Views:17 Author:Site Editor Publish Time: 2018-03-07 Origin:Site
Screw and barrel These two parts of the combination of work quality, the material of plasticizing, product quality and production efficiency, have important influence. Their working quality is related to the manufacturing accuracy and assembly clearance of two parts. When 20 pieces of wear is serious and the output of extruder decreases, the maintenance of screw and barrel should be arranged.
The causes of screw and barrel damage
1, screw in the barrel rotation, materials and the friction between the two, so that the work surface of the screw and the cylinder gradually wear: screw diameter gradually reduced, the barrel diameter of the hole gradually increased. In this way, the diameter gap between the screw and the barrel is increased slightly with the gradual wear of the two. However, as the barrel Front head and the resistance of the shunt plate has not changed, this increase in the extrusion material forward when the leakage flow, that is, the material from the diameter gap in the direction of the flow of material increase. As a result, the output of extruder decreased. This phenomenon also makes the material in the barrel of the stay time increases, resulting in material decomposition. In the case of polyethylene, the hydrogen chloride gas produced by decomposition strengthens the corrosion of the screw and barrel.
2, materials such as calcium carbonate and glass fiber filler, can speed up the screw and barrel wear.
3, because the material is not plasticized evenly, or have a metal foreign body into the material, so that the screw rotation torque force suddenly increased, this torque exceeds the strength limit of the screw, so that the screw torsion. This is a very bad accident.
Second, screw repair
1, the broken screw should be based on the actual diameter of the barrel to consider, according to the normal gap with the barrel of the new screw to make the outer diameter deviation.
2, wear screw diameter reduction of the thread surface after treatment, thermal spraying wear-resistant alloy, and then by grinding to size. This method generally has a professional spraying factory repair, the cost is relatively low.
3, in the wear screw thread part surfacing wear-resistant alloy. According to the screw wear degree surfacing 1~2mm thick, and then grinding screw to size. This kind of wear-resistant alloy is composed of C, Cr, Vi, Co, W and b materials, which can increase the abrasion resistance and corrosion resistance of the screw. Professional surfacing plant for this kind of processing costs very high, in addition to the special requirements of the screw, generally rarely used.
4, repair screw can also be used on the surface of hard chromium plating method, chromium is also wear and corrosion-resistant metal, but hard chromium layer is easier to fall off.