How big is the technical gap between the most popu

2022-09-26
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How big is the technical gap between medium and slow wire walking processing

NC WEDM includes fast wire walking and slow wire walking, which are widely used in mold manufacturing industry. What is the current development of the processing efficiency, cutting accuracy and surface quality of these two technologies

development status of fast wire walking processing technology

most importantly, as the name suggests, fast wire walking processing is named for the high-speed wire walking operation of electrode wires in the cutting process. Fast wire processing machine tool is an original electrical processing machine tool in China. After decades of continuous improvement and development, it has become an important processing means in the manufacturing industry. It can meet the requirements of medium and low-grade mold processing and other complex parts manufacturing, and occupies a considerable share in the medium and low-grade market

the biggest advantage of the fast wire processing machine tool lies in its good performance price ratio. Because of its practicality and economy, it has a large market in China. 6 The test results of electronic tensile testing machine can be output in Excel format. Traditional fast wire processing adopts one-time cutting. 1. The measurement system of tensile testing machine: the process has a processing efficiency of about 40 mm2/min and a surface roughness of ra3.0 μ M, there are obvious lines on the surface, and the machining accuracy is about 0.02 mm

in order to improve the processing quality, the manufacturer of the fast wire walking machine tool has improved the relevant parts of the machine tool with reference to the multiple cutting process, and the so-called "medium wire walking machine tool" has appeared. The numerical control accuracy, pulse power supply, wire walking system, process database and other process technologies of the machine tool have been greatly improved. The machining accuracy and surface quality are improved

at present, the technical indicators of wire walking machine tools: the efficiency of one cutting is 180 mm2/min, and the surface roughness after multiple cutting is RA ≤ 1.0 μ m. At this time, the average efficiency is 50 ㎜ 2/min, the processing surface gloss has no obvious cutting stripes, the processing accuracy is 0.01 ㎜, and the electrode wire loss is ≤ 0 01 mm/200000 mm2. These performance indicators look good, but it should be noted that to consolidate the existing market position, these indicators need to ensure all links. Once there are differences, such as changes in the concentration of working fluid and the loss of electrode wire, it will affect the stability of processing quality

typical manufacturers of wire walking machine tools in production include Suzhou Sanguang, Suzhou Hanqi, Shanghai special strategy, Beijing ande, Suzhou Baoma, Suzhou new spark, Shanghai large number, etc

development status of slow wire processing technology

with the continuous improvement of manufacturing accuracy and surface quality requirements of precision, complex and long-life stamping dies, fast wire processing technology can no longer meet the manufacturing requirements of precision dies. This status promotes the rapid development of slow wire processing technology, and its process indicators in all aspects have reached a fairly high level, which is irreplaceable by other processing technologies

(1) improvement of machining accuracy

multiple cutting technology is the fundamental means to improve the machining accuracy and surface quality of slow wire walking. Generally, it is formed by one-time cutting, the accuracy is improved by two-time cutting, and the surface quality is improved by more than three times cutting

due to the lag of electrode wire when cutting corners, the corners will collapse. In order to improve the accuracy of corner cutting, more dynamic corner processing strategies are adopted. Such as: automatically changing the processing speed, automatically adjusting the water pressure, controlling the processing energy, etc

the high-precision finishing circuit adopted by the advanced slow wire processing machine tool is an effective technology to improve the flatness of the processed workpiece, which significantly improves the accuracy of thick workpiece processing; In order to carry out the micro finishing of small fillets, narrow slots, narrow grooves and micro parts, the top CNC low-speed wire EDM machine tool can use 0.02-0.03 mm electrode wire for cutting

in order to ensure high-precision processing, the mechanical accuracy, pulse power accuracy and servo control accuracy of the machine tool (including the control of mechanical motion, pulse parameters, wire feeding system and working fluid system) have reached a very high level. Using the water temperature cooling device, the internal temperature of the machine tool is the same as the water temperature, and the thermal deformation of the machine tool is reduced; The closed-loop digital AC (DC) servo control system is adopted to ensure excellent dynamic performance and high positioning accuracy. The machining accuracy can be controlled within several microns, and the precision positioning can achieve 0.1 μ M equivalent control; Immersion machining is adopted to reduce the thermal deformation of the workpiece; Motor servo, closed-loop electrode wire tension control; The voltage modulation tool setting power supply is used to realize high-precision tool setting, and the tool setting accuracy can reach 0.002 mm, without damaging the workpiece, whether dry or wet

(2) the surface quality is improving day by day

the advanced slow wire processing machine tool adopts the non anti electrolysis pulse power supply with an average voltage of zero, and the damage of electrolysis has been reduced to a minimum. In addition, due to the improvement of pulse power supply, high peak value and narrow pulse width (microsecond level) are widely used. Most of the materials are thrown out in the gas phase, which takes away a lot of heat. The surface temperature of the workpiece cannot go up, and the cracking phenomenon is greatly reduced; Not only the processing efficiency is high, but also the surface quality is greatly improved. Using non electrolytic power supply for WEDM, the surface deterioration layer can be controlled within 2 μ Below M. The wear resistance of the cutting edge of cemented carbide die is no different from that of grinding, and even better than mechanical grinding. More and more parts are processed by "cutting instead of grinding"

