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1、Numerical Control SystemThe numerical control system is the digital control system abbreviation. By early is composed of hardware circuit is called hardware numerical control (Hard NC), after 1970, hardware circuit components gradually instead by the computer called for computer numerical control sy
2、stem. Computerized numerical control system is a system that is use computer control processing function to achieve numerical control system. CNC system according to the computer memory stored in the control program execution part or all, numerical control function, and is equipped with interface ci
3、rcuit and servo drive the special computer system. CNC system consists of NC program, input devices; output devices, computer numerical control equipment (CNC equipment), programmable logic controllers (PLC), the spindle and feed drive (servo) drive (including detection devices) and so on. The core
4、of CNC system is equipment. By using the computer system with the function of software and PLC instead of the traditional machine electric device to make the system logic control more compact, its flexibility and versatility, reliability become more better, easy to implement complex numerical contro
5、l function, use and maintenance can be more convenient, and it also has connected and super ordination machine and the remote communication function. At present, the numerical control system has variety of different forms; composition structure has its own characteristics. These structural features
6、from the basic requirements of the initial system design and engineering design ideas. For example, the control system of point and continuous path control systems have different requirements. For the T system and the M system, there are also very different, the former applies to rotary part process
7、ing, the latter suitable for special-shaped the axially symmetrical parts processing. For different manufacturers, based on historical development factors and vary their complex factors, may also be thinking in the design is different. For example, the United States Dynapath system uses a small plat
8、e for easy replacement and flexible combination of the board; while Japan FANUC system is a large plate structure tends to make the system work in favor of reliability, make the system MTBF rate continues to increase. However, no matter what kind of system, their basic principle and structure are ve
9、ry similar. The numerical control system generally consists of three major components, namely the control system, servo system and position measuring system. Control procedures by interpolation operation work piece, issue control instructions to the servo drive system; servo drive system control ins
10、tructions amplified by the servo motor-driven mechanical movement required; measurement system detects the movement of mechanical position or speed, and feedback to the control system, to modify the control instructions. These three parts combine to form a complete closed-loop control of the CNC sys
11、tem. Control system mainly consists of bus, CPU, power supply, memory, operating panel and display, position control unit, programmable logic controller control unit and data input / output interface and so on. The latest generation of CNC system also includes a communication unit; it can complete t
12、he CNC, PLCs internal data communications and external high-order networks. Servo drive system including servo drives and motors. Position measuring system is mainly used grating, or circular grating incremental displacement encoder. CNC system hardware from the NC device, input / output devices, dr
13、ives and machine logic control devices, electrical components, between the four parts through the I / O interface to interconnect. Numerical control device is the core of CNC system, its software and hardware to control the implementation of various CNC functions. The hardware structure of no device
14、 by CNC installations in the printed circuit board with infixing pattern can be divided into the big board structure and function module (small board) structure; Press CNC apparatus hardware manufacturing mode, can be divided into special structure and personal computer type structure; Press CNC app
15、aratus in the number of microprocessor can be divided into single microprocessor structure and many microprocessor structure. (1)Large panel structure and function templates structure 1) Large panel structure Panel structures CNC system CNC equipment from the main circuit board, position control pan
16、els, PC boards, graphics control panel, additional I / O board and power supply unit and other components. The main circuit board printed circuit board is big; the other circuit board is a small plate, inserted in the large printed circuit board slot. This structure is similar to the structure of mi
17、cro-computer. 2) Function templates structure(2)Single-microprocessor structure and mulct-microprocessor structure 1) Single-microprocessor structureIn a single-microprocessor structure, only a microprocessor to focus on control, time-sharing deals with the various tasks of CNC equipment. 2) melt-mi
18、croprocessor structure With the increase in numerical control system functions, CNC machine tools to improve the processing speed of a single microprocessor CNC system can not meet the requirement; therefore, many CNC systems uses a multi-microprocessor structure. If a numerical control system has t
19、wo or more microprocessors, each microprocessor via the data bus or communication to connect, share system memory and common I / O interfaces, each processor sharing system Part of the work, which is multi-processor systems.CNC software is divided into application software and system software. CNC s
20、ystem software for the realization of various functions of the CNC system, the preparation of special software, also known as control software, stored in the computer EPROM memory. CNC Systems feature a variety of settings and different control schemes, and their system software in the structure and
21、 size vary widely, but generally include input data processing procedures, computing interpolation procedures, speed control procedures, management procedures and diagnostic procedures.(1)Input data processing proceduresIt receives input part program, the standard code, said processing instructions
22、and data decoding, data processing, according to the prescribed format for storage. Some systems also calculated to compensate, or interpolation operation and speed control for pre-computation. Typically, the input data processing program, including input, decoding and data processing three elements
23、.(2)Computing interpolation proceduresCNC work piece processing system according to the data provided, such as curve type, start, end, etc. operations. According to the results of operations were sent to each axis feed pulse. This process is called interpolation operation. Feed drive servo system Im
24、pulsive table or by a corresponding movement of the tool to complete the procedural requirements of the processing tasks.Interpolation for CNC system is the side of the operation, while processing, is a typical real-time control, so the interpolation directly affects the speed of operation the machi
25、ne feed rate, and should therefore be possible to shorten computation time, which is the preparation of interpolation Complements the key to the program.(3)Speed control proceduresSpeed control program according to the given value control the speed of operation of the frequency interpolation, in ord
