Strapping machine with variable-speed strap-feeding cycle

Abstract

Various embodiments of the present disclosure provide a strapping system configured to feed strap into and around a strap chute initially at a first speed and then at a second slower speed after a slowdown condition is met.

Description

STRAPPING MACHINE WITH VARIABLE- SPEED STRAP-FEEDING CYCLEPriority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 655,177, filed June 3, 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 areconfigured 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 support surface 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] Certain known strapping machines include a sensor within the strap-sealing assembly that is configured to detect the leading strap end. In operation, the strap-feeding assembly feeds the strap at a fixed speed into and through the strap chute until the sensor detects the leading strap end, at which point the strap-feeding assembly stops feeding the strap. To reduce cycle time and increase throughput, the fixed speed is typically quite high, which can result in the leading strap end impacting a strap stop in the strap-sealing assembly before the strap-feeding assembly stops the strap from moving. This can damage the leading strap end, cause the part of the strap to deform within the strap chute, or cause part of the strap to exit the strap chute prematurely.Summary

[0009] Various embodiments of the present disclosure provide a strapping system configured to feed strap into and around a strap chute initially at a first speed and then at a second slower speed after a slowdown condition is met.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-6G are simplified elevational views of the strapping system of Figure 2 carrying out the strapping process of Figure 5.Detailed Description

[0016] 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 todirect mounting methods but should be interpreted broadly to include indirect and operably mounted, 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.

[0017] 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), and a controller 800.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] For a given strapping process, which is explained below with respect to Figure 5, the strap chute 400 has an effective length LEFF that is equal to the length of the strap chute 400 that the strap moves through and occupies during the strap-feeding cycle of that strapping process. As shown in Figures 3 and 6B, in this example the effective length LEFF of the strap chute 400 that is equal to the sum of: (1) a distance W1 that represents the length of the part of the upper connecting portion 430 between the point at which the strap enters the upper connecting portion 430 and the approximate center of the first corner Cl; (2) the effective height HEFF of the first leg 410 (explained below); (3) a distance W2 that represents the length of the lower connecting portion 440 between the approximate centers of the second and third corners C2 and C3; (4) the effective height HEFF of the second leg 420; and (5) the distance W3 that represents the length of the part of the upper connecting portion 430 between the point at which the leading strap end is held by the strap-sealing assembly 530 (explained below) and the middle of the fourth comer C4. In other words: LEFF = W1 + HEFF + W2 + HEFF + W3.

[0024] As noted above, the first and second legs 410 and 420 of each strap chute 400 have the same effective height HEFF as shown in Figures 3 and 6B. The effective height HEFF of the first leg 410 represents the length of the portion of the first leg 410 between the approximate centers of the first and second comers Cl and C2. The effective height HEFF of the second leg 420 represents the length of the portion of the second leg 420 between the approximate centers of the third and fourth corners C3 and C4. The effective height can change from load to load based on the height and compressibility of the loads. For instance, the effective height HEFF of the first and second legs 410 and 420 during the strapping process for a relatively tall, incompressible load is greater than the effective height HEFF of the first and second legs 410 and 420 during thestrapping process for a relatively short, compressible load. The distances Wl, W2, and W3 are fixed and do not change based on the height or compressibility of the load.

[0025] Since the effective height HEFF of the first and second legs 410 and 420 can vary from load to load, the effective length LEFF of the strap chute 400 can vary from load to load. For instance, the effective length LEFF of the strap chute 400 during the strapping process for a relatively tall, incompressible load is greater than the effective length LEFF of the strap chute 400 during the strapping process for a relatively short, compressible load.

[0026] 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.

[0027] 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-tensioning assemblies 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 besupported 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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 adigital-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.

[0032] 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. As described below, the controller 800 is configured to control the platen actuator 350 and the strapping heads 500.

[0033] 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-6G. The strapping system 10 is configured to reduce the speed at which strap is fed into and around the strap chute 400 during the strapfeeding cycle of the strapping process 1000 in response to a slowdown condition being met based at least in part on the effective length LEFF of the strap chute 400, which as explained below is based on the height of the load.

[0034] 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 strapping process 100 begins by lowering a platen into contact with a load on a strapping area of a support surface, as block 1002 indicates. In this example embodiment, the controller 800 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.

[0035] The strapping process 1000 continues by determining, based on a height of the load, an effective length of a strap chute that circumscribes the support surface, as block 1004 indicates. In this example embodiment, as explained above, the effective length LEFF of the strap chute 400 is equal to the sum of the first distance Wl, the effective height HEFF of the first leg 410, the second distance W2, the effective height HEFF of the second leg 420, and the third distance W3. As explained above, the first, second, and third distances Wl, W2, and W3 are fixed, and the effective height HEFF of the first and second legs 410 and 420 depends on and will vary with the height and compressibility of the load. In this example embodiment, the controller 800 is configured to determine the effective height HEFF of the first and second legs 410 and 420 in any suitable manner. For instance, in certain embodiments, the controller 800 does so based on feedback from a distance sensor configured to monitor the height of the one or more compression surfaces 310 of the platen 300 above the support surface 210. In other embodiments, the controller 800 does so via an encoder operably connected to the platen actuator 350 that enables the controller 800 to determine the absolute position of the platen 300 relative to the support surface 210. In other embodiments, the controller 800 determines the effective length of the strap chute after the platen 300 stops descending, whereas in other embodiments the controller does so before the platen 300 stops descending. In various embodiments, the controller 800 determine the effective length of the strap chute based on the height of the load, which may be determined via a suitable sensor, rather than based on the actual height of the platen after contacting the load.