(3) improvement of processing efficiency

due to the development of nanosecond high peak current pulse power supply technology and detection, control and anti-interference technology, the processing efficiency of the slow wire processing machine tool is also constantly improving. The maximum processing efficiency of the current advanced slow wire processing machine tool can reach 500 mm2/min. The processing efficiency of workpieces with larger thickness has practical significance. For example, when cutting workpieces with a thickness of 300 mm, the processing efficiency can reach 170 mm2/min. For the processing of workpiece with thickness change, the thickness of the workpiece is automatically detected, and the processing parameters are automatically adjusted to prevent wire breakage, so as to achieve the highest processing efficiency in this state

in addition, the fast automatic threading technology introduced by the advanced slow threading machine tool, with an automatic threading time of 15 s, improves the efficiency of processing operations; The double wire automatic exchange technology introduced can automatically switch between two wires with electrode wires of 0.20-0.02 mm. Thick wire is used for the first cutting, and the wire diameter is generally 0.25 mm to improve the processing efficiency, and coreless cutting is allowed; Then use fine wire for trimming. Generally, use 0.10mm fine wire to cut small rounded corners, which can improve the accuracy and save 30% - 50% of the cutting time in general

(4) development of automation, intelligence and informatization

in the processing process, in order to reduce human intervention and ensure the expected process indicators, the automation, intelligence and informatization of slow wire walking processing have achieved corresponding development

the complete process expert system of the slow wire processing machine gives a complete set of parameters according to the processing requirements. It not only includes the commonly used electrode wire grades and corresponding workpiece materials, but also provides the processing parameters of special materials such as PCD, PCBN, etc., which can generate their own standards according to whether the upper and lower nozzles are in contact with the workpiece, how far away they are, whether they are refined in the cutting air or open surface, and which processing strategy gives priority to precision, surface roughness and efficiency; The discharge expert system deals with the random factors in cutting. Under the conditions of cutting in, cutting out, cross-section change, center cutting, near edge cutting, large cross-section high-speed cutting, etc., the adaptive control strategy and automatic control function are used in the processing process to obtain continuous wire stable and efficient processing

the automatic hole free detection function is also very practical. During automatic skip processing, if the pre hole is forgotten to be punched or the hole position is offset, the machine tool will automatically move to the next pre hole, which can prevent shutdown during unattended processing. When a short circuit occurs after threading, it can automatically search the position of eliminating the short circuit, and improve the reliability of continuous unattended operation

the CNC system of the machine tool is equipped with standardized mechanical interfaces to form an intelligent manufacturing system. Through the manipulator of 3R system or EROWA system, the automatic exchange of workpieces (pallets) can be easily realized. With expert system and electrode wire automatic exchange technology, the whole processing process can be completed automatically

2. The technical level of all grades of slow moving wire processing machine tools

can be divided into four grades: top-level, high-end, medium-level and entry-level. Typical manufacturers of slow moving machine tools include GF processing scheme in Switzerland (formerly Archie Shamir), Makino in Japan, Mitsubishi in Japan, Sadiq in Japan, western Japan, Frank in Japan, etc

(1) top level slow moving wire processing machine tool

this kind of slow moving wire processing machine tool represents the highest level at present, mainly made in Switzerland and Japan. The machining accuracy of this kind of machine tool can be guaranteed within ± 0.002 mm, the maximum machining efficiency can reach 400-500 mm2/min, and the surface roughness can reach ra0.05 μ m. With perfect processing surface quality, the surface has almost no metamorphic layer, and can be used Φ The electrode wire of 0.02 mm is used for micro finishing. Most of the main machines have a heat balance system, and some machine tools use cutting in oil. This kind of machine tool has complete functions and a high degree of automation. It can directly complete the precision machining of molds, and the service life of the processed molds has reached the level of mechanical grinding

(2) high grade slow threading machine tools

these machine tools are basically produced by Swiss and Japanese companies, with automatic threading function, no resistance anti electrolytic power supply, and an overall thermal constant system, which can be used Φ The electrode wire of 0.07 mm is cut, and the accuracy is about ± 0.003 mm. The maximum processing efficiency can reach more than 300 mm2/min, and the surface roughness can reach RA 0.2 μ m. It has the function of timely detecting the change of workpiece section and optimizing the discharge power in real time. This kind of machine tool is also widely used in precision stamping die processing

(3) medium grade slow wire cutting machine tool

this machine tool is generally produced by Swiss and Japanese companies in China. The technical level of some Taiwan machines can also reach this level, and its configuration and performance meet the requirements of most domestic precision wire cutting processing. Generally, non resistance anti electrolysis power supply is used, which has the functions of submerged processing and taper cutting. The practical maximum processing efficiency is 150-200 mm2/min, and the best surface roughness is ra 0.4 μ m. The cutting accuracy can reach ± 0.005 mm, which is generally used Φ Electrode wires of 0.1mm and above are cut, and the anti-collision protection system is equipped to avoid collision damage caused by programming errors or misoperations. Automatic threading mechanism is equipped or optional

(4) entry level slow wire processing machine tool

this machine tool is generally Taiwan machine tool or domestic self-developed and produced machine tool, and its configuration and performance meet the processing requirements of domestic ordinary molds and parts. Generally, the process of cutting one and repairing one and cutting one and repairing two is used, which can stably achieve a surface finish of Ra0.8 μ M, and the machining accuracy is ± 0.008 mm. Most of them can only use electrode wires of 0.15mm or more for cutting. There is a certain gap between the processed surface microstructure and corners and advanced machine tools

in general, compared with fast wire walking machine tools, slow wire walking machine tools have obvious advantages in processing efficiency, accuracy, surface quality and so on. Although the price of slow moving wire processing machine tool is relatively expensive, with the rapid development of manufacturing industry, it will be more and more used in various processing fields

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