Configuration of system of machine tool numerical control and function select a system

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  • source:TANAY CNC Machining
The configuration of numerical control system and functional selection system are the main component of numerical control machine tool, the numerical control system that deploys what type and choice function of what numerical control, it is the problem of manufacturer of machine tool production and attention of final user place. Open loop controls a system: Use a pace to regard drive as the component into electric machinery, without the position and speed feedback parts of an apparatus, control is so simple, the price is low, but their laden capacity is small, positional control precision is poorer, feed speed is inferior, basically use at device of economy numerical control; Half closed circuit and closed circuit position control a system: Use dc or communication servo electric machinery to regard drive as the component, can use inside the pulse coder inside machine of outfit Wu Dian, rotate transformer serves as the position / speed detects parts of an apparatus will form position of half closed circuit to control a system, also can use direct installation to regard the position as detector in the grating of working Ning or inductive synchronized, the position of complete closed circuit that will form high accuracy controls a system. As a result of the existence of pitch error, make the guide screw that feedbacks from detector of position of system of half closed circuit rotates angle change quantity, return the sharp movement position that cannot reflect feed axis accurately. But, be opposite through numerical control system the compensation after of pitch error, they also can achieve quite high position to control precision. Compare with photograph of system of complete closed circuit, their value is inferior, the sealing that installs the positional feedback parts of an apparatus in electric machinery interior is good, the job is more stable and reliable, need not maintain almost, apply at the numerical control machine tool of all sorts of types widely so. The control of dc servo electric machinery is simpler, the value is inferior also, its are main defect is electric machinery interior has mechanical inverting unit, carbon brush wears away easily, maintenance workload is big. Easy a kind of firecrackerfire breaking out is beautiful when moving, make of the rotate speed of electric machinery and power it is relatively difficult to rise. Communicating servo electric machinery is to not have brush a structure, need to maintain scarcely, volume is relatively minor, be helpful for rotate speed and power rise, already surrounded in very big Geng at present inside replaced dc servo electric machinery. Servo controls unit phyletic depart servo to control unit, its characteristic is numerical control system and servo control unit opposite independence, that is to say, they can deserve to use with a variety of numerical control systems, the instruction that NC system gives out is the DC voltage related to axial motion speed (for example 0-10V) , and is what return from the machine tool the axial movement position that matchs with NC system detects signal (for example coder? The output signal such as inductive synchronized) . The set of servo data and adjust control unit side to undertake in servo (use potentiometer adjustment or input through digital means) . Serial data is transmitted model servo control is unit, its characteristic is the data between NC system and servo control unit conveying is two-way. The instruction data related to axial motion, servo data and alarm signal are to pass corresponding clock line, anthology communication name number, deliver data line, receive data line of line, alarm signal is deferent. Return the information such as the has athletic rod actual place of NC device and condition from positional coder. Network data is transmitted model servo control is unit, its characteristic is axle control unit is installed together thick and fast, by a power supply of public unit of DC power source. The join dot SR that NC device passes the module of network data processing on FCP board, ST is as unit as each axle control (child station) the SR of module of network data processing, ST orders series, form servo operating ring. The position of each axes is to pass join of line of communication of 2 high speed between coder and axle control unit, the information of feedback has buy of athletic position of axle and relevant condition news. Serial data is transmitted model transmit with network data model the servo parameter with servo unit control is in NC device with digital set, switch on the mobile phone initialization fashionable dress controls unit into servo, revise and adjust very convenient. Network data is transmitted model servo control is unit (river bend greatly for example OSP-U10/U100 system) in corresponding control software cooperates to fall, have real time adjust ability, add decelerate function in Hi-G fixed position for example in, can beg a corresponding function according to the speed of electric machinery and torque character, when controlling high speed to locate with its function again add decelerate to spend, restrain the causes possibly vibration when high speed locates thereby. Of fixed position speed rise can shorten blame cutting time, improve treatment efficiency. If be in function of control of Hi-Cut feed speed, the system can be in read in after of spare parts machine program, the spare parts figure that identifies numerical control automatically to dictate the requirement is machined (edge of circular arc, arris) , self-adjusting treatment speed, made maximize, realize treatment of high speed high accuracy then. Use high speed microprocessor and processor of special number signal (DSP) occurrence after of servo of complete digitlization communication, hardware servo control turns into software servo control, the advanced algorithm with a few contemporary