the end of the ribbon. In this way, the abrasive layer mass can be spread at will over the length of the tape. An example of this is shown in Figure 10c, in which the different tracks are offset by a track width W from each other. Two layers (eg 1004, 1004') are top deposited against each other.
    [00036] Preferably, the time to form the abrasive layer is limited to less than about 10 seconds, or less than 5 seconds or even less than 3 seconds. However, it will take at least 0.5 second to produce a single abrasive layer of dimensions currently in use. The relative tube rotation speed must be such that at least a circumferential tube speed "vt" of 5 mm/second is achieved. This corresponds to a turn in about 4 seconds on a 6mm outside diameter tube. Particularly, a rotational speed is imagined to be greater, for example, than 1 revolution in 2 seconds, or more than 2, 3, 4, 5...revolutions in 2 seconds of laser coating time. This corresponds to circumferential tube velocities of at least 9, 18, 28, 37...mm/second. Increasing the number of turns per second has a beneficial effect on the tube's thermal load. On the other hand, the circumferential velocity of the tube can be so high that afterwards the molten metal deposit that forms is pulled out of the sleeve due to centrifugal forces. This occurs when circumferential speeds greater than 500mm/second are applied to a 6mm OD sleeve. For smaller gloves, this circumferential speed needs to be lower to avoid tearing. For example, on a 4mm OD sleeve, the "vt" should stay below 410mm/second.
    [00037] After the tape is formed, that is, when a thickness of about 1 to 3 mm, over the total axial length of about 3 to 15 mm of the abrasive layer, is reached, the tube coating is interrupted, and , in this way, the formed tape is allowed to cool down (Figure 2d).
    [00038] In an alternative embodiment, the interruption of the tube coating is done in stages, that is, first the interruption of the abrasive particle feed, while continuing the flow of metallic matrix material for at least one rotation of the tube, before let the tape cool down. As an option, the laser beam can be "on" or "off" during this at least one tube rotation. In any situation (laser beam "on" or "off"), a final coverage is established on the abrasive particles to better fix them. When the laser beam is "off", the still hot tape is cooled faster. The resulting tape shows abrasive particles that protrude from the tape surface but are retained with a thin layer of metallic matrix material to retain the particles. This tape has the particular advantage that there is no need for any "treatment" of the tape, thereby solving the "handling problem".
    [00039] To overcome the "geometry problem", the inventors placed on one side a forming piece 304, over the end of the tube, thereby forming a rectangular circumferential corner, against which the abrasive layer was accumulated. . After removal of the forming piece, a suitable sharp edge of the tape can be obtained. When placing this forming piece 304, 306 at both ends of the tube, both ends of the abrasive layer of the tape are flat. These forming pieces 304, 306 are present during the formation of the abrasive layer.
    [00040] The forming pieces 304, 306 can be in the form of a ring, or particularly a segmented ring (with two or more segments), which can be opened to a diameter of at least the diameter of the finished tape, and by tight closure it fits into the tube. Forming pieces can be molded, for example, to impinge one or more protrusions, or one or more recesses, on one or both sides of the abrasive layer.
    [00041] In addition to, or alternatively to, forming pieces 304, 306, at one or both ends, after stopping the laser coating, but before complete cooling of the ribbon, the still soft ribbon can be molded by calibrating it in a mold. This mold can take the form of two halves, which generate the final shape of the ribbon, after being closed. Possibly, the tube can be rotated while the tape is held in the mold, to improve the rotating symmetry of the tape.
    [00042] In addition to, or alternatively to, providing the forming pieces 304, 306 at one or both ends of the tube, the tape can also be molded by pushing a rotating mold 308, for example, a roller against the tape, after stopping said laser coating, but before complete cooling of the ribbon. Rotating mold 308 must be held against the tape and rolled through it to at least an integral perimeter of the tape.
    [00043] By providing the rotating mold 308' and/or said forming parts 304, 306 with a structured model, the negative of this model can be placed on the sides (in case the forming parts are molded) or on the external surface (in the the case of a rotating molded mold 308') of the abrasive layer of the tape.
    [00044] The fixation of the rings and/or the mold is a problem that occurs. To prevent this, the inventors have found that it is best to produce the mold parts in a shiny metallic material, such as, for example, brass or another polished copper (copper - beryllium) based alloy. The high reflectance of these parts prevents them from being heated by the laser beam.
    [00045] In another preferred embodiment of the process, the substrate tube is retained at one end, for example a lathe plate 202, the abrasive coating 220 is laser coated on the tube 204, according to any of the processes described above . The tape thus formed is cut by means of a chisel or saw 218. The tube 204 is advanced progressively by the vise plate 202, under the laser coating apparatus, and the cycle is repeated. In this way the tapes can be made so that they can be threaded into a steel cord in the known manner.
