Strapping machine with retraction validation

Abstract

Various embodiments of the present disclosure provide a strapping system configured to feed strap into and around a strap chute that circumscribes a load; retract the strap; and, before tensioning the strap, validate that the strap has been adequately retracted from the strap chute.

Description

STRAPPING MACHINE WITH RETRACTION VALIDATIONPriority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 663,927, filed June 25, 2024, the entire contents of which is incorporated herein by reference.Field

[0002] The present disclosure relates to strapping machines for forming tensioned loops of strap around loads.Background

[0003] A strapping machine forms a loop of plastic strap (such as polyester or polypropylene strap), metal strap (such as steel strap), or paper strap around a load. Certain strapping machines include a support surface that supports the load, a strap chute that encircles the support surface, a strap reservoir (also called a strap accumulator or a slack box) storing strap in a slack state, a strapping head that forms the strap loop using strap drawn from the strap reservoir, a controller that controls the strapping head to strap the load, and a frame that supports these components. The strap reservoir is periodically replenished via strap drawn from a strap coil. A typical strapping head includes a strap-feeding assembly, a strap-tensioning assembly, and a strap-sealing assembly. The strap-feeding assembly is configured to feed strap from the strap reservoir into and around the strap chute and to retract the strap so it exits the strap chute and moves radially inwardly into engagement with the load with the excess being fed back into the strap reservoir. The strap-tensioning assembly is configured to tension the strap around the load. The strap-sealing assembly is configured to hold the leading end of the strap, to attach two portions of the strap together to form the tensioned strap loop, and to cut the tensioned strap loop from the remaining strap. Certain strapping machines have multiple strapping heads and respective strap chutes that define respective strap paths. These strapping machines are configured to simultaneously form multiple tensioned strap loops around a load using strap from separate respective strap supplies.

[0004] To strap the load, the strapping machine carries out a strapping process including a strap-feeding cycle, a strap-retraction cycle, a strap-tensioning cycle, and a strapsealing cycle. The strapping machine first carries out the strap-feeding cycle during which the strap-feeding assembly feeds strap (with the leading strap end first) through the strap-sealing assembly and into and around the strap chute until the leading strap end returns to the strapsealing assembly. The strapping machine then carries out the strap-retraction cycle during which the strap-sealing assembly holds the leading strap end while the strap-feeding assembly retracts the strap to pull the strap out of the strap chute and onto and around the load. The strapping machine then carries out the strap-tensioning cycle during which the strap-tensioning assembly tensions the strap to a designated strap tension. The strapping machine then carries out the strapsealing cycle during which the strap-sealing assembly attaches the leading strap end to another portion of the strap to form a strap joint, thereby forming a tensioned strap loop around the load, and cuts the tensioned strap loop from the remaining strap.

[0005] Press-type strapping machines apply a compressive force to the load to partially compress the load — such as to partially compress a stack of corrugated sheets — and / or to stabilize the load — such as to stabilize a load of stacked lumber — before strapping the load using one or more strapping heads. A typical press-type strapping machine includes a platen supported by the frame and vertically movable relative to the support surface and the load. The platen supports the strap-sealing assembly, and a strap dispenser adjacent the strapping machine supports the strap supply (e g., a coil of strap) and the strap-feeding and strap-tensioning assemblies. An input chute connects the strap-feeding assembly to the strap-sealing assembly and provides a path for the strap to follow when fed from the strap-feeding assembly to the strapsealing assembly.

[0006] To carry out a strapping process, the platen first moves downward toward the support surface and into engagement with the load. As the platen continues moving downward, it applies a compressive force to the load. As this occurs, the controller monitors the compressive force the platen applies to the load and stops the platen once the applied compressive force reaches a target compressive force. At this point, the load is stabilized and / or partially compressed (depending on the application), and the controller then controls the strapping head(s) to strap the load as explained above. The platen then moves upward away from the supportsurface and the load to disengage the load and enable the load to be moved out of the strapping machine.