[0036] The strapping process 1000 continues by feeding strap at a first speed from a strap supply into and around the strap chute, as block 1006 indicates. In this example embodiment, the controller 800 controls the strapping head 500 to begin carrying out the strapfeeding cycle. Specifically, the controller 800 controls the strap-feeding assembly 510 to begin feeding strap S leading strap end LE first at a substantially constant first speed through the input chute 700, through the strap-sealing assembly 530, and into upper connecting portion 430 such that the leading strap end LE travels toward the first corner Cl.

[0037] Strap continues to be fed at the first speed — with the leading strap end traversing the strap chute — until a slowdown condition is met based at least in part on the effective length of the strap chute, as diamond 1008 indicates. And as explained above, the effective length of the strap chute is itself determined by the height of the load. In this exampleembodiment, the controller 800 determines that the slowdown condition is met when the leading strap end LE reaches a slowdown point 400a that is approximately halfway between the fourth corner C4 of the strap chute 400 and the strap sealing assembly 530. Figure 6C shows the leading strap end LE positioned at the slowdown point 400a. The slowdown point may be at any other suitable position in other embodiments, such as (but not limited to) at the middle of the third corner C3, between the third and fourth corners C3 and C4, or at the middle of the fourth corner C4. In this example embodiment, the controller 800 uses feedback from an encoder of the strapfeeding assembly 510 to determine how much strap has been fed into the strap chute 400 and, therefore, the approximate position of the leading strap end LE. For instance, in this example embodiment, 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 to feed the strap, and this movement of the strap results in commensurate rotation of the 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 the position of the strap and to determine when the leading strap end LE has substantially reached the slowdown point 400a.

[0038] In other embodiments, a suitable sensor is positioned to detect the leading strap end when it reaches the slowdown point. In certain such embodiments, the sensor is automatically repositionable when the platen ascends and descends — and the slowdown point ascends and descends accordingly — so that the sensor can detect the leading strap end regardless of the vertical position of the slowdown point.

[0039] After the slowdown condition is met, the strapping process 1000 continues by feeding the strap at a second speed from the strap supply into the strap chute, the second speed being lower than the first speed, as block 1010 indicates. In this example embodiment, after the slowdown condition is met, which occurs before the leading strap end reaches the strap-sealing assembly 530, the controller 800 controls the strap-feeding assembly 510 to reduce the speed at which it is feeding the strap S to a substantially constant second speed that is lower than the first speed. In this example embodiment, the first speed is approximately 12 feet per second and the second speed is approximately 8 feet per second, though these may be any other suitable valuesin other embodiments. The controller 800 continues to control the strap-feeding assembly 510 to feed the strap at the second speed until the leading strap end LE reaches the strap sealing assembly 530. When this occurs, the controller 500 controls the strap-sealing assembly 530 to hold the leading strap end LE and controls the strap-feeding assembly 510 to stop feeding the strap S, thereby completing the strap-feeding cycle. Figure 6D shows the strapping system 10 after the strap-feeding cycle has been completed.

[0040] The strapping process 1000 continues by retracting the strap such that the at least part of the strap exits the strap chute and engages the load, as block 1012 indicates; tensioning the strap around the load, as block 1014 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. 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. Figure 6E shows the strapping system 10 after the strap S has exited the strap chute 400 and engaged the load LI. The controller 800 controls the strap-tensioning assembly 520 to tension the strap S around the load to a designated tension and controls the strap-sealing assembly 530 to attach two portions of the strap S to one another and to cut the strap S from the strap supply to form a tensioned strap loop TSL around the load LI and complete the strapping process. Figure 6F shows the strapping system 10 after the strap S has been tensioned, sealed, and cut to form the tensioned strap loop TSL. The strapping process 1000 concludes by moving the load out of the strapping area, as block 1018 indicates. In this example embodiment, the controller 800 controls the platen actuator 350 to raise the platen 300 until it disengages the load LI so the load LI can be moved out of the strapping system 10. Figure 6G shows the strapping system 10 after the load LI has been moved.

[0041] Reducing the feed at which the strapping head feeds strap after a slowdown condition has been met — and particularly when the leading strap end is nearing the fourth corner of the strap chute — solves the above problems by reducing the likelihood that the strap will be damaged or exit the strap chute prematurely upon reentry into the strap-sealing assembly without significantly lengthening cycle time.

