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Cylindrical Grinding Machines
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Cylindrical Grinding Machines are intended for grinding external cylindrical and tapered surfaces, and are further subdivided into universal and plane types.
In addition to the small table swivel (up to + 6°), universal cylindrical grinders also provide for swivelling the workpieces and the grinding wheel by swivelling headstock, wheel head about their vertical axes to a large angle. This enables steep tapers and end faces to be ground in these machines. Universal grinders are usually equipped with an additional head or attachment for grinding holes.
In a plain cylindrical grinder only the work table can be swivelled through an angle of + 6°. This is used for grinding tapers with a small included angle.
The capacity of a cylindrical grinder is specified by the maximum diameter and length of workpiece that can be accommodated. In the general-purpose grinders, the maximum workpiece diameter ranges from 100 to 1, 600 mm, and the maximum length from 150 to 12, 500 mm.
Up-to-date cylindrical grinding machines operate on a semiautomatic or automatic cycle and can be efficiently employed for mass, lot and piece production. Many models have provision for installing an automatic in-process size control device. The roughness value of surfaces ground in cylindrical grinders should be within the values stipulated for the 4th and 5th classes after rough grinding, 7th and 8th classes after finish grinding and 8th through 11th classes after precision grinding according to the standards used in our country.
Cylindrical grinders can be employed for:
1. Traverse and plunge-cut grinding with manual controls.
2. Traverse grinding to a stop with automatic infeed during table reversal.
3. Plunge-cut grinding to a positive stop on a semiautomatic operating cycle.
EXERCISES
1. Name the main points of the text answering the following questions:
1. What are cylindrical grinding machines intended for?
2. What types of them do you know?
3. Can you say anything about the construction arrangement of universal cylindrical grinding machines?
4. How is the capacity of a cylindrical grinder specified?
5. How do up-to-date grinders operate from the point of view of automation?
6. What can cylindrical grinders be employed for?
2. Guess the meaning:
1. It is intended for grinding external cylindrical and tapered surfaces.
2. It is equipped with an additional attachment for grinding holes.
3. It is specified by the maximum diameter and length of workpiece that can be accommodated.
4. It is used for grinding tapers with a small included angle.
3. Choose the definition that fits each word or phrase as it is used in the text:
| 1. to grind | 2. plain |
| a) crush into grains or powder | a) straightforward, candid |
| b) oppress or crush by cruelty | b) unmistakable, easy to see or hear or understand |
| c) sharpen or smooth by friction | c) not elaborate or intricate, not luxurious, without flavoring |
| 3. to range | 4. value |
| a) vary between limits | a)the amount of money or other commodity considered to be equivalent to something else |
| b) extend, reach | b) the amount or quantity denoted by a figure etc., |
| c) arrange in a row or ranks or in a specified way | c) desirability, usefulness, importance |
4. Find in the text verbs for the following nouns:
Subdivision, provision, equipment, swivel, accommodation, operation, installation employment.
5. Underline the suffixes in the following words and state what part of speech they belong to:
Cylindrical, subdivided, addition, attachment, automatic, efficiency, roughness, precision, grinder.