Strapping device with strap-cleaning option

Abstract

Various embodiments of the present disclosure provide a strapping device including a tensioning plate, a rotatable tensioning wheel adjacent the tensioning plate, a first weld plate, a second weld plate, a motor operably connected to one of the first and second weld plates, and a controller. The controller is configured to, responsive to initiation of a sealing cycle with a strap-cleaning option active, control the motor to: oscillate the one of the first and second weld plates relative to the other at a first frequency for a first period; after the first period, oscillate the one of the first and second weld plates relative to the other at a second frequency for a second period, wherein the second frequency is greater than the first frequency; and after the second period, stop oscillating the one of the first and second weld plates relative to the other.

Description

STRAPPING DEVICE WITH STRAP-CLEANING OPTIONPriority

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 520,770, filed August 21, 2023, the entire contents of which is incorporated herein by reference.Field

[0002] The present disclosure relates to strapping devices, and more particularly to strapping devices configured to tension strap around a load and to attach overlapping layers of the strap to one another to form a tensioned strap loop around the load.Background

[0003] Strapping devices are configured to tension strap around a load and to attach overlapping layers of the strap to one another to form a tensioned strap loop around the load. Some strapping devices utilize friction welding to attach overlapping upper and lower strap layers to one another. To use one of these strapping devices to form a tensioned strap loop around a load, an operator pulls strap leading end first from a strap supply, wraps the strap around the load, and a lower layer of the strap including the leading end of the strap below an upper layer of the strap. The operator introduces the overlapped strap layers into the strapping device and presses a button to initiate a tensioning cycle during which a tensioning wheel rotates to move the upper stray layer over the lower strap layer and tension the strap around the load. After completion of the tensioning cycle, a sealing cycle is initiated. During the sealing cycle, a weld shoe sandwiches the strap layers against a toothed weld plate. A motor oscillates the toothed weld shoe at a high frequency. The oscillating weld shoe oscillates the upper strap layer relative to the lower strap layer, which generates friction between portions of the overlapping strap layers. This friction locally melts and joins those portions of the overlapping strap layers, thereby attaching the upper and lower strap layers to form the tensioned strap loop.

[0004] Strapping devices are sometimes used in wet or dirty environments, such as outdoors at a lumber mill. In situations like these, the strap may be wet or dirty when introduced into the strapping device. The moisture or debris on the strap can interfere with the frictionwelding process, resulting in weaker strap joints.Summary

[0005] Various embodiments of the present disclosure provide a strapping device including a tensioning plate, a rotatable tensioning wheel adjacent the tensioning plate, a first weld plate, a second weld plate, a motor operably connected to one of the first and second weld plates, and a controller. The first weld plate is movable toward and away from the second weld plate. The controller is configured to, responsive to initiation of a sealing cycle with a strapcleaning option active, control the motor to: oscillate the one of the first and second weld plates relative to the other of the first and second weld plates at a first frequency for a first period; after the first period, oscillate the one of the first and second weld plates relative to the other of the first and second weld plates at a second frequency for a second period, wherein the second frequency is greater than the first frequency; and after the second period, stop oscillating the one of the first and second weld plates relative to the other of the first and second weld plates.Brief Description of the Figures

[0006] Figures 1A and IB are perspective views of one example embodiment of a strapping device of the present disclosure.

[0007] Figure 1C is a block diagram of certain components of the strapping device of Figures 1A and IB.

[0008] Figures 2A-2C are diagrammatic views of the strapping device of Figures 1A and IB securing a load to a pallet.

[0009] Figure 2D is a perspective view of a friction- weld strap joint formed by the strapping device of Figure 1 A to attach two overlapping strap layers.

[0010] Figures 3 A and 3B are perspective views of the working assembly of the strapping device of Figures 1A and IB.

[0011] Figure 4A is a perspective view of part of the working assembly of Figures 3A and 3B.

[0012] Figure 4B is a cross-sectional perspective view of part of the working assembly of Figures 3A and 3B.

[0013] Figures 5A-5F are side views of part of one side of the working assembly of Figures 3A and 3B showing the tensioning assembly moving from its tensioning position to its strap-insertion position and back to its tensioning position. Certain components of the working assembly are not shown for clarity.

