A winding apparatus for production of web tubular film rolls

Abstract

Disclosed herein is a winding apparatus for winding of web tubular film rolls, the winding apparatus comprising a hot melt unit and a winding shaft. The present disclosure further relates to a web tubular film roll making machine for making web tubular film rolls and a process for making web tubular film rolls.

Description

Technical Field

[0001] The invention relates to a winding apparatus for winding of web tubular film rolls, the winding apparatus comprising a hot melt unit and a winding shaft. The present invention further relates to a web tubular film roll making machine for making web tubular film rolls and a process for making web tubular film rolls.Background art

[0002] In the realm of flexible packaging and industrial materials, the production of web tubular film rolls stands as a cornerstone process that bridges the gap between raw materials and finished goods. Web tubular films find extensive utility in packaging, transportation, agriculture, and various other industries due to their exceptional durability, flexibility, and barrier properties.

[0003] The process of creating these web tubular film rolls involves multiple intricate steps, with the winding apparatus playing a pivotal role in achieving the desired end product. The winding apparatus is an integral component of the overall film production line, responsible for taking the continuous extruded flat film, often several meters in width, and transforming it into tightly wound, uniformly structured rolls.

[0004] The significance of the winding apparatus lies not only in its role in shaping the end product but also in its influence on critical quality parameters such as roll tension, alignment, and overall consistency. A well-designed winding apparatus can directly impact the overall production efficiency, material utilization, and end-product performance.

[0005] Over the years, advancements in materials science, manufacturing technologies, and automation have led to the evolution of winding apparatus designs. Traditional winding methods often relied heavily on manual intervention, limiting production rates and introducing human error. However, modern winding apparatuses incorporate sophisticated automation, precision controls, and real-time monitoring systems that enhance winding efficiency, reduce defects, and ensure consistent roll quality.

[0006] In the present landscape, considerations such as film thickness, composition, intended application, and end-user requirements all influence the design and capabilities of winding apparatuses. Innovations in friction control, tension management, roll alignment, and defect detection have propelled the industry forward, enabling manufacturers to produce web tubular film rolls that meet stringent quality standards and cater to diverse application needs.

[0007] As industries continue to demand higher efficiency, sustainability, and product performance, the winding apparatus's role remains critical in ensuring that web tubular film rolls are produced reliably and consistently. It is thus an object of the present invention to build even further supply this demand, especially within the area of sustainability.Summary

[0008] Disclosed herein in a first aspect is a winding apparatus for production of web tubular film rolls, the winding apparatus comprising: a hot melt unit; and a winding shaft; wherein the winding apparatus is configured for receiving a web tubular film; wherein the hot melt unit is located upstream of the winding shaft; wherein the hot melt unit is configured for applying a hot melt to a bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by the winding shaft onto the core, the core being positioned on the winding shaft; wherein the winding shaft is arranged to be rotated around its own axis and to receive the web tubular film to be winded up onto the core; and wherein the winding shaft is further arranged to wind up a predetermined length of the web tubular film onto the core hereby creating the web tubular film roll.

[0009] By the above disclosed first aspect of the present invention, and the below disclosed aspects, it will be possible to apply a hot melt from the bottom side just before winding the web tubular film onto a new core. The first contact point of the web tubular film after being applied with hot melt is the core (may also be called a roll). The timing for the contact between core and hot melt may further be synchronized with a cutter / breaker bar in order to prevent unforeseen wrap around at the core.

[0010] The web tubular film is hereby glued to the core or to itself.

[0011] The step of gluing to the core is today often done with double-adhesive tape provided on the core prior to winding the web tubular film onto the core. However, if hot melt is applied to one side (herein defined as the bottom side) of the web tubular film it may glue the web tubular film to the core, and hereby the step of adding double adhesive tape to the core is omitted.

[0012] If the adhesive or hot melt is applied to one side of the web tubular film after a short distance from a first end of the web tubular film, this distance corresponding to one winding on the core, the web tubular film will be adhered to the core by gluing the web tubular film to the web tubular film itself, and not to the core. This means that the innermost part of the web tubular film is glued to itself, and this part of the film would go to waste, however, it would anyway in the traditional method with the double-adhesive tape. Therefore, by gluing the web tubular film to itself, the core may be recycled, as it would not comprise any residual glue or hot melt once the web tubular film has been removed. This means that the cores can be recycled if the hot melt is not on the core itself.

[0013] When the adhesive or hot melt is applied to one side of the web tubular film after a short distance from a first end of the web tubular film, such that the web tubular film is adhered to itself, the hot melt is preferably applied such that it will be located between the first and second layer of the web tubular film seen / counted from the core and out. During this process, it may further be preferred that a cutter arrangement (or a breaker bar) is assisting the winding shaft in the first couple of windings on a new core, such that both the first and second layer of web tubular film winded onto the core is tightly wrapped around the core. Even further, this may additionally be assisted by the use of pressurised air or other forms of air to assist in the wrap around.

