JPH11254055A - Method for shear-punching in two processes in same direction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent property of a cut section by providing a roundness (R) to prevent generation of cracks on a blade tip of a punch in a first process to achieve the half blanking of a work to prevent generation of the secondary shear in a second process to punch out the work. SOLUTION: In the half blanking in a first process, a tip part of a punch 7 is made to have the shape having a taper (θ) of <=15 deg. according to the shearing condition. A trouble that a work is lifted together with the punch is prevented by providing the taper. The height (e) of a tapered part is preferably larger than the thickness (t) of the work 7 (e>=t). Roundness R is formed on the blade tip of the punch 7. Generation of cracks in a part to be half blanked of the work 7 in the first process is avoided by forming roundness R on the blade tip. Relating to roundness R, it is satisfied if approximately arched surface is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for shearing a metal work, for example, for drilling a disk of an automobile wheel, and more particularly, to obtaining an excellent cut surface property. And two-step shear hole drilling method for metal work in the same direction.

[0002]

2. Description of the Related Art A so-called decorative hole is formed in a disk portion of an automobile wheel. Since the decorative hole portion is strongly cold-worked by cold spinning, the strength of the decorative hole portion is increased.

[0003] The portion where the strength is increased is in a state of being highly susceptible to cracking in a shear hole forming process for forming a decorative hole. A high tensile material (490 N / mm ^{2 in} this case) is used for this disk member.
When the above method is used, the strength of the decorative hole portion is further increased, and the crack sensitivity is further increased.

[0004] When a portion in such a state is subjected to a shear hole drilling process by a conventional drilling, a crack at the center of the sheet thickness occurs on the cut surface.

As a method of preventing such cracking, the present applicant has developed a two-step shear hole drilling method in the same direction, and has previously filed a patent application.

The above-described two-step shear hole drilling method in the same direction is a method in which a workpiece is half-punched in a first step, a punch and a die are exchanged in a second step, and the workpiece is removed by a so-called conventional method. The problem of cracks in the center of the thickness of the decorative hole of the high-tensile material was solved.

[0007]

However, in the above method, as shown in FIG.
Cracks 2 may occur in the half-cut portion of the work 1.

[0008] When the crack 2 is generated in this way, the association with the crack generated from the die side in the second step is not successful, so that the cut surface 3 punched out in the second step as shown in FIG.
The burr 4 and the secondary shear 5 are generated in the portion where the crack has occurred, and the appearance of the cut surface is deteriorated. In addition, in FIG.
It is a cut surface formed in the first step.

When the burrs 4 and the secondary shears 5 occur, coining cannot be uniformly applied in the next step, so that the appearance after coining also deteriorates.

[0010] The present invention is directed to two steps in the same direction in which excellent cut surface properties can be obtained by preventing the occurrence of cracks in the first step and the occurrence of burrs and secondary shearing in the second step. An object of the present invention is to provide a method for processing a shear hole.

[0011]

According to the structure of the present invention, there is provided a first step of half-cutting a work as a workpiece using a punch and a die, and a step of half-cutting the work. A second step of punching the workpiece from the same direction as above using a punch and a die. And a roundness (R) for preventing the occurrence of cracks.

[0012]

Next, an embodiment of the present invention will be described. In the present invention, it is assumed that drilling is performed in two steps, a first step and a second step. As shown in FIGS. 3 and 4, in the half blanking in the first step, the tip of the punch 7 has a taper of 15 ° or less depending on the shearing condition.
It has a shape with (θ). By giving the taper in this way, it is possible to prevent a trouble that the work is lifted together with the punch. As shown in FIG. 4, the height e of the tapered portion is preferably larger than the thickness t of the work (e ≧ t).

The edge of the punch 7 is rounded (R). By forming the roundness (R) on the cutting edge in this way, as shown in FIG. 5, it is possible to avoid the generation of cracks in the half-blanked processing portion of the work 1 in the first step.

In the present invention, the roundness (R) is only required to be formed in a substantially arc-shaped curved surface, and does not have to be a complete arc. The point is that the first step may be formed in a round shape (R) so that no crack is generated.

