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Carbide wire drawing die EDM processing
If the cemented carbide raw material is not sintered, then it is needed To punch the hole in the center of the cavity with a spark punching machine. CNC wire cutting processing: 1. Cut the die, The die section of the die section is determined by drawing the final section Size, so very critical, such as the direct use of EDM molding processing, it is difficult to guarantee the degree of light. To this end, we are in the tip of the NC line cutting machine cut off the shape of the shape of the section (straight wall), which not only effectively guarantee the quality, but also for the subsequent molding process to remove the halo, creating a working fluid cycle Good condition. Cutting the cavity at the same time, according to the location shown in Figure 2, in the prestressed pressure on the circle cut out two positioning holes.
2. Cut the board Grinding the two sides of the sheet metal, as shown in Figure 3 cut out three internal shape, the middle of the internal cavity with the electrode shape with a single gap 0.015 mm, both sides of the hole diameter and location, should be consistent with the stalk.
3, EDM molding processing There are three cones on the die and an orifice Spark molding process, we put on the DM5440 machine. As the hard alloy melting point is high, so no matter what kind of electrode selection Materials, the loss is very serious, to copper electrode, for example, in the same specification, the processing of carbide loss is "rocessing ordinary steel about 15 times, so the use of single electrode Flat method "is not appropriate, for processing carbide cavity, the" multi-electrode processing method "is better.
1. Design and manufacture of electrodes We have done a number of tests, the results show that: copper and cast iron for the electrode were processed carbide, in the phase processing, their loss rate difference is not much, but the copper machine with poor performance, and the price is also expensive , So the rough plus a bit of the electrode or cast iron as well. Taking into account the convenience of electrode manufacturing, so the four different internal shape is the use of four electrodes were processed. Lubrication section and working section of the erosion of the day is very large, each with 5-6 phase electrode, and the entrance section and the outlet section of the erosion is much smaller, so there are 2-3 thick electrode is enough to finish Of the electrode, each with only one, the material used to buy the loss of performance is particularly good copper fence alloy (Cu-W80). The rough bite of the coarse electrode is preferably designed so that it can share a blank The general process of manufacturing is: milling - inch square shape - leaf if the instrument can be processed in the tool curve grinding, the more ideal. The straight wall shape and tapered surface (or concave R) 'of each electrode should be machined once to ensure that they are concentric and co-ordinated with each other.
2. Electrode and work repeated positioning Although the small end of the tapered electrode can go into the well of the cavity, with weak regulation in the cavity around the uniform spark, as the basis for positioning, but because the electrode to be replaced more than 10 times, so this " Spark positioning method, "the error will be greater than once, resulting in a serious dislocation of each section of the shape, practical description of the" board positioning method "is better. With the positioning pin to set the plate and die fixed, and put a suitable horn between them, move the hangar workstations, so that the electrode can be sliding in the plate-like holes through the pass, so that the cut The precise positioning between the inner shape and the electrode, so that the empty board, that can be carried out EDM.
3. Roughing to erode the working margin as the main objective, in order to achieve the highest possible productivity, we chose a strong specification: pulse width 512 microseconds, processing current 5 ampere. Of course, when the cast iron electrode loss of more than 2.0%, therefore, the need for frequent replacement of the electrode. Coarse T generally only stay 0.1-0.2 mm of finishing capacity.
4. Nondestructive testing Carbide is a heat-sensitive material, the thermal conductivity is small, in the case of strong control Huai processing, often produce mesh cracks, which greatly affect the life of the mold. Therefore, after roughing, a non-destructive testing is beneficial, or once the finishing all completed, and roughing the cracks can not be removed, the mold can only be scrapped, the loss is greater.
5. Finishing, Mainly in order to ensure the accuracy of the cavity and improve the surface finish, to achieve this goal, can only use weak standard processing, that is, narrow pulse, small current. At this time not to test the production efficiency, so the time spent finishing quite long. We choose the pulse width of 16 microseconds, processing current 0.5A, processing results: electrode wear less 3%, the surface light up to 7 strong.
