JPH11169995A - Structure of forging die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent burrs from generating in a joining surface between an upper die and a lower die and to high precisely hold the coaxiality between the upper die and the lower die. SOLUTION: A structure is composed of a force-fitting ring 20 in which a tapered hole part 19 is formed, a sleeve 24 which is formed into a nearly cylindrical shape and forced into the hole part 19, and the upper die 26 and the lower die 28 wherein a cavity 42 in which a forging stock is disposed is formed. An inclined surface part 21, which increases specific pressure in the joining surface between the upper die 26 and the lower die 28 by pressurizing the upper die 26 toward the lower die 28 side, is formed in one end part parallel to the axial direction of the inner peripheral surface of the sleeve 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forging die structure capable of integrally joining, for example, an upper die and a lower die constituting a die.

[0002]

2. Description of the Related Art Conventionally, a forging material is inserted into a forging cavity formed in an upper die and a lower die joined to each other, and a pressing force is applied to the forging material via a punch. 2. Description of the Related Art A mold apparatus for forging a material for use into a predetermined shape is known.

FIG. 12A shows a cold forging die devised by the present applicant (see Japanese Patent Application Laid-Open No. 7-178493).

[0004] The cold forging die 1 is provided on a die holder 5 and has a lower die 3 and an upper die 4 joined to each other via a fastening means 2. The lower die 3
A cavity 7 into which the forging material 6 is loaded is formed in the upper die 4 and a punch 8 for pressurizing the forging material 6 loaded into the cavity 7 is provided.

[0005]

However, in the cold forging die 1 according to the prior art, the joining surface A (partition surface) of the upper die 4 and the lower die 3 in the forming step.
(See FIG. 12B). A clearance is generated, and a burr may be generated due to the forging material that has been plastically deformed entering the clearance.

Further, a clearance 9 for assembling is provided in a joining portion 9 (see FIG. 12A) of the upper die 4 and the lower die 3 by the step portion.
And the lower die 3 are assembled in a state of misalignment within the range of the clearance, so that a product obtained by forging, for example, the coaxiality between the cup portion and the shaft portion of the outer cup constituting the constant velocity joint can be accurately determined. There is concern that it cannot be retained.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned various inconveniences, and prevents burrs from being generated at a joint surface between an upper die and a lower die. An object of the present invention is to provide a forging die structure capable of maintaining coaxiality with high accuracy.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a mold member having a tapered hole portion whose diameter gradually decreases from one side to the other side, and a substantially cylindrical shape member. A sleeve member formed and press-fitted into the hole, and an upper die and a lower die that are held by the sleeve member and have a cavity formed therein for disposing a forging material. A pressing portion for pressing either the upper die or the lower die toward the other is formed under the action of compressive stress generated when the hole is pressed into the hole.

In this case, the pressing portion comprises an inclined surface portion formed at one end of the inner peripheral surface of the sleeve member along the axial direction, and the upper die is directed toward the lower die under the pressing action of the inclined surface portion. Pressing increases the surface pressure of the joint surface between the upper die and the lower die.

Before the sleeve member is pressed into the hole of the mold member, a clearance is formed between the inner peripheral surface of the sleeve member and the outer peripheral surfaces of the upper die and the lower die. After being press-fitted into the portion, the inner peripheral surface of the sleeve member and the outer peripheral surfaces of the upper die and the lower die are brought into surface contact, whereby the upper die and the lower die are tightened by the sleeve member.

As described above, the upper die and the lower die can be firmly tightened via the sleeve member in a state where the surface pressure of the joint surface between the upper die and the lower die is increased. Therefore, by preventing the generation of the clearance between the joining surfaces of the upper die and the lower die, it is possible to prevent the occurrence of burrs. Further, there is no need to provide a clearance for assembling the upper die and the lower die, and the coaxiality of the upper die and the lower die can be maintained with high accuracy.

By forming an uneven portion on one of the inner peripheral surface of the sleeve member and the outer peripheral surface of the upper die and the lower die, and forming an uneven portion on the other,
The frictional force of the contact surfaces that are in surface contact with each other increases, so that the upper die and the lower die can be more firmly tightened via the sleeve member.

