• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Laser nozzle comprising a nozzle body (1) comprising a first axial housing (3) passing axially through said body (1), an inlet orifice (9) for feeding said first axial housing (3) with assist gas (23) and a first outlet (4) located at a front face (1a) of the nozzle body (1), and a movable member (2) arranged in the first axial housing (3), said element mobile device comprising a front part (2a) forming a skirt and an axial passage (5) with a second outlet orifice (6) opening at said front part (2a). According to the invention, the nozzle body (1) is formed of at least a first part (11) arranged around the movable element (2) and a second part (12) coming to position, following the direction of flow of the assist gas (23) into the first axial housing (3) above said second portion (12), the nozzle body (1) further comprising first attachment means (7, 8) adapted to and adapted to secure the second portion (12) to the first portion (11). Focusing head and associated laser cutting facility. Laser beam cutting method implementing a nozzle according to the invention, a laser focusing head according to the invention or an installation according to the invention.
    公开号:FR3020774A1
    申请号:FR1454093
    申请日:2014-05-06
    公开日:2015-11-13
    发明作者:Philippe Lefebvre
    申请人:Air Liquide SA；LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude；
    IPC主号:
    专利说明:

    [0001] The invention relates to a laser nozzle that can be used in laser cutting with an internal moving element comprising a skirt for concentrating the gas in the cutting groove, the nozzle offering an improved industrial implementation and making it possible to preserve the focusing head of the effects. shocks that can undergo said nozzle. Laser beam cutting requires the use of a generally copper nozzle having the effect of channeling the gas and passing the laser beam. The nozzles typically have diameters of their outlet orifice of between 0.5 and 3 mm for a working distance of between 0.6 and 2 mm. In order to allow the cutting, it is necessary to use high pressures, generally several bar, in the focusing head to allow the gas to enter the groove to drive the molten metal. However, a large part of the gas used, typically between 50 and 90%, has no effect on the cutting process, that is to say on the expulsion of the molten metal, because it leaves on the sides of cutting bleeding. These losses of gas are in fact due to the enormous difference between the passage section of the nozzle orifice and the size of the focal task. Thus, as an indication, the passage section of a nozzle with an outlet orifice of diameter equal to 1.5 mm is 25 times greater than the section of the focal spot created by the laser beam passing through this nozzle. However, if an insufficient proportion of gas is used, then there is the appearance of cutting defects, in particular adhering burrs and / or oxidation traces.
    [0002] Attempting to remedy this by reducing the diameter of the orifice of the nozzle is not ideal because we take the risk of seeing the laser beam strike the inside of the nozzle and damage it, which also deteriorates the quality cutting and / or performance. There are also a number of documents proposing various solutions to try to promote the entry of gas into the kerf, for example EP-A-1669159, JP-A-62006790, JP-A-61037393, JP-A-63108992. JP-A-63040695 and US-A-4,031,351. However, none of these solutions is really ideal because often complex architecture to implement, operating incompatible with industrial use, and / or having limited effectiveness. Notably, US-A-4,031,351 discloses a laser cutting nozzle comprising a movable member whose end is pressed by a spring against the surface of the workpiece to promote the injection of the cutting gas into the groove.
    [0003] The major disadvantage of this solution lies in the fact that the force exerted by the spring in the direction of the sheet, accumulated at the pressure of the cutting gas, causes the movable member to exert a significant force on the sheet to be cut. It follows a risk of deformation, scratching or even driving the sheet, which is usually simply placed on the table of the industrial cutting machine. To remedy this, WO-A-2012/156608 proposes a laser nozzle with a movable element able to move axially in the nozzle body, under the effect of a gas pressure, and in the direction of the surface of the cutting sheet, until coming into contact with the sheet. The nozzle further comprises an elastic member exerting an elastic return force on the movable member in a direction tending to move away from the sheet. Thus, when the gas is cut, the movable member can be returned to its rest position and thus the skirt enter the interior of the nozzle body. However, this solution continues to pose some problems. Firstly, the design of this nozzle leaves little freedom to adapt its geometry to the different focus heads existing on the market, as well as different thicknesses to cut. However, the inventor of the present invention has shown that the cutting of fine thicknesses, typically less than 3 mm, required assistance gas ejection orifices of larger diameters than the maximum diameters accessible with the nozzle according to the invention. WO-2012/156608. Indeed, the maximum diameter of the axial housing machined in the nozzle body to accommodate the movable member is imposed by the diameter of the upper part of the nozzle to connect to the focusing head. As a result, the outlet orifice of the movable element can be widened only to a certain extent, typically up to 2 mm, which does not allow to obtain satisfactory cutting performance on thin thicknesses. In addition, the industrial laser cutting machines and the associated focusing heads implement, in a manner known per se, a capacitive distance sensor system for moving the head at a constant distance above the sheet. However, it turns out that current capacitive sensor systems can not detect a lateral obstacle extending above the surface of the sheet. Such an obstacle may result, for example, from already cut pieces that have remained wedged in the sheet and positioned at an angle to its surface. Cutouts started from a sheet edge can also generate steps or unevenness, that is to say differences in levels between different parts of the sheet, due to deformation or lowering of certain parts of the sheet occurring during cutting.
