JPS624477Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a die for punching plastic discs, etc., and enables highly accurate and efficient punching with an extremely simple structure.

Since the present invention is particularly suitable for punching out flexible magnetic disks, this example will be used for explanation. A flexible magnetic disk is made by applying magnetic paint to both sides of a plastic sheet approximately 0.1 mm thick and punching it out into a circular shape, and a hub may be attached if necessary. An example is shown in FIGS. 1a and 1b, where 1 is a flexible magnetic disk, 2 is a center hole, 3 is an index hole, 4 is a hub fixing hole, 1A is an effective area for recording information, and 1A is an effective area for recording information. As shown in FIG. 1b, a hub 5 is attached to the hub fixing hole 4.

FIG. 2 shows an example of a mold conventionally used to punch out such flexible magnetic disks. Figure 2a shows the upper mold, 6 is a die for punching the outer shape, 7 is a punch for punching a center hole, 8 is a punch for punching a hub fixing hole, 9 is a knockout, and 10 is a moving knockout 8. 11 is a punch plate, 12 is a bucking plate, 13 is a punch holder, and 14 is a bolt for fixing the outer punching die 6 and the punch holder 13. Fig. 2b shows the lower mold, 15 is a punch for punching the outer shape, 16 is a die for punching a center hole, 17 is a die for punching a hub fixing hole, 18
19 is a stripper, 19 is a spring for supporting and moving the stripper 18, and 20 is a die holder. As shown in FIG. 2a, the punches 7 and 8 are positioned and fixed by a punch plate 11. In this case, in order to prevent the punches 7 and 8 from falling off the punch plate 11, it is necessary to enlarge the diameter of their bases into a head shape. Further, when the diameters of the tips of the punches 7 and 8 are relatively small, it is necessary to make the center shaft portions thicker than the tips to reinforce the punches themselves and to ensure that they are fixed by the punch plate 11. As described above, in the conventional mold structure, the diameter of the base must be considerably larger than that of the tip of the punch, and there is a limit to how close the punches can be to each other. For this reason, it is difficult to construct a mold for punching holes in close proximity, and it is often necessary to adopt so-called multi-stage punching, in which punching is performed in two or three stages, and punching accuracy becomes an issue. Ta. Furthermore, the second
Another problem with the upper mold shown in Figure a is that the punch 7
Since the distance between the tip position of punches 7 and 8 and the position where the punch is fixed by the punch plate 11 is large,
8, and because the positioning of the external punching die 6 is performed by a bolt 14 passing through the punch plate 11, it is difficult to achieve relative positional accuracy with the punches 7 and 8. Therefore, punched flexible magnetic disks not only have insufficient punching accuracy and burrs at the cutting part, but also have difficulty adjusting the alignment of the upper and lower molds, causing a lot of wear on the molds themselves, and shortening their lifespans. .
Furthermore, during the punching process of flexible magnetic disks, fine crushed particles of the magnetic film are generated, and it is difficult to completely prevent them from adhering to the mold. If punching is carried out in this state, the pressure of the press will push the crushed powder against the magnetic layer, damaging the magnetic layer, resulting in dropouts, etc., if that part is an effective area where information should be recorded. There was a problem in that it caused an abnormality in the reproduced signal.

The present invention aims to provide a mold which has an extremely sophisticated structure and which solves the above-mentioned problems with a simple structure. a base body made of at least three stages of concentric cylindrical shapes with different diameters; another punch fitted into a hole parallel to the axis of the base body and penetrating the medium diameter portion of the base body; an outer shape punching die fixed in a fitted state with the side surface of the large diameter portion;
In the area surrounded by the die, a knockout is provided in sliding contact with the side surface of the medium diameter part between the large diameter part and the minimum diameter cylindrical part of the base body, and between the large diameter part of the base body and the knockout. An upper mold having an interposed elastic rubber block as a main component and configured such that the surfaces of the main components other than the elastic rubber block with respect to the workpiece are on the same plane when no pressure is applied, and the minimum diameter cylinder on the upper surface. A punch for punching the outer shape, which is provided with a punching die hole corresponding to the part and other punches, and an annular part at the lower end, an elastic rubber block provided on the annular part, and an elastic rubber block provided on the elastic rubber block. a lower die, comprising a stripper that contacts and slides on a side surface of the outer shape punch, and is configured such that the surfaces of the outer shape punch and the stripper with respect to the workpiece are on the same plane when no pressure is applied; and an annular recess is formed in at least one of the lower surface of the knockout and the upper surface of the punch for punching out the outer shape.

