Patent Application
20210309401
The present disclosure relates to wrapping apparatuses, namely apparatuses for wrapping a load with a web of film. More particularly, the present disclosure relates to a film dispenser for such wrapping apparatuses.
Typical loads, such as a bundle of grouped items, have a rectangular cross-section or other non-circular cross-sections. Due to corner variations which change the effective wrapping radius, such loads present a fluctuation in their demand for film web when the film web is wrapped around their periphery. More particularly, when a relative rotation is provided between the load and the film dispenser, the film dispenser needs to accelerate or decelerate around the load corners to maintain a constant film tension on the load.
The film feed requirement of a load can be sensed by a dancer bar. Dancer bars used in conventional film dispensers are generally biased towards a first position with non-linear biasing means, i.e., the force exerted by the non-linear biasing means generally increases with an increasing displacement. Such non-linear biasing means are difficult to model, and their control remains a challenge, notably because the system behaviour, as well as its reaction, vary in accordance with the position of the dancer bar relative to the first position.
There is a need in the industry for a film dispenser for a wrapping apparatus that alleviates at least in part the deficiencies of existing film dispensers and seeks to solve problems and drawbacks of the prior art.
In accordance with one aspect, there is provided a film dispenser for a wrapping apparatus, including:
In some embodiments, a value of the constant force is adjustable.
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the displacement of the dancer bar is a translation between the first position and the at least one second position.
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the first and second axes are substantially parallel one to another.
In some embodiments, the displacement of the dancer bar is a rotation between the first position and the second position and the dancer bar is rotatable about a rotation axis.
In some embodiments, the dancer bar control assembly includes a rotatory servo motor operatively connected to a first end of the dancer bar, the rotatory servo motor being configured to detect and guide a rotation of the first end about the rotation axis.
In some embodiments, the rotatory servo motor is configured to measure an angular displacement of the dancer bar.
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the threshold is a tension value.
In some embodiments, the threshold is about 10 pounds.
In some embodiments, the threshold is adjustable.
In some embodiments, wherein the dispenser roller is configured to support a roll of the material web and is located upstream of the pre-stretch assembly and wherein the pre-stretch assembly includes:
In some embodiments, second pre-stretch roller is mechanically connected to the first pre-stretch roller with a belt.
In some embodiments, the pre-stretch motor is operatively connected to the second pre-stretch roller.
In some embodiments, the pre-stretch motor is operatively connected to a roller mechanically connected to the second pre-stretch roller, the roller being mechanically connected to the second pre-stretch roller with a belt.
In some embodiments, the film dispenser motor is in driving engagement with the film dispenser, the film dispenser motor driving the film dispenser in relative rotation with respect to a load.
In accordance with another aspect, there is provided a film dispenser for a wrapping apparatus, including:
In accordance with another aspect, there is provided a method for dispensing a film, including:
In some embodiments, the method of claim includes pre-stretching the material web.
In some embodiments, monitoring the displacement of the dancer bar includes monitoring a translation of the dancer bar between a first angular position and at least one second angular position.
In some embodiments, monitoring the displacement of the dancer bar includes monitoring a rotation of the dancer bar between a first position and at least one second position.
In some embodiments, the threshold is a tension value.
In some embodiments, the threshold is comprised in a range extending from about 1 pound to about 20 pounds.
In some embodiments, the method further includes adjusting the threshold.
In accordance with another aspect, there is provided a film dispenser for a wrapping apparatus, including:
In some embodiments, the value of the constant force is adjustable.
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the displacement of the dancer bar is a translation between the first position and the at least one second position.
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the first and second axes are parallel one to another.
In some embodiments, the displacement of the dancer bar is a rotation between the first position and the second position and the dancer bar is rotatable about a rotation axis.
In some embodiments, the dancer bar control assembly includes a rotatory servo motor operatively connected to a first end of the dancer bar, the rotatory servo motor being configured to detect and guide a rotation of the first end about the rotation axis.
In some embodiments, the rotatory servo motor is configured to measure an angular displacement of the dancer bar.
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the dancer bar control assembly includes:
In some embodiments, the threshold is a tension value.
In some embodiments, the threshold is comprised in a range extending from about 1 pound to about 20 pounds.
In some embodiments, the threshold is adjustable.
