CCMT2006 China CNC Machine Tool Exhibition was held in Shanghai on February 13. It can be seen from this exhibition that the quality of domestic machine tools has been greatly improved, and the five-axis linkage machining centers exhibited by seven domestic manufacturers have become A highlight of this exhibition.

    Compared with ordinary machining centers, the five-axis linkage machining center has greatly improved structure and performance. Regardless of the ordinary vertical or ordinary horizontal machining center, due to the limitation of the structure and the number of linkage servo axes, it can only effectively complete four-sided machining at most. The most effective processing surface of the vertical machining center is only the top surface of the workpiece, and the most effective processing surface of the horizontal machining center is only the four sides of the workpiece with the help of the rotary table. However, with the improvement of machining technology and the development of the industry, the requirements for machine tools are getting higher and higher in terms of effective high-precision machining of complex spatial areas (Figure 1), and five-axis machining centers have become the mainstay of machine tool development. one direction. The high-end CNC system equipped with five-axis linkage can perform high-precision processing of complex spatial surfaces. Among the machine tools exhibited at this exhibition, most are large-scale vertical five-axis linkage machine tools, such as Zhejiang Rifa Digital Co., Ltd., Shenyang Machine Tool Group, etc., while horizontal five-axis linkage machining centers are relatively rare.

    The structural characteristics of the large-scale vertical five-axis linkage machine tool exhibited by Seiki Co., Ltd. are: the front end of the spindle is mostly a double swing head (Figure 2). One of the degrees of freedom can swing around the Z-axis in the range of ±185° and become the C-axis. The large-torque built-in torque motor is used to control the swing. According to actual needs, it can be divided into single-torque motor and parallel dual-torque motor control. Another degree of freedom, it can swing around the X-axis in a range of ±110°, which becomes the A-axis, and the swing is controlled by a dual-torque motor. The advantage of this structure is that the tool has no blind spots and is very flexible. Swing head torque motors adopt internal water cooling or oil cooling, circulating cooling water or oil, take away the heat generated by the servo, reduce to a suitable temperature through the refrigerator, and then return to reduce thermal deformation and improve accuracy. Equipped with a circular grating to improve the indexing accuracy, generally within a few seconds. Of course, this type of structure is more complicated and the manufacturing cost is also higher. Another major advantage of the dual-swing five-axis linkage machine tool is that when we use the ball cutter to process the curved surface, when the center line of the tool is perpendicular to the processing surface, the cutting effect will be poor because the linear velocity of the cutting point of the apex of the ball cutter is zero. The surface quality of the cut workpiece is also very poor. Adopting double swing head design, combined with CAM software to automatically edit and optimize the program, the machine tool will rotate the tool center to an appropriate angle relative to the surface of the workpiece, so that the ball cutter does not cut at the apex, and ensures that the cutting point of the tool has a proper linear speed, so that the tool is always at The best cutting angle and state to improve processing quality. Another structural feature of the large gantry machining center is the use of a moving screw nut structure, which can reduce the moment of inertia of the screw, and the rapid feed can reach more than 40-60m/min, which improves the dynamic performance parameters. With the linear grating ruler, it effectively improves the stability of the machine tool. Sex and precision. All of the above structural methods allow the size of the worktable to be designed to be large, which can meet the processing requirements of large molds and engine casings. Large-scale vertical five-axis linkage machine tools have broad market prospects, and their applications will become more and more extensive, especially in the fields of automobiles, ships, and mold manufacturing.