GB840274A - An automatic control system for band saw blades - Google Patents

Abstract

840,274. Automatic control systems for band saw blades. ARMSTRONG-BLUM MANUFACTURING CO. Nov. 19, 1957 [Nov. 21, 1956], No. 35983/57. Class 38 (4). [Also in Group XXIII] In a control system for a band saw blade, means for detecting lateral departure of the blade from a desired line of cut actuate means including a servo, for correctively twisting the blade in the workpiece to direct the blade back toward said line of cut. The blade 24 running over wheels 25, 26 is supported by the carriage 23 movable on slides along the machine bed 21. The blade is twisted through 90 degrees by guides 27, 28 to present its cutting edge to a workpiece 35 held by clamps 30 to the machine table 29. A U-shaped feeler device 37, which straddles the blade just behind the teeth, detects lateral movement and through levers actuates one or the other of two switches controlling reversible motor 120. This drives through gearing 108 a pinion 107, meshing with which are racks on the ends of levers 90, 100. The resultant small angular rotation is transmitted by levers to the blade guides to correctively twist the blade. One half revolution of pinion 107 is sufficient for an associated cam to actuate one or the other of two further switches to open-circuit the motor. The initial twist of the blade will cause it to overshoot and the motor will be energized in the reverse direction, but due to the geometry of the lever system and a mechanical follow-up link the detector-operated switch will be open-circuited before pinion 107 has moved arms 90, 100 to their opposite limits. Thus successive corrective twist angles are smaller and the blade rapidly regains its line of cut. The invention may be applied to non-continuous saw blades of the reciprocating type and is applicable to saws for cutting any material.