JP2002361355A - Forging method and forging punch for cut material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forging punch capable of preventing the development of cracking due to the ductility limit of a material even in the working large in fractional reduction in upsetting height. SOLUTION: The forging punch is provided with a flat face A orthogonal to the direction of a punch axis L on the outer periphery side, and a tilting face B having a projecting inclination toward the center of the punch succeeding the flat face to constitute a tip part, wherein the angle formed by the tilting face and the flat face is made to be 30 deg. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forging a cut material and a punch for forging, and more particularly, to forging during upsetting performed in a preforming stage when a product is forged from a cut material. The present invention relates to a method and a forging punch used in the forging method.

[0002]

2. Description of the Related Art In the case of multi-stage forging of a material having low ductility, a material cut to a required weight is often upset for the purpose of preforming. In this upsetting process, as shown in FIG. 9A, the punch 1 having a shape of a flat surface 1A whose front end is orthogonal to the punch axis direction, and the unevenness of the cut surface of the material after the upsetting process are not left. A punch 2 having a shape having an inclined surface 2A protruding from the outer periphery of the punch toward the center of the punch as shown in FIG. 2B is used, and a mold shown in FIG. 10 is used. An upsetting process such as 11 was performed.

[0003] The configuration of the mold shown in FIG. 10 includes a fixed die 3, a knockout pin 4 slidably assembled inside the die 3, and the die 3 periodically inserted into the die 3. Punch 1 or 2. Prior to the start of processing, the punch 1 or 2 is at a position retracted from the state shown in FIG. 10, and the knockout pin 4 kicks out the work inside the die. It is in a protruding position.

The cutting material 5 shown in FIG. 11A is transported by a transfer mechanism (not shown), and stops at the entrance of the die processing section. Then, punch 1 or 2
Moves forward in the direction of the die 3 and pushes the cut material 5 into the die 3 to start processing. At this time, the knockout pin 4 is pushed together with the cutting material 5 by a punch, and stops at a position adjusted in advance.

[0005] The punch 1 or 2 inserted into the die 3 is further advanced, and when the punch 1 or 2 reaches the adjusted position, the preforming of the cutting material 5 is completed, and the work 6 after the upsetting shown in FIG. Is obtained. Thereafter, when the punch 1 or 2 retreats and has a certain distance from the die 3 and the transfer, the transfer returns to the original position, and before the processing portion of the die 3, the transfer to the next processing step is performed. The transfer mechanism is waiting.

After that, the knockout pin 4 starts to move to kick out the work 6 after the upsetting in the die 3, and the work 6 after the upsetting is held by the transfer mechanism and transported to the next processing step. Then, the mold returns to the state before the start of processing. By repeating these series of cycles, processing is performed continuously.

FIG. 12 shows a deformed state of the cutting material 5 into the work 6 after the upsetting in the upsetting process. FIG. 12 shows an example in which the punch 1 shown in FIG. 9A has a flat surface 1A as shown in FIG. 9A, and is used as shown in FIGS. 9A to 9E. To
The friction at the contact portion between the punch 1 and the cutting material 5 is small, and the end surface 5a of the cutting material 5 on the punch 1 side is widened.

[0008]

In the case of the upsetting process according to the prior art, as shown in the deformed state of FIG. 12, as the diameter of the punch-side end face 5a of the cutting material 5 increases, the cutting material 5 A circumferential tensile stress is generated inside. As a result, if the material itself has low ductility, or if there is a defect such as a fine crack on the punch-side end face, a crack is likely to occur at the punch-side end face corner 6a of the work 6 after the upsetting.

In order to prevent such a crack at the corner of the end face on the punch side, the ratio of the difference between the length of the raw material before processing and the length of the work after processing to the raw material length before processing (hereinafter referred to as the upsetting ratio). ) Could not be adopted. Therefore, the ratio of the length L to the diameter D in the cut material (L / D)
Has to be reduced to a range where no adverse effects occur, and the work dimensions after the upsetting must be approached.

