JPH01289520A - Method for punching metallic work sheet by press - Google Patents

Abstract

PURPOSE:To prevent scrap from jamming and rising by providing a contraction part bulging to the internal part of a small hole and using a punch having a recess part formed corresponding to the contraction part and a die having a bulging part formed on an internal wall surface corresponding to the contraction part. CONSTITUTION:The recess part 12a corresponding to the shape of the contraction part 10 of a small hole is provided in the punch 12 while the bulging part 14a corresponding to the shape of the contraction part 10 is provided in the die 14. In a punching time by a press, a metallic work sheet is punched by a punch 12 and the scrap having the contraction part is pushed down into the punched hole of the die 14. At this time, the scraps are lowered as their contraction parts are slid along the bulging part 14a of the die 14 and the scraps are prevented from inclining and lowered as they are stacked in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a press punching method for punching small holes in a metal processed plate such as a lead frame.

(Prior Art and its Problems) Some thin metal processed plates for lead frames or various contact parts are provided with various small holes drilled therein. These small holes are usually formed by press punching, but in particular when forming extremely small holes of 1 mm or less, because the hole size is small, the punched scraps generated when drilling the small holes are removed by the die. There are problems such as debris clogging inside and debris floating from the die side to the punch side. There is a problem in that when such debris clogging or debris lifting occurs, the press operation becomes stagnant, resulting in a significant decrease in work efficiency and product yield.

Generally, the shape of a small hole drilled is oval or rectangular as shown in Figure 3, but in the case of a small hole of this shape, there is a problem in which scrap floats up on the punch side and the die dies. A phenomenon called slug clogging, in which scraps get stuck inside, often occurs.

In continuous press punching, the pressed scraps must move down through the die one after another by pushing down the lower scraps that were previously punched out.
Once the scrap gets stuck in the middle of the die,
The scrap that came in from the next one piles up, making it impossible to discharge the scrap, leading to breakage of the punch and damage to the mold.

In addition, when scrap lifting occurs, scraps come out between the upper and lower dies of the punching die, resulting in dents on the product, lowering the yield, and causing damage to the die.

Press punching of lead frames, etc. is performed at extremely high speeds, so if slug clogging or slug buildup occurs, work efficiency and product yield will be significantly reduced, and mold damage will frequently occur. be.

Therefore, the present invention has been made to solve the above-mentioned problems, and its purpose is to enable normal machining without causing scraps or scrap clogging during press punching of small holes, thereby improving work efficiency. The purpose of the present invention is to provide a press punching method for metal working plates that can improve the yield of products.

(Means for Solving the Problems) The present invention has the following configuration to achieve the L-opening objective.

That is, in a press punching method for punching small holes in a thin metal processed plate such as a lead frame.

A constricted portion that bulges inward of the small hole is provided on the circumference of the small hole within an allowable range of product tolerance, and a punch is provided with a concave portion corresponding to the constricted portion, and a bulged portion on an inner wall surface corresponding to the constricted portion. The method is characterized in that a small hole is made using a die in which a small hole is formed.

(Function) By creating a constriction in the small hole formed by press punching, the circumference of the small hole becomes longer, which improves the engagement between the die and the scrap, and eliminates scrap lifting.

Further, the scrap that has been punched out and pushed down into the die descends along the bulge provided on the inner wall surface of the die. The bulge formed on the inner wall surface of the die allows the scrap to fall along the bulge and prevents the scrap from tilting inside the die.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing the shape of a small hole formed in the press punching method for a metal working plate according to the present invention. 1st
Figure 1(a) shows an example in which a constriction 10 is formed on the opposite long side of a conventional oval-shaped small hole, and Fig. 1(b) shows a constriction 10 formed on the long side of a rectangular small hole. Figure 1 (C) shows an example in which a constriction 10 is formed on the short side of a rectangular small hole.
This is an example of forming a .

When drilling a small hole having the constricted portion 10, as shown in FIG. 2, press molding is performed using a punch and die formed in a shape that follows the shape of the small hole to be drilled.

FIG. 2 is an explanatory diagram showing an example of the punch 12 and die 14 used when drilling the small hole shown in FIG. 1(a).
As shown in the figure, the punch 12 is provided with four parts 12a corresponding to the shape of the constriction 10 of the small hole, and the die 14 is provided with a bulge part 14a corresponding to the shape of the constriction 10.

The bulging portions 14a are provided on both opposing inner wall surfaces of the punching hole of the die 14, and are provided along the scrap punching direction.

By using the punch 12 and die 14, a small hole having a constriction 10 as shown in FIG. 1 is punched in the metal work plate. During the press punching process, the metal work plate is punched out by the punch 12, and the scrap having the constriction is pushed down into the punch hole of the die 14. At this time, the scrap descends by sliding the constriction formed on the circumferential surface onto the bulge 14a of the die 14, so even if the scrap tries to tilt, the constriction 10 prevents the bulge 14a from tilting. The bulge part 14 does not tilt when
a acts as a guide when the scraps are normally lowered, and the scraps pushed down into the die 14 descend in parallel stacks. As a result, it is possible to eliminate clogging caused by tilting of scrap inside the die 14.

Furthermore, since the scraps are not tilted within the die 14, it is possible to prevent the top of the piled scraps from floating toward the punch side.

Furthermore, since the circumference of the small hole is longer than the circumference of a conventional small hole, the scrap and die stick together better when punched out, which prevents the scrap L from floating to the punch side. can be prevented.

In addition, since certain product tolerances are set for the small holes during manufacturing, the constricted portion 10 shall be formed within this tolerance range. Since the small hole is quite small in size, by providing the constriction within this tolerance range, it is possible to suitably prevent clogging and lifting of debris.

Further, although the constricted portions 10 shown in FIG. 1 are provided on both opposing sides, they may be formed only on one of the opposing sides depending on the case. Furthermore, by providing constrictions on both the opposing long and short sides, tilting can be further prevented.

It should be noted that when punching a small hole having the shape shown in FIG. 1) or (C), the small hole can be formed by using a punch and die corresponding to the shape of the small hole as described above.

The present invention has been variously explained above using preferred embodiments, but the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

(Effects of the Invention) According to the press punching method of the present invention, it is possible to prevent scrap clogging in which scraps get stuck in the die during press punching of small holes, and scrap lifting in which scraps float to the punch side, resulting in an extremely small size. Even when punching small holes using a press, the press processing can be performed without clogging or lifting of scraps. As a result, the workability of press punching of small holes can be greatly improved, and the yield of products can be improved. Further, since the small holes are formed within the manufacturing tolerance range, the press punching process can be performed normally without affecting the quality of the product, and other remarkable effects are achieved.

[Brief explanation of the drawing]

Figures 1 (a), (bl, and c) are explanatory diagrams showing the shape of small holes formed by the press punching method for metal working plates according to the present invention, and Figure 2 shows the punch and die used in the press punching process. Explanatory drawing, FIG. 3(a), mountain) is an explanatory drawing showing a conventional example of a small hole. 10... Constriction, 12... Punch, 12a...
- Concave portion, 14...Die, 14a...Bulging portion.

Claims (1)

[Claims] 1. In a press punching method for drilling a small hole in a thin metal processing plate such as a lead frame, a constriction that bulges inward within the permissible product tolerance is provided on the periphery of the small hole to accommodate the constriction. 1. A press punching method for a metal working plate, characterized in that a small hole is punched using a punch having a concave portion formed therein and a die having a bulged portion formed on an inner wall surface corresponding to the constricted portion.