JPH044932A - Structure of hole for fixing screw of metallic base board and its working method - Google Patents

Abstract

PURPOSE:To disperse the flow of material at the time of plastic working to prevent insulating material from peeling by providing parts enlarged partially in the radial direction on the prepared hole in a countersink by plastic working on the other surface of the metallic base plate on which an insulating material and a conductor pattern at least on one surface of a metallic plate. CONSTITUTION:A metallic base plate 1 on which a laminated board 3 and the conductor pattern 4 as insulating material are laminated at least on one surface 2a of the metallic plate 2 is mounted on a die 6 and punched by pressing down a spline-shaped punch 5. A prepared hole 7 punched by a punch 5 has parts 7a punched by the cylindrical surface of the punch 5 and magnified parts 8 punched by projecting parts 5a. Then, a circular punch 12 having a tapered surface on the side of a rear 2b of the metallic plate 2 opposite to the side of the laminated plate 3 of the metallic base plate 1 is pressed coaxially to the prepared hole 7 and a countersink part 9 is formed by plastic working. At this time, since the flow of the material is escaped to the magnified parts 8, dispersed in the peripheral direction and in the radial direction and a load put on the rear 2b of the metallic plate 2 is dispersed and the laminated plate 3 can be prevented from separating.

Description

[Detailed Description of the Invention] [Objective of the Invention] <Industrial Application Field> The present invention relates to a structure of a hole for a fixing screw in a metal substrate having a conductor pattern and a method for processing the same, and in particular, The present invention relates to a structure of a hole for a fixing screw in a metal substrate provided with a countersunk hole in order to minimize the amount of protrusion of the head of the fixing screw, and a method for processing the same.

<Prior Art> Generally, there is a metal substrate in which a conductor pattern is provided on the surface of a metal plate such as an aluminum plate or a steel plate with an insulating material interposed therebetween. When this metal substrate is used in a floppy disk drive device built into computer equipment, it can also serve as a part of the casing of the device, and in that case, the device can be made thinner. Furthermore, by providing a counterbore in the fixing screw hole of the metal substrate and using a countersunk screw as the fixing screw for fixing the metal substrate to the device, the amount of protrusion of the screw head from the metal substrate can be minimized. Therefore, the device can be made even thinner.

Conventionally, forming countersink holes in the fixing screw holes has been carried out by cutting using a chamfer cutter, the cutting edge of a drill, or the like. However, cutting chips scatter, which not only complicates the processing of the chips, but also requires post-treatment after cleaning due to the use of cutting oil, which increases processing time and increases processing costs. There was a problem of becoming

Instead of the above-mentioned cutting process, countersinking may be performed by pressing using a round punch having a tapered surface, and in this case, the machining time can be shortened and the machining cost can be reduced. However, due to the pressing force of the press, the material at the periphery of the pilot hole of the metal plate largely flows inward in the radial direction, causing a relative shift between the bonding surfaces with the insulating material and causing the insulating material to peel off. There's a problem.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to develop a metal substrate that can suitably reduce the processing cost of countersinking holes for fixing screws in metal substrates. An object of the present invention is to provide a structure of a hole for a fixing screw in a substrate and a method for processing the same.

[Structure of the Invention] <Means for Solving the Problem> According to the present invention, the object is to provide a metal substrate comprising an insulating material and a conductive pattern laminated in this order on at least one surface of a metal plate. The fixing screw hole has a countersunk hole portion formed by plastically working the other side of the metal plate of the pilot hole after forming the pilot hole. The structure of the fixing screw hole of the metal substrate is characterized in that the pilot hole has a partially enlarged portion along the radial direction, or the metal plate has an insulating material on at least one surface. A method of processing a hole for a fixing screw provided in a metal substrate formed by laminating conductor patterns in this order, the method comprising: forming a pilot hole having a partially enlarged portion along the radial direction; This is achieved by providing a method for processing a hole for a fixing screw in a metal substrate, which comprises the step of forming a countersunk hole portion on the other side of the metal plate of the prepared hole by plastic working.

<Function> With this method, when the countersunk hole portion after forming the pilot hole is processed, for example, by pressing using a punch,
Since the flow of material during press processing is dispersed not only in the radial direction but also in the circumferential direction, the relative displacement between the bonding surfaces of the metal plate and the insulating material is suppressed, and peeling of the insulating material is prevented. I can do it.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side sectional view of a main part showing a state in which the pilot hole of a fixing screw hole of a metal substrate 1 is machined based on the present invention. , a laminate 3 made of a glass cloth base epoxy resin as an insulating material provided on one lower surface 2a of the metal plate 2 in the figure, and a copper foil pasted on the surface of the laminate 3. Conductor pattern 4
For example, it is used as a printed wiring board installed in a floppy disk drive device.

