Classification of the most popular CNC machine too

Classification of CNC machine tools

at present, there are many varieties of CNC machine tools, which are usually classified according to the following methods

I. classification by motion mode

1. Point control system point control system refers to a system in which the numerical control system only controls the tool or machine tool workbench to move accurately from one point to another, and the trajectory of motion between points does not need to be strictly controlled. In order to reduce the movement and positioning time of the moving parts, it is generally to move quickly to the position near the end point, and then move accurately to the end point positioning position at a low speed to ensure good positioning accuracy. The tool does not cut during movement. CNC coordinate boring machine, CNC drilling machine, CNC punching machine, etc. are mainly used in this kind of control system

2. Point position linear control system point position linear control system refers to a control system in which the numerical control system not only controls the tool or worktable to move accurately from one point to the next, but also ensures that the motion path between two points is a straight line. Cutting can be carried out during tool movement. The application of this kind of control system includes CNC lathe, CNC drilling machine and CNC milling machine

3. Contour control system contour control system, also known as continuous cutting control system, refers to a system in which the CNC system can strictly and continuously control two or more coordinate axes at the same time. It can not only control the moving parts to move accurately from one point to another, but also control the speed and displacement of each point in the whole processing process, and process the parts into a certain contour related button): when designing, we should consider the action direction, resistance, speed, safety and other factors of the machine. Such control systems are applied to CNC milling machines, CNC lathes, CNC gear processing machines and machining centers in 2014

II. Classification by control mode

1. Open loop control CNC machine tools

the characteristics of the open loop control system are that there is no detection feedback device in the system, the instruction information is transmitted in one direction, and the instruction 1 Add shims in the fixture; After it is sent out, it will not be fed back, so it is called open-loop control

affected by the step accuracy and working frequency of stepping motor and the transmission accuracy of transmission mechanism, the speed and accuracy of open-loop system are low. However, due to its simple structure, convenient debugging, easy maintenance and low cost, open-loop control is still widely used in economic CNC machine tools

2. Semi closed loop control CNC machine tool

semi closed loop control CNC machine tool does not directly detect the displacement of the workbench, but uses corner displacement detection elements to measure the rotation angle of the servo motor or lead screw, calculate the actual displacement of the workbench, feed it back to the computer for position comparison, and control it with the compared difference. Since the feedback loop does not contain the workbench, it is called semi closed loop control

the accuracy of semi closed-loop control is worse than that of closed-loop control, but it has good stability, low cost, and easy debugging and maintenance. It takes into account the characteristics of both open-loop control and closed-loop control, so its application is relatively common

3. Closed loop control CNC machine tool

the feature of the closed loop control system is that the actual displacement of the workbench is fed back to the computer by using the detection element installed on the workbench, compared with the required position command, and controlled with the compared difference until the difference is eliminated. It can be seen that the closed-loop control system can eliminate the influence of various errors of mechanical transmission components and the interference generated in the workpiece processing process, so as to greatly improve the machining accuracy. The function of the speed detection element is to transform the actual speed of the servo motor into an electrical signal and send it to the speed control circuit for feedback correction to ensure that the motor speed remains constant. The commonly used speed detection element is the speed measuring motor

closed loop control is characterized by high machining accuracy and fast moving speed. This kind of CNC machine tool adopts DC servo motor or AC servo motor as the driving element. The control circuit of the motor is complex, and the detection element is expensive. Therefore, debugging and maintenance are complex and costly

III. classification according to process use

according to process use classification, CNC machine tools can be divided into CNC drilling machines, lathes, milling machines, boring machines, grinding machines and gear processing machines, as well as presses, punches, pipe benders, EDM cutting machines, flame cutting machines, etc

the machining center is a CNC machine tool with a tool magazine and an automatic tool change device. Below it, you will know why these problems fell to the ground? Multiple processes can be realized on one machine tool. The workpiece can be clamped at one time to complete a variety of processing, which not only saves auxiliary working hours, but also improves the processing accuracy. The machining center is especially suitable for the processing of boxes and shells. The turning center can complete the machining of all rotating parts