Counter-pressure roller, pressure roller device and method for forming a longitudinal seal of a web of packaging material

Abstract

A counter-pressure roller (102) is provided for applying pressure to a longitudinal seal (202) of a roll of packaging material. The counter-pressure roller (102) includes: a first back panel support portion (104) having a first radius (R1) and a second back panel support portion (106) having a second radius (R2), which are respectively used to support a first (108) and a second (110) back panel of the roll, wherein the first radius (R1) is greater than the second radius (R2); and a groove (112) located between the first (104) and second (106) back panel support portions for retaining longitudinal overlap portions (204) formed by the first and second edge portions of the first (108) and second (110) back panels, respectively. The first edge portion is arranged to be placed outside the second edge portion such that the first edge portion faces the bottom (302) of the groove (112), wherein the bottom (302) has a third radius (R3) less than or equal to the second radius (R2), wherein the groove (112) has a first groove edge portion (304) with a first inclination angle (α) between the first back panel support portion (104) and the bottom portion (302), and a second groove edge portion (306) with a second inclination angle (β) between the second back panel support portion (106) and the bottom portion (302).

Description

Technical Field

[0001] This invention relates to packaging technology. More specifically, this invention relates to a counter-pressure roller for applying pressure to the longitudinal seal of a roll of packaging material. Background Technology

[0002] Today, packaging is a crucial part of the food industry. Besides branding and providing information to customers, packaging plays a vital role in ensuring food safety. Packaging materials are designed to provide strength and stability, preventing damage during transport. Furthermore, packaging materials create a protected environment for food, shielding it from factors such as bacteria, germs, oxygen, and sunlight. However, packaging materials are not the only important element. Proper sealing is also essential. In roller-feed systems, this is typically achieved by forming a longitudinal seal along the overlap between the two ends of the packaging material, creating a tube, and then forming the package from the tube by a transverse seal at the lower end.

[0003] Traditionally, longitudinal overlap sealing is achieved by applying pressure to the two overlapping ends and providing a longitudinal sealing strip within the cardboard packaging section, thus sealing them together. The longitudinal sealing strip is applied to the overlap on the inside of the packaging to prevent the inner end of the packaging material from contacting the product contained within. When using cardboard-based packaging materials, the longitudinal sealing strip forms a barrier between the cardboard layers of food and packaging material. Therefore, using and safely applying longitudinal sealing strips is a key factor in providing environmentally friendly food packaging.

[0004] To ensure proper longitudinal sealing, current solutions for forming the longitudinal seal typically require high pressure. Exposing components to such high pressure leads to accelerated wear, resulting in higher maintenance costs. In addition to the high pressure, roller-feed packaging machines operate at speeds of up to 30,000 packages per hour in some cases. The speeds involved introduce other types of challenges. For example, even minor deviations can quickly lead to machine malfunction and breakdown.

[0005] Based on the above, in order to further reduce maintenance requirements and production downtime, and to further improve productivity, a more reliable longitudinal sealing system is needed for roller feed packaging machines and other similar types of equipment. Summary of the Invention

[0006] One object of the present invention is to overcome, at least in part, one or more of the limitations of the prior art. In particular, one object is to provide an improved counter-pressure roller and a method for forming a longitudinal seal.

[0007] It has been recognized that by providing asymmetrical counter-pressure rollers that take into account thickness differences due to overlapping packaging materials, pressure can be concentrated on the area related to sealing. This reduces the applied pressure because less pressure is wasted in areas not addressed during the sealing process. Furthermore, improved pressure distribution in the relevant areas is achieved.

[0008] According to a first aspect, a counter-pressure roller is provided for applying pressure to a longitudinal seal portion of a packaging material roll. The counter-pressure roller includes:

[0009] A first back panel support portion having a first radius and a second back panel support portion having a second radius are respectively used to support the first back panel and the second back panel of the roll material.

[0010] The first radius is greater than the second radius.

[0011] A groove located between the first back panel support portion and the second back panel support portion is used to retain the longitudinally overlapping portion formed by the first edge portion and the second edge portion of the first back panel and the second back panel, respectively.

[0012] The first edge portion is positioned outside the second edge portion, such that the first edge portion faces the bottom of the groove.

[0013] The bottom portion has a third radius that is less than or equal to the second radius.

[0014] The groove has a first groove edge portion with a first inclination angle (α) between the first back panel support portion and the bottom portion, and a second groove edge portion with a second inclination angle (β) between the second back panel support portion and the bottom portion.

[0015] The second inclination angle can be any angle between 0 and 90 degrees. In other words, the radius of the second back panel support portion can be the same as the radius of the groove.

