Patent GB-451169-A (GB)
Title: Improvements in sawing machines
IPC: B23D53/00
Filed: 1936-01-18
Abstract: 451,169. Sawing - machines. GROB, B., and GROB, T., (trading as GROB BROS.), South 97th Avenue, West Allis, Wisconsin, U.S.A. Jan. 18, 1936, Nos. 1702 and 1703. Convention dates, Jan. 19, 1935 and May 4, 1935. [Class 145 (ii)] A sawing-machine has a relatively short portion of an open-ended flexible band saw restrained by suitable guides to a predetermined path adjacent a work support, the movement of said saw through said path being caused by driving means which wind the major portion of the saw in a number of adjacent helical coils, and which is associated with reversing means operable to effect a reverse direction of saw movement. One end of the saw 3, Fig. 1, is attached to the spool 6, and a number of turns laid on the spool ; the saw is then passed around the pulleys 4, 5 and through the slot in the table 2, and also threaded through a hole in the work when operations such as cutting out internal portions of metal die blocks, punches, stripper plates, &c. are to be performed ; the free end of the saw 3 is then attached to the spool 6. When the spool 6 is driven, the saw 3 is wound on the spool 6 at one end and unwinds at the other end, the portion between the pulleys 4, 5 acting on the work as in an endless band saw machine. When all the blade 3 has been operative, the rotation of the spool 6 is reversed by a hand control to return the saw blade 3 to its initial arrangement. The spool 6 is slightly tapered to enable the blade 3 to lie flat despite the set of the teeth ; the spool is moved axially during its rotation, having an internally threaded portion running on a fixed screw for this purpose. The pulley 4 is spring mounted so as to tension the blade 3, which is guided by an adjustable back and side guide 29 and by the edge of the insert in the table 2. In a modification, Figs. 5 and 6, the spool 6 is alternately driven in opposite directions by forward and reverse motors 42, 43 respectively which drive by belts a pulley 51 having rods 53 extending through the spool 6. The motors 42, 43 are controlled by a push-button board 96, a controller 97 being provided for the motor 42. The spool 6 is fixed to a screw 54 which rotates in a nut 55 fixed in the machine, so as to effect the lateral movement of the spool 6. As the spool 6 reaches the end of its travel to the right, as seen in Fig. 6, a member 102 carried by the screw 54 operates a switch 99 which cuts out the reverse motor 43 so that the machine stops ; as the drum is rotating rapidly during its reverse movement, braking surfaces 59 are provided which engage projections 57 on the spool to bring it to rest. Similarly when the spool 6 reaches its extreme left-hand position a switch 106 is operated to cut out the forward motor 42. The saw blade 3 passes over pulleys 4, 5 and 65 which are slightly tapered so that the blade can lie flat despite the set of the teeth ; the pulleys are also flanged to take the thrust of the blade. The blade 3 is guided by contact members 74, 75 adjustably mounted below and above the table 2 and by a contact member 73 near the spool 6. The pulley 65 is urged to the left, Fig. 5, to tension the blade by a spring 67 ; if the saw breaks, the pulley flies to the left, operating a switch 110 which interrupts the current to the motors 42, 43 so that the machine stops ; the pulley 65 is received by a cushion 89. Unwinding of the coils is prevented by a spring-pressed roller 86 which presses against the coils on either side of the portion leaving the spool. To relieve the tension on the blade, as when threading its free end through the work, the pulley 65 is moved to the right by a rod 79 carried by an arm 83 rocked by a hand lever. In this position of the pulley 65 the switch 110 is again operated to interrupt the current to the motors 42, 43 so that the machine cannot be started. The saw may be placed in the machine wound on a spool 115 mounted on a stud 114 ; the saw blade is wound off this spool, whose motion is retarded by a brake 116, on to the spool 6 when the latter is driven in the appropriate direction. To facilitate handling the ends of the saw blade are not toothed.