Strapping machine configured to pre-feed strap

Abstract

Various embodiments of the present disclosure provide a strapping machine (1) configured to feed strap (S) around at least part of a strap chute (40) before a load (L) to-be-strapped reaches a strapping area circumscribed by the strap chute (40).

Description

STRAPPING MACHINE CONFIGURED TO PRE-FEED STRAPPriority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 504,847, filed May 30, 2023, 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 circumscribes 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 straptensioning 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, and the strap-sealing assembly is configured to attach two portions of the strap together to form the tensioned strap loop and to cut the strap from the strap supply. 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 strap-feeding process, a strap-retraction process, a strap-tensioning process, and a strap-sealing process. The strapping machine first carries out the strap-feeding process during which the strap-feeding assembly feeds strap (with the leading strap end first) from the strap reservoir through the strap-tensioning assembly, through the strap-feeding assembly, through the strap-sealing assembly, and into and around the strap chute until the leading strap end returns to the strap-sealing assembly. The strapping machine then carries out the strap-retraction process 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 and to push the excess strap back into the strap reservoir. The strapping machine then carries out the strap-tensioning process during which the strap-tensioning assembly tensions the strap to a designated strap tension. The strapping machine then carries out the strap-sealing process during which the strap-sealing assembly attaches the leading strap end to another portion of the strap to form a strap joint and cuts the strap from the strap supply, thereby forming a tensioned strap loop around the load.

[0005] Press-type strapping machines are configured to apply a compressive force to the load to partially compress the load — such as to partially compress a stack of flattened corrugated sheets — and / or to stabilize the load — such as to stabilize a load of stacked 2x4 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. 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.

[0006] Figures 1A-1F show a simplified illustration of a known press-type strapping machine 1 carrying out this strapping process. First, 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 then descends intoengagement with the load L and partially compresses the load L, as shown in Figure IB. The strapping machine 1 then carries out the strap-feeding process by controlling a strap-feeding assembly to feed strap S through a strap chute 40 and controlling a strap-sealing assembly 50 to hold the leading end of the strap once it traverses the strap chute 40 and returns to the strapsealing assembly 50, as shown in Figure 1C. The strapping machine 1 then carries out the strapretraction process 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 then carries out the strap-tensioning process by controlling the strap-tensioning assembly to tension the strap S to a designated tension. The strapping machine 1 then carries out the strap-sealing process 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 strap S from the strap supply, as shown in Figure IE. The platen 30 then ascends and disengages the load L, as shown in Figure IF, completing the strapping process.

[0007] In integrated packaging lines, loads are conveyed from one machine to another to prepare them for shipment before being conveyed to the end of the line where they are loaded into a truck or container. To maximize throughput, the time each load spends idle — i.e., not moving down the line — must be minimized. Since a load is idle when being strapped, there is a continuing need to minimize the idle time of the load in the strapping machine.Summary

[0008] Various embodiments of the present disclosure provide a strapping machine configured to feed strap around at least part of a strap chute before a load to-be-strapped reaches a strapping area circumscribed by the strap chute.Brief Description of the Figures

[0009] Figures 1A-1F are simplified elevational views of an example known strapping machine compressing and strapping a load.

[0010] Figure 2 is a perspective view of one example embodiment of a strapping machine of the present disclosure.

[0011] Figure 3 is a block diagram showing certain components of the strapping machine of Figure 2.

[0012] Figure 4 is a flowchart showing a method of operating the strapping machine of Figure 2 to carry out a strapping process.

[0013] Figures 5A-5G are simplified elevational views of the strapping machine of Figure 2 carrying out the strapping process of Figure 4.Detailed Description

[0014] 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 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.

[0015] Figures 2 and 3 show one example embodiment of a press-type strapping machine 10 of the present disclosure and components thereof. The strapping machine 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) each configured to draw strap from a respective strap supply 600 (only one of which is labeled for clarity), and a controller 700.

[0016] The frame 100 is configured to support some or all of the other components of the strapping machine 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.

[0017] 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 machine 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 machine 10. In this example embodiment, the support surface 210 includes multiple rollers that facilitate movement of the load through the strapping machine 10. The rollers may be driven or undriven. In other embodiments, the support surface includes a driven conveyor instead of rollers.

[0018] 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 this example embodiment, the platen 300 includes two rotatable pinions (not shown) fixed to 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.

[0019] The platen actuator 350 is 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.

[0020] Each strap chute 400 circumscribes the support surface 210 and defines a strap path that the strap follows when fed through the strap chute 400 and from which the strap is removed when retracted onto the load. As shown in Figure 5A, 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. A strapping area is defined between the load supporter 200 and the platen 300 and is circumscribed 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 inwardwalls of the strap chute are configured to be actively opened, such as under control of a suitable actuator.

[0021] The strapping head 500 is configured to form a tensioned strap loop around the load by feeding the strap through the strap chute 400, holding the leading strap end 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 strap-feeding 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. 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 be supported by the frame 100, the platen 300, or any other suitable component of the strapping machine 10). 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. A strap guide 540 extends between the strap-feeding and strap-tensioning assemblies 510 and 520 and the strap-sealing sealing assembly 530 and is configured to guide the strap as it moves between the assemblies.

