faceplate; thrust washers; bed; gear teeth; to cut threads; face plate; turret lathe; automatic screw machine; upright drilling machine; spindle; to mount smth; milling nachines; rotating cutters; gear drive; jack screw; spacing washers; locking nut; shaper; to lubricate with oil; tap; planer; slotting machine; rack-and-pinion drive; dog clutches.
Загальна максимальна рейтингова оцінка: 52 бали
ВАРІАНТ № 19.
Завдання № 1.
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MACHINE-TOOLS. COMPUTER CONTROL OF MACHINE-TOOLS
A machine-tool may be briefly defined as a power-driven machine used for producing a variety of shapes by cutting away the excess metal. The basic function of the lathe, as well as of any kind of machine-tool, is of two-fold nature: 1) to hold and control the metal being machined, and 2) to support and control the cutting tools which remove the metal. The range and variety of machine-tools being very great, it is sufficient to give here a short description of the most commonly used type, i. e. the lathe.
The lathe is a machine-tool in which the work (usually cylindrical or round) is held so that it can be rotated about an axis, while the cutting tool is traversed past the work from one end to the other, thereby forming it to the desired shape.
The lathe consists essentially of the following parts: the bed, the headstock, the tailstock and the saddle. The bed is a box-casting with machined “ways” in its upper surface; it is bolted to a heavy base which houses the driving motor and the electric switch gear. The headstock is fixed to the bed and carries the bearings, in which the spindle rotates. These bearings are automatically lubricated by a mechanical pump and can work under extreme conditions of low speeds for taking heavy cuts, and high speeds for taking light cuts. The lead screw is engaged through the change gears (not shown) for cutting threads. The apron houses the friction clutch, and the gearing which drives the feed mechanism. The speeds are obtained partly from the driving motor and partly by gears.
The idea of automatic control of production machines is not a new one. Tools which take stampings and castings and turn them into finished products without the touch of human hands are known to be used in many plants.
Computer control applied to machine-tools means production machines which are self-acting and self-regulating. Instructions to these machines are recorded on tape, and the taped data are interpreted into specific instructions to the production machine. There is a feedback which is used in order that the machine control unit can know what the production machine is doing, and how well it is carrying out the instructions.
One of the first to apply computer control to machine-tools was the aicraft industry.