铝挤压机培训资料3.1

Chapter3 Machinery and Equipment for Direct/Indirect HotExtrusionTHE 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：rod[rɔd]杆，棒，竿optimum['ɔptiməm] 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 flat sectionsb. 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）today’s market are discussed in this chapte r . These are referred to as standard extrusion presses in T able 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.Machines 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 inbrass) and tube (40%) (mainly in copper).Table 3.1 Presses for the direct extrusion of aluminum alloys (light metal), copper alloys (heavymetal), and steelSteel 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 me tallurgical （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['waiə] 金属丝制的；金属网制的bar [bɑ:] (木、金属等的)条Copper ['kɔpə] 铜brass [brɑ:s] 黄铜lubrication [,lu:bri'keiʃən] 润滑shell [ʃel] 壳Container [kən'teinə] 挤压筒stem [stem] 杆dummy ['dʌmi] block [blɔk] 挤压垫high-output高输出extent [iks'tent] 范围,程度rolling ['rəuliŋ] 滚压；轧制metallurgical [,metə'lə:dʒikəl] 冶金的,冶金学的rationalization [,ræʃənəlai'zeiʃən] 合理化integrated ['intigreitid] 整合的longitudinal [,lɔndʒi'tju:dinəl] 纵向的transverse [trænz'və:s] 横向的conveyors [kən'veiə]输送带stretcher ['stretʃə] 拉伸机cut-to-length saws 定长剪切锯床stackers ['stækə] 栈式存储器packing ['pækiŋ] 包装Sophisticated [sə'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 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 forthe billet loading. Over 95% of extrusion presses in extrusion plantsFig. 3.2 Geometric relationships for different designs for directextrusionare 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）.The 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)Fig. 3.3 Standard stroke extrusion press. Location: Alusuisse in Chippis, Switzerland● 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)Figure 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 .Fig. 3.4 Short-stroke press (compact press) for direct extrusionThe 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.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.Fig. 3.5 Upsetting of a billet clamped on the press centerline (good), and upsetting of abilletIn 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 120ºwithin 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 [bɔ:] (管、圆筒的)空心部分，膛孔.emerges [i'mə:dʒ] 形成，出现proportions [prəu'pɔ:ʃən]比例；大小prestressed [pri:'stres]预应力的four-column press 四柱压力机.stroke [strəuk] 行程，冲程maintenance ['meintinəns]维护,保持,维修monitor ['mɔnitə] 监视,监听,监督optimize ['ɔptimaiz] 使最优化，使完善foreground ['fɔ:ɡraud] 最显著的位置.compact ['kɔmpækt] 紧凑的,紧密的,简洁的manipulation [mə,nipju'leiʃən] 操作；操纵；处理clamped[klæmp] 夹住，夹紧rotated[rəu'teit] 旋转frame[freim] 框,结构,骨架auxiliary [ɔ:ɡ'ziljəri] 辅助的swinging ['swiŋiŋ]旋转的upsetting [ʌp'setiŋ] 缩锻，镦锻compensated ['kɔmpenseit]补偿high-throughput高生产量adjacent[ə'dʒeisənt] 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 deflection （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 guidingand 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 andnon-prestressed press frame at a load of 31.5 MN.g, platen; h, column; i, inboard nut;j, outboard nut;It 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 produ ced by the main cylinder and, when fitted, 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 onthe 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 F R-St is the container stripping force, D0 is the container diameter, l R is the discard thickness, l F is the dummy block land length, and τS is the shear stress of the billet material.The auxiliary loads of the extrusion press are determined by the relevant functions. The ability to remove a billet stuck in the container from the press (sticking billet) is one factor that must be taken into account.The tool carriers for the stem and container can be moved and are fitted with double-acting cylinders. The space-saving oil hydraulic （水压的；液压的）double-acting cylinder offers advantages for both access and press maintenance.Usually, the die carrier and the tools for die changing are fitted with rapid-locking （急锁）systems. Bayonet fittings（卡口式组装件）, which enable the tool to be locked or released by a simple partial rotation,have proved successful.The discard separators do not belong directly to the extrusion press. Discard shears and/or discard saws are configured（安装，配置）in the design of the extrusion press to ensure the optimal operation.The competition among press manufacturers during the 1950s and 1960s resulted in extrusion presses that were simple to build, cost-effective, and that met the demands of the aluminum industry. This resulted in machines that had and still have identical main subassemblies throughout the world. For reasons of quality and economy, modern extrusion press manufacture requires a machine design based on