JP2007167862A - Die for producing gear with crowning, method for producing such die, and method for producing gear with crowning by using such die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die for producing a gear with crowning with which the dimensional precision after forge-forming can be improved, a method for producing such die and a method for producing the gear with crowning with such die. <P>SOLUTION: Before crowning processing, a core 11 having an inner tooth gear-state tooth-shape of no crowning on the inner peripheral surface, has an increasing volume part for interference for processing the crowning on the outer peripheral surface. Such core before crowning processing is pressed into the tapered inner wall surface of a ring 10 in the axial direction of the ring, and the crowning processing is performed to produce the die 3 for gear with the drowning. Further, the core before crowning processing, having the cylindrical outer peripheral surface can be crowning-processed by pressing into the inner wall surface with the crowning, of the ring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold for manufacturing a gear with crowning suitable for use in a power transmission mechanism of an automobile, a method for manufacturing such a mold, and a method for manufacturing a gear with crowning using such a mold. .

  To avoid noise and vibration due to abnormal biting during loading, the external gear tooth profile is molded with a crowning that gradually reduces the tooth thickness from the center to the end of each tooth. Yes.

  A method and an apparatus for molding a tooth profile with crowning of such an external gear used in an automobile with a mold are known.

  For example, Patent Document 1 describes a forging method for a crowned tooth profile in which a coarse tooth, which is an external gear with a constant tooth thickness, is molded into a crowned tooth profile.

  In this method, the teeth of the rough material are inserted into the first space from the lower end by pressing the upper punch to form the crowning from the lower end of the tooth to the central portion, and the first space and the second space of the upper die are smoothly connected. After the lower die and the upper die are brought into close contact, the coarse material held in the lower die is inserted into the second space from the upper end by pressing the lower punch, and the crowning is formed from the upper end of the tooth to the central portion.

  Patent Document 2 describes a method of manufacturing a tooth mold with crowning.

In the method described in Patent Document 2, a primary mold in which inner teeth are formed with a substantially equal tooth thickness over the entire length is elastically deformed to a small diameter, and the side surfaces of the outer teeth are formed in a crowning shape in the primary mold. The crown tooth electrode is aligned, the crown tooth electrode is reciprocated in the circumferential direction at a predetermined angle, and the side surface shape of each tooth of the primary mold is subjected to electric discharge machining so as to correspond to the side surface shape of the tooth of the crown tooth electrode. After processing, the temporary mold is elastically restored, and the crown tooth electrode is removed from the processed product in the axial direction to produce a finish mold in which the side surfaces of the inner teeth have an anti-crown shape.
JP 2003-220442 A JP 2003-80338 A

  An object of the present invention is to provide a mold for manufacturing a gear with crowning that can improve the dimensional accuracy after forging, a method for manufacturing such a mold, and a gear with crowning by such a mold. It is to provide a method of manufacturing.

  Examples of the solving means of the present invention are as follows.

  (1) A mold in which a core press-fitted into a tapered inner wall surface of a ring has an internal gear-like tooth profile with a crowning formed by press-fitting.

  (2) A mold characterized in that a core press-fitted into an inner wall surface with a crowning of a ring has an internal gear-like tooth profile with a crowning formed by press-fitting.

  (3) The axial relative position between the core and the ring can be adjusted. By adjusting the relative axial position between the core and the ring, the shape of the crowning of the tooth profile of the internal gear of the core can be corrected. A mold as described above, characterized in that it is possible.

  (4) A core having an internal gear-like tooth profile without crowning on the inner peripheral surface is press-fitted into the inner wall surface of the ring in the axial direction of the ring, and at that time, the inner peripheral surface of the core is deformed, A method of manufacturing a mold for a gear with a crowning, characterized in that a crowning process is performed on the tooth profile of the inner peripheral surface of the core.

  (5) A core having an internal gear-like tooth profile without crowning on the inner peripheral surface has an increase portion for tightening on the outer peripheral surface, and such a core has a tapered shape of the ring. The crowned gear is characterized in that it is press-fitted into the inner wall surface in the axial direction of the ring, the increased portion disappears and becomes tapered, and accordingly, the toothing of the inner peripheral surface of the core is crowned. A method of manufacturing a mold.

