Development and advantages of wire cutting machine tools

1. Basic theory

Experts pointed out that the so-called "medium wire travel" does not mean that the wire travel speed is between high and low speeds, but a composite wire cutting machine, that is, the principle of wire travel is to use high-speed (8-12m/s) wire travel during rough machining. , Low-speed (1-3m/s) wire feeding is used for finishing, so that the work is relatively stable and the jitter is small, and the error caused by material deformation and molybdenum wire loss is reduced by multiple cutting, so that the processing quality is relatively improved. It can be between high-speed wire feeder and low-speed wire feeder. Therefore, it can be said that the user's "intermediate wire travel" is actually a reciprocating wire EDM wire cutting machine that draws on the processing technology of some low-speed wire travel machines, and realizes stripe-free cutting and multiple cutting.

In practice, it is found that the first cutting task in multiple cuttings is mainly high-speed and stable cutting. High peak current and long pulse width can be used for high-current cutting to obtain higher cutting speed. The task of the second cutting is to refine and ensure the machining dimensional accuracy. The medium standard can be selected, so that the roughness Ra after the second cutting is between 1.4 and 1.7 μm. In order to achieve the purpose of finishing, a low-speed wire-feeding method is usually adopted, the wire-feeding speed is 1-3m/s, and the tracking feed speed is limited to a certain range, so as to eliminate the round-trip cutting stripes and obtain the required machining dimensional accuracy. . The task of the third, fourth or more cuttings (currently the middle wire feed control software can achieve up to seven cuttings) is polishing and polishing, which can be trimmed with the minimum pulse width (currently the minimum frequency can be divided to 1μs). , and the peak current varies with the quality of the machined surface. In fact, the finishing process is a kind of electric spark grinding, and the processing volume is very small, which will not change the size of the workpiece. For the wire-feeding method, just use low-speed wire-feeding and limited-speed feed like the second cutting. In the process of processing, multiple cuttings also need to pay attention to the deformation treatment, because when the workpiece is cut online, with the effect of the original internal stress and the influence of the processing thermal stress generated by the spark discharge, non-directional and irregular deformation will occur. , so that the thickness of the subsequent cutting knife is uneven, which affects the processing quality and processing accuracy. Therefore, it is necessary to reserve different machining allowances according to different materials, so that the workpiece can fully release the internal stress and completely torsional deformation, and there can be enough allowance for fine cutting processing in the subsequent multiple cuts, so that the final size of the workpiece can be guaranteed.

2.Second, the origin of domestic wire cutting machine tools

Wire cutting machine tools originated in the early 1970s. Before the implementation of the market economy, the development of wire cutting machine tools was relatively slow, mainly because China's electronics industry was relatively backward at that time, and the production plants of wire cutting machine tools were state-owned enterprises.

Although the technical ability is strong, due to the disconnection from the market and the constraints of the planned economy, the wire cutting machine tools produced not only have a high failure rate, but also have limited performance (can only cut 50mm thick, and the efficiency is about 30mm²/min), but in any case This kind of wire cutting machine is a kind of machine tool unique to China. Although it has lower precision compared with foreign wire cutting machine tools, its manufacturing and use costs have absolute advantages. It is very suitable for those developing countries. It is precisely because of this potential market demand.

After the implementation of the market economy in China, many wire cutting machine tool manufacturers have emerged across the country, so disorderly competition has emerged in the wire cutting market, and disorderly competition has evolved into price competition. In order to reduce costs, some enterprises with poor technical strength reduce production. Standards, coupled with the ineffective management of relevant national technical supervision agencies, make the quality of wire cutting machine tools of different manufacturers in the market vary greatly. For the same wire cutting machine tools, some can be used for 10 years without loss of accuracy, and some can only be used for two years. The price of wire cutting machine tools of the same specification can differ by 100,000 yuan, which does cause great difficulties for users (especially foreign users) in the selection of models. appear in the market?

From the perspective of the social environment, China has not implemented a market economy for a long time. Some small wire cutting machine tool manufacturers are still in the stage of accumulation of original capital. These manufacturers often do not have the ability to manufacture complete machines. The quality control of the whole process cannot be talked about at all, and research and development and innovation are even more impossible. In addition, the current laws in China that are compatible with the market economy are not mature, and the local government protection is driven by interests. Therefore, these enterprises without production capacity It will continue to survive. Judging from the current situation, the state's attitude towards this is that it will be eliminated naturally through market competition.
Third, the development status of wire cutting machine tools

3.Today, the non-scientific name of "China wire cutting machine" has become the code name of a high-end product in China's unique high-speed wire cutting machine. Committed to the high-speed wire cutting machine to the international market.

It has been recognized that multiple cuts can effectively improve the processing quality of high-speed wire-cutting WEDM, but not all high-speed wire-cutting machines can perform multiple cuts, or not all high-speed wire-cutting machines can perform multiple cuts. The wire spark cutting machine can obtain good process results after using multiple cutting techniques. Only those high-speed wire-cutting machines with high manufacturing precision and multiple cutting conditions in various aspects can perform multiple cutting and streak-free cutting, and obtain significant process effects. After the high-speed wire cutting machine adopts the multiple cutting technology, its processing quality is significantly improved, and it is close to the economical low-speed wire cutting machine, and the price and consumption of this machine tool are far lower than the low-speed wire EDM wire. Cutting Machine.

"At present, the technical strength of domestic enterprises is uneven, and the capital strength is also different. To radiate a new spring of high-speed wire cutting machines, we must first pay attention to technological innovation, and only technology can be sustainable. The foundation and guarantee of development; thirdly, it is possible to adopt the method of enterprise alliance, led by strong enterprises, unite or cooperate with relevant enterprises, and realize resource sharing by promoting strengths and avoiding weaknesses; thirdly, it is necessary to have healthy and rational competition, and avoid simplifying products. Prevent technology from deteriorating. Now, our efforts in technology have led to the popularity of 'China Silk Road', which is a path worth continuing to explore. Unique to China (except mainland China, no country or region produces such machine tools) The high-speed wire-cutting wire EDM (WEDM-HS) developed by the manufacturer) has developed rapidly since it was successfully developed in the late 1960s due to its simple structure, low cost, good process effect, and low consumption during use. , has become an essential process equipment in the manufacturing industry.

Yu Zhongqiang, vice president of sales of Sanqi Medium Wire Cutting, believes that the current domestic medium wire cutting technology has been further improved, and it is close to slow wire cutting in terms of accuracy, smoothness, speed, etc., which can replace part or even half of the processing of slow wire cutting. Closed-loop, basically meeting the needs of medium-sized mold factories.

4. Conclusion and Outlook

The wire-feeding machine tool is an original electric processing machine tool in my country. It has a wide range of applications in the field of mold manufacturing and parts processing, and occupies a considerable weight in the middle and low-end market. At present, how to develop the wire-feeding machine tool is a topic of great concern to the electrical processing industry. We must learn from the successful experience of foreign countries, foster strengths and avoid weaknesses, directly apply the latest achievements of today's computer technology, and develop a powerful PC-based numerical control system as soon as possible to lay a good foundation for the development of wire-feeding machine tools from the hardware; at the same time, pay attention to artificial intelligence technology Combined with high-speed wire cutting machine, computer software technology is used to improve the performance of the machine tool. In addition, strengthening the research on the machine tool body and the application of multiple cutting technology have greatly improved the overall processing level of the machine tool, and continuously enhanced the competitiveness of the high-speed wire cutting machine in the market. While using new technology and new process, we must also pay attention to the in-depth and meticulous basic theory and experimental research on the process rules of WEDM, which is also a very important link.