    [0004] This results in the risk of shocks at the nozzle body that can damage the nozzle and impair its operation, to cause its rupture or complete deterioration. The most problematic aspect is that a shock at the nozzle body can also damage the focusing head at its connection with the nozzle and cause a displacement of the head on its support, causing a misalignment of the beam laser. It is then necessary to intervene on the focusing head and proceed with its realignment, which affects the productivity of the cutting machine. The problem that arises is therefore to overcome all or some of the aforementioned drawbacks, in particular by proposing a laser nozzle whose design limits or even eliminates the risk of damage and / or misalignment of the focusing head in the event of an impact. nozzle level, and whose geometry can further adapt to a wider range of thicknesses to cut compared to existing solutions. The solution of the present invention is then a laser nozzle comprising a nozzle body comprising a first axial housing axially passing through said nozzle body, an inlet orifice for supplying said first axial housing with assist gas and a first orifice. outlet member located at a front face of said nozzle body, and - a movable member arranged in the first axial housing of the nozzle body, said movable member comprising a skirt front portion and an axial passage with a second outlet port. opening at said front skirt portion, characterized in that the nozzle body is formed of at least a first portion arranged around the movable member and a second portion being positioned, following the direction of flow of the assist gas in the first axial housing above said first portion, the nozzle body further comprising first fastening means adapted for and adapted to Set the second part on the first part. Depending on the case, the nozzle of the invention may comprise one or more of the following technical features: the first fastening means extend through at least a portion of the first and second parts of the nozzle body and in one direction generally parallel to the axis of the first axial housing. the second portion of the nozzle body comprises second attachment means adapted to and adapted to secure said second portion to a laser focusing head. the first and second fixing means are adapted to and designed to fix the second part of the nozzle body to the laser focusing head more securely than to the first part, so that, in the event of a shock at the the first part of the nozzle body, there is deformation or rupture of the nozzle body substantially between the first part of the nozzle body and the second part. the movable element is adapted to and designed to move in translation in the first axial housing towards the first outlet orifice until the front part projects outside said first axial housing through the first orifice; Release. - The movable element is able to move in translation in the first axial housing towards the first outlet port under the effect of a gas pressure applying in the first axial housing and acting on the movable member . the nozzle further comprises an elastic element arranged in the first axial housing, between the nozzle body and the movable element, the said elastic element exerting an elastic restoring force on the movable element tending to oppose the translational movement; in the first axial housing towards the first outlet. The nozzle comprises a separator sleeve arranged between the first part and the movable element, said separator sleeve comprising a second axial housing comprising a third outlet located at a front face of said separator sleeve, the movable element; being arranged in said second axial housing and said third outlet opening opening above said second outlet opening of the axial passage of the movable member when the front portion projects out of the first axial housing. the separator sleeve is formed of a material having a relative permittivity less than 8, preferably less than 6. the movable element is able to move between several positions comprising: a rest position in which the front part of the movable element is totally or almost totally retracted into the axial housing, and - a working position in which the skirt of the front part of the movable element is totally or almost totally protruded outside the axial housing through the first exit port. At least one sealing element is arranged between the nozzle body and the movable element, for example one or more O-rings. said at least one sealing element is arranged in a peripheral groove formed in the outer peripheral wall of the movable element. the axial passage of the movable element has a profile of conical, frustoconical or convergent / divergent shape. the nozzle body is advantageously made of an electrically conductive material, for example a metallic material, such as steel, bronze, refractory steel, copper, brass, or an electrically conductive ceramic material. alternatively, the nozzle body is made of an electrically insulating material, in particular an electrically insulating technical ceramic, for example of the type A1203, A1N, ZrO2 or Al2Ti05, a polymeric material, for example polyetheretherketone (Peek) or Vespel®, electrically insulating ceramic or pyrex. the mobile element is advantageously formed wholly or partly of an electrically conductive material, for example a metallic material, such as steel, bronze, refractory steel, copper, brass, or a material electrically conductive ceramic. Preferably, the movable member is formed of an electrically conductive material which induces limited friction on the sheet to limit wear of the sheet. alternatively, the movable element is made of an electrically insulating material, preferably resistant to temperature / heat, in particular an electrically insulating technical ceramic, for example of the type A1203, A1N, ZrO2 or Al2Ti05, a polymeric material, for example example of polyetheretherketone (Peek) or Vespel®, electrically insulating ceramic or pyrex. the separator sleeve is made of an electrically insulating material, in particular electrically insulating technical ceramic, for example of the type A1203, A1N, ZrO2 or Al2Ti05, a polymeric material, for example polyetheretherketone (Peek) or Vespel®, of electrically insulating ceramic or of pyrex. the separator sleeve is formed of a material chosen from: ceramic foams such as alumina foam or porous alumina, glass-ceramics, for example Macor®, or technical ceramics such as boron nitride, mullite , soapstone, cordierite. The invention also relates to a laser focusing head comprising at least one focusing optics, for example one or more lenses or mirrors, in particular a focusing lens and a collimating lens, characterized in that it also comprises a nozzle laser according to the invention. Furthermore, the invention also relates to a laser installation comprising a laser generator, a laser focusing head and a laser beam conveying device connected to said laser generator and to said laser focusing head, characterized in that the laser focusing head is according to the invention.
    [0005] Preferably, the laser generator or source is of the type CO2, YAG, with fibers or with disks, preferably with fibers or with disks, in particular a laser source with ytterbium fibers. According to yet another aspect, the invention also relates to a method of laser-beam cutting of a metal part, in which a nozzle according to the invention is implemented, a laser focusing head according to the invention or a installation according to the invention. The invention will now be better understood thanks to the following description given with reference to the appended figures in which: FIG. 1A schematizes a focusing head of a conventional laser cutting installation, FIG. 1B schematizes the size of the laser spot relative to the size of the nozzle orifice, - Figure 2 is a sectional diagram of the body of a nozzle according to one embodiment of the invention, without a movable element is arranged, - the Figure 3 is a sectional diagram of a nozzle according to one embodiment of the invention, and FIGS. 4A and 4B show the nozzle of the invention with the movable element in two different positions.