[0022] This is merely one example strapping head, and the strapping machine 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 machines 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 machines 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 machines configured for metal strap includestrapping 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 machines 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.

[0023] The controller 700 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 machine 10.

[0024] The controller 700 is communicatively and operably connected to the platen actuator 350 and the strapping head 500 to receive signals from and to control those components. As described below, the controller 700 is configured to control the platen actuator 350 and the strapping head 500.

[0025] Operation of the strapping machine 10 to carry out a strapping process 1000 to strap a load L is now described in conjunction with the flowchart shown in Figure 4 and the example embodiment of the strapping machine shown in Figures 5A-5G. The strapping machine 10 is configured to pre-feed strap into the strap chute by carrying out at least part of the strapfeeding process before or while the load is being moved beneath the platen, which decreases the idle time of the load in the strapping machine, thereby increasing throughput.

[0026] The strapping process 1000 begins by feeding strap around a strap chute that circumscribes a support surface, as block 1002 indicates. This step begins and in certain embodiments is completed before the load reaches the strapping area of the strapping machine. In this example embodiment, the controller 700 controls the strapping head 500 to carry out thestrap-feeding process. Specifically, the controller 700 controls the strap-feeding assembly 510 to feed strap S around the strap chute 400 and controls the strap-sealing assembly 530 to hold the leading end of the strap S after it traverses the strap chute 400 and returns to the strap-sealing assembly 530. Figure 5A shows the strapping machine 10 after the strap-feeding process has been completed.

[0027] The strapping process 1000 continues by moving a load to a strapping area that is between the support surface and a platen and that is circumscribed by the strap chute, as block 1004 indicates. In this example embodiment, the load L is moved to the strapping area of the strapping machine 10 and reaches the strapping area after the strap-feeding process has completed, though in other embodiments the load reaches the strapping area after the strapfeeding process has started but before it has completed. Figure 5B shows the strapping machine 10 after the load L has reached the strapping area.

[0028] The strapping process 1000 continues by moving the platen toward the support surface while retracting the strap such that at least part of the strap remains in the strap chute, as block 1006 indicates. Retracting the strap while the platen descends prevents excess slack strap from accumulating in the strap chute or the strap-sealing assembly, which can cause the strap to deform, jam, or prematurely exit the strap chute. Retracting the strap while ensuring it does not exit the strap chute prevents the strap from being damaged, such as by being stuck between the platen and the load and deformed or broken when the platen engages the load. In this example embodiment, the controller 700 controls the platen actuator 350 to begin moving the platen 300 toward the support surface 210 while simultaneously controlling the strap-feeding assembly 510 to retract the strap at a rate that prevents the strap from exiting the strap chute. For instance, in this example embodiment, the strap is retracted at twice the speed at which the platen descends since the strap must be removed from the first and second legs 410 and 420 of the strap chute. Figure 5C shows the strapping machine 10 as the platen 300 is descending toward the load L and the strap is being retracted.

[0029] The strapping process 1000 continues by stopping the platen after the platen engages the load, as block 1008 indicates. In certain embodiments, the controller monitors the amount of compressive force the platen applies to the load, such as via a compression sensor, and stops the platen once the applied compressive force reaches a predefined threshold. In other embodiments, the controller monitors the position of the platen, such as via a distance sensor,and stops the platen once the platen is a predetermined distance above the support surface. In this example embodiment, after the platen 300 engages the load L, the controller 700 controls the platen actuator 350 to stop moving the platen 300. Figure 5D shows the strapping machine 10 after the platen 300 has engaged the load L and stopped descending.

[0030] 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 1010 indicates; tensioning the strap around the load, as block 1012 indicates; and attaching two portions of the strap to one another to form a tensioned strap loop around the load, as block 1014 indicates. In this example embodiment, the controller 700 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 L. Figure 5E shows the strapping machine 10 after the strap S has exited the strap chute 400 and engaged the load L. The controller 700 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 L. Figure 5F shows the strapping machine 10 after the strap S has been tensioned, sealed, and cut to form the tensioned strap loop TSL.

[0031] The strapping process continues by moving the platen away from the support surface, as block 1016 indicates. In this example embodiment, the controller 700 controls the platen actuator 350 to move the platen 300 away from the support surface 210 so the platen 300 disengages the load L. Figure 5G shows the strapping machine 10 after the platen 300 has disengaged the load L The strapping process concludes by moving the load out of the strapping area after the platen disengages the load, as block 1018 indicates.

[0032] As explained above, there is a continuing need to minimize the time a load remains idle at a strapping machine. The strapping machine and strapping process of the present disclosure shorten the idle time of a load at the strapping machine as compared to certain existing strapping machines and strapping processes. Specifically, in the known strapping machine and process described in the Background, once the load reaches the strapping area it remains idle while the platen descends and the strap is fed, retracted, tensioned, sealed, and cut. In the strapping machine and strapping process of the present disclosure, carrying out the strap-feeding process before the load reaches the strapping area eliminates the need for the load to sit idle while this step is carried out. The load only remains idle as the platen descends and the strap isretracted, tensioned, sealed, and cut since the strap has been pre-fed into the strap chute before the load reaches the strapping area and the platen begins descending. This shortens the idle time of the load at the strapping machine by the time it takes to complete the strap-feeding process.

