A non-uniform allowance allocation method based on interim state stiffness of machining features for NC programming of structural parts

For thin-walled parts,uniform allowance to each machining surface is allocated by the traditional machining method.Considering the sequence of the adjacent machining features,it may cause poor stiffness for some side walls due to a minor wall thickness,which may cause the deformation of the final formed parts to be large,or deduce machining efficiency for some machining features due to too thick remains.In order to address this issue,a non-uniform allowance allocation method based on interim state stiffness of machining features for the finishing of thin-walled structural parts is proposed in this paper.In this method,the interim state model of machining features is constructed according to the machining sequence of the parts,and the stiffness of the side wall is taken as the evaluation index to allocate reasonable allowance value to the corresponding machining surface to ensure the stiffness requirement of the parts in the machining process.According to the finite element simulation results,the non-uniform allowance allocation method proposed in this paper can effectively improve the stiffness of the parts and reduce the deformation of the parts,when compared with the traditional uniform allowance machining method.

Image Based NC Programming of Plane Contour Machining

Simplified Hough Transform (HT) and Adaptive Including Box (AIB) approach are proposed. The size of AIB is controlled according to the precision requirement of machining. The image data of part contour is turned into a set of line segments and then NC program for machining the contour is generated .

Directly Generating the NC Machining Program from AutoCAD Graph

One kind of auto-programming method directly gener at ing the NC machining program by AutoCAD graph is discussed in this article. Firs tly, the article discusses the open type graphic interface of AutoCAD. Then the graphic export among the AutoCAD, the adding of process information and the data storage, as well as technology of generating NC program has been introduced . Finally, a NC auto-programming system GAPS based on AutoCAD graph is develope d. The tendency of auto-programming is graphic auto-programming, because it posse sses these merits that the programming in the system is simple and the graph is perceived easily and the graphic data can be shared in many auto-programming sy stems. It is well known that AutoCAD is widely used graphic software in machiner y at present. The AutoCAD plotting function is more powerful than other special drawing-software in auto-programming system, and has provided the convenient o pen data interface for development of software. The AutoCAD has several kinds of open data graphic interfaces, and these interfaces are general among different versions. Chiefly, there are ASCII’s graphic exchange file (.dxf ) and the bina ry system graphic exchange file (.dxb ) in AutoCAD. We discuss the second fi le format right off here. The technology generating the NC machining program from AutoCAD graph is accompl ished by four relatively independent modules. In the auto-programming, NC progr am designer firstly carries on technology analysis to the part-drawing to estab lish the drawing scheme for auto-programming, later draws out the detail diagra m based on the analyzed in AutoCAD system. The graphic data is converted to the recognizable data structure in the system by the graphic data conversion module in the auto-programming system. Then the new data is joined process information at the process control module of system, and forms the cutter-orbit data. The cutter-orbit can generate the NC program as a result of the handle of the post -processing module of system.

ESTIMATING THE CUTTER＇S MAXIMUM DIAMETER IN 5－AXIS NC FACE MILLING OF TURBINE BLADES

Based on the principles of differential geometry,the basic equations are derived for generating gouging free tool path in 5-axis NC face milling,the influence of surface's local geometry is discussed,and the conditions of using cutter with reasonable diameter are presented.