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UNCONVENTIONAL MACHINE TOOLS
Unconventional machine tools employ light, electrical, chemical, and sonic energy; superheated gases; and high-energy particle beams to shape the exotic materials and alloys that have been developed to meet the needs of modern technology. Unconventional machine tools include plasma-arc, laser-beam, electro discharge, electrochemical, ultrasonic, and electron-beam machines. These machine tools were developed primarily to shape the ultrahard alloys used in heavy industry and in aerospace applications and to shape and etch the ultrathin materials used in such electronic devices as microprocessors. Numerical control of machine tools and flexible manufacturing systems have made it possible for complete systems of machine tools to be used for the manufacture of a range of products.
Plasma Arc. Plasma-arc machining (PAM) employs a high-velocity jet of high-temperature gas to melt and displace material in its path. The materials cut by PAM are generally those that are difficult to cut by any other means, such as stainless steels and aluminum alloys.
Laser. Laser-beam machining (LBM) is accomplished by precisely manipulating a beam of coherent light to vaporize unwanted material. LBM is particularly suited to making accurately placed holes. The LBM process can make holes in refractory metals and ceramics and in very thin materials without warping the workpiece. Extremely fine wires can also be welded using LBM equipment.
Electrodischarge. Electrodischarge machining (EDM), also known as spark erosion, employs electrical energy to remove metal from the workpiece without touching it. A pulsating high-frequency electric current is applied between the tool point and the workpiece, causing sparks to jump the gap and vaporize small areas of the workpiece. Because no cutting forces are involved, light, delicate operations can be performed on thin workpieces. EDM can produce shapes unobtainable by any conventional machining process.
Electrochemical.Electrochemical machining (ECM) also uses electrical energy to remove material. An electrolytic cell is created in an electrolyte medium, with the tool as the cathode and the workpiece as the anode. A high-amperage, low-voltage current is used to dissolve the metal and to remove it from the workpiece, which must be electrically conductive. A wide variety of operations can be performed by ECM; these operations include etching, marking, hole making, and milling.
Ultrasonic. Ultrasonic machining (USM) employs high-frequency, low-amplitude vibrations to create holes and other cavities. A relatively soft tool is shaped as desired and vibrated against the workpiece while a mixture of fine abrasive and water flows between them. The friction of the abrasive particles gradually cuts the workpiece. Materials such as hardened steel, carbides, rubies, quartz, diamonds, and glass can easily be machined by USM.
Electron Beam. In electron-beam machining (EBM), electrons are accelerated to a velocity nearly three-fourths that of light. The process is performed in a vacuum chamber to reduce the scattering of electrons by gas molecules in the atmosphere. The stream of electrons is directed against a precisely limited area of the workpiece; on impact, the kinetic energy of the electrons is converted into thermal energy that melts and vaporizes the material to be removed, forming holes or cuts. EBM equipment is commonly used by the electronics industry to aid in the etching of circuits in microprocessors.
Exercise 6.Answer the questions to the text:.
1) What types of unconventional machine tools do you know?
2) What were unconventional machine tools developed for?
3) How does PAM work?
4) Which of the tools is particularly suited to making accurately placed holes?
5) Do the terms “electrodischarge machining” and “spark erosion” mean the same?
6) What types of unconventional machine tools use electric energy to remove material?
7) What sorts of operations can be performed by ECM?
8) What materials can be machined with the help of USM?
9) Describe the working mechanism of EBM.
Exercise 7. Find the English equivalents in the text:
Специальные станки, быстрая частица, формовать сверхжесткие сплавы, сверхтонкие материалы, гибкая система производства, нержавеющая сталь, растворять металл, электрическая энергия, проводимость, ток, обрабатывать, сплав алюминия, вакуумная камера, фрезерование, высокочастотный, деформировать материал.
Exercise 8. Look through the sentences and say if they are true (T) or false (F):
1) Unconventional machine tools are used to generate light, electrical, chemical, and sonic energy.
2) These machine tools were developed primarily to shape the ultrahard alloys.
