The Research And Development Of Plunger Mold Compensation System For Projection Tube Screen

This dissertation is focused on the method to ensure quality of inner surface ofprojection tube screen indirectly by means of amending its plunger mold. With theaid of computer graphics, software engineering, database technology, NC technologyand VB programming language, a relatively simple and practical spline function isused to construct mathematic model of surface, multi-surface smooth transition andmethods of NC machining program are also researched here and a compensationsystem for the plunger mold is developed. The major content is summarized asfollows:1. In view of the contradiction between the complicated deformations of innersurface of screens and the requirement of small amount of measured points, Cardinalbicubic interpolation spline surface is used to construct mathematic model of surface,which solves the above problem correctly. The Cardinal bicubic interpolation splinesurface, a simple and practical function, meets the need that the figure of the surfaceof the plunger mold must reflect the deformations of the inner surface of projectiontube screens which influence each other in different areas.2. The same function and topology structure is used to construct the fillettransition surface between the surface and the side of plunger mold. By using ofLagrange quadric interpolation curve, the problem of smooth transition between theconstructed surface of the plunger mold and the side is resolved. Furthermore, theproblem of over-cut at the corner of the plunger mold is resolved by means ofincreasing the number of parameter curves.3. The module of NC program generation is developed. Some researches onmethods of NC program generation are made, and, at last, we adopt the local equalparameters method of computing step-length. Namely, the step-length is computedaccording to tolerance in the direction of cutter moving and to equal value ofparameter in the direction of machining zone.4. In the process of compensating, there are not only some kinds of data butalso some kinds of data files which need to be managed, such as the figure parametersof plunger mold and interim data during system's computing period and so on. Publicdatabase technology is used to solve this problem that too many data need to bemanaged.