    [0006] FIG. 1A shows the focusing head 20 of a conventional laser cutting installation, to which is fixed a conventional laser nozzle 21 which is traversed by a focused laser beam and by assist gas (arrow 23) serving to expel the molten metal by the beam out of the cutting groove 31 formed by the beam 22 in the metal piece to cut 30, for example a steel sheet or stainless steel.
    [0007] The assist gas may be an active gas, such as oxygen, air, CO2, hydrogen, or an inert gas, such as argon, nitrogen, helium, or mixing several of these active and / or inert gases. The composition of the gas is chosen in particular according to the nature of the piece to be cut. The beam that impacts the part will melt the metal that will be expelled below the workpiece by the pressure of the assist gas. FIG. 1B makes it possible to clearly visualize the passage section 51 of the orifice 24 of the nozzle 21 with respect to the size S 2 of the focal spot of the beam 22. As can be seen, the section 51 is much larger than the size S 2 the focal task of the beam 22, which generates, with the conventional nozzles, a high consumption of assist gas which only a small proportion will be used to expel the molten metal out of the cutting groove 31.
    [0008] In order to considerably reduce the gas consumption and the pressure necessary for cutting, a laser nozzle has been proposed in WO-A-2012/156608 and capable of being designed to cut with a laser beam by implementing a flow rate. gas and / or gas pressure reduced by a particular nozzle architecture to force a larger proportion of gas to enter the groove 31 and expel effectively the molten metal. According to WO-A-2012/156608, the laser nozzle comprises a nozzle body 1 cooperating with a movable element 2 arranged and movably inside the body 1 of the nozzle. However, the construction of this laser nozzle is ideal for the reasons already mentioned. To remedy this, and as illustrated in Figures 2 and 3, the present invention provides a laser nozzle comprising a movable member 2 and a body 1 formed of at least a first portion 11 arranged around the movable member 2 and a second part 12 being positioned, following the direction of flow of the assist gas (arrow 23), above said first portion 11. The nozzle body 1 further comprises first fixing means 7, 8 adapted to and designed to attach the second portion 12 to the first portion 11. In fact, when assembling the nozzle, the movable member 2 is first arranged within the first portion 11. The second portion 12 comes then superimpose and attach to the first part 11 of the nozzle body 1. Thus, it is possible to maintain a second portion 12 whose geometry is adapted to the focusing head on which the nozzle body 1 must be attached, while increasing the volume available within the first portion 11 to accommodate the element 2. It is then possible to widen the axial passage 5 and the outlet orifice 6 of the movable element 2, the diameter of the outlet orifice 6 being typically up to 10 mm, preferably 6 mm . This makes it possible to widen the gaseous coverage of the cutting groove and to prevent the oxidation phenomena of the cutting faces that can occur at high cutting speeds achieved on thin sheet thicknesses, typically from 3 to 30 m / min for thicknesses less than 3 mm, especially when cutting stainless steel under nitrogen as an assist gas 23. In addition, the nozzle according to the invention allows to preserve the focusing head of the adverse effects caused by d ' possible obstacles on the sheet. Indeed, when an obstacle is on the surface of the sheet, it is essentially at the first portion 11 of the nozzle body 1, positioned immediately above the sheet that the shock occurs. The construction of the nozzle body 1 in several parts assembled, and no longer in one piece, provides a certain flexibility of displacement of the first part 11 with respect to the second part 12 and / or a possibility of breaking the connection between the first part 11 and the second part 12. This allows, in case of shock, to minimize the risk of displacement of the second portion 12 relative to the focusing head and / or the focusing head relative to its support.
    [0009] Advantageously, the body 1 of the nozzle is a part of revolution traversed right through by a first axial housing 3 of axis AA which extends from the rear face lb of the body 1 to the front face of said body 1. The first axial housing 3 opens at the two faces before the rear and lb of the body 1 nozzle. The rear face 1b carries an inlet port 9, while the front face the door a first outlet port 4 of the nozzle body 1, the first inlet and outlet ports 9 and 4 being coaxial axis AA. This first axial housing 3 is in fact a recess formed by a second portion 3b extending through the second portion 12 and a first portion 3a extending through the first portion 11. The first and second portions 3a, 3b, preferably of cylindrical shape, the first portion 3a comprising a first inner shoulder 19a projecting radially towards the center of the first housing 3, said first inner shoulder 19a being formed by a restriction of the section of the first axial housing 3 at the first outlet port 4. Preferably, the first inner shoulder 19a is arranged at the bottom of said first axial housing 3. The nozzle further comprises a movable element 2 which is inserted into the first housing 3 of the nozzle body 1, preferably, coaxially with the body 1, as visible in FIG. 3. The movable element 2 comprises a front part 2a forming a skirt of cylindrical, that is to say tubular, shape. and an axial passage 5 with a second outlet opening 6 opening at said front portion 2a forming a skirt. The axial passage 5 may have a conical internal profile, with a cylindrical or non-conical outlet channel, of the convergent / divergent type (i.e. Laval nozzle) or any other suitable geometry. Optionally, the nozzle comprises a separator sleeve 14 arranged between the first portion 11 and the movable member 2. The separator sleeve 14 comprises a second axial housing 15 comprising a third outlet orifice 16 located at a front face 14a of said sleeve separator 14, the movable element 2 being arranged in said second axial housing 15 and said third outlet opening 16 opening above said second outlet orifice 6 of the axial passage 5 of the movable element 2 when the front part 2a protrudes outside the first axial housing 3. The second axial housing 15 advantageously comprises a second inner shoulder 19b projecting radially towards the center of said second