academic control gets coming true, improved the control performance of servo greatly then. Servo control unit is the component of correlation of as direct as machinery look in numerical control system, the cutting speed of their function and machine tool and positional precision concern are very big, what its price also takes numerical control system is very major. Opposite for, the fault rate of servo component is higher also, occupy the 70% above of electric breakdown about, choose so it is very important to match servo to control unit. Servo breakdown is concerned besides the dependability that controls unit with servo outside, still mix with the use environment of the machine tool, mechanical state closely related cutting condition. For example environmental temperature is exorbitant, easy cause overheat of parts of an apparatus and damage; Defend lax likelihood causes electric machinery to drink water, cause short circuit; Slideway and guide screw are lubricant bad or cutting bear is overweight can cause electric machinery to flow too. Card of mechanical main transfer machinery can cause the damage of power parts of an apparatus more to death, although servo controls unit itself to certain overload protects ability, but when breakdown condition perhaps happens badly for many times, still can make parts of an apparatus damages. The real time load that system of some numerical control has main shaft and feed axis displays a function (river bend greatly for example of OSP system " current position " the data of real time position that can show the axis moves not only on the page, and the percentage of real time load that still shows each axis at the same time, the user can use these information, adopt measure to prevent the happening of the accident. The choice output torque of feed servo electric machinery is the index of ability of load of feed electric machinery. From the graph 2 visible, in successive operation condition falls, outputting torque is those who follow rotate speed is elevatory and reductive, the performance of electric machinery has healed, this kind reduces a value to heal small. The output torque when satisfying highest cutting speed to when feed axis configures electric machinery, answer. Although do not make cutting when fast feed, laden and lesser, but the starting torque that also should consider speed of highest and fast feed to fall. The control that the output torque when high speed has dropped to also can affect feed axis more is characteristic. The choice output power of electric machinery of main shaft servo is the index of ability of load of main shaft electric machinery. From the graph the rated power of electric machinery of 3 visible main shaft is to point to in constant power division (speed N1 arrives N2) inside the output power when moving, under rated power of the short of when basic rate N1, speed heals low, output power heals small. To satisfy the power requirement when main shaft low speed, adopt gear case speed change commonly, make the electric machinery speed when main shaft low speed also is in above of basic rate N1, right now, rigid structure is relatively complex, cost also can raise accordingly. In the numerical control machine tool that receives one after another continuously in main shaft and servo electric machinery, have the power demand when two kinds of methods will satisfy main shaft low speed, it is to choose basic rate firstly inferior or the main shaft electric machinery of rated power high first gear, it is the electric machinery of servo of main shaft of winding switch type that uses special type secondly (for example electric machinery of the YMF that Japan rivers bend greatly main shaft) , the three-phase winding of this kind of electric machinery receives astral form when low speed moves, and receive when high speed moves triangularly, the low speed power that enhanced main shaft electric machinery thereby is characteristic, reduce the cost of component of main shaft machinery. Want here special those who point out is, although high speed treatment is the efficient way that raises numerical control machine tool to manufacture efficiency, but cutting of high speed, high accuracy can give servo drive and computer component to bring higher demand, raise the cost of numerical control system necessarily, and the treatment that domain of another when high speed machines fundamental application is light metal and thin wall spare parts, so, the real need that should press a machine tool chooses the career of main shaft and feed electric machinery. The position detects the choice machinery origin of parts of an apparatus is the datum mark that all coordinate are numerical control machine tool, the stability of mechanical origin is the technical index with numerical control very main machine tool, assure basically also be stable treatment precision, of mechanical origin build a method to have two kinds: In the numerical control machine tool that using synchronized of relative position coder, induction or grating to regard the position as feedback parts of an apparatus, numerical control system a 0 decelerate switch each feed axis (or mark) mark signal served as datum mark the first when after arises by positional feedback parts of an apparatus at 0 o'clock. This kind of machine tool is in cut off the power every time or urgent a 0 operations that cease machine after to must make each feed rod afresh, otherwise, real position may produce deflection, time 0 decelerate switch bumps with its piece relative position adjusts misgivings, what also can cause mechanical origin position is not stable, these should take seriously; In using the numerical control machine tool that regards the position as feedback parts of an apparatus to positional coder absolutely, absolutely position coder can remember each bits of position inside total travel of each feed axis automatically, do not need to answer 0 switch, cut off the power every time or urgent stop machine after, the set that need not make datum mark afresh is operated. After