Taper turning methods in lathe machine
A taper turning is the gradual reduction in diameter from one portion of a cylindrical workpiece into another portion as a machining process doing in a lathe machines. Tapers can be external or internal. If a workpiece is confined to the outside, there is an external taper; it has an internal taper if confined to the inside.
There are five methods of Taper turning methods in lathe machine
1. Form tool method
2. Tailstock set over method
3. Compound rest method
4. Taper turning attachment method
5. Combining feeds method
Form tool method
This is one of the simplest taper turning methods in lathe machine to produce short taper. This method is shown in the above figure. To the required angle the form is grounded. The tool is fed perpendicular to the lathe axis, when the workpiece rotates.
The tool cutting edge length must be greater than the taper length. Since the entire cutting edge removes the metal, it will produce a lot of vibration and hence a large force is required. It is done in slow speed.
Tailstock set over method
Generally, when the angle of taper is very small this taper turning methods in lathe machine will be employed. The workpiece be placed in the live center. Now, the tailstock will be moved in a crosswise, that is perpendicular to the lathe axis by turning the set over method. This process is known as tailstock set over method.
Hence here the job is inclined to the required angle. When the workpiece rotates the tool is moved parallel to the lathe axis. So that the taper will be generated on the workpiece.
Compound rest method
Generally short and steep taper will be produced will be produced using this taper turning methods in lathe machine. In this method the workpiece will be held in the chuck and it will be rotated about the lathe axis. The compound rest is swiveled to the required angle and then it will be clamped in position.
Then by using the compound rest hand wheel the tool will be fed. Both the internal and external taper can be done using this method. The important feature is that the compound rest can be swiveled up to 45° on both sides. Only with the help of the hand the tool should be moved.
Taper turning attachment method
In this taper turning methods in lathe machine by using bottom plate or bracket, a taper turning attachment is attached to the rear end of the bed. It has a guide bar which is usually pivoted as its center. The guide bar has the ability to swing and it can be set in any required angle. It has graduations in degrees. On either side, the guide bar can be swivelled to a maximum angle of 10°. It has a guide block which connects to the rear end of the cross slide and it moves on the guide bar. The binder screw is removed, before connecting the cross slide, hence the cross slide is free from the cross slide screw.
Usually during taper turning, the job will be held in the chucks or in the centers. To the required angle the guide bar turned.
The angle is calculated using the formula, tanα = (D-d)/2l
When the division is given in mm instead of degree, then the angular distance of the guide bar to be tilted is given by
Using the compound rest hand wheel the depth of cut will be given. At an half taper angle the guide will be set. Using this taper turning methods in lathe machine any taper turning method can be done.
Combining feeds Method
Another more advanced taper turning methodology is taper turning by combining feeds. Both longitudinal and cross feeds may be engaged concurrently in some lathes, allowing the tool to travel a diagonal course that is the product of the magnitude of the two feeds. The trajectory of the resultant can be adjusted by changing the feed rate by changing the gears given within the apron.