JP2002018548A - Forging method and forging device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To form a spline on the outer peripheral surface of a material having an enlarged head at the top end of a hollow cylindrical portion having a small hole, and simultaneously form the enlarged head into a gear. Provided is a forging method and a forging device capable of avoiding deformation of a small hole. A die (1) and a hollow cylindrical part (22) for forming an outer peripheral surface of a hollow cylindrical part (22) are formed from a material (20) having a bulging part (23) formed on the top end of a hollow cylindrical part (22) having a narrow hole (21) formed in the axial direction. Is set in the lower die 3 having the mandrel 7 inserted into the small hole 21 of
The material 20 is compressed by combining the upper mold 5 for forming
At the same time as forming the spline on the outer peripheral surface of the hollow cylindrical portion 22 and forming the bulging portion 23 into a bevel gear, the mandrel 7 is inserted up to the bottom 21 a of the small hole 21 of the hollow cylindrical portion 22, and is being formed. The mandrel 7 follows the movement of the small hole bottom 21a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hollow cylindrical part having a small hole with a bottom and a protruding part formed at the top end of a hollow cylindrical part. TECHNICAL FIELD The present invention relates to a forging method and a forging apparatus for forming a gear into a gear.

[0002]

2. Description of the Related Art For example, as shown in FIG. 5, a raw material 20 having a bulging portion 23 formed at a top end of a hollow cylindrical portion 22 having a bottomed narrow hole 21 formed in the axial direction from a base end. As shown in FIG. 6, in order to manufacture the product 30 having the spline 31 on the outer peripheral surface of the hollow cylindrical portion and the bevel gear 32 on the head, since the material 20 and the product 30 are hollow, It is necessary to go through multi-step processing steps such as processing and double-acting press, and the production efficiency is extremely low.

[0003] Regarding the processing of a pipe-shaped product, Japanese Unexamined Patent Publication No. Hei 5-7922 discloses that a mandrel for forming the inner peripheral surface of a hollow material is pressed and forged while being fixed to a bolster to thereby break the mandrel. It is disclosed that a pipe-shaped product is extruded by reducing the inner diameter and outer shape of a raw material while preventing insertion defects.

This technique is an extrusion process of a pipe-shaped product, and a spline 31 is formed on the outer peripheral surface of the hollow cylindrical portion.
In the case of manufacturing a product 30 having a bevel gear 32 at the head and having a bevel gear 32, it is necessary to perform molding to regulate the overall length and outer shape. Therefore, at present, when a product whose overall length and outer shape are regulated is formed, it is manufactured by one-step press forging using, for example, a single-acting press-type forging device shown in FIG.

More specifically, the forging device shown in FIG. 7 is a die 1 and a die 1 for forming the outer peripheral surface of a hollow cylindrical portion 22 having a bottomed narrow hole 21 formed from the base end along the axial direction shown in FIG. A lower die 3 having a counter punch 2 for regulating the base end of the raw material 20 and for extruding the molded product 30 from the die 1.
And an upper die 5 having a punch 4 for pressing the bulge 23 of the material 20 into the bevel gear 32 and pressing the die into the die 1.

The upper die 5 is moved up and down by a single-acting cylinder (not shown), and when descending, the lower die 3 and the upper die 5 are concentrically joined together, and the raw material 20 is compressed and forged into a product 30. .

On the other hand, below the die 1 of the lower die 3, a counter punch 2 is movably inserted in the axial direction of the die 1, and a spline 31 is formed on the outer peripheral surface of the raw material 20 by the die 1 of the lower die 3. At the same time, molding is performed between the punch 4 of the upper die 5 and the counter punch 2 of the lower die 3 to reduce the entire length of the raw material 20 to a specified length.

The counter punch 2 comprises a sliding portion 2a that moves in the die 1 in the axial direction and a base 2b having a larger diameter than the sliding portion 2a.
The lower end surface of b contacts the plate 6a fixed to the lower mold 3, and receives the load from the punch 4 of the upper mold 5.

