Patent GB-138703-A (GB)
Title: Improvements in broaching implements
IPC: B23D43/02
Filed: 1919-02-12
Abstract: 138,703. Oakley, J. Feb. 12, 1919. Broaching; tools.-A broaching-implement for cutting grooves in the exterior of objects comprises a holder provided with internal guide-surfaces arranged laterally with respect to or opposite the cutting-elements, which are in the form of teeth provided with cutting-edges detachably mounted in the holder, and having chip-clearance passages extending outwardly from each cutting- edge. In one form, the broach consists of a round bar 12, Fig. 2, which has a series of slots to receive cutters 16 and provide chip-clearance passages 15, the cutters being secured by pins 17. The frame 1 is provided with a rectangular end 2 and a circular end 3, having openings 7, 8 through which the work is passed. The opening 8 is connected by a slot with an opening 9 to admit of the cutter-bar being withdrawn through the rear end 3 for attaching and detaching purposes. The cutter-bar has a screwed head 13 for securing it to a bar 4 which is clamped to the end 2 by bolts 5; it is held in the piece 3 by a bolt 6. The openings 7, 8 may be of different diameters, and bushings provided. In a modification, in which four cutter-bars are used, the frame consists of a rectangular slotted centre portion 18, Fig. 4, and rectangular ends 19. The cutter-bars 22 are rectangular and are secured so that the cutters project through the slots 23, by bolts 21 passing through the ends 19. In a further modification, two cutter-bars 27, Fig. 8, with integral teeth 28, Fig. 7, are used, with slots 29 between the teeth for the escape of chips. The cutter-bars are clamped between segmental bars 24 by bolts and nuts 30, 31. The bars 24 have a flange 25 at one side and a pair of lugs 26 at the other side, between which they are cut out lengthways to form chip-clearance slots 32. In a modification, the slots 29 in the cutter-bar are replaced by oblique-sided passages which open only into the slots 32 instead of through the outer edges of the bars also, as in the previous case. In a further modification of the double-cutter type, separate cutter teeth 16<a>, Fig. 12, are mounted directly in oblique grooves in the slot 58 formed between the flanges 56 of the segmental bars 54, and are clamped by bolts 57. The chip-clearance passages are provided, in this case, by the open portions of the slots 58. In another form, six sets of cutters may be used, and the holder is hinged so that it can be opened and closed. The two parts of the frame, which each consist of two end pieces connected by separators 35, 36, Fig. 17, are pivoted at 38 and held in their closed position by a pair of cam-levers 43 each carried by a pair of links 40 pivoted at 41 to a lug 39 of the lower frame and engaging the upper surface of a lug 39 of the upper frame. The cutting-teeth 16 are mounted, as in the form shown in Fig. 2, in cutter-bars 47, which have flat end's so that they may be secured by bolts 49 to the ends of the frames, and tapered centre portions 48 so that they may fit into the slots between the separator bars. The cutter teeth are secured by pairs of bolts 52. The work-receiving opening may be made of any shape.