Induction brazing method for sealing capillary tube

Abstract

The invention discloses an induction brazing method for sealing a capillary tube. The method successively comprises three steps: plugging; brazing wire inserting; and induction brazing. By adopting a technical scheme that a brazing wire is inserted into a cavity to remove most trapped air in the cavity, the brazing wire in the cavity is fused to liquid welding flux by way of electromagnetic induction heating, the liquid welding flux is cooled and cured to form a deeply plugging welding stud which fills the cavity, and the brazing wire is integrally quickly fused to fill the cavity to eliminate micropores by reducing the trapped air in the cavity through electromagnetic induction heating, the problems and defects that in the prior art, micropores are likely to generate, the capillary tube is not tightly sealed, the quality is different and the service life is short are overcome, so that for a thermostatic expansion valve product of an automobile air conditioner, purposes of eliminating the micropores, sealing the capillary tube tightly, gaining the consistent quality and prolonging the service life are achieved.

Description

technical field [0001] The invention relates to a capillary sealing method, in particular to an induction brazing method for capillary sealing of a capillary of the expansion valve after injection of working fluid for the production of thermal expansion valves of automobile air conditioners. Background technique [0002] The working medium is injected into the thermal expansion valve of the automobile air conditioner through the capillary tube. After injecting the working medium, the injection end of the capillary tube needs to be brazed and sealed. The existing technology uses an acetylene oxygen torch burning acetylene and oxygen to heat and melt the brazing wire. The brazing method is to braze and seal the injection end of the capillary, and the brazing method of heating and melting the brazing wire with an acetylene oxygen torch is referred to as wind brazing; refer to image 3 , There is a section of empty cavity left over from the capillary’s deflated plug to the inject...

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Problems solved by technology

[0002] The working medium is injected into the thermal expansion valve of the automobile air conditioner through the capillary tube. After injecting the working medium, the injection end of the capillary tube needs to be brazed and sealed. The existing technology uses an acetylene oxygen torch burning acetylene and oxygen to heat and melt the brazing wire. The brazing method is to braze and seal the injection end of the capillary, and the brazing method of heating and melting the brazing wire with an acetylene oxygen torch is referred to as wind brazing; refer to image 3 , There is a section of empty cavity left over from the capillary’s deflated plug to the injection end due to the process of injecting the working fluid, which is called the cavity; when the air brazing seals, the brazing wire melt cools at the injection end of the capillary to form a shallow plug During the process of welding bolts, the trapped air in the cavity will form small, penetrating, and difficult-to-detect micropores inside the shallow plugging welding bolt due to heat expansion and contraction. The micropores will cause slow leakage of the working fluid in the product, making the The quality of the products is different, and the service life of the products is shortened; in addition, air brazing requires a certain amount of semi-finished products to be sealed to be sealed at the same time, and the spare parts will leak during the process of accumulating and preparing semi-finished products, resulting in poor product quality; The required oxygen and acetylene are flammable and explosive, and there are hidden dangers of explosion; therefore, there are problems and deficiencies in the prior art that micropores are easily generated, the seal is not strict, the quality is different, and the service life is short

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