[0016] Packaging materials can be multi-layered. They may include layers of thick cardboard.

[0017] Having a first back panel support portion with a larger radius than the second back panel support portion is advantageous because the overlapping packaging material can be arranged in a way that compensates for thickness differences. In this way, the portion below the overlap portion that would otherwise be difficult to seal can be exposed to the applied pressure. The groove also helps to arrange the longitudinal seal in a way that ensures the applied pressure is evenly distributed.

[0018] The first tilt angle (α) relative to the central axis of the counter-pressure roller can be 10-30 degrees.

[0019] A roll gap edge can be formed between the first back panel support portion and the groove, such that when the longitudinal overlap portion faces the bottom, the roll gap edge faces the longitudinal sealing strip portion.

[0020] The advantage of forming the roll gap edge may be that it provides an increased back pressure point in areas where it is usually difficult to form a proper seal.

[0021] The groove may have a depth from the second back panel support portion to the bottom of the groove, which is less than or equal to 1.5 times the thickness of the packaging material.

[0022] Compared to the first back panel support portion, the bottom of the groove can be placed closer to the second back panel support portion.

[0023] The first tilt angle (α) can be less than or equal to the second tilt angle (β).

[0024] The second tilt angle relative to the central axis of the counter-pressure roller can be 80-90 degrees, such that the edge portion of the second groove is arranged to face the end of the first edge portion of the packaging material.

[0025] The advantage of having a near-vertical second tilt angle is that it prevents the packaging material roll from slipping toward the second back panel support portion (106), since the edge portion of the first back panel support portion (104) faces the edge portion of the second groove (306). Therefore, the correct placement of the longitudinal seal portion (202) on the counter-pressure roller (102) can be ensured.

[0026] The pressure roller can be made of a rigid material. One advantage of doing so is that it prevents the shape of the pressure roller (102) from deforming under pressure.

[0027] According to a second aspect, a pressure roller device is provided for applying pressure to a longitudinal sealing portion of a packaging material roll. The pressure roller device includes a pair of rollers for applying pressure to a longitudinal sealing strip portion. The roller pair includes a pressure roller and a counter-pressure roller according to a first aspect arranged opposite to the pressure roller.

[0028] The pressure roller assembly may also include an additional pair of rollers for applying pressure to the longitudinal overlap portion of the packaging material. The additional pair of rollers may include an additional pressure roller and an additional counter-pressure roller arranged opposite to the additional pressure roller. The additional pair of rollers may be arranged to apply general pressure to the longitudinal seal.

[0029] Having roller pairs and additional roller pairs can be advantageous because two roller pairs can concentrate pressure on different areas of the longitudinal seal. By doing so, pressure wasted in unrelated areas can be reduced.

[0030] Additional roller pairs can be arranged upstream of the roller pairs.

[0031] According to a third aspect, a method for forming a longitudinal seal portion of a packaging material roll is provided. The method includes receiving a packaging material roll, providing a longitudinal sealing strip along one edge of the packaging material roll, forming a packaging material roll tube, applying heat to a first edge portion and a second edge portion of the packaging material roll, forming a longitudinal overlap portion between the first edge portion and the second edge portion of the packaging material roll, feeding the roll to a pressure roller assembly, the pressure roller assembly including: a pair of rollers for applying pressure to the longitudinal sealing strip portion, wherein the roller pair includes: a pressure roller, and a counter-pressure roller arranged opposite to the pressure roller for applying pressure to the longitudinal seal portion of the packaging material roll, wherein the counter-pressure roller includes: a first back panel support portion having a first radius and a second back panel support portion having a second radius, respectively supporting the first and second back panels of the roll. The groove, with a first radius greater than the second radius, is located between the first back panel support portion and the second back panel support portion. It is used to hold the longitudinal overlap portion formed by the first edge portion and the second edge portion of the first back panel and the second back panel, respectively. The first edge portion is arranged to be placed outside the second edge portion, such that the first edge portion faces the bottom of the groove. The bottom portion has a third radius less than or equal to the second radius. The groove has a first groove edge portion with a first inclination angle (α) between the first back panel support portion and the bottom and a second groove edge portion with a second inclination angle (β) between the second back panel support portion and the bottom. Pressure is applied along the longitudinal sealing portion using a pressure roller device, such that the first edge portion and the second edge portion of the packaging material roll and the longitudinal sealing strip are sealed together.

