A, processing program carrier
When CNC machine tools are working, it is not necessary for workers to directly operate the machine tools. To control CNC machine tools, machining programs must be compiled. The machining program of parts includes the relative motion trajectory, process parameters and auxiliary motion of the tool and workpiece on the machine tool. Parts processing program is stored in a program carrier with a certain format and code, such as punched paper tape, cassette tape, floppy disk, etc.
Second, the numerical control device
Numerical control device is the core of numerical control machine tool, and generally adopts multiple microprocessors to realize numerical control function in the form of programming software. It interpolates the ideal motion trajectory according to the input data, and then outputs it to the executive part to process the required parts. Therefore, the numerical control device is mainly composed of three basic parts: input, processing and output. All these tasks are reasonably organized by computer system programs, so that the whole system can work harmoniously.
1) input device: input NC instructions to NC devices, and there are different input devices according to different program carriers. There are mainly keyboard input, disk input, direct communication input of CAD/CAM system and DNC (direct numerical control) input connected to the upper computer. At present, many systems still keep the paper tape input form of photoelectric readers.
2) Information processing: the input device compiles the machining information into information that can be recognized by the computer, and the information processing part stores and processes it step by step according to the provisions of the control program, and then sends position and speed instructions to the servo system and the main motion control part through the output unit. The input data of the system include: part contour information, machining speed and other auxiliary machining information. The purpose of data processing is to complete the preparatory work before interpolation operation. The data processing program also includes tool radius compensation, speed calculation and auxiliary function processing.
3) Output device: the output device is connected with the servo mechanism. The output device receives the output pulse of the arithmetic unit according to the instruction of the controller and sends it to the servo control system of each coordinate. After power amplification, the servo system is driven to control the machine tool to move according to the specified requirements.
Thirdly, servo and measurement feedback system.
Servo system is an important part of CNC machine tools, which is used to realize feed servo control and spindle servo control of CNC machine tools. The function of the servo system is to convert the command information received from the numerical control device into linear displacement or angular displacement of the execution part of the machine tool after power amplification and shaping. Servo system is the last link of CNC machine tools, and its performance will directly affect the accuracy and speed of CNC machine tools and other technical indicators. Therefore, the servo drive device of CNC machine tools is required to have good fast response performance, accurately and sensitively track the digital instruction signals sent by CNC machine tools, and faithfully execute the instructions sent by CNC machine tools, so as to improve the dynamic tracking characteristics and static tracking accuracy of the system.
Fourth, the machine tool body
Machine tool host is the main body of CNC machine tools. It comprises a lathe bed, a base, an upright post, a cross beam, a sliding seat, a workbench, a spindle box, a feeding mechanism, a tool rest and an automatic tool changing device. It is a mechanical part that automatically completes all kinds of cutting processing on CNC machine tools. Compared with traditional machine tools, the main body of CNC machine tools has the following structural characteristics:
1) adopts a new machine tool structure with high rigidity, high earthquake resistance and small thermal deformation. Usually, methods such as improving the static stiffness of structural system, increasing damping and adjusting the mass and natural frequency of structural parts are used to improve the stiffness and seismic capacity of machine tool body, so that the machine tool body can meet the needs of continuous automatic cutting of CNC machine tools. The influence of thermal deformation on the main engine can be reduced by improving the structural layout of machine tools, reducing heating, controlling temperature rise and adopting thermal displacement compensation.
2) The wide application of high-performance spindle servo drive and feed servo drive device shortens the transmission chain of CNC machine tools and simplifies the structure of mechanical transmission system of machine tools.
3) Adopt transmission devices and moving parts with high transmission efficiency, high precision and no clearance, such as ball screw nut pair, plastic sliding guide rail, linear rolling guide rail and hydrostatic guide rail.
Five, CNC machine tool lubrication cooling system
The lubrication and cooling system of machine tool consists of oil storage tank, oil pump, magnetic separator, pipeline nozzle and filtering device. When the machine tool is working, the oil pump injects the cutting oil in the oil pool into the processing part through the pipeline nozzle, the separator and the filter device. Cutting oil plays the role of cleaning, cooling and lubrication, reduces the direct friction between the cutter and the workpiece, cools the cutter, and brings the chips into the oil storage tank for recycling.
Six, CNC machine tool auxiliary device
In order to ensure the full play of the functions of CNC machine tools, auxiliary equipment is essential. Commonly used auxiliary devices include: pneumatic and hydraulic devices, chip removal devices, rotary tables and numerical control indexing heads, protection, lighting and other auxiliary devices.
The above is the basic working principle of each part of CNC machine tool equipment. In daily use, operating in accordance with the usage specifications of each equipment and formulating a perfect equipment maintenance process can effectively avoid the failure of the equipment during use and greatly prolong the service life of the equipment.