Patent GB-260905-A (GB)
Title: Improvements in and relating to metal-broaching machines
IPC: B23D37/06
Filed: 1926-06-18
Abstract: 260,905. Perkins, J. L., and Croft, H. D. June 18, 1926. Broaching.-A broaching- machine comprises two rams reciprocated vertically in opposite directions by a pinion situated between them and engaging a rack on each, the rams each carrying two rows of opposed cutters which act on opposite sides of the work. One set of cutters in each ram may be omitted, however, if it is desired to operate on one side of the work only. A work-holder is provided for each ram and is oscillated automatically to and from operative position simultaneously with the reversal of rotation of an electric motor which drives the pinion, the working position of the holders being determined by projections thereon engaging central grooves in the rams. Cutters are described for producing two opposite plane surfaces on hinge blanks, but cutters for producing grooves may also be used. Each ram 24 has the section shown in Fig. 5 and is guided on a vertical T-shaped upright 23, Figs. 3 and 4. A balancing rope 30 is attached at each end to a bracket 32 on the rams and passes over pulleys 29 on fixed brackets 27. The pinion 19 is rotated by reduction gearing from the electric motor 12 and engages the racks 26 secured to the rams. The cutters consist of separate parts 50, eight on each ram, which are set at a slight angle to the line of travel by pairs of wedges 56, 57, adjusted by screws 59, and are locked by bolts 53 engaging slots in the cutters. Abutments 55 take the end thrust of the cutters. The work-holders, which as shown in Fig. 13 are for gripping hinge blanks 62, comprise brackets 64 adjustably secured to two separate shafts 63, one being arranged in front of each ram. The brackets have rectangular recesses 65 in which U-shaped holders 47 are secured by screws 66, the holders having blocks 68 attached thereto by keys 72. A screw 69 in each block engages a gripping-jaw 67 and is operated by means of a hand-wheel 70 having a small amount of rotational play on a square shank 74 of the screw so as to impart a hammer blow to the screw for securing or releasing the work 62. The weight of the holder is so distributed about the shaft 63 that the end of the holder 47 is maintained in contact with a grooved plate 45, Fig. 5, on the corresponding ram during the cutting stroke. The shafts 63 are oscillated alternatively to bring the work into and out of working position by mechanism actuated bv cam surfaces on the rams. The cam surfaces consist of inclined ribs 36, Fig. 4. arranged at the top and bottom of the outer sides of each ram, the upper and lower cams being oppositely inclined. In operation, when a ram reaches the lower limit of its stroke the cam 36 engages a roller on a lever 112, Fig. 4, which is loose on a shaft 111 and carries two pockets 120 enclosing compression springs which impinge on the lugs of a lever 116 so as to communicate the oscillation to this level without shock. The lever 112 on one side of the machine has an arm 117 adjustably secured thereto, which arm carries a segmental gear engaging a pinion on a reversing device 20 for the motor 12. The lever 116 carries a pin 123 on which rests a link 89 pivoted at 88 to a lever 85 adjustably connected to the shaft 63, the link having a hooked end 90 so that when the pin is moved to the left in Fig. 4 the shaft 63 will be oscillated to carry the work-holder 47 out of operative position. The finished workpiece 62 may then he removed and replaced by a new blank. The pivot 88 has also loosely pivoted thereon an arm 91 carrying a roller 93 which normally rides along a hand-lever 104 pivoted at 107. The hand-lever is maintained in the raised position shown by a trip-lever 100 and a pin 103. When the ram reaches the top of its stroke the bottom cam throws the lever 112 to the left and the pin 123 engages the end of the arm 91 so as to oscillate the shaft 63 and return the workholder to its operative position, but in the movement of the lever 85 to the right a pivoted dog 96 thereon trips the lever 100 and allows the hand-lever 104 to fall. The arm 91 falls with the hand-lever 104 and thus the work-holder cannot again be brought into working position automatically until the hand-lever has been raised. The operator of the machine raises each hand-lever 104 in turn when he inserts a new blank in the corresponding work-holder. Each work-holder rests against a fixed stop 84 in its inoperative position and a stop 129 is provided on the machine frame to engage a lug 128 on the arm 91 when the latter is in its lower position so that the work-holder cannot be moved into its operative position unless the hand-lever 104 has been raised. Cuttings, catching and removing; beds and framings. - The base 1 on which the machine frame 2 stands is provided with compartments 38, Fig. 2, directly under the rams 24, into which the cuttings and oil fall. If an excessive quantity of cuttings collects in a compartment 38 the ram compresses them against a plate 41 supported on a rib 43, thus breaking the plate and warning the operator by the sound of breaking. Each compartment 38 leads into a box 39 and a row of projections 40 is provided to allow the cuttings to be raked into the boxes whilst the oil runs back into the compartments. The cuttings are finally removed through doors 6, Figs. 3 and 4. and doors 7, 8, 9 are also provided in the frame 2.