of set of datum mark position is permanent and changeless, remember by the memory that uses for absolutely position coder only, special apply to rat tooth dish the whirl of fixed position works Ning at 0 o'clock positional set, not only stability is good, and mix to the operation adjust bring great and convenient. The choice machine tool of mechanical design plan is mix by machinery electric two parts composition, answer when devising overall plan from Electromechanical two respects consider a machine tool the executive plan of all sorts of functions, the function of the inflexible demand of numerical control machine tool and numerical control system is very complex, so more should Electromechanical is communicated, foster strengths and circumvent weaknesses. Below illustrate. Exemple the adjustment of rotate speed of one main shaft has use servo electric machinery or implementation of frequency conversion electric machinery is automatic stepless speed regulation and classification with drive of electric machinery of common three-phase asynchronous, mechanical gear gearshift, have manual shift two kinds of methods. Machining center machine tool uses a variety of cutting tool to have successive different sort (mill, auger, boring and tap) cutting treatment, so the rotate speed of main shaft often changes, and must come true automatically by the S instruction of machine program, main shaft still must undertake when changing a knife automatically directional, must use the means of automatic stepless speed regulation that contains directional function so. For not tall to requirement of main shaft rotate speed common CNC Milling, of cutting tool changing is to use a hand to move means to undertake, and in machining a process, same do not see the opportunity that cutting tool chooses different rotate speed more, move in the hand change a knife while the effect that undertakes the hand moves gearshift opposite to produce efficiency is not big, often use mechanical gear to classification so the control means of gearshift, manual shift. Compare with the plan posture that adopts servo electric machinery to have stepless speed regulation, can show touchdown to reduce manufacturing cost, save the sources of energy, maintenance is simple also, it is very practical choice. Exemple when machining center of 2 use horizontal undertakes to the spare parts much face is machined, often need to change clamping apparatus holds card for many times, must take up valuable machine tool run time, choose have duplex operation automatic splint is exchanged (APC) the horizontal machining center of device, can save what spare parts outfit gets stuck greatly to take machine time, improve the manufacturing efficiency of the machine tool thereby, and the control of this function is by PLC control program is finished, besides multi-purpose a few inputs / outside outputting reference point, the cost of numerical control system raises not much, it is a function / the choice with price very tall comparing. Exemple the time changing a knife of machine tool of 3 machining center has very big effect to manufacturing efficiency, and the speed that change a knife and rigid structure have very big concern. For example, by manipulator of oil cylinder pilot the time that change a knife is in commonly 10 seconds above, the manipulator that completes the action that change a knife in 2~3 second internal energy introduces drive of servo electric machinery commonly, deserve to have cam and orgnaization of loose knife of oil cylinder of inside and outside. The speed changing a knife that does not comparative with the orgnaization, the likelihood makes fault rate increases. The maximize that chooses condition of the logical cutting way, cutting tool that uses high quality, cutting also is the important step that improves manufacturing efficiency, answer to consider integratedly. The choice of numerical control function divides basic function beyond, numerical control system still provides a variety of optional functions for the user, the basic function difference of each numerical control system of well-known trademark is not big, so, choose to suit the optional function of the machine tool reasonably, abandon dispensable or unpractical is optional function, the function that tastes to raising high yield / price comparing has profit greatly, a few example are listed to offer reference below. Animation / this function uses orbit indication function at imitate spare parts to machine a process, the cutting way that shows true cutting tool to go up in semifinished product, two in can choosing orthogonal coordinate to fasten different plane while show, what also can choose different perspective is three-dimensional and stereo show. Can machining while make real time show, what also can lock up decided means dirty to machine a process in machinery is fast depict. This is one kind examines the spare parts machine program, effective tool that raises process designing efficiency and real time surveillance. It is OK that floppy disk driver occupies deferent tool through this kind of number systematic machine program will been debugged stock floppy disk after to file in the system, the machine program that also can adopt it to will be generated in other computer stocks NC system, the input that reduces machine program thereby takes machine time, can make the backup of all sorts of machine tool data or memory with it more, be made up to Cheng and operate personnel to bring very easy. DNC-B communication function is well-known, the work out of the spare parts machine program that forms by the curve that be not a circle or curved surface is very difficult, normally method is have the aid of at the general purpose computer, them fractionize is after of tiny three-dimensional straight line segment to write machine program again, program capacity is so great. In mould treatment, this kind is as long as byte of hundreds of K (4K byte approximates length of 10 meters of punched tape) machine program often is encountered, and the basic course memory capacity that system of ordinary numerical control provides is 64? 