JP3031848B2 - Bevel gear forging method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for manufacturing a bevel gear such as a bevel gear used for a differential device of an automobile by forging.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a bevel gear forging apparatus comprising a lower die having a lower punch, and an upper die having an upper punch which is configured to be able to approach and separate from the lower die.
In order to manufacture a bevel gear using this forging device, a cylindrical work cut to a predetermined length is placed in a cavity formed in the lower die, and the lower punch and the upper punch are used to mount the work. Is pressed, the workpiece is set on the wall constituting the cavity between the upper mold and the lower mold, and is molded. This method is generally called a double pressing forging method.

On the other hand, a lower die having a lower punch and an upper die which can be freely moved toward and away from the lower die are provided, and a work placed on the lower die is pressed by the lower punch to form a cavity in the work. There has also been proposed a single-pressing forging method of setting up a wall portion to be formed.

However, in the forging method of the double-pressing die described above, burrs are liable to be generated due to the forging material which goes around the gap between the lower die and the lower punch and the gap between the upper die and the upper punch. A removal step is required. Further, in the single-pressing forging method, it is difficult to sufficiently plastically deform the work, and there is a disadvantage that molding defects are apt to occur, such as the occurrence of underfill.

In order to overcome this kind of inconvenience, a lower mold having a lower punch, and an upper mold having a predetermined tooth profile, which is configured to be able to approach and separate from the lower mold, is provided. A preform is applied to form a preform having a shape similar to a bevel gear, and the preform is supported by a lower punch,
The upper mold is pressed against the lower mold to clamp the preform in a closed state, and the lower punch is pressed against the preform to set the preform on the wall constituting the cavity,
A method for obtaining a bevel gear has also been proposed.

Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-100758, the upper end of the work is projected to a predetermined height from the end face of the first mold, and the second mold is moved to the first mold. Displacing the upper end of the workpiece plastically to close the first mold and the second mold, and displace the punch in the axial direction relative to the first mold and the second mold. There has been proposed a method of manufacturing a bevel gear by swaging the work on a wall portion forming a cavity of the first mold and the second mold.

Further, as disclosed in Japanese Patent Application Laid-Open No. 7-236937, there is provided an upper die provided with an upper punch, and a lower die provided with a lower punch so as to be displaceable. Under the action, the upper part of the work is pressed with the upper punch to apply the primary forging pressure, and the flow is displaced to at least the bottom of the bevel gear of the bevel gear for manufacturing the forged material, and the lower punch is pressed into the cavity to press the work and the secondary is pressed. There has been proposed a method of manufacturing a bevel gear by applying a forging pressure and flowing and displacing the bevel gear to the tip of a bevel gear for manufacturing a forged material.

[0008]

In the forging method of a bevel gear according to the prior art described above, when the upper die is pressed against the lower die, the tooth profile formed on the upper die is replaced with the tooth profile of the preformed product. To deform it. For this reason, a strong force is applied to the tooth profile of the upper die, and there is a concern that the tooth profile formed on the upper die may be damaged, and there is a problem that the durability of the upper die is shortened.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and does not damage the tooth profile formed on the upper die, improves the durability of the upper die, and removes burrs during forging. An object of the present invention is to provide a method and an apparatus for forging and forming a bevel gear, which does not cause generation and defective formation.

[0010]

In order to achieve the above object, the present invention provides a method for forming a bevel gear by forging, comprising: The preformed product having the shape formed is engaged with the lower mold having the male and female shapes corresponding to the male and female shapes of the bevel gear, and the preformed product is separated from the lower punch with the lower mold. The positioning step, the lower mold and the upper mold are brought into contact with each other, the upper punch abuts on the upper part of the preform, and the tooth shape formed on the upper mold and the preform are in a non-contact state. And a step in which the lower punch and the preform are held in a non-contact state to close the lower mold and the upper mold with each other, and the lower mold, the upper mold, and the upper mold provided on the upper mold. The lower punch is moved forward with respect to the lower punch by moving the punch relatively to the lower punch. Characterized in that it and a step of forming swaging presses the preform by entering the image made cavities between the lower mold and the upper mold.

According to the present invention, when the preform is placed on the lower mold, the preform is separated from the lower punch. When the upper mold is lowered with respect to the preform, and the upper mold and the lower mold are closed to each other, the upper punch abuts on the upper part of the preform, and the tooth shape formed on the upper mold is separated from the preform. Therefore, no impact is applied when the upper mold and the lower mold come into contact with the tooth profile. When the lower punch relatively enters the cavity, the preformed product inside the cavity is pressed and plastically deformed, and flows into the upper tooth profile without gaps to form a bevel gear.

