Brief introduction of processing technique of milling of mould high speed

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The article is mixed from knife handle of machine tool structure, cutting the technical characteristic that the respect such as process designing of craft of cutting tool, treatment, numerical control told about high speed milling in detail and the application that process a trade in the mould. Although the article is written relatively macroscopically, but content is relatively comprehensive, understand the reader of mould domain in the round and use high speed processing technique, still have stronger direct sense. One, preface is in contemporary mould production, as to model beautiful degree reach a function to ask higher and higher, model internal composition is designed more and more complexly, the appearance design of the mould is complex with each passing day also, place of free curved surface occupies scale to increase ceaselessly, corresponding mould structure also is designed more and more complexly. These raised taller requirement to mould processing technique, should assure tall production precision and exterior quality not only, and what should seek treatment appearance is beautiful. As the ceaseless development that studies to high speed processing technique, machining what the relevant technology such as software of system of machine tool, numerical control, cutting tool system, CAD/CAM develops ceaselessly to drive especially below, the treatment that high speed processing technique uses increasingly already at mould antrum and in making. Cutting of numerical control high speed machines a most important advanced production technology in be being made as the mould, it is collect efficient, high grade, low cost the advanced production technology at a suit. Machine at traditional cutting relatively, its cutting speed, feed speed had very big rise, and cutting mechanism is not same also. High speed cutting makes cutting machines the leap that produced substaintial sex, the metallic excision rate of its unit power rose 30%~40% , cutting force was reduced 30% , the cutting life of cutting tool rose 70% , the heat in metal cutting that stays at workpiece is reduced substantially, low rank cutting vibration disappears almost. As cutting speed rise, the purify rate of material of unit time semifinished product increased, cutting time decreased, treatment efficiency rose, shortened thereby the production of the product is periodic, enhanced the market competition ability of the product. In the meantime, the grain speed that high speed machines makes cutting power decreased, the high speed eduction that cuts bits reduced the cutting force of workpiece and thermal stress to be out of shape, raised the possibility of rigid difference and treatment of cutting of thin wall spare parts. As a result of cutting force reduce, of rotate speed rise those who make the working frequency of cutting system is far from a machine tool is low rank natural frequency, and the exterior surface roughness of workpiece is right low rank frequency is most sensitive, reduced exterior surface roughness from this. The hard steel of high temper by dipping in water in the mould (in the treatment process of HRC45~HRC65) , use high speed cutting to be able to replace the working procedure of electric treatment and grinding polish, avoided the electric treatment of the production of electrode and take time thereby, reduced the burnish of benchwork and polishing amount substantially. Provide work to the Bao Bimo that needs more and more on a few markets, high speed milling also can be finished smoothly, and go up in machining center of CNC of high speed milling, the mould holds clip treatment of achievable multitask pace. High speed processing technique machined craft to produce tremendous effect to the mould, changed traditional pattern treatment to use " grinding of heat treatment → of → of treatment of anneal → milling " or " manual burnish of → of electric spark treatment, polish " wait for complex and lengthy technological process, treatment of cutting of usable even high speed replaces original whole process. High speed processing technique divides the applicable immediate treatment at strong pattern of temper by dipping in water antrum (especially semifinishing machining and finish machining) outside, in EDM electrode treatment, sudden appearance make waited for a respect to also get applied extensively. Mass-produced practice makes clear, the manual and abrade time of 80% is restricted in applying technology of high speed cutting to be able to save mould follow-up to machine, charge of managing finished cost is close 30% , mould surface machines precision to be able to amount to 1m, efficiency of cutting tool cutting can raise 1 times. 2, one of main development direction that technology of cutting of high speed of machine tool of treatment of high speed milling is cutting processing technique, it waits for fundamental technology as CNC technology, microelectronics technology, new material and new structure develop and stride higher chance to extricateoneself from an awkward position. As a result of the oneself characteristic of the characteristic that the mould machines and high speed processing technique, the relevant technique that processes to mould high speed and machining complex (system of treatment machine tool, numerical control, cutting tool) put forward to machine higher demand than traditional pattern. 1.

