JP4548972B2 - Manufacturing method of irregular shield gasket - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for industrially advantageously manufacturing a deformed shield gasket for applying electromagnetic shielding mainly by applying to a main body, a lid, a door, or the like of a housing in an electronic device.
[0002]
[Prior art]
An electromagnetic shielding gasket that closes the opening is used between the main body of the housing and the lid / door of the electronic device to prevent EMI (electromagnetic interference or electromagnetic interference) or RFI (radio frequency interference).
[0003]
There are various methods for manufacturing an electromagnetic shielding gasket. Among them, as the irregularly shaped shielding gasket, various structures and shapes have been devised, for example, a U-shape as described in JP-A-11-135964 and various shapes.
[0004]
(A) As one method for producing an electromagnetic shielding gasket, there is known a method of extruding synthetic rubber such as thermoplastic elastomer or silicone rubber imparted with conductivity. This method has an advantage that the target product can be produced continuously and efficiently.
[0005]
(B) As another method of manufacturing an electromagnetic shielding gasket, an extruded product of a thermoplastic elastomer or synthetic rubber foam is used as the gasket core material, and a conductive woven fabric is wound around the core material. There is a method of sticking to the shape. In this method, the core material can be efficiently manufactured, and since the core material is a foam, the elasticity is large, and the pressing force when mounted on the housing or the base is small. And has the advantage of not distorting the substrate.
[0006]
(C) As another method for manufacturing an electromagnetic shielding gasket, as described in US Pat. No. 4,857,668, a conductive woven fabric is continuously inserted into a mold (guide plate) having a predetermined shape. There is known a method in which a foaming raw material (a mixture of several kinds of liquid raw materials) is injected into the cavity while creating a cavity, causing a chemical reaction to foam, and then curing. This method has an advantage that an object can be produced continuously and efficiently, and an arbitrary elasticity can be obtained by changing the expansion ratio.
[0007]
(D) Then, as a method for manufacturing a deformed shield gasket having a special or complex cross section, a predetermined size was cut as shown in FIGS. 5 (a) and 5 (b). Each of the plurality of foam blocks (7a), (7b), (7c) is joined through an adhesive or the like to form a foam molded product (9) such as a groove (8). There is a method to do.
[0008]
(E) Further, as a method for manufacturing a deformed shield gasket having a special cross section, a foam block cut into a predetermined size as shown in FIGS. 6 (a) and 6 (b). A method is also known in which (7) is heated and bent into a predetermined direction as indicated by an arrow in the figure to obtain a foam molded product (9) with a groove (8).
[0009]
[Problems to be solved by the invention]
The above method (A) requires many types of molds for each type of product during production, and the cost for equipment and setup change (switching of working conditions) for this is great. Not suitable. In addition, since the elastic body that is the core material is non-foamed (without bubbles), the elasticity is small, and the pressing force when attached to the case or base becomes excessive, and the case or base is distorted. May cause it.
[0010]
The method (B), like the method (A), requires many types of molds for each type of product during production, and the cost required for equipment and setup change (switching of work conditions) for this purpose. However, it is not suitable for high-mix low-volume production. Moreover, since the outer side part of a core material will be in a non-foaming state, there exists a disadvantage that the adhesion part which bonded the electroconductive woven fabric becomes hard.
[0011]
The method (C) has a disadvantage in that it requires a high-precision casting machine, a long heat curing facility, and the like in production, and therefore the facility cost and the maintenance cost are large.
Moreover, since the uncured raw material oozes out from the weave of the conductive woven fabric due to the foaming pressure when foaming, it is necessary to clog the conductive woven fabric in advance, and depending on the shape of the irregular shield gasket The apparent density differs depending on the portion of the filled foam material, and the hardness may be non-uniform.
[0012]
The above method (D) is suitable for high-mix low-volume production and has the advantage that the equipment cost is low. However, since the number of parts increases, the number of bonding steps increases, and the bonding accuracy is low. There is a risk of peeling off or the adhesive surface becoming hard.
