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Machine tool numerical control reforms
First, CNC systems and the development trend of history
1946 birth of the world's first electronic computer, which shows that human beings created to enhance and replace some of the mental work tools. It and human agriculture, industrial society in the creation of those who merely increase compared to manual tools, from a qualitative leap for mankind's entry into the information society laid the foundation. Six years later, in 1952, computer technology applied to the machine in the United States was born first CNC machine tools. Since then, the traditional machine produced a qualitative change. Nearly half a century since the CNC system has experienced two phases and six generations of development.
1.1, Numerical Control (NC) phase (1952 to 1970)
Early computer's computational speed low and the prevailing scientific computing and data processing is not affected, but can not meet the requirements of real-time control machine. People have to use digital logic circuit "tied" into a single machine as a dedicated computer numerical control system, known as the hardware connection NC (HARD-WIRED NC), called the Numerical Control (NC). With the development of components of this phase after three generations, that is, in 1952 the first generation - tube; 1959 of the second generation - transistor; 1965 of the third generation - small-scale integrated circuits.
1.2, Computer Numerical Control (CNC) phase (1970 to present)
To 1970, GM has been a small computer and mass-produced. So it transplant system as the core component of NC, have entered a Computer Numerical Control (CNC) stage (in front of the computer should be "universal" word omitted). To 1971, the United States INTEL company in the world will be the first time the two most core computer components - computing and controller, a large-scale integrated circuit technology integration in a chip, called the microprocessor (MICROPROCESSOR) , also known as the central processing unit (CPU).
1974 microprocessor to be used in CNC system. This is because the function of the computer is too small to control a machine tool capacity affluent (the time has been used to control more than one machine, called Group Control), as a reasonable economic use of the microprocessor. Minicomputer reliability and then not ideal. Early microprocessor speed and functionality while still not high enough, but can be adopted to solve the multi-processor architecture. As microprocessor core is a general computer components, it is still known as the CNC.
By 1990, PC machines (personal computers, domestic habits that computer) performance has been developed to a high stage, as a CNC system to meet the requirements of the core components. NC system based on PC has now entered the stage.
In short, CNC has also experienced a stage three generations. That is, in 1970's fourth generation - small computer; 1974 of the fifth generation - microprocessors and the sixth-generation 1990 - Based on the PC (called PC-BASED abroad).
Also pointed out that, although the foreign computer has been renamed NC (CNC), but China still customary said Numerical Control (NC). Therefore, we stress the day-to-day "NC", in essence, is that "computer numerically controlled."
1.3, the trend of future development of NC
1.3.1 continue to open, the sixth generation of PC-based development
Based on the PC with the open, low-cost, high reliability, rich in resources such as hardware and software features, and more CNC system manufacturers will embark on this path. At least it used PC as a front-end machine, to deal with the human-machine interface, programming, networking and communications problems, the former NC Some systems have the mandate. PC machine with the friendly interface, will be universal to all CNC system. Remote communications, remote diagnostics and maintenance will be more widespread.
1.3.2 high-speed and high-precision Development
This is to adapt to high-speed and high-precision machine tools to the needs of the development direction.
1.3.3 intelligent direction to the development
With artificial intelligence in the computer field infiltration and the continuing development of the intelligent numerical control system will be continuously improved.
（1）adaptive control technology
CNC system can detect some important information in the process, and automatically adjust system parameters to improve the system running state purposes.
（2）the introduction of expert guidance processing system
the experience of skilled workers and experts, processing and the general rules of law of special deposit system, the process parameters to the database as the foundation, and establish artificial intelligence expert system.
（3）introduction of Fault Diagnosis Expert System
（4）intelligent digital servo drives
Automatic Identification can load, and automatically adjust parameters to get the best drive system operation.
Second, CNC of the need for transformation
2.1, microscopic view of the necessity of
From the micro perspective, CNC machine tools than traditional machines have the following prominent superiority, and these advantages are from the NC system includes computer power.
2.1.1 can be processed by conventional machining is not the curve, surface and other complex parts
Because computers are superb computing power can be accurately calculated instantaneous each coordinate axis movement exercise should be instantaneous, it can compound into complex curves and surfaces.
2.1.2 automated processing can be achieved, but also flexible automation to increase machine efficiency than traditional 3 to 7 times.
Because computers are memory and storage capacity, can be imported and stored procedures remember down, and then click procedural requirements to implement the order automatically to achieve automation. CNC machine tool as a replacement procedures, we can achieve another work piece machining automation, so that single pieces and small batch production can be automated, it has been called "flexible automation."
2.1.3 high precision machining parts, the size dispersion of small, easy to assemble, no longer needed "repair."
2.1.4 processes can be realized more focused, in part to reduce the frequent removal machine.
2.1.5 have automatic alarm, automatic control, automatic compensation, and other self-regulatory functions, thus achieving long unattended processing.
2.1.6 derived from the benefits of more than five.
