JPS6031122B2 - Manufacturing method of conductor tube with spiral waves for high frequency transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a conductor tube with spiral waves used for high frequency transmission lines such as waveguides and coaxial cables.

The waveguides that make up the high-frequency transmission line, and the inner and outer conductors of coaxial cables are required to be flexible for ease of installation.
A corrugated conductor tube is used.

Corrugated conductor tubes can be roughly divided into two types: corrugated extruded smooth tubes pressed with an aluminum press, or metal tapes formed into a cylindrical shape in the longitudinal direction and welded together at the joints of the tape twills. It is manufactured by forming a seamed smooth tube and then corrugating the seamed smooth tube. Among these methods, the method using extruded smooth tubes has the disadvantage that the material is limited to aluminum, whereas the method using seamed smooth tubes does not limit the material to aluminum, but can also use copper, iron, steel, stainless steel, etc. The manufacturing of corrugated conductor tubes has the advantages of being able to select the appropriate material, being able to use steel plates and composite materials such as steel plates that satisfy electrical properties and mechanical strength at the same time, and being able to manufacture tubes at low cost. The method of using a seamed smooth tube is becoming popular. The present invention relates to an improved manufacturing method for forming a corrugated conductor tube by forming a metal tape into a cylindrical shape. Hereinafter, a conventional method of manufacturing a seamed corrugated tube and its drawbacks will be explained.

Conventionally, seamed conductor tubes have been manufactured by the method shown in FIG.

That is, the metal strip 1, which has been washed, dried, and has both green parts cut to the same size, is given a predetermined bend by the forming device 4 and sequentially formed into a cylindrical shape, and then the mated twill parts are welded by the welding device 5. A smooth cylindrical body 2 is formed. Next, the smooth cylindrical body 2 is taken up by a taking-off device 6 comprising clamps having inner surfaces that are in close contact with the outside surfaces of the cylindrical bodies and arranged facing each other at intervals on a chain, and fed into a corrugating device 7.

The corrugating device 7 is a corrugating link that is eccentric from the central axis of the smooth cylindrical body 2 by an appropriate amount and has a predetermined inclination with respect to the central axis. Apply waving. Here, the smooth cylindrical body 2 is corrugated in a spiral manner. Here, the smooth cylindrical body 2 becomes a spirally corrugated tube 3 and is then wound onto a take-up drum 8. The corrugated conductor tube manufactured by the above-mentioned method has sufficient mechanical properties and portability as a general cable sheath, but as a conductor tube for inner and outer conductors for waveguides and coaxial cables.
It is not always possible to obtain sufficient performance.

In other words, when transmitting high-frequency signals in the microwave band using waveguides or coaxial cables, if there is a periodic non-uniformity in the transmission line that is on the order of the wavelength of the transmission frequency band or an integral multiple of the wavelength, minute reflections occur at specific frequencies. The accumulation of these causes a significant deterioration of the voltage standing wave ratio, making high-quality transmission of that frequency impossible.

For this reason, waveguides and coaxial cables for high-frequency transmission lines are required to have extremely small periodic fluctuations in the longitudinal direction and excellent uniformity. In the above method, the corrugation of the smooth cylindrical body 2 in the corrugation device 7 is carried out by rotating the corrugation ring itself at a predetermined rotational speed with the center of the corrugation ring itself being offset by an appropriate amount from the central axis of the smooth cylindrical body 2. by the way,
In order to obtain a predetermined wave shape, that is, a predetermined wave depth, wave pitch, and wave curve shape, the longitudinal speed meter 2 and the pulling speed of the tensioning device 6 during wave formation by the wave forming device 7 must be adjusted. It is necessary to process them so that they match perfectly, and this adjustment is extremely difficult, and even a slight mismatch tends to cause periodic fluctuations in pitch.

Further, the corrugating ring rotates on its own axis so as not to slide on the surface of the smooth cylindrical body 2 during corrugation. Therefore, in order to create a cylindrical body with uniform corrugations in the length direction, the corrugated ring must have roundness, and if the inner shape of the corrugated ring is distorted,
If there is unevenness in the rotational state, periodic unevenness will occur every few pitches of the waves due to the existence of the rotation period of the corrugation link itself and the rotation period of the corrugation ring relative to the smooth cylindrical body.
A spirally corrugated conductor tube for a high frequency transmission line has the disadvantage of deteriorating transmission characteristics. Further, the pulling device 6 holds the smooth cylindrical body 2 with clamps arranged oppositely at appropriate intervals, and takes the smooth cylindrical body without slipping by overcoming the resistance force generated during molding and the resistance force generated during corrugation. For,
The smooth cylindrical body is tightly held by the clamps, and it is inevitable that slight deformation will occur at each clamp interval, which will also deteriorate the high frequency transmission characteristics of the spirally corrugated conductor tube for high frequency transmission lines. Therefore, it is inappropriate. Therefore, in view of the drawbacks of the above-mentioned follow-up method, the present invention aims to form a smooth cylindrical body by welding both edges of a metal strip formed in a cylindrical shape, and then forming a spiral wave pattern on the smooth cylindrical body. In the method for manufacturing a corrugated conductor tube, the smooth cylindrical tube is first guided to a twist prevention device that prevents twisting around the axis but holds the tube so that it can be moved in the longitudinal direction, and then the smooth cylindrical tube is The smooth cylindrical tube is guided to a corrugating device equipped with a die box and a spiral die housed in the die box, and the die box is driven to rotate, thereby corrugating the smooth cylindrical tube. An object of the present invention is to provide a method for manufacturing a spirally corrugated conductor tube for a high frequency transmission line, which is characterized in that the tube is transported in the longitudinal direction at the corrugation speed of a spiral die while applying corrugation. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a method of manufacturing a seamed corrugated elliptical waveguide according to one embodiment of the present invention. FIG. 3 is a sectional view showing the detailed structure of the corrugating device of the present invention. The metal strip 11, which has been washed, dried, and has both edges trimmed, is given a predetermined bend by a forming device 14 and sequentially formed into a cylindrical shape, and then the mated green portions are welded by a welding device 15. A smooth cylindrical body 12 is formed.

