Wound paperboard tube, apparatus and method for manufacturing the same

Abstract

A plastic film roll includes a wound paperboard tube including a tubular body having a tubular body wall formed from a plurality of layers of wound paperboard sheets, the paperboard sheets having a weight equal to or less than 300 gsm; a plastic film wound around the wound paperboard tube to form a plurality of plastic film windings around the wound paperboard tube, the plastic film windings exerting a radial compressive force on the tubular body wall equal to or greater than 10 bar, wherein the paperboard sheets include a plurality of fibers, at least a majority of the fibers being substantially aligned in a tangential direction relative to the tubular body to allow the wound paperboard tube to resist the radial compressive force.

Description

Technical Field

[0001] This disclosure generally relates to cardboard tubes and cores, and more particularly to wound cardboard tubes and the apparatus and methods for manufacturing them. Background Technology

[0002] The cardboard tube used for winding films (such as stretchable or malleable films typically made of plastic) must withstand a certain radial compressive force. Cardboard tubes manufactured for winding stretchable film rolls are typically produced by laminating several layers of cardboard and then spirally winding them at a 30-degree angle until the tube has the desired width. The width of the spiral tube is a function of the mass of the film to be wound around the tube and a function of the diameter of the film roll.

[0003] The key parameters commonly used in developing paperboard tubes are the ring crush strength of the paperboard used to form the tube (measured by the force required to crush the paperboard tube when an axial crushing force is applied to its edge) and the delamination resistance of the paperboard (measured by the force required to split the paperboard in half along its thickness). These parameters are commonly used in developing tubes and cores for winding paper rolls, but they may not be suitable for tube design in applications involving radial compression, as the paper roll applies linear rather than radial compression to the tube. Furthermore, in helical wound cores, there is often a small gap between two consecutive strips (or layers). When the core is subjected to radial compression, this gap can lead to core breakage.

[0004] To date, paperboard with fibers oriented in multiple directions has been used to manufacture paperboard tubes designed for plastic film applications, as this arrangement is generally considered to strengthen the tube. To increase the strength of spiral tubes, known techniques require the use of multiple layers of paperboard, meaning the tube wall thickness must be increased and relatively large, even for rolls with short lengths. Another known technique involves using more resistant paperboard, which is generally more expensive, thus increasing the price of the paperboard tubes.

[0005] Spiral paperboard tubes were originally designed for winding paper rolls, and their use for winding stretchable or plastic films stems primarily from the fact that, for obvious economic reasons, manufacturers of paperboard tubes and cores tend to use a single machine and process when manufacturing the tubes. However, spiral tubes may not be the best choice for applications involving radial compression, as they are not specifically designed to resist such radial compression.

[0006] Straight winding of the cardboard wire is another method for manufacturing cardboard tubes and cores. While this method was commonly used at the beginning of cardboard tube manufacturing, it is less common now because it is difficult to manufacture cores of various lengths, and because increasing the strength of the tube requires increasing the number of windings, which in turn leads to a significant increase in the diameter and weight of the tube, which may be neither practical nor economical.

[0007] Canadian Patent No. 2,590,067 describes a method for reusing rolls discarded from paper and paperboard plants by shaping them into straight cores for use in the paper and paperboard industry. While this method offers the advantage of reusing waste rolls within a paper mill, it also suffers from the aforementioned disadvantages of straight cores.

[0008] Therefore, it is desirable to provide cardboard tubes that are particularly suitable for winding stretchable films and / or plastic films while remaining inexpensive and relatively easy to manufacture, and resistant to radial compression. Summary of the Invention

[0009] According to one aspect, an improved cardboard tube is provided that satisfies at least one of the above-mentioned needs.

[0010] Therefore, a plastic film roll is provided, comprising: a wound cardboard tube comprising a tubular body having a tubular body wall formed by a plurality of layers of straight-wound cardboard sheets, the wall thickness of the tubular body wall being less than about 7.5 mm; and a plastic film wound around the wound cardboard tube to form a plurality of plastic film windings around the wound cardboard tube, the plastic film windings exerting a radial compressive force equal to or greater than 15 bar on the tubular body wall, wherein the cardboard sheets comprise a plurality of fibers, at least a majority of which are arranged substantially tangentially relative to the tubular body to allow the wound cardboard tube to resist the radial compressive force.

[0011] In at least one embodiment, the wall thickness is substantially equal to 7.2 mm.

[0012] In at least one embodiment, the radial compressive force generated by the plastic film winding on the tubular wall is equal to or greater than 35 bar.

[0013] In at least one embodiment, the wall thickness is less than 5 mm, and the radial compressive force generated by the plastic film winding on the tubular wall is equal to or greater than 28 bar.

[0014] In at least one embodiment, the plastic film winding is wound around a cardboard tube winding machine.

[0015] In at least one embodiment, all the fibers are arranged substantially along a tangential direction relative to the tubular body.

[0016] In at least one embodiment, the tensile resistance of the tubular body is equal to or greater than 60 kg / mm.

[0017] In at least one embodiment, the weight of the cardboard sheet is equal to or less than about 300 gsm.

[0018] In at least one embodiment, the weight of the cardboard sheet is equal to or less than about 140 gsm.

[0019] In at least one embodiment, the multiple layers of straight-wound cardboard sheets comprise 6 to 10 layers.

[0020] In at least one embodiment, the cardboard sheet includes a cut edge defining a shoulder on the outer surface of the tubular body, the height of which is substantially equal to or less than about 1.2 mm.

[0021] In at least one embodiment, the humidity level of the tubular structure is equal to or less than 7%.

[0022] In at least one embodiment, the humidity level of the tubular structure is substantially equal to or less than 6%.

[0023] In at least one embodiment, the humidity level of the tubular structure is substantially equal to 4.5%.

[0024] In at least one embodiment, the cardboard sheet is made from trimmed cardboard.

[0025] In at least one embodiment, the cardboard sheet has a sheet width defined in the transverse direction of the cardboard sheet, the sheet width being substantially equal to the length of the tubular body.

[0026] In at least one embodiment, multiple layers of straight-wound paperboard sheets are bonded together using an adhesive selected from PVA, dextrin, and silicates.

[0027] In at least one embodiment, the inner diameter of the tubular body is approximately 40 mm to 200 mm.