[0014] A hot melt refers to a type of thermoplastic adhesive that is solid at room temperature but becomes liquid and adhesive when heated. It is commonly used in various industrial and commercial applications due to its quick-setting properties and strong bonding capabilities. The hot melt adhesive is typically supplied in the form of solid pellets, sticks, or blocks, which are loaded into a hot melt glue gun or hot melt applicator. The glue gun or applicator heats the adhesive, melting it into a liquid state, which can then be applied to the desired surface, in this case the bottom side of the film. In the present content, hot melt is also referred to as glue and / or adhesive.

[0015] In one or more embodiments, the winding apparatus further comprises at least one spindle, wherein the at least one spindle is configured for guiding the web tubular film from the hot melt unit to the winding shaft.

[0016] A winding apparatus as disclosed herein is a unit for winding-up web tubular films, or alternatively bags or strips / lines of interconnected individual bags that create bags when individualized, such as plastic bags to create bag rolls hereof. Thus, in one or more embodiments, the web tubular film is web tubular film that has already been formed into bags or strips / lines of interconnected individual bags.

[0017] The winding apparatus is a mechanical device used in the packaging industry to efficiently roll and material onto a roll, core, tube, or a spool for easy storage and dispensing.

[0018] A winding apparatus is commonly employed in factories or facilities that produce large quantities of bags, such as plastic bags, for various purposes, such as grocery bags, trash bags, or other disposable plastic bags, or that produce web tubular film for later production of such bags.

[0019] A winding apparatus may typically comprise one or more of the following components: A winding shaft: This part holds the core or spool onto which the web tubular films, or alternatively bags or strips / lines of interconnected individual bags will be wound or creates the centre at which the web tubular films, or alternatively bags or strips / lines of interconnected individual bags will be wound. The core is a cylindrical tube around which the web tubular films, or alternatively bags or strips / lines of interconnected individual bags are wrapped during the winding process. It provides stability and support to the wound material. The core or spool is herein disclosed as being a roll, core, tube, or spool onto which the material is wound. A conveyor system: A conveyor system or feeding mechanism is used to transport the web tubular films, or alternatively bags or strips / lines of interconnected individual bags from the production line to the winding apparatus. This may ensure a continuous supply of web tubular films, or alternatively bags or strips / lines of interconnected individual bags for winding. A tension control mechanism: Used to ensure consistent winding and prevent overstretching or overlapping of the material. It regulates the tension applied to the material as they it is wound onto the core. One or more spindles: The spindles incorporate one or more rollers that rotate and guide the web tubular films, or alternatively bags or strips / lines of interconnected individual bags onto the core. These rollers help ensure smooth and even winding of the material. A cutting mechanism / cutting arrangement: In some cases, the winding apparatus may include a cutting mechanism to trim the bags to a specific length before they are wound onto the core (if individual bags are wound onto the core) or to cut the web tubular film or the plurality of interconnected individual bags after a predetermined length of said film / bags have been wounded onto the core or around itself. A drive system: The drive system provides the necessary power to rotate the winding shaft and perform the winding process. It is motor-driven and can be controlled for speed and precision.

[0020] In a normal winding process for winding a web tubular film, the process starts with the web tubular film being fed into the winding apparatus through the conveyor system. The web tubular film is then guided by the spindle(s) and wound onto the core in a tightly packed manner. As the core / roll fills up with wound material, it can be replaced with an empty core / roll, and the winding process continues seamlessly. However, in the present process, as disclosed herein, the web tubular film is applied a layer of hot melt / adhesive prior to coming into contact with the core. The tubular film is hereby being converted into rolls of web tubular film, where the web tubular film is either glued to the core or to itself, depending on the configuration of the hot melt unit.

[0021] The winding apparatus as disclosed herein hereby streamlines the packaging process, making it more efficient and reducing the storage space required for web tubular film while at the same time eliminates a process step of applying double adhesive tape, or the like, to the core around which the web tubular film is to be wound. Additionally, the winding apparatus as disclosed herein may in some embodiments provide cores, which can be reused after the web tubular film has been used in other processes.

[0022] The winding apparatus further facilitates easy dispensing, as the wound web tubular film can be easily unrolled and separated from the web tubular film roll, as needed for use.

[0023] A winding shaft as disclosed herein, also known as a winding mandrel or winding core, is a cylindrical device used in various industries for winding or coiling materials such as paper, film, fabric, plastic, wire, or other flexible materials into cores, tubes, rolls, or spools or around its own core. The winding shaft serves as the central support around which the material is wrapped during the winding process.

[0024] The winding shaft is an essential component in winding apparatuses, rewinders, slitters, and other equipment used in manufacturing, converting, and packaging processes. It provides stability and tension control during the winding operation, ensuring that the material is evenly wound and properly aligned on the core / roll / tube / spool or arounds its own core.

