How to repair the damage to the screw and barrel of the rubber extruder
The twisted screw should be considered according to the actual inner diameter of the barrel, and the outer diameter deviation of the new screw should be given according to the normal gap with the barrel.
1. The twisted screw should be considered according to the actual inner diameter of the barrel, and the outer diameter deviation of the new screw should be given according to the normal gap with the barrel.
2. After the thread surface with the reduced diameter of the wear screw is treated, the wear-resistant alloy is hotly sprayed, and then it is ground to the size. This method is generally processed and repaired by professional spraying plants, and the cost is relatively low.
3. Overlay welding wear-resistant alloy in the threaded part of the worn screw. According to the degree of screw wear, overlay welding 1~2mm thick, and then grind the screw to size. This wear-resistant alloy is composed of materials such as C, CR, VI, CO, W and B, which increases the wear and corrosion resistance of the screw. Professional overlay welding plants have a high cost for this kind of processing, except for special requirements of screws, which are generally rarely used.
4. The repair screw can also be used by the surface plating hard chrome method, chromium is also a wear-resistant and corrosion-resistant metal, but the hard chromium layer is relatively easy to fall off.
Second, the repair of rubber extruder barrel
The inner surface of the barrel is harder than the screw, and its damage comes later than the screw. The scrapping of the barrel is the increase in the inner diameter diameter due to wear over time. Here's how to fix it:
1. If there is still a certain nitriding layer of the barrel that increases the diameter due to wear, the inner hole of the barrel can be bored directly, ground to a new diameter size, and then prepare a new screw according to this diameter.
2. The inner diameter of the barrel is recast by machining and trimming, the thickness is between 1~2mm, and then finished to the size.
3. Under normal circumstances, the homogenization section of the barrel wears quickly, this section (take 5~7D long) can be trimmed by boring, and then equipped with a nitriding alloy steel bushing, the diameter of the inner hole refers to the diameter of the screw, left in the normal matching gap, and processed and prepared.
It is emphasized here that the two important parts of the screw and the barrel, one is an elongated threaded rod, and the other is a relatively small and long hole, their machining and heat treatment processes are more complicated, and the guarantee of accuracy is more difficult. Therefore, whether the two parts are repaired or replaced with new parts after wear must be analyzed from an economic point of view. If the repair cost is lower than the cost of replacing the new screw, decide to repair, this is not sure is a correct choice, the comparison of repair cost and update cost is only one aspect. In addition, it is necessary to look at the ratio of repair cost to the time used by the screw after repair to the cost of renewal and the use time of the update screw. It is the right choice to adopt a solution with a small ratio.
4. Materials for screw and barrel manufacturing
To manufacture screws and barrels, the current commonly used materials in China are 45, 40Cr and 38CrMoAlA.