[0007] Figures 1A-1F show a simplified illustration of a press-type strapping machine 1 carrying out this strapping process. A load L is moved onto a support surface of a load supporter 20 beneath a platen 30, as shown in Figure 1 A. The platen 30 descends into engagement with the load L and partially compresses the load L, as shown in Figure IB. The strapping machine 1 carries out the strap-feeding cycle by controlling a strap-feeding assembly to feed strap S from an inlet chute 70, leading strap end first, through a strap-sealing assembly 50 and into and around a strap chute 40 and then controlling the strap-sealing assembly 50 to hold the leading strap end once it traverses the strap chute 40, as shown in Figure 1C. The strapping machine 1 carries out the strap-retraction cycle by controlling the strap-feeding assembly to retract the strap S such that it exits the strap chute 40 and moves radially inwardly into engagement with the load L, as shown in Figure ID. The strapping machine 1 carries out the strap-tensioning cycle by controlling the strap-tensioning assembly to tension the strap S to a designated tension. The strapping machine 1 carries out the strap-sealing cycle by controlling the strap-sealing assembly 50 to attach two portions of the strap S to one another to form a tensioned strap loop TSL around the load L and to cut the tensioned strap loop TSL from the remaining strap S, as shown in Figure IE. The platen 30 ascends and disengages the load L, as shown in Figure IF, completing the strapping process.

[0008] Due to the quantity of and the nature of the components of strapping machines, the variability of the strap used in the strapping machines, and the environment in which the strapping machines operate, strap can occasionally get hung up during the strapretraction and the strap-tensioning cycles — such as by getting stuck in the strap chute — such that the strap is not completely engaged with and tensioned around the load before the strap-sealing assembly attaches two portions of the strap to one another. When this occurs, the strap loop formed by the strapping head is loose around the load, which is problematic.Summary

[0009] Various embodiments of the present disclosure provide a strapping system configured to feed strap into and around a strap chute that circumscribes a load; retract the strap;and, before tensioning the strap, validate that the strap has been adequately retracted from the strap chute.Brief Description of the Figures

[0010] Figures 1A-1F are simplified elevational views of an example known strapping machine compressing and strapping a load.

[0011] Figure 2 is a perspective view of one example embodiment of a strapping system of the present disclosure.

[0012] Figure 3 is a simplified elevational view of the strapping system of Figure 2.

[0013] Figure 4 is a block diagram showing certain components of the strapping system of Figure 2.

[0014] Figure 5 is a flowchart of an example strapping process of the present disclosure.

[0015] Figures 6A-6D are simplified elevational views of the strapping system of Figure 2 carrying out the strapping process of Figure 5.

[0016] Figure 7 is a flowchart of another example strapping process of the present disclosure.Detailed Description

[0017] While the systems, devices, and methods described herein may be embodied in various forms, the drawings show and the specification describes certain exemplary and nonlimiting embodiments. Not all of the components shown in the drawings and described in the specification may be required, and certain implementations may include additional, different, or fewer components. Variations in the arrangement and type of the components; the shapes, sizes, and materials of the components; and the manners of connections of the components may be made without departing from the spirit or scope of the claims. Unless otherwise indicated, any directions referred to in the specification reflect the orientations of the components shown in the corresponding drawings and do not limit the scope of the present disclosure. Further, terms that refer to mounting methods, such as mounted, connected, etc., are not intended to be limited to direct mounting methods but should be interpreted broadly to include indirect and operablymounted, connected, and like mounting methods. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the present disclosure and as understood by one of ordinary skill in the art.

[0018] Figures 2-4 show one example embodiment of a press-type strapping system 10 of the present disclosure and components thereof. The strapping system 10 includes a frame 100, a load supporter 200, a platen 300, a platen actuator 350, multiple strap chutes 400 (only one of which is shown for clarity), multiple strapping heads 500 (only one of which is labeled for clarity), multiple strap supplies 600 (only one of which is labeled for clarity), multiple input chutes 700 (only one of which is labeled for clarity), a width sensor SI, a height sensor S2, and a controller 800.

[0019] The frame 100 is configured to support some of the components of the strapping system 10. In this example embodiment, the frame 100 includes a base 110, first and second spaced-apart upstanding legs 120 and 130, and a connector 140 that spans and connects the upper ends of the first and second legs 120 and 130. Although not labeled, the first and second legs 120 and 130 each include a vertically extending toothed rack to enable the platen 300 to move relative to the first and second legs 120 and 130 in a rack-and-pinion fashion, as described below. This is merely one example of a configuration of components that form the frame 100, and any other suitable configuration of any other suitable components may form the frame 100 in other embodiments.