[0014] Figure 6A is a front elevational view of the working assembly of Figures 3A and 3B showing the sealing assembly in a home configuration.

[0015] Figure 6B is a front elevational view similar to Figure 6A showing the sealing assembly between the home configuration and a sealing configuration and forcing the overlapping upper and lower strap layers against the weld plate.

[0016] Figure 6C is a front elevational view similar to Figures 6A and 6B showing the sealing assembly in the sealing configuration and the weld shoe oscillating.

[0017] Figure 7 is a flowchart of an example strapping process of the present disclosure with the strap-cleaning option active.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 operablymounted, connected, and like mounting methods. This specification is intended to be taken as a whole and interpreted in accordance with the principles of the present disclosure and as understood by one of ordinary skill in the art.

[0019] Figures 1A-6C show one example embodiment of a strapping device of the present disclosure in the form of a battery-powered portable strapping device 50 and certain assemblies and components thereof. As shown in Figures 2A-2C, the strapping device 50 is configured to carry out a strapping cycle to tension and seal strap S (plastic strap in this example embodiment) around a load L on a pallet P to form a tensioned strap loop that secures the load L to the pallet P. An operator pulls strap S from a strap supply (not shown) and wraps the strap around the load L and through the openings in the pallet P until a lower layer LL of the strap S (which includes the leading end of the strap S) is positioned below an upper layer UL of the strap S, as shown in Figure 2A. The operator then introduces the overlapping upper and lower layers UL and LL of the strap S into the strapping device 50 and actuates one or more buttons to initiate the strapping cycle. As shown in Figure 2B, a motor drives a tensioning assembly to carry out a tensioning cycle during which the strapping device 50 tensions strap S around the load L. Once a preset tension is reached in the strap S, as shown in Figure 2C, the motor drives a sealing assembly to carry out a sealing cycle during which the strapping device 50 connects the upper and lower layers UL and LL of the strap S to one another via friction welding to form a strap joint SJ, as shown in Figure 2D, and cuts the strap S from the strap supply.

[0020] The strapping device 50 includes a housing 100 (Figures 1A and IB), a working assembly 200 (Figures 3A-4B), first and second pushbutton actuators 1410 and 1440 (Figures 1A-1C), a display assembly 1490 (Figures 1A-1C), a power supply 1500, a controller 1600 (Figure 1C), and one or more sensors 1700 (Figure 1C).

[0021] The housing 100, which is shown in Figures 1A and IB, is formed from multiple components (not individually labeled) that collectively at least partially enclose and / or support some (or all) of the other assemblies and components of the strapping device 50. In this example embodiment, the housing 100 includes a front housing section 110, a rear housing section 120, a motor housing section 130, and a handle section 150. The front housing section 110 at least partially encloses and / or supports at least some of the components of the working assembly 200. The rear housing section 120 at least partially encloses and / or supports at least some of the components of the display assembly 1490 and defines a receptacle sized, shaped,and otherwise configured to receive and at least partially enclose and / or support the power supply 1500 and the controller 1600. The motor housing section 130 extends between and connects the bottoms of the front and rear housing sections 110 and 120 and at least partially encloses and / or supports at least some of the components of the working assembly 200, including the motor 1100. The handle housing section 150 extends between and connects the tops of the front and rear housing sections 110 and 120 and defines a handle used by the operator. This is merely one example, and in other embodiments the components of the strapping device may be supported and / or enclosed by any suitable portion of the housing 100. The housing 100 may be formed from any suitable quantity of components joined together in any suitable manner. In this example embodiment, the housing 100 is formed from plastic, though it may be made from any other suitable material in other embodiments.

[0022] The working assembly 200, which is best shown in Figures 3A-4B, includes the majority of the components of the strapping device 50 that are configured to carry out the strapping cycle to tension the strap around the load, attach the overlapping layers of the strap to one another, and cut the strap from the strap supply. The working assembly 200 includes a support 300, a tensioning assembly 400, a trigger 600, a sealing assembly 900, a transmission 1000, and a motor 1100.

[0023] The support 300, which is best shown in Figures 3A and 3B, serves as a direct or indirect common mount for the tensioning assembly 400, the trigger 600, the sealing assembly 900, the transmission 1000, and the motor 1100. The support 300 includes a base 300b and a frame 300f extending from the base 300b. The base 300b supports a toothed tension plate 312 below the tension wheel 400w of the tensioning assembly 400 (described below) and a toothed weld plate 314 below the weld shoe 942 of the sealing assembly 900 (described below).

