JP2003145298A - Punch for die, structure and method for centering die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a punch for a die which has a prolonged service life, and by which vibration transmission to the powder by a vibration means is improved while suppressing the occurrence of an extremely large burr caused by the deviation of a clearance by fixing the clearance of the punch for the die, and also to provide a structure and a method for centering the die. SOLUTION: The structure has the die 14 provided with a through-hole 12, the punch with a tip part 24, and a hydraulic jack 20 that fixes the punch and enables the loading and unloading of the tip part 24 into and from the through-hole 12. A positioning part 26 for centering the tip part 24 by fitting with the through-hole 12 is formed at the rear end side from the tip part 24 of the punch, and the moving range of the hydraulic jack 20 is set so that the positioning part 26 reaches the through-hole 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die punch, a die centering structure, and a centering method, and in particular, centering can be performed by fitting the punch into a die without using a jig. The present invention relates to a die punch, a die centering structure, and a centering method.

[0002]

2. Description of the Related Art Heretofore, there has been known a means for pressurizing powder made of ferrite or ceramics with a mold to form the powder.

FIG. 7 is a schematic sectional view showing a conventional mold structure. As shown in the figure, in the conventional mold, the die 1 is fixed to a pedestal (not shown), and the die 1 is formed with a through hole 2 corresponding to the outer shape of the molded product. Above and below the die 1, an upper punch 3 and a lower punch 4 which are engaged with the through holes 2 are arranged, and these upper punch 3 and lower punch 4 are arranged by an elevating means (not shown).
The lower punch 4 can be inserted into the through hole 2 individually.

In the die thus constructed, after the powder is supplied into the through hole 2, the powder is sandwiched between the upper punch 3 and the lower punch 4 in the die 1, and this is pressed. Then, the powder is molded.

By the way, in the above-mentioned mold, since the upper punch 3 and the lower punch 4 are worn out as the number of molding times increases, the upper punch 3 and the lower punch 4 are regularly replaced.

That is, when the number of molding times of the die reaches a preset number, the worn punch is removed from the elevating means, and then a new punch is temporarily fixed to the elevating means. Then, after the new punch is temporarily fixed, the new punch is fitted into the through hole 2 in the die 1, the clearance is measured by a measure or the like, and the new punch is centered by hitting with a tool. After the centering of the new punch is completed, the new punch is fixed to the elevating means by the additional tightening of the punch tightening bolt, and the punch replacement work is completed.

The punch is attached to the lifting means not only by tightening the punch tightening bolts, but also by simultaneously clamping the die with a plurality of clamp levers as described in, for example, Utility Model Registration No. 3058379. What to wear is also known.

The method of centering the punch with respect to the die is not limited to the measurement of the clearance with a measure and the tapping with a tool. For example, as described in JP-A-10-118798, Attach the centering jig to the die plate during mold assembly,
It is also known to perform punch centering with this centering jig.

[0009]

However, the above-described centering method for the mold has the following problems. In other words, the punch centering method that uses a measure and a tool requires skill such as the force of tapping, and also requires a large amount of adjustment time. Further, even if such a method is used, centering can be performed accurately. There was a problem that it was difficult.

When the punch is misaligned with respect to the die (when the clearance between the inner wall of the through hole in the die and the punch is deviated), a large amount of powder enters the side with a large clearance during molding. result,
As shown in FIG. 8, a large burr 6 may occur on the molded product 5. And a large burr 5 on the molded product like this
When this occurs, there is a problem that it becomes difficult to remove the burr 5.

If the punch is in contact with the inner wall surface of the through hole due to misalignment in the centering, the tip of the punch comes into contact with the opening edge of the through hole when the punch is taken in and out of the die, Chipping (so-called chipping) may occur. For this reason, it is necessary to take measures such as using a material having a high bending resistance and a low hardness as the punch material, and there is a fear that the number of times the punch is replaced increases due to wear.

Exciting means may be connected to the die or punch for the purpose of uniformly smoothing the powder supplied into the through hole (prevention of deviation), but the punch contacts the inner wall surface of the through hole. If so, the vibration from the vibrating means is attenuated by the contact between the two, the vibration is not sufficiently transmitted to the powder in the through hole, it may not be possible to even the powder in the through hole. there were.

