Grinders

Grinders (шлифовальные станки)remove metal by a rotating abrasivewheel. The wheel is composed of many small grains of abrasive,bonded together, with each grain acting as a miniature cutting tool. The process gives very smooth and accurate finishes. Only a small amount of material isremoved at eachpass of the wheel, so grind­ing machines requirefine wheel regulation. The pressure of the wheel against the workpiece is usually very light, so that grinding can be carried out onfragile materials that cannot be machined by otherconventional devices.

Vocabulary:

milling machine —фрезерный станок

series — серия, ряд

cutting edge — режущий край, острие

circumference — окружность

to feed— подавать

longitudinal— продольный

horizontal — горизонтальный

vertical — вертикальный

versatile — универсальный

flat— плоский

contoured — контурный

angle— угол

slot — прорезь, паз

gear teeth— зубья шестерни

drill — дрель, сверло, сверлить

hole — отверстие

to enlarge— увеличивать

thread— резьба

portable— портативный

unit— единица, целое, узел

previously — ранее

to slide — скользить

stroke— ход

lateral — боковой

displacement— смещение

straight— прямой

idle— на холостом ходу

workshop — цех, мастерская

to mount — крепить

holder — держатель

to execute— выполнять

simultaneous — одновременный

multiple — многочисленный

grinder— шлифовальный станок

wheel — круг, колесо

bonded — скрепленный

to remove — удалять

pass— проход

fine — точный

conventional — обычный

device — устройство, прибор

fragile — хрупкий

General understanding:

1. What is the shape of a cutter in a milling machine?

2. What moves in a milling machine, a table or a cutter?

3. What possible movements has the table of a milling machine?

4. What kind of surfaces and shapes may be machined by a milling machine?

5. What can we use a drilling machine for?

6. What kinds of drilling machines exist?

7. What is rotated while boring, a cutter or a work-piece?

8. Describe the work of a shaper (planer).

9. What must be done to execute multiple simultane­ous cuts on a planer?

10. What is the working tool in a grinder?

11. Can we obtain a very smooth surface after grind­ing and why? 12. Can we grind fragile materials and why?

Exercise 4.3. Translate into English:

1. Токарный станок все еще остается самым важ­ным станком.

2. Все современные токарные станки оборудованы электроприводами.

3. Движение инструмента контролируется с высо­кой точностью.

4. Электропривод позволяет обрабатывать заготов­ку на различных скоростях.

Text D: «DIES»

Dies are tools used for the shaping solid materials, especially those employed in the pressworking of cold metals.

In presswork, dies are used in pairs. The smaller die, orpunch, fits inside the larger die, called thematrix or, simply, the die. The metal to be formed, usually a sheet, is placed over the matrix on the press. The punch is mounted on the press and moves down by hydraulic or mechanical force.

A number of different forms of dies areemployed for different operations. The simplest arepiercing dies(пробивной штамп), used forpunching holes. Bending and folding diesare designed to make single or compound bends. A combination die is designed to perform more than one of the above operations in one stroke of the press. A progressive die permits successive forming op­erations with the same die.

In coining, metal is forced to flow into twomatchingdies, each of which bears a engraved design.