Metal-cutting and locksmith's cutting tools

 

Metal cutting differs from chipping in substituting impact stresses by pressing forces in this operation. Cutting is used for separating some part from a piece of

 

 

metal as well as to cut angles, grooves and pipes. Depending upon the shape and size of workpieces cutting is done by means of different cutting tools such as pliers, bench-shears, alligator shears, hack saws and pipe-cutters made of carbon steel.

 

 

Fig. 4. Pliers:

I - cutting jaw; 2 – handle

 

Pliers, or wire-cutters (Fig. 4) are used for cutting thin wire. Pliers consist of two cutting jaws and two handles. A piece of wire is placed between the cutting jaws and the wire is cut by exerting pressure on the handles of the pliers. Bench shears are made of steel. Lateral surfaces of shear blades are hardened, sharpened and ground.

Bench-shears (Fig. 5) are provided with two handles one of which is at a right angle to the other and fixed on a bench. The length of the handle is 400-800 mm, while that of the cutting part is 100-300 mm. The material is cut by pressing on one of the handles.

 

 

Fig. 5.

Bench-Shears: 1 - shear blade; 2 – handle

 

 

Fig.6. Hack Saw:

1 - frame; 2- toothed blade

 

A hack saw (Fig. 6) is used for cutting thick metal sheets, bars, round-shaped material, etc. The hack saw consists of a frame and a long toothed blade made of tool carbon steel. The teeth on the blade are hardened. The blades with different pitches have different applications, the pitch of the blade depending on the material to be sawed. The thinner the material to be handled, the finer must pitch be the pitch of the blade used for sawing this material, and vice versa.

Fig. 7 shows alligator shears which is a heavy duty machine used for cutting materials of large sections such as pipes, beams, auto frames, axles and different types of industrial scrap. The alligator shears consist of cast iron bed I and bedplate 2. Arm 3 is mounted on the bedplate. Cutting blade 4 is fixed within the arm.

Electromotor 5 imparts reciprocating motion to the arm and the blade. The workpiece to be cut is clamped in machine vice 6.

 

 

Fig.7. Alligator Shears:

1 - bed; 2 - bedplate; 3 - arm; 4 - cutting blade;

5 - electromotor; 6 - machine vice

 

 

Fig. 8. Pipe-Cutter:

1 - body; 2 - rollers; 3 - roller; 4 – handle

 

Special pipe-cutters (Fig. 8) serve for cutting pipes. The pipe-cutter consists of body 1, handle 4, and three steel cutting rollers. Two rollers 2 installed on the fixed axles of the body and roller 8 installed on the axle of the handle may revolve and cut a pipe fixed in a special pipe fixture. For this purpose the pipe-cutter is turned round the pipe to be cut, pressing the cutting rollers against its surface.

 

Exercises

 

I. Use the following words and phrases in sentences of your own:

 

bedplate, arm, pitch, bar, lateral, metal cutting tools, pliers, pipe-cutters, hack saw, cutting jaws, to harden, right angle, bench-shears, to press, bed, industrial scrap, groove, to impart, reciprocating motion, to install, fixture, body

II. Supply the missing words:

 

l. The p... of a blade is the distance from the point of one t... to the point of the next t.... 2. This pitch is expressed by the number of t... per one inch of the b... length. 3. The hand hacksaw blade is a thin blade with teeth formed on one е.... 4. The flexible h... s... blade is used for s...ing tin, copper, aluminium and other soft metals. 5. Cutting is done by means of different c... t.... 6. For cutting wire such cutting t... as p... are used. 7. One handle of b...-s... is at a r... a... to the other.

III. Translate the following sentences into English using the infinitive instead of the attributive clauses:

 

 

Example: Материал, который нужно разрезать, зажимается в тисках.

The metal to be cut is clamped in the vice.

 

1. Шаг полотна ножовки зависит от материала, который будет распиливаться. 2. Различные виды стали, которые используются для полотна ножовок, изготовляются на нашем заводе. 3. Полотно ножовки, которое надо использовать для распиливания этих тонких листов, должно иметь 32 зуба на один дюйм. 4. Труба, которую надо разрезать труборезом, будет закреплена в специальном приспособлении, 5. При вращении трубореза вокруг изделия, которое надо разрезать, создается режущее усилие.

 

IV. Make up questions to which the italicized words are the answers:

 

1. This bar is subjected to the action of two sets of external forces. 2. Cutting is used in cases when it is necessary to separate a piece of metal. 3. Thin wire is cut with pliers. 4. Sheets of metal are cut with bench-shears. 5. Cutting tools are made of carbon steel. 6. Pliers consist of two cutting jaws and two handles.

V. Giving the answers to the following questions describe the principle of operation of pliers, bench-shears, and alligator shears and pipe-cutter shown in Figs 4, 5, 7, and 8:

 

l. What are pliers used for? 2. What do the pliers consist of? 3. What is the function of pliers, jaws and handles? 4. What material are bench-shears made of? 5. What are the bench-shears provided with? 6. What purposes are alligator shears used for? 7. What principal parts do the alligator shears consist of? 8. What part of the alligator shears is the arm mounted on? 9. Where is the cutting blade of the alligator shears fixed? 10. What motion does the electromotor impart to the arm and the blade? 11. What purpose are pipe-cutteres used for? 12. What parts coes a pipe-cutter consist of? 13. How is the cutting performed? 14. Where is the pipe fixed for cutting?