function specific subassemblies.Extrusion presses of modular （模块化的）design can have common functional components and still be tailored （调整使适应）to specific applications, depending on the product and the process.The press types described can be configured for a specific application in an extrusion plant by the addition or removal of components, for example, a discard saw instead of a discard shear . This also applies to the power system (water or oil hydraulic).Some of the most important presses for direct extrusion are:● Extrusion presses for aluminum extrusion for the production of bar , section, and hollow sections● Extrusion presses for copper alloys for the production of wire and/or bar and section Indirect extrusion presses and tube presses, which are similar to direct-extrusion presses in the main components, are discussed in more detail in sections 3.1.2 and 3.2.2.The components of the extrusion press must form a structural unit that ensures a systematic functionality and combination (Fig. 3.7).It must be possible to combine the modular units so that depending on the application of the press, the desired production can be guaranteed. T able 3.2 gives a general overview to assist in the understanding of a rational （合理的）modular system and encompasses （包含）the modern extrusion press and its products, including wire, rod, section, hollow sections, and flat sections. The examples shown can differ from each other in the arrangement （结合体，组合体）of the subassemblies.Fig. 3.7 Direct extrusion press for aluminum showing the componentsCombined direct- and indirect-extrusion presses are known that have, for example, one shear for direct extrusion and one for indirect extrusion. Table 3.3 gives the steps in press power of modern extrusion presses. This range corresponds （符合，一致）(in bold type) to the standard range R10 (from the tool standard DIN 25540). The intermediate sizes (standard type) occur more frequently in the United States than in Europe.Table 3.3 Standard force ratings ofTable 3.2 Components of direct-extrusionpressesFig. 3.8 Press frameThe design of the press frame (Fig. 3.8) must take into account the extrusion load, container and tool changing, and freedom for manipulation, including billet loading. The extrusion load is used as a defining parameter for all components. The press stroke determines the column length according to the design of the press and not the cross section. A bed plate is not required with a prestressed design. This design enables X-guiding to be readily realized. Flat guiding can also be provided by the inclusion of suitable structural elements that have to be independent of the elastic behavior of the press frame. The symmetry （对称性）of the press frame is very important for the elastic behavior of the press under the extrusion load. A square column arrangement is preferred, because it simplifies the components and results in uniform stresses. The tool carrier moving crosshead (Fig.3.9) provides the advance, extrusion, and return strokes. It is moved by the two double-acting cylinders and the main cylinder and transfers the load to the extrusion stem. Quick release systems are used to locate the extrusion stem. The moving crosshead is guided by adjustable guide shoes （导块）on the press frame guides. Upper locating guide shoes are used to provide better alignment （校正；调整）accuracy during the movement of the extrusion stem (X-guiding).The tool carrier container housing (Fig. 3.10) can be moved by two double-acting cylinders. T o ensure that the working area is as open as possible, the container-moving cylinders are located in the main cylinder housing.Fig. 3.9 Moving crosshead for direct extrusionAdjustable guide shoes are used to guide the container housing. The guide-ways are primarily determined by the container housing because it houses the container, which is the largest tooling item. The container working temperature depends on the production. T o achieve a positive location in the container housing independent of the temperature, the container is located in the container housing by four keys. It is located virtually without any play in both the cold and the hot condition. In horizontal （水平的,横的）extrusion, the maximum temperature occurs in the region of the container housing at approximately 20% of the external container diameter above the press centerline. This is because the container housing, which is also hot on the outside, induces an air current(气流）. This cools the bottom half more severely, whereas the upper part of the container housing falls in the wind shadow of the chimney effect（抽吸效应）and increases in temperature. Locating the thermal center of the container housing requires the center of the container to be measured in both the cold and the hot condition. The difference can exceed 5 mm on large