JP2000135539A - Plate thickness increasing method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a sink mark and material overlapping around an inner/outer periphery of a boss when a part having a boss at its flange is cold forged by making an upper die energizing means and a punch energizing means independent, and also deciding an energizing force thereof individually. SOLUTION: An upper die pin 8 is energized by an upper die gas pressure cylinder 24 via an upper die piston 26. When the upper die gas pressure cylinder 24 is adjusted, a force for energizing an upper die 23 can be adjusted. The upper die pin 8 is energized by a means different from the one for the punch 21. An upper die spring 25 energizes the upper die pin 8 towards the upper die 23 so that the upper die piston 26 and the upper die pin 8 are not detached. A force to be energized by the punch is individually adjusted with the usage of hydraulic and the like. When a core bar 4 is inserted into a hole of a material, and a sliding processing is carried out by a press machine, the punch and the upper die are lowered. Cold forging of the material is thus carried out with the cooperation of the bottom die, the punch, the core bar 4 and the upper die.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for obtaining a part having a boss on a flange by cold forging.

[0002]

2. Description of the Related Art Conventionally, such cold forging has been performed by the method shown in FIGS. 3 (A), 3 (B) and 3 (C).
That is, as shown in FIG. 2A, a metal core is inserted into a hole of a material, the upper end surface of the boss portion of the material is pressed with a punch, and the flange portion of the material is pressed with a die. In this case, the die is fixed to the upper die. Therefore, the material of the boss portion flows to the flange side as shown in FIG.
It protrudes between the upper die and the lower die, and inserts it between the upper die and the lower die.
Occurred and was a defect.

Further, when a thick boss is to be formed from a relatively thin material, buckling of the material causes sink marks K3 and material overlap K4 on the inner periphery of the boss. Overlap K5 sometimes occurred.

On the other hand, as shown in FIG. 1C, the boss portion is in a hermetically closed state at the bottom dead center when the boss is formed. At this time,
The volume of the boss portion varies due to the variation in the thickness of the material and the influence of press forming in the previous process. For this reason, when the volume of the boss portion is larger than the setting, the overload (3
4) occurred and was often damaged. Conversely, when the volume of the boss portion is smaller than the setting, as shown in the figure on the left side, sink marks K2 having insufficient volume remain on the inner and outer peripheries of the boss, and a predetermined shape accuracy could not be obtained. Therefore, in order to reduce the variation in the volume of the boss portion as much as possible, it has been necessary to use an expensive plate material having a strict thickness tolerance.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method and an apparatus for obtaining a part having a boss on a flange by cold forging, which does not cause sink marks or material overlap on the inner and outer circumferences of the boss. That is. Another object of the present invention is to provide a product having a good boss inner and outer diameter precision by preventing the boss portion from buckling when a thick boss is press-formed from a relatively thin plate material.

Further, even when the volume of the boss portion varies during the boss molding, it is possible to prevent the die from being overloaded, to provide a means for extending the life of the die, and at the same time, to provide an inexpensive plate thickness tolerable to some extent. Is to be able to use a suitable board material.

[0007]

According to the present invention, a core is inserted into a hole of a material, a resistance is applied to a flange portion of the material, and a punch for pressing an upper end surface of a boss of the material and a die for pressing the flange portion. Are provided so as to be relatively movable in the vertical direction.
More specifically, the invention of claim 1 is a method for obtaining a product having a boss portion on a flange by cold forging.
A punch that urges the upper end surface of the boss portion of the material, an upper die that urges the flange portion of the material, and a lower die that faces the upper die;
It has a metal core provided in the lower mold, the punch is provided on the outer peripheral portion of the metal core, the upper die is provided on the outer peripheral portion of the punch, and the punch and the upper die are vertically moved together. Using a mold having a structure capable of relative movement and a means for preventing the material from flowing to the flange portion, the means for urging the upper die and the means for urging the punch are independent of each other. And, when the boss is formed as a configuration in which the biasing force can also be independently determined, when the volume of the boss portion is larger than the setting, the punch cannot press the upper end face of the boss anymore when the punch is in a sealed state. When the boss height is higher than the setting and the volume of the boss portion is lower than the setting, the punch presses the upper end surface of the boss more than the setting and reduces the urging force of the punch so that the boss height becomes lower than the setting. Configuration That. On the other hand, at the time of boss molding, the volume of the boss is set to the smallest amount, and when the volume is larger than that setting, an extra volume flows out to the flange near the corner of the outer periphery of the boss, and the upper die is pushed upward, and the boss is raised. The urging force of the upper die is set so that the height is constant, the core is inserted into the hole of the material, and the material is formed by the punch and the die to obtain a product.

