Patent GB-955790-A (GB)
Title: Improvements in or relating to log-cutting mills
IPC: B27B1/00
Filed: 1962-12-19
Abstract: 955,790. Sawing; woodworking. E. E. RUNNION. Dec. 19, 1962, No. 47883/62. Heading B5L. [Also in Division B8] A log-cutting machine comprises cutter heads for profiling a log into pyramidal steps ascending above and descending below a transverse horizontal centre line, saws for cutting the log on the vertical planes of the respective riser faces for producing dimensional lumber, and means for conveying the log past the cutter heads and saws. The log 2, Fig. 1, is advanced by an infeed conveyer having lower and upper runs 34, 54 to upper and lower chippers 80, 81 which shape the pyramidal steps on the upper and lower surfaces of the log before the log is advanced by a mid-feed conveyer 112, 113, Fig. 3, between chipping cutters 150, Fig. 10, which surface the sides of the log. From the cutters 150, the log passes circular saws 170 which are aligned with the vertical faces of the steps to cut the log into lumber, an outfeed conveyer 176, 177 feeding the lumber to an output conveyer 191. The infeed conveyer consists of a table 29 Fig. 1, over which the upper run of a chain 34 rides, the chain being driven by a motor 37. The upper run of chain 34 co-operates with reentrant shaped dogs 56 on the lower run of an upper chain 54 which is driven by a motor 67 around sprockets 55 and drums 68 mounted on pivoted levers 61. A roller 62 carried by a pivoted arm 63 bears on the lower run of the chain 54 and actuates a selector switch 65 which controls the position of the upper cutter 81 and side cutters 150 and the actuation of a motor 40 connected by a linkage to the table 29 in response to the diameter of the log. The roller 62 and switch 65 actuate the motor in such a way that if the diameter of the log is an odd number of inches, the table is set at a lower level and if it is an even number of inches, the table is set at a higher level, the difference in levels being an inch. The log is fed by the conveyer 34, 54 between the chipping cutters 80, 81, the lower cutter 80, Fig. 8, consisting of a number of discs 82 having offset bits 84, Fig. 19, mounted on a shaft 85 driven by a motor. The upper cutter 81 is similar in construction to the cutter 80 and is mounted on a slide 93 movable to a vertical position dependent upon the diameter of the log by a pneumatic cylinder 99, an hydraulic cylinder 102 providing a lock to retain the cutter in its adjusted position; the flow of air and oil to the cylinders 99, 102 is controlled by solenoid-operated valves under the control of the selector switch 65. Immediately after passing the cutters 80, 81, the log is engaged by guide shoes having stepped surfaces conforming to the flats on the log, and the chips from the cutters are collected by funnels 108. The guide shoes direct the stepped-log between upper and lower chains 112, 113, Fig. 3, of the mid-feed conveyer, the upper chain being supported on a carriage 121 which is lifted by the log, the lifting of the carriage actuating a switch controlling a cylinder 136 which acts to urge the upper chain into engagement with the log as it is fed between the side cutters 150, Fig. 10, which trim the sides of the log. Each side cutter comprises a head having staggered bits 151, Fig. 21, and is carried by a pivoted frame 149 movable towards and away from the vertical centre of the log by pneumatic cylinders 156, hydraulic cylinders 158 acting to lock the frames in their adjusted position; the cylinders 156, 158 are controlled, as with the cylinders 99, 102, by solenoid-operated valves actuated by the switch 65. From the mid-feed conveyer, the stepped and side-trimmed log passes along guides 175, Fig. 1, to be cut into lumber by saws 120 mounted on shafts 171, 172, each shaft being driven by a motor. The lumber is then engaged by the outfeed conveyer which has upper and lower members 176, 177 which have stepped configurations and comprise a plurality of discs. The centre disc of the lower member is knurled to grip the lumber, the remaining discs being smooth to permit slippage resulting from the differing rim speeds. As a log passes through the machine, it depresses a limit switch 109, Fig. 3, positioned beyond the cutters 80, 81 so that if a photo-cell positioned before the cutters detects a following log, the infeed conveyer is stopped until the limit switch is released.