[0013]
The method (E) is suitable for high-mix low-volume production and has the advantage that the equipment cost is low. However, the deformed shape is limited to a relatively simple one, and the bent portion is likely to return to its original shape over time. There is a problem.
[0014]
Under such a background, the present invention can cope with both mass production and multi-product small-quantity production, is advantageous in terms of manufacturing cost, and reliably obtains a product that is uniform and has elasticity as designed. Further, it is an object of the present invention to provide an industrial manufacturing method of a modified shield gasket which can be obtained with little change with time during use and thus can provide a reliable product.
[0015]
[Means for Solving the Problems]
The manufacturing method of the modified shield gasket of the present invention is as follows:
Preparing a cut elastic body (2) obtained by cutting the elastic block (1) into a band or string;
The grindstone (6) of the grinding means is pressed against a specific part of the outer peripheral surface of the cut elastic body (2) to grind and remove unnecessary parts by grinding the cut elastic body (2) in the longitudinal direction. To become a grinding body (3), and
A conductive outer cover (4) is wound around the outer periphery of the modified cross-section grind (3) in a cylindrical shape through an adhesive layer to form a shield gasket (5).
[0016]
In this case, after forming the modified cross-section grind body (3), the deformed cross-section grind body (3) is cut in the longitudinal direction to form a cut irregular cross-section grind body (3 '), and then the cut. It is also possible to form a shield gasket (5) by winding a conductive jacket (4) around the outer periphery of the modified cross-section grinding body (3 ′) in a body-wound shape via an adhesive layer.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
[0018]
<Elastic body block (1)>
The elastic body block (1) is preferably made of a foamed soft, elastomeric or rubbery polymer such as polyurethane, silicone rubber, EPDM (ethylene-propylene-diene copolymer), or neoprene rubber. Examples thereof include a molded body block of a foam (particularly a sponge-like foam).
[0019]
The density of the elastic block (1) is often about ³⁰ to 120 kg / m ³ .
[0020]
The size of the elastic block (1) is arbitrary, but there are restrictions on devices such as foaming devices and slicers.For example, in the case of polyurethane open-cell foams, the vertical, horizontal, and height are from tens of centimeters each. Often several meters are used.
[0021]
<Cutting elastic body (2)>
A cut elastic body (2) is obtained by cutting the elastic body block (1) into a band shape or a string shape. Since the surface portion of the elastic block (1) may be a skin layer having a higher density than the inside, it is often preferable not to use the portion from the surface to a depth of several millimeters. When thickness accuracy is required, the elastic body block (1) may be heat-compressed to form a compressed product, and then subjected to cutting into a band shape or a string shape.
[0022]
To obtain the cut elastic body (2) from the elastic body block (1), for example,
(B) A method of slicing a rectangular parallelepiped or a similar block parallel to a predetermined thickness and then chopping to a predetermined width (the ends of each piece can also be joined and connected by slicing or cutting),
(B) Peeling the cylindrical block to a predetermined thickness (stripping the wig) to form a sheet, and then cutting this into a predetermined width;
(C) Connect the ends of a long block to form a loop, peel it from the inner or outer circumference (wig off) into a sheet, and then chop it into a predetermined width (first (It can also be made into a loop by connecting both ends after making it a narrow and long object, and then peeling)
Etc. can be adopted.
[0023]
The cross section in the width direction of the cut elastic body (1) is usually a quadrilateral. Examples of the quadrilateral include a square, a rectangle, a trapezoid, a half trapezoid (a top surface and a bottom surface are parallel, one of the side surfaces is vertical, and the other is slanted), a parallelogram, and the like. In addition to the quadrilateral, it may be a triangle, a hexagon, or the like depending on circumstances.
[0024]
The elastic block (1) or the cut elastic body (2) may be manufactured by another company or an affiliated company.
[0025]
Although there is no particular limitation on the cross-sectional size of the cut elastic body (1), the cross-sectional size of the final product (shield gasket) excluding the conductive jacket (4) is often set to about 25 to 900 mm ^2. .