Also, when cutting a material to a required weight by shearing, it is well known that if the ratio of the length L to the diameter D (L / D) of the cut material is small, the cut shape is distorted and the shape tends to be distorted. Because of this, troubles such as dropping during transfer were likely to occur.

Furthermore, in the prior art, the work 6
Is, as described above, the punch-side end face 5 of the cut material 5.
Since a is in a spread state, if there is a defect such as a flaw in the sheared surface on the end face of the material, this flaw etc. remains on the product as it is, and further processing is required after forging to remove the defect on the end face of the product There was also a problem that it was costly.

Further, since the work 6 after the upsetting is in the processing state as described above, its internal fiber flow is, as schematically shown in FIG. 11B, outside the work 6 near the punch-side end face. Nearly parallel to the radial surface. Then, for example, when forging as shown in (c) and (d) of FIG. 13 is performed to the end and the product 7 is formed, as shown in (e) of FIG. Has a problem that the fiber flow remains almost parallel to the outer diameter surface and is inferior in strength to stress in a direction perpendicular to the forging direction.

The present invention has been made to solve the above-mentioned problems which cannot be overcome by the prior art.
By actively restraining the corners on the punch side where cracks are likely to occur during upsetting, it is possible to prevent edge cracking due to the ductility limit of the material even in machining with a large upsetting ratio, It is an object of the present invention to provide a forging method for a cutting material and a forging punch used in the forging method, which can improve the quality of the forging and further reduce the cost required for post-processing after forging.

[0014]

In order to achieve the above-mentioned object, a method for forging a cut material according to the present invention is a method of swaging a cut material with a forging punch. The diameter of the punch-side end face is restricted by restraining the outer face, and the outer diameter face is swept up to the end face side.

By adopting this forging method, the end face of the cut material is hardly increased in diameter, and the upsetting process is performed in a state where the outer peripheral face having no defect goes around the end face side. Therefore, even in machining with a large upsetting ratio, it is possible to prevent the occurrence of cracks on the outer peripheral surface of the punch side end surface due to the limit of ductility of the material, and to improve the end surface quality of the product after forging, and also to improve the internal fiber Since the flow has a substantially concentric arc shape centered on the inside of the product, a product having high strength against stress in a direction perpendicular to the forging direction can be obtained.

The forging punch used in the above-described forging method has a plane on the outer peripheral side perpendicular to the direction of the punch axis, and has a convex slope from the plane to the center of the punch. The tip portion is constituted by an inclined surface, and the angle between the inclined surface and the plane is 30 ° or less.

By performing upsetting using the forging punch, the corner of the end face of the cut material is fixed at the connection between the inclined surface and the flat surface as the punch advances, and the outer diameter surface is changed to the end face side. And is processed so as to come into contact with the punch. Thereby, a defect such as a crack does not occur on the outer peripheral portion of the punch-side end surface of the work after the upsetting. Further, since the processing can be completed without enlarging the cut surface of the cut material, the post-process after forging can be omitted without leaving a defect of the cut surface in the product.

Further, in another forging punch according to the present invention, in addition to the configuration of the forging punch of the present invention, the forging punch has a convex inclination toward the center of the punch and the plane perpendicular to the punch axis direction. + 10 ° to -10 between the held inclined surface
An intermediate inclined surface having an angle of ° was formed.

By performing the upsetting process using the forging punch, when the end face corner of the material is fixed at the connection between the inclined surface and the intermediate inclined surface, the intermediate inclined surface is fixed. When the angle is on the negative surface, the movement of the end face corner of the material is restricted at the point where the intermediate inclined plane intersects with the inclined face (connecting portion), and the end face corner is more securely fixed.

