Material or article handling – Vertically swinging load support
Reexamination Certificate
1998-06-25
2001-11-06
Underwood, Donald W. (Department: 3352)
Material or article handling
Vertically swinging load support
C212S287000, C414S017000
Reexamination Certificate
active
06312211
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to load balancing mechanisms for facilitating handling of parts by a worker in assembly operations and, more particularly, to semi-automated load balancing mechanisms which automatically move parts between supply and assembly lines.
BACKGROUND ART
Workers use conventional load balancing mechanisms to handle equipment such as heavy air driven tools and to aid in placement for mounting parts in assembly line operations. These load balancing mechanisms supply supporting forces in a vertical direction to counter gravitational force for supporting a load and also structure to resist torque and vibration associated with tool operations. Typical load balancing mechanisms include a two-piece articulated arm of a straight cross section pivotally connected to a support post about which the arm is rotatable. The arm is pivotal for movement in a vertical plane and also rotatable about an axis of rotation horizontally displaced from an axis of the support post. A hinged connection allows the two sections of the arm to be selectively moved by a worker for placement of a load located at a distal end of one of the arms within the reach of the articulated arm.
In this conventional arrangement of the load balancing mechanism, deflection is created in the support post by the weight of the arm and is increased by the application of a load on the arm. This deflection establishes a home position, due to the combined effect of deflection of the axis of rotation and the axis of rotation being displaced from the axis of the support post, which is at a lowest elevational position for the arm about the post. The arm drifts to this home position if left uncontrolled or unattended. This drift is further exaggerated by the hinged construction of the articulated arm and makes controlling the arm mandatory.
The straight cross sectional shape of the articulated arm also necessitates applying a greater lifting force to the arm to counter the weight of a load applied to the end of the arm as the greatest bending movement occurs at the connection of the support post and arm.
U.S. Pat. No. 5,037,267, entitled Load Balancing Mechanism, hereby incorporated by reference, discloses an improved load balancing mechanism which overcomes the above noted deficiencies of conventional load balancing mechanisms. However, the improved load balancing mechanism is designed solely for manual use by a worker.
A problem with load balancing mechanisms designed solely for manual use is that too much time and energy is wasted. For instance, in automobile assembly operations for placing an automobile seat into an automobile frame, a worker initially uses the mechanism to pick up a seat from a supply line or pickup position. Then, the worker moves the mechanism away from the supply line towards the assembly line to position the seat adjacent an automobile frame on the assembly line. The worker then uses the mechanism to place the seat into the automobile frame. To repeat the process for the next automobile frame coming down the assembly line, the worker moves the mechanism back to the supply line adjacent the next seat coming down the supply line to use the mechanism to pick up that seat.
Time and effort could be saved if the mechanism automatically moved between a part pickup position where it retrieves a part, and an “operator” position, for example adjacent the assembly line; at which operator position the worker could take over and manually move the part carried by the mechanism to mount the part into an automobile body or the like.
Thus, what is needed is an improved load balancing mechanism which overcomes the deficiencies associated with conventional load balancing mechanisms and is designed for combined automated and manual use by a worker.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a semi-automated load balancing mechanism designed for automatic and manual use.
It is another object of the present invention to provide a semi-automated load balancing mechanism which automatically moves between predetermined positions to facilitate part pickup and placement.
It is a further object of the present invention to provide a semi-automated load balancing mechanism which automatically moves between predetermined positions having given heights, given angles, and given longitudinal displacements relative to the mechanism.
In carrying out the above objects and other objects, the present invention provides a semi-automated load balancing mechanism having automatic and manual modes. In the disclosed embodiment the mechanism includes a post having a vertical axis. A first arm is pivotally mounted to the post for upward and downward pivotal movement. Constant force balancing means are connected to the post and the first arm for equilibrium balancing upward and downward pivotal movement of the arm and a load supported by the first arm. A first actuator is connected to the post and the first arm. The first actuator is extensible and retractable to pivotally move upward and downward the first arm. A controller is connected to the first actuator. The controller causes the first actuator to automatically move the first arm to a selected vertical position and disables the first actuator once the first arm is at the selected vertical position to allow an operator to manually move the first arm to move the load in a vertical direction.
The mechanism may also include rotating means for rotating the first arm about the vertical axis of the post to horizontally displaced positions. The controller is connected to the rotating means and causes the rotating means to automatically move the first arm to a selected horizontal position and disables the rotating means once the first arm is at the selected horizontal position to allow an operator to manually move the first arm to move the load in a horizontal direction.
The mechanism may further include a second arm mounted to the first arm. The second arm is movable along a longitudinal axis relative to the vertical axis of the post to move the load along the longitudinal axis. A second actuator is connected to the first and second arms. The second actuator is extensible and retractable to longitudinally move the second arm. The controller is connected to the second actuator and causes the second actuator to automatically move the second arm to a selected longitudinal position and disables the second actuator once the second arm is at the selected longitudinal position to allow an operator to manually move the second arm to move the load in a longitudinal direction.
The advantages accruing to the present invention are numerous. The controller moves the arms to a part pickup position. The part pickup position will have a given height, a given angle, and a given longitudinal displacement relative to the post. After part pickup, the controller moves the arms to an “operator” position. The operator position will also have a given height, a given angle, and a given longitudinal displacement relative to the post. At the operator position the worker may manually move the part while carried by the arms to place the part.
After the operator uses the arms in the manual mode to place the part, the arms may automatically return back to the part pickup position to get a new part. The transition from automatic to manual mode, or vice versa, may be determined either by the operator actuating a control switch or by the operator positioning the arms in a predetermined position, at which the mechanism would enter the automatic mode to return to the part pickup position. The process is then repeated with the arms automatically and accurately moving between the part pickup and operator positions to facilitate assembly operations. As a result, worker productivity greatly increases with a corresponding reduction in effort.
These and other features, aspects, and embodiments of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.
REFERENCES:
patent:
Protomark Corporation
Underwood Donald W.
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