In this case, on the lower surface side of the preformed product,
The male and female shapes on the bottom side without the toothed surface of the bevel gear to be manufactured are molded, the lower mold has a male and female shape corresponding to the male and female shapes of the bevel gear, and the lower mold has the preformed product. It is preferable that the lower surface side of the preform is engaged with the lower die when placing the preform.

[0013] The present invention also provides an apparatus for forming a bevel gear by forging, comprising: a lower die having a male and female shape corresponding to a male and female shape on the bottom side of the manufactured bevel gear without a toothed surface. An upper die having female and male teeth corresponding to the male and female teeth of the bevel gear to be manufactured, the upper die being freely movable toward and away from the lower die, and provided in a hole defined in the lower die. A lower punch relatively displaceable with respect to the lower mold,
An upper punch provided in a hole defined in the upper die,
When the preform is placed on the lower mold, the male and female shapes on the bottom side without the toothed surface of the preform are engaged and positioned with the male and female shapes of the lower mold, and the lower mold and When the upper mold is closed, the upper punch abuts on the upper part of the preform, and the tooth form formed on the upper mold does not contact the preform, and the lower punch is And the preform are held in a non-contact state, and the preform is pressed by the lower mold, the lower punch, the upper mold, and the upper punch to perform swaging.

According to the present invention, the preform is placed on the lower mold while the preform and the lower punch are separated from each other.
When the upper mold is lowered to close the upper mold and the lower mold, the tip of the upper punch contacts the upper part of the preform, and the tooth shape formed on the upper mold and the preform are held in a non-contact state. Because
No impact is applied to the tooth profile when the upper and lower dies abut. When the lower punch relatively enters the cavity, the preform is plastically deformed and flows into the tooth profile of the upper die without a gap, thereby forming a bevel gear.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a forging method of a bevel gear according to the present invention will be described in detail below with reference to the accompanying drawings.

In this embodiment, a case where a bevel gear used for an automobile is manufactured will be described as an example.

In FIG. 1, reference numeral 10 indicates a bevel gear forging apparatus according to the present embodiment. The bevel gear forging apparatus 10 includes a lower mold mounting member 12. A hydraulic unit 14 is provided at the center of the lower mold mounting member 12, and a pressure oil is supplied from a pressure oil supply source (not shown) to a chamber 16 defined inside the hydraulic unit 14. Room 1
6 is provided with a pressing member 18 that can move up and down, and the pressing member 18 is pressed upward by the pressure oil in the figure. A step 20 is formed on the upper part of the pressing member 18, and a pressing member 22 fixed on the upper part of the hydraulic unit 14 is engaged with the step 20. Accordingly, upward movement of the pressing member 18 is suppressed by the pressing member 22. A tubular member 24 is provided at the center of the hydraulic unit 14, and the upper end of the tubular member 24 is fitted into a concave portion 26 defined at the center of the pressing member 18. A knockout pin 30 is inserted into the central hole 28 of the tubular member 24. A cylindrical member 31 having the same diameter as the knockout pin 30 abuts on the upper portion of the knockout pin 30, and a groove 33 is defined on an outer wall of the cylindrical member 31, and an O-ring 35 is provided in the groove 33. . The knockout pin 30 and the columnar member 31 protrude further upward from a hole 32 defined in the upper part of the recess 26. A cylindrical lower punch 34 smaller in diameter than the cylindrical member 31 is fixed to the upper end of the cylindrical member 31.
The tip portion 36 of 4 has a tapered shape with its diameter reduced upward.

On the upper part of the lower mold mounting member 12, a support 38 is provided.
a and 38b are erected, and coil springs 40a and 40b are provided so as to surround the columns 38a and 38b. The upper ends of the coil springs 40a and 40b are in pressure contact with the holding plate 42. In fact, the columns 38a, 38b are slidably inserted into the holes 44a, 44b defined in the holding plate 42, whereby the holding plate 42 can move up and down along the columns 38a, 38b. is there. Therefore,
The coil springs 40a and 40b are connected to the lower
It can be easily understood that the holding plate 42 and the holding plate 42 are urged in a direction away from each other. A large hole 46 having a step is defined at the center of the holding plate 42, and a punch holder 48 is fitted into a lower portion of the large hole 46. The punch holder 48 has a flange 50 formed thereon. A pressing member 52 is engaged with the flange portion 50, and the pressing member 52 is fitted to a lower portion of the holding plate 42, so that the punch holder 48 is held by the holding plate 42. At the center of the punch holder 48, a concave portion 54 in which the cylindrical member 31 is slidable is defined.
A hole 56 having a diameter smaller than that of the concave portion 54 is defined in the upper portion of the lower punch 34, and the lower punch 34 is slidably inserted into the hole 56.

