JP3339363B2 - Half blanking forming method and cold forging die used for the method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for half blanking a workpiece and a cold forging die used for the method.

[0002]

2. Description of the Related Art FIG. 14 shows a ratchet plate P 'used for a seat reclining device.
In ′, the inner peripheral portion of the circular plate is further concavely formed in a circular shape, and a tooth profile P1 is formed on the inner periphery of the concave portion. As a method of integrally forming the ratchet plate P ′ having such inner peripheral teeth P1, half punch press forming using a cold forging die is known. In this, as shown in FIG. 11, a plate holder 4 and a punch 3 having a molding tooth shape 31 on the outer periphery are provided on an unillustrated upper die, while the outer die of the punch 3 is provided on a lower die. A die 5 having a die hole 51 having a large inner diameter is provided, and the punch 3 is held while the workpiece M is held by the plate holder 4 and the die 5.
Is advanced by a predetermined amount.
Is formed by shearing the central portion of the workpiece M, and a tooth profile P1 (FIG. 14) is simultaneously formed on the inner periphery of the recessed portion of the workpiece M extruded by the punch 3 and formed by half punching. Is done.

However, in this method, there is a problem that a crack C due to a shearing force (arrow in FIG. 11) is apt to be generated at the time of molding on a line connecting the cutting edge 52 of the opening edge of the die hole 51 and the corner of the tip of the punch 3. . Note that in FIG.
Is a knockout slidably provided in the die hole 51, and the knockout 7 retreats with almost no resistance to the workpiece M cut into the die hole 51 during molding.

In order to prevent the occurrence of cracks during molding, as shown in FIG. 12, the inner diameter of the die hole 51 is made smaller than the outer diameter of the punch 3 so that the die 5 and the punch 3 are wrapped. The cutting blade 52 of the die hole 51 and the punch 3
There is a method in which a predetermined hydrostatic pressure is applied to a material portion on a line connecting the tip corner portions during molding.

[0005]

However, according to this method, although the occurrence of cracks is prevented, the half-blanking depth (d in FIG. 12) must always be smaller than the thickness of the workpiece M. For this reason, when the inner peripheral teeth are formed, there is a problem that the length of the engagement margin cannot be sufficiently secured. On the other hand, if it is attempted to increase the half-deeping depth d to secure a long allowance for engagement of the inner peripheral teeth, the thickness of the portion (A in FIG. 12) connecting the inner peripheral portion and the outer peripheral portion of the product becomes insufficient. , The strength is reduced. Further, since a large compressive load is applied to the lap portion between the die 5 and the punch 3 during molding, there is a problem that the life of the punch 3 having the molding tooth form 31 is particularly reduced.

Accordingly, the present invention has been made to solve such a problem, and a product having a high strength can be obtained while securing a sufficient half-punching depth, and a half-punching forming method which does not cause a reduction in the life of a press device. An object is to provide a cold forging die used for this.

[0007]

Means for Solving the Problems To achieve the above object, the half blanking forming method of the first invention comprises a plate holder (4),
Punch (3) provided on plate holder (4) side and plate holder (4)
Punch and disposed opposite dies (5), in contact with the inner circumferential die hole (51) in a reverse pressing punch slidably provided (6), die (5) and the (3) wraps
Use a cold forging die in which the inner diameter of the die hole (51) is larger than the outer diameter of the punch (3) so that the punch (3) is not covered.
By entering the center of the upper surface of the work material (M),
Work material while forming a recess at the center of the upper surface of the work material (M)
When the center of the lower surface of (M) enters the die hole (51),
Sometimes, the workpiece (M) is clamped by the punch (3) and the reverse presser punch (6), and half-punching is performed while applying a hydrostatic pressure that causes compressive deformation to the clamping portion.
In this case, a necessary portion of the outer periphery of the punch (3) is formed with a molding tooth profile (3
1) can be provided.

According to the first aspect of the present invention, the workpiece portion sandwiched by the punch and the reverse presser punch receives a large hydrostatic pressure and undergoes compression deformation, and at this portion, the plastic fluidity of the material itself is improved. The material is efficiently supplied to the shear deformation portion during molding. Thereby, the occurrence of cracks in the shear deformation portion is prevented. In the first invention, a cold forging die in which the inner diameter of the die hole is larger than the outer diameter of the punch can be used, so that the half-blanking depth is not limited to within the thickness of the workpiece. Further, even if the half-blanking depth is increased, the thickness of the portion connecting the inner peripheral portion and the outer peripheral portion of the product does not become thin, so that sufficient product strength can be obtained. Further, since the die of the cold forging die and the punch do not overlap, no excessive compressive load is applied to the punch or the like at the time of molding, and a reduction in life can be avoided. Since the shaping depth at the time of shaping can be increased, when the shaping tooth profile is provided on the outer periphery of the punch, the meshing allowance of the inner circumferential teeth simultaneously formed at the time of shaping can be sufficiently ensured.