The axial center of the counter punch 2 is hollow.
The lower end of the mandrel 7 is inserted through the hole in the center of the plate 6a into the center of the plate 6b disposed at the lower stage of the plate 6a. It is fixed in contact.

The plates 6a and 6b also support a plurality of knockout pins 8 that push up the lower end surface of the counter punch 2, and the plates 6a and 6b have
A hole for inserting the knockout pin 8 is provided. An ejector 9 driven by a driving mechanism (not shown) is provided below the knockout pin 8.

That is, the head of the knockout pin 8 is inserted into the plate 6a which comes into contact with the lower end surface of the counter punch 2, and the knockout pin 8 is prevented from coming off by the plate 6b. When the upper die 5 rises after the molding by the lowering of the upper die 5, the ejector 9 moves up together with the upper die 5, and then the counter punch 2 is pushed up through the knockout pin 8, so that the product 30 is pushed out of the die 1. It is.

[0012] The forging apparatus of this configuration uses the lower die 3
The punch 4 of the upper die 5 is lowered to press the material 20 in the die 1 of the lower die 3, and the entire length is regulated by the punch 4 and the counter punch 2 to form the spline 31 and the bevel gear 32. The steps can be performed in one step.
At this time, the mandrel 7 is inserted into the small hole 21 of the raw material 20 to prevent the deformation of the small hole 21 of the raw material 20 and a change in the inner diameter thereof.

[0013]

However, when the mandrel 7 of this forging apparatus is compression-molded with the upper die 5 and the lower die 3, the raw material 20 is pressed into the die 1 and descends. It is necessary to provide a space S between the bottom 21a of the small hole 21 of the material 20 and the tip of the mandrel 7, and the mandrel 7
And is fixed at a predetermined position via the.

However, when this space S is present, when the forging is performed with the lower die 3 and the upper die 5 together, the surrounding material enters the space S, and the vicinity of the bottom 21 a of the small hole 21 is deformed. It is feared that a product having a desired spline shape and a fine hole cannot be obtained.

Accordingly, an object of the present invention, which has been made in view of the above points, is to provide a hollow cylindrical portion having a narrow hole formed in the axial direction, a material having a bulging portion formed at the top end, and an outer peripheral surface of the hollow cylindrical portion. It is an object of the present invention to provide a forging method and a forging device capable of avoiding deformation of splines and small holes formed in a hollow cylindrical portion when performing a forging process of forming a spline and a gear into a gear at the same time as forming a spline. is there.

[0016]

According to a first aspect of the present invention, there is provided a forging method, wherein a forging method is provided at a top end of a hollow cylindrical portion having a narrow hole with a bottom along an axial direction from a base end. The material having the portion formed thereon is set on a lower die having a die for molding the outer peripheral surface of the hollow cylindrical portion and a mandrel inserted into the small hole of the hollow cylindrical portion, and forming a bulging portion of the material. The forging method of forming the spline on the outer peripheral surface of the hollow cylindrical portion of the material by simultaneously compressing the material according to the lower die and forming the spline on the gear was formed on the hollow cylindrical portion. The mandrel is inserted to the bottom of the small hole, and the mandrel is made to follow the movement of the bottom of the small hole during molding.

According to the first aspect of the present invention, the mandrel inserted to the bottom of the small hole of the material follows the movement of the bottom of the small hole accompanying the lowering of the material at the time of forging. The state in which the inside of the hole is always filled with the mandrel is maintained, and no gap is formed in the small hole during molding, in which the surrounding material enters.
The process press forging results in the desired product shaping.

According to a second aspect of the present invention, there is provided a forging apparatus comprising: a hollow cylindrical portion having a narrow hole with a bottom formed in an axial direction from a base end; In a forging device for forming a spline on the outer peripheral surface of the portion and simultaneously forming the bulging portion into a gear, a die for forming a spline on the outer peripheral surface of the hollow cylindrical portion of the material is inserted into the small hole. A lower mold having a mandrel, and an upper mold having a punch for forming a bulge of the material, wherein the mandrel is movable along the moving direction of the upper mold, and is biased toward the upper mold. It is characterized by being.