FILING AND FILING TOOLS

 

Filing is the most widely used fitting operation in the practice of metalworking shops "used for cutting metal by means of a tool known as a file. By means of a file it is possible to give a different shape and size to a workpiece, to fit one part to another, etc.

The most widely used operations with a file are: (1) filing separate surfaces, (2) filing mating surfaces, (3) filing holes.

A file is a hardened steel bar having a great number of fine cutting edges or teeth running diagonally across its face. These teeth can remove fine chips from a treated workpiece. A file differs from a chisel in having a large number of cutting points instead of one cutting edge and in being driven directly by hand instead of by hammer.

There are various kinds of files applied for finishing different workpieces depending on the shape of their surfaces (Fig. 9).

Flat files are used for filing flat surfaces but the shape of the files is not quite flat because if the file had been made quite flat, it would have prevented the

 

 

production of a flat surface, as the file would have cut away at the edges of a work and would have left a convex surface.

For filing convex and concave surfaces half-round files are used. A half-round file is made with a convex surface to prevent all the teeth from cutting at the same time, which requires too' much pressure on the file, as well as to prevent the file from bending.

Square files are applied for filing square holes and rectangle grooves, while triangular or three-square files are used for filing angles.

Round files are used for filing round holes of small diameters, and for filing metal in narrow plates diamond shaped files made of copper strip into which diamond powder has been hammered, or knife files are used.

For filing soft metals rasp files or rasps are employed.

 

Exercises

 

I. Use the following words and phrases in sentences of your own:

 

to file, to fit, mating surfaces, face, a great number of, convex surfaces, triangular file, to prevent, strip

II. Retell the text giving answers to the following questions.

 

1. What is filing? 2. What tools are used for filing operations? 3. What operations are performed with a file? 4. What is the difference between a file and a chisel? 5. How is cutting performed with a file? 6. What files are used for filing depending on the shape of the surfaces to be finished?

 

 

knife file
rhombic file, diamond-shaped file
round file
triangular file
square file
half round file
flat file

 

Fig.9. Files

a- edge; b- face; c- handle

 

III. Supply antonyms for the following words:

 

flat, convex, soft, different

IV. Give the derivatives from the following words and translate them into Russian:

 

to differ, to operate, file, to fit, diagonal, to finish, to separate

V. Change the following sentences using the subordinate clauses instead of participle phrases and translate the sentences into Russian:

Example: Files with convex surfaces, preventing all their teeth from cutting at the same time, are used for filing convex and concave surfaces. Files with convex surfaces which prevent all their teeth from cutting at the same time are used for filing convex and concave surfaces.

 

 

 

1. Files are generally made with convex surfaces being thicker in the middle than at the ends. 2. Files having various shapes of cross-section such as square, flat, round, etc. are used in metal-cutting practice. 3. When filing convex surfaces one uses a half-round file. 4. A file is an instrument having teeth on its face. 5. Files are tools belonging to the group of locksmith's cutting instruments. 6. Files having single cut teeth are called "single-cut files". 7. For removing a large amount of metal one uses a coarse-pitched file.

VI. Make up questions to which the italicized words are the answers:

 

1. A file has a great number of fine cutting teeth. 2. These teeth are used for removing chips from the workpiece to be treated. 3. Depending on the shape of the surfaces to be filed various kinds of files are used. 4. No, flat files are not used for filing round holes. Round files are used. 5. No, knife files are not used for filing soft metals, but rasps are used. 6. Yes, diamond-shaped files are used for filing metal in narrow, places.

VII. Giving answers to the following quest ions describe Fig. 9:

 

1. What is a file? 2. What principal parts does a file consist of? 3. In what cases is a square file used? 4. Which file is used for filing angles'? 5. What material are diamond-shaped files made of? 6. In what cases are knife files used?

 

MECHANICAL TOOLS

 

Both in maintenance and in repair of machines all kinds of fitting operations are applied. An important role is played by disassembling and assembling operations. Special instruments are used for performing these operations.

Among the variety of mechanical tools used for disassembling and assembling machine parts and in their repairing are wrenches (Fig. 10). According to their construction and application wrenches may be of different types: single-ended and double-ended nut wrenches, adjustable wrenches, socket wrenches and special wrenches.

 

 

Fig. 10. Wrenches:

1-single-ended wrench (a- handle; b- head; c- span);

2- double-ended wrench; 3- adjustable wrench; 4- socket wrench

 

A nut wrench is used for screwing and unscrewing nuts. It consists of a handle and a head with an opening known as the span.

Adjustable wrenches may be used for unscrewing nuts and bolts of different dimensions.

 

Socket wrenches are applied in cases when nuts or bolt heads located in recesses are hardly accessible for a nut wrench.

Special wrenches are used for unscrewing and screwing nuts of a definite type.