[0032] The step of applying pressure may include a sub-step of applying general pressure to the longitudinal seal using an additional pair of rollers, the additional pair of rollers being included in the pressure roller assembly for applying pressure to the longitudinal overlap portion of the packaging material, wherein the additional pair of rollers may include: an additional pressure roller and an additional counter-pressure roller arranged opposite to the additional pressure roller, wherein the additional rollers are arranged to apply general pressure to the longitudinal seal.

[0033] The step of feeding the roll material into the pressure roller device may include a sub-step of feeding a longitudinally overlapping portion into a groove having a depth from the second back panel support portion to the bottom of the groove, the depth being less than or equal to 1.5 times the thickness of the packaging material.

[0034] The step of applying pressure may include a sub-step of aligning the longitudinal sealing strip portion with the edge of the roll gap formed between the first back panel support portion and the groove.

[0035] Other objects, features, aspects, and advantages of the invention will become apparent from the following detailed description and accompanying drawings. Unless otherwise expressly stated, the same features and advantages described with respect to one aspect apply to the other aspects. Attached Figure Description

[0036] Embodiments of the invention will now be described by way of example with reference to the accompanying schematic diagrams, wherein...

[0037] Figure 1 This is a cross-sectional view of an example of a counter-pressure roller.

[0038] Figure 2 Different portions of the longitudinal seal between the two ends of the packaging material roll are shown.

[0039] Figure 3 Different cross-sections and measurements of the counter-pressure roller are shown.

[0040] Figure 4 This is a flowchart illustrating the steps of a method for forming a longitudinal seal in a roll of packaging material.

[0041] Figures 5a-5e Different examples of the shape of the counter-pressure roller are shown.

[0042] Figure 6 A pressure roller device for applying pressure to the longitudinal seal of a roll of packaging material is shown. Detailed Implementation

[0043] Figure 1 This is a cross-sectional view 100 of an example of a counter-pressure roller 102 used to apply pressure to the longitudinal seal 202 of a packaging material roll. It also shows how the longitudinal overlap 204 of the packaging material roll can be arranged on the counter-pressure roller 102 together with the longitudinal sealing strip 118 to form the longitudinal seal 202.

[0044] The counter-pressure roller 102 has a first back panel support portion 104 for supporting a first back panel 108 of the roll material. Furthermore, the counter-pressure roller 102 has a second back panel support portion 106 for supporting a second back panel 110 of the roll material. In this embodiment, the first back panel support portion 104 has a first radius that is larger than the second radius of the second back panel support portion 106.

[0045] Subsequently, after the longitudinal and transverse seals have been performed, the first and second back panel support portions 104, 106 can together form the back panel of the package. Currently, it is common practice to place the longitudinal seal on the back panel of the package; that is, the longitudinal seal is not typically placed on the panel intended for the customer, but functionally this is not necessary. Therefore, even though the section referred to herein as being related to the back panel should be understood to be limited to a specific panel of the package.

[0046] A groove 112 is provided on the anti-pressure roller 102 between the first back panel support portion 104 and the second back panel support portion 106. The groove 112 is arranged to hold a longitudinal overlap portion 204 formed by the first edge portion and the second edge portion of the first back panel 108 and the second back panel 110. The first edge portion may be arranged to be positioned outside the second edge portion such that the first edge portion faces the bottom 302 of the groove 112. In this example, the depth of the groove 112 is similar to the thickness of the packaging material, so that the second back panel 110 can remain flat on the second back panel support portion 106 and the bottom 302 of the groove 112. The groove 112 itself has a first groove edge portion 304 and a second groove edge portion 306 having a first tilt angle α and a second tilt angle β, respectively. In this non-limiting example, the tilt angle α is 10-30 degrees relative to the central axis 114 of the anti-pressure roller 102. In this example, the tilt angle β is 80-90 degrees relative to the central axis. In other words, the second groove edge portion 306 is substantially vertical. Combination Figure 3 The edge portions of the first and second grooves are further described.

[0047] A roll gap edge 116 is formed between the first back panel support portion 104 and the groove 112, such that the roll gap edge faces the longitudinal sealing strip portion. The roll gap edge 116 can provide a point of increased pressure to ensure a proper seal. The roll gap edge 116 can be positioned, for example, at the point on the longitudinal sealing strip portion 206 closest to the longitudinal overlap portion 204.

[0048] Figure 2 Different portions of the longitudinal seal 202 between the two ends of the packaging material roll are shown. The figure shows portions of the first back panel 108 and the second back panel 110 of the roll, as well as the longitudinal sealing strip 118, in cross-section. Only the portion where the two ends of the packaging material meet is shown here. It should be understood that these two ends are opposite ends of the same packaging material roll, i.e., forming a closed body when placed together. The longitudinal sealing strip 118 is located on the inside of the package.

