Computer numerical control system is a system that uses computer to control machining function and realize numerical control. According to the control program stored in computer memory, CNC system performs some or all numerical control functions, and is equipped with a special computer system with interface circuit and servo drive device.
The numerical control system consists of numerical control program, input device, output device, computer numerical control device (CNC device), programmable logic controller (PLC), spindle drive device and feed (servo) drive device (including detection device).
The core of numerical control system is numerical control device. Because of the use of computer, the system has software function. Using PLC instead of the traditional logic control device of machine tool electrical appliances makes the system smaller, more flexible, universal and reliable, easy to realize complex numerical control functions, convenient to use and maintain, and has the functions of connecting with upper computer and remote communication.
Fourteen development trends of machine tool technology
1, high-speed machine tool
With the wide application of light alloy materials in automobile, aerospace and other industries, high-speed machining has become an important development trend of manufacturing technology. High-speed machining has the advantages of shortening machining time, improving machining accuracy and surface quality, and is more and more widely used in mold manufacturing and other fields. High-speed machine tools need new numerical control system, high-speed motorized spindle and high-speed servo feed drive, as well as optimization and lightweight of machine tool structure. High-speed machining is not only the equipment itself, but also the synthesis of machine tools, tools, tool handles, fixtures, numerical control programming technology and personnel quality. The ultimate goal of high speed is high efficiency, and machine tools are only one of the keys to achieve high efficiency, not all, and production efficiency and benefits are on the "knife edge".
2. Machine tool accuracy
Machine tools can be divided into ordinary machine tools, precision machine tools and ultra-precision machine tools according to the machining accuracy, and the machining accuracy doubles about every 8 years. The positioning accuracy of CNC machine tools is about to bid farewell to micron era and enter sub-micron era, and ultra-precision CNC machine tools are moving towards nanometer. In the coming 10 year, precision and high speed, intelligence and miniaturization will converge to form a new generation of machine tools. The accuracy of machine tools is not only the urgent demand of automobile, electronics, medical equipment and other industries, but also directly related to the modernization of national defense industries such as aerospace, missile satellites and new weapons.
3. From process combination to complete processing
In the 1970s, the machining center took the lead in integrating multiple processes, and now it has developed to full processing, that is, all the processing processes of complex parts are completed on one machine tool. The complete machining is integrated according to the process, and the machining process of a part can be completed at one time. Due to the reduction of card loading times, the machining accuracy is improved, the high reliability of the process is easily guaranteed, and zero-defect production is realized. In addition, complete machining shortens the processing process chain and auxiliary time, reduces the number of machine tools, simplifies the material flow, improves the flexibility of production equipment, and has a small total production area and more efficient investment.
4. Machine tool informatization
The typical case of machine tool informatization is Mazak4 10H, which is equipped with an information tower and realizes the independent management of the workplace. The information tower has communication functions such as voice, text and video. Networking with production planning and scheduling system, downloading work instructions and processing programs. When the workpiece is cut, the machining process can be observed on the screen. The information tower can reflect the working status and processing progress of machine tools in real time, and can be queried by mobile phone. At the same time, the information tower carries out statistical analysis of working data and tool life management, as well as fault alarm display and online help elimination. The operating authority of the machine tool needs to be confirmed by fingerprints.
5, intelligent machine tools-measurement, monitoring and compensation
The intelligentization of machine tools includes on-line measurement, monitoring and compensation. The position detection and closed-loop control of CNC machine tools is a simple application case. In order to further improve the machining accuracy, the circular motion accuracy of the machine tool and the spatial position of the tool point can be measured by using a club instrument and a laser, and then input into a numerical control system for compensation. In the future, CNC machine tools will be equipped with various micro sensors to monitor the errors caused by cutting force, vibration and thermal deformation, automatically compensate or adjust the working state of the machine tools, and improve the working accuracy and stability of the machine tools.
6. Miniaturization of machine tools
With the rapid development of nanotechnology and MEMS, the development of machine tools for machining micro parts has been put on the agenda. Micro machine tools have the characteristics of high speed and precision at the same time. The smallest micro machine tool can be put in the palm of your hand, and the micro factory can be put in the suitcase. The operator controls the operation of the whole factory through the handle and monitoring screen.
7. New principle of parallel mechanism
In traditional machine tools, the movement of X, Y and Z along three coordinate axes and the rotation of A, B and C around three coordinate axes are sequentially superimposed in series according to Cartesian coordinates to form the required tool path. Parallel motion machine tools use various types of rod mechanisms to transfer spindle components in space and form the required tool path. Parallel motion machine tools have a series of advantages, such as simple and compact structure, high stiffness and good dynamic performance, and have broad application prospects.
