JP5609291B2 - Mandrel for manufacturing internal gear and method and apparatus for manufacturing internal gear using the mandrel - Google Patents

Description

  The present invention relates to a mandrel for manufacturing an internal gear by forging, and an internal gear manufacturing method and manufacturing apparatus using the mandrel.

Patent Document 1 below discloses a method for manufacturing an internal gear that performs extrusion by cold forging. However, in the conventional manufacturing method using extrusion molding, there is a problem that, when trying to manufacture a helical gear (a gear having a twisted tooth line), a strong torsion is generated in the material during extrusion, so that sufficient molding accuracy cannot be obtained. Still, if the twist angle was 20 degrees or less, the twist of the material was suppressed by devising the shape of the introduction part (starting twist) at the beginning of extrusion, and a certain degree of molding accuracy could be maintained. In order to manufacture a helical gear of this type, the extrusion method cannot maintain accuracy and it has been impossible to form by forging. In addition, although the shaping | molding method using the meat gathering manufacturing method shown by the following patent document 2 is also proposed, this meat gathering manufacturing method has the problem that the gear tooth precision of a shaping | molding initial part is bad.
On the other hand, the manufacturing method of the internal gear shown in Patent Document 3 is a tapered shape having a certain inclination angle on the inner peripheral surface as shown in FIGS. A pressing part of the pressing device is provided so that a die b having a cylindrical hole g formed with a reduced diameter part a is provided, and a cylindrical mandrel d having a tooth mold h formed on the outer peripheral surface thereof is opposed to the die b. After the annular gear c is provided on the reduced diameter portion a of the die b, the annular punch c is provided on the outer periphery of the mandrel d so as to be movable independently of the mandrel d. 14, as shown in FIG. 15, the material e is plastically deformed inwardly along the reduced diameter portion a by reducing the mandrel d and the punch c, and the material e is deformed inside the outer surface tooth profile of the mandrel d. The internal gear is manufactured by making it intrude. As described above, according to the method of manufacturing the internal gear by causing the gear blank e to plastically deform inward along the reduced diameter portion a and enter the outer peripheral surface tooth profile of the mandrel d, the helical gear having a high helix angle is high. It becomes possible to maintain accuracy.

JP 2005-342779 A JP 11-147158 A JP 2010-64100 A

However, in the manufacturing method shown in FIGS. 13 to 15, the unpressed portion f remains in the gear material e at the time of molding, and this unpressed portion f is a portion that must be cut off by machining after molding. Therefore, there is a problem that the yield is poor and the manufacturing cost is high. In addition, in this manufacturing method, when machining an assembly part or the like on a gear material after molding, for example, with a lathe, it is difficult to align the center of the tooth profile formed by molding with the machined part, and the part that is gripped by the lathe chuck If it is bad, the accuracy of the product may be deteriorated. Furthermore, in order to employ this manufacturing method, a mechanically complex multi-axis double-acting press apparatus is required, which causes a problem that the equipment becomes expensive.
The present invention solves such problems of the prior art and enables an internal gear manufacturing mandrel and an internal tooth using the mandrel to enable high-precision internal gears to be manufactured at low cost by forging. A gear manufacturing method and a manufacturing apparatus are provided.

Therefore, the invention of the mandrel for manufacturing an internal gear according to claim 1 is a disk-shaped mandrel having a tooth shape formed on the outer peripheral surface, and the weight is borne by the magnetic force of the magnet provided in the pressing portion of the press device. Thus, the holding means is detachable so as to be separated from the pressing portion while being held coaxially inside the annular punch provided in the pressing portion, depending on the tensile force received from the gear material during molding. It is characterized by that.
Further, the invention of the method for manufacturing an internal gear according to claim 2 is provided by disposing a die having a tapered reduced diameter portion formed on an inner peripheral surface of a penetrating cylindrical hole in a press device, An annular punch is provided in the pressing portion of the pressing device facing the die, and a disk-shaped mandrel having a tooth mold formed on the outer peripheral surface is coaxial with the inner side of the annular punch, and depending on the tensile force received from the gear material during molding. The mandrel is held by being detachable from the pressing portion of the pressing device, and an annular gear material is set on the reduced diameter portion, and the annular punch and the mandrel are advanced into the cylindrical hole. Inserting into the gear blank and pressing the gear blank in the axial direction by the annular punch to plastically deform the gear blank inward along the reduced diameter portion so that the gear blank embrace the mandrel and Face teeth As the gear blank encloses the mandrel and plastically deforms, the mandrel disengages from the pressing portion of the pressing device, and then the annular punch is retracted while leaving the mandrel in the cylindrical hole. And holding the new mandrel with the same shape on the pressing portion of the press device, and setting the new gear material with the same shape on the previously set gear material and then cylindrically inserting the annular punch and the new mandrel. By moving into the shape hole, the newly set gear material embraces the new mandrel and plastically deforms, and the previously set gear material is further pressed by the newly set gear material. Further, it is characterized in that it is further plastically deformed so as to penetrate through the cylindrical hole in a state where the mandrel is embraced.
Further, the invention described in claim 3 is such that the mandrel described in claim 2 is coaxial with the inner side of the annular punch provided in the pressing portion by the weight being borne by the magnetic force of the magnet provided in the pressing portion. On the other hand, depending on the tensile force received from the gear material at the time of molding, it is held so as to be detached from the pressing portion.
According to a fourth aspect of the present invention, in the method for manufacturing an internal gear according to the second or third aspect , the mandrel is gripped without separating the mandrel from the gear material discharged while the mandrel is held. Then, the gear material is machined. This improves the machining accuracy after molding.

