DRILLING MACHINE
..1 INTRODUCTION
Drilling is an operation of making a circular hole by removing a volume of metal from
the job by cutting tool called drill. A drill is a rotary end-cutting tool with one or more cutting
lips and usually one or more flutes for the passage of chips and the admission of cutting fluid.
A drilling machine is a machine tool designed for drilling holes in metals. It is one of the most
important and versatile machine tools in a workshop. Besides drilling round holes, many
other operations can also be performed on the drilling machine such as counter- boring,
countersinking, honing, reaming, lapping, sanding etc.
2 CONSTRUCTION OF DRILLING MACHINE
In drilling machine the drill is rotated and fed along its axis of rotation in the stationary
workpiece. Different parts of a drilling machine are discussed
below: (i) The head containing electric motor, V-pulleys and V-belt which transmit rotary
motion to the drill spindle at a number of speeds. (ii) Spindle is made up of alloy steel. It
rotates as well as moves up and down in a sleeve. A pinion engages a rack fixed onto the
sleeve to provide vertical up and down motion of the spindle and hence the drill so that the
same can be fed into the workpiece or withdrawn from it while drilling. Spindle speed or the
drill speed is changed with the help of V-belt and V-step-pulleys. Larger drilling machines are
having gear boxes for the said purpose. (iii) Drill chuck is held at the end of the drill spindle
and in turn it holds the drill bit. (iv) Adjustable work piece table is supported on the column
of the drilling machine. It can be moved both vertically and horizontally. Tables are generally
having slots so that the vise or the workpiece can be securely held on it. (v) Base table is
a heavy casting and it supports the drill press structure. The base supports the column, which
in turn, supports the table, head etc. (vi) Column is a vertical round or box section which rests
on the base and supports the head and the table. The round column may have rack teeth cut
on it so that the table can be raised or lowered depending upon the workpiece requirements.
This machine consists of following parts
1. Base
2. Pillar
3. Main drive
4. Drill spindle
3 TYPES OF DRILLING MACHINE
Drilling machines are classified on the basis of their constructional features, or the type
of work they can handle. The various types of drilling machines are:
(1) Portable drilling machine
(2) Sensitive drilling machine
(a) Bench mounting
(b) Floor mounting
(3) Upright drilling machine
(a) Round column section
(b) Box column section machine
(4) Radial drilling machine
(a) Plain
(b) Semiuniversal
(c) Universal
(5) Gang drilling machine
(6) Multiple spindle drilling machine
(7) Automatic drilling machine
(8) Deep hole drilling machine
(a) Vertical
(b) Horizontal
Few commonly used drilling machines are described as under:
1 Portable Drilling Machine
A portable drilling machine is a small compact unit and used for drilling holes in worpieces
in any position, which cannot be drilled in a standard drilling machine. It may be used for
drilling small diameter holes in large castings or weldments at that place itself where they
are lying. Portable drilling machines are fitted with small electric motors, which may be
driven by both A.C. and D.C. power supply. These drilling machines operate at fairly high
speeds and accommodate drills up to 12 mm in diameter.
2 Sensitive Drilling Machine
It is a small machine used for drilling small holes in light jobs. In this drilling machine,
the workpiece is mounted on the table and drill is fed into the work by purely hand control.
High rotating speed of the drill and hand feed are the major features of sensitive drilling
machine. As the operator senses the drilling action in the workpiece, at any instant, it is
called sensitive drilling machine. A sensitive drilling machine consists of a horizontal table,
a vertical column, a head supporting the motor and driving mechanism, and a vertical spindle.
Drills of diameter from 1.5 to 15.5 mm can be rotated in the spindle of sensitive drilling
machine. Depending on the mounting of base of the machine, it may be classified into
following types:
1. Bench mounted drilling machine, and
2. Floor mounted drilling machine
3 Upright Drilling Machine
The upright drilling machine is larger and heavier than a sensitive drilling machine. It
is designed for handling medium sized workpieces and is supplied with power feed arrangement.
In this machine a large number of spindle speeds and feeds may be available for drilling
different types of work. Upright drilling machines are available in various sizes and with
various drilling capacities (ranging up to 75 mm diameter drills). The table of the machine
also has different types of adjustments. Based on the construction, there are two general
types of upright drilling machine:
(1) Round column section or pillar drilling machine.
(2) Box column section.
The round column section upright drilling machine consists of a round column whereas
the upright drilling machine has box column section. The other constructional features of
both are same. Box column machines possess more machine strength and rigidity as compared
to those having round section column.
4 Radial Drilling Machine
The radial drilling machine consists of a
heavy, round vertical column supporting a horizontal arm that carries the drill head. Arm can
be raised or lowered on the column and can also be swung around to any position over the
work and can be locked in any position. The drill head containing mechanism for rotating and
feeding the drill is mounted on a radial arm and can be moved horizontally on the guide-ways
and clamped at any desired position. These adjustments of arm and drilling head permit the
operator to locate the drill quickly over any point on the work. The table of radial drilling
machine may also be rotated through 360 deg. The maximum size of hole that the machine
can drill is not more than 50 mm. Powerful drive motors are geared directly into the head
of the machine and a wide range of power feeds are available as well as sensitive and geared
manual feeds. The radial drilling machine is used primarily for drilling medium to large and
heavy workpieces. Depending on the different movements of horizontal arm, table and drill
head, the upright drilling machine may be classified into following types-
1. Plain radial drilling machine
2. Semi universal drilling machine, and
3. Universal drilling machine.
..1 INTRODUCTION
Drilling is an operation of making a circular hole by removing a volume of metal from
the job by cutting tool called drill. A drill is a rotary end-cutting tool with one or more cutting
lips and usually one or more flutes for the passage of chips and the admission of cutting fluid.
