Drilling Machine: Types of Drilling Machine, Portable drilling machine, Sensitive drilling machine ~ MECHTECH GURU

Drilling Machine: Types of Drilling Machine, Portable drilling machine, Sensitive drilling machine

·        The drilling machine is one of the most important machine tools in a workshop. As regards its important is second only to the lathe.
·        It was primarily designed to originate a hole; it can perform a number of similar operations.
·        In drilling machine, holes may be drilled quickly and at a low cost. The hole is generated by rotating edge of a cutting tool known as ‘drill’, which exerts large force on the work clamped to the table.

                       Types of Drilling Machine:-

·        Drilling machines are made in many different types and sizes, each designed to handle a class of work or specific jobs to the best advantages.
·        The different types of drilling machines are:
1.               Portable drilling machine        5.     Gang drilling machine
2.               Sensitive drilling machine        6.     Multiple spindle drilling machine
A.                Bench mounting            7.     Automatic drilling machine
B.                Floor mounting             8.     Deep hole drilling machine
3.               Upright drilling machine                  A.     Vertical
A.                Round column section            B.     Horizontal
B.                Box column section
4.               Radial drilling machine
A.                Plain
B.                Semi universal
C.               Universal

    Portable drilling machine:-

·        As the name implies this type of drilling machine can be operated with ease anywhere in the workshop and is used for drilling holes in workshop in any position which cannot be drilled in a standard drilling machine.
·        Some of portable machine are operated by hand power but some of the machine are driven by individual motor.
·        The maximum size of hole it can accommodate is not more than 12 to 18 mm.

    Sensitive drilling machine:-

·        Sensitive drilling machine is a small machine designed for drilling small holes at a high speed in light jobs.
·        The base of machine may be mounted on a bench or on a floor.

Sensitive drilling machine
Sensitive drilling machine

1 Table, 2 Vertical drill spindle, 3 Sleeve, 4 Cone pulley, 5 V Belt, 6 Head, 7– Driving motor, 8 Vertical column, 9 Base

·        It consists of a vertical column, horizontal table, a head supporting motor and driving mechanism for driving and rotating the drill.
·        There is no automatic feed of drill spindle.
·        Drill is fed to the work by purely hand control.
·        Hand feed permits the operator to feel or sense the progress of the drill into work, so that if the drill becomes worn out or jams on any account, the pressure on the drill may be released immediately to prevent it from breaking.
·        Sensitive drilling machine are capable of rotating drills of diameter from 1.5 to 15.5mm

              Upright drilling machine:-

·        The upright drilling machine is designed for handling medium sized workpiece.
·        Its construction is very similar to a sensitive drilling machine for having a vertical column mounted upon the base.
·        But this is larger and heavier than sensitive drilling machine and is supplied with power feed arrangement.

            ·       In an upright drilling machine a large number of spindle speeds and feeds may be available for drilling different types of work.
·       There are two types of upright drilling machines.
1.     Round column section or pillar drilling machine
2.     Box column section

upright drilling machine
Upright drilling machine

1 Bevel gear drive to spindle, 2 Spindle, 3 Over head shaft, 4 Back stay, 5 Cointer shaft cone pulley, 6 Fast and loose pulley, 7 Table elevating handle, 8 Foot padel, 9 Base, 10 Rack on column, 11 Table elevating
clamp handle, 12 – Table clamp, 13 – Table, 14 – Column,
15 – Hand wheel forquick hand feed, 16 Hand wheel for sensitive hand feed

·       Round column section or pillar drilling machine consists of a round column that rises from the base which rests on the floor, an arm and a round table assembly and a drill head assembly.
·       The arm and the table have three adjustments for locating workpiece under spindle.
1.     Arm and table may be moved up and down on the column.
2.     Arm and table may be moved in arc up to 180o around the column.
3.     The table may be rotated 360o about its own center.
·       The construction of machine being not very rigid so useful for lighter work.
·       The maximum size of holes that the machine can drill is not more than 50 mm.
            ·       Upright drilling machine with box column section has the square table fitted on the slides at the front face of the machine column.
·       Heavy box column gives the machine strength and rigidity.
·       The table is raised or lowered by an elevating screw that gives additional support to the table.
·       This special feature permits machine to work with heavier workpiece and holes more than 50 mm diameter can be drilled by it.

