机械制造加工 外文翻译 外文文献 英文文献 电火花线切割技术

Wire EDM TechnologyAbstract: With the continuous improvement of machinery manufacturing and the need for precision processing, advanced machinery manufacturing technology also matter of course. In this paper, EDM wire cutting technology and its application and development trends.Key words: Mechanical manufacturing technology, EDM wire cutting0.PrefaceManufacturing technology is not only a measure of a country an important indicator of the level of technological development is the focus of international technological competition. Machinery manufacturing technology is the study of product design, production, processing, manufacturing, selling and use, maintenance services and even the whole process of recycling the engineering disciplines, is to enhance quality, efficiency, competitiveness as the goal, including material flow, information flow and energy flow complete system works. With the development of society, the requirements for products, great changes have taken place, asked to diverse species, update to speed, quality to high-end, the use to be convenient, the price must be reasonable and appearance to appearance, higher degree of automation, service better, more and more to meet the requirements necessary to adopt advanced machine manufacturing technology. The characteristics of advanced manufacturing technology: (1) it is the 21st century technology. (2) it is the technology for indust of micro-hole slot, narrow, arbitrary curves, with allowance of small, high precision, short production cycle, manufacturing highlight the advantages of low cost, has been widely apprial applications. (3) it is to harness the production process systems engineering. (4) it is a technology for global competition. (5) it is the unity of the three elements of market competition.However, EDM wire cutting technology is one of advanced manufacturing technology, mechanical production and wide application, it is mainly used for processing a variety of complex shapes and precision small parts, for example, Die punch, die, punch and die, fixed plate, stripper plate and so on, forming cutter, model, EDM machining the metal electrode, a varietylied in production, the current account abroad WEDM EDM over 60% of the total. The following highlights WEDM machining technology and application of principles and development trends.1. Principles of WEDMWEDM (Wire cut Electrical Discharge Machining, referred to as the WEDM), sometimes also known as cutting. The basic physical principle is the presence of free positive ions and electrons to accumulate, and soon to be ionized to form a conductive channel. In this stage, a current between two plates, lead to numerous collisions between particles occur, forming a plasma, and soon increased to 8000 to 12,000 degrees Celsius, melting moments in the two conductors, some of the material at the same time, the electrode and dielectric fluid vaporized, forming a bubble, the rules and it increased until the pressure isvery high. And current interruption, the temperature suddenly drop, causing the bubble implosion, the momentum generated to melt the material thrown into the crater, and then the material is corrosive fluid in the dielectric re-condensed into a small ball, and was discharged dielectric fluid. NC-controlled then the monitoring and control, servo bodies, so that the phenomenon of uniform discharge to achieve the processing of materials to be processed, making it meet the requirements of size and shape precision products.On this basis, our domestic development of the Fast Wire System (HS). Europe and Japan, developed the walking system (LS). The main difference is 1, the electrode wire of tungsten and molybdenum alloy wire used, the foreign use of brass. 2, by specification of the working fluid, demonized water used abroad. 3, take the wire of the speed of 11 meters / second or so, abroad for 3 to 5 m / min. 4, we repeat the electrode wire is to use until the broken wire to the foreign is not reused after the walk. 5, our precision than in other countries.According to the electrode wire running at different speeds, and processing quality of different WEDM is usually divided into three categories: the first is to go wire speed WEDM (WEDM-HS), the electrode wire for high-speed reciprocating motion, generally take the wire speed of 8 ~ 10m / s, the electrode wire can be reused, the higher processing speed, rapid walking easily lead to the electrode wire and reverse wire jitter when the pause, the decline in the quality process is the production and use of the main machine species, but also our unique WEDM model; second is the low-speed WEDM wire walk (WEDM-LS), the electrode wire for low-speed one-way movement, generally take the wire speed is lower than 0.2m / s , no longer in use after discharge electrode wire, smooth, uniform, small jitter, processing, better quality, but the processing speed of lower production and use is the main foreign models. The third class to go wire-speed WEDM and accurately should be called "multi-speed to go wire." Is our original, and its principle is to cut the work piece repeatedly, beginning with fast speed wire tube, strong high-frequency to cut, as the current Fast thread cut, the last knife wire tube with a slower rate than weak high-frequency current to repair light, thereby enhancing the processing finish; and wire-speed reduction, the guide wheel and bearing less jitter, precision is also increased; In addition, the first knife to cut the fastest speed, then cutting and cutting the amount of light repair is very small, therefore, generally Mito time together cut the knife than the speed wire cut faster.Trajectory based on the control of the electrode wire in different forms, can be divided into three WEDM: one is an