Further, when the angle of the intermediate inclined surface is a plus surface, the stress applied to the point (connection portion) where the inclined surface and the intermediate inclined surface intersect is alleviated, and the life of the punch is improved. In any of the forging punches described above, the vicinity of the center of the tip of the punch can be formed into an arbitrary shape in accordance with the forged product to be formed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a forging punch according to the present invention will be described in detail with reference to the embodiments shown in FIGS. 1 to 4. According to the present invention, a material cut to a required weight (hereinafter referred to as a cut material) will be described. ) Is characterized by the structure of the tip of the forging punch used when upsetting is performed. That is, as shown in FIG. 1, the tip structure of the forging punch according to the present invention has a vertical plane A perpendicular to the punch axis L formed on the outer peripheral side and a convex shape toward the center of the punch. And the angle between the inclined plane B and the vertical plane A is 30 °.

[0022] Then, the forging punch P ₁ cutting material according to the first embodiment of the present invention, as shown in FIG. 2, perpendicular plane A perpendicular to the punch axis L formed on the outer peripheral side
And a plane B perpendicular to the axis L of the punch, followed by an inclined plane B having a convex slope toward the center of the punch. The angle between the inclined plane B and the vertical plane A is 30 °.

Further, in the forging punch in accordance with a second embodiment of the present invention as shown in FIG. 3, the punch P ₂ is perpendicular plane A perpendicular to the punch axis L formed on the outer peripheral side
And three planes A, B, and C: an intermediate inclined plane C having an angle of plus 10 ° from the vertical plane A, and an inclined plane B having a convex inclination toward the center of the punch. And the angle between the inclined surface B and the vertical plane A is 30 °.

[0024] and further, as shown in FIG. 4 is a forging punch in accordance with a third embodiment of the present invention, the punch P ₃
Replaces the intermediate inclined surface C of the punch P2 according to the _second embodiment with a minus 1
0 ° is obtained by an intermediate inclined plane D having the angle of the other configuration is the same as the punch P ₂ according to the second embodiment.

Next, the upsetting as shown in FIG. 6 using the punch P according to the present invention and the mold shown in FIG. 5 will be described with reference to FIG. 7 which schematically shows the process of deforming the work. I do. The die has the configuration shown in FIG.
A and the knockout pin 4A incorporated so as to slide inside the die are the same as those in the prior art shown in FIG. Further, punch using a punch P ₁ of the first embodiment shown in FIG. 2 described above, the processing cycle is processed in the prior art and similar cycles.

Further, in use the forging apparatus horizontal multistage heading machine (former), one mold material is that die 3A is fitted double baked carbide nib SKD6 case, knock-out pins 4A and the punch P ₁ is In both cases, SKH51 is applied. As a work material (work), a coil obtained by supplying a coil obtained by treating a surface of a spheroidized annealed high carbon chromium bearing steel with a zinc phosphate film to a forging machine and continuously shearing the inside of the forging machine was used.

By upsetting the cut blank W shown in FIG. 6A with such a mold configuration, the work F after the upsetting has the shape shown in FIG. The state becomes characteristic. To explain this deformation state with reference to FIG. 7, the cut material W inserted into the die 3A and immediately before the deformation starts is in the state of FIG.

[0028] Then, when the punch P ₁ from the state shown in FIG. 7 (a) advances, a state of FIG. (B), as sequentially punch is advanced, the cutting material W is drawing (c),
(D), (e), and (f), respectively. In addition,
FIG (f) is in a state of advancement of the punch P ₁ is completed stopped (before top dead center), and ends the deformation of upsetting and cutting material W, a condition that the workpiece F after inclusive据.

[0029] In FIG. 7 (b), the inclined surface B of the tip of the punch _{P 1} is a state in which bite into the end surface Wa of the cutting material W.
At this time, the diameter of the cut material W is slightly enlarged, but the length is hardly deformed. Therefore, the diameter d of the inclined surface B of the punch P ₁ according to the present invention is larger than the diameter of the cutting material W.

