JP7617174B2 - Bending die regeneration method and regenerated bending die - Google Patents

Description

The present invention relates to a method for recycling bending dies and recycled bending dies.

Patent Document 1 describes a method for regenerating a worn die (hereinafter, referred to as a die regeneration method). The die regeneration method described in Patent Document 1 is a method for regenerating a new edge portion of a press punch die by applying buildup welding to an edge portion that has worn or chipped due to use, and then mechanically grinding the welded buildup portion.
The method of recycling dies described in Patent Document 1 is not limited to press punch dies, but is commonly used as a method of recycling other dies, and punch dies and die dies for bending dies can also be recycled using this method.

A conventional method for recycling bending dies will be described with reference to Figures 7A and 7B, using a punch die as an example. Figure 7A is a right side view showing a conventional punch die 101. Figure 7B is a diagram for explaining the conventional die recycling method, and Figures 7B (a) to (c) are side views corresponding to the first to third steps, respectively.

As shown in FIG. 7A, a conventional punch die 101 has a body portion 111 that is attached to a punch holder, and a cutting edge portion 112 that is formed at the tip of the body portion 111 and that comes into contact with a workpiece.
FIG. 7B is an enlarged view of the tip region 112A of the cutting edge portion 112 in FIG. 7A. The cutting edge portion 112, which has been subjected to multiple bending processes, has a worn surface 112c whose outer shape has been worn away from the outer shape of the reference cutting edge line LNa when not in use, which is shown by the two-dot chain line in FIG. 7B(a).

When the wear has progressed to a certain extent, as shown in FIG. 7B(b), metal is welded to form a padded portion 113 of a size and cross-sectional shape that includes the reference cutting edge line LNa. The padded portion 113 is then ground to match the external shape of the reference cutting edge line LNa using a punch forming grindstone 105 having a shape that corresponds to the reference cutting edge line LNa, resulting in a regenerated punch top 114 as shown in FIG. 7B(c).

Japanese Patent Application Publication No. 7-265972

The finishing dimensions of the bending die are set with a tolerance that takes into account variations in processing during manufacturing within a range that allows performance to be achieved as specified. Specifically, the punch die 101 is set with a tolerance of, for example, "+0 mm to -0.05 mm" for its dimension in the thickness direction. Meanwhile, the grinding surface shape of the punch forming grindstone 105 shown in Fig. 7B(b) is designed to form a grinding surface of ±0 mm corresponding to the reference cutting edge line LNa.
Therefore, if the pre-use dimensions of the cutting edge portion 112 of the punch die to be recycled are formed near the upper limit of the tolerance, as shown in Figure 7B (c), the cutting edge portion 112 and the recycled punch top portion 114 formed by grinding the padding portion 113 using the punch forming grindstone 105 will be formed with a continuous surface without any steps.

In contrast, if the thickness dimension of the cutting edge 112 before use is formed near the lower limit of the tolerance, a gap Δd corresponding to the tolerance is generated between the punch forming grindstone 105 and the cutting edge 112 as shown in FIG. 8A. Then, a grinding surface corresponding to the reference cutting edge line LNa is formed on the recycled punch top 114 formed by grinding the padded portion 113, but as shown in FIG. 8B, a steep step 115 is formed at the end of the padded portion 113, with the padded portion 113 side being convex. This step 115 is formed along the longitudinal direction of the punch die 101 (the left-right direction shown in FIG. 1). FIG. 8A shows a case where the gap Δd is generated on the left side of the figure, but it may be generated on the right side of the figure or on both sides, and there is a risk that the step 115 will be formed on the right side or both sides.

The same is true for die molds; if the width of the V-groove is biased toward the larger tolerance side, there is a risk that a steep step will be formed on at least one of the pair of inclined surfaces of the V-groove, causing the buildup to become convex.

If such a step 115 is formed in the cutting edge 112 of the punch 101, which is a bending die, and in the V-groove of the die, the appearance quality of the punch 101 and the die will be reduced, and if the bending process is so-called coining, there is a risk that a line corresponding to the step 115 will be formed on the surface of the workpiece, reducing the appearance quality of the workpiece, and therefore improvement is desired.

In order to solve the above problems, one embodiment of the bending die regeneration method of the present invention has the following configuration. That is, the bending die regeneration method includes a build-up process for forming a build-up portion covering the entire surface to be regenerated on a base material of the bending die having a surface to be regenerated that is different from a reference shape, and a shaping process for shaping the build-up portion into the reference shape by rotating a grindstone having a grinding portion that grinds the build-up portion, the grinding portion of the grindstone having a peripheral convex portion that is carved out to include the external end of the build-up portion that connects to the base material, and the shaping process is a bending die regeneration method in which the peripheral convex portion forms a recess in the bending die that includes the external boundary between the base material and the build-up portion.

