Boring Machine: Horizontal boring machine, Vertical boring machine, Precision boring machine, Jig boring machine

 Boring Machine:-

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·      
The boring machine
is one of the most
versatile machine tools
used to bore
holes in large and heavy
parts such as engine frame, steam engine cylinders, machine housing, etc. which are practically impossible to hold and
rotate in an engine lathe
or a drilling machine.
·      
In addition to its primary
purpose of boring
the range of speeds and feeds provided to the various traversing
components allow drilling, milling and facing to be performed with equal facility.
·      
By the fitting of simple attachments,
the use of the machine can be extended still
further to include screw cutting,
turning, planetary or gear cutting.


Types
of boring machine

·       The boring
machines may be classified under
the four headings:
1.          
Horizontal boring machine
A.                
Table type
B.                
Floor type
C.               
Planer
type
D.               
Multiple head type
2.            
Vertical boring machine
A.                
Vertical turret lathe
B.                
Standard vertical boring machine
3.          
Precision boring machine
4.          
Jig boring machine
A.                
Vertical milling machine type
B.                
Planer
type


                                              Horizontal boring machine:-

·       In
horizontal boring machine the work is supported on a table which is stationary
and the tool revolves in a horizontal axis.
·       A
horizontal boring machine can perform operation like boring, reaming, turning,
threading, facing, and grooving etc. with suitable
tools.
·       Workpiece which
are heavy, irregular, unsymmetrical can be conveniently held and
machined easily.
·       Table
type is the most common of all horizontal boring machines. In this boring
machine work is mounted on the table.
·       Table may be adjusted
by hand or power in lengthwise or crosswise.

·       The headstock
may be adjusted vertically on the column.
·       The
machine essentially consists of a bed, headstock, supporting column, end
supporting column, headstock, saddle and table,
and boring bar.
·       This machine
is suitable for general purpose
work where other
operation, in addition to boring are required
to be performed.

Horizontal boring Machine
Horizontal boring Machine



 1 Headstock, 2 Pulley
for counter balancing weight of  headstock, 3 Headstock elevating screw,
4 Boring head, 5 Boring
cutter on boring
bar, 6 Work, 7– End
supporting
column, 8 Bearing
block, 9 Saddle, 10 Cross
slide, 11 Table

Table type Horizontal boring Machine
Table type Horizontal boring Machine
1 Column base,
2 End supprting column,
3 Table, 4 Saddle, 5 Spindle, 6 – Head stock
supporting column, 7– Headstock, 8 Motor,

9 Bed
·       Floor type
horizontal boring machine
having no table
uses a stationary floor plate
on which T slots are provided to hold the work.
·       The headstock
supporting column and the end supporting column
are mounted on the runways which
are placed at right angles to the spindle axis.
·       This is so designed
for holding very
large and heavy
workpieces which are difficult to be
mounted and adjusted
on a table.

Floor type Horizontal boring Machine
Floor type Horizontal boring Machine

1 End supprting column, 2 –Column
base, 3 Spindle, 4 Floor
plate, 5 Head
stock supporting column,
6 Head stock, 7– Motor
 Floor type Horizontal boring Machine
·      
Planer type horizontal boring machine
resembles the table type but table slides directly on the bed instead of on a
saddle and reciprocates at right angles to the spindle similar to a planner.

·       The
end supporting column and headstock supporting column may be adjusted towards or away from the table for accommodating
different width of the work.
·       This type of machine
is suitable for supporting a long work.

Planer type Horizontal boring Machine
Planer type Horizontal boring Machine
1 End supporting column, 2 Column base,
3 Table, 4 Spindle, 5 Headstock supporting column,
6 Head stock, 7– Motor, 8 Bed
·       Multiple head
type horizontal boring
machine resembles a double housing
planer or a plano
miller. The table is supported on a long
bed on which
it reciprocates.
·       There are two vertical
columns at two sides of the bed, nearly at the middle of the bed.
The two columns
are bridged by a cross rail.
·       The machine
may have two, three or four headstocks. This type of machine may be
used both as a horizontal and vertical machine.
·       The
machining operations can be performed simultaneously at different work
surfaces.


