Taper Turning Methods
Taper Turning:
A conical surface produced on a lathe is called taper
turning. The tool moves at an angle to the axis of rotation.
Methods of Taper turning:
• Form tool method
• Compound rest method
• Taper attachment method
• Tailstock set over method
Form tool method:
It is one of the simplest methods used to produce short
taper. A broad nose tool having straight cutting edge is set on to the work at
half taper angle and is fed straight into the work. It requires excessive
cutting pressure which may distort the workpiece due to vibration.
Compound rest method:
This method is used to produce short and steep taper. The
compound rest is swivelled to the required angle and clamped in position, it
can be moved up to 45° on both sides.
Taper turning attachment method:
This attachment is attached to the rear end of the bed by
using bottom plate or bracket. This guide bar can swing at any required angle
of taper. The work is held between centres or in a chuck while the guide bar is
turned to a required angle.
Taper Angle Calculation:
D = large diameter, mm
d = small diameter, mm
L = length of taper, mm
tan α = BC / AD = D - d / 2L
D - d / L = K
tan α = K / 2
K = 2 tan α
Tailstock setover method:
This method shifts the axis of rotation of the workpiece at
half angle of taper to the lathe axis and feeding the tool parallel to the
lathe axis.
Tailstock setover [h] is calculated as,
h = [(D - d) / 2l] ×
L = L ×
tan α
Where,
D = Maximum diameter of the workpiece.
d = Minimum diameter of the workpiece.
l = Required length on which taper being made.
L = Full length of the workpiece.
Calculation of Setover:
Where,
D = Maximum diameter of the workpiece.
d = Minimum diameter of the workpiece.
l = Required length on which taper being made.
L = Full length of the workpiece.
From above figure,
In △ ABC, sin α = BC / AB
sin α ≈ tan α (For small angles)
BC = Amount of setover
And, AB = Overall length of work piece
Setover, S = BC = AB tan α
S = L tan α = L × [(D - d) / 2l]
Where
D = Large diameter, mm
d = Small diameter, mm
l = Length of taper,
mm
L = Length of work piece, mm
If the taper is turned through entire length, then I = L and
the amount of setover is given by the equation,
Setover, S = (D - d) / 2
END
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