[0020] The load supporter 200 is positioned atop the base 110, between the first and second legs 120 and 130, and below the connector 140 of the frame 100. The load supporter 200 is configured to support loads as they are compressed and strapped by and as they move through the strapping system 10. The load supporter 200 includes a support surface 210 on which the loads are positioned during compression and strapping and over which loads move as they move through the strapping system 10. In this example embodiment, the support surface 210 includes multiple rollers that facilitate movement of the load through the strapping system 10. The rollers may be driven or undriven. In other embodiments, the support surface includes a driven conveyor instead of rollers.

[0021] The platen 300 is supported by the first and second legs 120 and 130 above the load supporter 200 and is vertically movable relative to the load supporter 200 so the platen 300 can adjust to loads of different heights and apply a compressive force to the loads. In thisexample embodiment, the platen 300 includes two rotatable pinions (not shown) fixed to opposite ends of a pinion shaft 305 such that the pinions and the pinion shaft 305 rotate together. The pinion shaft 305 extends between the first and second legs 120 and 130 such that one pinion meshes with the toothed rack in the first leg 120 and the other pinion meshes with the toothed rack in the second leg 130. In this configuration, rotation of the pinions (which rotate together via their fixed connection to the pinion shaft 305) under control of the platen actuator 350 (described below) causes the pinions to climb or descend their respective toothed racks such that the platen 300 moves away from or toward the support surface 210 of the load supporter 200 (i.e., upward or downward, as described in more detail below). The platen 300 also includes one or more compression surfaces 310 on its underside for engaging and applying the compressive force to the load.

[0022] The platen actuator 350 includes any suitable actuator — such as an electric, pneumatic, or hydraulic motor — operably connected to the platen 300 and configured to move the platen 300 relative to the first and second legs 120 and 130 toward and away from the support surface 210 of the load supporter 200 (i.e., downward and upward). In this example embodiment, the platen actuator 350 is operably connected to the pinions and the pinion shaft 305 of the platen 300 via gearing such that rotation of an output shaft of the platen actuator 350 results in rotation of the pinion shaft 305 and the pinions and vertical movement of the platen 300. In one example embodiment, an output gear of the gearing is meshed with one of the pinions such that rotation of the output gear caused by rotation of the output shaft of the platen actuator 350 directly causes that pinon to rotate, which in turn causes the pinion shaft 305 and the other pinion to rotate. Rotating the output shaft of the platen actuator 350 in one direction results in movement of the platen 300 away from the support surface 210, and rotation of the output shaft in the opposite direction results in movement of the platen 300 toward the support surface 210. This is merely one example embodiment of the platen actuator, and any suitable actuator may be employed. Additionally, any other suitable manner of controlling vertical movement of the platen 300 may be employed (e.g., hydraulic or pneumatic cylinders, belt-and- pulley assemblies, and the like), as the rack-and-pinion configuration is merely one example embodiment.

[0023] Each strap chute 400 encircles the support surface 210 and defines a strap path that the strap traverses when fed into and through the strap chute 400 and from which thestrap is removed when retracted onto the load. As shown in Figure 3, the strap chute 400 includes spaced-apart first and second upstanding legs 410 and 420, an upper connecting portion 430 that spans the first and second legs 410 and 420 and is positioned in the platen 300, and a lower connecting portion 440 that spans the first and second legs 410 and 420 and is positioned in the load supporter 200. The strap chute 400 includes a first comer Cl at the junction of the first leg 410 and the upper connecting portion 430, a second comer C2 at the junction of the first leg 410 and the lower connecting portion 440, a third corner C3 at the junction between the second leg 420 and the lower connecting portion 440, and a fourth corner C4 at the junction between the second leg 420 and the upper connecting portion 430.

[0024] A strapping area is defined between the load supporter 200 and the platen 300 and is encircled by the strap chute 400. In this example embodiment, the radially inward walls of the strap chute 400 are formed from multiple gates that are spring biased to a closed position that enables the strap to traverse the strap path when fed through the strap chute 400. When the strapping head 500 later exerts a sufficient pulling force on the strap to retract the strap, the pulling force overcomes the biasing force of the springs and causes the gates to pivot to an open position, thereby releasing the strap from the strap chute so the strap engages the load as the strapping head 500 continues to retract the strap. In other embodiments, the radially inward walls of the strap chute are configured to be actively opened, such as under control of a suitable actuator.

