JP2001259782A - Crowning forming method, and crowning forming die used in the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a crowning on a tooth flank of a spur gear and a bevel gear formed by extrusion by a simple forging without using any cutting. SOLUTION: The spur gear 100 having no crowning on the tooth flank is fitted in the axial direction to one end of a cavity 17 of a cylindrical forming die 11. A tooth profile forming portion 30 which can extrude the spur gear by pressing the stock material in the axial direction is provided at the depth of the cavity 17. The groove space between the tooth flank forming surfaces of a tooth profile forming portion 30 is set to be smaller than the thickness of the tooth flank of the gear. The gear 100 is pressed by a punch 51 so that the tooth is pressed in the direction of a shaft Jg through a space between the tooth flank forming surfaces. A portion corresponding to the tooth profile forming portion 30 of the forming die 11 is elastically deformed in a contracting manner selectively when both ends 121, 122 in the axial direction of the gear 100 passes each tooth profile forming portion 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crowning forming method, and more particularly, to a spur gear or a helical gear (helical gear) manufactured by extrusion (forging) molding or the like and having no crowning formed in the tooth trace direction on the tooth surface. The present invention also relates to a method for forming crowning without cutting, and a molding apparatus used for the method.

[0002]

2. Description of the Related Art In a gear (tooth-shaped product) such as a spur gear or a helical gear, a tooth trace direction (axial direction of the gear).
The teeth may be thicker near the center and gradually thinner toward both ends, so-called crowning. This is to prevent deviation in tooth contact due to an error in the position at the time of assembling the gear parts or the gear itself. The size of the crowning depends on the gear, but 0.02-0.1m
About m is normal. When manufacturing the gear by hobbing or the like, such crowning of the tooth surface is simultaneously applied by cutting and forming the teeth by the processing machine.

[0003] Recently, a technique for manufacturing a tooth profile product by forging, not by cutting, has become widespread. The spur gear is manufactured by pressing a material in the axial direction into a molding die having a plurality of tooth forming portions parallel to the axis formed on the inner peripheral surface. In addition, the helical gear is manufactured by pressing a material in the axial direction into a mold having a plurality of tooth forming parts twisted with respect to the axis formed on the inner peripheral surface. However, when manufacturing a gear by such a method, it is not possible to crown the tooth surface during the manufacturing process. For this reason, in order to crown a tooth profile product made by forging, a separate process is required after the gear is manufactured by forging. However, there is currently no suitable way to do this.

[0004]

As described above, when gears such as spur gears and helical gears are manufactured by extrusion, not by cutting, crowning is applied to the tooth surface during the manufacturing process. Could not. Therefore, in order to add crowning, it is inevitable to add this by cutting after forging, but this not only causes an increase in cost but also makes it unnecessary to manufacture the gear by extrusion. Therefore, the tooth profile products manufactured by forging are limited to those without crowning.

[0005] The present invention has been made in view of the above-mentioned problems, and is provided by a simple forging (extrusion molding) on a tooth surface of a spur gear or a helical gear formed by extrusion or the like without cutting. An object of the present invention is to provide a crowning forming method for forming crowning, and a crowning forming die apparatus used in the method.

[0006]

According to a first aspect of the present invention, there is provided a method for forming a crowning, wherein the cylindrical forming die is provided with a punch inlet at one end of the hole. At the same time, a portion of the hole near the punch entrance is formed as a gear loading portion by forming a gear formed as a spur gear or a helical gear having no crowning on the tooth surface in such a manner that the gear can be fitted in the axial direction with a clearance fit. On the other hand, inside the hole deeper than the gear loading portion, a spur gear or a helical gear is provided with a tooth forming portion that can be extruded by pushing a material in the axial direction of the hole, and the tooth forming shape is formed. The groove spacing between the tooth flanks forming the tooth flanks of the spur gear or the helical gear in the part is smaller than the thickness of the tooth flanks of the gears loaded in the gear loading part, and the gear loading part has Before being loaded The gear is provided with guide means capable of extruding teeth between the tooth flanking surfaces of the tooth shaping part, and the gear loading part of the molding die is provided with no crowning on the tooth flanks of the teeth. After the gears are loaded, the gears are pushed in by a punch, and the teeth of the gears pass between the tooth flanking surfaces of the tooth shaping parts, and both ends of the gears in the axial direction are respectively formed by the tooth forming parts. When passing through, a portion corresponding to the tooth forming portion of the cylindrical forming die is elastically deformed to a reduced diameter to form crowning on the tooth surface of the tooth of the gear to be extruded. It is characterized by the following.

