INCLUDING A STRAP- JOINT-VERIFICATION PROCESS

Priority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/376,675, filed September 22, 2022, the entire contents of which is incorporated herein by reference.

Field

[0002] The present disclosure relates to a strapping machine for bundling and unitizing loads of goods, and more particularly to a strapping machine configured to carry out a strapping process including a strap-joint-verification process.

Background

[0003] A strapping machine forms a tensioned loop of plastic strap (such as polyester or polypropylene strap), metal strap (such as steel strap), or paper strap around a load. A typical strapping machine includes a support surface that supports the load, a strap chute that circumscribes the support surface, a strapping head that forms the strap loop, a controller that controls the strapping head to strap the load, and a frame that supports these components. A typical strapping head includes a strap-feeding assembly for feeding strap from a strap supply into and around the strap chute and for retracting the strap so it exits the strap chute and moves radially inwardly into contact with the load, a strap-tensioning assembly for tensioning the strap around the load, and a strap-sealing assembly for cutting the strap from the strap supply and attaching two areas of the strap together to form the strap loop. The strapping machine includes several guides that define strap channels that the strap passes through as it moves between the various assemblies of the strapping head and the strap chute. The strap channels and the strap chute together define a strap path that the strap moves through.

[0004] To strap the load, the strapping machine carries out a strapping process including 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 supply through the strap-tensioning 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. 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 and completing the strapping process.

[0005] After the strap joint is formed in certain instances, the strap itself exerts a pulling force on the strap joint. This pulling force can be caused, for instance, by the load attempting to expand after being compressed before or during the strap-tensioning process and/or by the strap having been stretched during the strap-tensioning process and attempting to return to its unstretched state. Occasionally, this pulling force will cause a strap joint to fail shortly after formation. This could occur for a variety of reasons, including poor-quality strap, strap misalignment, worn mechanical components, and the like. A strap joint that unexpectedly fails requires additional time and material to re-strap the load and can cause damaged goods.

Summary

[0006] Various embodiments of the present disclosure provide a strapping machine configured to carry out a strapping process including a strap-joint-verification process. During the strapping process, the strapping machine is configured to carry out a strap-feeding process by feeding strap from a strap supply around a strap chute that surrounds the load, a strap-retraction process by pulling the strap out of the strap chute and onto and around the load, a straptensioning process by tensioning the strap around the load to a designated strap tension, and a strap-sealing process by attaching two portions of the strap to one another to form a strap joint. The strapping machine then carries out a strap-joint-verification process to determine whether the strap joint was satisfactorily formed.

Brief Description of the Figures

[0007] Figure 1 is a diagrammatic side view of one example embodiment of a strapping machine of the present disclosure.

[0008] Figure 2 is a perspective view of the strapping head of the strapping machine of Figure 1.

[0009] Figure 3 is a front elevational view of the strap-feeding and strap-tensioning assemblies of the strapping head of Figure 2.

[0010] Figure 4 is a block diagram showing certain of the components of the strapping machine of Figure 1.

[0011] Figure 5 is a flowchart of an example strapping process of the present disclosure carried out by the strapping machine of Figure 1.

[0012] Figures 6A-6G are cross-sectional front elevational views of part of the strap-sealing assembly of the strapping machine of Figure 1 during the strapping processes of Figures 5 and 8.

[0013] Figures 7A-7C are diagrammatic side views showing the failure of a strap joint during the strap-joint-verification process of the strapping process of Figure 5.

[0014] Figure 8 is a flowchart of another example strapping process of the present disclosure carried out by the strapping machine of Figure 1.

Detailed Description

[0015] 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.

[0016] Various embodiments of the present disclosure provide a strapping machine configured to carry out a strapping process including a strap-joint-verification process to determine whether the strap joint formed via the strapping process was satisfactorily formed. Figures 1-4 and 6A-6G show one example embodiment of a strapping machine 10 of the present disclosure and components thereof. The strapping machine 10 is configured to form a tensioned loop of strap drawn from a strap supply (not shown) around a load and includes a frame 100, a strap chute 150, a load supporter 200, a strapping head 300, and a controller 900.

[0017] The frame 100 supports some (or all depending on the embodiment) of the other components of the strapping machine 10 and may be formed of any suitable components arranged in any suitable configuration. The load supporter 200 is supported by the frame 100 and is sized, shaped, positioned, oriented, and otherwise configured to support loads — such as the load 50 shown in Figure 1 — as they are strapped by and as they move through the strapping machine 10. The load supporter 200 includes a support surface (not labeled) on which loads are positioned during strapping and over which loads move as they move through the strapping machine 10. In this example embodiment, the support surface includes multiple rollers that facilitate movement of the loads across the load supporter 200. The rollers may be driven or undriven. In other embodiments, the support surface includes any other suitable driven conveyor.

