JP2020006377A - Forging method - Google Patents

Abstract

To provide a forging method capable of lengthening a die life by inhibiting an unreasonable material flow.SOLUTION: A forging method of the present invention includes a back pressure application step (S1), forward movement steps (S2-S5), and back pressure control steps (S3 and S4). In the back pressure application step, back pressure is applied to a material by a counter punch. In the forward movement steps, the punch is moved forward to a material side. In the back pressure control steps, a control part controls the back pressure of the counter punch on the basis of whether or not a position of the material in a position of the punch is proper, in the forward movement steps.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a forging method in which a forged material is plastically flowed and extruded into a predetermined shape.

  2. Description of the Related Art A forging method is known in which a forged material such as a mechanical component having a predetermined shape is formed by plastically flowing a forged material and extruding the material by utilizing the plasticity of the material. For example, in Patent Document 1, in a forging process of a forging machine including a punch, a die, and a forming pin, the forming pin is stopped when the punch moves forward, and the punch moves backward when the punch moves backward. It is described that the operation is performed in the backward direction of the punch at a speed higher than the speed. This eliminates the underfill that has occurred in the work during the forward movement of the punch.

Japanese Patent No. 6245674

  By the way, in the forging method described in Patent Document 1 and the generally known forging method, since the temperature of the mold and the hardness of the material are not taken into consideration, for example, at the start of production and during the stable production period, the material in the mold is not used. There is a difference in flow conditions. For example, the frictional state generated between the mold and the material due to the temperature change of the mold may change, and the material flow may become non-uniform. Therefore, a local pressure increase occurs, and the molding load increases due to the pressure increase. As a result, there has been a problem that the mold life is deteriorated. In addition, a low-hardness material has a lower deformation resistance than a high-hardness material, so that the load decreases. For this reason, the amount of elastic deformation of the material changes, and there is also a problem that the product accuracy varies depending on the material.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a forging method capable of improving a mold life by suppressing an excessive material flow.

  In the forging method of the present invention, a die (11) on which a forging material (W) is placed, a punch (12) reciprocating with respect to the die, and a counter for applying a back pressure from one end surface of the forging material when the punch moves forward. A forging device (100) having a punch (14) and a control unit (17) for controlling the back pressure by the counter punch causes the forging material to plastically flow and extrude it into a predetermined shape.

  The forging method includes a back pressure applying step, a forward movement step, and a back pressure control step. In the back pressure applying step, a back pressure is applied to the forged material by a counter punch. In the forward movement step, the punch moves forward to the forging material side. In the back pressure control step, at the time of the forward movement step, the control unit controls the back pressure of the counter punch based on whether or not the position of the forging material at the position of the punch is appropriate.

  According to the configuration of the present invention, when the punch moves forward, the position of the forging material at the position of the punch is detected, and based on whether or not the detected position of the forging material is appropriate, the back of the counter punch is determined. Pressure control is performed. By looking at the position of the forged material, for example, in the case of front-rear extrusion, it can be determined whether or not the forging material is appropriately extended forward and backward. By controlling the back pressure according to such elongation, it is possible to suppress a local pressure rise due to an unreasonable material flow. In addition, it is possible to suppress such a rise in the pressure and a deterioration in the mold life caused by an increase in the molding load due to the increase in the pressure, and it is possible to improve the mold life.