In the present invention, a gear formed as a spur gear or a helical gear and having no crowning is loaded into the gear loading portion of the molding die, and the gear is pushed in the axial direction to form the tooth-forming portion. To form crowning on the tooth surface. In the tooth forming portion, the groove interval between the tooth forming surfaces is smaller than the thickness of the tooth surface of the gear. Therefore, when the gear is loaded, the tooth forming portion (upper end) acts as a stopper. When the two ends of the gear each pass through this tooth-forming part, the diameter of the tooth-forming part is elastically deformed to reduce the diameter of the tooth-forming part. Is formed thinner (plastically deformed) than the central portion, and thus crowning is formed in the tooth trace direction. Thus, according to the present invention, crowning can be formed on a gear that is formed as a spur gear or a helical gear and does not have crowning in the tooth trace direction of the tooth surface without cutting, so that a spur gear formed by forging is used. The crowning can be easily formed on the gear or the helical gear.

[0008] In the present invention, the tooth forming portion may include:
Although the groove spacing between the tooth flanks forming the tooth flanks was made smaller than the thickness of the tooth flanks of the gears loaded in the gear loading part, in order to form crowning on the tooth flanks, The tooth-forming portion may be such that the contour of the hole in a cross section perpendicular to the axis of the hole is generally smaller than the contour of the tooth profile of the gear.

That is, in the tooth forming portion, the groove interval between the tooth forming surfaces forming the tooth surfaces is smaller than the thickness of the tooth surfaces of the gears loaded in the gear loading portion, and the tooth forming surfaces between the tooth forming surfaces are different from each other. The diameter of the circle passing through the groove bottom of the gear may be smaller than the diameter of the tooth tip of the gear, and the diameter of the circle passing through the tip face forming the root of the gear to be loaded may be smaller than the diameter of the root of the gear. By doing so, the thickness of the teeth at both ends in the tooth width direction (axial direction of the gear) is smaller than that at the center, and the tip circle and the bottom circle are also smaller, but crowning in the tooth trace direction is performed. Is still attached.

According to the present invention, when the gear is passed through the tooth forming portion of the hollow of the cylindrical mold, the diameter of the tooth forming portion is selectively reduced when both ends of the gear pass. This is a method of forming and giving crowning to a gear by plastic working by elastically deforming a cylindrical forming die to have a diameter. Therefore, the size of the crowning can be adjusted by adjusting the amount of diameter reduction of the tooth forming portion. In addition, the thickness and length of the cylindrical mold may be set together with the material so that the tooth forming portion can be elastically deformed to a desired amount in a reduced diameter.

[0011] As the guide means, internal teeth having a shape corresponding to the profile of the tooth profile of the gear to be loaded are provided inside the gear loading section, and grooves between the internal teeth of the gear loading section are provided; It is preferable to connect the grooves between the tooth surface forming surfaces of the tooth forming portion with each other.

In the above-mentioned crowning forming method, a large-diameter portion (land) is provided on the outer peripheral surface corresponding to the tooth forming portion of the cylindrical forming die, and the wedge collides with the large-diameter portion. An outer ring body provided with a diameter-reducing pressing portion projecting from the inner peripheral surface at an interval above and below is provided so as to move together with the punch so that the cylindrical molding die can be reduced in diameter by the action, and is loaded. When the gears are pushed by the punch and both ends thereof pass through the tooth forming part,
It is preferable that the pressing portion for diameter reduction collides with the large diameter portion to elastically deform the portion corresponding to the tooth forming portion in a reduced diameter shape.