[0025] Each strapping head 500 is configured to form a tensioned strap loop around the load by feeding the strap through one of the strap chutes 400, holding the leading end of the strap while retracting the strap to remove it from the strap chute 400 so it engages the load, tensioning the strap around the load to a designated tension, connecting the leading strap end to another portion of the strap, and cutting the strap from the strap supply. In this example embodiment, the strapping head 500 is a modular strapping head including independently removable and replaceable feed, tensioning, and sealing assemblies 510, 520, and 530. The strapfeeding assembly 510, which is configured to feed and retract the strap, and the strap-tensioning assembly 520, which is configured to tension the strap, are mounted to a frame of the strap supply 600. The platen 300 supports the strap-sealing module 530, which is configured to hold the leading strap end, cut the strap from the strap supply, and connect two portions of the strap to one another. That is, in this example embodiment, the strap-feeding and strap-tensioningassemblies 510 and 520 are located remote from the strap-sealing assembly 530 (though in other embodiments the strap-feeding and / or strap-tensioning assemblies 510 and 520 may be supported by the frame 100, the platen 300, or any other suitable component of the strapping system 10). In this example embodiment, each strapping head is associated with and configured to feed strap into a different one of the strap chutes.

[0026] This is merely one example strapping head, and the strapping system 10 may include any suitable modular strapping head or non-modular strapping head (i.e., a strapping head that is not comprised of independently removable and replaceable feed and sealing modules). The manner of attaching the two portions of the strap to one another depends on the type of strapping machine and the type of strap. Certain strapping systems configured for plastic strap or paper strap include strapping heads with friction welders, heated blades, or ultrasonic welders configured to attach the two portions of the strap to one another. Some strapping systems configured for plastic strap or metal strap include strapping heads with jaws that mechanically deform (referred to as “crimping” in the industry) or cut notches into (referred to as “notching” in the industry) a seal element positioned around the two portions of the strap to attach them to one another. Other strapping systems configured for metal strap include strapping heads with punches and dies configured to form a set of mechanically interlocking cuts in the two portions of the strap to attach them to one another (referred to in the strapping industry as a “sealless” attachment). Still other strapping systems configured for metal strap include strapping heads with spot, inert-gas, or other welders configured to weld the two portions of the strap to one another.

[0027] Each strap supply 600 includes a suitable frame (not labeled) that supports the strap-feeding assembly 510 and the strap-tensioning assembly 520 of the associated strapping head 500 along with a coil of strap.

[0028] Each inlet chute 700 connects the strap-feeding assembly 510 of one of the strapping heads 500 to the strap chute 400 associated with that strapping head 500. In this example embodiment, each inlet chute 700 is a flexible tubular member that has an arch shape and defines a strap path between the strap-feeding assembly 510 and the strap-sealing assembly 530 of the associated strapping head 500.

[0029] The width sensor SI, which is shown in Figure 4, is configured to detect a width of a load to-be-strapped by the strapping system 10. Similarly, the height sensor S2, which is also shown in Figure 4, is configured to detect a height of a load to-be-strapped by thestrapping system 10. The width and height sensors SI and S2 may be any suitable sensors, such as (but not limited to) laser sensors, ultrasonic sensors, or optical sensors. In other embodiments, the strapping system 10 includes only one or none of the height and width sensors. In these embodiments, the strapping system 10 is configured to receive the height and / or the width of each load (as the case may be) from an external component, such as an inventory management system.

[0030] The controller 800 includes a processing device or devices communicatively connected to a memory device or devices. For instance, the controller may be a programmable logic controller. The processing device may include any suitable processing device such as, but not limited to, a general-purpose processor, a special-purpose processor, a digital-signal processor, one or more microprocessors, one or more microprocessors in association with a digital-signal processor core, one or more application-specific integrated circuits, one or more field-programmable gate array circuits, one or more integrated circuits, and / or a state machine. The memory device may include any suitable memory device such as, but not limited to, readonly memory, random-access memory, one or more digital registers, cache memory, one or more semiconductor memory devices, magnetic media such as integrated hard disks and / or removable memory, magneto-optical media, and / or optical media. The memory device stores instructions executable by the processing device to control operation of the strapping system 10.