[0028] In at least one embodiment, the inner diameter of the tubular body is about 74 mm to 78 mm.

[0029] In at least one embodiment, the inner diameter of the tubular body is approximately 76 mm.

[0030] In at least one embodiment, the sheet thickness of the straight-rolled cardboard sheet is about 0.72 mm to 1.2 mm.

[0031] According to another aspect, a winding tube manufacturing apparatus for manufacturing winding paperboard tubes is also provided, the apparatus comprising: a frame extending between an input end and an output end positioned relative to the input end, the frame being configured to receive a paperboard roll to allow the roll to rotate about a reel; a tube forming roller rotatably connected to the frame, the tube forming roller having a tube roller shaft oriented such that the tube roller shaft is substantially parallel to the reel, the tube forming roller further comprising a gripping mechanism for engaging the end edges of the paperboard roll, thereby winding the paperboard roll around the tube forming roller as the tube forming roller rotates to form a winding paperboard tube.

[0032] In at least one embodiment, the apparatus further includes a tube removal assembly for removing the formed wound cardboard tube from the tube forming roller.

[0033] In at least one embodiment, the tube removal assembly includes a carriage movable along a travel path parallel to the tube roller axis and an adjacent element fixed to the carriage and positioned adjacent to the tube forming roller.

[0034] In at least one embodiment, the adjacent element includes an annular member extending coaxially around the tube forming roll.

[0035] In at least one embodiment, the inner diameter of the annular member is smaller than the outer diameter of the formed wound cardboard tube, such that the movement of the carriage along its travel path causes the annular member to push the formed wound cardboard tube.

[0036] In at least one embodiment, the gripping mechanism includes at least one suction port defined in a tube forming roller and a suction actuator operatively connected to the at least one suction port to provide suction through the at least one suction port.

[0037] In at least one embodiment, at least one suction port comprises a plurality of suction ports aligned with each other and substantially parallel to the tube roller axis.

[0038] In at least one embodiment, the tube forming roll further includes a plurality of suction nozzle components, each suction nozzle component being received in a corresponding suction port, each suction nozzle component being movable between an extension position in which the suction nozzle component extends outward from the corresponding suction port and a retracted position in which the suction nozzle component is fully retracted into the tube forming roll.

[0039] According to another aspect, a winding tube manufacturing apparatus for manufacturing a wound paperboard tube is also provided, the apparatus comprising: a frame extending between an input end and an output end positioned relative to the input end; a paperboard roll rotatably received on the frame, the paperboard roll being rotatable about a reel, the paperboard roll containing a plurality of fibers, at least a majority of which are arranged in a tangential direction relative to the paperboard roll; a tube forming roller rotatably connected to the frame, the tube forming roller having a tube roller shaft oriented such that the tube roller shaft is substantially parallel to the reel, the tube forming roller further comprising a gripping mechanism for engaging end edges of the paperboard roll, thereby winding the paperboard roll around the tube forming roller as the tube forming roller rotates to form a wound paperboard tube containing fibers arranged in a tangential direction relative to the wound paperboard tube.

[0040] According to another aspect, a method for manufacturing a wound cardboard tube is also provided, the method comprising: unwinding a preselected cardboard roll along a machine direction tangential to the preselected cardboard roll to obtain an unwound cardboard sheet, the preselected cardboard containing a plurality of fibers oriented along the machine direction; straight-winding the unwound cardboard sheet into a wound cardboard tube, the wound cardboard tube containing fibers oriented along the machine direction; and cutting the unwound cardboard sheet along its width.

[0041] In at least one embodiment, the method further includes applying an adhesive to the unwound cardboard after unwinding the preselected roll of cardboard.

[0042] In at least one embodiment, the pre-selected paperboard includes scrap paperboard.

[0043] In at least one embodiment, the unraveled cardboard sheet is cut along its width after the unraveled cardboard sheet is rolled straight into a winding cardboard tube to separate the winding cardboard tube from the remainder of the unraveled cardboard sheet.

[0044] In at least one embodiment, the tensile strength of the preselected paperboard is equal to or greater than 60 kg / mm.

[0045] In at least one embodiment, the method further includes drying the wound cardboard tube until the humidity level of the tube is less than or equal to 7%.

[0046] In at least one embodiment, the method further includes connecting at least two wound cardboard tubes to form a wound cardboard tube of a desired length.

[0047] In at least one embodiment, the method further includes cutting the wound cardboard tube along its length to form at least one wound cardboard tube fitting having a desired length.

[0048] In at least one embodiment, unwinding the preselected cardboard roll includes rotating the roll along a first axis of rotation.

[0049] In at least one embodiment, the straight-wound unwinding of the cardboard sheet includes rotating the unwinding cardboard sheet along a second rotation axis parallel to the first rotation axis.

[0050] In at least one embodiment, the unwinding of the pre-selected cardboard roll and the straight-wound unwinding of the cardboard sheet are performed simultaneously.

[0051] The wound paperboard tube disclosed below is cheaper to produce than existing spiral or straight-wound paperboard tubes because it is more resistant to the radial forces exerted on the tube by the stretchable film wound around it, while minimizing the raw materials required to form the tube.

[0052] Furthermore, since the raw materials used to form the wound cardboard tubes come from rolls of scrap cardboard, i.e., rolls of waste cardboard, the manufacturing cost is further reduced because rolls of scrap cardboard are cheaper than the rolls typically used for such tubes. In addition, using rolls of scrap cardboard as raw materials has a positive environmental impact because it eliminates the need to manufacture new rolls, thus reducing the greenhouse effect.

[0053] Since the length of the scrap paper roll corresponds to the length of the tube typically required for winding plastic film, i.e., 15 to 21 inches, the paper from the scrap paper roll generally does not need to be cut along its length, thereby reducing the steps required to manufacture the wound paper tube of the present invention. It also eliminates the need to connect several tubes together to form a wound tube of the desired length. Attached Figure Description

[0054] Figure 1A This is a perspective view of a prior art spiral cardboard tube used for winding plastic film or stretchable plastic film.

[0055] Figure 1B This is a front view of the prior art spiral cardboard tube shown in Figure 1.

