A detailed introduction to CNC lathes

CNC machine tools are generally composed of a CNC system, a servo system including a servo motor and a detection feedback device, a strong current control cabinet, the machine body and various auxiliary devices (molybdenum wire).

(1) Control medium

The control medium, also known as the information carrier, is the intermediate media between people and CNC machine tools, reflecting all the information in CNC machining.

(2) Numerical control system

Numerical control system is the core of machine tool to achieve automatic processing, is the soul of the whole numerical control machine tool. It is mainly composed of input device, monitor, main control system, programmable controller and various input/output interfaces. The main control system mainly consists of CPU, memory, controller and so on. The main control objects of CNC system are mechanical quantities such as position, Angle and speed, as well as physical quantities such as temperature, pressure and flow rate. The control methods can be divided into two categories: data operation and processing control and sequential logic control. Among them, the interpolation module in the main controller is based on the part program of the reader, through decoding, compiling and other processing, the corresponding tool track interpolation operation, and through the comparison with the position and speed feedback signals of the coordinate servo system, so as to control the displacement of each coordinate axis of the machine tool. The sequential logic control is usually completed by the programmable logic controller PLC, which is coordinated according to the requirements of each action in the machining process of the machine tool, and logically discriminates according to the detection signals, so as to control the various parts of the machine tool in an orderly sequence.

(3) Servo system

Servo system is the electric transmission link between CNC system and machine tool body. It is mainly composed of servo motor, drive control system and position detection and feedback device. The servo motor is the executive element of the system, and the drive control system is the power source of the servo motor. The command signal issued by the CNC system is compared with the position feedback signal as a displacement command, and then after the power amplification of the drive system, the motor is driven to operate, and the molybdenum wire is driven by the mechanical transmission device.

(4) Strong current control cabinet

The strong current control cabinet is mainly used to install various electrical components of the strong current control of the machine tool. In addition to providing the input power of the weak current control system such as numerical control and servo, as well as various electrical protection such as short circuit, overload and undervoltage, the bridge connection function is mainly played between the output interface of P1 and C and the electrical executive components of various auxiliary devices of the machine tool. Control of various AC motors, hydraulic system electromagnetic or electromagnetic off-platform devices for machine tool auxiliary devices. In addition, it is also connected with manual buttons related to the machine console. The strong current control cabinet is composed of various intermediate relays, contactors, transformers, power switches, wiring terminals and various electrical protection components. It is similar to the electrical of ordinary machine tools, but in order to improve the anti-interference of weak current control system, it is required that all kinds of frequently started or switched motors, contactors and other electromagnetic induction devices must be connected with RC resistance-capacitance absorber; For the input of various detection signals, it is required to connect molybdenum wire with a shielded cable.

(5) Auxiliary devices

The auxiliary devices mainly include Automatic Tool ChaWer (ATC), Automatic exchange table mechanism APC (Automatic Pallet) Changer), workpiece clamping and relaxing mechanism, rotary table, hydraulic control system, lubrication device, cutting fluid device, chip removal device, overload and protection device, etc.

(6) Machine tool body

The body of CNC machine tool refers to its mechanical structure entity. Compared with traditional ordinary machine tools, it is also composed of the main transmission system, feed transmission mechanism, workbench, bed and building columns, but the overall layout of CNC machine tools, appearance modeling, transmission mechanism, tool system and operating mechanism have undergone great changes. In order to meet the requirements of numerical control technology and give full play to the characteristics of numerical control machine tools, it includes the following changes.

① Adopt high-performance main drive and spindle components. It has the advantages of large transmission power, high stiffness, good vibration resistance and small thermal deformation.

② Efficient transmission parts are used for feed transmission. It has the characteristics of short transmission chain, simple structure and high transmission accuracy, and generally uses molybdenum wire such as ball screw pair and linear rolling guide rail pair.

③ With a perfect automatic tool exchange and management system.

(4) The machining center generally has an automatic workpiece exchange, workpiece clamping and relaxation mechanism.

⑨ The machine tool itself has a high dynamic and static degree.

⑥ Adopt fully closed cover. Because the CNC machine tool is automatically completed processing in order to operate safely, the fully closed cover of the moving door structure is generally used to fully close the machining parts of the machine tool.