Such as: reducing the labor intensity of the workers, save the labor force (one can look after more than one machine), a decrease of tooling, shorten Trial Production of a new product cycle and the production cycle, the market demand for quick response, and so on.
These advantages are our predecessors did not expect, is a very major breakthrough. In addition, CNC machine tools or the FMC (Flexible Manufacturing Cell), FMS (flexible manufacturing system) and CIMS (Computer Integrated Manufacturing System), and other enterprises, the basis of information transformation. NC manufacturing automation technology has become the core technology and basic technology.
2.2, the macro view of the necessity
From a macro perspective, the military industrial developed countries, the machinery industry, in the late 1970s, early 1980s, has begun a large-scale application of CNC machine tools. Its essence is the use of information technology on the traditional industries (including the military, the Machinery Industry) for technological transformation. In addition to the manufacturing process used in CNC machine tools, FMC, FMS, but also included in the product development in the implementation of CAD, CAE, CAM, virtual manufacturing and production management in the implementation of the MIS (Management Information System), CIMS, and so on. And the products that they produce an increase in information technology, including artificial intelligence and other content. As the use of information technology to foreign forces, the depth of Machinery Industry (referred to as information technology), and ultimately makes their products in the international military and civilian products on the market competitiveness of much stronger. And we in the information technology to transform traditional industries than about 20 years behind developed countries. Such as possession of machine tools in China, the proportion of CNC machine tools (CNC rate) in 1995 to only 1.9 percent, while Japan in 1994 reached 20.8 percent, every year a large number of imports of mechanical and electrical products. This also explains the macro CNC transformation of the need.
Third, CNC machine tools and production lines of the transformation of the market
3.1, CNC transformation of the market
My current machine total more than 380 million units, of which only the total number of CNC machine tool 113,400 Taiwan, or that China's CNC rate of less than 3 percent. Over the past 10 years, China's annual output of about 0.6 CNC machine tools to 0.8 million units, an annual output value of about 1.8 billion yuan. CNC machine tools annual rate of 6 per cent. China's machine tool easements over age 10 account for more than 60% below the 10 machines, automatic / semi-automatic machine less than 20 per cent, FMC / FMS, such as a handful more automated production line (the United States and Japan automatic and semi-automatic machine, 60 percent above). This shows that we the majority of manufacturing industries and enterprises of the production, processing equipment is the great majority of traditional machine tools, and more than half of military age is over 10 years old machine. Processing equipment used by the prevalence of poor quality products, less variety, low-grade, high cost, supply a long period, in view of the international and domestic markets, lack of competitiveness, and a direct impact on a company's products, markets, efficiency and impact The survival and development of enterprises. Therefore, we must vigorously raise the rate of CNC machine tools.
3.2, import equipment and production lines of the transformation of NC market
Since China's reform and opening up, many foreign enterprises from the introduction of technology, equipment and production lines for technological transformation. According to incomplete statistics, from 1979 to 1988 10, the introduction of technological transformation projects are 18,446, about 16.58 billion US dollars.
These projects, the majority of projects in China's economic construction play a due role. Some, however, the introduction of projects due to various reasons, not equipment or normal operation of the production line, and even paralyzed, and the effectiveness of enterprises affected by serious enterprise is in trouble. Some of the equipment, production lines introduced from abroad, the digestion and absorption of some bad, spare parts incomplete, improper maintenance, poor operating results; only pay attention to the introduction of some imported the equipment, apparatus, production lines, ignore software, technology, and management, resulting in items integrity, and potential equipment can not play, but some can not even start running, did not play due role, but some production lines to sell the products very well, but not because of equipment failure production standards; because some high energy consumption, low pass rate products incur losses, but some have introduced a longer time, and the need for technological upgrading. Some of the causes of the equipment did not create wealth, but consumption of wealth.
These can not use the equipment, production lines is a burden, but also a number of significant assets in stock, wealth is repaired. As long as identifying the main technical difficulties, and solve key technical problems, we can minimize the investment and make the most of their assets in stock, gain the greatest economic and social benefits. This is a great transformation of the market.
Fourth, NC transformation of the content and gifted missing
4.1, the rise of foreign trade reform
In the United States, Japan and Germany and other developed countries, and their machine transform ation as new economic growth sector, the business scene, is in a golden age. The machine, as well as technology continues to progress, is a machine of the "eternal" issue. China's machine tool industry transformation, but also from old industries to enter the CNC technology mainly to the new industries. In the United States, Japan, Germany, with CNC machine tools and technological transformation of production lines vast market, has formed a CNC machine tools and production lines of the new industry. In the United States, transforming machine tool industry as renewable (Remanufacturing) industry. Renewable industry in the famous companies: Borsches engineering company, atoms machine tool company, Devlieg-Bullavd (Bo) services group, US equipment companies. Companies in the United States-run companies in China. In Japan, the machine tool industry transformation as machine modification (Retrofitting) industry. Conversion industry in the famous companies: Okuma engineering group, Kong 3 Machinery Company, Chiyoda Engineering Company, Nozaki engineering company, Hamada engineering companies, Yamamoto Engineering Company.
