材料成型及控制工程专业毕业设计(论文)外文翻译

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材料成型及控制工程专业英语

材料成型及控制工程专业英语Mechanical property机械性能austenitic奥氏体的martensite 马氏体Plastic deformation塑性变形stress concentrator应力集中点bar棒材beam线材sheet板材ductile可延展的stress relief应力松弛austenitie奥氏体 martensite马氏体normalize正火temper回火anneal正火harden淬火close-die forging模锻deformation rate变形速度diffusion扩散overheat过热Work hardening加工硬化dislocation density位错密度die模具residual strain残留应变as-forged锻造的injection mold注射模molding shop成型车间clamping force合模力grind磨削drop stamping锤上模锻nickel-base superalloy镍基合金insulation 隔热burr毛刺injection capacity注射容量deterioration变化、退化discrete不连续的abrasive磨损welding焊接metallurgical 冶金的Formation of austenite奥氏体转变The transformation of pearlite（珠光体）into austenite can only take place at the equilibrium critical point（临界温度）a very slow heating as follows from the Fe-C constitutional diagram（状态图）. under common conditions, the transformation is retarded and results in overheating,i.e.occurs at temperatures slightly higher than those indicated in the Fe-C diagram.The end of the transformation iS characterized by the formation of austenite and the dis—appearance of pearlite(ferrite+cementite)．This austenite is however inhomogeneous even in the volume of a single grain．In places earlier occupied by lamellae（层片）(or grains)of a pearlitic cementite，the content of carbon is greater than in places of ferritic lamellae．This is why the austenite just formed is inhomogeneous.In order to obtain homogeneous （均匀的）austenite，it is essential on heating not only to pass through the point of the end of pearlite to austenite transformation，but also to overheat the steel above that point and to allow a holding time to complete the diffusion（扩散） processes in aus-tenitie grains．为了获得均匀的奥氏体，在加热过程中通过珠光体的结束点向奥氏体转变是必要的，而且对过热刚以上的点，允许持续一定时间来完成奥氏体晶粒的扩撒过程。