In this embodiment, by forming a recess that includes the boundary between the base material and the build-up portion, a steep step is not formed where the build-up portion becomes convex, and even if the bending process is coining, no line corresponding to the step is formed on the surface of the workpiece, and the appearance quality is not reduced.

In order to solve the above problems, one embodiment of the recycled bending die of the present invention has the following configurations 1) and 2) .
1) A first portion having a substantially plate-like shape formed from a first material and a V-shaped cutting edge or V-groove portion having a V-shaped cross-sectional shape formed by a first surface and a second surface at one edge portion;
A second portion is provided on a tip side of the cutting edge portion or the V-groove portion and is made of a second material different from the first material,
the first surface and the second surface each have a recess formed in a range including an apparent boundary between the first region and the second region ,
The recycled bending die is a punch die having the cutting edge portion at the first portion .
2) a first portion having a substantially plate-like shape formed from a first material and a V-shaped cutting edge or V-groove portion having a V-shaped cross-sectional shape formed by a first surface and a second surface at one edge;
A second portion is provided on a tip side of the cutting edge portion or the V-groove portion and is made of a second material different from the first material,
the first surface and the second surface each have a recess formed in a range including an apparent boundary between the first region and the second region ,
The first portion and the second portion are smoothly connected to each other by rounding.
the second portion is formed of laminated metal powder;
The recycled bending mold is a die having the V-groove portion in the first portion .

This embodiment has a recess that includes the boundary between the first and second parts, so a steep step is not formed where the second part becomes convex, and even if the bending process is coining, no lines corresponding to the step are left on the surface of the workpiece, so the appearance quality is not reduced.

According to one embodiment of the bending die recycling method and one embodiment of the recycled bending die of the present invention, there is no step at the cutting edge of the punch die and the V-groove of the die die, so there is no degradation of the appearance quality, and even if the bending process is coining, there are no lines on the surface of the workpiece, so there is no degradation of the appearance quality.

FIG. 1 is a perspective view showing the appearance of a punch die 1 which is a first embodiment of the recycled bending die of the present invention. FIG. 2 is a cross-sectional view for explaining a method for forming the cutting edge portion 12 of the punch 1. FIG. 3A is a cross-sectional view for explaining the first step of shaping the cutting edge portion 12 in a first embodiment of the bending die regenerating method of the present invention. FIG. 3B is a cross-sectional view for explaining the second step of shaping the cutting edge portion 12 in the first embodiment of the bending die regenerating method. FIG. 3C is a cross-sectional view for explaining the third step of shaping the cutting edge portion 12 in the first embodiment of the bending die regenerating method. FIG. 3D is a cross-sectional view for explaining the fourth step of shaping the cutting edge portion 12 in the first embodiment of the bending die regenerating method. FIG. 3E is a cross-sectional view for explaining the first step of shaping the cutting edge portion 12 in the second embodiment of the bending die regenerating method of the present invention. FIG. 3F is a cross-sectional view for explaining the second step of shaping the cutting edge portion 12 in the second embodiment of the bending die regenerating method. FIG. 4 is a perspective view showing the appearance of a die 2 which is a second embodiment of the recycled bending die of the present invention. FIG. 5A is a cross-sectional view for explaining the first step of forming a V-groove portion 22 in a first embodiment of the bending die regenerating method of the present invention. FIG. 5B is a cross-sectional view for explaining the second step of forming the V-groove portion 22 in the first embodiment of the bending die recycling method. FIG. 5C is a cross-sectional view for explaining the third step of forming the V-groove portion 22 in the first embodiment of the bending die recycling method. FIG. 5D is a cross-sectional view for explaining the fourth step of forming the V-groove portion 22 in the first embodiment of the bending die regenerating method. FIG. 6A is a plan view showing a punch forming grindstone 5 used in the first and second embodiments of the bending die regenerating method. FIG. 6B is a plan view showing the die forming grindstone 6 used in the first and second embodiments of the bending die regenerating method. FIG. 7A is a side view showing a punch die 101 of a conventional recycled bending die. FIG. 7B is a diagram for explaining a conventional method for regenerating a bending die, and FIG. 7B(a) to (c) are cross-sectional views corresponding to the first to third steps, respectively. FIG. 8A is a cross-sectional view showing an example of a forming step of a cutting edge portion 112 in a conventional method for remanufacturing a bending die. FIG. 8B is a perspective cross-sectional view showing the cutting edge portion 112 of a conventional recycled bending die.

