JPH0741352B2 - dice - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die used for forging or forging bolts, nuts and other mechanical parts.

[0002]

2. Description of the Related Art As shown in FIG. 7, such a die has a mold member (3) having a mold hole (33) fitted to a reinforcing ring (57) through an intermediate sleeve (4). Mold unit (2)
The mold unit (2) is housed in the support case (1).

During press forming, a large tensile stress acts on the die member (3) in the radial direction and the tangential direction due to the impact of the punch applied to the die hole (33). As shown in FIG. 10, the radial stress σr has a maximum value in the die hole (33) and decreases to zero toward the outer circumference. The tangential tensile stress σt is
It has the maximum value in 3) and decreases toward the surroundings. In order to prevent the die member (3) from being damaged by these stresses, the die member (3) is press-fitted or shrink-fitted into the intermediate sleeve (4), and further, this is press-fitted into the reinforcing ring (57), whereby The die member (3) is reinforced under the preload of the pressing force.

The reinforcing ring (57) is generally a single ring made of die steel, but it is more effective to have a multiple ring structure for the tensile stress in the tangential direction. I know. Therefore, as shown in FIG.
Metal strips on the outer circumference of the intermediate sleeve (4) instead of multiple rings
It has been proposed to wind the (59) in a coil to form a reinforcing ring (58) and press-fit the mold member (3) into the intermediate sleeve (4) to extend the service life of the mold member (Japanese Patent Laid-Open No. Hei 10 (1999) -58242). 2-15133
8). The applicant has studied the die (hereinafter, referred to as “coil reinforcement die”) in which the metal strip (59) is wound into a coil to form the reinforcement ring (58), and as a result, the following conclusions were obtained.

The coil-reinforcing die has a life span slightly less than twice as long as that of the die using the conventional die steel reinforcing ring (57), but the price is several tens of times, and the overall cost is significantly high. Invite.

If the reinforcing ring 57 made of die steel is used, the reinforcing ring 57 can be press-fitted or shrink-fitted to the intermediate sleeve 4 to easily apply radial stress. In the case of (59), it is not easy to wind this around the mold member (3) and to apply compressive stress in the radial direction. At the beginning of winding to maximize the stress, apply a strong tensile force to the metal strip.
It is impossible to tighten (59).

When the metal strip plate (59) is wound in a coil by applying a uniform tensile force, looseness occurs at the middle portion, and the outer side of the loosened portion presses the intermediate sleeve (4) in the radial direction. Does not contribute at all. Not only the metal strip plate (59) but also a strip material that is applied with a uniform pulling force causes looseness in the middle portion. This is because when the strips are wound and the strips are stacked, the tensile force against the strips in the upper layer acts as a pressing force toward the center of the strips in the lower layer, and the pressing force from the upper layer causes A reaction force acts in the outward radial direction. This reaction force causes the metal strip
This is because a force in the direction opposite to the tightening direction acts on (59), and as a result, the pressing force in the radial direction is reduced.This phenomenon is due to the winding state of the toilet paper. This is the same phenomenon as the paper in Rippling.

By changing the winding tension for each winding layer of the metal strip plate (59), the above problem is solved and the stress distribution acting on the die at the time of forging shown in FIG. The appropriate stress distribution with the intermediate sleeve
Although it can be applied to (4), it is extremely difficult to wind the metal strip plate (59) in the width direction under the same conditions and while changing the winding tension, and it is not practical.

The intermediate sleeve (4) of the die shown in FIG. 7 is omitted, and the reinforcing ring (57) is directly press-fitted into the die member (3) to distribute the joining pressure in the height direction and the die member (3). Considering the relationship between the total height of the and the total height of the reinforcing ring (57),
It is most not the case that the height of the mold member (3) is surrounded by the reinforcing ring (57) in the radial direction from the upper surface of the mold member (3) to the depth of the mold hole (33). It has been found that stress concentration is reduced. However, the coil-reinforcing die shown in FIG. 8 has a metal strip plate (5) having the same width as the entire height of the die member (3).
9) is wound, and it cannot be partially reinforced corresponding to the depth of the die hole (33) of the die member (3), which is disadvantageous in terms of stress concentration.