[0025] Som characteristics of a winding shafts may include: Core Diameter: The winding shaft has a specific diameter that determines the inner diameter of the wound material roll. Different applications may require winding shafts with various core diameters to accommodate different roll sizes. Material: Winding shafts are commonly made of materials such as steel, aluminium, or other sturdy materials that can withstand the tension and stresses of the winding process. Surface Coating: Some winding shafts may have a specialized surface coating, such as rubber or silicone, to enhance grip and prevent slippage between the shaft and the core. Expandable or Collapsible Shafts: Some winding shafts are designed to be expandable or collapsible, allowing easy loading and unloading of the wound material roll including the core. Shaft Locking Mechanism: Winding shafts often have a locking mechanism that secures the wound material in place once the winding process is complete, preventing unwinding or unravelling.

[0026] A web tubular film refers to a specific type of packaging film that is manufactured in a tubular form. This type of film is commonly used in the packaging industry for various applications, such as creating bags or pouches. The film may be produced in a continuous tube-like structure, with the edges sealed together to form a tube. It may alternatively by produced in other ways known in the art. Hence, in one or more embodiments, the web tubular film is a continues web tubular film. The web tubular film may be provided as a prefabricated web tubular film, where the term "prefabricated" indicates that the film is already manufactured and ready for use; however, the film may alternatively be created upstream of the winding apparatus in a continues process. The film can be made from various materials, such as polyethylene (PE), polypropylene (PP), or other plastic resins, depending on the intended application and packaging requirements. In one or more embodiments, the film is made from polyethylene (PE).

[0027] In one or more embodiments, the web tubular film is a web tubular plastic film. In one or more embodiments, the web tubular film is in the form of a single layer film sheet, such as a plastic sheet prior to being formed as a web tubular film.

[0028] The web tubular film may further be provided in a form having crosswise welds. In this case the film has been produced in a continuous tube-like structure, with the edges sealed together to form a tube, and at regular intervals along the width of the tubular film there are crosswise welds or seals. These seals create separate compartments / segments / sections in the film, allowing for easy separation and forming of individual bags when the film is cut or perforated.

[0029] In the context herein "downstream" and "upstream" refer to different stages or positions relative to the direction of flow of the process. These terms are used to describe the sequence or order of events in the process or the movement of materials in the system.

[0030] Downstream refers to the stages or processes that come after a particular point in a sequence or workflow. Upstream refers to the stages or processes that come before a particular point in a sequence or workflow. This means that downstream represents the stages or processes that come after a particular point in a sequence, while upstream represents the stages or processes that come before that point.

[0031] A crosswise weld as disclosed herein may also be called a "crosswise seal" or "transverse seal / weld." A crosswise weld refers to a sealing line or weld that runs substantially crosswise / transversally to the direction of the material's flow. The crosswise weld may be formed in multiple different shapes, depending on the tool in the welding machine used to make the weld. In the context of packaging, it is a crucial component in creating individual bags or pouches from a continuous roll or web of flexible material, such as plastic film. During the packaging process, a crosswise seal is formed by applying heat or pressure to fuse the flexible material together. This creates a secure and air-tight seal, dividing the continuous material into separate compartments / sections. Each compartment becomes an individual bag or pouch, ready to be filled with the desired contents when an opening is created, such as via a cut or a perforation that is broken.

[0032] Disclosed herein in a second aspect is a web tubular film roll producing machine for producing web tubular film rolls, the machine comprising: a feed conveyor for advancing a length of a web tubular film; a winding apparatus comprising: a hot melt unit; and a winding shaft; wherein the winding apparatus is configured for receiving a web tubular film; wherein the hot melt unit is located upstream of the winding shaft; wherein the hot melt unit is configured for applying a hot melt to a bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by the winding shaft onto the core, the core being positioned on the winding shaft; wherein the winding shaft is arranged to be rotated around its own axis and to receive the web tubular film to be winded up onto the core; and wherein the winding shaft is further arranged to wind up a predetermined length of the web tubular film onto the core hereby creating the web tubular film roll.

[0033] Disclosed herein in a third aspect is a process for producing web tubular film rolls, the process comprises the following steps: advancing a length of a web tubular film trough a feed conveyor to a winding apparatus; applying a hot melt to the bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by a winding shaft onto the core; guiding the web tubular film from the hot melt unit to a winding shaft arranged to be rotated around its own axis; winding up the web tubular film onto the core hereby producing a web tubular film roll.

[0034] In one or more embodiments, the web tubular film is guided by the at least one spindle from the hot melt unit to a winding shaft arranged to be rotated around its own axis.Brief description of the drawings

[0035] Figure 1 shows a winding apparatus. Figure 2 shows a winding apparatus comprising a perforator unit. Figure 3 shows a winding apparatus together with the dancer unit. Detailed description

[0036] The description herein of any aspect or embodiment of the invention using terms such as "comprising", "having," "including," or "containing" with reference to an element or elements is intended to provide support for a similar aspect or embodiment of the invention that "consists of", "consists essentially of', or "substantially comprises" that particular element or elements, unless otherwise stated or clearly contradicted by context, e.g. a composition described herein as comprising a particular element should be understood as also describing a composition consisting of that element, unless otherwise stated or clearly contradicted by context. It will be further understood that the terms "comprises," "comprising," "includes" and / or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0037] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly indicates otherwise. "At least one" is not to be construed as limiting "a" or "an."

[0038] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this invention pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined in the present specification.