  (6) A core having an internal gear-like tooth profile with no crowning on the inner peripheral surface has a cylindrical outer peripheral surface, and such a core is placed in the inner wall surface of the ring with the crowning axis. A method of manufacturing a mold of a gear with a crowning, wherein the die is pressed in a direction and crowning is performed on the tooth profile of the inner peripheral surface of the core.

  (7) The method described above, wherein the shape of the crowning is adjusted by adjusting the amount of press-fitting of the core in the axial direction of the ring.

  (8) A method of manufacturing a gear with crowning by the above-mentioned mold.

  (9) Maintain the same tooth thickness as the initial tooth profile by cold forging the gear before crowning, or reduce the tooth thickness within 10% or less of the initial tooth profile. And at the same time, projecting the tip of the tooth from the initial tooth profile.

  (10) The aforementioned method, wherein the accuracy of the gear before crowning is JIS grade 5 or higher.

  (11) The above-described method, wherein the gear before crowning is stretched and then extruded.

  (12) When cold forging a gear that is a workpiece, the end surface of the tooth profile formed on the outer periphery of the knockout sleeve supports the end surface of the tooth profile of the gear that is the workpiece, and knocks out the entire gear end surface. A method for cold forging a gear, characterized by supporting the entire end face of the sleeve.

  According to the invention, the mold consists of a ring and a core press-fitted into it. The inner wall surface of the ring has a tapered shape, a crowning shape, and other shapes. Crowning is performed on the inner peripheral surface of the core. For example, a core having an internal gear-like tooth profile without crowning on the inner peripheral surface is press-fitted into the inner wall surface of the ring in the axial direction of the ring, and at that time, the outer peripheral surface of the core is deformed, and accordingly Then, crowning is performed on the tooth profile on the inner peripheral surface of the core.

  In one preferred form of the invention, the ring has a tapered inner wall and the core press-fit therein has an internal gear-like tooth profile with a crowning formed by press-fitting.

  According to another preferred embodiment of the present invention, the ring has an inner wall surface with a crowning, and the core press-fitted therein has an internal gear-like tooth profile with a crowning formed by press-fitting.

  In particular, the relative position of the core and the ring in the axial direction can be adjusted, and by adjusting the relative position of the core and the ring in the axial direction, the shape of the crowning of the tooth profile of the core internal gear is corrected. Preferably it is possible.

  In one preferred method of manufacturing a crowned gear mold according to the present invention, a core having an internal gear-like tooth profile without crowning on the inner peripheral surface is used as a fastening margin for attaching crowning to the outer peripheral surface. With a weight increasing portion, such a core is press-fitted into the tapered inner wall surface of the ring in the axial direction of the ring. At that time, the increased portion disappears and becomes tapered, and accordingly, the inner peripheral surface of the core is crowned.

  In another preferred method of manufacturing a crowned gear mold according to the present invention, a core having an internal gear-like tooth profile without crowning on the inner peripheral surface has a tapered or cylindrical outer peripheral surface, Such a core is press-fitted into the inner wall surface of the ring with the crowning in the axial direction of the ring, and crowning is performed on the inner peripheral surface of the core.

  An important point for increasing the accuracy of crowning is to enable adjustment of the relative position of the core and the ring in the axial direction, that is, adjustment of the press-fitting amount of the core in the axial direction of the ring. It is preferable to adjust the shape of the crowning (especially the diameter of the pitch circle or the like in the region to be crowned) by adjusting the amount of press-fitting of the core in the axial direction of the ring.

  When a gear with a crowning is manufactured by the above-described mold, a desired high-accuracy crowning shape can be easily and reliably processed.

  It is preferable to process the gear before crowning in the form of protrusion by cold forging. For example, the tooth thickness is maintained substantially the same as the tooth thickness of the initial tooth profile of the gear before crowning, or the tooth thickness is reduced within a range of 10% or less than that of the initial tooth profile, and at the same time than the initial tooth profile. Stick out the teeth. Then, an extremely high precision crowning shape can be processed easily and reliably.

  In that case, it is preferable that the precision of the gear before crowning is JIS grade 5 or higher.

  It is preferable that the forging machine used when crowning the gear is capable of precise load control.

  It is preferable that the crowning mold has a structure in which the amount of crowning can be adjusted, the structure of the mold is simple, and a popular forging machine can be used.