housing 15 and preferably located at the bottom of said second housing 15. The peripheral wall of the element Mobile 2 advantageously comprises a first stop 18 arranged at the outer surface. Preferably, the first stop 10 is of annular shape and extends over all or part of the periphery of the movable member 2. Depending on whether or not the nozzle comprises an intermediate sleeve 14, the first stop 18 is arranged opposite the first shoulder 19a of the nozzle body 1 or the second shoulder 19b of the sleeve 14. The first and second parts 11, 12 of the nozzle body 1 are advantageously formed of an electrically electrically conductive material such as a metallic material, for example steel, bronze, refractory steel, copper, brass, or electrically conductive ceramic material. The first and second parts may also be formed of an electrically insulating material, composite or not, such as a technical ceramic, a polymer, for example polyetheretherketone (Peek), Vespel®, or pyrex. Note that in the context of the present invention, the term "electrically insulating material, or dielectric material, a material that does not conduct electricity, that is to say that prohibits the passage of electrical current between two conductive elements electric. Conversely, an electrically conductive material contains many electric charge carriers that can move easily under the action of an electromagnetic field. The use of a conductive material for the first and second parts 11, 12 of the nozzle body 1 is advantageous because it allows the use of a capacitive sensor system. Indeed, in use condition, the nozzle body 1 is mounted at the end of a focusing head 20 comprising, in a manner known per se, a capacitive sensor system. This system uses the capacitive effect to detect small variations in distance between two conductive elements forming a capacitor. The distance separating the two conductive elements is determined by measuring the capacitance of this capacitor, which depends in particular on the dielectric permittivity of the medium which separates them. Traditional laser nozzles are generally formed of an electrically conductive material such as copper. When the nozzle is mounted at the end of the head, it is electrically connected to the capacitive sensor system. In this way, the capacitive sensor can measure the electrical capacitance between the sheet and the flat surface of the nozzle located opposite the sheet. The capacitive sensor is itself electrically connected to the movement commands of the focusing head 20 so as to adjust the height positioning of the head in the event of variations in the measured capacitance. Advantageously, when the laser nozzle according to the invention is assembled at the focusing head, the nozzle body 1 made of a material made of conducting material can be electrically connected to the capacitive sensor system fitted to the head. Advantageously, this electrical connection is made by contact of at least a portion of the second portion 12 of the body 1 with a part of the head 20 formed of an electrically conductive material and forming part of the capacitive sensor system. When the movable element 2 electrically conductive comes into contact with the sheet, it is at the same electrical potential as the latter. In order not to disturb the capacitive sensor, it is possible to use either a mobile element 2 made of electrically insulating material when said mobile element 2 is arranged directly within the body 1 of the nozzle, that is to say in contact with the body 1 , or a movable element 2 of electrically conductive material. The movable member 2 is preferably formed of an electrically conductive material.
    [0010] Indeed, the movable element is located in the immediate vicinity of the cutting zone and this type of material offers greater resistance to high temperatures and mechanical shocks (impacts of the movable element on the sheet) and / or thermal (ignition and extinction of the laser). For example, the movable member 2 may be formed of steel, hardened steel, carbon, a composite material ...
    [0011] Preferably, a conductive material will be chosen which induces a limited friction on the sheet to limit wear of the sheet, that is to say a material that is little or not abrasive. In the case where the nozzle body 1 and the mobile element 2 are made of a conductive material, the nozzle according to the invention comprises a separator sleeve 14 formed of an electrical insulating material so as not to fault the capacitive sensor.
    [0012] The capacitive sensor then measures one or more capacitance values between the front face 1a of the nozzle body 1 and the upper surface of the workpiece 30. From these values, the sensor makes it possible to adjust the distance between the cap and the sheet at a constant or quasi-constant value, typically between 0.1 and 5 mm, preferably between 0.5 and 2 mm, and to correct flatness defects of the sheet.
    [0013] In the context of the present invention, use is advantageously made of a separator sleeve 14 formed of a material having a low permittivity. Indeed, in the case of a conventional laser nozzle, i. e. without a moving element, the capacitance measurement takes place between two flat surfaces opposite one another, i. e. the front face of the nozzle body and the upper surface of the workpiece. In this case, the capacitance C is expressed (in pF / m) according to the following formula: C = EoEY X - d where co is the permittivity of the vacuum equal to 8.85 pF / m, sr is the relative permittivity of the material separating the front face of the nozzle body and the upper surface of the work piece, of a value of 1.004 for air, S is the nozzle surface facing the cutting sheet (expressed in m2 ), and d is the distance between the front face of the nozzle body and the upper surface of the workpiece (expressed in m). In the case of a moving element laser nozzle according to the invention, the capacitive sensor system actually performs two types of capacitance measurements. Before the movable element comes into contact with the upper surface of the sheet, the sensor makes a first measurement between two flat surfaces, i. e. the front face of the nozzle body and the upper surface of the workpiece. This measurement is the reference measurement for maintaining the nozzle body 1 at the desired height relative to the workpiece. Once the movable member 2 is in contact with the workpiece to perform the cutting operation itself, it is at the same potential as the workpiece.