The component propping up such as the lathe bed of machine tool of cutting of high speed of the component that prop up should have the machine tool of tall stability to be moved very well, static stiffness, heat up stiffness and first-rate damp character. Major machine tool uses high quality, tall tigidity and Gao Kang piece sexual casting pig regards the component that prop up as material, some machine tool companies still add the polymer concrete of tall damp character in base, fight in order to increase its brace up gender and thermal stability, this not only can make sure machine tool precision is stable, the cutting tool when also can preventing cutting brace up quiver. Use enclosed lathe bed design, whole casts lathe bed, structure of symmetrical lathe bed deserves to densely covered reinforcement waits also is the important step that increases machine tool stability. The branch of research and development of company of a few machine tools is in design process, still use mode analysis and finite yuan of structure computation, optimized a structure, make the machine tool component that prop up more stable and reliable. 2.

The main shaft function of machine tool of high speed of machine tool main shaft is the fundamental condition that realizes treatment of high speed cutting. The rotate speed limits of main shaft of machine tool of high speed cutting is 10000~100000m/min, main shaft power is more than 15kW. Through main shaft compresses air or cooling the system controls the axial clearance between knife handle and main shaft to be more than 0.

005mm. Still ask main shaft is had rise quickly fast, the function that showing emplacement allows to stop quickly (have extremely tall horn to add decelerate to spend) namely, because main shaft of this high speed often uses a liquid static pressure bearing type, air is static press nitrogen of bearing type, hot pressing to change silicon (Si3N4) the configuration such as type of bearing of in suspension of magnetism of bearing of pottery and porcelain. Lubricate to use oil gas more eject is lubricant, lubricant wait for a technology. Main shaft refrigeration uses water-cooling of main shaft interior or air cooling commonly. 3.

System of machine tool drive is the need that contented mould high speed machines, high speed machines the drive system of the machine tool to should have following character: (The feed rate with high 1) . Consider to make clear, to small diameter cutting tool, raise rotate speed and every tine feed to be helpful for reducing cutting tool to wear away. At present commonly used feed speed limits is 20~30m/min, if use transmission of guide screw of big lead ball, feed speed can amount to 60m/min; Use linear electric machinery to be able to make feed speed achieves 120m/min. (The acceleration with tall 2) . To the high speed of profile of three-dimensional and complex curved surface treatment asks drive system has good acceleration character, the driver that asks to offer high speed feed (speed speed makes an appointment with 40m/min, 3D outline machines speed to be 10m/min) , can offer 0.

4m/s2 is spent to the acceleration of 10m/s2 and decelerate. Machine tool manufacturer uses guide screw of the ball guide screw of small lead of pilot of servo of position of complete closed circuit, large size, high quality or big lead bull mostly. As the development of electric machinery technology, advanced linear motor has come out, apply successfully at CNC machine tool. Advanced linear electromotor drive makes CNC machine tool has quality no longer the problem such as inertial, lead, lag and vibration, accelerated servo to answer speed, raised servo to control precision and precision of machine tool treatment. 4.

The numerical control system with numerical control advanced system is to make sure the pattern is mixed the crucial factor of quality of treatment of curved surface high speed and efficiency, cutting of mould high speed machines logarithm to accuse main demand of the system to be: (1) high-speed number dominates return circuit (Digitalcontrolloop) , include: 32 or 64 collateral processor and 1.

The hard disk of 5Gb above; Cutty is linear time of electric machinery sampling. (Of 2) speed and acceleration before make a present of is controlled (Feedforwardcontrol) ; The crawl of digital drive system is controlled (Jerkcontrol) . (The interpolation method with advanced 3) (the batten interpolation) that is based on NURBS, in order to obtain good exterior quality, exact size and tall geometrical precision. (4) pretreatment (Look-ahead) function. The requirement has register of high capacity amortize, can be read beforehand and check many block (if DMG machine tool can amount to 500 block, simens system can amount to 1000~2000 block) , so that be being machined exterior figure (curvature) when producing change can adopt the measure such as change feed speed in time to wait with avoiding to cut. (5) error compensates a function, the hot error compensation that because the hair thermal conductivity such as linear electric machinery, main shaft is sent,includes, quadrantal error compensation, measure systematic error compensation to wait for a function. In addition, the demand that treatment of cutting of mould high speed transmits speed to data is very high also. (The data interface of 6) tradition, if RS232 is serial,transmission speed of the mouth is 19.