    [00046] Alternatively, the lathe plate 202 can assume the role of a forming piece 304. Then, the laser coating starts against the lathe plate, and, after the tape is formed, the tube is advanced by at least the tape length. Then the tape is cut using a chisel or a saw. A new piece of tube is already present to start a new cycle. Optionally, a second forming piece 306 can be closed around the free end of the tube to form both sides of the tape. After finishing the tape, the forming piece 306 should preferably open enough to allow the tape to pass through.
    [00047] Alternatively, a series of abrasive layers can be deposited on the tube, gradually staggering the tube each time the abrasive layer width is coated. Then the tube can be cut into individual ribbons.
    [00048] It appears to be very beneficial to cool the tube to prevent excessive thermal load on the tube. This can be done in several ways: - a fluid can be passed through the tube while it is being rotated; a fluid can be a gas or a liquid; examples are nitrogen or water; flow rate can be adjusted; gases have the advantage that they do not have to be collected but need a higher flow rate than liquids; and - a solid can be moved through the tube, which absorbs some of the heat.
    [00049] A particularly convenient way to perform the cooling is by moving the steel cord - this will act as the conveyor cord for the tapes - through the tube; in this way, the tapes are produced while in the cord, thereby eliminating the step of having to thread the tapes into the steel cord afterwards. The steel cord can also be moved back and forth so that the temperature of the steel cord does not increase too much. The lower the temperature of the steel cord, the better it is: heat transfer is improved (a greater temperature difference is beneficial for cooling) and damage to the cord is minimized.
    [00050] The tubes can be compressed and connected around the steel cord in an earlier step, as described in patent application PCT/EP2010/067527 (in particular, paragraphs [016] to [018], before coating them by laser coating.
    [00051] Although laser coating with metallic matrices containing abrasive particles is known, this process is only practical on bulky metallic substrates, such as drill holes, saw blades, grinding blades, tubes and the like. It seems to be a convention in the field that these bulky substrates are needed to be able to drain heat from the coating process in the laser coating process. As the mass of the tubular sleeve is very small, the cooling rate "dT/dt" together with the circumferential velocity "vt" will determine whether or not the sleeve will survive the coating process. In comparison to this, a sufficient amount of heat is needed to form a metallurgical bonding layer 207 between the sleeve and the abrasive layers 206 and to consolidate the subsequent layers 208, 210... with each other. These requirements are contradictory but in harmony with the process described above, thereby solving the "heating problem". The inventors fully verify that the described coating process can be used for the production of saw bands, in which the mass of the abrasive layer is greater than the mass of the metal tube or rod covered by said abrasive layer. Only the mass of the radial tube under the abrasive layer must be considered. The mass of the covered tube can be less than 1 gram.
    [00052] Or even more serious: that the wall thickness of the metal tube is less than the thickness of the abrasive layer. Naturally, the thickness of the unused tape will be considered - during use - as the major part of the abrasive layer that will be worn away. MATERIAL SELECTION SECTION
    [00053] Preferably, the metallic tube, which is used as a substrate, is produced from a metal or metallic alloy, having a higher melting point than that of the metallic matrix material. Particularly similar materials are plain carbon steel or stainless steel. A steel with low to medium carbon content, i.e. a steel with a carbon content between 0.04% by weight and 0.80% by weight of carbon, is preferred. The substrate can be supplied in the form of a long tube. Or the substrate can be supplied in the form of short sleeves, which have been formed and connected around the carrier steel cord, as described in the applicant's patent application PCT/EP2010/067527 (particularly paragraphs [0016] to [0018 ] The gloves then show a connection. The metal tube wall thickness is less than 1 mm, even thinner than 0.7 mm, while successful tests were conducted by the inventors on the gloves, with a wall thickness 0.3 mm. The inventors believe that a wall thickness of 0.2 mm or even 0.1 mm is feasible. The gloves are preferably provided with an internal notch, such as a thread, to provide better grip with the polymer covering the steel cord. The "wall thickness" of the sleeves is therefore understood to include the inner spikes of the thread. Additionally, the sleeve may have a variable wall thickness - eg thinner at the ends, thicker in the middle part - for better polymer penetration.
    [00054] There are many known alloys of metallic matrix materials, which are suitable for use with a laser coating system. Because of the restrictions imposed by abrasive particles, alloys with melting temperatures between 400°C and 900°C are particularly preferred. These alloys comprise silver, copper, nickel or cobalt as the main alloying element. Additionally, melting temperature reducing elements such as tin, zinc or even indium can be added. In the case of nickel, non-metals such as phosphorus, silicon or boron can be used to reduce the melting temperature.