[0018] The strap chute 150 is supported by the frame 100 and circumscribes the support surface of the load supporter 200. The strap chute 150 defines a strap path that the strap follows when fed through the strap chute 150 and from which the strap is removed when retracted. The strap chute 150 includes two spaced-apart first and second upstanding legs (not labeled); an upper connecting portion (not labeled) that spans the first and second legs; a first lower connecting portion (not labeled) within or beneath the load supporter 200 that connects the strapping head 300 with the first upstanding leg; and a second lower connecting portion (not labeled) within or beneath the load supporter 200 that connects the strapping head 300 with the second upstanding leg. The radially inward wall of the strap chute 150 is formed from one or more gates that are spring biased to a closed position that enables the strap to traverse the strap path when fed through the strap chute 150. When the strap-feeding assembly 400 exerts a pulling force on the strap to retract the strap, the pulling force overcomes the biasing force of the springs and causes the gate(s) to pivot to an open position, thereby releasing the strap from the strap chute 150 so the strap moves radially inward into contact with the load. A leading-end sensor 905 communicatively connected to the controller 900 is positioned and otherwise configured to detect the leading end of the strap when the leading end has traversed the strap chute 150 and returned to the strapping head 300, as explained below.

[0019] The strapping head 300 is configured to carry out the strapping process, including the strap-joint-verification process. The strapping head 300 includes a head frame 305 mounted to the frame 100 and supporting a strap-feeding assembly 400, a strap-tensioning assembly 500, a strap-sealing assembly 600, and one or more guides G1 and G2.

[0020] The strap-feeding assembly 400 is configured to feed strap from the strap supply into and around the strap chute 150 and to, after the leading-end sensor 905 senses the leading end of the strap and the strap-sealing assembly 600 holds the leading end, retracts the strap so it exits the strap chute 150 and contacts the load 50. The strap-feeding assembly 400 includes a drive roller 410, a pinch roller 420, and a strap-feeding actuator 430. The drive roller 410 is cylindrical (here, disc-shaped) and is mounted to the head frame 305 so the drive roller 410 is rotatable relative to the head frame 305 about a drive-roller rotational axis. The pinch roller 420 is cylindrical (here, disc-shaped) and is mounted to the head frame 305 such that the pinch roller 420 is freely rotatable relative to the head frame 305 about a pinch-roller rotational axis. The drive roller 410 and the pinch roller 420 are sized, shaped, positioned, and oriented such that their respective rotational axes are generally parallel and coplanar. The pinch roller 420 is positioned adjacent the drive roller 410 such that a nip is formed between the two rollers. The nip is sized such that the strap S can be received in the nip and such that the drive roller 410 and the pinch roller 420 apply sufficient force to the strap S to enable the drive roller 410 to feed and retract the strap S around the load. In certain embodiments, at least part of the external cylindrical surface of the drive roller 410 and/or the pinch roller 420 is knurled or coated with a friction-enhancing material to facilitate engaging and dispensing the strap. [0021] The strap-feeding actuator 430, which is an electric motor in this example embodiment but may include any suitable actuator, is mounted to the head frame 305 and is operably connected to the drive roller 410 and configured to drive the drive roller 410 in opposing feed and retract rotational directions. The strap-feeding actuator 430 may be operably connected to the drive roller 410 in any suitable manner, such as via a keyed or splined connection and/or via a suitable drive train.

[0022] The strap-tensioning assembly 500 is configured to tension the strap around the load 50. The strap-tensioning assembly 500 includes a drive roller 510, a pinch roller 520, and a strap-tensioning actuator 530. The drive roller 510 is cylindrical (here, disc-shaped) and is mounted to the head frame 305 so the drive roller 510 is rotatable relative to the head frame 305 about a drive-roller rotational axis. The pinch roller 520 is cylindrical (here, disc-shaped) and is mounted to the head frame 505 such that the pinch roller 520 is freely rotatable relative to the head frame 305 about a pinch-roller rotational axis. The drive roller 510 and the pinch roller 520 are sized, shaped, positioned, and oriented such that their respective rotational axes are generally parallel and coplanar. The pinch roller 520 is also movable — under control of the strap-sealing drive assembly 690, described below — relative to the head frame 305 and the drive roller 510 between a tensioning position (Figure 3) and a spaced position (not shown). When the pinch roller 520 is in the tensioning position, the pinch roller 520 is adjacent the drive roller 510 such that a nip is formed between the two rollers. The nip is sized such that the strap S can be received in the nip and such that the drive roller 510 and the pinch roller 520 apply sufficient force to the strap S to enable the drive roller 510 to tension the strap S around the load. When the pinch roller 520 is in the spaced position, the pinch roller 520 is spaced-apart from the drive roller 510 such that the strap S can pass freely between the two rollers. In this example embodiment, the pinch roller 520 is in the spaced position except during the strap-tensioning process, during which the pinch roller 520 is in the tensioning position. In certain embodiments, at least part of the external cylindrical surface of the drive roller 510 and/or the pinch roller 520 is knurled or coated with a friction-enhancing material to facilitate engaging and dispensing the strap.