[0056] Figure 2A This is a perspective view of a wound cardboard tube according to one embodiment of the present invention, showing a wound cardboard tube having a plastic film wound around it, and wherein the tube is compressed by radial force.

[0057] Figure 2B yes Figure 2A The front view of the tube shown.

[0058] Figure 2C This is a perspective view of another wound cardboard tube according to a preferred embodiment of the present invention.

[0059] Figure 3 This is a perspective view showing the rings of the cardboard during the ring crush test.

[0060] Figure 4 This is a perspective view of a spiral wound tube manufacturing equipment according to one implementation plan.

[0061] Figure 5A It is shown Figure 4 A perspective view showing a portion of the winding tube manufacturing equipment, detailing the tube forming rollers and cutting assembly.

[0062] Figure 5B yes Figure 5A The perspective view is taken from region B and shows a magnified portion of the details of the tube removal component.

[0063] Figure 6 yes Figure 4 The diagram shows a side cross-section of the spiral wound tube manufacturing equipment.

[0064] Figure 7 yes Figure 6 The side cross-sectional view is taken from region A and shows a magnified portion of the details of the gripping mechanism used to engage the end edges of the cardboard roll.

[0065] Figure 8A It is shown Figure 7The schematic diagram of the side cross-section of the tube forming roller is shown in a first position in which the suction nozzle member is in an extended position and the suction actuator is activated to allow the suction nozzle member to engage and hold the end edge of the cardboard roll.

[0066] Figure 8B It is shown Figure 7 The schematic diagram of the side cross-section of the tube forming roller is shown in a second position in which the tube forming roller is partially rotated relative to the first position, such that a first winding of a paperboard tube is partially formed around the tube forming roller.

[0067] Figure 8C It is shown Figure 7 The schematic diagram of the side cross-section of the tube forming roller is shown in a third position in which the first winding of the paperboard tube is completely formed around the tube forming roller.

[0068] Figure 9A This is a perspective view of the portion of the device shown in Figure 5 facing the output end, wherein the end edge of the paper roll is positioned between the tube forming roller and the upper holding roller, and the upper holding roller is spaced upward from the end edge.

[0069] Figure 9B This is a perspective view of a portion of the apparatus shown in Figure 5, in which the upper holding roller descends toward the tube forming roller to hold the end edge between the upper holding roller and the tube forming roller.

[0070] Figure 9C This is a perspective view of a portion of the device shown in Figure 5, where a gripping mechanism is activated to keep the end edges against the tube forming roller as the tube forming roller rotates.

[0071] Figure 9D This is a perspective view of a portion of the apparatus shown in Figure 5, in which a wound cardboard tube is formed on a tube forming roller, and an upper retaining roller remains descending and adjacent to the wound cardboard tube.

[0072] Figure 9E This is a perspective view of a portion of the apparatus shown in Figure 5, in which the upper retaining roller is raised above the winding cardboard tube to release the winding cardboard tube.

[0073] Figure 9F Figure 5 shows a perspective view of a portion of the equipment, in which the wound cardboard tube is partially removed from the tube forming roller by the tube removal assembly.

[0074] Although the invention will be described in conjunction with exemplary embodiments, it should be understood that the scope of the invention is not limited to such embodiments. Rather, it is intended to cover all alternatives, modifications, and equivalents that may be included and defined in this specification. Detailed Implementation

[0075] In the following description, similar features in the accompanying drawings have been given similar reference numerals. For clarity, if certain reference numerals have already been indicated in the preceding drawings, these reference numerals are omitted from the accompanying drawings.

[0076] A measurement system specifically designed for the paper and paperboard industry can be used to measure the tube's resistance to radial forces.

[0077] Through several experiments, the applicant demonstrated that straight-wound or wound-wound cardboard tubes offer better resistance to radial forces compared to commonly used spiral cardboard tubes.

[0078] The term "cardboard" refers to paper-based materials whose thickness and stiffness vary depending on their intended use.

[0079] The term "wound cardboard tube" refers to a tube that is directly wound or straight-wound, as opposed to a spirally wound tube. Each "layer" of the wall of a wound tube refers to a single winding of a sheet of cardboard.

[0080] Specifically, in at least some cases, an improvement of at least about 21% in radial force resistance has been observed between wound cardboard tubes and conventional spiral tubes with the same wall thickness.

[0081] It was also found that in some cases, the resistance of straight-wound pipes to radial forces can be a function of one or more of the following parameters:

[0082] - Tensile strength (in kg / mm);

[0083] - The length and / or orientation of the fibers in the paperboard; and

[0084] -The level of humidity within the walls of the forming tube.

[0085] Further experiments showed that straight-wound cardboard tubes have sufficient resistance to radial compression when the tensile strength is greater than or equal to 60 kg / mm ​​or approximately 5900 bar·mm. The test to determine this ratio involves attaching a cardboard sheet (e.g., 5 mm (width) × 100 mm (length)) to its upper end and applying a load to its opposite lower end until the sheet breaks. This ratio is obtained by dividing the load (in kg) by the sheet thickness (in mm).

[0086] By testing the radial compression of several tubes made of different types of cardboard, it was found that tubes made of cardboard with most or all of its fibers oriented substantially along the winding direction of the tube (i.e., along the tangential direction relative to the tube) were more resistant to radial forces than tubes made of cardboard sheets with multi-directionally oriented fibers, which are generally considered to be more resistant.

[0087] In some cases, the humidity level inside the cardboard tube can also affect its overall resistance. During flat crush testing (where the tube is placed between two compression plates perpendicular to its longitudinal axis and applying pressure to the tube wall), a 1% difference in tube humidity level has been found to cause a 4% to 5% loss in the tube's resistance to compression. For example, if the humidity level in the tube is 5%, a flat crush tube will require 10 bar of pressure, while at 6% humidity, the required pressure is approximately 9.5 bar.

[0088] The applicant's experiments showed that when the tube's resistance to radial compression was tested by applying force to the tube in the radial direction relative to the tube (rather than straight or perpendicular compression, as described above), a 1% difference in tube humidity level resulted in a 10% to 12% loss of tube resistance. Other experiments conducted by the applicant showed that the tube had sufficient radial compression resistance when the humidity level inside the tube was less than 7%, or more specifically less than 6%, and that its resistance was stable at a humidity level of approximately 4.5%.

