JPH06140789A - Manufacture of electromagnetic wave shield panel - Google Patents

Abstract

PURPOSE:To prevent deformation of a shield panel due to charging of paint by taking out the shield panel which is formed by blow molding from a die after it is fully cooled and then by charging a hollow inside thereof with paint in a hollow double wall structure plastic electromagnetic wave shield panel. CONSTITUTION:A shield panel 1 is formed by blow molding between division dies 2, 3. After molding, it is cooled in the die and taken out after mold opening. The shield panel 1 is made to stand straight above a tube part 4 and paint 6 having electromagnetic wave shield property is injected from an opening hole of the tube part 4 to an area near the tube part by using a nozzle tube 5. The nozzle tube 5 is drooped to an area near a lower end of a hollow part from the opening hole of the tube part 4 and the paint 6 is sucked and discharged. Then, the shield panel 1 is made horizontal, a tube member 12 wherein a blow means is connected to the opening hole of the tube 4 is connected after a small hole 11 is shaped at another end of the shield panel 1 in longitudinal direction, air is injected inside the shield panel 1 and air in the hollow inside is forcible dried by circulating it with air outside through the small hole 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electromagnetic wave shield panel used as a housing of an electric device, a wall material for construction, an electromagnetic wave shield material of a measuring instrument and the like.

[0002]

2. Description of the Related Art Conventionally, a metal panel is often used as a panel constituting a housing of an electric device. However, the metal panel requires a lot of man-hours such as pressing, bending, and welding parts, and There are problems that it takes time and cost to finish such as painting, and there are many design restrictions. For this reason, the constituent material of the housing panel is being changed from metal to resin. That is, resin has various advantages such as light weight and excellent moldability, a high degree of freedom in design, the possibility of integrating parts, and a cost advantage. It is widely used in molded parts, and its applications are being expanded. However, even though resin is excellent as a material, it is inferior in electromagnetic wave shielding property. Therefore, (1) a method of applying conductive paint to the surface of the resin panel with a spray gun, (2) metal on the surface of the resin panel. Means for imparting electromagnetic wave shielding properties are required, such as a method of sticking a foil and a method of (3) molding a panel with a composite resin mixed with a conductive filler. The coating method (1) has a problem that the coating work environment is bad and the coating film is peeled off due to an external impact, which adversely affects peripheral equipment. In the method (2) of sticking the metal foil, the sticking work is difficult when the panel has a three-dimensional shape. In the method (3) of molding a panel with the composite resin, it is difficult to simultaneously satisfy the electromagnetic wave shielding property and the moldability of the panel itself. Further, as an improvement of the coating method of (1), the applicant of the present invention has disclosed in JP-A-61-197.
As disclosed in Japanese Patent No. 221, No. 221, a molded product having a hollow double-wall structure is formed by arranging a parison in a mold and performing blow molding, and thereafter, the molded product in the mold is filled with a paint. We have proposed a method of manufacturing an electromagnetic shielding and shielding molded product by forming a conductive coating film on the inner surface of the hollow part of the molded product.

[0003]

In the above-mentioned conventional manufacturing method, since the coating material is applied while the hollow panel is still in the mold during the molding process, the interior temperature of the hollow panel still high. There is a problem that the paint having a relatively low temperature is injected into the hollow panel, which causes the hollow panel to be rapidly cooled and deformed.

On the other hand, there is also a coating method in which the hollow panel is removed from the molding die and then the coating material is filled / applied / discharged / dried in the hollow panel, but the coating material is simply removed from the die. In the coating method of (1), it is difficult to obtain a uniform coating film on the inner surface of the hollow panel, and it takes a long time to fill, coat, and discharge the coating material into the hollow panel.

The present invention has been conceived in view of the above, and provides a method for manufacturing an electromagnetic wave shield panel in which the hollow panel is not deformed, the working time is short, and the inner surface of the hollow panel can be uniformly coated. It is intended to be provided.