[0024] The tensioning assembly 400 is operable via the motor 1100 to tension the strap around the load during the tensioning cycle. The tensioning assembly 400 includes a rocker 400r, tensioning-assembly gearing (not labeled), and a tension wheel 400w. The tension wheel 400w is supported by the tensioning-assembly gearing, which is in turn supported by the rocker 400r. The tensioning-assembly gearing is configured to rotate the tension wheel 400w about a tension-wheel rotational axis A400W in a tensioning rotational direction to tension the strap around the load. The tensioning assembly 400 is movably mounted to the support 300 via the rocker 400r and a tensioning-assembly mounting shaft 395 (Figures 3A and 3B) and configured to pivotrelative to the support 300 — and particularly relative to the base 300b of the support 300 and the tension plate 312 — about a rocker-pivot axis A or between a tensioning position (Figures 5A, 5B, and 5F) and a strap-insertion position (Figures 5C-5E). When the tensioning assembly 400 is in the tensioning position, the tension wheel 400w is adjacent to the tension plate 312 of the support 300 (or the upper surface of the upper layer of the strap if the strap has been inserted into the strapping device 50). When the tensioning assembly 400 is in the strap-insertion position, the tension wheel 400w is spaced-apart from the tension plate 312 to enable the overlapping upper and lower layers of the strap to be inserted between the tension wheel 400w and the tension plate 312. The weight of the tensioning assembly 400 and one or more springs or other biasing elements (not shown) bias the tensioning assembly 400 to the tensioning position.

[0025] The trigger 600 is operable (here, pivotable) to cause the tensioning assembly 400 to move from the tensioning position to the strap-insertion position. In this example embodiment, when the trigger 600 is pulled it triggers a switch that causes the motor 1100 to cooperate with the tensioning assembly 400 to pivot the tensioning assembly 400 from the tensioning position to the strap-insertion position. In other embodiments, the trigger 600 is operably connected to the tensioning assembly 400 via one or more mechanical linkages such that pulling the trigger 600 forces the tensioning assembly 400 to pivot from the tensioning position to the strap-insertion position.

[0026] The sealing assembly 900, which is best shown in Figures 4A, 4B, and 6A- 6C, is configured to attach overlapping portions of the strap to one another to form a tensioned strap loop around the load during the sealing cycle via friction welding. The sealing assembly 900 includes a first link arm 910, a second link arm 920, a first sealing-assembly biasing element 930, a second sealing-assembly biasing element 932, a weld arm 940, a weld shoe 942, a cutter 944, and an eccentric shaft (not shown). The weld shoe 942 is slidably mounted to the weld arm 940 such that the weld shoe 942 can oscillate relative to the weld arm 940 in the transverse direction of the strap (left and right from the perspective of Figures 6A-6C). The eccentric shaft is operably connected to the weld shoe 942 and configured to, when rotated, cause the weld shoe 942 to oscillate. A toothed belt 900b operably connects the transmission 1000 to a driven gear 905 to rotate the driven gear 905. The driven gear 905 is fixed in rotation with the eccentric shaft such that rotation of the driven gear 905 results in rotation of the eccentric shaft and oscillation of the weld shoe 942. The cutter 944 is removably mounted to the weld arm 940.

[0027] The weld arm 940 is pivotably mounted to the support 300 and is pivotable relative to the support 300 and the weld plate 314 about a weld-arm axis A940 between a home position (Figures 3A and 6A) in which the weld shoe 942 is spaced-apart from the weld plate 314 and a sealing position (Figures 4A and 6C) in which the weld shoe 942 is adjacent to the weld plate 314 and positioned to weld the strap. The first and second link arms 910 and 920 operably connect the transmission 1000 to the weld arm 940 such that the transmission 1000 can move the weld arm 940 from the home position to the sealing position. The first link arm 910 is pivotably mounted to the support 300 via a first pivot 900pl (such as a pivot pin). The second link arm 920 links the first link arm 910 to the weld arm 940. Specifically, one end of the second link arm 920 is pivotably connected to one end of the first link arm 910 via a second pivot 900p2 (such as a pivot pin), and the other end of the second link arm 920 is pivotably connected to the weld arm 940 via a third pivot 900p3 (such as a pivot pin). The first sealing-assembly biasing element 930 circumscribes the second link arm 920 and, as explained below, biases the sealing assembly 900 to its sealing configuration. The second sealing-assembly biasing element 932 biases the sealing assembly to its home configuration.