[0013]

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

In FIG. 1, reference numeral 10 denotes a forging die apparatus to which a forging die structure according to the present embodiment is applied. This forging die apparatus 10 is located near four corners. It has a first die holder 14 on which a plurality of guide means 12a to 12d are erected, and a second die holder 16 and a third die holder 18 provided at the center of the first die holder 14 in a stacked manner.

On the second die holder 16, a thick press-fit ring (mold member) 20 formed integrally is fixed via fastening means 22, and a hole 19 of the press-fit ring 20 is formed.
The upper die 26 and the lower die 2 are inserted through a sleeve (sleeve member) 24 formed in a thin cylindrical shape.
8 are integrally joined.

As shown in FIG. 3, the hole 19 of the press-fit ring 20 is formed in a tapered shape whose diameter gradually decreases from the lower part to the upper part in the assembled state. The surface is formed in a reverse tapered shape corresponding to the hole 19. Upper die 26,
The lower die 28 and the sleeve 24 are formed so as to be press-fitted into the holes 19 of the press-fit ring 20 as described later.

On the upper part of the inner peripheral surface of the sleeve 24,
A tapered inclined surface portion (pressing portion) 21 that gradually decreases in diameter toward the upper end edge portion is formed, and the inclined surface portion 21 exerts a force of pressing downward in the assembled state, Upper die 26 and lower die 28
Performs the function of increasing the contact pressure of the contact surface with the contact.

As shown in FIG. 5, before assembling, the gap between the outer peripheral surfaces of the upper die 26 and the lower die 28 and the inner peripheral surface of the sleeve 24 is predetermined (about 0.0
(2 mm). The outer peripheral surfaces of the upper die 26 and the lower die 28 have substantially the same dimensions along the axial direction, and are formed in a linear cross section.

On the inner peripheral side of the lower surface of the upper die 26, an annular convex portion 2 joined to the upper surface of the flat lower die 28 is provided.
5, a concave portion 31 is formed on the outer peripheral side of the lower surface of the upper die 26 to form a clearance with the upper surface of the flat lower die 28.

The fastening means 22 includes a press-fit ring 2
And a plurality of bolts 29 for holding the fixed plate 27 to the first die holder 14.

A punch 3 is provided on the upper surface of the upper die 26.
First ring body 34 in which hole 32 into which 0 is press-fitted is formed.
Are integrally joined, and a second ring body 36 externally fitted to the first ring body 34 is integrally joined to the upper surface of the sleeve 24. In this case, the first ring body 34 and the second ring body 36 may be integrally formed as ring bodies instead of being formed separately.

The first ring body 34 is made of, for example, a super hard material and subjected to shrink fitting.
6 is strongly tightened toward the center. Further, the first ring body 34 and the second ring body 3
The upper die 26, the lower die 28, and the sleeve 2 are tightened by the tapered portion 41 of the fastening ring 40 screwed into the screw hole 39 of the press-fit ring 20.
4 and are integrally joined.

In this case, a cavity 42 is formed by the first ring body 34, the upper die 26 and the lower die 28, and a knockout pin 44 for extruding a forged product is provided below the cavity 42 with the second die holder 16 and The third die holder 18 is disposed so as to be able to advance and retreat along a hole 46 formed in the third die holder 18. A secondary molded product 48 as shown in FIG. 9D is loaded into the cavity 42 as a forging material.

Above a predetermined distance from the press-fit ring 20, a ram (not shown) of a mechanical press (not shown) is connected, and is displaced vertically with the ram under the driving action of the mechanical press. An elevating member 50 is provided. The punch 30 is fixed to the elevating member 50 via a jig 52, and a guide sleeve 54 formed of a cylindrical metal material is fitted on a predetermined portion of the outer peripheral portion of the punch 30.

As shown in FIG. 4, a graphite 56 is embedded in the guide sleeve 54 through a plurality of holes, and has lubricating properties when press-fitted into the holes 32 of the first ring body 34. Can be favorably maintained. Also,
The outer diameter of the guide sleeve 54 externally fitted to the punch 30 is set slightly larger than the inner diameter of the hole 32 of the first ring body 34.

The guide sleeve 54 is made of, for example, S
It is preferable that the first ring body 34 be formed of a material harder than the guide sleeve 54, such as a metal material such as KD11, FC25, or FC30.

The punch 30 is provided so as to be displaceable along the vertical direction integrally with the elevating member 50 under the guiding action of a plurality of guide means 12a to 12d erected on the first die holder 14.