Wrenches are used by drivers for repairing cars, in locksmith's shops and fitter's shops. Fitters use them to screw different types of machine parts as: washers, bolts, shafts, etc. Plumbers use them to repair pipes, taps, etc. Besides different types of wrenches there are round pliers or needle nose pliers which are widely used by locksmiths, electricians and other specialists for gripping, screwing or cutting off thin metal and wires.

 

Exercises

 

I. Use the following words and phrases in sentences of your own:

 

nut, to screw, to maintain, to unscrew, to assemble, to disassemble, nut wrench, adjustable wrench, socket wrench, to grip, plumber, electrician, fitter

II. Answer the following questions:

 

l. What operations are applied in maintenance and repair of machines? 2. What instruments are used for disassembling and assembling machine parts? 3. How are wrenches subdivided? 4 What is a nut wrench used for? 5. When are adjustable wrenches applied? 6. In what cases are socket wrenches used? 7. What wrenches are used for screwing and unscrewing nuts? 8. By whom are different wrenches used? 9. What other mechanical tools can be used in repairing?

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

 

to maintain, to operate, to construct, to fit, to assemble; to apply

IV. Supply antonyms for the following words:

 

disassembling, to screw, difficult, single-ended, accessible

V. Supply synonyms for the following words:

 

to locate, to grip, widely, different, dimensions

VI. State the functions of all the -ed forms and translate the following sentences into Russian:

 

1. Wrenches used to unscrew and screw nuts are known as adjustable wrenches. 2. Different wrenches are used to screw different types of machine parts, such as washers, bolts and shafts. 3. Locksmiths and fitters use special

 

 

instruments depending on the parts of machines to be disassembled and assembled. 4. Nut wrenches may be used for screwing different nuts. 5. Tools called "wrenches" are used for turning bolts and nuts. 6. Tools known as S-wrenches, angle wrenches, etc. are named so according to their shape. 7. The wrenches may also be named from the object on which they are used. 8. Adjustable wrenches are named so because they may be applied for screwing and unscrewing bolts and nuts of different sizes.

VII. Translate the following sentences into English:

 

1. Обычно механические ключи, используемые при ремонте разнообразных деталей, изготовляются из прочной стали. 2. Кусачки могут применяться для операций, выполняемых слесарями. 3. Торцовый ключ может применяться для завинчивания гаек, расположенных в углублениях. 4. Слесарь часто пользуется инструментами, называемыми разводными ключами. 5. Среди многих инструментов, применяемых электриками, есть круглогубцы.

MEASURING TOOLS AND DEVICES

 

A. MEASUREMENT

 

The size and shape of all machine parts should be in accordance with the corresponding drawing. The produced parts should be checked by means of measurement, which generally involves comparison either with some accepted standard or with a mating part. The significance of any measurement is determined by the degree of accuracy to which the parts may be measured.

Depending on measurements different measuring tools can be used such as rules, slide gauges, vernier calipers, depth gauges, dial indicators, micrometers, clearance gauges, inside and outside calipers, plug gauges, bevels, universal protractors, etc.

 

B. MEASURING TOOLS

 

When accurate measurement of the part is required, the vernier calipers, micrometers and slide gauges are used. When it is not so important to have an accurate measurement of the part, metal rules, inside calipers and outside calipers will do.

 

 

Fig. 11. Steel Rule

 

 

 

Fig. 12.Calipers:

a-inside; b-spring; c- outside

 

Steel rules (Fig. 11) serve for determining the length and sometimes the depth of the part to be measured. Steel rules are graduated in millimeters, but in the USA and England they are graduated in thirty-seconds and sixty-fourths of an inch¹.

The outside (Fig. 12) calipers are the simplest instruments for measuring external diameters of the part. The outside caliper consists essentially of two curved legs.

The inside calipers are used for determining the internal diameters of the part. Its construction is almost similar to that of the outside calipers. Sometimes the outside calipers may be used for measuring internal diameters of the part. The outside and inside caliper measurements may be read by placing the legs of the calipers on a rule and placing one leg and the end of the rule against a flat surface as shown in Fig. 11.

 

 

Fig. 13. Vernier Calipers:

1, 2, 3, 8 -jaws; 4 - adjusting screw; 5 - primary scale; 6 - depth rod;

7 - frame with vernier

 

 

Fig. 14. Micrometer:

1 - frame; 2 - anvil; 8 - spindle; 4 - lock nut; 5 - barrel;

6 - thimble; 7 - ratchet thimble

 

Vernier calipers (Fig. 13) can be used for measuring both external and internal sizes of a part. By using vernier calipers measurements up to.001" may be

determined. Vernier calipers consist of a primary steel scale and four jaws. Jaws 1 and 2 are integral with the scale. Jaws 8 and 8 are attached to the frame sliding along the scale. The frame may be clamped on the scale in any position by means of an adjusting screw. External surfaces may be measured with jaws 1 and 8, while internal surfaces are measured with jaws 2 and 8. The depth of recesses is measured with a depth rod 6. A vernier on the frame 7 serves for measuring fractional parts of a millimeter.