[0028] When the sealing assembly 900 is in the home configuration in which the weld arm 940 is in the home position — shown in Figures 3A and 6A — the first and second link arms 910 and 920 are oriented such that they form an angle greater than 0 degrees and less than 180 degrees (i.e., an acute or obtuse angle). When the sealing assembly 900 is in the sealing configuration in which the weld arm 940 is in the sealing position — shown in Figures 4A and 6C — the first and second link arms 910 and 920 form an angle greater than 180 degrees and less than 360 degrees (i.e., a reflex angle). As described in detail below, the transmission 1000 is configured to switch the sealing assembly 900 from its home configuration to its sealing configuration by manipulating the orientation of the first and second link arms 910 and 920.

[0029] The transmission 1000, which is best shown in Figures 3 A and 3B, is driven by the motor 1100, is operably connected to the tensioning assembly 400 and configured to cause the tension wheel 400w to rotate in the tensioning direction to tension the strap, and is operably connected to the sealing assembly 900 and configured to cause the sealing assembly 900 to attach the overlapping portions of the strap to one another. The transmission 1000 includes transmission gearing including a drive gear 1012 (which is a bevel pinion gear in this example embodiment) and a variable offset coupling 800. The transmission gearing and the variable offsetcoupling 800 are mounted to the support 300 such that the drive gear 1012 is configured to drive the variable offset coupling 800.

[0030] The transmission gearing 1010 includes suitable components (such as gears, bearings, and freewheels) that transmit rotational movement of the output shaft of the motor 1100 in a first drive direction to the drive gear 1012 to rotate the drive gear 1012 (but not to drive any components of the sealing assembly 900 in this example embodiment). The drive gear 1012 drives the variable offset coupling 800, which transmits the rotational movement of the drive gear 1012 to the tensioning-assembly gearing to rotate the tension wheel 400w.

[0031] The components of the transmission gearing 1010 transmit rotational movement of the output shaft of the motor 1100 in a second drive direction opposite the first drive direction to the sealing assembly 900 to switch the sealing assembly 900 from its home configuration to its sealing configuration and to drive the toothed belt 900b to rotate the driven gear 905 and the eccentric shaft and cause the weld shoe 942 to oscillate (but not to drive the drive gear 1012 in this example embodiment). More specifically, the transmission gearing 1010 includes a cam 1010c (Figure 6A) driven in rotation by the output shaft of the motor 1100 when the output shaft is rotated in the second drive direction. The cam 1010c engages the free end (not shown) of the first link arm 910 of the sealing assembly 900, which causes the first link arm 910 of the sealing assembly 900 to rotate clockwise about the first pivot 900pl (from the viewpoint shown in Figures 6A-6C) to raise the second pivot 900p2 and switch the sealing assembly 900 to the sealing configuration, thereby moving the weld arm 940 into its sealing position.

[0032] This is merely one example transmission assembly, and the strapping device may include any suitable transmission assembly or assemblies operably connecting one or more motors to the tensioning and sealing assemblies to drive those assemblies.

[0033] The motor 1100, which is best shown in Figures 3A and 3B, is operably connected to (via the transmission 1000) the tensioning assembly 400 and the sealing assembly 900 and is configured to drive those assemblies as explained herein. The motor 1100 includes the output shaft (not shown) referenced above. The motor 1100 is an electric motor in this example embodiment but may be any suitable motor.

[0034] The display assembly 1490, which is shown in Figures 1A-1C, includes a suitable display screen 1492 with a touch panel 1494. The display screen 1492 is configured to display information regarding the strapping device 50 (at least in this embodiment), and thetouch screen 1494 is configured to receive operator inputs such as the desired operating mode (described below), whether the strap-cleaning option (described below) is activated, a desired strap tension, and a desired weld cooling time. A display controller (not shown) may control the display screen 1492 and the touch panel 1494and, in these embodiments, is communicatively connected to the controller 1600 to send signals to the controller 1600 and to receive signals from the controller 1600. Other embodiments of the strapping device do not include a touch panel. Still other embodiments of the strapping device do not include a display assembly. Certain embodiments of the strapping device include a separate pushbutton panel instead of a touch panel beneath or integrated with the display screen.

