Unit 3 turning and turning machines (lathes)

TOPICAL VOCABULARY

1. Read and memorize the following words and word-combinations:

lathe swing rear end to designate versatile v-type belt immense toolroom lathe appearance turret lathe bench lathe precision lathe gap lathe engine lathe	- токарный станок - максимальный диаметр обрабатываемого изделия - задняя часть - определять, обозначать, называть - универсальный - клиновой ремень - огромный - инструментальный токарный станок - внешний вид - токарно-револьверный станок - настольный токарный станок - прецизионный токарный станок - токарный станок с выемкой в станине - токарно-винторезный станок
Chuck	- зажимной патрон
Faceplate	- планшайба
(cutting) tool	- резец
Accurate	- точный
Inch	- дюйм
Headstock	- передняя бабка
Tailstock	- задняя бабка
saddle (carriage)	- суппорт
Attachment	- приспособление
gear(s)	- шестерня (и)
Gearbox	- коробка передач
Pitch	- шаг резьбы
Bed	- станина
Ways	- направляющие
Sleeve	- втулка
Handwheel	- маховик
tool post	- резцедержатель
Slides	- салазки
Apron	- фартук
stock-removal stiffness overhaul layout to handle distortion guard	- снятие припуска (с заготовки) - жесткость - капитальный ремонт - расположение, компоновка - ухаживать (за машиной), обслуживать - искажение, искривление - защитный кожух, предохранительное устройство
Shaft	- вал
Bearing	- подшипник
Counterboring	- цилиндрическое зенкование
Reaming	- развертывание (на токарном станке)
Tapping	- нарезание резьбы метчиком
Template	- шаблон, модель
impact load	- ударная нагрузка
Torque	- ударная нагрузка
to run through	- обработать за 1 проход
Chips	- стружка
Fixture	- зажимное приспособление

T ext 1

Types of lathes

A lathe is a machine tool in which the work is either rotated between two rigid supports called centers, or is held in chuck or on a face plate attached to the rotating spindle of the machine. On this machine the material is removed from the rotating work by the action of the cutting tool, which may be advanced either parallel or perpendicular to the axis of the work. The lathe is probably the most versatile and important tool in the machine shop.

The lathe is thought to be one of the first machines invented by man.

Modern lathes are highly efficient, accurate and complex devices, capable of doing a great quantity and variety of work. A well constructed engine lathe will, when properly operated, produce work accurate within 0.001 of an inch or even less.

Motion is transmitted to modern lathes by means of individual motors. Sometimes the motor is direct mounted, while on other machines it is connected by means of a short belt, usually of the V-type.

The size and capacity of a lathe is given in terms of swing and length of bed. The swing refers to the diameter of work that can be rotated in the lathe. Thus a 16-inch lathe will swing work as large as 16 inches in diameter. The length of a lathe should not be confused with the maximum distance between centers when the tailstock is moved to the rear end of the lathe bed. The maximum distance between centers however, determines the length of stock that can be machined.

Lathes are made in a wide variety of types and sizes, from the small precision lathe found in watch repair shops to the immense machine used in manufacturing big guns.

There also exist various attachments which can be employed on a lathe to perform functions or operations formerly done on a special machine: a milling attachment, a boring attachment and a gear-cutting attachment. Such devices greatly extend the variety of work that can be performed on a lathe.

As lathes in general are used for a great variety of operations, naturally there are many different designs end sizes. The most common type of lathes is .usually known by manufacturers as an engine lathe. The term "engine", as - used in this connection simply means a machine, and it serves to designate that particular class of lathe which is hand-manipulated and used by machinists for general work. In ordinary shop usage, the word "lathe" is commonly used to indicate a lathe of this class. Lathe having gears which are changed for cutting threads of different pitch are sometimes known as plain or standard engine lathes. The tool-room or toolmaker's lather is classified according to the general class of work for which the lathe is designed. It is similar in appearance to an ordinary lathe, but has extra attachments and is generally considered a very accurate machine.

Other types of lathe which have some distinguishing characteristics are: the turret lathe, which is so named because tools for performing successive operations are held in a revolving turret; the bench lathe, which in so small that it is mounted on a bench, and intended for delicate work usually requiring considerable accuracy; the precision lathe, which is usually a bench-type that is capable of very accurate work and is more expensive than an ordinary bench lathe; the gap lathe, which has a gap formed in the bed in front of the face plate in order to increase the “swing” or maximum diameter that may be revolved.

The lathe consists essentially of a bed, headstock, tailstock and saddle.

The main casting of the lathe is called the bed, and usually consists of a good quality grey iron casting of rigid design to prevent bending or twisting.

The Headstock is located true with the ways and bolted rigidly to the bed at the left-hand end. It carries the lathe spindle and gear-box.

The Tailstock consists of a casting fitted to the bed and capable of being firmly clamped to it any position along its length. The casting is bored for a sliding sleeve which is moved axially by a handwheel at the right-hand end.

The saddle consists of a casting designed to carry the tool post slide or slides, and is fitted to the ways of the bed so that it may slide along it without lateral movement. The front of this casting is called the apron.

EXERCISES