Improper Operation Caused The Damage Of Screw And Barrel
Improper operation caused the damage of Screw and Barrel
Cause of damage of Screw and Barrel
1. The screw is rotated inside the barrel, and the friction between the material and the two is gradually worn down on the working surface of the screw and the cylinder: the diameter of the screw is gradually reduced, and the diameter of the inner hole of the cylinder is gradually increased. In this way, the diameter gap between the screw and the cylinder is increased with the gradual wear and tear of the two. , however, because of the barrel in front of the nose and shunt plate resistance has not changed, which adds to the forward extrusion material leakage flow, the material feeding direction from diameter clearance flow has increased. The result is that the production of extruder is reduced. This kind of phenomenon causes the material to stay in the cylinder for more time, resulting in the decomposition of materials. If it is polyethylene, the decomposition of hydrogen chloride gas enhances the corrosion of the screw and barrel. 2. Materials such as calcium carbonate and glass fiber fill materials can accelerate the wear of screw and cylinder.
Because the material is not plasticized, or in the mixture of metal and foreign material, the torque force of the screw is increased suddenly, the torque exceeds the strength limit of the screw and causes the screw to twist. This is a kind of irregular accident
Repair of Screw and Barrel
1. The twisted screw should be considered according to the actual inner diameter of the cylinder, and the outer diameter deviation of the new screw is made according to the normal clearance of the cylinder.
2. After treatment of the threaded surface of the reduced screw diameter, the thermal spraying wear-resistant alloy is then machined to the size. This method usually has professional spraying factory to process repair, the cost is relatively low
3, to weld wear-resistant alloy in the threaded part of the worn screw. According to the degree of the screw wear to the degree of welding 1 ~ 2mm thick, then grinding the screw to the size. This wear-resistant alloy is composed of C, Cr, Vi, Co, W and B, which can increase the wear resistance and corrosion resistance of the screw. Professional surfacing plant is very expensive for this kind of processing, except for the special requirement of screw, seldom used.
4. The repair screw can also be used for surface plating hard chromium, which is also abrasion resistant and anti-corrosion metal, but the hard chromium layer is easy to fall off. Repair of the cylinder
The inner surface of the cylinder is higher than the screw, and its damage is much later than the screw. The failure of the cylinder is the diameter of the diameter due to the time wear. Its repair methods are as follows:
1, because wear increases, the diameter of the barrel, if there is a certain of nitriding layer, can be boring, the barrel inner hole directly grinding to a new diameter size, and then according to the diameter of the new screw.
2. The inner diameter of the machine can be machined and recast, and the thickness is between 1 ~ 2mm and then finished to the dimension.
3, in general, the plane homogenization of cylinder wear faster, but will take 5 ~ 7 d (long) this paragraph by boring nap, match again a nitriding steel bushing, Screw and Barrel diameter of bore with reference to the screw cylinder diameter, stay in normal fit clearance, carry on the processing preparation.
The adjustment of process during the production of screw rod is the necessary way to improve product quality and yield. Because the injection cycle itself is very short, if the process condition is not good, the waste will be endless. In the adjustment process, change one the best conditions for observation a few times more, if the pressure, temperature, time, all together, very easy to cause confusion and misunderstanding, Screw and Barrel is out of the question and I don't know dangyang. The measures and means of the adjustment process of double alloy screw are multifaceted.