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1、消失模铸造存在的技术问题（Technical problems in EPC Process）Problems in lost foam casting / Countermeasures2009-3-25 23:15:00EPC process and products with good appearance quality, high precision, low labor intensity and good working environment in China foundry industry has been used well, especially in recent y
2、ears, domestic manufacturers and technical personnel continue to develop in the raw materials and process equipment, the process of the basic realization of localization, and further promote the EPC Process, the development of technology.The name and type of casting or EPC casting, intuitively namel
3、y: foam model embedded in dry sand vacuum formed casting iron liquid injection, of course to good use of this technology to produce excellent products, should also be good to handle the following problems.Study on forming principle of cut and lost foam casting1. basic requirements for forming of EPC
4、 in dry sandPyrolysis characteristics of 2. foam model3., dry sand, lost foam casting, molding sand filling and compaction characteristics4. filling and replacement of liquid metal by dry sand lost foam casting5. dry sand; lost foam casting; casting; solidification characteristics6. cooling characte
5、ristics of foundry castings with dry sand and their effects on microstructure, properties and residual stresses of cast ironTwo. Development of common technology for EPC process of dry sand1. design and manufacturing technology of foam mould for EPC(1) the function, requirement and manufacturing pro
6、cess of foaming mould;(2) design of foam model (block)(3) design of foaming mould (mould type, module number, module parting surface, structure design, cavity design, vent hole, feeding port, die making mechanism, positioning)(4) foam mold processing;(5) die assembly adjustment;(6) test die for foam
7、ing mould;(7) the rapid manufacture of foaming mould2. manufacturing technology of EPC foam plastics model(1) model properties and selection of raw materials(2) foaming technology(3) curing technology(4) die forming technology;3. coating and coating requirements and basic composition(1) requirements
8、 and basic composition of EPC coating(2) model brushing method;(3) coating drying;4. micro vibration molding technology(1) the requirement of EPC for dry sand molding;(2) modeling key equipment and tooling - vibration table and sand box(3) molding process parameters5. negative pressure casting techn
9、ology(1) technical requirements for pouring;(2) development of vacuum system(3) negative pressure casting process parametersThree 、 lost foam casting raw and auxiliary materials1. foam model raw material - expandable resin beads(1) the requirement of model material for EPC(2) the structure and prope
10、rties of the expandable resin(3) domestic varieties of resin beads2. model adhesive adhesive material3. model surface patches4, the choice of commercial coatings5. molding sandFour, dry sand disappeared Hou casting equipment and workshop designA complete set of expendable pattern casting equipment h
11、as been developed, with specialized suppliers(1) die making equipment - hair generator and molding machine(2) model bond machine;(3) coating and coating preparation equipment(4) molding equipment - various vibrating and sand adding devices(5) sand falling equipment - all kinds of dumping and sanding
12、 devices(6) sand treatment equipment - sand screening, cooling equipment and molding sand conveying equipment(7) negative pressure pouring equipment(8) environmental protection equipment - dust removal system equipment, pouring tail gas purification deviceFive, process levelMinimum weight 0.2kg, max
13、imum weight 500kg, minimum wall thickness 3.5mm, minimum hole Phi 8, dimensional accuracy OBCT8, weight accuracy GBCT8, surface roughness Ral2.5 mu m, machining allowance 2 - SMMSix. Analysis of casting defects of dry sand lost foam castingOneIn this paper, the casting defects of dry sand lost foam
14、casting are comprehensively analyzed. The four categories, fourteen kinds of casting defects, characteristics, causes, influencing factors and preventive measures are expounded.2. the study of carbon defects peculiar to EPC has accumulated some experience in the prevention of deformation, sand, poro
15、sity and inclusions.3. model quality, coating quality, molding process and pouring process and quality of casting, and influence processDegree.Seven. Application of EPC1. types of casting alloys used:Aluminum alloy, special cast iron (high chromium cast iron, etc.), grey iron, nodular cast iron, spe
16、cial cast steel (high Mn steel, Ni Cr and hot steel), plain carbon steel, low C steel and stainless steel2. typical castings with success:(1) antifriction castings - grinding ball, lining board, hammer head(2) and heat - casting grate, heat treatment, floor frame etc.(3) pipe fittings - grey, ductil
17、e iron fittings of various specifications (phi 25 - 1200)(4) valve castings - cast steel valve body, valve cover, nodular iron valve body, valve cover(5) construction machinery parts - bucket teeth, gears, rack, forklift steel castings(6) box (shell) casting - transmission case, differential case, s
18、teering housing, motor housing, fire hydrant housing, shell shells, etc.(7) automobile brake system castings - brake drum, brake disc;(8) crankshaft - compressor crankshaft, automobile engine crankshaft;(9) inlet and exhaust pipes, aluminum intake manifold, ductile iron 4 cylinder automobile exhaust
19、 pipe, iron 6 cylinder diesel engine exhaust pipe(10) bracket casting - Railway 25 steel support plate, automobile spring support, etc.(11) rear axle castings - cast steel, ductile iron, rear axle housing;(12) cylinder block, cylinder head casting - compressor cylinder block, single cylinder engine
20、block, cylinder head, automobile 4 cylinder blockEight, the development of lost foam casting problems and CountermeasuresQuestion:1., many manufacturers of EPC, normal and stable production is not much.According to incomplete statistics, from around the beginning of 90s, around 200 manufacturers who
