Introduction of the hottest five axis machining ce

2022-08-24
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Introduction of five axis machining center and its difference from three axis and four axis

the most effective machining surface of vertical machining center (three axis) is only the top surface of the workpiece, and horizontal machining center can only complete the four-sided machining of the workpiece with the help of rotary workbench. At present, the high-end machining center is developing in the direction of five axis control, and the workpiece can complete the machining of pentahedron with one clamping. If equipped with a high-end five axis CNC system, it can also process complex spatial surfaces with high precision

vertical five axis machining center

there are two ways of rotating the shaft of this kind of machining center, one is the workbench rotating shaft. The workbench set on the bed can rotate around the X axis, which is defined as the a axis. The general working range of the a axis is +30 degrees to -120 degrees. There is also a rotary table in the middle of the workbench, which rotates around the Z axis at the position shown in the figure, which is defined as the c axis, and the c axis rotates 360 degrees. In this way, through the combination of axis A and axis C, the workpiece fixed on the workbench can be processed by the vertical spindle except the bottom surface. The minimum division value of axis A and axis C is generally 0.001 degrees. In this way, the workpiece can be subdivided into any angle to process inclined planes, inclined holes, etc. If the a-axis and c-axis are linked with the XYZ three linear axis, complex spatial surfaces can be processed. Of course, this requires the support of high-end CNC system, sample loading and unloading: sample clamping service system and software. The advantages of this setting method are 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, generally, the workbench cannot be designed too large and the load-bearing is small, especially when the rotation of axis A is greater than or equal to 90 degrees, the workpiece cutting will bring a great load-bearing torque to the workbench

the other depends on the rotation of the vertical spindle head (Figure). The front end of the main shaft is a rotary head, which can rotate 360 degrees around the Z axis and become the c axis. The rotary head is also equipped with an a axis that can rotate around the X axis, which can generally reach more than ± 90 degrees, realizing the same functions as above. The advantage of this setting method is that the spindle processing is very flexible, and the workbench can also be designed to be very large. The huge fuselage of the airliner and the huge engine shell can be processed on this kind of processing center. This design also has a big advantage: when we use the spherical milling cutter to process the surface, when the tool center line is perpendicular to the processing surface, because the vertex linear speed of the spherical milling cutter is zero, the surface quality of the workpiece cut by the vertex will be very poor. Using the design of spindle rotation, make the spindle turn an angle relative to the workpiece, make the spherical milling cutter avoid vertex cutting, ensure a certain linear speed, and improve the surface processing quality. This structure is very popular for high-precision surface machining of molds, which is difficult for the rotary machining center of the workbench. In order to achieve high precision of rotation, high-grade rotary shafts are also equipped with circular grating ruler feedback, and the indexing accuracy is within a few seconds. Of course, the rotary structure of this kind of spindle is relatively complex, and the manufacturing cost is also high

vertical five axis machining center with spindle rotation

the spindle gravity of the vertical machining center is downward, the radial force of bearing high-speed idling is equal, and the rotation characteristics are very good, so the speed can be increased. Generally, the high speed can reach more than 12000r/min, and the practical maximum speed has reached 40000 rpm. The spindle system is equipped with a circulating cooling device. The circulating cooling oil takes away the heat generated by high-speed rotation, drops to the appropriate temperature through the cooler, and then flows back to the spindle system. 10. The three linear axes of Y and Z can also be fed back by linear grating ruler, and the bidirectional positioning accuracy is within the micron level. As the rapid feed reaches more than 40 ~ 60m/min, the ball screws of X, y and Z axes mostly adopt central cooling. Like the spindle system, the cooled circulating oil flows through the center of the ball screw to take away heat

horizontal five axis machining center

there are also two ways for the rotation axis of this kind of machining center. One is that the horizontal spindle swings as a rotation axis, plus a rotation axis of the workbench to realize five axis linkage machining. This setting method is simple and flexible. If the spindle vertical and horizontal conversion is required, the workbench can be simply configured as a three-axis machining center with vertical and horizontal conversion only by indexing and positioning. The vertical and horizontal conversion of the spindle and the indexing of the workbench can realize the pentahedral processing of the workpiece, reduce the manufacturing cost, and it is very practical. The CNC axis can also be set for the workbench, with a minimum division value of 0.001 degrees, but without linkage, it becomes a four axis machining center for vertical and horizontal conversion, which can adapt to different processing requirements, and the price is very competitive

the other is the traditional workbench rotation shaft, and the a-axis of the workbench set on the bed generally has a working range of +20 degrees to -100 degrees. There is also a rotary table b axis in the middle of the workbench, which can rotate 360 degrees in both directions. This horizontal five axis machining center has better linkage characteristics than the first method, and is often used to process the complex surface of large impellers. The rotary shaft can also be equipped with circular grating ruler feedback, and the indexing accuracy can reach a few seconds. Of course, this kind of rotary shaft has a complex structure and is expensive