[0023] The strap-tensioning actuator 530, which is an electric motor in this example embodiment but may include any suitable actuator, is mounted to the head frame 305 and is operably connected to the drive roller 510 and configured to drive the drive roller 510 in a tensioning rotational direction (which is the same rotational direction as the retract rotational direction in this example embodiment). The strap-tensioning actuator 530 may be operably connected to the drive roller 510 in any suitable manner, such as via a keyed or splined connection and/or via a suitable drive train.

[0024] The strap-sealing assembly 600 is supported by the head frame 305 and configured to, after the strap-tensioning assembly 500 tensions the strap to the designated tension, attach two overlapping portions of the strap to one another and, after the strap-joint- verification process is complete, cut the strap from the strap supply. The manner of attaching the overlapping 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 or paper strap include a strapsealing assembly with a friction welder, a heated blade, or an ultrasonic welder configured to attach the overlapping portions of the strap to one another. Some strapping machines configured for plastic strap or metal strap include a strap-sealing assembly 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 overlapping portions of the strap to attach them to one another. Other strapping machines configured for metal strap include a strap-sealing assembly with punches and dies configured to form a set of mechanically interlocking cuts in the overlapping 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 a strap-sealing assembly with spot, inert-gas, or other welders configured to weld the overlapping portions of the strap to one another.

[0025] In this example embodiment, the strap-sealing assembly 600 includes a counter-pressure plate 610, a strap guide 620 having spaced-apart upper and lower portions 622 and 624 defining a channel (not labeled) therebetween and a leading-end stop 626, a first strap clamp 630 having a body 630b defining an opening 63 Oo therethrough and including a clamping surface 630s, a second strap clamp 640 having a body 640b including a clamping surface 640s, a third strap clamp 650 having a body 650b including a clamping surface 650s, a separator 660 having a body 660b and a cutting element 660c, a heating element 680, and a strap-sealing drive assembly 690 including a strap-sealing actuator 695 (which is an electric motor in this example embodiment but any other suitable actuator).

[0026] The strap-sealing drive assembly 690 is operably connected to certain components of the strap-sealing assembly 600 and the pinch roller 520 to move those components in certain ways to manipulate the strap during various phases of the strapping process and attach two overlapping portions of the strap to one another, as explained below. In this example embodiment, the strap-sealing drive assembly 690 includes a camshaft with multiple cams thereon that are operably connected to the different components of the strapsealing assembly and the pinch roller 520 via suitable cam followers, linkages, or other suitable components. In operation, the strap-sealing actuator 695 drives the camshaft to rotate the cams and cause the above-referenced and below-explained movements of these components to carry out the strapping process (along with the strap-feeding and strap-tensioning assemblies). This is merely one example of a way the strap-sealing drive assembly 690 is operably connected to the various components of the strap-sealing assembly and the pinch roller 520, and other suitable operative connections may be employed in other embodiments.

[0027] The strap-sealing drive assembly 690 is operably connected to the counterpressure plate 610 to move the counter-pressure plate 610 along the width direction of the strap (into and out of the page from the perspective shown in Figures 6A-6G) and relative to the other components of the strap-sealing assembly 600 between a retracted position (not shown) and a sealing position (Figures 6A-6G).

[0028] The strap-sealing drive assembly 690 is operably connected to the strap guide 620 to move the strap guide 620 along the width direction of the strap (into and out of the page from the perspective shown in Figures 6A-6G) between a retracted position (Figures 6B-6G) and a guiding position (Figure 6A).

[0029] The strap-sealing drive assembly 690 is operably connected to the first strap clamp 630 to move the first strap clamp 630 transverse to the width and longitudinal directions of the strap (vertically from the perspective shown in Figures 6A-6G) and relative to the other components of the strap-sealing assembly 600 between a retracted position (Figure 6A) and a clamping position (Figures 6B-6G).