[0030] Next, when the punch _{P 1} is further advanced,
Entire end face of the cutting material W is in contact with the inclined surface B, the end surface corner portions Wb of the cutting material W is perpendicular perpendicular to the inclined surface B and the traveling direction of the punch of the punch P ₁ (punch axis L direction) It is fixed by the connecting portion R ₁ of the plane a. This is shown in FIG.
It is a state of. Thereafter, the deformed state advanced punch P ₁ is further (d), the outer diameter surface of the (e) in the cutting material W wraparound the end face side, it will be processed in contact with the punch P _1.

Since the machining state is as described above, the upsetting process is continued without increasing the diameter of the end surface Wa of the cut material W, and the punch side end surface outer peripheral portion Fb of the work F after the upsetting is formed on the end surface Wa. The outer diameter surface of the cut material having no defect is located, and the process ends in a healthy state. As shown in FIG. 6F, that is, as shown in FIG. The fiber flow inside is not generally parallel to the outer peripheral surface of the work, but is substantially concentric with the inside of the work as a center.

In the prior art, cracks are generated at the corners of the end face of the work after the upsetting because the end face of the cut material is too large, and the present invention hardly enlarges the end face. Therefore, a cutting material having a large L / D (the ratio of the length L to the diameter D) that cannot be used in the prior art, that is, a large difference between the cutting material and the work diameter after the upsetting, and a machining process with a large upsetting ratio However, this can be achieved by using the punch according to the present invention.

Next, the punch P ₃ of the third embodiment shown in punch P ₂ and 4 according to the second embodiment shown in FIG. 3
And the deformation state of the work due to the upsetting will be described. First, in the punch P _2, in the state of (c) in FIG. 7, the end surface corner portions Wb of the cutting material W is fixed by the inclined surface B and the connecting portion R ₂ of the intermediate inclined surface C. Thereafter, the deformation state of more advanced punch P ₂ (d), the outer diameter surface of the (e) in the cutting material W wraparound the end face side, it will be processed in contact with the punch P _2.

[0034] Thus, the punch P ₂ Similar results as in the case of using a punch P ₁ according to the Use of this punch P ₂ first embodiment can be obtained, according to the second embodiment
In the stress acting on the connecting portion R ₂ of the inclined surface B and the intermediate inclined surface C is alleviated, the life of the punch is improved than the punch P ₁ of the first embodiment. However, if an angle exceeding 10 ° is set for the intermediate inclined surface C, the function of suppressing the movement of the end face corner Wb of the cutting material W is lost, so that the angle of the intermediate inclined surface C formed continuously from the vertical plane A is It was smaller than plus 10 °.

Next, the effects will be described when using a punch P ₃ of the third embodiment shown in FIG. 4, in the state of FIG. 7 (c), the end surface corner portions Wb of the cutting material W is the inclined surface B and it is fixed at the connection R ₃ of the intermediate inclined surface D.
The connecting portion R ₃ because it has a V-shaped annular groove structure, the end surface corner portions Wb of the cutting material W is suppressed movement of the end surface corner portions Wb engages into the annular groove of the V-shaped The function is enhanced, and there is an effect that the outer diameter surface of the cutting material W in the deformed states (d) and (e) is easily deformed to go to the end face side.

[0036] However, when the angle between the plane A of the intermediate inclined surface D is larger on the minus side exceeding minus 10 °, the stress acting on the connecting portion R ₃ of the inclined surface B and the intermediate inclined surface D is increased Disadvantageous in terms of punch life. Therefore, the angle of the intermediate inclined surface D formed continuously from the vertical plane A was smaller than -10 °.

As described above, the object of the present invention is achieved by the forging punch according to the present invention regardless of any one of the _{first to} third embodiments P ₁ , P ₂ , and P _3. While being able to do so, the fiber flow inside the work F after being machined by the punch according to the present invention is further characterized. That is, as schematically shown in FIG. 6B, the fiber flow inside the work F after the upsetting is not parallel to the outer peripheral surface of the work, but becomes a substantially concentric arc centered on the inside of the work.

