Stepanova_LM_AM-123_Stanki_Part2_1978-1 (533318), страница 3

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_{The standard drill press may have either a rectangular or a round worktable. There are three ways in which this worktable may be adjusted for position: (1) The supporting arm (and table) may be raised or lowered; this provides for different heights of work.(2) The supporting arm may be swung to substantially 90 deg. either side of center, and (3) the table itself, being pivoted at its center, may be swiveled through 360 deg. The ad­justments (2) and (3) in combination provide for locating, di­rectly under the cutting tool, any given spot on the work when the work is clamped or is for some other reason impracticable to move about on the table.}

_{drilling - cверление}

_{twist drill - спиральное сверло}

_{drill press - вертикально-сверлильный станок}

_{column - колонна, стойка}

_{base - основание, плита (фундаментная;}

_{§4.MULTIPLE-SPINDLE AUTOMATICS}

_{Many more operations can be combined, and production there- ­by speeded up, if more than one piece is being worked on at the same time. This can be done in the multiple—spindle auto- ­matic screw machine which may have four, six, or eight working spindles. As the number of spindles goes up, the cost of the}

_{machine rises correspondingly. Use of an eight-spindle machine,}

_{therefore, is justified only when it is necessary to perform a
large series of operations on a piece and when the quantities
to be produced are quite large. For one thing}¹_,

_{the special tooling required is expensive, and it takes a long time to set up these machines. It would scarcely pay}² _{to make a set-up unless the machine is to be operated continuously for at least three or four days before changing to another job. Very often, such machines run for weeks at a time}³_{, the only stops being made for sharpening tools and inserting new bars of stock.}

_{The choice between the number of spindles to be employed
lies in the relative simplicity or complexity of the work. If
there are comparatively few operations, the work can be handled
on a four-spindle machine; if there must be a large number of
operations, a six- or eight-spindle machine will be needed,
provided always that the quantities required will justify the
long set-up time involved in changing over the machine from
one job to another.}

_{On a six-spindle automatic, for example, the progressive action is obtained in this way. The group of spindles is moun- ­ted in a cylindrical carrier. Opposite each spindle, end-work­- ing tools are mounted on a hexagonal slide. For some of the spindle stations, there are cross-feed tools mounted on slides. These move in and out radially, but remain in their relative positions. As in the case of a single-spindle automatic, the tools are fed into the work and withdrawn at, the end of the cut. When the main tool slide is withdrawn, the entire spindle carrier is rotated a sixth of a turn to bring each of the spindles and their revolving workpieces in front of the next set of tools. Spindle No.1 is presented successively to six sets of cutting tools, and right behind it}⁴ _{comes Spindle No.2.}

_{This sequence of operation is repeated continuously, so that at each indexing of the spindle carrier a piece is complet­-ed, although, actually, it has been worked on at six different stations. This is what makes the multi-spindle machine so high­- ly productive.}

_{Notes: 1) For one thing - прежде всего}

_{2) It would scarcely pay - едва ли (окупится) выгодно}

_{3) such machines run for weeks at a time - такие станки}

_{работают в течение нескольких недель без перерыва}

_{4) right behind it - сразу же за ним}

_{Words and word combinations to be remembered: automatic - автоматический (n.) - автомат bar - пруток, полоса}

_{carrier - держатель}

_{to change over - переводить (станок) переключать}

_{comparatively - сравнительно}

_{correspondingly - соответственно}

_{expensive - дорогой, дорогостоящий}

_{piece - деталь, обрабатываемая заготовка}

_{progressive - последовательный}

_{sequence - последовательность}

_{set-up - наладка to set up – налаживать (станок)}

_{slide - салазки, каретка}

_{station - позиция, положение}

_{successively - последовательно}

_{tooling - оснастка (станка)}

_{to withdraw - удалять, отводить}

_{multiple-spindle machine - многошпиндельыый станок}

_{set of tools - набор инструментов}

_{tool slide - резцовые салазки}

_{cross feed tool - резец поперечной подачи}

_{end-working tool (end-cut tool) - резец с передней режущей кром­кой}

_Exercises.

_{I.a) Give verbs corresponding to the nouns and translate them:}

_{combination, production, speed, cost, justification, performance, operation, requirement, choice, employment, involvement, action, withdrawal, rotation, revolution, set.}

_{b) Give the adverbs corresponding to the adjectives and translate them:}

_{comparative, corresponding, progressive, successive, rapid, pre­cise, rough, smooth, longitudinal, efficient, helical, recipro­cating, transverse.}

_{II. Look through the text and find equivalents for:}

_{одновременно, с увеличением числа шпинделей, целый ряд (большое число) операций, требуется много времени, по крайней мере, про­вести наладку, такие станки- работают неделями, для заточки рез-}