The recycled bending die of the present invention will be described with reference to Figures 1 to 6B using a punch die 1 of a first embodiment and a die die 2 of a second embodiment as examples. The punch die 1 and the die die 2 are each included in the recycled bending die K.

(Punch die 1)
FIG. 1 is a perspective view showing the appearance of a punch die 1 which is a first embodiment of the regenerated bending die of the present invention. FIG. 2 is a cross-sectional view for explaining a method for shaping the cutting edge portion 12 of the punch die 1. FIG. 3A is a cross-sectional view for explaining a first step of shaping the cutting edge portion 12 in the first embodiment of the regenerating method for a bending die of the present invention. FIG. 3B is a cross-sectional view for explaining a second step of shaping the cutting edge portion 12 in the first embodiment of the regenerating method for a bending die. FIG. 3C is a cross-sectional view for explaining a third step of shaping the cutting edge portion 12 in the first embodiment of the regenerating method for a bending die. FIG. 3D is a cross-sectional view for explaining a fourth step of shaping the cutting edge portion 12 in the first embodiment of the regenerating method for a bending die. FIG. 3E is a cross-sectional view for explaining a first step of shaping the cutting edge portion 12 in the second embodiment of the regenerating method for a bending die of the present invention. FIG. 3F is a cross-sectional view for explaining a second step of shaping the cutting edge portion 12 in the second embodiment of the regenerating method for a bending die. Fig. 6A is a plan view showing a punch forming grindstone 5 used in the first and second embodiments of the bending die regeneration method. Fig. 6B is a plan view showing a die forming grindstone 6 used in the first and second embodiments of the bending die regeneration method. For ease of explanation, the up, down, left, right, front and back directions are defined as the directions shown by arrows in Fig. 1.

As shown in FIG. 1, the punch die 1 of the recycled bending die K has a punch body 11 as a substantially plate-shaped base material A extending up, down, left, and right, and a cutting edge 12 formed on one edge, which is the lower edge, of the punch body 11. The punch body 11 is attached to a punch holder of a bending machine. The punch die 1 moves up and down by the operation of the attached bending machine, and when it descends, the cutting edge 12 comes into contact with the upper surface of the workpiece W (see FIG. 3D) placed between the punch die 1 and a die 2 (see FIG. 4) described later, and presses the workpiece W downward, thereby bending the workpiece W.

As shown in Figures 1 and 2, the cutting edge 12 is V-shaped in side view with a pair of tapered inclined surfaces. The inclined plane on the front side of the cutting edge 12 is the first inclined surface 12a as the first outer surface, and the inclined plane on the rear side is the second inclined surface 12b as the second outer surface. In the cutting edge 12, the first inclined surface 12a has a first recess 121 extending in the left-right direction near the tip, and the second inclined surface 12b has a second recess 122 extending in the left-right direction near the tip. The first recess 121 and the second recess 122 are collectively referred to as recess E.

As shown in FIG. 2, the first inclined surface 12a and the second inclined surface 12b are formed by grinding with a punch forming grindstone 5. The punch forming grindstone 5 is a grindstone having a cylindrical or disk-shaped base body 50, and a grinding portion 5G having a predetermined grinding surface is formed on the peripheral surface of the base body 50. The predetermined grinding surface has a shape corresponding to the final finished shape of the cutting edge portion 12. The punch forming grindstone 5 is collectively referred to as grindstone C, and the grinding portion 5G is collectively referred to as grinding portion Ca.

In detail, the grinding portion 5G has a first concave inclined grinding wheel surface 5a that forms the first inclined surface 12a of the cutting edge portion 12 and a second concave inclined grinding wheel surface 5b that forms the second inclined surface 12b of the cutting edge portion 12. The first concave inclined grinding wheel surface 5a has a first peripheral convex portion 51 that forms the first recess 121 of the cutting edge portion 12, and the second concave inclined grinding wheel surface 5b has a second peripheral convex portion 52 that forms the second recess 122 of the cutting edge portion 12. The first peripheral convex portion 51 and the second peripheral convex portion 52 are convex portions formed over the entire circumference in shapes corresponding to the shapes of the first recess 121 and the second recess 122, respectively. The first peripheral convex portion 51 and the second peripheral convex portion 52 are included in the general term peripheral convex portion Ca1.

The punch forming grinding wheel 5 is attached to a grinding machine (not shown) and rotates around the axis CL5 while being pressed against the cutting edge 12. As a result, the cutting edge 12 is ground into a shape corresponding to the grinding part 5G.

