Patent GB-783791-A (GB)
Title: Improvements in and relating to machines for sawing logs and wood in the form of baulks into planks
IPC: B27B31/08
Filed: 1954-12-20
Abstract: 783,791. Sawing. PARKER MITCHELL ENGINEERING CO., Ltd., PARKER, W. M., PARKER, W. J., and BOYLE, J. B. Feb. 27, 1956 [Dec. 20, 1954], No. 36707/54. Class 145. A machine for sawing planks from timber baulks 14 comprises a horizontal band saw 13a, a pivoted stripper 18 for preventing the sawn plank from returning with the log during the return stroke of the work table 10 and a plank carriage 11 which has a vertically adjustable structure 20 for receiving the stripped planks and then lowering or raising them to the correct position for a pusher 24 on side chains 22 to stack them on a platform 12. The table 10, carriage 11 and platform 12 are reciprocated on rollers 13 by means of motor under control of the sawyer and may be a single structure or consist of separate interconnected units. The structure 20 is adjustable by means of a motor 28 and screws 26 and the side chains 22 are driven by a motor 25. To adjust the structure 20 to receive each plank as it is cut, again adjust-it to the height of the stack on platform 12 and return it to the height at which the next plank will be received, a control panel 30a having a vertically-adjustable switch casing is provided. The casing embodies three stripperheight switches 30, 31, 32, a switch actuator 33 and a change-over switch 34 for altering the direction of adjustment of the structure 20 and is connected by a cable 36 to the saw frame to move in unison with it as the frame is adjusted to suit the thickness of plank to be cut. A casing 38 for stack-height switches 39, 40 is connected by a cable 41 to the casing for the stripperheight switches so as to move in unison with the latter but in the opposite direction. The switch actuator 33 is loaded downwards by a weight 45g and is connected by a cable 44 to a pulley 45a around which passes a cable 45b, the cable 45b being anchored at both ends and passing over a pulley 45e on the structure 20. The change-over switch 34 is supported by a cable 47 anchored at one end 48 and adjustably securable at the other end to a scale 50 and the switch is positioned at the mid point of the baulk when the adjustable end is fixed to the scale at the height of the baulk. When the first plank has been cut and transferred to the structure 20, a press button switch is operated to set the motor 28 in operation to lower the structure and consequent movement of the actuator 33 causes a roller 43 to operate the stack-height switches 39, 40 and stop the motor when the structure is in a position where the pusher 24 can transfer the plank to the platform 12. Preparatory to the next plank being cut, another press button switch is operated to cause the motor to raise the structure to approximately its previous height, such movement being arrested by a roller 33b operating to open switches 31 and 32, and the sawyer then lowers the saw frame under manual control by one plank thickness. Movement of the saw frame resets the position of the stack-height and stripper-height switches by means of the cables 36 and 41 and the structure 20 is adjusted to correct position to receive the next plank by operating a press-button switch to energize the motor 28 and move the structure down until a roller 33a on the actuator opens the switch 30. The switches 31, 32 and 39, 40 are connected in parallel and have oppositely inclined faces to co-operate with the rollers in either direction of travel of the actuator. The switches for the pusher 24 and for adjustment of the structure 20 may be operated automatically.