These problems become more remarkable in a multi-cavity mold. That is, as shown in FIG. 9, since the punch 7 corresponding to the multi-cavity production is usually integrally formed, when the pitch between the punches and the pitch of the through holes 9 formed in the die 8 are different from each other, This is because it becomes difficult to perform centering work on all punches 7 as shown in the figure.

By the way, as described above, when attaching the punch to the elevating means, it is known that the die is fastened at the same time by a plurality of clamp levers. However, the same method facilitates the attachment of the die. Yes, it was not intended to perform centering reliably. Further, in the method of performing the centering of the punch by the jig, it is necessary to separately attach the centering jig to the die plate, and it takes a lot of time to attach and detach the jig.

In view of the above-mentioned conventional problems, the present invention forms a positioning portion on the punch and performs die matching with the die by the positioning portion, so that the clearance of the punch with respect to the die is constant and the clearance is offset. The purpose of the present invention is to suppress the occurrence of maximum burrs caused by the above, to prolong the life of the punch, and to improve the vibration transmission to the powder by the vibrating means.

[0016]

According to the present invention, when a positioning portion is formed on the rear end side of a punch, the positioning portion is fitted into the through hole of the die, whereby the punch can be centered. It was made based on the knowledge.

That is, the die punch according to the present invention is a die punch in which a tip portion to be inserted is formed in a hole provided in a die, and the die punch is fitted into the hole to form a hole in the hole. On the other hand, the positioning portion for centering the tip portion is formed on the rear side of the tip portion of the punch.

Further, in the centering structure of the die according to the present invention, a die having a hole portion, a punch having a tip portion having a shape corresponding to the hole portion, and fixing to the punch is provided. A centering structure of a mold having a lifting means for allowing the tip part to be taken in and out of the hole part, and positioning for centering the tip part with respect to the hole part by fitting with the hole part. The part is formed on the rear end side of the front end of the punch, and the moving range of the elevating means is set at least until the positioning part reaches the hole.

The positioning portion is composed of a minimum sliding surface that regulates at least the tip end portion in the centering direction, or the die is provided with a plurality of hole portions, and the punch and the elevating means are provided. A fixing plate that allows a plurality of punches to be attached between the punch and the fixing plate, and a slide portion that moves in the centering direction between the punch and the fixing plate, and the punch is attached to the fixing plate. You may make it provide the fixing means for this.

The die centering method according to the present invention is a die centering method for centering a punch on a die, which is formed on a rear end side of a front end portion of the punch. The positioning portion for centering the part is inserted into the hole formed in the die, the tip portion is centered with respect to the hole, and the relative position of the punch with respect to the die is fixed.

According to the above construction, the punch is provided with the tip portion for pressing or punching and the positioning portion.

Here, the positioning portion is set to a size such that it fits into the hole portion with a minimum clearance, and when the positioning portion is fitted into the hole portion, the clearance around the tip end portion fits into the hole portion. It is set to be even. Therefore, when centering the die, first, the punch is moved by the elevating means until the positioning portion is fitted in the hole. When the positioning part is fitted in the hole, the tip part is centered with respect to the hole by this fitting operation, so if the punch is fixed to the elevating means while maintaining the same state, the punch will be evenly distributed around the tip part. Clear clearance can be formed.

By forming a uniform clearance around the tip portion, it is possible to prevent the maximum burr from being generated due to the deviation of the clearance, and to open the hole portion when the tip portion is taken in and out of the hole portion. It is possible to prevent the tip from contacting the edge. Therefore, the problem of chipping is solved, the number of maintenance can be reduced by using a material of high hardness for the punch, and the vibration from the vibrating means is sufficiently transmitted to the powder in the die, and It is also possible to prevent the powder from being offset.

Further, when the hole has a complicated shape, the positioning portion does not necessarily have to have the same shape as the hole, as long as the tip portion is constituted by a sliding surface capable of centering in the hole. Well, for this reason, the positioning portion can be configured in a simple shape.

Further, when a plurality of punches are attached using the fixing plate, a slide portion is formed between the punches and the fixing plate. Therefore, at the time of centering, the slide portion allows the fixing plate and the fixing plate to be fixed. The position of the punch may be fitted into the hole while maintaining the posture described above. By thus moving the individual punches along the fixing plate using the slide portion, it becomes possible to perform centering on the individual punches even if a plurality of punches are attached. Then, after centering the individual punches, if the punches are fixed to the fixing plate by using the mounting means, it is possible to manufacture uniform molded products in which all burrs do not occur. .