Since the metal strip (59) cannot be wound around the tapered surface, the outer circumference of the intermediate sleeve (4) must be a cylindrical surface. Intermediate sleeve with tapered outer circumference (4)
On the other hand, it is not possible to directly wind the metal strip around the die member (3) having a tapered outer circumference by omitting the intermediate sleeve.
Based on the above conclusion, the applicant has sought an alternative to the metal strip (59), and has devised a die superior to the coil reinforcement die.

[0011]

[Means for Solving the Problems] The die of the present invention comprises a molding die hole (3
The reinforcing ring (5) is fitted to the mold member (3) having 3) in a state where a pressing force is applied in the radial direction, and the reinforcing ring (5)
In the die that fits the support case (1) into the die member (3)
The diameter of the mold hole (33) is tapered, and the inner surface of the reinforcing ring (5) is tapered corresponding to the outer circumference of the mold member (3).
The reinforcing ring (5) is formed by winding a strand (55), which is obtained by bundling advanced fibers having excellent strength and rigidity such as carbon fiber and aramid fiber, around the ring member (51) in a multi-layered state by stretching the strand (55). ), The number of turns is larger toward the die hole (33) side in the axial direction of the die member (3), and the strand (55) is the die member.
In the axial direction of (3), the coil is wound with a stronger tensile force toward the die hole (33) side.

[0012]

[Action and effect] The advanced fiber has the strength per unit cross-sectional area,
Rigidity is better than steel. The steel is homogeneous and integrated, but even if the strand in which the advanced fiber is bundled is wound in a tensile state, there are some gaps between the fibers, so the cross-sectional area of the wound layer is multiplied by the strength of the advanced fiber. The strength of the advanced fiber is higher than that of steel even if these factors are taken into consideration. However, the strand (55) is easier to handle than a metal strip, and the tension can be easily adjusted during winding, and the strand (55) is tightly wound around the die cavity where strong reinforcement is required, and other It can be easily wrapped around the place.

Therefore, the durability of the die for reinforcing the die member (3) by winding the strand in a strongly tensioned state and preloading the strand is higher than that of the die and coil reinforcing die reinforced by the conventional die steel reinforcing ring. Is also excellent. Therefore, it can contribute to reducing the diameter of the die. In addition, the adjustment of the tensile force on the strand and the workability of winding are much better than when winding a metal strip, and a strong tensile force is applied at the beginning of winding when the stress should be maximized. You can

Of the internal pressure acting on the die member (3), the radial pressure and the tangential tensile force are applied to the upper portion on the die hole (33) side, and the axial pressure acts on the lower portion, so that the reinforcing ring.
(5) requires a reinforcing effect on the upper part rather than the lower part. This requirement can be fulfilled by winding the strand (55) from above into the upper part of the die hole (33) while applying a strong tensile force, and also to the inner ring member (5) of the reinforcing ring (5).
It is also realized by making 1) a taper shape and increasing the winding amount of the upper part than that of the lower part.

[0015]

FIG. 1 shows a first embodiment. In the drawing, the cross-sectional hatching of the support case (1) and the attached mold stand are omitted. The support case (1) is made of a hardened steel having a high tensile strength and a soft hardness, and is formed into a cylindrical shape. Screw hole (13)
Has been established. Mold insertion hole (11) and lifting table insertion hole (12)
Are both straight holes, and the die insertion hole (11) has a larger diameter than the lifting table insertion hole (12).

The mold unit (2) is press-fitted into the mold insertion hole (11) of the support case (1). The mold unit (2) is formed by reinforcing the mold member (3) with the reinforcing ring (5) through the intermediate sleeve (4). The mold member (3) is made of cemented carbide and is composed of an upper mold (31) and a lower mold (32) which are axially divided into two parts.
(31) has a die hole (33) at its axis, and the lower die (32) has the die hole on the upper surface.
A mold cavity (34) continuous with (33) is formed.

A knockout pin guide hole (35) penetrating the push-up base (6) is formed in the shaft center of the lower mold (32). The outer peripheral surfaces of the upper and lower molds (31, 32) are tapered surfaces whose diameter is reduced on the upper mold side. Multiple vertical grooves for air escape around the lower die (32)
(36) has been opened.