  In addition, the crowning shape can be manufactured with high accuracy, surely and inexpensively as follows.

(1) Production of core before press-fitting First, an internal gear-like tooth profile (initial tooth profile) without crowning is formed on the inner wall surface of the sleeve-shaped or ring-shaped core by wire-cut electric discharge machining and lapping is performed.

  The outer wall surface of the core has a tapered shape corresponding to the tapered hole of the ring at the front half. The latter half of the core, to which crowning is to be applied, has a shape obtained by adding an additional amount for tightening to the tapered shape. In this way, if the desired shape is added to the taper shape so as to add an increase portion for tightening, when the core is press-fitted into the taper hole of the ring, the increase portion disappears and becomes a tapered shape. A desired crowning can be formed in the initial tooth profile of the inner wall surface of the core. The shape of the increase portion for fastening allowance can be easily processed with a numerically controlled cylindrical polishing machine.

(2) Assembling the core into the ring with a taper hole Adjusting the amount of press-fitting of the core into the ring with a taper hole even if there is some processing error in the initial tooth profile of the inner wall surface and the taper shape of the outer wall surface Therefore, the shape of the crowning (for example, a dimension such as a diameter) can be adjusted in units of 1 micron. While measuring the processed crowning shape, it is necessary to repeatedly adjust the press-fitting amount of the core into the ring with the tapered hole and press the core into the ring, so that the desired value is surely obtained.

(3) Correction for die dimensional change during crowning by cold forging There are cases where die distortion due to forging load and die size due to spring bag of workpiece (crowning gear) and dimensional difference between workpieces may occur. is there. In this case, it is possible to correct the crowning shape (especially dimensions such as diameter) of the mold. That is, such a dimensional difference can be easily adjusted by shifting the relative positions of the core and the tapered hole ring in the axial direction. If this adjustment is small, it can be adjusted simply by adjusting the forging load.

(4) Heat treatment distortion and tooth surface roughness of gear with crowning (workpiece) It is preferable to perform annealing to remove internal stress immediately before performing crowning molding. By doing so, the heat treatment distortion becomes small.

  The roughness of the tooth surface can be finished to a roughness of 1 to 6 microns, for example, by additionally setting a fine grain spraying process (liquid honing) performed after the heat treatment.

(5) Correspondence to general crowned gears After one side half is crowned as described above, the workpiece (gear with only one side half crowned) is inserted as necessary, and the other half is inserted. The half of the side is crowned. In this case, in order to avoid the loss of accuracy due to deformation of the previously formed crowning portion, it is preferable to reduce the outer diameter of the pressure pin and increase the distance from the teeth. In this way, the crowning load can be set to the minimum necessary.

  In another preferred form of the present invention, the structure of the mold formation start portion is such that a low tooth having a lower tooth depth than a normal full tooth has a multi-stage structure before a normal tooth having a normal full tooth shape. It is preferable to be formed in the shape of Further, it is preferable that a fiber escape step is formed in the middle of the low teeth so as to be retracted inward from the end of the first inclined surface of the tooth forming start portion.

  In addition, when forming the tooth profile with crowning by cold forging the initial tooth profile of the gear before crowning, it is almost the same as the tooth thickness of the initial tooth profile by cold forging before forming the completed tooth profile by sizing. It is preferable to maintain a tooth thickness or to reduce the tooth thickness within a range of 10% or less than the tooth thickness of the initial tooth profile, and at the same time to intervene a process of protruding the tooth tip from the initial tooth profile.

  In the best mode of the present invention, at the time of the above-described extrusion step, after the metal material is extruded in one mold, the crowning is further formed by drawing as a sizing for finishing.

  Further, in any of the above-described embodiments, except for the final stage, the closed forging is not performed, that is, in each of the plurality of cold forgings, before the tooth tip portion of the processed product reaches the tooth root of the die. It is preferable to stop the molding in order to avoid an increase in the molding load.

  In yet another embodiment of the present invention, the metal material overhang and protrusion are divided into two steps, performed in separate molds, and further combined with a sizing (finish drawing) step.

