Rough boring is often used as the pre-processing of boring processing. Before rough boring, the workpiece holes are generally blank holes, with large machining allowance and uneven veneer allowance, which is easy to cause vibration during machining. Therefore, the surface roughness after rough boring is relatively rough and the machining accuracy is relatively low. At this time, we should adopt the processing principle of efficiency first and accuracy second, that is, to improve labor productivity. Therefore, in actual production, we should first increase the back cutting amount, reduce the feeding times, then increase the feeding amount, and finally select the cutting speed corresponding to the back cutting amount and feeding amount.
The machining principle of efficiency first and accuracy second is never to ignore accuracy. In actual production, the quality of rough boring will directly affect the quality of semi precision boring and precision boring. Sometimes, due to the large geometric error during rough boring, which cannot be corrected during fine boring, the workpiece is scrapped. Therefore, boring workers must pay great attention to these problems when rough boring. For holes with low accuracy requirements, rough boring can be used as the final machining. For holes with high accuracy requirements, rough boring can be used as the pre-processing of semi fine boring and fine boring, cut off most of the allowance of blank holes, improve the dimensional accuracy of the blank, reduce the surface roughness, and prepare for semi fine boring and fine boring.
For some holes with high processing requirements, semi fine boring processing should be arranged after rough boring and before fine boring, so as to further improve the dimensional accuracy of the blank and reduce the surface roughness, so as to make a good pig cloth ratio for fine boring. For some holes with low machining accuracy, fine boring can also be used as the final machining of holes.
Fine boring is often used as the final machining of boring holes with high accuracy requirements. Before fine boring, generally, it has gone through the processing sequence of rough boring and semi fine boring. The dimensional accuracy, position accuracy, shape accuracy and surface roughness of holes have been greatly improved compared with blank holes. At this time, fine boring is mainly to meet the technical requirements of the hole specified in the drawing. At this time, the processing principle of "accuracy first, efficiency second", that is, to ensure the dimensional accuracy, geometric accuracy, mutual position accuracy and surface roughness requirements of holes, should be adopted.
At this time, the feed rate should not be too large. In order to ensure the surface roughness requirements of the hole and improve labor productivity, the cutting speed of the boring cutter should be increased. The machining allowance of fine boring is generally small, and the back feed is limited by the machining allowance. Therefore, the back feed is intelligently selected within the range of machining allowance.
The above is a general introduction to the machining principles of boring. You should understand the machining principles of different processes. These principles have a great impact on machining accuracy and machining efficiency, so we must pay attention to the above principles when boring, so as to process boring products that meet the requirements.