[0049] The longitudinal sealing portion 202 refers to the portion that needs to be sealed. The longitudinal sealing portion 202 includes a longitudinal overlapping portion 204 and a longitudinal sealing strip portion 206.

[0050] The longitudinal overlap portion 204 refers to the portion of the longitudinal sealing portion 202 at the overlap between the first back panel 108 and the second back panel 110 of the roll material.

[0051] The longitudinal sealing strip portion 206 refers to the portion of the longitudinal sealing strip 118 that is attached to the first back panel 108 of the roll material.

[0052] Figure 3 Different portions of the counter-pressure roller 102 and their measurements are shown. The first back panel support portion 104 may have a first radius, denoted herein by R1. Similarly, the second back panel support portion 106 may have a second radius, denoted by R2. The third radius R3 can be defined as the radius of the counter-pressure roller 102 at the bottom 302 of the groove 112. The depth D4 of the groove 112 can also be defined as the difference between the second radius R2 and the third radius R3. The relationship between the radii can be expressed as R1 > R2 and R2 ≥ R3, therefore R1 > R3.

[0053] The groove 112 can be divided into three parts. The first groove edge portion 304 has a width D1, the second groove edge portion 306 has a width D2, and the bottom 302 has a width D3. The width D2 can be zero, resulting in the second groove edge portion 306 being a vertical edge. The width D3 can be zero, resulting in the bottom 302 being a single point.

[0054] The first groove edge portion 304 and the second groove edge portion 306 may each have a first tilt angle α and a second tilt angle β. The second tilt angle β may take any value between 0 and 90 degrees. The first tilt angle α may be less than the second tilt angle β. Both the first and second tilt angles may include multiple individual tilt angles. In this case, α and β may represent effective tilt angles defined by a line between the points defining the start and end points of the first groove edge portion 304 and the second groove edge portion 306, respectively.

[0055] Figure 4 This is a flowchart illustrating the steps of a method 400 for forming a longitudinal seal 202 of a packaging material roll.

[0056] In the first step 402, the packaging material roll is received.

[0057] In the second step 404, a longitudinal sealing strip 118 is provided along one edge of the packaging material roll.

[0058] In the third step 406, a tube is formed from the packaging material roll.

[0059] In the fourth step 408, heat is applied to the first and second edge portions of the packaging material roll.

[0060] In the fifth step 410, a longitudinal overlap 204 is formed between the first edge portion 108 and the second edge portion 110 of the packaging material roll.

[0061] In step 412, the packaging material roll is fed into the pressure roller assembly 600. The pressure roller assembly 600 includes a pair of rollers 608 for applying pressure to the longitudinal sealing strip portion 206. The roller pair 608 includes a pressure roller 610 and a counter-pressure roller 102 disposed opposite to the pressure roller 610. The counter-pressure roller 102 includes a first back panel support portion 104 having a first radius R1 and a second back panel support portion 106 having a second radius R2, which respectively support the first back panel 108 and the second back panel 110 of the roll. The first radius R1 may be larger than the second radius R2. The counter-pressure roller 102 also includes a groove 112 located between the first back panel support portion 104 and the second back panel support portion 106 for retaining the longitudinal overlap portion 204 formed by the first edge portion and the second edge portion of the first back panel 108 and the second back panel 110, respectively. The first edge portion may be arranged outside the second edge portion such that the first edge portion faces the bottom of the groove 112. The bottom 302 has a third radius R3 that is less than or equal to the second radius R2. The groove 112 has a first groove edge portion 304 with a first inclination angle α between the first back panel support portion 104 and the bottom 302, and a second groove edge portion 306 with a second inclination angle β between the second back panel support portion 106 and the bottom 302.

[0062] In the seventh step 414, pressure is applied along the longitudinal sealing portion 202 using the pressure roller device 600, so that the first edge portion and the second edge portion of the packaging material roll and the longitudinal sealing strip 118 are sealed together.

[0063] Optionally, the seventh step 414 of applying pressure may include a sub-step of applying general pressure to the longitudinal seal 202 using an additional roller pair 602, which is included in a pressure roller assembly 600 for applying pressure to the longitudinal overlap portion 204 of the packaging material. The additional roller pair 602 may include an additional pressure roller 606 and an additional counter-pressure roller 604 arranged opposite to the additional pressure roller 606. The additional roller pair may be arranged to apply general pressure to the longitudinal seal 202. The additional roller pair 602 may be used in the fifth step 412 of forming the longitudinal overlap portion 204.