imitation of shape control, before cutting the conducting wire, pre-create the same shape as the die and the workpiece, the processing time rough and die while the workpiece clamping in the machine table, the electrode wire in the cutting process closely for the trajectory moves close to the edge mode, thereby cutting out the shape with the mold and precision parts to the same; the other is the optical tracking control, the conducting wire cutting before amplification under a certain percentage of part drawings depict an optical tracking map, the processing machine will be placed in optical pattern tracing stage, the stage of the optical head tracking tofollow the ink line graph is always trajectory, then by means of electrical, mechanical linkage, the control machine table with the workpiece relative to the movement of the electrode wire to do similar figures to cut out shapes with the same pattern to the workpiece; another one is the digital process control, advanced digital automatic control technology, the drive machine according to the geometric shape of the workpiece before processing parameters based on pre-programmed processing of the NC machining program automatically, without making look like board and need not draw Enlargement, two forms of control than the previous higher precision and wide range of applications, more than 95% at home and abroad WEDM have adopted CNC. Direct Digital Control (DNC) EDM wire cutting system can improve the level of automation, the overall productivity and responsiveness.2. WEDM Characteristics and ApplicationThe so-called EDM wire cutting, is to move forward to the filament (diameter of about 0.5mm or less) to make electrodes, the electrode wire and the spark discharge between the workpiece and simultaneously driven by the shape of the parts required for processing.2.1.WEDM characteristics:(1) it 0.03 ~ 0.35mm metal wire to the electrode tool, do not need to create a specific shape of the electrode.(2) Although the process is mainly flat shape of the object, but in addition to the decision of the inside of the wire diameter foot minimum diameter R (radius + wire discharge gap) such restrictions, no restrictions, no complicated at the beginning of all can be processed.(3) contouring less than the required processing can be effective in saving precious materials.(4) loss of wire can be ignored (using low-loss high-speed cutting away Siqie pulse power; slow walk for a continuous thread cutting one-way wire, always kept in the processing area Sijia new electrode), high precision(5) relies on a tiny computer-controlled electrode wire traces and space compensation, while both concave and convex mold processing, the gap can be adjusted.(6) by emulsion liquid or to the working fluid from the water, do not have to worry about fire, day and night, no one can be a continuous process.(7) cutting WEDM can be difficult to machine or can not be the traditional method for processing high hardness, high strength, high brittleness, high-Ren Xing and other conductive materials and semiconductor materials.(8) at the beginning of any complex parts, as long as the preparation of processing can be processed, and thus very suitable for small batch production of parts and test products, processing, short processing cycle, application flexibility.(9) with four simultaneous axes, can be processed, the following special-shaped body, the shape distortion of the body surface, such as variable taper and spherical parts.(10) process, the tools are not in direct contact with the workpiece, there isno significant cutting force, enabling processing of low-rigidity workpiece. (11) and EDM as compared to the wire electrode instead of forming the electrode, eliminating the molding tool design and manufacturing costs electrode Used to shorten the production lead time.WEDM the disadvantage of low productivity, and can not be blind hole machining parts and ladder surfaces.2.2.WEDM applications:(1) The trial of new products: new product development process requires a single piece samples, use of wire cutting parts cut out directly, without molds, which can greatly shorten the development cycle of new products and reduce trial costs. Such as stamping, the die is not expected to open Chula, first with a wire cutting for forming such a model for subsequent processing, be verified before blanking die manufacturing.(2) processing of special materials: cutting some of the high hardness, high melting point metal, the use of machine processing methods is almost impossible, and economical use of line cutting can ensure accuracy.(3) processing mold parts: mainly used in EDM wire cutting dies, extrusion dies, plastic dies, EDM electrodes cavity mold processing, the EDM wire cutting speed and accuracy of the rapid increase has reached can compete with the coordinates of the degree of grinding. For example, the small die, the material is tool steel, in the past with a separate mold and method of curve grinding machining, EDM wire cutting now switch to the overall processing methods, manufacturing cycle can be shortened 3 / 4 to 5 / 4, reduce the cost of 2 / 3 / 4, with high precision, the work does not require skilled operators. Therefore, some industrial countries such as precision grinding washed process has been EDM and WEDM replaced.2.3.WEDM application areas:WEDM is mainly used for a variety of dies, plastic molds, powder metallurgy molds composed of two-dimensional and three-dimensional ruled surface of the mold and parts. Can cut a variety of templates, magnets, silicon steel, semiconductor materials or precious metals, but also for micro-machining, shaped slot and the standard specimen processing defects. Widely used in electronic equipment, precision machine tools, light industrial, military and so on.