The worn cutting edge portion 12 is the surface Aa to be refurbished, and is refurbished using the bending die refurbishment method of the first embodiment described below. In the description, please refer to Figures 3A to 3D.

Figure 3A shows the cutting edge portion 12 having a leading wear surface 12c, which is the surface Aa to be regenerated in a worn state. The outermost two-dot chain line is the imaginary reference cutting edge line LN1a in a new, unworn state. The outer shape in the worn state is shown by the solid wear edge line LN1b. The two-dot chain removal cutting edge line LN1c indicates the removal position of the portion to be removed in the next process. The removal cutting edge line LN1c is set as a straight line extending in the front-to-rear direction above the wear edge line LN1b.

First, as shown in FIG. 3B, the portion of the worn cutting edge 12 below (toward the tip) the removal edge line LN1c is removed by grinding or other processing. The removal is performed over the entire range in the longitudinal direction (left-right direction) of the punch die 1. As a result, a removal surface 12d, which is a flat surface extending in the front-rear and left-right directions, is formed at the position of the removal edge line LN1c.

Next, as shown in FIG. 3C, a padding portion 13 is formed at the tip of the cutting edge 12. The padding portion 13 completely covers the removal surface 12d, and padding end positions P2a, P2b, which are the upper ends of the padding, are located closer to the base side (upper side) of the cutting edge 12 than the removal surface end positions P1a, P1b, which are the connection positions of the removal surface 12d and the first and second inclined surfaces 12a, 12b. The padding portion 13 is collectively referred to as padding portion B. In addition, if the visible end of padding portion B that connects to the base material A is referred to as end Ba, the padding end positions P2a, P2b are collectively referred to as end Ba.

The method of forming the build-up portion 13 is not limited. For example, methods such as laser cladding, PTA (Plasma Transferred Arc Welding) welding, and thermal spraying can be used. The metal to be built-up is also not limited, and may be a material different from the material of the punch body portion 11 of the base material A, and may be selected appropriately depending on the application and specifications.

The amount of removal and the amount of build-up required to obtain the removal surface 12d may be adjusted as appropriate according to the amount of wear on the cutting edge 12. When the amount of removal is large, the removal surface end positions P1a and P1b are positioned higher, so the build-up end positions P2a and P2b need to be positioned even higher to cover the removal surface 12d, requiring a larger amount of build-up.

Then, the padding portion 13 is cut and shaped by the punch forming grindstone 5 described with reference to FIG. 2 to form the recycled punch top 14 corresponding to the reference cutting edge line LN1a. As described above, the punch forming grindstone 5 has a first peripheral convex portion 51 and a second peripheral convex portion 52. Therefore, a first recess 121 corresponding to the first peripheral convex portion 51 is formed on the first inclined surface 12a of the recycled punch top 14, and a second recess 122 corresponding to the second peripheral convex portion 52 is formed on the second inclined surface 12b.

3D, the first recess 121 is formed by removing a range including the build-up end position P2a on the first inclined surface 12a. The second recess 122 is formed by removing a range including the build-up end position P2b on the second inclined surface 12b.
The depth Dp1 of the first recess 121 and the second recess 122 is determined in accordance with the tolerance set for the dimension in the thickness direction (front-rear direction) of the punch die 1. For example, if the tolerance of the dimension D1 in the thickness direction (see FIG. 2) is set to "+0 mm to -0.05 mm," the depth Dp1 may be set to a value that exceeds 0.05 mm in theory, but may be set to, for example, 0.1 mm, including a certain degree of margin.

The shapes of the first recess 121 and the second recess 122 are not limited as long as they do not protrude from the first inclined surface 12a and the second inclined surface 12b, respectively. The shapes of the first recess 121 and the second recess 122 may be concave curved surfaces with a curved cross section, or may include a three-dimensional plane in which a part of the curve of the cross section is a straight line. For example, the first recess 121 may be connected so that its upper and lower ends are clearly bent with the first inclined surface 12a. In addition, the first recess 121 may be shaped so that its upper and lower ends are smoothly connected to the first inclined surface 12a by R-forming, which is desirable from the viewpoint of reducing the influence on the workpiece W during coining. The same applies to the second recess 122.

In the first aspect of the bending die regeneration method described above, the worn cutting edge shape is regenerated to obtain a punch die 1 having a regenerated punch top 14 with an unused cutting edge shape.

In the above-mentioned first embodiment of the regeneration method, whether or not to remove the tip portion of the cutting edge 12 may be determined depending on the degree of wear. In other words, when regenerating when the degree of wear is small, the regeneration method of the second embodiment described below may be carried out without removing the tip portion.