[0030] The strap-sealing drive assembly 690 is operably connected to the second strap clamp 640 to move the second strap clamp 640 transverse to the width and longitudinal directions of the strap (vertically from the perspective shown in Figures 6A-6G) and relative to the other components of the strap-sealing assembly 600 between a retracted position (Figures 6A, 6B, 6F, and 6G) and a clamping position (Figures 6C-6E). [0031 ] The strap-sealing drive assembly 690 is operably connected to the third strap clamp 650 to move the third strap clamp 650 transverse to the width and longitudinal directions of the strap (vertically from the perspective shown in Figures 6A-6G) and relative to the other components of the strap-sealing assembly 600 among a retracted position (Figures 6A-6C, 6F, and 6G); a first clamping position (Figures 6D); and a second clamping position (Figure 6E).

[0032] The strap-sealing drive assembly 690 is operably connected to the separator 660 to move the separator 660 transverse to the width and longitudinal directions of the strap (vertically from the perspective shown in Figures 6A-6G) and relative to the other components of the strap-sealing assembly 600 between a retracted position (Figures 6A-6F) and a cutting position (Figure 6G).

[0033] The strap-sealing drive assembly 690 is operably connected to the heating element 680 to move the heating element 680 along the width direction of the strap (into and out of the page from the perspective shown in Figures 6A-6G) between a retracted position (Figures 6A-6C and 6E-6G) and a sealing position (Figure 6D).

[0034] Generally, the strap-feeding assembly 400, the strap-tensioning assembly 500, and the strap-sealing assembly 600 are together configured to form a tensioned strap loop around the load 50 by feeding strap S through the strap chute 150 in a feed direction F (Figure 3), holding the leading strap end while retracting the strap S in the retract direction R (Figure 3) to remove it from the strap chute 150 so it contacts the load 50, tensioning the strap S around the load 50 to a designated tension, attaching two overlapping portions of the strap S to one another to form a strap joint, determining whether a strap-joint-verification condition is satisfied, and if so cutting the strap S from the strap supply. In this example embodiment, the strapping machine 10 is a “tabletop” strapping machine in which the frame 100 supports the strap-feeding assembly 400, the strap-tensioning assembly 500, and the strap-sealing assembly 600. In other embodiments, one or more of these assemblies is not supported by the frame 100. For instance, in certain embodiments in which the strapping machine is configured to strap large loads, such as palletized loads, loads of lumber, or loads of corrugated, these assemblies are distinct, independently replaceable modules supported by different components of the strapping machine.

[0035] The strap guide G1 extends between the strap supply (not shown) and the strap-feeding and strap-tensioning assemblies 400 and 500 and is configured to guide the strap as it moves between those components. The strap guide G2 extends between the strap-feeding assembly 400 and the strap-sealing assembly 600 and is configured to guide the strap as it moves between those components.

[0036] The controller 900 includes a processing device (or devices) communicatively connected to a memory device (or devices). For instance, the controller 900 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, read-only 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, such as to carry out the strapping process 1000 described below.

[0037] In this example embodiment, as shown in Figure 4, the controller 900 is operably connected to the strap-feeding actuator 430, the strap-tensioning actuator 530, and the strap-sealing actuator 695 and configured to control the output of these actuators. The controller 900 is communicatively connected to and configured to receive signals from and send signals to the leading-end sensor 905.

[0038] Operation of the strapping machine 10 to carry out a strapping process 1000 is now described in accordance with the flowchart shown in Figure 5 and Figures 6A-6G. During the strapping process 1000, the strapping machine is configured to carry out: (1) a strapfeeding process 1000a by feeding strap from a strap supply around a strap chute that surrounds the load; (2) a strap-retraction process 1000b by pulling the strap out of the strap chute and onto and around the load; (3) a strap-tensioning process 1000c by tensioning the strap around the load to a designated strap tension; (4) a strap-sealing process lOOOd by attaching two portions of the strap to one another to form a strap joint; and (5) a strap-joint-verification process lOOOe by monitoring for movement of the strap after sealing to determine whether the strap joint fails.

[0039] Initially, the pinch roller 520 of the strap-tensioning assembly 500 is in its spaced position, the counter-pressure plate 610 of the strap-sealing assembly is in its sealing position and the strap guide 620, the first strap clamp 630, the second strap clamp 640, the third strap clamp 650, the separator 660, and the heating element 680 of the strap-sealing assembly 600 are in their respective retracted positions. After initiation of the strapping process 1000, strap is moved in a feed direction to feed the strap from a strap supply through a strap chute and around a load, as block 1002 indicates. In this illustrated example embodiment, after initiation of the strapping process 1000, the controller 900 initiates the strap-feeding process and drives the strap-feeding actuator 430 to drive the drive roller 410 in the feed rotational direction to feed the strap S from the strap supply in the feed direction F through the strap guide Gl, between the drive roller 510 and the pinch roller 520 of the strap-tensioning assembly 500, through the strap guide G2, through the opening 630o of the first strap clamp 630, through the channel between the upper and lower portions 622 and 624 of the strap guide 620 of the strap-sealing assembly 600 and into and around the strap chute 150. The leading end LE of the strap S eventually reaches the leading-end stop 626 of the strap guide 620, at which point the leading-end sensor 905 senses the leading end LE and sends an appropriate signal to the controller 900. In response, the controller 900 stops driving the strap-feeding actuator 430 to stop the drive roller 410 and complete the strap-feeding process. Figure 6A shows the strap S and the configuration of the strap-sealing assembly 600 at this point.