It is a front sectional view of the forging device which performs the forging method of a 1st embodiment of the present invention, and is a figure showing the state at the time of processing start. 5 is a flowchart illustrating control executed by a control unit in the forging method according to the first embodiment. It is a front sectional view of a forging device, and is a figure showing the state of the middle stage of processing in which material flow is proper. It is a front sectional view of a forging device, and is a figure showing a state in the middle stage of processing in which material flow is inappropriate, (a) is a figure showing a state where material flow is promoted backward, and (b) is forward. FIG. 4 is a diagram showing a state in which the material flow is promoted. It is a flowchart which shows the control which a control part performs in the forging method of 2nd Embodiment. It is a front sectional view of a forging device, and is a figure showing the state in the middle stage of processing with improper load, (a) is a figure showing a state where load is small, and (b) is a figure showing a state where load is large.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
<First embodiment>
[Constitution]
A forging method according to a first embodiment of the present invention will be described with reference to FIGS. First, the configuration of a forging device that performs the forging method will be described with reference to FIG. As shown in FIG. 1, the forging apparatus 100 mainly includes a die 11, a punch 12, a punch sleeve 13, a counter punch 14, a hydraulic cylinder 15, a drive circuit unit 16, a control unit 17, and the like. Note that the forward movement direction of the punch 12 is defined as forward, and the backward movement direction is defined as backward. In FIGS. 1, 3, 4, and 6, the lower part of the drawing is the front and the upper part is the rear. The reciprocating direction of the punch 12 coincides with the axial direction of the apparatus.

  A large-diameter hole 21 and a small-diameter hole 22 are formed in the die 11. The large-diameter hole 21 and the small-diameter hole 22 are arranged coaxially, and have a circular cross section in the axial direction. A flat mounting surface 23 on which the material W is mounted is formed at a step between the large-diameter hole 21 and the small-diameter hole 22. The punch sleeve 13 is a cylindrical member, and is slidably provided in the large-diameter hole of the die 11. The punch sleeve 13 operates in conjunction with the operation of the counter punch 14 so as to allow a plastic flow of the material W during the forward working by the punch 12. Here, “linked” means that it moves with the operation of the counter punch 14. The punch sleeve 13 corresponds to an example of an “interlocking member”.

  The punch 12 is a cylindrical member, and is slidably provided in the punch sleeve 13. Further, the punch 12 is connected to a hydraulic cylinder, a drive circuit unit, and a control unit (not shown), and the lowering speed and stroke of the punch 12 are controlled by the control unit (which can also be used as the control unit 17). ing.

  The counter punch 14 is slidably provided in the small-diameter hole of the die 11. The counter punch 14 is connected to a cylinder rod 24 of the hydraulic cylinder 15. The hydraulic cylinder 15 is connected to a drive circuit unit 16, and its pressure is controlled by the control unit 17 via the drive circuit unit 16. Therefore, the counter punch 14 can apply a predetermined back pressure Fr to the material W.

[Action / Effect]
Next, a forging method using the forging device 100 will be described. In the present embodiment, the columnar material W is formed by compound extrusion combining forward extrusion and backward extrusion. As shown in FIG. 3, the formed product has a shaft portion 25, an annular flange portion 26, and a circular convex portion 27. The annular flange 26 is located on the rear end side of the shaft 25 in the axial direction. The circular convex portion 27 is located at the center of the front end side of the shaft portion 25. Note that, in FIG. 3 and FIGS. 4 and 6 to be referred to below, illustration of the hydraulic cylinder 15, the drive circuit unit 16, and the control unit 17 is omitted for simplification.

  First, the material W is set on the mounting surface 23 with the mold opened. At the start of processing, as shown in FIG. 1, the lower end surface of the material W is in contact with the mounting surface 23 and the upper surface of the counter punch 14. Further, the upper end surface of the material W is in contact with the punch sleeve 13. That is, the material W is filled in the mold. As shown in the flowchart of FIG. 2, when the processing is started, first, in step (hereinafter, step is abbreviated as “S”) 1, the back pressure Fr is applied from the rear end face of the material W by the counter punch 14. This S1 corresponds to a “back pressure applying step”.

  Next, in S2, the lowering of the punch 12 is started. The punch 12 presses the front end surface of the material W. As the stroke of the punch 12 increases, the pressing load F gradually increases from zero to a predetermined value. Since this predetermined value is larger than the back pressure Fr of the counter punch 14, the material W and the counter punch 14 descend when the pressing load F becomes larger than the back pressure Fr. The punch sleeve 13 descends in conjunction with the operation of the counter punch 14. In this process, as shown in FIG. 3, a shaft portion 25 thinner than the original thickness of the material W, an annular flange portion 26 extending backward, and a circular convex portion 27 extending forward are gradually formed. Then, it is formed into the shape of the product.