[0089] Referring to Figure 1, a conventional plastic film roll 5 is shown, comprising a conventional spiral cardboard tube 10 and a plastic film or stretchable film 12 wound around the tube 10. Due to its stretchable properties, the plastic film 12 compresses the wound tube with a radial compressive force F, which is generally radially distributed around the entire circumference of the tube 10 and toward the central longitudinal axis of the tube 10. In contrast, a tube wound with a material of different properties (e.g., substantially non-stretchable paper) does not experience radial forces. Instead, the main force the tube will experience will be a downward force from the weight of the paper on the tube, tending to compress or bend the tube.

[0090] Reference Figure 2A and Figure 2B The diagram illustrates a plastic film roll 15 according to one embodiment. The plastic film roll 15 includes a wound cardboard tube 20 and a plastic film 50 wound around the wound cardboard tube 20. Specifically, the plastic film 50 forms a plurality of plastic film windings around the wound cardboard tube 20. The plastic film windings exert a radial compressive force F on the wound cardboard tube 20, and the wound cardboard tube 20 is designed to resist this radial compressive force F. The wound cardboard tube 20 has a tubular body 22 defined by a tubular body wall 24 formed of several layers of straight-wound cardboard sheets 26. Specifically, the body 22 of the tube 20 is formed by winding or straight-winding a continuous sheet of cardboard or paper-based material. The process of “winding” or “straight-winding” means that each subsequent winding is superimposed on the previous winding in a winding direction substantially perpendicular to the longitudinal axis of the tube 20. In this configuration, the thickness of the wall 24 of the tube 20 thus substantially corresponds to the thickness of the cardboard sheet multiplied by the number of times the sheet is wound.

[0091] In one embodiment, the sheet thickness of the straight-wound cardboard is about 0.72 mm to 1.2 mm, and the tubular body 22 comprises 6 to 10 layers of straight-wound cardboard. Therefore, the wall thickness of the wall 24 can be less than 7.5 mm, more specifically less than 7.2 mm. Alternatively, the straight-wound cardboard can have any other suitable thickness, and the tubular body 22 can comprise fewer than 6 layers or more than 10 layers of straight-wound cardboard, allowing the wall 24 to have any other suitable wall thickness.

[0092] In one embodiment, the weight of the straight-rolled cardboard sheet is equal to or less than about 300 gsm or 300 g / m², more specifically less than about 140 gsm or 140 g / m². Alternatively, the straight-rolled cardboard sheet may have any other suitable weight.

[0093] In one embodiment, the inner diameter of the tubular body 22 is from about 40 mm to 200 mm, more specifically from about 74 mm to 78 mm, or even more specifically about 76 mm. Alternatively, the tubular body 22 may have any other suitable inner diameter.

[0094] In the illustrated embodiment, the cardboard sheet includes a cut edge 60 formed during the cutting of the cardboard sheet, before forming the wound cardboard tube 20, or after forming the wound cardboard tube 20. The cut edge 60 corresponds to the end of the outermost winding of the cardboard sheet in the wound cardboard tube 20. The cut edge 60 is fixed to the outer surface of the tube 22 and defines a step or shoulder 62 on the outer surface of the tube 22 due to the thickness of the cardboard sheet. Thus, the shoulder 62 may have a height substantially corresponding to the sheet thickness of the cardboard sheet. For example, in one embodiment, the height of the shoulder 62 is substantially equal to or less than about 1.2 mm, or more specifically, about 0.72 mm to 1.2 mm. Alternatively, the shoulder 62 may have any other suitable height.

[0095] In one embodiment, the layers of the cardboard sheet are bonded together using an adhesive selected from PVA, dextrin, and silicates. Alternatively, the layers of the cardboard sheet may be bonded together using any other suitable adhesive or any other suitable fastening technique.

[0096] like Figure 2C As shown, the cardboard sheet 28 comprises fibers 30 oriented substantially along the circumferential direction of the tubular body 22. In other words, the fibers 30 are oriented along the winding direction of the cardboard sheet 28 or along the length of the unwound continuous sheet 28 (i.e., along the tangential direction relative to the tube 20). The fibers 30 are also preferably long, as is common in cardboard or paper-based sheets used for boxes and bags. In one embodiment, all the fibers 30 in the cardboard sheet 28 are aligned along the winding direction of the cardboard sheet 28. Alternatively, not all but most of the fibers are aligned along the winding direction of the cardboard sheet 28.

[0097] In the illustrated embodiment, the paperboard used to form the tube 20 is characterized in that its tensile strength ratio is substantially equal to or greater than about 60 kg / mm. Alternatively, the paperboard used to form the tube 20 may have a larger or smaller tensile strength ratio. Figure 3 An example of a method for measuring the tensile strength ratio of a paperboard sheet, such as paperboard sheet 32, is shown. In this example, the tensile strength ratio is measured by fixing a paperboard sheet 32, or a portion thereof, having a predetermined thickness t, length l, and width w, at one end, and by fixing a load 34 that generates tension in the paperboard sheet 32 ​​at its other end. The load is increased until the sheet 32 ​​breaks or fractures.

[0098] In one embodiment, the humidity level of the wound cardboard tube 20, measured within the wall 24 of the tubular body 22, is substantially equal to or less than about 7%, more specifically substantially equal to or less than about 6%, and even more specifically 4.5%. It has been observed that, in at least some cases, a humidity level below 7%, more specifically below 6%, provides improved resistance to radial compression to the tube 20. Alternatively, the humidity level of the wound cardboard tube 20 may be higher than about 7%.

[0099] While the cardboard sheet 32 ​​for forming the tube 20 can be specifically manufactured for this purpose, the cardboard sheet 28 is preferably derived from rolls of scrap cardboard. In other words, the raw material used to form the cardboard tube 20 comes from waste paper from a paper mill. This provides a significant advantage in terms of raw material costs for manufacturing the cardboard tube 20 for radial compression applications, as it directly reduces the total cost of the tube 20. Alternatively, the cardboard sheet 28 may not be derived from rolls of scrap cardboard, but may instead comprise other types of cardboard.

