JPH08243676A - Forging apparatus - Google Patents

Abstract

PURPOSE: To prevent excess load from exerting on a die even if a work having larger than a prescribed vol. sets, by constituting a punch with a main punch and a fixed pressure punch and enabling the setting of the load of the fixed pressure punch at lower than the load of the main punch. CONSTITUTION: A ringed work W is set into a cavity 3 and a punch 6 is descended. A mandrel 7 penetrates the hole in the work W to form the inner diameter of a product. An outer punch 9 as the fixed pressure punch pushes the work W into the cavity 3 to close a tooth die 4. An inner punch 8 as the main punch squeezes the work W. The thickness of the work W escapes into a through-hole 2a along the mandrel 7 by two steps of the pressurizing movement and also, bulges into the tooth die 4. In the case of being much vol. of the work W, the outer punch 9 is retreated upward by the pressure in the tooth die 4, and the excess thickness is flowed into a recessed part 13. Therefore, the pressure in the cavity 3 is not made to be excess.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging device, particularly a cold forging device.

[0002]

2. Description of the Related Art In a forging machine, a work matched to the volume of a molded product is put in a cavity and pressed by a punch to deform the work into a cavity shape in a closed or open cavity. Then, a product having a desired shape is molded. In recent years, it has become possible to form a gear from a ring-shaped work in one step by cold forging.

[0003]

In order to improve the accuracy of the product shape, it is desirable to increase the pressing load, but in cold forging, the pressing load is extremely high, and therefore the die design is difficult. When the press load is reduced, a wall thickness is generated. Conversely, if the press load is increased or the volume of the work is large, the load on the die increases accordingly. Therefore, the press load must be balanced with the pressure resistance of the die, and even if the press load is appropriate, unless the work is thoroughly managed, the yield will be poor or the device will be destroyed. In particular, in the gear molding having a chamfer in the tooth profile, as shown in FIG.
When the work W is pressed by closing the punch 6 with the punch 6, the stress concentrates on the tip of the chamfer. Therefore, when the volume of the work W is large, the concentrated stress acts on the portion P corresponding to the chamfer of the die 1. A crack occurs. Also, b in FIG.
As described above, when pressure is released by the punch 6 that matches the diameter of the root pitch circle and the pressure is released to the periphery of the punch 6, the excess thickness 15 causes excessive burrs and the accuracy of the tooth diameter portion deteriorates.

[0004]

SUMMARY OF THE INVENTION The present invention is a forging device capable of forming a highly accurate product and preventing the device from being damaged even when the load is high and the work is uneven. The punch is composed of a main punch and a constant pressure punch, and the load of the constant pressure punch can be set lower than the load of the main punch. Further, the main punch and the constant pressure punch can be made to have a relationship between the inner punch and the outer punch, or the constant pressure punch can be provided with a close contact surface with the side surface in the radial direction of the die. Further, for a die having a gear-shaped cavity, the diameter of the main punch is set to the root circle diameter, and the constant pressure punch having the inner diameter equal to the diameter of the main punch and the outer circumference including the diameter of the cutting edge circle is used as the main punch. It can be arranged concentrically around the punch.

[0005]

[Function] If the press load of the constant pressure punch is set within the pressure resistance load of the die, even if the press load of the main punch is too high or the volume of the work is too large, the constant pressure punch absorbs the excess stress, The die is not overloaded. Further, if the main punch and the constant pressure punch are made to have a relationship between the inner punch and the outer punch, the meat flows in the radial direction from the center to improve the accuracy of the outer peripheral shape, and the constant pressure punch has a side surface with respect to the radial direction of the die. If the close-contact locking surface is provided, the die is restrained from the surroundings, so that the die is reinforced. Further, in the gear forming, since the tooth profile is closed by the constant pressure punch, the concentrated stress applied to the chamfer part is controlled by the press load of the constant pressure punch to prevent the die from breaking and improve the tooth profile accuracy. Also connect.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the forging device according to the present invention is applied to gear forming will be described with reference to the drawings. Reference numeral 1 denotes a die, which has a through hole 2a provided with an ejector 2 in the center, and a cavity 3 is formed at an upper end portion of the through hole 2a. A tooth profile forming tooth mold 4 having a chamfer is recessed on the inner peripheral surface of the cavity 3, and a locking step 5 is formed on the upper peripheral edge.
Is provided.

Reference numeral 6 denotes a punch. As shown in FIG. 1A, the punch 6 has a mandrel 7 which is concentric with the through hole 2a and smaller in diameter than the through hole 2a, just above the through hole 2a.
On the outer circumference of the mandrel 7, an inner punch 8 as a main punch and an outer punch 9 as a constant pressure punch are arranged concentrically with the mandrel 7, respectively. The mandrel 7, the inner punch 8 and the outer punch 9 are integrally moved up and down by a pressing mechanism 10, and a constant pressure load applying means 11 for applying a press load lower than the press load of the punch 6 to the outer punch 9.
Is provided. The constant pressure load applying means 11 has a structure in which a constant load is maintained by, for example, elasticity of an elastic body or hydraulic pressure, and when a stress equal to or higher than the constant load is applied, the constant pressure load applying means 11 is retracted in the anti-press direction (upward) and absorbs the stress. There is.

