Abstract : A special-shaped surface CNC planer system was developed using the features of Mitsubishi PLC positioning control units. Compared with traditional single-chip microcomputer control systems, this system simplifies both the machine tool structure and control system, as well as the user's programming work, thus improving the system's stability and flexibility. Keywords : Mitsubishi PLC positioning control unit; CNC system; special-shaped surface CNC planer drive system. Many modern electromechanical industries widely use positioning units for control, such as x-Y table control, rotary table control, feed control, synchronous feed control, roller conveyor control, and complex track motion control. The main control methods include linear interpolation, circular interpolation, constant velocity track control, high-speed and high-precision track calculation, speed switching control, speed and position control, and fixed-length feeding. All these control requirements can be addressed by using PLC control units or modules of different levels to construct a system, achieving a technically advanced and economically reasonable solution. The author developed a special-shaped surface CNC planer system using a Mitsubishi Electric PLC positioning control unit. 1. CNC Planer for Special-Shaped Surfaces and its Drive System The CNC planer processes special-shaped surfaces formed by arcs, straight lines, and transition fillets, with a certain degree of taper: that is, composed of a certain conical surface and inclined surface. The generation line of this shaped surface along the axial direction is still a straight line—unlike general three-dimensional curved surfaces. During processing, the tool makes a rapid linear motion to scan the workpiece surface, thus processing the template special-shaped surface—using planing. It can achieve efficient cutting with simple tools (compared to milling) and simplify the machine tool structure. The working cycle of the CNC planer is the same as that of an ordinary planer, namely intermittent feed—planing stroke—return stroke. The difference is that it requires the linkage of three axes: x (planing direction), Y (horizontal feed direction), and Z (vertical feed direction)—taking the processing of a conical surface as an example. Assume that the planing starts from the large end to the small end, as shown in Figure 1. During intermittent feed, the y and z directions move by a feed amount F (mm) through circular interpolation. During the planing stroke, x and y... z needs to move simultaneously, and the speeds of each movement must satisfy the following relationship: [b][align=center]For details, please click: Application of Mitsubishi PLC in CNC System of Planer[/align][/b]