    [0014] The sensor then performs, in addition to the first capacity measurement, a measurement of overall capacity resulting from a multitude of measurements taken between the outer surface of the movable element 2 and the inner surface of the first part 11 of the body. In fact, the distance between these surfaces varies according to the position considered along the axis AA of the nozzle.
    [0015] At a given point along the axis AA of the nozzle, the capacity C is expressed (in pF / m) according to the following formula: C = 27reoer x ri where r2 is the radius of the first axial housing 3, and r1 the radius of the movable element 2 at the considered point (see Figure 3), and 1 is the distance (expressed in m) along the axis AA on which the first axial housing 3 and the movable element 2 respectively have the r2 and r1 spokes, the inventor of the present invention has demonstrated that the use of a separator sleeve 14 formed of a material of low relative permittivity used to improve the stability of the capacitive sensor by reducing the disturbances due to to the measure of overall capacity, in addition to the first reference measure. It is thus possible to keep during cutting a positioning of the nozzle body 1 at a height very close, or even identical to the reference height before the beginning of cutting.
    [0016] By material with a low relative permittivity, is meant a material whose relative permittivity is less than 8, preferably less than 6. Advantageously, the thickness at any point of the peripheral wall of the separator sleeve 14 is at least 0 , 5 mm, preferably at least 1 mm, and advantageously between 0.5 and 10 mm, preferably between 1 and 3 mm. It is also advantageous to choose a material resistant to temperatures of the order of 100 to 2000 ° C, typically between 500 and 1500 ° C. According to a particular embodiment, the outer dimensions of the separator sleeve 14 are chosen so as to provide a space between the first part 11 of the nozzle body 1 and the mobile element 2. This air-filled space makes it possible to reduce even more the detrimental influence of the overall capacity measurement on the stability of the height positioning of the nozzle body 1. Preferably, the separator sleeve 14 is formed of a material chosen from: ceramic foams such as alumina foam or porous alumina, glass-ceramics, for example Macor®, or technical ceramics such as boron nitride , mullite, soapstone, cordierite. Table 1 below shows the ranges of relative permittivity values of the abovementioned materials, which may vary according to the grades of materials selected and the types of manufacturing processes used. Table 1 Type of ceramic Range of relative permittivity Porous alumina 1.7 - 1.9 Macor® 5.6 - 6.1 Boron nitride 4 - 5 Mullite 5.5 - 6.5 Steatite 5.7 - 6.2 Cordierite 4.8 - 5.2 As shown diagrammatically in Figures 2 and 3, the first means of fixing 7, 8 for fixing the second portion 12 on the first portion 11 of the nozzle body 1 advantageously extend through at least a portion of the first and second parts of the nozzle body 1 and in a direction generally parallel to the Axis AA of the first axial housing 3. Such an arrangement makes it possible to reduce the bulk of the nozzle body 1 and furthermore, in the event of a major shock to the first part 11, a sharp break between the first part 11 and the second part 11. Part 12. The first fastening means 7, 8 may allow a removable or irremovable attachment of the first 11 to the second portion 12 of the body 1 nozzle.
    [0017] According to a preferred embodiment of the invention, the first fastening means 7, 8 comprise at least a first threaded bore through at least partially the first and second parts 11, 12 of the nozzle body 1 and a threaded cylindrical piece (not illustrated) shaped to be screwed into said first threaded bore. Figures 2 and 3 illustrate an embodiment wherein the first attachment means 7, 8 comprise two diametrically opposed tapped holes. According to an alternative embodiment, the first attachment means 7, 8 comprise means for fixing the first part 11 to the second part 12 by clipping, bayonet or crimping.
    [0018] Preferably, the second portion 12 of the nozzle body 1 comprises second attachment means 10 adapted to and adapted to fix said second portion 12 to the laser focusing head 20. As illustrated in FIG. 3, the second portion 12 can thus comprise a tubular end portion, said end portion comprising a first thread 10 arranged on the outer surface of said end portion or a first thread 10 arranged on the inner surface of said end portion. The first thread or tapping 10 is shaped to be screwed respectively into a second thread or around a second thread of the laser focusing head 20 (not shown).
    [0019] Advantageously, the first 7, 8 and second fastening means 10 are adapted to and designed to fix the second part 12 of the nozzle body 1 to the laser focusing head 20 more securely than to the first part 11, so that that, in the event of an impact at the first part 11 of the nozzle body 1, there is a deformation or rupture of the nozzle body 1 substantially between the first portion 11 and the second portion 12 of the nozzle body 1. In this way, the risk of rupture or deformation at the level of the focusing head 20 is greatly minimized, which avoids lengthy maintenance operations at the level of the cutting installation. According to a particular embodiment, this control of the strength of the fastening of the second part 12 to the focusing head 20 with respect to the strength of the fixing of the second part 12 to the first part 11 can be obtained by sizing. threads, in terms of diameters and / or pitch, threads or tappings of the first 7, 8 and second fastening means 10. The first 7, 8 and second fastening means 10 can also be quick fastening means, in particularly fastening means snap or clipping, crimping or bayonet.
