Abstract:
A method for clearing stalled containers in a taping or other container sealer includes the steps of (i) conveying a container to a sealing station, (ii) sealing the container with a sealer at the sealing station as the container travels through the sealing station, (iii) detecting a stalled container in the sealing station, and (iv) raising the sealer upon detection of a stalled container in the sealing station to relieve the stalled condition so that the container travels through the sealing station and is sealed by the sealer. Raising the sealer can clear the stalled container, thereby minimizing or eliminating events that require an operator&#39;s attention.

Description:
This application is a national phase of International Application No. PCT/US2009/046391, filed Jun. 5, 2009, and published in English as WO 2009/149338 on Dec. 10, 2009, which claims the benefit of U.S. Provisional Patent Application No. 61/059,364, filed Jun. 6, 2008, which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is related to a system and method for sealing packing containers, and more particularly to a system and method for automatically applying packing tape or otherwise sealing a packing container. 
     BACKGROUND 
     In increasingly automated packaging systems, once an article has been placed in a container for shipment, a conveyor typically moves the container to an automated container closing and/or sealing assembly for closing the container and sealing it for shipment. The automated equipment also can apply a shipping label and/or the appropriate postage for the container. 
     One of the more common types of shipping containers is a cardboard box having one or more flaps that close an open side of the box. Once the box is ready to be sealed, automated assemblies can fold the flaps over the open side to close the box and then automatically seal the box for shipment, such as by taping the box closed. Automated assemblies that close the box and apply tape to hold the box closed can be referred to as automatic taping machines, and automated assemblies that just apply tape can be referred to as semi-automatic taping machines. 
     When the taping machine is sealing containers with a consistent height, a fixed-height tape-applying assembly applies tape to seal the containers. When sealing containers with different heights, an adjustable-height tape-applying assembly raises and lowers as needed to apply the tape and seal the containers. 
     One type of adjustable-height tape-applying assembly includes a pressure switch at an upstream end. When a container engages the pressure switch, the tape-applying assembly raises its height relative to the conveyor until the container no longer engages the pressure switch. The tape-applying assembly then proceeds to tape the container closed as it moves through or past the tape-applying assembly. 
     SUMMARY 
     The present invention provides a system and method for sealing a packing container that solves a problem with some prior adjustable-height taping assemblies where the container to be sealed catches on the tape-applying assembly and stalls or jams. The container does not progress past the taping assembly as it should. This can occur when a flap catches on part of the tape-applying assembly or when dunnage in the container creates a bulge at an upper end of the container, or when the taping assembly is below the appropriate height for that container, as a few examples. Such a situation typically would require an operator&#39;s attention both to recognize and correct the problem to relieve the stalled condition of the container. 
     The present invention solves the stalling problem by detecting the stalled condition automatically and taking action to resolve it. The present invention also alerts the operator when the actions taken failed to resolve the problem. And this solution is not limited to taping assemblies, but also applies to other types of adjustable-height container sealing mechanisms. 
     More particularly, the present invention provides a system and method that raises the taping or other sealing assembly or sealer under predetermined conditions, typically including one or more sensors detecting the presence of a container at two different times. Raising the sealer can clear the stalled container, thereby minimizing or eliminating events that require an operator&#39;s attention. The operator is alerted when the sealer reaches its maximum height without clearing the container, e.g., the sensor still detects the container at an upstream end of the sealer. Between raising the sealer and alerting the operator, the present invention provides systems and methods that minimize the time and attention required of the operator to ensure continued operation of the sealer. 
     Specifically, an exemplary system provided by the invention includes a conveyor that delivers a container to a sealing station, a sealer at the sealing station that seals the container closed as the container travels through the sealing station, a detector that detects a stalled container in the sealing station, and a sealer lift mechanism that raises the sealer upon detection of a stalled container in the sealing station to relieve the stalled condition of the container so that the container travels through the sealing station and is sealed by the sealer. 
     And an exemplary method provided by the invention includes the steps of conveying a container to a sealing station, sealing the container with a sealer at the sealing station as the container travels through the sealing station, detecting a stalled container in the sealing station, and raising the sealer upon detection of a stalled container in the sealing station to relieve the stalled condition so that the container travels through the sealing station and is sealed by the sealer. 
     The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail several illustrative embodiments of the invention, such being indicative, however, of but a few of the various ways in which the principles of the invention may be employed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a container-sealing system provided in accordance with the present invention. 
         FIG. 2  is perspective view of an exemplary container-sealing system provided in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention solves the problem of stalled containers by automatically raising an adjustable-height taping or other sealing assembly. Referring to the drawings, the present invention provides, for example, a system  100  for sealing a packing container  102 . The system  100  includes a conveyor  104  that delivers a container  102  to a sealing station  110 . A sealer or sealing assembly  112  at the sealing station  110  seals the container  102  closed as the container travels through the sealing station  110 . A detector  120  detects when a container  102  stalls in the sealing station  110  and a sealer lift mechanism  122  raises the sealer  112  upon detection of a stalled container. The system  100  raises the sealer  112  to relieve the stalled condition of the container  102  so that the container will travel through the sealing station  110  and be sealed by the sealer  112 . 
