Roundness modeling in BTA deep hole drilling

The modeling of deep hole geometry which was generated for boring and trepanning association (BTA) drilling was performed and its characteristics was discussed, also the effects of internally BTA drilled round profile are analyzed and its geometric modeling reliability was verified by the experiments of roundness testing, especially in BTA drilling operation. In this study, a harmonic geometric round model with the parameter of harmonic function was established. This relationship is also used to provide physical meanings to harmonic lobes generated by the proposed roundness model for a profile of BTA drilling, especially those caused by the spindle error motions of the BTA tool. In general, the theoretical roundness profile of a hole with an arbitrary multi-lobe can be calculated. But in real experiments, the two- to six-lobe hole profile was frequently measured. The most frequently measured one is three- and five-lobe profile in experiments. With these results, It was predicted that the reliability of proposed harmonic model has been verified theoretically and experimentally by a large number of real profile estimation of the hole and the experimental results that was produced by BTA drilling operation in deep hole making operation. This new modeling method is expected to provide desirable insights into the advanced tolerance analysis of circular hole making in BTA drilling process.