材料成型与控制工程专业设计外文文献翻译固态微孔丙烯腈丁二烯苯乙烯泡沫塑料本科毕业论文

毕业设计外文文献译文及原文学生：学号：院（系）：机电工程学院专业：材料成型与控制工程指导教师：2011 年 6 月 8 日Solid-State Microcellular Acrylonitrile-Butadiene-Styrene FoamsSUMMARYMicrocellular ABS foams are a novel familv of materials with the potential to significantly reduce material costs in a number of applications that currently use solid polymer. ABS foams were produced using carbon dioxide in a solid-state process. Solubility and diffusivity of C02 in ABS was measured, and the latter was found to depend significantly on the gas concentration. The useful range of process-space for ABS-CO2 was characterized. Closed cell ABS foams were produced with densities ranging from 1.03 g/cm3 (almost completely solid) to 0.09g/cm3.It was determined that there are many different processing conditions that can produce microcellular ABS foams that have the same density. The cell nucleation density was of the order of 10 cells per cm3, and the average cell sizes observed ranged from 0.5 um to 5.6 um.INTRODUCTIONABS (Acrylonitrile-butadiene-styrene) has grown to become one of the most widely used thermoplastic in the world because of the wide range of available properties. ease of processing, and a good balance between price and performance. ABS is an amorphous copolymer alloy, with acrylonitrile bringing chemical resistance and heat stability, butadiene bringing toughness, and styrene providing good processing characteristics.These qualities provide an excellent engineering thermoplastic that is used for a wide range of products, including computer housings, automotive interiors, appliances, and building materials. In many applications, the solid ABS can be replaced by relatively high density microcellular foams, since the properties of solid ABS are not fully utilized. Currently, the only process than can produce foams suitable for thin cross-sections is the solid-state microcellular process originally developed at MIT as a way to produce high strength polymer foams which can reduce the amount of material used in manufactured products.This process produces foams with a very large number of very small cells, typically on the order of 10 um diameter, and thus the phase "microcellular foams" was coined.The batch microcellular process has two stages. In the first stage a thermoplastic sample is placed in a pressure vessel which is then pressurized with a non-reacting gas. Carbon dioxide and nitrogen are typically used as the foaming agents because of their low cost and high solubility in most polymers. The polymer sample absorbs the gas until an equilibrium gas concentration is reached. At this point. the sample is removed from the pressure vessel. In the second stage of the microcellular process the sample is heated, typically in a hot bath, to induce foaming. The temperature of the hot bath is in the neighbourhood of the glass transition temperature of the polymer, and thus the polymer remains in a solid, or rubbery state, well below the melting point, during the entire process. To distinguish these foams from the common foams made from polymer melts, they are described as "solid state" foams.The process described above is a batch process used to produce relatively small amounts of foam specimens at a time. The production capability of the solid-state microcellular foams has increased with the development of the semi-continuous process.In the semi-continuous process the sheet of polymer placed in the pressure vessel is replaced with a roll of polymer which has a gas permeable material rolled up in it to allow gas to diffuse into the entire surface of the roll. The polymer roll and gas permeable material are first separated, and then the polymer sheet is drawn through a hot bath to foam, and a cold bath if necessary to quench the structure.Microcellular foams can be produced with a wide range of densities and with an integral skid. Due to their potential as a novel family of materials, a number of polymer-gas systems have been explored in recent years, including polystyrene, polycarbonate, PET, PETC, and PVC.In this paper we present a detailed experimental characterization of the ABS-C02 system, and explore the effects of key process parameters on the microstructure.EXPERIMENTALCommercially available Cycolac GPX 3700 ABS, manufactured by General Electric was used in this study. All of the specimens were produced from 1.5 mm thick sheet with natural colour. The unprocessed material has a density of 1.04 g/cm3, and a glass transitions temperature of about 116℃.Solubility and diffusivity measurementsSpecimens were cut from 1.5 mm thick sheet to dimensions of 2.5 x 2.5 cm. Each sample was then saturated in a pressure vessel at 26.7℃(80°F) controlled to±1℃. The temperature and pressure used to saturate the specimens will be referred to as the saturation temperature and saturation pressure respectively. The saturation pressure was controlled to within ±35 kPa (±5 psi). The samples were periodically removed from the pressure vessel and weighed on a precision balance with accuracy of ±10ug to determine the amount of gas absorbed. Because the amount of gas absorbed by the samples was on the order of 10 mg, this method provided sufficient accuracy.Desorption measurements were made from fully saturated samples. After reaching equilibrium C02 concentration, the samples were allowed to desorb the C02 while held at 26.7℃(80°F) and atmospheric pressure. During the desorption experiments, the samples were weighed on a precision balance to determine the remaining C02 concentration.Foam sample preparation and characterizationSamples were cut to dimensions of 2.5 cm×2.5 cm and saturated in a pressure vessel maintained at 26.7±1℃(80°F) until an equilibrium CO2concentration was reached. The time required to reach equilibrium was determined from the sorption measurements discussed above. After saturation. all specimenswere allowed to desorb gas for five minutes prior to foaming. The same desorption time, 5 minutes, was used for all specimens to ensure that the integral unfoamed skin thickness was negligibly small. After desorption, the samples were foamed by heating in a glycerin bath for a length of time that will be referred to as the foaming time. The temperature of the glycerin bath used to foam the specimens will be referred to as the foaming temperature. All samples were foamed for five minutes. Once the foaming time had elapsed, the foamed specimens were immediately quenched in a water bath maintained at room temperature. Specific values of the saturation pressures,foaming temperatures, and foaming times will be discussed later. After foaming, the samples were immersed in liquid nitrogen and then fractured to expose the internal microstructure. The fractured surfaces were made conductive by deposition of Au-Pd vapour and then studied under a scanning electron microscope (SEM). All SEM micrographs were taken along the centre-line of the sample.Determination of cell size and cell nucleation densityThe average cell size, cell size distribution, and number of bubbles per unit volume of foam were determined by Saltikov's method described in detail by Undenvood. Saltikov's method allows the characteristics of a three dimensional distribution of spheres to be estimated from a two dimensional image, such as a micrograph. Previously it was assumed that the fracture plane passed through the centre of all bubbles in a micrograph, introducing a small error in the estimation of the average cell size. cell size distribution, and cell nucleation density. In addition, it was also assumed previously that the number of bubbles per unit volume (i.e. bubble density) could be determined by cubing the line density. Saltikov's method provides a more robust procedure for estimating the bubble density, and is applicable to a wider range of microstructures. Saltikov's method was implemented by digitizing an SEM micrograph with approximately 200 bubbles, and using NlH lmage to determine the areas of the bubbles. NIH Image is a public domain image processing and analysis program developed at the Research Services Branch (RSB) of the National lnstitute of Mental Health (NIMH), part of the National Institutes of Health (NIH). The mean bubble diameter and standard deviations reported in this paper are based on the lognormal distribution proposed by Saltikov.The cell nucleation density was determined by a method described previously and is the number of bubbles that nucleated in each cm3 of unfoamed polymer. The volume fraction of the bubbles was taken to be the area fraction of the bubbles in a micrograph as suggested by Underwood. The density of each sample was determined by the weight displacement method, ASTM D792.RESULTS AND DISCUSSIONThe solubility and diffusivity of C02 in ABSFigure 1 shows the gas sorption of CO2 into 1.5 mm thick ABS sheet subjected to saturation pressures of350 kPa, 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, and 6MPa at a saturation temperature of 26.7℃(80°F). The CO2concentration in mg gas/g polymer is plotted vs time. Over time, the concentration of CO2increases within the polymer until the polymer absorbs no more gas and can be considered saturated. As expected, the concentration of gas at equilibrium increases as the saturation pressure is increased. For the ABS formulation studied here, equilibrium concentrations as high as 150 mg C02/g polymer were achieved at a saturation pressure of 6 MPa. Figure 1 also shows that the diffusion of CO2 in ABS isFigure 1 Sorption curves for 1.5 mm thick ABS in CO2 at 26.7℃(8O°F), and pressures ranging from 350kPa to 6MPa. Increasing saturation pressures result in short er saturation times and higher equilibrium concentrationsdependent on gas pressure. We see that it takes approximately 50 hours to reach equilibrium at a saturation pressure of 3 MPa, while at 6 MPa the equilibrium is reached in 20 hours. The faster diffusion at 6 MPa is a result of effective Tg of the gas-polymer system approaching the saturation temperature of 26.7℃. This isevident from Figure 5 where, for 6 MPa saturation. the onset of bubble nucleation is around 27°C.The equilibrium concentration in milligrams of C02 per gram polymer is plotted in Figure 2 as a function of the saturation pressure. The set of points in Figure 2 define the sorption isotherm for 26.7℃. Usually this isotherm can be characterized using the Dual Mode Sorption Model.In this system at 26.7℃however, a straight line passing through the origin represents all of the data accurately, and therefore Henry's Law can be used to predict the equilibrium concentration at a given saturation pressure:C=HP s(1)where C is the equilibrium gas concentration, mg/g; H is Henry's Law constant (or solubility), mg/g..MPa; and Ps is the saturation pressure, MPa.Figure 2 Sorption isotherm for C02 in ABS at 26.7℃(80°F). Note that equilibrium concentration increases linearly with saturation pressure and the linear regression passes through the origin, indicating Henry's Law is valid for a wide range of pressures in this systemFigure 2 shows that Henry's Law is valid for all of the saturation pressures explored. From a least squares fit of the data in Figure 2, the Henry's Law constant was determined to be 25.0 mg/g.MPa for a saturation temperature of 26.7℃.Figure 3 shows desorption results for ABS at 26.7℃. where the fraction of the gas remaining from the fully