Research On Location Error And Automatic Clamping Planning Of Holes Of Flexible Fixture

As an important branch of Computer-Aided Fixture Design (CAFD), based on itshighly flexible and intelligent advantages, flexible fixture is more favored by the market.More and more research on the flexible fixture system was obtained. However there are stillmany problems to be solved, such as the lack of complete quality evaluation system afterthe completion of positioning and clamping; little research on automatic clamping moduleshas been done, the clamping manners and clamping components can’t be automaticallyselected; clamping position can only be accurate to the clamping area, there are few studieson calculating the specific clamping points and the calculation is cumbersome; clampingelements can’t be fully automatically assembled. Therefore, we need to develop a moreintelligent flexible fixture system.To solve the above problems, a set of flexible fixture system for cutting machiningshould be established. This paper is based on the existing intelligent location system. Themain job includes the following aspects:(1) Based on the analysis of the structure of cutting machining and currentdevelopment for flexible fixture, a flexible fixture system for cutting machining wasdesigned. This system can locate and clamp one workpiece automatically, and implementthe automatic assembly of the workpiece and fixture with a rich fixture database;(2) With the summary of the existing methods of location error analysis and the actualsituation of this system, the location error study module was completed, including thelocator tolerance allocation and the accuracy analysis of the machining surface. Theworkpiece-fixture geometry was established, and the Jacobian Matrix connected workpiecedisplacement and locator displacement; machining surfaces were represented with"sampling points", with the definition of machining surface accuracy and the given locatortolerances,we can calculate the machining surface accuracy; with the given precisionmachining surfaces and the "sensitivity matrix", we can get the locator tolerance allocation;(3) The automatic clamping module was designed. The feature recognition technologyand the normal vectors were used to get a set of candidate clamping surfaces; with the"linear weighting method", the best clamping surfaces were selected; through meshclamping surfaces, a set of candidate clamping points was got; according to the clampingpoints selection principle, setting the objective function determined the "clamping triangle"; the clamping components positioning holes were determined with the "hole featurerecognition method",with the use of Virtual Assembly Technology, clamping componentswere assembled automatically.(4) The function modules of the existing flexible fixtures for machining systems wereimproved. By using VB6.0programming language for SolidWorks secondary development,the frame structure of this system was set up, and the interactive interface was alsodesigned.