According to a second aspect of the present invention, in the first aspect, the means for preventing the material of the material from flowing to the flange portion is a projection provided on the upper die or the lower die.

According to a third aspect of the present invention, in the first aspect, the means for preventing the material from flowing to the flange portion is a concave portion provided on the lower die for restraining an outer peripheral portion of the material.

According to a fourth aspect of the present invention, there is provided an apparatus for obtaining a product having a boss portion on a flange by cold forging, comprising: a punch for urging an upper end face of the boss portion of the material; and an upper die for urging the flange portion of the material. A lower die facing the upper die, having a metal core provided in a lower mold, disposing the punch on an outer peripheral portion of the metal core, disposing the upper die on an outer peripheral portion of the punch, The punch and the upper die have a structure capable of moving relative to each other in the vertical direction, and prevent the material of the material from flowing to the flange portion, and the means for urging the upper die and the means for urging the punch are: When the boss is formed, if the volume of the boss is larger than the setting, press the top end face of the boss any more when the punch is closed. Can no longer do If the height is higher than the setting and the volume of the boss is smaller than the setting, the punch presses the upper end surface of the boss more than the setting and sets the urging force of the punch so that the boss height is lower than the setting. I do. On the other hand, at the time of boss molding, the volume of the boss is set to the smallest amount, and when the volume is larger than that setting, an extra volume flows out to the flange near the corner of the outer periphery of the boss, and the upper die is pushed upward, and the boss is raised. Means is provided for setting the urging force of the upper die so that the height is constant.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the means for preventing the material of the raw material from flowing to the flange portion is a projection provided on the upper die or the lower die.

According to a sixth aspect of the present invention, in the invention of the fourth aspect, the means for preventing the material of the material from flowing to the flange portion is a concave portion provided on the lower die for restraining an outer peripheral portion of the material.

According to a seventh aspect of the present invention, there is provided a method for obtaining a product having a boss portion on a flange by cold forging, wherein a punch for urging an upper end face of the boss portion of the material and an upper die for urging the flange portion of the material are provided. A lower die facing the upper die, having a metal core provided in a lower mold, disposing the punch on an outer peripheral portion of the metal core, disposing the upper die on an outer peripheral portion of the punch, Means for biasing the upper die using a mold having a structure in which the punch and the upper die can move relative to each other in the vertical direction, and having a means for preventing the material of the material from flowing to the flange portion; The means for urging the punches are independent of each other, and the urging force can be independently determined.When molding the boss, if the volume of the boss is larger than the set value, the punch is closed at the time when the punch is closed. Press the top end of the boss any more. If the boss height is higher than the setting and the volume of the boss is less than the setting, the punch presses the upper end surface of the boss more than the setting so that the boss height becomes lower than the setting. Set the biasing force of the punch. On the other hand, at the time of boss molding, the volume of the boss is set to the smallest amount, and when the volume is larger than that setting, an extra volume flows out to the flange near the corner of the outer periphery of the boss, and the upper die is pushed upward, and the boss is raised. Set the biasing force of the upper die so that the height is constant,
The core metal is inserted into the hole of the material, and the shape of the tip of the punch is tapered from the inner diameter to the outer diameter or from the outer diameter to the inner diameter, and the material is formed by the punch and the die. Let the product.

According to an eighth aspect of the present invention, there is provided an apparatus for obtaining a product having a boss portion on a flange by cold forging, comprising: a punch for urging an upper end face of the boss portion of the material; and an upper die for urging the flange portion of the material. A lower die facing the upper die, having a metal core provided in a lower mold, disposing the punch on an outer peripheral portion of the metal core, disposing the upper die on an outer peripheral portion of the punch, The punch and the upper die have a structure capable of moving relative to each other in the vertical direction, and a means for preventing material from flowing to the flange portion is provided, and the shape of the tip of the punch is directed from the inner diameter portion to the outer diameter portion. Or a tapered shape from the outer diameter part to the inner diameter part, the means for urging the upper die and the means for urging the punch are independent from each other, and the urging force can be independently determined, and the boss Bolt volume during molding When the punch is more than the setting, the punch cannot press the upper end face of the boss any more when the seal is closed, the boss height becomes higher than the setting, and conversely, when the volume of the boss portion is lower than the setting. In the method, the biasing force of the punch is set so that the punch presses the upper end face of the boss more than the set value and the boss height is lower than the set value. On the other hand, at the time of boss molding, the volume of the boss is set to the smallest amount, and when the volume is larger than that setting, an extra volume flows out to the flange near the corner of the outer periphery of the boss, and the upper die is pushed upward, and the boss is raised. Means is provided for setting the urging force of the upper die so that the height is constant.

