In the 1970s, the development of internal threaded copper coils and hydrophilic aluminum foil for condensers and evaporators, to industrial mass production after 20 years. 1969 the United States first appeared in the threaded core head rotary forging method of processing internal threaded copper tubes, and later appeared in Japan, the cable threaded core head roller spinning method, the core head from a single threaded core head for the development of the combination of the core head. 80's Japanese Mitsubishi copper, Kobe Steel and Valley River Electric and other companies to do a lot of research on the drawing method from the roller spinning gradually to the development of ball spinning process into a hot early 1990s. Mitsubishi copper, Kobe Steel and Valley River Electric and other companies have done a lot of research on the drawing method, from the roller spinning forging gradually to the development of ball spinning, in the early 90's formed into a hot ball spinning molding process.
China's internal threaded copper pipe processing of high-speed ball spinning process research more for Japan's Kobe Steel and Valley River Electric two companies, these two companies to drive the steel ball rotating spin die materials and steel ring and steel ball contact area design, lubrication conditions to improve the development of new types of small-diameter, large helix angle of the internal threaded pipe, spinning die speed to improve a lot of research. China in the 1980s before the air conditioning heat exchanger used copper tube for light tube. 80 years later, China's air conditioning industry rapid development, internal threaded tube gradually favored, which promotes energy saving, environmental protection, lightweight and miniaturization, high precision, high cleanliness, high efficiency of heat transfer, thin-walled, thin diameter, high concentricity of the rapid development of internal threaded tube. The development of internal threaded copper pipe has roughly gone through the following development stages: (1) mountain-shaped teeth internal threaded pipe; (2) trapezoidal groove internal threaded pipe; (3) small top-angle type of internal kerning; (4) fine and high-toothed type of internal threaded pipe. From the 90's air conditioning also began to develop rapidly, internal threaded copper tube mainly rely on imports, to the end of the 90's, the domestic began to introduce the internal threaded copper tube drawing forming equipment and carry out independent research and development, to the beginning of this century, the internal threaded copper tube drawing forming method in the country has been widely used, and then, after the copper tube processing industry technicians innovation and improvement, the formation of the current mainstream process: planetary steel ball spinning-drawing method.
So far, the planetary ball spinning method is the main method for producing seamless copper tubes with internal threads. There are three main forms of equipment for processing internally threaded copper tubes using the planetary steel ball ultra-high-speed spinning internal thread forming process: (1) straight line stretch forming machine; (2) inverted vertical disk drawing forming machine; (3) V-shaped groove disc stretch forming machine.
Professor Tang Yong of South China University of Technology in China has done systematic experimental and theoretical research on lubrication and process. Proposed the use of liquid-filled spin forming process to improve the quality of the outer surface of the copper tube and reduce the drawing force. Some copper tube producers and equipment manufacturers have reported more on the internal threading process of copper tube spinning and forming, but most of them are based on experience and experiments.
With the development of air-conditioning industry, the internal threaded copper tube will gradually develop to thin-walled, fine diameter, high tooth and small tooth top angle. Considered from the tooling, the development trend of the internal thread forming machine has two main trends (1) the increase in spinning speed: it is estimated that with the emergence of new high-speed motors, the spinning speed will be increased from 20,000r/min to more than 30,000r/min, spinning is easier to become a tooth, the internal thread pipe tooth shape is fuller, more uniform texture, and better surface quality; (2) the refinement of the mold production. Through the improvement of molding wheel, the design and production of internal thread core head tooth item and tooth root curvature will be guaranteed. The gram weight per meter will be easier to control.
With the development of air-conditioning industry, there is no doubt that the demand for internal threaded copper tubes will be greatly improved, and the quality requirements for the internal threaded copper tubes themselves will also have a new height.
