Patent GB-280586-A (GB)
Title: Improvements in or relating to methods of and machines for broaching
IPC: B23D43/06
Filed: 1927-11-12
Abstract: 280,586. Cincinnati Mining Machine Co., (Assignees of Blood, L. H.). Nov. 13, 1926, [Convention date]. Rivets.-In a continuously acting broaching - machine, particularly designed for cutting diametrically opposed flats on rivets but applicable also to other articles, an arcuate cutter has peripheral teeth arranged eccentrically so as to have a progressive cutting action on a number of work-pieces which are moved relatively to the cutter. The work-pieces are placed by hand in holders and are automatically clamped and released at each end of the cutting traverse, the holders being mounted on a circular table surrounding the cutter and the cutter or table being rotated continuously. When rotation is imparted to the work-table, the table 28 has a central cylindrical portion 29, Fig. 2, rotatably mounted on a pillar 27 and is driven by a wormwheel 36. The work-holders 43, Figs. 1 and 2, are mounted on slides 41 radially adjustable on the table by screws 42, and each comprises a lower V-block and an upper movable jaw rotatably attached to a vertical screwed spindle 48 carrying arms 49, 50, provided at their extremities with rollers 51. A fixed projection 53, Fig. 1, lies in the path of the arms 50 and serves to rotate the screws 48 in turn during rotation of the table and open the holder, whereupon a stationary spring 55 engages the finished work-piece and ejects it into a discharge shoot 56. When new blanks have been inserted in the open holders by hand the arms 49 come into contact with a stationary stop 59 to close the holders, the stop 59 being yieldingly supported in position by a spring 60 to allow the blanks to be gripped with an equal pressure irrespective of slight variations in size. The cutter comprises two discs 68, Fig. 2, spaced apart by distance pieces 65 and secured to a table 57 by T-slots therein and bolts 62. The teeth 63 may be of the individually inserted type or may be formed on blocks which are seated on flat chordal surfaces of the plates arranged eccentrically so that the blocks may be interchangeable, the assembled blocks being ground to produce a smooth arc. The cutter is adjusted vertically by a screwed sleeve 72 rotatable in a bush 73 secured to the machine bed and having a ballbearing 77 supporting a central boss 71 on the cutter-table 57, locking being provided for by a central spindle 78 engaging a nut 79 fixed on the bed. The cutter-table is guided by a depending sleeve 69 keyed at 70 to the fixed pillar 27. If the work-holders are stationary and the cutter rotates, the worm-wheel 36 is attached to the cutter-table 57 and the latter carries arms which actuate the levers 49, 50 to open and close the holders in turn. Cooling fluid is supplied to the cutter 63 by a pipe 12, the fluid being circulated from a reservoir 11, Fig. 2, in the machine frame by a pump. Cuttings and cooling fluid pass through apertures 38 in the work-table 28 on to gratings 21 covering apertures 20 in the flange 19 of the machine frame, the fluid falling into the reservoir 11 and the cuttings being swept by pushers 39, attached to the rotary table 28, through a common aperture 40 into a compartment 13 from which they may easily be removed, any fluid remaining passing through a grating 17 into the reservoir. A trough 26 in the machine frame receives cuttings &c. which fall from the periphery of the work-table. Surrounding the sleeve 29, Fig. 2, of the rotary work-table 57 is a, rim 32 forming an annular chamber 31 from which lubricant can flow through apertures 34 in the sleeve to oil grooves 35 between the interior of the sleeve and its stationary supporting pillar 27. The worm-wheel 36 which rotates the work or cutter-table is driven by two worms 37, Fig. 2, diametrically opposite each other. The worms are driven respectively by a shaft 96, Fig. 8, and a sleeve 92, each carrying a flange 90 having an aperture 89 to receive a ball end 88 on a link 87 which is pivotally mounted in a recess 86 in a central flange 85, the latter being secured to a shaft 84 passing through the sleeve 92 and driven by change speed gearing from a belt pulley. Oscillation of the link 87 in the flange 85 ensures that the drive will be balanced and evenly distributed between the two worms.