JPS5918508A - Method of producing forcible cooling type superconductive conductor electrically insulating joint - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to a method for manufacturing an electrically insulating joint that is inserted between a forced cooling superconducting conductor and a refrigerant supply pipe.

Conventional technology There are two methods for cooling superconducting coils: 1) immersing the entire coil in a refrigerant such as liquid helium, and 2) forming the conductor into a pipe and circulating the refrigerant within it. In this method, it is necessary to provide electrical insulation between the conductor and the piping system that supplies refrigerant to it, so metal pipes that are connected to the conductor and the supply pipe are usually placed on both sides of the ceramic sleeve. Bonded insulating fittings are used.

Generally, such insulated joints are required to withstand this pressure at extremely low temperatures because the refrigerant is flowed at a pressure of 10 atmospheres or more.For this reason, conventionally, a part of the metal pipe is placed inside an insulating sleeve. A method is used in which the joint surfaces of the two are fitted and brazed to ensure the mechanical strength and sealing function of the joint.

C. Problems to be Solved by the Invention However, since the temperature of brazing is extremely high at 800°C or more, if the brazing method is used, the difference in thermal expansion between the insulating sleeve and the metal tube will be large; Because a portion of the sleeve is inserted inside the sleeve, excessive force is applied and the sleeve often breaks, and even when it does not break, the sleeve is susceptible to thermal deterioration.

Additionally, brazing usually requires heating under high vacuum for a long time to melt and blend the wax that has been placed on the surface to be bonded, but this requires considerable effort.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing an electrically insulating joint that does not cause damage or deterioration of the insulating sleeve and has excellent workability.

2. Means for solving the problem This invention uses a known ultrasonic soldering iron to form a solder plating layer on the adhesive surface of the insulating sleeve in advance, and then fits the metal tube to the insulating sleeve. The gist of this method is to heat this to the melting point of the solder (approximately 250°C ± 50°C) and join them together. According to this method, the low joining temperature prevents thermal expansion between the sleeve and the metal tube. The difference is suppressed to a small range, thermal deterioration of the sleeve is reduced, and workability is improved.

E, Example Hereinafter, the present invention will be described in detail based on the accompanying drawings.

First, as shown in Fig. 1, a ceramic insulating sleeve 1 having a stepped hole and a large diameter hole 2 of this sleeve have the same diameter and a flange 3.3' that is joined to the outer periphery of the sleeve at the end of the sleeve.
A stainless steel pipe 4.4' was prepared, and a solder plating layer 6 was formed on the end surface 5 of the sleeve 1 and the inner surface of the large diameter hole 2 using an ultrasonic soldering iron. Half 11 used at this time was used exclusively for ultrasonic soldering and had a melting point of 263°C. After that, insert the tip of the pipe 4 into the large diameter hole of the sleeve, butt the adhesive surfaces of both, and hold the whole in the atmosphere for about 30 minutes.
Heated to 0°C±20°C. Also, once the solder had melted, I added a small amount of solder to the joint around the flange by melting it with a soldering iron. Then, let it cool naturally in the atmosphere.
Finished the hand.

Next, as shown in FIG. 2, one pipe 4 of the above-mentioned joint is welded to a copper pressure pipe 8 connected to a helium gas cylinder 7, and a blind lid 9 is attached to the other pipe 4'. A copper pipe 10 having the following properties was welded. After that, this sample was immersed in liquid nitrogen, and the valve 11 of the cylinder 7 was opened to give 15 kyu.
After pressurizing to /aA, the valve 12 was closed and a 24-hour leak test was conducted using the pressure gauge 12. As a result, there was no change in the sealing pressure and no cracking of the sleeve.
It was confirmed that the conditions as an insulating joint for superconducting conductors were fully satisfied.

As explained above, according to the present invention, the insulating sleeve and the metal tube are joined at low temperature, so there is no damage to the sleeve due to the difference in thermal expansion, and there are almost no defective products.

Furthermore, since the sleeve is bonded at a low temperature, there is no thermal deterioration of the sleeve, which increases its mechanical strength.

Furthermore, since solder is used, it is possible to work in the atmosphere, which simplifies the manufacturing process of the joint.

Note that the same effect can be obtained even if the insulating sleeve is made of glass.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the method of the present invention, and FIG. 2 is a diagram showing the IJ-cut state of the insulation joint obtained by the method of the present invention. 1... Insulating sleeve, 3... Flange, 4... Stainless steel pipe, 6... Solder plating layer Patent applicant: Sumitomo Electric Industries, Ltd. Agent: Kama 1) Text 2 Figure 1 2 Figure 2 2 Procedural amendment (drunk) ■, Small case indication 1987 Patent Application No. 128741 2, Title of invention Method for producing electrically insulating joints for forced cooling superconducting conductors 3, Person making the amendment Relationship with the case Patent applicant Address: 5-15 Kitahama, Higashi-ku, Osaka (Name: Wabi) (2)
13) Sumitomo Electric Industries, Ltd. 5゜Showa Year Month Day (shipment date) 6. The number of inventions will increase due to the amendment 7. The scope of the patent claims will be amended as per the attached sheet subject to the amendment. Claims: After a solder plating layer is formed in advance on the bonding surface of a glass or ceramic insulating sleeve by ultrasonic soldering, a metal tube is fitted onto the surface on which the plating layer is formed, and this is heated to the melting point of the solder. A method for manufacturing an electrically insulating joint for a forced cooling superconducting conductor, which consists of liquid-tightly joining an insulating sleeve and a metal tube.

Claims (1)

[Claims] For glass, a solder plating layer is formed in advance on the adhesive surface of a ceramic insulating sleeve using ultrasonic soldering, a metal tube is fitted onto the surface on which the plating layer is formed, and this is heated to the melting point of the solder to bond the insulating sleeve to the metal. A method for manufacturing an electrically insulating joint for forced cooling superconducting conductors, which consists of liquid-tightly joining pipes.