The long-term use of the three-jaw chuck will reduce the coaxiality and the bell mouth phenomenon, which directly affects the processing accuracy and clamping reliability. Practice has proved that using the following method to correct is simple and practical, and the effect is significant, so you might as well give it a try.
Take the positive jaw chuck as an example. First, clamp a round rod of appropriate diameter with an external clamp, start the machine tool, and turn the outer circle part of the jaw. Then clamp an annular piece by means of internal support, start the machine tool, and turn the inner circle part and end face of the jaws. Obviously, in this way, the coaxiality between the inner circle of the processed jaw and the main shaft of the machine tool can be obviously improved, and the bell mouth phenomenon can be eliminated, and higher precision can be obtained to achieve the purpose of correction.
The following points should be paid attention to in specific applications:
1. The outer circle of the round bar and the inner circle of the ring part need to be processed in advance and have a certain accuracy. And the inner diameter of the ring body should not be too small, otherwise the concave arc of the jaw surface will be large and deep, and the surface of the workpiece will be easily damaged when clamping large-diameter workpieces, which must be paid attention to.
2. Since there is inevitably a gap between the jaws and the sliding grooves of the chuck body, and the force direction of the jaws during correction is exactly opposite to the force direction during actual work, the corrected chuck will be used instead. There will be a bell mouth phenomenon. Therefore, the inner circle of the jaws should be pre-processed into a certain taper inverted bell mouth (large inside and small outside) when making corrections. The adjusted taper value can be determined through experiments. This is the key to success or failure.
3. Due to the high hardness of the jaws and intermittent cutting, the cutting depth and cutting amount should be small during correction, and the cutting speed should not be too high. The tool material is preferably cemented carbide. If a small power head can be installed on the carriage, the effect will be better if the grinding wheel is used for correction.
4. The purpose of cutting the outer circle of the jaws for the first time is to establish a good benchmark to improve the correction accuracy. It is best not to save this step. 5. This method can also be used to correct the new three jaws due to improper installation or other reasons. Errors caused to improve machining accuracy.
6. The same principle can be used to correct the anti-claw.