The inner and outer hardness of the barrel is higher than that of the screw, and its damage is 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 and tear. If there is a certain layer of nitrided, the bore of the barrel can be directly stopped, ground to a new diameter, and then the new screw can be 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. Injection molding machine screw
3. Under normal conditions, the homogenization section of the barrel wears faster. This section (take 5~7D length) can be trimmed through the borehole, and then a nitriding alloy steel bushing is used. The diameter of the inner hole is referenced to the screw diameter. Normally fit the gap and stop processing.
Here, one important point is that the two important parts, the screw and the barrel, are the elongated threaded rods, and the ones are smaller and longer in diameter. Their machining and heat treatment processes are more complicated and the precision is guaranteed. difficult. Therefore, after the wear and tear of these two parts is repaired or replaced with new ones, it must be fully analyzed from the economic point of view. If the repair cost is lower than the cost of replacing the new screw, it is not necessarily the correct choice. The comparison between the repair cost and the update cost is only one aspect. In addition, it depends on the ratio of the repair cost and the screw time and the update cost and the update screw operation time after the repair. It is the right choice to adopt a plan with a small ratio to be economical.
4, screw and barrel manufacturing materials
Manufacture of screw and barrel. At present, the domestic commonly used materials have special materials, 40Cr and 38CrMoAlA.
The manufacturing information of the screw and barrel in the imported extruder, commonly used alloy steel has 34CrAINi7 and CrMoV9. The yield strength of this data is about 900 MPa. After nitriding treatment, the hardness is above 1000 HV, which is both wear-resistant and has good corrosion resistance.