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    • 专利摘要:
    The invention relates to a method for manufacturing a toothed wheel (1), said method comprising a step (a) during which a carrier core (3) is produced in a first polymer material, said carrier core (3) comprising a hub (4) having a steering axis (XX ') and a flange (5) extending radially from said hub (4) to a peripheral flange (6), said method then comprising a step (b) of coating in which is formed by molding on the carrier core (3), in a second polymeric material, a coating layer (7) permanently comprising a single piece on the one hand a front layer (7F) which covers the upper surface (5S) of the flange (5), and secondly a lateral layer (7L) which axially extends said front layer by covering the radially outer surface (6E) of the flanged edge ( 6), such that said side layer (7L) forms a rim (8) in the radial thickness of which e are made meshing teeth (2) of the wheel (1)
    公开号:FR3020305A1
    申请号:FR1453702
    申请日:2014-04-24
    公开日:2015-10-30
    发明作者:Patrice Brochot；Laurent Rey
    申请人:JTEKT Europe SAS；
    IPC主号:
    专利说明:

    [0001] The present invention relates to the general field of manufacturing wheels intended to ensure the transmission of a torque within a mechanism, and more particularly to the field of production of wheels. gear wheels for gear mechanisms. The present invention relates more particularly to the manufacture of gear wheels for power steering reducers for motor vehicles. Document US-2010/0201030 discloses a method for manufacturing gears during which a metal hub is placed in a mold, as well as a toothed rim, and then the hub is connected to the rim. forming between them, by molding, an intermediate disk of plastics material. Such a method may, however, have certain disadvantages. First of all, the use of a metal hub, of sometimes relatively large dimensions, tends to weigh down the toothed wheel thus obtained. Then, such a method requires very precisely position the rim relative to the hub, during the molding of the intermediate disc. In practice, any defect in the positioning of the parts, or any uncontrolled displacement of one part with respect to the other during molding, under the pressure of the injected plastic, can lead to a significant concentricity defect of the teeth of the wheel by relative to the axis of rotation of said wheel, which can compromise the proper functioning of the toothed wheel (noise, wear ...), or even cause it to be scrapped. In addition, such a method requires that the rim and / or the hub have relatively complex shapes, intended to improve the grip of the intermediate disc, which may in practice complicate the prior manufacture of the hub and / or the rim, and therefore increase the cost. Finally, it is systematically necessary to proceed, after molding, to a recovery of the wheel by machining, in particular to eliminate the solidified remains 30 of the downcomers (conical), which increases the manufacturing time and tends to cause some waste of raw material. The objects assigned to the invention therefore aim at overcoming the aforementioned drawbacks and at proposing a new process for manufacturing gear wheels which is simple and inexpensive to implement and which makes it possible to obtain, reliably and reproducibly , toothed wheels both light and robust.
    [0002] The objects assigned to the invention are achieved by means of a method of manufacturing a toothed wheel, said method comprising a step (a) of producing a carrier core, during which a carrier core is produced in a first polymer material, said bearing core comprising a hub, with a directing axis (XX '), and a flange which extends substantially radially from said hub, away from the steering axis (XX'), up to a peripheral flange, said collar being delimited axially by a so-called "upper" surface oriented on the axially opposite side to the flanged edge, and by a so-called "lower" surface oriented axially on the side of the flanged edge, said method then comprising a step (b) a coating during which a permanent coating layer which remains permanently on the finished toothed wheel, said layer of e is produced by overmolding on the carrier core, in a second polymeric material; nrobage comprising in one piece on the one hand a front layer which covers the upper surface of the collar in axial excess of said collar, and secondly a lateral layer which axially extends said front layer by covering the radially outer surface of the fallen edge, in radial excess thickness of said fallen edge, such that said side layer forms a rim in the radial thickness of which are formed the meshing teeth of the wheel. Advantageously, the use of polymer materials simplifies the manufacture of the carrier core and the coating layer, possibly allowing molding production or, more particularly, manufacturing by a succession of overmolding operations. In addition, the use of polymeric materials provides overall relief of the toothed wheel, compared to a wheel with a metal structure. The coating layer according to the invention also advantageously forms a one-piece shell which adheres to the carrier core and envelopes said carrier core in several directions, both axially, extending transversely to the directing axis (XX). '), on the upper surface of the flange, and radially, extending substantially parallel to said steering axis (XX'), on the dropped edge, which allows to obtain an excellent anchoring of the coating layer on the carrier core, and therefore an excellent cohesion of the mixed structure, here bilayer, thus obtained, which is permanently retained in order to guarantee durably a good resistance of the toothed wheel during its operation, both vis-à-vis couples transmitted around the steering axis (XX ') as possible axial tearing forces. Advantageously, by covering the carrier core with an extended coating layer, which lays both the peripheral rim of the toothed wheel and the radially intermediate portion of said toothed wheel, between the hub and said rim, and which therefore corresponds to At the "spokes" of the toothed wheel, the structure of the carrier core as a whole is strengthened and effectively stiffened, while using a relatively small amount of material.
