Introduction to the knowledge of CNC wire cutting machine tools

CNC wire cutting machine tool is composed of three parts: mechanical, electrical and working fluid system.

The mechanical part of the wire cutting machine tool is the foundation, and its accuracy directly affects the working accuracy of the machine tool, and also affects the full play of the electrical performance. The mechanical system consists of the machine bed, coordinate table, wire transport mechanism, wire frame mechanism, taper mechanism, lubrication system, etc. The machine bed is usually a box structure, which provides an installation platform for various components, and is closely related to the accuracy of the machine tool. The coordinate workbench is usually composed of a cross carriage, a rolling guide, a screw motion pair, and a gear transmission mechanism. It is mainly the relative movement with the electrode wire to complete the processing of the workpiece. The wire transport mechanism is composed of a wire storage drum, a motor, a gear pair, a transmission mechanism, a reversing device, and an insulating part. The electrode wires are neatly arranged and wound on the wire storage cylinder. The wire rack is divided into single-column cantilever type and double-column gantry type. The single-post cantilever type is divided into upper and lower arms. Generally, the lower arm is fixed, and the upper arm can be moved up and down. The guide wheel is installed on the wire frame to support the motor wire. The taper mechanism can be divided into swing type and cross carriage type structure. The swing type is completed by the rotation of the upper and lower arms, and is generally used in large taper machines. The cross carriage type is completed by moving the electrode wire to expand and contract, and it is generally suitable for small taper machines. The lubrication system is used to ease the wear of mechanical parts, improve mechanical efficiency, and reduce power loss. It can play the role of cooling, corrosion inhibition, vibration absorption and noise reduction.

The working fluid system is generally composed of a working fluid tank, a working fluid pump, a fluid inlet pipe, a fluid return pipe, a flow control valve, a filter screen cover or a filter element. The main function is to concentrate the discharge energy, take away the discharge heat to cool the electrode wire and the workpiece, and remove the electrical corrosion products.

The electrical part includes machine tool circuit, pulse power supply, driving power supply and control system. The machine tool circuit mainly controls the operation of the wire transport motor and the working fluid pump, so that the electrode wire can continuously cut the workpiece. The pulse power supply provides spark discharge energy between the electrode wire and the workpiece to cut the workpiece. Drive power is also called drive circuit, which is composed of pulse distributor, power amplifier circuit, power supply circuit, preamplifier circuit and other control circuits. It is a special power supply that provides power to the stepper motor, and is used to control the stepper motor. The control system mainly controls the movement of the carriage of the workbench (track control) and the discharge of the pulse power supply (processing control).

Control system from the late 1960s to the mid-1970s, the CNC system of high-speed wire-cutting machine tools in China-'special industrial computerRegisters, input controllers, arithmetic units, output controllers, etc., the processing program is manually input through the toggle switch, or read from the perforated paper tape through the photoelectric reader, using the glow digital tube and neon lamp to display the counting length and X, Y coordinate value (binary). In the late 1970s, CNC systems have transitioned to circuits based on medium and large-scale integrated circuit chips. Although the basic principle and structure have not changed, the function has been strengthened and the reliability has also been improved. Its input still has two ways of manual input (pull button or button) and paper tape input (telegraph head), indicating that there are fluorescent digital tubes and light-emitting diodes. This type of product has been in use until the end of the 1980s. With the emergence of single-board microcomputers (computers with CPU, RAM, ROM, input and output interfaces installed on a printed circuit board, referred to as single-board computers), high-speed wire cutting machine controllers are used in large quantities, with Z-80 as the The single-board computer of the microcomputer processor has truly achieved the goal of strong function and price. This is a glorious period for simple CNC systems. With the development of other related industries, CNC high-speed wire EDM has been rapidly popularized. By the 1990s, the CNC system with 8051 series single-chip controllers had functions such as graphic scaling, backlash compensation, short-circuit retraction, broken wire protection, power failure memory, automatic centering, automatic shutdown at the end of processing, and taper cutting. Function. The programming and control integrated machine with display has also been used, but the programmed program cannot be directly transmitted to other consoles, but it is equipped with external equipment such as printers and paper tape punching machines, and can only control a single machine tool. With the rapid development and popularization of computers, desktop microcomputers (including industrial computers) can be used to control several machine tools that work independently. Within the allowable quantity range, adding machine tools only needs to increase the control card. The working status of each machine tool can be monitored separately by switching the screen. This not only saves the cost of the control system, but also uses the computer's powerful data access capabilities. The function of automatic programming system is continuously enhanced, and there are various programming methods, such as command input, drawing method, scanning method, CAD file conversion, etc., and data exchange can also be carried out through U disk, network and other interfaces and communications. Avoid manual input procedures, drawing inefficiency and errors.

At present, the development of fast-moving wire-cutting technology has become clear. On the basis of maintaining the advantages of reciprocating wire-cutting, continuous exploration and research are carried out, and new theories and new methods are applied to new In the system. The new generation control system will be more stable, more practical, simpler and more convenient.