6. Working fluid circulation Good chip removal is an important condition to ensure stable processing. So in the processing used from the bottom of the concave red, pumping alternating method. Practice shows that the stability of the processing of carbide is significantly superior to ordinary steel, so it can reduce the red, pumping pressure to improve the erosion rate. This is a total of 40 hours (including rough, finishing). From the production efficiency, it is not satisfactory. We believe that there are two ways to solve: (1) Carbide core in the sintering, it is best to put the paragraphs directly into the shape, leaving only less processing brother, which will undoubtedly greatly shorten the electrical processing time. (2) the EDM machine tool height of the hatred from 173 V to 300 volts, then the processing of carbide corrosion rate and electrode damage assessment estimates will be greatly improved, kidney, this Need to make some necessary improvements to the machine. Force, distance, angle, feed rate, projectile flow and projectile diameter Nozzle number and nozzle number (3) the use of the record to the number, in order to spray the same way the same parts shot pincers. (4) In order to ensure the consistency of the pills, it is necessary to test the parts at the end of the shot peening, and verify whether the arc values produced by the three pieces of the parts are within the scope of the drawings. In the range of qualified products; otherwise for nonconforming products, allowing re-spray once to achieve the requirements of shot peening strength.
Conclusion 1. I plant fatigue comparison test confirmed that the intensity of foreign recommended reliability is higher, consistent with the actual production drawings, can be applied. 2. From the fatigue comparison test can be seen: shot peening effect increases with the thickness of the parts, that is, smaller parts of the shot peening effect is obvious; the same time, with the increase in the thickness of the shot peening strength should be increased accordingly. 3. At present, most of the domestic shot peening parts, are generally repeated use of the field and used. And into the fatigue design rules Fan products less, in order to improve product fatigue life and anti-stress corrosion performance, should be used to strengthen the shot peening, according to foreign recommendations I plant test shot peening strength shot peening on the smaller cross-section of the different parts, you can use A special cold extrusion - drawing profile approach to the system, that is, the embryo from the cavity in the strong pull out, through the plastic deformation of the material to achieve a certain geometric shape and size requirements, which is a high efficiency , High quality, no chip ideal processing methods.
A complete set of technology for electrolytic grinding of tungsten carbide cold rollers
With the continuous development of China's 45 ° wire mill, the key to the rolling mill supporting equipment tungsten carbide cold roller electric processing technology research is very urgent. Carbide Roller Electric Machining Technology Research, Research on EDM Grinding Metal Bonded Diamond Grinding Machine Tool and Process, and Machine Tool and Process for Electrolytic Grinding of Cemented Carbide by Metal Bonded Diamond Wheel The results show that the forming precision of the diamond alloy grinding wheel of the metal bonding agent can reach 0.015 mm after grinding and grinding. The forming precision of the alloy grinding wheel with the metal alloy diamond grinding wheel is 1 ),0.2mm.
First, hard alloy rolling bar electrolytic molding grinder The machine uses the forming diamond grinding wheel to carry on the electrolytic molding grinding to the cemented carbide roll. Between the grinding wheel of the machine tool and the spindle of the grinding wheel, the tailstock sleeve and the top of the tailstock are insulated. The main shaft of the head frame drives the workpiece (carbide bar) to rotate. And drive the spindle to drive the motor has two, one is the AC motor, through the three-belt deceleration, the spindle speed of 35 r / min. One is the stepper motor through a pair of gears and beyond the clutch, connected to the AC motor drive the latter two belt drive, so that the spindle rotation according to the situation when the electrolytic grinding can be o.oos-1 r / min manual stepless speed. There is also insulation between the spindle and the top.
Process tests show that the machine is basically able to meet the requirements of roll electrolytic molding grinding. The precision of the grinding wheel of the machine is improved by 0.02 mm, the position accuracy of the groove is 0.01 mm and the finish is VB-9. The wire size error of the cold rolled iron bar was 0.4-0.5 mm, while the wire size error of the tungsten carbide cold roller/ was 0.1-0.2 mm.