The crowning mold apparatus according to the fourth aspect of the present invention is as follows. That is, the cylindrical mold has a punch entrance into which a punch is pushed in at one end of the hole, and a portion of the hole near the punch entrance has a spur gear or helical gear without crowning on the tooth surface of the teeth. The gear formed as described above is formed so as to be able to be loaded in a gap-fitting manner in the axial direction, and is used as a gear loading portion. On the other hand, inside the hole deeper than the gear loading portion, there is a material in the axial direction of the hole. The spur gear or the helical gear is provided with a tooth forming part that can be extruded by pushing in, and the groove interval between the tooth flank forming surfaces forming the tooth flank of the spur gear or the helical gear in the tooth forming part is a gear. The thickness of the tooth surface of the gear loaded in the loading portion is smaller than the thickness of the tooth surface of the gear loaded in the gear loading portion. And possible guidance means On the other hand, a punch which can be pushed into the tooth surface of the tooth without being crowned and which is loaded into the gear loading part of the molding die is provided, and the tooth of the gear is the tooth of the tooth forming part. A process of passing between the tooth-forming surfaces, wherein when both ends in the axial direction of the gear each pass through the tooth-forming portion, the two ends correspond to the tooth-forming portion in the cylindrical forming die. A molding die diameter reducing means for elastically deforming a portion to be deformed into a reduced diameter is provided.

As the guide means in this molding apparatus, the above-mentioned guide means can be said to be preferable. Also,
As the molding die diameter reducing means, a large diameter portion is provided on the outer peripheral surface corresponding to the tooth forming portion of the molding die having a cylindrical shape. An outer ring body provided with a diameter-reducing pressing portion projecting from an inner peripheral surface of the molding die at an interval above and below is provided so as to move together with the punch, and the loaded gear is used for the punching. When the both ends are pushed through the tooth-forming portion, the diameter-reducing pressing portion collides with the large-diameter portion so that the portion corresponding to the tooth-forming portion is elastically deformed to a reduced diameter. It is good to Note that the distance between the upper and lower diameter reducing pressing portions protruding from the inner peripheral surface is determined by the tooth width of the gear to be processed (the length of the tooth measured in the axial direction of the gear). When each of the ends passes through the tooth forming part, each diameter reducing pressing part is located on the large diameter part, and an effective diameter reducing action is given to the tooth forming part of the cylindrical forming die. It may be set as follows.

[0015]

1 shows an embodiment of a crowning molding method and a crowning molding apparatus according to the present invention.
This will be described in detail with reference to FIGS. FIG. 1 is a longitudinal sectional view showing a schematic configuration of the molding apparatus 1 before pressing.
As shown in the figure, in the molding apparatus 1 of the present embodiment, a lower mold 10 including a lower molding die (die) 11 and an upper mold 50 including an upper punch 51 are vertically coaxially mounted. They form a set of molding apparatus (die). The components of such a mold are made of alloy tool steel or the like.

A steel plate (hereinafter, also referred to as a lower plate) 13 which is disposed below and has a flat plate shape is fixed so as not to move up and down, and a circular hole is formed in the center of the lower plate 13. A molding die 11 having a substantially cylindrical shape is attached to the center of the upper surface 14 in an upright manner. At the upper end of a hole (space) 17 of the molding die 11,
A spur gear (hereinafter, referred to as “figure”) shown in FIG.
The inner contour is formed to be slightly larger than the work 100 so that the gear 100 or the work 100 can be loaded in a clearance fit manner in the direction of the axis Jg. However, as shown in FIGS. 5 and 6, in this embodiment, a plurality of internal teeth 21 are formed inside the gear loading portion 20 in parallel to the axis Jk so as to correspond to the contour of the work tooth profile. But this internal tooth 2
1 and the internal teeth 31 of the tooth forming section 30 described below are not shown in the drawings for explaining the molding process for easy understanding.

Inside the hole 17 at the back (downward) of the gear loading section 20, there is provided a tooth forming section 30 in which a spur gear can be formed by extrusion. That is,
The tooth forming part 30 is formed such that a spur gear can be extruded by pushing a material in the direction of the axis Jk of the hole 17. The tooth forming part 30 forms the tooth surface of the spur gear in the tooth forming part 30. The interval between the grooves 34 between the surfaces 33 is
Is smaller than the thickness of the tooth surface 133, and the diameter is also reduced. That is, the circle D11 passing through the groove bottom 35 between the tooth surface forming surfaces 33 is made smaller in diameter than the tip circle D21 of the work 100, and the circle D11 passing through the tip end surface forming the work bottom is formed.
12 is smaller in diameter than the work root circle D22. In the drawing, the gear loading section 20 and the tooth forming section 30 are connected via a tapered surface 29, but the dimensional relationship is exaggerated. However, the groove 34 between the tooth surface forming surfaces 33 and the groove 24 between the internal teeth 21 inside the gear loading portion 20 are connected in parallel to the axis Jk, and the gear 1
When 00 is loaded into the gear loading section 20 and pressed by the punch 51, the teeth 110 serve as guide means passing through the grooves 34 between the tooth flanks 33 in the tooth forming section 30.