2kb, and a lot of advanced machining center already all used aether local area network (Ethernet) undertakes data is transmitted, speed can amount to 200kb. 5.

Treatment of cooling and lubricant high speed uses the hard alloy cutting tool that takes coat, fall in the circumstance of high speed, high temperature need not cutting fluid, cutting efficiency is taller. Because,this is: High speed of milling main shaft rotates, if cutting fluid wants to reach cutting area, want to overcome huge to leave mental efforts above all; Although it overcame centrifugal force to enter cutting area, likely also as a result of the high temperature of cutting area evaporate instantly, cooling effect is very little do not have even; At the same time cutting fluid can make the temperature of ministry of cutting tool blade intense change, bring about the generation of crackle easily, should use oil so / the means of dry type cutting with gas lubricant refrigeration. This kind of means can use high-pressured gas to blow the cutting that cutting area produces quickly, walk along many cutting tropics thereby, at the same time the lube of classics pulverization can be in ministry of cutting tool blade and workpiece surface form a paper-thin microcosmic diaphragm, can prolong cutting tool life effectively and improve the exterior quality of the spare parts. 3, because when high speed cutting is machined, the knife handle that high speed cutting machines and cutting tool leave mental efforts and oscillatory effect, requirement cutting tool has very tall geometry precision and outfit clip to repeat the sex of on the safe side of fixed position precision and very tall stiffness and high speed dynamic balancing. Because high speed cutting adds the centrifugal power with greater man-hour and vibration to wait for a characteristic, traditional 7:2System of 4 taper knife handle shows apparent rigid inadequacy when undertaking high speed cutting, repeat fixed position precision dimension of not tall, axial is flabby wait for blemish surely, of main shaft expand the deviate that causes cutting tool and clamp orgnaization centroid, affect the dynamic balancing ability of cutting tool. The heat that application is at present more is knife handle of HSK high speed and foreign nowadays popularity bilges knife handle of style of cold crimple firm. Heat bilges knife handle of style of cold crimple firm has heat system, knife handle uses awl ministry and main shaft end panel to be contacted at the same time commonly, its tigidity is better, but cutting tool can change a gender poorer, a knife handle can install the cutting tool of diameter of a kind of join only. Heat as a result of this kind the system is more expensive, HSK is used when initial stage kind knife handle system can. When the amount of high speed machine tool of the enterprise exceeds 3 above, use heat to bilge knife handle of style of cold crimple firm is more appropriate. Nextpage cutting tool is one of the most active and main factors in treatment of high speed cutting, it is affecting the treatment precision that processes efficiency, production cost and product directly. Cutting tool should bear in process of high speed treatment the load such as high temperature, high pressure, attrition, concussion and vibration, cutting tool of high speed cutting should have good mechanical performance and thermal stability, have the good character that fights caustic of concussion, wear-resisting and heatproof exhaustion namely. The rate of development of cutting tool technology that high speed cutting machines is very rapid, application is more like diamond (PCD) , cubic nitrogen changes boron (hard alloy of cutting tool of CBN) , pottery and porcelain, coating, (carbon) nitrogen changes titanium hard alloy TIC(N) . Machining cast-iron in the cutting cutting tool with alloy steel, hard alloy is the most commonly used cutting tool material. Wearability of hard alloy cutting tool is good, but hardness changes boron and pottery and porcelain than cubic nitrogen low. To rise hardness is mixed the surface is bright and clean degree, use technology of cutting tool coating, coating material changes titanium for nitrogen (TiN) , nitrogen changes aluminous titanium (TiALN) . Coating technology makes coating develops the coating that is a variety of multilayer, coating material by onefold coating, already made one of crucial technologies that increase capacity of high speed cutting. The diameter is inside 10~40mm limits, and the hard alloy bit that carbolic nitrogen changes titanium coating can machine Rockwell hardness to be less than the material of 42, and the cutting tool that nitrogen turns titanium aluminous coating can machine Rockwell hardness to be 42 more expensive even stuff. When steel products of high speed cutting, cutting tool material should choose the P with hot rigid and fatigue high intensity kind hard alloy, coating hard alloy, cubic nitrogen changes boron (CBN) material of as compound as CBN cutting tool (WBN) etc. Cutting is cast-iron, the K that should choose fine grain kind hard alloy undertakes rough machining, choose compound nitrogen changes silicon pottery and porcelain or get together nitrogen of brilliant cubic metre changes boron (PCNB) compound cutting tool has precision work. When nicety processes nonferrous metal or metalloid data, should choose get together brilliant diamond PCD or cutting tool of CVD diamond coating. When choosing cutting parameter, be aimed at round razor blade and ball head milling cutter, should notice the idea of effective diameter. Cutting tool of high speed milling should be made by dynamic balancing design. Of cutting tool before horn compares groovy cutting tool before horn wants small, hind horn slightly big. Advocate joint of deputy cutting blade should repair a circle or guide horn, will increase role of point of a knife, prevent point of a knife to be in heat to wear away. Should increase the cutting blade length near point of a knife and volume of cutting tool material, raise cutting tool tigidity. Below the condition that assures safety and contented treatment requirement, cutting tool is dangerous extend as far as possible short, tenacity is close friends in the center of cutter hub. Knife handle should compare cutting tool diameter brawny, join handle submits awl form, in order to increase its tigidity. It is as far as possible in the center of cutting tool and cutting tool system stay have cooling fluid opening. Ball head stands milling cutter to want to consider effective cutting length, point wants as far as possible short, head of ball of two helix chamfer stands milling cutter to be used at thick mill normally complex curved surface, head of ball of 4 helix chamfer stands milling cutter to use Yu Jingxi normally complex curved surface. 4, craft of treatment of mould high speed and the rough machining that high speed treatment includes strategy to be a purpose with purify surplus, remain rough machining, and the semifinishing machining that is a purpose in order to get the treatment surface of high quality and fine structure, finish machining and lens face treatment. 1.