[0100] In one embodiment, the wound cardboard tube 20 has a length Lt, and the cardboard sheet 32 ​​comes from a roll having a length Lr corresponding to the length Lt. This characteristic of the cardboard sheet 32 ​​eliminates the need to cut sheets along the length of the tube 20 during manufacturing. It also eliminates the need to join several tubes together to form a wound cardboard tube of the desired length. In practice, the length Lr of the roll of scrap cardboard is typically 15 inches to 21 inches, which advantageously corresponds to the length Lt of the cardboard tube used for winding the stretchable film.

[0101] In another embodiment, the roll Lr of scrap paperboard may alternatively be longer than the required or desired length Lt of the paperboard tube. In this embodiment, an initial paperboard tube can be formed and then cut into one or more paperboard tubes having the required or desired length Lt.

[0102] Alternatively, when the length Lr of the cardboard roll does not exactly correspond to the desired length of the wound cardboard tube 20, the tube 20 may be formed from at least two wound cardboard tubes connected to each other by any suitable means (e.g., with adhesive, male and female joints, or by spirally winding finishing tape around the joined tubes).

[0103] Example 1

[0104] Table 1 below presents the results of tests performed on the first group of wound cardboard tubes, compared to similar tests performed on conventional spiral tubes. Specifically, each test was conducted on a tube with a length of 150 mm. The test involved applying a uniform radial force inward around the entire circumference of the tube, gradually increasing the force until the tube failed. The applied force was then divided by the area covered by the applied force to obtain the ultimate radial compressive strength value of the tube, which is independent of the tube's dimensions (i.e., diameter and length).

[0105] Table 1: Comparison of radial compression resistance between conventional spiral tubes and wound cardboard tubes for different wall thicknesses (Group 1 test)

[0106]

[0107]

[0108] The results in Table 1 show that, for each paperboard thickness tested, the radial compressive strength of the wound paperboard tube is greater than that of the corresponding spiral tube. In at least one case (i.e., a paperboard thickness of 4.6 mm), the wound paperboard tube even shows an improvement of approximately 21% in radial compressive strength compared to the corresponding spiral tube.

[0109] Example 2

[0110] Table 2 below presents the results of tests performed on the second group of wound cardboard tubes, comparing them again with the results of similar tests performed on conventional spiral tubes. This test again involved applying a uniform radial force inward around the entire circumference of the tube, gradually increasing the force until the tube failed. Conventional spiral tubes and wound cardboard tubes with various cardboard thicknesses were selected, and the test was repeated for three wound cardboard tubes for each thickness. In this embodiment, both the conventional spiral tubes and wound cardboard tubes tested were made of cardboard with a weight of 160 gsm and a moisture level of approximately 5%.

[0111] Table 2: Comparison of radial compression resistance between conventional spiral tubes and wound cardboard tubes for different wall thicknesses (Second group of tests)

[0112]

[0113] In this embodiment, in addition to determining the ultimate radial compressive strength of each tube as in Embodiment 1, the ultimate radial compressive strength per unit thickness was also determined. The results show that for tubes of the same thickness, the ultimate radial compressive strength of the wound cardboard tube configured as disclosed herein is consistently higher than that of a conventional spiral tube.

[0114] Spiral wound tube manufacturing equipment

[0115] Turn now Figures 4 to 7 A winding tube manufacturing apparatus 100 for manufacturing a winding tube, such as a winding cardboard tube 20, according to one embodiment is shown. In this embodiment, the apparatus 100 includes a frame 102 having an input end 104 for feeding paper to the apparatus 100 and an output end 106 positioned opposite the input end 106. The frame 102 is configured to receive a paper roll 150 at the input end 104 to feed the paper toward the output end 106. Specifically, the paper roll 150 can be rotated about a reel R1 to unwind a section of paper or an unwound cardboard 160 from the paper roll 150. The unwound cardboard 160 includes an end edge 152 that moves toward the output end 106 in the machine direction M via a plurality of intermediate rollers 110 arranged between the input end 104 and the output end 106. Figure 7 (Best shown in the diagram). In one embodiment, the intermediate roller 110 can be further selectively moved up and down by a corresponding actuator to allow the user to set the desired tension in the unfolded cardboard sheet 160.

[0116] "Machine direction" M refers to the direction in which the unwound cardboard sheet 160 travels through the device 100 from the input end 104 to the output end 106. This direction is also tangent to the paper roll and perpendicular to the reel R1. "Transverse direction" T refers to a direction that is substantially perpendicular to the machine direction.

[0117] The apparatus 100 also includes a tube forming roller 112 rotatably connected to the frame 102 and rotatable about the tube roller axis R2. The tube forming roller 104 is configured to engage the end edge 152 of the paper roll 150 and rotate to wind or wrap the paper roll 150 around the tube forming roller 104. Specifically, the apparatus 100 includes a gripping mechanism 200 for engaging the end edge of an unwound sheet of paper. This allows the end edge 152 of the unwound sheet of paper to be guided along a circular path around the tube forming roller 104 to form a first winding of the tube. Once the first winding of the tube is formed, the end edge 152 is wedged under the unwound sheet of paper being wound thereon, thus deactivating the gripping mechanism 200. Alternatively, the gripping mechanism 200 may remain active throughout the formation of the winding tube 20.

[0118] The diameter of the tube forming roller 104 is substantially equal to the inner diameter of the wound cardboard tube 20. In one embodiment, the diameter of the tube forming roller 104 is from about 40 mm to 200 mm, more specifically from about 74 mm to 78 mm, and even more specifically about 76 mm. Alternatively, the tube forming roller 104 may have a larger or smaller diameter.

[0119] In this configuration, the unwinding of paper from the paper roll 150 and the winding or wrapping of the unwound cardboard sheet 160 around the tube forming roller 112 can thus be performed in a continuous motion. Specifically, the tube forming roller 112 is oriented such that when the paper roll 150 is received on the frame 102, the tube roller shaft R2 and the roll shaft R1 are parallel to each other. Therefore, the unwound cardboard sheet 160 remains in the machine direction as it unwinds from the paper roll 150 and is wound around the tube forming roller 112 to form the wound cardboard tube 20.

[0120] In an embodiment where the wound cardboard tube contains multiple fibers, at least a majority of which are arranged in a tangential direction relative to the wound cardboard tube 20, the paper roll 150 is selected such that the cardboard on the roll contains fibers also oriented in a tangential direction relative to the paper roll 150, i.e., in the machine direction. Therefore, as the unwound cardboard sheet 160 travels from the input end 104 to the output end 106, the fibers remain aligned in the machine direction M.