Further, inside the hole 17 below the tooth forming portion 30, the work 10
Its inner contour is formed slightly larger than 0, and is a relief space 27 through which the gears can be inserted in a clearance-fitting manner. That is, when the gear is loaded into the gear loading unit 20 and pushed by a punch 51 described below and deformed in the tooth forming shape unit 30 and pushed downward to reach the relief space 27, the empty space of the lower plate 13 is released. It is configured to drop down from the hole 15. The inner peripheral surface of the relief space 27 may not have internal teeth.

The molding die 11 has a straight cylindrical shape having a diameter D36 and substantially the same diameter.
A large-diameter portion (hereinafter, also referred to as a land) 37 having a predetermined width with a diameter D37 slightly larger than other portions is provided around the inner peripheral surface at a height corresponding to the tooth forming portion 30. . The land 37 has a cylindrical surface parallel to the axis Jk, and has an upper tapered upper tapered surface (hereinafter also referred to as a land upper tapered surface) 37a at the upper end and a lower tapered lower surface at the lower end. Tapered surface (hereinafter, also referred to as land-under tapered surface) 37
b, each of which is continuous with the outer peripheral surface 36. In addition,
The upper taper surface 37a and the lower taper surface 37b have the same taper, and the angle of the generatrix of the taper with respect to the axis Jk (one-side angle of the taper) is set, for example, in the range of 0.5 to 15 degrees.

On the other hand, a steel plate (hereinafter, also referred to as an upper plate) 53 which is disposed above the mold 11 and has a flat plate shape is configured to be movable up and down via a mechanism (not shown). Then, the lower surface 5 of the upper plate 53
4, a column-shaped punch 51 having a fixed diameter is attached vertically with its upper end surface fixed. In addition,
The punch 51 is formed to have a slightly smaller diameter than its inner diameter so that it can be pushed into the hole (mold cavity) of the cylindrical mold 11 described above.

An outer ring formed on the lower surface 54 of the upper plate 53 is coaxial with the punch 51 and has an inner diameter D60 larger than the diameter D37 of the cylindrical surface of the land 37 on the outer peripheral surface 36 of the molding die 11 to form a cylindrical shape. A body 60 is attached in a hanging manner with its upper end surface fixed. However, on the inner side (inner peripheral surface) of the lower part of the outer ring body 60, two upper and lower protrusions projecting toward the axis Jk side are formed in a ring shape while maintaining a predetermined interval K vertically. The diameter reducing pressing portions 63 and 64 are configured to reduce the diameter of the cylindrical molding die 11 by colliding with the lands 37 by wedge action. The pressing portions 63 and 64 for reducing the diameter are formed into tapered surfaces 63 a and 64 that are downwardly spread at a predetermined taper angle.
a. Of these, the tapered surface of the lower pressure reducing portion 63 (hereinafter also referred to as the lower tapered surface of the lower diameter pressing portion) 6
3a and the minimum diameter D6 of the tapered surface 64a of the upper diameter-reducing pressing portion 64 (hereinafter, also referred to as the lower tapered surface of the upper diameter-reducing pressing portion).
3 is smaller than the diameter D37 of the cylindrical surface of the land 37 on the outer peripheral surface 36 of the molding die 11, and these tapered surfaces 6
The maximum diameter portions 3a and 64a are the same as the diameter D60 of the inner peripheral surface 61 of the outer ring body 60, and the diameter D37 of the cylindrical surface of the land 37.
Has been made larger. The angle on one side of each of these tapers in the outer ring body 60, that is, the angle between the axis Jk and the generatrix, is also set in the range of, for example, 0.5 to 15 degrees.

A taper surface 63b (hereinafter, also referred to as an upper taper surface) having an upwardly spreading shape is formed on the minimum diameter portion of the lower diameter reducing pressing portion 63.
A tapered surface (hereinafter, also referred to as an upper tapered surface of the upper diameter-reducing pressing portion) 64b that forms an upward spread is formed on the minimum diameter portion of the upper diameter-reducing pressing portion 64, and the lower diameter-reducing pressing portion 63 is formed. Tapered surface 63a and lower tapered surface 64 of upper pressure reducing portion 64
The taper is substantially the same as each taper of a. In addition, the inner diameter of the portion of the inner peripheral surface 61 of the outer ring body 60 other than the lower-diameter pressing portion 63 and the upper-diameter pressing portion 64 is made larger than the outer diameter D37 of the land 37. 60 is a mold 11
It is made of alloy tool steel etc. much thicker than its thickness.