The main goal of rough machining of rough machining mould is the material purify rate inside pursuit unit time, prepare the geometrical outline of workpiece for semifinishing machining. The craft plan that the rough machining place in high speed treatment should adopt is the combination of rate of tall cutting speed, tall feed and small cutting dosage. Waiting for tall treatment means is the means of a kind of treatment that numerous CAM software uses generally. Application is more is helix wait to be mixed high wait for Z axis two kinds tall means, machining area namely only feed, carrying successive and slick cutting tool way is made below the circumstance of the knife, into, the means that retreat a knife uses circular arc to be cut, cut. The characteristic of the high fashion such as helix is, did not wait for the cutter track shift between the high level, can avoid to carry often the consume with the influence of knife, feed to quality of spare parts surface and mechanical needless equipment. Handle respectively to area of abrupt peace calm, computation suits to wait to be reached high suit to use similar 3D to slant the area of buy, and can use helix means, carrying rarely optimized cutting tool way is made below the circumstance of the knife, acquire better exterior quality. In high speed treatment, must adopt circular arc to be cut, cut join way, and turning point circular arc transfers, avoid to change way of cutting tool feed suddenly, taboo leaves the join way of the knife directly, avoid workpiece of cutting tool embedded. When machining mould antrum, should avoid cutting tool perpendicular insert workpiece, and should use tilt means leaving a sword (commonly used banking angle is) of ° of 20 ° ~30, had better use the knife below screw type in order to reduce cutting tool load. When machining mould core, answer to cut work from the level after Dao Ran of the following outside workpiece first as far as possible. Cutting tool is cut, bend inclined should be used as far as possible when cutting a work (or circular arc type) cut, cut, avoid perpendicular cut, cut. Use climb cutting climbing type to be able to reduce heat in metal cutting, reduce cutting tool to get force and treatment sclerosis rate, improve treatment quality. 2.