The outer diameter of the inner punch 8 is equal to the root diameter of the gear corresponding to the shape of the cavity 3, and the outer shape of the outer punch 9 is larger than the tip diameter of the gear corresponding to the shape of the cavity 3. On the lower surface, the die 1
A locking step portion 12 having a close locking surface that can be locked is formed on the outer surface of the locking step portion 5 formed in. On the outer side of the surface of the outer punch 9 which closes the tooth profile forming tooth mold 4, a relief recess 13 for burr formation is provided.

In such a forging device, when the ring-shaped work W is set in the cavity 3 (a in FIG. 2) and the punch 6 is lowered, first, the mandrel 7 penetrates the hole of the work W, and then, The outer punch 9 pushes the work W into the cavity to close the tooth profile forming tooth mold 4 (see FIG. 2).
B), and finally the inner punch 8 crushes the work W (b in FIG. 1). By the two-step pressing operation, the meat of the work W escapes into the through hole 2a along the mandrel 7 and is projected into the tooth profile forming tooth mold 4 to form the tooth profile 14.

When the volume of the work is large, a part of the work can be released into the through hole 2a.
When the meat protruding inwardly fills the tooth profile forming tooth mold 4 and exceeds the amount required for forming a predetermined tooth profile accuracy, the pressure inside the tooth profile forming tooth mold 4 causes the outer punch 9 to retreat upward. Then, the load corresponding to the excess is absorbed, excess meat is allowed to flow into the recess 13 to form the burr 15, and the pressure in the tooth profile forming tooth mold 4 is kept constant.
The load on the die is controlled within the pressure resistant load (Fig. 3).

Further, in the forging apparatus of the embodiment, as the punch is lowered, the outer punch 9 is attached to the step portion 5 of the die 1 as shown in FIG.
Since the locking stepped portion 12 of the die is locked and restrains the periphery of the die, the force F acting in the radial direction of the die is reinforced by the reinforcement.
It is possible to increase the pressure resistance load of the die. The mandrel can be provided not only on the punch side but also on the die side in a movable or fixed state.

The forging device of the present invention is applied to other than gear forming, and in addition to the main punch, a constant pressure punch is provided so that the pressure load can be adjusted, and if the constant pressure punch absorbs excessive stress, the constant pressure punch can be used. The punch does not have to be provided as a concentric circle around the main punch, but may be provided at the center of the main punch, and the shapes of both punches are appropriately changed according to the product shape.

[0013]

According to the present invention, even if a work larger than a predetermined volume is set due to the variation of the work, an excessive load does not act on the die. Therefore, a punch having a high press load is used to improve the accuracy of the product. The die life can be extended.

[Brief description of drawings]

FIG. 1 is an explanatory view of a forging device according to the present invention.

FIG. 2 is an explanatory diagram showing a flow of meat of a work in a forming process.

FIG. 3 is an explanatory diagram of a locking step portion.

FIG. 4 is an explanatory diagram of a conventional example.

[Explanation of symbols]

1 ... die, 2 ejector, 2a ... through hole, 3 ...
・ Cavity, 4 ・ ・ Tooth profile forming tooth mold, 5 ・ ・ Locking step, 6 ・ ・ Punch, 7 ・ ・ Mandrel, 8 ・ ・ Inner punch, 9 ・ ・ Outer punch, 10 ・ ・ Pressure mechanism, 1
1 ... Constant pressure load applying means, 12 ... Locking step portion, 13 ...
Escape recess, 14 ・ ・ Tooth profile, 15 ・ ・ Excessive thickness, P ・ ・ Chamfer corresponding part, W ・ ・ Work, F ・ ・ Force acting in radial direction of die.

[Procedure amendment]

[Submission date] June 29, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is an explanatory view of a forging device according to the present invention.

FIG. 2 is an explanatory diagram of a molding process.

FIG. 3 is an explanatory diagram showing a flow of meat of a work in a forming process.

FIG. 4 is an explanatory diagram of a locking step portion.

FIG. 5 is an explanatory diagram of a conventional example.

[Explanation of symbols] 1 ... Die, 2 ... Ejector, 2a ... Through hole, 3 ...
・ Cavity, 4 ・ ・ Tooth profile forming tooth mold, 5 ・ ・ Lock step, 6 ・ ・ Punch, 7 ・ ・ Mandrel, 8 ・ ・ Inner punch, 9 ・ ・ Outer punch, 10 ・ ・ Pressure mechanism, 1
1 ... Constant pressure load applying means, 12 ... Locking step portion, 13 ...
Escape recess, 14 ・ ・ Tooth profile, 15 ・ ・ Excessive thickness, P ・ ・ Chamfer corresponding part, W ・ ・ Work, F ・ ・ Force acting in radial direction of die.

Claims (4)

[Claims] 1. A forging device in which a punch comprises a main punch and a constant pressure punch, and the load of the constant pressure punch can be set lower than the load of the main punch. 2. The forging device according to claim 1, wherein the main punch and the constant pressure punch are in a relationship of an inner punch and an outer punch. 3. The forging device according to claim 1, wherein the constant-pressure punch has a surface for closely engaging with a side surface of the die in the radial direction. 4. A die having a gear-shaped cavity is formed such that the diameter of the main punch is equal to the diameter of the root circle, the inner diameter is equal to the diameter of the main punch, and the outer circumference includes the diameter of the cutting edge circle. The forging device according to claim 1, 2 or 3, wherein a constant-pressure punch is concentrically arranged on the outer periphery of the main punch.