According to the second aspect of the present invention, the mandrel inserted to the bottom of the fine hole of the material can follow the movement of the bottom of the fine hole accompanying the lowering of the material at the time of forging. The material can be formed by one-step press forging while preventing the formation.

According to a third aspect of the present invention, in the forging device of the second aspect, the mandrel is urged toward the upper die via a spring. According to the invention of claim 3, it is possible to easily apply an appropriate biasing force toward the upper mold to the mandrel by the spring.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a forging method and a forging apparatus according to the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic diagram showing a configuration of a forging device according to the present embodiment. In FIG. 1, parts corresponding to those in FIG. 7 are denoted by the same reference numerals, and detailed description of the parts will be omitted. Different parts will mainly be described.

The forging device shown in FIG. 1 controls the die 1 for forming the outer peripheral surface of the material 20 shown in FIG. 5 and the base end of the material 20 and a counter for pushing out the formed product 30 from the die 1. A lower mold 3 having a punch 2 and an upper mold 5 having a punch 4 for pressing the material 20 into the die 1 while forming the bulging portion 23 of the material 20 into a bevel gear 32 are provided. By moving the upper mold 5 up and down by a cylinder (not shown), the lower mold 3 and the upper mold 5 are concentrically aligned at the time of lowering, and the material 20 is compressed to produce a product 30.
Forging.

Here, the mandrel 7 to be inserted into the small hole 21 of the raw material 20 is installed movably along the axial direction, that is, the moving direction of the upper die 5, in the hollow formed at the center of the axis of the counter punch 2. However, in the forging apparatus shown in FIG. 7, the lower end of the mandrel 7 is fixed by contacting with the center of the plate 6b disposed below the plate 6a through the hole at the center of the plate 6a. Was.

On the other hand, the forging device of the present embodiment shown in FIG. 1 has a lower end of a mandrel 7 and an upper end of an ejector 9 which pushes up a lower end surface of the counter punch 2 through a plurality of knockout pins 8 after molding. It is characterized in that a spring 10 is disposed as a biasing means between the first and second parts.

That is, the lower end of the mandrel 7 is urged toward the upper mold 5 through the spring 10 so that the tip of the mandrel 7 is pushed up to such a degree that it protrudes slightly from the lower mold 3. The material 20 is set in the lower mold 3 by fitting the small holes 21 formed in the material 20 into the mandrel 7 slightly projecting from the lower mold 3. As shown in FIG. 1, the bottom 2 of the small hole 21 of the material 20 is set by this set of the material 20.
1a, the tip of the mandrel 7 is inserted and the mandrel 7
Is kept in the small hole 21 without any gap.

Next, the upper die 5 is lowered to apply a compressive force to the raw material 20 to the lower die 3 on which the raw material 20 is set.
The lowering of the upper die 5 forces the raw material 20 to lower, so that the base end is pressed against the die 1 of the lower die 3, and the punch 4 of the upper die 5 is pressed against the swollen portion 23. When this material 20 descends into the die 1,
The mandrel 7 that is accommodated in the lower hole follows the material 20 against the urging force of the spring 10 and descends.
Forging is continued in a state where the mandrel 7 is contained in the small hole 1 without a gap, and the spline 31 is deformed in a state where the small hole 21 is prevented from being deformed by the mandrel 7 filled in the small hole 21 as shown in FIG. Is formed, and at the same time, the bevel gear 32 is formed on the expansion head 23.

Therefore, since the spline 31 is formed in a state where the deformation of the small hole 21 of the material 20 and the change of the inner diameter are prevented by the mandrel 7, an optimum desired spline shape without droop can be secured.

After the above forging is completed, the upper die 5 is raised as shown in FIG. 3, and then the ejector 9 is raised as shown in FIG. And the product 30 is extruded from the die 1 and carried out.

It should be noted that the fine hole 2 of the finally formed product 30
In the case of further finishing machining of No. 1 with a drill or the like, the fine hole 21 serving as a pilot hole is formed with high precision, so that the drill does not escape in the so-called finishing process of exposing the hole diameter, and more precise machining is performed. There is also an advantage that finishing accuracy can be improved and finishing accuracy can be improved.