    [0003] In this respect, it will be noted that, on the one hand, thanks to the generally convex structure of the toothed wheel, in the form of a hollow dome shell (centered on the generator axis) or "bell", which is obtained thanks to the profile of the the soul that draws the flange and the fallen edge placed in the continuity of said flange, and also thanks to a coating layer which substantially matches this same profile, it confers excellent rigidity to the toothed wheel, even using relatively thin material thicknesses, both for the core and for the coating layer. Advantageously, the toothed wheel according to the invention is therefore both light and economical in raw material, while remaining particularly solid. In addition, the appropriate form of the carrier core allows an effective, progressive and homogeneous topping of said core by the second polymeric material, when it is in the fluid state and flows to the surface of said core. during overmolding. The manufacture of the coating layer is therefore particularly simple and reliable. In addition, the quality of the flow and the material distribution provided by the arrangement proposed by the invention makes it possible in particular to resort to overmoulding in the diaphragm (flat) by central injection, in the axis of the core. carrier, which uses very little residual material for the descent of casting. This saves raw material, while significantly reducing finishing operations by resuming machining. Finally, the proposed manufacturing method, which makes it possible to easily produce a homogeneous rim of good radial thickness around the dropped edge, in a (second) particularly resistant material, is particularly suitable for carrying out a cutting operation of meshing teeth of the wheel which is posterior to the molding operations, and preferably subsequent to the attachment of the wheel on its shaft, which makes it possible to overcome any lack of concentricity between the actual pitch diameter of the toothing and the material axis of rotation of the toothed wheel. Other objects, features and advantages of the invention will appear in more detail on reading the description which follows, and with the aid of the accompanying drawings, provided for purely illustrative and non-limiting purposes, among which: Figures 1, 2, 3 and 4 illustrate, in axial sectional views, the successive steps of a manufacturing method according to the invention. Figures 5 and 6 illustrate, in partial views in axial section, the bare bearing core and the bearing core coated with its final coating layer.
    [0004] Figures 7, 8 and 9 illustrate, in perspective views from above, in perspective of cutaway top, and in perspective from below, the finished toothed wheel of Figure 4, obtained by a method according to the invention. Figures 10, 11, 12 and 13 illustrate, respectively in perspective views from below, in perspective from above, in perspective of cutaway top, and in axial projection from above, the carrier core of the toothed wheel of Figures 1 to 9, mounted on a connection socket. Figure 14 illustrates, in a partial view from above, the detail of the channel grooves dug in the carrier, at the transition between the flange and the flange. Figures 15 and 16, respectively 17 and 18, respectively 19 and 20 illustrate, in pairs of perspective views from below and in axial projection from below, three embodiments of gear wheels according to the invention. The present invention relates to a method of manufacturing a toothed wheel 1. Said toothed wheel 1 may in particular be a gear wheel gear, and more particularly a gear wheel for power steering, and may for example form a tangent wheel for to be driven by a worm. The toothed wheel may have any type of meshing teeth 2, 25 for example forming a right toothing (as illustrated, in a non-limiting manner, in FIGS. 7 to 9, 15 and 16), a helical toothing (such as that is illustrated, not limited to, in FIGS. 17 to 20), or a herringbone toothing. The method firstly comprises a step (a) of producing a carrier core, in the course of which a carrier core 3 is produced in a first polymeric material, as illustrated in FIG. invention, and as that is particularly illustrated in Figures 1 to 6, 8, 11, 12 and 13, said carrier core 3 comprises a hub 4, axis director (XX ') and a flange 5 which s extends substantially radially from said hub, away from the steering axis (XX '), to a peripheral flange 6.
    [0005] The steering axis (XX ') corresponds in practice to the axis of rotation of the toothed wheel 1, and is advantageously common to the various components of said wheel. For convenience of description, the term "axial" a direction or a dimension considered along said axis director (XX ') or parallel thereto, and "radial" a direction or a dimension considered transversely, and more particularly perpendicular, audit steering axis (XX '). By convention, it will be considered that the flange 5 is delimited axially by a so-called "upper" surface 5S oriented on the axially opposite side to the dropped edge 6, and by a so-called "lower" surface 51 oriented axially on the side of the fallen edge 6. So-called upper surface 5S will here correspond in practice to the apparent surface intended to receive a coating layer 7 (while the opposite bottom surface 51 is preferably intended to remain bare, without a coating layer), said upper surface 5S being axially oriented for this purpose on the side of the material inlet (the side of the overmolding injector), while the falling edge 6 "falls" (and is contained) in axial withdrawal of said upper surface 5S. As is particularly visible in Figures 8, 11 and 13, the flange 20 5 (full) surrounds the hub 4 around the entire circumference of said hub, 360 degrees around the steering axis (XX '), to make office of spokes of the wheel, so as to ensure a stable connection between said hub 4 and the periphery of the toothed wheel 1 forming the rim 8 carrier meshing teeth 2. As such, it will be noted that the overall diameter D5 of the flange 5, and more generally the overall diameter of the carrier core 3, will preferably be equal to or greater than 50%, 60% or even 75% of the overall diameter D1 of the finished wheel 1, and preferably less than or equal to 90%, or even 85% of said overall diameter D1 of the finished wheel. As an indication, on the views provided, this ratio D5 / D1 is of the order of 84%. Although the invention is not limited to a wheel 1 of particular dimensions, it will be noted that, particularly in the context of a wheel 1 intended for a power steering gearbox, the overall diameter D 1 of said wheel 1 may be substantially between 3 cm and 20 cm, more particularly between 5 cm and 15 cm, and preferably equal to 10 cm. The hub 4 will preferably extend axially beyond the thickness of the flange 5 to provide sufficient axial reach of the wheel 1 on its shaft.
    [0006] Preferably, for the sake of compactness, said hub 4 will extend at least in part in axial projection from the lower surface 5S, inside the volume enveloped by the flange 5 and by the dropped edge 6, as illustrated. in Figures 2 to 6.
