System For Tool Path Generation Of 2D Contour Milling Of Die

In the mechanical manufacturing industry, the die manufacture isone kind of quite complex work, and the CNC milling has already the moreand more important position in the die manufacture, The milling ofcontour is extremely common. Our cooperator is (The Die ManufacturingCo., Ltd. of FAW)a die manufacture company,in which to mill 2D contour,NC module of CAM software is used for producing the NC program ,thecoordinates size of actual contour is applied in the NC program, andthe cutting tool radius compensation is adopted in actually milling.Because the function of radius compensation in the CNC system iscertainly imperfect, the only effective segments can be treated withahead of time. The machining become the more complex when the contourcontains a series of short line segments, and it is impossible that themachining interference will be produced. Therefore, to the complexcontour machining, calculating the non-interference processing pathis needed before machining in the CNC Machine Tool. And because the CAMsoftware is very complex, it is difficult to be popular with the workshopworkers .In this way, it is essential extremely to develop a softwareof producing the cutting tool path for 2D contour.The algorithm of producing the cutting tool path for 2D contourmainly includes: pretreatment of the contour, production of theoffsetting segment, transition processing of the offsetting segment,interference examination of cutting tool track and so on.Because the offsetting segment of the non-circular curve cannotexpress precisely, it is impossible to use the CNC to realizeinterpolation operation of point-by-point comparison. It becomenecessary to disperse the curve to a series of tangents or the segmentalarcs beforehand, then moves these tangents or the segmental arcsaccording to the order of the contour.Production of offsetting segment mainly is to move the contoursegment a cutting tool radius towards the offset direction, theoffsetting segment of the tangent is still a tangent, and the offsetsegment of the segmental arc is still the segmental arc, then calculatethe two end points of the offsetting segment.Transition processing of offsetting segment refers that theoffsetting segments can't be connected directly as the cutting toolpath, otherwise, the cutting tool will meet the contour and theinterference happens. Regarding the concave point of contour line, theoffsetting segments of its two sides will intersect, so it is neededto transit in a point of intersection from preceding offsetting segmentto the latter offsetting segment. Regarding the raised point of contourline , the offsetting segment is separation, so the preceding offsettingsegment endpoint can not also be connected with the latter offsetingsegment beginning directly, and it should take the suitable transitionway. There are many kinds of transition way for avoiding interference,which have the characteristics respectively, but it is the mostadvantageous to use the circular arc transition.The interference examination aims at examining the wholeinterference, it possibly happens that when moving along an offsettingsegment the cutting tool meet other unconnected offsettingsegments .the method of interference examination processing mainlyadopts the loop decomposing, which keeps effective loop and picks outinterference loop.By cooperating with the die manufacturer and on the base of practiceinvestigation, This article has studied the algorithm of 2D contouroffsetting and the transition processing, and discuss the algorithmdeeply. This article has developed the System for Cutting Tool PathProduction of 2D Contour Milling of Die by using the MATLAB language.This system will be used in the workshops. The program should be carriedon according to the actual cutting tool radius and the non-interferenceCutting tool path should be calculated directly out of CNC machine tool.The cutting tool radius compensation is putted away, and theinterference can be avoided in machining. The system also hasdirect-viewing, the simple graphical user interface, and visiblefunction to cutting tool path, it is certainly useful for the diemanufacture. This system is being at the practice examination stage,and it need to be improved.This article is divided into six chapters altogether, the firstchapter introduces the present situation and existence question for 2Ddie milling, and proposes a method to solve the question;The secondchapter introduces some theories of CNC machining;The third chapternarrates the algorithm principle to the cutting tool path producing;The fourth chapter narrates the procedure realization of the system;The fifth chapter takes a car door die as an example to use this systemto machine;The sixth chapter draws out the conclusion , and point outthe deficiency of this article.