The micrometer (Fig. 14) is an instrument for precise measurement of length and thickness of a part to one ten thousandth of an inch. The principle of operation is similar to that of vernier calipers. A graduated thimble serves as the primary scale. The scale on the barrel of the micrometer is used for the vernier reading. The part to be measured is placed between the anvil and micrometer screw, which is called a "movable spindle". By rotating the thimble, the spindle is removed or approached to the anvil. By rotating the ratchet thimble the spindle is moved and thus the part is pressed to the anvil. Thereupon the rotation of the ratchet thimble is discontinued, the micrometer opening is fixed by the lock nut and the reading is taken. The micrometer reading is the sum total of the barrel divisions, the thimble divisions with respect to the axial line on the barrel, and the vernier reading.

 

 

Fig. 15. Dial Indicator: I - dial; 2 - indicator pointer; 3 - test point

 

Fig. 15 shows a dial indicator. The dial indicator is a gauge with a graduated dial and an indicator pointer connected to a test point by a system of levers. Any movement of the test point is magnified by the indicator pointer. The dial indicator is used to check the shape of a part., the precision of its machining, as well as for checking the accuracy of cutting machines.

 

 

Fig. 16. Go and No-Go Plug Gauge:

1 - go plug gauge; 2 - handle; 3 - no-go plug gauge

 

 

Thread plug gauges or internal gauges, being of "go" and "no-go" type (Fig. 16), are generally used for testing threads or tapped holes.

 

 

Fig. 17. Depth Gauge:

1 - primary scale; 2 - frame; 3 - vernier; 4 – screw

 

Depth gauges are used for measuring the depth of grooves and holes. Their principle of operation is similar to that of vernier calipers. A primary scale sliding in a frame may be locked in any position by a screw. The depth of a groove or a hole is measured by means of the primary scale and a vernier as shown in Fig. 17. Conical surfaces are measured with control gauges.

 

 

Fig. 18. Universal Angle Gauge:

1 - base; 2 - triangle; 3 - vernier; 4 -quadrant; 5 - detachable rule; 6 - holder

 

A universal angle gauge for measuring internal and external angles is shown in Fig. 18. The universal angle gauge consists of a base with a primary scale attached to the base. A quadrant with a vernier may be moved along the arc of the base. A triangle may be attached to the quadrant by means of a holder. In its turn a detachable rule is attached to the triangle. The triangle and the detachable rule can be moved along the face of the quadrant. Angles can be measured within the range of 0° to 320° by means of the universal angle gauge.

¹. they are graduated in thirty-seconds and sixty-fourths of an inch - они градуируются в тридцать вторых или шестьдесят четвёртых дюйма.

 

Exercises

 

I. Use the following words and phrases in sentences of your own:

drawing, to measure, to involve, mating part, accuracy, slide gauges, vernier calipers, depth gauges, clearance gauges, micrometer, inside calipers, outside calipers, to graduate, internal diameters, to slide, adjusting screws, lock nut, tapped hole

 

II. Translate the following groups of words, paying attention to the meaning of suffixes:

 

to measure, measuring, measurable, measured, measurement; to compare, comparative, compared, comparison; to signify, significant, significance; to depend, depending, dependence, dependent; to graduate, graduated, graduation; accuracy, accurate; precise, precision; general, generally, generation

III. Supply synonyms for the following words:

 

to place, inside, outside, to be similar, according to, with reference to

IV. Fill in the blanks with prepositions in accordance with, by means of, within, for, to, of:

 

1. Machine parts should be manufactured... their respective drawing. 2.... a micrometer it is possible to make measurements to a very high degree of accuracy. 3. Calipers are used for measurements to... 0.18 mm. 4. Measuring tools should be chosen... the machine part to be measured. 5. The micrometer is an instrument... measuring directly... thousandths, and estimating to quarter thousandths an inch,... its range.

V. Translate the following sentences observing different meanings of the words in italics:

 

1. The principle involved in the operation of the micrometer is explained in technical text-books. 2. The instruction on the use of this dial indicator is rather involved. 3. These drawings and their explanations are given to illustrate the principles involved. A. Different kinds of instruments are used to measure holes of considerable depth. 5. A millimeter is a measure of length. 6. Steel plates usually vary by sixteenths of an inch. 7. By dividing the load required to break the specimen by its area, the ultimate tensile strength of material is obtained. 8. By accuracy of form is meant not only the exact duplication of irregular pro files, but also the accuracy of form embodied in squares, true cylinders, cones, etc.

VII. (a) Translate the following text using a dictionary:

 

A range of optical instruments for measuring surface finish, which are relatively inexpensive and of very robust design, and afford the advantage that they can readily be applied under both workshop and inspection-room conditions, is being produced by many plants. Known as optical devices, these units are of modern designs. The portable device is intended for checking the relatively coarse finishes produced by planing, turning, and milling. With this device a beam of light

is directed past a straight, opaque edge, and through a lens at an angle of 45' to the work surface, and the line of intersection is observed at an angle of 90° to the light beam, through the eyepiece of the microscope.

 

(b) Make up three questions on the basis of this text and answer them.