In some embodiments, the film dispenser motor is in driving engagement with the film dispenser, the film dispenser motor driving the film dispenser in relative rotation with respect to a load.
These and other aspects of the technology will now become apparent to those of ordinary skill in the art upon review of the following description of embodiments of the technology in conjunction with the accompanying drawings.
A detailed description of the embodiments of the present technology is provided herein below, by way of example only, with reference to the accompanying drawings, in which:
In the drawings, embodiments of the technology are illustrated by way of examples. It is to be expressly understood that the description and drawings are only for the purpose of illustration and are an aid for understanding. They are not intended to be a definition of the limits of the technology.
Before any variants, examples or embodiments of the technology are explained in detail, it is to be understood that the technology is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The technology is capable of other variants or embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional suitable items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. Additionally, the words “lower”, “upper”, “upward”, “down” and “downward” designate directions in the drawings to which reference is made. Similarly, the words “left”, “right”, “front” and “rear” designate locations or positions in the drawings to which reference is made. The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import.
Variants, examples and embodiments of the technology are described hereinbelow.
The need for the film dispenser and related methods which will be described in the current description arises, inter alia, from the fact that the dancer bars of prior art are typically biased towards their initial position (sometimes referred to as a “zero position” or a “first position”) with non-linear biasing means, meaning that the force exerted by the non-linear biasing means on the dancer bar increases with increasing displacement. Systems including such non-linear biasing means and methods relying on the same are known to be difficult to model, and so to control, since the system's behaviour generally varies depending on the relative position of the dancer bar with respect to its zero position.
The present disclosure addresses the need for a system and related methods in which a constant force can be generated over the entire displacement range or working range (or “stroke”) of the biasing assembly or means. Even though the generated force is constant over the entire displacement range or working range (or “stroke”), the force is adjustable (i.e., the magnitude of the constant force can be modified, changed, varied, or adjusted). As it will be described in greater detail below, such a system and related methods can be useful for providing feedback during a wrapping cycle of a load without creating tension peaks, thereby mitigating, or eliminating the negative effects generally associated with such tension peaks. Tension peaks may cause, for example, and without being limitative, damages in the material web or film being dispensed on the load, improper or non-optimal stretching of the material web (in the case of stretchable material webs), and many other issues that may negatively affect or compromise the wrapping cycle of the loads.
Referring to
As illustrated, the film dispenser 20 includes a roll support 22 for rotatably supporting a roll of a material web 24 (sometime referred to as a “wrapping film”) to be dispensed. Of note, the roll support 22 is sometimes referred to as a “dispenser roller”. The material web 24 may be a film made from any types of material such as, to name a few, polymer, plastic, paper, and many others. It should be noted that the material web 24 may either be stretchable, non-stretchable, or exhibit a certain degree of stretchability. The selection of adequate materials and/or properties (e.g., stretchability) for the material web 24 may depend on a plurality of factors, such as, for example, and without being limitative, dimensions of the loads, geometry of the loads, the nature of the products being wrapped, shipping conditions, and many other parameters that would be readily identified as being relevant for a person skilled in the art. In some embodiments, the material web 24 may be a polymeric film dispensed in a web form. The roll support (or dispenser roller) 22 is sized and configured for supporting a roll of the material web 24.
In some embodiments, such as the one illustrated in
As illustrated in
In the depicted embodiment of
In the embodiment shown in
The film dispenser 20 includes a dancer bar 38 (sometimes referred to as “dancer roller” or “dancer arm”). In some embodiments, the dancer bar 38 is free to pivot or translate in response to variations in film demand, which will be referred to as variations of a film feed requirement.
