Head stock spindle drive system may include stepped or cone pulley drive or all geared head drive. In stepped pulley, the number of speed equals to number of steps in pulley. In all geared head drive, total nine various speed can be obtained.
Stepped Pulley (Cone Pulley) Drive: V-belt is used to transmit the power from driver shaft to spindle shaft. In four-stepped pulley drive, four different speeds of the head stock can be attained. Spindle speeds are varied in arithmetic progression (Figure 19.8).
Figure 19.8 Stepped Cone Pulley Drive
Let driver shaft rotates at the speed of N rotation per minute (rpm) and the stepped diameters of the pulley are D1, D2, D3, and D4. Driven shaft has pulley of same steps diameters but in reverse order as shown in Figure 19.8. We know the speed is inversely proportional to the diameter, therefore,
where N is speed of driver shaft and N1, N2, N3, N4 are speeds of spindle shaft. Here D1 < D2 < D3 < D4.
All Geared Head Drive: This drive comprises of nine gears on three shafts. By operating two levers attached with two cluster gears on pulley shaft and head stock main spindle, respectively, nine speeds can be obtained. Three gears 2–4–6 are fixed on intermediate shaft. Spur gear, 10 is fixed on head stock spindle to transmit power to the feed shaft and lead screw. The constructional detail of all geared head drive is shown in Figure 19.9.
Figure 19.9 A Constructional Detail of All Geared Head Drive
The gear combinations for nine different speeds are given below:
where T1, T2, T3, T4, T5, T6, T7, T8 and T9 are number of teeth on gear 1, 2, 3, 4, 5, 6, 7, 8 and 9, respectively.
Leave a Reply