| 摘要 |
<p>1,176,963. Metal strip feeds. MAGNETIC METALS CO. 10 Aug., 1967 [19 Aug., 1966], No. 36831/67. Heading B3W. A punching press has feed means which are driven from the main shaft of the press, the drive means including a first shaft which rotates with uniform angular velocity through a complete revolution for each cycle of operation and drives a second shaft so that it has non- uniform angular velocity, the second shaft being connected to the input shaft of a further device which also has an output shaft, the input and output shafts being connected so that the output shaft rotates in response to rotation of the input shaft over a first predetermined portion of a revolution and then dwells during the remainder of that revolution. The metal strip is fed into the press by feed rolls of which one is intermittently driven and the other is spring-loaded against the driven roll. The take-off shaft of the press which makes one revolution for each cycle of the press drives an elliptical gear 136, Fig. 10, which meshes with a second elliptical gear 142. The shaft 133 of the second gear drives a shaft on which is eccentrically mounted a pinion 47. This pinion meshes with an idler gear 48 and an output gear 49 which dwells during part of the rotation of pinion 47. This part of the mechanism is fully described in Specification 1,097,480 (Division B3). In a modification the gear train 47, 48, 49 is replaced by a Geneva cam mechanism which is fully described in Specification 1,159,883. The elliptical gears are mounted in a casing, Fig. 8, on parallel shafts 132, 133. Also included in the casing are two circular gears 137, 143, each mounted on one of the shafts. The gears 136, 137 are mounted on a sleeve which is keyed to but slidable along the shaft 132. By moving a spacer 140 from the position shown in Fig. 8, to a position between the gear 136 and the adjacent wall of the casing, the gears 136, 142 are disengaged and the gears 137, 143 are engaged. The angular positions of the gears 136, 142 are such, in relation to the remainder of the mechanism shown in Fig. 10, that the angular velocity of gear 133 is at a minimum when it is at the midpoint of its angular range of motion throughout which the dwell of the output gear 49 occurs. The effect of the elliptical gears is to increase the dwell time of the output shaft from about 90 degrees, which is about the maximum which can be achieved with either of the previously disclosed constructions, to 180 degrees.</p> |
