Patent GB-559698-A (GB)
Title: Improvements in or relating to mechanically operated presses
IPC: B30B15/14
Filed: 1942-08-26
Abstract: 559,698. Mechanical presses; operating clutches. GOLDING, W. F., and NUELL, A. P. Aug. 26, 1942, No. 12015. [Class 87 (ii)] [Also in Group XXIV] A mechanically-operated press, of the type having a constantly-rotating flywheel, pulley, gear &c. which is clutched to a crankshaft, toggle or other pressure-applying mechanism, includes mechanism which is automatically brought into operation to disengage the clutch when the pressing member reaches a point of dwell, e.g. of maximum pressure, and to reengage the clutch after a predetermined period. The clutch is held in engaged position by a catch. When a cam trips the catch, a spring pulls the clutch out. At the end of an interval the length of which is determined by the setting of two gear wheels relative to one another, a drive containing the gear wheels has rotated a second cam to such a position that it actuates lever mechanism to re-engage the clutch and so restart the press. The crank shaft 39 of a press is driven, through the medium of a clutch (not shown), by a constantly rotating flywheel. The clutch is operated by a sleeve 1 mounted to slide on the driving shaft 41 of the press. The sleeve 1 is actuated by a lever 8 fixed to a shaft 7 which is rocked by a lever 36 coupled to a slidable bar 30. When the crank shaft is rotating, the bar 30 is maintained in its leftward (closed-clutch) position, against the pressure of a spring 38, by a catch 2 mounted on a lever 3.. When the crank shaft reaches a certain position a cam 5 rocks the lever 3, the catch 2 is tripped, the spring 38 urges the bar 30 and sleeve 1 to the right, and the crank shaft stops. The crank shaft remains stationary for a period of time determined as described below, and is then restarted by the following means :-The flywheel drives, through gearing 22 ... 11, a shaft 10 carrying a cam 9 which, at the end of the crank shaft dwell, rocks clockwise a lever 6 which is coupled to lever 8 by a dogclutch 25; the bar 30 (and sleeve 1) is thus moved to the left, closing the clutch, and is retained by the catch 2. Presently the cam 5 rocks the lever 3 again, and the sequence is repeated. As lever 36 moves, a projection 43 thereon engages a lever 40 to apply or release a brake which stops the press when the clutch is disengaged. The period of dwell is determined by the setting, relative to each other, of two intermeshing gears 11, 12. The gear 11 is fixed on the shaft 10, and the gear 12 is free to rotate clockwise on the crank shaft. The gear 12 is driven, from the flywheel, by two drives, (a) through gearing 22 ... 11, (b) through the clutch, the crank shaft, a ratchet wheel 24 which is fixed on the crank shaft and has one tooth only, and a spring- pressed pawl 23 mounted on the gear 12. Both drives turn the gear 12 clockwise, but drive (a) is slower than drive (b). When the crank shaft stops, the gear 12 still turns (through drive (a)) and the pawl 23 runs away from the ratchet 24. When the crank shaft re-starts, the ratchet 24 overtakes the pawl 23 and drives the gear 12 ; when this happens, a ratchet wheel 17 runs away from a gear 15. (The arrangement constitutes a closed driveflywheel, clutch, crank shaft, gear 12, gearing 11-22, flywheel-having two degrees of freedom at 17 and 24.) When the crank shaft stops the peak of the cam is at some position C, and must rotate to position D before it can close the clutch. The distance C-D, and hence the period of dwell, may be varied by engaging the teeth of gears 11, 12 as desired. Manual stopping and starting :-When the press is idle, the parts 6, 8 of the clutch-closing lever are disengaged from each other, and the bar 30 is in the right-hand position. To start the press, a bar 32 is depressed by hand or foot, thereby rocking bell-crank levers 31, 35 counterclockwise so that (a) bar 30 is moved to the left and retained by the catch 2, and (b) bar 29 is moved to the left and allows a spring (not shown) to move the dog-clutch 25 to couple the parts 6, 8. During subsequent automatic stoppages of the press, lost-motion slots 33, 34 in the bar 32 allow the bar 29 to remain undisturbed. To stop the press the bar 32 is raised high enough to move bar 29 to the right and thus open the dog-clutch.