The intermediate sleeve (4) is made of die steel, the inner surface of which is formed as a tapered surface corresponding to the outer circumference of the die member (3), and the outer circumference of the intermediate sleeve (4) is slightly tapered as compared with the inner circumference. . The upper and lower molds (31) (32) are fitted into the intermediate sleeve (4) by pre-pressing under a pressing force in the radial direction by press fitting or shrink fitting.

The reinforcing ring (5) has outer flanges (52) (53) at both axial ends of an inner ring member (51) formed in a tapered shape corresponding to the outer peripheral tapered surface of the intermediate sleeve (4). Wide peripheral groove (50) formed between the flanges (52) and (53)
A strand (55) is wound around and a cylindrical outer ring member (54) is fitted over the flanges (52) and (53).

In the embodiment, carbon fiber (55a) having a thickness of 10 μm is used.
The above 3000 pieces are bundled into one strand (55) and wound on the inner ring member (51). When winding the strand (55), the tension is stronger toward the inner layer side in the radial direction,
As shown in FIG.
A preload corresponding to the radial stress acting on the die at the time of forging is applied. The lower die (32) to the upper die (3
The tension is increased toward 1) and the stress in the portion corresponding to the upper die (31) is increased. The value of the initial tension is
The strength of each advanced fiber is slightly smaller than that of the advanced fiber, and the tension at the end of winding is set to the minimum tension that can be controlled by the control device (83) of the winding device described later.

Further, in the embodiment, the strand (55) is wound while adhering the epoxy resin thereto, and the strand (55) is fixed with the epoxy resin (56). Epoxy resins are convenient because they have the property of not shrinking when solidified, but they are not necessarily epoxy resins. The winding end of the strand (55) is
Even if it is free, the tension does not loosen, but it is bonded with the above resin.

As shown in FIG. 1, the push-up base (6) is slidably inserted into the push-up base insertion hole (12), and the bottom surface of the die unit (2) is supported by the tip end surface of the base and the internal screw is used. Fastening stand (7) in hole (13)
Is screwed in to prevent the push-up base (6) from coming off.

In FIG. 8, the strand (55) is connected to the inner ring member (5
1) shows the outline of the winding device, and the inner ring member (5
1) is connected to the torque motor (8) and rotatably supported at a fixed position. The tip of the strand (55) is wound around the inner ring member (51) from a drum (not shown) around which the strand (55) is wound, via the localization roller (81) and the dancing roller (82).

The torque motor (8) and the dancing roller moving device (84) are connected to the control device (83), and the control device (8)
It operates as programmed in advance in the computer of 3), and as described above, the inner ring member (51) is wound in the radial direction and the height direction while adjusting the tension.

At the beginning of winding the strand (55), as shown in FIG. 1, a fine groove (50a) is opened at the end of the large diameter portion of the inner ring member (51), and the strand (55) is formed in the fine groove (50a). ) Is manually wound, and thereafter, the torque motor (8) and the dancing roller (82) are automatically wound by the connecting operation.

However, the advanced fiber is superior to steel in strength and rigidity per unit cross-sectional area. Therefore, the strand in which the advanced fiber is bundled is wound in a tension state and a preload is applied to the mold member (3). The durability of the reinforced die is superior to that of the die reinforced with the conventional die steel reinforcing ring and the coil reinforced die. Therefore, it can contribute to reducing the diameter of the die. The strand (55) is easier to handle than a metal strip, and the workability of winding is much better than when winding a metal strip. Further, the tension of the strand can be easily adjusted during winding, and it is easy to wind the strand strongly around the die hole of the die, which requires particularly strong reinforcement, and weakly at other places.

Dies for hot forging and warm forging need to maintain their strength at high temperatures. With conventional reinforcing rings made of die steel, during use in hot and warm regions, Although the tightening force becomes weaker due to the coefficient of thermal expansion of the die steel, the coefficient of thermal expansion of carbon fiber is smaller than that of the die steel, so it is difficult to be affected by heat.

