Electron Beam

Date: 2015-10-07; view: 411.

Ultrasonic

Electrochemical

Electrochemical machining (ECM) also uses electrical energy to remove material. An electrolytic cell is created in an electrolyte material where the tool is the cathode and the workpiece is the anode. A high-amperage, low-voltage current is used to melt the metal and to remove it from the workpiece.

Ultrasonic machining (USM) employs high-frequency, low-amplitude vibrations to create holes. A vibrated tool is placed against the workpiece while a mixture of fine abrasive and water flows between them. The friction of the abrasive particles cuts the workpiece. Materials such as hardened steel, carbides, rubies, quartz, diamonds can easily be machined by USM.

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. The electrons are directed against an accurately limited area of the workpiece; on impact, the kinetic energy of the electrons is converted into thermal energy that melts and vaporizes the material forming holes or cuts. EBM equipment is commonly used by the electronics industry to make circuits in microprocessors.

Задания к тексту B:

I. Найдите в тексте английские эквиваленты следующим русским выражениям:

электрохимическая обработка; ультратвердые сплавы; пульсирующий высокочастотный электрический ток; электроннолучевая обработка; необычные станки; лазерно-лучевая обработка; высокочастотные колебания с небольшой амплитудой; точное манипулирование лучом когерентного света; плазменная обработка; обработка ультразвуком; обработка посредством электрического разряда; приблизительно три четверти от скорости света; электролитическая ячейка; высокоскоростная струя горячего газа; высокий ток с низким напряжением.

II. Сформулируйте в нескольких словах содержание каждого абзаца.

III. Напишите резюме к тексту.

IV. Ответьте на вопросы:

1. What machines do unconventional machine tools include?

2. What were these machine tools primarily developed for?

3. What does plasma-arc equipment employ to melt material?

4. What materials can be cut with plasma-arc equipment?

5. What is laser-beam machining used for?

6. What energy does electrodischarge machining employ to remove metal from the workpiece without touching it?

7. In what material is an electrolytic cell created?

8. What current is used in electrochemical machining?

9. What does ultrasonic machining (USM) employ to create holes and other cavities?

10. What cuts the workpieces in ultrasonic machining?

11. What materials can be machined with USM?

12. What velocities are electrons accelerated to in electron-beam machining?

13. Where is the process performed and why?

14. Where is the EBM equipment commonly used?

V. Перескажите текст, используя в качестве плана вопросы предыдущего упражнения.