Specifically, in the second aspect of the bending die regeneration method, when the amount of wear is less than a predetermined amount in the cutting edge portion 12 to be regenerated having the tip wear surface 12c shown in FIG. 3A, as shown in FIG. 3E, a padding portion 13 is formed without removing the tip. The padding portion 13 completely covers the tip wear surface 12c, which is the surface Aa to be regenerated, and the padding end positions P2a, P2b, which are the upper ends of the padding portion 13, are located closer to the base side (upper side) of the cutting edge portion 12 than the removal surface end positions P3a, P3b, which are the connection positions between the tip wear surface 12c and the first and second inclined surfaces 12a and 12b.

In this second embodiment, the method of forming the build-up portion 13 is not limited. For example, methods such as laser cladding, PTA (Plasma Transferred Arc Welding) welding, and thermal spraying can be used. The metal to be built-up is also not limited, and may be selected appropriately depending on the application and specifications.

Next, using the punch forming grindstone 5 described with reference to FIG. 2, the padding portion 13 is cut to form a recycled punch top 14 corresponding to the reference cutting edge line LN1a, as shown in FIG. 3F. The punch forming grindstone 5 has a first peripheral convex portion 51 and a second peripheral convex portion 52, as described above. Therefore, a first recess 121 corresponding to the first peripheral convex portion 51 is formed on the first inclined surface 12a of the recycled punch top 14, and a second recess 122 corresponding to the second peripheral convex portion 52 is formed on the second inclined surface 12b.

In this second aspect of the bending die regeneration method, the depth Dp1 of the first recess 121 and the second recess can be determined in the same manner as in the first aspect, depending on the tolerance set for the dimension in the thickness direction (front-back direction in Figure 3F) of the punch die 1.

(Die mold 2)
Next, the procedure for regenerating the die 2 of the second embodiment of the regenerated bending tool K of the present invention by the first embodiment of the regenerating method for a bending tool of the present invention will be described with reference to Figs. 4 to 5D.

As shown in FIG. 4, the die 2 has a die body 21 as a substantially plate-shaped base material A extending up, down, left and right, and a V-groove 22 formed on one edge of the die body 21. The die body 21 is attached to a die holder of a bending machine. In the case of a bending machine in which the die side is fixed and the punch side is raised and lowered, the die 2 comes into contact with the underside of the workpiece W (see FIG. 5A) placed between the punch 1 which rises and lowers above, and the V-groove 22 receives the workpiece pushed down by the descending punch 1, thereby bending the workpiece. In FIG. 5A, to simplify the drawing, the workpiece W is shown in a position spaced above the die 2.

As shown in FIG. 4, the V-groove portion 22 is formed in a V-groove shape having a pair of inclined surfaces tapered downward. The inclined plane on the front side of the V-groove portion 22 is the first groove surface 22a as the first inner surface, and the inclined plane on the rear side is the second groove surface 22b as the second inner surface. In the V-groove portion 22, the first groove surface 22a has a first recess 221 extending in the left-right direction, and the second groove surface 22b has a second recess 222 extending in the left-right direction. The first recess 221 and the second recess 222 are collectively referred to as recess E.

The first groove surface 22a and the second groove surface 22b are ground by the die forming grindstone 6 (see FIG. 5D) to form a predetermined surface. The die forming grindstone 6 will be described later.

The V groove portion 22 worn through use can be regenerated by applying a first aspect of the bending die regeneration method as follows. FIG. 5A shows the V groove portion 22, which is the surface Aa to be regenerated in a worn state. The outermost two-dot chain line is the reference groove line LN2a, which indicates the outer shape of the unused, unworn state. The outer shape in the worn state is indicated by the solid wear groove line LN2b. The two-dot chain removal groove line LN2c indicates the position for removal in the next process. The pair of front and rear removal groove lines LN2c are set below the wear groove line LN2b as straight lines with an inclination angle close to that of the first groove surface 22a and the second groove surface 22b, respectively.

As shown in FIG. 5B, the portion of the V-groove portion 22 in this worn state that is on the tip side (upper side) of the removal groove line LN2c is removed by polishing or the like. The removal is performed over the entire range in the longitudinal direction (left-right direction) of the die 2. As a result, a first removal surface 22ad and a second removal surface 22bd, which are flat surfaces extending back-to-back and left-to-right at the position of the removal groove line LN2c, are formed on the first groove surface 22a and the second groove surface 22b, respectively.

