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Slotting Machine
A slotting machine is a type of reciprocating machine. The tool is held in the ram, which reciprocates vertically and the workpiece is held on the table. The slotter has a base upon which the column is being integrated. The column houses the driving mechanism for the ram. The top portion of the ram has the guideways. With the help of these guides ways, the ram reciprocates vertically. This reciprocation is achieved by the quick return mechanism. The base has horizontal guideways which enable the saddle to move perpendicular to the column.
The top face of the saddle has guideways. These guideways are perpendicular to the guideways present in the base over which a cross slide moves. This movement is parallel to the column face.
A circular-shaped rotary table is mounted on top of the cross slide. This rotary table can be rotated about a vertical axis parallel to the column. This movement is the circular feed for the table. All the feeding systems are graduated.
T-slots are being provided on the table for holding the workpiece. With the longitudinal feed of the saddle, the cross feed of the cross slide, and the rotary movement of the table in all these feeding mechanisms the feed can either be given by hand or by power.
Quick return mechanism
Metal from the workpiece is removed only during the cutting stroke. During the return stroke, no metal is removed. To reduce the idle time of the return stroke, quick return mechanisms are being used. The following are the generally used quick return mechanisms in a slotting machine.
- Whitworth quick return mechanism.
- Variable-speed reversible electric motor drive.
- Hydraulic drive.
Feed mechanisms
The following are the feed mechanisms generally used in a slotter.
· Longitudinal feed: This movement is achieved by moving the saddle either towards or away from the column.
· Crossfeed: This is obtained by moving the cross slide parallel to the face of the column.
· Circular feed: This is obtained by rotating the table about a vertical axis.
Automatic feed
A groove for the cam is cut on the face of the bull gear of the driving mechanism of the slotter. A roller follower slides in this groove. The roller is fixed at one end of the lever. The lever is pivoted in the middle, and the other end of the lever has a slot. In this slot, a feed adjustment pin is fitted.
This pin is connected by a connecting rod to the pawl and ratchet mechanism.
The bull gear starts to rotate, and the follower follows the groove profile. When the lobe portion of the cam groove passes the follower, the slotted end of the lever moves up and down. This makes the pawl rotate the ratchet wheel. The ratchet is keyed to the feed shaft. This feed shaft is engaged with the longitudinal, cross, or rotary feed screws. This makes it achieve automatic feed.
The amount of feed can be adjusted by shifting the location of the feed adjustment pin in the lever slot.