JP2001225139A - Method and apparatus for forging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the technical problem that a method to have a product shape by overall cutting from a metal bar stock in a conventional way requires a long working time and is not suitable for mass production, further, a material is not effectively used due to generation of a cutting chip. SOLUTION: A manufacturing method of a stepped/tapered off hollow member, which is provided with a large end part and a small end part to both ends of a stepped barrel part, a hole part (for power transmission) to the end face of the large end part and a hexagon part (polygonal part) (for power transmission) to the outer periphery of the small end part, has a first step to prepare a metal stock, a second step to form by inserting a first punch into the stock and a third step to remove an excess metal located to a first punch tip side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a forging method and apparatus.

[0002]

2. Description of the Related Art Heretofore, as a method of manufacturing a stepped tapered hollow member, for example, it has been general to perform a full cutting from a round bar metal material to obtain a product shape.

FIG. 1 shows a completed tapered hollow member with a step.
Conventionally, this stepped tapered hollow member is made of a hexagonal portion 101, a first outer periphery 102, a second outer periphery 103,
Third outer periphery 104, fourth outer periphery 105, hole 106, bottom 1
All of 07 were processed by cutting.

The hole 1 of this stepped tapered hollow member
06 and the hexagonal portion 101 are fitted with different members, and power is transmitted through a stepped tapered hollow member.

[0005]

The conventional method of performing a full cutting from a round bar metal material into a product shape has a very low productivity, and in particular, a long machining time is required for cutting hexagonal portions and holes. It took a long time, was not suitable for mass production, and had a technical problem that the material was not efficiently used due to generation of cutting chips.

Means for solving the above technical problems include:
Although it is conceivable to use casting, it is not possible to perform complicated and high-precision molding such as a hole portion and a hexagonal portion (polygonal portion) (in addition, pinholes, Defects such as sinks tend to occur, resulting in poor product yields and direct rates.)

Accordingly, an object of the present invention is to provide a forging method and apparatus capable of forming the above-mentioned shape using forging.

[0008]

According to the present invention, a lower die having a first hollow portion and a second die having a first hollow portion are provided.
Butting the upper die having the hollow portion of
In a forging method of forming a closed space consisting of a hollow portion of a fork and forming a forged product by forging a material arranged in the closed space using a punch provided in the lower die, the lower die is , Is divided into an inner die including the inner periphery of the hollow portion and an outer die surrounding the inner die, and upon completion of forging, forging is performed in a gap between the inner periphery of the hollow portion of the inner die and the outer periphery of the punch. The end of the product is present, the inner die, when opening the lower and upper dies, compared to when closing the mold,
The distance between opposing inner walls is configured to be large.

Preferably, the inner die has at least two or more dividing lines from the upper end to the lower end thereof,
It can be divided into at least two or more members, and when the lower and upper dies are clamped, each member is configured to abut along a division line.

That is, when the inner die and the outer die are not divided and the distance between the inner walls facing the inner die is constant, if the frictional force and adhesion between the end of the forged product and the inner periphery of the hollow portion are strong, the die There is a possibility that the forged product is deformed at the time of opening. In particular, when the end of the forged product is thin like a burr, the end of the forged product may be torn when the mold is opened.

On the other hand, according to the present invention, when the above-mentioned frictional force and adhesion force are strong when the mold is opened, the inner die and the outer die are divided, and the inner die tends to follow the forged product and lift.

When the inner die is lifted, the above-mentioned frictional force is lost at that moment, and only the adhesion works between the end of the forged product and the inner periphery of the hollow portion of the inner die. Peels off from the end of Depending on the strength of the adhesion, the inner die may peel off immediately upon lifting.

In a preferred embodiment of the present invention, by forming the outer periphery of the inner die into a tapered shape, the inner die is easily separated from the outer die when the mold is opened, and the inner die easily follows the forged product.

Further, by retracting the punch before opening the lower and upper dies, no frictional force acts between the end of the forged product and the punch when the mold is opened.

