Metalworking lathes

A CNC metalworking lathe

In a metalworking lathe, metal is removed from the workpiece using a hardened cutting tool, which is usually fixed to a solid moveable mounting, either a tool-post or a turret, which is then moved against the workpiece using handwheels and/or computer controlled motors. These (cutting) tools come in a wide range of sizes and shapes depending upon their application. Some common styles are diamond, round, square and triangular.

The tool-post is operated by lead-screws that can accurately position the tool in a variety of planes. The tool-post may be driven manually or automatically to produce the roughing and finishing cuts required to turn the workpiece to the desired shape and dimensions, or for cutting threads, worm gears, etc. Cutting fluid may also be pumped to the cutting site to provide cooling, lubrication and clearing of swarf from the workpiece. Some lathes may be operated under control of a computer for mass production of parts. Manually controlled metalworking lathes are commonly provided with a variable ratio gear train to drive the main lead-screw. This enables different thread pitches to be cut. On some older lathes or more affordable new lathes, the gear trains are changed by swapping gears with various numbers of teeth onto or off of the shafts, while more modern or expensive manually controlled lathes have a quick change box to provide commonly used ratios by the operation of a lever. CNC lathes use computers and servomechanisms to regulate the rates of movement.

The workpiece may be supported between a pair of points called centres, or it may be bolted to a faceplate or held in a chuck. A chuck has movable jaws that can grip the workpiece securely.

EXERCISES:

I. Find in the texts the following topical words and phrases, explain what they mean, and add them to your Active Vocabulary:

three jaw chucks; collets; spindle; carriage; apron; stand; bed; headstock; tailstock; faceplate ; four-jaw chuck; collet; dead center; live center

II. Write out from the texts the sentences or the parts of the sentences which contain the following words and expressions and translate them into Russian:

A saddle, high-precision spinning bearings, internal taper, ball bearings, frictional heat, lubrication, auxiliary operations.

III. Answer the following questions:

1) What are the main parts of a lathe?

2) How can a workpiece be hold in a lathe?

3) What is the main function of centers?

4) What is the carriage used for?

5) What parts does the carriage consist of?

TRANSLATION

EXERCISES:

I. Before translating the text, find in it the sentences in which you would be able to use the following topical words and expressions:

A saddle, an apron, cross-slide, a bed, three-jaw chuck, headstock, tailstock, solid moveable mounting, roughing and finishing cuts, lead-screw.

II. Read the text again, find in it the information about the following questions, and answer them using the topical words and phrases:

1. What is the basement of any lathe?

2. How can a workpiece be fixed on the lathe?

3. What part of the lathe controls feed mechanisms?

4. What part of the lathe can the tailstock be fixed to?

5. How can the spindle be rotated to a precise angle?

TEXT B