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 cutting 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. 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, производство заготовок, подвергать, высокопроизводительный.

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

Mainly, sphere, to fulfil, 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 italicized 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.