extrusion presses.Fig. 3.10 Container housingThe guide-ways for the container housing are arranged as a prism (棱柱)(half X-guiding) to maintain the central location of the container within the tightest limits possible at different operating temperatures. In order to achieve better and reproducible guiding, an upper guide is used that often extends the guiding to X-guiding. The location of the guide-ways with X-guiding should take into account the thermal center point to ensure that the container housing is free from play as far as possible and is accurately located within the extrusion press, even with temperature variations.Flat guiding is also encountered, and this is simpler to adjust but assumes constant thermal conditions in the container holder under production conditions. If the production conditions do not require different working temperatures, then flat guiding is used. The geometry of the flat guiding requires a central guide at the bottom as well as the supporting guides.Top guides to improve the running and guiding reliability are used in a wide range of configurations.The container heating has a significant influence on the container housing. Induction and resistance heating （感应电阻加热）affect the design of the container housing in different ways. In each case, the internal space must be thermally insulated to ensure that the container loses as little heat as possible and to protect the housing from overheating. Resistance heating can be used instead of induction heating, and this requires insulation from the body of the housing. It heats the container from the outside. In this case, it is difficult to bring the temperature above 400 ℃.V arious designs are used for the tool carrier for the dies. Four different designs are usually used (Fig. 3.11).Die shuffles（移动、移来移去、改组）are used almost exclusively （专门地）today for aluminum alloy extrusion presses. Two die carriers are used with a changing table outside the press (Fig. 3.12). The die shuffle can be used, if necessary, as an auxiliary shear to cut the sections behind the die by using a larger shear cylinder. Theoperating position must be adjustable. The design height of the die stack （堆；堆叠）must be held to tight tolerances to guarantee the exact shear position for correct separation of the discard from the section.It is important to always locate the die stack in the same shear position; otherwise, material can build up in the area of the die front face, which results in problems.Die slides are used for copper alloy extrusion presses. They have a die and an ejection （排出）position for the discard, dummy block,Fig. 3.11 Die carrierFig. 3.12 Die changing by exchanging tool carriers on the shuffle table （移动台）outside the pressshell, and cleaning block. The die position can also be a carrier that can be connected and disconnected.Die rotate systems with two positions are used for loading the die sets. Die rotate systems are more commonly seen on copper alloy extrusion presses. Depending on the operational sequence, a faster die change is required for short cycle times. A special discard remover is needed for the discard, dummy block, shell, and cleaning block.Stationary die carriers are mainly used for small extrusion presses up to 8 MN because of the good accessibility. They guarantee accurate and reliable location and therefore are also sometimes found on large presses and for indirect-extrusion presses.Discard separators separate the discard from the section. With aluminum alloys, the separation is carried out directly at the front face of the die or the feeder chamber（进料室）by a shear. A saw is used for copper alloys, and this cuts the extrusion between the container and the die. The discard in this case is still in the container bore. A shear is often used for separation in the extrusion of brass wire. Shears and saws are always part of the extrusion press and are usually mounted （安装）on the top of the platen.注释：Platen ['plætən]台板；焊机床面discard [dis'kɑ:d, 'diskɑ:d] 丢弃；抛弃；放弃sleeves [sli:v] 套筒；套管lamellar （[lə'melə] 薄片状的；薄层状的Bed plate底板crosshead ['krɔ:s,hed]联杆器，十字头deflection [di'flekʃən] 挠度stiffness ['stifnis]刚度notch [nɔtʃ] 刻痕dimensions [di'menʃən]规模，大小.sealing ['si:liŋ] 封闭，密封stripping ['stripiŋ] 剥离；剥脱resultant [ri'zʌltənt]综合的；合成的，组合的hydraulic [hai'drɔ:lik] 水压的；液压的rapid-locking 急锁Bayonet fittings卡口式组装件configured [kən'fiɡə]安装，配置modular ['mɔdjulə] 模块化的tailored ['teiləd] 调整使适应rational ['ræʃənəl] 合理的encompasses [in'kʌmpəs] 包含arrangement [ə'reindʒmənt] 结合体，组合体corresponds [,kɔ:ri'spɔnd] 符合，一致symmetry ['simitri] 对称性guide shoes导块、导套alignment [ə'lainmənt]校正；调整horizontal [,hɔri'zɔntl] 水平的,横的air current气流chimney effect抽吸效应prism ['prizm] 棱柱Induction and resistance heating 感应电阻加热exclusively [ik'sklu:sivli]专门地stack [stæk] 堆；堆叠ejection [i'dʒekʃən] 排出feeder chamber导流室mounted ['mauntid] 安装21。