    [00055] Brass (copper and zinc as the main elements) and bronzes (copper and tin as the main elements) are considered as special, particularly the latter. Other preferred alloys are those based on silver, such as Ag - Cu, Ag - Cu - Zn or Ag - Cu - In. Also preferred are nickel based alloys such as Ni - Cr - P, Ni - Cr - Fe - Si - B or Ni - Cr - Si - Mn. These alloys have a good balance between abrasive wear and die wear. If the die is worn out too quickly, the abrasive particles will be displaced while not being fully used, causing premature tool wear. Conversely, if the die is too wear resistant, the abrasive particles will not protrude sufficiently for cutting, resulting in very low saw cutting speeds.
    [00056] Special alloys contain an additional active metal, such as chromium, titanium, vanadium, tungsten, zirconium, niobium, molybdenum, tantalum, hafnium or their combinations. Specialty are chrome, zirconium, vanadium or titanium, the latter of which is particularly preferred as it has the lowest melting point. These metals are active in two ways: - they are known to improve the wetting of abrasive particles during deposition; and - are carbide formers, which work well in combination with carbon-containing abrasives (see below).
    [00057] Bronzes are special, which contain between 5 and 30% by weight of Sn, between 0.5 and 15% by weight of Ti, the remainder being copper. Best results have been obtained with bronzes having between 10 and 20% by weight of Sn and between 2 and 10% by weight of Ti, the remainder being copper. An example is an alloy containing 14% Sn, 8% Ti, the rest being copper, all expressed as a percentage by weight of the total.
    [00058] Possible abrasive particles are diamond, cubic boron nitride, silicon carbide, aluminum oxide, silicon nitride, tungsten carbide, titanium carbide or their mixtures. Carbon-containing particles - diamond, silicon carbide, tungsten carbide, titanium carbide or their mixtures - are special in that they are easily wettable by all the active metals mentioned. Nitrides (ie, cubic boron nitride, silicon nitride) are best wetted with titanium. Diamond (ie almost pure carbon), synthetic or natural is special, the former being preferred for its lower cost.
    [00059] As an alternative to adding an active metal in the metal matrix material, the active metal can also be provided on the surface of the abrasives, for example, in the case of diamond. Diamond particles coated with a coating containing tungsten, chromium or titanium are available.
    [00060] When no active metal is present in the metal matrix material or abrasive particles, the abrasive particles will not easily wet the molten metal. This even causes "backward bounce" of abrasive particles in the meniscus of the molten metal deposit when they are colliding with the metal deposit.
    [00061] In general, particles with a size between 100 µm and 600 µm can be used in the process. The stone cutting particles are preferably coarse grained, i.e. with a wide range of grain sizes, based on US mesh, 30/40, 40/50 or 50/60 (Mesh sizes are according to US ASTME 11 standard, the higher the numbers, the smaller the particles). Especially saw bands in the size of 40/50 mesh. A 40-mesh sieve has 420 µm square openings on one side, through which the smallest sized particles pass. Part of these smaller particles will be retained by the 50 mesh sieve, with 297 µm square side openings. The average size of the remaining particles is about 427 µm in the grain size indication system according to FEPA (Federation of European Abrasive Producers), which assigns an average size for each mesh size.
    [00062] The density of abrasives is generally lower than the density of metallic matrix materials, are favored: for example, bronzes generally have a density of 8 to 9 g/cm3, while diamond has only a density of 3, 5 g/cm3. As the abrasive particles are relatively large, their greater buoyancy force is not hindered by the viscous flow of the particles that will flow towards the surface of the molten metal deposit. When the particle size is less than about 100 µm, the viscosity of the molten metal will prevent them from floating towards the surface, so the diamond distribution is frozen "in place". It is therefore a problem to have larger abrasive particles evenly distributed over the mass of the material: "the particle distribution problem". The inventors solved this problem by deposition of several superimposed top layers between them, whereby the average thickness of each layer is between 0.1 to 5 times or 0.5 to 3 times or 1 to 3 times the average particle size abrasives. On each track, the diamond tends to float, but the metal alloy freezes fast enough that the track solidifies before the next track is deposited on top. This results in an even distribution of particles in the radial direction. TAPE CHARACTERIZATION SECTION
    [00063] According to a second aspect of the invention, the tape resulting from the process described above is claimed. The tape has a tubular metallic sleeve surrounded by an abrasive layer, which comprises abrasive particles embedded in a metallic matrix material. The characteristic around the tape is that it has a dendritic microstructure in a metallographic cross section.
    [00064] The tapes made by the inventive process mentioned above show a distinct metallography compared to the tapes obtained by known sintering processing (see paragraph [6]). The layers deposited by means of laser coating can present different metallographic structures, depending on the metallic matrix material, temperature gradient at the liquid-solid interface and solidification speed. For example, a low solidification rate and a high temperature gradient can result in a flat structure, with uniform alloying of the metallic elements. Decreasing the temperature gradient, at the same rate of solidification, can result in a type of cell structure, in which one phase is retained in cells of another phase, which have a lower melting point.
