10.A] Explain the principle of working of horizontal milling machine
Answer:-
Horizontal Milling Machine
The schematic arrangement of the horizontal milling machine/ column and knee typr milling machine as shown in the figure.
Milling machine has some principal parts.
Their understanding would help us in understanding how the machine operates.
The various parts are
- Base
- Column
- Arbor
- Knee
- Saddle
- Table
- Overhanging arm
- Driving and feeding Mechanism
Base:
- The base forms the foundation of the machine tool.
- It’s a rectangular casting made up of Cast Iron.
- The one end of the base houses the Column and another end of the base contains a space for a table elevating screw or knee supporting screw.
Column:
- The column is another rectangular casting mounted on one end of the base.
- The column is ribbed heavily in order to support the knee.
- The front vertical face of the column is provided with a vertical slide, which may be of square or dovetail type.
- The knee moves up and down on this slide.
- At the top of the column, an internal dovetail slide accommodates a cast overarm. The overarm supports the arbor. It also houses the driving mechanism to drive the spindle and the feeding mechanism to feed the table.
Arbor:
- The arbor is a horizontal shaft provided with a straight body and tapered shank.
- On the straight portion of the arbor, rotary cutters are mounted.
- The tapered end of the arbor fits into the tapered hole of the spindle.
- The other end of the arbor is mounted in a bearing housed in the projecting overarm.
- The knee of the casting is mounted on the front vertical slide of the column and is moved up or down by an elevating screw.
- The upper face of the knee is provided with guideways so as to mount the saddle.
Knee:
- The Knee is a casting mounted on the front vertical slide of the column and is moved up or down by an elevating screw.
- The upper face of the knee is provided with guideways so as to mount the saddle.
Saddle:
- The saddle is casting provided with two slides one at the top and the other at the bottom, which is exactly right angles to each other.
- The lower slide fits within the guideways on the top of the knee and the upper slide receives the dovetail guides provided at the bottom of the table.
Table:
- The table is mounted on the top of the saddle.
- The bottom of the table has a dovetail slide that fits in the slideway on the top of the saddle.
- The top table is machined with full-length T-slots for mounting vices or other work holding fixtures. Overhanging
Arm:
- The overhanging arm extends from the column in order to support the arbor.
- The front brace attached to the overhanging arm supports the free end of the arbor and thus provides rigidity to the rotating cutter.