The film dispenser 20 includes a dancer bar control assembly 40 including a biasing actuator 47 configured to bias the dancer bar 38 towards its zero position and a sensor 49 configured to monitor the position of the dancer bar 38 relative to the zero position. In the illustrated embodiment, the dancer bar control assembly 40 is shown as being connected to the dancer bar 38, but one would readily understand that such a connection is only schematic and serves the purpose of illustrating the operational relation between the dancer bar 38 and the dancer bar control assembly 40. In some embodiments, the dancer bar control assembly 40 may include a controller 51 operatively connected to at least one of the biasing actuator 47, the sensor 49, the pre-stretch motor 36 of the pre-stretch assembly 26 and the film dispenser motor 28. As illustrated in
The dancer bar control assembly 40 is configured to bias the dancer bar 38 with a constant force over the whole displacement range of the dancer bar 38 (i.e., the displacement between the first position and the at least one second position). In the context of the current description, the expression “bias” refers to the fact that the dancer bar control assembly 40 is configured to exert a force on the dancer bar 38. As it will be explained in greater detail below, the force can either be a translational force or a rotational force, depending on the configuration of the dancer bar control assembly 40. The biasing force exerted by the dancer bar control assembly 40 is substantially constant over the entire displacement range of the dancer bar 38. In some implementations, the constant force is adjustable, meaning that the force, when set, remains constant over the entire displacement range, but that the value of the force can be adjusted, modified, altered, or determined a priori. The dancer bar control assembly 40 is also configured to monitor a displacement of the dancer bar 38, for example using the actuator 47, the sensor 49 and/or the controller 51 and determine the film feed requirement based on the displacement of the dancer bar 38. The expression “monitor” herein refers to detecting, measuring, recording, watching and/or observing the displacement of the dancer bar 38. The dancer bar control assembly 40 (e.g., the controller 51) is also configured to generate a speed command based on the film feed requirement and send the speed command towards the pre-stretch assembly 26 to adjust the film delivery speed, thereby compensating for the variation of the film feed requirement during the wrapping cycle. As such, the dancer bar control assembly 40 receives the displacement of the dancer bar 38 as an input and produces a command, namely a speed command, as an output, the command being a dispenser motor 28 (e.g., when the film dispenser 20 does not include a pre-stretch assembly 26, as illustrated in
In some embodiments, such as the one illustrated in
It is understood that the dancer bar 38 has one first position but can have one or more second positions. More particularly, the expression “second position” refers to any position(s) different than the first position. The displacement of the dancer bar 38 from the first position towards the second position(s) can be a translation or a rotation. The displacement range includes at least the first and the second position and is continuous. In some embodiments, the dancer bar 38 can continuously move from the first position to the second position upon the variation of the film feed requirement.
In the illustrated embodiment of
Referring to
As previously presented, the film dispenser 20 may include, in some embodiments, a pre-stretch assembly 26 configured to pre-stretch a material web 24 and provide the material web 24 at a film delivery speed (see for example
In some embodiments, the film dispenser 20 includes a dancer bar 38 positioned downstream of the pre-stretch assembly 26 and engageable with the material web 24, such that, in response to a variation of a film feed requirement, the dancer bar 38 is movable (either translatable or rotatable) over a displacement range between a first position and at least one second position. The dancer bar 38 may be in the first position when a tension in the material web 24 is below a threshold and may be in the at least one second position when the tension in the material web 24 is equal or above the threshold. For example, in some implementations, the dancer bar 38 can either move from the first position towards the at least one second position (referred as the “second position”) when the tension in the material web 24 is equal or above the threshold or remain in the first position when the tension in the film is below the threshold. The position of the dancer bar 38 when the tension is equal or above the threshold is generally correlated to the tension applied thereon by the material web 24 as it is supplied. In some embodiments, the dancer bar 38 includes a pivoting roller which pivots as the load demands more or less film fed.
In some embodiments, the dancer bar control assembly 40 is embodied by a feedback control loop. In some embodiments, the feedback control loop may be operatively connected to the dancer bar 38 and to the pre-stretch assembly 26 (when the film dispenser includes a pre-stretch assembly 26, see for example
As already described in the context of the current disclosure, the dancer bar control assembly 40 is configured to exert a constant force (e.g., tension), i.e., a substantially non-variable force on the dancer bar 38, despite the displacement of the dancer bar 38. As such, the constant force is said to be independent from the displacement of the dancer bar 38. Amongst other, the dancer bar control assembly 40 according to the current disclosure differs from other biasing assemblies, such as, for example and without being limitative, biasing assemblies of prior art exerting a variable force on the dancer bar (by contrast to the dancer bar control assembly 40 exerting a constant force over the entire displacement range of the dancer bar 38). These assemblies of prior art that apply a variable force are generally such that the force being exerted on the dancer bar is typically greater as the displacement increases.