    [00065] The preferred structure according to the inventors, for use in a saw band, is a dendritic ("tree-shaped") metallographic structure, which is obtained with high but not so high cooling rates, and a minimum circumferential speed. Under minimal laser coating conditions, the metal alloy components in the metal deposit do not have the opportunity to reach thermal equilibrium. Due to the presence of a high spatial temperature gradient, the growing solid phase will seek a more effective way of ejecting the superfluous solute components into the liquid ahead to satisfy the solid's preferred intermetallic phase. This ejection proved more effective if the solid grew in the shape of a tree, as most of the surface is then available to expel the solute. The trunk and branches of the tree will therefore be formed by an intermetallic phase with a high solidification temperature, while the interdendritic phase will be a component or an intermediate phase with a lower solidification point. By increasing the solidification speed, which is proportional to the circumferential speed "vt", the microstructure can be refined. The fineness of the microstructure is also considered to contribute to the hardness and wear resistance of laser coating layers: the thinner the structure, the higher the wear resistance. See "Laser Cladding" by E. Toyserkani, A. Khajepour and S. Corbin, Chapter 6, 2005, CRC Press, ISBN 0-8493-2172-7.
    [00066] The fineness of the microstructure is specifically important for saw tape, as the metal matrix material must wear according to the wear of the diamonds. The use of cellular or all-alloy type microstructure materials obtained by laser coating will result in too soft metallic matrices, which are not suitable for the intended purpose. The fineness of the structure can be, for example, quantified by measuring the largest aspect of the dendritic structure, such as the "branch" of the tree in various frames taken from a metallographic cross section. Starting with a small magnification (10X), the largest structure is identified. The magnification is intensified so that the beginning and end of the branch are visible in a frame. The branch should be uninterruptedly visible in a single view. The end-to-end distance can be measured by suitable imaging software. Preferably, the maximum twig length, obtained in ten different frames, is below 300 µm, otherwise the structure is too soft. In particular, these branches are shorter than 200 or 100 µm, or even shorter than 50 µm. Typically, branches can be seen up to a length of about 5 to 10 µm. If the maximum branch length found is below 1 µm, the structure is no longer considered dendritic for the purpose of this patent application.
    [00067] The metallic matrix material is selected according to the selections as specified in paragraphs [53] to [56].
    [00068] Another advantage of using the laser coating technique is that a metallurgical bonding layer 207 forms between the metallic glove and the abrasive layer. This eliminates the need to weld the abrasive layer onto the tube. The inventors found that it was perfectly possible to obtain a good bond with the considered coating alloys: there is no need to first coat the substrate with an adhesion layer, of a composition different from that of the abrasive layer. Therefore, the alloy that forms in the metallurgical bonding layer 207, between the tubular metallic sleeve and the abrasive layer, consists only of the metallic components of the glove and the metallic components of the abrasive layer.
    [00069] The adhesion of the abrasive layer can be tested by shearing the abrasive layer of the glove, in an axial tension test. The shear force required to pull the abrasive layer from the glove, when related to the common area between the abrasive layer and the glove, should be at least 30 N/mm2, or preferably greater than 50 N/mm2. Release forces between 70 and 100 N/mm2 were achieved.
    [00070] Advantageously, some of the abrasive particles can - at most - penetrate the metallurgical bonding layer. As abrasive particles are present even close to the glove or even in the glove, this allows the tapes to be used until the abrasive layer is almost completely spent on the glove. In prior art tapes, this is not possible due to the use of a solder between the sleeve and the abrasive layer, which occupies a part of the radial distance of the tape diameter.
    [00071] The bonding layer can be kept too thin. Preferably, the bonding layer is less than half or even a third of the wall thickness of the tubular sleeve. On an absolute scale, it is preferred that the bonding layer be thinner than 2000 μm or 150 μm, or thinner than 100 μm, although good results have been obtained with metallurgical bond layers thinner than 50 μm, as a thickness around 20 to 10 µm. Extremely thin bonding layers - thinner than 0.1 µm - will result in a reduced abrasive layer in glove holding force, and will result in premature tape failure.
    [00072] The preferred abrasive particles are those described in paragraphs [57] and [58], with the sizes mentioned in paragraphs [60] and [redicted image]. The amount of abrasive particles present in the abrasive layer depends on the material to be sawn by the tape and the type of abrasive particles. Generally, an amount of 10 to 2000 mg/cm3, considered in relation to the volume of the abrasive layer, is necessary. In particular, it is 10 to 1,000 mg/cm3. In the case of diamond, this is expressed in carats as 0.05 to 10 carats/cm3 (1 carat is equal to 200 mg), or even 0.05 to 5.0 carats/cm3. For diamond, this amounts to 0.28 to 57% or 0.38 to 28% by volume of the abrasive layer.
