Handling: hand and hoist-line implements – Utilizing fluid pressure – Frames
Patent
1986-09-08
1988-05-17
Marbert, James B.
Handling: hand and hoist-line implements
Utilizing fluid pressure
Frames
294 812, 294 814, 414730, 414737, B66G 102
Patent
active
047445955
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hoisting apparatus for groupwise transfer, i.e. hoisting and lowering, of cargo units in the form of substantially uniform cargo pieces, such as paper rolls, bales, boxes, drums and the like.
The invention more particularly relates to a means for automatic positioning of gripper means such as vacuum cups in order to space the same relative to the center distance between the cargo units in the group to be transferred.
The invention is particularly developed for groupwise transfer of paper rolls and shall in the following be described and illustrated for such use, but it shall be understood that the invention with similar advantages can be utilized for groupwise transfer of other kinds of unit cargo such as bales, boxes, containers and the like.
In the following specification the gripper means are specified as vacuum lifters or vacuum cups, but it shall be understood that the invention can be utilized with other forms for gripper means, for instance magnetic grippers or lifters or mechanical gripper means.
In known cargo systems for handling standard paper rolls arranged side by side in parallel rows adjacent each other the rolls having the same length or height, but possibly slightly varying diameter, a group of the rolls usually is grasped at the time and lifted by means of socalled vacuum cups. The cups are suspended in two or more parallel rows in an overhanging hoisting bank, usually an extensible and retractable pantographic socalled zigzag frame such that the center distance between the vacuum cups can be adjusted to fit the center distance between the rolls in the selected groups to be transferred. The vacuum cups are usually given a diameter somewhat smaller than the applicable central area or core of the rolls, such that a certain variation in the distance between the center of the rolls can be tolerated, without necessitating adjustments, but adjustments are most often required. The hoisting bank with the cups is suspended below a socalled turntable, the pivoting of which is controlled by the crane operator.
As illustrative for the prior art can be referred to Norwegian patent specification Nos. 133.886 and No. 135.521. In the latter patent are shown two steering or guiding rams, one arm mounted at each end of the hoisting bank, the arms in active position being positioned lower than the vacuum cups. The crane operator lowers the hoisting bank over the group to be transferred such that the control arms come into contact with one or more of the cargo units at each end of the group. The crane operator thereafter adjusts, i.e. extends or retracts the hoisting ramp, by eyesight, until the guiding arms come in position between suitably the two outermost units at each end of the long side of the group in order to ensure correct positioning of the vacuum cups. The problem in connection with this solution is that the crane operator, who very often is positioned far above the cargo, for instance 40-50 meters above the place where the cargo must be picked up, hardly can observe the exact position of the hoisting ramp, i.e. control that the actual center distance between the vacuum cups conforms to the center distance between the cargo units. For this reason a skilled operator must always stand by when lowering the hoisting ramp on to the group of cargo to be lifted, and give signs or otherwise communicate with the crane operator who thereafter, when he assumes everything is in order, lowers the vacuum cups and actuates the same in order to hoist up the selected group of cargo units.
Especially when using grippers such as vacuum cups, it is very important that the cups are positioned centrally on the paper rolls. Only slightly displaced positioning of the vacuum cups on the rolls will imply that the rolls will be hanging at a tilt, a fact which again implies that the gripping force of the cups is greatly reduced. A displaced positioning of for instance 5 centimeters may imply that the rolls get a tilt of about 7.degree. from the vertical, and this again can result in up to
REFERENCES:
patent: 3610673 (1971-10-01), Strombeck et al.
patent: 3831992 (1974-08-01), Francois
Halvorson Jacob S.
Tonning Erling
Leif Hoegh & Co. A/S
Marbert James B.
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