21、 introduced the lost metal casting process at different levels could still maintain normal production up to now, with an estimate not exceeding 30%o2., EPC foundry production scale is small, more than 90% manufacturers actual annual output of less than 1000T, black castOne, the actual annual output
22、reached 5000T / year manufacturers almost have no, most of them disappeared design scale die casting factory, equipment supporting capacity is small, there is a part of EPC casting plant design capacity may yield is very high, but due to various reasons can not reach production.3., some manufacturer
23、s lost foam casting quality is not up, casting finished product rate is low, failed to show the progress of this process, seriously affecting the market competitiveness of this new process.4., Chinas lost foam casting factory production of lower grade, for difficult castings (such as cylinder block,
24、 cylinder head, etc.), we can not produce a large number of stable production.5. imported key equipment, supporting domestic EPC casting factory, a large amount of investment (50 million yuan / 5000T), raw materials depend on foreign, the localization process is slow, can make a very good sample, bu
25、t not on the scale of production to cost down, lose the competitive ability.6. a small factory, the EPC equipment is too simple, the workshop dust, than the traditional sand casting working conditions are poor, serious environmental pollution problems, dust and other harmful gases, losing the green
26、casting reputation.Reason：Some manufacturers have introduced the L. casting process is not careful, EPC is not scientific enough, the lack of in-depth understanding of the target product, EPC is not clear or lack of the technical feasibility and economic rationality to fully demonstrate the lack of
27、professional personnel; complete the feasibility report, the project in a hurry.2., the business leaders have high expectations of the new process, the transfer unit blowing too much, and there is not enough technical personnel to digest the process,Basically brought on by burn out the sample, but n
28、ot stable production, so the introduction of this technology manufacturers, must have a thorough understanding of several specialized technical personnel, to master this technology, and technology accumulation in practice, this work requires a process, technology is the key technology Kung Fu, need
29、long-term accumulation. And this process is not omnipotent, it has its limitations.Most of the 3. manufacturers of EPC casting process is very rough, seemingly simple EPC casting, the actual process control has greatly increased, we basically also beginning to wear a simple approach to more complex
30、casting mold, pouring system has no commission rough, strict procedure.4., the lack of strict quality assurance system, the lack of strict process management.5., our process has accumulated little, nor is it stable enough.6. raw and auxiliary material quality is not poor, but also not stable enough.
31、7., the level of the transfer unit is not high, the production units in favor of the impact.8., the reasons for the market, some units, as a result of fierce changes in the market caused by production, new product development capacity to control the speed of production.9. reasons for financial resou
32、rces.Countermeasure:1. units have not yet started, should strictly set up procedures, scientific analysis, not easily launched, before launching, must be based on product markets, production conditions, talent status and financial feasibility analysis. And to conduct nationwide research and select r
33、eliable technical support units or partners. Then leading product advanced process test and workshop overall design, determine purchase equipment details and self-made equipment detail. Organize the construction, equipment installation, debugging and personnel training, and finally try production, a
34、cceptance, not anxious, but should be methodical.2. has been set up factories, for strong technology ability, complete production conditions, should be the main focus of summing up in the market development and process, improve the rate of finished products, reduce product cost, the conditions shoul
35、d also improve the level of product, to enter the international market.3., a considerable part of EPC factory product quality is low, the benefits are not good, should be carried out in a comprehensive manner, quickly change the face, to accelerate investment in return.(1) the implementation of tota
36、l quality management, starting from raw materials, process steps should be established strict quality management system.(2) establish process operation procedures for each process.(3) complete with the necessary production equipment and environmental protection equipment.(4) conscientiously summing
37、up experiences and lessons.4., to strengthen exchanges (meetings, materials, magazines, Internet access, etc.), in the country to train a group of experts to guide the production of lost foam casting, training (training courses, internships, etc.) a large number of lost foam casting workers backbone
38、.5. improve the professional level, in the country of different parts, establish model of several large-scale production workshop, for example, a large number of production: pipe fittings, wear resistant parts, grate heat-resistant parts, exhaust pipe, box, cylinder etc.6., to improve the socializat
39、ion and establish regional central factories, such as the establishment of public mold factories, and give full play to equipment potentialPower。7., improve the scale and quality of supporting factories, establish stable raw and auxiliary materials and supply base of equipment.8., improve the technical support units (universities, hospitals, Technology Development Company, etc.) quality, level and scale.