saturated condition is plotted as a function of time. The rate of desorption seen in Figure 5 is a function of the initial C02 concentration; increasing saturation pressure (or equivalently the equilibrium concentration) results in a faster rate of desorption. This behaviour is consistent with our observations from Figure 1 where higher saturation pressures led to significantly lower sorption times.The average diffusion coefficient, D, can be estimated from Figure 1 using the solution of the diffusion equation for a plane sheet. This diffusion coefficient is an average over the entire range of gas concentrations experienced by the sample, and is given by:2/121049.0⎪⎪⎭⎫ ⎝⎛=t D (2) Figure 3 Desorption curves for 1.5 mm ABS at 26.7℃and atmospheric conditions. The gas concentration is given as a fraction of the initial concentration. A higher initial saturation pressure results in a faster desorptionwhere t is the sorption time, 1 is the thickness of the sheet, and(t/12)1/2 is the value of t/12 when half of the equilibrium amount of gas has been absorbed. Table 1 presents the approximate time to reach saturation, and the average diffusion coefficients for C02 in ABS for different gas pressures. We see that the diffusion coefficients range from 2.14 x10-8cm2/sec for saturation at 350 kPa to 19.2 x 10-8cm2/sec at 6.0MPa. As a result of this concentration dependent diffusivity, the saturation time decreases (see Table 1) with increasing saturation pressure. from about 120 hours at 350 kPa to about 8 hours at 6.0 MPa.Conditions for steady-state structureThe objective of this portion of the study was to determine the foaming time required to produce ABS foams with a steady-state, or equilibrium, density. From the instant a saturated sample is placed in the glycerin bath, the bulk density of the specimen decreases at an ever decreasing rate until a steady sate value is achieved. After the foam density has reached steady-state, the density stops decreasing. For a given specimen thickness, the time required to reach steady-state is a function of the saturation pressure and temperature, and foaming temperature.In this experiment, samples were saturated with C02maintained at 350kPa (50.8 psi) and 22℃, and foamed at 120℃for various lengths of time. The lowest gas pressure was chosen for this experiment so as to find the longest time needed to achieve steady-state structure. The foam density as a function of foaming time is plotted in Figure 4. Recall that the density of the original. unfoamed ABS was 1.04 g/cm3. Figure 4 shows that it takes approximately 300 seconds (5 min) to reach steady-state in the ABS-C02 system for the given processing conditions. Since most other processing conditions will reach an equilibrium foam density faster than at these conditions, we used a foaming time of 300 seconds for all experiments in this study. In addition. Figure 4 shows that at a foaming temperature of 120℃, the original density is reduced by approximately 50% during the 300 seconds of foaming.Figure 4 Plot of foam density as a function of foaming time, showing that a foaming time of approximately 300 seconds is required to reach equilibrium in the ABS-C02system. Samples weresaturated at 350 kPa, allowed to desorb for 5 minutes, then foamed at 120°CThe effect of saturation pressure and foaming temperatureTo explore the effect of foaming temperature and saturation pressure on microstructure, samples were saturated at different pressures and then foamed over a range of temperatures. After the samples had been produced, the foam density, average cell size, cell size distribution, and cell nucleation density were determined.Figure 5 shows a plot of the relative density (density of the foam divided by the density of the solid material) as a function of foaming temperature for the saturation pressures explored. A wide range of relative densities can be produced in the ABS-C02 system. Foams can be produced with relative densities from 0.99 (i.e. almost fully dense) to as low as 0.09. In addition, most densities can be produced by using more than one processing condition. In other words, different saturation conditions and foaming temperatures can be used to produce the same density foam. Similar to other microcellular systems, Figure 5 shows that foaming can occur in ABS at temperatures significantly below the glass transition temperature of the unsaturated material due to plasticizing of the polymer matrix by the absorbed C02. As the saturation pressure is increased, the effective glass transition temperature drops, allowing foams to be producedFigure 5 Process space for the ABS-CO2, system, showing a plot of the relative density as afunction of foaming temperature for saturation pressures from 350kPa to 6MPa. All samples were saturated at 26.7℃. allowed to desorb for five minutes before foaming, then foamed for five minutes. The useful part of the process space lies to the left of the minimum density for a given gas pressureat lower temperatures. At a saturation pressure of 6 MPa. Figure 5 shows that foaming is possible at approximately 27℃, just above room temperature.The relative density of microcellular ABS is affected strongly by the foaming temperature. As the foaming temperature increases, the relative density decreases in near linear proportion. The fact that relative density decreases nearly linearly with foaming temperature is a great processing advantage. allowing precise control over this vital foam property. As the foaming temperature increases, the foam density reaches a minimum, and can start to increase with increasing temperature. At 5 MPa, Figure 5 shows that using foaming temperatures higher than 100℃produces foams with a higher relative density. At 140℃, for example, a relative density of approximately 0.8 is produced, significantly higher than the relative density of 0.3 produced at a foaming temperature of 100℃. At higher temperature, the cells begin to collapse leading to a denser structure. Foams produced at these higher temperatures are typically of poor quality, with 1 to 2 mm blisters on the surface. This minimum in the density versus foaming temperature can be observed at several other gas pressures in Figure 5.Figure 6 shows SEMs of four different microcellular ABS foams. The first two images, A and B, demonstrate the large effect of saturation pressure on foam density and cell size. Figure 6 A and B wereproduced with different saturation pressures, 3 and 6 MPa respectively, but the same foaming temperature of 70℃. The foams in A and B have relative densities of 0.70 and 0.42 respectively. The cell sizes vary from approximately 5 um for A to less than 1 um for B. Images C and D in Figure 6 show two foams produced from the same saturation pressure, 350 kPa, but foamed at different temperatures, 105 and 120℃. The foams have relative densities of 0.88 for C and 0.31 for D and show markedly different foam structures.Table 2 presents the results of the scanning electron micrograph analysis, and shows it is possible to produce microcellular ABS foams with a wide range of cellular properties. Not all foams were suitable for analysis using Saltikov's method. To be suitable for analysis, the foam structure should have spherical cells, and the cells must be distinct in the micrograph. For example, in Figure 6 images A and C can be analyzed, while B and D can not. Thus the test pressures and foaming temperatures not reported in Table 2 are the conditions that produced cells not suitable for a Saltikov analysis. The measured average cell diameters in Table 2 vary from 5.58 pm to 0.54 pm, and the cell nucleation density ranges from 4.0 x 1 010 to 1.8 x 1013 cells per cm3. Microcellular ABS foams generally have small cell sizes and high cell nucleation densities.Figure 6 Micrographs of four different microcellular ABS foams. A and B were saturated at different pressures, 3 MPa and 6 MPa respectively, but were foamed at the same temperature, 70℃. C and D were both saturated at the same pressure, 350 kPa, but were foamed at different temperatures, 105 and 120℃, respectively. All samples were allowed to desorb for five minutes before being foamed for five minutesCONCLUSIONSProcessing conditions have been presented for producing solid-state microcellular ABS foams using carbon dioxide as the blowing agent. It was found that, at a given temperature, the rate of C02 sorption and desorption in ABS is dependent on the gas concentration. It was also discovered that the ABS-C02 system exhibited a unique microstructure with a relatively narrow distribution of bubble sizes. An experimentalinvestigation of the major processing variables, foaming time, saturation pressure, and foaming temperature yielded several insights into the processing behaviour of the ABS-C02 system. It was determined that it takes a maximum of approximately 300 seconds for foam growth to complete. It was also determined that, for all saturation pressures explored, foam density decreases nearly linearly with increasing foaming temperature until a minimum density is reached. Foams with densities ranging from 0.09 g/cm3 to almost fully dense, 1.03 g/cm3 were produced. The useful range of process space for the ABS-C02 system was established.ACKNOWLEDGEMENTSThis research was primarily supported by the University of Washington-Industry Cellular Composites Consortium. Partial support was provided by National Science Foundation Grant MSS 9114840. This support is gratefully acknowledged.1. Brisimitzakis A.C., Styrenic resins - ABS, Modern Plastics, 68,(1991), 85-86；2. Martini J.E.. Suh N.P. and Waldman F.A., The Production and Analysis of Microcellular Thermoplastic Foams, Society of Plastics Engineers Technical Papers, XXVIII, (1982), 674-676；3. Kumar V. and Schirmer H.G., Semi-continuous Production of Solid State PET Foams, Society of Plastics Engineers Technical papers, XLI, (1995), 2189-2192；4. Kumar V. and Schirmer H.G., A Semi-continuous Process to Produce Microcellular Foams, US Patent 5,684.055 (1997)；5. Kumar V. and Weller J.E., A Model for the Unfoamed Skin on Microcellular Foams. Polymer Engineering and Science, 34, (1994), 169-173；6. Kumar V. and Weller J.E., Production of Microcellular Polycarbonate Using Carbon Dioxide for Bubble Nucleation, Journal of Engineering for Industry, 116. (1994). 413-420；7. Handa V.P.. Wong B., Zhang Z., Kumar V., Eddy S. and Khemani K., Some Thermodynamic and Kinetic Properties of the System PETG-C02, and Morphological Characteristics of the C02-Blown PETG Foams, Polymer Engineering and Science, 39, (1999), 55-61；8. Kumar V. and Stolarczuk P.J., Microcellular PET Foams produced by the Solid State Process, Society of Plastics Engineers Technical Papers. XLII, (1996). 1894-1899；9. Kumar V. and Weller J.E., A Process to Produce Microcellular PVC, International Polymer Processing, 7, (1993), 73-80；10. Shimbo M., Baldwin D.F. and Suh N.P., Polym. Eng. Sci., 35, (1995), 1387；11. Park C.B. and Suh N.P., Polym. Eng. Sci., 36, (1996), 34；12. Collias D.I., Baird D.G. and Borggreve R.J.M., Polymer, 25, (1994), 3978；13. Underwood E.E.. Quantitative Stereology, Adison-Wesley, Reading, Massachusetts, (1970)；14. Michaels A.S., Vieth W.R. and Barrie J.A., Solution of Gases in Polyethylene Terephthalate, Journal of Applied Physics, 34, (1963),1-12；15. Crank J.. The Mathematics of Diffusion, Oxford University Press,New York (1975)。