The end of the forged product may be a burr that is removed in a process after forging.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a completed product of a stepped tapered hollow member formed by forging, which can be formed in a single forging operation from the rod-shaped material shown in FIG. 4. Only the excess thickness 108 (burr 109) is removed by cutting. It can be finished into one stepped tapered hollow member finished product. Hex portion 101, first outer periphery 102, second outer periphery 103, third outer periphery 104, fourth outer periphery 105, hole 10
No. 6 is made by forging, and no post-processing is performed.

According to this forging method, the productivity can be greatly improved and the material yield can be improved as compared with the conventional whole-cut products (the hexagonal portion 101 and the first outer periphery, which are easily worn or broken by the forging effect). The material strength of No. 102 is also improved.)

Next, the structure of a forging die of a stepped tapered hollow member will be described with reference to FIG.

This stepped tapered hollow member forging die has a fixed main body frame 11, a lower die holder 10 provided in the main body frame, a lower die 9 provided in the lower die holder,
Lower die piece 8, Lower punch 12 that can be raised and lowered by a hydraulic cylinder A (not shown), Upper slider facing the lower die
4, upper die holder 3 provided on this upper slider, upper die 2, upper die piece 1, upper punch provided on this upper die holder
5, has a piece guide 6, and a spring 7. The upper slider is connected to a hydraulic cylinder B (not shown) and is movable up and down.

The upper die piece is used to release the product (to two)
The upper punch is restrained in the vertical direction by the piece guide, and is movable in the horizontal direction. The initial punch is fixed to the upper die by the force of a spring.
At the time of product release, the upper punch is pushed downward by a hydraulic cylinder C (not shown), and the upper die piece is extruded from the upper die along a guide part (not shown) provided at a tapered portion between the upper die and the upper die piece. And open right and left.

The lower die piece is divided into two parts (no guide part is provided), and is restrained by a tapered part of the lower die in a clamped state. When the mold is open, it is free in the upward direction, and if it floats slightly from the lower die, it is free in the left-right direction. Therefore, if a burr occurs between the lower die piece and the lower punch during molding, the lower die piece is pulled by the burr and lifts upward due to the frictional force and adhesion between the burr and the lower die piece when the mold is opened. .

At that moment, the lower die piece becomes free in the left-right direction, and the frictional force between the burr and the lower die piece disappears. At this time, by making the weight of the lower die piece larger than the adhesion between the burr and the lower die piece, only the lower die piece returns to its original position (in the lower die) by its own weight, and no burr remains in the lower die piece. It has a structure. Even if burrs remain, the lower die piece is split and not fixed to the lower die,
Deburring maintenance is easy.

The heating of the mold is performed by strip heaters 13 attached to the outer periphery of the lower die holder and the upper die holder, respectively, and the temperature is controlled by a thermocouple 14 and a temperature controller (not shown), respectively. The outer periphery of the belt-shaped heater is covered with a heat insulating material 15, and a heat insulating plate 16 is interposed between the main body frame and the lower die holder, and between the upper slider and the upper die holder, respectively, so as to be insulated and kept warm.

Next, a method of forging a stepped tapered hollow member will be described with reference to FIGS.

First, the upper and lower dies and the respective punches are heated to appropriate temperatures, the respective punches are retracted as shown in the figure with the mold opened, and the material D heated to an appropriate temperature is placed in the lower die piece 8. Then, as shown in FIG. 7, the upper die 2 is lowered and the mold is clamped. Next, as shown in FIG. 8, the lower punch 12 is inserted and molding is performed. At this time, since the completed product of FIG. 3 is performed from the material D by one forging, the deformation resistance required for the forging becomes large,
A burr 109 is generated between the lower die piece 8 and the lower punch 12.
When the molding is completed, the lower punch is retracted to the original position as shown in FIG.

