1. Problems in tool setting and loading in thread turning
1) First turning clamping tool
When clamping the thread cutter for the first time, there will be the phenomenon that the height of the thread cutter tip is not equal to the rotation center of the workpiece, which is generally common in welding cutters. Due to rough manufacturing and inaccurate tool bar size, the center height needs to be adjusted with shims, and the height of the center affects the actual geometric angle of the cutter after turning. When installing the cutter, the cutter tip angle is biased, which is easy to produce thread profile angle error and tooth profile skew. If the thread cutter extends too long, it will vibrate during processing, which will affect the surface roughness of the thread.
2) Rough and fine turning tool setting
In the process of machining high-precision threads and trapezoidal threads, two thread cutters are needed to separate rough and fine turning. Large offset (especially in Z direction) caused by two cutters will make the pitch diameter of the thread larger and cause scrapping.
3) Repair workpiece tool setting
Repair workpiece tool setting due to the secondary clamping of the workpiece, the repaired helix and the first rotation signal of the encoder have changed, and there will be disordered buckle during the repair and processing again.
2. Solutions to problems
1) The tip of the thread cutter must be kept at the same height as the rotation center of the workpiece. After the cutter is grinded, use the tool setting template to lean against the axis of the workpiece for tool setting, and maintain the correct installation of the tip angle. If the NC machine is used to clamp the tool, because the manufacturing accuracy of the tool bar is high, generally, the tool bar can be placed close to the side of the tool holder.
2) For the tool setting of rough and fine machining thread cutter, set a certain point as the reference point, and use the usual method for tool setting. In the actual tool setting process, use the trial cutting method, as long as you slightly adjust the tool compensation.
3) In the process of thread machining, if there is tool wear or tool collapse, it is necessary to re sharpen the tool and adjust the tool after sharpening. The workpiece is not removed for repair, so it is only necessary to overlap the installation position of the thread cutter with the position before removal, which is equivalent to the processing of the same turning tool.
4) If the disassembled workpiece is repaired, the repair processing can be carried out only after the position of the processing starting point is determined. How to determine the processing starting point and the position of the one turn signal, first of all, use the test bar to turn the thread with a surface depth of 0.05 ~ 0.1mm (all parameters are the same as the parameters of the thread to be processed), the Z value is the integer thread lead distance from the right end face of the thread starting point, and the spiral line is carved on the surface to determine the thread turning starting point, Mark the corresponding position on the circular surface of the chuck (even if the mark is in the same axial section as the starting point of the screw on the test rod).