Taper turning method for engine lathe

1. K.J. INSTITUTE OF
ENGG. AND TECH.

2. NAME : SHETHWALA UZEFA M. (130640119113)
BRAHAMBHATT RUSHI (130640119103)
RABARI PRAKASH (130640119098)
BRANCH : MECHANICAL [B]
SUBJECT : MP-1

3. TAPER TURNING
METHOD FOR ENGINE
LATHE

4. Head stock
Spindle
Guide ways
Feed rod
Spindle
speed
Compound rest
and slide(swivels)
Bed
Carriage
Apron
selector
Feed change
gearbox
Lead screw
Cross slide
Dead center
Tool post
Tailstock quill
Tailstock
Handle

5. Engine Lathe
Speed Lathe
Bench Lathe
Tool Room Lathe
Special Purpose Lathe
Gap Bed Lathe

6. Turning
Drilling
Milling
Roughing
Finishing

7. Taper turning means, to produce a conical
surface by gradual reduction or increase in
diameter from a cylindrical work piece.
This tapering operation has wide range of
use in construction of machines. Almost all
machine spindles have taper holes which
receive taper shank of various tools and
work holding devices.

9. Taper Turning Methods: A taper may be
turned by any one of the following
methods:
(A) By a broad nose form tool.
(B) By setting over the tailstock centre.
(C) By swivelling the compound rest.
(D) By a taper turning attachment
(E) By combining longitudinal and cross
feed in a special lathe.

10. A broad nose tool having straight cutting edge
(form tool) is set on to the work at half taper
angle, and is fed straight into the work to
generate a tapered surface. In this method
the tool angle should be properly checked
before use. This method is limited to turn
short length of taper only. Tool will require
excessive cutting pressure, which may distort
the work due to vibration and spoil the work
surface.

11. This Method Is Used In Mass Production
For Producing A Small Length Of Taper.
The Form Tool Should Be Set At Right To
The Axis Of The Work. The Carriage
Should Be Locked While Turning Taper By
This Method.

13.  The principle of turning taper by this method is to shift the
axis of rotation of the workpiece, at an angle to the lathe
axis, and feeding the tool parallel to the lathe axis. The
angle at which the axis of rotation of the workpiece is
shifted is equal to half the angle of the taper. The body of
the tailstock is made to slide on its base towards or away
from the operator by a set over screw. The amount of set
over being limited, this method is suitable for turning
small taper on long jobs. The main disadvantage of this
method is that the live and dead centres are not equally
stressed and the wear is not uniform. Moreover, the lathe
carrier being set at an angle, the angular velocity of the
work is not constant.

14. D= Large Diameter of Taper,
d= Small Diameter of Taper,
L=Length of work,
l= Length of taper,
 α= Half taper angle,
S = Set over

16.  This method employs the principle of turning taper by
rotating the work piece on the lathe axis and feeding
the tool at an angle to the axis of rotation of the work
piece. The tool mounted on the compound rest is
attached to a circular base, graduated in degree, which
may be swivelled and clamped at any desired angle.
Once the compound rest is set at the desired half taper
angle, rotation of the compound slide screw will cause
the tool to be fedat that angle and generate
acorresponding taper. This method is limited to turning
a short taper owing to the limited movement of the
cross slide. But a small taper may also be turned.

17.  The compound rest may be swivelled at 45°on
either side of the lathe axis enabling it to turn a
steep taper. The movement of the tool in this
method is being purely controlled by hand, thus
giving a low production capacity and poor
surface finish. The setting of the
compound rest is done by swivelling the rest at
half taper angle, if this is already known. If the
diameter of the small and large end and Length
of taper are known, the half taper angle can be
calculated from the equation {Tan α = (D-d) / 2L}.

19.  The principle of turning taper by a taper
attachment is to guide the tool in a straight path set
at an angle to the axis of rotation of the work piece.
A taper turning attachment consists essentially of a
bracket or frame which is attached to the rear end
of the lathe bed and supports a guide plate pivoted
at the centre. The plate having graduations in
degrees may be swivelled on either side of the
zero graduation and is set at the desired angle with
the lathe axis. When the taper turning attachment
is used, the cross slide is first made free from the
lead screw by removing the binder screw.

20.  The rear end of the cross slide is then tightened
with the guide block by means of a bolt. When the
longitudinal feed is engaged, the tool mounted on
the cross slide will follow the angular path, as the
guide block will slide on the guide plate set at an
angle to the lathe axis. The required depth of cut is
given by the compound slide which is placed at
right angles to the lathe axis. The guide plate must
be set at half taper angle and the taper on the work
must be converted in degrees. The maximum
angle through which the guide plate may be
swivelled is100 to12°on either side of the centre
line.

21.  If the Large diameter (D), Small diameter
(d), and the taper length (L) are specified,
the angle of swivelling the guide plate can
be determined from equation. Tan ά = (D-d)
/ 2L.

23. (A) The alignment of live and dead centres being
not disturbed, both straight and taper turning may
be performed on a work piece in one setting
without loosing much time.
(B) Once the taper is set, any length of a piece of
work may be taper turned within its limit.
(C) Accurate taper on a large number of work pieces
may be turned.
(D) Internal tapers can be turned with ease.

24. Taper turning by combining feeds is a
more specialized method of turning taper.
In certain lathes both longitudinal and
cross feeds may be engaged
simultaneously causing the tool to follow a
diagonal path. This is the resultant of the
magnitudes of the two feeds. The direction
of the resultant may be changed by
varying the rate of feeds by change gears
provided inside the apron.