[0031] The controller 800 is communicatively and operably connected to the platen actuator 350 and the strapping heads 500 to receive signals from and to control those components and is communicatively connected to the width sensor SI and the height sensor S2 to receive signals from those components. As described below, the controller 800 is configured to control the platen actuator 350 and the strapping heads 500.

[0032] In various embodiments, the controller 800 is configured to control the strapping heads 500 to carry out a strapping process that generally includes a strap-feeding cycle, a strap-retraction cycle, a strap-tensioning cycle, and a strap-sealing cycle. The controller 800 is configured to — either during or after completion of the strap-retraction cycle depending on the embodiment — determine whether a validation condition is met before initiating the straptensioning cycle. If the validation condition is met, the strap has been adequately retracted from the strap chute and onto the load, and the controller initiates the strap-tensioning cycle to continue the strapping process. But if the validation condition is not met, the strap has not beenadequately retracted from the strap chute, and the controller causes a fault indication to be output and stops the strapping process. Requiring the validation condition to be met before starting the strap-tensioning cycle improves upon certain prior art strapping machines because it enables the strapping system to recognize when strap gets stuck in the strap chute or is otherwise inadequately retracted or tensioned and prevents the strapping system from forming loose straps around the load.

[0033] In this example embodiment, the validation condition is met when an amount of unretracted strap is substantially similar to the perimeter of the load. In this example embodiment, the amount of unretracted strap is substantially similar to the perimeter of the load when the amount of unretracted strap is no more than 10% different from the perimeter of the load, though this percentage may differ in other embodiments.

[0034] The controller 800 is configured to determine the perimeter of the load based on feedback from the width sensor SI and the height sensor S2. Specifically, for rectangular loads, the controller 800 is configured to determine the perimeter of the load by determining the sum of twice the height of the load and twice the width of the load. This is merely one example embodiment, and the controller may determine the perimeter of the load in any suitable manner. In further embodiments, the controller is not configured to determine the perimeter of the load but is configured to receive the perimeter of the load from an external component, such as an inventory management system. In certain embodiments, the perimeter of the load after compression is used, whereas in other embodiments the perimeter of the load before compression is used.

[0035] The amount of unretracted strap is equal to the difference between an amount of fed strap, which is the amount of strap fed into the strap chute during the strap-feeding cycle, and an amount of retracted strap, which is the amount of strap retracted during the strapretraction cycle. In this example embodiment, the controller 800 uses feedback from an encoder of the strap-feeding assembly 510 to determine the amount of fed strap and the amount of retracted strap. Specifically, the strap-feeding assembly 510 includes a motor configured to drive a drive wheel. A freely rotatable pinch wheel is biased into engagement with the drive wheel, and the strap extends through the nip between the drive and pinch wheels. In operation, the motor drives the drive wheel in one direction to feed the strap and the opposite direction to retract the strap. Movement of the strap in either direction results in commensurate rotation ofthe pinch wheel. In this example embodiment, the encoder monitors rotation of the pinch wheel. Because the diameter of the pinch wheel is fixed, each rotation of the pinch wheel detected by the encoder corresponds to a particular distance the leading strap end LE has moved through the strap chute 540. The controller uses this information to calculate how much strap has been fed into the strap chute 540 and retracted from the strap chute 540 during the strap-feeding and strapretraction cycles.

[0036] Operation of the strapping system 10 to carry out a strapping process 1000 is now described in conjunction with the flowchart shown in Figure 5 and the example embodiment of the strapping system shown in Figures 6A-6D.