Next, as shown in FIG. 5C, padding portions 23 are formed at both front and rear end portions of the V-groove portion 22. The front padding portion 23 is the first padding portion 23a, and the rear padding portion 23 is the second padding portion 23b. The front first padding portion 23a is formed so as to completely cover the first removal surface 22ad. That is, the padding end position P4a, which is the lower end of the padding, is located closer to the back of the V-groove portion 22 than the removal surface end position P3a, which is the connecting position between the removal surface 2ad and the first groove surface 22a. Similarly, the rear second padding portion 23b is formed so as to completely cover the second removal surface 22bd. That is, the padding end position P4b, which is the lower end of the padding, is located closer to the back of the V-groove portion 22 than the removal surface end position P3b, which is the connecting position between the second removal surface 2bd and the second groove surface 22b. The padding portion 23 is collectively referred to as padding portion B. Additionally, padding end positions P4a and P4b are collectively referred to as end Ba.

The method of depositing the V-groove portion 22 is not limited. For example, methods such as laser cladding, PTA (Plasma Transferred Arc Welding) welding, and thermal spraying can be used. The metal to be deposited is also not limited, and may be a material different from the material of the die body portion 21 of the base material A, and may be selected appropriately depending on the application and specifications.

The amount of removal and the amount of build-up required to obtain the first removal surface 22ad and the second removal surface 22bd may be adjusted as appropriate according to the amount of wear on the first groove surface 22a and the second groove surface 22b of the V-groove portion 22. If the amount of removal is large, the removal surface end positions P3a, P3b will be positioned further downward, and therefore the build-up end positions P4a, P4b must be positioned further downward to cover the first removal surface 22ad and the second removal surface 22bd, requiring a larger amount of build-up.

Next, as shown in FIG. 5D, the die forming grindstone 6 cuts and forms the padding portion 23, forming a regenerated die groove portion 24 corresponding to the reference groove line LN2a. As shown in FIG. 5D and FIG. 6B, the die forming grindstone 6 is a grindstone having a cylindrical or disk-shaped base body 60, and a predetermined grinding portion 6G is formed on the peripheral surface. The predetermined grinding portion 6G has a shape corresponding to the final finished shape of the V-groove portion 22. The die forming grindstone 6 is collectively referred to as grindstone C, and the grinding portion 6G is collectively referred to as grinding portion Ca.

The grinding portion 6G has a first convex inclined grinding wheel surface 6a that forms the first groove surface 22a of the V groove portion 22 and a second convex inclined grinding wheel surface 6b that forms the second groove surface 22b of the V groove portion 22. The first convex inclined grinding wheel surface 6a has a first peripheral convex portion 61 that forms the first recess 221 of the V groove portion 22, and the second convex inclined grinding wheel surface 6b has a second peripheral convex portion 62 that forms the second recess 222 of the V groove portion 22. The first peripheral convex portion 61 and the second peripheral convex portion 62 are convex portions formed over the entire circumference in shapes corresponding to the shapes of the first recess 221 and the second recess 222, respectively. The first peripheral convex portion 61 and the second peripheral convex portion 62 are included in the general term peripheral convex portion Ca1.

The die forming grinding wheel 6 is attached to a grinding machine (not shown) and rotates around the axis CL6 while being pressed against the V-groove portion 22. As a result, the V-groove portion 22 is ground into a shape corresponding to the grinding portion 6G.

By cutting and forming the V-groove portion 22 having the padding portion 23 using this die forming grindstone 6, a first recess 221 corresponding to the first peripheral convex portion 61 is formed on the first groove surface 22a of the regeneration die groove portion 24, and a second recess 222 corresponding to the second peripheral convex portion 62 is formed on the second groove surface 22b.

5D, the first recess 221 is formed by removing a range including the build-up end position P4a on the first groove surface 22a. The second recess 222 is formed by removing a range including the build-up end position P4b on the second groove surface 22b.
The depth Dp2 of the first recess 221 and the second recess 222 is determined according to the tolerance set for the dimension in the thickness direction (front-rear direction in FIG. 5D) of the die 2. For example, if the tolerance for the dimension D2 (see FIG. 4) in the thickness direction is set to "+0 mm to -0.05 mm," the depth Dp2 may be set to a value that exceeds 0.05 mm in theory, but may be set to, for example, 0.1 mm, including a certain degree of margin.

The shapes of the first recess 221 and the second recess 222 are not limited as long as they do not protrude from the first groove surface 22a and the second groove surface 22b, respectively. The shapes of the first recess 221 and the second recess 222 may be concave curved surfaces with a curved cross section, or may include a three-dimensional plane in which a part of the curve of the cross section is a straight line. For example, the first recess 221 may be connected so that its upper and lower ends are clearly bent with the first groove surface 22a. In addition, the first recess 221 may be shaped so that its upper and lower ends are smoothly connected to the first groove surface 22a by rounding, which is desirable from the viewpoint of reducing the effect on the workpiece W during coining. The same applies to the second recess 222.

