Detailed introduction





How to disassemble the screw and how to repair it

 ScrewCause of damage
1. The raw material plasticizing temperature is low.
2. The raw material is mixed with metal foreign matter or impurities in the raw material.
3. Screw idle running time is too long.
4. Manufacturing screw material selection is unreasonable.
5. The screw manufacturing precision is low, and the heat treatment hardness of the thread working surface is low.
Disassembly sequence of screw
Special tools shall be used when disassembling the screw, and no heavy hammer shall be used. The specific disassembly steps are as follows.
1. Remove the nozzle and the connection between the nozzle and the barrel.
2. Separate the key connection at the rear of the screw from the drive shaft.
3. Remove the connecting flange and move the screw forward.
4. When the screw head is exposed to the barrel, immediately remove the screw head connection thread (note: the thread here is generally left-handed).
5. Remove the check ring and seal ring on the screw.
6. Disassembled nozzle, check ring, seal ring and screw should be cleaned up with copper brush and shovel tools immediately while it is hot. Special difficult to clean the adhesive material, should be placed in the oven heating, the temperature can make the material softening of the lowest temperature, and then remove the residue.
7. Assemble the parts on the screw together, and the threaded connection parts should be coated with molybdenum disulfide heat-resistant grease to facilitate the next disassembly.
8. The screw not used for the time being shall be coated with protective oil after the surface is cleaned, wrapped and hung in a ventilated and safe place.
Repair and replacement of screw:
1. If there are slight wear or scratch marks on the working surface of the screw, the damaged parts can be ground with oilstone or fine emery cloth.
2. When the working surface of the screw is severely worn and the scar groove is deep, the cause of the screw wear should be checked and analyzed, and the fault should be eliminated to avoid similar phenomena again, and then the deeper scar groove should be repaired. If the thread of the entire screw is severely worn, the matching gap between the screw and the barrel increases, the melt leakage flow increases during work, and the injection volume is unstable, the outer circle of the screw thread should be thermally sprayed with wear-resistant alloy, and then according to the inner diameter of the barrel The actual size of the screw is ground according to the requirements of the fit clearance of the parts.
If the barrel is seriously worn, the diameter of the inner hole increases after repair, and the grinding of the screw after spraying can no longer meet the requirements of the matching clearance size between the barrel and the screw, the screw shall be remanufactured. The outer diameter of the screw thread shall be processed according to the matching clearance requirements of the two parts and with reference to the actual inner hole diameter of the barrel.