[0121] In the illustrated embodiment, the apparatus 100 further includes an adhesive application assembly for applying adhesive to the unwound cardboard sheet 160 wound on the tubular forming roller 112. In one embodiment, the adhesive application assembly is configured to apply adhesive to the underside of the unwound cardboard sheet 160 upstream of the tubular forming roller 112, such that the unwound cardboard sheet 160 is simultaneously adhered to the preceding winding as it is wound to form a winding above the preceding winding below. In another embodiment, the adhesive application assembly may alternatively be configured to apply adhesive to the outside of each winding as it moves below the unwound cardboard sheet 160, which has been fully rotated around the tubular forming roller 112 and on which a new winding is formed, thereby adhering the winding to the underside of the unwound cardboard sheet 160. In one embodiment, the adhesive may be selected from PVA, dextrin, and silicates. Alternatively, the adhesive may include any other suitable adhesive.

[0122] In the illustrated embodiment, once the wound cardboard tube 20 is formed, the cardboard sheet forming the wound cardboard tube 20 is separated only from the remainder of the unwound cardboard sheet 160. Specifically, the apparatus 100 also includes a cutting assembly located upstream of the tube forming roller 112 toward the input end 104. Once the unwound cardboard sheet 160 has been wound a desired number of times to form the desired number of windings and desired thickness of the wound cardboard tube 20, the cutting assembly can move toward the unwound cardboard sheet 160 to separate the formed wound cardboard tube 20 from the remainder of the unwound cardboard sheet 160. In this configuration, the apparatus 100 thus manipulates a single sheet of paper, i.e., the unwound cardboard sheet 160, rather than multiple separate sheets, which simplifies the manufacturing process.

[0123] Alternatively, the cardboard piece used to form the wound cardboard tube 20 can be separated from the rest of the unwrapped cardboard 160 before forming the wound cardboard tube 20.

[0124] Turn now Figures 7 to 8C The gripping mechanism 200 includes a plurality of suction ports 202 defined in the tube forming roller 112. Specifically, the tube forming roller 112 is hollow and includes an inner channel 204 in fluid communication with the suction ports 202. The inner channel 204 is further operatively connected to a vacuum source, such as a pump, to generate suction through the suction ports 202. Specifically, the generated suction is sufficient to hold the end edge 152 against the tube forming roller 112.

[0125] In the illustrated embodiment, the suction ports 202 are aligned with each other substantially parallel to the tube roller axis R2. Alternatively, the suction ports 202 can be arranged in any other suitable manner. Still in the illustrated embodiment, each suction port 202 is substantially circular, but alternatively, the suction ports 202 can be elongated or have any other shape.

[0126] In the illustrated embodiment, the gripping mechanism 200 further includes a plurality of suction nozzle members 220. Each nozzle member 220 is received in a corresponding suction port 202 and is movable relative to the tube forming roller 112. Specifically, each suction nozzle member 220 is selectively movable between an extended position in which the suction nozzle member 220 extends outward from the corresponding suction port 202 and a retracted position in which the suction nozzle member 220 is fully retracted into the tube forming roller 112.

[0127] In the illustrated embodiment, each suction nozzle component 220 is connected to a nozzle component actuator 222, such as a solenoid actuator or electromagnet, which, when activated, moves the suction nozzle component 220 from a retracted position to an extended position. Still in the illustrated embodiment, the suction nozzle component 220 is also connected to a spring component 224, which biases the suction nozzle component 220 toward the retracted position. In this embodiment, when the nozzle component actuator 222 is deactivated, the spring component 224 moves the suction nozzle component 220 from the extended position back to the retracted position. Alternatively, the nozzle component actuator 222 may alternatively include a bidirectional actuator capable of moving the suction nozzle component 220 both from the retracted position to the extended position and vice versa.

[0128] like Figure 8A As shown, the suction nozzle component 220 is initially in an extended position to engage the detached cardboard sheet 160 at or adjacent to end edge 152. In this position, a vacuum source is further activated to provide suction through the suction nozzle component 220. As the tube forming roller 112 rotates forward, as... Figure 8B As shown, the suction nozzle component 220 holds the untied cardboard sheet 160 against the tube forming roller 112. The tube forming roller 112 then rotates further until the end edge 152 is wound under the untied cardboard sheet 160 and forms a first winding, as shown. Figure 8C As shown. At this time, when forming other windings, the vacuum source can be deactivated and the suction nozzle member 220 can be moved to the retracted position. In one embodiment, the vacuum source can remain active and the suction nozzle member 220 can remain in the extended position when forming the first few windings to ensure sufficient friction between the windings to prevent the windings from dislodging from the tube forming roller 112 before the suction nozzle member 220 moves to the retracted position.

[0129] In one embodiment, the tubular forming roller 112 rotates at a first rotational speed when forming the first winding or the first few windings, and then rotates at a second rotational speed greater than the first rotational speed when forming the remaining windings. Alternatively, the tubular forming roller 112 may rotate at a constant speed throughout the formation of all windings.

[0130] Still in the illustrated embodiment, the device 100 further includes an upper holding roller 300 rotatably connected to the frame 102 and arranged above the tube forming roller 112. Specifically, the upper holding roller 300 extends generally parallel to the tube forming roller 112 and is movable substantially vertically. The upper holding roller 300 is further operably connected to an upper holding roller actuator to move the upper holding roller 300 between an open position in which the upper holding roller 300 is spaced upward from the tube forming roller 112 and a holding position in which the upper holding roller descends toward the tube forming roller 112 to hold the unfolded cardboard sheet 160 against the tube forming roller 112. Alternatively, the device 100 may not include the upper holding roller 300.

[0131] In the illustrated embodiment, the apparatus 100 further includes a tube removal assembly 400 for removing the wound cardboard tube 20 from the tube forming roller 112 once formed. Specifically, the tube removal assembly 400 includes a carriage 402 movable along a travel path parallel to the tube roller axis R2 and an abutment element 404 fixed to the carriage 402 and positioned adjacent to the tube forming roller 112.

