Stepanova_LM_AM-123_Stanki_Part2_1978-1 (Станки), страница 4

_{single machine. The benefits here are obvious. If drilling, boring and milling can be accomplished on one machine at one set­-up with one operator the savings in setup time and in time re­quired to move the workpiece are immediately apparent. The third development - the machining centre - has made the greatest im-pact, thus far, in NС machine tool design.}

_{Words and word combinations to be remembered:}

_{apparent - очевидный, несомненный}

_{benefit - выгода}

_{breakdown - авария, поломка}

_{capability - способность, возможность}

_{consistency — постоянство}

_{control - управление}

_{conventional - обычный, стандартный}

_{efficiency - производительность}

_{impact - толчок, воздействие}

_{input - ввод, входной сигнал}

_{obvious - явный, очевидный}

_{output - выход, выходной сигнал}

_{saving - экономия}

_{trend - направление, тенденция}

_{value- значение, величина}

_{wear - износ}

_{thus far - до сих пор}

_{machining centre - обрабатывающий центр}

_{manufacturing technology - технология производства}

_{numerical control - числовое программное управление}

_Exercises.

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

_{технология производства; все возрастающая; любая система; в качестве ввода; команды, управляющие машиной; данного (опреде­ленного) станка; станок с числовым программным управлением; в пределах своих возможностей; производительность труда; новые достижения приводят к значительным изменениям; отдельные операции резания; обычные станки; за одну наладку; до сих пор; три этапа развития.}

_{II. Put the verb In brackets into the form of Participle I or
Participle II and translate the sentences.}

_{1. When (to introduce) numerical control started a revolution in manufacturing technology. 2. Although highly (to train) an ope­rator is unable to perform the operations more precisely than an NC-prоgrammed machine tool. 3. While (to accept) a symbolic numerical value as an input the system provides numerical cont­-rol. 4. When (to wear) one of the machine parts should be re- moved and replaced by a new one. 5. Though (to change) the ma-chine tools the new method of controling has not changed in­dividual metal cutting operations. 6. (to influence) directly by NC conventional machine tools were redesigned. 7. While (to combine) several operations NC-programmed machine tools provide great savings in setup time.}

_{III. Read the text and make up a summary.}

_{If we are to maintain a steady, continuous stream of parts into and out of automatic machines, we must be sure that there is al­ways a fresh part ready when the machine needs it, and that the completed part is taken out of the way and moved to the next ma­chine. The answer lies in the automatic conveyor.}

_{Depending upon the size, shape, and weight of the parts to be handled, the conveyor may be an overhead chain with books}¹ _{to carry the work, an under-floor chain to drag the work on small wheeled cars or a series of rollers along which the work can travel by gravity or be propelled by turning the rollers by power. Sometimes combinations of two or more of these methods may be employed, together with automatic elevators to raise or lower the work, as needed. The conveyor may start and stop at timed intervals, as on an automatic assembly line, giving each operator a certain period of time to perform his particular task; or it may run continuously to carry the work from place to place.}

_{In a fully conveyorized factory it is quite possible for work to progress from raw stack to finished part without ever being touched by hand. Under such conditions, the question na­turally arises as to what happens if a machine breaks down and interrupts the flow of material from one machine to the next. The answer is found in a system of "banks" or by the use of stand-by machines.}

_{1) overhead chain with hooks - подвесная цепь с крючхами.}

_{IV. Answer the questions.}

1. _{What new method of controlling machine tools do you know?}

2. _{Did it start a revolution in manufacturing technology?}

_{3. What does this control system accept as an input?}

_{4. Into what value is the symbolic numerical value converted?}

_{5. What operations does the program of machine operating com-}

_{­mands direct?}

1. _{Which is one of the advantages of an NC-programmed machine tool?}

2. _{When may the machine tool vary from its programmed instruct-}

_ions?

