Numerical Control
план-конспект занятия по английскому языку (11 класс) на тему

Numerical Control

Vocabulary

initial- первоначальный                          particular-особый, отдельный

to define-определять                               sequencing-согласованный

accurate-точный, тщательный               semiconductor-полупроводник

precision-точность, четкость                 surface-поверхность

to insert-помещать                                  to employ-использовать

to implement-выполнять                         to draft-делать чертеж, составлять план

indicate-показатель

to accomplish-доводить до конца, завершать

x-y-z coordinates in a Cartesian axis system-трехмерная система координат

в Декартовой системе оси

to punch-штамповать, проделывать или пробивать отверстия

1.Read the text and translate it

        Numerical control is a form of programmable automation in which a machine is controlled by numbers (and other symbols) that have been coded on punched paper tape or an alternative storage medium. The initial application of numerical control was in the machine tool industry, to control the position of the cutting tool relative to the work part being machined. The NC part program represents the set of machining instructions for the particular part. The coded numbers in the program specify x-y-z coordinates in the Cartesian axis system, defining the various positions of the cutting tool in relation to the work part. By sequencing these positions in the program, the machine tool is directed to accomplish the machine of the part. A position feedback control system is used in most NC machines to verify that the coded instructions have been correctly performed. Today a small computer is used as the controller in an NC machine tool. Since this form of numerical control is implemented by computer, it is called computer numerical control, or CNC. Another variation in the implementation of numerical control involves sending part programs over telecommunication lines from a central computer to individual machine tools in the factory. This form of numerical control is called direct numerical control, or DNC.

         Many applications of numerical control have been developed since its initial use to control machine tools. Other machines using numerical control include component-insertion machines used in electronics assembly, drafting machines that prepare engineering drawings, coordinate measuring machines that perform accurate inspections of parts. In these applications coded numerical data are employed to control the position of a tool or work head relative to some object. Such machines are used to position electronic components (e.g., semiconductor chip modules) onto a printed circuit board (PCB). It’s basically an x-y positioning table that moves the printed circuit board relative to the part-insertion head, which then places the individual component into position on the board. A typical printed circuit board has dozen of individual components that must be placed on its surface; in many cases, the lead wires of the components must be inserted into small holes in the board, requiring great precision by the insertion machine. The program that controls the machine indicates which components are to be placed on the board and their locations. This information is contained in the product-design database and is typically communicated directly from the computer to the insertion machine.

2.Match the definite with their explanation

   1. Computer numerical control

   2. Direct numerical control

   3. Feedback control

   4. Numerical control

   5. Coordinate measuring machines

   6. Drafting machines

   7. Component-insertion machines

                a) The form of numerical control which involves sending part programs

                    from a central computer to individual machine tools.

                b) Machines that perform accurate inspections of parts.

                c) A form of control when a small computer is used as a numerical  

                    control machine tool.

                d) Machines that prepare engineering drawings.

                e) A form of programmable automation in which a machine is controlled

                    by numbers.

                f) Machines which are used in electronics assembly.

                g) A system of control which is used in most numerical control machines

                    to verify that the coded instructions have been correctly performed.

3.Answer the questions

   1.What does the term “numerical control” mean?

   2.What does the NC represent?

   3.How is the machine tool directed to accomplish the machining of the part?

   4.What purpose is a position feedback control system used for?

   5.Which of the variations in the implementation of NC called DNC?

   6.When have different applications of NC been developed?

   7.Where is information that controls the machine indicates contained?

4.Translate into English

    Закодированные инструкции, цифровой контроль, программированная  

    автоматизация, тщательно выполняемые инструкции, направленный на  

    завершение, показатели механизма, осуществление цифрового контроля,

    тщательная проверка, система контроля с обратной связью.