[0039] The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0040] Effects and features of the second and third aspects are to a large extent analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second and / or third aspects.

[0041] The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.

[0042] In one or more embodiments, the winding apparatus further comprises an inlet section. An inlet section as disclosed herein refers to the initial part of the winding apparatus, within the working space of the winding apparatus, i.e., and inlet as being part of the winding apparatus and not further upstream of the processing line. In one or more embodiments, the web tubular film is conveyed to the inlet section. In one or more embodiments, the hot melt unit is located downstream of the inlet section and before the winding shaft. In one or more embodiments, a length of the web tubular film is advancing trough a feed conveyor to the inlet section of the winding apparatus.

[0043] In one or more embodiments, the winding apparatus further comprises a cutter arrangement, wherein the cutter arrangement is arranged for cutting the web tubular film after the predetermined length of the web tubular film have been wounded up by the winding shaft.

[0044] In one or more embodiments, the distance from the hot melt unit to the winding shaft is maximum 150 cm, such as maximum 100 cm, such as maximum 75 cm, such as maximum 50 cm, such as maximum 40, such as maximum 30 cm. The distance between the hot melt unit and the winding shaft is defined as the distance the web tubular film needs to travel after having received the hot melt to meeting the winding shaft. The distance may be measured by placing the measuring tool against the centre of the hot melt unit as the starting point and measure to the centre of the winding shaft as the endpoint.

[0045] It is an advantage that the hot melt unit is close to the winding shaft, as this will prevent or reduce the curing / drying out of the adhesive provided by the hot melt unit to the web tubular film. Further, if the hot melt unit is positioned with a greater distance, it may introduce the need for multiple spindles being positioned between the hot melt unit and the winding shaft, and said spindles would need to come into contact with the adhesive applied side of the film to maintain correct tension in the web tubular film with wound onto the core.

[0046] In one or more embodiments, the distance from the hot melt unit to the winding shaft is between 100 cm and 10 cm, such as between 20 cm and 90 cm, such as between 30 cm and 80 cm, or such as between 40 cm and 70 cm.

[0047] In one or more embodiments, the winding apparatus further comprises a housing enclosing a workspace of the winding apparatus, wherein the workspace comprises the hot melt unit and the winding shaft. The workspace may further comprise the at least one spindle.

[0048] A core as used herein may also be called a roll, tube, or a spool. The core is preferably a roll that is cylindrical. In one or more embodiments, the core may be a paper roll or a cardboard roll. In one or more embodiments the core has a diameter of 10 mm to 1000 mm, such as 20 mm to 800 mm, or such as 20 mm to 600 mm.

[0049] In one or more embodiments, the winding apparatus further comprises a base frame.

[0050] In one or more embodiments, the winding apparatus further comprises a feeding mechanism for supplying a continuous stream of web tubular film to the hot melt unit and the winding shaft.

[0051] In one or more embodiments, the winding apparatus further comprises a tension control mechanism to regulate the tension of the web tubular film during winding.

[0052] In one or more embodiments, the winding apparatus further comprises a control unit operatively connected to the feeding mechanism, tension control mechanism, and / or cutting arrangement, wherein the control unit is configured to automate and control the winding process.

[0053] In one or more embodiments, the winding apparatus further comprises an unload position arranged for receiving the web tubular film roll.

[0054] In one or more embodiments, the unload position comprises a label system arranged for close fix a roll tail of the web tubular film roll with a label, so that the web tubular film roll is prepared for automatic packaging.

[0055] In the unload position a label system may be used to close fix the roll tail, so that the finished web tubular film roll is prepared for automatic packaging. The finished web tubular film roll may automatically slide off the winding shaft and can be placed in a position that enable a robot to pick up the web tubular film roll.

[0056] In one or more embodiments, the winding apparatus further comprises an additional winding shaft. In one or more embodiments the winding apparatus comprises four winding shafts in total. By having more winding shafts the winding apparatus may be configured to run two streams of web tubular film and to have further winding shafts on one stream, the apparatus may be configured for a timeless shift between one core and the next core by shifting the film to wind on the second winding shaft in said stream.

[0057] In one or more embodiments, the core is positioned on the winding shaft to receive the web tubular film to be winded up. In one or more embodiment, the core is made of a plastic material or a paper material, such as cardboard.

[0058] In one or more embodiments, the web tubular film is having crosswise welds with a predetermined distance between each crosswise weld. In one or more embodiments, the web tubular film is having premade crosswise welds with a predetermined distance between each crosswise weld.

[0059] In one or more embodiments, the winding apparatus further comprises a perforator unit, wherein the perforator unit is configured for providing crosswise perforations in the web tubular film, hereby creating sections of web tubular film being interconnected along transverse lines of weakness created by the crosswise perforations.