[0026]
<Irradiated cross-section grinding body (3), Cut irregular-shape grinding body (3 ')>
Using the above cut elastic body (2), the grindstone (6) of the grinding means is pressed against a specific part of the outer peripheral surface of the cut elastic body (2) to grind the cut elastic body (2) in the longitudinal direction. If it is removed by grinding, a modified cross-section ground product (3) is obtained. In grinding, at least one of the grinding means or the cut elastic body (2) may be moved.
[0027]
Grinding typically refers to a process in which a necessary part of a workpiece is scraped off by a grinding wheel that rotates at high speed. As a grinding means, various types of grinding machines including a grinding wheel and a grinding wheel portion (6) are used, and a belt grinding method and a barrel grinding method are also employed.
[0028]
For example, when grinding the surface of the cut elastic body (2) into a groove shape such as a concave groove or a U-shaped groove, grinding means including a grinding wheel suitable for the shape of the groove is used. When grinding so that the surface of) becomes convex, a grinding means having a grinding wheel having a U-shaped grinding surface is used. The same applies when dropping or rounding the edge of the cut elastic body (2).
[0029]
The specific part of the outer peripheral surface means the upper surface, lower surface, side surface, ridge, etc. of the cut elastic body (2). Grind to one or more of these areas. One or more grindstones (6) of the grinding means are used. When grinding is performed on n parts, grinding may be performed at once using n grinding wheel portions (6) of the grinding means (a multi-purpose grinding wheel may be used). Grinding may be performed sequentially using less than n parts (6).
[0030]
In the above, it is assumed that the cut elastic body (2) is ground to form an irregular cross-section grinding body (3), and one shield gasket (5) is manufactured from the irregular cross-section grinding body (3). However, after grinding the cut elastic body (2) to form a modified section grinding body (3) in which the unit to be the shield gasket (5) is connected, the modified section grinding body (3) May be cut in the longitudinal direction to form a cut irregularly-shaped cross-section grind (3 ′).
[0031]
<Conductive jacket (4), shield gasket>
The conductive outer shell (4) is wound around the outer periphery of the modified cross-section ground workpiece (3) obtained above (or the cut irregular-shaped cross-section ground workpiece (3 ')) in a cylindrical shape through an adhesive layer, and shielded. Make a gasket (5). In the case where the irregular-shaped cross-section grind body (3) (or the cut irregular-shaped cross-section grind body (3 ')) has a concave groove, the conductive jacket (4) is also along the concave groove.
[0032]
As the conductive sheath (4), a sheath having a conductive shape such as a cloth shape, a net shape, or a sheet (foil) shape, preferably a conductive woven fabric or a metal foil is used. A synthetic resin film layer may be provided. Among these, as the conductive woven fabric, a multifilament yarn made of fine metal wires (monel, copper weld, aluminum, tin-plated copper, etc.) or metal-coated fibers (fibers coated with synthetic fibers by means of plating, vapor deposition, sputtering, etc.) Or the thing which woven the monofilament yarn, the thing which gave the metal coat to the woven fabric woven using the synthetic fiber yarn, etc. are mention | raise | lifted. As the metal foil, an aluminum foil is usually used.
[0033]
Preferable examples of the adhesive for forming the adhesive layer include various hot melt adhesives including polyester, polyolefin, ethylene-vinyl acetate copolymer, polyamide, polyurethane, and acrylic. However, depending on the case, an adhesive or a normal adhesive can also be used.
[0034]
<Application>
The deformed shield gasket obtained by the method of the present invention is a joint between metal casings of equipment using electronic components, between the casing and the lid, between the casing and the door, and between the lid and the door. It is mounted between the base and parts.
[0035]
【Example】
The following examples further illustrate the invention.
[0036]
Example 1
FIG. 1 is an explanatory view showing an example of a manufacturing process of a modified shield gasket of the present invention.
