INCLUDING A FLEXUR ALL Y MOUNTED WELD PAD

Priority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/381,955, filed November 2, 2022, the entire contents of which is incorporated herein by reference.

Field

[0002] The present disclosure relates to strap-sealing assemblies for strapping devices, and more particularly to friction-welding strap-sealing assemblies including a flexurally mounted weld pad.

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. 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 using strap drawn from a strap supply, 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 the 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 attaching two portions of the strap together to form the strap loop and for cutting the strap from the strap supply. The strapping machine includes several guides that define strap channels that the strap passes through as it moves through the various components of the strapping machine. 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-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. The strapping machine then carries out the strap-tensioning process during which the straptensioning 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 two overlapping portions of the strap to one another to form a strap joint and cuts the strap from the strap supply, thereby forming a strap loop around the load and completing the strapping process.

[0005] Certain strapping machines configured for plastic or paper strap include a friction-welding strap-sealing assembly to weld the two overlapping portions of the strap to one another. A typical friction-welding strap-sealing assembly includes an anvil, a weld pad mounted to a support that is movable toward and away from the anvil, and a weld motor operable to rapidly oscillate the weld pad relative to the support and the anvil. In operation, the two overlapping portions of the strap are positioned between the anvil and the weld pad. The support is moved toward the anvil such that the weld pad clamps the overlapping portions of the strap against the anvil. The weld motor is activated to oscillate the weld pad, and the friction and heat generated by the rapid oscillation of the weld pad melts and joins parts of the overlapping strap portions together to form a welded strap joint.

[0006] In certain friction-welding strap-sealing assemblies, such as the one shown in Figures 1 A and IB, the weld pad WP is mounted to the support S via four linear roller bearings B that support and guide the weld pad WP during oscillation, and the weld pad WP includes carbide pads CP that engage the bearings B. This results in several issues. First, the bearings must be lubricated regularly, requiring the strapping machine to be shut down for maintenance on a regular basis. Second, the rollers in the bearings are relatively large compared to the stroke of the weld pad — e.g., 2 millimeters in diameter versus a 1 millimeter weld pad stroke. This results in the rollers only partially rotating as the weld pad oscillates, which can lead to ineffective lubrication and premature failure. Third, the linear roller bearings and carbide pads are relatively small components that must be replaced relatively often during the lifetime of the strapping machine, which increases costs, requires machine shut down, and makes replacement difficult (due to their small size).

Summary

[0007] Various embodiments of the present disclosure provide a strapping machine including a friction-welding strap-sealing assembly with a flexurally mounted weld pad. Specifically, the strap-sealing assembly includes a weld pad flexurally mounted to a support by one or more resiliently flexible mounting members. The mounting members support the weld pad and are deformable to enable the weld pad to oscillate relative to the support during the friction-welding process.

Brief Description of the Figures

[0008] Figures 1A and IB are assembled and exploded perspective views of an example prior art weld pad and support.

[0009] Figure 2 is a diagrammatic view of one example embodiment of a strapping machine of the present disclosure.

[0010] Figure 3 is a perspective view of the weld-pad assembly of the frictionwelding strap-sealing assembly of the strapping machine of Figure 2.

[0011] Figure 4 is a diagrammatic side view of the weld-pad assembly of Figure 3 and other components of the friction-welding strap-sealing assembly.

[0012] Figures 5A-5E are diagrammatic side views of the weld-pad assembly of Figure 3 and other components of the friction-welding strap-sealing assembly during the frictionwelding process.

[0013] Figure 6A is a diagrammatic side view of another embodiment of a weld-pad assembly and other components of the friction-welding strap-sealing assembly.

[0014] Figure 6B is a perspective view of the components shown in Figure 6A. [0015] Figure 7 is a diagrammatic side view of another embodiment of a weld-pad assembly.

[0016] Figure 8 is a diagrammatic side view of another embodiment of a weld-pad assembly.

[0017] Figure 9 is a diagrammatic side view of another embodiment of a weld-pad assembly.

Detailed Description

[0018] 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.