[0006]

In order to achieve the above object, a method of manufacturing an electromagnetic wave shield panel according to the present invention comprises:
After molding a plastic panel with a hollow double wall structure and taking it out from the molding die, a paint having an electromagnetic wave shielding property is injected to the vicinity of the opening hole in the panel through an opening hole provided at one end of this panel. Then, a nozzle tube is inserted from the above opening hole to the hollow inner bottom portion, the excess paint in the panel is sucked and discharged by this nozzle tube, and then the coating film attached to the inner wall of the hollow portion of the panel is dried. Further, in the above-described method of manufacturing an electromagnetic wave shield panel, the panel is placed in an upright state, the coating material is filled and applied to the panel, and then discharged, and then dried in a horizontal state with the side wall on the flat side facing down. . Further, when the coating film in the panel is dried, the air in the panel is forcibly sucked and exhausted.

[0007]

[Operation] The panel molded in the hollow double-wall structure is taken out from the molding die and cooled, and the inside of the hollow is filled with the paint. Then, the paint is forcibly discharged by suction to form a coating film on the inner wall surface of the entire hollow of the panel. The panel having the coating film formed on the inner surface is dried with the side wall on the flat side facing down, so that the coating film can be formed uniformly with the proper thickness maintained without the occurrence of the paint pool.
In this drying step, the air in the panel is forcibly sucked and exhausted, so that the panel is quickly dried.

[0008]

EXAMPLES Examples of the present invention will be described with reference to the drawings. FIG. 1 shows an electrophotographic copying machine. Since electromagnetic waves are radiated from the copying operation section of this type of copying machine, an electromagnetic wave shield panel 1 is provided on the front cover panel to protect workers from this electromagnetic wave. Is used. The electromagnetic wave shield panel 1 (hereinafter, abbreviated as a shield panel) has a structure in which a paint having an electromagnetic wave shielding property is applied to the inner surface of a plastic hollow panel.

A method of manufacturing the shield panel 1 will be described below. (1) Molding Step As shown in FIG. 2, the shield panel 1 is molded by blow molding while sandwiching the plasticized and melted parison between the split molds 2 and 3 having cavities formed in the outer shape thereof. To be done. After molding, the mold is cooled and then the mold is opened and taken out. A cylindrical portion 4 communicating with the hollow inside of the shield panel 1 is provided at one longitudinal end of the shield panel 1. After molding, the tip of the tubular portion 4 is cut off to open an opening.

(2) Filling and coating process As shown in FIG. 3 (a), the shield panel 1 is placed upright on the cylindrical portion 4 and is erected upright, and the nozzle tube 5 is used to shield the electromagnetic wave from the opening of the cylindrical portion 4. The coating material 6 having the above is injected up to the vicinity of the cylindrical portion. At this time, the paint 6 is water-based.

(3) Discharging step As shown in FIG. 3 (b), the nozzle tube 5 is hung down from the opening hole of the cylindrical portion 4 to the vicinity of the lower end of the hollow portion, and the paint 6 inside the hollow portion is sucked and discharged from the nozzle tube 5. To do. At this time, a device as shown in FIG. 4 is used as a means for injecting and sucking the paint 6. In the figure, 7 is a filling pump connected to the paint tank 8, 9 is a suction pump, which are connected to the nozzle pipe 5 via a solenoid valve 10. By switching the solenoid valve 10, the filling and suction of the paint 6 is performed. It is designed to be discharged. In addition, as shown in FIG. 3D, the paint may be discharged from the opening hole of the tubular portion 4 by inverting the shield panel 1 as shown in FIG. 3D.

(4) Drying Step A small hole 11 is formed at the other end in the longitudinal direction of the shield panel 1 in a portion that does not interfere with the appearance of the panel, and then, as shown in FIG.
As shown in (c), the pipe member 12 connected to the air blower or suction means is connected to the opening hole of the cylindrical portion 4 to inject or suck air into the shield panel 1 to remove air in the hollow inside from the small hole. The coating film inside the hollow is forcibly dried by circulating it through the air through 11. Thereafter, the tubular portion 5 is cut off and the opening of this portion is closed. The small hole 11 provided at the other end is left open for ventilation inside the hollow. The injection air may be normal air, but dry air or high temperature air is used.

