DRILLING AND BORING MACHINES

DRILLING AND BORING MACHINES

DRILLING AND BORING MACHINES Introduction: The drilling machine or drill press is one of the most common and useful machine employed in industry for producing forming and finishing holes in a workpiece. The unit essentially consists of: 1.A spindle which turns the tool (called drill) which can be advanced in the workpiece eitherautomatically or by hand. 2.A work table which holds the workpiece rigidly in position.

WORKING PRINCIPLE OF DRILLING:-
Drilling is the process (operation) of making holes in a solid metal (workpiece) by means of a rotating cutting tool called drill. It is one of the most common operations in the manufacturing industry. In this operation can’t produce a perfectly true hole. It is considered as a roughing operation. So drill is followed by another operation called reaming. In reaming operation the required dimensional accuracy & fine surface finish is obtained means of a multi tooth revolving tool called reamer. In this, the workpiece is held stationary during the process.

The main operating parts of a sensitive machine/drill press are Base, Column, Table, and Drill Head.

1. Base: The base is a heavy casting that supports the machine structure; it provides rigid mounting for the column and stability for the machine. The base is usually provided with holes and slots which help to Bolt the base to a table or bench and allow the work-holding device or the workpiece to be fastened to the base.

2. Column: The column is a vertical post that Column holds the worktable and the head containing the driving mechanism. The column may be of round or box section.

3. Table: The table, either rectangular or round. Drill machine/press in shape supports the workpiece and is carried by the vertical column. The surface of the table is 90-degree to the column and it can be raised, lowered and swiveled around it. The table can be clamp/hold the required the workpiece. Slots are provided in most tables to allow the jigs, fixtures or large workpieces to be securely fixed directly to the table.

4. Drilling Head: The drilling head, mounted close to the top of the column, houses the driving arrangement and variable speed pulleys. These units transmit rotary motion at different speeds to the drill spindle. The hand feed lever is used to control the vertical movement of the spindle sleeve and the cutting tool.

Different types of drilling machines and their features:-
1. Portable drilling machine 2. Sensitive or bench drill 3. Upright drilling machine (single spindle) 4. Upright drilling machine (Turret type) 5. Radial drilling machine 6. Multi spindle drilling machine 7. Deep hole drilling machine. 8. Gang drilling


Boring:

Boring is the process of using a single point tool to enlarge and locate a previously made hole. Drills tend to wander or drift, thus, where greater accuracy is required, drilling is followed by boring and reaming.
Classification of boring machines:-
Boring machines are manufactured in various different designs and sizes. They can broadly be classified into the following three types:
1. Horizontal boring machine,
2. Vertical boring machine,
3. Jig boring machine.
The above three, the first two types include production machines, used in general production work, last one is a precision machine used for precision boring operations, such as jig boring.