<sub>8. What about the working efficiency of an NC machine tool?
9. Has NC changed individual metal cutting operations?
l0.What has NC changed?</sub>

_{11.What was the first step in the development of machine tools? 12.What is the second trend in the development of machine tools? 13.Why are savings possible?}

_{l4.What kind of savings is provided?}

_{15.What trend has made the greatest impact in NC machine tool design?}

_{V. Retell the text.}

_{§6.MACHINING CENTRES}

_{The definite trend in NC machine tool design is toward accomplishing a number of different machining operations on a machine in a single setup. The highest order of this trend is the machining centre, where many operations, even tool chang- ing, is under program control.}

_{Here is a short description of a machining centre. A maxi­- mum of 60 cutting tools can normally be stored in four rows in a drum-type magazine on top of the column of the machining centre. If required, a magazine with a capacity for storing a maximum of 100 tools can be supplied. Vertical slots at the periphery of the magazine house rectangular carriers, each of which will accommodate a row of cutting tools. For tool chang­- ing, one of the carriers is brought into line with guideways at the front of the column, and is then moved downwards. At the end of a machining operation, the cutting tool which has}

_{been in service, is removed from the spindle and is replaced by another cutter from the carrier, by means of the transfer unit. Tools can be stored in the magazine in any order, and they can be selected and brought to a position ready for loading into the spindle while machining is being carried out on the work. It is stated that the actual tool changing operation is complet- ed in less than 5 s. The equipment will handle tools with dia­meters up to 100 mm and lengths up to 400mm.}

_{The machine is equipped with a special NC system, and the table incorporates indexing platen which enables different sur­faces on the work to be presented to the cutter in turn.}

_{Words and word combinations to be remembered:}

_*

_{to accomodate - вмещать, размещать}

_{drive - привод}

_{drum - барабан}

_{to house - вмещать, содержать}

_{magazine - магазин, бункер}

_{obtainable - доступный, достижимый}

_{periphery - окружность}

_{platen - cпутник}

_{slot - паз}

_{to store - хранить,вмещать}

_{in turn - поочередно, в свою очередь}

_{h p - horse power - лошадиные силы}

_{transfer unit — узел передачи}

_Exercises

_{I. Arrange the following words in groups of synonyms and trans-
late them:}

_{single, accomodate, usually, perform, house, different, one, normally, align, make possible, complete (v.), enable, various, incorporate, bring into line, finish (v.), carry out.}

_{II. Translate without a dictionary paying attention to the un-
derlined groups of words.}

_{1. A maximum travel of 41 1/2 in. is provided for the table saddle longitudinally on the bedways, and of 21 1/2 in. for the slide transversely. The spindle head has a maximum ver­tical movement of 9 5/8 in. Feeds ©an be varied from 0.16}

_{to 63 in/mm and rapid traverse is provided at the rate of 200 in/mm. Main drive is taken from a 7.5/5 – h p motor, and spindle speeds from 40 to 200 rev/min are obtainable.}

1. _{A maximum travel of 600 mm is provided for the spindle head saddle vertically.}

2. _{A cutting tool which was formerly held at the 3 o'clock posi­tion is brought into line with - and then loaded into - the spindle bore.}

3. _{Mounted in high-precision taper roller bearings and in an angular-contact bail bearing, the cutter spindle is driven by a 5.5 h p motor. (bearing - подшипник)}

_{III. Make up sentences with Predicative Infinitive Constructions.}

_{Example: Spindle speeds from 40 to 200 rev/min are obtainable}

_(believe).

_{Spindle speeds from 40 to 200 rev/min are believed to be obtainable.}

_{1. Even tool changing is under program control. (expect).}

_{2. Machining centres accomplish a number of different machin-}

_{ing operations in a single setup.(suppose)}

_{3. A maximum of 100 tools are stored in the magazine.(expect)}

_{4. Each rectangular carrier accomodates a row of cutting tools.}

_(say)

_{5. The actual tool changing operation is completed in less than}

_{5 s. (consider)}

_{6. The indexing platen enables different surfaces on the work}

_{to be presented to the cutter in turn.(assume)}

_{IV. Answer the questions:}

_{1. What kind of a device is a machining centre?}

_{2. How many cutting tools can be stored in the magazine of a}

_{machining center?}

_{3. Where is the magazine mounted?}

_{4. What is the maximum capacity for storing tools?}

_{5. What do the vertical slots house?}

_{6. What does each rectangular carrier accomodate?}

_{7. What is done for tool changing?}

_{8. What should be done at the end of a machining operation?}

_{9. In what order can the tools be stored in the magazine?}

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