[0037] Before the strapping process 1000 begins in this example embodiment, a load LI is introduced into the strapping system 10. In this example embodiment, the load LI is moved to the strapping area of the strapping system 10, as shown in Figure 6A. The load LI has a width W detected by the width sensor SI and a height H detected by the height sensor S2, which enables the controller 800 to determine the perimeter of the load LI as being equal to (2xH) + (2xW). The controller 800 also controls the platen actuator 350 to begin moving the platen 300 toward the support surface 210 and, eventually, stops the platen 300 after the platen 300 contacts the load LI. In certain embodiments, the controller 800 monitors the amount of compressive force the platen 300 applies to the load LI, such as via a compression sensor, and stops the platen 300 once the applied compressive force reaches a predefined value. In other embodiments, the controller 800 monitors the position of the platen 300, such as via a distance sensor, and stops the platen 300 once the platen 300 is a predetermined distance above the support surface 210. Figure 6B shows the strapping system 10 after the platen 300 has engaged the load LI and stopped descending.

[0038] The strapping process 1000 begins by feeding strap from a strap supply into and around a strap chute that encircles a load on a support surface, as block 1002 indicates. In this example embodiment, the controller 800 controls the strapping head 500 to carry out the strap-feeding cycle. Specifically, the controller 800 controls the strap-feeding assembly 510 to begin feeding strap S leading strap end LE first through the input chute 700, through the strapsealing assembly 530, and into and around the strap chute 400 until the leading strap end LE returns to the strap sealing assembly 530. When this occurs, the controller 500 controls the strapsealing assembly 530 to hold the leading strap end LE and controls the strap-feeding assembly510 to stop feeding the strap S, thereby completing the strap-feeding cycle. Figure 6C shows the strapping system 10 after the strap-feeding cycle has been completed. As explained above, the controller 800 determines the amount of fed strap for the strap-feeding cycle.

[0039] The strapping process 1000 continues by starting to retract the strap, as block 1004 indicates, and afterwards stopping retraction of the strap, as block 1006 indicates. In this example embodiment, the controller 800 controls the strap-feeding assembly 510 to retract the strap S so that it exits the strap chute 400 and moves radially inwardly and engages the load LI. The controller 800 stops retracting the strap when a termination condition is met, which in this example embodiment occurs when the pinch wheel of the strap-feeding assembly 510 stops rotating, which occurs when the tension in the strap exceeds the retraction force generated by the drive wheel. Figure 6D shows the strapping system 10 after the strap-retraction cycle has been completed. In this example embodiment, the strap is stuck in the fourth corner C4 of the strap chute 400. As explained above, the controller 800 determines the amount of retracted strap for the strap-retraction cycle.

[0040] The strapping process 1000 continues by determining whether a validation condition has been met based on a perimeter of the load, as diamond 1008 indicates. If the validation condition is met, the strapping process 1000 concludes by tensioning the strap, as block 1010 indicates, and attaching two portions of the strap to one another to form a tensioned strap loop around the load and separating the tensioned strap loop from the strap supply, as block 1016 indicates. If, on the other hand, the validation condition is not met, the strapping process 1000 concludes by outputting a fault indication, as block 1014 indicates.

[0041] In this example embodiment, as explained above, the controller 800 determines the amount of unretracted strap, compares the amount of unretracted strap to the perimeter of the load LI, and determines that the validation condition is met only if the amount of unretracted strap is substantially similar to the perimeter of the load LI. In the scenario shown in Figure 6D in which the strap is stuck at the fourth comer C4 of the strap chute 400 during the strap-retraction cycle, the controller 800 determines that the validation condition is not met because the amount of unretracted strap is more than 10% greater than the perimeter of the load LI and controls an output device (such as a speaker or a screen) to output a fault indication.

[0042] Operation of the strapping system 10 to carry out another strapping process 2000 is now described in conjunction with the flowchart shown in Figure 7. The strappingprocess 2000 differs from the strapping process 1000 in that the controller continuously monitors whether the validation condition is met during the strap-retraction cycle rather than after completion of the strap-retraction cycle.

[0043] The strapping process 2000 begins by feeding strap from a strap supply into and around a strap chute that encircles a load on a support surface, as block 2002 indicates. The strapping process 2000 continues by starting to retract the strap, as block 2004 indicates, and starting a retraction timer, as block 2006 indicates. In this example embodiment, the controller 800 controls the strap-feeding assembly 510 to start retracting the strap S and starts a five-second retraction timer (though any suitable value may be employed). The strapping process 2000 continues by determining whether a validation condition has been met based on a perimeter of the load, as diamond 2008 indicates. If the validation condition is met, the strapping process 2000 concludes by stopping retraction of the strap, as block 2010 indicates; tensioning the strap, as block 2012 indicates; and attaching two portions of the strap to one another to form a tensioned strap loop around the load and separating the tensioned strap loop from the strap supply, as block 2014 indicates.