The following drawings (Figures 3 to 3) show an example of implementing the present invention.
This will be explained based on FIG. 5). Figure 3 shows the upper mold, 21 indicates multiple stages (at least 3 stages)
a base made of concentric cylinders with different diameters,
Reference numeral 22 is a cylindrical portion with the smallest diameter at the lower end of the base body 21, and serves as a punch for punching a center hole of the flexible magnetic disk. The cylindrical portion 22 is also used as a guide when positioning both the upper and lower molds. Reference numeral 23 denotes a hole that is parallel to the axis of the base body 21 and passes through the medium diameter portion 27 other than the smallest diameter cylindrical portion 22. A punch 24 is provided to fit into this hole 23. That is, the base body 21 also serves as a punch plate. A die 26 for punching out the outer shape is provided so as to fit into the side surface of the large diameter portion 25 at the third stage of the base body 21 . The base body 21 also serves to position the die 26. The large diameter portion 2 of the base body 21
A knockout 28 is provided in a region surrounded by the die 26 and in sliding contact with the side surface of the medium diameter portion 27 between the cylindrical portion 27 and the cylindrical portion 22 . That is, the base body 21 also serves as a guide when positioning and moving the knockout 28. 29 is knocked out 28
An annular depression is formed on the lower surface of the flexible magnetic disk, and the area of the depression 29 is opposite to the effective area where information is recorded on the flexible magnetic disk. The knockout 28 is also limited in its movement by a bend 30 at the lower end of the die 26 to prevent it from falling off. An elastic rubber block 31 is provided between the large diameter portion 25 of the base body 21 and the knockout 28, and moves the knockout 28 up and down in accordance with the press cycle. A bucking plate 32 is provided on the upper surface of the base body 21, and the base body 21, die 26, and bucking plate 32 are connected to a punch holder 33 by bolts 34.
are integrally combined with.

FIG. 4 shows the lower mold, and 35 is a punch for punching the outer shape, and in the center of the upper surface there are a center hole, an index hole, and a hub corresponding to the cylindrical part 22 and punch 24 of the upper mold. Die holes 36 and 37 for punching fixing holes are provided. 3
Reference numeral 8 denotes an annular recess provided on the upper surface of the outer shape punch 35 at a position opposite to the effective information recording area of the flexible magnetic disk. An annular portion 39 is formed at the lower end of the punch 35 for punching out the outer shape. A stripper 40 is provided in sliding contact with the side surface of the punch 35 for punching out the outer shape. An elastic rubber block 41 is provided between the stripper 40 and the annular portion 39, and moves the stripper 40 up and down in accordance with the press cycle. The punch 35 for punching out the outer shape presses the bolt 42 at the annular portion 39.
It is integrally connected to the die holder 43 by.

Next, the punching process will be explained with reference to FIG. A shows the initial state, and a magnetic sheet 44 to be punched is placed between the upper and lower molds. At this time, the surfaces of the upper and lower molds facing the magnetic sheet 44 are flush with each other. b shows a state in which punching has been performed, and the magnetic sheet 44 is firmly sandwiched between the die 26 and the stripper 40 and between the knockout 28 and the punch 35, and in this state, the elastic rubber blocks 31, 41 are pressed. Punching is performed by shearing force generated by shrinkage and accompanying movement of knockout 28 and stripper 40. As a result, the magnetic sheet 44 is blank 45, remaining sheet 46,
Divided into 47 scraps. c shows a state in which punching is completed and the pressure is removed, and the contracted elastic rubber blocks 31 and 41 return to their original states, and the knockout 28 and stripper 40 are pushed back to their initial states, leaving the blank 45 uncut. sheet 46
be inserted again into the However, the punched scraps 47 remain in the die holes 36, 37, accumulate as punching continues, and are successively pushed downward and discharged. d shows a state in which the magnetic sheet 44 has moved to the left for the next punching.

As described in the embodiments above, the base body 21 of a special shape is provided in the upper mold, and the cylindrical part 2 at the lower end of the base body 21 is provided.
By using 2 as a punch for punching center holes, there is no longer a head-shaped base or a thick center shaft like in the conventional punch for punching center holes shown in FIG. Not only can the center hole punch be provided with a punch plate, but also a punch plate for fixing the punch for center hole punching becomes unnecessary. Therefore, the positional accuracy of the center hole punching punch becomes extremely high, so that the relative positional accuracy with other punches and dies can be improved based on this. Also, another punch 24 shown in FIG.
Since the punch is fitted into the hole 23 of the base body 21, a sufficient reinforcing effect can be provided even with a thin punch. Therefore, unlike conventional punches, there is no need to thicken the center shaft portion for reinforcement, and this is also the reason why the other punch 24 can be placed very close to the cylindrical portion 22 serving as the punch for punching the center hole. ing.