As shown in FIG. 4, the edge of the die 8 is also rounded (R '). As described above, by forming R 'on the cutting edge of the die 8, it is possible to prevent a crack from being generated at the half punching position of the work on the die side.

The radius of curvature of the radius R of the blade tip surface of the punch 7 is
It is 0.5 to 2.0 mm, preferably 1.0 to 1.5 mm. The radius of curvature of the cutting edge R 'of the die is preferably larger than R, specifically 1.5 to 3.0 mm, and more preferably 2.0 to 2.5 mm.

As shown in FIG. 3, the diameter A of the punched hole of the die in the first step and the diameter B of the punch end surface (the portion in contact with the work 1)
Means that the clearance ((A−B) / 2) is negative.

As described above, when the punch 7 is tapered and half-punched so that the clearance becomes negative, the punched waste side and the product side are deformed while receiving compressive force from each other. The machined surface of the separated portion in the state becomes a mirror surface state, which is extremely good.

The degree of half-blanking (the amount of processing) varies depending on the material and plate thickness of the work 1, but it is preferable to set it to 25% to 80% of the plate thickness. If the processing amount is less than 25%, the properties of the processed surface in the second step deteriorate, and if it is more than 80%, the load on the punch increases, leading to a reduction in punch life.

By setting the half-blanking to the above processing amount, cracks at the center can be effectively prevented even when impurities are segregated at the center of the workpiece thickness or when the workpiece is subjected to heavy working. It is possible to prevent such a problem and obtain a good processed surface.

In the second step, as shown in FIG. 6, the shape of the punch 7 'is different from the shape of the punch in the first step, and a straight shape is used. 1
The diameter is larger than the diameter of the half punched hole of the die 8 in the process, that is, punching is performed in the same manner as ordinary punching.

As shown in FIG. 6, the die 8 'in the second step has a clearance ((A'-B') / 2) between the side surface of the punch 7 'and the side surface of the punched hole of the die 8'. In the second step, the plate thickness of the work 1 to be further punched is +4 to +
It is better to select 35%.

In the second step, in order to accurately punch the punch into the punch hole half-punched in the first step, it is necessary to use a work 1
It is good to perform the positioning accurately.

For this purpose, for example, when a decorative hole is formed on a disk of an automobile wheel, a bolt hole may be used for positioning.

Alternatively, a through hole (guide hole) may be formed in the work, and a positioning member connected to the punch in the second step may be fitted into the guide hole so that the work is positioned and punched out at the same time.

[0026]

Next, a description will be given of an embodiment for clarifying the influence of the roundness (R) of the punch edge on the properties of the cut surface when two large holes are drilled in the same direction in a real disk decoration hole.

(Work to be Tested) As the work, a high-tensile material of 540 N / mm ² grade subjected to cold spinning was used. The plate thickness of the flat portion of the work is 12 mm, and the plate thickness is reduced by cold spin from the decoration hole to the end of the disk. The thickness of the decorative hole is about 9 mm at the center of the disc and about 5 mm at the end of the disc.

Incidentally, in the above-mentioned test work, the strength of the decorative hole position is increased due to the cold working, and the crack sensitivity is high. For this reason, it has been confirmed by experiments that cracking occurs at the center of the plate thickness when the work is conventionally punched.

(Test Method) As a half punch for the first step, an end face diameter of 80.40 and a cutting edge R of 0.5 to 1.0 m were used.
m, the end face diameter is the same as the blade edge R 1.0-1.5 mm,
End face diameter 80.80 mm, cutting edge R 0.5-1.0 mm,
Four shapes having the same edge diameter as the above and having a blade edge R of 1.0 to 1.5 mm were produced. The taper (θ) on the tip side of the punch is
All were 6 mm.

The die for the first step has a hole diameter of 7 mm.
9.00 mm, radius of curvature of cutting edge R is 2.0 to 2.5 mm
Was used. The second step was carried out in the same manner as the above-mentioned ordinary punching, using ordinary ones without roundness (R) for the cutting edges of the punch 7 'and the die 8'.

