铝挤压机培训资料31.docx

Chapter 3 Machinery and Equipment for Direct/Indirect Hot ExtrusionTHE MACHINERY AND EQUIPMENT required for rod（杆，棒，竿） and tube extrusion is determined by the specific extrusion process.Ideally, the machinery and equipment should have flexibility but, also, provide specific extrusion process with the optimum（最适宜的） quality and economic efficiency. Direct hot extrusion is the most widely used process, and the term extrusion usually refers to this process. The machinery used is usually based on so-called standard designs.The other extrusion processes usually require specially developed machines. They are designed accordingly and built to meet the needs of the operator.注释：rodrd杆，棒，竿optimum'ptimm 最适宜的3.1 Machinery for Direct ExtrusionThe design of a direct-extrusion press is determined by the following factors： Producta. Aluminum and aluminum alloys (light metal) easy to extrude and/or difficult to extrude. Wire（金属丝制的；金属网制的）, bar（ 木、金属等的条）, section, hollow section, and wide at sections b. Copper（铜） and copper alloys including brass （黄铜） (heavy metal) easy to extrude and/or difficult to extrude. Wire, bar, and sectionc. Steel and high-strength steel alloys easy to extrude and/or difficult to extrude. Process technologya. Extrusion without lubrication （润滑）and without a shell （壳）b. Extrusion without lubrication and with a shellc. Extrusion with lubrication without a shell Toolinga. Container（挤压筒）, stem（杆）, dummy block（挤压垫）, and dieThe wide range of different designs for extrusion presses has recently been reduced in most extrusion plants to a few high-output（高输出）types.Therefore, only extrusion press designs that dominate（主导）todays market are discussed in this chapter. These are referred to as standard extrusion presses in Table 3.1.Direct-extrusion presses account for more than 95% of the total volume of all presses. The direct-extrusion press is used for all current extrusion processes.Table 3.1 Presses for the direct extrusion of aluminum alloys (light metal), copper alloys (heavy metal), and steelMachines for the direct hot extrusion of light-metal alloys are mainly used for the extrusion of section (80%), tube (10%), and rod(<10%) in aluminum and aluminum alloys. The machines for direct hot extrusion of heavy metals, mainly copper and copper alloys, are used for the extrusion of rod, wire, and section (60%) (mainly in brass) and tube (40%) (mainly in copper).Steel and steel alloys are only produced by extrusion to a limited extent （范围,程度）, and then only when rolling （滚压；轧制）is not possible or the volumes are too small.The following major points must be considered in the construction of extrusion presses: Technology requirements: This covers the metallurgical （冶金的,冶金学的）aspects of the deformation technology of extrusion. Economic factors: The economic need for rationalization （合理化）in the construction of extrusion presses is most clearly seen in aluminum extrusion. New extrusion plants are built as integrated （整合的）production lines. They include billet stores, billet heating, extrusion press, handling equipment with longitudinal （纵向的）and transverse （横向的） conveyors （输送带）, section cooling systems, stretcher （拉伸机）, cut-to-length saws（定长剪切锯床） and stackers （栈式存储器）, as well as heat treatment equipment and packing（包装）lines. Similar developments can be found in heavy-metal extrusion plants. Sophisticated（富有经验的；精致的；复杂的）systems for electronic data collection and data analysis for the economic optimal production are already considered to be standard.注释：Wire'wai 金属丝制的；金属网制的bar b: (木、金属等的)条Copper 'kp 铜brass br:s 黄铜lubrication ,lu:bri'kein 润滑shell el 壳 Container kn'tein 挤压筒stem stem 杆dummy 'dmi block blk 挤压垫high-output高输出extent iks'tent 范围,程度rolling 'ruli 滚压；轧制metallurgical ,met'l:dikl 冶金的,冶金学的rationalization ,rænlai'zein 合理化integrated 'intigreitid 整合的longitudinal ,lndi'tju:dinl 纵向的transverse trænz'v:s 横向的conveyors kn'vei 输送带stretcher 'stret 拉伸机cut-to-length saws 定长剪切锯床stackers 'stæk 栈式存储器packing 'pæki 包装Sophisticated s'fistikeitid 富有经验的；精致的；复杂的3.1.1 Extrusion Press Design PrinciplesInitial discussions, over 50 years ago, to rationalize the construction of extrusion presses, resulted in the standardization of extrusion tooling in (DIN 24540). Within the last 30 years, the press manufacturing companies have introduced standardized designs onto the market.Table 3.1 shows the features of extrusion presses for light metals, heavy metals, and steel.The main feature of the direct-extrusion press is the stationary container during extrusion. The die, which is also stationary, and the support tooling are located at one of the end faces of the container, in front of the container bore（ (管、圆筒的)空心部分，膛孔）. Opposite the die, the dummy block located in front of the extrusion stem pushes the billet through the container bore, and the section emerges（形成，出现）through the die (Fig. 3.1).Fig. 3.1 Tool arrangement for direct extrusionFig. 