The practice that implements USB interface to transform to machine tool of economy numerical control is explored (one)

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  • source:FINKEL CNC Machining
The great data bulk of complex curved surface in be aimed at CNC Machining transmits speed slow, cause the defect that communication competes, the article put forward to go up mediumly in numerical control system a kind of new interface is used between a computer and numerical control machine tool -- the thought that USB interface will come to transform machine tool of economy numerical control, had proof to the improvement of corresponding soft hardware. Article middle finger gave numerical control machine tool to implement the method of USB interface, the USB driver that gave out to fall in Windows system. Because used the transmission of the data after USB interface to be accelerated significantly, increased economy numerical control and the flexibility that PC photograph configures and diversity at the same time, extended network function for machine tool of economy numerical control thereby, in solving network to make because transmit rate slow and the problem that the data communication that bring about competes. One, of the problem put forward the arrival as network times, mechanical production industry also is facing the problem that how gets used to network to make. Mix computer technology, network technology then traditional control technology photograph is united in wedlock, in order to use the heat that the numerical control system that PC gives priority to controller is making mechanical production field increasingly. PC changes numerical control to be able to be divided for 3 kinds of types, we give respectively below the introduction. NC board is inserted model system of this kind of numerical control is to show the core function of numerical control board card is changed, in the patulous chamfer that inserts its PC. PC is in charge of realizing the function such as user interface, file management and communication, NC board is in charge of the athletic control of the machine tool and switch capacity control. CNC of software CNC software is understandable the function that realizes CNC to use the concept of PC and method. The main body of device of this kind of CNC is a PC, made full use of the operating system that the raises ceaselessly computation rate of PC, storage capacity that enlarges ceaselessly and function optimize ceaselessly, the athletic contrail control in realizing a machine tool to control and switch measure logistic control. At present case of this one party still has a lot of problems to still be waited for solve, still stay in the lab to study level. Will PC board embeds this is the numerical control system that uses extensively at present in CNC. The front interface that goes up through CNC and PC are linked together, although this is lighted it is a kind of eclectic plan, but the CNC technology with OK and successive former mature some, what got PC again at the same time is flexible with open sex. The USB interface technique that article place discusses is based on system of this kind of numerical control just about. Equipment of numerical control of this kind of join and on the basic method of position control computer calls DNC skill, it is the basiccest an application technology that makes network make. System of our country's inchoate economic numerical control changes his costume or dress by veneer machine mostly and become, a DNC is received outside needing implementation of interface board ability conducts NC program below basic DNC() function, if pursue,1 is shown. Graph the communication means of the computer of basic communication interface of system of 1 economy numerical control and CNC Machining equipment depends on the communication interface of numerical control system and communication agreement. The communication interface that numerical control system offers and communication agreement have the following kinds: Recording interface, this interface produces the communication interface of system of vintage economy numerical control for Japan. Punched tape reader inputs interface and interface of output of punched tape card punch. Inchoate introduced numerical control system has this interface normally, be like FANUC 7M system. The numerical control system of new development oneself is basic washed out this interface, but still have in our country enterprise, the CNC Machining equipment that decides an amount to contain this port. Asynchronous is serial communication interface, wait like RS232, R5422, R485. This is a kind of communication interface with the most general application, the numerical control system of new development contains this kind of port almost, it uses XON/XOFF, 3964R, simplify 3964 wait for communication agreement. Interface, be like FANUC DNC2 interface, this kind of interface can realize a telecommunication, have make mistake feedback and online real time revise a function, facilitate long-range management, but because its structure is complex, difficulty of communication software development is great, the price is high, accordingly our country is introduced rarely. Network communication interface, basically MAP interface, aether net interface and interface of spot bus line wait, rate of communication of this kind of interface reliability is tall, high, the system of open mode numerical control of new development has options of aether net interface mostly, but network communication interface is deployed rarely in the numerical control system that our country introduces. The net uses MAP2.

1 with MAP3.

