JPH0354878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method of manufacturing a shield cover for high-frequency electrical equipment, and more particularly relates to a method of forming a grounding cut-and-raised piece partially formed on a shield cover.

2. Description of the Related Art In general, high-frequency electrical equipment such as electronic tuners have a structure in which a printed wiring body in which high-frequency circuit components are assembled and wired on a printed circuit board is assembled into a frame-shaped base, and a shield cover is fitted into the opening of the base. A grounded partition plate is installed vertically on the printed circuit board of the printed wiring body to separate the high frequency circuit components incorporated on the same board into high frequency shields for each unit circuit, and the shield cover is partially attached to the partition plate together with the base. This prevents unnecessary radiation and improves electrical characteristics. The means for grounding the shield cover to the partition plate is generally to provide a cut and raised piece protruding from the inner surface of the shield cover, and bring the tip of this cut and raised piece into elastic contact with the partition plate when the shield cover is installed. It is. Conventionally, the following two methods have been used to form the grounding cut-and-raised piece of the shield cover.

First, the most common first method will be explained with reference to FIGS. 3 and 4. First, a flat shield cover 1 shown in FIG. 3 and FIG. The third cut-and-raised piece is planned to be formed.
As shown in FIG. 4 and FIG. Next, as shown in FIGS. 3 and 4, the cut and raised portion 2 is bent toward the inner surface of the shield cover 1 to form a desired cut and raised piece 3. Incidentally, such cut and raised pieces 3 form one shield cover 1.
It is formed at once in multiple cylindrical places, and the cut and raised pieces 3
For example, when the shield cover 1 is fitted onto the frame-shaped base 4 as shown in FIG. It comes into contact with the bullet.

Next, the second method will be explained with reference to FIGS. 5 and 6. First, a predetermined portion of the shield cover 1 where the cut and raised pieces are to be formed is placed as shown in FIG. 5 and FIG. A substantially U-shaped edge hole 6 with a width d ₁ is punched out. Next, the portion surrounded by the cut-out hole 6 is bent inward as shown in FIGS. 5 and 6 to form a desired cut-and-raised piece 7.

Problems to be Solved by the Invention Incidentally, the first method described above is the simplest in terms of man-hours and technology, but because it is simply a cut and raise, it requires cutting the cut and raise piece 3 and the base material side of the shield cover 1. If the friction between the surfaces is large, the elasticity of the cut and raised piece 3 may be impaired, and in the worst case, the tip of the cut and raised piece 3 and the base metal side may repeatedly come into contact and non-contact, causing noise generation or damage to the cut and raised piece 3. The contact between the raised piece 3 and the partition plate 5 became uncertain, which sometimes made the high frequency characteristics unstable.

In addition, in the second method, there is no friction with the base material side of the cut and raised piece 7, and there is no problem mentioned above, but the width of the edge hole 6 is
If _d1 is small, the life of the mold for punching and forming the edged hole 6 will be shortened, and conversely, if the width _d1 is large, the gap between the cut and raised piece 7 and the base material side will become large and the high frequency of the shield cover itself will be reduced. There was a problem where the shield function was impaired.

Furthermore, the first and second methods described above apply to the shield cover 1.
When forming the substantially U-shaped cut and raised portion 2 and the edge hole 6, stress may be concentrated at both ends of the cut and raised portion 2 and the edge hole 6, causing distortion and cracks at both ends. As a result, the elastic force of the root portions of the cut and raised pieces 3 and 7 is weakened, causing a problem that the contact pressure of the cut and raised pieces 3 and 7 to the partition plate 5 becomes unstable.

Means for Solving the Problems The present invention has been made in view of the above problems.
The technical means of the present invention to solve this problem is to drill a hole in advance at both ends of the portion of the shield cover where the grounding piece is to be formed, and then cut the hole in a substantially U-shape from the hole as the base point. The method is to form a cut and raised piece in each process of edge cutting and bending.