In a first example of dancer bars from prior art, the dancer bar is coupled with a biasing means including a torsion spring, which biases the dancer bar towards the first position. In a second example of dancer bars from prior art, the dancer bar is mounted through a non-linear biasing means including a pulley and a cable operatively connected to a spring. In these two examples from prior art, the dancer bar is biased towards its original (first) position in such a way that the force exerted on the dancer bar increases as the displacement increases (i.e., the force to be exerted increases with the displacement). In the assemblies of prior art, the position of the dancer bar is typically sensed or monitored by a cam. The cam is operatively connected to a controller which, in turn, is operatively connected to a film dispenser actuator, such as, for example and without being limitative, a motor. The rotation speed of the motor, which is associated with the film dispensing speed can be adjusted in a closed feedback control loop, based on the position of the dancer bar. However, adjusting the film dispensing speed with the closed feedback control loop is associated with a delay between the demand for the web material and the adjustment of the film dispensing speed. Furthermore, the fact that the force increases as the displacement increases makes the modeling of such assemblies of prior art relatively complex.
The dancer bar control assembly 40 according to the current disclosure mitigates the abovementioned challenges by providing an adjustable yet constant force over the entire range of displacement (translational or rotational) of the dancer bar 38. The adjustable and constant force can be useful, for example and without being limitative, for varying the amount of tension during the wrapping cycle, thereby reducing, or eliminating, tension peaks. For instance, the adjustable constant force allows to wrap a one load with a tight web material and to wrap another load with a more flexible (i.e., less tight, or looser) web material. The adjustable and constant force could also be useful to wrap a first portion and a second portion of a load with different level of tension (e.g., the first portion could be the lower portion of the load and could be more tightly wrapped than the second portion, which would be the upper portion of the load in this example). Such an adjustable and constant force could also be useful when the film demand varies during a wrapping cycle, for example and without being limitative in portions located near or at the corners of the load.
Different embodiments employing or relying on a dancer bar control assembly 40 will now be described.
In some embodiments, such as the one illustrated in
In these embodiments, the linear displacement of the dancer bar 38 is monitored and controlled by the first and/or second linear servo motors 46,52 located at each end of the dancer bar 38. The first and second linear servo motors 46,52 can bias the dancer bar 38 with a constant force along the displacement range of the dancer bar 38 in response to a variation in the film feed requirement. In some embodiments, the force is adjustable, meaning its set-point can be adjusted and/or predetermined. In some embodiments, the first and second linear servo motors 46,52 are configured to monitor, detect, and measure the translational position (or a variation thereof) of the dancer bar 38 in real-time or near real-time. More particularly, at least one of the first and second linear servo motors 46,52 is configured to track the translational positioning of the dancer bar 38. When the first and/or second servo motors 46,52 detect that the dancer bar 38 is in the first position (i.e., when there is no tension applied on or to the dancer bar 38, or when the tension is below or equal to the threshold), the first and second linear servo motors 46,52 remain in standby. However, when the threshold is reached, the dancer bar 38 moves towards the second position, following a translational movement. The first and second servo motors 46,52 are configured to measure the linear displacement of the dancer bar 38 and bias the dancer bar 38 with a constant force. Upon detection of a displacement equal or above the threshold, the first and second servo motors 46,52 are configured to send a speed command to the pre-stretch assembly 26 (or the film dispenser) to adjust the film delivery speed, thereby engaging the dancer bar 38 in translation towards its first position. Appropriate sensor(s), actuator(s) and/or controller(s), such as the ones which have been previously described, could be used. For example, and without being limitative, the embodiment illustrated in
Now turning to
In some embodiments, such as the one illustrated in
In some embodiments, such as the one illustrated in
The magnetic assembly 62 may include a permanent magnet (not shown in the Figures) mounted inside the dancer bar 38. For example, and without being limitative, the permanent magnet can be mounted near the first end of the dancer bar 38. Alternatively, the permanent magnet could be mounted elsewhere within the dancer bar 38, such as the second end. The magnetic assembly 62 also includes an inductive magnet 64, which may include an electrical conductor, mounted around the dancer bar 38. The inductive magnet 64 may be mounted around the dancer bar 38 near or at the first or second end, depending on the positioning of the permanent magnet. The configuration of the magnetic assembly 62 is such that the electrical conductor is provided around of or around at least a portion of the permanent magnet. In some embodiments, the inductive magnet 64 may be mounted inside the dancer bar 38, and the permanent magnet mounted around the dancer bar 38. Appropriate sensor(s), actuator(s) and/or controller(s), such as the ones which have been previously described, could be used.