材料成型及控制工程专业英语--1.MATERIALS-AND-THEIR-PROPERTIES

1.1 Metals and Non-metalsWords and termsdefinite－确定的、明确的defect－缺陷plastic deformation塑性变形stress concentrator 应力集中点self-strengthening自强化the tip of a crock裂纹尖端☐Among numerous properties possessed by materials，their mechanical properties，in the majority of cases，are the most essential and therefore，they will be given much consideration in the book．☐在一些主要应用场合，机械性能是材料的各种性能中最重要的性能，因此，本书中将重点讨论。

▪consideration 考虑，需要考虑的事项，报酬☐All critical parts and elements，of which a high reliability （可靠性）is required，are made of metals, rather than of glass，plastics or stone.☐由于各种关键零部件的可靠性要求高，均用金属而不是玻璃、塑料或石头制造。

▪is required 翻译时将英文中的被动语态，改译为汉语中的主动语态。

▪rather than 而不是☐As has been given in Sec.1-1，metals are characterized by the metallic bond（金属键），where positive ions （正离子）occupy the sites of the crystal lattice （晶格）and are surrounded by electron gas（电子云）．☐正如Sec1-1中所说，金属主要由金属键组成（其特征主要……）。

材料成型外文文献翻译

WELDING FOR THE RAILROAD INDUSTRYBy Brian MeadeManager of Railroad Technical ServicesThe Lincoln Electric CompanyCleveland, Ohio. To meet their demanding service conditions, railroads continue to advance welding technology.There are several distinct differences between railroad welding and that of other industries. The bulk of all railroad welding is performed by either the engineering (track) department or the mechanical (car) department. Welding in the car and locomotive department generally uses the common arc welding processes to join materials such as mild steel, stainless, cast iron, and some manganese. The track department, however, is far more unusual and uses fewer, more specialized types of welding.The most common track welding functions are electric arc, thermite,, and flash butt. Standard arc welding processes such as SMAW, GMAW, and FCAW are used to weld manganese and carbon steel track components. However, thermite and flash butt are used for joining continuous welded rail. The flash butt method is used in the plant to create quarter-mile ribbon rails, which are then transported by a rail train to the location where they will be installed. Both flash butt and thermite (sometimes known as aluminothermic) are then used in the field, to join the larger lengths of rail together into continuous welded rail. They are also used in maintenance welding for replacing defective rail and for light construction.Following are some of the considerations that separate railroad welding from other fields. Most of the differences occur in the welding of rails and other track components, such as frogs(the parts of switches where the two tracks join) and crossing diamonds. Therefore, this article will focus most heavily on this area.Classes of Rail WeldingWelding is a process that joins rail ends by melting them with superheatedThermiteliquid metal from a chemical reaction between finely divided aluminum and iron oxide. (Fig.A5—from AWS D15.2). Filler metal is obtained from a combination of the liquid metal produced by the reaction and pre-alloyed shot in the mixture.Flash Butt Welding is a resistance welding process that produces a weld at the closely-fit surfaces of a butt joint, by a flashing action followed by the application of pressure after heating is substantially completed. Very high current densities at small contact points between the rail ends causes the flashing action, which forcibly expels the material from the joint as the rail ends are moved together slowly. A rapid upsetting of the two workpieces completes the weld.Welding refers to the standard arc welding processes used elsewhere, particularly Electricshielded metal arc welding (SMAW) or “stick welding (Fig. A1-- from AWS D15.2);gas metal arc welding (GMAW) (Fig. A2 --from AWS D15.2); and flux-cored arc welding (FCAW), with or without additional gas shielding (Fig. A3-- from AWS D15.2.) These processes are used on frogs and crossing diamonds (both manganese and carbon steel); for carbon steel rail ends, switch points, and wheel burns; and for joining carbon steel rails.Rail Service and Chemical CompositionPart of what makes rail welding different from other welding is the composition of the rail.Carbon content limits are 0.72% to 0.82%, while manganese can range between 0.80% and1.10%. Rail is subjected to continually varying loads, forces and stresses, in all kinds of temperatures and environments, and must carry out its task without failure for many years. Service demands on modern rail continue to become more severe, with loaded freight cars approaching 286,000 pounds. Wheel loads may reach 36,000 pounds, applied to a contact patch approximately the size of a dime. The resulting contact and shear stresses are severe, both in and on the railhead.While the first cast iron rail was produced in England in 1776, modern steel rail incorporates steelmaking techniques such as vacuum degassing and multiple-station argon gas stirring. Continuously cast, fully pearlitic, in-line head hardened rail is now being produced with head hardness values exceeding 380 Brinell.The result of these improvements is rail with better static and dynamic properties, in addition to more metallurgical cleanliness. The chemical composition limits for standard steel rail are shown in the AREA (American Railway Engineering Association) Manual for Railway Engineering (Table 2-1, Chapter 4, AREA Manual).Related mechanical properties are also spelled out in the AREA manual (Table 2-2, Chapter 4). These include a surface hardness of at least 300 Brinell for standard rail and between 341 and 388 Brinell for high-strength rail (alloy and heat-treated). The 388 Brinell upper limit may be exceeded, providing a fully pearlitic microsructure is maintained. Tensile properties required include a minimum yield strength of 70 ksi for standard rail and 110 ksi for high-strength rail; tensile strength minimums of 140 ksi and 170 ksi respectively; and minimum elongation in 2 inches of 9 percent for standard and 10 percent for high-strength.Thermite WeldingAlthough widely used in the railroad industry, thermite welding is probably one of the least understood processes in the balance of industry. Developed as an improvement to the earlier practice of bolting rail joints together, thermite welding still produces some closures with impact and fatigue properties that may be less than desirable. A 1996 Conrail1 study showed that, in 1994, 26.5 percent of total rail defects were attributable to weld failures, 18.3 percent were due to defective thermite welds and 8.2 percent were due to defective flash butt welds. However, the portability, cost-effectiveness, and convenience of thermite welding results in its continued extensive use.Thermite welds are actually as much a casting as they are a weld, and consistency may be difficult to achieve. Weld charge manufacturers have made significant improvements to thermite weld quality and hardness in recent years. Comparisons of welds made using thermite charges from two suppliers showed that the premium charges of one firm were typically harder and stronger than the standard charges produced by the other, although there was a substantially greater spread in the strength values obtained with the first firm’s welds. Thermite weld charge manufacturers can provide a variety of weld hardnesses, depending on customer needs. Higher hardness is deemed to be better, considering the desire of the railroads to have the rail last longer under increasingly severe axle loadings and tonnages. The higher hardness also improves fatigue and deformation resistance and more closely matches the hardness of new head-hardened rail,1An Investigation of Thermite Rail Weld Composition and Properties; Lonsdale. C.P., and Luke, S.T., Conrail Technical Services Laboratory, Altoona, PA; Proceedings of the 1996 International Conference on Advances in Welding Technology, Columbus, Ohio, pp. 447-460.which approaches 400 Brinell. Harder welds also stand up better to heavy traffic and help prevent localized railhead depressions and deformation at the weld.Aluminum plays a key role in thermite welding, where it not only reacts with iron oxide to provide the original heat for welding but also serves as a deoxidizer in the weld charge. Here, it tends to react with oxygen in the still-liquid casting as it solidifies, reducing weld porosity and increasing tensile strength. However, too much aluminum will embrittle the steel. To ensure weld quality and consistency, it is important to control all weld charge alloying elements and residuals to keep them within specificationsMany variables can affect the properties of welds produced by thermite field welding. Among