As described above, the worn V-groove shape is restored by the first aspect of the bending die restoration method, and a die mold 2 having an unused restored die groove portion 24 is obtained.

Whether or not to remove the tip end portion of the V-groove portion 22 may be determined depending on the degree of wear. In other words, when regenerating when the degree of wear is small, the tip end portion may not be removed and the padding portion 23 may be formed, and the V-groove portion 22 may be ground with the die forming grindstone 6 to form it into the standard groove shape, in accordance with the second embodiment of the bending die regeneration method described above.

According to the first and second aspects of the bending die recycling method described above, the area including the end of the padding portion 13, 23 is carved out to form the first recess 121, 221 and the second recess 122, 222, so that no steps are formed at the ends. Therefore, the recycled bending die K has high appearance quality, and when the bending process is so-called coining, there is no risk of a line corresponding to the step being formed on the workpiece W, and the bent workpiece W has high appearance quality.

Each aspect of the present invention is not limited to the configuration and procedures described above, and may be modified without departing from the spirit and scope of the present invention.

The first recesses 121, 221 and the second recesses 122, 222 are formed by carving out the areas that will become the ends of the padding portions 13, 23, respectively, and the depth, formation range, cross-sectional shape, etc. of the carved out areas can be freely set according to the range of the worn areas and the degree of wear.

The punch body 11 and die body 21, which are the base material A, are made of a first metal material, and the padding portions 13 and 23, which are padding portions B, are made of a second metal material. The first and second materials do not have to be the same, and the second material that comes into contact with the workpiece W may be a metal material other than the first material that has better wear resistance or chipping resistance.

Although we have described the restoration of bending dies with worn parts, restoration in this invention is not limited to restoration from wear, but also includes repair of parts damaged by corrosion, overload, etc.

As described above in detail, one aspect of the bending die recycling method of the present invention includes a padding process for forming a padding portion B covering the entire surface Aa to be recycled on a base material A of a recycled bending die K having a surface Aa to be recycled that has a shape different from the reference shape, and a shaping process for rotating a grindstone C having a grinding portion Ca for grinding the padding portion B to shape the padding portion B into the reference shape and regenerate it, the grinding portion Ca of the grindstone C having a peripheral convex portion Ca1 that is carved out to include the external end portion Ba of the padding portion B that connects to the base material A, and the shaping process forms a recess E in the recycled bending die K by the peripheral convex portion Ca1 that includes the external boundary between the base material A and the padding portion B.

As a result, a recess E is formed that includes the boundary between the base material A and the build-up portion B, and no steep step is formed where the build-up portion B protrudes from the surface of the recycled bending die K. Therefore, the recycled bending die K has high appearance quality, and even if the recycled bending process is coining, no lines corresponding to the step are formed on the surface of the workpiece W, and the appearance quality is not reduced.

In addition, in this embodiment, the recycled bending die K is a punch die 1, and the cutting edge of the punch die 1 has a first outer surface 12a and a second outer surface 12b that approach each other toward the tip, and the recess E may be simultaneously formed as a first recess 121 on the first outer surface 12a and a second recess 122 on the second outer surface 12b.

This reduces the time required to regenerate the punch die 1, which is the regenerated bending die K.

In addition, in this embodiment, the recycled bending mold K is a die mold 2 having a V-groove portion 22, and the V-groove portion 22 has a first inner surface 22a and a second inner surface 22b that approach each other toward the back, and the recess E may be simultaneously formed as a first recess 221 on the first inner surface 22a and a second recess 222 on the second inner surface 22b.

This reduces the time required to regenerate the die tool 2, which is the regenerated bending tool K.

In this embodiment, the padding portion B may be formed by layering metal powder.

This makes it possible to weld thin materials and precisely control the thickness of the weld. It also makes the welded surface, which is the layered surface, smooth.

One aspect of the recycled bending die of the present invention is a recycled bending die that includes a first portion MA that is substantially plate-shaped and made of a first material, and has at one edge a cutting edge portion 12 or a V-groove portion 22 whose cross-sectional shape is V-shaped and made up of a first surface and a second surface, and a second portion MB that is provided on the tip side of the cutting edge portion 12 or the V-groove portion 22 and is made of a second material different from the first material, and the first surface and the second surface each have a recess E formed in a range that includes the apparent boundary between the first portion MA and the second portion MB.