A drilling machine is a machine tool designed for drilling holes in metals. It is one of the most
important and versatile machine tools in a workshop. Besides drilling round holes, many
other operations can also be performed on the drilling machine such as counter- boring,
countersinking, honing, reaming, lapping, sanding etc.
2 CONSTRUCTION OF DRILLING MACHINE
In drilling machine the drill is rotated and fed along its axis of rotation in the stationary
workpiece. Different parts of a drilling machine are discussed
below: (i) The head containing electric motor, V-pulleys and V-belt which transmit rotary
motion to the drill spindle at a number of speeds. (ii) Spindle is made up of alloy steel. It
rotates as well as moves up and down in a sleeve. A pinion engages a rack fixed onto the
sleeve to provide vertical up and down motion of the spindle and hence the drill so that the
same can be fed into the workpiece or withdrawn from it while drilling. Spindle speed or the
drill speed is changed with the help of V-belt and V-step-pulleys. Larger drilling machines are
having gear boxes for the said purpose. (iii) Drill chuck is held at the end of the drill spindle
and in turn it holds the drill bit. (iv) Adjustable work piece table is supported on the column
of the drilling machine. It can be moved both vertically and horizontally. Tables are generally
having slots so that the vise or the workpiece can be securely held on it. (v) Base table is
a heavy casting and it supports the drill press structure. The base supports the column, which
in turn, supports the table, head etc. (vi) Column is a vertical round or box section which rests
on the base and supports the head and the table. The round column may have rack teeth cut
on it so that the table can be raised or lowered depending upon the workpiece requirements.
This machine consists of following parts
1. Base
2. Pillar
3. Main drive
4. Drill spindle
3 TYPES OF DRILLING MACHINE
Drilling machines are classified on the basis of their constructional features, or the type
of work they can handle. The various types of drilling machines are:
(1) Portable drilling machine
(2) Sensitive drilling machine
(a) Bench mounting
(b) Floor mounting
(3) Upright drilling machine
(a) Round column section
(b) Box column section machine
(4) Radial drilling machine
(a) Plain
(b) Semiuniversal
(c) Universal
(5) Gang drilling machine
(6) Multiple spindle drilling machine
(7) Automatic drilling machine
(8) Deep hole drilling machine
(a) Vertical
(b) Horizontal
Few commonly used drilling machines are described as under:
1 Portable Drilling Machine
A portable drilling machine is a small compact unit and used for drilling holes in worpieces
in any position, which cannot be drilled in a standard drilling machine. It may be used for
drilling small diameter holes in large castings or weldments at that place itself where they
are lying. Portable drilling machines are fitted with small electric motors, which may be
driven by both A.C. and D.C. power supply. These drilling machines operate at fairly high
speeds and accommodate drills up to 12 mm in diameter.
2 Sensitive Drilling Machine
It is a small machine used for drilling small holes in light jobs. In this drilling machine,
the workpiece is mounted on the table and drill is fed into the work by purely hand control.
High rotating speed of the drill and hand feed are the major features of sensitive drilling
machine. As the operator senses the drilling action in the workpiece, at any instant, it is
called sensitive drilling machine. A sensitive drilling machine consists of a horizontal table,
a vertical column, a head supporting the motor and driving mechanism, and a vertical spindle.
Drills of diameter from 1.5 to 15.5 mm can be rotated in the spindle of sensitive drilling
machine. Depending on the mounting of base of the machine, it may be classified into
following types:
1. Bench mounted drilling machine, and
2. Floor mounted drilling machine
3 Upright Drilling Machine
The upright drilling machine is larger and heavier than a sensitive drilling machine. It
is designed for handling medium sized workpieces and is supplied with power feed arrangement.
In this machine a large number of spindle speeds and feeds may be available for drilling
different types of work. Upright drilling machines are available in various sizes and with
various drilling capacities (ranging up to 75 mm diameter drills). The table of the machine
also has different types of adjustments. Based on the construction, there are two general
types of upright drilling machine:
(1) Round column section or pillar drilling machine.
(2) Box column section.
The round column section upright drilling machine consists of a round column whereas
the upright drilling machine has box column section. The other constructional features of
both are same. Box column machines possess more machine strength and rigidity as compared
to those having round section column.
4 Radial Drilling Machine
The radial drilling machine consists of a
heavy, round vertical column supporting a horizontal arm that carries the drill head. Arm can
be raised or lowered on the column and can also be swung around to any position over the
work and can be locked in any position. The drill head containing mechanism for rotating and
feeding the drill is mounted on a radial arm and can be moved horizontally on the guide-ways
and clamped at any desired position. These adjustments of arm and drilling head permit the
operator to locate the drill quickly over any point on the work. The table of radial drilling
machine may also be rotated through 360 deg. The maximum size of hole that the machine
can drill is not more than 50 mm. Powerful drive motors are geared directly into the head
of the machine and a wide range of power feeds are available as well as sensitive and geared
manual feeds. The radial drilling machine is used primarily for drilling medium to large and
heavy workpieces. Depending on the different movements of horizontal arm, table and drill
head, the upright drilling machine may be classified into following types-
1. Plain radial drilling machine
2. Semi universal drilling machine, and
3. Universal drilling machine.
No comments:
Post a Comment