[0044] If, on the other hand, the validation condition is not met, the strapping process 2000 continues by determining whether the time period tracked by the retraction timer has expired, as diamond 2016 indicates. If the time period tracked by the retraction timer has not expired, the strapping process 2000 continues by returning to diamond 2008. If, on the other hand, the time period tracked by the retraction timer has expired, the strapping process 2000 concludes by stopping retraction of the strap, as block 2018 indicates, and outputting a fault indication, as block 2020 indicates.

Claims

Claims1. A strapping system comprising: a strap chute encircling a strapping area; a strapping head; and a controller configured to: control the strapping head to feed strap from a strap supply into and around the strap chute so the strap encircles a load in the strapping area; control the strapping head to start retracting the strap; determine whether a validation condition is met based on a perimeter of the load; and if the validation condition is met, control the strapping head to tension the strap around the load and to attach two portions of the strap to one another to form a tensioned strap loop around the load.

2. The strapping system of claim 1, wherein the controller is further configured to determine whether the validation condition is met based on a comparison between an amount of unretracted strap and the perimeter of the load.

3. The strapping system of claim 2, wherein the controller is further configured to determine that the validation condition is met when the amount of unretracted strap is substantially equal to the perimeter of the load.

4. The strapping system of claim 3, wherein the amount of unretracted strap is substantially equal to the perimeter of the load when the amount of unretracted strap is no more than 10% different from the perimeter of the load.

5. The strapping system of claim 2, wherein the controller is further configured to determine the amount of unretracted strap by determining a difference between an amount of fed strap and an amount of retracted strap.

6. The strapping system of claim 5, wherein the controller is further configured to: determine the amount of fed strap based on feedback from one or more sensors while strap is being fed into and around the strap chute; and determine the amount of retracted strap based on feedback from the one or more sensors while strap is being retracted.

7. The strapping system of claim 6, wherein the one or more sensors comprise one or more encoders.

8. The strapping system of claim 2, wherein the controller is further configured to determine the perimeter of the load based on a height of the load and a width of the load.

9. The strapping system of claim 8, further comprising a sensor communicatively connected to the controller and configured to sense the height of the load one of before the load is compressed and after the load is compressed.

10. The strapping system of claim 2, wherein the controller is further configured to control the strapping head to stop retracting the strap before determining whether the validation condition is met.

11. The strapping system of claim 2, wherein the controller is further configured to control the strapping head to stop retracting the strap responsive to determining that the validation condition is met.

12. The strapping head of claim 11, wherein the controller is further configured to, if the validation condition is not met within a designated period after starting to retract the strap: control the strapping head to stop retracting the strap; and cause a fault indication to be output.

13. The strapping system of claim 1, wherein the controller is further configured to, if the validation condition is not met, cause a fault indication to be output.

14. A method of operating a strapping system, the method comprising: feeding strap from a strap supply into and around a strap chute encircling a load in a strapping area; start retracting the strap; determining that a validation condition is met based on a perimeter of the load; and responsive to determining that the validation condition is met, tensioning the strap around the load and attaching two portions of the strap to one another to form a tensioned strap loop around the load.

15. The method of claim 14, further comprising determining that the validation condition is met based on a comparison between an amount of unretracted strap and the perimeter of the load.

16. The method of claim 15, further comprising determining that the validation condition is met responsive to determining that the amount of unretracted strap is substantially equal to the perimeter of the load.

17. The method of claim 16, wherein the amount of unretracted strap is substantially equal to the perimeter of the load when the amount of unretracted strap is no more than 10% different from the perimeter of the load.

18. The method of claim 15, further comprising determining the amount of unretracted strap by determining a difference between an amount of fed strap and an amount of retracted strap.

19. The method of claim 18, further comprising: determining the amount of fed strap based on feedback from one or more sensors while strap is being fed into and around the strap chute; and determining the amount of retracted strap based on feedback from the one or more sensors while strap is being retracted.

20. The method of claim 15, further comprising stop retracting the strap one of before determining that the validation condition is met; and responsive to determining that the validation condition is met.

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