JP3659617B2 - Method and apparatus for plastic working of bevel gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic working method and apparatus for bevel gears. The bevel gear is mainly intended for a gear incorporated in a differential provided on a wheel shaft of an automobile. And plastic working means what is called cold forging performed by mounting a die on a press machine.
[0002]
[Prior art]
A small bevel gear for a differential rotates and revolves. Therefore, the tooth end surface on the back surface needs to escape to avoid interference with other members, and the back surface is spherical or conical for the purpose of securing an effective tooth surface. There are many documents regarding the plastic working of such bevel gears. As an example, Japanese Patent Application Laid-Open No. 61-27137 can be cited. As shown in FIG. 1 (A) of the publication, a portion having a tooth profile protrudes on the upper mold 1a side on the mating surface of the upper mold 1a and the lower mold 1b. When molding is performed such that the cavities formed by the upper and lower molds are fully filled with the mold having the projecting portion, the projecting portion is extremely worn and the mold life is shortened. And since this protruding part has to form a tooth profile, reinforcement is impossible.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a method and apparatus for obtaining a bevel gear having a predetermined shape and size without applying an excessive load to a mold.
[0004]
[Means for Solving the Problems]
In the present invention, in the initial forming step, the tooth portion on the back side of the bevel gear is formed as an incomplete formed portion, and in the next step, this incomplete portion is formed into a desired shape and size.
That is, in the first invention, the cylindrical material 1 whose lower end face is chamfered in a conical shape is inserted into a lower mold comprising a lower counter punch 14 that can be raised and lowered and a lower die 12 having a tooth shape on the inner periphery, By pressing the material 1 with an upper die composed of an upper die 11 having a flat lower end surface in contact with the upper counter punch 8 and the lower die 12, the end surface portion of the back side tooth is the end surface of a regular tooth. An initial molding step of forming an incomplete tooth molding portion 2 a having a width higher than 4c and narrow, and the obtained initial molding product 2 is divided into a die 21 having a female die on the inner periphery, and an outer periphery. This is a plastic working method of a bevel gear, which comprises a step of forming with a device provided with a spur gear meshing with the teeth of the die 21.
In the initial forming step, the upper mold for processing the cylindrical material 1 having the lower end face chamfered into the initial molded product 2 is composed of the upper counter punch 8 and the upper die 11, and the upper counter The front end portion of the punch 8 has a back surface of the initial molded product 2 and a convex portion that forms a tapered concave portion 26 on the back surface, and the lower end surface of the upper die 11 is a flat surface and is directed toward the lower die 12 by the cushion pin 10. The lower die 12 that is urged and constitutes the lower mold has a normal tooth profile on the inner periphery, and the tooth surface of the back side tooth end surface portion is narrower than the normal one and has a tall incomplete molded portion 2 a . It is a plastic working apparatus having a tooth profile for forming.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the steps of the first embodiment. That is, A, B, C, and D described below each member in the figure indicate a material, a roughing process, a drilling process, and a finishing process in order. Although a hole is formed in the molded article 4 of this embodiment, this hole may not be provided. However, the effect of the present invention is greater in the molded product having the hole than in the molded product without the hole. This point will be explained later.
[0006]
In FIG. 1, the raw material 1 is a solid cylinder, and the vicinity that is later formed into teeth is beveled obliquely. This material 1 is formed into an initial molded product 2 by a mold. The initial molded product has an incomplete molded portion 2a and a recessed portion 2b. The imperfect molding part 2a is intentionally generated in order to reduce the load on the mold.
[0007]
The AA cross section of the initial molded product 2 is shown in FIG. In FIG. 3, the imperfect molded part 2a is taller than the regular back side tooth end face 4c, has a narrow width, and has a spur gear shape, for example. That is, the balance of the material in the vicinity of the imperfect molding part 2a and the regular back side tooth end face 4c is achieved.
[0008]
The concave portion 2b is a circular hole opened to the middle of the initial molded product 2. The recess 2b is tapered. In other words, the opening of the recess is wider than the back. This is for urging the material 1 to flow toward the tooth portion. In other words, since the tooth portion is more easily formed by the concave portion 2a, the effect of the present invention is exhibited more greatly.
[0009]
The bottom of the recess 2b is punched in the next step to become the hole 3a in the punched product 3. In the punched product 3, the incomplete molded part 2 a is molded into a regular shape to become a molded product 4. The molded product 4 is provided with a chamfered portion 4b on the back side tooth end surface 4c on the back side 4a. The tooth part of the molded product 4 is formed in a predetermined shape from the tooth root 4e to the tooth tip 4d.
[0010]
FIG. 2 shows an apparatus for obtaining an initial molded product. The upper die plate 5 and the lower die plate 6 and members provided therebetween constitute a mold. The upper die plate 5 is fixed to the slide of the press machine, and the lower die plate 6 is fixed to the bolster of the press machine, and the mold is operated with the operation of the press machine, and the material 1 is molded to become the initial molded product 2. .