[0035] The first and second pushbutton actuators 1410 and 1440 are operable to initiate the tensioning and / or sealing cycles as described below. Other embodiments of the strapping device 50 do not have pushbutton actuators and instead incorporate their functionality into the display assembly 1490. For instance, in one of these embodiments two areas of the touch panel define virtual buttons that have the same functionality as mechanical pushbutton actuators.

[0036] The controller 1600, which is shown in Figure 1C, 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 specialpurpose processor, a digital-signal processor, one or more microprocessors, one or more microprocessors in association with a digital-signal processor core, one or more applicationspecific 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 device 50. The controller 1600 is communicatively and operably connected to the motor 1100, the display assembly 1490, the pushbutton actuators 1410 and 1440, and the sensor(s) 1700 and configured to receive signals from and to control those components. The controller 1600 may also be communicatively connectable (such as via Wi-Fi, Bluetooth, near-field communication, or other suitable wireless communications protocol) to anexternal device, such as a computing device, to send information to and receive information from that external device.

[0037] The controller 1600 is configured to operate the strapping device in one of three operating modes to carry out the strapping cycle: (1) a manual operating mode; (2) a semiautomatic operating mode; and (3) an automatic operating mode. In the manual operating mode, the controller 1600 operates the motor 1100 to cause the tension wheel 400w to rotate responsive to the first pushbutton actuator 1410 being actuated and maintained in its actuated state. The controller 1600 operates the motor 1100 to cause the sealing assembly 900 to carry out the sealing cycle responsive to the second pushbutton actuator 1440 being actuated. In the semiautomatic operating mode, the controller 1600 operates the motor 1100 to cause the tension wheel 400w to rotate responsive to the first pushbutton actuator 1410 being actuated and maintained in its actuated state. Once the controller 1600 determines that the tension in the strap reaches the (preset) desired strap tension, the controller 1600 automatically operates the motor 1100 to cause the sealing assembly 900 to carry out the sealing cycle (without requiring additional input from the operator). In the automatic operating mode, the controller 1600 operates the motor 1100 to cause the tension wheel 400w to rotate responsive to the first pushbutton actuator 1410 being actuated. Once the controller 1600 determines that the tension in the strap reaches the (preset) desired strap tension, the controller 1600 automatically operates the motor 1100 to cause the sealing assembly 900 to carry out the sealing cycle (without requiring additional input from the operator).

[0038] The controller 1600 carries out the sealing cycle differently depending on whether the strap-cleaning option is active or inactivate. This occurs across all operating modes in this example embodiment. When the strap-cleaning option is active, during the sealing cycle, the controller 1600 controls the motor 1100 to operate to oscillate the weld shoe 942 at a first frequency for a first period and, after the first period, automatically and without additional operator input controls the motor 1100 to oscillate the weld shoe 942 at a second frequency greater than the first frequency for a second period. The oscillation of the weld shoe 942 at the first frequency for the first period results in some or all of any moisture or debris being driven from between the upper and lower strap layers, effectively cleaning them in preparation for sealing, but is slow enough so as not to locally melt the strap. The subsequent oscillation of the weld shoe 942 at the second, greater frequency generates friction and heat substantial enough tolocally melt and join the portions of the overlapping strap layers, thereby attaching the upper and lower strap layers to form the tensioned strap loop. The frequency of oscillation is controlled by the rotational speed of the output shaft of the motor 1100 — the higher the rotational speed of the output shaft, the higher the frequency of oscillation. The periods may be defined temporally, via the number of revolutions of the motor output shaft, or in any other suitable manner.

[0039] On the other hand, when the strap-cleaning option is inactive, during the sealing cycle, the controller 1600 controls the motor 1100 to oscillate the weld shoe 942 at a third frequency for a third period. In this example embodiment, the third frequency is equivalent to the second frequency and the third period is equivalent to the second period, though that may not be the case in other embodiments.