[0132] like Figure 5A and 5B As shown, carriage 402 is operatively mounted on carriage track 406, which extends below and is movable along the tube forming roller 112. Adjacent element 404 is connected to carriage 402 via support member 408, which extends substantially perpendicularly between carriage 402 and adjacent element 404. In the illustrated embodiment, adjacent element 404 includes an annular member 410 extending coaxially around tube forming roller 112. Specifically, the inner diameter of annular member 410 is smaller than the outer diameter of the formed wound cardboard tube 20. In this configuration, movement of carriage 402 along its path of travel on carriage track 406 causes annular member 410 to move along tube forming roller 112 and push the formed wound cardboard tube 20 toward one end of tube forming roller 112 until it is completely removed from tube forming roller 112. Carriage 402 can then move back to its initial position, and a new wound cardboard tube 20 can then be formed on tube forming roller 112.

[0133] It should be understood that the aforementioned apparatus 100 provides a relatively fast and fully automated method for manufacturing wound paperboard tubes, such as wound paperboard tube 20. For example, in some embodiments, the apparatus 100 can be configured to wind unwound paperboard sheets 160 at a speed of about 1 m / s to about 2 m / s to form wound paperboard tubes 20, and to form an average of about three wound paperboard tubes 20 per minute. Furthermore, by using a paper roll containing fibers that are at least mostly arranged in the tangential direction, i.e., in the machine direction M, the formed wound paperboard tube 20 contains multiple fibers that are also mostly arranged in the tangential direction, thereby providing enhanced radial compression resistance to the wound paperboard tube 20 as described above.

[0134] Instead of cutting and then moving the unraveled cardboard sheet 160 independently laterally, moving the unraveled cardboard sheet 160 in a single direction, namely the machine direction M, further simplifies and accelerates the manufacturing process.

[0135] Manufacturing process of wound cardboard tubes

[0136] Turn now Figures 9A to 9F The diagram illustrates a method for manufacturing a wound cardboard tube, such as a wound cardboard tube 20, according to one embodiment. Although the following method is described in conjunction with the above-described apparatus 100, it should be understood that this is merely an example and the method can be performed alternatively with different apparatus.

[0137] First, a paper roll, such as paper roll 150, is provided and unwound. Specifically, the paper roll includes a paperboard pre-selected according to a desired characteristic. For example, paper roll 150 includes a pre-selected paperboard comprising a plurality of fibers arranged substantially in a direction relative to the tangent of paper roll 150.

[0138] In the illustrated embodiment, the paper roll 150 is mounted on the frame 102 with the input end 104 facing it, as shown. Figure 4 As shown. The paper roll 150 can then be unwound along the machine direction M to form an unwound cardboard sheet 160. The end edge 152 is then moved toward the output end 106 until it engages with the tube forming roller 112.

[0139] The unwound cardboard sheet 160 can then be straightened or wound to form a wound cardboard tube 20, such that the wound cardboard tube 20 contains fibers arranged in the machine direction M. In one embodiment, the unwound cardboard sheet 160 can be wound at a speed of about 1 m / s to 3 m / s. Alternatively, the unwound cardboard sheet 160 can be wound at a lower or higher speed.

[0140] Reference Figure 9A In order to wind the unwound cardboard sheet 160 to form a wound cardboard tube 20 according to one embodiment, the end edge 152 is positioned above the tube forming roller 112. The upper holding roller 300 is placed in an idle position such that it is spaced upward from the tube forming roller 112, and the end edge 152 is positioned between the tube forming roller 112 and the upper holding roller 300.

[0141] like Figure 9B As shown, the upper holding roller 300 is then lowered to a holding position, in which the detached cardboard sheet 160 is positioned above the tube forming roller 112. A vacuum source is then engaged to generate suction through the suction port 202 to hold the end edge 152 against the tube forming roller 112. The suction nozzle member 220 can also be positioned in an extended position.

[0142] like Figure 9CAs shown, the tube forming roller 112 can then be rotated forward to form a first winding, with the end edge 152 remaining abutting against the tube forming roller 112. The tube forming roller 112 can then be further rotated at the same or greater speed to form the remaining windings, during which time the vacuum source can be deactivated and the suction nozzle member 220 can be moved back to the retracted position. As described above, an adhesive such as PVA, dextrin, or silicate is further provided as the tube forming roller 112 rotates. In one embodiment, the tube forming roller is rotated a total of 6 to 10 times to form a wound paperboard tube 20 having 6 to 10 layers of paperboard. Alternatively, the tube forming roller can be rotated a total of fewer than 6 times or more than 10 times.

[0143] Figure 9D A wound paperboard tube 20 formed around a tube-forming roller 112 is shown, wherein an upper retaining roller 300 is adjacent to the wound paperboard tube 20. (See diagram) Figure 9E As shown, the upper holding roller 300 is then raised back to its idle position. The unwound cardboard sheet 160 is cut laterally adjacent to the tube forming roller 112 to separate the wound cardboard tube 20 from the remainder of the unwound cardboard sheet 160. In one embodiment, the unwound cardboard sheet 160 is cut before the upper holding roller 300 is raised, but alternatively, the unwound cardboard sheet 160 can be cut after the upper holding roller 300 is raised.

[0144] like Figure 9F As shown, the wound cardboard tube 20 can then be removed from the tube forming roller 112. In the illustrated embodiment, the wound cardboard tube 20 is removed using a tube removal assembly 400. Specifically, the carriage 402 is moved along the carriage track 406 such that the annular member 110 pushes the wound cardboard tube 20 toward the end of the tube forming roller 112 and completely disengages it from the tube forming roller 112.

[0145] It should be understood that the location where the untied cardboard sheet 160 is cut now defines a new end edge of the untied cardboard sheet 160, which can then be engaged by the gripping mechanism 200 to form a new wound cardboard tube 20.

[0146] In one implementation, the adhesive can then be fixed. Specifically, the adhesive can be fixed simply by waiting for a certain amount of time. Alternatively, active adhesive fixing techniques can be used, such as using ultraviolet light, heat, or any other suitable technique to fix or cure the adhesive.

