Lathe machine

Lathe machine

Lathe machine is a heavy machine. We can do all kind of job work on lathe machine. A work we need to do to complete the job work can be done on lathe machine. Operating lathe machine is difficult. Only those people can operate lathe machine who know how to operate them. Many kind of job work is done on a single lathe machine like drilling, plain turning, step turning, facing, parting, boring, threading, forming etc. One who knows how to operate lathe machine can operate all machines. The lathe has been classified into various types according to their design, construction, and application.

Engine lathe or Centre lathe:

Centre lathe is the most important member of the lathe machine family and is commonly used in industries. The machine has a large number of speed steps, and the tool supported on a tool post can be given controlled power feed with the help of a carriage, feed rod or a lead screw. The machine is capable of performing a wide variety of operations such as turning, facing, drilling, boring and threading etc.

Bench lathe:

Bench lathe is a small lathe machine which can be mounted on the work bench. Its constructional features are the same as that of engine lathe; it differs only in size and mountings. Lathe of this type are used for doing small precision and light jobs such as instrument making and watch repairing etc.

Tool room lathe:

Tool room lathe is a modern engine lathe having all geared headstock with a very wide range of speeds. The machine is equipped with accessories such as quick changing gears, separate lead screw and feed rod, steady rest, taper turning attachment, draw in Collet attachment etc.

Speed lathe:

Speed lathe is the simplest of all lathes and consists of a bed supported on legs, a headstock, a tail-stock, and a tool post for support in the tool. There is no gear box, lead screw, and carriage. The tool control is manual. The tool is feed and controlled by hand wheel. These machines run at high speeds and are advantageously used for wood turning, metal spinning, and polishing operations.

Turret and Capstan lathes:

These are production lathes used for producing large number of identical components. The turret can accommodate six tools which can be indexed and fed into the work piece in a proper sequence. This aspect helps in time saving in changing and setting tools, avoids unnecessary movement and achieves better quality control. With these machines, the supervision is simplified and much less skill is needed except for setting the machine.

Automatic lathes:

Automatic lathes machines are high speed heavy duty lathes in which the various controls like feeding the raw material, tool change, feed; speed change and unloading the work piece are automatically controlled. Once the particular attachment and tools are set, all the operations performed automatically till the job is completed.

Special purpose lathes:

Special purpose lathes machines are designed for producing definite type of work that involves certain specific operations that cannot be performed on standard lathe machines.

Working Principle: The lathe is a machine tool which holds the work piece between two rigid and strong supports called centers or in a chuck or face plate which revolves. The cutting tool is rigidly held and supported in a tool post which is fed against the revolving work. The normal cutting operations are performed with the cutting tool fed either parallel or at right angles to the axis of the work.

The cutting tool may also be fed at an angle relative to the axis of work for machining tapers and angles.

Construction: The main parts of the lathe are the bed, headstock, quick changing gear box, carriage, and tailstock.

1. Bed: The bed is a heavy, rugged casting in which are mounted the working parts of the lathe. It carries the headstock and tail stock for supporting the work piece and provides a base for the movement of carriage assembly which carries the tool.

2. Legs: The legs carry the entire load of machine and are firmly secured to floor by foundation bolts.

3. Headstock: The headstock is clamped on the left hand side of the bed and it serves as housing for the driving pulleys, back gears, headstock spindle, live Centre, and the feed reverse gear. The headstock spindle is a hollow cylindrical shaft that provides a drive from the motor to work holding devices.

4. Gear Box: The quick-change gear-box is placed below the headstock and contains a number of different sized gears.

5. Carriage: The carriage is located between the headstock and tailstock and serves the purpose of supporting, guiding, and feeding the tool against the job during operation. The main parts of carriage are:

a) The saddle is an H-shaped casting mounted on the top of lathe ways. It provides support to cross-slide, compound rest and tool post.

b) The cross slide is mounted on the top of saddle, and it provides a mounted or automatic cross movement for the cutting tool.

c) The compound rest is fitted on the top of cross slide and is used to support the tool post and the cutting tool.

d) The tool post is mounted on the compound rest, and it rigidly clamps the cutting tool or tool holder at the proper height relative to the work Centre line.

e) The apron is fastened to the saddle and it houses the gears, clutches and levers required to move the carriage or cross slide. The engagement of split nut lever and the automatic feed lever at the same time is prevented she carriage along the lathe bed.

6. Tailstock: The tailstock is a movable casting located opposite the headstock on the ways of the bed. The tailstock can slide along the bed to accommodate different lengths of work piece between the centers. A tailstock clamp is provided to lock the tailstock at any desired position. The tailstock spindle has an internal taper to hold the dead Centre and the tapered shank tools such as reamers and drills.