When the outer ring body 60 is lowered together with the upper plate 53 without loading the gear into the loading section 20, the lower tapered surface 63a of the lower diameter reducing pressing portion 63 collides with the land upper tapered surface 37a. . When further depressed, the lower tapered surface 63a of the lower diameter reducing pressing portion 63 slides down while giving a wedge action to the land upper tapered surface 37a,
The molding die 11 is elastically deformed to have a reduced diameter so that the molding die 11 is narrowed around a portion corresponding to the land 37. The minimum diameter portion of the lower tapered surface 63a of the lower diameter pressing portion 63 is the land 3
7, the deformation (diameter reduction of the molding die) is maximized, the outer ring body 60 is further lowered, and the lower diameter reduction pressing portion 63 is reached.
When the upper end portion or the minimum diameter portion of the upper tapered surface 63b reaches the land lower tapered surface 37b, the diameter of the molding die 11 decreases and returns to the original size, and when it becomes lower than the land lower tapered surface 37b. Since the large diameter portion 65 having the diameter D60 above the lower diameter pressing portion 63 of the outer ring body 60 is located outside the land 37, the narrowing of the molding die 11 is released, and the tooth forming shape portion 30 is included. The diameter is set so as to resiliently return to the dimension in the no-stress state. That is, until the lower tapered surface 63a of the lower diameter reducing pressing portion 63 collides with and exceeds the land 37, the molding die 11 is elastically deformed in a reduced-diameter manner centering on the height portion of the tooth forming portion 30. The inner peripheral surface of the tooth forming portion 30 is configured to be reduced in diameter by the deformation.

When the outer ring body 60 further descends, the lower tapered surface 64a of the upper diameter reducing pressing portion 64 becomes the land upper tapered surface 37.
a, the lower tapered surface 63a of the lower diameter reducing pressing portion 63 collides with the land 37, as in the case of the upper diameter reducing pressing portion 64.
Until the lower tapered surface 64a collides with and exceeds the land 37, the molding die 11 is elastically deformed to have a reduced diameter, and the tooth forming portion 30 is set to be reduced in diameter. And
When the upper end portion of the upper diameter reducing pressing portion 64 or the minimum diameter portion of the upper tapered surface 64b is below the land lower tapered surface 37b,
The narrowing of the mold 11 is set to be released.

The lower tapered surface 6 of the lower diameter reducing pressing portion 63
An interval (pitch) K between the lower taper surface 64a and the upper diameter reducing pressing portion 64 is set somewhat smaller in accordance with the tooth width of the gear (work) to be processed. After the work 100 is loaded into the gear loading section 20 of the molding die 11 in this way, the work 100 is pushed in by the punch 51 and the tooth 1
10 is a process of passing between the tooth flank forming surfaces 33 of the tooth shaping portion 30, and only for a certain time during which both ends 121, 122 in the direction of the axis Jg of the workpiece (the portions near both ends) pass through the tooth shaping portion 30. The upper and lower pressing portions 63 and 64 are configured to collide with the land 37 and elastically deform the portion corresponding to the tooth forming portion 30 into a reduced diameter. The punch 51 starts pressing the work 100 when the lower tapered surface 63a of the lower diameter reducing pressing portion 63 of the outer ring body 60 collides with the land 37 and starts reducing the diameter of the tooth forming portion 30. The height (length) dimension is set so that it can be extruded (punched) out of the molding portion 30 into the escape space portion 27. Further, the diameter D37 of the land 37 and the pressing portions 63, 64 for reducing the diameter are set in accordance with the required size of the crowning or in such a manner that the deformation is obtained to the extent that the desired crowning is obtained.
The minimum diameter of the tapered surface may be designed.

As shown in FIGS. 7 and 8, the gear 100 extruded into, for example, a gear shape without crowning is inserted into the gear loading portion 20 of the molding die 11 while the mold is open.
Is loaded such that its teeth 110 mesh with the internal teeth 21 in the gear loading section 20. At this time, the teeth 11 of the gear 100
0 is a groove 34 between the tooth flanking surfaces 33 of the tooth forming profile 30
(See FIG. 6), but the width of the groove 34 and the diameter D11 and D12 of the tooth forming part 30 are smaller than the thickness and the diameter D21 and D22 of the tooth surface 133 of the gear 100 loaded. It stops at the tapered surface 29 at the upper end of the tooth forming part 30.