In this drying step, as shown in FIG. 3 (c), the shield panel 1 is laid down to be horizontal and the above drying is performed. This is to make the coating film on the inner wall surface uniform and have an appropriate thickness. Note that functional members such as ribs, fool proofs, brackets, and switch projections are three-dimensionally integrally formed on the back surface of the shield panel used as the housing of the electric device. Therefore, ribs 1 on the shield panel 1
When there is a three-dimensional functional member such as 3, the side wall (back surface) on which the functional member is present is set to the upper side, and the planar side wall is positioned on the lower side. This is because when the side wall having the functional member is located on the lower side, the thickness of the coating film changes due to the unevenness of the functional member. The resin used in the present invention is a blow-moldable thermoplastic resin such as ABS resin, polycarbonate, polyamide, modified polyphenylene oxide, and as the coating material, a resin binder such as acrylic or polyurethane is used, and nickel, copper, silver, A water-based or oil-based paint containing a conductive filler such as carbon graphite or carbon black can be used. The blow-molded resin preferably has a wall thickness of about 2 to 4 mm, and the coating film has a wall thickness of about 30 to 80 μm.

[0014]

According to the present invention, the shield panel 1 to be blow-molded is taken out from the molds 2 and 3 and sufficiently cooled, and then the hollow interior of the shield panel 1 is filled with the coating material. Deformation can be prevented. Further, the paint 6 filling the hollow inside of the shield panel 1 is forcibly filled through the nozzle pipe 5, and the surplus paint 6 is sucked by the nozzle pipe 5 and forcibly discharged, The coating process can be performed in a short cycle time. Further, by drying the shield panel 1 in a horizontal state with the flat side wall facing downward during the drying step, local coating material can be prevented from being accumulated and a coating film having a uniform thickness can be obtained. Therefore, it does not take much drying time locally, and the entire inner wall surface can be dried in a uniform drying time. Further, in the drying step, the hollow inside of the shield panel 1 is forcedly ventilated, so that the shield panel 1 can be dried in a short time.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of use of an electromagnetic wave shield panel manufactured by the method of the present invention.

FIG. 2 is a cross-sectional view showing a forming process of a hollow panel.

3 (a), (b), (c), and (d) are explanatory views showing each process of filling, discharging, and drying the paint.

FIG. 4 is a circuit diagram showing an apparatus for filling and discharging paint.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electromagnetic wave shield panel, 2, 3 ... Split mold, 4 ... Cylindrical part, 5 ... Nozzle tube, 6 ... Paint, 7 ... Filling pump, 8 ... Paint tank, 9 ... Suction pump, 10 ... Solenoid valve, 11
... Small hole, 12 ... Tube member, 13 ... Rib.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area B29L 24:00 4F

Claims (3)

[Claims] 1. A plastic panel having a hollow double-wall structure is molded, taken out from a molding die, and a paint having an electromagnetic wave shielding property is opened in the panel through an opening hole provided at one end of the panel. Inject up to the vicinity of the hole, then insert the nozzle tube from the above-mentioned opening hole to the inner bottom of the hollow, suck and discharge the excess paint in the panel with this nozzle tube, then,
A method for producing an electromagnetic wave shield panel, which comprises drying the coating film attached to the inner wall of the hollow portion of the panel. 2. A plastic panel having a hollow double-wall structure is molded, taken out from a molding die, and then the hollow interior of the panel is filled with a paint having an electromagnetic wave shielding property.
In the method for manufacturing an electromagnetic wave shield panel, which is applied, and then the excess paint is discharged and then the coating film adhered to the inner wall of the hollow portion is dried, the panel is placed in an upright state and the paint is filled / applied to it. At the same time, discharge is performed, and then drying is performed in a horizontal state with the side wall on the flat side facing down, and a method for manufacturing an electromagnetic wave shield panel. 3. The air in the panel is forcibly sucked and exhausted when the coating film in the panel is dried.
A method for manufacturing the described electromagnetic wave shield panel.