[0019] Various embodiments of the present disclosure provide a strapping machine including a friction-welding strap-sealing assembly with a flexurally mounted weld pad. Figure 2 shows one example embodiment of a strapping machine 1 of the present disclosure and components thereof in a simplified manner for clarity. The strapping machine 1 is configured to form a tensioned loop of strap around a load and includes a strapping-machine frame (not shown), a strap chute CH, a load supporter LS, a strap-feeding assembly FM, a strap-tensioning assembly TM, a strap-sealing assembly SM, guides G1 and G2, and a controller C. [0020] The strapping-machine frame is configured to support some (or all) of the other components of the strapping machine 1 and may be formed of any suitable components arranged in any suitable configuration. The load supporter LS is configured to support loads — such as the palletized load L — as they are strapped by and as they move through the strapping machine 1. The load supporter LS 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 1. In this example embodiment, the support surface includes multiple rollers that facilitate movement of the loads through the strapping machine 1. The rollers may be driven or undriven. In other embodiments, the support surface includes a driven conveyor instead of rollers.

[0021] The strap chute CH circumscribes the support surface of the load supporter LS and defines a strap path that the strap follows when fed through the strap chute CH and from which the strap is removed when retracted. The strap chute CH includes two spaced-apart first and second upstanding legs, an upper connecting portion that spans the first and second legs, a lower connecting portion that spans the first and second legs and is positioned in the load supporter LS, and elbows that connect these portions. The radially inward wall of the strap chute CH is 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 CH. When the strap-feeding assembly FM exerts a 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 CH so the strap moves radially inward into contact with the load L.

[0022] The strap-feeding assembly FM, the strap-tensioning assembly TM, and the strap-sealing assembly SM are together configured to form a tensioned strap loop around the load by feeding the strap through the strap chute CH, holding the leading strap end while retracting the strap to remove it from the strap chute CH so it contacts the load L, tensioning the strap around the load L to a designated tension, connecting two overlapping portions of the strap to one another, and cutting the strap from the strap supply. In this example embodiment, the strap-feeding assembly FM, the strap-tensioning assembly TM, and the strap-sealing assembly SM are distinct modules that are individually attachable to and removable from the strappingmachine frame. The guide G1 extends between the strap-feeding and strap-tensioning assemblies FM and TM and is configured to guide the strap as it moves between those assemblies. The guide G2 extends between the strap-tensioning and strap-sealing assembly TM and SM and is configured to guide the strap as it moves between those assemblies. In other embodiments these assemblies form a strapping head that is not comprised of self-contained and individually removable modules.

[0023] Generally, the strap-feeding assembly FM is configured to feed strap from a strap supply (not shown) and into and around the strap chute CH and to retract the strap so it exits the strap chute CH and contacts the load L. Generally, the strap-tensioning assembly TM is configured to tension the strap around the load L. The strap-tensioning assembly includes a tensioning wheel driven by a tensioning actuator. Once the strap-feeding assembly FM retracts the strap so it contacts the load L, the tensioning actuator drives the tensioning wheel to tension the strap to a designated (typically preset) tension. Generally, the strap-sealing assembly SM is configured to, after the strap-tensioning assembly TM tensions the strap to the designated tension, attach two overlapping portions of the strap to one another to form the strap loop and cut the strap from the strap supply. The manner of attaching the leading and trailing strap ends to one another depends on the type of strapping machine and the type of strap. The strap-sealing assembly SM of the present disclosure is a friction-welding strap-sealing assembly, as described below.

[0024] The controller C 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 1. In certain embodiments, the strapping machine 1 includes a single controller, while in other embodiments the strapping machine 1 has multiple controllers that operate together. In certain embodiments, the controller C is part of the strap-feeding assembly FM, the strap-tensioning assembly TM, and/or the strap-sealing assembly SM.

[0025] Returning to the strap-sealing assembly SM, the strap-sealing assembly SM is configured to attach two overlapping portions of the strap together via friction welding. To that end, and as best shown in Figures 3-5E, the strap-sealing assembly SM includes a weld-pad assembly 10, an eccentric 500, a connector 600, a weld motor 700 including a rotatable output shaft, and an anvil 800.

[0026] The weld-pad assembly 10 includes a weld pad 100, a weld-pad support 200, a first mounting member 300, multiple first fasteners 300f, a second mounting member 400, and multiple second fasteners 400f.

