A cnc machine tool is an automated machine tool equipped with a program control system. The control system can logically process programs with control codes or other symbol instruction rules, and decode them, so that the machine tool can operate the CNC bending machine and process the parts.
The machine tool body of a cnc machine tool is similar to a traditional machine tool. It consists of spindle transmission equipment, feed transmission equipment, bed, work table and auxiliary motion equipment, hydraulic and pneumatic systems, smoothing systems, cooling equipment, etc. However, the overall layout, appearance, transmission system, tool system structure and operation organization of CNC machine tools have undergone great changes. The intention of this change is to satisfy the requirements of CNC machine tools and give full play to the characteristics of CNC machine tools. .
⑵, CNC unit
The CNC unit is the center of the CNC machine tool. The CNC unit is composed of three parts: information input, processing and output. The CNC unit accepts digital information, decodes, interpolates, and logically processes the control software and logic circuit of the CNC equipment, and then outputs various instruction information to the servo system, which drives the fulfillment components for feed motion.
⑶ Input/output equipment
The input device transmits various processing information to the external device of the computer. In the early stage of the occurrence of CNC machine tools, the input device was punched paper tape. It has been screened and then developed into a cassette tape, and then developed into portable hardware such as keyboards and disks. This greatly facilitates information input operations. Now general DNC network communication serial communication Method input.
Output refers to the output of internal operating parameters (including the original parameters of the machine tool under normal and ideal operating conditions, fault diagnosis parameters, etc.). Generally, these parameters need to be output for record and save when the machine tool has just been operating. After a period of operation, the output will be compared with the original Data comparison and comparison can help determine whether the machine tool operation remains normal.
⑷Servo unit The servo unit is composed of a driver and a drive motor, and forms the feed system of the CNC machine tool with the fulfillment parts and mechanical transmission parts on the machine tool. Its function is to convert the pulse signal from the numerical control equipment into the movement of the moving parts of the machine tool. Regarding stepper motors, each pulse signal makes the motor rotate through a point of view, thereby driving the moving parts of the machine tool to move a small interval. Each fulfillment component of the feed movement has a corresponding servo drive system, and the function of the entire machine tool depends primarily on the servo system.
⑸Driving equipment The driving equipment turns the amplified instruction signal into mechanical motion, and drives the machine tool through simple mechanical connection parts, so that the worktable can be accurately positioned or made strict relative motion according to the regular trajectory, and finally processed the parts required by the drawing. Corresponding to the servo unit, the drive equipment includes stepper motors, DC servo motors, and AC servo motors.
Servo unit and drive equipment can be collectively called servo drive system, which is the power equipment for machine tool operation. CNC equipment commands are implemented by the servo drive system. Therefore, the servo drive system is an important part of CNC machine tools.
The Programmable Controller (PC, Programmable Controller) is a general-purpose automatic control device based on a microprocessor, specially designed for application in an industrial environment. Because the original intention of developing this device was to process the logic and switch control of the production device, it was called a Programmable Logic Controller (PLC, Programmable Logic Controller). When the PLC is used to control the sequential actions of a machine tool, it can also be called a Programmable Machine Controller (PMC, Programmable Machine Controller). PLC has become an indispensable control device for CNC machine tools. CNC and PLC cooperate harmoniously to complete the control of CNC machine tools.
⑺ Measuring reaction equipment
Measuring equipment is also called response element, including grating, rotary encoder, laser rangefinder, magnetic grid, etc. Usually installed on the workbench or screw of the machine tool, it converts the actual displacement of the workbench of the machine tool into an electrical signal to respond to the CNC equipment, for the CNC equipment to compare with the command value and generate an error signal to control the machine tool to move in the direction of eliminating the error .
2. Principle of operation
When using a CNC machine tool, the geometric information and process information of the drawing of the processed part must first be written into a processing program with regular codes and formats; then the processing program is input to the CNC equipment, and the information is processed and distributed by the CNC system according to the requirements of the program. , Make each coordinate move several minimum displacements, realize the relative movement of the tool and the workpiece, and complete the processing of the part.
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