Методический материал по обучению чтению литературы на английском языке по специальности «Обработка металлов давлением» для студентов 3 курса (6-ой семестр)
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MARKET PENETRATION BY HYDRAULIC PRESSES In the not so distant past hydraulic presses were looked upon with some degree of suspicion due to fears of their leakage, lack of speed, being incapable of blanking operations, maintenance problems as well as the noise made by hydraulic power packs. Therefore a tendency was to use them for deep drawing and assembly operations. And the training that tool and die makers and manufacturing engineers received, the terms used, the approach to tooling, feeding and part handling were almost always oriented towards mechanical presses. This trend, however, is now changing. And as a result of design improvements major developments are taking place which have already led to a new type of fast-acting presses which are arousing considerable interest in what usually was a predominantly mechanical press field. Historically a hydraulic press is one of the oldest of the basic machine tools. As a machine it is probably as old as a bicycle. In recent years hydraulic presses have been attracting greater attention. Automotive manufacturers stamp fuel pump diaphragms, assemble shock absorbers and form disc brakes. Aircraft companies form tough titanium housings and forge turbine blades. Not only engineers are interested in hydraulic press market place – our knowledge extends to the physicist with his varieties of valves, the biologist, the dentist and even the makers of food products. These and hundreds of other jobs are being done today in industry by hydraulic presses. What is a hydraulic press? First and foremost it is a press. Although the term hydraulic press covers a very wide range of types of presses they all have in common the application of force to accomplish work through the controlled containment of fluids. One hundred years or so ago the fluid used to be water – hydraulic presses were all water presses. With the development of the petroleum industry oil was found to be a superior fluid since it lubricated the moving parts of the machine while at the same time providing an excellent medium for transferring pressure. Now one hundred years later because of the oil crisis the industry is on a trend to the use of water, 95% water and 5% soluble oil. Generally a hydraulic press includes a frame, a bed, one or more hydraulic cylinders, a guide or a slide mechanism to control the ram, a control system and a power source. The construction of a hydraulic press and its characteristics will vary depending upon the intended use. Hydraulic presses are built for rubber molding, forging, various types of metalworking operations, maintenance work, auto repairs and glassware manufactures. With the providing of the latest kind of fast-acting presses and a successful outcome of further developments hydraulic presses have made significant in-roads into the traditional market for single-acting mechanical presses. The widespread introduction of hydraulic presses is seen in the double and triple-action press field for sheet-metal pressing, where the great advantage over mechanical presses is the controllability offered by hydraulic power. III. Answer the questions 1. Why were hydraulic presses looked upon with suspicion in the not so distant past? 2. What caused the widespread introduction of hydraulic presses into the market? 3. Where are hydraulic presses used? 4. What do all hydraulic presses have in common? 5. Can you describe a typical hydraulic press? 6. What does its construction depend on? 7. What are hydraulic presses built for? Text 2B 1. Remember the following words: allowance – поправка, ограничение adjust – регулировать accommodate – приспосабливать exert – оказывать давление, действовать eliminate – устранять breakage – поломка, выход из строя crankshaft – коленчатый вал coil – спираль fit, suit – подходить, соответствовать shift – изменять auxiliary accessories – вспомогательное оборудование tool life – срок службы инструмента bending – гибка piercing – прошивка straightening – выпрямление punching – пробивка meet the current standards – отвечать современным стандартам damage – повреждение versatility – многосторонность flexibility – гибкость smashing a die – разрушение штампа pre-set pressure – заранее установленное давление pressure dwell – выдержка под давлением abrasive wheel forming – формовка абразивных кругов at 10 times the capacity – при мощности большей в 10 раз interlocking – блокировка II. Read and translate the text. ADVANTAGES OF HYDRAULIC PRESSES Full power stroke – the full power of a hydraulic press can be delivered at any point in the stroke, not only at the very bottom as the case with mechanical presses. One of the advantages is that no allowance should be made for reduced tonnage at the top of the stroke. In drawing operations, for example, full power of the press is available at the top of the stroke and it is unnecessary to buy a 200 ton press to get 100 tons throughout the stroke. Other advantages are faster setups and no time consuming job of adjusting the screw on the slide to accommodate different dies. Built-in overload protection – a 100 ton hydraulic press will exert only 100 ton pressure (less, if set for less) no matter what mistakes are made in set-up. It is unnecessary to worry about overloading or breaking the press or smashing a die. When a hydraulic press reaches its pre-set pressure, no further pressure is added since the relief valve opens at that limit and the danger of overload is eliminated. Much lower original cost and operating costs – hydraulic presses are relatively simple and there is a significant cost advantage over mechanical presses in comparable sizes. The number of moving parts is few and these