3.2 Geometric relationships for different designs for direct extrusionThe geometric proportions (比例；大小)for different designs for direct extrusion are shown in Fig.3.2.The most common design of extrusion press today is the prestressed(预应力的)four-column press(四柱压力机). It is usually built with a standard stroke（行程，冲程）, which provides good access and easy maintenance（维护,保持,维修）.In a standard-stroke press, the billet is loaded between the container and the stem. The press stroke is determined by the loading stroke and the extrusion stroke. There are no specific requirements placed on the quality of the billet geometry; it is not important for the billet loading. Over 95% of extrusion presses in extrusion plants are standard-strokes.Figure 3.3 shows a 75 MN aluminum extrusion press with extrusion tooling for the extrusion of round and flat billets. The moving cross head has X-guiding similar to the container holder. The control and information systems to monitor （监视,监听,监督）and optimize（使最优化，使完善）the extrusion process can be seen in the foreground（最显著的位置）.Fig. 3.3 Standard stroke extrusion press. Location: Alusuisse in Chippis, SwitzerlandThe short-stroke press is compact （紧凑的,紧密的,简洁的）and requires less space. The short stroke (approximately 60% of the standard stroke) includes the extrusion stroke and a free stroke for manipulation （操作；操纵；处理）. There are three different designs.The billet-loading requirements are either: Billet loading with a billet loader in the free space between the die and the container, with the billet clamped（夹住，夹紧）on the press centerline (the most common design) Free space by extrusion stem transverse movement on the moving cross head (billet loading with a billet loader between the moving cross head and the container) Three containers that can be rotated（旋转）around a column of the press frame（框,结构,骨架） (billet loading without a billet loader in one of the three containers outside the press)Fig. 3.4 Short-stroke press (compact press) for direct extrusionFigure 3.4 shows the control desk, movable auxiliary （辅助的）control desk (swinging （旋转的）), hot log shear（圆棒剪）with the billet loader, and the short-stroke press for aluminum alloys. The container is in the extrusion position. The billet is loaded between the die and the stem when the container has moved back over the stem. The billet must be held exactly between the die and the stem on the press centerline. This ensures that the clearance between the billet and the container is as uniform as possible, guaranteeing perfect upsetting （缩锻，镦锻）of the billet in the container.The tolerance-related diameter variations must be compensated （补偿）by the billet loader to ensure that the billet can be clamped on the press centerline (Fig. 3.5). This ensures that the upsetting of the billet takes place under optimal conditions because of the equal clearance on all sides to the container bore. Air inclusions are less critical, and transverse forces, even if acceptable to a small degree, are avoided during upsetting.Fig. 3.5 Upsetting of a billet clamped on the press centerline (good), and upsetting of a billet resting in the container (poor)Short-stroke extrusion presses have been the state of the art for some time. There are various reasons for this. Schloemann built two 125MN rod-and-tube extrusion presses for aluminum around approximately 1950. These were manufactured as short-stroke presses for production reasons, with billet loading between the die and the container. The stem transverse movement was used before the end of the last century. The length of expensive press components, including columns and the main cylinder, can be kept to a minimum.The company Loewy built a steel tube extrusion press in 1960, with three containers that could be rotated around a column. The aim was high-throughput（高生产量） extrusion with fast press cycles. In practice, this was unsuccessful. The manipulation of the heavy heated containers was only possible with expensive technology. Temperature variations within the container holder as well as in adjacent（毗连的,邻近的,接近的）press components could not be avoided during production. Accurate location of the rotating containers on the press centerline and in line with the stem and the die could not be guaranteed to the necessary reproducibility. The continuous movement of the large containers, three rotations of 120º within an extrusion cycle, required extensive maintenance and regular repair. Only a few presses were built to this design and actually used for production. In general, short-stroke presses are more expensive than standard-stroke presses because of the manipulation needed for billet loading and the mechanical design.