INFORMATICS SYSTEM FOR SELECTION OF CLAMPING SURFACES OF WORKPIECES IN MACHINING FIXTURES

Fixtures are used for orientation and positioning of workpieces in various machining, control, assembly operations. According to 12S (twelve steps) design methodology, the activity of conception and design of fixtures has strong creative character. This character is determined by the possibility of selection of optimal fixture variant, form a large variety of fixtures. The optimal solution is searched for each main component of the fixture. The methodology allows the generation, in scientific manner, of the solution space, in a larger and larger number in order to increase the possibility of determining the optimal solution. Clamping is the technological phase where orientation and positioning scheme is conserved during machining. The clamping stage consists in applying a force system on the workpiece, in a certain succession on a single or multiple surfaces of the workpiece. The clamping forces are applied only on certain surfaces, entitled clamping surfaces. By clamping forces are understood the actual surfaces and also edges or tightening points. The paper presents an informatics system for selection of clamping surfaces, according to certain criteria. The system allows highlighting of all workpiece surfaces and for each surface an evaluation is made according to the mentioned criteria. Each surface will be characterized by a weighted average that will allow ranking of all surfaces. Also, for each surface the application of forces can be simulated. Thus, it can be visualized the effect of the clamping scheme and the stability, deformation, clamping precision of the workpiece can be assessed. In this way, the optimal clamping surfaces on which the clamping forces will act can be selected.