Introduction to the components of the hottest CNC

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Introduction to the components of CNC machine tools

CNC machine tools are generally composed of control media, CNC devices, servo systems and machine tool bodies

in order to improve the machining accuracy of the machine tool, a measuring device (i.e. the dotted line in the above figure) is added to the above system, which constitutes the block diagram of the NC machine tool with closed-loop control. The working process of the open-loop control system is as follows: the displacement, displacement speed, displacement direction, displacement trajectory and other parameters that control the movement of the machine tool workbench are input to the machine tool numerical control device through the control medium. The numerical control device calculates the feed pulse sequence (including the above four parameters) according to these parameter instructions, and then it is converted and amplified by the servo system, and finally controls the workbench according to the required speed, trajectory Direction and distance movement. If it is a closed-loop system, while inputting the command value, the feedback detects the error displacement value between the real person of the machine tool workbench. The feedback quantity and the input quantity are compared in the numerical control device. If there is a difference, it indicates two differences, and the numerical control device controls the machine tool to operate in the direction of eliminating the error

now the components are briefly described as follows:

1. Control medium

when repairing equipment for CNC machine tools, workers do not need to shake the handle to operate the machine tools, but they also need to automatically implement people's intentions. Therefore, a certain connection must be established between the six new material industry fields defined by the people's Republic of China and CNC machine tools, This kind of media is called control media (or program media, input media, information carrier) because of the 34% reduction of imported waste paper in 2018

the commonly used control medium is 8 units of standard perforated tape, and the commonly used perforated tape is paper, so it is also called paper tape. Its width is 25.4mm and thickness is 0.108mm. There must be one in each row φ There can be at most 8 synchronization holes outside the 1.17mm synchronization hole φ 1.33mm information hole. Different codes are represented by the arrangement and combination of 8 holes in each line (the arrangement regulations of holes on paper tape are called codes). Input the perforated belt to the tape reader of the numerical control device, and then the code on the perforated belt is converted into the electrical signal that can be recognized and processed by the numerical control device by the tape reader, and transmitted to the numerical control device, so as to complete the input of instruction information

2. Numerical control device

domestic blow molding machines are transformed into high-end lines. Control is the center of numerical control machine tools. In ordinary numerical control machine tools, it is generally composed of input devices, memory, controllers, arithmetic operators and output devices. The numerical control device receives the information of the input medium, identifies, stores and calculates its code, and outputs the corresponding command pulse to drive the servo system, so as to control the action of the machine tool. In computer numerical control machine tools, because the computer itself contains the above units such as arithmetic unit and controller, the function of its numerical control device is completed by a computer

3. Servo system

the function of the servo system is to convert the pulse signal from the numerical control device into the movement of the moving parts of the machine tool, so that the workbench (or slide) can be accurately positioned or move strictly according to the specified trajectory, and finally process the parts that meet the requirements of the drawing

in the servo system of CNC machine tools, the commonly used servo driving components are power stepping motor, electro-hydraulic pulse motor, DC servo motor and AC servo motor

4. Machine tool

in the numerical control machine tool, the general machine tool is used in the initial stage, but some changes are made in the aspects of automatic speed change, automatic positioning of tool rest or worktable, handle, etc. Practice has proved that the NC machine tool can not be interfered by human at any time as in the general machine tool because of its automatic control, except that the workpiece accuracy is affected by the large cutting amount and the continuous machining heat. Therefore, its design requirements are stricter than general machine tools, and its manufacturing requirements are more precise. Therefore, in the later design of CNC machine tools, many new measures have been adopted to strengthen rigidity, reduce thermal deformation and improve accuracy, which has made great changes in the external modeling, overall layout, transmission system and tool system of CNC machine tools

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