[0040] The sensors 1700 include any suitable sensors, such as microswitches, optical sensors, ultrasonic sensors, magnetic position sensors, and the like, configured to detect the position of certain components of the strapping device 50 and to send appropriate signals to the controller 1600. The sensors 1700 may include, for instance: one or more tensioning-assembly- position sensors configured to detect when the tensioning assembly 400 is in its tensioning position and / or its strap-insertion position; one or more trigger-position sensors configured to detect when the trigger 600 is pulled; and one or more actuating assembly sensors configured to detect actuation of the first and second pushbutton actuators 1410 and 1440.

[0041] The power supply 1500 is electrically connected to (via suitable wiring and other components) and configured to power several components of the strapping device 50, including the motor 1100, the display assembly 1490, the controller 1600, and the sensor(s) 1700. The power supply 1500 includes a rechargeable battery (such as a lithium-ion or nickel cadmium battery) in this example embodiment, though it may be any other suitable electric power supply in other embodiments. The power supply 1500 is sized, shaped, and otherwise configured to be received in the receptacle defined by the rear housing section 120 of the housing 100. The strapping device 50 includes one or more power-supply-securing devices (not shown) to releasably lock the power supply 1500 in place upon receipt in the receptacle. Actuation of a release device of the strapping device 50 or the power supply 1500 unlocks the power supply 1500 from the housing 100 and enables an operator to remove the power supply 1500 from the receptacle.

[0042] Figure 7 is a flowchart of one example embodiment of a strapping process 2000. The strapping process 2000 begins by tensioning a strap around a load, as block 2002 indicates. The strapping process 2000 continues by sandwiching overlapping upper and lower layers of the strap between a first weld plate and a second weld plate, as block 2004 indicates. The strapping process 2000 continues by oscillating the first weld plate relative to the second weld plate at a first frequency for a first period, as block 2006 indicates. This step may occur at least partially concurrently with step 2004. The strapping process 2000 continues by, after the first period, oscillating the first weld plate relative to the second weld plate at a second frequency greater than the first frequency for a second period to locally melt and join portions of the overlapping upper and lower strap layers to form a tensioned strap loop around the load, as block 2008 indicates. The strapping process 2000 concludes by, after the second period, stopping the oscillation of the first weld plate relative to the second weld plate, as block 2010 indicates.

[0043] Use of the strapping device 50 to carry out the strapping process 2000 to form a tensioned strap loop around a load is described below with reference to Figures 5A-6C. Initially, the tensioning assembly 400 is in its tensioning position and the sealing assembly 900 is in its home configuration, as shown in Figure 5A. The strapping device 50 is in the automatic mode for the purposes of this example, and the strap-cleaning option is active.

[0044] The operator pulls the strap S leading-end first from a strap supply (not shown), wraps the strap S around the load, and positions a lower layer LL including the leading end of the strap S below an upper layer UL of the strap S. The operator then pulls the trigger 600, as shown in Figure 5B, to lift the tensioning assembly 400 to its strap-insertion position, as shown in Figure 5C. With the tensioning assembly 400 in its strap-insertion position and while continuing to pull the trigger 600, the operator introduces the overlapping upper and lower layers UL and LL of the strap S between the tension wheel 400w and the tension plate 312 and between the weld shoe 942 and the weld plate 314, as shown in Figures 5D and 6A. The operator then releases the trigger 600, as shown in Figure 5E, enabling the appropriate biasing elements to force the tensioning assembly 400 pivot back to its tensioning position to sandwich the overlapping upper and lower strap layers UL and LL between the tension wheel 400w and the tension plate 312, as shown in Figure 5F.

[0045] The operator then actuates the first pushbutton actuator 1410. Once one of the sensors 1700 detects the actuation of the first pushbutton actuator 1410, the controller 1600initiates the strapping process 2000. The controller 1600 starts the tensioning cycle by controlling the motor 1100 to rotate the output shaft in the first drive direction. As explained above, the transmission 1000 transmits this rotational movement of the output shaft to the tensioning-assembly gearing which, in turn, rotates the tension wheel 400w about the tensionwheel rotational axis A400W in the tensioning direction. As the tension wheel 400w rotates in the tensioning direction, it pulls the upper layer UL of the strap S over the lower layer LL of the strap S, thereby tensioning the strap S around the load. Throughout the tensioning cycle, the controller 1600 monitors the current drawn by the motor 1100. When this current reaches a preset value that is correlated with the (preset) desired strap tension for this strapping cycle, the controller 1600 stops the motor 1100, thereby terminating the tensioning cycle.