Further, the invention of the internal gear manufacturing apparatus according to claim 5 includes a press device, a die in which a tapered diameter-reduced portion is formed on an inner peripheral surface of a penetrating cylindrical hole, and the die. An annular punch provided in a pressing portion of the opposing pressing device and a plurality of internal gear manufacturing mandrels according to claim 1 are provided.

  According to the present invention, the internal gear can be continuously formed by a press device having a simple structure, and the production efficiency is improved, and even a helical gear with a high helix angle is formed with high accuracy and high yield, and the manufacturing cost is improved. Is reduced. Also, the machining accuracy after molding is improved.

The external appearance perspective view of the mandrel for internal gear manufacture which concerns on this invention. FIG. 2 is a longitudinal sectional view of the mandrel shown in FIG. 1. A longitudinal section when connecting a plurality of mandrels. The longitudinal cross-sectional view of the internal gear manufacturing apparatus which concerns on this invention. The operation state figure of the device shown in FIG. FIG. 6 is a further operational state diagram of the device shown in FIG. 5. FIG. 7 is a further operational state diagram of the device shown in FIG. 6. FIG. 8 is a further operational state diagram of the device shown in FIG. 7. FIG. 9 is a further operational state diagram of the device shown in FIG. 8. Schematic of the manufacturing line of the internal gear manufacturing apparatus which concerns on this invention. Schematic of the principal part at the time of machining of the internal gear concerning this invention. Schematic of the principal part at the time of machining of the internal gear concerning this invention. The longitudinal cross-sectional view of the principal part of the conventional internal gear manufacturing apparatus. The operation | movement state figure of the apparatus shown in FIG. Fig. 15 is a further operational state diagram of the device shown in Fig. 14;

  Next, an embodiment of the present invention will be described. As shown in FIGS. 1 and 2, the mandrel 1 for manufacturing an internal gear according to the present invention is a disc-shaped member made of a hard metal and having a tooth mold 2 formed on an outer peripheral surface, and a circular shape is formed at the center of the upper surface. A columnar convex portion 3 is integrally formed, and a concave portion 4 in which the convex portion 3 can be slidably fitted is formed at the center of the lower surface. Then, by fitting the convex portion 3 and the concave portion 4 to each other, as shown in FIG. 3, the plurality of mandrels 1 can be positioned coaxially and connected to each other.

  FIG. 4 shows an internal gear manufacturing apparatus using the mandrel 1, 5 is a pressing device, 6 is a die fixed to a bolster of the pressing device by a base plate 5 a, and the die has a penetrating cylindrical hollow space. A hole 7 is formed. The cylindrical hole 7 includes a large-diameter cylindrical portion 8 that continues from the upper opening edge, a tapered reduced diameter portion 9 that follows the cylindrical portion, and a small diameter that continues to the reduced diameter portion 9. The lower portion of the small-diameter cylindrical portion 10 opens into the lower space 11, and an outlet 12 is formed on the side of the lower space 11. The pressing device 5 has a simple structure in which a pressing portion 13 is fixed to the base plate 5b so as to face the die 6, and the pressing portion 13 moves forward and backward (up and down in the figure) by hydraulic pressure. An annular punch 14 having an outer diameter that can be fitted into the large-diameter cylindrical portion 8 is provided at the peripheral edge of the pressing portion 13. 15 is a recess formed coaxially in the center of the pressing portion 13 inside the annular punch 14, 16 is a magnet fixed to the inner bottom of the recess 15, and the convex portion 3 of the mandrel 1 is By inserting the mandrel 1 into the recess 15 and attracting the mandrel 1 by the magnetic force of the magnet, the mandrel 1 is held coaxially inside the annular punch 14 and detachable from the pressing portion 13. Here, the releasable holding means that the magnetic force of the magnet 16 is more than the weight of the mandrel 1 can be borne, but as will be described later, the holding force can be released depending on the tensile force received from the gear material during molding. It means that.

