1. The thread length is incorrect The reason is that the matching of the hanging wheel is incorrect or the position of the feed box handle is not correct, you can recheck the position of the feed box handle or check the hanging wheel.
2. Partially incorrect The reason is that due to the local error of the screw thread of the cardan drive shafts itself (generally caused by wear), the screw can be replaced or repaired locally.
3. The pitch of the entire length of the thread is uneven The reason is:
o Axial movement of the lead screw.
o Axial movement of the spindle.
o The open and close nuts of the slide box and the screw lead to different shafts, resulting in poor engagement.
o Sliding box dovetail guides are worn, which makes the opening and closing nuts unstable when closed.
o The gap between the wheels is too large.
Pass the test:
o If it is caused by the axial movement of the screw, the adjustment round nut at the connection between the screw and the feed box of the lathe can be adjusted to eliminate the axial clearance of the thrust ball bearing at the connection.
o If it is caused by the axial movement of the main shaft, the nut can be adjusted after the main shaft to eliminate the axial clearance of the rear thrust ball bearing.
o If it is caused by poor engagement between the opening and closing nut of the slide box and the screw, the opening and closing nut can be trimmed and the gap between the opening and closing nut can be adjusted.
o If the dovetail guide rail is worn, dovetail guide rails and inserts can be prepared to achieve the correct matching requirements.
o If the clearance is too large, the clearance can be adjusted again.
4. Slub pattern appears
The reason is that there is a periodic error in the gear transmission from the main shaft to the screw, such as the gear in the hanger box, the gear in the feed box due to itself, manufacturing errors, or local wear, or the eccentric installation of the gear on the shaft, etc.
As a result, the center of rotation is low, which leads to uneven periodic rotation of the lead screw and uneven periodicity that drives the movement of the tool.
4. Incorrect diameter
Failure analysis and solution: The reason is that the knife is too large, the dial is not accurate, and it is not measured in time. The solution is to carefully check whether the dial is loose when finishing, the remaining amount of the finishing is appropriate, the cutting edge of the turning tool should be sharp, and it should be measured in time.
5. Rough thread surface
Failure analysis and solution: The reason is that the cutting edge of the turning tool is not smooth, the cutting fluid is not suitable, the cutting speed and the material of the workpiece are not suitable, and the vibration during the cutting process is successful.
The solution is: correct the grinding wheel or grind the tool with whetstone; select the appropriate cutting speed and cutting fluid; adjust the insert of the lathe bed saddle pressure plate and the small and medium slide dovetail guide rails, etc., to ensure the accuracy of each guide rail gap and prevent cutting Produce vibration.
In short, there are many kinds of faults generated when turning threads, including equipment reasons, tools, operators, etc., when troubleshooting, it is necessary to analyze the specific circumstances and find out the specific Influencing factors, take effective measures.