are fully lubricated in a flow of pressurized oil. Breakage when it occurs is usually minor, not, for example, like a broken crankshaft. Solenoid coils and occasionally a valve are inexpensive and they are easily replaced without taken the machine apart. This means more operating time and lower maintenance costs. Larger capacity at lower cost – it is easier and less expensive to buy certain kinds of capacity in hydraulic presses. Stroke length of 12, 18 and 24 in. are common, extra stroke is easy to provide. In addition, larger table areas and small presses with big bed areas can be provided. Large 200 ton presses with relatively small beds are available; tonnage of the press does not dictate what the bed size will be. More control flexibility – hydraulic press power is always under control. The ram force, the direction, the speed, the release of force, the duration of press dwell, all can be adjusted to fit a particular job. Jobs with light dies can be done with the pressure turned down. The ram can be made to approach the work rapidly, then shifted to a slower speed before contacting the work. Tool life is just prolonged. Timers, feeders, heaters, coolers and a variety of auxiliary accessories can be switched on in the circuit to fit the job. Hydraulic presses can do far more than just go up and down, up and down. Greater versatility – a single hydraulic press can do a wide variety of jobs within its tonnage range, e.g. forming, blanking, bending, piercing, punching, straightening, powered metal forming, abrasive wheel forming, plastic and rubber molding. Quiet – fewer moving parts and the elimination of a flywheel reduce the overall noise level of hydraulic presses compared to mechanical presses. Properly sized and properly mounted pumping units meet the current standards for noise, even with the pump under full pressure. Noise levels can be controlled due to the control of each phase of the ram movement. More compact – a typical 20 ton hydraulic press is 8ft high, 6ft deep and 2ft wide. A 200 ton press is only 10ft high, 9ft deep and a little over 3ft wide. At 10 times the capacity a 200 ton press only takes up 50% more floor space. Lower tool costs – the built-in overload protection applies to the tools also. The pressure of the press can be regulated to suit the job and the lack of impact, shock and vibration promotes longer tool life. Safety – no manufacturer will (or should) claim that hydraulic presses are safer than mechanical presses. Both types of machines are designed and built to be safe if the controls and safety features built in are used properly. Improperly used all machines are potentially dangerous, but the factor of control of the ram movement makes hydraulic presses easy to make safe. The interlocking of guards as well as other safety devices is relatively easy because of the nature of hydraulic press control system. III. Enumerate all the advantages of hydraulic presses listed in the text and prove them. Text 2C
custom-built – построенный по заказу one-stop shop – многоцелевое предприятие simulation package – моделирование с отображением модели в динамике hub projection – фланец втулки webbing ['webiN] – ребра жесткости intricate ['intrikqt] – сложный bolster ['bqulstq] – матрица, втулка die train – обойма train – зубчатая передача, серия, цепь, ряд взаимодействующих деталей package – узел, агрегат shop-floor trial ['trai(q)l] – производственное испытание torch cut/contoured ['kOntuq] – контурные детали для горелок ring mill – кольцевой прокатный стан hollow – пустотелая деталь net – аккуратный, точный
A NEW 2-COLUMN CUSTOM-BUILT OPEN-DIE HYDRAULIC PRESS The two-column unit, rated at 5,500 tons, combined with the use of simulation software, enables Scot Forge to produce larger open-die forgings in close-to-net shapes, from of a wider variety of ferrous and nonferrous alloys. For years, Scot Forge has been a “one-stop shop” for small through large open-die forgings. Now, with the addition of a two-column, custom-built open-die hydraulic press the company can produce carbon and alloy forgings in more diverse part configurations, in sizes up to 80,000 lb. New types of products that can be produced include parts with hub projections, flanges, and webbing. Using this new press, Scot Forge can also produce heavier and more intricate forgings than it could previously, from materials with higher deformation properties, such as stainless steel, titanium, aluminum, and nickel. In addition, reverse extrusion processes available with the new unit make it possible to produce hollow parts with thinner walls and closed-end cylinders. Equipped with an 11,000-hp hydraulic system, the new press is rated at 5,500 tons. Its forging ram weighs 200, 000 lb, and it can cycle at more than 200 strokes per minute. A 10-bolster die train is provided for efficient tool changes. Aided by new computer modeling software and the press’s large “forging window”, Scot Forge has also increased its ability to forge close-to-net-shape parts, saving customers material and machining costs. The new software provides accurate forging simulations, resulting in optimal forging process plans and precise tool design, while the large “forging window”, which measures 14.315 ft, allows large tooling to be used. The press was designed and built by the company. It joins six other open-die presses, six hammers, and four ring mills, making it possible for Scot to offer customers a wide range of part shapes, including bars, blanks, rings, hubs, cylinders, hollows, torch cut/contoured parts, and spindles. Scot Forge has recently acquired the Transvalor Forge simulation package. It has proved that it can accurately simulate the forging process so that optimal near-net-shape forging can be planned and tooling designed. The simulation approach replaces the need to conduct shop-floor trials with new tooling.