Third, the diamond grinding wheel EDM grinding machine The machine is formed by the use of graphite grinding wheel on the diamond grinding wheel EDM grinding. The grinding wheel frame of the machine is equipped with a vertical horizontal AC motor. The vertical motor is decelerated to the grinding wheel spindle by a pair of worm gears and a belt. The grinding wheel is rotated at 10 revolutions per minute. The horizontal motor passes through a belt Deceleration and beyond the clutch, driven wheel spindle, the grinding wheel speed of 573 r / min.
Notice of the Ministry of Industry and Information Technology of China on the Control of Tungsten Production in 2017
The relevant provinces, autonomous regions and industrial and information authorities:
I Ministry of relevant departments to determine the 2017 total production of tungsten control indicators, is now issued to you, please follow the requirements of organization and implementation:
First, tungsten is the country to implement the total production control and management of products, any business shall not be indicators and super-standard production. The provincial industrial authorities shall promptly release the indicators issued by our department (see Annex 1) to the production enterprises, the distribution of indicators shall not be decentralized, shall not increase the additional indicators.
Second, the total production control indicators should be issued to meet the national tungsten industry policy and industry planning requirements, with mining permits enterprises, indicators to meet the environmental protection requirements, advanced technology and equipment, high level of key enterprises tilt enterprises. On the ultra-standard production and the existence of environmental pollution, security risks of enterprises to be cut until the abolition of indicators.
Third, the relevant provinces (autonomous regions) industrial authorities issued indicators, should do a good job with the local land and resources authorities in charge of the timely implementation of the indicators to the enterprise, and develop a monthly plan.
Fourth, local industrial authorities should gradually implement the industry management responsibility, conscientiously implement the relevant provisions of the document, the monthly implementation of the program to check. No indicators, ultra-target production enterprises, to immediately order to stop production, illegal acquisition and sales of enterprises shall be punished according to law.
Fifth, local industrial authorities to implement the person responsible for the production of tungsten concentrate production statistics, monthly statistics report on the implementation of production indicators. According to the statistical report (see Annex 2) requested on the 10th of each month (holiday extension) before the report last month production situation.
Please the relevant provinces (autonomous regions) industrial authorities to do a good job of tungsten production control indicators of the total management, timely report of the problems encountered in the work, and in June 30, 2017 before the decomposition and implementation of the situation reported to me for the record.
Nano-Cemented Carbide EL ID Grinding
An experiment was conducted to study the grinding p roperty of nano2metric cemented carbide by means of EL ID grind2 ing. The difference in grinding p roperty was compared between nano2metric cemented carbide and common cemented car2 bide. Effects of p rocessing parameters, such as grinding dep th and workp iece feed rate, on grinding p roperty were ana2 lyzed. Results imp ly that, under the same conditions, grinding force and surface quality of nano2metric cemented2carbide are higher than those of common cemented carbide.
Key words: Nano materials; Cemented carbide; Grinding force; Surface quality; Grinding
Nano-material refers to the grain size in the nano-level (1 ~ 100 nm) of the material, due to the grain size of the nano-material, the material surface of the electronic structure and crystal structure has changed accordingly, a large number of atoms in the grain between the sub Steady state interface. Therefore, compared with conventional grain size materials, nanomaterials exhibit many excellent physical and chemical properties in terms of mechanical, optical, thermal and catalytic properties. The microstructures of nanomaterials have nanoscale scale (including grain size, grain boundary width, second phase distribution, pore size, defect size and so on). . Grain refinement, the effect of size effect, can increase the grain boundary area, Improve its anti-crack expansion resistance, so as to obtain some excellent mechanical properties. The excellent performance of nanomaterials makes it a wide application prospect, and the research on the processing characteristics of its application field is becoming more and more important.
