Patent GB-365252-A (GB)
Title: Improvements in or relating to work holders for broaching machines
IPC: B23D37/06
Filed: 1930-11-24
Abstract: 365,252. Broaching. WHITE, A. E., 5, Quality Court, Chancery Lane, London.- (Perkins Machine & Gear Co.; Circuit. Avenue, West Spring- field, Massachusetts, U.S.A.) Nov. 24, 1930, No. 35342. [Class 83 (iii).] A work-holder for a broaching-machine, particularly for broaching hinge leaves of the type shown in Fig. 5, is mounted on an oscillating arm which is moved to swing the work piece into and out of the path of the broaches. The vertical ram 3 is provided with a holder 4 for a central broach 5 and two side broaches 6 and is reciprocated by means of a rack 7 and a pinion 8, the pinion being driven from an electric motor 160, Fig. 16, through gears 164, 165, spiral gears 168, 169, and shaft 167. The ram carries upper and lower dogs 10, 11 respectively, which coact with a roller 18 on a twoarmed lever 16, 17, mounted on a rock-shaft 15. The rock-shaft also carries an arm 173 having segmental teeth engaging a pinion 172 which operates a controller 170 for reversing the direction of the motor at opposite ends of the ram stroke. A lever 19, pivoted at 26, carries a pin 27 coacting with two notches 30, 301 in a pivoted trip member 20, the upper end of which coacts with a dog 25 pivoted to the lower end of a lever arm 21 pivoted at 22. A link 23, pivoted at one end to the arm 21, has a hook engageable with a pin 35 on the arm 16, and a dog 24, pivoted at 31, carries a separate pivoted shoe 36 which has a lug 40 riding on the lever 19. The framing carries a bed 41 secured by bars 43, and adjustable to and from the ram 3 by means of a threaded stud 47 passing through a lug on the bed. A hollow rock-shaft 56 is mounted in a bearing 53 and encloses a cam shaft 57 carrying a cam 60 and having pinion teeth 65 engaging a sector 66 on the arm 21. The shaft 57 carries a sliding handle 63 which is normally inoperative but which may be engaged with a pin 61 for hand operation. A trunnion 58 of a hollow cylinder 100 is keyed to the hollow shaft 56 to which is also keyed the hub 68 of a rocker arm 69 connected by a link 74 to the arm 21. Thus during the rocking movement of the arm 21 the pinion 65 is oscillated to rotate the cam shaft 57 alternately in opposite directions while the arm 69 also imparts oscillating movement to the hollow shaft 56 and trunnion 58. The hollow shaft carries a rocking work-holder 77 which is keyed thereto at 79 and is bifurcated at 83 to form a work-locating arm 84 and a clamp-carrying arm 85. The arm 84 carries side-plates 86 whose edges coact with the edge of the arm to provide a supporting surface for the work 87 such as a hinge leaf, the lower edge of the work resting on a pin 88. The arm 85 is slotted to receive a clamp 90 which is pivoted at 91 and carries a pivoted forked clamping-piece 94 adapted to engage and fit closely against the hinge. The clamping jaw is rocked on its pivot to grip the work by means of the cam 60 which acts through a plunger 81 and a stiff spring 82. The gripping and locating members are narrower than the work piece in order that the sides of the work may be broached by the broaches 6. Clearance is also allowed for the central broach 5. When the plunger 81 is in its withdrawn position the work clamp is kept from closing accidentally by means of a bolt 96. The rocking movement of the shaft 56 serves to transfer the work from the broaching position, Fig. 10, to a loading position, Fig. 8, and the parts are timed so that the clamp is closed as the work approaches the broaching position and is released on approach to the discharging and loading position. The position of the rocker 77 at the broaching position is determined by a pillow block 98. The cylinder 100 carries a spring latch 101 having an angular base coacting with inclined surfaces 107, 108, Fig. 3, on a block 102 so that when the cylinder is rocked by movement of the shaft 56 the latch snaps into position against one or other of the surfaces 107, 108, and assists in maintaining the work-holder in one or other of its extreme positions and in preventing rebound or back lash in the work-holder movement. When the work-holder is in the loading position a work piece is placed between the jaws by the operator, side guides 157 being provided to facilitate this operation. A shaft 116 journalled in a housing 109 carries a pinion engaging a rack on a safety bar 119. When the pinion is rotated by mechanism operated from the rock arm 21, the bar 119 normally passes over the work piece but if the work piece is incorrectly positioned, the bar 119 is obstructed and the rocker 77 cannot then be operated to move the work into the broaching position. An extractor device for removing a finished work piece is carried on a bracket 139 secured to the ram. The bracket carries a stem 141 terminating in a lug 142 carrying a head 138 provided with clamping jaws. The jaws are normally disposed at a distance apart somewhat less than the thickness of the work but as the ram approaches its lowest position and the work has been returned to loading position the jaws engage the sides of the work piece and are pushed back against spring resistance along inclined guides being thus separated to permit them to engage the sides of the work. The work piece remains in the jaws until the next downward movement when it is ejected by the next work piece located in the holder, the jaws then passing on to this second work piece which is removed and ejected in turn. In operation when the dog 10 on descent of the ram, engages the roll 18, the lever mechanism, Fig. 10, is operated to swing the arm 21 and move the work-holder to loading position. The clamp is also opened and the work piece picked up by the extractor jaws, the previous work piece being thereby ejected. The ram moves up while the operator inserts a fresh work piece and at the same time lifts the lever 122. This action, through the lever mechanism shown in Fig. 10, lifts the lever 19 and locates the dog 24 in front of the pin 35, the lever 19 being held in the raised position by the trip 20. If, however, the path of the safety bar 119 is obstructed by the work piece the dog 24 cannot be set in this way. As the ram approaches the upper end of its travel, the dog 11 engages the arm 17 and through the arm 16 and dog 24 pushes back the arm 21 thus clamping the fresh work piece and moving the work-holder into the broaching position after which the ram is reversed for the operative stroke. At the time that the arm 21 is moved forward the dog 25 knocks the trip 20 from the pin 27 and permits the lever 19 to fall to the Fig. 10 position. The work-holder is provided with troughs 159 to catch oil and particles cut from the work and prevent clogging of the clamping mechanism.