    [0007] In a particularly preferred manner, the hub 4 will extend (protrude) axially on either side of the flange 5, both in axial projection of the upper surface 5S and, on the opposite side, in axial projection of the lower surface. 51. The flange 5 preferably extends, and at least starts from the hub 4, substantially in a plane PO normal to the steering axis (XX '), or, more particularly, as it is visible. in FIG. 5, along a slight slope a5 which progressively folds said flange 5 toward the fallen edge 6, as one moves away from the director axis (XX '). The slope a5 (the cone) followed by the collar 5, or at the very least by the upper surface 5S of said flange 5, may be between 5 degrees and 20 degrees, and preferably between 10 degrees and 15 degrees, relative to at the plane PO normal to the steering axis (XX '). As an indication, in Figure 5, said slope a5 is of the order of 15 degrees. Such a frustoconical sloping arrangement will facilitate firstly the manufacture by molding of the carrier core 3, in particular by simplifying the stripping, and may furthermore improve the flow of the second polymer material on the upper surface 5S during the The falling edge 6, secant to the flange 5, is in turn folded axially in the continuity of said flange 5, so as to form a cylinder, and more preferably an annular band, concentric with the flange 5. hub 4 and 25 radially remote from said hub 4. Said falling edge 6, and more particularly its radially outer surface 6E, thus preferably extends substantially parallel (to +/- 5 degrees or +/- 10 degrees, for example) to the director axis (XX '), or exactly parallel to the director axis (XX'). The assembly formed by the flange 5 and the dropped edge 6, and more generally the carrier core 3, can thus advantageously have a convex hoop-like (bell-shaped) structure of revolution at the same time. light, strong and rigid. The toothed wheel 1 formed from such a carrier core 3 can therefore benefit from these properties of rigidity and lightness. According to the invention, and as illustrated in particular in FIG. 3, the method then comprises, after the step (a) of producing the carrier core 3, a step (b) of coating during which is formed by molding on the carrier core 3, in a second polymer material, a permanent coating layer 7 which remains permanently on the toothed wheel 1 (that is to say that said coating layer 7 is not removed, or at least not completely removed, by machining after being formed on the carrier core 3, so as to be retained on the final gear 1, in which said coating layer 7 plays in particular a functional role of structural reinforcement). Said coating layer 7 (which remains on the final wheel) comprises in one piece on the one hand a front layer 7F (or "upper layer") which covers the upper surface 5S of the collar 5 in axial excess of said flange 5, and on the other hand a lateral layer 7L which axially extends said front layer 7F by covering the radially outer surface 6E of the fallen edge 6, in radial excess thickness of said dropped edge 6, so that said lateral layer 7L forms a rim 8 in the radial thickness of which are made the meshing teeth 2 of the wheel 1. Advantageously, the added thickness of the carrier core 3, by overmolding, and the conservation, within the wheel 1 finished, a coating layer 7 with two adjoining "secant" and "secant" sections (substantially "L"), namely a front layer 7F (forming a first pan of substantially radial disk type) and a lateral layer 7L (forming a second pan type annea substantially axially, which extends the first panel), makes it possible to obtain a wheel 1 with a bilayer structure, in which the second layer (the coating layer 7), formed by the second polymer material, reinforces (consolidates) the first layer (the carrier core 3) which is formed by the first polymer material and to which said second coating layer 7 (and therefore said second material) is superimposed, this bilayer structure being found both in the intermediate zone corresponding to the "radii" of the wheel (that is to say at the level of the flange 5, from the hub 4 to the fallen edge 6) than in the peripheral zone of the rim 8 (at the level of the fallen edge 6). As such, it will be noted that the front coating layer 7F preferably covers, around the hub 4 and the steering axis (XX '), an annular domain whose radial extent R7F represents at least 25%, at least 30%, and preferably between 40% and 80%, of the total radial extent of the front surface of the carrier core 3 which is radially between the radially inner wall of the bore of the hub 4 and the radially outer surface 6E from the fallen edge 6.
    [0008] According to a dimensioning that can be alternative or substantially equivalent to that mentioned in the preceding paragraph, the front layer 7F coating can cover, around the hub 4 and the axis director (XX '), overlap on the upper surface 5S of the flange 5, an annular domain whose radial extent R7F (considered between the steering axis (XX ') and the rim 8) represents at least 5%, at least 10%, at least 20%, and more particularly between 20% and 50%, for example between 25% and 35% of the overall radius (that is to say the overall half-diameter D1 / 2) of the finished wheel 1. In a particularly preferred manner, the radial extent R7F of the front layer 7F of coating will be greater (and preferably several times greater) than the axial thickness E7 [of said front layer 7F of coating, in order to obtain a good base of the coating layer 7 on the carrier core 3 and effective reinforcement of said carrier core 3 without increasing the size and weight of the wheel 1. The continuity and the extent of the coating layer 7, which comes to form a monolithic over-shell enveloping around the carrier core 3, thus makes it possible to obtain a toothed wheel 1 whose structure is particularly resistant in all points, both at the periphery and in the intermediate portion of the wheel 1, and this even if, if necessary, a carrier core 3 and / or a coating layer 7 relatively thin (s), and therefore particularly light (s). The convex shell structure of the coating layer 7 in particular makes it possible to enhance the adhesion of the coating layer 7 to the carrier core, by maximizing the extent of the contact interface between the first and the second polymeric material. This same shell structure also provides excellent mechanical anchoring of the coating layer 7 on the carrier core 3, the front layer 7F forming, in particular, an axial immobilization abutment of the coating layer 7 against the core carrier 3, and the lateral layer 7L a centering stop (on the axis director) and radial immobilization (transverse to the axis director). In addition, the continuity of the coating layer 7 which covers in one piece the flange 5 and the falling edge 6 makes it possible to give the wheel 1 a neat appearance, with a homogeneous finish, free from unevenness or unevenness. Potential primers of cracks. Although it is not excluded to form the carrier core 3 and / or the coating layer 7 by means of a first material or a second material, of thermosetting resin type, in particular by molding, it will be preferable to Using a first thermoplastic material, and / or respectively a second thermoplastic material.
