4. Перечень вопросов для подготовки к зачету по дисциплине

1.“Machine - tools”(станки).

2.“Types of machine - tools ”(типы станков)

3.“The most important machine - tool” (мой любимый станок)

Machine tool, any stationary power-driven machine that is used to shape or form parts made of metal or other materials. The shaping is accomplished in four general ways: (1) by cutting excess material in the form of chips from the part; (2) by shearing the material; (3) by squeezing metallic parts to the desired shape; and (4) by applying electricity, ultrasound, or corrosive chemicals to the material. The fourth category covers modern machine tools and processes for machining ultrahard metals not machinable by older methods.

METAL-CUTTING MACHINES LATHES

A lathe is known to be essentially a machine tool for producing and finishing surfaces of work pieces. The machine is designed to hold and revolve work around an axis of rotation so that it may be subjected to the action of a cutting tool moving in a horizontal plane through the axis of the work. When the cutting tool moves in a longitudinal direction or parallel to the axis, the operation is known as "turning"; when it moves in a transverse direction, it is known as "facing". In addition to turning and boring, which the machine is primarily designed for, many other operations, such as drilling, threading, tapping, and, by employing special adapters grinding and milling, may be performed on a lathe.

Lathes used in shop practice are known to be of different designs and sizes. These lathes fall into various types, either according to their characteristic constructional features, or according to the work for which they are designed. The size of a lathe is determined by the diameter and length of work that may be swung between centers. Lathes of comparatively small size, which may be mounted on a bench, are termed bench lathes, and are intended for small work of considerable accuracy; lathes provided with tools held in a revolvable turret are called "turret lathes": lathes in which work pieces to be treated are held in a chuck are known as "chucking lathes"; lathes in which most of operations are performed automatically are named "automatic lathes".

Besides there are also many special-purpose lathes such as crankshaft lathes and wheel lathes for turning crankshafts or engine driving wheels respectively; screw-cutting lathes for threading screws, etc. The engine lathe used for metal-turning operations is fitted with a power-actuated carriage and cross-slide for clamping and holding the cutting tool. In engine lathes the cutting tools are generally guided by the machine tool itself, in other words, they are operated mechanically, while in some lathes the cutting tools are guided by hand. The engine lathe consists essentially of the following basic parts: the bed, the headstock, the tailstock, the feed mechanism, and the carriage.

The bed is a rigid casting with two longitudinal walls firmly connected by cross ribs integral with the casting. The bed serves as a base to support and align the rest of the machine. The upper surface of the bed is provided with parallel V-type and flat ways or guides for accurate aligning of the sliding parts of the lathe—the carriage and the tail-stock. The headstock is located and firmly bolted to the left-hand side of the bed and carries a pair of bearings in which the spindle-rotates. Many modern lathes have a motor built into the headstock-with the spindle serving as the motor shaft. The spindle ,-being one of the most important-parts of a lathe, is a steel hollow shaft with a taper bore for the insertion of the live or running centre on which the piece to be turned is placed. The other end of the work is" supported by the non-rotating dead or cup centre. The nose of the spin-die is accurately threaded for chucks to be screwed on it. The chucks, in turn, hold and revolve work pieces together with the spindle. The head- stock also incorporates the change gearbox driven by a set of speed-change levers. The change gearbox lathe at different speeds required work pieces of various diameters.

The tailstock located at the right-hand side of the bed, is a casting carrying a non-rotating sleeve, which together with the nut can be advanced or retracted by means of the tailstock revolving screw operated by the hand wheel. The tailstock may be moved anywhere along the lathe bed and can be clamped in place at any point. On changing the position, the tailstock slides along the two inner bed ways one of which named flat way is of rectangular cross-section and the other one is of V — section. The tailstock sleeve mounts a hollow spindle with a standard taper bore for holding the lathe centers or tapered tool shanks. The dead centre fits in a Morse taper hole in the sleeve and may be removed by retracting the sleeve, thereby bringing the end of the tailstock screw against the rear of the centre and forcing it out. The tailstock spindle has a large area bearing in both the front and rear of the tailstock. To facilitate measurement of the spindle travel the tailstock spindle is graduated.