When the workpiece F after the upsetting is made into a product H through forging steps (c) and (d) as shown in FIG. 8 as an example, as shown in FIG. While the fiber flow inside the product H remains substantially arcuate as a whole, the fiber flow on the end face also becomes substantially concentric arcuate centering on the inside of the product H, and is in a direction orthogonal to the forging direction. Excellent strength against stress.

[0039]

EXAMPLES As an example, the surface of a spheroidized annealed high carbon chromium bearing steel was treated with a zinc phosphate lubricating film to have a diameter of 15.2.
Table 1 shows the results when the mm-coil was supplied to a multi-stage forging machine and was upset using the punch according to the present invention and the conventional punch. In both the present invention and the prior art, the mold material and material conditions are the same as those described in the embodiment of the invention. In addition, the working conditions of the upsetting ratio and the cutting L / D were the same in the present invention and the prior art.

[0040]

[Table 1]

[0041]

Since the present invention has the above configuration,
Even in processing with a large upsetting ratio, it is possible to prevent the occurrence of cracks at the outer peripheral portion of the end face due to the limit of ductility of the material, and it is possible to improve the end face quality of the product after completion of forging. The required cost can be reduced.
Furthermore, since the fiber flow inside the work after upsetting is almost concentric with the outer peripheral surface of the work centering on the inside of the work, even if the product is made through the forging process, the inside of the product is totally There are various effects such that a product having a large strength against stress in a direction perpendicular to the forging direction can be obtained, since the center remains substantially concentric arc shape.

[Brief description of the drawings]

FIG. 1 is a front view of a tip portion of a forging punch according to the present invention.

FIG. 2 is an enlarged sectional partial view of the same punch according to the first embodiment.

FIG. 3 is an enlarged cross-sectional partial view of the punch according to the second embodiment.

FIG. 4 is an enlarged sectional partial view of the same punch according to a third embodiment.

FIG. 5 is a sectional view showing a configuration of a mold.

FIG. 6 is a schematic view showing a fiber flow of a cut material and a work after upsetting.

FIG. 7 is an explanatory diagram of a processing step showing a deformed state of a cut material.

FIG. 8 is a drawing showing a forging process.

FIG. 9 is a half sectional view of the tip of a conventional forging punch.

FIG. 10 is a cross-sectional view showing a conventional mold configuration.

FIG. 11 is a schematic diagram showing a conventional cutting material and a fiber flow of a work after upsetting.

FIG. 12 is an explanatory diagram of a processing step showing a deformed state of a cutting material by a conventional punch.

FIG. 13 is a conventional forging process diagram.

[Explanation of symbols]

_{P, P 1, P 2,} P 3 forging punch L punch axis A plane B inclined surface C, D intermediate inclined surface _{R 0, R 1, R 2} , R 3 connecting portion W cut material Wa cutting punch side material End face Wb Corner of punch-side end face of cut material F Work after upsetting Fb Outer circumference of punch-side end face of work after upsetting

Claims (3)

[Claims] 1. A method for swaging a cut material with a forging punch, wherein a corner of an end surface of the cut material is restrained to suppress an increase in diameter of an end surface on a punch side, and an outer diameter surface is wrapped around the end surface. A forging method for a cut material, which is characterized by being swaged. 2. An outer peripheral side has a plane perpendicular to the punch axis direction, and the tip portion is constituted by an inclined surface having a convex slope continuing from the plane toward the center of the punch. 2. The forging punch used in the method for forging a cutting material according to claim 1, wherein an angle between the forging punch and the plane is 30 ° or less. 3. An outer peripheral side has a plane orthogonal to the punch axis direction, an intermediate inclined surface having an angle of + 10 ° to −10 ° from the plane, and a convex shape toward the center of the punch. 2. A forging punch for use in a method for forging a cutting material according to claim 1, wherein the tip portion is formed by an inclined surface having an inclination, and an angle between the inclined surface and the plane is 30 ° or less. .