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments suitable for a die punch, a die centering structure and a centering method according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a die to which a die centering structure according to the present embodiment is applied, and FIG. 2 is an explanatory view showing a shape of a punch used in the die of FIG. The figure (1) shows a front view, and the figure (2) shows a bottom view.

As shown in these figures, a die 10 for powder molding to which the die centering structure according to the present embodiment is applied.
Is a through hole 1 which is a hole having a shape similar to that of the product.
The die 14 in which 2 is formed, the upper punch 16 and the lower punch 18 arranged above and below the die 14, and an elevating means for fixing the punches to and taking them out of the die 14. It has a hydraulic jack 20 and a hydraulic jack 22.

Although not shown, powder supply means is provided near the upper opening edge of the through hole 12 in the die 14, and vibration means is further provided in the die 14, the upper punch 16 and the lower punch 18. Connected (both not shown). Therefore, after the powder serving as the molding material is supplied into the through hole 12 by the powder and granular material supply means,
The powder is vibrated by operating the vibrating means to prevent the powder from being offset in the through hole 12.

In the upper punch 16 constituting the die 10,
A leading end portion 24 serving as a punch effective portion is formed at the leading end thereof, while a positioning portion 26 for centering is formed at the rear end of the upper punch 16. A connecting portion 28 is provided between the tip portion 24 and the positioning portion 26.
The connecting portion 28 connects the tip portion 24 and the positioning portion 26, and the outer diameter of the connecting portion 28 is set to be thinner than the tip portion 24 and the positioning portion 26.
When the upper punch 16 is inserted into the through hole 12, the connecting portion 2
8 does not interfere with the inner wall of the through hole 12.

In the present embodiment, the upper punch 16 is described as an integral shape, but the present invention is not limited to this, and for example, the tip portion 24, the positioning portion 26, and the connecting portion 28 are all separate bodies. Alternatively, one of the tip portion 24 and the positioning portion 26 and the connecting portion 28 may be integrally formed.

The end face of the tip portion 24 that applies pressure to the powder has a shape in which the edge of the through hole 12 is offset inward by a certain dimension. Therefore, the tip 2
When 4 is inserted into the through hole 12, a certain clearance is generated between the through hole 12 and the tip portion 24, and the tip portion 2
4 does not interfere with the inner wall surface of the through hole 12. The clearance may be set to an optimum value in consideration of the properties of the raw material powder, the pressing force of the punch, the thickness of the product, and the like.

On the other hand, the end face shape of the positioning portion 26 formed at the rear end of the upper punch 16 is such that the end face of the tip end portion 24 is offset outward by a certain dimension. Here, the amount of offset with respect to the end face shape of the tip portion 24 is set to the minimum dimension that allows fitting into the through hole 12, and therefore, when the positioning portion 26 is inserted into the through hole 12. The movement of the through hole 12 in the radial direction (XY direction 58 described later) is restricted, and the restriction allows the tip portion 24 to be centered with respect to the through hole 12.

A fixing flange 30 is formed at the end of the positioning portion 26. Then, if the fixing flange 30 is brought into close contact with the mounting surface 32 of the hydraulic jack 20 and the fixing flange 30 is sandwiched by a tightening bolt or the like (not shown), the upper punch 16 is fixed to the hydraulic jack 20 via the fixing flange 30. It can be attached to.

The hydraulic jack 20 which is fixed to the upper punch 16 can be moved up and down by introducing hydraulic pressure from a hydraulic pressure supply source (not shown). The stroke range of the upper punch 16 extends from the through-hole 12 until the tip portion 24 of the upper punch 16 is pulled out at least at the rising time, while the positioning portion 26 of the upper punch 16 fits into the through-hole 12 at the lowering time. Set by the time.

By the way, the lower punch 18 and the hydraulic jack 22 arranged below the die 14 so as to face the upper punch 16 have the same shapes as the upper punch 16 and the hydraulic jack 20 described above, and therefore the description thereof will be given here. Is omitted.

Using the mold 10 thus constructed,
The operation of centering the upper punch 16 will be described below.
FIG. 3 is a cross-sectional view showing a procedure of centering work of the upper punch. The punch used in the mold 10 is worn out as the number of moldings increases, and therefore needs to be replaced regularly.