Next, as shown in FIGS. 9 and 10, the upper plate 53 is lowered and the outer ring body 60 is pressed down by the lower diameter pressing portion 63.
The lower taper surface 63a collides with the land 37 and starts to reduce the diameter of the tooth forming portion 30. At about the same time, the punch 51 starts to press the gear 100 in the direction of its axis Jg. That is, the lower tapered surface 63a of the lower diameter reducing pressing portion 63 is
7, during the initial stage of pressing until it exceeds the land 37, that is, when the one end (lower end) 121 of the work 100 is pushed into the tooth forming portion 30, it is elastically deformed to have a reduced diameter. For this reason, in the pushing process, the tooth thickness of the tooth 110 in the tooth width direction corresponding to the lower end portion 121 becomes thinner than the central portion. In this embodiment, both ends 121 and 122 in the face width direction (the axial direction of the gear) are used.
, The tip circle and the root circle are also reduced.

Subsequently, when the upper plate 53 is lowered and the lower tapered surface 63a of the lower diameter reducing pressing portion 63 exceeds the land 37, the outer ring body 60 is narrowed by the lower taper surface 63a of the lower diameter reducing pressing portion 63. The force gradually decreases, and the outside of the land 37 is located near the enlarged diameter portion 65 of the outer ring body 60 as shown in FIG. At this time, since the narrowing of the molding die 11 is released, the diameter of the tooth forming portion 30 increases accordingly.
In the process in which the narrowing of the molding die 11 is released, the intermediate portion 123 of the gear 100 in the tooth width direction passes through the tooth forming portion 30. Therefore, the tooth thickness of the teeth (not shown) of the intermediate portion 123 of the gear 100 becomes larger than the tooth thickness of the end portion 121 in the tooth width direction that has passed through the tooth forming portion 30 first.

When the upper plate 53 is further lowered, FIG.
As shown in FIGS. 2 and 13, the lower tapered surface 64a of the upper diameter reducing pressing portion 64 collides with the land 37 and the tooth forming portion in the same manner as when the punch 51 starts pushing the gear 100. 30 while reducing the diameter of the tooth forming profile 30
The upper end 122 of the work 100 is pressed by the punch 51 in the inside, and finally pushed out to the escape space 27 as shown in FIG. That is, the upper end portion 122 of the workpiece 100 is elastically deformed to have a reduced diameter during the end of pressing until the lower tapered surface 64a of the upper diameter reducing pressing portion 64 collides with the land 37 and exceeds the land 37. Since the tooth is pushed into the portion 30, the tooth thickness of the end portion 122 in the width direction of the tooth 110 of the gear 100 is reduced in the pushing process. Therefore,
The thickness of the tooth 110 corresponding to both end portions 121 and 122 in the tooth width direction of the gear 100 extruded in this manner is thinner than that of the intermediate portion 123, so that crowning is formed in the tooth trace direction of the tooth surface. You. When the gear 100 has passed through the tooth forming portion 30, the land 37 is located at the enlarged portion (D60) above the upper diameter reducing pressing portion 64, and the narrowing of the molding die 11 has been released.

After the crowning is formed, the upper plate 53 is pulled up to complete one process. In addition,
In the lifting step of the upper plate 53, the upper diameter reducing pressing portion 6 is used.
The upper tapered surface 64b and the upper tapered surface 63b of the lower-diameter pressing portion 63 successively collide with the lower tapered surface 37b of the land 37 to continuously deform the molding die 11 elastically.

That is, in the present invention, the gear 100 extruded into a gear shape without crowning is pushed again into the molding die 11 without cutting, so that the tooth surface of the teeth 110 of the gear 100 is formed. The crowning can be formed in the direction of the tooth trace. In this embodiment, the gear 1
The portions 121 and 122 near both ends in the tooth width direction of 00 are not only the tooth surface in the direction along the tooth trace than the intermediate portion 123,
The crown is also crowned, but there is no problem as a gear.

In the above-described embodiment, as the molding die diameter-reducing means, the entire contour of the inner peripheral surface of the tooth forming portion 30 in the molding die 11 is smaller than the contour of the teeth 110 of the gear 100. For the formation of crowning,
As shown in FIG. 15, the interval between the grooves 34 between the tooth flanks 33 in the tooth shaping part 30 may be smaller than the thickness of the tooth flanks of the gear 100 loaded in the gear loading part 20.

