Layout planing method for positioning unit of precise clamp

Abstract

The invention is a precision clamp locating cell laying-out method, selecting characteristic points and directional vectors on a workpiece to define an error tolerance index according to the manufacture task, thus deriving locating error control index as design optimizing target function, using the density data points obtained by scattering reference surface of the workpiece as a candidate set of clamp locating cells, and letting initial solution set of locating cells be a null set, applying the floating search method to select a point from the candidate set each time to supplement it into the solution set, and simultaneously conditionally deleting the selected bad points, so circulating until six locating cells are screened, and thus laying out the optimum locating cells. The said locating error tolerance index has a geometrical meaning related with the manufacture task but is irrelated with the selection of the reference frame, neither is the derived locating error control index. The invention can reduce the precision requirement for clamp locating cells and reference surface of a workpiece on the premise of meeting the workpiece manufacturing accuracy, thus reducing the manufacturing cost.

Description

technical field [0001] The invention relates to a precision fixture positioning element layout planning method, which can be used for precision fixture design in manufacturing engineering and belongs to the technical field of mechanical manufacturing. Background technique [0002] In the manufacturing process, the fixture plays the role of positioning and supporting the workpiece. Correctly designing the fixture according to the precision requirements of the workpiece is one of the key factors to ensure product quality. The fixture is composed of two parts, the positioning element and the clamping element. The positioning accuracy of the fixture is determined by the manufacturing and assembly accuracy of the positioning element, the manufacturing accuracy of the workpiece reference surface, and the spatial layout of the positioning element. The first two are related to the manufacturing Technology and equipment are related, and improving manufacturing accuracy often leads to...

AI Technical Summary

Problems solved by technology

At present, the positioning error measurement index is usually taken as the Euclidean norm of the motion screw, and a series of optimization objective functions have been developed from this, but this definition has the following disadvantages: (1) It involves the addition of values ​​​​of different dimensions (2) It is not related to the manufacturing task and has no physical meaning; (3) It is related to the specific machine tool coordinate system and workpiece coordinate system, and has no coordinate transformation invariance

The former has a large amount of calculation, and it is not easy to deal with additional geometric constraints and the transition between surfaces; the displacement algorithm in the latter has too much calculation, and the incremental algorithm does not have the ability to backtrack

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