After the reciprocating wire EDM wire cutting machine adopts multiple cutting technology, although the processing quality is obviously improved, it still belongs to the category of high-speed wire EDM wire cutting machine. The cutting precision and smoothness still exist with the low speed wire cutting machine. The gap, and the retention of precision and finish, also needs to be further improved. "Basic physical principles free cations and electrons accumulate in the field, and soon form an ionized conductive channel. At this stage, a current is formed between the two plates. This causes numerous collisions between particles, forming a plasma region, and rising rapidly. High to 8000 to 12000 degrees, some materials are instantaneously melted on the surface of the two conductors, and at the same time, due to vaporization of the electrodes and the dielectric liquid, a bubble is formed, and its pressure rises regularly until it is very high. Then the current is interrupted and the temperature suddenly drops. Involving the inward explosion of the bubble, the generated power throws the dissolved material out of the crater, and then the corroded material recondenses into a small sphere in the dielectric liquid and is drained by the dielectric liquid. Then it is monitored and controlled by NC control. The servo is executed to make the discharge phenomenon uniform, so that the processed product is processed to become a product of a desired size and shape accuracy.
Classification EDM wire cutting machine can be divided into high-speed reciprocating wire EDM wire cutting machine (Reciprocating type High Speed ​​Wire Cut Electrical Discharge Machining commonly known as "fast wire"), low speed one-way wire EDM wire cutting machine ( Low Speed ​​one-way walk Wire Cut Electrical Discharge Machining is commonly known as "slow wire" and Vertical Wire Electrical Discharge Machining machine tool With Rotation Wire. It can also be divided into a single column cross table type and a double column type (commonly known as the gantry type) according to the work table form.
Reciprocating wire EDM wire cutting machine reciprocating wire EDM wire cutting machine set the wire speed of 6 ~ 12 m / s, is China's original model. Since September 1970, the “Digital Program Automatic Control Wire Cutting Machine Tool†has been successfully developed by the State-owned Changfeng Machinery General Factory of the Third Ministry of Machinery Industry, which is the first in China for this type of machine tool. In 1972, the Ministry of Machinery Industry conducted technical appraisal of the CKX CNC wire-cutting machine tool produced by the factory, and believed that it had reached the domestic advanced level at that time. In 1973, according to the decision of the Ministry of Machinery Industry, the CNC wire-cutting machine numbered CKX-1 began mass production. In September 1981, the DK3220 coordinate CNC machine with taper cutting function was successfully developed. The biggest feature of the product is the 1.5 degree taper cutting function. Completed major technical improvements in wire cutting machines. With the gradual improvement of the large taper cutting technology, the taper and the upper and lower profile cutting process have also made great progress. The breakthrough of large-thickness cutting technology has greatly improved the accuracy of cross section and longitudinal section, and the processing thickness can exceed 1000mm. The reciprocating wire cutting machine has certain advantages. At the same time, it meets the needs of domestic and foreign customers. The number of such machine tools is growing at a relatively fast rate, from the original annual output of 2-3 thousand units to tens of thousands of annual output. At present, the stock of reciprocating wire cutting machine tools in the country has reached more than 200,000 units. Medium and low-end mold manufacturing and special parts processing have become one of the most widely used models in CNC machine tools in China. However, since the reciprocating wire cutting machine cannot perform constant tension control on the wire, the wire is greatly shaken and is easily broken during processing. Since the electric grade wire is used reciprocally, it causes electrode wire loss, processing precision and surface quality are lowered.
Low-speed one-way wire EDM wire cutting machine low-speed wire cutting electromechanical "target=_blank> machine wire with copper wire as a tool electrode, generally for one-way movement at a speed of less than 0.2m / s, in copper wire and copper A pulse voltage of 60 to 300 V is applied between the materials to be processed such as steel or super-hard alloy, and a gap of 5 to 50 μm is maintained. The gap is filled with an insulating medium such as deionized water (close to distilled water) to allow electrode and workpiece to be processed. Spark discharge occurs, and each other is consumed and corroded, and numerous small pits are electrically etched on the surface of the workpiece. The NC control is monitored and controlled, and the servo mechanism is executed to make the discharge phenomenon uniform, so that the processed object is processed. It is made into a product with the required size and shape accuracy. The current precision is up to 0.001mm, and the surface quality is close to the grinding level. The electrode wire is no longer used after discharge, and the non-resistive anti-electrolysis power supply is generally used. Automatic threading and constant tension device. Smooth, uniform, small jitter, high processing precision, good surface quality, but not suitable for processing large thickness workpieces. Due to the precise structure of the machine tool, technical content High, the machine price is high, so the cost of use is also high.
In the early days, the one-way wire EDM machine was only an organic species of foreign companies. Although Taiwan's low-speed wire-cut EDM wire cutting machine started late, it has developed rapidly in recent years. One of the key measures is to jointly fund a number of home appliance processing machine tool manufacturers. With the limited support of relevant departments, the Taiwan Industrial Technology Research Institute has invested a large amount of manpower and material resources to develop key technologies. After more than 10 years of research, it has made breakthroughs in key technologies such as control systems and power supplies. The low-speed wire-cut EDM wire-cutting machine manufactured by various enterprises in Taiwan should be in the range of mid-range machines. It has reached a growth rate of 20% to 30% every year for the past three years. It is estimated that in the next five years, Taiwan’s low-speed wire-cut EDM wire cutting machine The annual output can reach 2,000 units, which can account for more than 25% of the world market. The low-speed wire-cut EDM wire cutter has high technical content and good market prospects, and can obtain a high return. It is a “strategic place†and a “strategic highland†for various manufacturers in the electric processing industry. It can also be said that whoever masters the technology of the low-speed wire-cut EDM wire-cutting machine will have the opportunity to develop and grow in the next step. In order to seize the Chinese market, electric processing machine tool manufacturers in Japan, Switzerland and Taiwan set up factories in mainland China to produce such machine tools. With the support of the special fund of the Ministry of Science and Technology, China's science and technology workers have invested a large amount of research and development, and have completed the research and development of a new generation of low-speed wire-cut EDM wire-cutting machines, and have made major breakthroughs. The product, and occupied a certain market share, its performance indicators can reach the mid-range machine level. At present, some domestic companies hope to develop low-speed wire EDM wire cutting processing technology through cooperation with related companies in Taiwan.