  Next, a forging process for manufacturing an internal gear using this apparatus will be described. The gear material W has an outer diameter slightly smaller than the large-diameter cylindrical portion 8 (diameter difference of about 0.1 mm) and an inner diameter slightly larger than the outer diameter of the mandrel 1 (diameter difference of about 0.1 mm). The gear material W is formed in an annular shape in advance, and is set on the reduced diameter portion 9 as shown in FIG. Then, as shown in FIG. 5, the annular punch 14 and the mandrel 1 are advanced into the cylindrical hole 7 by lowering the pressing portion 13, and the mandrel 1 is inserted into the gear material W. Then, the gear material W is pressed by the annular punch 14. As a result, as shown in FIG. 6, the gear material W is plastically deformed inward along the reduced diameter portion 6, and the gear material W is embraced by the mandrel 1 and enters the tooth mold 2. Thus, when the gear material W embraces the mandrel 1 and plastically deforms, the gear material W extends in the axial direction, so that the gear material W separates the mandrel 1 from the pressing portion 13 according to the deformation. That is, as the gear blank W is deformed, the mandrel 1 is pulled, and the tensile force is stronger than the holding force by the magnet 16, so that the mandrel 1 gradually moves from the pressing portion 13 as shown in FIG. break away.

  Next, as shown in FIG. 7, with the mandrel 1 remaining in the cylindrical hole 7, only the annular punch 14 is retracted once, and a new mandrel 1 ′ having the same shape is held in the pressing portion 13 by the magnet 16. . Then, a new gear material W 'having the same shape is set on the gear material W which has been plastically deformed, and the annular punch 14 and the new mandrel 1' are connected to the cylindrical hole 4 as shown in FIG. The gear material W ′ is plastically deformed in the same manner. At this time, since the previously set gear material W is further pressed by the new gear material W ′, the plastic material is further plastically deformed and penetrates the cylindrical hole 4 in a state where the mandrel 1 is embraced. As shown in FIG. Then, the gear material W discharged into the lower space 11 is taken out sideways from the outlet 12 together with the mandrel 1.

  As shown in FIG. 9, the previously set gear blank W and mandrel 1 are discharged into the lower space 11, and the newly set gear blank W 'is plastically deformed to embrace the mandrel 1' and within the tooth mold 2. 7, the mandrel 1 ′ remains in the cylindrical hole 7, and the annular punch 14 is retracted again as shown in FIG. 7, and a new mandrel having the same shape is again put on the pressing portion 13 by the magnet 16. At the same time, a new gear material having the same shape is set on the gear material W ′, and the annular punch 14 and the mandrel are advanced again into the cylindrical hole 4. Similarly, each time the annular punch 14 is moved forward / backward, a new mandrel and gear material are set as described above, and the gear material enters the tooth mold 2 to form internal teeth. The mandrel is continuously discharged into the lower space 11 in a state where the mandrel is integrally held.

  As shown in FIG. 8, when a plurality of mandrels are connected in the cylindrical hole 4, the mandrels are fitted so that the convex portions 3 and the concave portions 4 are slidable in the axial direction. As a result, the mandrels are always held coaxially, and the mandrel is always located at the center of the cylindrical hole 4. Therefore, a gap filled with the gear material is formed with high accuracy between the inner peripheral surface of the cylindrical hole 4 and the outer peripheral surface of the mandrel, and the molding accuracy can be extremely increased.

  Further, according to this manufacturing method, even a helical gear with a high helix angle can be molded with high precision, and the previously set gear material is pressed by the newly set gear material to reduce the diameter of the small diameter cylindrical portion 6. 10, the outer diameter of the gear blank discharged into the lower space 11 can be made to match the inner diameter of the small-diameter cylindrical portion 10 uniformly. For this reason, the yield is improved without producing a non-pressing portion unlike the conventional gear material, and the manufacturing cost is reduced. In addition, since this manufacturing method uses a simple press device and does not require an expensive multi-axis double-action press device having a complicated structure as in the prior art, there is an advantage that the equipment cost can be reduced.

  The gear material W integrated with the mandrel 1 taken out from the outlet 12 is moved from the forging step A to the machining step B as shown in FIG. 10, and as shown in FIG. By causing the chuck 21 of the lathe 20 to grip the convex portion 3 of the mandrel 1 and applying the cutting tool 22 to a required outer peripheral portion or end portion of the gear material W, these portions are cut. The protrusion 3 of the mandrel 1 is gripped by the chuck 21 without separating the mandrel 1 from the gear material W discharged in the state where the mandrel 1 is held in this way, and the gear material W is By machining, the concentricity between the internal teeth formed in the gear material W and the machined portion is maintained, so that machining accuracy is improved, defective products are eliminated, and high-precision internal gears are produced. It becomes easy to manufacture.