[0011]
In FIG. 2, an upper counter punch 8 is fixed to the upper die plate 5 with a holder 9. The tip of the upper counter punch 8 has a shape sufficient to mold the back surface of the initial molded product 2 and the recess 2b. A portion where the concave portion 2b is formed becomes thinner toward the tip. Thus, the molded recess is tapered. As described above, the taper effect facilitates the flow of the material 1 toward the tooth portion.
[0012]
An upper cylinder 7 is fixed to the upper die plate 5, and an upper die 11 is provided so as to be movable up and down by being guided by the cylinder 7 and the upper counter punch 8 on the outer periphery and inner periphery thereof.
The lower limit of the upper die 11 is regulated by a flange provided on the upper cylinder 7. The upper die 11 is urged downward by the cushion pin 10.
[0013]
A lower cylinder 13 is fixed to the lower die plate 6, and a block 15 and a lower die 12 are incorporated in the lower cylinder 13. The block 15 and the lower die 12 are pressed by a collar provided on the lower cylinder 13 and fixed to the lower die plate 6.
[0014]
A tooth profile is formed on the inner periphery of the lower die 12. This tooth profile is transferred to the material 1 to become an initial molded product 2. A space in which the material formed in the cavity formed by the upper die 11 and the lower die 12 is present at the upper portion of the incomplete molding portion 2a. Since this space exists, an excessive load is not applied to the upper die 11 and the lower die 12.
[0015]
A lower counter punch 14 is incorporated so as to be movable up and down across the block 15 and the lower die 12. The lower counter punch 14 is configured to be urged upward by a knockout pin 16. The initial molded product 2 remains on the lower die 12 after molding, but is taken out via the lower counter punch 14 by the action of the knockout pin 16.
[0016]
When the material 1 in FIG. 1 is supplied to the concave portion of the lower die 12 in FIG. 2, the material 1 is molded along with the operation of the press machine and becomes the initial molded product 2. The initial molded product 2 taken out from the lower die 12 is punched in the next step to become a punched product 3 in FIG. The hole 3 a of the punched product 3 is an extension of the concave portion 2 b of the initial molded product 2.
[0017]
FIG. 4 shows an apparatus for molding the punched product 3 to obtain the molded product 4 of FIG. The upper die plate 17 and the lower die plate 18 and the members provided between them constitute a mold. The upper die plate 17 and the lower die plate 18 are fixed to a slide and a bolster of a press machine, respectively.
[0018]
An upper punch 19 is fixed to the upper die plate 17 with an upper holder 20.
[0019]
A mandrel 23 is fixed to the lower die plate 18 with a lower holder 24. A cylindrical body 26 is fixed to the lower die plate 18, and a block 27 and a die 21 are incorporated in the cylindrical body 26. The die 21 and the block 27 are fixed to the lower die plate 18 by engaging the flanges provided on the die 21 and the cylindrical body 26.
[0020]
An outer periphery is guided over the die 21 and the block 27, and a lower punch 22 whose inner periphery is guided by a mandrel 23 is provided so as to be movable up and down. The lower punch 22 is urged upward by a knockout pin 25.
[0021]
A female shape of a bevel gear and a helical gear is formed on the inner periphery of the die 21. That is, the perforated product 3 of FIG. The upper punch 19 has a spur gear on the outer periphery and meshes with the tooth portion of the die 21, and the tip portion is shaped to mold the back side tooth end surface 4 c of the molded product 4 of FIG. 1.
[0022]
When the punch 3 shown in FIG. 1 is supplied to the recess of the die 21 and the press machine is operated, the punch 3 and the upper punch 19 and the die 21 are formed with an incomplete molding portion 2a into a regular shape. The The molded product 4 remaining on the die 21 is ejected from the die 21 via the lower punch 22 by the knockout pin 25 and taken out.
[0023]
FIG. 5 shows an apparatus for obtaining the molded product 4 by molding the punched product 3 of FIG. Accordingly, the apparatus shown in FIG. 5 corresponds to another embodiment of the apparatus shown in FIG.
[0024]
In FIG. 5, a mold is constituted by an upper die plate 28, a lower die plate 29, and members provided therebetween. An upper punch 30 is fixed to the upper die plate 28 by an upper holder 31. A cylindrical body 37 is fixed to the lower die plate 29, and a block 38 and a die 32 are incorporated in the cylindrical body 37. The die 32 and the block 38 are fixed to the lower die plate 29 by engaging the flanges provided on the die 32 and the cylindrical body 37.
[0025]
A mandrel 33 is fixed to the lower die plate 29 with a lower holder 35. The mandrel 33 has a function of constraining the inner diameter of the perforated product 3 when the punched product 3 is formed, thereby obtaining a regular dimension.
[0026]
The outer periphery is guided over the block 38 and the die 32, the inner periphery is guided by the mandrel 33, and the lower punch 34 is provided so as to be movable up and down. The lower punch 34 is urged upward by a knockout pin 36.
[0027]
The upper die plate 28 and the lower die plate 29 are respectively fixed to the slide and bolster of the press machine, and the punched product 3 supplied to the concave portion of the die 32 with the operation of the press machine has an incompletely formed part 2b as a normal one. The molded product 4 is formed into a shape.