Effect: According to this technical means, when cutting and bending the portion of the shield cover where the cut and bend pieces are to be formed into a substantially U-shape, holes are first drilled at both ends of the cut and bend. The stress applied at both ends is dispersed by the holes,
Distortion and cracks are less likely to occur in the root portion of the cut and raised pieces that are finally formed, and the elastic force of the cut and raised pieces can be stably obtained. In addition, after cutting and raising, the cut and raised part is edged, but unlike the process of punching out parts of a metal plate, the edge cutting process at this time is different from the process of partially punching out a metal plate. This is a relatively easy process of punching or bending, and it is possible to make the edge width sufficiently small.

Embodiments Specific embodiments of the present invention are shown in FIGS. 1 and 2.
The explanation will be given below in sequence with reference to (d).

First, holes 8, 8 are made as shown in FIGS. 1 and 2 B at both ends of the part where the cut and raised piece for the arm is to be formed, which is the chain line part of the shield cover 1 shown in FIGS. 1 and 2 A. to be drilled. Although the holes 8, 8 are square holes in the drawings, they may be round holes or the like, and the area thereof is small enough not to impair shielding performance.

Next, cut out the dotted line tube part shown in FIGS. Cut and shape. Since this cut and raised portion 9 is formed with the holes 8, 8 as the base points, the stress applied to both ends of the cut and raised portion during cutting and raising is dispersed by the holes 8, 8, and therefore the cut and raised portion 9
There is almost no concern that distortion or cracks will occur at both ends.

Next, the edge of the cut and raised portion 9 is cut out, and at the same time, the edged portion is bent inward to form a predetermined cut and raised piece 10 as shown in FIGS. 1 and 2 D. Form. At this time, the edge width d ₂ of the cut-and-raised portion 9 is smaller than the length of one side of the holes 8 and 8, which are square holes (in the case of round holes, smaller than the diameter thereof).
so that it is formed from the center of one side of 8,
To prevent cracks or distortions from occurring around the holes 8 and 8 when drilling. This kind of edge cutting process can be performed with less force than the process shown in Figure 5 B.
No matter how small the edging width _d2 is, there is no problem that the life of the edging mold will be shortened. Therefore, the cut and raised piece 10 can be formed separated from the base material side of the shield case 1 by a sufficiently small edge width d ₂ , thereby preventing the cut and raised piece 10 from coming into contact with the base material side and preventing the base material from contacting the base material side. This solves problems such as the shield function being impaired due to a large distance from the side. Further, the elasticity of the root portion of the cut and raised piece 10 is always stable because the holes 8, 8 prevent cracks and distortions during processing.

Effects of the Invention According to the present invention, the elasticity of the grounding cut-and-raised piece of the shield cover is stabilized, and a non-contact state can be stably obtained even with a minute gap with the base material side of the shield cover. When the cut-and-raised piece is fitted into the base of high-frequency electrical equipment and grounded by making elastic contact with the partition plate inside the base, the contact between the cut-and-raised piece and the partition plate is always good, resulting in stable characteristics. It becomes possible to provide high-frequency electrical equipment.

[Brief explanation of drawings]

1A to 1D are partial plan views of the shield cover at each step showing a specific embodiment of the method of the present invention;
A to D in FIG. 2 are sectional views taken along lines A-A, B-B, C-C, and D-D at corresponding points A to D in FIG. 1. 3 and 4, and 5 and 6 are for explaining two examples of conventional shield cover manufacturing methods. A to C in the diagram are number 3
Corresponding lines A to C in the diagram, E-E line, F-F line, G-
A sectional view taken along line G, A to C in FIG. 5 are partial plan views of the shield cover, A to C in FIG. It is a sectional view along the JJ line. FIG. 7 is a perspective view showing an example of a high frequency electric device having a shield cover. 1...Shield cover, 8, 8...hole, 9...
Cut-and-raised portion, 10... cut-and-raised piece.

Claims (1)

[Claims] 1. Pre-drilling holes in the cut-and-raised piece of the shield cover having a partially substantially U-shaped earthing cut-and-raised piece at both ends of the portion where the cut-and-raised piece is planned to be formed; A method for manufacturing a shield cover, characterized in that the shield cover is formed by a step of cutting and raising a substantially U-shape from a hole, and a step of bending the cut and raised portion into a desired shape at the same time as edge processing.