What Are the Different Types of Machine Tool Controls?

NC machine tool is the abbreviation of Computer numerical control machine tools, which is an automatic machine tool with a program control system. NC machine tool realizes the processing of complex, precise, small batches, and multiple varieties. It is a flexible, high-performance automatic machine tool, and represents the development direction of modern machine tool control technology.

Classification of CNC machine tools

Right!

CNC machine tools are digitally controlled

1. Ordinary CNC machine tools : Ordinary CNC machine tools generally refer to automated machine tools that implement digital control on a process in the processing process, such as CNC milling machines, CNC lathes, CNC drilling machines, CNC grinding machines, and CNC gear machining machines. Ordinary CNC machine tools are not perfect in terms of automation. The replacement of tools and the clamping of parts still need to be done manually.

2. Machining center : Machining center is a CNC machine tool with a tool magazine and an automatic tool changer. It combines the functions of a CNC milling machine, a CNC boring machine, and a CNC drilling machine. After a part is clamped, most of its machining surfaces can be processed Milling.

1) Point control NC machine tools : The NC system only controls the exact position of the tool from one point to another, and does not control the movement trajectory. The movement between the coordinate axes is irrelevant, and the workpiece is not processed during the movement. Such CNC machine tools are mainly CNC drilling machines, CNC coordinate boring machines, CNC punching machines, etc.

2) Linear control CNC machine tools : In addition to controlling the exact position between the points, the CNC system must also ensure that the movement trajectory between the two points is a straight line, and the movement speed must also be controlled, also known as point linear control. This kind of CNC machine tools are relatively simple CNC lathes, CNC milling machines, CNC grinding machines, etc. Numerical control machine tools used only for linear control are rare.

3) Contour control CNC machine tools : The feature of contour control is that it can continuously and continuously control the displacement and speed of two or more motion coordinates. It must not only control the start and end coordinates of the moving parts of the machine tool, but also control The speed, direction and displacement of each point in the entire machining process are also called continuous control CNC machine tools. This type of CNC machine tools are mainly CNC lathes, CNC milling machines, CNC wire cutting machines, machining centers, etc.

1) Open-loop control CNC machine tools : This type of machine tools does not have a position detection feedback device, and usually uses a stepper motor as the actuator. The input data is calculated by the numerical control system, and a pulse command is issued to make the stepping motor rotate through a step angle, which is then converted into a linear movement of the table by the mechanical transmission mechanism. The moving speed and displacement of the moving part are determined by the frequency of the input pulse and Determined by the number of pulses.

2) Semi-closed-loop control CNC machine tools : Install detection elements (such as induction synchronizers or photoelectric encoders) at the end of the motor or the end of the screw, and indirectly detect the displacement of the moving part by detecting its rotation angle, and then feedback to the CNC System. Since most of the mechanical transmission links are not included in the closed loop of the system, more stable control characteristics can be obtained. Although its control accuracy is not as good as that of a closed-loop control CNC machine tool, it is more convenient to debug and is therefore widely used.

3) Closed-loop control CNC machine tools : This type of CNC machine tools has a position detection feedback device. The position detection feedback device uses linear displacement detection elements, which are directly installed on the moving parts of the machine tool. The measurement results are directly fed back to the CNC device. It can eliminate the transmission error in the entire mechanical transmission chain from the motor to the moving parts of the machine tool, and finally achieve accurate positioning.