    [0020] During the use of the nozzle, the laser beam 22 and the assist gas 23 pass through the axial passage 5 of the movable element 2 and emerge through the second outlet orifice 6 opening at the front portion 2a forming a skirt. Advantageously, the mobile element 2 is displaceable in translation along the axis AA in the first axial housing 3 in the direction of the first outlet orifice 4 until the front portion 2a projects outside said first axial housing 3 through the first outlet orifice 4. Preferably, the movable member 2 moves under the effect of the pressure of the assist gas 23 which is exerted on said movable member 2, which tends to push it in the direction of the workpiece 30. The displacement in translation along the axis AA of the movable element 2 will cause the approximation of the skirt of the upper surface 30 of the sheet to be cut, which will come into contact with each other. on the other, as shown in Figure 4B. Thus, the gas will be channeled through the skirt and be concentrated at the laser spot and therefore the bleeding, which will greatly improve its efficiency of expulsion of the molten metal by the laser beam 22. Advantageously, an elastic element 17, such as a spring, is arranged in the first axial housing 3, between the nozzle body 1 and the movable element 2 or in the second axial housing 15, between the separator sleeve 14 and the mobile element 2. More specifically, the elastic member so as to exert an elastic restoring force on the movable member 2 in a direction tending to move it away from the workpiece 30. Thus, at the end of cutting, when the gas is cut and the pressure gas ceases to be exerted on the movable member 2, it can be recalled in its rest position and thus the skirt back inside the first housing 3. The elastic element 17 is advantageously arranged between the first stop 18 and the first shoulder 19a of the nozzle body 1 or the second shoulder 19b of the sleeve 14 according to whether a sleeve is arranged or not in the first axial housing 3. The elastic element 17 thus makes it possible to limit the phenomenon of wear of the skirt during piercing phases of the sheet which generally precede the cutting phases. Indeed the drilling is most often operated with low gas pressures, typically less than 4 bar. The elastic element then exerts a sufficient restoring force so that the skirt rises completely or almost completely in the first housing 3 and is thus protected from projections of molten metal generated by the drilling. In addition, the elastic member 17 facilitates rapid movements of the cutting head a short distance above the sheet, without cutting gas or beam, since the gas pressure then ceases to be exerted on the movable member. and the skirt fits inside the first housing 3. Only the skirt rises and it is not necessary to raise the focusing head supporting the nozzle. The elastic element 1 also makes it possible to limit the pressure exerted by the movable element 2 on the workpiece when it moves towards the workpiece under the effect of the cutting gas. More specifically, the restoring force of the elastic element 8 is advantageously dimensioned so as to keep the movable element 2 in contact with the workpiece while limiting the pressure that said element exerts on the sheet, to greatly minimize or eliminate any risk of deformation of the sheet in which the piece is cut, scratches of the surface of the sheet, and drive the sheet.
    [0021] Depending on the case, the movable element 2 may comprise a front portion 2a of cylindrical shape, that is to say of constant external diameter along the axis AA, or a shaped end portion to pass on a vertical drop or an obstacle without or with a greatly reduced shock at the level of the skirt 6. Advantageously, the front portion 2a comprises an end portion whose outer diameter gradually decreases towards the second outlet orifice 12. In this way, the part before 2a is shaped to facilitate its passage on reliefs or obstacles present on the surface of the sheet. The shocks are better absorbed because the gradual decrease in the outer diameter of the end portion promotes the rise of the skirt 6 to the housing 5 when the skirt 6 encounters a drop or a punctual obstacle.
    [0022] By end portion is meant a portion of the front portion 2a located at the end of said front portion, that is to say facing the upper surface of the sheet to be cut. Optionally, at least one sealing element, for example an elastomeric seal, is arranged between the nozzle body 1 and the movable element 2 or between the separator sleeve 14 and the mobile element 2, in particular one or more O-rings. , which ensures a seal between the nozzle body 1 or the separator sleeve 14 and the movable insert 2. Preferably, said sealing member is arranged in a peripheral groove arranged in the outer peripheral wall of the movable element 2. In fact, the movable element 2 of the nozzle according to the invention is able to move between several positions comprising at least: - a working position in which the front portion 2a is totally or almost totally protruded at the outside of the first axial housing 3 of the nozzle body 1, through the first outlet orifice 4, and comes into contact with the workpiece 30 to be cut, as illustrated in FIG. 4A, and - a rest position in which e the front portion 2a is completely or almost completely retracted into the first axial housing 3 of the nozzle body 1, as shown in Figure 4B. Of course, the mobile element 2 can occupy intermediate positions in which the front portion 2a only partially projects outside the first axial housing 3 of the nozzle body 1. These intermediate positions can be in particular a function of the pressure exerted by the gas on the movable element 2. In order to show the effectiveness of the nozzle according to the invention with respect to a standard nozzle, that is to say a conventional nozzle without moving element, and therefore the interest of to force the gas in the cutting groove through the implementation of a skirt mounted on a movable element, comparative tests were carried out using a cutting unit with CO2 laser generator to generate a laser beam which is brought to a laser focusing head comprising focusing optics, namely lenses. Example 1 The laser focusing head is equipped with:. a standard nozzle with a 1.8 mm diameter outlet, or. of a nozzle according to Figure 3 with two-part body, cylindrical steel skirt and axial passage of the conical profile skirt with cylindrical outlet channel with a diameter of 1.8 mm in diameter.
    [0023] During this test, the capacitive sensor is set to adjust the distance between the front face of the cap and the upper surface of the sheet to be cut at a distance of 1 mm. The assist gas used is nitrogen. The cutting sheet is made of 304 L stainless steel 5 mm thick.