According to a ninth aspect of the present invention, in the first aspect, the tip of the boss portion of the material is tapered by the upper die from the inner diameter portion to the outer diameter portion or from the outer diameter portion to the inner diameter portion. Increase the thickness of the boss while preforming.

According to a tenth aspect of the present invention, in the fourth aspect,
A means is provided to increase the thickness of the boss while preforming the tip of the boss portion of the material from the inner diameter portion to the outer diameter portion or from the outer diameter portion to the inner diameter portion in a tapered shape by the upper die. Was.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the left half shows a blank 1 and the right half shows a state in which the blank is formed by cold forging.

In the right half of FIG. 1, a lower die fixed to a bolster of a press machine is constituted by a lower die 3, a cored bar 4, and the like. The upper die fixed to the slide of the press machine is composed of a punch 6, an upper die 5, etc., and the punch 6 is urged downward by a punch pin 7 and the upper die 5 by an upper die pin 8, respectively. Have been.

The upper die die pin 8 is urged by an upper die gas pressure cylinder 24 via an upper die piston 26 as shown in the embodiment of FIG. By adjusting the upper die gas pressure cylinder 24, the force for urging the upper die 23 can be adjusted. That is, the upper die pin 8 is
It is urged by another means different from the punch 21.
The upper die spring 25 urges the upper die pin 8 toward the upper die 23 so that the upper die piston 26 and the upper die pin 8 are not separated. On the other hand, the biasing force of the punch 6 can also be independently adjusted using, for example, hydraulic pressure.

A punch 6 is provided on the outer periphery of the cored bar 4, and an upper die 5 is provided on the outer periphery of the punch 6. Punch 6
And the upper die 5 are relatively movable in the vertical direction.

As described above, the metal core 4 shown on the right side of FIG. 1 is inserted into the hole of the material 1 shown on the left side of FIG. And when the press machine slide is processed,
The punch 6 and the upper die 5 are lowered, and the material is subjected to cold forging by the cooperation of the lower die 3, the punch 6, the metal core 4, and the upper die 5, and the material 1 becomes the product 2.

Therefore, if the volume of the boss portion is larger than the set volume at the time of forming the boss, the punch 6 cannot press the upper end surface of the boss any more when the punch 6 is closed, so that the boss height is higher than the set value. When the volume of the boss is lower than the setting, the punch 6 pushes the upper end face of the boss more than the setting, and sets the urging force of the punch 6 so that the boss height becomes lower than the setting. On the other hand, at the time of boss molding, the volume of the boss portion is set to the smallest amount, and when the volume is larger than the setting, an extra volume flows out to the flange portion near the corner of the outer periphery of the boss and pushes the upper die 5 upward, The urging force of the upper die 5 can be set so that the boss height becomes constant.

FIG. 2 is similar to FIG. That is, the mold structure of FIG. 2 is very similar to the mold structure of FIG. The difference is that there is no protrusion on the upper die 15 or the lower die 13,
The two points are that the lower die 13 has a concave portion that restricts the outer peripheral portion of the material.

The protrusion is provided to prevent the material from flowing to the flange portion, and is provided when the material does not interfere with the product and the strength and rigidity of the product do not matter. The protrusion is the protrusion 2 shown in FIG.
The tip may have a pointed shape like 8, 29, or may have a flat tip like the projection 30 shown in FIG.
It is desirable that these projections be provided as close to the center as possible from the viewpoint of increasing the thickness of the boss by molding.

On the other hand, the material can be prevented from flowing to the flange portion by the action of the concave portion. Therefore, the action of the projections and recesses not only facilitates the thickening of the boss,
Another object is to reduce the amount of material flowing from the boss to the flange as much as possible to reduce the variation in the volume of the boss.

Since the punch 16 and the upper die 15 are separately urged by the pin 17 for the punch and the pin 18 for the upper die, the punch 16 and the upper die 15 can move relative to each other in the vertical direction. This relationship is the same as the relationship between the punch 6 and the upper die 5 in FIG.

FIG. 7 shows a state in which the boss of the material 19 buckles. This condition occurs when a thick boss is to be press-formed from a relatively thin plate material. When the tip of the boss portion of the material 19 is pressed by the punch 6, the boss portion may bend between the cored bar 4 and the upper die 5 and buckle.
This is mainly related to the length of the boss portion, the distance between the outer diameter of the cored bar 4 and the inner diameter of the upper die 5, the thickness and material of the material, and the like.

