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Screw analysis: how to maintain and repair the screw?

Update:24-05-2021
Summary:

How to maintain and repair the screw? ①It is not allowe […]

How to maintain and repair the screw? ①It is not allowed to start the screw rotation with an empty car at will. Empty car inspection before driving? It should be started at low speed during trial operation, and the rotation time should be as short as possible (it should not exceed 2~3min. If everything is checked, stop immediately.


②The heating and constant temperature time before driving must be guaranteed, and the heat preservation and constant temperature time after reaching the process temperature should be no less than 1~2h. This prevents the material from increasing the working torque of the screw due to uneven temperature during plasticization.
③When handing over shifts, carefully listen to whether the rotating sound of the screw is normal. If abnormal noise is found, stop immediately and report to the relevant personnel for inspection? , Troubleshoot.
④ When disassembling the screw, use special tools to disassemble, and no heavy knocking is allowed. Disassembly sequence:
a. First disassemble the connection between the nozzle and the nozzle barrel;
b. Separate the key connection part at the rear of the screw from the drive shaft;
c. Disassemble the connecting flange and move the screw forward;
d. When the screw head is exposed to the barrel, immediately disassemble the screw head connecting thread (the thread here is generally left-handed);
e. Disassemble the non-return ring and the sealing ring;
f. The disassembled nozzle, non-return ring, sealing ring and screw should be immediately cleaned up with copper brushes and shovel tools while they are hot. Special hard-to-clean sticky materials should be heated in an oven to soften them before cleaning.
⑤When assembling the parts on the screw, each threaded connection part should be coated with molybdenum disulfide heat-resistant grease to facilitate the next disassembly.
⑥ The surface of the screw that is not in use should be coated with protective oil and hung in a ventilated and safe place.
(2) Repair of screw.
① The working surface of the screw is slightly worn or scratched. Use oilstone or fine emery cloth to polish the damaged part.
②When the screw working surface has serious wear or scar groove, should it be inspected? Analyze the reasons for the wear and tear of the screw and eliminate the fault to avoid similar phenomena again. Then repair the scratches and grooves of the screw.
③When the screw and barrel have serious damage marks, and the matching gap between the two has been large, the screw should be replaced, and the outer diameter of the screw thread should be prepared according to the inner hole diameter after the barrel is repaired. Ensure that the clearance between the barrel and screw is within the specified range.

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