Patent GB-770534-A (GB)
Title: Sawing machine
IPC: B23D45/00
Filed: 1954-03-08
Abstract: 770,534. Sawing. OHLER, F. K. OHLER, K, OHLER, E., sen., and OHLER, E., jun., [trading as OHLER,J. FJ. March 8, 1954 [March 11, 1953], No. 6645/54. Class 145. A sawing machine has a pair of separate vices 2, one on each side of the cutting plane of a circular saw, and final clamping pressure is applied to one jaw 4 of each vice by a separate fluid-pressure cylinder 7 or 8, each cylinder having independent supply lines so that change of pressure in one cylinder does not affect the other. The pistons 9 and 10 in the cylinders are each rotatable on, or connected by levers to, a screwed shaft 6 for each vice jaw 4 and each shaft 6 is slidably coupled to an opposite-handed screwed shaft 5 for each jaw 3. The jaws are centred by means of a handle 17 and the shafts may be interconnected for simultaneous operation by means of gears 14, 16 and a sliding gear 15. A double pump 24 supplies pressure to feed cylinders 31 for the saw carriage and also through control valves to the clamping cylinders 7, 8, the valves being controlled by hand or automatically. In one form of automatic control, each clamping cylinder is controlled by a valve 18 normally maintained by spring, weight or oil pressure in a position to supply fluid to the cylinders to move the vices to clamping position. When the saw carriage begins its return stroke, dogs on the carriage raise the valve 18 connected to the cylinder 8 and thus the pressure is released from cylinder 8 and the cut-off piece is released. When the saw carriage reaches the end of its return run, the second valve 18, connected to the cylinder 7, is reversed by the engagement of a lug 34 on the carriage with a dog 35 and the release of pressure in cylinder 7 releases the remaining portion of the workpiece. In another form of automatic control, the first valve 18 is replaced by a valve 19 connected at its ends to opposite ends of the feed cylinders 31 so that, as soon as the pressure is supplied to feed the saw carriage down, the valve moves to the right to supply pressure to the cylinder 8 to clamp the piece to be cut-off but is reversed as soon as pressure is supplied to raise the saw carriage. With both forms of control, the cut-off piece is released while the main body of the work is still clamped. The pressure of both cylinders can be applied to one vice by means of a connector 13 rigidly connected to one piston, the inoperative vice jaws being opened out to allow the lost motion to be taken up. Different clamping pressures may be applied by each vice by applying different fluid pressures to each cylinder or the cylinders may be of different crosssection. To prevent lowering of the saw carriage if the work is not sufficiently clamped, valves 27 and 28 are fitted between the feeding cylinders 31 and the line 20 to the clamping cylinder 7. Normally the valve 27 allows the full pressure in the line 20 to act on the end of the valve 28 and hold it against spring, weight or fluid pressure in a 'position in which the feeding cylinder line 41 is connected to a return conduit but, if the clamping piston reaches the end of its stroke before the work is fully engaged, a dog formed by an extension of the connector 13 or by other means on the shaft 6 shifts the valve 27 to release the pressure on the valve 28 through a conduit 25; the-valve 28 then moves to block the fluid return conduit for the feeding cylinders and the saw carriage cannot be lowered.