Conveyors: power-driven – Conveyor section – Live roll
Patent
1990-07-20
1991-12-31
Valenza, Joseph E.
Conveyors: power-driven
Conveyor section
Live roll
192 56R, B65G 1306
Patent
active
050764217
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a slipping sprocket clutch for an accumulating roller conveyor.
An accumulating roller conveyor is a conveyor which has a plurality of transverse driven rollers, each of the rollers being driven via a respective slipping clutch. Each of the rollers is mounted on a respective shaft for conjoint rotation therewith, the shafts being drivable, via the slipping clutches, by a drive member extending longitudinally along the conveyor at one side thereof. The clutches are designed to permit slipping between the rollers and the drive member so that, when an item being conveyed is stopped, the clutches associated with the rollers engaging the item will slip. This ensures that these rollers are stationary, whilst all the other rollers continue to be driven Any other item on the conveyor does, therefore, continue to be conveyed. Consequently, items upstream of the stopped item will tend to accumulate behind the stopped item, and this gives rise to the term accumulating roller conveyor.
A known type of accumulating roller conveyor has a rotatable drive shaft extending along one side of the conveyor. Drive is transmitted to roller shafts via O-rings, each of which passes round the drive shaft and engages with a groove in a respective roller shaft. The O-rings constitute slipping clutches as they slip in the associated grooves when the corresponding rollers are prevented from rotating by a stationary item in contact therewith. The disadvantage of this type of conveyor is that the torque transmission from the drive shaft to the roller shafts depends upon the tension in the O-rings, and this is often insufficient to provide adequate torque transmission. Moreover, it is extremely difficult to control the tension in the O-rings so as to provide given torque transmission properties.
Another known type of accumulating roller conveyor has an endless drive chain constituting the drive member. This drive chain drives sprockets which in turn drive the roller shafts via slipping clutches. Each of these slipping clutches is a complicated ratchet arrangement having a plurality of cams and spring-loaded balls. The disadvantage of this type of conveyor is that it is difficult to assemble the clutches so as to give a desired torque transmission, and it is even more difficult subsequently to change their torque transmission properties. Because of its complicated construction, this type of conveyor is also relatively expensive.
In another known type of accumulating roller conveyor, the roller drive shafts are hexagonal, and the slipping clutches are constituted by deformable plastics tubes held in pockets in cages surrounding the shafts. The deformable plastics tubes associated with each of the hexagonal shafts are drivably engageable with the internal cylindrical surface of the corresponding roller so as to transmit torque thereto. Here again, drive is transmitted to the roller drive shafts, via sprockets fixed thereto, from an endless drive chain. If a given roller is prevented from rotation by a stationary item in contact therewith, the respective roller drive shaft can continue to rotate, with the plastics tubes being successively more and less deformed between that shaft and the internal cylindrical surface of the respective roller as the pointed regions of the shaft engage the plastics tubes. The disadvantage of this arrangement is that each clutch assembly needs four bearings, so that it is relatively expensive. Moreover, the rollers themselves require accurate machining, and extra sleeves are needed to accommodate the hexagonal shafts, and these steps entail further expense.
U.S. patent specification No. 4,286,441 describes an automatic slip coupling assembly for a roller conveyor. The slip coupling assembly incorporates a ball bearing which permits an associated sprocket to continue to rotate with slip taking place between the balls and an associated clutch plate, thereby preventing damage to conveyed goods if a jam occurs. Unfortunately, the bearing assembly is mounted on a journal bearing that can take
REFERENCES:
patent: 4063636 (1977-12-01), vom Stein
patent: 4286441 (1981-09-01), Scheneman, Jr. et al.
Automation Conveyors Limited
Dodd Thomas J.
Nguyen Tuan N.
Valenza Joseph E.
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