JPS62772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an elliptical waveguide, and more particularly to a method for manufacturing an elliptical waveguide that is flexible and has a highly stable cross-sectional shape using a thin metal tape.

Waveguides are widely used as microwave transmission lines for UHF, SHF bands, etc., and flexible waveguides using conventional thin metal tapes are manufactured as follows. A thin metal tape, which is the material of the waveguide, is coated with a thermoplastic resin on one side.Then, the thermoplastic resin layer is on the outside, and the edges of the laminated tape are overlapped with each other to form a circular shape. Form into a cylinder. Subsequently, in a melt bonding device, the thermoplastic resin layers of the overlapping portions of the laminated tapes are melted using a heating means such as a hot jet to fuse the overlapping portions. Next, a cylinder with a circular cross section is formed into an elliptical cylinder using a molding device, a protective coating of polyethylene is applied on the circumference of the elliptical cylinder using an extrusion device, and the protective coating is cooled using a cooling device. to manufacture waveguides.

By the way, in the above method, after forming the laminated tape into a cylinder with an oval cross section, a polyethylene protective coating is extruded on the circumference of the cylinder, and the protective coating is cooled with a cooling device. Cooling of the protective coating causes rapid thermal contraction of the polyethylene protective coating. This heat shrinkage applies stress to the overlapped portions of the heat-sealed laminated tapes, causing displacement in the overlapped portions, making it impossible to obtain a cylinder with desired dimensions and shape. Maintaining highly accurate dimensions and shapes is especially necessary when manufacturing waveguides that require good electrical properties such as transmission properties. In addition, if heat shrinks rapidly when the protective coating cools, the stress applied to the overlapping part will cause the edges of the inner laminated tape at the overlapping part to fray or peel, making it impossible to maintain the shape of the cylinder. . This fraying or peeling of the tape edge causes an increase in transmission loss in the case of a waveguide, so it is necessary to avoid this as much as possible.

The present invention has been made in view of the above points, and it is possible to obtain a cylinder having a desired cross-sectional shape with high dimensional accuracy formed from a laminated tape, and which has good fusion bonding at the overlapped portion of the laminated tape. The present invention provides a method for manufacturing an elliptical waveguide with good electrical properties and excellent flexibility by manufacturing a laminated tape having a thermoplastic synthetic resin layer on at least one side of a metal tape in the longitudinal direction. A method for manufacturing an elliptical waveguide, in which the elliptical waveguide is formed into an elliptical cylinder having continuous overlapping parts, a protective coating is extruded onto the elliptical cylinder, and then cooled, the protective coating on the elliptical cylinder being cooled. In this case, a cooling device is installed in a columnar body that has an outer periphery similar in shape to the inner periphery of the elliptical waveguide but slightly larger in size, and is tapered so that its tip is slightly tapered. An elliptical waveguide characterized by being arranged in a floating state inside an elliptical cylinder to support the thermal contraction force of the protective coating from the inside when the extruded protective coating is cooled. This is the manufacturing method.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a process explanatory diagram of the present invention, FIG. 2 is a cross-sectional view of a cooling device portion of the present invention, and FIG. 3 is a perspective view of a columnar body.

In FIG. 1, reference numeral 1 denotes a tape drum around which a laminated tape 2, which is a material for a waveguide, is wound. The laminated tape 2 is a thin metal tape, such as a conductive tape made of a thin metal film such as aluminum, and at least one side thereof is coated with a thermoplastic resin layer, such as a copolymer of ethylene and vinyl acetate. This laminated tape 2 is washed, and then in a molding device 4, the laminated tape 2 is formed into a circular cross-sectional cylinder having an axis in the longitudinal direction by overlapping both side edges of the laminated tape 2 with the thermoplastic synthetic resin layer on the outside. Form into body 5. FIG. 4 shows the state of forming the tape 2 in the 4 parts of the forming apparatus. Subsequently, in the melt bonding device 6, the thermoplastic synthetic resin layers of the overlapped portions of the laminated tape 2 are melted by heating means to fuse the overlapped portions. At this time, at the positions of the forming device 4 and the melt bonding device 6, there are both ends having an outer diameter that is approximately the same as the inner diameter of the cylinder 5 and a slightly smaller diameter, and an intermediate portion smaller than the outer diameter of both ends, and a central portion in the longitudinal direction. A metal cylindrical molding tool having gas flow holes is disposed in the holder. On the outer surface of both ends of the cylindrical forming tool, a release layer such as Teflon, which has a small coefficient of friction, is vapor-deposited or attached to the outer surface of both ends of the cylindrical molding tool to prevent scratches on the metal tape surface inside the cylindrical body during manufacture of the cylindrical body. be. The cylindrical body 5 is formed by the forming device 4 so that the laminated tape 2 is wrapped around the surface of the large diameter portion at one end of the cylindrical forming tool.
Next, in the melt bonding device 6, the thermoplastic resin layer at the overlapped portion of the laminated tape 2 is melted by a heating means such as a hot jet placed at the middle of the cylindrical molding tool, and the overlapped portion is fused. Then, sufficient pressure is applied to the overlapping portion from the outside using the large diameter portion on the other side of the cylindrical forming tool.

