GB571192A - Improved means for bending tubes - Google Patents

Abstract

571,192. Bending tubes. DRAPER, F. C. Dec. 7, 1943, No. 20420. [Class 83 (iv)] In a machine for bending tubes of the kind having a shaped bending block over which the tube is bent by a member shaped to conform to a development of the half circumference of the finished work on the outside of the bend and mounted tangentially to the block. and adapted to roll thereover and provided with gear teeth meshing with gear teeth on the bending block, the pitch circle of the gear teeth is substantially coincident with the inner circumference of the bend. The tubes may be previously corrugated as described in Specification 571,191, or the internal surface may be subjected during bending to high fluid pressure from a reservoir as described in Specification 567,753. The tube may be secured by a clamp 3 to a former 1 with a semicircular groove round which it is bent by a semicircularly grooved member 4 which is rolled round the former by rollers 9 on a carriage 12 radially adjustable on a lever 8 which is detachably hooked to a pivot 11 at the centre of curvature of the former. The member 4 is provided with cheeks 6 which overlap the sides 7 of the former, so that at the point of bend the work is completely embraced by the member and former. The cheeks 6 are formed with gear teeth 16 co-operating with gear teeth 17 on quadrants fixed to the former, the pitch circle of which is coincident with the inner circumference of the bend so that as the member 4 rolls round the former it has a sliding movement relatively to the work in the direction of progress of the bend so as to smooth the outer surface of the tube. With tubes corrugated as described in Specification. 571,191, in which the neutral' axis is substantially coincident with the inner circumference of the bend, the sliding movement of the member is effective to iron out the corrugations on the outer side of the bend. A tubular handle 14 may be applied to the spigot 15 on the lever 8.