As a result, when the first region MA is the base material A and the second region MB is the padded portion B, there is a recess E including the boundary between them, so no steep step is formed where the padded portion B becomes convex from the surface of the recycled bending die K. Therefore, the appearance quality of the recycled bending die K is not degraded, and even if the bending process is coining, no lines corresponding to the step are left on the surface of the workpiece W, so the appearance quality is not degraded.

This embodiment may also be a punch die 1 having a cutting edge portion 12 in the first area MA.

As a result, no steep steps are formed on the surface of the recycled punch die 1 where the padding B becomes convex, and the recycled punch die 1 does not leave lines on the surface of the workpiece W due to the padding B, so the appearance quality of the workpiece W is not reduced.

This embodiment may also be a die mold 2 having a V-groove portion 22 in the first portion MA.

As a result, no steep steps are formed on the surface of the recycled die 2 where the padding B is convex, and the recycled die 2 does not leave lines on the surface of the workpiece W due to the padding B, so the appearance quality of the workpiece W is not reduced.

Reference Signs List 1 punch die 11 punch body 12 cutting edge 12a first inclined surface (first outer surface)
12b Second inclined surface (second outer surface)
12c Tip wear surface (surface to be regenerated)
12d removal surface 121 first recess 122 second recess 13 build-up portion 14 recycled punch top portion 2 die metal mold 21 die main body 22 V-groove portion 22a first groove surface 22ad first removal surface 22b second groove surface 22bd second removal surface 221 first recess 222 second recess 23 build-up portion 23a first build-up portion 23b second build-up portion 24 recycled die groove portion 5 punch forming grindstone 5a first concave inclined grindstone surface 5b second concave inclined grindstone surface 5G grinding portion 50 base 51 first peripheral convex portion 52 second peripheral convex portion 6 die forming grindstone 6a first convex inclined grindstone surface 6b second convex inclined grindstone surface 6G grinding portion 60 base 61 first peripheral convex portion 62 second peripheral convex portion A Base material Aa Surface to be regenerated B Build-up portion C Grinding wheel Ca Grinding portion E Recess CL5, CL6 Axis Dp1, Dp2 Depth D1, D2 Dimension K Regenerated bending tool MA First portion MB Second portion LN1a Reference cutting edge line LN1b Wear cutting edge line LN1c Removal cutting edge line LN2a Reference groove line LN2b Wear groove line LN2c Removal groove line P1a, P1b, P3a, P3b Removal surface end positions P2a, P2b, P4a, P4b Build-up end position W Workpiece

Claims (6)

a padding process for forming a padding portion covering the entire surface to be regenerated on a base material of a bending die having a surface to be regenerated that is different from a reference shape;
a forming step of rotating a grindstone having a grinding portion for grinding the padding portion to form the padding portion into a reference shape and regenerating the padding portion;
Including,
The grinding portion of the grindstone has a peripheral convex portion that is carved out to include an external end portion of the padding portion that is connected to the base material,
The molding step is a method for recycling a bending die, in which a recess is formed in the bending die by the peripheral convex portion, the recess including the appearance boundary between the base material and the build-up portion. The bending die is a punch die, and a cutting edge portion of the punch die has a first outer surface and a second outer surface which approach each other toward a tip end,
The method for regenerating a bending die according to claim 1 , wherein the recesses are simultaneously formed as a first recess in the first outer surface and a second recess in the second outer surface. The bending tool is a die having a V-groove, the V-groove having a first inner surface and a second inner surface which approach each other toward the back,
The method for regenerating a bending die according to claim 1 , wherein the recesses are simultaneously formed as a first recess on the first inner surface and a second recess on the second inner surface. The bending die regeneration method according to any one of claims 1 to 3, in which the build-up portion is formed by layering metal powder. a first portion having a substantially plate-like shape formed from a first material and having a cutting edge portion or a V-groove portion having a V-shaped cross section formed by a first surface and a second surface at one edge;
A second portion is provided on a tip side of the cutting edge portion or the V-groove portion and is made of a second material different from the first material,
the first surface and the second surface each have a recess formed in a range including an apparent boundary between the first region and the second region ,
A recycled bending die which is a punch die having the cutting edge portion at the first portion . a first portion having a substantially plate-like shape formed from a first material and having a cutting edge portion or a V-groove portion having a V-shaped cross section formed by a first surface and a second surface at one edge;
A second portion is provided on a tip side of the cutting edge portion or the V-groove portion and is made of a second material different from the first material,
the first surface and the second surface each have a recess formed in a range including an apparent boundary between the first region and the second region ,
The first portion and the second portion are smoothly connected to each other by rounding.
the second portion is formed of laminated metal powder;
A recycled bending mold which is a die having the V-groove portion in the first portion .

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