The forging die apparatus 10 to which the forging die structure according to the embodiment of the present invention is applied is basically constructed as described above. explain. In the following, a case where an outer cup forming a constant velocity joint is forged as a forged product will be described as an example.

By performing first forging on a cylindrical billet 76 as shown in FIG. 9A by a mold device (not shown), the diameter of the billet 76 is increased through a middle step as shown in FIG. 9B. Different primary molded articles 78 are obtained. Subsequently, after performing preliminary forming on the primary molded product 78 (see FIG. 9C), secondary forging is performed by another mold device (not shown), as shown in FIG. 9D. The secondary molded product 48 including the cup portion 80 and the shaft portion 82 is obtained.

In the forging die apparatus 10, a third forging is performed using the second molded product 48 as a forging material.

The process of assembling the mold will be described below. 5 and 6, the shape of the press-fit ring 20 is partially changed for convenience of explanation.

As shown in FIG. 5, first, the sleeve 2
The upper die 26 and the lower die 28 are mounted in the holes of the sleeve 24 in a state where the inclined surface portion 21 of 4 is downward. In this case, except for the inclined surface portion 21 that holds the upper die 26, the inner peripheral surface of the sleeve 24 and the outer peripheral surfaces of the upper die 26 and the lower die 28 are set to be separated via a predetermined clearance 23. Have been. A lubricant is applied to the outer peripheral surface of the sleeve 24, and the inner peripheral surface of the sleeve 24 is previously degreased to be in a non-lubricated state.

Subsequently, as shown in FIG. 5, the upper die 26 and the lower die 28 are placed in a state where the upper surface and the lower surface of the press-fit ring 20 are reversed and the diameter of the hole 19 is increased. The press-fit sleeve 24 is press-fitted along the hole 19 of the press-fit ring 20 in the direction of the arrow. In this case, under the lubricating action of the lubricant applied to the outer peripheral surface of the sleeve 24,
The sleeve 24 is smoothly press-fit along the hole 19 of the press-fit ring 20.

In the hole 19, the sleeve 24 and the upper die 2
6 and the lower die 28 are press-fitted,
The state shown in FIG. 6 is obtained by reversing the vertical direction of 0. In this case, as shown in FIG.
4, a downward pressing force (in the direction of arrow B) acts on the inclined surface portion 21, and the pressing force increases the surface pressure of the joint surface between the upper die 26 and the lower die 28.

Further, when the sleeve 24 is press-fitted into the tapered hole portion 19, a compressive stress is applied to the sleeve 24 to tighten the sleeve 24 toward the center, and the inner peripheral surface of the sleeve 24 in a non-lubricated state. The clearance 23 between the upper die 26 and the outer peripheral surface of the upper die 26 and the lower die 28 is eliminated, and the inner peripheral surface of the sleeve 24 and the upper die 26 are removed.
And the outer peripheral surface of the lower die 28 comes into surface contact with each other.

Therefore, under the action of compressive stress, the inner peripheral surface of the sleeve 24 and the upper die 26 and the lower die 28
The upper die 26 and the lower die 2 are locked by a tightening force acting to bring the outer peripheral surfaces of the upper die 26 and the lower die 28 into contact with each other.
8 can be held in a state where the surface pressure of the bonding surface is increased.

As described above, in the forging die structure according to the present embodiment, the surface pressure of the joining surface between the upper die 26 and the lower die 28 is maintained in an increased state, so that the upper die 26 and the lower die 28 The burr is prevented from being generated on the joint surface of the upper die 26 and the coaxiality between the upper die 26 and the lower die 28 can be maintained with high accuracy.

As shown in FIG. 8, the upper die 26, the lower die 28 and the sleeve 24, which are press-fitted into the holes 19 of the press-fit ring 20, are pressed in the direction of the arrow by the pressing device P, thereby forming the upper die. 26, the lower die 28 and the sleeve 24 can be removed from the press-fit ring 20 and easily replaced. As a result, the efficiency of maintenance can be improved, the versatility can be improved, and the management cost of the mold can be reduced.

As shown in FIG. 7A, on the inner peripheral surface of the sleeve 24 which comes into surface contact with each other, for example, a convex / concave portion (or concave / convex portion) 83a is formed by lace processing or the like, and the upper die 26 and the lower die By forming concave and convex portions (or convex and concave portions) 83b and 83c respectively on the outer peripheral surface of 28, and increasing the frictional force at the time of surface contact,
The joint state between the upper die 26 and the lower die 28 can be more firmly locked (see FIG. 7B).