[0037]
Elastic body block (1) comprising a foam-like or sponge-like elastic foam body block (for example, polyurethane open cell foam having a size of 1 m × 1 m × 0.5 m and a density of 60 kg / m ³ (See Fig. 1 (a)), slice it into strips (if necessary, it may be heat-compressed in the thickness direction after slicing), and then cut into cords in the length direction to complete A cut elastic body (2) having a cross-sectional shape in consideration of the cross-sectional dimensions of the product was obtained (see FIG. 1 (b)).
[0038]
Next, a grindstone portion (6) of a rotating disc-shaped grinding wheel as an example of a grinding means is pressed against the central portion of the upper surface of the cut elastic body (2), and the cut elastic body (2) is moved in the longitudinal direction. By grinding, unnecessary portions were removed by grinding (see FIG. 1C). As a result, a deformed cross-section grinding body (3) having a cross-sectional shape of a concave groove was obtained (see FIG. 1 (d)).
[0039]
A shield gasket (5) was obtained by winding a conductive outer shell (4) around the outer periphery of the modified cross-section grind (3) obtained in this way in a body-wound shape via an adhesive layer ( (See FIG. 1 (e)).
[0040]
Example 2
FIG. 2 is an explanatory view showing another example of the manufacturing process of the modified shield gasket of the present invention.
[0041]
Prepare the elastic block (1) in the same way as in Example 1 and slice it into strips (if necessary, it may be heat-compressed in the thickness direction after slicing) and further cut in the length direction to make it wider Thus, a sheet-like cut elastic body (2) having a cross-sectional shape in consideration of a cross-sectional dimension of the shape when the finished product is continuously provided (see FIG. 2 (B)).
[0042]
Next, the grindstone portion (6) of a rotating disc-shaped grinding wheel as an example of a grinding means is pressed against the upper surface of the sheet-like cut elastic body (2) at a time (may be sequentially pressed). Unnecessary portions were ground and removed by grinding the cut elastic body (2) in the longitudinal direction (see FIG. 2 (c)).
[0043]
As a result, a modified cross-section grinding body (3) having a cross-sectional shape in which the unit of the finished product is continuously formed is obtained (see FIG. 2 (c)). 3) was cut in the longitudinal direction to obtain individual cut irregularly-shaped cross-section grinding bodies (3 ′) (see FIG. 2 (d)).
[0044]
A conductive gasket (4) is wound around the outer periphery of the cut profile cross-section grind (3 ') obtained in this way via an adhesive layer to form a shield gasket (5). (See FIG. 2 (e)).
[0045]
Example 3
FIG. 3 is an explanatory view showing still another example of the manufacturing process of the modified shield gasket of the present invention.
[0046]
Prepare the elastic block (1) in the same way as in Example 1 and slice it into strips (if necessary, it may be heat-compressed in the thickness direction after slicing) and then cut into a string in the length direction Thus, a cut elastic body (2) having a cross-sectional shape in consideration of the cross-sectional dimension of the finished product was obtained (see FIG. 3B).
[0047]
Next, a rotating disc-shaped grindstone portion (6) as an example of a grinding means is pressed against the central portion of the upper surface of the cut elastic body (2), and the grindstone portion (6) as an example of the grindstone portion (6). Unnecessary portions were ground and removed by pressing a pulley-shaped grinding wheel having a U-shaped grinding surface and grinding the cut elastic body (2) in the longitudinal direction (see FIG. 3C). As a result, a deformed cross-section grinding body (3) was obtained in which the upper surface was formed in the shape of a concave groove, the lower surface was formed in an arc shape protruding outward, and the entire cross-section was U-shaped (see FIG. 3 (d)). ).
[0048]
A shield gasket (5) was obtained by winding a conductive outer shell (4) around the outer periphery of the modified cross-section grind (3) obtained in this way in a body-wound shape via an adhesive layer ( (See FIG. 3 (e)).
