The design of accurate vertical machining center and application
- source:PERFSO CNC Machining
5/22KW, main shaft rotate speed 15, 000r/min, BT40 knife handle; The time that change a knife (the knife arrives knife) 1.
5s, 7kg of weight of the biggest cutting tool, knife storage capacity measures 24; X of fast and floating rate, Y, Z is 48m/min, 48m/min, 36m/min respectively; ≤ of precision of the fixed position below circumstance of complete closed circuit 0.
008mm, repeat ≤ of fixed position precision 0.
004mm(carries out GB/T8771.
4 standards) . Mix as series product choose configuration, 5 axial linkage match revolving stage of two axes numerical control when control, workbench area size is Ø500mm, coordinate journey X, Y, Z is the) when 5 axes of 500mm, 500mm, 415mm(respectively; Main shaft rotate speed 12, 000r/min, 20, 000r/min is optional, knife handle can choose HSKA63. The stiffness design that designs design of process machine tool to design further progress to be machine tool structure from commonly used function, precision design, high speed changes design, error to compensate the contemporary and advanced machine tool such as design of technology, life and dependability design to design a technology. Design a requirement to realize accurate machine tool, integrated consideration had to each respect in machine tool design. To assure the rationality that machine tool structure designs, to the foundation, transmission system, main shaft and overall undertook finite yuan of analysis, the weak point that finds out a design tries to improve, be optimized to function of machine tool whole and very good direct action reachs since high rigid design. The initial stage of the process is developed in the design, preliminary devised the quadruplet plan with over all dimension and working area range are same and different structure, namely: Type of slide carriage of table of job of cross of type of ram of buy of the top that decide bridge, calm pillar, beam and calm pillar type of 3 coordinate unit 4 kinds of structures. Pass finite yuan of stiffness analysis and machining error analysis, reach plan 1(decides bridge to carry buy ram type on the head namely) stiffness is the biggest, and error allocation is more reasonable also, chose plan in be designed actually so 1. By plan the structure of 1 had a machine tool overall the design with the component, and be opposite according to blueprint the machine tool is overall undertook with the component finite yuan of analysis and structural parameter are improved, avoid the occurrence of weak point. Conclusion is as follows: Compare with photograph of congener vertical machining center, this machine tool has larger dominant position in the stiffness of each direction, integrated equivalent stiffness rises about 40% to double above, and the stiffness of 3 direction is worth evener (1) seeing a table. Express the 1 stiffness computation value with similar standards machining center to compare X of machine tool name to spend Ky(N/µm)Z Xiang Gang to spend Kz(N/µm) to stiffness Kx(N/µm)Y Xiang Gang 3 to other of K(N/µm) of integrated equivalent stiffness A46 of similar machining center.
7 by computation the result is knowable, the integral performance with overall machine tool is good, static stiffness is showing the machine tool to rise, can satisfy high speed, high spirit, efficient requirement. The advantage of structure of this kind of distribution is: Fission of lathe bed, pillar, and main component part all shows box shape structure, in treatment not changeful form, treatment craft sex is good; Combinative area is larger, the base is solid, main shaft is dangerous extend small, integral structure stiffness is tall; Influence design of completely symmetrical type, main shaft X is better to hot balance; Y to dangerous extend small, heat is out of shape the impact is little; Part of shift of axis of X, Y, Z is small, acceleration is good; Component part structure assures slideway motion precision easily firm, precision stability is good. To make sure the precision of the machine tool is stable, use box of lathe bed, pillar, slide carriage, main shaft finite yuan of analysis, those who use tall damp property is high grade and cast-iron make; Reasonable sectional design and muscle case are decorated, unreasonable cantilever position appears in preventing the stroke as far as possible; Slideway uses guide of high rigid roller, nicety of installation tool reference plane is blown grind. µ1000 series machine tool is broken normally machine tool configuration, lathe bed is used propped up at 3 o'clock, tall tigidity is designed, make the machine tool is adjusted simple, do not rely on foundation, the machine tool can not want special foundation and direct installation is on cement ground level ground. What lathe bed sheds a principle with the force that is based on the quadrature that do not have a turn is special muscle board design, make sure the component on its is in athletic process, laden centre of gravity and cutting dot do not leave the range that propped up at 3 o'clock from beginning to end, have the enough stiffness that prop up, be helpful for maintaining the stability of precision. Slide carriage uses structure of type carrying buy on the head, its characteristic is high rigid and light-duty design, make athletic unit agile, get used to high speed requirement. Slideway of pillar of slide carriage edge makes X to motion, lengthen slideway props up length, the slide carriage when motion does not leave slideway from beginning to end, easy assure precision of linearity, fixed position and treatment precision. Workbench makes only way only (Y to) mobile, as lighter than mobile component as photograph of crossed workbench structure, and bearing big, the design bearings be more than 800kg. Additionally direction of