Therefore, according to the present embodiment, the material 20
The mandrel 7 inserted to the bottom 21a of the small hole 21 of
Since the bottom 21a of the fine hole 21 follows the downward movement of the material 20 during forging, the state in which the inside of the fine hole 21 is always filled with the mandrel 7 is maintained during the forming of the material 20,
There is no gap in which the surrounding material enters into the small hole 21 during molding, and the spline 31 and the bevel gear 32 are formed by one-step press forging while preventing deformation of the small hole 21. A product 30 is obtained. As a result, production efficiency is improved and product costs can be reduced.
Since it has a simple structure in which the mandrel 7 is urged upward by the spring 10 with an appropriate urging force, it can be obtained at a low cost by slightly changing the structure of the conventional forging device, and is extremely advantageous in reducing the manufacturing cost. .

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the spirit of the invention. For example, in the above-described embodiment, the spring 10 is used as the urging means of the mandrel 7, but other elastic members such as cushion rubber may be used, and other types of gears may be formed instead of bevel gears. It is also possible.

[0033]

According to the forging method of the present invention described above, the mandrel inserted to the bottom of the fine hole of the material follows the movement of the bottom of the fine hole accompanying the lowering of the material at the time of forging pressure. The inside of the small hole is always kept filled with the mandrel, and no gap is formed in the small hole during molding to allow the surrounding material to enter. This results in the formation of a product with the desired splines and gears.

Further, according to the forging apparatus of the present invention, the mandrel inserted to the bottom of the fine hole of the material can follow the movement of the bottom of the fine hole accompanying the lowering of the material at the time of forging, and the fine hole can be formed. Because the material can be formed by one-step press forging while preventing deformation, production efficiency can be improved and product cost can be reduced, and it can be obtained at low cost by slightly changing the structure of the conventional forging device. This is extremely advantageous for reducing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a forging apparatus for explaining an embodiment of a forging method and a forging apparatus of the present invention.

FIG. 2 is a schematic view showing the operation of the forging device.

FIG. 3 is a schematic view showing the operation of the forging device.

FIG. 4 is a schematic view showing the operation of the forging device.

FIG. 5 is a diagram showing a shape of a material.

FIG. 6 is a view showing the shape of a product.

FIG. 7 is a schematic view showing a configuration of a conventional forging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 2 Counter punch 2a Sliding part 2b Base 3 Lower die 4 Punch 5 Upper die 6a, 6b Plate 7 Mandrel 8 Knockout pin 9 Ejector 10 Spring 20 Material 21 Fine hole 22 Hollow cylindrical part 23 Bulb 30 Product 31 Spline 32 Bevel gear (gear)

Claims (3)

[Claims] 1. A material in which a bulging portion is formed at a top end of a hollow cylindrical portion having a bottomed narrow hole along an axial direction from a base end,
A die for forming the outer peripheral surface of the hollow cylindrical portion and a lower die having a mandrel inserted into the small hole of the hollow cylindrical portion are set on the lower die, and the upper die for forming the bulging portion of the material is aligned with the lower die. In the forging method of compressing the material and forming a spline on the outer peripheral surface of the hollow cylindrical portion of the material and forming the bulge into a gear, the mandrel is inserted up to the bottom of the small hole formed in the hollow cylindrical portion. And forcing the mandrel to follow the movement of the bottom of the small hole during molding. 2. A material in which a bulging portion is formed at a top end of a hollow cylindrical portion having a bottomed narrow hole formed along an axial direction from a base end,
In a forging device for forming a spline on the outer peripheral surface of the hollow cylindrical portion and simultaneously forming the bulging portion into a gear, a die for forming a spline on the outer peripheral surface of the hollow cylindrical portion of the material and the fine hole are formed. A lower mold having a mandrel to be inserted; and an upper mold having a punch for molding a bulging portion of the material, wherein the mandrel is movable along a moving direction of the upper mold, and is attached to the upper mold. A forging device characterized by being energized. 3. The forging apparatus according to claim 2, wherein the mandrel is urged toward an upper die by a spring.