VIII. Make up questions concerning the measuring tools shown in Figs 11, 12 and answer them.

IX. Using the following words and word combinations describe the principle of operation of the vernier calipers shown in Fig. 13:

 

vernier calipers, to be used, to measure, external and internal sizes, a part, to consist of, steel scale, four jaws, two jaws, to be attached, the frame, to slide, the scale, the first two jaws, to be used, measuring external surfaces, the Other two jaws, measuring internal' surfaces, the depth, to be measured, a spindle

X. Giving answers to the following questions describe the principle of operation of the micrometer shown in Fig 14:

 

1. What is a micrometer? 2. What is the function of the graduated thimble of the micrometer? 3. What is the scale on the micrometer barrel used for? 4. Where is the part placed for measurement? 5. How is the part pressed to the anvil and how is the micrometer reading taken?

XI. Describe the measuring tools shown in Figs 15, 16, and 18.

MACHINE-CUTTING TOOLS

 

The cutting tool is that part of a cutting machine which serves for removing material from revolving work. If either incorrect or faulty cutting tools had been used for metal-cutting operations, the quality of work would have become poor and cost would have been higher. That is why careful attention should be given to the cutting tools in any metal-cutting operation.

Cutting tools are made of hardened and tempered steel or alloy metals. All the cutting tools are adapted to perform certain work in the most efficient manner and, accordingly, they may be subdivided into turning tools, boring tools, milling cutters, planing tools, shaper tools, etc. These tools having one effective cutting edge along which excess material from the workpiece is removed are known as single-point cutting tools.

Other tools removing excess material on two or more cutting edges simultaneously are known as multiple-point cutting tools. Each cutting tool consists of a sliank for holding the tool in the machine and a tip or cutting edge for removing chips from the work.

 

 

 

The single-point cutting tools fall into several types, such as: (I) solid, forged tools having the same material throughout; (2) solid tools having a tough steel shank and a tip made of high alloy steel which is welded on to the shank; (3) solid tools with a tip brazed (Fig. 19) on to the shank; and (4) inserted tools having a small piece of the cutting edge made of carbide steels. Inserted tools held in a tool holder owing to a screw or wedge are used for machines of a complicated nature when it is necessary to prolong tool life as long a time as possible.

 

 

Fig.20. Cutting Tip:

A - top rake; В - side rake; С - front clearance; D - side clearance

 

The various types of cutting tools differ in shapes and in the angles to which the surfaces of the tools are ground. The cutting tipshould be ground by hand or by machine with correct angles (Fig. 20) on the top face (rake angles) and sides (clearance angles) to a desired shape. The shape of the tool, an ell as the proper rake and clearance angles depend upon a large number of factors, such as the specific operation, the material to be cut and the material from which the tool is made. The top rake is usually provided for the tool holder by the tool being set at an angle, which is correct for machining steel and cast-iron. On solid tools it is necessary to grind the top rake in the tool.

By adjusting the tool in the tool post through a wedge, this top rake can be varied somewhat to suit the material being turned. The softer the material the less the top rake should be as there is a tendency for the tool to dig in if the rake is too great. The side rake also varies with the material being machined. The proper angle is from 6° for soft material to 15° for steel. The front clearance depends on the diameter of the work to be turned. To turn cast-iron it is advisable to set the tool above center. If the tool were ground square¹ without any front clearance, it would not cut, but rub on the material to be turned below the cutting edge of the tool. The front clearance should be less for small diameters than for large diameters, ranging from 8° to 15°. The tool is ground with the side clearance to prevent the dragging of the tool on the shoulder formed by the cut. This angle is usually about 6 from the vertical and is constant.

For efficient operation of the machine, the proper surface speed of the work being machined must be maintained. If speed is too slow, the job takes more time than necessary and often the work produced is unsatisfactory. On the other hand, if the speed is too great, the cutting edge will be worn down too rapidly. Frequent grinding will be necessary, which is also wasteful. For ordinary

production work the speed should be as great as the tool will stand without requiring sharpening more often than every two or three hours when cutting continuously.

Cutting tools used for longitudinal turning are subdivided into roughing tools and finishing tools.

Roughing tools are applied for roughing or removing the excessive metal from the work. Such tools are usually carbide-tipped and they have a long cutting edge. Angular roughing tools are very convenient for turning surfaces of the parts which are at the chuck cams, as well as for facing.

Finishing tools are used after the work has been turned with a roughing tool to give accurate size and clean surface to the work being machined.

Before starting the cutting operation tools should be clamped in the tool-holder (Fig. 21) by means of two or more bolts.

 

 

Fig. 21. Tool Holder

1 - cutting tool; 2 - bolt; 3 - shank; 4 – bolt

 

Side tools are used for cutting faces. A side tool has a long cutting edge set in an angle of about 5° with respect to the surface of the work to be cut, and a short cutting edge. This cutting edge is largely beveled to facilitate the approach of the tool tip to the center of the part fastened between the two lathe centers.

Necking tools are used for grooving, since the width of grooves is usually small. The cutting edge of a necking tool is narrow, which increases the danger of its breakage. To prevent this breakage the height of the head is made several times larger than the width of the cutting edge.

Material is cut off by means of tools known as cutting-off tools, which are similar to necking tools. The difference is that they have a longer head which should be a little larger than one-half of the diameter of the blank to be cut.