The cylindrical body 12 passes through a twist prevention device 16 and is corrugated in a spiral manner by a corrugation device 17. The corrugating device 17 includes a die box 22 driven by a power source (not shown) and a spiral die 21 housed in the die box. The spiral die 21' is made of tool steel and has two pitches of spiral peaks and valleys on its inner surface, and the first pitch gradually gives a predetermined pitch and depth for corrugation, and the next pitch gives the wave a predetermined pitch and depth. The corrugation of the attached tube is processed with high precision to finish the corrugation to a predetermined dimension, and the die box 2 is aligned with the center axis of the smooth cylindrical body 12.
It is installed within 2. The die box 22 is driven without moving in the sleeve direction of the tube and gives a rotational motion to the spiral die 21. As a result, when the spiral die 21 corrugates the smooth cylindrical body 12, it also corrugates the corrugated cylindrical tube 13. is sent out in the longitudinal direction of the pipe. The corrugated cylindrical tube 13 is compressed and deformed when passing through a set of two roll forming devices 20 that give a predetermined deformation to the tube and is processed into a corrugated elliptical waveguide 101. It is wound up. The torsion prevention device 16 in the figure is a caterpillar-type torsion prevention device that can rotate freely, and after the caterpillar holds the smooth cylindrical pipe by an air spring using compressed air, it follows the movement of the smooth cylindrical body. .

In the method of the present invention, if there is no twist prevention device 16, the force that twists the smooth cylindrical tube 12 generated during spiral corrugation by the corrugation device 17 will be transmitted to the welding point, causing the abutted edges to expand or In the present invention, it is essential to prevent twisting of the smooth tube because the position of the green part may shift from directly under the welding machine, making uniform welding impossible. In addition, the above-mentioned spiral die 21 is used to simultaneously carry out corrugation and take-off when sequentially forming a metal body into a cylinder, and to transport the corrugated cylindrical tube after corrugation. The above operation can be carried out in the above manner, and a seamed corrugated conductor tube having sufficient high frequency characteristics can be obtained. A smooth cylindrical tube with a diameter of 43 ribs was produced by cylindrical molding using a copper tape with a thickness of 0.5 ribs according to the method of the embodiment shown in Fig. 2. After that, it was corrugated and formed into an oval shape with a diameter of 523 skin and a short diameter of 26. When we manufactured the side elliptical waveguide, we obtained a voltage standing wave ratio of 1.05 or less within the transmission band (5.0 to 6.50).In contrast, by the conventional method shown in Fig. When a four-circle bridge waveguide of the same size was manufactured by corrugating and elliptically forming a smooth cylindrical tube of the same size using the same material, the voltage standing wave ratio within the transmission band was 1. Several peaks occurred at the peak.

In the above embodiment, a caterpillar-type torsion prevention device is used as the torsion prevention device, but instead of the caterpillar, a torsion prevention device using a belt or clamp with a structure capable of pinching the cable may be used. . Furthermore, a caterpillar-type pulling device, a belt-type pulling device, a clamp-type pulling device, etc. can also be used as appropriate by allowing the cable to be held while the drive wheels of the pulling device are idled without being driven by power. In this case, it is only necessary to apply a pressing force sufficient to prevent twisting of the smooth cylindrical body held by either pulling device. . As is clear from the above explanation, according to the manufacturing method of the present invention, the corrugation and transport of the tube are performed using a spiral die, so the longitudinal direction traveling speed during corrugation and the take-up feed rate are adjusted to match. There is no need to do so, and there is no need for periodic slight deformation caused by being tightly held by the clamp of the pulling device.

In addition, since the spiral die of the present invention has the functions of corrugation forming and adjusting the pitch interval, it is possible to prevent the inner shape from being slightly distorted from being a perfect circle like the corrugated ring in the secondary method, or to rotate. There is no periodic non-uniformity in waves every few pitches, which occurs when conditions are uneven. Therefore, the seamed corrugated conductor tube obtained by the method of the present invention has extremely excellent uniformity in the longitudinal direction, making it possible to economically manufacture waveguides and coaxial cables with excellent characteristics. In this respect, it is a great contribution to the industry.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional method for manufacturing a corrugated conductor tube with a seam, FIG. It is a sectional view showing the detailed structure of the corrugation device in the invention. 11 is a metal band, 12 is a smooth cylindrical body, 13 is a corrugated conductor tube,
16 is a twist prevention device, 17 is a corrugating device, and 21 is a spiral die. Figure* Figure 3

Claims (1)

[Claims] 1. A method for manufacturing a corrugated conductor tube in which both edges of a metal band formed in a cylindrical shape are brought together and welded to form a smooth cylindrical body, and then the smooth cylindrical body is corrugated in a spiral manner. The tube is first guided to a twist prevention device that clamps the tube to prevent twisting around the axis but to allow movement in the longitudinal direction, and then to a die box that is arranged so that the central axis of the smooth cylindrical tube coincides with the tube. and a helical die housed in the die box, and by rotating the die box, the smooth cylindrical tube is corrugated, and at the same time, the tube is longitudinally waved at the corrugation speed of the helical die. 1. A method for manufacturing a conductor tube with spiral waves for a high frequency transmission line, characterized in that the conductor tube is moved in a direction.