Patent GB-829360-A (GB)
Title: Band saw
IPC: B23D53/04
Filed: 1957-11-22
Abstract: 829,360. Sawing. ARMSTRONG-BLUM MANUFACTURING CO. Nov. 22, 1957 [Jan. 4, 1957 ; April 17, 1957], No. 36439/57. Class 145. A band saw comprises an upright sawcarrying frame 31 tiltable about a horizontal axis on a carriage 40 reciprocable hydraulically to feed the blade 25 into work held in clamps 150, 151 on a slotted table 21. The saw blade may be a continuous loop or an elongated double-ended blade moving unidirectionally or with a reciprocating movement. The carriage 40 runs beneath the table 21 in channelsection guides 45, 46. Fig. 2, and has pairs of rollers 44 at each end, one roller of each pair being journalled on an eccentric adjustment bolt 50 so that one roller can be set to engage the upper guide surface while the other engages the lower surface and the rollers one one side being grooved to engage bars 48 and prevent lateral movement. The frame 31 is pivoted on the carriage by a support member 61 journalled at the rear end of the carriage and by a support member 66 extending from a lower wheel housing 33 and having an arcuate rib engaging a groove 69 on a rear carriage member. The table slot 22 is bevelled at 60 to accommodate the saw blade 25 in the tilted position of the frame and the frame can be locked in any position by a ring clamp 63 operated by a lever 65. The upper wheel 34, Fig. 5, for the blade 25 is mounted for slight angular tracking adjustment by screws 96 in a slide 82 movable by hydraulic pressure in a cylinder 111 to tension the blade and downward movement of the slide when hydraulic pressure is released is limited by a stop 105. The lower wheel is similarly adjustable to ensure correct tracking of the blade and is driven by a hydraulic motor.  Work clamping.-The jaws 150, 151 of the work clamps are slidable in the upper part of T-slots in the table 21 and co-operate with members 158, 175 which can be located at different positions along the slots by bars 164, 175 engaging hardened notched locking bars 162 on each side of the slots ; the members 158, 176 are rockable against the force of springs 165, 177 to disengage the bars 164, 176. With the members 158, 175 adjusted to the required position, the jaw 151 can be locked at this position by screwing down a screw 160 and the other, jaw can be moved up to engage the work by a hydraulic piston 182 spring-loaded to the retracted position. To avoid crushing of a tubular workpiece, the movement of the piston 182 is limited by an adjustable stop collar 187. Saw guides and cooling.-Above and below the workpiece, guides bearing on the back and sides of the saw blade are provided in mountings angularly adjustable in brackets 284, Fig. 19, which are adjustable longitudinally of the blade. The back stop 277 has a hardened face or a facing 279 of tungsten carbide and is pivoted at 277 so that the whole face engages the back of the blade, even when it is deflected in operation. The side guide bars 290 are made of cemented hard carbide and are secured in inclined grooves by screws. A nozzle 294 supplies coolant and is slotted to afford passage for the blade. Operation.-On momentarily depressing a switch S on a control panel 247, a motor driving a pair of hydraulic pumps and a coolant pump is started and pressure is supplied to the cylinder 111 to tension the saw blade. Operation of a switch 52 then sets a solenoid-operated valve to deliver pressure from the first pump to the saw blade driving motor and operation of another valve by a lever 262 delivers pressure from the second pump to the clamping piston 182. In order to increase the clamping pressure when the saw blade is heavily loaded, the first pump circuit is connected to the second pump circuit through a check valve which opens and increases the pressure supplied to the clamping cylinder as the pressure from the first pump rises owing to the heavy loading. A lever 266 controlling the supply of pressure for feeding the saw blade into the work has four positions, a neutral position, a feed position in which an adjustable metering valve controls the feed speed, a rapid approach position in which the metering valve is by-passed and a return position. An adjustable sequence valve delays supply of pressure to the saw blade feed cylinder until the work clamping and blade tensioning cylinders have completed their operation as evidenced by the rise in pressure in the circuit. A rotatable control rod 200, Fig. 1, mounted of the base of the machine has adjustable front and rear lever stops 210, 211 which are tilted by a cam surface on the carriage -40 to operate a switch and stop the advance and retraction of the carriage. In order to stop the advance as soon as a workpiece has been cut through, the movable clamp jaw 150 can be connected to the front stop 210 through a bar 220 so that the stop is set according to the position of the jaw. A safety switch is operated to stop the machine by the movement of tensioning cylinder 111 on breakage of the saw.