[0046] In this example embodiment, after completion of the tensioning cycle, the controller 1600 automatically starts the sealing cycle by controlling the motor 1100 to begin rotating the output shaft in the second drive direction at a first rotational speed and starting a first countdown timer. This causes the transmission 1000 to drive the toothed belt 900b to begin rotating the eccentric shaft and oscillating the weld shoe 942 at a first frequency and to switch the sealing assembly 900 from its home configuration to its sealing configuration, and in doing so pivot the weld arm 940 to its sealing position. As the weld arm 940 reaches the sealing position, the weld shoe 942 forces the overlapping upper and lower layers of strap UL and LL against the weld plate 314 while the cutter 944 cuts the upper strap layer UL from the strap supply. Figures 6B and 6C show this movement of the weld arm 940 and oscillation of the weld shoe 942. As explained above, the first frequency of oscillation of the weld shoe 942 is fast enough to drive some or all of any moisture or debris from between the upper and lower strap layers UL and LL, effectively cleaning them in preparation for sealing, but is slow enough so as not to locally melt them.

[0047] In this example embodiment, after the controller 1600 determines that the first countdown timer has expired, the controller 1600 controls the motor 1100 to rotate the output shaft in the second drive direction at a second rotational speed that is greater than the first rotational speed and starts a second countdown timer. This causes the transmission 1000 to drive the toothed belt 900b to rotate the eccentric shaft and oscillate the weld shoe 942 at a second frequency that is greater than the first frequency. As explained above, the second frequency is great enough to generate friction and heat substantial enough to locally melt and join the portionsof the overlapping strap layers, thereby attaching the upper and lower strap layers UL and LL to form the tensioned strap loop.

[0048] In this example embodiment, after the controller 1600 determines that the second countdown timer has expired, the controller 1600 controls the motor 1100 to stop rotating the output shaft, completing the sealing cycle. The operator can then pull the trigger 600 to raise the tensioning assembly 400 and to switch the sealing assembly 900 back to its home configuration to release the tensioned strap loop.

[0049] In this example embodiment, the strap-cleaning option can be activated or deactivated by the operator as desired. In other embodiments, the strap-cleaning option is not an option and is instead always active.

[0050] The above-described example embodiment of the strapping device includes a single motor configured to drive both the tensioning assembly and the sealing assembly. In other embodiments, the strapping device includes separate motors configured to drive the respective tensioning and sealing assemblies and may include separate transmissions for each motor.

[0051] Other embodiments of the strapping device may include fewer assemblies, components, and / or features than those included in the strapping device 50 described above and shown in the Figures. In other words, while the strapping device 50 includes all of the assemblies, components, and features described above, they are independent of one another and may be independently included in other strapping devices.

[0052] While the strapping device described above is a handheld strapping device, the strapping device may be any other suitable strapping device in other embodiments, such as a standalone automatic or semi-automatic strapping machine.

Claims

Claims1. A strapping device comprising: a tensioning plate; a rotatable tensioning wheel adjacent the tensioning plate; a first weld plate; a second weld plate, wherein the first weld plate is movable toward and away from the second weld plate; a motor operably connected to one of the first and second weld plates; and a controller configured to control the motor to:(a) oscillate the one of the first and second weld plates relative to the other of the first and second weld plates at a first frequency for a first period;(b) after the first period, oscillate the one of the first and second weld plates relative to the other of the first and second weld plates at a second frequency for a second period, wherein the second frequency is greater than the first frequency; and(c) after the second period, stop oscillating the one of the first and second weld plates relative to the other of the first and second weld plates.

2. The strapping device of claim 1, the controller is configured to carry out (a)-(c) responsive to initiation of a sealing cycle with a strap-cleaning option active.

3. The strapping device of claim 2, wherein the controller is further configured to, responsive to initiation of the sealing cycle with the strap-cleaning option inactive: oscillate the one of the first and second weld plates relative to the other of the first and second weld plates at a third frequency for a third period; and after the third period, stop oscillating the one of the first and second weld plates relative to the other of the first and second weld plates.

