GB1536938A - Driven rotatable turret drive particularly for automatic nc(numeric control)lathes - Google Patents

Abstract

1536938 Indexing turrets F BANDERA 7 April 1976 [17 April 1975] 14102/76 Heading B3B A lathe turret TO is rotatively indexed by a drive arrangement which comprises a first differential piston-cylinder device cm, CM for rotating the turret, a second differential pistoncylinder device PP GI for raising the turret to disengage a locating toothed coupling IF and engage a drive toothed coupling IN, and an hydraulic system including a three position solenoid valve EV which in a first position ensures that the turret is held down to engage the locating coupling IF to lock it in a programmed position, in a second position (Fig. 2) raises and rotates the turret to a new programmed position, and in the third position allows the first and second piston-cylinder devices to act simultaneously on the turret which has the effect of rotating the turret, after an over-run, backwards to the programmed position. To ensure that the locating coupling IF is disengaged before rotative drive is applied to the turret, a port LU supplying the chamber cm is uncovered only when the turret is raised. When the valve is in the third position pressure is applied to both lines A and B and the large chamber CM ensures the backward rotation of the turret, and the large pressure area in the chamber Gl ensures that the turret is forced downwards to engage the coupling IF. The turret is driven backward to engage a face on a spring biased pawl SA which engages teeth in the turret. A four position tool turret is described having four tool UT. A numerical control programme activates a contact CO at a selected position which is engaged by a feeler when the turret reaches the programmed position.