    [0024] The laser beam has a power of 4 kW and the cutting speed is 2.6 m / min. The results obtained showed that: - with the standard nozzle, a gas pressure of 14 bar is insufficient to obtain a quality cut. Indeed, at 14 bar, the cutting edges have many adherent burrs. This demonstrates that the evacuation of the molten metal is hurt due to insufficient action of the gas on the molten metal to be expelled. In order to eliminate these burrs, a pressure of 16 bar was necessary. With the nozzle of the invention, tests carried out at pressures ranging between 1 and 5 bar led to good quality cuts, that is to say to cutting edges devoid of adherent burrs. The skirt of the nozzle allows to channel the gas in the kerf and effectively expel the molten metal. Example 2 The laser focusing head is equipped with:. standard nozzle (A) with outlet orifice 1.5 mm in diameter,. a nozzle with a one-piece body (B) according to WO-A-2012/156608, cylindrical steel skirt and axial passage of the conical profile skirt with cylindrical outlet channel of 2 mm in diameter, or. a nozzle (C) according to Figure 3 with a two-part body, cylindrical steel skirt and axial passage of the conical profile skirt with cylindrical outlet channel with a diameter of 6 mm in diameter. During this test, the capacitive sensor is set to adjust the distance between the front face of the cap and the upper surface of the sheet to be cut at a distance of 1 mm. The assist gas used is nitrogen. The cutting sheet is made of 304 L stainless steel of 2 mm thickness. The laser beam has a power of 4 kW.
    [0025] The table below shows the cutting results obtained under the conditions of Example 2 with the three types of nozzle A, B, C mentioned above, in terms of cutting speed, pressure of assistance gas used and presence or absence of burrs and / or traces of oxidation on the cutting faces. These tests clearly demonstrate the effectiveness of the nozzle C according to the invention which makes it possible to considerably reduce the gas pressures to be used compared with a standard nozzle, all other conditions being equal, and therefore also to reduce the gaseous consumption. . In addition, the nozzle C according to the invention allows a widening of the diameter of the exit orifice of the assist gas, which allows thin thickness to increase the cutting speed without generating oxidation phenomenon of the faces of cutting, which was not possible with the movable skirt nozzle B according to the prior art.
    [0026] Table 2 Tip Type Material / Thickness Orifice Diameter Pressure Cutting Speed Cut Quality A Steel 304L / 2 mm 1.5 mm 15 bar 6.7 m / min Good, no smudging or oxidation B Steel 304L / 2 mm 2.0 mm 7 bar 6.7 m / min No burrs but oxidized cutting faces C Steel 304L / 2 mm 6.0 mm 7 bar 9.5 m / min Good, without smudging or oxidation (Invention)
    权利要求:
    Claims (13)
    [0001]
    REVENDICATIONS1. Laser nozzle comprising: - a nozzle body (1) comprising a first axial housing (3) passing axially through said nozzle body (1), an inlet orifice (9) for feeding said first axial housing (3) with an assist gas (23) and a first outlet (4) located at a front face (1a) of said nozzle body (1), and - a movable member (2) arranged in the first axial housing ( 3) of the nozzle body (1), said movable element comprising a front part (2a) forming a skirt and an axial passage (5) with a second outlet orifice (6) opening at the level of said front part (2a) forming a skirt , characterized in that the nozzle body (1) is formed of at least a first part (11) arranged around the movable element (2) and a second part (12) coming to position, following the direction of flow of the assist gas (23) into the first axial housing (3) above said first portion (11), the nozzle body (1) further comprising s first attachment means (7, 8) adapted to and adapted to secure the second portion (12) to the first portion (11).
    [0002]
    Nozzle according to Claim 1, characterized in that the first fastening means (7, 8) extend through at least a portion of the first and second parts (11, 12) of the nozzle body (1) and according to a direction generally parallel to the axis of the first axial housing (3).
    [0003]
    Nozzle according to one of the preceding claims, characterized in that the second portion (12) of the nozzle body (1) comprises second fastening means (10) adapted to and adapted to secure said second portion (12) to a laser focusing head (20).
    [0004]
    4. Nozzle according to one of the preceding claims, characterized in that the first (7, 8) and second fixing means (10) are adapted to and designed to fix the second portion (12) of the nozzle body (1). at the laser focusing head (20) more securely than at the first part (11), so that, in the event of an impact at the first part (11) of the nozzle body (1), there is causes deformation or breakage of the nozzle body (1) substantially between the first portion (11) of the nozzle body (1) and the second portion (12).
    [0005]
    5. Nozzle according to one of the preceding claims, characterized in that the movable element (2) is adapted to and designed to move in translation in the first axial housing (3) towards the first outlet (4) until the front portion (2a) protrudes outside said first axial housing (3) through the first outlet (4).
    [0006]
    6. Nozzle according to one of the preceding claims, characterized in that the movable member (2) is adapted to move in translation in the first axial housing (3) towards the first outlet orifice (4) under the effect of a gas pressure applying in the first axial housing (3) and acting on the movable element (2).
    [0007]
    7. Nozzle according to one of the preceding claims, characterized in that it further comprises a resilient element (17) arranged in the first axial housing (3) between the nozzle body (1) and the movable element ( 2), said elastic member (17) exerting an elastic restoring force on the movable member (2) tending to oppose the translation movement in the first axial housing (3) towards the first outlet (4) .
    [0008]
    8. Nozzle according to one of the preceding claims, characterized in that it comprises a separator sleeve (14) arranged between the first portion (11) and the movable member (2), said separator sleeve (14) comprising a second axial housing (15) comprising a third outlet (16) located at a front face (14a) of said separator sleeve (14), the movable member (2) being arranged in said second axial housing (15) and said third outlet (16) opening above said second outlet (6) of the axial passage (5) of the movable member (2) when the front portion (2a) projects out of the first housing axial (3).
    [0009]
    9. Nozzle according to one of the preceding claims, characterized in that the separator sleeve (14) is formed of a material having a relative permittivity less than 8, preferably less than 6.