The feed mechanism for both longitudinal and cross feeds of the engine lathe is simple and easy to operate. It comprises a cone of gears, an intermediate shaft and a set of sliding gears. The fine change shifter slides on a splined shaft and carries a tumbler gear which is dropped into engagement with a gear on the cone corresponding to the thread or feed selected on the index plate above it.

Movement of the carriage and the cross-slide can be reversed either by reversing the feed mechanism with the reverse handle or by shifting the single lever located on the carriage apron. Suitable speed ratios between the spindle and the feed mechanism are provided by a change gearbox. The carriage is a unit intended for mounting the tool, and capable of sliding along the two outer V-type ways, on which it is supported, in a direction parallel to the spindle axis.

For turning and facing operations the carriage is driven from the headstock spindle by gearing or belting through a feed shaft. For thread cutting, where a definite amount of carriage movement is required for every spindle rotation, a lead screw, geared to the spindle, is used for the motion of the carriage. The carriage is made up of two principal parts, one of which carries the saddle, which slides upon the bed and on which the cross-slide and the tool rest are mounted. The other part, termed the apron, represents the front wall of the carriage. It provides a support for the operating hand-wheel and control levers, as well as carries the mechanism for engaging the feed mechanism of the lathe to drive the carriage. The cross-slide mounted on the carriage can move at right angles to the spindle axis. It is operated by the cross-slide screw which turns in a nut fixed to the carriage.

On the top of the saddle there is the compound rest for mounting the tool post. The compound rest is similar to the cross-slide, except that it can be swung around at an angle. It has a circular base graduated in degrees, so that it may be set at any angle, and may be used for cutting bevels, tapered work and similar jobs. The compound rest is actuated by a screw which rotates in a nut fixed to the saddle. The tool post intended for holding the tool fits in a tee slot in the compound rest, and the toolholder is adjusted, and clamped by the tool post screw. Engine lathes are fitted with a multiple disc clutch and brake. The powerful multiple disc clutches when disengaged automatically engages the plate brake.

There are three important methods of holding and rotating work in engine lathes, which may be referred to as turning between centers, chuck work, and faceplate work. In turning between centers, the work is supported by the 60° conical points of the live and dead centers. It turns together with the live centre on the dead centre. In chuck or faceplate work, the work to be machined is held in a chuck or a faceplate.

Словарь

Lathes - Токарные станки

Workpieces - заготовка

Turning - обработка

Facing - соединение

Chuck - чак

The bed – платформа, основание

Drilling - бурение

Threading - нарезка резьбы

Hydroelectric power-station - ГЭС

Carriage - вагонетка

Spindle - шпиндель

Saddle - седло

Shaft - шахта

Tool rest – суппорт

To nut - гайка

MACHINE TOOLS — A MEASURE OF MAN'S PROGRESS

The variety and combinations of machine tools today are unlimited. Some of them are very small and can be mounted on a work-bench but others are so large that we have to construct special buildings to house them.

There are some basic operations at any workshop. They are turning, drilling, threading, etc. The main machine tool of such a workshop is the multipurpose lathe. What is a lathe? It is a power-driven machine with special tools which can cut or form metal parts. The metal that cuts another metal must be very hard and so tools should be made of very hard steel alloys. The tool itself is very small in comparison with the mechanism that is to direct it.

Technological progress improves accuracy of machine tools. Today's equipment can produce parts with very high accuracy. One can find a number of machine tools that can measure and inspect their production themselves — machine tools that are to handle the parts mechanically and automatically. Such machines can hold the parts which are to be measured and are able to indicate precise measurements themselves. A great many of such "clever" machines can be found today in our industry.

Since machine tools become faster and more complex, automatic measurements and inspection ought to be of greater importance. Automation is one of the main factors of engineering progress.

Flexible production lines form the basis for automated workshops. The main principle of such a flexible line is the fact that it can be switched over from one product to another, which has a similar structure but a different outline, almost instantaneously. It is equally efficient in conditions of both mass and small-batch production and will serve to increase the productivity.