[0040] Part of the strap is then clamped, as block 1004 indicates. In this illustrated example embodiment, after the strap-feeding process is complete, the controller 900 initiates the strap-retraction process and drives the strap-sealing actuator 695 to move the strap guide 620 to its retracted position and the first strap clamp 630 to its clamping position such that the clamping surface 630s of the first strap clamp 630 clamps part of the strap S spaced-apart from the leading end LE of the strap S against the underside of the counter-pressure plate 610. Figure 6B shows the strap S and the configuration of the strap-sealing assembly 600 at this point. The strap is then moved in a retract direction to retract the strap from the strap chute so the strap contacts the load, as block 1006 indicates. In this illustrated example embodiment, the controller 900 drives the strap-feeding actuator 430 to drive the drive roller 410 in the retract rotational direction to pull the strap S in the retract direction R and out of the strap chute 150 and onto and around the load, at which point the controller 900 stops driving the strap-feeding actuator 430 to stop the drive roller 410 and complete the strap-retraction process. Figure 6B shows the strap S and the configuration of the strap-sealing assembly 600 at this point. [0041] The strap is then tensioned around the load, as block 1008 indicates. Tn this illustrated example embodiment, after the strap-retraction process is complete, the controller 900 initiates the strap-tensioning process and drives the strap-sealing actuator 695 to move the pinch roller 520 of the strap-tensioning assembly 500 to the tensioning position. The controller 900 drives the strap-tensioning actuator 530 to drive the drive roller 510 in the tensioning rotational direction to pull the strap S in the retract direction R and tension the strap S around the load. As this occurs, the controller 900 monitors the electrical current drawn by the strap-tensioning actuator 530. Once the current draw reaches a predetermined amount that is correlated with a predetermined strap tension, the controller 900 stops driving the strap-tensioning actuator 530 to stop the drive roller 510 and complete the strap-tensioning process. Figure 6B shows the strap S and the configuration of the strap-sealing assembly 600 at this point.

[0042] First and second portions of the strap are connected to one another to form a strap joint, as block 1010 indicates. In this illustrated example embodiment, after the straptensioning process is complete, the controller 900 initiates the strap-sealing process and drives the strap-sealing actuator 695 to move the second strap clamp 640 to its clamping position such that the clamping surface 640s of the second strap clamp 640 clamps a portion of the strap S against the counter-pressure plate 610, as shown in Figure 6C, and to move the pinch roller 520 back to its spaced position (not shown). Continued driving of the strap-sealing actuator 695 moves the heating element 680 — which is heated at this point — to its sealing position in which the heating element 680 is between a first portion of the strap S adjacent the leading end LE and a second portion of the strap S below the first portion, as shown in Figure 6D.

[0043] Continued driving of the strap-sealing actuator 695 moves the third strap clamp 650 to its first clamping position such that the first portion of the strap S is clamped between the underside of the counter-pressure plate 610 and the upper surface of the heating element 680 and the second portion of the strap S is clamped between the clamping surface 650s of the third strap clamp 650 and the underside of the heating element 680. The heating element 680 softens the first and second portions of the strap S while contacting them. Continued driving of the strap-sealing actuator 695 moves the heating element 680 back to its retracted position and then moves the third strap clamp 650 to its second clamping position to clamp the softened first and second portions of the strap S against one another and between the clamping surface 350s of the third strap clamp and the underside of the counter-pressure plate 310, as shown in Figure 6E. This connects the first and second portions of the strap S to one another and forms a strap joint SJ. Continued driving of the strap-sealing actuator 695 moves the second and third strap clamps 640 and 650 back to their respective retracted positions, as shown in Figure 6F.