Multiple head type Horizontal boring Machine
Multiple head type Horizontal boring Machine

1 Cross
rail, 2 Headstock, 3 Column,
4 Headstock, 5 Bed, 6 Table

  


           
Vertical boring machine:-


               ·       
In this boring machine work piece rotate
on a horizontal table and tool remains stationary except for the feed
Vertical boring Machine
Vertical boring Machine

1 Feed adjusting levers, 2 Tool box,
3 Tool head assembly, 4 Ram, 5 Housing,
6
Handwheel for ram adjustment, 7– Crossrail, 8 Fine
hand adjustmetn for
ram,9
Crossrail elevating
screw, 10 Table, 
11 Bed
·      
This
specific design of the machine
provides certain distinct advantages over a lathe
for a particular class of work. The advantages are:
1.     Large diameter and heavy workpieces, similar to chucking
jobs on a lathe, may be
set up more coveniently and quickly than on a lathe. It is easier to lay a
workpiece down on the table rather than to hang it up.
2.     The table and the work it carries rotate in a horizontal plane, and there is no overhang as in the case of a lathe
spindle, and consequently any chance of bending the spindle which supports the
heavy workpiece is eliminated.
3.    
The table being
horizontal, the diameter
of the table may be designed as large as possible to support large
workpieces.
4.    
Multiple tooling may be adapted in the
case a vertical boring machine with its
turret type tool post increasing the rate of production.
·       Vertical
turret lathe combines the advantages of the vertical boring mill and the turret lathe.
A vertical boring
machine of smaller
size is called
a vertical turret
lathe.
·       It has an indexable turret mounted upon the cross
rail above the table for multiple
tooling.
Vertical turret lathe
Vertical turret lathe

                     1
– Housing, 2 – Crossrail, 3 – Saddle, 4 – Turret, 5 – Table, 6 – Bed
             ·      
A four station
square turret side head which enables facing,
turning, under  cutting and many other operations is mounted at the side of the lathe.
·      
The cross rail may have vertical adjustments and for ease of operation
it is counter balanced.
·      
The turret mounted
on the saddle may be moved crosswise by hand or power. The turret may also be moved in a vertical
plane. The side head also has up and down and
to and fro adjustments from the center
of the table.
·      
The machine is suitable for boring and
turning railroad wheels, piston rings, gear
blanks, etc.
·      
Standard vertical boring machine
is larger in size than
vertical turret lathe
and there is no turret lathe.
·      
The machine is provided with two vertical
heads and one or two side heads.
·      
The machine is particularly intended for
boring large cylindrical and symmetrical workpiece.
·       Turbine castings, locomotive tires, etc. are some of the common examples
which need vertical boring machine.


          
Precision
boring machine:-

·       The precision boring machine uses single point
tools to machine
surfaces rapidly and accurately.
·       Cemented carbide
and diamond tipped
single point tools
are operated at a very high
cutting speed to produce accurately sized holes with a fine surface finish.
·       The feeding
movement may be provided by the tool or by the work.
·       The machine
may be horizontal or vertical
type.

          
Jig
boring machine:-

·      
The
jig boring machine
is the most accurate of all machine
tools. This was developed
in the year 1910 in Switzerland and used as a locating
machine. The real jig borer was first built in the year 1917 by Pratt and Whitney.
·      
The jig boring
machines are now
used for production of jigs, fixtures, tools and other precision parts which require
high degree of accuracy.
·      
They characterized by provisions of
highest accuracy through rigidity, low thermal 
expansion and precise
spacing holes.
·       The machining
accuracy is very high, within
range of 0.0025
mm.
·      
A jig boring
machine resembles in appearance to a vertical
milling machine, but so
far its operation and accuracy
are concerned there cannot be any comparison the two.


Jig boring Machine
Jig boring Machine

1 Spindle head,
2 Quill, 3 Column, 4 Spindle
housing, 5 Spindle, 6 Table, 7– Saddle, 8 Bed


 ·      
The spindle and other parts of the machine are extremely rigid
to resist deflection and the vibration is minimum.
·      
The spindle runs in preloaded antifriction bearing. The spindle housings are made of invar
having a very low coefficient of linear expansion.
·      
The jig boring machine requires
to be operated in temperature can be maintained constant. This is essential
to prevent inaccuracy in the machine in the work being manufactured due to thermal
expansion of the metal.
·      
Vertical milling machine type resembles
in construction to a vertical milling machine.
·      
The
spindle rotates on a vertical
column and the horizontal table
rests on the bed in front of the column.
·      
The positioning of the work mounted on
the table may be obtained by compound
movements of the table, perpendicular and parallel to the column
face.
·      
Planer type consists of two vertical
columns at the two sided of the table and is mounted on the base.
·      
The table has reciprocating movement for
adjustment of the work. The spindle is
mounted on the cross rail bridging
the two vertical columns.

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·      
In a planer type jig borer, two co –
ordinate movements for hole locations are provided by the longitudinal movement of the table and the cross
movement of the spindle along
the cross rail.




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