A lower mold 58 is provided so as to be stacked on the punch holder 48. Actually, a step portion 60 is formed on the outer wall of the lower die 58, and a positioning member 62 is engaged with the step portion 60, and the positioning member 62 is fixed to the upper portion of the holding plate 42, thereby lowering the lower die 58. 58 is positioned and fixed to the holding plate 42. A hole 64 communicating with the hole 56 coaxially is defined at the center of the lower mold 58, and the lower punch 34 is relatively slidably inserted into the hole 64. The positioning member 6 of the lower mold 58
A step 66 is provided on the upper surface of the outer peripheral edge protruding from 2, and the step 66 has a tapered shape whose diameter is slightly reduced upward. A mounting portion 68 is formed at a central portion of the lower mold 58,
The mounting portion 68 is reduced in diameter downward and communicates with the hole portion 64. The placing portion 68 is formed in a male and female shape corresponding to the male and female shapes on the side opposite to the tooth profile of the bevel gear to be manufactured, that is, on the bottom side where the tooth profile surface of the bevel gear is not formed.

The forging apparatus 10 has an upper die mounting member 70 which can be freely moved toward and away from the lower die mounting member 12. A hole 72 is defined at the center of the upper die mounting member 70, and an upper punch 74 is inserted into the hole 72. The hole 72 is formed with an inclined portion 76 whose diameter is reduced downward. On the other hand, the upper punch 74 is formed with a tapered portion 78 whose diameter is reduced downward. It is prevented from falling out of the hole 72 while being held by the upper die attaching member 70. At the lower end of the upper punch 74, a convex portion 7 is provided.
9 is formed. An upper die 8 is provided below the upper die mounting member 70.
0 is provided. A step 82 is formed on the outer wall of the upper die 80, and a holding member 84 is engaged with the step 82. The holding member 84 is fixed to the upper die mounting member 70 and the upper die 8
Numeral 0 is positioned and fixed to the upper die mounting member 70 by the flange portion 85 of the holding member 84. A step portion 86 is provided concentrically with the upper die 80 on the lower surface of the outer peripheral edge of the upper die 80, and the step portion 86 has a tapered shape whose diameter is slightly increased downward. A concave portion 88 is defined in the center of the lower surface of the upper die 80, and a male and female tooth profile 90 corresponding to the male and female tooth profile of the bevel gear to be manufactured is formed on the wall constituting the concave portion 88. . A hole 92 communicating with the hole 72 of the upper die mounting member 70 is defined in the concave portion 88 of the upper die 80, and the upper punch 74 is fitted into the hole 92, and the protrusion of the upper punch 74 is formed. The portion 79 protrudes into the recess 88.

As shown in FIG. 2, when the upper die 80 is lowered and the lower die 58 is closed, the mounting portion 68 of the lower die 58, the distal end portion 36 of the lower punch 34, and the upper die 80 Recess 88
A cavity 94 is defined by the projection 79.

The bevel gear forging apparatus 10 according to the present embodiment is basically configured as described above.
Next, the operation will be described below in relation to the forging method according to the present embodiment.

First, a preform 100 is formed by forging a cylindrical work. At this time, the lower part of the preform 100 is formed corresponding to the male and female shapes on the bottom side of the bevel gear to be manufactured without the tooth profile.

After the preparatory steps described above, as shown in FIG.
Placed on At this time, since the placing portion 68 is formed so as to correspond to the shape of the bottom surface side without the tooth profile of the bevel gear to be manufactured, the preform 100 can be easily positioned on the placing portion 68. It is. At this time, the lower surface of the preform 100 is separated from the tip 36 of the lower punch 34 by a predetermined distance.

Next, the upper die 8 is integrated with the upper die mounting member 70.
0 descends, and the step 66 of the lower die 58 and the step 86 of the upper die 80
And the tapered portions of the stepped portion 66 and the stepped portion 86 are engaged with each other, so that the upper die 80 is
8 and the lower mold 58 and the upper mold 80 are closed. At this time, the lower surface of the upper die 80 and the upper surface of the lower die 58 are pressed by the elastic force of the coil springs 40a and 40b. At this time, the projection 79 of the upper punch 74 contacts the upper part of the preform 100 (see FIG. 2). At this time, the tooth form 90 formed on the upper mold 80 is separated from the upper part of the preform 100, and the preform 100 is not forged. That is, a slight gap is defined between the tooth profile 90 and the preform 100, and they are not in contact with each other. Therefore, no force is applied to the tooth profile 90, and the tooth profile 9
There is no concern that 0 will be damaged. Further, the hydraulic unit 14 exhibits a cushion function, absorbs an impact when the lower die 58 and the upper die 80 come into contact with each other, and prevents the lower die 58 and the upper die 80 from being damaged.