O makes automation agreement, it is the industrial network with at present more extensive application, it broadband technology, bus line technology and passive workstation be in harmony is an organic whole, make sure information is transmitted without the fault thereby. But when should asking MAP implementation and treatment synchronism transmit NC order, it is very inaccessible requirement of real time sex, because MAP uses 7 whole agreements,this is, the network accesses charge sex of low, real time differs tall, transmission efficiency, because this is unsuited the couplet net at CNC Machining equipment. By go up the analysis is knowable, asynchronous is serial communication interface RS232 is communication interface of the most commonly used numerical control system, almost all numerical control systems contain this port. Same, graph 1 medium DNC interface board also is adoption RS232 interface. In computer technology change quickly today, RS232 interface is in in computer application domain be replaced by a kind of new USB interface place, arrive from clavier, mouse printer, scanner, numerous the peripheral that is based on USB replaced the device that uses RS232 interface in former days, so in numerical control system, whether can you also use a such new USB interface technology? In DNC communication system, machine some at the same time when equipment of much stage CNC Machining when complex part, because NC program is huge, the memory of numerical control system cannot deposit whole NC program, can adopt DNC to transmit means treatment only, this appears likely CNC Machining equipment machines idle phenomenon because of lacking NC program temporarily, this kind of phenomenon is called " communication competes " . Communication competition often can produce serious consequence in actual production, for example, the midway halt that the car enclothes a punch mould to be versed in inscrupulously can be caused enclothe local " get together smooth " phenomenon, affect quality of punch spare parts directly thereby. The element that poses communication competition is as follows roughly: Participate in the quantitative M of the CNC Machining equipment of couplet net, the amount is more, the possibility that poses communication competition is larger. Spot bus line transmits T of C of rate, transmission efficiency and node switch serve time. Transmission efficiency is to point to the scale that transmits effective byte number to occupy total transmission byte. The Vi of communication transmission rate of equipment of each CNC Machining and transmission efficiency Ei(i=1 ～ M) . Vi is 9600b/s normally, but complex model face antrum finish machining asks to admit achieve 19200b/s above. Program of numerical control system uses up rate Pi, namely every second implements numerical control system of the program (Bit) number. Pi wave motion is bigger, but every system has a value of more certain the biggest Pi; The size Qi of BUFFER of buffer of data of communication of numerical control system. The size Si of BUFFER of buffer of odd metadata of front of each DNC communication. Si is the quantity that need optimizes, through building mathematical model, can get: 1.

2.

By type (1) is knowable, the upper limit of S of buffer of odd metadata of DNC communication front and Q, V, C, P is relevant: Q, V, C is bigger, p is smaller, criterion S upper limit is bigger. The floor level of S returns related to M, T: M, T is smaller, criterion the floor level of S is smaller. Type (equipment of identical CNC Machining of join of system of communication of DNC of 2) watch palpability and the largest amount that does not produce communication competition: V, C is bigger, p, T is smaller, criterion M is bigger. If DNC corresponds,the platform of CNC Machining equipment of systematic couplet net counts dissatisfaction sufficient type (2) , should be unified calm meeting occurrence communication competes, can pass only at this moment reduce all or the method such as the feed speed of equipment of partial CNC Machining with reducing machine program use up rate P, perhaps use higher transmission rate, raise V namely, the communication competition issue in collecting appliance to the USB bus line that transmits rate higher and interface can solve DNC communication system so. 2, photograph of interface of technical analysis USB depends on to the advantage of RS232 interface: USB bus line offerred 3 kinds of different data to transmit rate: 1.

The low speed data of 5Mb/s is transmitted, of 12Mb/s amain data is transmitted, the high speed data of 480Mb/s is transmitted (USB2.

0 support) , and the rate of RS232 is top have 20kb/s only, USB is machining the curved surface with curvature very big change when, high speed number has clear advantage according to transmitting. USB is theoretic supportable amount to 127 peripheral, join to the dot relative to the dot at RS232, the system that uses USB interface realizes a PC to control much stage NC likely, can improve efficiency greatly thereby, reduce cost, facilitating control, more be helpful for coming true to be made in coordination. The significant link distance of USB is 5m, can pass collect line implement patulous join, can expand at most 5 class, achieve the distance of 30m, and the largest when data is transmitted space is RS232 only 15m. Icron company developed Exterme USB technology, can expand USB equipment the distance is in for 500 ～ 2000m more. Another of USB marked characteristic is to support heat to unplug insert, this kind of character special apply to manufacturing distribution to adjust frequent environment. Just think, should need NC of increase and decrease or when NC occurrence breakdown needs shutdown maintenance, can accept facility the system directly, can make manufacturing settling time is reduced greatly certainly. USB still is had use low price, easily, transmission data has better fault tolerance sex to wait for a characteristic. Graph the 2 network develop after using USB interface attack the structure is analysed from above not ugly piece, numerical control system uses USB interface have a lot of advantage, opposite at RS232 interface it is a kind of technologies rise. We put forward a kind further convenient medium or small the mode that machines production network, if pursue,2 are shown. CNC Milling