Of the internal pressure acting on the die unit (2), the radial pressure and the tangential tensile force are applied to the upper die (31), and the axial pressure acts on the lower die (32), so that the reinforcement is reinforced. The ring (5) is required to have a reinforcing effect on the upper mold (31) rather than the lower mold (32). This requirement can be achieved by winding the strand (55) with the upper mold (31) side from the lower mold (32) side under a strong tensile force, and as in the embodiment, the reinforcing ring. The inner ring member (51) of (5) is tapered, and the upper die (31)
It is also realized by increasing the winding amount on the side of the lower die (32).

In the practice of the present invention, the type of fiber is changed such that the inner layer of the wound layer of the strands (55) is aramid fiber and the outer layer is carbon fiber, or the same carbon fiber has a particularly high inner layer. The outer layer can be selected in consideration of characteristics, price, etc., such as one having particularly high strength.

FIG. 2 omits the intermediate sleeve, and the mold member (3)
A second embodiment is shown in which is directly pressed into the reinforcing ring (5). Further, the push-up base (6) is shrink-fitted to the support case (1), and the tightening base is also omitted.

FIG. 3 shows a third embodiment in which the upper and lower integrated mold members (3) are directly press-fitted into the reinforcing ring (5).

FIG. 4 shows a fourth embodiment in which a wide groove (50b) is formed on the outer peripheral surface of a tapered ring member (51a) and a strand (55) is wound around the groove to form a reinforcing ring (5). Shows. The wide groove (50b) is located near the bottom of the die hole (33)
It is shallowly formed on the (6) side. The reinforcing ring (5) is press-fitted into the tapered hole (11a) of the support case (1), and in this state, the die member (3) is press-fitted or shrink-fitted to the reinforcing member (5).

FIG. 5 shows a fifth embodiment in which the wall thickness of the upper flange of the tapered ring member (51) is reduced.

FIG. 6 shows a sixth embodiment in which the upper flange of the tapered ring member (51) is omitted. Even if the flange is omitted, by forming the outer surface of the inner ring member (81) in a stepwise manner, the strand (5
It has been confirmed that 5) can be wound. The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a sectional view of a second embodiment.

FIG. 3 is a sectional view of a third embodiment.

FIG. 4 is a sectional view of a fourth embodiment.

FIG. 5 is a sectional view of a fifth embodiment.

FIG. 6 is a sectional view of a sixth embodiment.

FIG. 7 is a sectional view of a conventional die using a reinforcing ring made of die steel.

FIG. 8 is a cross-sectional view of a coil reinforcing die.

FIG. 9 is a schematic view of a winding device.

FIG. 10 is a stress distribution diagram that acts during forging.

[Explanation of symbols]

 (1) Support case (2) Mold unit (3) Mold member (4) Intermediate sleeve (5) Reinforcement ring (55) Strand

Claims (5)

[Claims] 1. A reinforcing ring (5) in a state in which a radial pressing force is applied to a mold member (3) having a molding die hole (33).
In the die in which the reinforcing ring (5) is fitted in the support case (1), the die member (3) is tapered on the die hole (33) side, and the inner surface of the reinforcing ring (5) is the die member. The reinforcing ring (5) is formed into a tapered surface corresponding to the outer circumference of (3), and the reinforcing ring (5) is a ring member.
(51) is formed by winding a strand (55) obtained by bundling advanced fibers having excellent strength and rigidity such as carbon fiber and aramid fiber in a tensile state, and the number of turns of the strand (55) is a mold member ( 3) in the axial direction toward the die hole (33) side, and the strands (55) are in the die hole (3) in the axial direction of the die member (3).
3) Die that is wound with increasing tensile strength toward the side. 2. An outer ring member (5) is provided on the outer surface of the strand winding layer.
The die according to claim 1, which is configured by fitting 4). 3. The die according to claim 1, wherein a gap between the fibers of the wound strands (55) is filled with a synthetic resin such as an epoxy resin to maintain the shape. 4. The die according to claim 1, wherein an intermediate sleeve (4) is interposed between the mold member (3) and the reinforcing ring (5). 5. The die according to claim 1, wherein the wound layer of the strand (55) has different types or characteristics of the advanced fiber in the inner layer and the outer layer.