them are welding procedures, including the amount of gap, preheat, rail movement, rail end cleanliness, weather during welding, crucible cleanliness, and welder skill.Flash Butt WeldingBecause aluminothermic rail weld failure rates tend to increase with higher axle loads, railroads are looking for viable alternative rail welds. In-track flash butt rail welding has gained great acceptance as an alternative. The process has proven to make strong, reliable welds in field conditions. However, because rail steel is consumed during the course of the process, in-track flash butt welding cannot presently be used as an alternative for all in-track applications.The flash butt welding process originally was developed in the former Soviet Union. However, it was improved and perfected in the U.S. by the Holland Company, a major flash butt welding contractor and builder of flash butt welding equipment. Large fixed plant flash butt rail welding plants are commonly used on major railroads units, but mobile truck-mounted units (Fig.6) can also take the equipment directly to the weld site. A typical unit aligns the rail ends, charges them electrically, and hydraulically forges the ends, melting the two ends together. Thewelderhead automatically shears upset metal to within 1/8" of rail profile. A base grinder then removes the 1/8" flashing material, leaving a smooth base and reducing the likelihood of stress risers that could shorten the life of the rail. A magnetic particle inspection, in addition to visual inspections, verifies the quality of the final weld.The flash butt welding process tends to produce a weld with a heat-affected zone that is much narrower than that of a typical thermite weld (Fig.7). This also results in a more consistent Brinell hardness profile across the finished weld, which signifies a lack of hard or soft spots that can cause welds to deform and ultimately fail.Electric Arc Welding of Frogs and Crossing DiamondsThe extra stresses incurred by frogs and crossing diamonds require a material with high strength and durability, and one that will resist failure under impact and heavy loading. To achieve these properties, they are typically cast from austenitic manganese steel, an extremely tough, nonmagnetic alloy with unique properties that differ from common structural and wear-resistant steels. One of these properties is its capacity for work hardening at the surface under impact while the underlying body retains its original toughness. Metal-to metal wear resistance is excellent, which is essential in rail applications.For trackwork castings, AREA requires conformance with ASTM A128, Standard Specification for Steel Castings, Austenitic Manganese, except for slightly modified chemical requirements that include:Carbon 1.00/1.30%Manganese 12.00% minimummaximumSilicon1.00%Phosphorus 0.07% maximumThe high manganese content stabilizes the austenite by retarding its transformation to other structures. Silicon acts mainly as a deoxidizer, while phosphorus is limited because it tends to promote hot cracking, during casting as well as in subsequent welding operations.Other than these special limits, the metallurgy of cast rail components is similar to other austenitic manganese castings. Understanding the basic metallurgy of this material will make it easier to relate to the special aspects of welding it. At high temperatures, the structure of all types of steel is essentially austenitic. Although most carbon and alloy steels transform to other structures as they cool, the addition of large amounts of manganese combined with sufficiently fast cooling suppresses this transformation. Manganese steel castings may be relatively brittle before heat treatment, as normal cooling rates in the mold are too slow to retain a fully austenitic structure. This is rectified by heating and holding at the appropriate austenitizing temperature (generally 1850 to 1950 F), then quenching in cold, agitated water. Proper procedures are important, since either inadequate austenitizing or too slow cooling can result in excessive carbides that will lower the mechanical properties.Reheating of manganese steels can also cause carbide precipitation and resulting embrittlement, with the degree depending upon both exposure time and temperature. Thus, it is necessary to use welding procedures that will minimize or avoid prolonged overheating.This and other considerations make electric arc welding of manganese frogs an area that can sometimes confuse a newcomer to this field. Without the ability to properly focus on all data generated by the manufacturer of welding materials, the weldor can easily be perplexed by the erratic results achieved with different welded track castings. The difficulty can arise from a number of areas.Lincoln Electric conducted a study of manganese frog welding failures in October, 1996.A team of engineers, assembled to evaluate weld metal fatigue in a #10 rail bound manganese casting, studied these areas:Number of times weldedGross MGT (million gross tons/year) on track segmentAge and type of castingsWelding procedureWelding materials compositionComposition of the base castingThere have been claims of premature cracking in weld deposits made with manual electrode and wire on frog castings for nearly 60 years. Lincoln Electric has recorded data from 1937 that supports the usage of a manganese-based formulation in a product developed to rebuild manganese frog castings. At that time, Lincoln supplied a 12-14% manganese electrode to the railroads along with a stainless electrode to seal cracks that were in the original castings. The stainless steel electrode was used only in the flangeways and deep in the bottom of the casting, prior to buildup with the manganese-based electrode. The 1996 study supported the earlier data and also yielded some interesting conclusions for improvements in the technique used.The as-received casting is shown in Fig. 1. A closeup view of the cracking area is shown in Fig. 2. Sections AA and BB were made with a carbon arc torch to remove the cracked portion for further study.Sections CC and EE in Fig. 3a were made to study the region near the point that seemed to be free of cracks on the surface. Cracks were observed in the base metal and in the weld. The morphology of the cracks indicates that the preexisting cracks in the base metal have grown intothe weld during or at the end of welding, and these have subsequently opened up under load in service (Fig. 3b and 3c). In addition, the presence of a repair weld near the base metal can be seen in Fig. 3b. This was identified as a 312 stainless weld, which was put down to repair cracks in the base casting prior to building up with a manganese electrode.The cracks in the base casting follow the austenite grain boundaries, as shown in the higher magnification view, Fig. 3d. As they grow into the weld, they continue along the austenite grain boundaries as seen in Fig. 3e. A full section of the weld with the whole casting (Section EE) is shown in Fig. 4a. As is evident, there are cracks in the base metal that subsequently run into the weld metal (Fig. 4b). Based on this evidence, this cracking phenomenon appears to be a form of hot cracking.Sections FF, GG, and HH were taken in the cracked region (Fig. 5a). Section GG is shown in Fig. 5b and indicates that the cracks at the top have opened up under the loading during service.Conclusions for Improving Weld Repair PerformanceIn summary, the welding in this example was done in a situation that caused hot cracking. Chemical analysis reveals that the phosphorus level in the base casting is somewhat on the high side. The effect of phosphorus in causing hot cracking is well known (See AWS D15.2 Annex B for discussion of phosphorus under B2 and B6.2).The evidence of the stainless bead (used to seal a crack prior to buildup with manganese electrode) shows that the cracks in the base casting grew along the austenite boundary until they reached the stainless deposit. This deposit retarded the growth of the cracks and protected the weld deposit. Changing the technique to include a light layer of 308L or 312 stainless steel canonly improve the performance of the weld repair. Lower heat input while welding can help reduce hot cracking. Wirefeed welding processes that favor lower heat input are highly recommended, as opposed to “stick” welding. Lincoln Electric continues to conduct experiments to determine whether manganese electrode deposit chemistry can be further optimized to provide greater resistance to weld cracking growing from preexisting cracks in the base casting.# # #15-195CP/11-17-97。