¹. If the tool were ground square - если бы резец затачивался под прямым углом

 

Exercises

I. Use the following words and phrases in sentences of your own:

 

to bevel, side tool, facing, roughing tools, to grind, to rough, speed, finishing tool, to provide, to adjust, to set, single-point cutting tools, turning tools, effective cutting edges, tip, shank

II. Use these verbs in the past participle form and make up sentences using past participles as attributes.

 

to grind, to turn, to form, to cut, to temper, to harden, to provide

III. Underline the suffixes and prefixes and translate into Russian the following group of words of the same stem:

 

to adjust, adjustable, adjusting, adjustment; to continue, continual, continuance, continuation, discontinuation, discontinuance, to discontinue; to divide, divided, division, divisional, divisor, to subdivide, subdivisible, subdivision

IV Choose synonymical groups out of the following list:

 

to sharpen, to undergo, to understand, precise, accuracy, to realize, to complete, to start, to subject, to finish, to begin, accurate, to clamp, precision, to squeeze, to grind

V. Change the following sentences, using the subordinate clause instead of participle phrases. Translate the sentences info Russian:

Example: Cutting tools used for various metal-cutting operations have quite a wide range of shapes.

Cutting tools which arc used for various metal-cutting operations have quite a wide range of shapes.

 

1. The number and types of cutting tools used in practice are very large. 2. Tools designed to take heavy roughing cuts are known as roughing tools. 3. Milling cutters have several cutting edges giving the cutter the advantage of cutting. 4. Each blade of the milling cutter is a single-point cutter provided with proper rake and clearance angles. 5. The cutting angle is determined by the physical characteristics of the material being machined. 6. A high cutting speed, a small chip thickness and a large rake angle are factors facilitating the flow of the chip over the face of the tool. 7. Different kinds of cutting tools are used for metal-cutting processes depending upon the kind of metal being cut. 8. The elements of a single-point tool used for turning operations are shown in Fig. 20.

VI. State the kinds of subordinate clauses in the following sentences and translate them info Russian:

 

1. The distance that the tool is set into the work for cutting operations is referred to as the depth of cut. 2. Metals may be so strong that it is difficult to produce a tool capable of cutting off the chip without frequent failures. 3. If the metal to be cut is soft, the top rake of the tool is decreased.4. When a tool cuts metal a force is exerted on its face by the material pushed ahead, and a friction force is set up along the face of the tool by a sliding chip. 5. If the tool were not ground correctly, it would not cut freely. 6. The basic principle of design employed in

making single-point cutting tools is the wedge which can be modified in accordance with requirements.

VII. Translate the following sentences into English using different ways of expressing obligation:

 

1. Все резцы, в зависимости от типа машины, на которой они используются, нужно подразделять на токарные, фрезерные, строгальные и другие. 2. Для того чтобы продлить работу режущего инструмента, следует правильно выбирать скорость резания. 3. Угол заточки инструмента должен меняться в зависимости от материала обрабатываемой детали. 4. Инструмент, который нужно затачивать и устанавливать в определенное положение в автоматическом станке, следует насаживать с меньшей силой, чем обдирочный резец. 5. Режущие инструменты могут затачиваться до тех пор, пока не останется маленькая полоска режущей кромки, и все же их можно еще использовать для резки материала.

VIII. Give different meanings of the words proper, to make, one, for, above, more, that. Give some examples of their use.

IX. Make up questions to which the italicized words are the answers:

 

1. On solid tools it is necessary to grind the top rake in the tool. 2. To turn cast-iron it is necessary to set the tool above centre. 3. The tool is ground with the slide clearance to prevent the dragging of the tool on the shoulder formed by the cut. 4. If the surface of the work being machined is too great, the cutting edge will be worn too rapidly. 5. Roughing tools are applied for roughing or removing excessive metal from the work. 6. To prevent the breakage of the cutting edge of a necking tool, the height of the head is made several times larger than the width of the cutting edge.

X. (a) Read and translate the following text without using a dictionary:

 

Lathe tools are made of carbon steel, high speed steel up and alloys such as stellite and cemented carbide. The stellite and cemented carbide tools are becoming more generally used as their cost is reduced. There are but few carbon steel tools used¹, the general practice is to use high-speed tool bits in holders. One should determine the kind of tool to be ground, as carbon and high-speed steel require different treatment. Tools should be marked to show the kind of material from which they are made. To ensure the proper operation of a lathe the cutting tools should be ground by hand or machine. In machine grinding the tool is supported rigidly in a chuck or holder and ground semi-automatically to the desired rake and relief or clearance angles. In grinding by hand, the tool should be supported on the work rest and moved back and forth across the entire face of the grinding wheel. The accuracy of a tool ground by hand depends almost entirely on the skill of the operator.

¹. there are but few carbon steel tools used – применяются лишь немногие резцы из углеродистой стали

(b) Answer the following questions:

 

1. What steel are lathe tools made of? 2. Why should one determine the kind of tool to be ground? 3. How should the cutting tools be ground to ensure the proper operation of a lathe?