When centering a new upper punch 16, first, the upper punch 16 is temporarily fixed to the hydraulic jack 20 above the die 14, and the upper punch 16 slides in the sliding direction of the mounting surface 32 of the hydraulic jack 20. To be able to move to. Then, from this state, the hydraulic jack 20
While lowering the upper punch 16 to finely adjust the upper punch 16 in the sliding direction, the positioning portion 26 of the upper punch 16 is fitted into the through hole 12 as shown in FIG.

When the positioning portion 26 is fitted into the through hole 12 in this manner, there is almost no clearance between the through hole 12 and the positioning portion 26, so that the upper punch 16 moves in the centering direction (diameter of the through hole 12). Direction). In this state, due to the positional relationship between the positioning portion 26 and the tip portion 24, the clearances around the tip portion 24 are all equal (A dimension and B dimension in the figure are equal), and the through hole 12 is formed.
The center of the tip portion 24 is performed with respect to. Then, after centering the tip portion 24 with respect to the through hole 12, the upper punch 16 is permanently fixed to the hydraulic jack 20, and the positioning portion 26 is pulled out from the through hole 12 to complete the centering operation.

After the centering work is completed for the through hole 12 as described above, as shown in FIG.
The hydraulic jack 20 may be operated so as to move the tip end portion 24 in and out of the 2, and the molding operation may be performed.

Since the tip portion 24 of the upper punch 16 is centered by fitting the positioning portion 26 into the through hole 12, the tip portion 24 may interfere with the inner wall surface of the through hole 12. Absent. Therefore, the vibration from the vibrating means attached to the die 14 or the upper and lower punches is sufficiently transmitted to the powder put into the through hole 12, and the powder does not deviate in the through hole 12 and It is possible to apply an even force to.

Further, since the clearance around the tip portion 24 is made uniform, it is possible to prevent a large amount of powder from entering the large clearance side and locally generating large burrs which are difficult to remove. That is, FIG. 4 is a perspective view showing a molded product manufactured by this mold, but as shown in FIG. 4, burrs 36 of the same degree are formed at the peripheral edge of the molded product 34. Therefore, it becomes possible to easily remove the burr over the peripheral portion under substantially the same conditions.

The inventor conducted various experiments and examinations according to the present invention to verify the state of burrs with respect to the amount of clearance. The outer diameter of the molded product is 5 mm (φ
In the general ferrite powder compacting die set in 5), the difference in outer diameter between the die hole and the tip of the punch is usually set to 10 to 30 μm. When the conventional centering method was used, the punch had a maximum deviation of about 20 μm. However, when the punch according to the present embodiment is used, by inserting the positioning portion of the punch into the hole, it becomes possible to set a uniform clearance of 10 μm around the tip portion, and the centering work can be performed. It has been confirmed that this will be done reliably.

Further, the inventor also verified the height of burrs by using a dental impression material. According to the same verification by the inventor, it was confirmed that the height of the burr generated in the actual molded product can be suppressed from 100 μm to 40 μm by making the clearance around the tip of the punch uniform.

Further, since there is no possibility that the punch will come into contact with the inner wall surface of the through hole due to the misalignment in the centering, the material of the punch can be changed from a material with high bending resistance and low hardness to a material with high hardness. For this reason, it becomes possible to suppress wear of the punch, and it is possible to reduce the number of times of exchanging the punch.

In the above description, the centering method of the upper punch 16 has been described, but the same method may be applied to the lower punch 18 and the centering work may be performed. Therefore, the description thereof will be given here. Omit it.

FIG. 5 is a cross-sectional structural view when the centering structure of a mold according to this embodiment is applied to a multiple-cavity mold. The die also has an upper punch and a lower punch for a single die, but since the upper and lower punches have the same structure, the lower punch and its The description is omitted.

As shown in the figure, the multi-cavity mold 38 to which the centering structure of the mold is applied has a die 42 having a plurality of through holes 12 and a plurality of dies 42 corresponding to the through holes 12. An upper punch 16 is provided. A fixing plate 40 is provided at the rear end of the upper punch 16 so that the plurality of upper punches 16 can be integrated.