26、er to maintain a predetermined feed rate. Changes in speed is large, the need for automatic control of acceleration and deceleration to avoid speed drive system caused by mutations in step.(4)Management procedures Management procedures responsible for data input, data processing, interpolation proce
27、ssing services operations as the various procedures for regulation and management. Management process but also on the panel command, the clock signal, the interrupt caused by fault signals for processing.(5)Diagnostic proceduresDiagnostic features are found in the running system failure in a timely
28、manner, and that the type of failure. You can also run before or after the failure, check the system main components (CPU, memory, interfaces, switches, servo systems, etc.) function is normal, and that the site of failure.Machining Any machining must have three basic conditions: machining tools, wo
29、rk piece and machining sports. Machining tool edge should be, the material must be rigid than the work piece. Different forms of tool structure and cutting movements constitute different cutting methods. Blade with a blade-shaped and have a fixed number of methods for cutting tools for turning, dril
30、ling, boring, milling, planning, broaching, and sawing, etc.; edge shape and edge with no fixed number of abrasive or abrasive Cutting methods are grinding, grinding, honing and polishing. Machining is the most important machinery manufacturing processing methods. Although the rough improve manufact
31、uring precision, casting, forging, extrusion, powder metallurgy processing applications on widely, but to adapt to a wide range of machining, and can achieve high accuracy and low surface roughness, in Manufacturing still plays an important role in the process. Cutting metal materials have many clas
32、sifications. Common are the following three kinds. By cutting process feature distinguishing characteristics of the decision process on the structure of cutting tools and cutting tools and work piece relative motion form. According to the technical characteristics of cutting can be divided into: tur
33、ning, milling, drilling, boring, reaming, planning, shaping, slotting, broaching, sawing, grinding, grinding, honing, super finishing, polishing, gear Processing, the worm process, thread processing, ultra-precision machining, bench and scrapers and so on. By material removal rate and machining accu
34、racy distinction can be divided into: rough: with large depth of cut, one or a few times by the knife away from the work cut out most or all allowances, such as rough turning, rough planning, Rough milling, drilling and sawing, etc., rough machining precision high efficiency low, generally used as a
35、 pre-processing, and sometimes also for final processing. Semi-finishing: General roughing and finishing as the middle between the process, but the work piece accuracy and surface roughness on the less demanding position, but also can be used as the final processing. finishing: cutting with a fine w
36、ay to achieve higher machining surface accuracy and surface quality, such as fine cars, fine planning, precision hinges, grinding and so on. General is the final finishing process. Finishing process: after the finish, the aim is to obtain a smaller surface roughness and to slightly improve the accur
37、acy. Finishing processing allowance is small, such as honing, grinding, ultra-precision grinding and super finishing and so on. Modification process: the aim is to reduce the surface roughness, to improve the corrosion, dust properties and improve appearance, but does not require higher precision, s
38、uch as polishing, sanding, etc. ultra-precision machining: aerospace, lasers, electronics, nuclear energy and other cutting-edge technologies that need some special precision parts, high accuracy over IT4, surface roughness less than Ra 0.01 microns. This need to take special measures to ultra-preci
39、sion machining, such as turning mirror, mirror grinding, chemical mechanical polishing of soft abrasive. Distinguished by method of surface machining, the work piece is to rely on the machined surface for cutting tool and the work piece to obtain the relative motion. By surface methods, cutting can
40、be divided into three categories. tip trajectory method: relying on the tip relative to the trajectory of the surface to obtain the required work piece surface geometry, such as cylindrical turning, planning surface, cylindrical grinding, with the forming surface, such as by turning mode. The trajec
41、tory depends on the tool tip provided by the cutting tool and work piece relative motion. forming tool method: short forming method, with the final work piece surface profile that matches the shape forming cutter or grinding wheel, such as processing a shaped surface. At this time forming part of th
42、e machine movement was replaced by the blade geometry, such as the shape of turning, milling and forming grinding forming and so on. The more difficult the manufacture of forming cutter, machine - clamp - work piece - tool formed by the process system can withstand the cutting force is limited, form
43、ing method is generally used for processing short shaped surface. generating method: also known as rotary cutting method, cutting tool and work piece during processing as a relatively developed into a campaign tool (or wheel) and the work piece instantaneous center line of pure rolling interaction b
44、etween the two maintain a certain ratio between Is obtained by processing the surface of the blade in this movement in the envelope. Gear machining hobbling, gear shaping, shaving, honing, and grinding teeth (not including form grinding teeth), etc. are generating method processing.PLC Early called
45、the programmable logic controller PLC (Programmable Logic Controller, PLC), which is mainly used to replace the logic control relays. With the technology, which uses micro-computer technology, industrial control device function has been greatly exceeded the scope of logic control, therefore, such a
46、device today called programmable logic controller, referred to as the PC. However, in order to avoid personal computer (Personal Computer) in the short confusion, it will be referred to as programmable logic controller PLC, plc since 1966, the U.S. Digital Equipment Corporation (DEC) developed there
47、, the current United States, Japan, Germany, PLC Good quality and powerful. The basic structure of Programmable Logic ControllerA. Power PLCs power in the whole system plays a very important role. If you do not have a good, reliable power system is not working, so the PLC manufacturers design and ma
48、nufacture of power very seriously. General AC voltage fluctuations of +10% (+15%) range, you can not take other measures to PLC to connect directly to the AC line.B.Central processing unit (CPU) Central processing unit (CPU) is the central PLC control. It is given by the function of PLC system progr
49、am from the programmer receives and stores the user program and data type; check the power supply, memory, I / O and timer alert status, and to diagnose syntax errors in the user program. When the PLC into run-time, first it scans the scene to receive the status of various input devices and data, respectively, into I / O image area, and then one by one from the user program reads the user program memory, after a shell and press