  Next, this is moved to the machining step C, the convex portion 3 of the mandrel 1 is removed and held and fixed by a mechanism (not shown), and one end face of the gear material W is pushed in the axial direction. The mandrel 1 is separated while rotating. If necessary, as shown in FIG. 12, the outer peripheral portion of the gear material W is gripped by the chuck 24 of the lathe 23, and the cutting tool 25 is applied to an end portion of the gear material W or a part of the inner peripheral surface. The end portion and inner peripheral surface of the gear material W are cut and further transferred to a deburring process D to be deburred, and then moved to an inspection process E to inspect the finished internal gear product. .

  On the other hand, the mandrel 1 separated in the machining step C is returned to the forging step A and reused. For this reason, the mandrel according to the present invention is provided with several to a dozen or more in advance for one production line, and the plurality of mandrels are circulated between the forging process A and the machining process C, thereby providing an internal gear. Can be manufactured continuously, and production efficiency can be improved.

  In this embodiment, the mandrel is held on the pressing portion 13 by the magnet 16. However, the mandrel is held by the magnetic force as in this embodiment, or a vacuum suction member is provided on the pressing portion 13 to hold the mandrel. The mandrel may be detachably held by vacuum suction and setting the suction force to be weaker than the tensile force. Alternatively, the mandrel may be detachably held by providing the pressing portion 13 with a mechanical chucking mechanism that can be set so that the holding force is weaker than the tensile force.

1, 1 'Mandrel 2 Tooth mold 3 Convex part 4 Concave part 5 Press device 6 Die 7 Cylindrical hole 8 Large-diameter cylindrical part 9 Reduced-diameter part 10 Small-diameter cylindrical part 11 Lower space 12 Outlet 13 Pressing part 14 Circular punch 15 Recess 16 Magnet 20 Lathe 21 Chuck W, W 'Gear material

Claims (5)

A disk-shaped mandrel having a tooth shape formed on the outer peripheral surface thereof, and is coaxial with the inner side of the annular punch provided in the pressing portion by bearing the weight by the magnetic force of the magnet provided in the pressing portion of the pressing device. A mandrel for manufacturing an internal gear, comprising : holding means that can be detached so as to be detached from the pressing portion depending on a tensile force received from a gear material during molding. A die having a tapered reduced diameter portion formed on the inner peripheral surface of the through-hole-shaped cylindrical hole is disposed in the press device, and an annular punch is provided in the pressing portion of the press device facing the die, and the outer peripheral surface A disc-shaped mandrel having a tooth shape formed on the inner side of the annular punch is held coaxially within the annular punch and detachable from the pressing portion of the pressing device depending on the tensile force received from the gear material during molding. An annular gear blank is set on the annular punch and the mandrel is advanced into the cylindrical hole so that the mandrel is inserted into the gear blank and the gear blank is axially moved by the annular punch. By pressing and plastically deforming the gear material inward along the reduced diameter portion, the gear material embraces the mandrel and enters the tooth mold on the outer peripheral surface, and the gear material embraces the mandrel. Plasticity As it is formed, the mandrel is released from the pressing part of the pressing device, and then the annular punch is retracted while leaving the mandrel in the cylindrical hole to form a new mandrel of the same shape in the pressing part of the pressing device. And setting a new gear material of the same shape on the previously set gear material and then advancing the annular punch and a new mandrel into the cylindrical hole. The gear material embracs a new mandrel and plastically deforms, and the previously set gear material is further pressed by the newly set gear material to further plastically deform and embed the mandrel. A method for manufacturing an internal gear, characterized in that it is discharged through a shaped hole. The mandrel described in claim 2 is held coaxially inside the annular punch provided in the pressing portion by being borne by the magnet's magnetic force provided in the pressing portion. A method for manufacturing an internal gear, wherein the internal gear is held so as to be detached from the pressing portion depending on a tensile force received . 4. The manufacturing of an internal gear according to claim 2, wherein the gear material is machined by gripping the mandrel without separating the mandrel from the gear material discharged in a state where the mandrel is held. Method. A pressing device, a die having a tapered reduced diameter portion formed on the inner peripheral surface of a through-hole cylindrical hole, an annular punch provided in a pressing portion of the pressing device facing the die, and a plurality of punches An internal gear manufacturing apparatus comprising the internal gear manufacturing mandrel according to claim 1 .

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