  The above-mentioned forming consisting of overhang and protrusion is fine forging, mainly due to compressive load. In molding (precision forging) consisting of such overhangs and protrusions, the molding proceeds radially from both end faces. Therefore, it is pressed against the mold, and excessive surface pressure and strong friction do not occur in the local part of the mold.

  The direction of the forming load and the form of plastic flow are preferably as described below. A load is applied from both upper and lower end faces to cause plastic flow symmetrically. This is called a split flow forging method. In this case, the sagging (unformed part) of the outer peripheral part of the workpiece is small. If only one side is cut, it can be easily finished to a desired dimension as a finished product, thereby reducing the cutting cost. Less material is required. The type life number can be 5-7 times that of a general one.

  Since the molding composed of the overhang and the protrusion according to the present invention is a kind of transfer form, the difference in surface pressure is relatively small. Moreover, the local wear of the mold is slight. There is little distortion of the mold. Since it can be molded to reflect the accuracy of the machined surface of the mold, high accuracy and good surface roughness can be obtained. As a result, the accuracy and surface roughness of the workpiece can be made almost the same as the mold.

  By performing overhang, extrusion, sizing molding, annealing, and lubrication coating in order as needed, it is possible to obtain high precision and good surface roughness and good characteristics at the same time, greatly improving the die life. Therefore, the effect of cost reduction and quality variation reduction is great.

  In the present invention, it is preferable to use a precision forging machine (in particular, a precision forging machine that uses a servo motor to control the speed at the time of molding to reduce the impact load fluctuation). Furthermore, it is preferable to reduce the distortion of the machine due to the forging load and increase the rigidity of the forging machine. For example, a strain gauge is used to measure the load generated in the forging machine.

  Moreover, it is preferable to use a material with good plasticity.

  A high-precision electric discharge machine is used to manufacture a die for precision cold forging, and a high-precision NC cutting machine and machining program are used.

  Further, preferably, a surface hardening film treatment is performed in order to extend the precision life of the mold.

  According to the present invention, the three-dimensional dimension of the tooth profile of the crowned gear can be made within a tolerance of 1 to 8 microns.

  Preferred conditions for crowning molding are as follows.

1) The accuracy of the gear just before crowning is JIS grade 5 or higher.

2) The accuracy of the gear width, hole diameter, hole eccentricity, squareness, parallelism, surface roughness, etc. of the gear immediately before crowning molding is equal to or higher than that of a JIS class 5 gear.

3) The hardness of the gear just before crowning molding is within the range where plastic working is possible.

4) The accuracy and rigidity of the mold shall satisfy the required accuracy of the gears under the load of the molding load.

5) The forging machine can set the upper limit value and the lower limit value of the molding load and can be precisely controlled.

6) The forging machine has the accuracy and rigidity necessary for maintaining the accuracy of the workpiece.

7) The work piece should have a lubricating coating. This is because the coefficient of friction is stable and the variation in workpiece accuracy is reduced. In addition, since the molding load is reduced, the distortion of the mold is reduced and the mold life is extended.

  FIG. 1 illustrates one preferred embodiment of the present invention.

  In FIG. 1, a forging machine 1 includes a holder 2, a mold 3 disposed inside the holder 2, a support member 4 that supports and fixes the mold 3 from below in the holder 2, and a central axis. And a punch sleeve 6 and a knockout sleeve 7 which are provided so as to be movable in the vertical direction around the mandrel 5.

  The mold 3 is an assembly of a ring 10 and a core 11. A core 11 is press-fitted into the ring 10. The ring 10 has a tapered inner wall surface 10a (corresponding to a tapered hole). The core 11 is press-fitted into the tapered inner wall surface 10a of the ring 10 in the axial direction (downward in FIG. 1), and is fixed to a desired position in an adjustable manner.

  With reference to FIGS. 1 and 2, this point (a point that can be adjusted and fixed) will be described in detail.

  With reference to FIG. 2, first, the core 11 before crowning will be described.

  An internal gear-like tooth profile 11a having no crowning is formed on the inner wall surface of the core 11 by a wire-cut electric discharge machine (not shown) to create an initial tooth profile. This initial tooth profile is preferably lapped.

  As shown in FIG. 2, the outer wall surface 11b of the core 11 before crowning has a tapered front half part 11c on the inlet side, and a rear half part 11d following the rear part is on an extension line of the front half part 11c. It is a shape obtained by adding an increasing portion for tightening to the imaginary taper shape by the dimension of A.

