As we all know, the screw and barrel are two important parts of the plastic mechanical extruder. If it is damaged, it will affect the operation of the machine. What should we pay attention to when repairing?
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 is given according to the normal gap of the barrel.
2. After the surface of the thread with the reduced diameter of the wear screw is treated, the wear-resistant alloy is thermally sprayed and then ground to a size. This method is generally processed and repaired by a professional spray factory, and the cost is still relatively low.
3. Surfacing the wear-resistant alloy on the threaded portion of the wear screw. Depending on the degree of wear of the screw, weld 1 to 2 mm thick and then grind the screw to size. This wear-resistant alloy consists of materials such as C, Cr, Vi, Co, W and B, which increases the anti-wear and corrosion resistance of the screw. Professional surfacing plants have a high cost for such processing, and are rarely used except for special requirements.
4, the repair screw can also be surface hard chrome plating method, chromium is also wear-resistant and corrosion-resistant metal, but the hard chrome layer is easier to fall off.
The inner surface of the barrel is harder than the screw and it is damaged later than the screw. The scrapping of the barrel is such that the diameter of the inner diameter increases due to time wear. Its repair method is as follows:
1. The barrel with increased diameter due to wear. If there is a certain layer of nitrided, the inner hole of the barrel can be directly bored, ground to a new diameter, and then the new screw is prepared according to the diameter.
2. The inner diameter of the barrel is machined and trimmed to recast the alloy, the thickness is between 1~2mm, and then finished to the size.
3. Under normal circumstances, the homogenization section of the barrel wears faster. This section (take 5~7D length) can be trimmed by the boring hole, and then a nitriding alloy steel bushing is used. The diameter of the inner hole is referenced to the diameter of the screw. Normally fit the gap and process and prepare.
Article link: China Plastic Online http://info.21cp.com/industry/News/201710/1343550.htm
