Chapter 2 machine tools

1. Read and translate the texts into Ukrainian or Russian paying attention to new words and word combinations

A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by machining, which is the selective removal of metal. The term machine tool is usually reserved for tools that used a power source other than human movement, but they can be powered by people if appropriately set up. Many historians of technology consider that the true machine tools were born when direct human involvement was removed from the shaping or stamping process of the different kinds of tools. For instance, they consider that lathe machine tools were invented around 1751 by Jacques de Vaucanson because he was the first to mount the cutting instrument on a mechanically adjustable head, taking it out of the hands of the operator. Machine tools can be powered from a variety of sources. Human and animal powers are options, as is energy captured through the use of waterwheels. However, machine tools really began to develop after the development of the steam engine, leading to the Industrial Revolution. Today, most are powered by electricity.

Machine tools can be operated manually, or under automatic control. Early machines used flywheels to stabilize their motion and had complex systems of gears and levers to control the machine and the piece being worked on. Soon after World War II, the NC, or numerical control, machine was developed. NC machines used a series of numbers punched on paper tape or punch cards to control their motion. In the 1960s, computers were added to give even more flexibility to the process. Such machines became known as CNC, or computerized numerical control, machines. NC and CNC machines could precisely repeat sequences over and over, and could produce much more complex pieces than even the most skilled tool operators.

Before long, the machines could automatically change the specific cutting and shaping tools that were being used. For example, a drill machine might contain a magazine with a variety of drill bits for producing holes of various sizes. Previously, either machine operators would usually have to manually change the bit or move the work piece to another station to perform these different operations. The next logical step was to combine several different machine tools together, all under computer control. These are known as machining centers, and have dramatically changed the way parts are made.

From the simplest to the most complex, most machine tools are capable of at least partial self-replication since they are machines, and produce machine parts as their primary function.

A broach is a series of progressively taller chisel points mounted on a single piece of steel, typically used to enlarge a circular hole into a larger non-circular shape such as a square or other desired shape.

Another typical use of a broach is to cut splines or a square key way on objects such as gears, drives hafts, pulleys etc. The amount of material removed by each broach tooth (or chisel) varies with the material being cut.

By the way all machine tools that use metal to shape metal have similar parts to carry out the shaping process many of which are made of alloys. Cutting tools must be made of materials that are harder than the metals and are capable of maintaining their cutting edge at friction temperatures. The most common materials used are high-speed steel, nonferrous metals containing tungsten, chromium, and cobalt, ceramicized aluminum-oxide and diamonds. In addition, it means of controlling the rate of feed, the depth and angle at which the tool cuts the workpiece and its position must be provided. A work holder, called a table or slide, to hold the part that is to be shaped and to move or feed it at a fixed speed against the tool. In some machines the table is stationary and the tool moves. Water and various types of oil are used to reduce friction temperatures and to lubricate the cutting area.

Machine tools can be classified according to size: light duty (weighing less than 1 tonne), medium duty (1 to 10 tonnes), and heavy duty (above 10 tonnes). Some people prefer classification according to the method of actuation: manually operated, semi-automatic, and fully automated. Another method of classification segregates machine tools according to purpose: general purpose machine tools, which can be used for a wide variety of operations, on a range of sizes of workpieces, and special purpose machine tools, for specific operations, on a limited range of workpiece sizes and shapes.

Another method classifies machine tools according to the types of motions used for removing material. Rotary cutting machines rotate workpiece (turning lathes, capstans, turrets), or the cutting tool (drill, milling cutter, grinding wheel), or both (cylindrical grinder).

Linear cutting machines remove material by moving the tool (shaping, slotting), or the workpiece (planning, surface grinding), in a straight line. In both the types of machine tools, linear motion is used for moving (feeding) the workpiece or the tool, to mate (engage) them for material removal. Feed classification can further subdivide machine tools as: The axial feed machines such as drilling machines that move the workpiece/ tool, parallel to the axis of the machine spindle, and the transverse feed machines, such as face milling machines that move the workpiece or tool, in a direction that is at right angle to the m/c spindle axis. Combined feed machines, such as center lathes and boring machines, can use both types of feeds.

machining - механічна обробка

shaping - фасонування; стругання; профілювання

stamping - штампування; карбування; видавлювання

cutting instrument - різальний інструмент

adjustable head — регульована голівка

NC machines — верстати із числовим програмним забезпечуванням

paper tape — паперова стрічка

punch cards — перфорована карта

CNC or computerized numerical control - числове програмне управління

magazine - комплект

drill bit — свердлувальне лезо, голівка

chisel - стамеска; зубило; долото

spline - шпонкова канавка; шліц

drives hafts — рухомі рукоятки

pulley - шків

friction temperature — температура терття; підвищення температури внаслідок терття

workpiece — заготовка (заготівка); деталь,що обробляється

table — стіл (золотник)

slide — золотник (стіл)

lubricate - змащувати

cutting area — ріжуча площа

ceramicized aluminum oxide — керамізований окис алюмінію

light duty — спрощений режим різання

medium duty — нормальний (середній) режим різання

heavy duty — складний режим різання

manually operated — керований вручну

semi-automatic - напівавтоматичний

fully automated — цілком автоматичний

segregate - відокремлювати, виділяти

general purpose machine tool — верстат загального призначення

removing material — матеріал, що переміщується

rotary cutting machine — ротаціонний різальний верстат

turning lathe — токарний верстат

capstan - револьверна головка (верстата); головка (болта) з отворами

turret - револьверна головка (верстата), револьверний супорт

cutting tool - різець

drill - свердло

milling cutter — фрезерний ріцезь, фреза

grinding wheel — шліфувальне колесо

cylindrical grinder — циліндрошліфувальний верстат

linear cutting machine — лінійний металорізальний верстат

shaping - фасонування; стругання

slotting - видовбування або прорізання пазів, канавок

planning — стругання

surface grinding — плоске шліфування

feeding — подача, постачання

mate -  з'єднувати; сполучати; зачіплятися (про зубчасті колеса)

axial feed machine — верстат з осівою подачею

face milling machine - верстат для фрезерування площини, поздовжньо-фрезерний верстат

center lathe - центровий токарний верстат

boring machine — розточувальний верстат