  The increased portion is necessary for the crowning process, and can be formed in an arc shape having a large radius R as shown in FIG.

  As shown in FIG. 2, the internal gear-like tooth profile 11a of the core 11 before crowning has a pitch circle with a predetermined diameter D1 in the latter half portion 11d.

  On the other hand, the taper inclination angle (B) of the inner wall surface 10a (corresponding to the taper hole) of the ring 10 is set to 1 ° to 2 °. It is preferable that the taper inclination angle of the outer peripheral surface of the front half portion 11C of the core 11 before the above-mentioned crowning is exactly the same as the taper inclination angle (B) of the inner wall surface 10a of the ring 10.

  The core 11 having such a shape is press-fitted along the axial center (downward in FIG. 2) into the tapered inner wall surface 10a (that is, the tapered hole) of the ring 10.

  As described above, the core 11 having the internal gear-like tooth profile 11a without crowning on the inner peripheral surface has an increasing portion for fastening for attaching the crowning to the rear half portion 11d of the outer peripheral surface 11b. The core 11 is press-fitted into the tapered inner wall surface 10a of the ring 10 in the axial direction of the ring 10, the increased portion disappears, and the entire outer peripheral surface 11b of the core 11 becomes tapered. Crowning is performed on the tooth profile 11 a on the inner peripheral surface of the core 11.

  FIG. 3 shows a state in which the crowning process is performed as described above (same as the state in FIG. 1), that is, the core 11 is fixed to a desired position of the tapered inner wall surface 10 a (tapered hole) of the ring 10 so as to be adjustable. Indicates the state.

  In FIG. 3, the core 11 is sandwiched between two ring-shaped adjusting members 12 and 13 and fixed at a desired position in the tapered inner wall surface 10 a of the ring 10. If the fixing position of the core 11 changes, the crowning shape changes. By adjusting the thickness H of the lower adjustment member 12, the position of the core 11 in the ring 10 can be adjusted in the vertical direction. For example, first, the thickness H of the lower adjustment member 12 is set to be slightly larger than a predetermined value, the core 11 is press-fitted into the ring 10 in the state of FIG. 3, and the crowning shape is measured. After that, they are disassembled and reassembled using the adjustment member 12 having a small thickness H. In this way, the core 11 is slightly shifted to a position below the inner wall surface 10 of the ring 10. As a result, the shape of the crowning changes. In particular, the diameter D2 of the pitch circle at the point corresponding to the lower end of the workpiece (17) (point indicated by a black circle in FIG. 3) decreases.

  Thus, by repeating the fine adjustment of the thickness H of the lower adjustment member 12, a desired accurate crowning shape can be obtained.

  Reference numeral 15 denotes a presser member that is fastened to a predetermined position 18 on the upper end surface of the ring 10 with a bolt (not shown) in order to press and fix the upper adjustment member 13 downward.

  The material of the core 11 is preferably high-speed steel or die steel, and is preferably quenched and tempered so that the core 11 has a hardness of HRc 58 to 65.

  Further, the thickness W of the core 11 is about 10% of the diameter D2 of the pitch circle at a point (point indicated by a black circle in FIG. 3) corresponding to the lower end of the processed gear (17), for example, D2 is 60 mm. In this case, the thickness is preferably 6 to 9 mm.

  As shown in FIG. 3, the tooth profile 11a on the inner peripheral surface of the core 11 includes a guide portion 11e and a throttle portion 11f formed on the inlet side. The guide portion 11e is provided for copying the mouth of the core 11. The diameter of the pitch circle of the guide portion 11e is preferably slightly larger than the diameter of the pitch circle of the workpiece (17) before being extruded. For example, it may be 0.05 to 0.2 mm larger. The axial length of the guide portion 11e is preferably 5 times or more that of the tooth module.

  The diaphragm portion 11f is provided continuously at the end of the guide portion 11e. The tooth profile of the narrowed portion 11f is a regular tooth profile with crowning.

  When the completed tooth profile of the workpiece (17) is formed, first, the metal material is stretched and formed by the guide portion 11e, and then the extrusion portion is formed by the narrowed portion 11f. As a result, a precise tooth stripe can be formed.