8. New technological process
In addition to metal cutting and forging, new processing methods and technologies emerge one after another, and the concept of machine tools is also changing. The field of laser processing is expanding day by day. Besides laser cutting and laser welding, laser hole machining, laser three-dimensional machining, laser heat treatment and laser direct metal manufacturing are more and more widely used. Electrical machining, ultrasonic machining, laminated milling, rapid prototyping technology and three-dimensional printing technology all show their magical powers.
9, new structure and new materials
The high speed and precision of machine tools require simplification and lightweight of machine tools, so as to reduce the negative influence of inertia of machine tool parts on machining accuracy and greatly improve the dynamic performance of machine tools. For example, the topology optimization of machine tool parts, the design of box-in-box structure and the use of hollow welded structure or lead alloy materials have begun to move from laboratory to practical use.
10, a new design method and means
The means of machine tool design and development in China should be changed from 2D CAD to 3D CAD as soon as possible. Three-dimensional modeling and simulation is the foundation of modern design and the source of enterprise's technological advantages. On the basis of this three-dimensional design, the integration of CAD/CAM/CAE/PDM can accelerate the development of new products, ensure the smooth production of new products, and gradually realize product life cycle management.
1 1, direct drive technology
In traditional machine tools, the motor and machine parts are connected by coupling elements, such as belts, gears and couplings, to realize the required movement or rotation of the parts, and the motor and electricity are separated. Direct drive technology integrates motor and mechanical parts into a whole and becomes a functional part of electromechanical integration, such as linear motor, motorized spindle, electric ball screw and torque motor. The direct drive technology simplifies the structure of the machine tool, and improves the rigidity and dynamic performance, movement speed and machining accuracy of the machine tool.
12, open CNC system
The opening of CNC system is the general trend. At present, there are three forms of open CNC system: 1) fully open system, that is, CNC system based on microcomputer. On the platform of microcomputer, the system is operated in real time, and various functions of the numerical control system are developed. The data is transmitted through the servo card to control the motion of the coordinate axis motor. 2) Embedded system, that is, CNC+PC, CNC controls the motion of coordinate axis motor, and PC serves as man-machine interface and network communication. 3) Fusion system, adding PC mainboard on the basis of CNC, providing keyboard operation and improving human-computer interface functions, such as Siemens840Di and Fanuc2 10i.
13, reconfigurable manufacturing system
With the acceleration of product upgrading, the reconfiguration of special machine tools and manufacturing systems is becoming more and more important. Through the modularization of NC machining unit and functional parts, the manufacturing system can be quickly reorganized and configured to meet the production needs of variant products. The standardization and standardization of mechanical, electrical and electronic, hydraulic and pneumatic, and control software interfaces is the key to realize reconfiguration.
14, Virtual Machine Tool and Virtual Manufacturing
In order to speed up the development speed and quality of new machine tools, with the help of virtual reality technology, the correctness and performance of machine tool design can be evaluated before machine tool manufacturing, and various errors in the design process can be found at an early stage, so as to reduce losses and improve the quality of new machine tool development.
Key development scope
1, high-speed, precision CNC lathes, turning centers and compound machining machines with more than four axes linkage. It mainly meets the needs of aerospace, aviation, instruments, meters, electronic information and bioengineering industries.
2. High-speed and high-precision CNC milling and boring machine and high-speed and high-precision vertical horizontal machining center. It mainly meets the processing requirements of automobile engine cylinder heads and large-scale complex structural supports, shells, boxes, light metal parts and precision parts in aerospace, high-tech and other industries.
3. Heavy and ultra-heavy CNC machine tools: CNC floor milling and boring machines, heavy CNC gantry boring and milling machines and gantry machining centers, heavy CNC horizontal lathes and vertical lathes, and heavy CNC hobbing machines. These products meet the requirements of parts processing in energy, aerospace, military industry, ship main engine manufacturing, heavy machinery manufacturing, large-scale mold processing, steam turbine cylinder block and other industries.
4. CNC grinders: CNC ultra-precision grinders, high-speed and high-precision crankshaft grinders, camshaft grinders, and various high-precision and high-speed special grinders that meet the needs of precision and ultra-precision machining.
5. CNC EDM machine tools: large-scale precision CNC EDM forming machine tools, CNC low-speed EDM cutting machine tools, precision small-hole EDM machine tools, etc. , mainly to meet the special needs of large and precision mold processing, precision parts processing, tapered hole or special-shaped hole processing, aerospace, aviation and other industries.
6. CNC metal forming machine tools (forging equipment): CNC high-speed precision sheet metal stamping equipment, laser cutting compound machine, CNC powerful spinning machine, etc. It mainly meets the needs of mass and efficient production of sheet metal in automobile, motorcycle, electronic information industry, household appliances and other industries, as well as the processing needs of various thin-walled, high-strength and high-precision rotary parts in automobile wheels, military industry and other industries.
7. Special CNC machine tools and production lines: FMS/FMC and various special CNC machine tools meet the processing requirements of cylinder blocks, cylinder heads, gearbox boxes and other parts in automobile, household appliances and other industries.