  FIG. 2 is referred to again. Next, in S3, it is determined whether the material position (front position Mf or rear position Mr (see FIG. 3) at the position of the punch 12 is appropriate. The front position Mf and the rear position Mr, which are the front end positions of the material W that has been plastically flowed and extended forward and backward, can be detected from the position of the counter punch 14, for example. Since the volume of the material W is constant, the front position Mf and the rear position Mr of the material W can be obtained from the descending amount of the counter punch 14 or the forward position after descending. Note that the rear position may be obtained from the position P of the interlocking punch sleeve 13.

  Also, in the process of forging, appropriate material positions Mf and Mr at the position of the punch 12 when a predetermined product is formed are determined. The control unit 17 stores in advance master data indicating the correspondence between the position P of the punch 12 and the appropriate material position Mf, Mr. By comparing the master data with the detected material position, for example, by checking whether the difference between the master value and the detected value is within a predetermined value, it is determined whether the material positions Mf and Mr are appropriate. Can be determined.

  If the material positions Mf and Mr are appropriate (S3: YES), the process proceeds to S5, where it is determined whether the punch 12 has descended to the bottom dead center. When the punch 12 has not descended to the bottom dead center (S5: NO), the processes of S2 to S5 are repeatedly executed until the punch 12 descends to the bottom dead center, that is, until YES is determined in S5. Is done. The processing from S2 to S5: YES corresponds to a “forward movement step” in which the punch 12 moves forward.

  When the material positions Mf and Mr are appropriate, as shown by arrows A1 and A2 in FIG. 3, the material flows forward and backward are uniform, and a local pressure rise occurs in the mold. The load on the mold is low and stable.

  On the other hand, if the material positions Mf and Mr are not proper in S3 (S3: NO), the back pressure control of the counter punch 14 is performed in S4. Hereinafter, specific back pressure control will be described. As an example of the case where the material positions Mf and Mr are not appropriate, that is, the balance of the material flows is poor, as shown by arrows A3 and A4 in FIG. The back pressure Fr is reduced to promote the forward flow of the material. On the other hand, as shown by arrows A5 and A6 in FIG. 4B, when the forward material flow is promoted, the back pressure Fr is increased to promote the backward material flow.

  After the back pressure control, the process returns to S3, and the back pressure control is executed until the material positions Mf and Mr become appropriate. The processing of S3 and S4 corresponds to a “back pressure control step”. Whether the material flow is promoted forward or backward can be determined from the respective detected values of the front position Mf and the rear position Mr of the material W at the position P of the punch 12.

  Then, in S5, when it is determined that the punch 12 has descended to the bottom dead center, the forming process is completed, and thus the present process is ended. Thereafter, the mold is opened and the product is taken out.

[effect]
For example, in the method in which the processing is performed while the back pressure of the counter punch 14 is constant, the temperature state of the mold differs between the start of production and the production stabilization period. There is a possibility that the frictional force generated therebetween changes and the material flow becomes uneven. In that regard, in the first embodiment, the positions Mf and Mr of the elongated material W at the position P of the punch 12 are detected, and the position of the counter punch 14 is determined based on whether the detected positions Mf and Mr are appropriate. Pressure control is being performed. Appropriate back pressure control is performed according to the elongation of the material W, and the material flow is always kept uniform.

  For this reason, it is possible to suppress the occurrence of a local pressure increase due to an unreasonable material flow, and to suppress an increase in the molding load F due to such an increase in the pressure, thereby improving the life of the mold.

<Second embodiment>
Next, a forging method according to a second embodiment of the present invention will be described with reference to FIGS. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In the second embodiment, the forging is performed using the same forging device 100 as in the first embodiment.

  As shown in FIG. 5, when the lowering of the punch 12 is started in S2, it is determined in S31 whether the material positions Mf and Mr and the load F at the position P of the punch 12 are appropriate. That is, it is different from the above-described first embodiment in that it determines whether or not the load F at the position of the punch 12 is appropriate in addition to the material positions Mf and Mr. If either the material position or the load F is not appropriate, the back pressure control is executed in S4. Note that other steps are the same as those in the first embodiment, and a description thereof will not be repeated.