[0060] In one or more embodiments, the winding apparatus further comprises a perforator unit, wherein the perforator unit is configured for providing crosswise perforations in the web tubular film having crosswise welds such that a plurality of interconnected individual bags are created, wherein the plurality of interconnected individual bags are interconnected along transverse lines of weakness created by the crosswise perforations; wherein the perforator unit is further configured such that the crosswise perforations are provided to the web tubular film having crosswise welds such that each of the plurality of interconnected individual bags are defined as a section between a downstream crosswise perforation and the next upstream crosswise perforation, wherein the downstream crosswise perforation defines a top and opening of each of the plurality of interconnected individual bags when the plurality of interconnected individual bags are individualized by breaking the transverse lines of weakness. When the winding apparatus comprises a perforator unit as disclosed above, the web tubular film to be applied the adhesive on the hot melt unit and to be wound up by the winding shaft, would be referred to as interconnected individual bags that create bags when individualized (if the web tubular film is further provided with crosswise welds). Further, the web tubular film roll would be disclosed as a bottom-first bag roll. The above and below disclosed advantages and features of wounding a web tubular film onto a core also applies for wounding strips / lines of interconnected individual bags onto a core.

[0061] By including the perforator at this point it will be possible to wind the created bag rolls with perforation first with high speed without air being trapped inside the bag, so that the bags can be unwinded with its bottom first.

[0062] In the present process, as disclosed herein, if the web tubular film is converted to interconnected individual bags, the bags are not finalized prior to being fed into the winding apparatus through the conveyor system as they are at that point only made of a web tubular film having crosswise welds with a predetermined distance between each crosswise weld. In a normal bag making process, the bags will have been finalized upstream of entering the winding apparatus. However, as disclosed herein, the winding apparatus of the present invention may further comprise a perforation unit, which when the web tubular film is fed to the unit makes a perforation in the tubular film, hereby completing the interconnected bag, such that individual bags can be created by breaking this transverse line of weakness. The web tubular film, now being converted into interconnected bags, is then further conveyed to the hot melt unit and then further to the winding shaft located close to the perforation unit, such that the interconnected bags are wound onto the core with the opening / top first, hereby creating a bag roll with minimum amount of air trapped into the interconnected bags and with bottom-first when unrolled from the core, i.e., hereby creating a seal off first (SOF) bag roll also called a bottom-first bag roll.

[0063] The perforator unit is set up to create crosswise perforations in the web tubular film, which preferably already has crosswise welds. This configuration allows for the formation of multiple interconnected individual bags. The crosswise perforations result in transverse lines of weakness that connect the individual bags together. The perforator unit is designed to create crosswise perforations in the web tubular film, defining individual bags as sections between downstream and upstream crosswise perforations. The downstream perforation forms the top and opening of each individual bag, which can be separated by breaking the transverse line of weakness. In one or more embodiments, the downstream crosswise perforation defines a top and opening of the individual bag when the individual bag is individualized by breaking the transverse line of weakness; whereas the upstream crosswise weld together with the upstream crosswise perforation defines the bottom part of the individual bag when the individual bag is individualized by breaking the transverse line of weakness. In one or more embodiments, the web tubular film is a web tubular plastic film, such that the individual bags will be in the form of individual plastic bags.

[0064] When manufacturing or winding bag rolls, there are two common methods: "bottom-first" and "top-first." In the "bottom-first roll" the film or material is initially fed onto the core from top to bottom. This means the outermost end of the bag roll will be the end of the interconnected bag that comprises the bottom of the last bag wound onto the core, i.e., the bottom weld of the bag. In the "top-first roll" the film is initially fed onto the core from the bottom. This results in the opening of the last bag being the first the user meets when unrolling the bag roll, i.e., the top (broken) perforation of the bag making up the open end of the bag.

[0065] Some of the advantages of making a bottom-first bag roll is that it is the bottom of the bag that is unrolled first when the bags are pulled off the bag roll. This means that it can easily be stuffed into a cardboard box or a container, so the container is quickly ready for filling and packing. Further, in many manual processes there will also be big advantages to unwind the bag roll with the bottom first as this is the right position for filling without turning the individualised bag upside down.

[0066] There may be alternative ways of providing a bottom-first bag roll without the need of having the perforation unit close to the winding shaft. Such alternatives are e.g., to re-roll the bags after the winding so that they will turn "upside down" or the use of static electricity or vacuum to hold the bag opening closed, such that air is not pushed into the opening during the conveyor process from the perforation unit to the winding shaft. Alternatively, the whole process may be run at extremely low speed to avoid air being trapped, as the interconnected bags with perforations needs to travel further on the process line after the perforations are created.

[0067] In one or more embodiments, the bottom-first bag rolls are bottom-first plastic bag rolls.

[0068] A perforator unit as disclosed herein is a device or component used in various industries to create perforations or holes in materials, such as paper, cardboard, plastic, or metal. The process of creating these holes is called perforating, and the resulting pattern of holes is referred to as perforations. The perforator unit typically consists of a mechanism that houses the punch heads or pins and a means to control the spacing and pattern of the holes. The process of perforating may be manual or automated, depending on the application and the level of precision required.

[0069] A crosswise perforation as used herein refers to a series of small holes or perforations made across the width of the material, perpendicular to the direction of its flow or movement. These perforations are created to allow for easy separation or tearing of the material along the perforation line. The crosswise perforation lines weaken the material along their path, enabling users or automated processes to tear or separate the material cleanly and efficiently.