Milling Machine

A milling machine is a power-driven machine used for the complex shaping of metals parts. Its basic form is that of a rotating cutter which rotates in the vertical axis (like a drill) and can move in three dimensions relative to the workpiece (in contrast to the drill which can only move in one dimension while cutting). Cutters are usually manufactured from high speed steel in a number of shapes and sizes. They can also be ob­tained in carbide or diamond for special milling operations.

The motion across the surface of the workpiece is usually accom­plished by having a moveable table on which the workpiece is mount­ed, so arranged to move in two dimensions.

Materials best suited for milling are soft metals and plastics. Alu­minium and brass are two commonly milled metals. The ability to mill a metal is limited only by the hardness of the cutter.

Milling machines may be operated manually or under numerical control. Such mills arc called Numerical Control mills, which are wide­ly used in small machine shops.

Milling machines can perform a great number of complex opera­tions, such as slot cutting, planning, drilling and others.

Учебник Агабекян стр.205-208, тексты +упражнения

Universal Cylindrical Grinding Machine

This universal grinder is designed for external grinding of both cy­lindrical and tapered surfaces. Depending on its size the workpicce is either mounted between dead centres or is held in a chuck. It is widely used in piece and lot production plants.

The rigid and massive design of the machine ensures dependable operation. The workpicce can be ground with high accuracy and ex­cellent surface finish.

The hydraulic system accomplishes the following operations: re­ciprocating table traverse, rapid approach and withdrawal of the wheel-head.

The upper part of the table, the wheel head and the headstock can be swivelled and clamped in (he required position for taper grinding operations.

The one-piece cast-iron base is of box shape. It is rigid and stable, thus preventing the development of vibration during operation.

The base ways have a large bearing surface, reliably protected against dust.

By the beginning of the new millenium a great number of complex machine tools had been designed to speed up production. Although these tools include features of the basic machine tools and perform the same operations, they incorporate design modifications that let them perform complex operational sequences quicker. Furthermore, after the production machine has been set up by a skilled worker or machinist, a less skilled operator also can produce parts accurately and quickly.

There's one more improvement that had already been incorpo­rated in machine tools by the 21st century. This is a highly automat­ed machining system, called adaptive control that involves the use of a microprocessor. A microprocessor is a tiny electronic device that performs the work of a computer. The microprocessor regulates vari­ables in the machining process such as the speed of the spindle. That makes the process very efficient. It also receives information from sensors that measure force, temperature, and other variables. It uses the information to operate the system at the level that is safe for the machine tool and the workpiece. Specialists predict that by the year 2015 all major industrial works in Belarus will have been equipped with such machining centres.

Scientists consider that the oldest tools that are known to the mankind are 2,600,000 years old. They were used by people in manual operations and that is why they were called hand tools. By the begin­ning of the Industrial Revolution, people had already devised simple hand tools for cutting and shaping different materials. But in the 18th century there appeared machine tools that made mass produc­tion a reality in the 19th century. A machine tool is a power-driven machine that is used to perform different operations with metal or other material. Basic machine tools use mechanical power to bend, cut, drill, grind and hammer metal into desired shapes. More advanced machine tools use such power sources as electrical or chemical energy, heat, magnetism and ultrasound.

Nowadays machine tools play an important role in the manufac­ture of almost all metal products. Machinists (people who operate machine tools) use them in making automobiles, radios, refrigerators, television sets and so on. Every mechanical engineering workshop is equipped with machine tools. They are the main source for the manu­facture of component parts of all machines and mechanical devices.

There are about 500 kinds of machine tools. Some perform a sin­gle operation, such as grinding or drilling. Others, called machining centres, carry out several kinds of tasks. These numerous machine tool types fall into two categories. The first group is called "metal cutting". The machine tools of this group remove some material from the workpiece and they are much stronger than the workpiece itself. The examples of metal cutting machines are lathes, drill presses, milling and shaping machines.