    [00073] Also, abrasive particle mixtures can be used. Particularly preferred blends are diamond with [tungsten carbide or silicon carbide] or cubic boron nitride with [tungsten carbide or silicon nitride].
    [00074] A particularly preferred embodiment of the saw band is one in which part of the abrasive particles is projected from the outer surface of the band. Preferably, the particles are retained in a retaining layer of metallic matrix material. Over-projecting particles cannot be sufficiently retained by the metal matrix retaining layer. When abrasive particles are buried too deep by the metal matrix retaining layer, they are not readily available for sawing. The retaining layer is preferably thinner than 0.5, or particularly thinner than 0.2 times the average size of the abrasive particles. Too thick a layer will not allow the abrasive particles to become fixed enough on first use. There is no minimum that the metallic matrix retaining layer, as part of the protruding edges or corners of the abrasive particles, may not be actually covered in any way, while the rest of the particle is covered. This saw band must not be treated before use.
    [00075] Preferably, the tape contains an active metal, to improve the bond between the abrasive particles and the metallic matrix material, as discussed in paragraph [55].
    [00076] The inventors have found that this active metal also helps to improve the distribution of diamonds across the ribbons. In fact, metallographic cross-sections (on any plane that crosses or contains the axis of the tubular metal sleeve, for example, a plane perpendicular to the axis) revealed the presence of very thin interface layers, which are rich in active metal. These interface layers are preferably thinner than 5 µm, particularly thinner than 2 µm. By "active metal rich" it is meant that the atomic abundance of the active metal in the interface layer is at least twice the total atomic abundance of the active metal in the total metal matrix material.
    [00077] These interface layers mark the different loops of the track, which are deposited on a previously deposited part of the track, during the laser coating process. How these interface layers are formed is not known. However, the inventors have observed that the abrasive particles are more present radially, just below the interface, and, on many occasions, one face of the abrasive particles is wetted by the reactive metal. Therefore, abrasive particles are present between the metallic bonding layer and the first interface layer, or between the first and second (if present) interface layers, and so on.
    [00078] It is therefore conjectured - without being bound in any way by this hypothesis - that the active metal helps to keep the abrasive particles in the metal deposit, and is preferably present on the outside of the deposit in fusion. This is not unreasonable, as active metals generally have a lower density than that of the other components of the molten metal deposit. After rapid solidification, the abrasive particles are held within the solidifying metal deposit, as if they were trapped by a crust. Therefore, the interface layers help to keep the abrasive particles in place and prevent them from floating. In this way, the "particle distribution problem", known when depositing laser coating layers with relatively large abrasive particles, is overcome. The average distance - measured by at least 12 radii not passing through an abrasive particle - between the metallurgical bond layer and the first interface layer or between the interface layers themselves - is preferably between 0.1 to 5 times or 0.5 or 1 to 3 times the average size of abrasive particles.
    [00079] When, during track deposition, there is a relative axial movement between the laser coating system and the tube, the track will present a substantially helical in itself, if the pitch, after one revolution, is less than the width of the trail. On the tape, what is left of this process is visible in the inclination of the interface layers, in relation to the axis of the tape. All interface layers are slanted substantially in the same direction. The interface layers form a conical helix. Of course, the interfaces are not smooth, but this general slant is present and traceable.
    [00080] If abrasive particles are used which are precoated with an active metal coating, this active metal coating remains discernible on the abrasive particle in the tape. As these active metals show a high affinity to one or more elements of the abrasive particle (see paragraph [58]), this greatly improves the adhesion of the abrasive particle to the metallic matrix material.
    [00081] According to a third aspect of the invention, a saw cord 400 (Figure 4) is claimed, which comprises a steel cord 408 d at least one tape 404, as described above, or obtained by the tape production process described above. Saw cord 400 further comprises a polymeric jacket 402 to hold the strips 404 in place. This cord can be produced in the conventional manner or in the manner as described in patent application PCT/EP2010/067527.
    [00082] When produced according to the last of the processes described, at least one band of the saw cord will have a tubular metal sleeve, with the feature that at least one connection, for closing the sleeve around the steel cord, is present in the glove, in addition to all claimed characteristics.
    [00083] According to a fourth aspect of the invention, the use of the tapes, as described above, and the use of the tapes, as produced according to the processes mentioned above, in a saw cord are claimed.