材料成型及控制工程专业英语及翻译解读

最新消息1-2the benefits of civilization which we enjoy today are essentiallydue to the improved quality of products available to us .文明的好处我们享受今天本质上是由于改进质量的产品提供给我们。

the improvement in the quality of goods can be achieved with proper design that takes into consideration the functional requirement as well as its manufacturing aspects. 提高商品的质量可以达到与适当的设计,考虑了功能要求以及其制造方面。

The design process that would take proper care of the manufacturing process as well would be the ideal one. This would ensure a better product being made available at an economical cost.设计过程中,将采取适当的照顾的生产过程将是理想的一个。

这将确保更好的产品被使可得到一个经济成本。

Manufacturing is involved in turning raw materials to finished products to be used for some purpose. 制造业是参与将原材料到成品用于某些目的。

In the present age there have been increasing demands on the product performance by way of desirable exotic properties such as resistance to high temperatures, higher speeds and extra loads.在现在的时代已经有越来越多的产品性能要求的理想的异国情调的性能如耐高温,更高的速度和额外的负载These in turn would require a variety of new materials and its associated processing.这些反过来需要各种新材料及其相关的处理Also, exacting working conditions that are desired in the modern industrial operations make large demands on the manufacturing industry.这些反过来需要各种新材料及其相关的处理。

材料成型及控制工程专业的专业英语翻译

polystyrene (PS) 聚苯乙烯；poly-tetra-fluoro-ethylene （PTFE）聚四氟乙烯；vacuum forming吸塑；ram injection moulding machine柱塞式注射成型机；计算机辅助设计computer aided design；热塑性塑料thermoplastics；ram injection moulding machines；模具维持费用；聚合物分子的几何形状the geometrical form of polymer molecule；模具设计die design；注射成型机injection moulding；热处理heart treatment；抗拉强度tensile serength；对焊buttwelding；自由锻open die forging；粉末冶金powder metalurgy；注射模塑injection molding；线状聚合物linear polymer；球化spheroidzing；正火normalizing；回火tempering；临界温度critical temperature。

1. The time has probably come to adapt a new name more worthy of the exciting range of polymer materials with many different properties which are available to engineers.目前塑料定义已可能迎来新的术语，以阐述具有不同属性可用于工程领域的聚合物材料。

2.It should be noticed that compression moulding would be impracticable for thermoplastics which have no curing stage during which a chemical reaction take place; because the mould would require cooling each cycle in order to allow the component to harden sufficiently for extraction. 需要指出的是，热塑性塑料压缩成型是不可行的。

材料成型及控制工程外文翻译文献

材料成型及控制工程外文翻译文献(文档含英文原文和中文翻译)在模拟人体体液中磷酸钙涂层激光消融L. Cle`ries*, J.M. FernaHndez-Pradas, J.L. Morenza德国巴塞罗那大学,西班牙1999年七月二十八日-2000年2月文摘:三种类型的磷酸钙涂层基质,在钛合金激光烧蚀技术规定提存,沉浸在一个模拟的身体# uid为了确定条件下他们的行为类似于人的血浆。

羟基磷灰石涂层也也非晶态磷酸钙涂层和a-tricalcium磷酸盐做溶解阶段b-tricalcium磷酸盐的涂料有细微的一个阶段稍微瓦解。

一个apatitic阶段降水量偏爱在羟基磷灰石涂层的涂料磷酸b-tricalcium上有细微的一个阶段。

在钛合金基体上也有降水参考,但在大感应时代。

然而,在非晶态磷酸钙涂层不沉淀形成。

关键词:磷酸钙,脉冲激光沉积,SBF1 介绍激光消融技术用于沉积磷酸钙涂层金属基体上,将用作植体骨重建。

用这个技术,磷酸钙涂层量身定做阶段和结构也成功地研制生产了[1,2]和溶解特性鉴定海洋条件]。

然而,真正的身体条件# uid饱和对羟基磷灰石的阶段,这是钙离子的浓度高于均衡的这个阶段。

因而,这就很有趣也测试条件磷酸钙涂料接近体内的情况,以了解其完整性,在这些条件及其催化反应性质}表面沉淀过程。

因此,非晶态磷酸钙涂层(ACP),羟基磷灰石(HA)涂层,涂层中的一个阶段b-tricalcium磷酸盐较小(ba-TCP)积下激光烧蚀是沉浸在饱和溶液为迪!时间、不同的结构性演变进行了测定。

饱和溶液的使用的是身体uid(SBF模拟#),解决了其离子浓度、酸碱度几乎等于那些人类血浆[5]。

该解决方案也是一个利用在仿生(沉淀)工艺生产磷灰石层在溶胶凝胶活性钛基体。

2 实验模拟身体化学溶解试剂级严格依照以下的顺序,除氢钠,NaHCO3:)3,K2HPO4 H2O,MgCl2)6 H2O,氯化钙和Na2SO4)2 H2O,在去离子水。