4.2, the content of NC
Machine tools and production line NC transformation main contents of the following:
One is the restoration of the original features of the machine tools, production line of the fault diagnosis and recovery; second NC, in the ordinary machine augends significant installations, or additions to NC system, transformed into NC machine tools, CNC machine tools; its Third, renovation, to improve accuracy, efficiency and the degree of automation, mechanical, electrical part of the renovation, re-assembly of mechanical parts processing, restore the original accuracy of their production requirements are not satisfied with the latest CNC system update; Fourth, the technology updates or technical innovation, to enhance performance or grades, or for the use of new technology, new technologies, based on the original technology for large-scale update or technological innovation, and more significantly raise the level, and grades of upgrading.
4.3, NC transformation of the gifted missing
4.3.1 reduce the amount of investment, shorter delivery time
Compared with the purchase of new machine, the general can save 60% to 80% of the costs and transforming low-cost. Especially for large, special machine tools particularly obvious. General transformation of large-scale machine, spent only the cost of the new machine purchase 1 / 3, short delivery time. But some special circumstances, such as high-speed spindle, automatic tray switching systems and the production of the installation costs too costly and often raise the cost of 2 to 3 times compared with the purchase of new machine, only about 50 percent of savings investment.
4.3.2 stable and reliable mechanical properties, structure limited
By the use of bed, column, and other basic items are heavy and solid casting components, rather than kind of welding components of the machine after the high-performance, quality, and can continue to use the new equipment for many years. But by the mechanical structure of the original restrictions, it is not appropriate to the transformation of a breakthrough.
4.3.3 become familiar with the equipment, ease of operation and maintenance
The purchase of new equipment, new equipment do not know whether to meet the processing requirements. Transformation is not, can be used to calculate the machine processing capacity; In addition, since the use of many years, the operator of the machine has long been understood that in the operation, use and maintenance of the training time is short, quick. Transformation of the machine tools installed, we can achieve full load operation.
4.3.4 can take full advantage of the existing conditions
Take full advantage of the existing foundation, not like buying new equipment as necessary to build a foundation.
4.3.5 can be used as control technology
According to the development speed of technological innovation and in a timely manner increased level of automation in production equipment and efficiency, improve the quality of equipment and grades, and the old machine will be replaced by the current level of machine.
Fifth， the choice of NC System
NC system are the three major types of transformation, in accordance with specific circumstances Choose.
5.1, stepper motor drive the open-loop system
The servo drive system is stepper motor, stepper motor power, such as electro-hydraulic pulse motor. NC system by sending commands to the progress of pulse, the drive control and power amplifier circuit, the stepper motor rotate through the gears with ball screw drive of the implementation of parts. As long as control commands the number of pulses, frequency and electricity sequence can control the implementation of parts of the displacement movement, speed and direction of movement. Such a system does not require the test will be the actual position and velocity feedback to the input, so called open-loop system, the system accuracy of the displacement in the major decisions of the stepper motor angular displacement accuracy, transmission gear and other components of the leads crew pitch accuracy, the accuracy of the lower displacement. The system is simple, convenient debugging maintenance, reliable, low cost, easy modification success.
5.2, or asynchronous motor DC Motor Drive, grating feedback loop measurement NC system
And the open-loop system is the difference between a system: from the grating, such as position sensors for simultaneous detection device measured the actual position feedback signals, at any time and to compare the value will be the difference between the two enlarge and change, driven implementing agencies , given the speed of elimination of bias towards the direction of movement, until a given position feedback and the actual location of the margin of zero. Feed the closed-loop system in the structure than to the open-loop system into the complex, high-cost, strict requirements on the environment at room temperature. Design and debugging difficult than open-loop system. However, can be compared to the open-loop system into higher accuracy, faster speed, greater power drive characteristic indicators. Under the technological requirements and decide whether or not to adopt this system.
5.3, AC / DC servo motor drive, the semi-encoder feedback loop NC system
Semi-closed-loop system detection devices installed in the middle of transmission, the implementation of indirect measurement components position. It can only be part of the internal loop compensation system components of the error and, therefore, it compared the accuracy of the closed-loop system of low accuracy, but its structure and debug than simple closed-loop system. Will be in the angular displacement detection devices and speed detection devices and make a servo motor when there was no need to consider the overall position of the installation of detection devices.
NC system for the current production companies more manufacturers, such as the famous German company SIEMENS, Japan FANUC companies; Everest domestic companies such as China, Beijing Aerospace CNC System Corporation, Shenyang and the central high-grade companies NC National Engineering Research Center.
NC selection system is based mainly CNC machine modified to achieve the various precision, motor-driven power and user requirements.
Sixth, the transformation of NC modification of the main mechanical components
A new CNC machine tools in the design to achieve: a high static and dynamic stiffness of movement of the friction coefficient between small, transmission without clearance; big power; easy operation and maintenance. CNC transformation should be