Five axis machining center is introduced, and analysis of high precision processing

Vertical machining center (three axis) of the most effective surface is only the top surface of workpiece, horizontal machining center with the help of a rotary table, also can finish machining of all around. The high-end machining center is developing in the direction of the five axis control, a clamping workpiece pentahedron processing can be completed. Five-axis linkage of high-grade CNC system such as configuration, also can to precision machining complex curved surface.

Vertical five-axis machining center

Rotating shaft of this kind of machining center there are two ways, one is the workbench rotating shaft. Set up on the bed of the workbench can surround the X axis rotation, defined as A shaft, A shaft generally work scope + 30 degrees to 120 degrees. In the middle of the table is equipped with a rotary table, in the position of graphic around the Z axis rotation, defined as C axis, C axis is 360 degrees of rotation. So through the combination of A shaft with C axis, fixed on the workbench artifact in addition to the bottom, the rest of the five surface can be processed by the vertical spindle. A shaft and minimum degree value is commonly 0.001 degrees C axis, like this can be subdivided into the workpiece at any Angle, processing of inclined plane, inclined holes, etc. Such as A shaft and C axis with XYZ three straight axis to realize linkage, can the space of machining complex curved surface, of course, the need of high-grade CNC system, servo system, and software support. This setting method has the advantage of the spindle structure is simpler, the spindle rigidity is very good, the manufacturing cost is low. But also general table design is not too large, the bearing is small, especially when A shaft rotation is greater than or equal to 90 degrees, the workpiece cutting the workbench when they bring A lot of load torque.

Another kind is rely on vertical spindle head rotation (figure). Spindle front is A turret, can themselves around the Z axis 360 degrees, become C axis, rotary head also can surround the X axis rotation of A shaft, generally can reach more than plus or minus 90 degrees, realize the same function. Mode of this set has the advantage of the main shaft processing is very flexible, workbench can also design a very large, large airliner fuselage, huge casing can be in this kind of machining center. This design has a big advantage: we are using spherical milling cutter machining curved surface, when cutting tool processing center line perpendicular to the surface, as a result of the spherical milling cutter vertex linear velocity is zero, the vertices will cut the workpiece surface quality is very poor, adopts the design of spindle, the spindle relative to the workpiece around a point of view, the spherical milling cutter cutting, avoid the vertex ensure that there is a certain linear velocity, to improve the quality of surface processing. This structure is very popular with the high precision surface processing, this is the rotary table of machining center is difficult to achieve. In order to achieve high precision rotation, high-grade rotary shaft is configured with a circular grating ruler feedback, dividing accuracy within a few seconds, of course, this kind of spindle rotation structure is more complex, the manufacturing cost is higher also.

Vertical machining center spindle gravity down, bearing the idle running of the radial force is equal, rotary characteristics is very good, so can improve the speed, the general high speed can reach more than 1200 r/min, practical highest speed has reached 4000 0 r. Spindle system is equipped with circulation cooling device, circulating cooling oil away the heat generated by the high-speed rotation, through the refrigerator to the right temperature, and flow back to the main shaft system. X, Y, Z three straight axis linear grating ruler feedback may be adopted, two-way positioning accuracy within microns. Due to the rapid feed reached more than 40 ~ 60 m/min, X, Y, Z axis center USES mostly ball screw type cooling, with the main shaft system, by a refrigeration cycle of oil flow through the center of the ball screw, heat can be taken away.

Horizontal five-axis machining center

Such processing center of the rotating shaft have two ways, one is horizontal spindle swing as a rotating shaft, plus the workbench of a rotating shaft, realize five-axis linkage machining. Easy and flexible to this way of setting, such as need the spindle, lie transformation, workbench simply dividing location, can be configured to simply stand, lie the three axis machining center of transformation. By the spindle, lie the conversion degree, working for artifacts implement pentahedron processing, manufacturing cost is reduced, and very practical. Can also be used for table set numerical control axis, minimum degree value of 0.001 degrees, but do not make linkage, become a lie, conversion of four axis machining center, adapt to different processing requirements, the price is very competitive.

Another for traditional workbench rotating shaft, set on bed like A workbench A shaft working range + 20 degrees to 100 degrees. In the middle of the table also includes a rotary table B shaft, shaft can be 360 degrees two-way rotary B. The horizontal five-axis linkage characteristics of machining center is better than the first way, often used in processing of large complex curved surface of the impeller. Rotating shaft also configurable circular grating ruler feedback, dividing precision reached a few seconds, the rotating shaft structure is more complex, of course, the price is expensive.