     Packing containers typically are one of two types. One type is a shoebox-style container having an enclosure with an opening on one side and a separate lid that closes the open side of the enclosure. Another type of container is the regular slotted container or similar container having one or more flaps that fold over an open side of the container to close it. Suitable sealers for any container type are available to tape the container and seal it, apply adhesive, apply heat to activate an adhesive or similar compound to seal the container, etc. 
     The conveyor  104  that delivers the container  102  to the sealing station  110  can be any type of conveyor, including a roller or belt conveyor, or other transport device for moving a container  102  to the sealing station  110 . The sealing station  110  typically has a conveyor that moves the container through the sealing station in an upstream-to-downstream direction  124 . A centering mechanism (not shown) typically engages the sides of the container to center it on the conveyor. The conveyor within the sealing station can be a continuation of the conveyor that delivers the container to the sealing station. 
     The sealer lift mechanism  122  can include a chain drive, a hydraulic drive mechanism, or other drive mechanism that lifts the sealer  112  relative to an upper surface of the conveyor  104 . The sealer  112  typically is moveable between a lower height position  126  above a conveyor surface and an upper height position  128  above the lower height position, the upper height position typically being a maximum height to which the sealer lift mechanism  122  can move the sealer  112 . 
     To control movement of the sealer  112  and accordingly control the sealer lift mechanism  122 , the system  100  can include a controller  130  connected to the detector  120  that controls the position of the sealer  112  in response to the detector detecting a stalled container in the sealing station  110 . The controller  130  typically includes a processor  132 , a memory  134 , and one or more input and output connections to the detector  120  and the sealer lift mechanism  122 , for example. 
     The controller controls the sealer lift mechanism  122  to move the sealer  112  toward the upper height position while predetermined criteria are satisfied. The predetermined criteria typically are satisfied when (a) the sealer  112  is not at the upper height position  128 , and (b) one or both of the following conditions also apply. Those conditions include (i) the detector  120  detects a container  102  at a first time and at a second time that occurs a predetermined period after the first time, or (ii) the detector  120  includes a first sensor  140  that detects a container  102  at the first time and a second sensor  142  spaced from the first sensor  140  that does not detect the container by the second time. In the first condition (i), the detector  120  includes a sensor  140  that detects a container  102  that is stalled adjacent the sensor. The container  102  either does not move quick enough to completely clear the sensor  140  within the predetermined period of time, or the container  102  is stuck at that location. 
     Containers can get stuck or stalled in a number of ways, including by not being square to the direction of travel, having an overfull container with flaps or contents that catch on the sealer to retard, or delay passage of the container past the sensor  140 . An overfull container that bulges in the middle could pass partially under the sealer before being stalled. The detector  120  can include both a first sensor  140  near an upstream end of the sealer  112  and a second sensor  142  spaced downstream of the first sensor  140 . In the alternative condition (ii), the container  102  does not travel sufficiently quickly from the first sensor  140  to the second sensor  142  within the predetermined period of time. So this also indicates that the container  102  has stalled and its passage though the sealing station  110  has been retarded, even if the container has passed the first sensor  140 . 
     While the predetermined criteria are satisfied, and a stalled container has been detected, the controller  130  can control the sealer lift mechanism  122  to repeatedly move the sealer  112  toward the upper height position in incremental steps at predetermined intervals. So, for example, while the predetermined criteria are satisfied, the controller  130  can control the sealer lift mechanism  122  to repeatedly move two centimeters at a time every fifteen seconds that the predetermined criteria are satisfied. Alternatively, while the predetermined criteria are satisfied the controller  130  can control the sealer lift mechanism  122  to continuously raise the sealer  112  toward the upper height position. When the predetermined criteria are no longer satisfied and the stalled condition of the container  102  has been relieved, the container will travel through the sealing station  110  and the sealer  112  will seal the container. 
     The predetermined time criteria can vary based on the size of the container, because a longer container will take more time to pass by a sensor and less time to reach a second sensor. Accordingly, the system  100  can also include a sensor  146  that identifies the container, whereby the controller  130  can determine the second time based on the container identification. This identification sensor  146  can be separate from or the same as the sensor  140  at the upstream end of the sealing station  110 . The identifying sensor  146  can include a barcode reader or other indicia detector, a radio frequency identification device (RFID) or other means for identifying the container. The controller  130  can determine the length of the container from data in a look-up table stored in the memory  134 , for example, to determine how long the container is. If the conveyor speed is known, the controller  130  can determine the second time based on the length of the container  102  and the speed of the conveyor  104 . This is the predetermined time at which the container should clear the sensor  140  and/or travel to the second sensor  142 . 