The main goal of semifinishing machining of semifinishing machining mould is to make level off of workpiece outline appearance, surplus of exterior precision work is even, this is attached most importance to especially to tool steel mould should, because it will affect the change of the change of area of cut of the cutting tool when finish machining and cutting tool load, affect the stability of cutting process and quality of finish machining surface thereby. Rough machining is to be based on volume model, finish machining is to be based on scale model. The CAD/CAM system that develops previously is discontinuous to the geometrical description of the spare parts, after because do not have,describing rough machining, the intermediate information that the model processes before finish machining, the odd mental allowance of surface of reason rough machining distributings reaching the biggest odd mental allowance all is sealed. Because this answers,strategy of half-and-half finish machining makes optimizing have even odd mental allowance in order to assure surface of the workpiece after semifinishing machining. Optimize a process to include: The the computation of outline of rough machining rear wheel, computation of the biggest odd mental allowance, biggest the deciding that allows mental allowance, right odd mental allowance is more than the biggest allow mental allowance model face partition (the area that is less than radius of rough machining cutting tool like the radius blend such as groove, corner) and semifinishing machining. Existing mould high speed machines CAD/CAM software to have odd mental allowance to analyse a function mostly, can reach distributinging circumstance to use sound semifinishing machining strategy according to the size of odd mental allowance. If MasterCAM software offerred bunchy milling (Pencilmilling) and odd milling (the method such as Restmilling) will keep clear of the odd mental allowance is bigger corner after rough machining in order to assure the mental allowance with follow-up even working procedure. 3.

The strategy of high speed finish machining of finish machining mould depends on the osculatory dot of cutting tool and workpiece, and the contact of cutting tool and workpiece nods the curved surface slope as treatment surface and cutting tool to have effect radius change and change. To the treatment of complex curved surface that be combined by many curved surface and becomes, answer to have successive treatment in a working procedure as far as possible, is not right each curved surface undertake machining respectively, carry in order to decrease the frequency of next knife, knives. However, as a result of the change of slope of the surface in treatment, if define the side penetration of a cutting tool of treatment only,measure (Stepover) , cause what differ in slope possibly apparently actual step pitch is inhomogenous, affect treatment quality thereby. Usually, 1 what the curvature radius of finish machining curved surface should be more than cutting tool radius.

5 times, in order to avoid the abrupt change of feed direction. In the high speed finish machining of the mould, cutting every time, when cutting a work, the change of feed direction should use circular arc as far as possible or the curve turns receive, avoid to use turn point-blank receive, in order to maintain the smooth stability of cutting process. Strategy of high speed finish machining includes three-dimensional slant buy, etc expensive precision work and optimal wait for the strategy such as the expensive precision work, expensive precision work such as helix. These strategy can make sure cutting process light is suitable, stable, ensure the material on workpiece of can fast excision, get high accuracy, slick cutting surface. The main demand of finish machining is to should acquire quality of very tall precision, smooth spare parts surface, realize the treatment of careful area easily, wait like small round part, groove. To a lot of appearance, the strategy with the most significant precision work is to use three-dimensional helix strategy. Use this kind of strategy to be able to avoid to use parallel strategy and slant the frequent directional change that the conference in strategy of buy finish machining appears, raise treatment rate thereby, reduce cutting tool to wear away. This strategy is carrying rarely successive and slick cutting tool way is made below the circumstance of the knife. This kind of processing technique is integrated helix treatment and the advantage that wait for tall treatment strategy, cutting tool bear is stabler, the frequency that carry a sword is fewer, can shorten handling time, reduce machine of cutting tool attaint to lead. It still can improve treatment surface quality, the biggest be restricted the need of manual burnish after the ground reduces finish machining. Area of calm of peace of expensive precision work waits in what a lot of circumstances need will abrupt area union of method of three-dimensional and equidistant finish machining rises use. Numerical control process designing also should consider geometrical design and craft arrangement, when use CAM system undertakes high speed machines numerical control process designing, outside choosing according to particular case except cutting tool and treatment parameter, the choice that machines a method and adoption process designing strategy became a key. The process designing engineer of an outstanding use CAD/CAM workstation also should be an eligible design and technology division at the same time, he should have a proper understanding to the geometrical structure of the spare parts, have the knowledge that designs to arrangement of ideal working procedure and contrail of reasonable cutting tool and idea. 5, the demand that milling of high speed of process designing of numerical control of high speed cutting machines logarithm to control process designing system is higher and higher, the high speed with high price machined equipment to raise higher security and effectiveness requirement to software. High speed cutting is having more special than traditional cutting craft demand, besides wanting to have machine tool of high speed cutting and cutting tool of high speed cutting, having software of appropriate CAM process designing also is crucial. The numerical control instruction of CNC Machining included all process, a system of excellent process designing of CAM of high speed treatment should have very high computation rate, stronger interpolation function, whole journey to cut examination and processing capability, automatic knife handle and clamping apparatus automatically to interfere rate of examination, feed to optimize processing too function, need treatment contrail of orbit monitoring function, cutting tool. Process designing of high speed cutting should notice to machine methodological security and effectiveness above all; Next, want all likelihoods to make sure cutting tool contrail is smooth and smooth, this can immediate impact machines the life of the spare parts such as quality and machine tool main shaft; Finally, want to make cutting tool load even as far as possible, this meeting affects the life of cutting tool directly. 1.