  The gear 17 to be processed is preferably supplied through the guide portion 11e because it can be supplied easily and accurately, and is preferably supplied directly to the narrowed portion 11f having a regular crowned tooth profile.

  The extruded tooth surface is used as a copying surface, and the metal material is extruded and formed by 0.05 to 0.2 mm by the narrowed portion 11f. As a result, the tooth profile error can be extremely reduced.

  With the mold 3 in the assembled state shown in FIG. 3 set in the forging machine 1 as shown in FIG. 1, a gear before crowning, preferably a gear 17 without crowning of JIS grade 5 or higher is used as a workpiece. First, the half of one side is subjected to crowning by cold cutting with the mold 3.

  After that, if necessary, the gear 17 is reversed and reinserted into the mold 3, and the other half is crowned.

  As shown in FIG. 1, it is preferable that the outer periphery near the upper end of the knockout sleeve 7 has a tooth profile 7a corresponding to the lower end of the crowned tooth profile of the gear 17 after processing.

  When the tooth profile 7a is present in this way, the upper end of the tooth profile 7a slightly enters the lower end of the tooth profile 11a of the core 11 of the mold 3 (the state shown in FIG. 1), and the gear 17 of the workpiece is crowned. Therefore, the lower end surface of the tooth profile portion of the gear 17 is supported by the upper end surface of the tooth profile 7a of the knockout sleeve 7 during processing. As a result, the lower end surface of the gear 17 after processing becomes a desired plane as a whole including the tooth profile portion, and it is not necessary to perform cutting in a subsequent process.

  When the crowning process is completed, the punch sleeve 6 first rises, and then the knockout sleeve 7 rises with the processed gear 17 placed thereon. The processed gear 17 is taken out from the mold 3 at a predetermined raised position.

  FIG. 4 shows another embodiment of the present invention. The embodiment of FIGS. 1 to 3 and the embodiment of FIG. 4 are the same except for the mold.

  In the embodiment of FIG. 4, the mold 3 has a ring 20 and a core 21. Before crowning, the core 21 having an internal gear-like tooth profile without crowning on the inner peripheral surface has a cylindrical or tapered outer peripheral surface without crowning, and the core 21 before such crowning is The ring 20 is press-fitted into the inner wall surface 20a with the crowning in the axial direction of the ring 20 (downward in FIG. 4). At that time, the outer peripheral surface of the core 21 is deformed into a crowning shape along the inner wall surface 20 a with the crowning of the ring 20, and accordingly, the tooth profile 21 a on the inner peripheral surface of the core 21 becomes the inner wall surface 20 a with the crowning of the ring 20. Along with the crowning shape. In this way, the crowning process is performed on the tooth profile 21 a on the inner peripheral surface of the core 21.

  In the assembled state of FIG. 4, the front half 21c of the region of about two-thirds of the outer peripheral surface 21b of the core 21 is formed in a taper shape, and the subsequent rear half 21d is formed in a crowning shape.

  The tooth profile 21a on the inner peripheral surface of the core 21 has a guide part 21e and a restricting part 21f corresponding to the guide part 11e and the restricting part 11f in the embodiment of FIGS. The operations of the guide portion 21e and the narrowed portion 21f are the same as those in the embodiment shown in FIGS.

  3 to 4 indicate positions in a state where the gear 17 that is the workpiece is crowned. In this state, the gear 17 is located inside the narrowed portions 11f and 21f of the teeth 11a and 21a on the inner peripheral surfaces of the cores 11 and 21. At the time of the first crowning, the lower half of the tooth profile of the gear 17 is crowned, and the upper half of the tooth profile of the gear 17 is not crowned.

  In addition, this invention is not limited to the above-mentioned Example.

  For example, the illustrated initial tooth profile of the core 11 has a two-stage shape in order to form an overhang and a protrusion, but other shapes may be used.

  Further, the present invention is not limited to the embodiment in which the tooth profile 7a is provided in the knockout sleeve, but may be a shape that does not support the tooth profile portion of the gear 17 after processing. Thus, when the tooth profile 7 a does not exist in the knockout sleeve 7, the tooth profile portion at the lower end of the gear 17 that is the workpiece is not supported by the knockout sleeve 7 during the crowning process. In this case, the lower end of the workpiece gear 17 is cut as necessary.