In the second aspect of the present invention, the cold forging die used in the half blanking forming method includes a cutting blade (5) on the periphery of the die hole (51).
2) is formed into a tapered surface that opens outward.

[0010] Since the cutting edge has a tapered surface, the material having improved plastic fluidity can be more efficiently supplied to the shear deformation portion, and thereby the generation of cracks during molding can be more effectively prevented. You.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a cross section of a cold forging die of a press apparatus to which the method of the present invention is applied. In the figure, a columnar punch 3 is provided on the lower surface of the upper die 1 downward. On the outer periphery of the punch 3, the forming tooth shape 31
Is formed, the center of the tip is recessed to form a recess 32, and a necessary portion around the recess 32 is left without being recessed to form a projection 33. An annular plate holder 4 is provided around the punch 3.
Is supported at the back by hydraulic pistons 41 and 42 projecting from the upper mold 1. An annular projection 43 is formed on the lower surface of the plate holder 4 so as to surround the punch 3.

A die 5 is provided on the lower die 2, and a die hole 51 having a shape similar to the punch 3 and having an inner diameter larger than the outer diameter is formed at the center thereof. The workpiece M is placed on the upper surface of the die 5. The die hole 51 is formed by the punch 3
In the die hole 51, a reverse pressing punch 6 is slidably in contact with the inner periphery thereof. The back press punch 6 is supported by a hydraulic piston 61 at the back. The cutting edge 52 at the opening edge of the die hole 51 is a tapered surface that opens outward at a fixed angle.

A method for half-punching a workpiece using such a press device will be described below. When the upper mold 1 is lowered from the top dead center, the annular projection 43 of the plate holder 4 comes into contact with the upper surface of the workpiece M (point a in FIG. 6). The load of No. 4 increases proportionally (FIG. 6). The point b in FIG. 6 is a point at which the plate presser 4 is separated from the upper surface of the workpiece M. When the upper die 1 further descends, the tip of the projecting portion 33 of the punch 3 comes into contact with the workpiece M (FIG. 2), and the load of the punch 3 rapidly increases as the upper die 1 moves toward the bottom dead center (FIG. 7). At this time, the annular projection 43 of the plate holder 4
Cuts into the upper surface of the workpiece M in a wedge shape, and supplies the material to the shearing deformation portion at the time of processing to prevent the occurrence of sagging.

When the upper mold 1 is further lowered, as shown in FIG. 3, the punch 3 enters the central portion of the upper surface of the workpiece M while shearing it, and the punch 3 Inner peripheral teeth are formed in the concave portion by the molding tooth form 31. At the same time, the center of the lower surface of the workpiece M is
The cut is made to enter by shearing deformation. At this time, the load of the punch 32 suddenly increases toward the bottom dead center of the press as described above (FIG. 7), but at the same time, according to the method of the present invention, the reverse pressing punch 6 abuts against the center of the lower surface of the workpiece M. Is also increased rapidly toward the bottom dead center of the press as shown in FIG. As a result, the workpiece M is pinched by the projecting portion 33 of the punch 3 and the back-pressing punch 6 particularly from the upper and lower edges (white arrows in FIG. 5), and this portion is subjected to a large hydrostatic pressure and is compressed and deformed. At the same time, the plastic fluidity of the material itself in this portion is improved, and the material is supplied to the shear deformation portion during molding, as indicated by the black arrow in FIG. This material supply is facilitated by the generation of a large pressing force on the lower end protruding portion 33 of the punch 3 and the use of the cutting edge 52 at the opening edge of the die hole 51 as a tapered surface that opens outward. To prevent cracking. When the forming of the workpiece M is completed, as shown in FIG.
Is raised, the reverse press punch 6 is raised, and the ratchet plate P as a product whose appearance is shown in FIG. 13 is released.

Thus, when the method of the present invention is applied,
A good product without cracks can be obtained even by using a press device in which the inner diameter of the die hole 51 is larger than the outer diameter of the punch 3. Therefore, as shown in FIG. In the case where the inner peripheral teeth P1 are formed as described above, it is not necessary to limit the engagement margin d within the thickness of the product P (that is, the workpiece M), and the product P having the engagement margin d of a sufficient length is not required. Obtainable. Further, even if the engagement margin d having a sufficient length is secured, a vertical wall P2 is always formed at a portion connecting the inner peripheral portion and the outer peripheral portion of the product P, and the thickness of this portion is ensured to provide sufficient product strength. Is obtained. Furthermore, since the die 5 and the punch 3 of the press device do not overlap, an excessive pressure load is not applied to the punch 3 and the like at the time of molding, and a reduction in the life can be avoided.