XI. Giving answers to the following questions describe the construction of the cutting tool in Fig. 19 and the angles to which a cutting tool shown in Fig. 20 should be ground, and clamping the tool in a tool holder in Fig. 21:

 

1. What parts does a cutting tool consist of? 2. What is the shank of the cutting tool used for? 3. What is the synonym for the word "cutting edge"? 4. By what means can the cutting tip of a tool be ground? 5. To what angles should the tip of the cutting tool be ground? 6. What do the shape of a tool as well as its rake and clearance angles depend upon? 7. How can the top rake be varied? 8. What does the top rake depend on? 9. How does the side rake vary for soft material and for steel? 10. What does the front clearance depend on? 11. What action would be performed by the tool if it were ground square without any front clearance? 12. Why is the tool ground with a side clearance? 13. How should the tool be clamped in the tool holder before starting the cutting operation?

 

DRILLS AND DRILLING

Drilling is one of the cutting operations producing cylindrical holes of different diameter in solid material by means of rotating tools called "drills" (Fig. 22).

The most common type of drill in use¹ is the twist drill made of a tempered steel round bar stock. Twist drills are made with two, three, or four spiral grooves or flutes milled from the solid. These grooves or flutes winding around the body of The drill serve for forming the cutting edges of the drill, as well as for removing the chips formed in drilling from the hole.

 

Straight-Shank Drill

 

Tapered-Shank Drill

 

Fig. 22. Drills.

 

The twist drill comprises three principal parts: body, shank and point. The twist drill has two cutting edges known as the "lips". These cutting edges, or lips, are connected e by a third edge, called a "web". It is this part that gives rigidity and strength to the drill. When in use the first two cutting edges remove the material

from the work, while the third one penetrates into the material by rubbing rather than cutting.

In order to drill holes in a metal the cutting edges of a drill should be correctly ground to a certain angle. When a drill is ground correctly, its cutting edges, or lips, should have equal length whereupon each of them should make the same angle with the centre line. Otherwise the drill will make holes the diameter of which is larger than that of the drill. This may disable the drill and cause an undesirable waste of material. Drills have shanks of various types, the most commonly used being those having straight and tapered shanks. The shank of the drill serves for clamping the drill either in the chuck spindle or socket of a drilling machine. The above part of the drill may be either of a cylindrical shape, like in² straight-shank drills, or of tapered shape in tapered-shank drills.

The third part of the drill is called a "drill point". It is always ground to a cutting angle varying with the kind of material to be drilled. For hard materials this cutting angle equals 140° and for soft materials it equals 90°. The cutting edges of flat drills used for drilling holes in steel or in cast iron are ground to an angle of 100° to 120°. All the drills get worn while drilling and they should be re-ground from time to time.

1. The most common type of drill in use -самым обычным используемым типом сверла...

2. like in - как в, подобно

 

Exercises

 

I. Use the following words and phrases in sentences of your own:

 

to drill, cylindrical holes, rotating tool, twist drill, flute, to mill, lips, web, spiral grooves, tapered shank, socket

 

II. Retell the text giving answers to the following questions:

 

1. What is drilling, and its purpose? 2. By means of what tools is drilling performed? 3. Which is the most widely used tool for drilling? 4. What material is a twist drill made of? 5. What purposes do twist drill flutes serve? 6. What are the principal parts of a twist drill? 7. What are the cutting edges of a twist drill called? 8. What part of the twist drill gives it rigidity and strength? 9. Why should the cutting edges of a drill be correctly ground'? 10. Why should the cutting edges of a drill have an equal length?

III. Form adverbs from the following adjectives:

 

proper, cylindrical, certain, good, wide, correct, equal

IV. Underline the suffixes and prefixes and translate into Russian the following groups of words of the same stem:

to desire, desirable, undesirable; cylinder, cylindrical, cylindrically; to straighten, straight; to grind, ground, re ground; equal, equality, equalization, to equalize, equalizer, unequal, unequalled

V. Supply the missing words:

 

1. In drilling h... in metal, heavy pressure must be applied at the drill p.... 2. Spiral f... are found on most drills. 3. The c... angle at the outer corner of the l... should be about 12. 4. The cutting edges of t... d... have angles of top rake and clearance the same as any other с… t... have. 5. The body of metal between the flutes forms what is called the w.... 6. The drills are held in place by their t... shanks or by gripping straight-s... drills in a c...

VI. Connect the following sentences using the con junction either... or:

Example: The body of the twist drill has two spiral grooves. The body of the twist drill has flutes cut on its surface.

The body of the twist drill has either two spiral grooves or flutes cut on its surface.

 

1. The twist drill is formed by twisting grooves in a fiat piece of steel. The twist drill is formed by milling a cylindrical piece of steel. 2. The grooves serve to form cutting edges of the drill. The grooves serve to remove the chips formed in the process of drilling. 4. The drill flutes serve to lubricate the drill. The drill flutes serve to remove chips from a hole being drilled. 5. The work to be drilled should be clamped in a vice. The work to be drilled should be clamped in a chuck. 6. The web of a drill penetrates into the material being cut. The web of a drill rubs the material.

VII. Translate the following sentences into English using the past participle instead of the attributive clauses:

Example: Часть сверла, которая называется режущей частью, всегда затачивается под определенным углом резания.

The part of the drill called a "drill point" is always ground to a certain cutting angle.

 

1. Операция, которая выполняется при помощи инструмента, называемого «сверлом», называется «сверлением». 2. Стружки, которые образуются при сверлении, удаляются по канавкам сверла. 3. Режущие кромки сверла, которые используются для сверления, должны затачиваться под определенным углом. 4. Инструмент, который используется для сверления, называется «сверлильным сверлом». 5. Одна из кромок сверла, которая называется «перемычкой», не режет металл.