3) Plasma-arc machining (PAM) employs a high-velocity jet of high-temperature gas to melt and displace material in its path.
4) The materials cut by PAM are generally those that are difficult to cut by any other means.
5) The LBM process can’t be applied to refractory metals, ceramics and very thin materials as it can warp the workpiece.
6) EDM employs electrical energy to remove metal from the workpiece without touching it.
7) Electrochemical machining (ECM) uses sonic energy to remove material.
8) For ECM the workpiece mustn’t be electrically conductive.
9) In ultrasonic machining the friction of the abrasive particles gradually cuts the workpiece.
10) While using EBM a beam of light is directed against a precisely limited area of the workpiece.
Exercise 9.Match the terms with the definitions below:
Plasma-arc machining, laser-beam machining, electrodischarge machining, electrochemical machining, ultrasonic machining, electron-beam machining.
1) Uses electrical energy to remove material.
2) Employs a high-velocity jet of high-temperature gas to melt and displace material in its path.
3) Uses accelerated electrons to a velocity nearly three-fourths that of light.
4) Employs electrical energy to remove metal from the workpiece without touching it.
5) Employs high-frequency, low-amplitude vibrations to create holes and other cavities.
6) Is accomplished by precisely manipulating a beam of coherent light to vaporize unwanted material.
Exercise 10.Look through the text and find sentences with the infinitive. Determine the function of the infinitive.
Exercise 11. A.Remember the following verbs and expressions, after which it is necessary to use gerund:
To avoid, to burst out, cannot help, to deny, to enjoy, to excuse, to finish, to forgive, to give up, to go on, to keep (on), to mind, to postpone, to put off, to stop.
B.Now translate the sentences from Russian into English, using Gerund:
1)Мы отложили покупку новых станков до следующего месяца.
2) Он настаивал на использовании специальных станков для обработки сверхжестких сплавов.
3) Он закончил электрохимическую обработку материала.
4) Извините, что мы задержали доставку этих деталей.
5) Они не могли не согласиться, что лазер – оптимальное средство для работы со сверхтонкими материалами.
6) Я не отрицаю, что стекло, рубины и бриллианты можно легко резать с помощью ультразвуковой обработки.
7) Им нравится резать и формовать металлы, применяя станки, которые отвечают требованиям современных технологий.
8) Он избегает разговоров о закупке новых станков для их предприятия.
9) Начальник цеха любит командовать своими подчиненными и продолжает думать, что так он сможет поддерживать дисциплину.
10) Перестань нервничать! Ты не виноват, что этот станок вышел из строя!
Exercise 12.Remember the following useful expressions.
a) to ask someone for their opinion.
What do you think of his new invention?
How do you feel about working with the others?
What are your feelings about the change in the timetable?
What’s your honest opinion of that investigation?
b) to give your opinion.
I think Max had the best idea.
I don’t think he knew very much about the subject.
Personally, I think his first idea was better.
In my opinion we should sell the old car.
c) to agree with someone.
Yes, I agree.
Yes, I think you are right.
d) to disagree with someone.
Perhaps, maybe, possibly but I don’t think…
Yes, that’s true I’m not sure…
You could be right don’t forget that…
Exercise 13. Complete the sentences in at least three different ways to ask people their opinion.
1) ……………………………. the proposed changes?
2) ……………………………. the new building?
3) ……………………………. the transport system?
4) ……………………………. the new law?
Exercise 14. Fill the gaps with the correct word. (one word only)
1) A: What do you think …………….. it?
2) B: Well, ……………….. I didn’t like it.
3)……………. to the radio, we won’t know the result until tomorrow.
4) I agree with him to a certain …………….
5) As far as I’m ……., we need to buy a new photocopier immediately.
6) I’m afraid I …………………… disagree with you.
Exercise 15.Compose a dialogue.Think over different types of machine tools.
Please, imagine that you are an independent vendor of conventional machine tools, and your friend presents unconventional machine tools. Speak on their advantages, possibilities and characteristics.