The horizontal machining center workbench can be greater than 1.25 m2, little influence on the first five axis set mode. But the second mode of five axis is difficult, since 1.25 m2 workbench do A axis of rotation, but also with the table in the middle of the rotary table B axis linkage really reluctant. Horizontal machining center spindle speed above 10000 RPM, generally due to horizontal set of spindle has since gravity in radial, unequal bearing radial forces during high speed running, and also the larger BT50 handle, generally up to 20000 RPM. Horizontal machining center quickly feed reached more than 30 ~ 60 m/min, the spindle motor power 22 - more than 40 kw, dao database is according to the need can be increased from 40 to 160, the processing capacity is far more than the general vertical machining center, is the first choice for heavy machinery processing.

Most machining center can be designed as double workbench exchange, when a workbench to run in the processing zone, another table in the processing zone replacement artifacts, in preparation for the machining of the next, workbench exchange time depending on the work table size, from a few seconds to a few seconds to complete. The latest design of machining center considering the structure should be suitable for modular manufacturing cell (FMC), and the flexible production line (FMS), modular manufacturing unit generally have at least two sets of processing center and four exchange of workbench, processing center all placed side by side, change table in front of the machine tool a glyph discharged, change table more can be arranged in two rows, even double design. Each side has a location as the position of the workpiece, the rest of the location on the change table waiting for processing the workpiece installation, system with a car will be in accordance with the instructions, the change table of workpiece in machining center, or removed from the processing center to complete processing of exchange of workbench, sent to the next station or directly to the blanking station, complete the whole processing operations. Flexible production line in addition to the car, exchanging worktable, and the unity of tool library, tend to have several hundred, the cutting tool information encoded into the identity of the cutting tool in the system, and then by cutting tool conveying system in processing center, and finish with a tool to retrieve, flexible production line often need a FMS controller to run command.

In the past more than five axis machining center for Germany, the United States, Japan, Italy, happily in March this year in "China numerical control machine tool exhibition" held in Shanghai, exhibited more domestic production of five axis machining center. Like jinan 2 machine tool group co., LTD of five-axis linkage machining center, gantry work head 6 m, 2 m wide, with vertical spindle, A shaft Angle of plus or minus 100 degrees Fahrenheit, shaft Angle + 200 degrees C, the behemoth has attracted many visitors, it marks the Chinese nc machine tool industry has reached the advanced level. Shanghai third machine tool plant, lie fourth machine tool plant manufacturing processing center, 630 was the workbench, cold in the high-speed motorized spindle, the spindle can stand, lie transformation, workbench can be 360 degrees equal, similar to the above simple configuration to stand, lie the conversion of three axis machining center, can be achieved on the workpiece pentahedron processing, although there is no configuration for five axis, it is also very practical.

The development of the machining center and the future

Machining center is now gradually become the main equipment in the mechanical processing industry, its processing is wide and its usage. In recent years in terms of variety, performance, function has a great development. Varieties: a new type of stand, lie the five-axis linkage machining center, can be used in aviation, aerospace parts processing; Is specially used for mould processing high-performance processing center, integrated 3 d CAD/CAM of the complex surface superfinishing; Is suitable for cars, motorcycles, large quantities of parts processing of high speed machining center, high production efficiency and flexibility. Performance: generally used the turn over of motorized spindle, up to 6 ~ 100000 RPM; The application of linear motor machine tool acceleration to 3-5 g; Implement ISO/VDI testing standards and prompt manufacturers to increase two-way positioning precision of the machining center. Function: mix the compound function of laser processing, the structure is suitable for modular manufacturing cell (FMC) and flexible production line (FMS), and have the function of mechanical and electrical, communications integration.

One step ahead of the machine tool manufacturers are conceived "processing center" in 2010, it will be a universal equipment, can be used in the car, milling, grinding, laser processing, etc., become a real sense of the machining center. Fully automatic from material sent to, to the finished product output, rough finish machining, hardening treatment, superfinishing, automatic detection, automatic correction, will be omnipotent. Equipment will attach importance to environmental protection, energy saving, present a symbol of green manufacturing. Characteristics of era in the 21st century IT capabilities is absolutely cannot little, equipment will exchange information through the network and the outside world, get the latest technological achievements, the wisdom of the human will get full display on high-tech products processing center.