In the above-described embodiment, the case where the spur gear is formed has been described. Therefore, the tooth forming part 30 used was a forming die having a linear tooth forming part parallel to the axis Jk. The same can be applied to the molding of the helical gear. That is, in forming a helical gear having no crowning, the tooth forming portion may be twisted with respect to the axis Jk. At this time, when the internal teeth 21 are provided as the guide means of the gear loading section 20 as described above, the internal teeth may be twisted similarly to the helical gear.

The lower tapered surface 6 of the lower diameter reducing pressing portion 63
The distance (distance) K between 3a and the lower tapered surface 64a of the upper diameter reducing pressing portion 64 depends on the tooth width of the gear to be processed, and each end in the width direction of the gear passes through the tooth forming portion. At this time, the upper and lower diameter reducing pressing portions may be set so as to be located on the land. The amount and time of the diameter reduction may be set in accordance with the timing of the start and end of the compression of the gear by the punch so that the effective diameter reducing action is applied to both ends of the gear.

The guide means only needs to be able to push the loaded gear through the tooth-forming surfaces of the tooth-forming portion, so that the gear-loading portion is formed by the tooth-forming portion. If the inner diameter of the gear loading portion is substantially the same as the diameter of the addendum circle of the gear, one internal tooth that meshes with the gear tooth can be used. The present invention is not limited to those described above, and can be embodied with appropriate modifications without departing from the gist thereof.

[0036]

As is apparent from the above description, according to the present invention, crowning is formed by extruding a tooth surface of a spur gear or a helical gear formed by extrusion or the like without cutting. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of a crowning mold apparatus according to the present invention before pressing.

FIG. 2 is an enlarged longitudinal sectional view of a main part of a lower die (molding die) of FIG. 1;

FIG. 3 is an enlarged longitudinal sectional view of a main part of the upper die of FIG. 1;

FIG. 4A is a front view of a gear without crowning on a tooth surface, and FIG. 4B is an end view thereof.

FIG. 5 is an enlarged vertical cross-sectional view illustrating a state in which the internal teeth of the gear loading portion and the tooth forming portion are formed parallel to the axis in the lower die of FIG. 2;

FIG. 6 is a plan half sectional view of FIG. 5;

FIG. 7 is a longitudinal sectional view before a press in which a gear is loaded in a gear loading section.

8 is an enlarged longitudinal sectional view of a main part of FIG. 7;

FIG. 9 is a vertical cross-sectional view when the gear loaded in the gear loading unit is started to be pressed.

FIG. 10 is an enlarged longitudinal sectional view of a main part of FIG. 9;

FIG. 11 is an enlarged longitudinal sectional view of a main part in a state where the punch is further pushed in from the state of FIG. 10;

FIG. 12 is an enlarged longitudinal sectional view of a main part in a state where the punch is further pushed in from the state of FIG. 11;

FIG. 13 is an enlarged longitudinal sectional view of a main part of a state in which the punch is further pushed in from the state of FIG. 12;

FIG. 14 is an enlarged longitudinal sectional view of a main part in a state where the punch is further pushed in from the state of FIG. 13;

FIG. 15 is a plan half sectional view showing another form of the tooth forming part.

[Explanation of symbols]

1 Crowning mold equipment. REFERENCE SIGNS LIST 11 molding die 17 hole 19 punch entrance 20 gear loading portion 21 internal teeth (guide means) of gear loading portion 30 tooth forming portion 33 tooth forming surface of tooth forming portion 34 groove between tooth forming surfaces 36 groove of molding die Outer peripheral surface 37 Large diameter portion (land) of outer peripheral surface corresponding to tooth forming portion of molding die 51 Punch 60 Outer ring body 61 Inner peripheral surface of outer ring body 63, 64 Press for reducing diameter of inner peripheral surface of outer ring body Part 100 Gears without crowning on tooth flank 110 Gear teeth 121, 122 Both ends in axial direction of gear 133 Gear flank Jg Spur gear shaft Jk Axis line of hole K Interval between upper and lower pressing parts for diameter reduction

Claims (6)

