1. Principle and notice of screw barrel innovation
After the screw barrel has been used for a period of time, the screw rib and the nitriding layer of the barrel (when making a new screw, the screw and the barrel will stop nitriding heat treatment, so there will be about 30-60 oxidation layers on the surface) will be worn in two directions, the gap between the two sides will increase, leading to local backflow of plastic, production and plasticizing effect drop. Screw innovation is to increase the thickness of the screw rib on the old screw and fill Fill the gap to increase the output.
At present, there are mainly three innovative ways in China:
(1) Electric welding: electric welding with alloy electrode (20-30 yuan / kg)
Defects: it is not wear-resistant, prone to appear faulty welding, the appearance is not lubricated, there will be sand holes, particles will stay in the screw, resulting in small yellow coke blocks and black spots.
(2) Spray welding: spray alloy powder with special "acetylene oxygen" spray gun (30-50 yuan / kg)
Defects: it is not wear-resistant, with sand holes, partial incomplete condensation of alloy in spray welding process, and alloy powder will come out with the material in the process of use, causing material leakage and die head damage
(3) Overlaying welding: use "acetylene oxygen" to completely condense 300 yuan / kg imported alloy electrode on the screw
Advantages: due to condensation, there is no false welding and sand hole.
2. Can the cylinder not be nitrided?
Can not! When making a new barrel, the barrel will stop the nitriding treatment. The thickness after treatment is about 40-50 wires. When the first screw is worn out, the barrel is also worn, with different levels. However, if the output falls fiercely, the nitriding layer of the barrel will not exceed 20c (wire), and the thickness of the nitriding layer of each barrel is different. Therefore, some innovation factories make innovations for the first time It can be used for more than half a year, but it can't be used for the second time for three months. The reason is that there is a little thickness of nitriding layer in the first time, so it can be used for more than half a year, and the nitriding layer will be completely gone in the second innovation, so it won't be used. Whether the cylinder can stop nitriding heat treatment is the key to ensure the use time of screw cylinder! Some innovation factory in order to save money, do not stop nitriding heat treatment of the barrel!
3. How to distinguish whether the cylinder can be nitrided?
After nitriding heat treatment, the color of the barrel will become gray white with texture, which is different from the rusty color before it is made. Some factories cheat people to burn it with fire. It is pure black without texture. A barrel can stop nitriding heat treatment for up to 4 times. Because the iron of the barrel has changed, the internal structure has been changed. There is no nitriding furnace in the center where machinery and hardware are not prosperous because it takes 1200 screw barrels to start the furnace at a time. Only in Shunde, Zhongshan, Guangdong Province, can there be nitriding furnace! Any innovative factory, if it doesn't stop nitriding the barrel, the absolute time is not as long as the nitriding treatment. If the old screw barrel is the first time to make innovation, the barrel doesn't stop nitriding treatment, the time used depends on the original wear level of the barrel! Therefore, the quality of the innovative factory which did not stop the nitriding treatment of the barrel is not stable. Some of them are used for a long time and some of them are not used for a long time. This is why! The old barrel material determines the application time.
4. What is the wear level of barrel and screw?
The wear level of barrel and screw is different for each set of barrel. Different materials wear different, generally speaking, because the screw is active and the friction position is the screw edge, the friction area of the screw edge is smaller than that of the barrel, so the wear level of the screw is larger. The wear level of the common screw is 3:1 compared with that of the barrel, but if the material hardness of the screw far exceeds that of the barrel, then the barrel is more worn!