              Radial drilling machine:-

·       The radial drilling machine is intended for drilling medium to large and heavy workpieces.
·       The machine consists of a heavy, round, vertical column mounted on large base.
·       The column supports a radial arm which can be raised and lowered and may be swing around to any position over the work bed.
·       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.

radial drilling machine
Radial drilling machine

1 Base, 2 Column, 3 Radial arm, 4 Motor for elevating the arm, 5 Elevating screw, 6 Guide ways,7 Motor for driving the drill spindle, 8 Drill head, 9 Drill spindle, 10 Table

·       These movements are useful to locate drill at any desired position.
·       When several holes are drilled on a large workpiece the position of arm and the drill may be moved from one position to other after drilling first hole without altering the setting of the workpiece.
·       In a Plain radial drilling machine, provisions are made for vertical adjustment of the arm, horizontal movement of the drill head along with the arm and circular movement of the arm in horizontal plane about the vertical column.
·       In a Semi universal drilling machine, in addition to the above three movement, the drill head can be swung about a horizontal axis perpendicular to the arm. This fourth movement of the drill head permits drilling hole at an angle to the horizontal plane other than the normal position.
·       In a Universal drilling machine, in addition to the above four movements, the arm holding the drill head may be rotated on a horizontal axis. All these five movements in a universal drilling machine enable it to drill on a workpiece at any angle.

              Gang drilling machine:-

·       When a number of single spindle drilling machine columns are placed side by side on a common worktable, machine is known as the gang drilling machine.
·       The speed and feed of the spindle may be controlled individually.
·       This type of machine is specially adapted for production work.
·       A series of operations may be performed on the work by simply shifting the work from on to other position on the work table.

              Multiple spindle drilling machine:-

·       The function of a multiple spindle drilling machine is to drill a number of holes in a piece of work simultaneously and to produce the same pattern of holes in a number of identical pieces in a mass production work.
·       The spindles are so constructed that their center distance may be adjusted in any position as per requirement of various jobs.

              Automatic drilling machine:-

·       Automatic machine can perform a series of machining operations at successive units and transfer the work from one unit to the other automatically.

·       Once the work is loaded at first machine then this will move from one machine to the other where different operations may be performed and finished product comes out at last without any manual handling.

              Deep hole drilling machine:-

·       Special machined and drills are required for drilling deep holes in rifle barrels, crank shaft, long shafts etc.
·       The machine is operated at high speed and low feed.
·       For that work is usually rotated while drill is fed into work and sometimes both work and drill are rotated.
·       The machine may be horizontal and vertical type.

                       Size of Drilling Machine

·        The size of a drilling machine varies with the type of machine being considered.
·        A portable drilling machine is specified by maximum diameter of the drill that it can hold.
·        The sensitive and upright drilling machines are specified by the diameter of the largest piece that can be centered under the spindle.
·        To specify a drilling machine fully further particulars such as the maximum size of drill that the machine can operate, table diameter, the maximum spindle travel, numbers of spindle speed and feeds available, Morse taper number of the drill spindle, power input, floor space required, net weight of the machine, etc. are all needed.
·        The size of the radial drilling machine is specified by the diameter of the column and length of the arm. Other particulars such as maximum drilling radius, minimum drilling radius, spindle speeds and feeds, etc. should also be stated to specify the machine fully.

                       Work Holding Devices:-

·       Before performing any operation in a drilling machine it is absolutely necessary to secure the work firmly on the drilling machine table.

·       The devices commonly used for holding the work in a drilling machine are:
     T - Bolts and Clamps
            Drill Press Vice
         Step Block
        V – Block
       Angle Plate
        Drill Jigs

·        One of the most common methods of holding the work directly on the drilling machine table is by means of T - bolt and clamp.

The diameter of T - bolts usually ranges from 15 to 20 mm.

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