Using the idea of ​​the pose matrix chain, the 6PM2 overall algorithm is decomposed into two parts: the series pose matrix and the parallel pose matrix. The tandem pose matrix is ​​the coordinate transformation from the fixed platform to the moving platform through the series part, and the parallel pose matrix is ​​the coordinate transformation from the fixed platform to the moving platform through the parallel part. The driving amount of each real axis can be obtained by solving equation (1). During machining, the workpiece can be rotated around the Z axis with the rotary table. As long as the tool rotates around the Y axis, most of the machining can be realized. Therefore, the moving platform only needs to rotate around the Y axis. Assuming that the angle θ is rotated, then: In the machining program, the direction vectors Cx, Cy, Cz of the tool axis in the workpiece coordinate system can be obtained. Using these direction vectors, the α and β in the Euler angle description can be inversely solved: α=arctan2(Cy, Cx)β= Arccos(Cz) solves the equation on this basis: γ=πC=π-αθ=π4-β where Lx, Lz, H are fixed values ​​determined by the machine tool structure, and xw, yw, and zw are the origins of the workpiece coordinate system. The coordinate value in the rotary table coordinate system. Knowing Zc and θ, we can find the length of three parallel rods L1, L2, L3 according to the inverse solution of the parallel part: L1=12r(3cosθ-1)-R2+Zc-rsinθ where R and r are respectively fixed platforms And the radius of the circumscribed circle of the moving platform. Interpolation processing The hybrid machine has a non-linear correspondence between the tool and the drive rod due to the existence of the parallel mechanism. When the drive rod moves linearly, the tool path is nonlinear. In order to reduce this deviation, the linear trajectory of the tool must be subdivided, and a long trajectory is replaced by a combination of multiple small linear trajectories, that is, coarse interpolation in the workpiece coordinate system. For linear interpolation, the starting point of a straight line path is P0, the tool axis direction vector T0, the end point is Pn, and the tool axis direction vector is Tn. For the hybrid machine tool, the direction of the tool axis of the starting point and the end point may be different. When the interpolation is fixed, the vector of the tool axis direction must be considered. The double path interpolation algorithm <3> can be used. At the start and end points of the straight track, the two points P'0 and P'n of the distance L are taken along the direction of the tool axis, respectively: then: P'0 = P0 + LT0P'n = Pn + LTn where L depends on the value Interpolation accuracy and machine structure. The selection of the number of interpolation points should consider both the straight lines P0Pn and P'0P'n. Circular interpolation In the circular interpolation process, a circular arc is replaced by a series of arc chords, so there are two factors to consider: interpolation arc length and arc chord error. The starting point of the circular path is P0, the ending point is Pn, the center of the circle is Pc, and the radius is R. The plane unit vector of the arc is n=(ax, ay, az). When the tool axis is perpendicular to the plane of the arc, n The unit direction vector corresponding to the tool axis can be taken; when the tool axis is not perpendicular to the plane of the arc, the unit normal vector of the plane where the arc is located should be calculated according to the vectors P0Pc and PnPc. The control system of the speed control 6PM2 hybrid machine adopts the form of PC+PMAC. The PMAC itself provides the interpolation function. Therefore, the PMAC PVT mode can be used to realize the position and speed control of the drive shaft. The host provides the following data: position T and speed V of the motor after time T. Where T is the interpolation period, which can be determined according to the actual processing requirements. Position P is the position corresponding to each axis at the end point of the interpolation cycle, and speed V is the speed corresponding to the end point in the interpolation cycle. The machine tool processing provides the moving speed of the tool, and requires the tool to do the uniform motion as much as possible to ensure the surface quality of the machine. However, due to the existence of the parallel part, the movement of the parallel rod is non-uniform when the tool is moving at a uniform speed. Therefore, it is necessary to determine the driving speed of each real axis based on the moving speed of the tool. Assuming that the tool is moving at a constant speed, the tool position data at two points in the interpolation period are P1=(X1, Y1, Z1, θX1, θY1, θZ1) and P2=(X2, Y2, Z2, θX2, θY2, θZ2). , the feed rate is F. Firstly, the starting position Pm1=(Xm1, Zm1, θm1) and the ending position Pm2=(Xm2, Zm2, θm2) of the moving platform and the starting of the three series axes X, Y, C are obtained by the tool position data. The position (X1, Y1, C1) and the end position (X2, Y2, C2), and then calculate the time T of the interpolation period according to the feed rate: T = P1P2 / F = (X1-X2)2+(Y1-Y2)2+(Z1-Z2)2F The speed of the moving platform is: Vz=(Zm2-Zm1)/T(33)ωY=(θm2-θm1)/T With Vz and ωY, the driving speed of each parallel rod can be obtained from the inverse speed solution. The speeds of the three series axes are: Vx=(X2-X1)/TVy=(Y2-Y1)/T(36)Vc=(C2-C1)/T The processing experiment is carried out on the 6PM2 mixed bed using the above method. The machining experiment of the impeller surface is as follows. The experimental results show that the method is feasible and effective. Conclusion Through the processing of the five-axis NC machining program, the more mature five-coordinate programming technology and control technology are applied to the mixed bed, which makes the control simple and universal. The above method has been successfully applied to 6PM2 six-axis hybrid 镗The milling machine is numerically controlled and verified by machining experiments. (Finish) Windows Switch,Window Lifter Switch,Window Switch for Buick Kapaco Automotive Parts Co., Ltd. , http://www.hz-autoparts.com