Задание 1:
Прочитайте текст, поймите его содержание, выполните задания после текста.
LATHE
A lathe is a machine tool which spins a block of material to perform various operations such as cutting, sanding, drilling, or deformation with tools that are applied to the work piece to create an object which has symmetry about an axis of rotation.
Lathes are used in woodturning, metalworking, metal spinning, and glass working. Lathes can be used to shape pottery, the best-known design being the potter's wheel. Most suitably equipped metalworking lathes can also be used to produce plane surfaces and screw threads.
The lathe is an ancient tool; it was first developed by the Egyptians around 1300 BC. During the industrial revolution the lathe was motorized, allowing wooden turned items to be created in less time and allowing the working of metal on a lathe. The motor produced a greater rotational speed, makes it easier to quickly produce high quality work. Today most lathes are computer operated al-lowing for mass-production that can be created with accurate precision and without the cost of em-ploying craftsmen.
The largest part of the lathe is called the bed on which the headstock and the tailstock are fastened at opposite ends. On the upper part of the bed there are special ways upon which the car-riage and tailstock slide.
The two lathe centers are mounted in two spindles: one (the live center) is held in the head-stock spindle while the other (the dead center) - in the tail- stock spindle.
The lathe chuck is used for chucking the work that is for clamping it so that it will rotate without wobbling while turning. The chucks usually mounted on the headstock spindle, may have different size and construc¬tions.
If the work is perfectly round, it may be chucked in the so-called three-jaw universal chuck all the jaws of which are moved to the center by turning the screw. But if the work is not perfectly round, the four-jaw independent chuck should be used.
In turning different materials and works of different diameter, lathes must be run at differ-ent speeds. The gear box contained in the headstock makes it possible to run the lathe at various speeds.
Before turning a work in the lathe, the lathe centers are to be aligned, that means that the axes of both centers must be on one line.
The alignment of the lathe centers may be tested by taking a cut and then measuring both ends of the cut with a micrometer.
Not all works should be fastened between the two centers of the lathe. A short work may be turned without using the dead center, by simply chucking it properly at the spindle of the head- stock.
Задание 2:
Ответьте на вопросы к тексту письменно (вопросы списывать):
1.What machine tool is the lathe?
2.What operations can the lathe perform?
3.When was the first lathe constructed?
4. What is the largest part of the lathe?
5.What is the lathe chuck used for? Where is it mounted?
6.How many work centers are there on the lathe?
Задание 3:
Заполните пропуски в предложениях в соответствии с содержанием текста:
1.The largest part of the lathe is called .
2.The headstock and the tailstock are fastened at .
3.The lathe chucks may have different .
4.The short work may be turned without .
Задание 4:
Поставьте глаголы, данные в скобках в правильную форму (предложения записывать полностью):
1.The lathe (to perform) many operations.
2.Almost all lathes (to have) a bed.
3.The headstock (to contain) a spindle.
4.A work piece (to be clamped) in a three- or four-jaw chuck, which (to mount) directly to the spindle.
5.In a metalworking lathe, metal (to be removed) from the work piece using a hardened cutting tool.
6.Cutting tools (to come) in a wide range of sizes and shapes.
Задание 5:
Переведите письменно следующие предложения на русский язык:
1.If the work is perfectly round, it may be chucked in the so-called three-jaw universal chuck all the jaws of which are moved to the center by turning the screw.
2.If the work is not perfectly round, the four-jaw independent chuck should be used.
3.Not all works should be fastened between the two centers of the lathe.
4.The lathe chuck is used for chucking the work that is for clamping it so that it will rotate without wobbling while turning.
Ответы
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Ответ:
задание 5:
1. Если изделие идеально круглое, его можно закрепить в так называемом трехкулачковом универсальном патроне, все кулачки которого перемещаются к центру поворотом винта.
2. Если изделие не идеально круглое, следует использовать четырехкулачковый независимый патрон.
3. Не все работы следует закреплять между двумя центрами станка.
4. Токарный патрон используется для зажима заготовки, чтобы она вращалась без колебаний при повороте
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