[0049]
Example 4
FIG. 4 is an explanatory view showing various examples of the cross-sectional shape at the stage of the modified cross-section grind (3). A portion indicated by a broken line is a grinding removal portion (V) removed by grinding.
[0050]
By appropriately selecting the shape of the grinding wheel portion (6) and the grinding part of the grinding means, as shown in FIGS. 4 (A) to (L), various modified cross-section grinding bodies (3) from the cut elastic body (2) are obtained. Was made.
[0051]
If the grinding removal part (V) increases, the waste of materials and processing increases, so the cut elastic body (2) has a shape and size other than those shown in the figure, and the irregular cross-section grinding body after grinding ( It is also preferable to approximate the cross-sectional shape and size of 3) as much as possible. Alternatively, in consideration of the cross-sectional shape and size of the material and the processed product, it may be cut and divided in advance so as to obtain a plurality of irregular cross-section grinding bodies (3).
[0052]
【The invention's effect】
The manufacturing method of the deformed shield gasket according to the present invention can be commercialized without impairing the elasticity inherent in the material, so there is no need to apply an excessive force when attaching to the housing, etc. Is not excessively deformed, and the electromagnetic wave shield can be perfected.
[0053]
In addition, since the production method according to the present invention simply grinds the cut elastic body into an arbitrary shape, the process can be simplified and it is possible to cope with a large variety of small-quantity production. And since there are no joints in the molded product in particular, it is possible to make the electromagnetic shielding more perfect by perfecting the adhesion of the conductive jacket without causing deviations at each part or deforming when using the product. it can.
[0054]
As described above, the method of the present invention can cope with both mass production and multi-product small-quantity production, and is advantageous in terms of manufacturing cost. Further, according to the method of the present invention, the method is uniform and designed as designed. A product having elasticity can be reliably obtained, and further, there is little change with time in use, and thus a reliable product can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a manufacturing process of a modified shield gasket of the present invention.
FIG. 2 is an explanatory view showing another example of the manufacturing process of the modified shield gasket of the present invention.
FIG. 3 is an explanatory view showing still another example of the manufacturing process of the modified shield gasket of the present invention.
FIG. 4 is an explanatory view showing various examples of the cross-sectional shape at the stage of the modified cross-section grind (3).
FIG. 5 is an explanatory view showing an example of a manufacturing process of a conventional deformed shield gasket.
FIG. 6 is an explanatory view showing another example of the manufacturing process of a conventional irregular shield gasket.
[Explanation of symbols]
(1) ... elastic block,
(2)… cut elastic body,
(3) ... Grinding body with irregular cross section,
(3 ') ... Cutting profile cross-section grinding body,
(4)… conductive jacket,
(5)… Shield gasket,
(6)… Wheel part of grinding means,
(V)… grinding removal part,
(7), (7a), (7b), (7c)… foam block,
(8)… groove,
(9) ... Foam molded products

Claims (4)

Preparing a cut elastic body (2) obtained by cutting the elastic block (1) into a band or string;
The grindstone (6) of the grinding means is pressed against a specific part of the outer peripheral surface of the cut elastic body (2) to grind and remove unnecessary parts by grinding the cut elastic body (2) in the longitudinal direction. To become a grinding body (3), and
Production of a deformed shield gasket characterized in that a conductive jacket (4) is wound around the outer periphery of the modified cross-section grind body (3) via an adhesive layer to form a shield gasket (5) Law. 2. The process according to claim 1, wherein the elastic block (1) is a sponge-like foam having elasticity. The manufacturing method according to claim 1, wherein the cut elastic body (1) has a quadrilateral cross section in the width direction. After forming the modified cross-section ground processed body (3), the modified cross-section ground processed body (3) is cut in the longitudinal direction to obtain a cut-shaped cross-section ground processed body (3 '), and
The conductive outer shell (4) is wound around the outer periphery of the cut irregular-shaped cross-section grinding body (3 ') through an adhesive layer in a cylinder shape to form a shield gasket (5). The manufacturing method described.

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