[0070] When providing the crosswise perforation, the perforator unit is making individual bags interconnected along transverse lines of weakness, i.e., the crosswise perforations, if the web tubular film is also applied with crosswise welds.

[0071] In one or more embodiments, the winding apparatus further comprise an inlet section, and wherein the perforator unit is located at the inlet section. In one or more embodiments, the perforator unit is located at the inlet section.

[0072] In one or more embodiments, the perforator unit is configured to provide each crosswise perforation at a predetermined distance upstream from each crosswise weld. In one or more embodiments, the perforator unit is configured such that each crosswise perforation is made adjacent to each crosswise weld. Adjacent as used herein is when the perforation and the weld are almost directly next to each other or located side by side without considerable space in between. By considerable space is meant that the distance between the perforation and the weld is a factor of 10 smaller than the distance between two crosswise perforations or two crosswise welds. In one or more embodiments, the predetermined distance upstream from each crosswise weld is between 1 and 50 mm, such as between 1 and 40 mm, such as between 1 and 30 mm, such as between 1 and 25 mm, such as between 2 and 20 mm, or such as between 3 and 15 mm.

[0073] In one or more embodiments, the perforator unit is configured such that each crosswise perforation is made within a range of 1 mm to 100 mm from the adjacent downstream crosswise weld. In one or more embodiments, the perforator unit is configured to provide a crosswise perforation between a downstream weld and an upstream weld, and closer to the downstream weld compared to the upstream weld.

[0074] In one or more embodiments, the perforator unit is configured to provide the crosswise perforations no more than 10% downstream of the crosswise welds compared to a total length of the individual bag from top to bottom. The total length of the individual bag from top to bottom is measured by separating / individualizing a bag from the web tubular film having both crosswise welds and crosswise perforations and measuring the length from top to bottom, i.e., the total length of the bag.

[0075] In one or more embodiments, the perforator unit is configured to provide the crosswise perforations at a predetermined distance upstream from each crosswise weld.

[0076] In one or more embodiments, the distance from the perforator unit to the winding shaft is maximum 150 cm, such as maximum 100 cm, such as maximum 75 cm, such as maximum 50 cm, such as maximum 40, such as maximum 30 cm. The distance between the perforator unit and the winding shaft is defined as the distance the plurality of interconnected individual bags needs to travel after having received the perforations to meeting the winding shaft. The distance may be measured by placing the measuring tool against the centre of the perforation unit as the starting point and measure to the centre of the winding shaft as the endpoint.

[0077] It is an advantage that the perforation is performed close to the winding shaft, as this will prevent or reduce air from entering the bags, as the bags are rolled into a bottom-first bag roll. Air entering into the bags will not be pushed out of the bag in a process of making a bottom-first bag roll, and therefore air trapped in the bags will increase the diameter of a bag roll with the same number of bags rolled onto it.

[0078] In one or more embodiments, the distance from the perforator unit to the winding shaft is between 100 cm and 10 cm, such as between 20 cm and 90 cm, such as between 30 cm and 80 cm, or such as between 40 cm and 70 cm.

[0079] In one or more embodiments, the workspace further comprises the perforator unit.

[0080] In one or more embodiments, the feed conveyor comprises a dancer unit. A dancer unit is used to maintain tension in the moving web tubular film as it is being wound onto the winding shaft. It helps to prevent wrinkles, stretching, and other issues that can arise due to uneven tension.

[0081] In one or more embodiments, the process includes the step of applying a hot melt to the bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by a winding shaft onto the core, wherein the hot melt is applied at a short distance from the first end of the web tubular film, wherein the first end of the web tubular film is the end coming into contact with the core at the beginning of the process for producing web tubular film rolls. In one or more embodiments, the hot melt is applied to only a section of the web tubular film corresponding to the section of the web tubular film equal to or less than a second layer on the web tubular film roll. Hereby, the web tubular film is adhered to itself by the hot melt only located between the first and second layer of the final roll, counting from the core and out.

[0082] In one or more embodiments, the bottom-first bag roll producing machine further comprises a welding machine, an edge guide, a punch unit, an extractor, a gusseting station, a folding unit, a reinforcement strip applicator, and / or an unwinder.

[0083] In one or more embodiments, the process further comprises the step of cutting the web tubular film after a predetermined length of the web tubular film have been wounded up by the winding shaft.

[0084] In one or more embodiments, the process further comprises a step of close fix a roll tail of the web tubular film roll with a label, so that the finished web tubular film roll is prepared for automatic packaging.

[0085] In one or more embodiments, the web tubular film is having crosswise welds with a predetermined distance between each crosswise weld.

[0086] In one or more embodiments, the process further comprises a step of crosswise perforating the web tubular film at a predetermined distance upstream of each crosswise weld at a perforator unit located at the inlet section, to create a transverse line of weakness in the web tubular film material having crosswise welds hereby creating a plurality of interconnected individual bags defined as sections between a downstream crosswise perforation and the next upstream crosswise perforation, wherein the downstream crosswise perforation defines a top and opening of each of the plurality of interconnected individual bags when the plurality of interconnected individual bags are individualized by breaking the transverse lines of weakness.

