The lathe is the main machine apparatus which appeared as a valuable machine for metal cutting. In this article, we explain the basic lathe mechanical engineering, what is lathe in mechanical engineering and list some principle parts in a lathe machine.
A lathe is one of the oldest and most important machine tool. The most common model is called a cinder lathe. In a cinder lathe, the workpiece or job is rotated and the cutting tool is smooth relative to the job. The tool motion may be parallel to the axis of rotation or perpendicular to it. The basic function of a lathe is to hold a workpiece and rotate it about an axis. A cutting tool is fet that is moved in a direction parallel or perpendicular to the axis of rotation. If the tool is more parallel to the axis of rotation, then a cylindrical surface is produced. The tool is more perpendicular to the axis of rotation then a flat surface is produced.
A lathe has the following principal parts: bed, headstock, tail stock, carriage, tool post, lead screw.
The bed is the foundation or base of the lathe and it has a convenient height. The bed provides sufficient strength rigidity and support to the machine. The top of the bed is made into straight and smooth pathway called guideway. The headstock, tailstock and carriage are mounted on the bed. The carriage and tailstock slide on these guide base. The bed is very heavy and made of cast iron, this is to absorb vibrations.
The headstock is permanently fixed at the left end of the lathe, inside it the drive mechanism for rotating the workpiece is situated the drive mechanism is a gearbox which gives the required speed and direction of rotation to the work. The headstock supports a hollow shaft called spindle.
Gearbox drives this spindle which rotates on its axis. At the right end of the spindle is a device for holding the workpiece. The most commonly used device for this is a Chuck. The workpiece is tightly gripped in the jaws of the Chuck, the Chuck has three jaws for easy centering of work. When the spindle rotates in the Chuck and thereby the workpiece rotates the primary drive for the lathe comes from an electric motor connected to the gear drive.
The tailstock is mounted on the right end of the lathe and can be moved along the guide base on the bed. The tailstock can be clamped at any position on the guide base according to requirement. Tailstock supports the right end of the workpiece, it is also useful supporting the tool like a drill bit during the drilling operation on the lathe.
The carriage is mounted between the headstock and tailstock. It moves the tool, allows the guide base parallel to the axis of rotation. The carriage has several parts, these parts hold the tool and control the motion of the tool. The base of the carriage is called saddle, it is a saddle that slides along the guide based on the top of the bed. It has an X shape cross slide. The cross slide is mounted on the saddle. It provides the motion in the direction perpendicular to the axis of rotation of the workpiece. This motion gives the depth of cut in turning.
The commode rest is mounted on the top of the cross slide, we can rotate and set the compound rest at any desired angle with respect to the workpiece. Compound rest can be moved in a straight line as well, but the range of movement is very small compared to the movement of the carriage.
Tool post is mounted on the compound rest. The cutting tool is held firmly on the tool post. Apron abran is a front part of the saddle, it hangs different of the bed apron consists of gears, clutches and livers for operating the movement of the carriage. There are handles provided on the apron to move the carriage and clothes light. When the hand wheel is stirred, the carriage slides along the guide base uniformly. The apron also consists of mechanisms for the automatic movement of the carriage.
The lead screw is a long threaded shaft, it is used only when thread cutting operation is to be done.
The feed rod is used for automated movement of carriage on the guide base.
Feed movement is the movement of the tool with respect to the workpiece. A lathe tool can be given three kinds of feed.
Longitudinal feed: The tool moves parallel to the axis of rotation of the workpiece.
Cross feed: The tool moves perpendicular to the axis of rotation of the workpiece.
Angular feed: the tool moves at an angle to the axis of rotation of diver piece.
All these speeds and depth of cut are related to the type of work material the depth of cut is small for hard material.