[0027] The weld pad 100 includes a body having a welding portion 110 and a driven portion 120. The welding portion 110 of the body of the weld pad 100 has a textured welding surface 110s. The weld pad 100 is flexurally mounted to the support 200 by the first and second mounting members 300 and 400 such that the weld pad 100 can oscillate relative to the support 200 in the direction D. The first and second mounting members 300 and 400 are formed from resiliently flexible material having a stiffness that enables the first and second mounting members 300 and 400 to, when subjected to a force in the direction D (such as a force imposed by the weld pad 100), deform from respective resting configurations and return to their respective resting configurations when the force is removed. In other words, once the first and second mounting members 300 and 400 are deformed from their resting configurations, they are biased to return to their resting configurations. This ability of the first and second mounting members 300 and 400 to deform enables the weld pad 100 to oscillate relative to the support 200 in the direction D.

[0028] In this example embodiment, opposing upper and lower portions of the first mounting member 300 are attached via the first fasteners 300f to first sides of the welding portion 110 of the weld pad 100 and the support 200, respectively. Similarly, opposing upper and lower portions of the second mounting member 400 are attached via the second fasteners 400f to second sides of the welding portion 110 of the weld pad 100 and the support 200, respectively. In this example embodiment, the first and second mounting members 300 and 400 are flat springs formed from steel that each have a planar resting configuration. The first and second mounting members 300 and 400 bend back and forth in the direction D as the weld pad 100 oscillates during the friction-welding process and imposes various bending forces on the first and second mounting members 300 and 400.

[0029] The eccentric 500 is configured to convert the rotary motion of the output shaft of the weld motor 700 into linear reciprocating motion to oscillate the weld pad 100. Specifically, the eccentric 500 includes an arm 510 connected to the driven portion 120 of the weld pad 100 via the connector 600 and fasteners 600f and 120f. As the weld motor 700 rotates its output shaft, the eccentric 500 converts that rotary motion into linear reciprocating motion of the arm 510, which (via the connector 600) oscillates the weld pad 100. In this example embodiment, the connector 600 is a flat spring made of steel, though it may be any other suitable connector in other embodiments. In further embodiments, the eccentric is directly connected to the weld pad (and not indirectly via a connector). In certain embodiments, the natural frequency of the first mounting member 300 and the second mounting member 400 is substantially the same as the driving frequency of the eccentric 500.

[0030] Figures 5A-5E illustrate the friction-welding process carried out by the sealing assembly SM. As shown in Figure 5 A, initially, the weld pad 100 is spaced-apart from the anvil 800 to make room for the strap. As shown in Figure 5B, before initiation of the frictionwelding process, overlapping upper and lower strap portions UP and LP are positioned between a welding surface 800s of the anvil 800 and the welding surface 110s of the welding portion 110 of the weld pad. As shown in Figure 5C, the support 200 is moved toward the anvil 800 by a suitable actuator (such as the cam of a camshaft driven by a motor) such that the weld pad 100 clamps the upper and lower strap portions UP and LP against the anvil 800. The weld motor 700 is activated to oscillate the weld pad 100 relative to the support 200 and the anvil 800, as shown in Figures 5D and 5E, and the friction and heat generated by the rapid oscillation of the weld pad 100 melts and joins parts of the overlapping strap portions together to form a welded strap joint. The first and second mounting members 300 and 400 are sized, shaped, and otherwise configured not to enable substantial movement of the weld pad 100 in directions transverse to the direction D. For instance, the first and second mounting members 300 and 400 are configured so as not to deform in response to counterforce applied by the anvil 800 as the weld pad 100 clamps the upper and lower strap portions UP and LP against the anvil 800. Additionally, the first and second mounting members 300 and 400 are configured so as not to deform and enable movement of the weld pad 100 in the direction transverse to the longitudinal direction of the strap (e.g., into and out of the page from the perspective shown in Figures 5A-5E).

[0031] The flexurally mounted weld pad of the present disclosure solves the above problems. Specifically, the use of resiliency flexible mounting members — which do not require lubrication — to mount the weld pad to the support eliminates the need for maintenance heavy linear roller bearings.

[0032] While the above-described example embodiment includes two mounting members, in other embodiments the weld-pad assembly may include only one mounting member or more than two mounting members to flexurally mount the weld pad to the support. Additionally, while the above-described example embodiment includes mounting members made of steel, in other embodiments the mounting member(s) may be made of any other suitable material, such as rubber.