    [00084] A particularly preferred mode of use of the tapes is when the tape 404 is, during use on the saw cord, driven in the direction 406, as indicated by the slope of the interface layers. Simply put: the slanted interface layers form an arrow indicating how the tape should preferably be used. This direction is particularly preferred as the interface layers are not impacted by entry into workpiece 410, which is sawn off. BRIEF DESCRIPTION OF THE DRAWING FIGURES
    [00085] Figure 1 shows an operating principle of a laser coating system.
    [00086] Figures 2a to 2e show the various aspects in the process for producing the tape.
    [00087] Figures 3a to 3d show several alternative embodiments of the process for producing the tape.
    [00088] Figure 4 explains how tape is best used in practice.
    [00089] Figures 5a and 5b show a metallographic cross section, in two different magnifications, of a tape produced by the process described.
    [00090] Figure 6 shows a scanning electron microscope detail of the tape produced by the process.
    [00091] Figure 7 shows a cross section of the abrasive layer of the tape, indicating the various characteristics of interest.
    [00092] Figure 8 is a schematic cross section of a saw band, produced by the laser coating process.
    [00093] Figures 9a and 9b are individual images of a microcomputer tomography scan of the tape.
    [00094] Figures 10a, 10b and 10c show different arrangements of the layers in the tape. WAY(S) TO CONDUCT THE INVENTION
    [00095] In the following only the preferred mode for the practice of the invention will be described, as several experiments had to be done before reaching these conditions.
    [00096] In a series of tests, the following type of equipment was used: - laser coating system; - "Laserline LDF 3 kW" diode laser operating at 1,300 W in continuous mode at a wavelength of 1,030 μm; - "Balliu" laser cannon made by Laserline GmbH with coaxial powder feed; - Medicoat Duo powder feeder; and - gas source: argon.
    [00097] Both the metallic matrix material and the abrasive particles were fed by the same gaseous stream of argon. The laser cannon was used in a vertical position, with the laser beam and associated gas flow in the downward direction. - The laser coating system can be moved in the axial direction of the lathe at a speed of 3.2 mm/s. The feed rate of the particles was kept constant in all subsequent experiments, resulting in a constant material flow "Φm".
    [00098] As a substrate, a glove with a welded connection, made of low carbon steel (0.067% by weight of C), with an inner diameter of 3.8 mm and an outer diameter of 4.95 mm, was used (wall thickness 0.575 mm) with a length of 10 mm. The substrate was retained between the polished brass forming pieces. Through the sleeve, a 19+6x7 galvanized steel cord with a diameter of 3.75 mm was inserted and slowly moved through it, during laser coating.
    [00099] As the materials, the following were used: - metallic matrix material: bronze powder with a nominal composition of Sn - 14% by weight, Ti - 8% by weight, the remainder being Cu (and unavoidable impurities) . Powder size was less than 75 µm; and - 40/50 mesh synthetic diamond particles with an average measured size of 415 µm.
    [000100] First, the lathe was put into operation to make the sleeve rotate at about 0.25 seconds for a full rotation ("T" rotation period), which results in a threshing speed of 6.3 mm/ s. The laser focus, with a 3.8mm spot size, was adjusted to about 7mm above the glove surface. The material stream was thus heated up already before coming into contact with the glove.
    [000101] The matrix material powder feed was set to 65%, with a gas flow of 4 liters/min, the abrasive particle feed was set to 25%, with a gas flow of 5 liters/min. After ignition of the laser, a deposit of molten metal formed and diamond particles were injected into the molten metal, as seen with a high-speed camera. No ejection of diamond particles out of the molten metal deposit occurred. The width of the formed track was 4.0 mm.
    [000102] The axial movement between the tube and the laser cannon was as follows:

    [000103] After stopping with the laser coating system, the surface was smoothed by pushing a brass roller against the still hot material while being rotated. This greatly improved the ribbon geometry.
    [000104] After final cooling, the mandrel was opened and the ribbon thus formed was formed on the carrier steel cord. Thermal damage to the steel cord became acceptable. The tape could still be moved on the steel cord. Several tapes were produced according to this procedure, which made it suitable for automation.
    [000105] The total thickness of the abrasive layer on the tape thus formed was 1.53 mm (i.e., 2.7 times the wall thickness of the glove), resulting in a tape with an outer diameter of 8.0 mm and with an axial length of the abrasive layer of 6 mm. The total mass of the tape was 1.7 grams, with the glove contributing 0.64 grams. As only 6mm of the total 10mm length of the sleeve is covered, the "mass of the tube covered by the abrasive layer" is 0.38 grams. The abrasive layer has a mass of 1.06 grams, which is 2.79 times the mass of the tube's mass covered by the abrasive layer. The ribbons had a diamond concentration between 1.86 and 2.00 carats/cm3 (mass per volume).