The surface of the fixing plate 40 is finished flat so that it can be brought into close contact with the fixing flange 30 of the upper punch 16, and at the same time, the fixing flange 30.
The axis of the upper punch 16 is set to be parallel to the axis of the through hole 12 when they are brought into close contact with each other. Further, the slide portion 4 is provided between the mounting surface 42 and the fixing flange 30.
No. 4 is configured, and while the fixing flange 30 is closely attached to the mounting surface 42, by sliding (sliding) on the mounting surface 42, the upper punch 16 is maintained while maintaining the posture thereof. 16 can be moved.

Fixing means 46 is provided between the fixing plate 40 and the fixing flange 30. The fixing means 46 is for fixing the upper punch 16 to the fixing plate 40, and the structure thereof is such that the fixing flange 30 is sandwiched by a not-illustrated tightening bolt or the like, as described above. Alternatively, as shown in FIG. 5, a screw portion 48 is provided on the fixing flange 30 side, and the upper punch 16 is fixed from the rear side of the fixing plate 40 with a tightening bolt 50. May be.

As described above, if the slide portion 44 and the fixing means 46 are provided between the fixing plate 40 and the fixing flange 30, the upper punch 16 is individually centered with respect to the through hole 12. You can do it.

That is, when performing centering, first, an arbitrary upper punch 16 is temporarily fixed so as to be movable on the mounting surface 42. Then, the hydraulic jack is lowered from this state, and immediately before the positioning portion 26 approaches the through hole 12, the upper punch 16 is slid on the mounting surface 42, and the positioning portion 26 is positioned so as to be fitted into the through hole 12. To do. Then, after fitting the positioning portion 26 into the through hole 12, the centering work can be completed by changing the upper punch 16 from the temporarily fixed state to the fully fixed state by the fixing means 46.

By performing this operation for each upper punch 16, even when a plurality of upper punches 16 are provided, centering can be performed individually.

In the present embodiment, the punch and the through hole are described as an example having a simple shape, but the present invention is not limited to this, and the core of the die according to the present embodiment is not limited to this. The projecting structure can be applied to a complicated shape.

FIG. 6 is an explanatory view showing a punch having an H-shaped cross section according to this embodiment, and FIG. 6 (1) is a front view.
The figure (2) shows a bottom view.

As shown in these figures, in the punch 52 having a complicated shape, the positioning portion 54 does not necessarily have to be similar in shape to the tip portion 56, and the tip portion 5 is not necessarily the same.
It suffices that 6 is constituted by a sliding surface that can be centered within the through hole. That is, as shown in FIG. 2B, the surface that can regulate the XY directions 58 in the drawing that is the centering direction only needs to be configured as the positioning portion 54. Therefore, in the punch 52, the recess 60 is formed in the drawing. It is not necessary to provide a step forming the positioning portion 54, and the A surface, B surface, C surface, D
Only the surface may be set as the positioning portion 54.

As described above, the positioning portion 54 has the tip portion 56.
Since it suffices to regulate the centering direction of, the shape does not necessarily have to be the same as the tip portion 56, and the shape can be simplified.

In the die punch according to this embodiment, the step between the tip portion and the positioning portion is usually formed by machining such as cutting, but the machining method is not limited to this. However, for example, if the punch shape is all formed to be the same as the tip portion, then only the positioning portion is plated, and the step between the tip portion and the positioning portion is formed by the thickness of the plating layer. Good. By using the plating process in this way, the plating layer can be formed uniformly on the surface even if it has a complicated shape, so the positioning part can be easily formed without complicated machining, and further The film thickness can be easily controlled by adjusting the time. When punching into the plating layer, other portions such as the tip may be covered with a masking tape or the like so that only the positioning portion is immersed in the plating liquid.

Further, since metal is usually used as the punch material, an efficient electrolytic plating method can be applied. As the type of plating to be applied, for example, hard chrome plating or nickel plating having excellent wear resistance may be used.

Further, if the electroless plating method is applied, a power source for the plating process becomes unnecessary and a plating layer (coating) having a more uniform film thickness is formed. The accuracy can be further improved.

The inventor conducted an experiment of forming a plating layer on the surface of a mold using electroless nickel plating.
In the same experiment, it was confirmed that the plating layer was uniformly formed even on the corner portion of the die, and the punch fit was improved.