  Also, when cold forging a gear that is a workpiece, the end surface of the tooth profile formed on the outer periphery of the knockout sleeve supports the end surface of the tooth profile of the gear that is the workpiece, and the entire gear end surface is knocked out. The cold forging method for gears supported by the entire end face of the present invention is not limited to the above-described mold with crowning, but can be applied to various molds without crowning.

The schematic longitudinal cross-sectional view which shows the condition which crowns a gear by cold forging using the type | mold by one Example of this invention. The longitudinal cross-sectional view which shows the state before the assembly of the type | mold shown in FIG. The longitudinal cross-sectional view which shows the state after the assembly of the type | mold shown in FIG. The longitudinal cross-sectional view which shows the state after the assembly | attachment of the type | mold by other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Forging machine 2 Holder 3 Mold 4 Support member 5 Mandrel 6 Punch sleeve 7 Knockout sleeve 10 Ring 10a Inner wall surface 11 of ring 10 Core 11a Tooth profile 11b formed on inner peripheral surface of core 11 Outer peripheral surface 11c of core 11 Core 11 The first half portion 11d The second half portion 11e of the core 11 The guide portion 11f of the core 11 The throttle portion 12 of the core 11 The adjustment member 13 The adjustment member 15 The pressing member 17
18 Center line 20 indicating the position of the fastening bolt 20 Ring 20a Inner wall surface 21 of ring 20 Core 21a Tooth profile H of inner peripheral surface of core 21 Thickness of adjusting member

Claims (12)

  A mold characterized in that a core press-fitted into a tapered inner wall surface of a ring has an internal gear-like tooth profile with a crowning formed by press-fitting.   A mold characterized in that a core press-fitted into an inner wall surface with a crowning of a ring has an internal gear-like tooth profile with a crowning formed by press-fitting.   The relative position of the core and ring in the axial direction can be adjusted. By adjusting the relative position of the core and ring in the axial direction, the crowning shape of the tooth profile of the core's internal gear can be corrected. The mold according to claim 1, wherein the mold is formed.   A core having an internal gear-like tooth profile without crowning on the inner peripheral surface is press-fitted into the inner wall surface of the ring in the axial direction of the ring. At that time, the outer peripheral surface of the core is deformed, and accordingly the core A method of manufacturing a mold for a gear with a crowning, characterized in that a crowning process is performed on the tooth profile of the inner peripheral surface of the gear.   A core having an internal gear-like tooth profile with no crowning on the inner peripheral surface has an increased portion for tightening on the outer peripheral surface, and such a core is formed on the tapered inner wall surface of the ring. A gear mold with a crowning is characterized in that it is press-fitted in the axial direction of the ring, the increased portion disappears and becomes a tapered shape, and the toothing of the inner peripheral surface of the core is accordingly crowned. How to manufacture.   A core having an internal gear-like tooth profile without crowning on the inner peripheral surface has a cylindrical outer peripheral surface, and such a core is press-fitted into the inner wall surface with the crowning of the ring in the axial direction of the ring. A method for manufacturing a mold of a gear with a crowning, wherein the tooth profile on the inner peripheral surface of the core is crowned.   The method according to any one of claims 4 to 6, wherein the shape of the crowning is adjusted by adjusting the press-fitting amount of the core in the axial direction of the ring.   The method to manufacture a gear with a crowning with the metal mold | die of any one of Claims 1-3.   By cold forging the gear before crowning, the tooth thickness is maintained substantially the same as the tooth thickness of the initial tooth profile, or at the same time the tooth thickness is reduced within a range of 10% or less than the tooth thickness of the initial tooth profile. The method according to claim 8, wherein the tooth tip is protruded from the initial tooth profile.   The method according to any one of claims 8 to 9, wherein the accuracy of the gear before crowning is JIS grade 5 or higher.   The method according to any one of claims 8 to 10, wherein the gear before being crowned is stretch-molded and then extrusion-molded. When cold forging the gear that is the work piece, the end face of the tooth profile formed on the outer periphery of the knockout sleeve supports the end face of the gear tooth shape that is the work piece, and the entire end face of the gear is the end face of the knockout sleeve. A cold forging method for gears characterized by overall support.

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