As shown in FIG. 4, it was found that the above-mentioned buckling did not occur when the thickness of the boss was increased while the tip of the boss portion of the material 19 and the tip of the punch 21 were tapered. This taper
It is tapered from the inner diameter to the outer diameter or from the outer diameter to the inner diameter. When sink marks K3 and material overlap K4 occur at the inner diameter of the boss portion as shown in FIG. 10A, the former is tapered as shown in FIG. The outer diameter of the gold 4 is set to be substantially the same as that of the gold 4. When the material overlaps K5 at the outer diameter of the boss as shown in FIG. 11 (A), the latter is tapered as shown in FIG. 11 (B). Further, it is more effective to set the outer diameter of the boss of the material 19 to be substantially the same as the inner diameter of the upper die 23 and increase the thickness of the boss at the same time.

As shown in FIG. 6, this taper can be formed by increasing the thickness of the boss while preforming the tip of the boss portion of the raw material 19 with the upper die 27, and thereafter, using the punch 6 or the like.

FIG. 8 shows how the variation in the volume of the boss portion of the material 19 is absorbed by adjusting the urging force of the punch 6 so as not to overload the mold. FIG. 8A shows a case where the volume of the boss portion is small, and the boss height of the product 2 is low. On the other hand, FIG. 2B shows that the boss height of the product 2 is high when the volume of the boss portion is large.

FIG. 9 shows how the variation in the volume of the boss portion of the material 19 is absorbed by adjusting the urging force of the upper die 5 so as not to overload the mold. FIG. 9A shows a case where the volume of the boss is the smallest. FIG. 5B shows a case where the volume is larger than that of FIG. 5A. The flange portion near the outer peripheral corner of the boss rises by the volume, and the upper die 5 is pushed upward. At this time, the boss heights of the products 2 are all the same. The bulge is a step and is smoothly connected to the upper surface of the flange, and does not cause a defect in product function.

[0032]

According to the present invention, the punch for urging the upper end surface of the boss portion of the material and the upper die for urging the flange portion of the material are relatively movable in the vertical direction, so that the corner portion on the outer periphery of the boss of the product is provided. No overlapping of materials occurs. In addition, the upper die is used to urge the flange of the product, and the upper and lower dies are provided with protrusions, or the outer periphery of the flange is restrained by the recess provided in the lower die. The amount of material flowing into the boss is reduced, so that the boss can be formed in a favorable state, and the boss portion has less volume variation. On the other hand, if a taper is provided at the tip of the punch, and the inner diameter or outer diameter of the boss is made substantially the same as the outer diameter of the cored bar or the inner diameter of the upper die in accordance with the tapered shape, the boss is increased in thickness to form a material. But it is less likely to buckle. By this effect, the occurrence of sink marks and overlap in the inner and outer diameters of the boss of the product is reduced, and the boss having a large thickness can be press-formed from a material having a relatively small thickness, so that the weight of the product can be reduced. In addition, the punch and the upper die are provided with independent biasing means, and the biasing force can be adjusted individually, so that even if the volume of the boss portion varies, the mold does not overload. In this way, the life of the mold can be extended. In addition, the accuracy of the inner and outer diameters of the product boss is improved, and an inexpensive material having a large allowable thickness tolerance can be used as a plate material.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a mold part.

FIG. 2 is a longitudinal sectional view of a mold part according to another embodiment.

FIG. 3 is an explanatory view of processing in a conventional example.

FIG. 4 is a longitudinal sectional view of a mold part according to another embodiment.

FIG. 5 is an explanatory view of a shape of a projection.

FIG. 6 is a longitudinal sectional view of a mold part according to another embodiment.

FIG. 7 is an explanatory view of buckling.

FIG. 8 is a vertical cross-sectional view of a mold part that absorbs variations in boss volume with a punch.

FIG. 9 is a longitudinal sectional view of a mold part for absorbing variations in the volume of a boss with an upper die.

FIG. 10 is a longitudinal sectional view of a defect of a boss inner diameter and a mold part for preventing the defect.

FIG. 11 is a longitudinal sectional view of a defect of a boss outer diameter and a mold part for preventing the defect.

[Explanation of symbols]

1 is a material, 2 is a product, 3 is a lower die, 4 is a core bar, 5 is an upper die, 6 is a punch, 7 is a punch pin, 8 is an upper die pin, 12 is a product, 13 is a lower die, 14 Is a metal core, 15 is an upper die, 16 is a punch, 17 is a punch pin, 18 is an upper die pin, 19 is a material, 20 is a product, 21 is a punch, 2
2 is a lower die, 23 is an upper die, 24 is an upper die gas pressure cylinder, 25 is an upper die spring, 26 is an upper die piston, 27 is an upper die, 28 is a projection, 29 is a projection, 30 is a projection, 32 is a taper punch, 33 is a taper punch, 34
Is overloaded.