Claims

Claims1. A strapping system comprising: a load supporter comprising a support surface defining a strapping area; a strap chute encircling the strapping area; a strap-sealing assembly adjacent the strap chute; a strap-feeding assembly; a strap-tensioning assembly; and a controller configured to: control the strap-feeding assembly to begin feeding strap at a first speed into the strap chute; responsive to a slowdown condition being met based at least in part on a height of a load on the support surface, control the strap-feeding assembly to continue feeding strap at a second speed into the strap chute, wherein the second speed is less than the first speed; control the strap-feeding assembly to retract the strap such that part of the strap exits the strap chute and engages the load; control the strap-tensioning assembly to tension the strap around the load; and control the strap-sealing assembly 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 slowdown condition is met when a leading strap end of the strap substantially reaches a slowdown point of the strap chute.

3. The strapping system of claim 2, wherein the controller is configured to determine when the leading strap end of the strap substantially reaches the slowdown point based on feedback from one or more sensors and based on the height of the load.

4. The strapping system of claim 3, wherein the one or more sensors comprise one or more encoders of the strap-feeding assembly.

5. The strapping system of claim 1, further comprising: a platen supported by the frame; and a platen actuator operably connected to the platen and configured to move the platen toward and away from the support surface, wherein the strap chute comprises an upstanding first leg, an upstanding second leg spaced-apart from the first leg, a substantially horizontal upper connecting portion supported by the platen and in communication with the first and second legs, and a substantially horizontal lower connecting portion supported by the load supporter and in communication with the first and second legs.

6. The strapping system of claim 5, wherein the controller is configured to determine an effective length of the strap chute based on an effective height of the first leg, an effective height of the second leg, a length of the upper connecting portion, and a length of the lower connecting portion, wherein the effective heights of the first and second legs are based on a distance between the platen and the support surface when the platen contacts the load, wherein the effective heights change as the distance between the platen and the support surface changes.

7. The strapping system of claim 6, wherein the slowdown condition is met when a leading strap end of the strap reaches a slowdown point of the strap chute.

8. The strapping system of claim 7, wherein the strap chute comprises a first corner between the upper connecting portion and an upper end of the first leg, a second comer between the lower connecting portion and a lower end of the first leg, a third corner between the lower connecting portion and a lower end of the second leg, and a fourth comer between the upper connecting portion and an upper end of the second leg, wherein the slowdown point is between the fourth corner and the strap-sealing assembly and is external to the strap-sealing assembly.

9. The strapping system of claim 8, wherein the controller is configured to determine when the leading strap end of the strap reaches the slowdown point based on feedback from one or more sensors and based on the effective length of the strap chute.

10. The strapping system of claim 8, wherein the controller is further configured to control the strap-feeding assembly to stop feeding strap into the strap chute responsive to the leading strap end reaching the strap-sealing assembly.

11. A method of operating a strapping system, the method comprising: begin feeding strap at a first speed into a strap chute; responsive to a slowdown condition being met based at least in part on a height of a load, continue feeding strap at a second speed into the strap chute, wherein the second speed is less than the first speed; thereafter, stop feeding strap into the strap chute; retracting the strap such that part of the strap exits the strap chute and engages a load on a support surface of a load supporter, the support surface circumscribed by the strap chute; 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.

12. The method of claim 11, further comprising determining that the slowdown condition has been met when a leading strap end of the strap substantially reaches a slowdown point of the strap chute.

13. The method of claim 2, further comprising determining when the leading strap end of the strap substantially reaches the slowdown point based on feedback from one or more sensors and based on the height of the load.

14. The method of claim 13, wherein the one or more sensors comprise one or more encoders of the strap-feeding assembly.

15. The method of claim 11, further comprising moving a platen into engagement with a top surface of the load, wherein the strap chute comprises an upstanding first leg, an upstanding second leg spaced-apart from the first leg, a substantially horizontal upper connecting portion supported by the platen and in communication with the first and second legs, and asubstantially horizontal lower connecting portion supported by the load supporter and in communication with the first and second legs.

16. The method of claim 15, further comprising determining an effective length of the strap chute based on an effective height of the first leg, an effective height of the second leg, a length of the upper connecting portion, and a length of the lower connecting portion, wherein the effective heights of the first and second legs are based on a distance between the platen and the support surface when the platen contacts the load, wherein the effective heights change as the distance between the platen and the support surface changes.

17. The method of claim 16, further comprising determining that the slowdown condition has been met when a leading strap end of the strap reaches a slowdown point of the strap chute.

18. The method of claim 17, wherein the strap chute comprises a first corner between the upper connecting portion and an upper end of the first leg, a second corner between the lower connecting portion and a lower end of the first leg, a third comer between the lower connecting portion and a lower end of the second leg, and a fourth corner between the upper connecting portion and an upper end of the second leg, wherein the slowdown point is between the fourth corner and a strap-sealing assembly and external to the strap-sealing assembly, wherein the strapsealing assembly is configured to attach the two portions of the strap to one another.

19. The method of claim 18, further comprising determining when the leading strap end of the strap reaches the slowdown point based on feedback from one or more sensors and based on the effective length of the strap chute.

20. The method of claim 18, wherein stop feeding strap into the strap chute comprises stop feeding strap into the strap chute responsive to the leading strap end reaching a strap-sealing assembly.

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