[0028]
The die 32 in FIG. 5 has a shape in which the tooth portion protrudes upward. However, the molding performed in FIG. 5 only forms the incomplete molded portion 2b locally into a regular shape. There is no worry that a large load is applied to the teeth.
[0029]
The formed molded product 4 remains on the die 32, but is ejected through the lower punch 34 by the knockout pin 36 and taken out.
[0030]
FIG. 6 shows a process for another component to which the present invention can be applied. That is, A, B, C, and D described below each member in the figure indicate a material, a roughing process, a drilling process, and a finishing process in order. A part related to the process has a boss on the back surface of the bevel gear. The material 39 is molded into the initial molded product 40, and is punched to become a drilled product 41, and the incomplete molded portion 40b is molded into a regular shape. These processing methods and apparatuses are the same as those in the above-described embodiments.
[0031]
The operation and effect when the punched product 3 is inserted into the finishing process mold of FIG. 4 and molded will be described with reference to FIG. The portion 43 to be crushed is crushed when the upper punch 19 is lowered to the punch lowered position, and fills the die 21. At this time, if the shape and dimensions of the perforated product 3 are set so that a gap 44 is formed between the lower end of the perforated product 3 and the recess of the die 21, the tooth surface is sized during molding. Thus, a high-quality tooth surface can be obtained. Further, if the tapered recess 2b gap 45 is formed between the tapered recess 2b of the punched product 3 and the mandrel 23, the member flows into the gap 45, so that excessive stress is applied to the mold member. Does not occur.
[0032]
In the description of the embodiment of the present application, the upper and lower relations such as the upper counter punch 8 and the lower counter punch 14 have been explained. Absent.
[0033]
【The invention's effect】
In the present invention, an incomplete molded part is provided in the initial molded product, and the incomplete molded part is formed into a predetermined shape in the subsequent process, so that an excessive load is not applied to the mold. The life of the mold can be extended.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of steps in the first embodiment. FIG. 2 is a longitudinal sectional view of an apparatus for obtaining an initial molded product. FIG. 3 is a cross-sectional view of the initial molded product in FIG. FIG. 5 is a longitudinal sectional view of an apparatus according to another embodiment for obtaining a molded product. FIG. 6 is an explanatory diagram of steps when the present invention is applied to other parts. FIG. 7 is an explanatory diagram when the punched product 3 is inserted into the apparatus of FIG.
1 is a raw material, 2 is an initial molded product, 3 is a punched product, 4 is a molded product, 5 is an upper die plate, 6 is a lower die plate, 7 is a cylinder, 8 is an upper counter punch, 9 is a holder, 10 is Cushion pin, 11 is upper die, 12 is lower die, 13 is lower cylinder, 14 is lower counter punch, 15 is block, 16 is knockout pin, 17 is upper die plate, 18 is lower die plate, 19 is upper punch , 20 is an upper holder, 21 is a die, 22 is a lower punch, 23 is a mandrel, 24 is a lower holder, 25 is a knockout pin, 26 is a cylinder, 27 is a block, 28 is an upper die plate, 29 is a lower die plate, 30 is an upper punch, 31 is an upper holder, 32 is a die, 33 is a mandrel, 34 is a lower punch, 35 is a lower holder, 36 is a knockout pin, 37 is a cylinder, 38 is a block, 39 is a material, 40 is an initial component Goods, 41 AnaAkirahin, 42 moldings, site 43 is crushed, 44 gaps, 45 clearance due tapered recess, 46 a punch lowered position.

Claims (3)

A cylindrical material (1) whose lower end face is chamfered is inserted into a lower mold comprising a lower counter punch (14) that can be raised and lowered and a lower die (12) having a tooth shape on the inner periphery, by lower end face in contact with the lower die (1) and an upper counter punch (8) (12) is pressed by the upper mold consisting of a planar vertically movable upper die (11), the end face portion of the rear side tooth The initial molding step for forming an incomplete tooth molding (2 a ) that is higher than the regular tooth end face (4c) and narrow in width, and the resulting initial molding (2) A bevel gear plastic working method comprising: a die (21) having a female die and a device having a spur gear meshing with teeth of the die (21) on the outer periphery. . The method for plastic working a bevel gear according to claim 1, characterized in that a tip portion of the upper counter punch (8) has a convex portion forming a tapered concave portion (26) on the back surface of the material (1) . An upper die and a lower die for cold forging that process a cylindrical material (1) whose lower end face is chamfered into an initial molded product (2). The upper die is an upper counter punch (8). And an upper die (11), and the tip of the upper counter punch (8) has a back surface of the initial molded product (2) and a convex portion forming a tapered recess (26) on the back surface. The lower end surface of the die (11) is flat and is urged toward the lower die (12) by the cushion pin (10), and the lower die (12) constituting the lower die has a regular tooth profile on the inner periphery, Incompletely molded part (2) with a narrower and taller tooth surface on the back side tooth end face part a A plastic gearing device for bevel gears for an initial molded product.

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