The structural characteristic of high speed machining center reachs a good point

    With the high speed machining center that machines at the mould, a common structural characteristic is to use structure of frame of dragon door type, enhance machine tool tigidity with this, and facilitate make full use of the space that machines an area. The material of machine tool lathe bed is most used polymer concrete, because this kind of material has better damp performance and inferior hot conductivity, reason is helpful for raising the treatment precision of the mould. Current, according to the configuration of reference axis, machining center basically can divide 5 axes for type of two kinds of structures. One kind is, 3 straight bobbin (X/Y/Z) is used at cutting tool moves and adding twice to rotate axis (the turn that A and C) use at workpiece and swinging structural type. The high speed machining center of this kind of type, like German R? The RXP500DS/RXP800DS of Der company, the GS1000/5-T of German Alzmetall company, the HSM400U/HSM600U of Swiss Mikro is the XSM400U/XSM600U that exceeds high speed machining center with what say, and the C30U/C40U/C50U of German Hermle. Another kind is, 5 reference axis swing medium axis (A) sets the structural type on main shaft head, swing through what head of furcate main shaft realizes main shaft cutting tool, and swing main shaft head also can pass firm clamp, make its fixed position is swinging the random inside angle limits locally. The machine tool of this kind of type is like the DMC75Vlinear/DMC105Vlinear of company of German De Maji, the GAMMA605/1200 of high speed milling machine of the HPM1850U of Mikro and German RolfWisser. Have individual machine tool swing axis and rotor all are installed go up in main shaft head, the 5 axes of the center of milling of G996V/BSH/5A high speed that is like German Parat company and German Edel company or 6 axes planer-type milling machine. Machining center of 5 axes high speed should compare 3 axes on the price machining center is a lot of higher, the 5 axes that occupy series of De Maji DMC75V machining center with 3 axes machining center undertakes the price is compared, 5 axes should be made an appointment with than the price of 3 axes tall 50% . Although price of machining center of 5 axes high speed is tall, but this kind of high-grade machine tool suits to use the pattern with treatment geometry mixed appearance particularly. Machining center is processing 5 rods deeper, steeper model when antrum, the add circumgyrate that can carry workpiece or main shaft head and swing to create first-rate craft condition to establish the treatment of milling cutter, avoid cutting tool and arbor and model antrum wall produces collision, reduce a knife to provide those who add man-hour to shake the danger with cutting tool damaged, be helpful for raising the durability of efficiency of the exterior quality of the mould, treatment and cutting tool thereby. When the user is purchasing machining center, it is to choose 3 axes machining center still is 5 axes machining center, answer to wait for a requirement to decide according to the complex degree of appearance of mould antrum geometry and precision. Can see in the process that innovates ceaselessly from high speed machining center, make full use of the newest achievement in current technology domain, use drive technology and the newest positive result that dominate a technology especially, it is to raise function of machining center high speed, dynamic character and the key that machine precision ceaselessly.   

    Electric main shaft  

    Main shaft of high speed report is the core component of high speed machining center. In the treatment of mould freedom curved surface and complex outline, often use lesser diameter of 2 ~ 12mm establish milling cutter, and when the electric spark that processing copper or black lead data machines used electrode, the cutting rate with very high demand, accordingly, electric main shaft must have very high rotate speed. Current, the main shaft rotate speed of machining center is in mostly 18000 ~ 42000r/min, rotate speed of its main shaft already amounted to the XSM400U/XSM600U of high speed machining center of Swiss Mikro 54000r/min. And the imperceptible milling to the mould (milling cutter diameter uses 0.1 ~ 2mm) commonly, need higher rotate speed. Be like the milling machine of 5 axes high accuracy of German Kugler company, its are highest 160000r/min(of main shaft turn up uses air bearing) , such high rotate speed, when the milling cutter that uses 0.3mm diameter machines steel model, with respect to the cutting rate that can achieve 150m/min. Current, institute of technology of German Fraunhofer production is developing rotate speed to be the main shaft that the air bearing of 300000r/min props up. When machining a mould, always use very high rotate speed, and what high rotate speed arises is calorific, and the main factor that the produces possibly vibration when cutting is precision of influence mould treatment. To assure the stability that main shaft of high speed report works, contain on main shaft with the sensor that will measure temperature, displacement and vibration, so that be opposite,displacement of the temperature rise of electric machinery, bearing and main shaft, axial and vibration undertake monitoring. The numerical control system that is high speed machining center from this provides correction data, in order to alter main shaft rotate speed and feed rate, undertake optimizing to machining parameter. Produce axial displacement when main shaft, can pass was amended at 0 o’clock or orbit is amended will undertake compensating.   

