Use of five-axis linkage machining center
Use of five-axis linkage machining center
The machining center is generally divided into a vertical machining center and a horizontal machining center. The most effective machining surface of the vertical machining center (three axes) is only the top surface of the workpiece. The horizontal machining center can only complete the workpiece by means of the rotary table. Four sides of processing. At present, the high-end machining center is developing in the direction of five-axis control. The five-axis linkage machining center has the characteristics of high efficiency and high precision, and the workpiece can be processed in one time with the pentahedron.
For example, the high-end numerical control system with five-axis linkage can also perform high-precision machining on complex spatial surfaces, and it is more suitable for processing modern molds such as automobile parts and aircraft structural parts. (In this issue, the vertical five-axis machining center is introduced.) The vertical five-axis machining center has two types of rotary axes for the machining center. One is the rotary axis of the table.
The table set on the bed can be rotated around the X axis, defined as the A axis, and the A axis generally works from +30 degrees to -120 degrees. There is also a turntable in the middle of the table, which is rotated around the Z axis in the position shown, defined as the C axis, and the C axis is 360 degrees. Thus, through the combination of the A-axis and the C-axis, the workpieces fixed on the table can be machined by the vertical spindle except for the bottom surface. The minimum index value of the A-axis and the C-axis is generally 0.001 degrees, so that the workpiece can be subdivided into arbitrary angles, and the inclined surface, the inclined hole, and the like can be processed. If the A-axis and the C-axis are linked with the XYZ three-linear axis, complex spatial surfaces can be machined. Of course, this requires high-end CNC systems, servo systems, and software support.
The advantage of this arrangement is that the structure of the spindle is relatively simple, the rigidity of the spindle is very good, and the manufacturing cost is relatively low. However, the general workbench cannot be designed too large, and the load-bearing weight is also small. Especially when the A-axis rotation is greater than or equal to 90 degrees, the workpiece will bring a large bearing moment to the workbench when it is cut. The other is the rotation of the vertical spindle head. The front end of the spindle is a turret, which can wrap 360 degrees around the Z-axis to become the C-axis. The slewing head also has an A-axis that can rotate around the X-axis, generally up to ±90 degrees, to achieve the same function.
The advantage of this type of arrangement is that the spindle machining is very flexible and the workbench can be designed very large. The huge fuselage of the passenger aircraft and the huge engine casing can be processed on such machining centers. This design also has a great advantage: when using a spherical milling cutter to machine a curved surface, when the tool center line is perpendicular to the working surface, the surface quality of the workpiece cut by the vertex will be poor due to the zero vertex linear velocity of the spherical milling cutter. The design of the spindle rotation makes the spindle rotate through an angle with respect to the workpiece, so that the spherical milling cutter avoids the cutting of the apex, ensuring a certain line speed and improving the surface processing quality.
This structure is very popular with the high-precision surface machining of the mold, which is difficult to achieve in the rotary machining center of the table. In order to achieve the high precision of the rotation, the high-end rotary shaft is also equipped with a circular scale feedback, and the indexing accuracy is within a few seconds. Of course, the rotary structure of such a spindle is complicated and the manufacturing cost is also high.
