The principle and precautions of screw material cylinder renovation
Screw barrel after a period of time, screw the screw and the nitriding layer of the barrel (to do new screw and barrel will be nitriding heat treatment, thus the surface will have a 30--60 of the oxide layer around the wire is two-way wear, the gap between the two sides increased, leading to the return of plastic parts, production and plasticizing effect decreased, screw renovation is in the old screw to increase the thickness of the screw, to fill the gap to achieve the purpose of increasing production.
At present, there are mainly three kinds of renovation methods in China:
(1) Welding: Alloy welding electrode (30-40 yuan/kg) welding
Disadvantages: Not wear-resistant, more prone to virtual welding, surface is not smooth, there will be sand holes, granular material in the screw will appear to stay, resulting in the material will appear yellow Gio, black spots.
(2) Spray welding: The use of a special "acetylene-oxygen" spray gun alloy powder (40-50 yuan/kg)
Disadvantages: Not wear-resistant, there is sand hole, alloy in the process of spray welding part not completely melted, in the process will appear alloy powder with the phenomenon, resulting in leakage of material, die head damage
(3) Surfacing: Using "acetylene-oxygen" 400 yuan/imported alloy electrode completely melted on the screw
Advantages: Because of melting, so no virtual welding, sand hole phenomenon.
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