The sensor is operatively connected to the magnetic assembly 62 and is configured to measure an angular position of the dancer bar 38. The magnetic assembly 62 biases the dancer bar 38 towards its first position.
In some embodiments, the permanent magnet is inserted in the dancer bar 38, at an end portion thereof, and an adjustable inductive magnet may be mounted to the frame and around the end portion of the dancer bar 38 including the permanent magnet. The angular position of the dancer bar 38 is monitored and controlled using the combination of the permanent and adjustable inductive magnet 64 and the sensor.
In some embodiments, such as the one illustrated in
In some embodiments, the cable 72 is engaged with a pulley mounted to the shaft of the dancer bar 38 at an end thereof. The cable 72 is inserted in an adjustable magnet providing a constant force. The angular position of the dancer bar 38 and/or the linear position of the cable 72 with respect to the adjustable magnet 68 or the pulley (e.g., a portion being wound thereon) can be monitored by monitoring the position of the cable 72.
In some embodiments, the magnetic spring 68 is a MagSpring (as commercialize by LinMot®). Such a magnetic spring can supply a constant force for any position of the spring. In some embodiments, the force can be adjusted but remains constant for any positions of the spring, which could be suitable for adjusting the force, depending on the load being wrapped or the wrapping phase. For instance, it is sometimes required to provide a higher value of tension while going upward and a lower value of tension while wrapping downwardly. The magnetic spring 68 could be used with a controller or a detector.
In some embodiments, the threshold is a tension value. The threshold could be, for example and without being limitative, about 10 pounds. The threshold is generally included in a range extending from about 1 pound to about 20 pounds. The threshold can be adjustable, i.e., the value of the threshold can be changed (by an operator and/or automatically).
In some embodiments, the dancer bar control assembly 40 is operatively connected to the pre-stretch assembly 26 and to the dancer bar 38, the dancer bar control assembly 40 being configured to bias the dancer bar 38 with a constant force over the displacement range, receive a measured position of the dancer bar 38 and adjust the film delivery speed to compensate for the variation of the film feed requirement based on the measured position.
Now turning to
It is understood that the above examples of the film dispenser 20 may be used in a related method. Broadly described, the method includes a first general step of providing a material web 24 at a film delivery speed. The method includes engaging a dancer bar 38 with the material web 24 such that, in response to a variation of a film feed requirement, the dancer bar 38 is configured to move from a first position towards at least one second position when a tension in the material web 24 is above a threshold and remains in the first position when the tension in the film is below or equal to the threshold. The method includes biasing the dancer bar 38 with a constant force over the displacement range of the dancer bar 38, as it has been previously described. The method includes monitoring a position of the dancer bar 38. The method also includes adjusting the film delivering speed based on the displacement of the dancer bar 38, thereby compensating for the variation of the film feed requirement.
In some embodiments, the method includes operating the dancer bar control assembly 40 to bias the dancer bar 38 with a constant force over the displacement range, monitor a displacement of the dancer bar 38 and generate a speed command based on the monitored displacement of the dancer bar 38 and send the speed command towards a motor of the film dispenser (e.g., the film dispenser motor 28) or the pre-stretch motor 26 adjust the film delivery speed.
In some embodiments, the method includes pre-stretching the web material.
In some embodiments, the method includes monitoring a linear displacement of the dancer bar 38, i.e., monitoring a translation of the dancer bar 38 between a first position and at least one second position.
In other embodiments, the method includes monitoring an angular position of the dancer bar 38, i.e., a rotation of the dancer bar 38 between a first position and at least a second position.
In some embodiments, the threshold is a tension value. The threshold can be, for example and without being limitative, comprised in a range extending from about 1 pound to about 20 pounds. In some embodiments, the tension value is about 10 pounds. The method could include a step of adjusting the threshold, for example in the circumstances in which the threshold is an adjustable value.
Several alternative embodiments and examples have been described and illustrated herein. The embodiments described above are intended to be exemplary only. A person skilled in the art would appreciate the features of the individual embodiments, and the possible combinations and variations of the components. A person skilled in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive. Accordingly, while specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the scope defined in the appended claims.
This application claims priority under 35 USC § 119(e) of U.S. provisional patent application 63/006,326 filed Apr. 7, 2020, the specification of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63006326 | Apr 2020 | US |