[0033] Figures 6A and 6B show another embodiment of a weld-pad assembly 1010 including a weld pad 1100, a weld-pad support 1200, multiple first mounting members 1300, multiple first fasteners 1300f, multiple second mounting members 1400, and multiple second fasteners 1400f. The weld pad 1100 includes a body having a welding portion 1110 and a driven portion 1120. The welding portion 1110 of the body of the weld pad 1100 has a textured welding surface 1110s. The weld pad 1100 is flexurally mounted to the support 1200 by the first and second mounting members 1300 and 1400 such that the weld pad 1100 can oscillate relative to the support 1200 in the direction D. The first and second mounting members 1300 and 1400 are formed from resiliently flexible material having a stiffness that enables the first and second mounting members 1300 and 1400 to, when subjected to a force in the direction D (such as a force imposed by the weld pad 1100), deform from respective resting configurations and return to their respective resting configurations when the force is removed. In other words, once the first and second mounting members 1300 and 1400 are deformed from their resting configurations, they are biased to return to their resting configurations. This ability of the first and second mounting members 1300 and 1400 to deform enables the weld pad 1100 to oscillate relative to the support 1200 in the direction D.

[0034] In this example embodiment, opposing upper and lower portions of the first mounting members 300 are attached via the first fasteners 300f to first sides of the welding portion 1110 of the weld pad 1100 and the support 1200, respectively. Similarly, opposing upper and lower portions of the second mounting members 1400 are attached via the second fasteners 1400f to second sides of the welding portion 1110 of the weld pad 1100 and the support 1200, respectively. In this example embodiment, the first and second mounting members 1300 and 1400 are flat springs formed from steel that each have a planar resting configuration. The first and second mounting members 1300 and 1400 bend back and forth in the direction D as the weld pad 1100 oscillates during the friction-welding process and imposes various bending forces on the first and second mounting members 1300 and 1400. The first and second mounting members 1300 and 1400 are sized, shaped, and otherwise configured not to enable substantial movement of the weld pad 1100 in directions transverse to the direction D. Multiple connectors 1600 connect the arm 1510 to the weld pad 1100.

[0035] Figure 7 shows another embodiment of a weld-pad assembly 2000 including a weld pad 2100, a weld-pad support 2200, multiple first mounting members 2300, multiple second mounting members 2400, an arm 2510, and multiple connectors 2600. The weld pad 2100 includes a textured welding surface 2100s. The weld pad 1100 is flexurally mounted to the support 2200 by the first and second mounting members 2300 and 2400 such that the weld pad 2100 can oscillate relative to the support 2200 in the direction D. The first and second mounting members 2300 and 2400 are sized and shaped such that they have a stiffness that enables the first and second mounting members 2300 and 2400 to, when subjected to a force in the direction D (such as a force imposed by the weld pad 2100), deform from respective resting configurations and return to their respective resting configurations when the force is removed. In other words, once the first and second mounting members 2300 and 2400 are deformed from their resting configurations, they are biased to return to their resting configurations. This ability of the first and second mounting members 2300 and 2400 to deform enables the weld pad 2100 to oscillate relative to the support 2200 in the direction D. The first and second mounting members 2300 and 2400 are sized, shaped, and otherwise configured not to enable substantial movement of the weld pad 2100 in directions transverse to the direction D. The connectors 2600 connect the weld pad 2100 to the arm 2510, which is driven by the eccentric. In this example embodiment, the weldpad assembly 2000 is formed from a single piece of material (such as via water-jet cutting) such that the above-identified components are integrally formed with one another.

[0036] Figure 8 shows another embodiment of the weld-pad assembly 3010. The weld-pad assembly 3010 is the same as the weld-pad assembly 1010 described above except that it included additional fasteners 3302 and 3402. The fasteners 3302 include one or more fasteners between the upper and lower fasteners 3300f that connect the first mounting members 3300 to one another (but not to the support 3200). Similarly, the fasteners 3402 include one or more fasteners between the upper and lower fasteners 3400f that connect the first mounting members 3400 to one another (but not to the support 3200).

[0037] Figure 9 shows another embodiment of the weld-pad assembly 4000. The weld-pad assembly 4000 is the same as the weld-pad assembly 2000 described above except that the thickness of the mounting members is greater in the center of the mounting member than near the ends of the mounting member. Although not shown, a similar modification could be made to any of the mounting members of any other embodiments described herein.