Nano - cemented carbide is a kind of nano - materials, generally in WC - Co cemented carbide, with the hard phase of the WC content increased and grain refinement, the hardness gradually increased; and fracture toughness Increase in the content of Co phase Co increased . In general, the hardness and fracture toughness changes in the opposite trend, that is, to obtain high hardness will have to sacrifice fracture toughness at the expense of . But after the grain refinement reaches nanometer level, the hardness and fracture toughness are improved at the same time, to achieve the perfect combination of hardness and toughness , is expected to obtain the ideal both high hardness and reasonable fracture toughness of the new tool material The Compared with the traditional hard alloy, nano-carbide has a high hardness, toughness, bending strength and excellent wear resistance. Its small grain size for the production of cutting tools can be sharpened extremely high precision, sharp cutting edge and very small radius of the nose; because of its high strength, can be used to make large rake angle, small feed and snacks The use of high-precision molds, punch, etc., such as the production of printed circuit board drilling micro-bit, wood processing industry's milling cutter, the printer's print pin, As well as precision molds, special tools, dental drill, difficult to process materials, such as tools. Based on the above points, it can be considered that the application prospect of nanocomposite is very broad. At present, the research on the preparation of nano-cemented carbide materials is more, and the research on nano-cemented carbide processing technology is less, therefore, nano-carbide processing technology research has become increasingly important. The grinding performance of nano-cemented carbide was studied, and the feasibility of processing nano-cemented carbide by EL ID grinding technology was verified. Some experiments were done mainly from the following two aspects: (1) The nano-cemented carbide The grinding characteristics of the grinding process were studied and compared with ordinary cemented carbide. The influence of the grinding amount on the grinding characteristics was analyzed. (2) The ultra-precision grinding of nano-cemented carbide was studied by AFM atomic force microscopy The microstructure and surface quality of the surface were analyzed under the same experimental conditions.
1 Nano Carbide EL ID Grinding experiment: EL ID grinding technology with wide adaptability, wide range of materials to adapt, high grinding efficiency, simple device features , I use diamond grinding wheel on-line electrolysis (EL ID) grinding The experimental study on the precision grinding of nano-cemented carbide was carried out.
1.1 Experimental apparatus and equipment: Laboratory equipment: FS420 horizontal grinder manufactured by G & H GmbH, W40 iron base diamond grinding wheel, specification 200 mm (diameter) × 10 mm (thickness), EL ID grinding power supply for HDMD - 3 Type high frequency DC - pulsed power supply, self-developed electrolytic grinding fluid. Detection equipment: KISTLER dynamometer. Electrolysis process parameters: voltage 120 V, current 2 ~ 5 A, pulse width 20μs, pulse interval 20μs, pre-electrolysis time 15 m in. The size of nanometer powder used in the preparation of nano - cemented carbide was about 45 nm, and the grain size was about 200 nm after sintering. Selection of ingredients close to the ordinary carbide YG8 as a comparative material, grain size of about 5μm
1.2 nano-carbide grinding experiments: grinding force from the workpiece and the wheel between the elastic-plastic deformation, cutting deformation, as well as abrasive and the friction between the workpiece. Grinding force and grinding wheel wear, grinding process system deformation, grinding wheel contact with the workpiece and the final formation of the surface quality are closely related . In this paper, the grinding force and grinding depth, grinding force and table feed of the nano-cemented carbide EL ID grinding were studied by comparing the grinding force under different grinding conditions with W40 iron-based diamond grinding wheel The relationship of speed. The force measuring device used in the experiment is shown in Fig. The nanocomposite specimens were bonded to a flat plate and fixed to a KISTLER dynamometer. The dynamometer is sucked on the magnetic chuck of the grinder. The transverse feed is used to lock the longitudinal feed and the longitudinal feed cut method is used to reverse the test specimen. The dynamometer is used to amplify the force signal and then enter the computer by A / D conversion deal with. Analysis of the data obtained after the grinding force of the measured value.
