Research On CNC System Of Five-Coordinate Virtual Axis Polishing Machine Tool

1．IntroductionSince our country was affiliated to WTO in due form in 2001, the economic development is speedier. With the development of automobile industry, aeronautics and astronautics industry and some new high-tech industries, the larger is the proportion of NC machining parts with free-form surface in all, the higher and higher requirements are made for quality and efficiency of machining on free-form surfaces. However, these subsequent processes of precision machining still depend mainly on the handwork of skilled mechanists presently. Productivity effect of handwork is very low and its quality is unstable. As to the machining of free-form surfaces, low cost and short period and high quality were its main aim. As a result of that, the research of a kind of increasingly automated polishing equipment is imperative. This paper regards the JDYP51 model five-coordinate virtual axis polishing machine tool for polishing free-form surfaces. We have researched a kind of open architecture CNC system which is based on PMAC.2．Mechanism design analysis of virtual axis machine toolThe series-parallel machine tool, which is well arranged by in series and paral-Fig.1 JDYP51 model five-coordinate Vir- Fig.2 the whole structure of virtual tual Axis polishing Machine Tool axis machine tool lel, is researched in this dissertation.It is a "3+2" model virtual axis machine tool .Three parallel axis carry out there movements in Xcoordinates,Ycoordinates and Z coordinates. Parallel mechanism drives move platform to move flatly. In series mechanism which have two degree of freedoms is fixed in move platform. principal axis mechanism is fixed with In series mechanism. The machine tool can be used to polish free-form surfaces of mold. the photo of machine tool is shown as Figure1. The whole structure of virtual axis machine tool is shown as Figure2. The parallel mechanism are composed of still platform, move platform, three poles and a chain that is fix long pole. At one end of every pole, a sliding block is linked. At the other end of it, the move platform is linked by Huke joint. The sliding block that is drived by servo electromotor and rolling screw thread-nut move up and down along with rail. The inseries mechanism of the machine tool is linked with move platform. It is made up of two rotation joints. The pose of polishing tools is adjusted around axis.Position analysis of series-parallel virtual axis machine tools for polishing free-form surfaces is to ask solving the position relation while input and export. Positive solution of position analysis is to ask solving the position and pose of the export part of the machine tools for polishing free-form surfaces, while the position of input part is already known. If the position and pose of the export part is known, solving the position of input part was named as negative solve. Because of the movement characteristic of the machine tools. Analytic method is used to get the positive solution equation. At first, the analytic Fig.3. The parse drawing of the figure of parallel mechanism is established. parallel mechanism It is shown as Fig.3. square of mode: through geometry relation, three kindsof relation between input and export of move platform are obtained. It is known: These are position analysis of parallel mechanism.And Positive position solution of inseries mechanism of machine tools is established through homogeneous transformation of the coordinate frames. Inseries and parallel mechanism are regarded moving the platform as the tie, so the position solution of machine tools can be got. 3. Design and realization of open NC system hardware Through research on JDYP51 model five-coordinate virtual axis polishing machine tool, a kind of open NC system is d...