Patent GB-1352172-A (GB)
Title: Horizontal band saws
IPC: B23Q15/12
Filed: 1971-05-28
Abstract: 1352172 Band saws AMADA CO Ltd 28 May 1971 [17 June 1970 26 Aug 1970 (3) 22 Sept 1970 21 Nov 1970 3 Dec 1970 30 Dec 1970] 18165/71 Heading B5L [Also in Division F2] A horizontal band saw machine comprises a housing 46, Fig. 1, for a band saw blade 54, and means for controlling the rate at which the saw blade moves in a cutting direction through the material to be cut depending upon the shape and/or hardness of the material. The rate controlling means comprises hydraulic pressure means for raising and lowering the housing, piston escape valve means 62, and means adapted to deliver fluid from the hydraulic pressure means to the escape valve means. The delivery means includes a distributer 104, Fig. 4, rotatable with a shaft 56 connected with a driving wheel 50, Fig. 1, for the saw blade, for delivering fluid to the escape valve means, so that, in use, the piston 168, Fig. 4, of the valve means is reciprocated at a rate proportional to the travelling speed of the band saw blade, whereby fluid escapes from the hydraulic pressure means at a rate proportional to the travelling speed. In the machine described the housing 46 is pivotally mounted on a base 42, and carries the drive wheel 50 and a driven wheel 52 about which the saw blade 54 passes. The housing is raised or lowered by an hydraulic cylinder 48, escape of oil from which during lowering is controlled by the said escape valve means 62. The escape valve means comprises an inlet 138, Fig. 4, for oil from cylinder 48, an outlet 132, the distributer 104 rotated by the shaft 56 connected with the drive for the wheel 50, a plunger 168, an adjustable stop 174, a spring urged slider 190, and various fluid passages. In one rotary position of the distributer oil under pressure is delivered to the left hand side of the plunger 168 until the oil pressure is balanced by pressure of a spring 192 against which the plunger is urged. On rotation of the distributer to the position shown in Fig. 4 the plunger is moved leftwards to expel oil. The stop 174 controls the initial lowering speed of the housing and its position is adjusted dependent on the workpiece by means of a cam rotated by moving a pointer over a scale. The workpiece feed is effected by damping the workpiece in a vice 84, Fig. 2, which is slid along rails 80 by a cylinder device 82. A device 88 carried by the vice detects absence or slippage of the workpiece to stop the machine. A roller 90 is raised while the workpiece is advanced, and lowered when the workpiece reaches a desired position, whereupon a vice 464, 470 operates to hold the workpiece. Cut portions of the workpiece are also supported by fences 548, 550. Tensioning of the saw blade prior to and during cutting is made possible by mounting the shaft of the follower wheel 52, Fig. 1, on a slidable plate which is adjustable by a screwed shaft. A spring acts through bell-crank levers against a flange on the shaft to tension the blade. Guiding of the saw blade is effected by a pair of rollers 306, 308, Fig. 15, each of which is arranged to engage one half of one face of the saw blade 54, and a pair of rollers 352, 354 which engage the back of the blade and are carried on a pivoted member 358.  Lubrication of the saw blade, and hence the workpiece is effected by feeding oil under pressure via conduits 338, 340a, 340b 334 and 348, Fig. 17, to blocks 326, 328 having recesses 342a, 342b, on opposite sides of the saw blade 54. The blocks 326, 328 are spring urged against the blade. Slippage of the saw blade relative to the follower wheel 52, Fig. 1, is detected by means of a fixed no-contact switch which is arranged to be operated by rotating blades carried with the wheel 52. The switch normally produces evenly distributed pulses, but if slippage or breakage of the saw blade occurs the change in pulse rate is detected by an electrical circuit to stop the machine. Cleaning of dust from the saw blade during cutting is effected by three wire wheels, e.g. 394, 386, Fig. 23. The wheel 394 is rotated by a shaft 392 which extends parallel to the direction of travel of the saw blade. Two more wheels 384 act tangentially on the saw blade and are rotated thereby. The shafts of the wheels 384 are mounted on levers which are pivoted at 376a the levers being oscillated by a cam on the shaft 392 to reciprocate the wheels 384 axially.