Furthermore, by inserting air into the gas flow hole of the cylindrical forming tool and adjusting the pressure of the air, internal pressure is applied to the cylindrical body after the protective coating has been extruded, and the shape of the cylindrical body is changed by rapidly cooling the protective coating. Prevent flattening.

The cylinder 5 thus obtained is formed into a cylinder 8 having an elliptical cross section in a molding device 7 using a die or a roll. At this time, the laminated tape is formed so that the edge of the laminated tape located inside the overlapping portion of the laminated tape is located near the short axis in the cross section of the cylinder 8. By locating the laminated tape edge located inside the laminated tape overlapping part near the short axis of the cross section of the cylindrical body, when transmitting the fundamental mode, it is possible to vertically cross the metal tape edge located inside. The wall current that occurs is equal to zero, resulting in a waveguide with no external radiation due to wall current that crosses the metal tape edge perpendicularly. Next, a protective coating 91 made of polyethylene or the like is applied as an outer layer to a uniform thickness by an extrusion device 9 onto the cylinder 8 formed by the molding device 7.
Protective coating for thermoplastic synthetic resin layer of laminated tape 91
The protective coating is fused with heat during extrusion to give the thin metal tape mechanical strength, and then the protective coating 91 is cooled in a cooling device 13 such as a cooling water tank to produce the waveguide 10. Protective coating 91 in cooling device 13
When cooling the elliptical waveguide 10 made of a release material such as Teflon, the elliptical waveguide 10 is placed inside the elliptical cylinder 8 in the part of the cooling water tank where the extruded protective coating 91 rapidly shrinks due to heat, as shown in FIG. For example, an elliptical columnar body E having a similar shape to the inner circumferential elliptical shape and a slightly larger outer circumference is arranged. The front end of this elliptical columnar body E is tapered so as to be slightly tapered, and this tapered portion first comes into contact with the inner surface of the ellipsoidal columnar body 8, and the ellipsoidal cylinder 8 is connected to the elliptical columnar body E. By moving along the ellipsoidal cylinder 8, the ellipsoidal cylinder 8 is slightly expanded at the ellipsoidal columnar body E. By pushing and expanding the elliptical cylinder 8 with this columnar body E, it is possible to eliminate misalignment, flapping, or peeling of the overlapped portions of the laminated tapes, and to ensure that both overlapped edges of the laminated tapes are tightly aligned. An elliptical waveguide 10 that can be brought into contact and whose overlapping portions are completely fused in the length direction is obtained. This waveguide 10
is taken up by the take-up device 11, and the winding drum 1
The waveguide 10 is continuously manufactured by winding the waveguide 10 into two.

As is clear from the above description, according to the present invention, a laminated tape is formed into a cylindrical body using a cylindrical molding tool, the overlapped portions of the laminated tape are fused, a protective coating is extruded, and then cooled to form an elliptical shape. In the method of manufacturing a waveguide, when cooling the protective coating, the cylindrical body has an outer periphery that has the same shape as the inner periphery of the elliptical waveguide but is slightly larger, and its tip is slightly tapered. By positioning the tapered columnar body in the area, it is possible to prevent the edges of the laminated tape from shifting due to heat shrinkage of the protective coating that occurs when the extruded protective coating is cooled, and to prevent the phenomenon of flaking or peeling of the inner tape edge of the overlapping part. This makes it possible to obtain an elliptical waveguide with high dimensional accuracy and excellent flexibility, and also with good fusion at the overlapped portion of the laminated tape, resulting in an elliptical waveguide with good electrical properties. .

Note that although an elliptical columnar body is used as the columnar body, the pulling force can be reduced by providing recesses at locations other than the vicinity of the major axis and minor axis to reduce the contact area with the elliptical cylinder.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing process of the present invention, FIG. 2 is a cross-sectional view of a cooling device portion of the present invention, FIG. 3 is a perspective view of a columnar body, and FIG. 4 is a state diagram of tape forming.

Claims (1)

[Claims] 1. A laminated tape with one or more thermoplastic synthetic resin layers on at least one side of a metal tape is formed into an elliptical cylinder having continuous overlapping parts in the longitudinal direction, and a protective coating is applied on the elliptical cylinder. In a method for manufacturing an elliptical waveguide, which involves extrusion coating and then cooling,
When cooling the protective coating on the elliptical cylinder, the elliptical cylinder has an outer periphery similar in shape to the inner periphery of the elliptical waveguide but slightly larger in size, and its tip is slightly tapered. By arranging the tapered columnar body in a floating state inside the ellipsoidal cylinder inside the cooling device, the heat shrinkage force of the protective coating that occurs when the extruded protective coating is cooled is supported from the inside. A method for manufacturing an elliptical waveguide characterized by: