Material or article handling – Load carried along a horizontal linear path – Having gripper means
Patent
1989-09-22
1990-12-04
Spar, Robert J.
Material or article handling
Load carried along a horizontal linear path
Having gripper means
294 8152, 294 6732, 414662, 414589, 414225, B23Q 100
Patent
active
049750186
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a linear unit for transferring objects, particularly for removing workpieces from a linear conveying track, such as an assembly or manufacturing belt, and comprising vertically and horizontally movable grippers for gripping an object and supported on a gripper carrier movable between pick-up and delivery positions.
For example, in assembly or production lines, such linear units serve to grasp and transfer workpieces which are transported on a linear conveying track, e.g. conveyor belt, e.g. to a second conveyor belt or to a processing station. For this purpose, the grippers are moved by a gripper carrier to a pick-up position, where they grip the workpiece, and then to a delivery position, where they deposit the workpiece again. Costly control mechanisms are required for the coordinated interplay of the gripper movements necessary for gripping and depositing.
SUMMARY OF THE INVENTION
The object of the invention is to simplify the structure of the linear unit for transferring objects.
This object and others which will become more apparent hereinafter is attained by providing a linear movement in which the movement sequence of the grippers for picking up an object at the pick-up position and depositing it at the delivery position is caused by an excess lift of the gripper carrier after it reaches the pick-up and delivery positions. The sequence of movements for gripping or depositing the objects is positively controlled mechanically and is carried out automatically by the excess lift of the gripper carrier after it reaches the pick-up and delivery positions, respectively.
It has proven advisable to divide the sequence of movements of the grippers into a horizontal rotational or swiveling movement and a vertical displacing movement which are carried out one after the other and in the reverse sequence in the pick-up and delivery positions. These two portions of the movement sequence can be achieved by means of the excess lift of the gripper carrier in a simple manner by providing a toothed rack and pinion gearing between the gripper carrier and gripper and by forming the grippers of vertical gripping arms and horizontal gripping fingers which are coupled with one another via a coarse thread connection in each instance. This has the advantage that the individual phases of the movement sequence need not be adapted to the size of the respective object to be transferred, but are independent of this. However, the workpieces are held with the same gripping force regardless of their size. The gripping technology used in the linear unit, according to the invention, is accordingly independent of the size of the object, wherein the maximum size of the workpieces to be grasped is, of course, determined by the distances of the vertical gripping arms from one another.
It is possible to feed and guide away the object to be transferred or gripped on all sides of the linear unit when four vertical gripping arms are provided so as to be equidistant from one another.
An additionally increased gripping force which ensures a secure holding of the gripped object during the movement of the gripper carrier is imparted to the gripping fingers at the end of the movement sequence by forming the coarse thread connection having a length that is less than the excess lift of the gripper carrier with the gripping fingers contacting the object in a force-locking manner. The lifting movement of the gripping fingers is defined by the end of the coarse-thread connection and the remaining slight residual excess lift of the gripper carrier forces a rotation of the gripping arms and, accordingly, an increased contact pressure of the gripping fingers at the object which is already gripped and lifted.
The excess lift of the gripper carrier required in the end stations of the gripper carrier, that is, in the pick-up and delivery position, when the grippers are positioned can be achieved in a simple manner by constructing the gripper carrier as a carriage which reciprocates axially and comprises
REFERENCES:
patent: 3774778 (1973-11-01), Flaig
patent: 4030614 (1977-06-01), Taneda et al.
patent: 4240237 (1980-12-01), Alduk et al.
Langenbacher Markus
Maier Gernot
Rothfuss Peter
Eller Jr. James T.
Robert & Bosch GmbH
Spar Robert J.
Striker Michael J.
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