    [0009] It will thus be possible to easily make the carrier core 3, then the coating layer 7, by hot molding, in particular by (on) injection molding at a pressure greater than atmospheric pressure. As an indication, the axial thickness E7 [residual of the front layer 7F 5 will be between 4 mm and 8 mm, and / or between 4% and 8% of the overall diameter D1 of the finished wheel 1. As an indication, the radial (total) thickness E7L of the lateral layer 7L, that is to say the thickness of the rim 8 (teeth 2 included) may be between 7 mm and 12 mm, and / or between 7% and 12% of the overall diameter D1 of the finished wheel; if necessary, the minimum residual radial thickness of the lateral layer 7L with a tooth base may be between 4 mm and 8 mm. Moreover, the cutting step of the meshing teeth 2 (in the thickness of the rim 8) will preferably take place after the overmoulding step (b), and, particularly preferably, after the wheel 1 will have been fixed on its shaft (not shown). Thus, by cutting the teeth 2 after the molding of the wheel 1, while the effective axis of rotation of the wheel 1 is materialized by the shaft on which said wheel 1 is fixed, so that said shaft forms a reference for the cutting machine, it will be possible to avoid any lack of concentricity between the pitch diameter of the teeth 2 and 20 said effective axis of rotation. Preferably, the shaft to which the wheel 1 is attached will comprise, at an end opposite the end receiving said wheel 1, a toothing, for example helical, forming a meshing pinion intended for example to engage a power steering column. Preferably, during the step (a) of producing the carrier core 3, the hub 4, the collar 5 and the fallen edge 6 are made in one piece. More generally, the carrier core 3 will be made in one piece, in the first polymer material. This will provide a simple and fast way a particularly strong carrier core 30. Preferably, as illustrated in FIGS. 1 and 2, the carrier core 3 (preferably in one piece) will be formed by overmolding on a metal connecting sleeve 10, intended to be fitted on a shaft, or directly by molding on the final support shaft of the toothed wheel 1 (in practice, it would suffice to substitute, in Figures 1 to 6, said shaft, preferably metal, to the sleeve 10).
    [0010] In other words, the method according to the invention preferably comprises two successive overmolding steps, a first overmolding step (FIG. 2) during which the carrier core 3 is formed by overmolding the first material on the sleeve 10 respectively on the shaft of the wheel 1, then a second overmolding step (Figure 3) during which the coating layer 7 is formed by overmolding the second material on the carrier core 3 (in this case by above this last). Such a method makes it possible in particular to quickly and simply produce the structure of the wheel 1, with minimal tooling, since at least a portion of the mold (not shown) used for the first overmolding, for example the lower imprint that allows molding the concave surface of the core 3 opposite to the upper surface 5S, can be reused for the second overmolding. Such a method also makes it possible to save energy, since the second overmolding can take place "hot", as soon as the carrier core 3 is solidified, whereas said carrier core 3, and at least a part of the mold (the reused part), is still hot from the first overmolding. As can be seen in particular in FIGS. 2, 6 and 12, the fixing (by overmoulding) of the hub 4 on the bushing 10, respectively directly on the shaft, can be reinforced by means of attachment shapes 11, 12, such as a protruding stop ring 11 (reinforcing the axial resistance) and / or radial indentations 12 (reinforcing the torque resistance) provided on the bushing 10, respectively on the shaft, and which will be embedded by the first material constituting the hub 4 during the first overmolding step (Figure 2). Preferably, the first, preferably thermoplastic, polymer material which is used to form the carrier core 3 is distinct from the second, preferably thermoplastic, polymer material which is used to form the coating layer 7, said first polymeric material having greater rigidity than that of said second polymeric material (i.e., in practice, a higher Young's modulus than that of the second material). This higher rigidity can for example be obtained by adding reinforcing fibers, for example glass fibers, carbon fibers, aramid fibers, etc., embedded in a polymer matrix, in order to obtain a first composite material. . Of course, the first material as well as the second material will be rigid once solidified at room temperature and over the entire predictable operating temperature range of the wheel 1.
    [0011] The use of a second less rigid material (more flexible) to form the coating layer 7 will have several advantages. First of all, such a second material will be easy to machine, which will make the cutting of the teeth 2 fast and inexpensive.
    [0012] Then, once the wheel 1 formed and implemented within a force transmission mechanism, and more particularly a worm gear, the relative flexibility of the gear teeth 2 will allow the latter to to match the shape of the threads of the worm, which will increase the number of teeth 2 in engagement as well as the contact surfaces under heavy load. This relative flexibility will also distribute and distribute the load over a larger portion of the carrier core 3 and thus avoid the appearance of high local stresses, may be at the origin of breaks. The operation and longevity of the wheel 1 will thus be improved.
    [0013] The use of a first, more rigid material, and more particularly of a first fiber material, to form the carrier core 3, will advantageously make it possible to limit the deformation under load of said core 3, and therefore, more generally, of the wheel structure 1. The use of reinforcing fibers will also make said bearing core 3, and more generally the wheel 1, less sensitive to thermal expansion phenomena, and will confer on said carrier core 3, which forms the portion the most mechanically stressed of the wheel 1 bi-material thus obtained, a better aging resistance in mechanical, thermal and chemical fatigue (vis-à-vis the lubricants used in the mechanism), and therefore a longer life.