[0044] The strap is monitored for movement in the feed direction, as block 1012 indicates, and the controller determines whether a strap-joint-verification condition is satisfied based on that monitoring, as indicated in diamond 1014. Generally, after the strap joint is formed, the strap imposes a pulling force on the strap joint in the feed direction. This pulling force can be caused, for instance, by the load attempting to expand after being compressed before or during the strap-tensioning process and/or by the strap having been stretched during the strap-tensioning process and attempting to return to its unstretched state. The pulling force may, in certain instances, cause the strap joint to fail, in which case the strap will move in the feed direction. A strap-movement sensor monitors for movement of the strap either directly (by monitoring the strap itself) or indirectly (by monitoring a component whose movement is indicative of strap movement). The strap-joint-verification condition is satisfied if the strap does not move more than a designated amount during a designated time period, which indicates that strap joint did not fail during that designated time period. If the strap-joint-verification condition is satisfied at diamond 1014, the strap is separated from the strap supply, as block 1016 indicates, the strap is unclamped, as block 1018 indicates, and the strapping process 1000 ends. If, on the other hand, the strap-joint-verification condition is not satisfied at diamond 1014, an alert is output, as block 1020 indicates, and the strapping process 1000 ends.

[0045] In this illustrated example embodiment, after the strap-sealing process is complete and the second strap clamp 640 has released the strap S, the controller 900 initiates the strap-joint-verification process and monitors for movement of the strap S in the feed direction F via the strap-movement sensor 915. In this embodiment, the controller 900 does so by monitoring rotation of the drive roller 410 of the strap-feeding assembly 400 via the strapmovement sensor 915, which includes an encoder or other suitable sensor, for a designated period of time (such as 0.1-0.2 seconds). The controller 900 determines that the strap-joint- verification condition is satisfied if the drive roller 410 does not rotate more than a designated amount in the feed rotational direction during the designated period of time. If this occurs, the strap joint SJ did not fail, and the controller 900 drives the strap-sealing actuator 695 to move the separator 660 to its cutting position to cut the strap S from the strap supply, as shown in Figure 6G. The controller 900 drives the strap-sealing actuator 695 to move the first clamp 630 and the counter-pressure plate 610 to their respective retracted positions, releasing the strap loop and enabling the strapped load to be removed from the strapping machine 10. In this example embodiment, the designated amount is zero degrees such that the strap-joint-verification condition is satisfied if the drive roller 410 does not rotate in the feed rotational direction during the designated period of time. The designated amount may be any other suitable amount in other embodiments, such as an amount that corresponds to movement of the strap 0.5-3 millimeters in the feed direction F. The designated amount may vary depending on the desired maximum strap movement and the diameter of the drive roller.

[0046] Conversely, the controller 900 determines that the strap-joint-verification condition is not satisfied if the drive roller 410 rotates more than the designated amount in the feed rotational direction during the designated period of time. If this occurs, the strap joint failed, and the controller 900 controls an output device to output an alert. For instance, the controller 900 controls a speaker to output a sound, a display screen to display a message, or a light to activate to alert the operator. This terminates the strapping process 1000. Figures 7A-7C show what happens when the strap joint SJ fails. Specifically, Figure 7A corresponds to Figure 6E after the strap joint SJ has been formed but with the second strap clamp 640 still in its clamping position. Figure 7B corresponds to Figure 6F after the second strap clamp 640 has released the strap S, at which point the strap S imposes a pulling force P on the strap joint SJ in the feed direction F. Figure 7C shows the strap S after the pulling force P caused the strap joint SJ to fail, thereby causing the strap S to move in the feed direction F and cause the drive roller 410 of the strap-feeding assembly 400 to rotate more than the designated amount in the feed rotational direction.

[0047] In the above-described embodiment, the strap-sealing assembly continues clamping at least part of the strap during the strap-joint-verification process. In other embodiments, the strap-sealing assembly unclamps the strap completely before initiating the strap-joint-verification process or while carrying out the strap-joint-verification process.

[0048] In the above-described embodiment, the controller monitors rotation of the drive roller of the strap-feeding assembly to determine whether the strap-joint-verification condition is met. In other embodiments, the controller monitors rotation of the pinch roller of the strap-feeding assembly or either of the rollers of the strap-tensioning assembly to determine whether the strap-joint-verification condition is met. Tn further embodiments, the controller monitors rotation of another suitable roller — such as a roller designated solely for determining whether the strap-joint-verification condition is met — to determine whether the strap-joint- verification condition is met. In other embodiments, the strapping machine includes any other suitable sensor, such as an optical sensor, configured to detect movement of the strap, and the controller monitors feedback from that sensor determine whether the strap-joint-verification condition is met.

[0049] In certain embodiments, if the strap-joint-verification condition is not satisfied, the controller is configured to control the strapping head to cut the strap from the strap supply and to automatically carry out another strapping process. In other embodiments, if the strap-joint-verification condition is not satisfied, the controller is configured to control the strapping head to cut the strap from the strap supply and to control an ejector, such as a mechanical lever or a blower, to eject the cut portion of strap from the strap chute before controlling the strapping head to automatically carry out another strapping process.

