Metal Lathe machine comprises a bed which is made up of grey cast iron.
On this lathe bed, there are other components like headstock, tailstock, carriage, feed mechanism, thread cutting mechanism, etc.
The major parts of lathe (engine lathe) are;
- Feed mechanism
- Thread cutting mechanism
Let’s see each of these lathe parts one by one.
Bed of the lathe machine is the base or foundation for all the other components which are mounted on it.
Lathe beds are rigid and made up of single piece casting which supports other parts of lathe.
The left side of the lathe bed consists of headstock, while the right side of the lathe bed consists of tailstock.
The carriage has a sliding mechanism and it slides over the bed of the lathe (see above image).
The top part of the lathe bed has a guideway which guides the tailstock to move forward and backward.
The guide ways on the bed can be V-shaped as well as squared shape.
The lathe beds are generally made up of cast iron alloyed with nickel and chromium material which gives more durability to the bed of lathe.
Headstock comprises of gear train arrangement and its main function is to transmit the power to other different parts of lathe.
The spindle is attached with the headstock of the lathe in which the workpiece is mounted.
This spindle rotates at a desired speed which ultimately rotates the workpiece mounted with it.
There is a cone puller arrangement in the headstock due to which variable spindle speeds can be achieved.
Also there is a back gear arrangement which gives slower speeds.
Headstock also consists of change wheels which produce different velocity ratios that are useful during a thread cutting operation on metal lathe.
In engine lathe, the main function of tail stock is to provide the support to the circular jobs which are being turned on the centers.
It is very easy to set the tailstock on the lathe bed with respect to the spindle centre.
To support one end of the workpiece, the tail stock contains a center which is known as dead center.
The love center and dead centers have the conical angle of 60° which fixes the job rigidly. The body of the dead center is tapered which gives better grip and fitting in the spindles.
The dead center can be mounted in the ball bearing so that it can rotate freely with the workpiece.
Carriage is one of the important parts of metal lathe which is mounted on an upper flat surface of the lathe bed.
This carriage is mounted in the guide ways which are made on the bed of lathe.
The motion of carriage is parallel to the spindle axis.
The important parts which a carriage holds are tool post, compound rest, apron, saddle, etc.
The lower part of the carriage contains gears which are used for adjusting the direction of the feed, and this lower part of the carriage is called apron.
On the carriage, there is a cross slide which travels perpendicular to the spindle axis.
On a cross slide, a saddle is mounted in which a compound rest is adjusted which can be rotated and fixed at a particular angle.
The tool post is a device which holds the tool holder in place with the help of a tool post screw.
Above image is a tool post of the center lathe.
Feed mechanism and Thread cutting mechanism
The feed mechanism is the mechanism in which a combination of different units transmits a motion of the headstock spindle to the carriage of the lathe machine.
The gearing which is present in the head stock transmits the rotary motion of the spindle to the feed gear box.
Through this feed gear, the motion is further transmitted to the lead screw or feed shaft. This generally depends on the weather the lathe is being used for plain turning operation or thread cutting operation.
There are different sizes of gears in the feed gear box which regulates the feed as well as ratio between revolution of headstock spindle and movement of carriage for thread cutting by changing the speed of rotation of lead screw or feed rod.
Apron is a hanging part in the front part of the carriage.
It consists of gear trains which give power feeds to the carriage and the cross slide. This helps to move the whole carriage in thread cutting operation.
Apron also consists of a clutch mechanism which is used to transmit the motion from the feed rod.
In other words, the apron consists of gears and clutches which transmits the motion from feed rod to the carriage and the half nut which engages with the lead screw during the thread cutting operation.
Hence, all the parts of engine lathe are very important and they have their special functions which are used for specific operations.