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Drilling and Boring Machines




To drill a hole usually hole-making machine-tools are used. They can drill a hole according to some specification, they can enlarge it, or they can cut threads for a screw or to create an accurate size or a smooth finish of a hole.

Drilling machines ( ) are different in size and function, from portable drills to radial drilling machines, multispindle units, automatic production machines, and deep-hole-drilling machines.

Boring () is a process that enlarges holes previously drilled, usually with a rotating single-point cutter held on a boring bar and fed against a stationary workpiece.

Shapers and Planers

The shaper (- ) is used mainly to produce different flat surfaces. The tool slides against the stationary workpiece and cuts on one stroke, returns to its starting position, and then cuts on the next stroke after a slight lateral displacement. In general, the shaper can make any surface having straight-line elements. It uses only one cutting-tool and is relatively slow, because the return stroke is idle. That is why the shaper is seldom found on a mass production line. It is, however, valuable for tool production and for workshops where flexibility is important and relative slowness is unimportant.

The planer (- ) is the largest of the reciprocating machine tools. It differs from the shaper, which moves a tool past a fixed workpiece because the planer moves the workpiece to expose a new section to the tool. Like the shaper, the planer is intended to produce vertical, horizontal, or diagonal cuts. It is also possible to mount several tools at one time in any or all tool holders of a planer to execute multiple simultaneous cuts.

Grinders

Grinders ( ) remove metal by a rotating abrasive wheel. 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 is removed at each pass of the wheel, so grinding machines require fine wheel regulation. The pressure of the wheel against the workpiece is usually very light, so that grinding can be carried out on fragile materials that cannot be machined by other conventional devices.

Vocabulary:


milling machine

series ,

cutting edge ,

circumference

to feed

longitudinal

horizontal

vertical

versatile

flat

contoured

angle

slot ,

gear teeth

drill , ,

hole

to enlarge

thread

portable

unit , ,

previously

to slide

stroke

lateral

displacement

straight

idle

workshop ,

to mount

holder

to execute

simultaneous

multiple

grinder

wheel ,

bonded

to remove

pass

fine

conventional

device ,

fragile


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. .

2. .

3. .

4. .

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, or punch, fits inside the larger die, called the matrix 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 are employed for different operations. The simplest are piercing dies ( ), used for punching holes. Bending and folding dies are 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 two matching dies, each of which bears a engraved design.

Wiredrawing Dies

In the manufacture of wire, a drawplate ( ) is usually employed. This tool is a metal plate containing a number of holes, successively less in diameter and known as wire dies. A piece of metal is pulled through the largest die to make a coarse wire. This wire is then drawn through the smaller hole, and then the next, until the wire is reduced to the desired measurement. Wiredrawing dies are made from extremely hard materials, such as tungsten carbide or diamonds.

Thread-Cutting Dies

For cutting threads on bolts or on the outside of pipes, a thread-cutting die ( ) is used. It is usually made of hardened steel in the form of a round plate with a hole in the centre. The hole has a thread. To cut an outside thread, the die is lubricated with oil and simply screwed onto an unthreaded bolt or piece of pipe, the same way a nut is screwed onto a bolt. The corresponding tool for cutting an inside thread, such as that inside a nut, is called a tap ().

Vocabulary:


chip

sharp

friction

content

range

inexpensive

to permit ,

common

tungsten

ingredient

diamond

tips

ceramic

truing , ,

die ,

matrix

to employ

to pierce ,

to punch

matching ,

coarse

wire

to draw ,

thread

hardened

to lubricate

to screw

nut

outside ,

inside ,


Exercise 4.4. Find English equivalents in the text:


1.

2.

3.

4.

5.

6.

7.

8.


 

Exercise 4.5. Translate the following sentences into Russian:

1. .

2. .

3. , .

4. , .

5. .

6. .

7. .

8. .





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