CAM system should have very tall consideration use in treatment of high speed of process designing speed very small feed and cut deep, its NC order is larger than wanting to program of traditional CNC Machining much, consequently speed of requirement software computation wants fast, in order to save editor of cutting tool contrail and the time that optimize process designing. 2.

Whole journey has been prevented automatically cut processing capability and interference of automatic knife handle to check treatment of ability high speed to machine the cutting speed of nearly 10 times to undertake machining with the tradition, once had happened to cut pair of machine tools, product and cutting tool to will produce disastrous consequence, ask its CAM system must have whole journey to had prevented the capacity that cuts processing and automatic knife handle and examination of clamping apparatus interference automatically so, circle avoid function. The system can hint the briefest clip runs cutting tool length automatically, undertake cutting tool interferes an examination automatically. 3.

Treatment of rich high speed of strategy of contrail of cutting tool of high speed cutting walks along knife means to having special demand than traditional pattern to machining craft, to can ensure the biggest cutting efficiency, assure the security that machines when high speed cutting again, CAM system should is opposite automatically according to processing the volume of instantaneous surplus feed rate undertakes optimizing handling, can undertake editor of cutting tool contrail is optimized automatically, machine leftover analysis and treat treatment contrail monitoring, in order to ensure cutting tool of high speed treatment gets the smooth stability of power position, improve the service life of cutting tool. After using high speed to machine equipment, to process designing the demand of personnel will increase, because requirement of craft of high speed treatment is strict, it is more important to cut protection too, reason needs to spend much time to undertake emulation examining to NC instruction. Usually, high speed machines process designing time to want to grow more than machining process designing time commonly. Machine the utilization rate with enough equipment to assure high speed, need to deploy more CAM staff. Show some CAM software, waited to offer the strategy of contrail of cutting tool of high speed milling of relevant function like PowerMILL, MasterCAM, UnigraphicsNX, Cimatron. 6, one of main development direction that technology of cutting of last word high speed is cutting processing technique, basically apply at auto industry and mould industry at present, the treatment domain with itself of the domain that machining complex curved surface especially, workpiece or higher demand of tigidity of cutting tool system, be a variety of advanced processing technique is compositive, its efficient, high quality is people place praise highly. It involves high speed to machine craft not only, and still include high speed to machine cutting tool of cutting of system of machine tool, numerical control, high speed and CAD/CAM technology to wait. Processing technique of mould high speed already was at present in the mould manufacturing industry of the developed country general application, and the applied limits that is in our country and applied level still remain to rise, because its have a tradition to machine unparalleled dominant position, will be henceforth processing technique develops way necessarily. CNC Milling CNC Machining