    [000106] In a metallographic cross section, the tapes obtained by laser coating presented a distinct metallurgical structure, compared to what is known of tapes obtained by sintering. This structure is shown in Figures 5a and 5b, which are polished cross sections of a tape cut in a plane comprising the axis of the plane. As the chemical etching solution, the following can be used: - 10 ml of 40% hydrofluoric acid, 5 ml of 65% nitric acid in 85 ml of H2O; and - 10 g of sodium hydroxide, 5 ml of 30% hydrogen peroxide in 100 ml of H2O.
    [000107] Figure 5a shows a photograph of the chemically attacked surface at a magnification of 100X. The "200 μm" bar marks the true size of the features. The lower background of the photo corresponds to the substrate. Dendritic structures are visible throughout the image. An example of a dendritic structure (very fern-like) is indicated by 502. A trunk is discernible with different branches perpendicular to it on the sides. The longest discernible throne is about 200 µm end to end. In addition, interface layers are visible, of which the 508 is an example. Another interface layer is visible in the top right corner of the photo.
    [000108] Figure 5b is a 1000X magnification of the same cross section as indicated by the "20 μm" bar, which shows the true length of the features. Again, an interface layer 510 remains visible. The tree-shaped structure resolves into white colored trunks, branches and leaves, between which a different, darker interdendritic phase is visible. The structure, therefore, shows a similar uniform structure of at least two of these increases.
    [000109] Figure 6 shows a scanning electron microscope (SEM) image at the magnification indicated by the "90 μm" bar. A 602 diamond particle is clearly visible. Matrix material 604 again shows the typical dendritic structure. An interface layer 608 extends diagonally across the image and touches the diamond surface at 610. Energy dispersive X-ray (EDX) analysis reveals that the interface layer is rich in titanium, with more than twice the mass concentration of titanium (in percent by mass). When the interface layer touches the diamond (at 610), the EDX spectra reveal the formation of titanium carbide.
    [000110] Figure 7 also shows an SEM image of an axial cross section. Again, different interface layers 706, 708 and a 702 diamond particle are discernible. It is an example of the observation that diamond particles tend to be present radially just below the interface layers. It is as if the diamonds are held in position by the interface layer. Therefore, diamonds are present between the interface layers. The numbers 245.35, 394.70, 346.71 and 320.28 µm are the thicknesses of the different layers formed in matrix material 704. Note that the 394.70 µm thickness of the layer is between 0.5 and 3 times the size of the 702 diamond it retains . More significantly, the image shows the metallurgical bond layer 710 with a thickness of 20 to 30 µm. EDX reveals that the metallurgical bonding layer is a mixture of the metallic elements present in the glove and the metallic matrix material.
    [000111] Axial stress tests, in which the abrasive layer is held in a U-clamp (no radial pressure) and the sleeve is pulled by means of a screw, presented forces of 8,357 N and 10,359 N, before the sleeve be busy. The comparative test on prior art tapes showed values from 5 to 12 kN. In relation to the common surface area between the glove and the abrasive layer, this is a shear force of 89 N/mm2 and 110 N/mm2, respectively.
    [000112] Figure 8 shows a schematic cross section of one of the produced tapes. 802 diamonds protrude from the surface in the immediate vicinity of the diamond. Diamonds protruding from surface 802 are buried more than 0.5 times their size in the metallic matrix material, considered in relation to their surrounding surroundings. Diamonds are partially or completely covered by a retaining layer 820 of metallic matrix material. Protruding diamonds make the need for a treatment step superfluous. Furthermore, the metallurgical bonding layer 810, which bonds the abrasive layer 804 to the sleeve 810, is indicated. Diamonds are present between the 808 interface layers, and the thickness of the layers between said interface layers is between half and twice the average size of diamonds.
    [000113] Figure 9A shows a cross section of a tape with a plane perpendicular to the axis of the tape, as obtained by a microcomputer tomography (μCT) scan. The image clearly reveals the geometric roundness of the ribbon, and the even radial distribution of the diamonds across the abrasive layer. This is significant in that although diamonds are always 400 to 500 microns in size, they do not seem to suffer from the buoyancy force, which tends to push them to the surface. The inventors hypothetically attribute this to stratified deposition of the abrasive layer, possibly in combination with the fact that the active metal interfacial layers prevent the diamonds from floating, thereby trapping the diamond in this layer. In this way, the "particle distribution problem" is solved.
    [000114] Figure 9b is another image of a cross section of the tape, which shows that diamonds are present below the metallurgical bond layer. It seems to be a trend for diamonds to be layered, which can be attributed to different layers of deposition.