VIII. Analyze and translate the following sentences:

 

 

1. Different kinds of drills are used in drilling, such as: a single-lipped twist drill, normally less than 1" (inch) in diameter. 2. It is formed of a tubular shank which is twisted of seamless tubing to make a single flute. 3. Coolant is carried through the hollow shank, through a small hole in the drill tip, and chips are washed out through the single flute. 4. A four-lipped hollow core drill is designed to carry chips out through a hollow drill shank. 5. This tool is used for enlarging holes and not for drilling solid metal. A two-lipped hollow type deep drill normally is used in drilling solid metal holes ranging from 1" to 3" in diameter and the tip is attached to a tubular steel shank. 7. Coolant carries chips through the flute into the centre of the drill and then out through the hollow shank. 8. Drills of the same design are also used for holes larger than 3". 9. These are provided with replaceable blades in the tip.

IX. Describe Fig. 22 orally using the following words and word combinations:

 

the body of a twist drill, to represent, a cylindrical rod, to have two spiral grooves, to serve, forming, the cutting edges of the drill, to be called lips, the lips, to be connected, a third edge, to be known., a web, to penetrate into material by rubbing, the shank, the drill, clamping the drill in the chuck, to be of different shapes, cylindrical shanks and tapered shanks, the third part of the drill, a drill point, to be ground to a cutting angle, to depend on, material to be drilled

THREADING TOOLS

 

There are different types of thread-cutting tools depending upon the operations to be performed. Thread-cutting tools are classified according to the work done into female screw-cutting tools and male screw-cutting fools.

According to their construction they are known as taps, nut taps (Fig.23), and threading dies. The tap used for cutting female threads in holes is made in the form of a screw provided mostly with straight grooves forming the cutting edges of the tool. The tap made of a steel cylindrical bar stock consists of the working part and the shank.

 

 

Fig. 23. Set of Taps

The shank serves for fastening the tap in a chuck or in a tap wrench (Fig.24).

 

 

Fig. 24. Tap Wrench

 

 

Threads can be cut by means of taps either by hand or on a machine. With manual tapping usually a set of two or three taps is used. The first tap serves for cutting threads; then the second tap is used; the third tap is applied for final thread cutting. With mechanical tapping in such materials as cast iron, bronze, brass, copper, aluminium, etc. one tap is used. When steel is tapped sometimes a set of two tools is used. Before cutting threads the tap should be set so that its axis strictly coincides with that of the hole to be cut, otherwise the thread may be oblique. To cut male threads such an instrument as a threading die is used, which is held in the die holder (Fig. 25).

 

Treading Die Die Holder

 

Fig.25

 

A threading die is usually made of internally threaded flat steel stock with cutting grooves or flutes. Between these grooves or flutes there are the cutting edges of the tool by means of which male threading is performed.

 

Exercises

 

I. Use the following words and phrases in sentences of your own:

 

thread, to classify, female screw-cutting tools, nut tap, to tap, threading die, die holder, tap wrench, male threads, female threads

II. Retell the text giving answers to the following questions:

 

1. What are thread-cutting tools? 2. How are thread-cutting tools classified according to the work done by them? 3. How are thread-cutting tools classified according to their construction? 4. What instrument is used for cutting threads? 5. What is the construction of a tap? 6. How can threads be cut? 7. What is needed for manual tapping? 8. What is the purpose of the first, second and third tap? 9. How should the tap be set before cutting threads and why is it necessary to do that? 10. What instrument is used for cutting male threads?

III. Supply synonyms for the following words:

 

to perform, female thread, male thread, construction, instrument, form

IV. Give derivatives from the following words and translate them into Russian:

 

to operate, to perform, to cut, to construct, to thread, to tap, to fasten, usual, to hold

V. Supply antonyms for the following words:

 

straight grooves, manual tapping, final, to coincide

 

 

VI. Translate the following sentences observing different meanings of the word machine:

 

1. This machine is mainly used for removing large pieces of metal. 2. The engineer explained in his lecture how to machine workpieces of different shapes and sizes. 3. The size and shape of all machine parts should be checked by means of different measuring tools.

VII. Make up questions to which the italicized words are the answers;

 

1. With mechanical tapping in cast iron, bronze, brass, copper, and aluminium one tap is used. 2. When steel is tapped a set of two tools is used. 3.Before cutting threads the tap should be firmly set in a tap wrench. 4. A threading die is made of internally threaded flat steel stock.

VIII. Describe Figs 28 and 24 orally using the following words and word combinations:

 

the tap, to be made, a cylindrical bar stock, to consist, the working part, the shank, to be used, fastening the threading tool, in a chuck or in a tap wrench, two or three taps, to be applied, manual tapping, the first and the second taps, to serve, to cut threads, the third tap, final thread cutting

IX. Giving answers to the following questions describe the threading die shown in Fig. 25:

 

1. What operations are performed with a threading die? 2. What material is a threading die made of? 3. How is a threading die threaded? 4. What is there between the cutting grooves of a threading die?