Further, since the punch 24 has a simple shape, machining becomes easy. Next, by providing the die 26 for punching the outer shape so as to fit with the side surface of the large diameter portion 25 of the base body 21, the relative position of the die 26 and the cylindrical portion 22 and the punch 24 as the punch for punching the center hole is adjusted. It is possible to make the relationship extremely accurate.

When punching flexible magnetic disks,
The magnetic sheet 44 is inserted into the outer shape punching die 2 as described above.
6 and the stripper 40 and the punch 3 for punching the outer shape.
In this case, the knockout 28 and the stripper 40 are in sliding contact with the side surfaces of a very tight member such as the base body 21 and the punch 35 for punching out the outer shape, respectively. Since the punch moves with a cylindrical shape, high precision can be maintained, and high precision punching can be performed using a simple cylindrical punch. Furthermore, since each member has a simple shape, it has a long life, can be processed at low cost, and is extremely easy to assemble and repolish. Further, on the surface facing the effective area of the flexible magnetic disk, annular depressions 29 and 38 are provided in the knockout 28 and the punch 35 for punching out the outer shape, so that no pressure is applied to the effective area during pressing. First, even if crushed powder of the magnetic film, base film, etc. generated during the punching process adheres to the mold surface, problems such as damage to the magnetic film will not occur. The recesses 29 and 38 may be formed only in either the knockout 28 or the punch 35 for punching out the outer shape.

It goes without saying that each part may be divided or integrated for processing reasons, and the packing plate 32, etc. may be omitted when using a die set, etc., but in both cases the present invention does not apply. It is clear that this does not change the intention.

By the way, as the material for the elastic rubber blocks 31 and 41, a material such as urethane rubber that is strong, has high elasticity, and has little change over time is suitable. Although it is possible to use a spring or the like, an elastic rubber block is better.

As mentioned above, this invention has a simple structure that has good sharpness, precision, and durability, and can prevent damage to the product by making extremely effective use of each basic part with a distinctive shape and by selecting the shape of the knock-out. The purpose of the present invention is to provide a mold that is free from the risk of damage, and thereby enables continuous high-speed punching of flexible magnetic disks with high quality and good yield.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the flexible magnetic disk, a shows the state before the hub is attached, b shows the state when the hub is attached, Fig. 2 a is a cross-sectional view of the conventional upper mold, and b is a cross-sectional view of the lower mold. Figures 3 to 5 show an example of the implementation of the present invention, in which Figure 3a is a cross-sectional view of the upper mold, b is a bottom view thereof, Figure 4a is a cross-sectional view of the lower mold, and b is the same plan view, and FIGS. 5a to 5d are explanatory diagrams of the punching process. 21... Base body, 22... Cylindrical part, 23... Hole,
24...Punch, 25...Large diameter part, 26...Outer punching die, 27...Medium diameter part, 28...Knockout, 29...Indentation, 30...Bending part, 31...
...Elastic rubber block, 32...Bucking plate, 33...Punch holder, 34...Bolt,
35... External punch for punching, 36, 37... Die hole, 38... Hollow, 39... Annular part, 40...
Stripper, 41...Elastic rubber block, 42...
... Bolt, 43 ... Die holder, 44 ... Magnetic sheet, 45 ... Blank, 46 ... Remaining sheet, 47 ... Scraps.

Claims (1)

[Scope of utility model registration request] a base made in the shape of a circular cylinder with at least three stages of different diameters, the minimum diameter cylindrical part at the lower end being used as a punch for punching the center hole, and a medium diameter part of the base parallel to the axis of the base another punch that fits into the hole penetrating the base body, a die for punching the outer shape fixed in a state where it is fitted with the side surface of the large diameter part of the base body, and a die for punching the outside shape that is fixed in a state that is fitted to the side surface of the large diameter part of the base body in the area surrounded by this die. The main parts are a knockout provided in sliding contact with the side surface of the medium diameter part between the part and the minimum diameter cylindrical part, and an elastic rubber block interposed between the large diameter part of the base body and the knockout. An upper mold configured so that the surfaces of the main parts other than the rubber block with respect to the workpiece are on the same plane when no pressure is applied, and a punching die hole corresponding to the minimum diameter cylindrical part and other punches on the upper surface. and an annular portion at the lower end; an elastic rubber block provided on the annular portion; and a stripper that contacts the elastic rubber block and slides against the side surface of the outer shape punch. and a lower mold configured such that the outer shape punch and the surface of the stripper facing the workpiece are on the same plane when no pressure is applied,
A punching die having an annular recess formed in at least one of the lower surface of the knockout and the upper surface of the outer shape punch.