    [0014] Advantageously, by creating and shaping a coating layer 7 at a lower cost in a second material which is more flexible than the first, while consolidating by the same coating layer 7 (by adding thickness) the core carrier 3 which supports said coating layer 7 and which is already in itself particularly rigid and solid, the invention makes it possible ultimately to obtain a toothed wheel 1 bi-material which combines robustness, low manufacturing cost, and quality Operating. Moreover, although the first material and the second material preferably have different compositions and therefore mechanical properties, they will preferably have a certain chemical affinity (compatibility) with each other, and possibly with relatively close glass transition temperatures, in order to be bonded by adhesion to one another, and more particularly in order to be able to attach to one another by superficial re-fusion of the first material (of the soul 3) during the injection of the second material (of the coating layer 7). By way of indication, it is possible to use a first composite material comprising a polymer matrix of the same composition as the second material but containing, unlike said second material, reinforcing fibers, or, if the second material is itself a composite containing reinforcing fibers, a first material containing a greater concentration of reinforcing fibers, or reinforcing fibers of a different kind than that of the first material. By way of example, it will be possible to choose a fiber-reinforced PA66 polyamide with 50% glass fibers as the first material (to form the core 3), and a PA66 polyamide as the second material (to form the coating layer 7). . Regardless of the composition of the second material constituting the coating layer 7, the latter will always assume, because it is advantageously placed in the apparent zones of the wheel, in particular at the level of the rim 8, which are the more exposed to external elements, a certain protective role of the core 3, and more generally of the wheel 1, in the manner of a shield, and thus improve the mechanical strength and longevity of said wheel 1. Preferably, and according to a characteristic which can constitute an entire invention, during the step (a) of producing the carrier core 3, channel grooves 13 are formed in the carrier core 3 which extend substantially radially the upper surface of the flange 5, to the dropped edge 6, and which then extend axially, by reference angle, along said fallen edge 6, to the radially outer surface 6E of said flanged edge, such as this is particularly visible in Figures 2, 3, 5, 8, 12 and 13. Advantageously, these channel grooves 13 can fulfill a dual function. First, during the step (b) of coating, said channel grooves 13, which open to the apparent surface of the carrier core 3 which is intended to be coated by the coating layer 7 , contribute to channeling, orienting and homogenizing the radial centrifugal flow of the second material (liquid) from the hub 4 to the dropped edge 6, and then along said fallen edge 6, which makes it possible to obtain a good distribution of the coating layer 7. After cooling (hardening) of the coating layer 7, said channel grooves 13 form, around the direction axis (XX '), crenellated reliefs embedded in the coating layer 7, and thus provide a solid anchoring of said coating layer 7, which improves the cohesion of the wheel against particular couples that are transmitted by said wheel 1 between the hub on the one hand 4 attached to the shaft and belonging to the core 3 and on the other hand the meshing teeth 2 of the rim 8 belonging to the coating layer 7. Advantageously, in order to ensure effective guidance of the flow of the second material to the falling edge 6 included, and more particularly in order to facilitate the circumvention of the transition between the flange 5 (radial) and the flanged edge 6 (axial), the channel grooves 13 comprise (upstream to downstream of the flow) a front section 13F, hollowed in the flange 5 and which follows a substantially radial direction ( substantially horizontal or sloping a5), then a lateral section 13L dug in the falling edge 6, which follows a path substantially parallel to the axis director (XX '), said sections 13F, 13L and arranged in a bevel gear (substantially "L") being located in the extension of one another and communicating with each other so as to globally form a continuous groove 13 which follows the contour (convex) of the carrier core 3. Preferably, the channel grooves 13 will be equidistributed in a star all around the director axis (XX '), as illustrated in FIGS. 8, 11, 12 or 13. As an indication, the width of each channel groove 13 may be substantially between 2 mm and 6 mm, and / or occupy an angular sector 20 is between 5 degrees and 15 degrees, and for example of the order of 7 degrees to 10 degrees, in azimuth (in yaw) around the axis direction ( XX '). The number of channel grooves 13 will preferably be greater than 12, and for example equal to 36, as illustrated in FIGS. 11 and 13. As an indication, the depth P13 of the channel grooves 13 (that is, that is to say the depth according to which each groove penetrates the surface of the collar 5, then that of the dropped edge 6), may be between 1 mm and 3 mm. In addition, the lateral sections 13L (axial) of the channel grooves 13 which run along the dropped edge 6 preferably have, as is particularly clearly visible in FIG. 14, transverse sections with an anti-torn strangulation 14, dovetail, which reinforce the grip of the rim 8 on said fallen edge 6, in particular against centrifugal radial forces. The constrictions 14 may advantageously be formed by bulges of the partition walls 15 respectively separating each channel groove 13 of the channel grooves 13 which are adjacent thereto. In section in a plane normal to the steering axis (XX '), the transverse section of the lateral section (s) 13L concerned may have any constricted shape, that is to say any shape with a narrowing of its opening on the surface. external 6E of the dropped edge, which will be functionally equivalent to a dovetail, for example a bulbous shape and narrow neck, a shape in "T", etc. Such throttled sections 14 may advantageously be obtained by molding during step (a) of producing the carrier core 3, by using cores (or a male fingerprint) of conjugate shape, carried substantially according to FIG. the steering axis (XX '), which will advantageously correspond to the demolding direction, and placed tangentially to the dropped edge 6, so that said cores each print a lateral section 13L of channel groove in said fallen edge 6 Preferably, during step (a) of producing