Subsequently, the first ring body 34 and the second ring body 36 are arranged on the upper die 26 and the sleeve 24, and the fastening ring 4 is formed along the screw hole 39 of the press-fit ring 20.
By screwing 0, the first ring body 34 and the second ring body 36 are integrally assembled with the upper die 26, the lower die 28, and the like under the tightening action of the tapered portion 41 of the fastening ring 40. Thus, the die assembling step is completed.

FIG. 11 shows another application example of the forging die structure shown in FIG. Note that components corresponding to the components shown in FIG. 3 are described below with the same reference numeral appended with a.

As will be understood from FIG. 11, the hole 19a of the press-fit ring 20a is formed in a tapered shape whose diameter is gradually reduced from the upper part to the lower part in the assembled state. The outer peripheral surface is formed corresponding to the hole 19a. Also, sleeve 2
At the lower part of the inner peripheral surface of 4a, there is formed a tapered inclined surface portion 21a whose diameter gradually decreases toward the lower end edge. The reference numeral 90 indicates the first ring body 34 shown in FIG.
And a second ring body 36 integrally formed.

In another application example, in a state in which the inclined surface portion 21a formed on the sleeve 24a is assembled, a force for pressing the lower die 28a upward is applied to the lower die 28a to thereby lower the lower die 24a against the sleeve 24a. It functions as a stopper for 28a. Also, the ring body 90 is pressed downward by the tapered portion 41a under the screwing action of the fastening ring 40a into the screw hole 39a, and a lower pressing force is applied to the upper die 26a, thereby causing the upper die 26a to be pressed. 26a and lower die 28a
The contact pressure of the contact surface with the contact is increased.

As described above, in another application example, when the forging is continuously performed, the lower die 28a is prevented from falling down, and the pressing of the ring body 90 causes the lower die 28a to be pressed. Upper die 26 within the allowable range
There is an advantage that the surface pressure of the contact surface between the a and the lower die 28a can be freely set.

Next, in a state where the punch 30 is arranged at a raised position (not shown), the cavity 42 is loaded with a secondary molded product 48 as a forging material. Then, under the driving action of a mechanical press (not shown), the punch 30 descends integrally with the elevating member 50 connected to a ram (not shown), and forging is started when the state shown in FIG. 1 is reached.

When the punch 30 descends integrally with the elevating member 50, the elevating member 50 and the first die holder 14
And a plurality of guide means 12a to 12d provided between the first ring body 34 and the punch 30 through the guide sleeve 54.
2 can be smoothly pressed into the center.

When forging is started, the guide sleeve 54 fitted to a part of the outer peripheral surface of the punch 30 is formed into an annular groove (shown in the figure) formed at the upper end of the hole 32 of the first ring body 34. )) And the punch 3
When 0 is lowered, the punch 30 and the guide sleeve 54 are integrally displaced while being pressed into the hole 32 of the first ring body 34.

In this manner, the punch 30 is lowered, and FIG.
2 from the forming start position shown in FIG. 2 to the forming end position shown in FIG. 2, forging is performed on the forging material via the punch 30, the lower die 28 and the upper die 26, and the forging is performed. The material plastically flows along the shape of the cavity 42.

In this case, as described above, the upper die 2
Since the surface pressure of the joint surface between the lower die 6 and the lower die 28 is maintained in an increased state, it is possible to prevent a clearance from being generated at the joint surface between the upper die and the lower die, thereby preventing burrs from being generated. be able to.

After the forging is completed in this way, the punch 30 is raised to a predetermined position integrally with the lifting member 50 connected to the ram (not shown) under the driving action of a mechanical press (not shown). Then, the punch 30 and the guide sleeve 54 are separated from the hole 32 of the first ring body 34, and are in a standby state for the next step. Then, the forged product 84 (see FIG. 9) is taken out under the displacement action of the knockout pin 44.

In the forging die structure according to the present embodiment, burrs are prevented from being formed on the joint surface between the upper die 26 and the lower die 28 and the upper die 26 and the lower die 28 are prevented from forming.
1 can be maintained with high accuracy.
As shown in FIG. 0, the coaxiality between the axis E of the cup portion 86 of the outer cup obtained as the forged product 84 and the axis F of the shaft portion 88 can be maintained with high precision.