    [0010]
    10. Nozzle according to one of the preceding claims, characterized in that the movable member (2) is adapted to move between several positions comprising: - a rest position in which the front portion (2a) of the movable member (2) is totally or almost completely retracted into the axial housing (3), and- a working position in which the skirt of the front part (2a) of the movable element (2) is totally or almost totally protruding outside the axial housing (3), through the first outlet (4).
    [0011]
    11. laser focusing head (20) comprising at least one focusing optics, characterized in that it further comprises a laser nozzle according to one of the preceding claims.
    [0012]
    Laser installation comprising a laser generator, a laser focusing head and a laser beam conveying device connected to said laser generator and to said laser focusing head, characterized in that the laser focusing head is according to claim 11.
    [0013]
    13. Laser beam cutting method of a metal part (30), in which is implemented a nozzle according to one of claims 1 to 10, a laser focusing head according to claim 11 or an installation according to claim 12.
    类似技术:
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    FR3101559A1|2021-04-09|METAL LASER DEPOSIT SYSTEM
    同族专利:
    公开号 | 公开日
    EP3140075B1|2018-06-06|
    EP3315247B1|2019-12-04|
    ES2678396T3|2018-08-10|
    JP2017514700A|2017-06-08|
    CN106457484B|2019-11-15|
    US20170189993A1|2017-07-06|
    FR3020774B1|2016-05-13|
    WO2015170029A1|2015-11-12|
    EP3315246B1|2020-10-21|
    EP3140075A1|2017-03-15|
    ES2764711T3|2020-06-04|
    CN106457484A|2017-02-22|
    EP3315247A1|2018-05-02|
    EP3315246A1|2018-05-02|
    JP6594900B2|2019-10-23|
    引用文献:
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    JP4820910B2|2010-03-29|2011-11-24|日酸Ｔａｎａｋａ株式会社|Laser cutting method, laser cutting nozzle and laser cutting apparatus|
    FR2982184B1|2011-11-07|2014-08-01|Air Liquide|LASER NOZZLE WITH MOBILE ELEMENT ON GAS LAYER|
    FR2997881B1|2012-11-09|2015-04-17|Air Liquide|LASER NOZZLE WITH EXTERNAL MOBILE ELEMENT|DE102015208157B4|2015-05-04|2017-06-14|Trumpf Werkzeugmaschinen Gmbh + Co. Kg|Cutting gas nozzle and laser cutting method with sliding valve sleeve for adjusting the flow characteristics|
    WO2017075566A1|2015-10-30|2017-05-04|Hypertherm, Inc.|Double nozzle for a laser processing head|
    US10569360B2|2015-10-30|2020-02-25|Hypertherm, Inc.|Highly positioned laser processing nozzle|
    DE102016215019B4|2016-08-11|2017-08-17|Trumpf Werkzeugmaschinen Gmbh + Co. Kg|Process for laser cutting with optimized gas dynamics|
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    法律状态:
    2015-05-21| PLFP| Fee payment|Year of fee payment: 2 |
    2015-11-13| PLSC| Search report ready|Effective date: 20151113 |
    2016-05-20| PLFP| Fee payment|Year of fee payment: 3 |
    2017-05-23| PLFP| Fee payment|Year of fee payment: 4 |
    2018-05-22| PLFP| Fee payment|Year of fee payment: 5 |
    2019-05-22| PLFP| Fee payment|Year of fee payment: 6 |
    2020-05-22| PLFP| Fee payment|Year of fee payment: 7 |
    2021-05-20| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1454093A|FR3020774B1|2014-05-06|2014-05-06|LASER NOZZLE WITH INTERNAL MOBILE ELEMENT AND DEFORMABLE BODY|FR1454093A| FR3020774B1|2014-05-06|2014-05-06|LASER NOZZLE WITH INTERNAL MOBILE ELEMENT AND DEFORMABLE BODY|
    JP2016566739A| JP6594900B2|2014-05-06|2015-04-22|Laser cutting nozzle with internal movable element and low dielectric constant sleeve|
    EP15725779.1A| EP3140075B1|2014-05-06|2015-04-22|Nozzle for laser cutting with an internal moveable element and a sleeve with low relative permittivity|
    EP17198493.3A| EP3315246B1|2014-05-06|2015-04-22|Laser nozzle with internal mobile element and nozzle body being made in two parts connected through fixtures|
    CN201580033435.9A| CN106457484B|2014-05-06|2015-04-22|The nozzle for laser cutting with internal displaceable element and low relative permitivity sleeve|
    US15/308,666| US20170189993A1|2014-05-06|2015-04-22|Nozzle for laser cutting with an internal moveable element and a sleeve with low relative permittivity|
    ES17198494T| ES2764711T3|2014-05-06|2015-04-22|Nozzle for laser cutting with an internal moving element and a sleeve with low relative permittivity; laser beam cutting procedure of a metal part using such a nozzle|
    EP17198494.1A| EP3315247B1|2014-05-06|2015-04-22|Nozzle for laser cutting with internal mobile element and sleeve having low relative permittivity ; process of cutting with a laser beam of a metallic workpiece using such a nozzle|
    ES15725779.1T| ES2678396T3|2014-05-06|2015-04-22|Nozzle for laser cutting with an internal moving element and sleeve of low relative permittivity|
    PCT/FR2015/051090| WO2015170029A1|2014-05-06|2015-04-22|Nozzle for laser cutting with an internal moveable element and a sleeve with low relative permittivity|
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