    [000115] Some tapes were subjected to a single tape cutting test as described in "Progress in the knowledge of granite cutting with diamond wire" by A. Bortolussi, A. Caranassios, R. Ciccu, R. Lassandro, PP Manca and G. Massacci in "Proceedings of the 11th International Conference on Ground Control in Mining," University of Wollongong, July 1992. In this essay, a single tape is pushed against the outside of a rotating stone disk (a disk of granite with a diameter of 30 cm and a width of 3 cm) with a normal force of 5 N. The peripheral velocity is adjustable between 20 and 30 m/s. The tape is also rotated around its own axis, with approximately one rotation per second. Water was injected between the tape and the stone, like a soda. Tape wear was measured as a function of sawed area. Sawing was continued until the tape was worn into the sleeve.
    [000116] The results presented below were obtained on commercially available tapes:

    (*) the tape was treated before starting the test.
    权利要求:
    Claims (14)
    [0001]
    1. Process for producing a tape for use with a saw cord comprising the steps of: - retaining a metal tube in at least one of its ends; - starting to coat said tube by means of a laser coating system, in which: a source of metallic matrix material is melted by a laser beam in said tube; and a source of abrasive particles is thrown into the deposit of molten metal matrix material; - forming a track in said tube by relative movement of said laser coating system on said tube, in a rotational and optionally translational motion, said track accumulating an abrasive layer on said tube; - interrupt the coating of said tube; - allowing the tape thus formed to be cooled; characterized in that said abrasive layer of said formed tape has a mass which is greater than the mass of said tube covered by said abrasive layer and the circumferential velocity of the tube relative to said laser coating system is between 5 and 500 mm per second.
    [0002]
    2. Process according to claim 1, characterized in that said tube has a wall thickness less than the thickness of said abrasive layer.
    [0003]
    3. Process according to claim 1 or 2, characterized in that said source of abrasive particles and said source of metallic matrix material are such that the average thickness of the formed path is between 0.1 and 5 times the average size of said abrasive particles.
    [0004]
    4. Process according to any one of claims 1 to 3, characterized in that said track also has a track width, said optional translation movement, after a complete rotation, being equal to or less than said track width .
    [0005]
    5. Process according to any one of claims 1 to 4, characterized in that said source of metallic matrix material is by means of transporting powdered metallic matrix material in a gas carrier stream, wherein said powder of metallic matrix material is heated by said laser beam, before impinging on said metallic tube.
    [0006]
    6. Process according to any one of claims 1 to 5, characterized in that said step of interrupting the coating of said tube is done first by interrupting said source of abrasive particles, optionally followed by deactivating said laser beam , while the source of metallic matrix material is continued for at least one rotation of said tube.
    [0007]
    7. Process according to any one of claims 1 to 6, characterized in that said accumulation of said abrasive layer is delimited by one or two lateral formation pieces, retained at one or both ends of said tube.
    [0008]
    8. Process according to any one of claims 1 to 7, characterized in that it further comprises the step of: - molding the external surface of said abrasive layer by contacting said layer with a mold, after the interruption of said re- clothing, but before the cooling of said tape.
    [0009]
    9. Process according to claim 8, characterized in that said mold is pushed and rolled against said tape for at least the entire perimeter of said tape.
    [0010]
    10. Process according to any one of claims 7 to 9, characterized in that said mold and/or said forming parts are made of a material that reflects the light of said laser beam, to limit the heating said forming parts and/or said mold.
    [0011]
    11. Process according to any one of claims 7 to 10, characterized in that the surface of said mold and/or said forming parts, in contact with said abrasive layer, are molded to impose an external shape on said abrasive layer.
    [0012]
    12. Process according to any one of claims 1 to 11, characterized in that it is followed by the steps of: - cutting said tape from said tube; and - progressively advancing said tube by the length of a ribbon.
    [0013]
    13. Process according to any one of claims 1 to 12, characterized in that said tube is cooled by moving a solid and/or a fluid through it.
    [0014]
    14. Process according to claim 13, characterized in that said solid is a steel cord.
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    同族专利:
    公开号 | 公开日
    PT2680998T|2017-03-01|
    CN103442833B|2016-03-02|
    CN103442833A|2013-12-11|
    US20130333681A1|2013-12-19|
    KR102013462B1|2019-08-22|
    EP2680998A1|2014-01-08|
    KR20140060461A|2014-05-20|
    ES2618914T3|2017-06-22|
    BR112013022035A2|2016-11-29|
    ZA201305388B|2014-10-29|
    EP2680998B1|2016-12-28|
    PL2680998T3|2017-06-30|
    US9254527B2|2016-02-09|
    WO2012119947A1|2012-09-13|
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    法律状态:
    2018-12-18| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-12-24| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-01-19| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|
    2021-05-18| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-07-06| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 02/03/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP11156982|2011-03-04|
    EP11156982.8|2011-03-04|
    PCT/EP2012/053643|WO2012119947A1|2011-03-04|2012-03-02|Method to produce a sawing bead|
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