注释：bore b: (管、圆筒的)空心部分，膛孔.emerges i'm:d 形成，出现proportions pru'p:n 比例；大小prestressed pri:'stres 预应力的four-column press 四柱压力机.stroke struk 行程，冲程maintenance 'meintinns维护,保持,维修monitor 'mnit 监视,监听,监督optimize 'ptimaiz 使最优化，使完善foreground 'f:raud 最显著的位置.compact 'kmpækt 紧凑的,紧密的,简洁的manipulation m,nipju'lein 操作；操纵；处理clampedklæmp 夹住，夹紧rotatedru'teit 旋转framefreim 框,结构,骨架auxiliary :'ziljri 辅助的swinging 'swii 旋转的upsetting p'seti 缩锻，镦锻compensated 'kmpenseit 补偿high-throughput高生产量adjacent'deisnt 毗连的,邻近的,接近的3.1.2 Main Subassemblies of the Direct Extrusion PressAll extrusion presses consist of the following main sub-assemblies: Press frame, consisting of the following subassemblies:a. Main cylinder: One or two piece; housing and main cylinderb. Platen （台板；焊机床面）: One piece with or without a discard （丢弃；抛弃；放弃）shear and/or with a discard sawc. Columns: Round columns with inboard and external nuts, round columns with compression sleeves （套筒；套管）(tubular) and external nuts, lamellar （薄片状的；薄层状的）tension elements with compression membersd. Bed plate（底板）: Standard with round columns Moving crosshead （联杆器，十字头）, consisting of stem holder , return cylinders, and, if necessary, advance cylinders Container holder with container-moving cylinders Die slide or short die carrier, rotating die carrier, or stationary tool carrier acting as the die holder Discard shear and/or discard sawThe function of the press frame is to withstand the extrusion load. A prestressed stiff press frame provides: Low press extension Low deection （挠度）of the die support Short decompression timeThe press frame consists of a cylinder housing with the main cylinder and ram, a platen, and, if the four columns are not designed as tension and compression elements, a bed plate and guide.The elastic behavior of the press frame under production conditions is an important characteristic of the extrusion press. The stiffness （刚度） of the machine influences the accuracy of the guiding and the die support during extrusion.In many respects, the quality of the press frame plays an important role in the extrusion process. The operational reliability must first be guaranteed. Failures in the column threads（螺纹） must be avoided at all costs. The notch（刻痕）effect at the root of the thread can increase the normal stress by a significant factor. In practice, only the first threads can transfer the forces. This disadvantage is avoided with hammer head lamellar columns. The geometry of the hammer head can be optimized by finite element analysis. In the area of the cylinder housing and the platen, prestressing with round columns is carried out, using inboard and external nuts. There is no prestressing between the housing and the platen, resulting in a relatively large elongation of the press during extrusion. If hollow compression members are located between the housing and the platen instead of the inboard nuts, then this is referred to as a fully prestressed press frame.With prestressed columns designed so that the tension elements are more highly stressed and the compressive elements subjected to lower stresses, the elongation can be reduced to 50% or less of that of non-prestressed columns with normal dimensions （规模，大小）.For example, for a 35.5 MN rod-and-tube press with a column length of 12 m and an extrusion load of 30 MN, the elongation for a prestressed press frame is approximately 2.5 mm and approximately 5 mm for a non-prestressed press frame. Figure 3.6 compares the load elongation diagrams for both tension and compression elements and columns with nuts for this press frame.Fig. 3.6 Load diagram of a prestressed and non-prestressed press frame at a load of 31.5 MN. g, platen; h, column; i, inboard nut;j, outboard nut; k, tension element; l, compression element; m, cyclindar housingIt is correct that larger column diameters result in a lower stress and thus reduce elongation of non-prestressed frames. However, from the machine design point of view, this approach causes problems with the geometry and the guiding system for the die carrier. There is limited space around the housings with larger columns, resulting in an increase in the press cross section and thus the size of the extrusion press.A bed plate is needed for the guide ways of the die carrier. The total extrusion load is produced by the main cylinder and, when tted, by the two advance cylinders. The forces needed for the auxiliary operations, including billet loading, ram return, container sealing （封闭，密封）, and stripping （剥离；剥脱）, and the resultant （综合的；合成的，组合的）cycle times must be taken into account in the design of the cylinders.The container sealing forces and the stripping forces depend on the design of the tooling and the extrusion technology as well as the discard thickness. The container stripping force for aluminum extrusion is determined as follows:where FR-St is the container stripping force, D0 is the containe