Patent Application
20150076100
The present disclosure relates to lifting systems. More particularly, the present disclosure relates to a load monitoring system for a lifting system.
During a manufacturing process, a product is typically advanced through a plurality of manufacturing stations within a manufacturing chain. Specifically, the product is transported through each of the manufacturing stations along a transportation system. The transportation systems may include overhead cranes, which are designed to lift and transport loads, within or between manufacturing stations. Overhead cranes, particularly those of the larger type, most commonly embody a bridge girder supported on trucks. The trucks are movable over runway beams supported on columns. In addition, the overhead crane includes one or more lifting components structured to lift loads for transportation. The lifting component, such as hook, strap, magnet, and/or the like, is coupled to a trolley frame slidably mounted on the bridge girder. Such lifting components may have rated capacities for a favorable lift operation. Further, during the lift operation, the lifting components may be subjected to stresses due to the loads being lifted by the lifting components. It may be considered that during the lift operation, the strain caused upon the lifting component, due to the lifted loads, may exceed a pre-determined threshold value. Since, the hoist devices have rated capacities, lifting the loads beyond the rated capacities may impose considerable stress on the lifting component and may result in unfavorable consequences.
U.S. Publication No. 2010/0044332 discloses a method to monitor overstress conditions experienced by a crane component. In the overstress condition, a wireless signal that indicates an overstress condition is generated. In response to receipt of the wireless signal, a record of the overstress condition is stored in a storage module mechanically coupled with a crane component. However, the reference does not discuss a provision for an active overstress prevention based on rated capacities of lifting components.
The present disclosure relates to a load monitoring system for a lifting system. The lifting device is configured to lift a load during a lifting operation.
In accordance with the present disclosure, the load monitoring system includes a lifting link assembly and a controller. The lifting link assembly includes a link body, a strain sensor, and a radio frequency identification (RFID) device. The link body is structured and arranged to couple the lifting device to the load. The strain sensor is fixed to the link body and is configured to generate a signal corresponding to the load. The RFID device is fixed to the link body and is configured to receive the signal. Further, the controller is in communication with the RFID device, and is configured to receive the signal from the RFID device and initiate a safe lifting protocol in response to the signal attaining a pre-determined threshold value.
a is a perspective view of a second embodiment of a lifting link assembly for use within the lifting system of
b is a perspective view of a third embodiment of a lifting link assembly for use within the lifting system of
c is a perspective view of a fourth embodiment of a lifting link assembly for use within the lifting system of
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The idler girder 110 is attached between the pair of the trucks 108. The idler girder 110 includes a first end 124 and a second end 126, which defines a bridge rail 128. The first end 124 and the second end 126 include a plurality of end stops 130. Further, the bridge rail 128 is structured to facilitate slidable movement of the trolley frame 112. The movement of the trolley frame 112 may slide over the bridge rail 128; however, such movement of the trolley frame 112 is restricted by the end stops 130 placed at the first end 124 and the second end 126. The trolley frame 112 includes a hoist 132 and the pair of trolley drives 116. The trolley drives 116 on each side of the trolley frame 112 facilitate the slidable movement of the trolley frame 112 over the bridge rail 128 between the first end 124 and the second end 126 of the idler girder 110.
Further, the lifting device 104 may be coupled to a hook 134, via the lifting link assembly 102′. The lifting link assembly 102′ may be a strap, cord or chain member, for example, or any portion of the aforesaid hereof, fitted with a force sensing and communication componentry as will be described herein below. Further, as seen in
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The strain sensor 202 is in communication with the RFID device 204. The strain measured by the strain sensor 202 is wirelessly communicated to a controller (shown as 502 in
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In operation, during the lift operation, the load 136 is engaged with the lifting link assembly 102, which includes the strain sensor 202 and the RFID device 204. As the lifting device 104 lifts the load 136 off a rest position, the strain sensor 202 in the lifting link assembly 102 stretches in length. By this means, there is an increase in electrical resistance. This results in generation of the signal that corresponds to the strain experienced by the strain sensor 202. The signal thus generated is communicated to the RFID device 204, which is connected to the strain sensor 202. The RFID device 204 then sends the signal to the controller 502. The controller 502 infers the strain information, which is based on the signal and determines if the measured strain is equal to the pre-determined threshold value for the respective lifting link assembly 102. The pre-determined threshold value corresponds to the strain beyond which the lifting link assembly 102 may fail. Thus, upon determination that the strain in the strain sensor 202 of the lifting link assembly 102 has reached the pre-determined threshold value, the controller 502 initiates a safe lifting protocol and sends signals to the lifting device 104 to disable or stop the lift operation. The controller 502 also sends alert signals to the display 504 for operator information. The display 504 is adapted to visually represent data that pertains to the lift operation received by the controller 502. The alert signal may be accompanied with sound alerts. In an embodiment, the controller 502 disables all navigation functions, except for the function that lowers the load 136.
For example, the lifting system 100 includes the lifting link assembly 102′ and 102″. In such case, the lifting link assembly 102″ may fail at a lower load as compared to the lifting link assembly 102′. This implies that the pre-determined threshold value for the lifting link assembly 102″ is lower than the pre-determined threshold value of the lifting link assembly 102′. Thus, in this case, the controller 502 gives priority to a lower pre-determined threshold value. The lower pre-determined threshold value corresponds to the pre-determined threshold value of lifting link assembly 102″. This helps in prevention of the failure of the lifting link assembly 102″, while lifting the load 136. This way failure of the weakest lifting link assembly 102 is prevented. In an embodiment, the RFID device 204 is coupled to loads, fixtures, pallets, and actual parts involved in the lift operation. In such case, an RFID reader is employed to extract information regarding the weight of the loads, fixtures, pallets, and/or actual parts (such as clamping/holding devices) and pre-determined threshold strain value for each of the loads, fixtures, pallets, and/or actual parts. Further, this may indicate whether the loads, fixtures, pallets, actual parts, and/or the current lifting link assembly 102 are favorable for the lift, which prevents any unfavorable results. Accordingly, the load monitoring system 500 notifies the operator about the lift operation via the display 504. This implies that the load monitoring system 500 notifies the operator if all conditions are optimum for the lift operation or what units need to be replaced to complete the lift operation, for example, if the lifting link assembly 102 does not meet weight limits or the load exceeds limit for the lifting device 104. The proposed load monitoring system 500 intends to provide a real-time monitoring of the load 136 to increase productivity of the lift operations. The disclosed load monitoring system 500 makes use of strain sensors which provides information of stresses in the lifting link assemblies 102. On reaching, the pre-determined threshold strain value, the disclosed system stops the raising of the lifting link assembly 102, thereby halting the lift operation. The existing systems calculate favorable total lift weight based on weight of each object to be lifted.
The many features and advantages of the disclosure are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the disclosure, which fall within the true spirit and scope thereof. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the disclosure.