[0087] In one or more embodiments, the process further comprises one or more of the steps of: unwinding a web tubular film on an unwinder; gusseting and / or folding the web tubular film on a gusseting station and / or a folding unit; printing on the web tubular film; welding the web tubular film on a welding machine to create crosswise welds with a predetermined distance between each crosswise weld in the web tubular film.

[0088] When describing the embodiments, the combinations and permutations of all possible embodiments have not been explicitly described. Nevertheless, the mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage. The present invention envisages all possible combinations and permutations of the described embodiments.Detailed description of the drawings

[0089] Various examples are described hereinafter with reference to the figures. It should also be noted that the figures are only intended to facilitate the description of the examples. They are not intended as an exhaustive description of the claimed invention or as a limitation on the scope of the claimed invention. In addition, an illustrated example needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular example is not necessarily limited to that example and can be practiced in any other examples even if not so illustrated, or if not so explicitly described.

[0090] As can be seen in the figures, a web tubular film 109 enters into the winding apparatus 101 via a feed conveyer 121. This feed conveyer may comprise a dancer unit 123 e.g., an in-line dancer, which can control the tension of the web tubular film and further is able to act as an accumulator to take up length variations of the web tubular film between the dancer and winding apparatus. In one embodiment, in the frame for the dancer 123 is normally included an edge guide in order to align the web tubular film so that the edge is straight before entering the winding apparatus.

[0091] A housing 115 enclosing a workspace of the winding apparatus 101, wherein the workspace comprises at least the hot melt unit 119, the at least one spindle 103, and the winding shaft 107 may be present.

[0092] The hot melt unit 119 is configured for applying a hot melt to a bottom side of the web tubular film 109. The hot melt unit is located after the perforator unit 105 (if present) but before the winding shaft 107.

[0093] Hence, a hot melt may be applied from the bottom side just before winding the film and the first contact point of the web tubular film after being applied with hot melt may in one embodiment be a core e.g., a paper or plastic core / roll. The timing for the contact between core and hot melt may be synchronized with a cutter 113 in order to prevent unforeseen wrap around at the core.

[0094] In one embodiment, the hot melt can be added to one side of the web tubular film 109 after a short distance from a first end of the web tubular film, this distance corresponding to one winding on the core, the web tubular film will 109 be adhered to the core by gluing the web tubular film 109 to the web tubular film 109 itself and not the core. This means that the innermost part of the web tubular film 109 is glued to itself. By gluing the web tubular film to itself, the core may be recycled, as it would not comprise any residual glue or hot melt once the web tubular film has been removed. This means that the cores can be recycled if the hot melt is not on the core itself.

[0095] The web tubular film 109 may have crosswise welds. A sensor (not shown) may detect the crosswise welds in the web tubular film 109. The crosswise welds may be made to the web tubular film 109 in a welding machine before the web tubular film enters the winding apparatus 101 or the dancer 123. The signal from the sensor may activate a perforator unit 105, so that a crosswise perforation is made in each section of the web tubular film such that a plurality of interconnected individual bags is created, wherein the plurality of interconnected individual bags are interconnected along transverse lines of weakness created by the crosswise perforations.

[0096] In one embodiment crosswise perforations are provided to the web tubular film, which may have crosswise welds such that each of the plurality of interconnected individual bags are defined as a section between a downstream crosswise perforation and the next upstream crosswise perforation, wherein the downstream crosswise perforation defines a top and opening of each of the plurality of interconnected individual bags when the plurality of interconnected individual bags are individualized by breaking the transverse lines of weakness. Hence, the opening of the next bag is in the front end of the bag.

[0097] The perforator unit 105 may be located at the inlet section 111 of the winding apparatus 101, which means a very short distance to the winding point. Due to the short distance between the perforator unit 105 and to the winding point (the winding shaft 107) it can be avoided or minimized that air enters and being trapped in the bag.

[0098] In the figures are also shown a cutter arrangement 113 (may be called a breaker bar if perforations are present), arranged for cutting the web tubular film 109 after the predetermined length of the web tubular film 109 have been wounded up by the winding shaft 107.

[0099] When the web tubular film roll is finished, it will change to the unload position and a new core will be ready for a new roll start. A turret 125 of the winding apparatus 101 may move the web tubular film roll (the finished roll) to the unload position (not shown in the figures) arranged for receiving the web tubular film roll (may also be called the exit position) and make a roll change. The roll change may happen by the turret 125 delivering the web tubular film roll to the unload position e.g., a tray and where the web tubular film roll afterwards is moved sideways out of the unload position. The finished roll may automatically slide off the winding shaft. Grippers may then apply a new roll / core from a magazine to the winding shaft 107.

