Patent GB-792521-A (GB)
Title: Sawing or like cutting apparatus
IPC: B23D45/18
Filed: 1956-02-21
Abstract: 792,521. Sawing. BIBBY, R. D. Feb. 21, 1956 [March 2, 1955], No. 5410/56. Class 145. Apparatus for severing sections from a moving body, such as comminuted wood board 21 issuing from an extrusion machine 20 as described in Specification 784,179 [Group V], comprises a carriage 26 movable on longitudinal guides 25, means for coupling the carriage to the moving board and a saw head 34 pivotally mounted on a carriage 33 movable transversely on guides 32 on the carriage 26 by means of a motor 60 which drives a chain 59 having a pin 66 coupled to an arm 36 on the sawing head ; the operative cutting traverse is made as the pin 66 moves along the lower run of the chain and the return stroke is made as it moves along the upper run, so that the saw 45 is swung to an elevated position. As the board is extruded, its outer end passes under the carriage 26 and then outwardly on to pivoted support rails 74. When the end of the board encounters a switch S1 mounted on an adjustable switch plate 85, a valve V1 is closed and a cylinder 73 is vented to atmosphere. The carriage 26, which is connected to the piston rod 72 of the cylinder, is then freed for movement with the board. The switch S1 also closes a power circuit to the'motor 44 for the saw blade 45 and an auxiliary circuit through a valve V2 and a limit switch S5. The valve V2 opens and admits pressure air to cylinders 28 causing the board to be clamped to the carriage by clamps 27. A brief interval after the actuation of switch S1, the end of the board actuates a switch S2 on the plate 85 and starts the traverse motor 60 ; the brief time interval permits the motor 44 to bring the saw 45 up to cutting speed. Switch S2 also completes an auxiliary circuit through the solenoid 89 of a switch 90 to complete a holding circuit for the motor 60. The motor 60 through the chain 59 drives the saw head 34 and saw transversely across the carriage with a roller on the pin 66 riding on a lower support track in order to maintain the assembly level. When the saw has completed its traverse across the board, the chain 59 carries the pin 66 up and around a sprocket 49, thus elevating the saw mount arm 36 and 'pivoting the saw head about its pivot 35. The roller on the pin momentarily closes a switch S3 mounted near the sprocket, thus completing a circuit through a valve V3 and the switch S5 and admitting pressure air to a cylinder 82 of which the piston rod is linked to the pivoted rails 74. The rails are thus pivoted downwardly and outwardly, to release the severed section and permit it to drop down and form a stack with other sections on a trolley underneath the rails. Closing of switch S3 also completes a circuit through the solenoid 91 of a gang switch comprising switches 92, 93 and 94. Closing of switch 92 completes a circuit through valve V1 and pressure air is admitted to the cylinder 73 which then returns the carriage 26 to its initial starting position. Simultaneously the opening of switch 93 breaks the circuit to the saw motor 44 and also breaks the auxiliary circuit through valve V2. The energization of valve V2 closes the valve and vents the clamp cylinders 28 to atmosphere thus disengaging the carriage from the board. Closing of switch 94 completes a holding circuit through solenoid 91 and maintains the gang switch in actuated condition through a switch S4, after the momentary closing of switch S3. The traverse motor 60 remains energized through switch S4 and the saw head 34 and saw are moved back across the path of the board with the saw maintained in an upward angular position clear of the board, the roller on the pin 66 being supported on an upper support rail to prevent the chain 59 from sagging downwardly. Near the end of the return stroke, as the pin 66 travels downwardly about a sprocket 50, the saw head momentarily engages and actuates the switch S4 which permits the switch 90 to open and break the holding circuit for the traverse motor 60. Opening of switch S4 also breaks the holding circuit through valve V3, closing that valve and venting the cylinder 82 to atmosphere and thus returning the rails 74 to supporting position. The holding circuit for the switches 92, 93, 94 is also broken and they are returned to their normal position. If there is incomplete severance of a section from the board in the time interval required for the carriage to travel with it for a predetermined distance the carriage 26 engages and opens the adjustably mounted switch S which immediately de-activates the valves V2 and V3 so that the cylinders 28 disengage the carriage from the board and cylinder 82 pivots the support rail 74 downwards to move support from the board. The switch S5 may be connected in the power circuit of the extrusion machine so that extrusion of the board is stopped. In a modification, applicable where the board is extruded step-by-step and could actuate the switch S1 at different stages of a forward stroke, the switches S1 and S2 are adjustably mounted above the carriage 26 and the carriage is connected to a draw bar 101 adjustably carrying a bracket 104. When the end of the board engages the bracket 104, the carriage is drawn along, thus actuating the switch S1 and energizing the saw motor and the clamp cylinders 28. Shortly after the cycle is initiated, the carriage actuates the switch S2 and the cycle proceeds as described above.