1. In what way does a new two-column-open-die hydraulic press expand capability of Scot Forge? 2. What are the improved technical characteristics of this new press? 3. Would you enumerate materials with higher deformation properties the press uses in its work? 4. What forgings can be produced by using this new press? 5. Can you give short technical characteristics of a new two-column-open-die hydraulic press of Scot Forge? 6. What does close-to-net-shape forging result in? 7. What are the advantages of simulation package, recently acquired by Scot Forge?
Module Three Text 3A
feasible ['fi:zibl] – осуществимый, вероятный, подходящий cross-girder ['gq:dq] – крестообразная балка header blank – заготовка для высадочной машины heading – высадка головок crosshead – крестовина, ползун sleeve – (переходная коническая) втулка gripping frame – зажимающая станина header ['hedq] – высадочный пуансон, пресс для высадки головки behave – (зд.) проявлять maintenance ['meint(q)nqns] – техобслуживание tension bolt – стяжной болт daylight – просвет, интервал pre-stressed framework –заранее напряжённая станина die cavity – полость штампа
A NEW TYPE OF OIL HYDRAULIC DRIVE HORIZONTAL UPSET FORGING PRESS The oil hydraulic drive horizontal upset forging press developed for making forgings of T815 truck chassis behaves widely technical adaptability to small scale production because of its structural design features which differ from those of mechanical presses. If these forgings are produced on a mechanical press, a standard press of 12.5 MN must be required. The determination of the press depends upon the strokes and daylight needed, only the force of 4 MN required to form the forgings. As viewed from metalworking capacity and tool cost, it can be seen that presses of hydraulic type are more feasible and economic for manufacturing special forgings of automotive and tractor industries than presses of mechanical type, especially the heavy truck chassis forgings. A hydraulic upset forging press is composed of two units with different functions. Each of them is basically a typical hydraulic press, but not a standard one, from the structural style point of view. They are combined into the organic whole by using the front cross-girder which behaves completely different actions in each unit. One of the units, vertical type, is designed to grip the header blank placed between the fixed and movable dies when they are closed. The other one, horizontal type, is used for heading operations after the blank is gripped firmly. The vertical unit principally includes a gripping cylinder, a slide block, used as a movable die holder here, a fixed die holder and a pre-stressed frame. The frame consists of upper and lower crossheads, a front cross-girder and four tension bolts. In whole unit by joining crossheads with a cross-girder by tension bolts, the cross-girder is used as two special square sleeves instead of inside nuts. There are similarities between horizontal and vertical units in their construction. The horizontal unit is mainly composed of a cylinder, a slide and a pre-stressed framework. In this unit a slide, as a punch holder, is equipped with a header ram and driven by upsetting cylinder assembly to squeeze the plastic metal with ram to final shape. Only in this unit, is the front cross-girder used as a usual crosshead, no longer special sleeves, as a conventional crosshead in horizontal frame. The structure of the cross-girder must be so designed that the die cavity is located at the appropriate distance behind the front surface of the cross-girder and there is the smallest eccentric load on the gripping frame. For this reason the problems of structure design and strength-stiffness analyses of a cross-girder become complicated. Obviously, the front cross-girder is a very important part in design and application. The design of the cross-girder supporting the upsetting force acting on the surfaces of the front guide body with a uniformly distributed load was well made. The actual front cross-girder used in the press is strong and rigid enough, and has good whole service behaviour under loads. Hydraulic cylinders are the same important parts as the cross-girder in the press. As a general rule, the structural style and the overall dimensions of the cylinder must be so determined that the press body be compact and, and maintenance convenient. According to this principle, a removable bottom structure is brought into practice. Although this type of press is developed for a special purpose, it has widely techno-economic adaptability to many kinds of similar forgings owing to its design features summarized as follows: 1) the stroke and the daylight may be larger than those of mechanical presses as well as the length of the stroke may be adjusted to whatever is needed; 2) the pre-stressed frameworks without inside nuts are employed so that the press have high strength and rigidity against eccentric loads.
Подвижный держатель штампа, с точки зрения структуры, вместо внутренних гаек, производство в малых количествах, удобный в эксплуатации, особенность структурной конструкции, который выполняет совершенно другие действия, состоит главным образом из…, бесперебойно работает при нагрузках, по этой причине, равномерно распределённая нагрузка, как правило, отсек цилиндров высадочного пресса.
1. What makes an oil hydraulic drive horizontal upset forging press available for making forgings of TB 15 truck chassis? 2. Could you call different functions of two units a hydraulic upset forging press composed of? 3. Will you list the main parts of the press and give their technical characteristics? 4. Why do the problems of structure design and strength-stiffness analyses of the cross-girder become complicated? 5. What causes techno-economic adaptability of this type of press? Could you summarize its design features?
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