Next, as shown in FIG. 3, when the upper die 80 is further lowered, the coil springs 40a and 40b are contracted and the holding plate 42 is lowered, and the lower die 58 and the upper die 80 are preformed in a closed state. It descends with the article 100, and the lower part of the punch holder 48 contacts the upper part of the pressing member 18. Then, a predetermined amount of pressure oil is discharged from the hydraulic unit 14 through a pressure oil supply source (not shown), the pressing member 18 descends inside the chamber 16, and the preform 100 also descends. At this time, since the lower punch 34 does not descend, the lower punch 34 is
As a result, the distal end portion 36 of the lower punch 34 is pressed into the cavity 94. Therefore, the preform 100 is plastically deformed and is set in the respective walls of the mounting portion 68, the concave portion 88, and the convex portion 79. For this reason, a part of the material constituting the preform 100 flows to the tip of the tooth form 90 of the upper mold 80, and molding defects such as underfilling do not occur, and the tooth form 102 corresponding to the tooth form 90 does not occur. Is formed.

At this time, since the upper die 80 and the lower die 58 are kept in pressure contact with the hydraulic unit 14 by the elastic force of the coil springs 40a and 40b, the preformed product 10
Burrs can be prevented from being generated around 0.

As described above, the tooth profile 102 is formed on the preform 100.

Next, the preform 100 is perforated. Drilling device 110 used for this drilling process
Will be described.

The drilling device 110 includes a die holder 112 as shown in FIG. A flange portion 113 is formed at a lower portion of the die holder 112, and the flange portion 1 is formed.
Reference numeral 13 is engaged with and fixed to a pedestal (not shown). A concave portion 114 is defined at an upper portion of the die holder 112, and a bottom portion of the concave portion 114 communicates with the hole 116.
The hole 116 is curved inside the die holder 112,
It is open outside the die holder 112. The recess 1
A punching die 118 is fitted into 14. A step 120 is formed on the outer periphery of the punching die 118.
The pressing member 122 is engaged with the die holder 112, and the pressing member 122 is fixed to the die holder 112. Accordingly, it will be readily appreciated that the punching die 118 is held by the die holder 112. A concave portion 124 is formed at an upper portion of the punching die 118 so as to be engaged with a lower portion of the preform 100, and a hole portion 126 is formed at a central portion of the concave portion 124. It communicates with the hole 116.

The punching device 110 has a pedestal 128 that can be freely moved toward and away from the die holder 112. Holes 130a, 130b are defined in the lower portion of the pedestal 128, and the cylindrical members 132a, 1b are formed in the holes 130a, 130b.
32b extends downward from the base 128 and is fixed. Disc-shaped plate members are fastened to lower ends of the tubular members 132a and 132b by screws 134a and 134b, and flange portions 136a projecting outward from outer walls of the tubular members 132a and 132b by the plate members. 136b
Are formed. Steps 138a, 138b are formed near the ends of the holes 130a, 130b,
The steps 138a and 138b include the cylindrical member 132a,
One ends of coil springs 140a and 140b are seated around 132b.

A mounting member 142 is fixed to the lower portion of the pedestal 128 so as to surround the coil springs 140a and 140b, and a hole 144 is defined in the center of the mounting member 142. The support member 146 is inserted in contact with the base 128. The lower part of the support member 146 is reduced in diameter through a step 150, and the step 150 has the hole 144.
The pressing member 152 fitted into the engagement is engaged. The holding member 152 is formed with a flange 153, and the flange 153 is fixed to the mounting member 142 with a screw 154, so that the support member 146 is prevented from coming off. A punch 155 is fixed to a lower portion of the support member 146, and the punch 155 is attached to the holding member 152.
Is inserted into the hole 156 defined in the above.

Below the mounting member 142, a holding plate 157 is provided.
58a, 158b are defined and the holes 158a, 158
The cylindrical members 132a and 132b are slidably inserted into b. The holes 158a and 158b are formed in the step 160.
a, 160b, and is formed by expanding the diameter.
The flange portions 136a and 136b are engaged with the flanges 136a and 136b, so that the holding plate 157 is prevented from moving downward. On the other hand, the other ends of the coil springs 140a and 140b are in contact with the upper portion of the holding plate 157,
The coil springs 140a and 140b urge the pedestal 128 and the holding plate 157 away from each other.