[Claims] 1. A cylindrical mold has a punch entrance into which a punch is inserted at one end of a hole thereof.
The portion near the punch entrance in the hole is formed so that a gear formed as a spur gear or a helical gear without crowning on the tooth surface of the tooth can be loaded in the axial direction with a clearance fit so as to be a gear loading portion. Inside the hole deeper than the gear loading portion, a spur gear or a helical gear is provided with a tooth forming portion that can be extruded by pushing a material in the axial direction of the hole, and The groove spacing between the tooth flanks forming the tooth flanks of the spur gear or the helical gear is set to be smaller than the thickness of the tooth flanks of the gear loaded in the gear loading part. Said gear
Guide means are provided so that the teeth can be extruded between the tooth flanking surfaces of the tooth shaping part, and the gear loading part of the molding die is loaded with the gear without crowning on the tooth flanks of the teeth. Then, the gear is pushed by a punch, and the teeth of the gear pass between the tooth flanks of the tooth shaping part, and both ends in the axial direction of the gear each pass through the tooth shaping part. In this case, a portion corresponding to the tooth forming portion of the cylindrical forming mold is selectively elastically deformed to have a reduced diameter, thereby forming a crowning on the tooth surface of the tooth of the extruded gear. Crowning molding method. 2. As the guiding means, an internal tooth having a shape corresponding to the profile of the tooth profile of the gear to be loaded is provided inside the gear loading section, and a groove between the internal teeth of the gear loading section is provided. 2. The crowning forming method according to claim 1, wherein grooves are formed between the tooth surface forming surfaces of the tooth forming portion. 3. A large-diameter portion is provided on the outer peripheral surface corresponding to the tooth forming portion of the cylindrical molding die, and the large-diameter portion collides with the large-diameter portion to reduce the cylindrical molding die by wedge action. The outer ring body provided with a diameter-reducing pressing portion protruding from the inner peripheral surface at an interval vertically is provided so as to move together with the punch, and the loaded gear is pushed by the punch. As each of the two ends passes through the tooth forming part,
3. The crowning forming method according to claim 1, wherein the diameter-reducing pressing portion collides with the large-diameter portion to elastically deform the portion corresponding to the tooth forming portion into a reduced-diameter shape. 4. A cylindrical mold has a punch entrance into which a punch is pushed at one end of a hole thereof,
The portion near the punch entrance in the hole is formed so that a gear formed as a spur gear or a helical gear without crowning on the tooth surface of the tooth can be loaded in the axial direction with a clearance fit so as to be a gear loading portion. Inside the hole deeper than the gear loading portion, a spur gear or a helical gear is provided with a tooth forming portion that can be extruded by pushing a material in the axial direction of the hole, and The groove spacing between the tooth flanks forming the tooth flanks of the spur gear or the helical gear is set to be smaller than the thickness of the tooth flanks of the gear loaded in the gear loading part. Said gear
Guide means are provided which allow the teeth to be extruded between the tooth flanking surfaces of the tooth shaping part, while the tooth flanks of the teeth loaded in the gear loading part of the mold have no crowning. A step of providing a punch capable of pushing the gear, wherein the teeth of the gear pass between the tooth surface forming surfaces of the tooth forming portion, and both ends in the axial direction of the gear are each formed of the tooth forming shape. A crowning means for selectively reducing the diameter of a portion corresponding to the tooth forming portion of the cylindrical molding die when passing through a portion, the diameter of the portion corresponding to the tooth forming portion being reduced. Molding equipment. 5. As the guide means, an internal tooth having a shape corresponding to the profile of the tooth profile of the gear to be loaded is provided inside the gear loading portion, and a space between the tooth surface forming surfaces of the tooth forming profile portion is provided. The crowning mold apparatus according to claim 4, wherein the groove and the groove are connected. 6. A large diameter portion is provided on an outer peripheral surface corresponding to a tooth forming portion of a cylindrical molding die as said molding die diameter reducing means, and wedge action is performed by colliding with said large diameter portion. An outer ring body provided with a diameter-reducing pressing portion projecting from an inner peripheral surface of the cylindrical mold so as to be able to reduce the diameter of the molding die at an interval above and below is provided so as to move together with the punch, and is loaded. When the gear is pushed by the punch and its both ends pass through the tooth forming part, the diameter reducing pressing part collides with the large diameter part and the part corresponding to the tooth forming part is reduced in diameter. 6. The crowning mold apparatus according to claim 4, wherein the crowning mold apparatus is elastically deformed.