workbench edge slideway moves, structural tigidity is good, athletic precision is tall, avoided workbench of traditional machine tool to move linearity of two end after is reduced or problem of out of tolerance. Structure of box of prolate main shaft, make main shaft centre of gravity stands by X guide course as far as possible, main shaft center and slideway are apart from 295mm, reduce 5 than traditional machine tool, such main shaft are dangerous extend small, rules getting a turn is petty. Additionally slideway installation is on main shaft box, slide block is on slide carriage, enhanced sex of Z Xiang Gang greatly, rose to machine precision and athletic stability, fixed position precision is tall. Used the roller guide with bigger width, medium preload carry on one's shoulder eliminated clearance and crawl, raise systematic stiffness and athletic precision. Linear axis drive uses servo electric machinery to drive guide screw of high speed ball deputy, it is adopted tighten form of type odd nut beforehand, the structure is compact. Of guide screw prop up use two end to secure prop up and bring to bear on beforehand drawing, in order to raise transmission system stiffness, absorb guide screw to give out heat the heat that cause is stretchy the error that cause. The shaft coupling between guide screw and electric machinery chooses ripple to provide a form, its advantage is: Transmission efficiency is tall, rigid good, deliver torque big, turn round stiffness tall, and oneself moment of inertia is small, get used to high speed sex. The length that adds pedestal appropriately in order to increase nut reach guide screw bearing with the foundation a combinative scale stiffness, adopt on craft at the same time deserve to blow grind technology, make precision enters stability period directly, increase surge resistance. Form report main shaft is installed inside tall tigidity, bearing is chosen before in 4 backs of preload contact ball bearing of pottery and porcelain to bearing high speed wine cup, Ø70 of bearing internal diameter, this kind of combination makes bearing can bear at the same time radial and axial load, stiffness of main shaft activity is tall. Pound to decrease, raise fixed position precision, control system set Zhong Xing adds decelerate function and HRV(HighResponseVector) control function, adjusted the position that affects dynamic performance and speed gain. In the meantime, grow life to design to come true, the to precision of a few influences and character of service crucial part in the design took corresponding step, be like: Because main shaft bearing uses oil gas to lubricate, partial oil gas can enter electric machinery stator and rotor between, make electric machinery is polluted and affect performance characteristics and life, to overcome this, before electric machinery after end all has inbreathe of gas of cleanness of dry of low pressure male, local form slight pressing, enter in order to prevent oil gas, make sure electric machinery performance is steady, life is long; Enter bearing to avoid main shaft front to have dirty thing, the useless oil that prevents bearing oil gas to lubricate is oozy go up to main shaft end panel, foremost end adds main shaft to be enraged all the way, come loose with preventing to dirty content is entered and be blown useless oil; The revolving stage electric machinery of 5 axes linkage moves directly at working zone time, dirty content may enter electric machinery, influence life, for this, bonnet of on revolving stage two report all is added low-pressure gas blows air, form pressing, prevent an eyewinker to invade; Maintain precision to make sure grating is long, improve service life, the reading of grating also has the air inbreathe of male dry cleanness on the head. To assure high accuracy, a variety of measure are used be out of shape in order to reduce the heat of the machine tool and oscillatory. If main shaft covers bearing of the after before the canister is mixed constant temperature loop is cooling, oil gas is lubricant reduce bearing to give out heat, after bearing uses columnar roller bearing, once produce heat to be out of shape, main shaft to after stretchy, do not affect treatment precision; Cutting tool of large flow refrigeration and workpiece, reduce generation of heat in metal cutting; On lathe bed two helix discharge bits implement will cut bits eduction airframe in time, avoid to cut bits a large number of accumulation cause lathe bed heat to be out of shape; Type designs machine tool semmetry, balance heat is out of shape etc; Main shaft has function of the refrigeration inside the center, cold the greatest pressure is 22bar inside, can satisfy treatment of high speed cutting, alveolus and deep aperture treatment to take away treatment caloric expeditely to discharging bits, in time to ask. To make main shaft movement smooth, reduce noise, reduce vibration, use dynamic balancing twice to main shaft, be in main shaft and after of rotor shrinkage fitting, had assembled the 2nd times in all circumgyrate spare parts and geometrical precision examines ending after. Such dynamic balancing precision are tall, make sure circumgyrate precision is mixed prevent vibration. Additional, before main shaft after position design has balance link in order to have online dynamic balancing is used. Knife library is put in the opposite side of the machine tool, with alone foundation, the vibration that produces when knife library and manipulator change a knife so and lopsided won't pass to lead plane, the to load outside removing one part carries on his shoulder or back, make machine tool precision stabler. Raise the fixed position precision of the machine tool and treatment precision to be below higher athletic rate, locate especially precision, precision was installed on the machine tool for 0.