[0033] This benefit is compounded in cases of a strap misfeed. In certain instances, the strap-feeding process is not successful in that the leading end of the strap never reaches the strap-sealing assembly. When this occurs, the strap-feeding assembly retracts the strap from the strap chute and re-feeds the strap. In certain known strapping machines and strapping processes, such as the one described in the Background section, this retraction and refeeding occurs while the load is idle at the strapping machine, further lengthening the idle time of the load and slowing the packaging line. The strapping machine and the strapping process of the present disclosure solve this problem. Since the strap-feeding process occurs before the load reaches the strapping area, the recognition of a misfeed and the retraction and refeeding also occurs before the load reaches the strapping area. This prevents the misfeed from lengthening the idle time of the load at the strapping machine and prevents a bottleneck in the packaging line.

[0034] In certain embodiments, after the controller controls the strapping head to form the tensioned strap loop around the load, the controller controls the platen actuator to move the platen back upward to a home position to await the next load. In some of these embodiments, the controller controls the strapping head to carry out the strap-feeding cycle to pre-feed the strap around the strap chute as soon as the platen reaches the home position. In other embodiments, the controller controls the platen actuator to move the platen to a height that is slightly greater than the height of the incoming load. For instance, the controller may receive the height of the incoming load from a central controller of the packaging line and move the platen accordingly.

[0035] In certain embodiments, the strap-feeding assembly is configured to retract the strap at a first speed as the platen is descending and a second speed greater than the first speed when retracting the strap from the strap chute so it engages the load.

Claims

Claims1. A strapping machine comprising: a frame; a platen supported by the frame; a load supporter below the platen, wherein a strapping area is defined between the load supporter and the platen; a platen actuator operably connected to the platen to move the platen toward and away from the load supporter; a strap chute circumscribing the strapping area; a strapping head; and a controller configured to: before a load is moved into the strapping area, control the strapping head to begin feeding strap from a strap supply into the strap chute; after the load has reached the strapping area, control the platen actuator to move the platen toward the load supporter and the load while controlling the strapping head to retract the strap such that at least part of the strap remains in the strap chute; and after the platen contacts the load, control the platen actuator to stop moving the platen and control the strapping head to form a tensioned loop of strap around the load.

2. The strapping machine of claim 1, wherein the controller is further configured to, before the load reaches the strapping area, control the strapping head to finish feeding the strap from the strap supply into the strap chute.

3. The strapping machine of claim 2, wherein the strapping head includes a strapfeeding assembly, a strap-tensioning assembly, and a strap-sealing assembly, wherein the controller is further configured to control the strap-feeding assembly to feed the strap from the strap supply into the strap chute and to control the strap-sealing assembly to hold a leading end of the strap after feeding is complete.

4. The strapping machine of claim 3, wherein the controller is further configured to control the strapping head to form the tensioned loop of strap around the load by: controlling the strap-feeding assembly to retract the strap such that it exits the strap chute and engages the load; controlling the strap-tensioning assembly to tension the strap to a designated tension; and controlling the strap-sealing assembly to attach two portions of the strap to one another and to cut the strap from the strap supply.

5. The strapping machine of claim 4, wherein the controller is further configured to control the strapping head to retract the strap such that at least part of the strap remains in the strap chute by controlling the strap-feeding assembly to retract the strap at a first speed.

6. The strapping machine of claim 4, wherein the controller is further configured to control the strap-feeding assembly to retract the strap at a second speed such that it exits the strap chute and engages the load, wherein the second speed is different from the first speed.

7. The strapping machine of claim 6, wherein the second speed is greater than the first speed.

8. A method of strapping a load, the method comprising: before the load has reached a strapping area of a strapping machine, begin feeding strap from a strap supply into a strap chute of the strapping machine; after the load has reached the strapping area, moving a platen toward the load while retracting the strap such that at least part of the strap remains in the strap chute; and after the platen contacts the load, stopping the platen and forming a tensioned loop of strap around the load.

9. The method of claim 8, further comprising finishing feeding the strap from the strap supply into the strap chute before the load reaches the strapping area.

10. The method of claim 9, further comprising feeding the strap from the strap supply into the strap chute via a strap-feeding assembly and holding a leading end of the strap after feeding is complete via a strap-sealing assembly.

11. The method of claim 10, wherein forming the tensioned loop of strap around the load comprises: retracting the strap such that it exits the strap chute and engages the load; tensioning the strap to a designated tension; attaching two portions of the strap to one another; and cutting the strap from the strap supply.

12. The method of claim 11, wherein retracting the strap such that at least part of the strap remains in the strap chute comprises retracting the strap at a first speed.

13. The method of claim 12, wherein retracting the strap such that it exits the strap chute and engages the load comprises retracting the strap at a second speed different form the first speed.

14. The method of claim 13, wherein the second speed is greater than the first speed.

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