A hole 162 is defined at the lower center of the holding plate 157, and the hole 162 is formed such that the diameter of the hole 162 is increased through a step 164. A stripper 168 is inserted into the hole 162, and a flange 170 is formed on the outer periphery of the stripper 168. The flange 170 is engaged with the step 164 and fastened with a screw 172, thereby The stripper 168 includes the holding plate 157.
To be fixed. The lower portion of the stripper 168 defines a recess 174 that engages the upper portion of the preform 100.
A hole 176 is defined in the center of the concave portion 174, and the punch 155 is slidably inserted into the hole 176.

The drilling device 110 used in connection with the present embodiment is basically configured as described above. Next, the operation thereof will be described.

The punching die 118 of the punching device 110
The preform 100 in which the tooth profile 102 is formed is placed in the concave portion 124 formed in the above. Pedestal 128 is stripper 1
When lowered integrally with 68, recess 174 of stripper 168 engages the top of preform 100 and preform 100 is positioned relative to stripper 168.
When the pedestal 128 further descends, as shown in FIG. 5, the coil springs 140a and 140b are pressed by the holding plate 157 and the pedestal 128 and contracted, and the punch 155 is pressed by the pedestal 128 and the support member 146 to descend. Then, the hole 178 is defined in the preform 100 by projecting downward from the hole 176 of the stripper 168, entering the upper portion of the preform 100, and punching. At this time, the scrap 180 generated by the definition of the hole 178 is discharged to the outside from the hole 116 through the hole 126 defined in the punching die 118.

The bevel gear is manufactured as described above.

[0038]

According to the method and apparatus for forging a bevel gear according to the present invention, the following effects and advantages can be obtained.

When closing the lower mold and the upper mold, the lower part of the preform is separated from the lower punch, and the upper part of the preform does not contact the tooth form formed on the upper mold. There is no pressing of the product, and the tooth profile of the upper mold is not damaged. Therefore, the durability of the upper mold is improved, and the upper mold can be used for a long time, so that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a bevel gear forging apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a method of using the forging apparatus of FIG. 1, in which an upper mold and a lower mold are closed.

FIG. 3 is a longitudinal sectional view showing a method of using the forging apparatus of FIG. 1 and in a state where a lower punch has entered a cavity.

FIG. 4 is a longitudinal sectional view showing a drilling device used in a method for forging a bevel gear according to an embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a method of using the drilling device of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Forging apparatus 34 ... Lower punch 36 ... Tip part 58 ... Lower die 68 ... Placement part 80 ... Upper die 90 ... Tooth shape 100 ... Preformed product

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-7-80590 (JP, A) JP-A-54-68753 (JP, A) JP-A-62-273539 (JP, A) JP-A-7-80590 236937 (JP, A) JP-A-7-100578 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21J 1/00-13/14 B21K 1/00-27/06

Claims (2)

(57) [Claims] 1. A method for forming a bevel gear by forging, comprising: forming a preformed product having a male and female shape on the bottom side without a toothed surface of the bevel gear to be manufactured, Engaging the lower mold with the corresponding male and female shapes formed therein, positioning the preform in the lower mold in a state of being separated from the lower punch, and contacting the lower mold with the upper mold, The upper punch abuts on the upper part of the preform, and the tooth shape formed on the upper mold and the preform are in non-contact state, and the lower punch and the preform are in non-contact state. Holding the lower die and the upper die closed with each other; and moving the lower die, the upper die, and the upper punch provided on the upper die relative to the lower punch relative to each other. With the lower punch entering the cavity defined between the lower mold and the upper mold Umbrella forging method of the gear, characterized in that it comprises a step of forming swaging presses the serial preform, the. 2. An apparatus for forming a bevel gear by forging, comprising: a lower mold having a male and female shape corresponding to a male and female shape on the bottom side of the manufactured bevel gear having no toothed surface; An upper die having male and female teeth corresponding to the male and female teeth of the bevel gear to be manufactured, and an upper die provided in a hole defined in the lower die. A lower punch relatively displaceable with respect to the upper die, and an upper punch provided in a hole defined in the upper die, wherein the preform is formed when the preform is placed on the lower die. The male and female shapes on the bottom side without the tooth profile of the product are positioned by engaging with the male and female shapes of the lower die, and when the lower die and the upper die are closed, the upper punch is Abut on the upper part, the tooth shape formed on the upper mold and the preform are in a non-contact state, and A bevel gear forging, wherein the punch and the preform are held in a non-contact state, and the preform is pressed and swaged by the lower die, the lower punch, the upper die, and the upper punch. Molding equipment.