Method for manufacturing copper-aluminum welded joint of capillary tube and copper end sleeved aluminum capillary tube

Abstract

A method for preparing a copper-aluminum welded joint of a capillary comprises: inserting an inner core (3) into a copper capillary (2), the inner core (3) being exposed at two ends of the copper capillary (2); using a precision roll forging machine to perform conical head processing on one end of the copper capillary (2) and reducing the wall thickness of the copper capillary (2), and at this time, the inner core (3) getting stuck at the conical head; preassembling the conical head end of the copper capillary (2) with the inner core (3) in an aluminum capillary (1); and drawing out the inner core (3) after welding. The present invention also relates to a sleeved copper-end aluminum capillary prepared by the method. In the copper-end aluminum capillary prepared by the method, the gap between the contact portions of the copper tube and the aluminum tube is quite small, so that no aluminum bead is produced, and the flow in the capillary is not affected.

Description

technical field [0001] The invention relates to a method for preparing a welded joint, in particular to a method for preparing a capillary copper-aluminum welded joint; the invention also relates to a sleeve-type copper-end aluminum capillary prepared by the method. Background technique [0002] At present, copper resources are in short supply, but the performance of aluminum is the closest to that of copper, and the output is abundant. Therefore, replacing copper tubes with aluminum tubes has become one of the most effective means for saving copper resources and reducing product manufacturing costs in the refrigeration industry. The scale of replacing copper with aluminum in refrigeration products is also increasing. In the refrigeration system, evaporators, return air pipes, condensers, dew pipes, and piping in the system have successively realized aluminum instead of copper. Capillary tubes are an essential system function for refrigeration products. One of the components...

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Problems solved by technology

[0003] Capillary is a kind of pipeline with relatively thin inner diameter. At present, copper tubes with an inner diameter of 0.5-0.7mm are used in the refrigerator industry; copper tubes with an inner diameter of 0.7-2.0mm are used in the air-conditioning industry. Due to the small inner diameter of the capillary, welding spatter will If the pores are blocked and cannot be removed, it cannot be completed by friction welding, energy storage welding, flash butt welding and other welding methods that are prone to spatter; the brazing method of flared connection needs to be socketed at one end of the connecting pipe. , the thin diameter exceeds 20mm to ensure that there is no welding blockage, and the thin diameter deep flaring cannot be realized, so brazing cannot complete the welding of thin diameter copper-aluminum tubes. For the same reason, the brazing method cannot complete the copper capillary connected by flaring. Or aluminum capillary tube, in summary, the current technology cannot realize capillary copper-aluminum tube welding

[0004] The existing sleeve extrusion resistance welding technology adopts the method of inserting copper tubes into aluminum tubes for welding and flaring after welding. Although a dense pipeline joint structure can be obtained, the inner diameter of copper-aluminum pipe fittings suitable for this welding method must be Greater than 2.0mm, the inner diameter of the capillary is less than 2.0mm, the above method cannot realize the copper-aluminum welding of the capillary

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