Research On Evaluation Method For Deep-hole Axis Straightness Error

With the development of deep-hole processing technology, high-precision and ultraprecision machining become a trend. As main parameter of deep-hole type parts, the testing and evaluation for axis straightness error is an important basis for product quality control. The evaluation program of deep-hole axis straightness error is complex. Currently, the high precision evaluation method for deep-hole axis straightness error is few. Research on evaluation method contribute to adjust its process craft and control product quality. In this paper, after a summary analysis of existing programs, a basic evaluation model for deep-hole axis straightness error was established. Four kinds of evaluation program was proposed based on the basic evaluation model, the main research works are as follows:(1)The principle of the linking two end points method, the least squares method and the least envelope zone method was analyzed. The establishment of a basic evaluation model was based on the minimum conditions principle of straightness error. Error evaluation model gives ideas, the main step and core of the optimal solution search program. The core is to seek an evaluation baseline.(2)Connection line of point on the sphere surface and sphere center is a baseline assessment. The straightness error and the optimal evaluation baseline can be determined by solving the minimum circumscribed circle of projection on sphere exterior tangent plane. In the model, the direction vector of the perpendicular line of sphere exterior tangent plane is the direction vector of the evaluation baseline. Uniform spherical bending provides continuous direction vector. The space problem is transformed into plane problem by projecting spatial point sets.(3) Error evaluation model searches the evaluation baseline is nonlinear optimal solution problem. Search result can only infinitely close to the true value, but not achieved. According to above feature, the model of harmony search algorithm for searching the evaluation baseline was proposed to improve the straightness error solving efficiency and precision. Assessment principles of harmony search algorithm was elaborated. The evaluation baseline spatial location information was stored in harmony memory. The optimal evaluation baseline was searched by trimming space information stored in the memory.(4) In order to further improve the search accuracy and avoid the phenomenon of local optima, harmony search algorithm was optimized by providing feedback information and diversity harmony memory. Dynamic floating mechanism of parameters was established by providing search results to algorithm parameters. So dynamic parameters can better accommodate to the search for the optimal solution. Diversity harmony memory randomly generated mechanisms was established to avoid singularity memory information, reduce the probability of arise local optima.