Handling: hand and hoist-line implements – Grapple – Multiple grapples for multiple objects
Reexamination Certificate
1999-07-30
2001-07-03
Cherry, Johnny D. (Department: 3652)
Handling: hand and hoist-line implements
Grapple
Multiple grapples for multiple objects
C294S103100
Reexamination Certificate
active
06254156
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to end effectors used with robots. More specifically, the present invention relates to an end effector having rolling blades to pick up cups and similar items.
Robots carry out tasks with speed, accuracy, and repeatability that can not be matched by manual techniques. They are used in a variety of applications, from welding to picking up and handling all sorts of items. In order to carry out these tasks, robots are equipped with “end effectors,” devices designed to effect a desired action. End effectors often take the form of mechanical fingers, claws, or jaws that mechanically compress articles between two members. While these types of end effectors (sometimes called “grippers”) are effective for use in industrial environments and to manipulate objects that are hard and relatively heavy, they are not useful for handling lighter, delicate, or easily crushed items.
For example, plastic glasses and cups are difficult to handle using typical robot grippers because they are usually made from materials that can be crushed or broken relatively easily. In addition, cups and glasses are often placed inside one another to create hard-to-handle, large stacks. The stacks can be unstable if they are not grasped along their entire length. It is also difficult to remove and place stacks of items in boxes and similar containers, because the area within such containers is limited and stacks are often surrounded on three sides (either by another stack or a wall of the container). This makes it difficult to grab or grip the stack without damaging the container or other stacks. Accordingly, the packing and unpacking of cups and similar items is often done using manual or semi-automated mechanisms. However, if an end effector existed that could grasp stacks of such items and deliver such items without damage, in the confines of a container, the benefits of robotic automation could be realized.
SUMMARY OF THE INVENTION
Therefore, it is an objective of the present invention to provide a robot end effector that can grasp stacks of cups, glasses, and similar items. This objective and others are achieved in an end effector having a mounting bracket or similar mount designed to be coupled to the arm of a robot. A main plate or body with a top side, a bottom side, and a plurality of apertures is connected to the bracket and supports the major components of the end effector.
The end effector includes at least one bay positioned in the bottom side of the main body. Each bay is defined by two side walls and is sized and shaped such that it can hold two parallel stacks of cups, glasses, or similar items. Within each bay is a multiple-piece blade support block that runs substantially the entire length of the bay and acts as a guide for the blades located within the bay. One or more roller blocks are positioned at predetermined points along the length of the bay, preferably between two pieces of the blade support block. Each roller block has an arcuate track that holds a roller assembly. Each roller assembly has a shaft which extends through one of the apertures in the main body. Each roller assembly is also coupled to a curved blade. One or more linear actuators are positioned on the top side of the main body. The drive shafts of each actuator are coupled to one or more of the roller assembly shafts. When the actuators are activated, the roller assemblies move in their tracks and the blades slide between an open position and a closed position.
In one embodiment, the end effector includes two actuators, three bays formed on the bottom of the main body, and each bay contains a pair of blades. The drive shaft from one of the actuators is coupled to a drive link that is connected to three roller assembly shafts and the drive shaft from the other actuator is coupled to a second drive link coupled to a second set of three roller assembly shafts. As each linear actuator moves between a retracted position and an extended position, it moves each of the three pairs of blades between an open position and a closed position.
In use, the end effector is coupled to a conventional, programmable, industrial robot which may move the end effector to desired locations between a stacking station and an open box or carton to be filled with stacks of plastic cups. For example, with the blades in the end effector in an open position, it may be moved down over a layer of parallel stacks of cups at a stacking station on a manufacturing line. Once the end effector is in place, the blades are moved to their closed position so that a portion of each blade is positioned partially under one stack of cups. With each stack so gripped, the end effector can then be raised by the robot and moved to a drop-off location such as an open box or carton. The cycle can be repeated to fill the carton and then to fill multiple cartons. Advantageously, this gripping and loading task is accomplished without the need to apply the typical contact and compression forces used in most end effectors, as the only force impacting the gripped items is their own weight against the blades.
Another advantage of the present invention is that gripping and releasing of the items can be accomplished in a confined space (such as a box or carton) because the curved blades remain within each bay at all times. Thus, unlike many known grippers and end effectors, the grasping elements do not extend beyond and outside of the end effector in order to successfully surround and then hold the objects of interest.
Still further objectives and features of the present invention will become apparent by a review of the description below and accompanying drawings.
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Sherwin John P.
Voves David R.
ABB Flexible Automation Inc.
Cherry Johnny D.
Godfrey & Kahn S.C.
Kees Nicholas A.
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