[0062]

As described above, according to the present invention, there is provided a die punch in which a tip part for insertion is formed in a hole provided in a die, and the hole is formed by fitting the hole into the hole. Positioning part for centering the tip part with respect to the part is formed on the rear end side of the tip part of the punch, or a die having a hole part and a shape corresponding to the hole part are formed on the tip part. Centering structure of a die having a punch that is fixed to the punch, and an elevating means that is fixed to the punch and that allows the tip to be taken in and out of the hole. A positioning portion for centering the tip portion with respect to the hole portion is formed on a rear end side of the tip portion of the punch, and a moving range of the elevating means is set at least until the positioning portion reaches the hole portion. Further, the punch is centered with respect to the die. A method of centering a die, wherein a positioning portion which is formed on the rear end side of the front end portion of the punch to center the front end portion is inserted into a hole portion formed in the die, and the hole portion is formed. After the centering of the tip end portion with respect to the die and fixing the relative position of the punch with respect to the die, the positioning portion is pulled out from the hole portion. It is possible to control the width and height of the generated burr while suppressing the occurrence of maximum burr caused by the deviation, and to extend the punch life and
It is possible to improve the vibration transmission to the powder by the vibrating means.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold to which a mold centering structure according to the present embodiment is applied.

FIG. 2 (1) is a front view showing the shape of a punch used in the mold of FIG. (2) is a bottom view showing the shape of a punch used in the mold of FIG. 1.

3 (1) and (2) are cross-sectional views showing the procedure of centering work of the upper punch.

FIG. 4 is a perspective view showing a molded product manufactured by this mold.

FIG. 5 is a cross-sectional structural view when the centering structure of a mold according to the present embodiment is applied to a multiple-cavity mold.

FIG. 6 (1) is a front view showing a punch having an H-shaped cross section according to the present embodiment. (2) is a bottom view showing a punch having an H-shaped cross section according to the present embodiment.

FIG. 7 is a schematic cross-sectional view showing a conventional mold structure.

FIG. 8 is a perspective view showing a molded product manufactured by a conventional mold.

FIG. 9 is an explanatory view showing the structure of a multi-cavity mold.

[Explanation of symbols]

1 ... Dice 2 ... through hole 3 ……… Punch on top 4 ... Bottom punch 5 ………… Molded product 6 ... Bali 7 ... Punch 8 ……… Dice 9 ... through-hole 10 ... Mold 12 ... through-hole 14 ……… Dice 16 ………… Upper punch 18 …… ... Lower punch 20 ... Hydraulic jack 22 ... Hydraulic jack 24 ………… Tip 26 ………… Positioning unit 28 ......... Connecting part 30 ......... Flange for fixing 32 ......... Mounting surface 34 ... Molded products 36 ... Bali 38 ………… Multi-cavity mold 40 ......... Fixing plate 42 ......... Mounting surface 44 ………… Slide part 46 .... Fixing means 48 ......... Screw part 50 ......... tightening bolts 52 ... Punch 54 ... Positioning unit 56 ......... Tip 58 ......... XY direction 60 ……… Concave

Claims (5)

[Claims] 1. A punch for a metal mold, wherein a tip portion for insertion is formed in a hole portion provided in a die, and the tip portion is centered with respect to the hole portion by fitting with the hole portion. A die punch, wherein a positioning portion is formed on the rear end side of the front end portion of the punch. 2. A die having a hole, a punch having a shape corresponding to the hole formed at the tip, and a die fixed to the punch so that the tip can be taken in and out of the hole. A centering structure of a die having a raising and lowering means, wherein a positioning portion for centering the tip portion with respect to the hole portion by fitting with the hole portion is provided on the rear end side of the punch tip portion. And a moving range of the elevating means is set at least until the positioning section reaches the hole section. 3. The centering structure for a mold according to claim 2, wherein the positioning portion is composed of at least a minimum sliding surface that regulates a centering direction at the tip portion. 4. The die is provided with a plurality of the holes, and a fixing plate is provided between the punch and the elevating means so that the plurality of punches can be attached, and the punch and the fixing plate are connected to each other. The mold centering structure according to claim 2, further comprising: a slide part that moves in a centering direction and a fixing means for mounting the punch to the fixing plate. 5. A die centering method for centering a punch with respect to a die, comprising a positioning portion formed on a rear end side of a front end portion of the punch and for centering the front end portion. A method for centering a die, which comprises inserting the hole into a hole formed in, centering the tip with respect to the hole, and fixing a relative position of the punch with respect to the die.