冲压模具设计成型方面毕业设计外文翻译

毕业设计（论文）英文翻译课题名称系部材料工程系专业材料成型及控制工程班级学号姓名指导教师2 0 10年3 月 10日4 Sheet metal forming and blanking4.1 Principles of die manufacture4.1.1 Classification of diesIn metalforming,the geometry of the workpiece is established entirely or partially by the geometry of the die.In contrast to machining processes,ignificantly greater forces are necessary in forming.Due to the complexity of the parts,forming is often not carried out in a single operation.Depending on the geometry of the part,production is carried out in several operational steps via one or several production processes such as forming or blanking.One operation can also include several processes simultaneously(cf.Sect.2.1.4).During the design phase,the necessary manufacturing methods as well as the sequence and number of production steps are established in a processing plan(Fig.4.1.1).In this plan,the availability of machines,the planned production volumes of the part and other boundary conditions are taken into account.The aim is to minimize the number of dies to be used while keeping up a high level of operational reliability.The parts are greatly simplified right from their design stage by close collaboration between the Part Design and Production Departments in order to enable several forming and related blanking processes to be carried out in one forming station.Obviously,the more operations which are integrated into a single die,the more complex the structure of the die becomes.The consequences are higher costs,a decrease in output and a lower reliability.Fig.4.1.1 Production steps for the manufacture of an oil sumpTypes of diesThe type of die and the closely related transportation of the part between dies is determined in accordance with the forming procedure,the size of the part in question and the production volume of parts to be produced.The production of large sheet metal parts is carried out almost exclusively using single sets of dies.Typical parts can be found in automotive manufacture,the domestic appliance industry and radiator production.Suitable transfer systems,for example vacuum suction systems,allow the installation of double-action dies in a sufficiently large mounting area.In this way,for example,the right and left doors of a car can be formed jointly in one working stroke(cf.Fig.4.4.34).Large size single dies are installed in large presses.The transportation of the parts from one forming station to another is carried out mechanically.In a press line with single presses installed one behind the other,feeders or robots can be used(cf.Fig.4.4.20 to 4.4.22),whilst in large-panel transfer presses,systems equipped with gripper rails(cf.Fig.4.4.29)or crossbar suction systems(cf.Fig.4.4.34)are used to transfer the parts.Transfer dies are used for the production of high volumes of smaller and medium size parts(Fig.4.1.2).They consist of several single dies,which are mounted on a common base plate.The sheet metal is fed through mostly in blank form and also transported individually from die to die.If this part transportation is automated,the press is called a transfer press.The largest transfer dies are used together with single dies in large-panel transfer presses(cf.Fig.4.4.32).In progressive dies,also known as progressive blanking dies,sheet metal parts are blanked in several stages;generally speaking no actual forming operation takes place.The sheet metal is fed from a coil or in the form of metal ing an appropriate arrangement of the blanks within the available width of the sheet metal,an optimal material usage is ensured(cf.Fig.4.5.2 to 4.5.5). The workpiece remains fixed to the strip skeleton up until the laFig.4.1.2 Transfer die set for the production of an automatic transmission for an automotive application-st operation.The parts are transferred when the entire strip is shifted further in the work flow direction after the blanking operation.The length of the shift is equal to the center line spacing of the dies and it is also called the step width.Side shears,very precise feeding devices or pilot pins ensure feed-related part accuracy.In the final production operation,the finished part,i.e.the last part in the sequence,is disconnected from the skeleton.A field of application for progressive blanking tools is,for example,in the production of metal rotors or stator blanks for electric motors(cf.Fig.4.6.11 and 4.6.20).In progressive compound dies smaller formed parts are produced in several sequential operations.In contrast to progressive dies,not only blanking but also forming operations are performed.However, the workpiece also remains in the skeleton up to the last operation(Fig.4.1.3 and cf.Fig.4.7.2).Due to the height of the parts,the metal strip must be raised up,generally using lifting edges or similar lifting devices in order to allow the strip metal to be transported mechanically.Pressed metal parts which cannot be produced within a metal strip because of their geometrical dimensions are alternatively produced on transfer sets.Fig.4.1.3 Reinforcing part of a car produced in a strip by a compound die setNext to the dies already mentioned,a series of special dies are available for special individual applications.These dies are,as a rule,used separately.Special operations make it possible,however,for special dies to be integrated into an operational Sequence.Thus,for example,in flanging dies several metal parts can be joined together positively through the bending of certain metal sections(Fig.4.1.4and cf.Fig.2.1.34).During this operation reinforcing parts,glue or other components can be introduced.Other special dies locate special connecting elements directly into the press.Sorting and positioning elements,for example,bring stamping nuts synchronised with the press cycles into the correct position so that the punch heads can join them with the sheet metal part(Fig.4.1.5).If there is sufficient space available,forming and blanking operations can be carried out on the same die.Further examples include bending,collar-forming,stamping,fine blanking,wobble blanking and welding operations(cf.Fig.4.7.14 and4.7.15).Fig.4.1.4 A hemming dieFig.4.1.5 A pressed part with an integrated punched nut4.1.2 Die developmentTraditionally the business of die engineering has been influenced by the automotive industry.The following observations about the die development are mostly related to body panel die construction.Essential statements are,however,made in a fundamental context,so that they are applicable to all areas involved with the production of sheet-metal forming and blanking dies.Timing cycle for a mass produced car body panelUntil the end of the 1980s some car models were still being produced for six to eight years more or less unchanged or in slightly modified form.Today,however,production time cycles are set for only five years or less(Fig.4.1.6).Following the new different model policy,the demands ondie makers have also changed prehensive contracts of much greater scope such as Simultaneous Engineering(SE)contracts are becoming increasingly common.As a result,the die maker is often involved at the initial development phase of the metal part as well as in the planning phase for the production process.Therefore,a much broader involvement is established well before the actual die development is initiated.Fig.4.1.6 Time schedule for a mass produced car body panelThe timetable of an SE projectWithin the context of the production process for car body panels,only a minimal amount of time is allocated to allow for the manufacture of the dies.With large scale dies there is a run-up period of about 10 months in which design and die try-out are included.In complex SE projects,which have to be completed in 1.5 to 2 years,parallel tasks must be carried out.Furthermore,additional resources must be provided before and after delivery of the dies.These short periods call for pre-cise planning,specific know-how,available capacity and the use of the latest technological and communications systems.The timetable shows the individual activities during the manufacturing of the dies for the production of the sheet metal parts(Fig.4.1.7).The time phases for large scale dies are more or less similar so that this timetable can be considered to be valid in general.Data record and part drawingThe data record and the part drawing serve as the basis for all subsequent processing steps.They describe all the details of the parts to be produced. The information given in theFig.4.1.7 Timetable for an SE projectpart drawing includes: part identification,part numbering,sheet metal thickness,sheet metal quality,tolerances of the finished part etc.(cf.Fig.4.7.17).To avoid the production of physical models(master patterns),the CAD data should describe the geometry of the part completely by means of line,surface or volume models.As a general rule,high quality surface data with a completely filleted and closed surface geometry must be made available to all the participants in a project as early as possible.Process plan and draw developmentThe process plan,which means the operational sequence to be followed in the production of the sheet metal component,is developed from the data record of the finished part(cf.Fig.4.1.1).Already at this point in time,various boundary conditions must be taken into account:the sheet metal material,the press to be used,transfer of the parts into the press,the transportation of scrap materials,the undercuts as well as thesliding pin installations and their adjustment.The draw development,i.e.the computer aided design and layout of the blank holder area of the part in the first forming stage–if need bealso the second stage–,requires a process planner with considerable experience(Fig.4.1.8).In order to recognize and avoid problems in areas which are difficult to draw,it is necessary to manufacture a physical analysis model of the draw development.With this model,theforming conditions of the drawn part can be reviewed and final modifications introduced,which are eventually incorporated into the data record(Fig.4.1.9).This process is being replaced to some extent by intelligent simulation methods,throughwhich the potential defects of the formed component can be predicted and analysed interactively on the computer display.Die designAfter release of the process plan and draw development and the press,the design of the die can be started.As a rule,at this stage,the standards and manufacturing specifications required by the client must be considered.Thus,it is possible to obtain a unified die design and to consider the particular requests of the customer related to warehousing of standard,replacement and wear parts.Many dies need to be designed so that they can be installed in different types of presses.Dies are frequently installed both in a production press as well as in two different separate back-up presses.In this context,the layout of the die clamping elements,pressure pins and scrap disposal channels on different presses must be taken into account.Furthermore,it must be noted that drawing dies working in a single-action press may be installed in a double-action press(cf.Sect.3.1.3 and Fig.4.1.16).Fig.4.1.8 CAD data record for a draw developmentIn the design and sizing of the die,it is particularly important to consider the freedom of movement of the gripper rail and the crossbar transfer elements(cf.Sect.4.1.6).These describe the relative movements between the components of the press transfer system and the die components during a complete press working stroke.The lifting movement of the press slide,the opening and closing movements of the gripper rails and the lengthwise movement of the whole transfer are all superimposed.The dies are designed so that collisions are avoided and a minimum clearance of about 20 mm is set between all the moving parts.4 金属板料的成形及冲裁4. 模具制造原理4.1.1模具的分类在金属成形的过程中，工件的几何形状完全或部分建立在模具几何形状的基础上的。