Linear electric machinery 

   Current, the majority on the high speed machining center that mould treatment uses or milling machine still uses servo electric machinery and ball guide screw to come drive is steep reference axis, but partial machining center already used linear electric machinery, for example machining center of milling machine of the RXP500DS/RXP800DS of German Röders company high speed and the DMC75Vlinear of company of heart auspicious horse high speed (its axis acceleration amounts to 2g and quick stroke speed to amount to 90m/min) . Because this kind of steep drive discharged the transmission component that circumgyrate athletic changeover is sharp movement, the dynamic performance that can improve an axis significantly thereby, floating rate and treatment precision. The machine tool that uses drive of linear electric machinery can improve productivity significantly. When machining electric spark to machine used electrode for example, handling time should decrease than using milling machine of tradition high speed 50% . Linear electric machinery can improve the dynamic performance of high speed machine tool significantly. Because mould great majority is three-dimensional curved surface, when cutting tool is machining curved surface, cutting tool axis should undertake apply the brake is mixed ceaselessly quickly. It is through higher axial acceleration talent only below very high path velocity case, ensure on shorter orbit way with constant every tine feed dogs given outline. If the curvature radius of curved surface outline heals small, feed speed heals tall, so the axial acceleration of the requirement heals tall. Accordingly, the axial acceleration of the machine tool affects the machines precision and cutting tool durability of the mould greatly.   

    Torsion electric machinery 

    On high speed machining center, of circumgyrate workbench swing and of head of furcate main shaft swing to wait for motion with circumgyrate, use torsion electric machinery extensively already to come true. Torsion electric machinery is a kind of synchronous electric machinery, its rotor secures the part that wants drive in place to go up directly, do not have mechanical drive component so, it resembles linear electric machinery is direct actuating device euqally. The drive of worm wheel worm that the angular acceleration that torsion electric machinery can achieve wants to compare a tradition is 6 times higher, swinging the acceleration when head of furcate main shaft can achieve 3g. Because torsion electric machinery can achieve extremely tall static state and dynamic and laden tigidity, rose thereby rotor and swing fixed position precision of the axis and repeat precision. Current, already had the high speed machining center of partial manufacturer, already used linear electric machinery and torsion electric machinery to part drive is steep axis (X/Y/Z) and circumgyrate swing axis (C and A) . Be like the RXP500DS/RXP800DS of R Er, the CyPort5 axis of De Maji’s DMC75Vlinear and Edel planer-type milling machine. What should allude is, the rotor photograph of the straight bobbin of direct drive and direct drive is combined, make all athletic rods have the machine tool higher dynamic performance and adjust characteristic, machined mould freedom curved surface to offer optimal condition for high rate, high accuracy and fast face quality thereby.  

    Control a system   

    CNC control system is the main component of high speed machining center, it is deciding the speed that the machine tool machines, precision and exterior quality greatly. Accordingly, to machining the high speed machine tool of mould freedom curved surface, the function of numerical control system has particularly important sense. When machining curved surface of high accuracy freedom, the cutting tool contrail that by small Duan Zhi line and circular arc form creates huge part program, these data shed need to control a system to store and be handled by the machine tool, accordingly, the accident of block processing time is the main index that decides CNC controls systematic work efficiency. Current, the) of system of ITNC530 numerical control that the block of system of high-grade CNC control handles time to be able to amount to 0.5ms(to be like Haidehan commonly, and the block processing time of system of individual numerical control already shortened 0.2 ~ 0.4ms. Apply at the system of contemporary CNC numerical control that mould high speed processes, besides providing promising to ensure the very short course with necessary place of speed of high speed feed handles time, still should have Nurbs and batten interpolation function, can have the job with the resolution of accept rice, so that quality of tall treatment precision and surface is acquired below the circumstance that high speed machines. Current, high-grade numerical control system also can have link with the CAD/CAM system of different manufacturer, data conveys to control a system to go up with very high rate from net of aether of CAD/CAM system classics. CAD/CAM is compositive go up to control system, can make the treatment of complex outline obtains the mould greatly favorable result, right shorten settling time and process designing time make very important contribution. On the machine tool of 5 axes high speed of afore-mentioned place quote, removing company of R Er is outside using the numerical control system that oneself develop, the system of ITNC530 numerical control that other basically is the 840D that used Xi Menzi and Hai Dehan company.  

Last word

  Come nearly 10 years, drive technology and the great progress that control a system, those who drove the ceaseless innovation of machining center structure and performance is ceaseless rise. The application of electric main shaft, linear electric machinery, torsion electric machinery and system of quick numerical control is the high speed to raising machining center, tall trends and tall treatment precision had conclusive effect. And in a variety of structure innovation that machine a machine tool in the mould, torsion electric machinery had particularly main effect. The turn that it uses at circumgyrate workbench not only and swing drive, and still apply at head of furcate main shaft swing or of main shaft head swing and circumgyrate drive, the 5 rods that make all sorts of different types from this machining center. And circumgyrate and swing the application of main shaft head, milling machine offerred the precision of high speed of type of door of 5 axes dragon that machines large mould to develop again technical support. Henceforth, the development key that raising main shaft rotate speed, dynamic function and journey rate further still is high speed machining center, this still should rely on the further progress of drive technology and numerical control technology not only, even component part of hang on machine tool is small the development of quantified development and shunt-wound machine tool. Can expect, henceforth in 5 years, the axial acceleration hopeful of high speed machining center or high speed milling machine achieves 3 ~ 4g, the quick stroke speed of reference axis achieves 100 ~ 140m/min.