1. Find in the text:

a) synonyms for the following words: big, manufacture, to move, part, design, to use, to place, with the aid of

b) antonyms for the following words: moving, difficulty, rarely, exclude, downtime.

2. Find English equivalents:

оборудование характеристика, работа используемый зажим, крепления автоматически меньше оборудовать требование

- machine, machinery, machining - perform, performing, performance - employ, employed, employment - clamping, clamped, clamp - automatics, automatical, automation, automatically - small, smaller, smallest - equipped, equip, equipment, equipping - required, requiring, requirement

3. Make sentences out of the two parts:

Radial drills are intended Self-propelled radial drills are The arm has horizontal ways The primary cutting motion in a radial drill Speeds and feeds are changed The head Ball-types safety clutch

Along which the drill head travels. Is clamped rigidly in the required position. By either electromechanical or hydraulic means. Frequently employed in bridge building. For machining large heavy work with a great number of cutting tools. Protected the motor against overload. Is speed rotation.

4. Translate the following in writing.

Check your knowledge of the new lexics:

1. Drill head in one of the principal units of a drilling machine.

2. In radial drills the spindle axis is made to coincide with the axis of the hole being machined.

3. Self-propelled radial drills are employed in bridge building.

4. The arm has horizontal ways along which the drill head travels.

5. Clamping and unclamping of the arm are automatically interlocked with the arm traverse along the column.

6. The base is a grey iron casing stiffened by internal ribbing.

7. The drill head is a self-contained unit combing the speed and feed gearboxes.

5. Make a brief summary of the text.

DISCUSSION

Working in pairs role-play the following situations:

1. You are in a laboratory of drilling machines. The teacher is showing you different types of them paying attention to the peculiarities in their arrangement. Ask him questions to get more detailed information.

2. You are going to carry out research using drilling machines. Ask your teacher which one is more suitable for your work and why.

Unit 5 grinding and grinding machines

T ext 1

Purpose and Field of Application of Grinding Machines

A distinguishing feature of grinding machines is the rotating abrasive tool. This group of machines is employed chiefly for finish machining operations, accomplished by removing layers of metal from the work surface with an accuracy that may reach tenth of a micron, and producing a very high class of surface finish.

Grinding machines handle workpieces that have been previously machined, in most cases, in other types of machine tools. The magnitude of the grinding allowance depends upon the required class of accuracy, size of the work and the preceding machining operation to which it has been subjected.

Improvements made in recent years in blank manufacture (rolling, drop forging and other precision casting processes) enable high-production grinders to be used in many cases for rough and finish grinding instead of lathes, milling and other machines performing semifinishing operations.

Operations efficiently performed by grinding machines include: a) roughing and cutting off blanks; b) precise machining of various surfaces; surfaces of revolution, profiles of gear teeth, thread and other helical surfaces, contoured surfaces, etc.; c) sharpening all types of cutti2ng tools.

Grinding machines find application in all branches of the engineering industries. There are general- and single-purpose grinding machines. In accordance with the ground surface and the type of grinding they do, general-purpose grinding machines can be classified into the following main types: cylindrical, internal, surface and centerless grinding machines.

The accuracy of surfaces machined in grinders depends upon the type of operation being performed (cylindrical grinding, internal grinding, etc.) and the grinding speeds and feeds.

EXERCISES

1.2 Name the main points of the text answering the following questions:

1. What is the main distinguishing feature of grinding machines?

2. Where is this group of machines employed?

3. What does the magnitude of grinding allowance depend upon?

4. Can you name the operations performed by grinding machines?

5. What types of general-purpose grinding machines do you know?

2. Find English equivalents to the following Russian words and word-combinations:

чистовая обработка, отшлифованная поверхность, специализированный шлифовальный станок, поверхности вращения, усовершенствование, степень точности, производств заготовок, подвергать, высокопроизводительный.

3. Find in the text synonyms for the following English words:

mainly, sphere, to fulfill, workpiece, formerly, precision, to use.

4. Find in the text verbs for the following nouns:

employment, removal, production, machining, dependence, requirement, subject, performance.

5. Make up questions to which the underlined words are answers:

1. The group of grinding machines is employed chiefly for finish machining operations.

2. Grinding machines find application in all branches of engineering.

3. The magnitude of grinding allowance depends upon the required class of accuracy, size of the work and preceding machining operations.

4. A distinguishing feature of grinding machines is the rotating abrasive tool.

6. Summarize the text.