at present, the workbench of horizontal machining center can be larger than 1.25m2, which has no impact on the first five axis setting mode. However, the second five axis setting method is more difficult, because it is really difficult for the 1.25m2 workbench to do the rotation of axis A and to connect with the axis B rotary table in the middle of the workbench. The rotation speed of the spindle of the horizontal machining center is generally above 10000rpm. Because the spindle set horizontally has self gravity in the radial direction, the radial force of the bearing is uneven when it is idling at high speed. In addition, the larger BT50 tool handle is also used, and the maximum speed is generally up to 20000rpm. The rapid feed of horizontal machining center reaches more than 30 ~ 60m/min, the main shaft power is more than kW when exploring the new development path of plastic granulator technology, and the tool magazine capacity can be increased from 40 to 160 as needed. The processing capacity is far more than that of general vertical machining center, which is the first choice for heavy machinery processing

most machining centers can be designed as double worktable exchange. When one worktable runs in the processing area, the other worktable changes the workpiece outside the processing area to prepare for the processing of the next workpiece. The time of worktable exchange depends on the size of the worktable, which can be completed from a few seconds to dozens of seconds. Considering the structure of the newly designed machining center should be suitable for forming modular manufacturing unit (FMC) and flexible production line (FMS), the modular manufacturing unit is generally composed of at least two machining centers and four exchange worktables. The machining centers are all placed side by side, and the exchange worktables are lined up in front of the machine tool. If there are many exchange worktables, they can be arranged in two rows or even double-layer design. There is a station on both sides as the position of loading and unloading workpieces, and the exchange worktable on the other stations is installed with workpieces waiting for processing. A trolley will send the exchange worktable loaded with workpieces to the processing center according to the system instructions, or take out the completed exchange worktable from the processing center, and send it to the next station or directly to the unloading station to complete the whole processing operation. In addition to the trolley and exchange workbench, the flexible production line also has a unified tool library. Generally, there are hundreds of tools. The ID code information of the tools is stored in the system, and then sent to the machining center through the tool conveying system, and the used tools are retrieved. The flexible production line also needs a FMS controller to command the operation

in the past, most five axis machining centers were made in Germany, the United States, Japan and Italy. It is gratifying that many domestically produced five axis machining centers were exhibited at the "China CNC Machine Tool Exhibition" held in Shanghai in March this year. For example, the gantry five axis machining center exhibited by Jinan No.2 Machine Tool Group Co., Ltd. has a workbench 6m long and 2m wide. It uses a vertical spindle to rotate, with a-axis rotation angle of ± 100 degrees and c-axis rotation angle of ± 200 degrees. This behemoth has attracted many visitors, marking that China's CNC machine tool industry has reached an advanced level. The vertical and horizontal machining center manufactured by Shanghai No.3 machine tool plant and No.4 machine tool plant has a workbench of 630mm2 and adopts a high-speed internal cooling motorized spindle. The spindle can be converted vertically and horizontally, and the workbench can be divided 360 degrees equally. Similar to the above three-axis machining center simply configured as vertical and horizontal conversion, it can realize pentahedral machining of workpieces. Although it has not been configured with five axes, it is also very practical

development and future of machining center

now machining center has gradually become the most important equipment in the machinery processing industry. It has a wide range of processing and a large amount of use. In recent years, it has made great progress in variety, performance and function. Variety: there are new vertical and horizontal five axis machining centers, which can be used for aerospace parts processing; There is a high-performance Machining Center specially used for mold processing, which integrates 3D cad/cam to superfinish the complex surface of the mold; There are high-speed machining centers suitable for the processing of large quantities of parts of automobiles and motorcycles, with high production efficiency and flexibility. Performance: Motorized Spindles with more than 10000 revolutions are widely used, up to 60000 ~ 100000 revolutions; The application of linear motor makes the acceleration of machine tool reach g; Implement iso/vdi testing standards, and urge manufacturers to improve the bidirectional positioning accuracy of machining centers. Function: combined with the composite function of laser processing, it is structurally suitable for forming modular manufacturing unit (FMC) and flexible production line (FMS), and has the function of electromechanical and communication integration

the leading machine tool manufacturer is envisioning the "machining center" in 2010, which will be a universal equipment that can be used for turning, milling, grinding, laser processing, etc., and become a real machining center. It can automatically detect and realize the incombustibility of organic-inorganic composite materials from material feeding to finished product output, rough and fine machining, hardening treatment and ultra precision machining; Automatic correction through hydrophobic treatment process and binder modification treatment will be omnipotent. The equipment will attach importance to environmental protection and energy conservation, presenting the symbol of green manufacturing. The it function with the characteristics of the 21st century is absolutely indispensable. The equipment will exchange information with the outside world through the network and obtain the latest technology. I believe we can achieve a good result in 2016, and human wisdom will be fully displayed in the high-tech product processing center. (end)

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