(Second Embodiment) The work piece M is pressed,
As a structure for improving the plastic fluidity of the material in this portion, for example, as shown in FIG. 9, the lower end face of the punch 3 is made flat, and the center of the upper end face of the reverse pressing punch 6 opposed to this is formed as a recess. Projection 62
Can be adopted. According to such a structure, the peripheral edge of the central portion of the workpiece M is pressed from above and below by the projecting portion 62 and the lower end surface of the punch 3 as indicated by the white arrow in the drawing to improve the plastic fluidity of the material in this portion. As a result, as shown by the black arrow in the drawing, the material is efficiently supplied to the shear deformation portion during molding along the cutting blade 52 having the tapered surface. As described above, when the protruding portion 62 is provided on the reverse pressing punch 6 side, the material flows more easily to the shear deformation portion. As a result, a vertical wall P2 is always formed at a portion connecting the inner peripheral portion and the outer peripheral portion of the completed product even if the half-blanking depth d is increased, and the thickness of this portion is ensured to provide sufficient product strength. Are obtained, and the same effects as in the first embodiment can be obtained.

(Third Embodiment) As shown in FIG. 10, the protrusion 63 may be provided on the outer periphery of the upper end surface of the reverse pressing punch 6 in a circular cross section. Even with such a structure, the peripheral edge of the center of the workpiece M is pressed from above and below by the projecting portion 63 and the lower end surface of the punch 3 as indicated by the white arrow in the figure, and the plastic fluidity of the material in this portion is improved. Thus, as indicated by the black arrow in the drawing, the material is efficiently supplied to the shear deformation portion during molding along the cutting edge 52 having the tapered surface. In the present embodiment, the same effects as in the second embodiment can be obtained.

[0018]

As described above, according to the present invention, a product having high strength can be obtained while securing a sufficient half-blanking depth, and the life of the press device does not decrease.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cold forging die of a press device to which a method of the present invention is applied according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the cold forging die when the press device is operated.

FIG. 3 is a cross-sectional view of the cold forging die when the press device is operated.

FIG. 4 is a cross-sectional view of the cold forging die when the press device is operated.

FIG. 5 is an enlarged sectional view of a main part of the cold forging die when the press device is operated.

FIG. 6 is a graph showing a temporal change of a plate pressing load when the press device is operated.

FIG. 7 is a graph showing a change over time of a punch load when the press device is operated.

FIG. 8 is a graph showing a change with time of a reverse press punch load when the press device is operated.

FIG. 9 is an enlarged cross-sectional view of a main part of a cold forging die during operation of a press device according to a second embodiment of the present invention.

FIG. 10 is an enlarged sectional view of a main part of a cold forging die when a press device is operated in a third embodiment of the present invention.

FIG. 11 is an enlarged sectional view of a main part of a cold forging die of a press device to which a conventional method is applied.

FIG. 12 is an enlarged sectional view of a main part of a cold forging die of a press device to which a conventional method is applied.

FIG. 13 is an overall perspective view of a ratchet plate formed by the method of the present invention.

FIG. 14 is an overall perspective view of a ratchet plate formed by a conventional method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 3 ... Punch, 31 ... Molding tooth shape, 33 ... Projection part, 4 ... Plate holder, 5 ... Die, 51 ... Die hole, 52 ... Cutting blade, 6 ... Reverse holding punch, 62, 63 ... Projection part, M ... Cover Work material, P1
… Inner teeth.

Continuation of the front page (56) References JP-A-57-172276 (JP, A) JP-A-50-53,981 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21J 1 / 00-13/14 B21J 17/00-19/04 B21K 1/00-31/00 B21D 28/10 B21D 28/14 B21D 28/34

Claims (2)

(57) [Claims] 1. A plate retainer (4), a punch (3) provided on the plate retainer (4) side, a die (5) arranged opposite to the plate retainer (4), and a die hole. (51) in the inner circumference
Contact with a slidably reverse pressing punch is provided (6) and with said punch (3) and the die (5) does not wrap
As described above, the inner diameter of the die hole (51) is larger than that of the punch (3).
Using a cold forging die larger than the outer diameter of the punch
(3) into the center of the upper surface of the workpiece (M).
As a result, a recess is formed at the center of the upper surface of the workpiece (M).
The center of the lower surface of the workpiece (M) is formed in a die hole (5
1) At the same time, the workpiece (M) is pressed by the punch (3) and the reverse pressing punch (6), and a hydrostatic pressure that causes compressive deformation is applied to the pressing portion. A half blanking forming method characterized by performing half blanking while performing. 2. A cold forging die used in the half blanking forming method according to claim 1, wherein a cutting edge (52) on a peripheral edge of the die hole (51) is formed into a tapered surface that opens outward. Features a cold forging die.