Feed mechanism of lathe
. the parts of the feeding mechanism
. functional features of the feeding mechanism
Feed mechanism
The feed mechanism of a lathe enables automatic feeding for the tool longitudinally and transversely as needed. By automatic feeding the finish on the work will be better, the feeding of the tool will be at a uniform by continuous rate and it takes less time to finish the operation while manual labour is avoided.
The feed mechanism comprises
Spindle gear
Tumbler gear unit
Fixed stud gear
Change gear unit
Quick change gear box
Feed shaft/lead screw
Apron mechanism
The proportionate tool movement for each revolution of work is achieved through all the above units of the feed mechanism.
Spindle gear
The spindle gear is fitted to the main spindle, and it is outside the headstock casting. It revolves along with the main spindle.
Tumber gear unit
The tumbler gear unit itself is of three gears, having the same number of teeth and it contacts the spindle gear to the fixed gear. It is also called the reversing gear unit as it is used to change the direction of feed of the tool for the same direction of rotation of the spindle. It can be engaged and disengaged with the fixed stud gear by the operation of the hand lever provided in the unit.
The fixed stud gear
The fixed stud gear gets the drive from the main spindle gear through the tumbler gear unit and runs at the same number of revolutions per minute as the spindle gear on most lathes.
Change gear unit
The fixed stud gear transmits its drive through a change gear unit to the quick change gear box. The change gear units has provision for changing the driver the driven and the idler gears from the set of change gears available for the purpose of feed chaging as an additional unit.
Quick change gear box
The quick change gear box is provided with levers outside the box casting, and by shifting the levers, different gears are brought in mesh so that different feed rates can be given to the tool. A chart listing the different feed rates for the different positions of the levers is fixed to the casting, and by refering to the table, the levers may be engaged in position for the required feed rate.
The feed shaft
The feed shaft gets it drive from the quick change gear box, and through the apron mechanism, the rotary movement of the feed shaft is converted into the linear movement of the tool.
The apron mechanism
The apron mechanism has the arrangement for transmitting the drive from the feed shaft to the saddle for longitudinal movement of the tool or to the cross slide for the transverse movement of the tool
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