(1) plane shape of the metal mold processing: die, powder metallurgy mold, drawing die, extrusion die machining(2) three-dimensional shape of the metal mold processing: Die by the withdrawal of the die groove machining, plastic with metal dies, plastic mold separation surface processing(3) EDM: production of complex shapes using micro-electrodes the electrode process, the general processing of perforated electrode, the electrode process with taper mold(4) test products and parts processing: prototype parts directly to processing, batch processing of small variety of parts, special materials, spare parts processing, materials, processing of specimens(5) profile gauge processing: measuring a variety of card board processing, the cam and the template processing, shape forming car(6) micro-processing: Processing of chemical fiber nozzle, shaped slot and narrow channel processing, standard processing defects3. WEDM technology statusCurrently, the cutting speed WEDM has been widespread over the past 20 ~ 40mm2/min increased to 100mm2/min above, and some can reach 260mm2/min, machining accuracy is ± 0.01mm, the surface roughness of the workpiece Ra1.25 ~ 2.5μm, which can meet the general mold machining and other complex parts manufacturing requirements. With the development of science and technology, the manufacture of various products have become increasingly demanding of wire cutting technology has also put forward higher requirements. Abroad (Europe, America, Japan, etc.) to go low-speed research and development of CNC wire electric discharge machines to meet the requirements of the manufacturing process technology, the use of closed-loop digital delivery (straight) flow servo control system to ensure excellent dynamic performance and high positioning accuracy, precision can be controlled in a number of microns or less. At the same time with a digital adaptive control of power tools, automatic wear silk, automatic removable waste, short-circuit automatic rollback and other automated techniques, in addition to the electrode wire tension and the working fluid pressure can be controlled. Due to the use of new technology and focus on updating the computer software technology and development of low-speed wire cutting away the process indicators have reached a very high level. Even if the machining of complex shape, the maximum cutting speed of more than 300mm2/min; size precision can reach ±2 ~ 5μm; surface roughness can be achieved Ra0.1 ~ 0.2μm (multiple cutting). High degree of automation of machine tools, processing stability, has been the development of unmanned machining.3.1.WEDM technology trends:WEDM due to loss of electrode wire, and precision mechanical parts of the structure, into the open-loop control to the system, processing of changes in working fluid conductivity, temperature processing environment and its own processing characteristics (such as wire speed operation fast, more vibration source, guide wheel wear large) and other factors, machining accuracy is limited. The current status of the machine, to a relatively short time and low-speed wire EDM to go to compete in the processing precision, the difficulty is quite large, and research and development costs will be high, the machine will significantly increase manufacturing costs From the perspective of reality and the market are not considered appropriate. Therefore, the development strategy WEDM weaknesses, to develop middle and low machine-based, so that the machine to the appropriate precision, good stability and easy processing direction, to meet growing production needs. Currently on the market high-speed wire cutting away the biggest advantage is to have a good cost performance, the machine must take this as further development of the basic starting point, not too much emphasis on precision machining, and overlook the factors that costperformance machine. In contravention of this principle, machine manufacturers and users are difficult to accept. In the short period of time, so that the processing performance of WEDM have greatly improved. WEDM to further development, we must get rid of SBC as a numerical control system, the use of new NC system. At present, there go the high-speed PC-based CNC wire cutting machine, but its main function is processing path programming, machine tool control is far from perfect, there is no full use of PC resources. In the use of new technologies, new processes must also attach importance to the law of WEDM process based on thorough and detailed theoretical and experimental research, this is a very important part.4. ConclusionAt present, artificial intelligence technology has started in the WEDM in the research, however, the depth and breadth of research is still not enough. There are many aspects to be studied further:(1) of the Servo WEDM inverter control has to rely on the operator, so the operating staff strength, machine performance of the play is limited. Artificial intelligence fuzzy control technology is an important aspect of technology, it can imitate the skilled control of machine tools, EDM machine has been successfully applied in EDM wire cutting has a good prospect.(2) concluded over the years to go wire cutting high-speed processing results, the establishment of appropriate knowledge base and expert systems, reducing the difficulty of the operation of machine tools is essential.(3) adaptive processing parameters, etc. can make a difference.The latest artificial intelligence technology into the development of WEDM, the development of high-speed wire cutting away parts of the intelligent control and enforcement agencies, which is the current national development priorities are consistent with high-tech industry, has important practical significance.电火花线切割技术摘要：随着机械制造业水平的不断提高和产品加工精度的需要，先进的机械制造技术的应用也就顺理成章。