At present, a lot of varieties of NC machine tools are usually several ways according to the following classification.
First, by way of sports classification
1, point-point control system control system control system are index only tool or machine tool control table, from the point Zonghuai indeed to move to another point, and between points and the trajectories do not need to exercise strict control system. In order to reduce the moving parts of exercise time and location, generally fast-moving first to the finish line near the location, then to low-speed and accurate positioning to move to the end position, in order to ensure good positioning accuracy. Moving the cutting tool is not. The use of such control systems have CNC jig borer, CNC drilling machine, CNC punching machine and so on.
2, point linear control system point linear control systems are control systems not only control the index or table knives and accurately from one point to move to the next point, but also to ensure that the exercise between two points is a straight-line trajectory of the control system. Mobile Tool cutting process can be carried out. Application of such control systems have CNC lathe, CNC drilling machine and CNC milling machine and so on.
3, contour control system control system, also known as contour cutting continuous control systems, control systems are able to index two or more axes simultaneously strictly continuous control system. It is not only moving parts that can be controlled from one point Zonghuai indeed point to move to another, but also control the entire process every point of the speed and amount of displacement will be processed into certain parts of the contour shape. Application of such control systems have CNC milling machine, CNC lathe, CNC machine tools and processing gear center.
Two, by control classification
1, open-loop control of CNC machine tools
Open-loop control system characteristics of the system are not detected feedback devices, one-way information transmission instruction, and instruction is issued, no feedback, so that the open-loop control.
By the stepper motor step accuracy and frequency, as well as transmission of the driving accuracy the impact of open-loop system in terms of speed and accuracy are lower. However, because of the open-loop control structure is simple and debugging easy maintenance, lower cost, are still being widely used on CNC machine tools.
2, semi-closed-loop control of CNC machine tools
Semi-closed-loop control of CNC machine tools is not a direct measurement of the displacement table, instead of using the angle of displacement detection components, measured servo motor or screw corner table projected actual displacement, feedback to the computer in the location of comparison, compared with the margin control. Because there is no feedback loop contains the table, so that semi-closed-loop control.
Semi-closed-loop control closed-loop control accuracy than bad, but good stability, lower cost, easier to debug than the repair, taking into account the open-loop control and closed-loop control characteristics of the two, so the more general application.
3, the closed-loop control of CNC machine tools
Closed-loop control system is characterized by the use of the installation work at the stage of detection components will be the actual table displacement feedback to the computer with the location of instructions required to compare the difference compared with control, until the margin eliminated. Can be seen that the closed-loop control system can eliminate all kinds of mechanical transmission components and workpiece error process generated by the impact of interference, thus greatly improve machining accuracy. The role of speed detection devices are servo motor will be converted into the actual speed signal to the speed control circuit, the feedback correction, guaranteed to keep the motor speed constant. Speed detection devices are commonly used electrical velocimetry.
Closed-loop control is characterized by high precision machining, mobile speed. This type of CNC machine tools using DC servo motor or AC servo motor as the drive components, motor control circuit is rather complicated, expensive detection devices. Debug and repair and therefore more complex and costly.
Three, according to technology use classification
Use classification by technology, CNC machine tools can be divided into the CNC drilling machine, lathe, milling machine, boring machine, grinding machine and gear machine tools, as well as ballast bed, punching machine, bending machine, electric spark cutting machine, flame cutting machines.
Machining center with a knife are the Treasury and automatic tool changing device of the CNC machine tools, it can achieve on a wide range of machine tool processing. Workpiece clamping time, to be completed by a variety of processing, saving hours of work aids, and improve machining accuracy. Machining Center is especially suitable for cabinet, casing processing. Turning machining center to be completed for all rotary machining.