the carrier core 3, the transition zone between the flange 5 and the dropped edge 6 is formed in a rounded manner 16, as is particularly visible on the Figures 2 to 6, 11 and 12. Preferably, the radius of curvature R16 of said round 16 is greater than or equal to 2 mm, and preferably less than or equal to 10 mm; said radius of curvature R16 will be particularly preferably substantially between 2 mm and 6 mm. Advantageously, a rounded flange 16 avoids the stress concentrations within the wheel, and thus improves the breaking strength of said wheel 1. In addition, this same rounded portion 16, which advantageously allows the channel grooves 13 to form a bent angle gear, facilitates the flow of the second material during the step (b) of coating, and more particularly the bypassing by the second liquid material of the junction between the flange 5 and the flange 6, in facilitating the transition between a radial flow at the upper surface 5S of the flange and an axial flow on a falling edge 6. Preferably, during the step (a) of producing the carrier, is formed on the lower surface 51 of the flange 5, opposite and at the axial plumb with the upper surface 5S intended to receive the coating layer 7, a plurality of reinforcing ribs 17 arranged along several azimuths around the directing axis 30 ( XX ' ), that is to say distributed in several yaw directions about said director axis (XX '), each of said reinforcing ribs 17 connecting the hub 4 to the lower surface 51 of the flange and to the radially inner surface 61 of the falling edge 6, as is particularly clearly visible in Figures 5, 6, 9, 10 and 15 to 20. Advantageously, these reinforcing ribs 17 form substantially (or exactly) radial partitions 35 which support the collar 5 and the falling edge 6 on the back of the carrier core 3, and more particularly which locally increase the axial thickness of the collar 5, in the concave (concealed) internal space of said bearing core 3 situated axially opposite the point d injection of the second material with respect to the upper apparent surface 5S of the flange 5. This allows the flange 5 and the dropped edge 6 to withstand, substantially without deformation, the pressure exerted by the second material during the molding of the layer 7, while retaining a light hollow structure, in particular at the axial plumb with the front layer 7F of coating, because of the presence of empty cells 18 of material which angularly separate the reinforcing ribs 17 one of the other.
    [0015] The reinforcing ribs 17 may have different shapes, rectilinear or curved, without departing from the scope of the invention, and in particular follow a rectilinear arrangement strictly radial star around the axis director (XX '), as illustrated on Figures 9 and 10 or 19 and 20, or a curved arrangement with arched feet (Figures 15 and 16), or a rectilinear arrangement in braces (Figures 17 and 18). Where appropriate, as illustrated in FIGS. 19 and 20, an annular intermediate strapping rib 17B, centered on the directing axis (XX '), can provide a junction between the various radial reinforcing ribs 17, in which hollow cavity radially between the hub 4 and the radially inner (distinct) surface 61 of the fallen edge 6. Advantageously, both for convenience of manufacture and to improve the strength of the carrier core 3, the reinforcing ribs 17, 17B will be made in one piece with the rest of the carrier core 3, during the step (a) of realization by (on) molding of said carrier core 3.
    [0016] Furthermore, preferably, during the step (a) of producing the carrier core, the upper surface 5S of the flange 5 is formed in axial recess from the corresponding end, called the "upper end" 4S, of the hub. 4, so as to form a shoulder 20 between the upper end 4S of the hub and the upper surface 5S of the collar, as is particularly well visible in Figures 2, 5 and 12. Preferably, during the step (b) coating, the front coating layer 7F can then advantageously wetting said shoulder 20, as is particularly visible in Figure 3. Advantageously, following step (b) coating, we can thus conserving, on the finished wheel 1, and as it is particularly visible in FIGS. 4, 6 and 8, at least a partial filling of said shoulder 20 with said front layer 7F, according to an axial thickness E7 [non-zero, preferably such that said front layer 7F afflicts axially the upper end 4S of the hub 4 (the front layer 7 thus filling the volume axially between the upper surface 5S of the flange and the upper end of the hub 4, here the closest to said upper surface 5S). Advantageously, the use of the hub 4 as a molding mark and / or as a machining recovery mark of the coating layer 7 simplifies the manufacture of said coating layer. Indeed, it will be possible for example to place in the mold, during the step (b) of coating, a central core intended to fill the bore of the hub 4, and more particularly a core filling the bore of the sleeve 10 , or alternatively directly use the shaft of the wheel 1 as a core, then inject at the upper end 4S of the hub the second polymeric material intended to form the coating layer 7, in order to fill the shoulder 20 ( without risk of overflowing into the hub bore 4, occupied and thus protected by the core). As illustrated in FIG. 3, the injection F of the second polymer material will preferably be substantially in a central position, opposite the center of the hub 4, ie along the axis director (XX '), so as to form (on the upper surface 4S of the hub and on the upper face of the core which closes said hub) a diaphragm 21 from which the second liquid material will spread progressively to the surface of the collar 5 and the dropped edge 6. Thanks to the diaphragm 21, substantially flat, and normal to the steering axis (XX '), we can benefit from a relatively large material injection surface, which will limit the shear phenomena and self-heating of the injection point that would otherwise be capable of degrading the quality of the second material, and more particularly the toughness of said second material (in fact, the shear tends to cut the polymer chains, which degrades the viscosity and the tenacity of the polymer in question, especially if it is a polyamide). It is thus possible to obtain a homogeneous and effective coating of the carrier core 3 by a second particularly robust material. It will then be possible to provide a finishing step (c) (FIG. 4) during which the diaphragm 21 will be removed by leveling, for example by milling, so as to obtain a residual front layer 7F which is axially flush with the upper end 4S. the hub (which is itself in the same plane, normal to the directing axis (XX '), as the upper end of the sleeve 10).