The above-mentioned pilot hole processing is performed by pressing using a punch 5 and a die 6, and as shown in FIG. Press down and punch out. The punch 5 has a spline shape, and is provided with protrusions 5a at eight equal positions in the circumferential direction, for example. Therefore, as shown in FIG.
and an enlarged portion 8 punched out by the protrusion portion 5a. Note that the machining of the pilot hole 7 is not limited to the press machining described in 1. For example, cutting machining such as laser machining or broaching machining can be used.

The metal substrate 1 with the pilot hole 7 processed as described above is
In the next process, countersunk holes are machined. As shown in Figure 3,
The metal plate 2 is a surface opposite to the laminate 3 side of the metal substrate 1.
A round punch 12 having a tapered surface is coaxially pressed against the lower surface 2b of the hole 7 in the direction of the arrow in the figure, and a countersunk hole portion 9 is formed by plastic working as shown in FIG. be done. In addition, when the laminated plate 3 is provided also on the back surface 2b side of the metal substrate 1 as shown by the imaginary line, that is, the metal plate 2 has the laminated plate 3 and the conductive pattern 4 on both sides 2a and 2b, respectively. It goes without saying that the present invention is also applicable to the substrate 1.

By providing the countersunk hole portion 9 in the fixing screw hole 10, a countersunk screw can be used as a screw for fixing the metal substrate 1 to, for example, a floppy disk drive device. The metal substrate 1 is fixed by inserting a countersunk screw 11 into the fixing screw hole 10 and screwing it into the casing of the floppy disk drive. At this time, a portion of the head of the countersunk screw 11 is recessed into the countersunk hole portion 9, so that the amount of protrusion of the screw head from the metal substrate 1 is small, and the device can be further made thinner.

By the way, for example, when the pilot hole has a circular cross-sectional shape, if a countersunk hole is formed by the same press working as described above, a large flow of material will occur inward in the radial direction of the pilot hole on the laminate side of the metal plate. There is a problem in that the laminate plate peels off due to a large misalignment between the metal plate and the laminate plate. According to the present invention, by forming the countersink hole portion 9, the fixing screw hole 10 shown in solid line with respect to the imaginary line showing the pilot hole 7 is formed as shown in FIG. The flow of material due to press working during the formation of 9 can escape to the enlarged portion 8 . Therefore, as shown by the arrows in FIG. 5, the flow of the material is suitably distributed in the circumferential direction and radial direction, and the load applied to the back surface 2b of the metal plate 2 is distributed, thereby preventing the laminate plate 3 from peeling. can do.

It is desirable to change the design of the pilot hole 7 as appropriate depending on the thickness and physical properties of the metal substrate 1 and the dimensions of the fixing screw. 8 is provided, however, enlarged portions similar to those in the above embodiment may be provided at positions divided into two or more equal parts. In addition, the lower hole 7
It is not limited to the above-mentioned star shape, but may also have a polygonal cross-sectional shape such as a quadrangle (triangle, hexagon, etc.) as shown in Figure 6, or an elliptical cross-sectional shape as shown in Figure 7. good. Furthermore, as shown in FIG. 8, it is also possible to make the cross-sectional shape trigonometric, or to modify it.

In this embodiment, the countersink portion 9 was processed by press working, but any plastic working may be used, for example, swaging may be used.

[Effects of the Invention] As described above, according to the present invention, the flow of material due to plastic working when forming the countersunk hole portion after preparing the pilot hole can be suitably dispersed in the radial direction and the circumferential direction. In order to prevent the insulating material from peeling off, the countersunk hole part for inserting the screw head can be processed by press processing, which further improves the thinness of the device, and improves the reduction of processing costs. The effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a main part showing processing of a pilot hole according to the present invention. FIG. 2 is a plan view showing the shape of the pilot hole. FIG. 3 is a side sectional view of a main part showing processing of a countersunk hole portion according to the present invention. FIG. 4 is a perspective view showing a fixing screw hole machined according to the present invention. FIG. 5 is a plan view showing the fixing screw hole after the countersunk hole has been partially machined. FIG. 6 is a diagram showing a second example of the shape of the pilot hole. FIG. 7 is a diagram showing a third example of the shape of the pilot hole. FIG. 8 is a diagram showing a fourth example of the shape of the pilot hole.

Claims (2)

[Claims] (1) A fixing screw hole structure provided in a metal substrate formed by laminating an insulating material and a conductive pattern in this order on at least one surface of the metal plate, wherein the fixing screw hole is located below the metal substrate. The hole has a countersunk portion formed by plastically working the other side of the metal plate of the pilot hole after the hole is formed, and the pilot hole has a portion that is partially enlarged along the radial direction. Features a structure of holes for fixing screws on metal substrates. (2) A method for processing holes for fixing screws provided in a metal substrate formed by laminating an insulating material and a conductive pattern in this order on at least one surface of the metal plate, the holes being partially formed along the radial direction. A fixing screw for a metal substrate, comprising the steps of: forming a pilot hole having an enlarged portion; and forming a countersunk hole portion of the pilot hole on the other side of the metal plate by plastic working. How to process holes.