Design Of Circular Form Tool Graphical Method

DESIGN OF CIRCULAR FORM TOOL Problem: Determining the outside diameter of a positive –rake circular form tool graphically

Draw two concentric circles corresponding to maximum & minimum radius of contour to be turned

Through point A ( on minimum diameter circle ) draw one line inclined at an angle γ , (which represents trace of plane ground to produce the tool face) below the line. “OA” Through same point draw another line above ‘OA’ inclined at an angle ∝ (relief angle). The value of ∝ is 100 to 120 for circular form tool.

At a distance K ( = 3 to 12 mm) depending upon chip thickness & amount of chips to be cut, draw a line perpendicular to OA to permit minimum amount of space for chip disposal.

From the point of intersection ‘C’ ( of vertical line with the tool face line) draw a line bisecting angle (OMEGA) .

From O2 draw circle represent ing outer diameter of tool with radius O2 A = R

To determine diameter of the mounting hole, the wall thickness ‘m’ is taken in the range form 6 to 10 mm.

Graphical Vs Analytical Method • The graphical method is simple and straight forward but has certain inaccuracies inherent in all graphical constructions. The analytical method, on the contrary, enable the dimensions to be determined with any degree of accuracy. A drawback of analytical method is that the complicated calculations required.