Claims (10)

[Claims] 1. A method for obtaining a product having a boss portion on a flange by cold forging, comprising: a punch for biasing an upper end surface of a boss portion of a material; and an upper die for biasing a flange portion of the material.
A lower die facing the upper die, a core bar provided in a lower die, the punch disposed on an outer peripheral portion of the core bar, the upper die disposed on an outer peripheral portion of the punch, The upper die and the upper die have a structure capable of moving relative to each other in the vertical direction, and a mold provided with a means for preventing the material of the material from flowing to the flange portion, and a means for urging the upper die, The means for urging the punches are independent of each other, and the urging force can be independently determined.The core is inserted into the hole of the material, and the material is formed by the punch and the die to obtain a product. Characteristic method of increasing the thickness. 2. The method according to claim 1, wherein the means for preventing the material from flowing to the flange portion is a projection provided on the upper die or the lower die. 3. The plate thickness according to claim 1, wherein the means for preventing the material of the material from flowing to the flange portion is a concave portion provided on the lower die for restraining an outer peripheral portion of the material. How to increase. 4. An apparatus for obtaining a product having a boss portion on a flange by cold forging, comprising: a punch for urging the upper end surface of the boss portion of the material; and an upper die for urging the flange portion of the material.
A lower die facing the upper die, a core bar provided in a lower die, the punch disposed on an outer peripheral portion of the core bar, the upper die disposed on an outer peripheral portion of the punch, And the upper die have a structure capable of moving relative to each other in the vertical direction, and a means for preventing the material of the material from flowing to the flange portion is provided, and the means for urging the upper die and the punch are urged. The thickness increasing device is characterized in that the means are independent and the biasing force can be determined independently. 5. The apparatus according to claim 4, wherein the means for preventing the material of the raw material from flowing to the flange portion is a projection provided on the upper die or the lower die. 6. The plate thickness according to claim 4, wherein said means for preventing the material of the material from flowing to the flange portion is a concave portion provided on the lower die for restraining an outer peripheral portion of the material. Increase device. 7. A method for obtaining a product having a boss portion on a flange by cold forging, comprising: a punch for biasing an upper end surface of a boss portion of a material; and an upper die for biasing a flange portion of the material.
A lower die facing the upper die, a core bar provided in a lower die, the punch disposed on an outer peripheral portion of the core bar, the upper die disposed on an outer peripheral portion of the punch, The upper die and the upper die have a structure capable of moving relative to each other in the vertical direction, and a mold provided with a means for preventing the material of the material from flowing to the flange portion, and a means for urging the upper die, The means for urging the punches are independent of each other, and the urging force can be independently determined.The core metal is inserted into the hole of the material, and the shape of the tip of the punch is tapered from the inner diameter to the outer diameter. And the inner diameter of the boss of the material is substantially the same as the outer diameter of the core metal, or is tapered from the outer diameter to the inner diameter, and the outer diameter of the boss of the material is substantially the same as the inner diameter of the upper die. Material is formed by the punch and the die It was characterized by obtaining a product
Plate thickness increase method. 8. An apparatus for obtaining a product having a boss portion on a flange by cold forging, comprising: a punch for urging the upper end surface of the boss portion of the material; and an upper die for urging the flange portion of the material.
A lower die facing the upper die, a core bar provided in a lower die, the punch disposed on an outer peripheral portion of the core bar, the upper die disposed on an outer peripheral portion of the punch, And the upper die have a structure capable of moving relative to each other in the vertical direction, and a means for preventing the material of the material from flowing to the flange portion is provided, and the means for urging the upper die and the punch are urged. The means are independent of each other, and the biasing force can be independently determined.The shape of the tip of the punch is tapered from the inner diameter to the outer diameter, and the inner diameter of the boss of the material is the same as the outer diameter of the cored bar. A plate thickness increasing device, wherein the thickness is substantially the same, or the outer diameter portion is tapered from the inner diameter portion to the inner diameter portion, and the outer diameter of the boss of the material is substantially equal to the inner diameter of the upper die. 9. The boss is thickened while the tip of the boss portion of the material is preformed in a tapered shape from an inner diameter portion to an outer diameter portion or from an outer diameter portion to an inner diameter portion by an upper die. 2. The method according to claim 1, wherein the thickness is increased. 10. The boss is thickened while the tip of the boss portion of the material is preformed in a tapered shape from an inner diameter portion to an outer diameter portion or from an outer diameter portion to an inner diameter portion by an upper die. The thickness increasing device according to claim 4, wherein the thickness is increased.