(Results) It was confirmed that by setting the cutting edge R of the punch 7 in the first step as described above, superior cut surface properties can be obtained as compared with the case where no R is provided.

From the above results, it is impossible to obtain excellent cut surface properties only by adjusting the clearance ((AB) / 2 in FIG. 3) and the amount of bite, and the radius of curvature of the punch edge R is adjusted appropriately. It became clear that it was possible to solve it. In this embodiment, the radius of curvature of the punch edge R is 1.0 to 1.5 mm, and the clearance is −0.9 m.
At the time of m, the most excellent properties were obtained.

According to the method of the present invention, a thin plate having a thickness of 1 mm or less
The invention can be applied to a plate having a thickness of not less than mm, and the thickness of the work is not particularly limited. The material of the work can be applied not only to steel materials but also to various metals and alloys. The shape of the work can be applied not only to a flat plate but also to a curved surface.

The method of the present invention can be applied not only to the drilling of hub holes, bolt holes, and decorative holes on disks of automobile wheels, but also to the drilling parts of all metals and alloys. Further, the shape of the hole to be punched can be any shape such as a circle, an ellipse, or the like, which is punched by a conventional punching.

[0035]

According to the present invention, the roundness (R) is imparted to the punch in the first step, so that it is possible to avoid the occurrence of cracks in the half-blanked portion of the work. As a result, burrs and secondary shear do not occur in the second step, so that a cut surface having an excellent appearance can be obtained over the entire circumference.

In addition, since coining can be evenly applied in the next step, the appearance after coining also becomes excellent.

[0037]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a half-punched work in a conventional first step in a two-step drilling method.

FIG. 2 is a perspective view of a hole extracted by a conventional two-step drilling method.

FIG. 3 is a sectional view of a first step of the present invention.

FIG. 4 is an enlarged view of a part X in FIG. 3;

FIG. 5 is a cross-sectional view of a workpiece half-blanked in a first step of the present invention.

FIG. 6 is a sectional view showing a second step of the present invention.

FIG. 7 is a perspective view of a hole dropped by the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Work 2 Crack 3,3 'Cut surface punched in 2nd process 4 Burr 5 Secondary shear 6,6' Cut surface formed in 1st process 7,7 'Punch 8,8' Dice A 1st Die hole diameter of process die B Punch end face diameter of first process A 'Die hole diameter of second process die B' Punch diameter of second process R Roundness of punch edge R 'Roundness of die edge

Claims (10)

[Claims] A first step of half-punching a workpiece, which is a workpiece, using a punch and a die;
And a second step of punching a workpiece from the same direction as above using a punch and a die. A method of forming a two-step shear hole in the same direction, wherein a roundness (R) for preventing the occurrence of cracks is provided. 2. The processing method according to claim 1, wherein a taper is provided on a tip side of the punch in the first step and a roundness (R) is provided on a cutting edge. 3. The radius of curvature of the roundness (R) of the cutting edge is 0.
The processing method according to claim 1, wherein the thickness is 5 to 2.0 mm. 4. The diameter of the punch end face in the first step is slightly larger than the diameter of the punched hole of the die in the first step.
3. The processing method according to any one of 3. 5. The processing method according to claim 1, wherein a radius of curvature (R ′) having a larger radius of curvature than the radius (R) of the punch edge is provided to the die edge of the first step. . 6. The processing method according to claim 1, wherein the diameter of the hole of the die in the second step is larger than the diameter of the half hole of the die in the first step. . 7. The method according to claim 7, wherein the diameter of the punched hole of the die in the second step is the second.
The clearance between the punch in the process and the hole of the die in the second process is +4 of the work plate thickness to be further punched in the second process.
The processing method according to any one of claims 1 to 6, wherein the diameter has a diameter of% to + 35%. 8. The half-blanked portion has a thickness of 25 to 25% of the work thickness.
The processing method according to claim 1, wherein the punching is performed by 80%. 9. The processing method according to claim 1, wherein the work is a high-tensile material having a strength of 490 N / mm ² or more. 10. The processing method according to claim 1, wherein in the second step, the workpiece half-cut in the first step is positioned.