[0147] In one embodiment, the wound cardboard tube 20 may also be dried to reduce its humidity level to a desired level, which may be substantially equal to or less than about 7%, more specifically about 4.5%. Drying can be performed by allowing the wound cardboard tube 20 to stand in a relatively dry environment for a certain period of time, or by using a drying device. Alternatively, the wound cardboard tube 20 may not be dried.

[0148] In one embodiment, a film, such as a plastic film 50, can then be wound around the wound cardboard tube 20 to form a plastic film roll 15. Specifically, the winding of the plastic film 50 around the wound cardboard tube 20 can be carried out in the same facility as the one used to manufacture the wound cardboard tube 20, i.e., a plastic film roll manufacturing facility. For example, if the wound cardboard tube 20 is manufactured using equipment 100, equipment 100 can be provided at the plastic film roll manufacturing facility. This can help maintain the wound cardboard tube 20 at a desired humidity level by reducing time, number of operations, and potential environmental changes between the manufacture of the wound cardboard tube 20 and the manufacture of the plastic film roll 15. Alternatively, the wound cardboard tube 20 can be manufactured in a first facility, such as a wound cardboard tube manufacturing facility, and then transferred to a second facility, such as a plastic film roll manufacturing facility, where the plastic film 50 is wound around the wound cardboard tube 20.

[0149] It is understood that the spiral wound tube 20 of the present invention is cheaper to manufacture than those known in the art, not only because it uses scrap or waste paperboard as its raw material (in fact, rolls of scrap or waste paperboard are relatively cheaper than the paperboard currently used to manufacture spiral or helical wound tubes or mandrels), but also because less material is required to form the tube due to the selection of paperboard with specific characteristics (weight, tensile strength, moisture level, fiber orientation). The invention also contributes to reducing the greenhouse effect by using scrap paperboard as its raw material, eliminating the need to specifically manufacture paperboard for the purpose of making the tube. It is also particularly suitable for applications involving radial compression, such as those using stretchable films or plastic films. Advantageously, since there are no gaps between the continuously wound strips or layers, as in the case of a helical mandrel, the core undergoes almost no breakage when radially compressed.

[0150] Furthermore, the fact that wound cardboard tubes, while having thinner walls than their corresponding conventional spiral tubes, can resist the same radial compressive forces offers additional advantages. For example, wound cardboard tubes typically experience a "springback" effect, where the cut edge of the cardboard tube in the final wound layer may tend to move before the adhesive is fully cured due to slight tension that may be generated in the winding as the tube forming rollers rotate. It has been observed that forming tubes with lower wall thickness reduces this springback effect, thereby helping to prevent the cut edge from moving relative to the rest of the tube when the adhesive has cured.

[0151] Although preferred embodiments of the invention have been described in detail herein and shown in the accompanying drawings, it should be understood that the invention is not limited to these exact embodiments, but can be modified and varied without departing from the scope of the invention.

Claims

1. A plastic film roll comprising: a wound paperboard tube comprising a tubular body having a tubular body wall formed of a plurality of layers of straight wound paperboard sheets, the paperboard sheets having a weight equal to or less than 300 gsm; a plastic film wound around the wound paperboard tube to form a plurality of plastic film windings around the wound paperboard tube, the plastic film windings exerting a radial compressive force on the tubular body wall equal to or greater than 10 bar, wherein the paperboard sheets comprise a plurality of fibers, at least a majority of the fibers being aligned in a tangential direction relative to the tubular body to allow the wound paperboard tube to resist the radial compressive force.

2. The plastic film roll of claim 1, wherein the wall has a wall thickness less than 7.5 mm.

3. The plastic film roll of claim 1, wherein the radial compressive force exerted on the tubular body wall by the plastic film windings is equal to or greater than 35 bar.

4. The plastic film roll of claim 1, wherein the wall has a thickness less than 5 mm, and wherein the radial compressive force exerted on the tubular body wall by the plastic film windings is equal to or greater than 28 bar.

5. The plastic film roll of claim 1, wherein the plastic film windings are wound around the wound paperboard tube by a machine.

6. The plastic film roll of claim 1, wherein all of the fibers are aligned in a tangential direction relative to the tubular body.

7. The plastic film roll of claim 1, wherein the tubular body has a tensile strength equal to or greater than 60 kg / mm.

8. The plastic film roll of claim 1, wherein the paperboard sheets have a weight equal to or less than 140 gsm.

9. The plastic film roll of claim 1, wherein the plurality of layers of straight wound paperboard sheets comprises 6 to 10 layers.

10. The plastic film roll of claim 1, wherein the paperboard sheets comprise cut edges defining shoulders on an outer surface of the tubular body, the shoulders having a height equal to or less than 1.2 mm.

11. The plastic film roll of claim 1, wherein the tubular body has a moisture level equal to or less than 7%.

12. The plastic film roll of claim 1, wherein the tubular body has a moisture level equal to or less than 6%.

13. The plastic film roll of claim 1, wherein the tubular body has a moisture level equal to 4.5%.

14. The plastic film roll of claim 1, wherein the paperboard sheets are made from scrap paperboard.

15. The plastic film roll of claim 1, wherein the paperboard sheets have a sheet width defined in a cross direction of the paperboard sheets, the sheet width being equal to a length of the tubular body.

16. The plastic film roll of claim 1, wherein the plurality of layers of straight wound paperboard sheets are adhered together using an adhesive selected from polyvinyl acetate, dextrin, and silicate.

17. The plastic film roll of claim 1, wherein the tubular body has an inner diameter of 40 mm to 200 mm.

18. The plastic film roll of claim 1, wherein the tubular body has an inner diameter of 74 mm to 78 mm.

19. The plastic film roll of claim 1, wherein the tubular body has an inner diameter of 76 mm.

20. The plastic film roll of claim 1, wherein the sheet of straight-wound paperboard sheets has a sheet thickness of 0.72 mm to 1.2 mm.

21. A wound paperboard tube for winding a plastic film, comprising: a tubular body having a tubular body wall formed from a plurality of straight- wound paperboard sheets, the paperboard sheets having a weight equal to or less than 300 gsm, the paperboard sheets including a plurality of fibers, at least a majority of the fibers being aligned in a tangential direction relative to the tubular body to allow the wound paperboard tube to resist a radial compressive force equal to or greater than 10 bar against the tubular body wall, wherein the radial compressive force is from the plastic film.

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