The second group is called "metal forming". They shape the work-piece without the removal of any material from it. For metal forming operations we use a wide range of forging machines¹, presses and press brakes².

'ковочная машина ²прессовые тормоза

Словарь

casing, n кожух, чехол, корпус

changer, n переключатель, механизм смены (инструмен­тов, валков и т. п.)

fixture, n приспособление, арматура

lathe, и токарный станок

machine, n станок cylindrical machine цилиндри­ческий станок prismatic machine призмати­ческий станок milling machine фрезерный станок

drilling machine сверлиль­ный станок, бурильная машина

grinding machine шлифо­вальный станок, заточный станок

boring machine расточный станок, сверлильный станок, бурильная машина multi-purpose machine многоцелевой станок machining centre многоцелевой станок

numerical control числовое программное управление, ЧПУ

computer numerical control (CNC) ЧПУ типа CNC direct numerical control (DNC) станок с централизо­ванным программным управлением

remove, v удалять, снимать

shape, v формировать, прида­вать форму

simultaneously, adv одновре­менно

tool, n орудие (производства); инструмент

hand tool ручной инструмент machine tool станочная (авто­матизированная) система cutting tool режущий инструмент, резец metal-cutting tool металло­режущий инструмент

abrasive materials абразивные ма­териалы

accuracy точность

adjust регулировать

apron фартук (суппорта)

axis ось

bearing подшипник

bed станина

box-shape коробчатой формы

bracket кронштейн

carriage суппорт

casting отливка

cast-iron чугун

clamp зажимать

column колонна

composition состав

control управлять

cross-rail поперечина (траверса)

cutter фреза

dependable надежный

diamond алмаз

dimension размер

drilling сверление

drive the motor приводить (в дви­жение) мотор

engine lathe токарно-винторезный станок

external внешний

face торец

facing торцевое точение

feed подача

flame furnace пламенная печь

finishing operation чистовая об­точка

grey iron серый чугун

grinder шлифовальный станок

grinding шлифование

guideways направляющие

handle рукоятка

deadstock передняя бабка

high-speed steel быстрорежущая сталь

hole отверстие

hydraulic unit гидравлический аг­регат

in-line production поточное произ­водство

length длина

lever рычаг

longitudinal direction продольное направление

lot production серийное произ­водство

machine-tool станок

mill фрезеровать

milling machine фрезерный ста­нок

multidisk friclion clutch многодисковая фрикционная муфта

mount устанавливать (монтиро­вать)

move двигаться

moveable (able подвижной стол

piece production штучное произ­водство

prevent мешать, предотвращать

reciprocating возвратно-поступательный

rigid жесткий

rotate вращать(ся)

roughing operation черновая об­точка

saddle салазки

screw cutting нарезание винтов

sot up налаживать (станок)

shape придавать форму

side head боковой суппорт

single lever единственный рычаг

sizes размеры

slide скользить

slot cutting прорезание пазов, канавок

speed скорость

speed gearbox коробка переклю­чения передач

spindle шпиндель

stable устойчивый, прочный

starting запуск

stopping остановка

suit соответствовать, подходить

support поддерживать

swivel поворачиваться

tailstock задняя бабка

tapered конический

the surface of the table поверх­ность рабочею стола

tool инструмент

travel передвигаться, переме­щаться

traverse поперечина, переклади­на

turning обточка

turning mill токарный станок

turret head револьверная головка

V-belt клинообразный привод­ной ремень

vertical turning mill вертикальный токарный станок

wheel head шлифовальный круг

wheel slide шлифовальный суп­порт

wheel spindle шпиндель шлифо­вального круга

withdrawal отвод

work (workpiece) заготовка (де­таль)

Интернет-ресурсы

1. http://www.lingvo-online.ru/ru (онлайн словарь)

2. http://usefulenglish.ru/grammar/( английская грамматика)

3. http://www.ego4u.com/ (грамматика, словари по темам)

4. http://www.kakprosto.ru/kak-118156-kak-vyuchit-tehnicheskiy-angliyskiy

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