In the present embodiment, the outer cup constituting the constant velocity joint is used as a material for forging. However, the present invention is not limited to this. For example, a stepped part (not shown), a stepped gear, etc. It is needless to say that the present invention can be applied to various forged products requiring coaxial accuracy between a part of a part and another part.

[0053]

According to the present invention, the following effects can be obtained.

That is, it is possible to prevent burrs from being generated on the joint surface between the upper die and the lower die, and to maintain the coaxiality between the upper die and the lower die with high precision. As a result, the coaxiality between one part and the other part of the obtained forged product can be maintained with high accuracy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a forging die apparatus to which a forging die structure according to an embodiment of the present invention is applied.

FIG. 2 is an operation explanatory view showing a state where a punch descends from a forging start position shown in FIG. 1 and forging is completed.

FIG. 3 is an enlarged view of a die constituting the forging die apparatus shown in FIG.

FIG. 4 is a perspective view of a guide sleeve externally fitted to the punch.

FIG. 5 is an explanatory view showing a state in which an upper die and a lower die are press-fitted into a press-fit ring via a sleeve.

FIG. 6 is an explanatory view showing a state in which an upper die, a lower die, and a sleeve are press-fitted into a hole of a press-fit ring.

7A is a partial sectional view showing a state before press-fitting by forming uneven portions on the inner peripheral surface of the sleeve and the outer peripheral surfaces of the upper die and the lower die, respectively, and FIG. FIG.

FIG. 8 is a cross-sectional view showing a state in which an upper die and a lower die pressed into the hole of the press-fit ring are taken out.

FIG. 9A to FIG. 9D are explanatory views showing a manufacturing process of an outer cup constituting the constant velocity joint.

10 is a longitudinal sectional view of a forged product forged by the forging die apparatus shown in FIG.

11 is a longitudinal sectional view showing another application example of the forging die structure shown in FIG.

12A is a longitudinal sectional view of a cold forging die according to the prior art devised by the present applicant, and FIG. 12B is FIG. 12A.
FIG.

[Explanation of Signs] 10 ... Forging die apparatus 12a to 12d
... Guide means 14, 16, 18 ... Die holder 20, 20a ...
Press-fit ring 21, 21a ... inclined surface 23 ... clearance 24, 24a ... sleeve 25 ... convex part 26, 26a, 28, 28a ... die 30 ... punch 32, 46 ... hole 34, 36, 9
0 ... Ring body 40, 40a ... Fastening ring 42, 42a ...
Cavity 44 ... Knockout pin 50 ... Elevating member 54 ... Guide sleeve 84 ... Forged product

Claims (4)

[Claims] 1. A mold member having a tapered hole gradually reduced in diameter from one side to the other, a sleeve member formed in a substantially cylindrical shape and pressed into the hole, and the sleeve member. And an upper die and a lower die in which a cavity for disposing a forging material is formed, and wherein the sleeve member is subjected to a compressive stress generated when the sleeve member is press-fitted into the hole, A forging die structure, wherein a pressing portion for pressing one of the upper die and the lower die toward the other is formed. 2. The forging die structure according to claim 1, wherein the pressing portion comprises an inclined surface portion formed at one end of the inner peripheral surface of the sleeve member along the axial direction, and the pressing portion is under a pressing action of the inclined surface portion. A forging die structure wherein the surface pressure of the joint surface between the upper die and the lower die is increased by pressing the upper die toward the lower die side. 3. The forging die structure according to claim 1, wherein a clearance is provided between the inner peripheral surface of the sleeve member and the outer peripheral surfaces of the upper die and the lower die before the sleeve member is pressed into the hole of the die member. After the sleeve member is press-fitted into the hole of the mold member, the inner peripheral surface of the sleeve member comes into surface contact with the outer peripheral surfaces of the upper die and the lower die, so that the upper die and the lower die are formed by the sleeve member. Forged die structure characterized by being tightened. 4. The forging die structure according to claim 3, wherein one of an inner peripheral surface of the sleeve member and an outer peripheral surface of the upper die and the lower die has an uneven portion, and the other has an uneven portion. A forging die structure characterized by being formed.