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中文2500字本科毕业设计翻译学生姓名：*****班级：*****班学号：*****学院：材料科学与工程学院专业：材料成型及控制工程指导教师：***** 副教授2011年3月25日Section 4 – Die Design and Construction Guidelines for HSS Dies General Guidelines for Die Design and ConstructionDraw DiesHigher than normal binder pressure and press tonnage is necessary with H.S.S. in order to maintain process control and to minimize buckles on the binder. Dies must be designed for proper press type and size. In some cases, a double action press or hydraulic press cushion may be required toachieve the necessary binder forces and control. Air cushions or nitrogen cylinders may not provide the required force for setting of draw beads or maintaining binder closure if H.S.S. is of higher strength or thickness.Draw beads for H.S.S. should not extend around corners of the draw die. This will result in locking out the metal flow and cause splitting in corners of stamping. D raw beads should “run out” at the tangent of the corner radius to minimize metal compression in corners, as shown in figure 16 on page 47. Better grades of die material may be necessary depending on the characteristics of the HSS, the severity of the part geometry, and the production volume. A draw die surface treatment, such as chrome plating, may be recommended for outer panel applications.Form and Flange DiesPart setup in form and flange dies must allow for proper overbend on all flanges for springback compensation. Springback allowance must be increased as material strength increases; 3 degrees for mild steels, but 6 degrees or morefor HSS.Punch radii must be fairly sharp. 1t for lower strength steels. Higher strength steels may require larger radii, but keeping them as small as practical will reduce springback in the sidewalls.Flange steel die clearance must be held to no more than one metal thickness clearance to reduce springback and sidewall curl.Form and flange steels should be keyed or pocketed in the casting to avoid flexing.Flange steels should be designed to wrap over and coin the flange break in order to set the break and reduce springback. See figure 17 on page 48.Die strength must not be compromised with light-weight die construction. High strength steel will require a stiffer die to resist flexing and the resultant part distortions, especially for channel or “hat-section” parts. This type of part can also cause serious die damage if double blanks occur.Cutting DiesTo reduce press tonnage requirements and extend die life, a minimum shear of four to six times metal thickness in twelve inches of trim steel length is recommended.To reduce die maintenance, maximum trim angles should be about 5° to 10°less than those used for mild steel. Trim steels should be keyed or pocketed in casting to avoid flexing. Die clearance should be 7 to 10% of metal thickness.Drawbead TypesConventional Drawbeads Run-out Drawbeads For H.S.S.Lock Beads for Stretch-Form DieFigure 161. Providing a vertical step in the flange stiffens and straightens the flange, stopping sidewall curl as well as springback.2. The addition of stiffening darts helps maintain a 90-degree flange.3. By adding a horizontal step along the flange, the flange is stiffened, resulting in reduced springback.4. Back relief on the upper flange steel allows for extra pressure to be applied futher out on the formed radius.Section 5 – Die Tryout Guidelines for High Strength Steel DiesGeneral Guidelines for Die TryoutDraw DiesHigher draw die binder pressure and press tonnage will be necessary in order to maintain process control and draw parts without buckles. A double action press or a press with hydraulic cushion may be required in some cases to achieve the required binder forces.HSS draw die operations will require sheet steel lubricants that are formulated for extreme pressures. Mill oils will not provide sufficient lubricity for most applications. Pre-lubes or dry film lubricants may be necessary for process control.Die plan view punchline corner radii should be larger than with mild steels to avoid buckling in the corners of the binder.Stretch Form DiesLock beads may require modification to avoid cracking or tearing with higher strength grades of HSS. Opening side walls of beads and enlarging corner radii will avoid cracking of high strength sheet steel. Lock beads should be continuous around the punchline for stretch form dies.For large panels from stretch-form dies, such as a roof panel or hood outer, elastic recovery may result in a shrunken panel that does not fit well on the male die member of the trim or flange dies. This problem is corrected by adding a “plus” factor to the overall part dimensions of the draw die or stretc hform die punch. This “plus” is usually no more than 2.5 mm at the center of the sides and the front, tapering to 0.0mm at the corners of the part profile on the punch. Finish part profile is defined, and plus is removed, in the main flange die.Form and Flange DiesThe punch radius should be fairly sharp with 1 or 2t used for lower strength steel. HSS may require larger radii, but as small as practical to reduce springback of sidewalls.The flange steel radius affects sidewall curl and springback on any offset flanges. This radius should also be small to reduce springback of side flanges. Overbend for springback compensation must be increased as tensile strength increases: 3 degrees is standard for mild steels, but 6 degrees or more will be required for HSS.Flange steel die clearance should be tight, maintaining no more than one metal thickness clearance to reduce springback and sidewall curl.Cutting DiesTo reduce press tonnage requirements and extend die life, a minimum shear of four to six times metal thickness in twelve inches of trim steel length is required.Die clearance should be 7 to 10% of metal thickness for HSS.To reduce trim steel maintenance, reduce maximum trim angles by about 5° to 10° from those used for mild steel. Trim steels should be keyed or pocketed in the casting to avoid flexing.Die Tryout When Using Bake Hardenable SteelIn order to obtain the maximum benefits of BHS, tryout of the dies should be performed as follows: Circle grid analysis must be performed on a panel before any die rework is attempted. With the gridded panel as a reference, the die can be modified to provide a minimum biaxial stretch of 2.0%. Stretch-form or draw dies are best for this material.For rough or functional tryout, it is possible to use mild steel with a 6% to 8% gauge increase to perform the normal process of die preparation. This alleviates complications when the BHS strengthens between each die being tried out. The reason for this is the time lag that normally occurs between a panel being formed and its use in the next operation.When the entire line of dies is ready for approval, all dies must be set in line. Panels should be run through all the die operations consecutively. This will avoid some of the strengthening effects of time delays between stamping operations that can cause variation in panels. Dimensional approval of the panel will be most difficult if this procedure is not followed.The strengthening reaction in the BHS can cause dimensional variation in flanges since springback will vary with time as the strength increases. This is why running the panel through all die operations consecutively is crucial to a successful buyoff.Part BuyoffTo reduce the part buyoff time and eliminate many hours of tryout time, the benefits of functional build must be considered. This procedure has beenproven to save time and money by concentrating on an acceptable sub-assembly rather than making each stamping to part specifications. Those parts that are easiest to change are revised to suit the sub-assembly dimensional targets. Those parts that do not affect the sub-assembly quality are not changed, but the detail part specifications are revised. The functional build process will eliminate excessive tryout hours if used for part buyoff on HSS stampings.In addition to saving tryout time and die rework costs with functional build, lower part variation can also be realized. Two dimensional challenges faced by the die maker when first trying out dies are to reduce the dimensional variation from nominal specifications, and to reduce the short term variationfrom part to part. The typical priority is to first minimize part-to-part variation and later address nominal deviation. A strong argument for this strategy is that the deviation from nominal is not precisely known until a dimensionally consistent part can be evaluated. The results are a dimensionally consistent part even though a number of checkpoints may deviate from nominal, and perhaps even be out of tolerance. In many situations when dimensions on the die are reworked to shift them closer to nominal, they become less stable and result in higher part-to-part variation. The functional build philosophy evaluates the acceptability of the part after it becomes stable, and before minor dimensional shifts are made. Large deviant or critical dimensions may be identified for rework even with functional build. There are dimensions that can often be spared rework based on a functional build approach. In these cases, the part remains more stable and the die more robust because less rework occurs while attempting to shift dimensions.For more information on functional build, refer to the Auto/Steel Partnership publication. “Event-Based Functional Build: An Integrated Approach to Body Development”.第四节-高强度钢模具设计和制造指南对模具设计和制造的一般准则拉深模具为了控制高强度钢的成形并减少板料边缘的弯曲，高强度钢成型时的压力和吨位高于一般情况是必要的。