[0050] Operation of the strapping machine 10 to carry out another embodiment of a strapping process 2000 including an alternative strap-j oint verification process is described in accordance with the flowchart shown in Figure 8 and Figures 6A-6G. During the strapping process 2000, the strapping machine is configured to carry out: (1) a strap-feeding process 2000a by feeding strap from a strap supply around a strap chute that surrounds the load; (2) a strapretraction process 2000b by pulling the strap out of the strap chute and onto and around the load; (3) a strap-tensioning process 2000c by tensioning the strap around the load to a designated strap tension; (4) a strap-sealing process 2000d by attaching two portions of the strap to one another to form a strap joint; and (5) a strap-joint-verification process 2000e by applying a tensile force to the strap and the strap joint.

[0051] Initially, the pinch roller 520 of the strap-tensioning assembly 500 is in its spaced position, the counter-pressure plate 610 of the strap-sealing assembly is in its sealing position and the strap guide 620, the first strap clamp 630, the second strap clamp 640, the third strap clamp 650, the separator 660, and the heating element 680 of the strap-sealing assembly 600 are in their respective retracted positions. After initiation of the strapping process 2000, strap is fed from a strap supply through a strap chute and around a load, as block 2002 indicates. In this illustrated example embodiment, after initiation of the strapping process 2000, the controller 900 initiates the strap-feeding process and drives the strap-feeding actuator 430 to drive the drive roller 410 in the feed rotational direction to feed the strap S from the strap supply in the feed direction F through the strap guide Gl, between the drive roller 510 and the pinch roller 520 of the strap-tensioning assembly 500, through the strap guide G2, through the opening 63 Oo of the first strap clamp 630, through the channel between the upper and lower portions 622 and 624 of the strap guide 620 of the strap-sealing assembly 600 and into and around the strap chute 150. The leading end LE of the strap S eventually reaches the leading-end stop 626 of the strap guide 620, at which point the leading-end sensor 905 senses the leading end LE and sends an appropriate signal to the controller 900. In response, the controller 900 stops driving the strapfeeding actuator 430 to stop the drive roller 410 and complete the strap-feeding process. Figure 6A shows the strap S and the configuration of the strap-sealing assembly 600 at this point.

[0052] Part of the strap that is spaced-apart from the leading end of the strap is then clamped against the counter-pressure plate, as block 2004 indicates. In this illustrated example embodiment, after the strap-feeding process is complete, the controller 900 initiates the strapretraction process and drives the strap-sealing actuator 695 to move the strap guide 620 to its retracted position and the first strap clamp 630 to its clamping position such that the clamping surface 630s of the first strap clamp 630 clamps part of the strap S spaced-apart from the leading end LE of the strap S against the underside of the counter-pressure plate 610. Figure 6B shows the strap S and the configuration of the strap-sealing assembly 600 at this point. The strap is then retracted from the strap chute so the strap contacts the load, as block 2006 indicates. In this illustrated example embodiment, the controller 900 drives the strap-feeding actuator 430 to drive the drive roller 410 in the retract rotational direction to pull the strap S in the retract direction R and out of the strap chute 150 and onto and around the load, at which point the controller 900 stops driving the strap-feeding actuator 430 to stop the drive roller 410 and complete the strapretraction process. Figure 6B shows the strap S and the configuration of the strap-sealing assembly 600 at this point.

[0053] The strap is then tensioned around the load, as block 2008 indicates. In this illustrated example embodiment, after the strap-retraction process is complete, the controller 900 initiates the strap-tensioning process and drives the strap-sealing actuator 695 to move the pinch roller 520 of the strap-tensioning assembly 500 to the tensioning position. The controller 900 drives the strap-tensioning actuator 530 to drive the drive roller 510 in the tensioning rotational direction to pull the strap S in the retract direction R and tension the strap S around the load. As this occurs, the controller 900 monitors the electrical current drawn by the strap-tensioning actuator 530. Once the current draw reaches a predetermined amount that is correlated with a predetermined strap tension, the controller 900 stops driving the strap-tensioning actuator 530 to stop the drive roller 510 and complete the strap-tensioning process. Figure 6B shows the strap S and the configuration of the strap-sealing assembly 600 at this point.

[0054] First and second portions of the strap are connected to one another to form a strap joint between the leading end of the strap and the clamped part of the strap, as block 2010 indicates. In this illustrated example embodiment, after the strap-tensioning process is complete, the controller 900 initiates the strap-sealing process and drives the strap-sealing actuator 695 to move the second strap clamp 640 to its clamping position such that the clamping surface 640s of the second strap clamp 640 clamps a portion of the strap S against the counter-pressure plate 610, as shown in Figure 6C, and to move the pinch roller 520 back to its spaced position (not shown). Continued driving of the strap-sealing actuator 695 moves the heating element 680 — which is heated at this point — to its sealing position in which the heating element 680 is between a first portion of the strap S adjacent the leading end LE and a second portion of the strap S below the first portion, as shown in Figure 6D.