Vertical self-rotating electric discharge wire cutting machine
Vertical self-rotating electric discharge wire cutting machine (horizontal self-rotating electric discharge wire cutting machine). The characteristics of the vertical rotary electric discharge wire cutting machine are different from the traditional high-speed wire-cutting and low-speed wire-cut wire EDM. First, the wire movement mode is one electrode more than the traditional two-wire wire-cutting process. The rotary motion of the wire; secondly, the wire speed of the wire is directly between the high speed wire and the low speed wire, and the speed is 1 to 2 m/s. Due to the increased rotational movement of the wire during processing, the biggest difference between a vertical rotary wire EDM machine and other types of wire cutters is the wire-traveling system. The wire-traveling system of the vertical rotary electric discharge wire cutting machine has two sets of the same two ends of the wire-cutting end and the wire-discharging end as the wire-trailing structure, realizing the high-speed rotary motion of the wire and the composite movement of the low-speed wire. The area between the two sets of spindle heads is the effective machining area. Except for the wire-traveling system, the other components of the machine are the same as the high-speed wire-cutting machine.
Compared with the one-way low-speed wire-cut EDM machine, the reciprocating high-speed wire EDM machine has a large gap in the key technical indicators such as average productivity, cutting accuracy and surface roughness. In response to these gaps, at the beginning of this century, several high-speed reciprocating wire EDM machines in China achieved multiple cutting operations on high-speed wire-cutting machines (this type of machine tool is commonly known as “medium wire†Medium Speed ​​Wire cut Electrical Discharge Machining). The so-called "medium wire" does not mean that the wire speed is between high speed and low speed, but a composite wire cutting machine. The wire routing principle is to use 8-12m/s high speed wire for roughing and fine machining. 1-3m/s low-speed wire, so the work is relatively stable, 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, and the processing quality can be between the high-speed wire-cutting machine. Between the low speed wire machine. Therefore, it can be said that the user said "medium wire", in fact, the reciprocating wire EDM wire cutting machine borrowed from the processing technology of some low-speed wire-cutting machines, and realized the stripless cutting and multiple cutting.
After several years of development, almost all domestic manufacturers of high-speed wire-cut EDM wire-cutting machines are in the process of production and sales, but it turns out that not all reciprocating wire EDM machines can cut many times. Or not all reciprocating wire EDM machines can achieve good process results after multiple cutting techniques. Multiple cutting is a comprehensive technology, which involves the numerical control precision of the machine tool, pulse power supply, process database, wire routing system, working fluid and a large number of process problems. It is not simply adding a set of high speed wire machine. The wire frequency conversion speed control system can be realized, only those reciprocating wire EDM machines with high manufacturing precision and multiple cutting conditions in various aspects can perform multiple cutting and stripeless cutting, and obtain remarkable Process effect. Therefore, our production enterprises must pay full attention to this problem, we must do it according to system engineering, and really use this technology well to make this product a good one. For example, in order to further improve the accuracy of the machine body, the X and Y coordinate worktables use a DC or AC servo motor as the drive unit to directly drive the ball screw. At the same time, the full-closed control with pitch compensation function is used, and the CNC can be used. The system compensates and corrects the positioning accuracy error of the machine tool. Under the premise of ensuring accuracy, the machining accuracy caused by long-term use is reduced, and the service life of the machine tool is prolonged. The wire system uses a special (mostly diamond) wire retainer to keep the wire filament relatively stable and reduce the tension change of the wire during processing. In the cooling system, the commonly used extensive cooling method is changed, and multi-stage filtration is adopted to control key parameters such as dielectric constant to ensure smooth finishing. The control software provides an open database of processing parameters, which can be selected according to the material's texture, thickness, roughness and other conditions. It is believed that through our efforts, the cutting technology will be more perfect, and the reciprocating wire EDM technology will also be better applied and developed.
After the reciprocating wire EDM wire cutting machine adopts multiple cutting technology, although the processing quality is obviously improved, it still belongs to the category of high-speed wire EDM wire cutting machine. The cutting precision and smoothness still exist with the low speed wire cutting machine. The gap, and the retention of precision and finish, also needs to be further improved. The “medium wire machine†has the characteristics of simple structure, low cost and low consumption. Therefore, it also has room for survival. The current implementation standard is still the relevant standard of high-speed wire-cutting machine. Therefore, the production enterprise should Be careful, be sure to seek truth from facts.
Wire EDM
Distinguish between fast-cut wire cutting, medium-cut wire cutting, and slow wire cutting.
1: The wire cutting speed of the fast wire EDM wire cutting is 6~12 m/s, and the electrode wire is used for high-speed reciprocating motion, and the cutting precision is poor.
2: Medium wire EDM wire cutting is a new process of frequency conversion and multiple cutting on the basis of fast wire cutting.
3: The wire speed of the slow wire EDM wire cutting is 0.2m/s, and the wire wire is made in a low speed one-way motion with high cutting precision.
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