    [0017] Such a manufacturing method advantageously makes it possible to obtain a compact and solid finished wheel 1 in a minimum of relatively simple steps, and by consuming little material (the volume lost by the leveling of the diaphragm 21 being particularly reduced).
    [0018] Moreover, preferably, during the step (a) of producing the carrier core, at the free end of the dropped edge 6 located axially opposite the flange, a retaining radial recess 22 is formed. , of the kind indentation or annular groove, as is visible in particular in Figures 2, 5, 6 and 12. Thus, during step (b) of coating, it is possible to continue the wetting of the dropped edge 6 with the second polymeric material to fill said recess radial recess 22, thereby forming a support flange 23 integrally formed with the side coating layer 7L, so that the carrier core 3 is axially locked in the two directions within the coating layer 7 by wedging said carrier core 3 between two stops formed on the one hand by the front layer 7F and on the other hand by the support flange 23, as is clearly visible on Figures 3 and 6. Where appropriate, the recess 22 may follow axially to a coll. and annular protruding 24 which marks the end of the channel groove 13 (and more particularly of its lateral section 13L) on the falling edge 6, as shown in particular in Figure 5.
    [0019] The bearing flange 23 will then form a radially reentrant collar of substantially conjugate shape, which will engage under said projecting annular collar 24. It will be noted moreover that said projecting annular collar 24 may contribute to stiffening the falling edge 6 radially under the teeth meshing 2, so that the wheel 1 can better withstand oval-type deformations under meshing stress. Moreover, during the step (a) of producing the carrier core, the upper surface 5S of the flange 5 and / or the radially outer surface 6E of the flanged edge 6 is preferably given a textured structure, presenting texturing reliefs (not shown), of the striated type, the depth of which is preferably substantially between 0.1 mm and 0.5 mm. Advantageously, it will then be possible (relatively easily) during step (b) of coating, the superficial melting of said texturing reliefs to improve the adhesion of the coating layer 7 on the carrier core 3.
    [0020] Advantageously, the presence of fine texturing reliefs (shallower than pipe grooves 13, in particular), which slightly disturb the flow of the second material on the surface of the core 3, and which are more easily subject than the rest the flange 5 for heating, and therefore for crossing the glass transition temperature of the first material, will allow the second material constituting the coating layer 7 to mix more easily with the first constituent material of the core 3, and thus to improve the anchoring of the coating layer 7 on the core 3 at the interface between the two materials. Advantageously, as mentioned above, part of the energy necessary for heating the carrier core 3 may come from the hot reuse, during the coating step (b), a part of the mold having already been used for the manufacture of the carrier core 3 during step (a). The invention also relates as such to a carrier core 3 allowing and facilitating the implementation of a method according to the invention. The invention thus relates to a carrier core 3 (annular) of (first) polymeric material, which comprises, preferably in one piece, a hub 4 with a directing axis (XX '), a flange 5 which extends substantially radially from said hub 4, away from the director axis (XX '), to a peripheral flange 6 whose junction with said flange 5 forms a rounded 16, carrier core 3 which has in addition to channel grooves 13 hollowed out of (and opening on) the upper surface 5S of the flange and then in the radially outer surface 6E of the dropped edge 6, so that said channel grooves 13 extend substantially radially to the upper surface 5S of the flange 5, to the dropped edge, and then extend axially, by reference angle, along said fallen edge 6, to the radially outer surface 6E of said fallen edge 6.
    [0021] The invention also relates as such to a toothed wheel 1 obtained by a method according to one and / or the other of the described characteristics, and thus having one or the other of the corresponding structural characteristics. Finally, the invention is in no way limited to the variants of embodiment described hereinabove, the person skilled in the art being in particular able to isolate or combine freely between them one or the other of the aforementioned characteristics. , or to substitute equivalents for them.
    权利要求:
    Claims (10)
    [0001]
    REVENDICATIONS1. A method of manufacturing a toothed wheel (1), said method comprising a step (a) of producing a carrier core, during which a carrier core (3) is produced in a first polymer material, said carrier core ( 3) comprising a hub (4), with a directing axis (XX '), and a flange (5) extending substantially radially from said hub (4), away from the steering axis (XX). '), up to a peripheral edge (6), said collar (5) being delimited axially by a so-called "upper" surface (5S) oriented on the axially opposite side to the fallen edge (6), and by a surface called " lower "(51) oriented axially on the side of the dropped edge (6), said method then comprising a step (b) of coating during which is performed by molding on the carrier core (3) in a second polymer material a permanent coating layer (7) which remains permanently on the finished toothed wheel (1), said encrylate layer bage (7) comprising in one piece on the one hand a front layer (7F) which covers the upper surface (5S) of the flange (5) in axial excess of said flange, and on the other hand a side layer ( 7L) which extends axially said front layer by covering the radially outer surface (6E) of the dropped edge (6), in radial excess thickness of said fallen edge, so that said side layer (7L) forms a rim (8) in the radial thickness of which are formed meshing teeth (2) of the wheel (1).
    [0002]
    2. Method according to claim 1 characterized in that, during step (a) of producing the carrier core, forming in the carrier core (3) channel grooves (13) which extend substantially radially to the upper surface (5S) of the flange (5), up to the dropped edge, and which then extend axially, by angle, along said fallen edge (6), to the radially outer surface (6E ) of said fallen edge.
    [0003]
    3. Method according to claim 2 characterized in that the lateral sections (13L) of the channel grooves (13) along the fallen edge (6) have transverse sections with constriction (14) anti-tearing, tails type. dovetail, which reinforce the attachment of the rim (8) on said falling edge (6), in particular against centrifugal radial forces.