Subsequently, as shown in FIG. 10, the upper die 2 is raised. At this time, the lower die piece is pulled by the burrs and lifted upward due to the frictional force and adhesion of the burrs generated during molding. At that moment, the lower die piece becomes free in the left-right direction, and the frictional force between the burr and the lower die piece disappears. At this time, since the weight of the lower die piece is larger than the adhesion between the burr and the lower die piece, only the lower die piece returns to its original position (in the lower die) by its own weight as shown in FIG. Does not remain.
Subsequently, as shown in FIG. 12, the upper punch 5 is lowered in the mold open state to open the upper die piece 1 to the left and right, and the molded product C is taken out from the mold.

[Brief description of the drawings]

[Fig. 1] Cut tapered hollow member with step

[Figure 2] Material for cutting a stepped tapered hollow member

Fig. 3 Forged product with a stepped tapered hollow member (completed molding)

FIG. 4 Material for forging hollow member with step taper

FIG. 5 is an assembly drawing of a stepped tapered hollow member forging die.

FIG. 6 is a forging process diagram of a stepped tapered hollow member (standby state).

FIG. 7 is a forging process diagram of a stepped tapered hollow member (in a mold-clamped state).

FIG. 8 is a forging process diagram of a stepped tapered hollow member (with a punch inserted).

FIG. 9 is a forging step diagram of a stepped tapered hollow member (in a state where a punch is pulled out).

FIG. 10 is a forging step diagram of a stepped tapered hollow member (in a mold opening start state).

FIG. 11 is a forging process diagram of a stepped tapered hollow member (in a state where the mold opening is completed)

FIG. 12 is a forging step diagram of a stepped tapered hollow member (forged product removal)

[Explanation of symbols]

101: hexagonal part, 102: first outer circumference, 103: second outer circumference, 104: third outer circumference, 105: fourth outer circumference, 106: hole, 107: bottom, 108: excess, 109: burr, D:
Material, C: Molded product, 1: Upper die piece, 2: Upper die, 3: Upper die holder, 4: Upper slider, 5: Upper punch, 6: Piece guide, 7: Spring, 8: Lower die piece, 9: Lower die, 10:
Lower die holder, 12: Lower punch, 13: Strip heater, 1
4: Thermocouple, 15: Insulation material, 16: Insulation plate

Claims (7)

[Claims] A first die having a first hollow portion and a second die having a second hollow portion are joined to form a closed space including the first and second hollow portions; Using a punch provided in the lower die, in a forging method of forging a material disposed in the closed space to form a forged product, wherein the lower die includes an inner periphery of the hollow portion. The inner die is divided into an outer die surrounding the inner die. When forging is completed, the end of the forged product is inserted into a gap between the inner periphery of the hollow portion of the inner die and the outer periphery of the punch. Wherein the inner die is configured to have a larger distance between opposing inner walls when the lower and upper dies are opened than in clamping. 2. The inner die has at least two or more division lines extending from an upper end side to a lower end side, and can be divided into at least two or more members. When the lower and upper dies are clamped, The forging method according to claim 1, wherein each member is configured to abut along the division line. 3. The forging method according to claim 1, wherein the outer periphery of the inner die has a tapered shape. 4. The punch is retracted before the lower and upper dies are opened.
4. The forging method according to any one of the above items 3. 5. The forging method according to claim 1, wherein the end of the forged product is a burr that is removed in a step after forging. 6. A closed die including a lower die having a first hollow portion and an upper die having a second hollow portion. The lower die is provided with a punch that can advance into the closed space, and the punch is used to forge a material disposed in the closed space to form a forged product. In the forging apparatus, the lower die is divided into an inner die including an inner periphery of the hollow portion, and an outer die surrounding the inner die, and the lower die is formed inside the hollow portion of the inner die. The gap between the circumference and the outer periphery of the punch is configured such that the end of the forged product is present when the forging is completed when the punch has advanced, and the inner die is a die for the lower and upper dies. When open, between the opposing inner walls compared to when clamping Forged apparatus characterized by being configured to release increases. 7. The inner die has at least two or more division lines extending from an upper end side to a lower end side thereof, and can be divided into at least two or more members. 2. The forging apparatus according to claim 1, wherein each member is configured to abut along said division line.