Five-axis machining center workpiece can be completed once the five-sided processing of the workpiece, but also for complex space and surface for high-precision machining. Vertical machining center (triaxial) the most effective machining surface is only the top of the workpiece, horizontal machining center with the rotary table, the workpiece can only be completed around the processing.
一、 Vertical five-axis machining center
1、Table rotary axis
The table set on the bed can be rotated around the X axis, defined as A axis, A axis general working range +30 degrees to -120 degrees. There is also a turntable in the middle of the workbench. In the position shown in the figure, it revolves around the Z-axis and is defined as C-axis and C-axis are all 360-degree rotation. In this way, through the combination of A-axis and C-axis, all the other five surfaces except for the bottom surface can be processed by the vertical spindle. The minimum scale of A-axis and C-axis is 0.001 degree, so that the workpiece can be subdivided into any angle, and the inclined plane and inclined hole can be processed. A-axis and C-axis, such as XYZ three linear axis linkage, you can work out the complex space surface, of course, this requires high-end CNC system, servo system and software support. The advantage of this setting method is the spindle structure is relatively simple, the spindle rigidity is very good, the manufacturing cost is relatively low. But the general table can not be designed too large, load-bearing is also small, especially when the A-axis rotation is greater than or equal to 90 degrees, the workpiece cutting will bring great bearing moment on the table.
2、Rely on vertical spindle head rotation
The front end of the spindle is a rotary head that can rotate around the Z axis by 360 degrees to become the C axis. The A-axis can be rotated around the X axis on the rotary head, generally up to ± 90 degrees to achieve the same function as above. The advantage of this setting is that the spindle is very flexible and the workbench can be very large. The huge fuselage and huge engine case of the passenger aircraft can be machined on this type of machining center. This design also has a big advantage: When we use the spherical milling cutter surface, when the tool center line perpendicular to the machined surface, the vertex point of the workpiece surface quality is bad due to the milling cutter vertex speed is zero, Adopting the design of spindle rotation, the spindle rotates relative to the workpiece by an angle so that the spherical milling cutter avoids the cutting of the vertex, ensuring a certain linear speed and improving the surface processing quality. This structure is very popular for mold surface machining of high precision, the table rotary machining center is difficult to do this. In order to achieve high-precision rotary, high-end rotary axis is also equipped with a circular grating feedback, indexing accuracy are within a few seconds, of course, such slewing structure of the spindle is more complex, higher manufacturing costs.
Spindle rotary vertical five-axis machining center of the spindle gravity down, the bearing high-speed radial load of the radial force is equal, the rotation is very good, so can increase the speed, the general high-speed up to 1,2000 r / min above, practical maximum speed has reached 4,0000 rpm. The spindle system is equipped with a recirculating cooling unit. The recirculating cooling oil takes away the heat generated by the high-speed revolution and is cooled down to a suitable temperature by the refrigerator and then back to the spindle system. X, Y, Z three linear axis can also adopt linear grating feedback, bi-directional positioning accuracy within the micron level. As the rapid feed to 40 ~ 60m / min or more, X, Y, Z axis ball-screw mostly adopt the central cooling, with the same spindle system, circulated through the refrigeration circulating oil ball-screw center, take away the heat .
二、horizontal five-axis machining center
1、horizontal spindle swing as a rotary axis, together with a rotary axis on table to achieve five-axis linkage processing
This setting is simple and flexible, such as the need for spindle conversion from vertical to horizental, table only indexing positioning, you can simply configure the vertical and horizontal conversion of the three-axis machining center. By the spindle vertical and horizontal conversion with the table indexing, the workpiece to achieve pentahedron processing, manufacturing costs is low, but also very useful. Can also be set CNC axis on the table, the smallest sub-value of 0.001 degrees, but not for linkage, only for the vertical and horizontal conversion of the four-axis machining center to adapt to different processing requirements, the price is very competitive.
2、the traditional table rotary axis, set in the bed table A axis general working range +20 degrees to -100 degrees
The middle of the table also has a rotary table B-axis, B-axis can be two-way 360-degree rotation. This horizontal five-axis machining center linkage characteristics better than the first method, commonly used in the processing of large impeller complex surface. Rotary axis can also be configured circular grating feedback, indexing accuracy of a few seconds, of course, this rotary axis structure is more complex, the price is expensive.
Horizontal machining center spindle speed is generally above 10,000rpm, due to the horizontal spindle has a self-weight in the radial direction of the bearing high-speed radial load is not equal, coupled with the use of larger BT50 shank, Generally up to 20,000rpm. Horizontal machining center rapid feed to 30 ~ 60m / min or more, the spindle motor power 22-40KW above, the capacity of the magazine can be increased from 40 to 160, the processing capacity far exceeds the general vertical machining center it is heavy machinery first choice.