128K byte, this brings very great difficulty to mould treatment. DNC-B communication function has kind of two kinds of jobs, it is firstly undertake between the machine program memery block of PC and numerical control system two-way program conveys, it is the machine program the PC secondly a paragraph a paragraph of ground conveys to run memory to the amortize of numerical control system, the edge conveys by the side of treatment, end till treatment. This machines a problem with respect to what solved part of high capacity order thoroughly. Although choose this function to need to raise fixed cost, but it is a function really / the option with price very tall comparing. Of course, choosing augment memory capacity also is the effective method that solves treatment of curved surface mould, river bend greatly for example the capacity of the biggest moving buffer storage of OSP system is 512K byte. Program memory capacity is OK augment arrives 4096K byte, can satisfy the need that great part pattern machines so, with use DNC-B means photograph to compare, its advantage is leave out PC this link, make move more reliable, the operation is more convenient also. Simplify the function of process designing the efficiency to raise process designing, shorten the length of machine program, develop the latent capacity of program memory, numerical control system was offerred a few simplify the method of to program. The treatment working procedure with fixed will commonly used loop (for example bore, bore hole, tap and housing and circumjacent treatment) the fixed loop program that writes parameter type, relevant data is filled by the user when process designing (like tool reference plane, hole depth, every time approach and main shaft rotate speed and feed speed) achievable booked treatment working procedure, can repeat for many times use. Coordinate computation function uses the capacity of real time computation of numerical control system, machine the aperture that distributings with all sorts of regulation working procedure (for example diagonal, circumferential wait with reseau) the fixed loop program that writes parameter type, relevant data is filled by the user when process designing (if angle, radius, Kong Shu, linage and row are counted,wait) achievable booked treatment working procedure. Subprogram function user is OK the same treatment process that uses the many part in the spare parts makes up a subprogram, call in corresponding place, shorten thereby the length of machine program. Grand program user can use the user all sorts of arithmetic that the system offers, logic and function operation accord with and all sorts of branch statements, will comprise a description to machine the mathematical expression of spare parts appearance, in order executive process, operation of margin of numerical control system, the edge outputs a result, use very short course to be able to realize the treatment of special type curve and curved surface. Function of tap of tigidity of rigid tap function must use servo electric machinery to come drive main shaft, ask to increase positional sensor on main shaft not only, and have firm demand to the clearance of main shaft main transfer machinery and inertia, so cannot oversight the cost of this function. To the user, if do not have special requirement (for example material of high speed high accuracy, special type or labour of big diameter Kong Jia) , can use head of stretch and adjustable card, undertake on general main shaft flexible tap will satisfy treatment to ask, need not choose rigid tap function. Cutting tool life manages a function to whether want to choose cutting tool life to govern a function on machining center, the element such as the capacity of the consistency of the batch that must consider to machine a spare parts, cutting tool and semifinished product quality and knife library, otherwise, can cause a lot of factitious errors not only, affect manufacturing on the rails, and reserve the knife that cutting tool takes up the effective size that also will reduce knife library greatly, make a few complex parts because knife be not worth and cannot machine. Radius of automatic cutting tool / length and workpiece measure the contrail of cutting tool motion in functional machine program to press cutting tool center and point of a knife to write normally, must input corresponding cutting tool radius and length before the program is carried out so, this pair of machining center especially important. Cutting tool radius and length can be measured with common measure handiwork, usable also and special cutting tool measuring instrument is measured. The point of a knife that handlers can carry every sword go up at the machine tool relatively in Z axis direction same " to knife face " positional difference will undertake compensating as length deflection value, those who use itself of numerical control system to offer " length of semi-automatic cutting tool is measured " function, the input is opposite at " standard cutting tool " length compensates a value. Radius of automatic cutting tool / length and workpiece measure a function, need deploys appropriative contact sensor and laser to measure head and signal receiver. The following should make clear when choosing this function: Contact sensor and signal receiver installation are inside area of machine tool work, its it is very important to defend, cutting amount is large, use gush drenchs rinsed machine tool shoulds not be installation; Undertake afore-mentioned measurement need to take up machine tool handling time, the likelihood affects the efficiency of the machine tool; The general use that workpiece measures a function is the position of the fiducial aperture center that measures work semifinished product to go up to make up origin as Cheng or other datum mark, replace artificial " to the knife " , its precision won't the fixed position precision of itself of prep above machine tool. CNC Milling CNC Machining