     If the predetermined criteria still are satisfied when the sealer has reached the upper position  128 , the controller  130  signals the operator for assistance. So the controller  130  also is connectable to an output device  150 . The controller  130  controls the output device  150  to signal an operator when (a) the sealer  112  is at the upper height position  128 , and (b) at least one of (i) a sensor  140  detects a container at both the first time and the second time, or (ii) a first sensor  140  detects a container at the first time and a second sensor  142  spaced downstream from the first sensor does not detect the container by the second time. The output device  150  can provide a visual, audible, electronic or other signal to alert an operator. The output device  150  can be located remotely relative to the controller  130  and/or the sealer  112  or can be located locally in the same place as the controller  130  and/or the sealer  112 . 
     The controller  130  can either be integral with the sealer  112  or be remotely located relative to the sealer. The conveyor  104  can be driven either continuously or intermittently as it delivers containers to the sealer  112 . The controller  130  also can be connected to the conveyor  104  to control the conveyor or to monitor the speed of the conveyor. So the conveyor speed can be controlled to adjust for a temporarily stalled container, or to maintain a constant speed as containers of different weights enter and leave the conveyor, for example. Connections between the controller  130 , the detector  120 , the conveyor  104 , and/or the sealer lift mechanism  122  can be continuous, intermittent through a wire, or wireless via infrared radio frequency or other signals in the electromagnetic spectrum. 
     An exemplary container sealing method employing the system provided by the invention includes the following steps: (a) conveying a container to a sealing station, (b) sealing the container with a sealer at the sealing station as the container travels through the sealing station, (c) detecting a stalled container in the sealing station, and (d) raising the sealer upon detection of a stalled container in the sealing station to relieve the stalled condition so that the container travels through the sealing station and is sealed by the sealer. 
     The raising step can include moving the sealer toward the upper height position while predetermined criteria are satisfied. As noted above, the predetermined criteria are satisfied when the sealer is not at the upper height position and a stalled container is detected. 
     The detecting step includes at least one of (i) detecting a container at a location at a first time and again at a second time that occurs a predetermined period after the first time, or (ii) detecting a container at a first location at the first time and failing to detect the container at a second location spaced downstream from the first location by the second time. Either variation indicates that the container is not progressing through the sealing station as fast as it should. The detecting step also can include the step of detecting a container at an upstream end of the sealing station, and detecting a container at a location downstream of the upstream end of the sealing station. Once a stalled container has been detected, other criteria can be used to determine when the stalled condition has been relieved. 
     If the detector  120  does not include the second sensor  142 , the controller  130  can stop raising the sealer  112  when the press  140  no longer detects the container  102  (or the sealer reaches the upper height position, although this does not resolve the stalled condition). If the sensor no longer detects the container, the container is presumed to continue to travel through the sealing station  110 . And if the detector  120  includes both the first sensor  140  and the second sensor  142 , the controller can stop moving the sealer when the container reaches or passes the second sensor  142  (or the sealer reaches the upper height position). 
     The moving step includes repeatedly moving the sealer stepwise at predetermined intervals while the predetermined criteria are satisfied. Such as moving one centimeter every two seconds until the stalled condition is resolved. Alternatively, the moving step includes continuously moving the sealer while the predetermined criteria are satisfied. When the system  100  includes both the first sensor  140  and the second sensor  142 , the incremental-movement should be used to minimize the chance that the sealer  112  will be raised too high to adequately seal the container. Otherwise, the method can include either incremental or continuous movement of the sealer toward the upper height position. 
     When both (a) the sealer has reached the upper height position, and (b) a stalled container is detected or the stalled condition has not been relieved, the method includes the step of signaling an operator to resolve the stalled condition. As discussed above, the method can include the step of identifying a container and determining the second time based on the container identification. The determining step can include determining the second time based on the length of the container, such as might be stored in memory, and the speed of the conveyor. The speed of the conveyor can be assumed to be constant or can be actively monitored and/or controlled. The conveying step can include driving a conveyor either continuously or intermittently. The method can also include monitoring the speed of the conveyor, controlling the speed of the conveyor, and closing one or more flaps of a container. The sealing step can include applying tape to a container, sealing with an adhesive, or applying heat to activate an adhesive to seal the container. 
     As mentioned above, some prior systems had a contact switch at an upstream end of the sealer. When a container pressed against the switch with sufficient force to close the switch, the sealer was raised until the switch cleared the container. If the container is not closed, however, upright flaps can exert enough force to close the switch, causing the sealer to rise above the closed height of the container. Then the sealer cannot properly seal the container. Alternatively, an over-full container with a bulging center might not close the switch before the leading edge moves under the sealer. The bulging center of the container could stall the container under the sealer without closing the switch to raise the sealer out of the way. The stalled condition would then require the attention of an operator. The system and method provided by the present invention avoid these problems, while also providing the ability to process different sizes of containers more quickly. 
     Although the invention has been shown and described with respect to a certain embodiment or embodiments, equivalent alterations and modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In particular regard to the various functions performed by the above described integers (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such integers are intended to correspond, unless otherwise indicated, to any integer that performs the specified function of the described integer (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure that performs the function in the herein illustrated exemplary embodiment of the invention.