A Method of Analysis and Adjustment of Workpiece Positioning Error Based on Tolerance Parameterization
A positioning error analysis and positioning error technology, applied in the field of workpiece positioning error analysis and adjustment based on tolerance parameterization, can solve problems such as high cost, dependence, and poor versatility
Active Publication Date: 2016-10-05
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology
Judging from the current research status at home and abroad, the current analysis of workpiece positioning errors still has deficiencies: 1) The fixture layout forms are diverse, and the workpiece positioning error analysis methods under each fixture layout form need to be established separately, and the versatility is poor; 2) ) In terms of workpiece positioning error adjustment or control, it depends on the adjustment of the fixture structure, and the cost is relatively high
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[0206] Such as figure 1 As shown, a 200mm×200mm×100mm cube workpiece is positioned on the fixture, and the positioning surface on the workpiece and the fixture (see figure 1 f in 3 , f 4 , f 5 , f 6 , f 7 , f 8 ) tolerance is taken as 0.2mm. see figure 2 ,Will figure 1 The positioning surface of the fixture formed by 4 and 3 fits the positioning surface of the workpiece into 3 positioning points (L 1 , L 2 , L 3 );Will figure 1 The positioning pin of the fixture formed by 6 and 5 is coaxial with the positioning hole of the workpiece and converted into two positioning points (L 4 , L 5 );Will figure 1 The positioning surface of the fixture formed by 8 and 7 fits the positioning surface of the workpiece into one positioning point (L 6 ). See Table 1 for the position and normal vectors of the six points. see figure 2 , taking 4 measurement points, their position vector and normal vector are shown in Table 2.
[0207] Table 1 Positioning points and their contr...
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The invention relates to a workpiece locating error analysis and adjustment method based on tolerance parameterization. The method is characterized by including the first step of calculating errors of rectangular planes according to the tolerance of the rectangular planes, the second step of calculating errors of cylindrical surfaces according to the tolerance of the cylindrical surfaces, the third step of calculating errors of the locating points where the rectangular planes are attached to one another, the fourth step of calculating errors of the coaxial locating points between the cylindrical planes, the fifth step of calculating the locating errors of workpieces, the sixth step of calculating the transfer coefficient of the errors of the locating points, and the sixth step of calculating a tolerance adjustment scheme. According to the method, the tolerance is parameterized and a fixture is converted to six locating points, so locating error analysis and adjustment of the workpieces are achieved, and the method has high calculation accuracy and universality; the locating errors of the workpieces are controlled by adjusting the tolerance of the workpieces and the fixture, and the cost increase caused by structural adjustment of the fixture can be avoided to some extent.
Description
technical field [0001] The invention relates to the technical field of machining, in particular to a method for analyzing and adjusting workpiece positioning errors based on tolerance parameterization. Background technique [0002] In mechanical processing, workpiece positioning reference errors and fixture errors lead to workpiece position errors, which are important factors affecting workpiece processing quality. Quantifying the workpiece positioning error and formulating an adjustment plan for the workpiece positioning error according to the analysis results is of great significance to avoid possible workpiece processing quality problems. [0003] At present, the research on workpiece positioning at home and abroad focuses on the design and optimization of fixtures, and there are few workpiece positioning error methods that can meet different fixture layout forms. The patent "a high-precision rotary positioning worktable" (application number: 201120500632.6) realizes the...
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IPC IPC(8): G06F19/00
Inventor 余剑锋金丽莎张杰唐文斌
Owner NORTHWESTERN POLYTECHNICAL UNIV