[0100] In the unload position, a label system (not shown) may be used to close fix the roll tail, so that the finished bag roll is prepared for automatic packaging.References

[0101] 101 winding apparatus 103 spindle 105 perforator unit 107 winding shaft 109 web tubular film 111 inlet section 113 cutter arrangement / breaker bar 115 housing 119 hot melt unit 121 feed conveyor 123 dancer unit 125 turret

Claims

1. A winding apparatus for production of web tubular film rolls, the winding apparatus comprising: - a hot melt unit; and - a winding shaft; wherein the winding apparatus is configured for receiving a web tubular film; wherein the hot melt unit is located upstream of the winding shaft; wherein the hot melt unit is configured for applying a hot melt to a bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by the winding shaft onto the core, the core being positioned on the winding shaft; wherein the winding shaft is arranged to be rotated around its own axis and to receive the web tubular film to be winded up onto the core; and wherein the winding shaft is further arranged to wind up a predetermined length of the web tubular film onto the core hereby creating the web tubular film roll.

2. The winding apparatus according to claim 1, wherein the winding apparatus further comprises a cutter arrangement, wherein the cutter arrangement is arranged for cutting the web tubular film after the predetermined length of the web tubular film have been wounded up by the winding shaft.

3. The winding apparatus according to any of the preceding claims, wherein the winding apparatus further comprises a housing enclosing a workspace of the winding apparatus, wherein the workspace comprises the hot melt unit and the winding shaft.

4. The winding apparatus according to any of the preceding claims, wherein the winding apparatus further comprises an unload position arranged for receiving the web tubular film roll.

5. The wind-up apparatus according to claim 4, wherein the unload position comprises a label system arranged for close fix a roll tail of the web tubular film roll with a label, so that the web tubular film roll is prepared for automatic packaging.

6. The wind-up apparatus according to any of the preceding claims, wherein the winding apparatus further comprises an additional winding shaft.

7. The winding apparatus according to any of the preceding claims, wherein the winding apparatus further comprises a perforator unit, wherein the perforator unit is configured for providing crosswise perforations in the web tubular film having crosswise welds such that a plurality of interconnected individual bags are created, wherein the plurality of interconnected individual bags are interconnected along transverse lines of weakness created by the crosswise perforations; wherein the perforator unit is further configured such that the crosswise perforations are provided to the web tubular film having crosswise welds such that each of the plurality of interconnected individual bags are defined as a section between a downstream crosswise perforation and the next upstream crosswise perforation, wherein the downstream crosswise perforation defines a top and opening of each of the plurality of interconnected individual bags when the plurality of interconnected individual bags are individualized by breaking the transverse lines of weakness.

8. The winding apparatus according to claim 7, wherein the perforator unit is configured to provide each crosswise perforation at a predetermined distance upstream from each crosswise weld.

9. The winding apparatus according to any one of claims 7-8, wherein the perforator unit is configured such that each crosswise perforation is made within a range of 1 mm to 20 mm from the adjacent downstream crosswise weld.

10. The winding apparatus according to any one of claims 7-9, wherein the distance from the perforator unit to the winding shaft is maximum 150 cm, such as maximum 100 cm, such as maximum 75 cm, such as maximum 50 cm, such as maximum 40, such as maximum 30 cm.

11. A web tubular film roll producing machine for producing web tubular film rolls, the machine comprising: ∘ a feed conveyor for advancing a length of a web tubular film; ∘ a winding apparatus comprising: - a hot melt unit; and - a winding shaft; wherein the winding apparatus is configured for receiving a web tubular film; wherein the hot melt unit is located upstream of the winding shaft; wherein the hot melt unit is configured for applying a hot melt to a bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by the winding shaft onto the core, the core being positioned on the winding shaft; wherein the winding shaft is arranged to be rotated around its own axis and to receive the web tubular film to be winded up onto the core; and wherein the winding shaft is further arranged to wind up a predetermined length of the web tubular film onto the core hereby creating the web tubular film roll.

12. The web tubular film roll producing machine according to claim 11, wherein the feed conveyor comprises a dancer unit.

13. A process for producing web tubular film rolls, the process comprises the following steps: ∘ advancing a length of a web tubular film trough a feed conveyor to a winding apparatus; ∘ applying a hot melt to the bottom side of the web tubular film, wherein the bottom side of the web tubular film is the side closest to a core after being wounded up by a winding shaft onto the core; ∘ guiding the web tubular film from the hot melt unit to a winding shaft arranged to be rotated around its own axis; ∘ winding up the web tubular film onto the core hereby producing a web tubular film roll.

14. The process for producing web tubular film rolls according to claim 13, the process further comprising the step of cutting the web tubular film after a predetermined length of the web tubular film have been wounded up by the winding shaft.

15. The process for producing web tubular film rolls according to any one of claims 13-14, wherein the process further comprises a step of crosswise perforating the web tubular film at a predetermined distance upstream of each crosswise weld at a perforator unit located at the inlet section, to create a transverse line of weakness in the web tubular film material having crosswise welds hereby creating a plurality of interconnected individual bags defined as sections between a downstream crosswise perforation and the next upstream crosswise perforation, wherein the downstream crosswise perforation defines a top and opening of each of the plurality of interconnected individual bags when the plurality of interconnected individual bags are individualized by breaking the transverse lines of weakness.

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