The HEIDENHAIN of 003mm is enclosed absolutely grating feet, have full closed-loop control. But the fixed position precision of the machine tool can evaluate a machine tool only the precision when specific place, when if be far from,measuring a face to undertake machining, the position of treatment is spent can have bigger error. And traditional pitch compensation can is opposite only the pitch error of specific place guide screw undertakes compensating, can not reduce the position alignment error of whole treatment face in the round. To eliminate the position alignment error inside treatment area as far as possible, raise the treatment precision of the machine tool, increased dimensional error to compensate a function, collect data through many experiment, computation gives the geometrical error that the machine tool nods in each space, compensate in real time through CNC system accord. Main shaft is in locomotive process, because of,electric machinery, bearing and other motion component are met the generation quantity of heat such as attrition, loss. If quantity of heat cannot send out in time with eduction, can affect machine tool precision badly. Accordingly, to coat of main shaft electric machinery and bearing coat undertakes circular cooling with the kind that carries constant temperature oil, make the quantity of heat of the majority in process of main shaft movement takes an airframe along with circular oil, be out of shape in order to reduce heat. But, refrigeration is again perfect because conduct speed,still also can have partial quantity of heat fast and cannot seasonable eduction, make main shaft produces heat to be out of shape. To solve main shaft further heat is out of shape the influence to precision, main shaft Z to heat is out of shape method of usable software compensatory undertook compensating. Compensating data is obtained through the experiment. Have versatility more to make compensate software, variable process designing is used, give these variable assignment respectively in the light of different machine tool, different use situation, can create a specific aim, practical compensation program. Because have 48m/min of taller fast and floating rate,the implementation of tall productivity is, 30m/min of tall cutting feed speed, the biggest 0.
The acceleration of 9g; High main shaft rotate speed 12, 000~20, 000r/min and the high rate that change a knife 1.
5s. Main shaft electric machinery chooses electric machinery of the outfit inside the &alphaBi series of FANUC, have low speed winding and high speed winding, in low speed winding rated rotate speed is when 1500r/min is the following, constant torque amounts to 118Nm, although heighten comes when 4000r/min, still have the bigger torque output of 36Nm~44Nm, although,fall in high speed winding 20, when 000r/min, still also have 8.
The torque of 8Nm~11Nm is outputted, constant power range is wide, can realize cutting of low speed big torque and high speed treatment. Of the machine tool supported a construction at 3 o'clock, facilitate according to product line need adjusts the position to come true to recombine quickly, shortened machine tool installation debugs cycle, managing adjust man-hour. Of the machine tool modular the design basically reflects the crossing-over in BT40 and HSKA63 knife handle; Revolving stage and workbench can change each other conveniently; Slideway and guide screw can choose the product of different production manufacturer according to user demand, wait like STAR, NSK, THK. Machining center can configure milling machine of numerical control high speed, 3 axes, four-axle, 5 axes quickly come out. Hydraulic pressure, lubricant, cooling design and electric design all can differ according to the user requirement and different configuration accept or reject conveniently; Differ according to the user demand, it is OK also that revolving stage banking angle is spent the change, widened the choice face of the user is mixed use face. Whole sealing shield ensures condition of high speed, efficient treatment leaves worker safety in operation. Use grease segregator, the oil in cooling fluid content depart filters, prolong the service life of cooling fluid, raise cooling fluid to use the effect, and accord with environmental protection requirement. Range of application of machining center of vertical of applied µ1000 series is very wide, the machine tool is exact form machining center, each precision includes geometrical precision, treatment precision to all be the exact form of national level, and fixed position precision compares exact form to still raise one times. The tall tigidity of the design falls in the premise of contented high accuracy, still have very strong cutting capacity. Applied limits is as follows: The casing of the lid of crock of engine cylinder body of the car, brake, gearshift, big batch that turns to the spare parts such as section, reducer is produced and machine; Spin industry board kind spare parts treatment; Oil pump is oily the spare parts such as body of the switch body that wait, a powerful person, lamina, impeller mixes industry, tabulation industry, mould industry the treatment of the mould. Be in already in the machine tool of work off, use at car engine crock lid and advocate, the machine tool on product line of poor reducer housing, can improve product line technology, raise productivity and precision; Use at the machine tool of aerospace industry, the spare parts with high demand of complex, precision processes can contented form, and Bao Bi is light-duty the treatment of the spare parts, make the new product that has strong market competition ability, obtained good society and economic benefits. After of success of this product development had verdict overall performance experiment, experience card satisfies a design completely to ask, and in condition of structure, movement stiffness is mixed precision respect shows scene. Meet in new product appraisal the spot, precision of fixed position of Z axis actual measurement 3.
4µm, repeat fixed position precision to be less than 1.
7µm; Milling of the milling cutter that use end is aluminous, exterior surface roughness is Ra0.
04µm. It is indicating the machine tool moves rotate speed, quickly in main shaft the respect such as precision of speed, position all reached higher level, formed new generation series of high-powered vertical machining center; Research achievement implementation is commercial, seriation, modular; The product uses the part that supported Gao Gang to sexual structure is designed and be based on dependability to grow an analysis at 3 o'clock to reach yuan of parts of an apparatus to design on integral structure, ensured machine tool high speed, high spirit and Gao Ke rely on a gender; Be out of shape in heat error compensation and respect of compensation of planar position error have the advantage such as distinctive technology, satisfied the market need to accurate vertical machining center, already had pre production and sale. CNC Milling