_{цов, выбор ... зависит от, заготовку можно обрабатывать, боль- шое время наладки, расходуемое на переключение, следующим об-разом, они выдвигаются и вдвигаются в радиальном направлении, в конце прохода (инструмента), поворачивается на 60° (1/6 обо- • рота), подается последовательно, сразу же за ним, последова­тельность операций, вот, что делает..., перед следующим набором инструментов.}

_{III. Arrange the following word3 la groups of synonyms:}

_{piece, revolve, present, carry out, feed, rise, rotate, use, go up, work, perform, employ.}

_{IV. Translate the sentences paying attention to the verbal forms.}

1. _{By increasing the number of spindles, several operations can be performed on the same machine tool, thus speeding up the production.}

2. _{The main tool slide withdrawn, the spindle carrier is ro­tated a sixth of a turn.}

_{3. The number of spindles employed depends on the complexity of the work.}

_{4. Multiple-spindle automatics can run for weeks at a time without being set up.}

_{5. While choosing between a four-, six-, or eight—spindle ma- chine one should think of the number of operations needed.}

_{6. On setting up a multiple-spindle automatic the operator
stops it only for sharpening tools and loading new bars of
stock.}

_{7. All the operations performed, the piece is completed and un­loaded from the machine.}

_{V. Translate the following text without a dictionary,
(time-limit - 10 min.)}

_{There are several types of multiple-spindle automatics, all of them having distinguishing features but having certain fun­damental principles of operation in common.}

_{To understand more clearly the action of such machines,let us see how a particular piece is made in a six-spindle bar-type automatic}¹_{. The various carriers are actually arranged in a circle.}

_{The first operation on the bar takes place at Station VI. At this point, the bar is fed forward through the spindle auto­matically until it hits a stop bar}² _{which is set to govern the length of the piece to be made. The stop bar then swings out of the way and the first end tool, a drill, is fed forward into the revolving bar. This is done by advancing the entire tool slide as a unit.}

_{While the bar is being drilled at Station VI, a form turn­- ing tool}³ _{is advanced radially into it from a cross-slide at the rear of the machine. When the drill has been fed to depth, it is automatically withdrawn, the cross-slide is withdrawn too, and the whole spindle carrier is indexed one-sixth of a turn to present the partly machined piece to Station I.}

_{Meanwhile, a second bar is being fed out and worked upon at Station VI.}

_{Notes: 1. bar-type automatic - прутковый автомат}

1. _{stop bar - упор, стопор}

2. _{form turning tool - фасонный резец}

_{VI. Answer the questions.}

1. _{How can production be speeded up?}

2. _{How many spindles can a multiple-spindle automatic screw machine have?}

_{3. In what cases are eight—spindle machines used?}

_{4. Why are they not used for small quantities?}

_{5. Will it pay if the machine is operated for less than three}

_days?

_{6. What are such machines usually stopped for?}

_{7. What does the number of spindles depend on?}

_{8. Where are the spindles mounted?}

_{9. What is mounted opposite each spindle?}

_{10.How do cross-feed tools move?}

_{11.When are the tools withdrawn out of the work?}

_{12.How is the entire spindle carrier rotated each time?}

_{13.When is a piece completed in a multiple-spindle automatic? 14.At how many stations is the piece worked on?}

_{VII. Retell the text.}

_{VIII. Read the text without a dictionary and explain the main difference between the multi-spindle automatic bar machine and the multiple-spindle chucking machine.}

_{Many operations, particularly form turning and cutting off, are done with tools mounted on cross-slides. A multi-spindle automatic bar machine has cross-slide tools and each of its spindle is able to take a bar.}

_{The multi-spindle automatic bar machine will continue to operate without attention until all the bars are used up. There is another type of automatic, that is quite similar in character but semi-automatic in operation. It is known as a multiple- spindle chucking machine. In these machines, the various operat­ions are performed on individual pieces, such as castings or forgings, instead of on barstock. Special chucks are provided at the end of the spindles, or standard power-operated chucks may be used. Each time the main spindle carrier indexes, a piece is released.}

_{§5.NUMERICAL CONTROL IN MACHINE TOOLS}

_{Numerical control started a revolution in manufacturing technology. It has won an ever increasing role as a method of controlling machine tools and other production equipment.}

_{Any system that accepts a symbolic numerical value as an input and converts it to a physical value, such as a dimension, as an output is providing numerical control. NC means that a program of machine operating commands directs some or all of the fundamental operations of a specific machine tool.}

_{Consistency is one of the advantages of an N C-programmed machine tool. It will do precisely what it has been told to do within the limit of its capability, and will not vary from its programmed instructions. The only exception to this would be wear or breakdown of one of the machine parts. The working effi­ciency of an N С machine tool is usually much higher than the most skilled manual effort. As, what an operator does visually, is done here electronically by a control unit.}

_{Quite often, new developments cause significant changes. However, NC has not changed individual metal cutting operations as much as it has changed the machine tools doing the operation.}

_{The result has been a three-step development of machine tools influenced directly by N C. First, conventional machine tools were redesigned specifically for operation by N C. The se- cond trend has been that of combining several operations in a}

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