  The load F applied to the material W changes according to the difference in the deformation resistance of the material W and the descending position (stroke). In the second embodiment, the load F is constantly sensed. In the forging process, an appropriate load F at the position P of the punch 12 is determined. In the second embodiment, the master data on the load F is controlled in addition to the material positions Mf and Mr at the position P of the punch 12. It is stored in the unit 17 in advance. The determination as to whether the data is appropriate is made by comparison with the master data.

  As an example of the improper load F, as shown in FIG. 6A, when the load F is too small, the back pressure Fr is increased to increase the amount of elastic deformation. In FIG. 6, arrows A7 and A8 show images of the amount of elastic deformation. As shown in FIG. 6B, when the load F is too large, the back pressure Fr is lowered to reduce the amount of elastic deformation. In the second embodiment, the processing of S31 and S4 corresponds to a “back pressure control step”.

  The second embodiment has the same effects as the first embodiment, and also has the following effects. The load F of the low hardness material is lower than that of the high hardness material. When a material having a difference in hardness is generated due to heat treatment conditions or the like, if the load F applied to the material W is not taken into consideration, the amount of elastic deformation may change due to the load fluctuation, and the product accuracy may be reduced. In this regard, in the second embodiment, the elastic deformation amount is made constant by considering the load F, and the dimensional accuracy of the product can be improved.

<Other embodiments>
In the forging apparatus 100 of each of the above embodiments, the counter punch 14 is driven by the hydraulic cylinder 15, but may be configured with a servomotor or may be variously modified.

  In each of the above embodiments, the appropriateness of the positions Mf and Mr of the material W is determined by comparing with the master data. However, if the product shape is simple, for example, the appropriateness is determined by simply comparing the forward extension and the backward extension. It may be executed or another method may be used.

  In each of the above embodiments, an example in which molding is performed by front-rear composite extrusion has been described. However, front extrusion, rear extrusion, and side extrusion may also be used. At that time, the shape of the mold, the position of the counter punch 14, and the like are appropriately changed.

  In the above embodiments, the cylindrical material W is processed, but the material before processing and the shape after molding are not limited to the above. For example, a material in which a flange portion is provided on a material before processing may be employed, and various forms are possible.

  The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 11 ... Die 12 ... Punch 13 ... Punch sleeve 14 ... Counter punch 17 ... Control part 100 ... Forging apparatus W ... Forging material

Claims (5)

A die (11) for placing the forging material (W), a punch (12) reciprocating with respect to the die, and a counter punch (14) for applying a back pressure from one end surface of the forging material when the punch moves forward. A forging device (100) having a control unit (17) for controlling back pressure by the counter punch, wherein the forging material is plastically flowed and extruded into a predetermined shape by extrusion.
A back pressure applying step in which a back pressure is applied by the counter punch to the forged material;
A reciprocating step in which the punch reciprocates toward the forging material side,
During the forward movement step, based on whether the position of the forged material at the position of the punch is appropriate, the control unit controls the back pressure of the counter punch,
Including forging methods.   The forging method according to claim 1, wherein in the back pressure control step, a position of the forging material is detected from a position of the counter punch.   The said back pressure control process WHEREIN: The said control part controls the back pressure of the said counter punch based on whether the load applied to the said forging material in the position of the said punch is proper. The forging method described. The forging device further includes an interlocking member (13) interlocked with the counter punch so as to allow plastic flow of the forging material,
4. The forging method according to claim 1, wherein the forging material is brought into contact with the interlocking member and the counter punch so as to fill the inside of the mold at the start of processing. 5. A forging method for performing compound extrusion combining forward extrusion and backward extrusion,
In the back pressure applying step, a back pressure is applied from the rear end surface of the forged material by the counter punch,
The forging method according to any one of claims 1 to 4, wherein in the forward movement step, the punch presses a front end surface of the forging material to push the forging material forward and backward.

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