    [0004]
    4. Method according to one of the preceding claims characterized in that, during step (a) of producing the carrier core, the transition zone between the flange (5) and the dropped edge (6) is formed according to a rounding (16), the radius of curvature (R16) of which is preferably substantially between 2 mm and 6 mm.
    [0005]
    5. Method according to one of the preceding claims characterized in that, during step (a) of producing the carrier core, is formed on the lower surface (51) of the collar (5), to the opposite and at the axial plumb of the upper surface (5S) intended to receive the coating layer (7), a plurality of reinforcing ribs (17) arranged along several azimuths around the director axis (XX '), and which each connect the hub (4) to the lower surface (51) of the flange (5) and the radially inner surface (61) of the dropped edge (6).
    [0006]
    6. Method according to one of the preceding claims characterized in that, during step (a) of producing the carrier core (3), the hub (4), the flange (5) and the edge are produced. fell (6) in one piece, forming the carrier core (3) by overmolding on a metal connecting sleeve (10), to be fitted on a shaft, or directly by overmolding on the support shaft definitive of the toothed wheel (1).
    [0007]
    7. Method according to one of the preceding claims characterized in that, during step (a) of realization of the carrier core, the upper surface (5S) of the collar (5) is formed in axial recess of the corresponding end, said "upper end" (4S), of the hub (4), so as to form a shoulder (20) between the upper end (4S) of the hub and the upper surface (5S) of the collar, in during step (b) of coating, the front layer (7F) of coating wets said shoulder (20), and in that, following step (b) of coating, retains, on the finished wheel (1), an at least partial filling of said shoulder (20) by said front layer (7F), according to a non-zero axial thickness (E7F), preferably in such a manner that said front layer is flush axially with the upper end (4S) of the hub.
    [0008]
    8. Method according to one of the preceding claims characterized in that, during the step (a) of producing the carrier core, is formed, at the free end of the dropped edge (6), located axially to the opposite to the flange (5), a re-entrant radial recess (22), of the indentation or annular groove type, and in that, during the coating step (b), the wetting of the dropped edge (6 ) with the second polymeric material to fill said recess radial recess (22), thereby forming a support flange (23) integral with the side layer (7L), so that axially blocked l carrier web (3) in both directions within the coating layer (7) by wedging said carrier web (3) between two stops formed on the one hand by the front layer (7F) and on the other hand by the support flange (23).
    [0009]
    9. Method according to one of the preceding claims characterized in that, during step (a) of realization of the carrier core, is given to the upper surface (5S) of the collar (5) and / or to the radially outer surface (6E) of the dropped edge (6) has a textured structure, having texturing reliefs whose depth is preferably substantially between 0.1 mm and 0.5 mm, and in that, when step (b) of coating, the surface melting of said texturizing reliefs is caused to improve the adhesion of the coating layer (7) on the carrier core (3).
    [0010]
    10. Method according to one of the preceding claims characterized in that the first polymeric material, preferably thermoplastic, which is used to form the carrier core (3), is distinct from the second polymeric material, preferably thermoplastic, which is used to form the coating layer (7), and has a stiffness greater than that of said second polymer material, for example through the addition of reinforcing fibers.
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    同族专利:
    公开号 | 公开日
    FR3020305B1|2017-01-06|
    BR112016024673A2|2017-08-15|
    JP6537530B2|2019-07-03|
    EP3134246A1|2017-03-01|
    PL3134246T3|2019-02-28|
    EP3134246B1|2018-08-15|
    CN106255580B|2019-07-19|
    US10414078B2|2019-09-17|
    WO2015162388A1|2015-10-29|
    CN106255580A|2016-12-21|
    JP2017515062A|2017-06-08|
    US20170120487A1|2017-05-04|
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    法律状态:
    2015-03-17| PLFP| Fee payment|Year of fee payment: 2 |
    2015-10-30| PLSC| Search report ready|Effective date: 20151030 |
    2016-02-23| PLFP| Fee payment|Year of fee payment: 3 |
    2017-03-09| PLFP| Fee payment|Year of fee payment: 4 |
    2018-03-16| PLFP| Fee payment|Year of fee payment: 5 |
    2019-03-08| PLFP| Fee payment|Year of fee payment: 6 |
    2021-01-15| ST| Notification of lapse|Effective date: 20201214 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1453702A|FR3020305B1|2014-04-24|2014-04-24|METHOD FOR MANUFACTURING A DOUBLE SURMOULAGE TOOTHED WHEEL|FR1453702A| FR3020305B1|2014-04-24|2014-04-24|METHOD FOR MANUFACTURING A DOUBLE SURMOULAGE TOOTHED WHEEL|
    CN201580021339.2A| CN106255580B|2014-04-24|2015-04-23|The method for manufacturing light-duty gear by dual cladding molding|
    PL15725791T| PL3134246T3|2014-04-24|2015-04-23|Process for manufacturing a toothed wheel by double injection- moulding|
    JP2016564155A| JP6537530B2|2014-04-24|2015-04-23|Method for manufacturing a light gear by double overmolding|
    BR112016024673A| BR112016024673A2|2014-04-24|2015-04-23|Method for the manufacture of a double overmolded sprocket|
    PCT/FR2015/051110| WO2015162388A1|2014-04-24|2015-04-23|Method for producing a lightweight gear by double overmoulding|
    EP15725791.6A| EP3134246B1|2014-04-24|2015-04-23|Process for manufacturing a toothed wheel by double injection- moulding|
    US15/302,055| US10414078B2|2014-04-24|2015-04-23|Method for manufacturing a lightened toothed wheel by double overmoulding|
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