Copper braided tape soft connection on G-M refrigerator
The low temperature system of cryocoolers of G-M refrigerator adopts the method of adding copper braided belt soft connection in the heat transfer module for flexible heat transfer and three-stage vibration reduction, so as to reduce the vibration amplitude of sample seat and ensure the heat transfer efficiency at the same time. At present, the vibration reduction method of G-M refrigerator mainly adopts passive vibration reduction, and the vibration between the cold head and the sample seat is isolated by soft connection of flexible copper strip.
At present, there are three soft connection processes of copper braided tape: screw connection, welding and interference cold pressing. (1) The screw connection method is to tighten and shape multiple strands of oxygen free high conductivity copper strips and fasten them between the secondary cold head and the sample seat through bolts. This method does not change the characteristics of the copper strip, the process is relatively simple, the yield is high and easy to replace, but soft metal needs to be padded to increase the contact area. At the same time, the compression force of the screws is relatively small and human factors have a great impact. (2) The welding method is to bind and shape multiple strands of oxygen free high conductivity copper strips, and then fasten them between the secondary cold head and the sample seat through vacuum brazing. This method does not need soft metal pad, and the connection is more firm. However, the high temperature in the welding process will lead to the oxidation of copper braided strips and affect the heat transfer efficiency. (3) After the multi strand oxygen free high conductivity copper strip is tightened and precisely shaped by interference cold pressing, it is firmly between the secondary cold head and the sample seat by extrusion, which can solve the problem of decreasing heat transfer efficiency in the traditional soft connection process. This method does not change the characteristics of copper braided belt, has no soft metal cushion, and has higher heat transfer efficiency.
At present, there are three soft connection processes of copper braided tape: screw connection, welding and interference cold pressing. (1) The screw connection method is to tighten and shape multiple strands of oxygen free high conductivity copper strips and fasten them between the secondary cold head and the sample seat through bolts. This method does not change the characteristics of the copper strip, the process is relatively simple, the yield is high and easy to replace, but soft metal needs to be padded to increase the contact area. At the same time, the compression force of the screws is relatively small and human factors have a great impact. (2) The welding method is to bind and shape multiple strands of oxygen free high conductivity copper strips, and then fasten them between the secondary cold head and the sample seat through vacuum brazing. This method does not need soft metal pad, and the connection is more firm. However, the high temperature in the welding process will lead to the oxidation of copper braided strips and affect the heat transfer efficiency. (3) After the multi strand oxygen free high conductivity copper strip is tightened and precisely shaped by interference cold pressing, it is firmly between the secondary cold head and the sample seat by extrusion, which can solve the problem of decreasing heat transfer efficiency in the traditional soft connection process. This method does not change the characteristics of copper braided belt, has no soft metal cushion, and has higher heat transfer efficiency.