4. The strapping device of claim 3, wherein the second frequency and the third frequency are substantially the same.

5. The strapping device of claim 4, wherein the second period and the third period are substantially the same.

6. The strapping device of claim 4, wherein the second and third periods are longer than the first period.

7. The strapping device of claim 1, wherein: the first period comprises one of: a first preset time period and a first preset quantity of revolutions of an output shaft of the motor; and the second period comprises one of: a second preset time period and a second preset quantity of revolutions of the output shaft of the motor.

8. The strapping device of claim 1, wherein the controller is configured to control the motor to oscillate the one of the first and second weld plates relative to the other of the first and second weld plates at: the first frequency by controlling the motor to rotate an output shaft of the motor at a first rotational speed; and the second frequency by controlling the motor to rotate the output shaft of the motor at a second rotational speed, wherein the second rotational speed is greater than the first rotational speed.

9. The strapping device of claim 1, further comprising: a support comprising the second weld plate; and a weld arm supporting the first weld plate such that the first weld plate is oscillatable relative to the weld arm and the second weld plate, wherein the weld arm is pivotable relative to the second weld plate to move the first weld plate toward and away from the second weld plate.

10. The strapping device of claim 9, further comprising an eccentric shaft operably connected to the first weld plate such that rotation of the eccentric shaft causes the first weld plate to oscillate relative to the second weld plate, wherein the motor is operably connected to the eccentric shaft to rotate the eccentric shaft, wherein the controller is configured to control the motor to oscillate the first weld plate relative to the second weld plate at:the first frequency by controlling the motor to rotate an output shaft of the motor at a first rotational speed; and the second frequency by controlling the motor to rotate the output shaft of the motor at a second rotational speed, wherein the second rotational speed is greater than the first rotational speed.

11. A method of operating a strapping device, the method comprising: tensioning a strap around a load such that an upper layer of the strap and a lower layer of the strap are positioned between a first weld plate and a second weld plate; moving the first weld plate to sandwich the upper and lower layers of the strap between the first and second weld plates; oscillating one of the first and second weld plates relative to the other of the first and second weld plates at a first frequency for a first period; after the first period, oscillating the one of the first and second weld plates relative to the other of the first and second weld plates at a second frequency for a second period to locally melt and join portions of the upper and lower layers of the strap, wherein the second frequency is greater than the first frequency; and after the second period, stopping the oscillation of the one of the first and second weld plates relative to the other of the first and second weld plates.

12. The method of claim 11, wherein the second period is longer than the first period.

13. The method of claim 11, wherein oscillating the one of the first and second weld plates relative to the other of the first and second weld plates comprises controlling a motor operably connected to the one of the first and second weld plates.

14. The method of claim 13, wherein: the first period comprises one of: a first preset time period and a first preset quantity of revolutions of an output shaft of the motor; and the second period comprises one of: a second preset time period and a second preset quantity of revolutions of the output shaft of the motor.

15. The method of claim 11 , further comprising oscillating the one of the first and second weld plates relative to the other of the first and second weld plates at: the first frequency by controlling the motor to rotate an output shaft of a motor at a first rotational speed; and the second frequency by controlling the motor to rotate the output shaft of the motor at a second rotational speed, wherein the second rotational speed is greater than the first rotational speed.

16. The method of claim 11, wherein moving the first weld plate to sandwich the upper and lower layers of strap between the first and second weld plates comprises pivoting a weld arm supporting the first weld plate toward a support comprising the second weld plate.

17. The method of claim 16, further comprising rotating an eccentric shaft operably connected to the first weld plate to cause the first weld plate to oscillate relative to the second weld plate.

18. The method of claim 17, further comprising controlling a motor to rotate the eccentric shaft.

19. The method of claim 18, further comprising controlling the motor to pivot the weld arm.

20. The method of claim 19, further comprising oscillating the first weld plate relative to the second weld plates at: the first frequency by controlling the motor to rotate an output shaft of a motor at a first rotational speed; and the second frequency by controlling the motor to rotate the output shaft of the motor at a second rotational speed, wherein the second rotational speed is greater than the first rotational speed.

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