[0055] Continued driving of the strap-sealing actuator 695 moves the third strap clamp 650 to its first clamping position such that the first portion of the strap S is clamped between the underside of the counter-pressure plate 610 and the upper surface of the heating element 680 and the second portion of the strap S is clamped between the clamping surface 650s of the third strap clamp 650 and the underside of the heating element 680. The heating element 680 softens the first and second portions of the strap S while contacting them. Continued driving of the strap-sealing actuator 695 moves the heating element 680 back to its retracted position and then moves the third strap clamp 650 to its second clamping position to clamp the softened first and second portions of the strap S against one another and between the clamping surface 350s of the third strap clamp and the underside of the counter-pressure plate 310, as shown in Figure 6E. This connects the first and second portions of the strap S to one another and forms a strap joint SJ. Continued driving of the strap-sealing actuator 695 moves the second and third strap clamps 340 and 350 back to their respective retracted positions, as shown in Figure 6F. [0056] A tensile force is then applied to the strap, as block 2012 indicates The controller determines whether a strap-joint-verification condition is satisfied, as indicated in diamond 1014. The controller does so by monitoring a characteristic of the strapping head, as explained below. Generally, the strap-joint-verification condition is satisfied if the strap joint does not fail while the tensile force is being applied to the strap by the drive roller. In certain embodiments, the tensile force is correlated to a minimum joint efficiency for the particular strapping process and type of strap such that if the strap joint does not fail while the tensile force is applied, the joint efficiency of the strap joint is least equal to the minimum joint efficiency. The joint efficiency of a strap joint is typically characterized as a percentage of the break strength of the strap. For example, if the strap has a break strength of 900 pounds and the strap joint has a joint efficiency of 75%, the strap joint will withstand at least 675 pounds of tensile force before failing. The minimum joint efficiency that a strap joint must meet for a strapping process to succeed varies based on the type of strap and the method used to attach the portions of the strap to one another. If the strap-joint-verification condition is satisfied at diamond 1014, the strap is separated from the strap supply, as block 1016 indicates, the part of the strap is unclamped from the counter-pressure plate, as block 1018 indicates, and the strapping process 1000 ends. If, on the other hand, the strap-joint-verification condition is not satisfied at diamond 1014, an alert is output, as block 2020 indicates, and the strapping process 2000 ends.

[0057] In this illustrated example embodiment, after the strap-sealing process is complete, the controller 900 initiates the strap-joint-verification process and drives the straptensioning actuator 530 to drive the drive roller 510 in the tensioning rotational direction (though it drives the strap-feeding actuator 430 to drive the drive roller 410 in the tensioning rotational direction in other embodiments) to apply a tensile force to the strap S in the retract direction R. As this occurs, the first strap clamp 630 continues to clamp the part of the strap S on the opposite side of the strap joint SJ as the leading end LE against the underside of the counter-pressure plate 610. The controller 900 monitors a characteristic of the strapping head 300 and determines whether the strap-joint-verification condition is satisfied based on that monitored characteristic. In this example embodiment, the controller 900 controls the strap-tensioning actuator 530 to apply the tensile force to the strap S for a designated period of time (such as 0.1-0.2 seconds) and while doing so monitors rotation of the drive roller 510, such as via an encoder or other suitable sensor The controller 900 determines that the strap-joint-verification condition is satisfied if the drive roller 510 does not rotate more than a designated amount during the designated period of time. If this occurs, the tensile force did not break the strap joint SJ, and the controller 900 controls the tensioning actuator 530 to stop driving the drive roller 510 and drives the strap-sealing actuator 695 to move the separator 660 to its cutting position to cut the strap S from the strap supply, as shown in Figure 6G. The controller 900 drives the strap-sealing actuator 695 to move the first clamp 630 and the counter-pressure plate 610 to their respective retracted positions, releasing the strap loop and enabling the strapped load to be removed from the strapping machine 10.

[0058] Conversely, the controller 900 determines that the strap-joint-verification condition is not satisfied if the drive roller 510 rotates more than the designated amount during the designated period of time. If this occurs, the tensile force broke the strap joint, and the controller 900 controls an output device to output an alert. For instance, the controller 900 controls a speaker to output a sound, a display screen to display a message, or a light to activate to alert the operator. This terminates the strapping process 2000.