1.2.1 workpiece feed rate on the grinding force: When the grinding depth is constant, only change the table feed speed VW, measured grinding force as shown in Table 2, the grinding conditions for the wheel speed VS = 2 500 r / min, grinding depth ap = 0. 03 mm. With the increase of feed rate VW, the grinding force of nanocomposite and ordinary cemented carbide increases, and the grinding force is nonlinear with the change of feed rate. This is because when the feed rate VW increases, the cutting thickness of each abrasive grain increases, so that the grinding force increases. The grinding force of nano-cemented carbide varies greatly with the feed rate VW, while the grinding force of ordinary cemented carbide is gentle with the change of feedrate VW. At the same feed rate, the grinding force of nano-cemented carbide To be greater than the ordinary carbide grinding force. From the picture can also be seen in the table speed is high, the nano-cemented carbide normal grinding force than ordinary carbide about 0. 5 times, tangential grinding force higher than 0.6 times about.
1.2.2 Cutting depth on the grinding force: When the table feed rate is constant, only change the grinding depth ap, measured The resulting grinding force is shown in Table 3. Grinding conditions: grinding wheel speed VS = 2 500 r / min, the table feed speed Vw = 7. 2 m / min in. It can be seen from Table 3 that the grinding force increases with the increase of the grinding depth, because the grinding depth ap increases, the contact arc length increases, and the total number of effective abrasive grains participating in the cutting increases, The grinding thickness increases, and the grinding depth increases with the grinding depth increasing, and the grinding depth has the most significant effect on the grinding force. At the same grinding depth, the grinding force of nanocomposites is higher than that of ordinary cemented carbide, which is due to the small grain size, compact structure, hardness and high strength of nanocomposites. As can be seen from Table 3, nano-cemented carbide grinding force than ordinary carbide to 0. 2 to 0.5 times higher.
2 Nano Carbide EL ID Grinding Surface Quality: EL ID precision grinding with W10, W1 iron-based diamond grinding wheel and measurement and microscopic analysis using atomic force microscopy (AFM). Figure 2a shows the grinding surface of ordinary cemented carbide. It can be seen that there are some plastic scratches on the surface, some of which are not continuous, showing brittle fracture characteristics, which affect the surface quality and the measured surface roughness Ra = 20. 972 nm. Figure 3a shows the grinding surface of nano-cemented carbide. Compared with Fig. 2a, it can be seen that the grinding scratches on the surface of nano-cemented carbide are clear, uniform and neatly arranged as plastic cutting traces. Atomic force microscopy, The surface roughness of the alloy Ra = 1.986 nm, to achieve a mirror grinding. This shows that the EL ID grinding process is suitable for grinding nano-cemented carbide, at the same time, because the nano-cemented carbide grain small, dense organization, high fracture toughness, easier to achieve plastic cutting, so get a better surface quality.
3 Conclusion: The grinding performance of nano-cemented carbide was studied by ELID grinding technology. The grinding performance of nanocomposite was compared with that of ordinary cemented carbide. The following conclusions can be drawn from the following conclusions: Conditions, nano-carbide grinding force is higher than ordinary carbide grinding force. When the feed speed of the table changes, the grinding force increases with the increase of the feed rate. When the feed rate is high, the grinding force of the nanocomposite is 0. 6 times higher than that of the ordinary cemented carbide about. When the grinding depth changes, the grinding force increases with the increase of the grinding depth, and the grinding force of the nanocomposite is 1.2 ~ 0.5 times higher than that of the ordinary cemented carbide. The results show that under the same grinding condition, the nanocomposite is better than ordinary cemented carbide because of its compact material and better performance. It is easier to realize plastic grinding. The surface quality of the cemented carbide is obviously better than that of ordinary cemented carbide. The Ra value of the nanocomposite was 1.986 nm by atomic force microscopy (AFM) under the condition of using W1 iron-based diamond grinding wheel. EL ID grinding technology is suitable for grinding nano-cemented carbide, can get better surface quality.