[0064] Optionally, the sixth step of feeding the roll material into the pressure roller device 600 may include a sub-step of feeding the longitudinal overlap portion 204 into a groove 112 having a depth D4 from the second back panel support portion 106 to the bottom 302 of the groove 112, the depth D4 being less than or equal to 1.5 times the thickness of the packaging material.

[0065] Optionally, the seventh step of applying pressure may include a sub-step of aligning the longitudinal sealing strip portion 206 with the roll gap edge 116 formed between the first back panel support portion 104 and the groove 112.

[0066] Even if described in a specific order, different steps can be performed in other orders, and can be performed multiple times.

[0067] Figures 5a-5e Different embodiments of the counter-pressure roller 102 are illustrated by way of example. The counter-pressure roller 102 is depicted as the outline of a cross-sectional view of the upper part of the counter-pressure roller 102.

[0068] Figure 5a The embodiment of the counter-pressure roller shown has Figure 1 and Figure 3 The anti-pressure roller 102 has many features. The radius of the first back panel support portion 104 is larger than the radius of the second back panel support portion 106. Furthermore, the inclination angle of the first groove edge portion 304 is smaller than the inclination angle of the second groove edge portion 306. Therefore, the bottom 302 of the groove is closer to the second back panel support portion 106 than the first back panel support portion 104. Here, the bottom 302 of the groove is shown as having a width (D3) other than zero. The width (D3) of the groove can be any value of zero or higher.

[0069] Figure 5b The second groove edge portion 306 is shown to be vertical.

[0070] Figure 5c This is an example of how the bottom 302 of the groove can be almost zero, which is similar to... Figure 5a and Figure 5b The bottom shown forms a contrast.

[0071] Figure 5d An embodiment with a second tilt angle of zero degrees is shown. In other words, the radius of the second back panel support portion 106 is the same as the radius of the bottom 302 of the recess. For illustrative purposes, the second back panel support portion 106, the second recess edge portion 306, and the bottom 302 refer to different parts of the flat portion. However, how they are divided is not important, as they are all part of the same planar portion.

[0072] Figure 5e The diagram illustrates how the edge portion 306 of the second groove can have a gradually changing tilt angle. In other words, it can be composed of multiple individual tilt angles of different values. The same applies to the first tilt angle.

[0073] Apart from Figures 5a-5eOther embodiments of the counter-pressure roller besides those shown are also possible. For example, the feature shown in one of these figures can be combined with the feature shown in another figure. As a non-limiting example, the second tilt angle can be as follows: Figure 5b As shown, it is vertical, and the bottom 302 of the groove can be as follows: Figure 5c As shown, it is a single point.

[0074] Figure 6 An example is shown of a pressure roller device 600 for applying pressure to the longitudinal sealing portion 202 of a packaging material roll.

[0075] The pressure roller assembly 600 may include a pair of rollers 608 for applying pressure to the longitudinal sealing strip portion 206. The roller pair 608 may include a pressure roller 610 and a counter-pressure roller 102. The counter-pressure roller 102 may be a counter-pressure roller according to the first aspect. The counter-pressure roller 102 may be arranged opposite to the pressure roller 610 such that they can apply pressure to the longitudinal sealing portion 202 of the packaging material roll passing between the roller pair 608.

[0076] The pressure roller assembly 600 may further include an additional roller pair 602 for applying pressure to the longitudinal overlap portion 204 of the packaging material. The additional roller pair 602 may include an additional pressure roller 606 and an additional counter-pressure roller 604 arranged opposite to the additional pressure roller 606. The additional roller pair 602 may be arranged to apply general pressure to the longitudinal seal portion 202.

[0077] An additional roller pair 602 may be arranged upstream of roller pair 608. In this case, the additional roller pair 602 may apply pressure on a larger portion of the roll material than roller pair 608, thereby allowing general pressure to be applied first to generally attach the sealing strip, and then specific pressure to be applied on specific portions to target the attachment of the sealing strip.

[0078] The counter-pressure roller 102 and the additional counter-pressure roller 604 can be made of rigid material so that they will not deform under pressure. Furthermore, they can be mounted on a fixed shaft so that they remain in place when subjected to pressure.

[0079] The pressure roller 610 and the additional pressure roller 606 can be suspended on a shaft connected to the device for applying pressure. Furthermore, they can be made of a flexible material such as rubber.

[0080] like Figure 6 As shown, the different rollers of the pressure roller device 600 can have different diameters.

[0081] The pressure roller assembly 600 can be provided as an upgrade kit to existing roller-feed packaging machines. In other words, in addition to being a component of the packaging machine and included in the assembly process, the pressure roller assembly can also be used to upgrade existing packaging machines.

[0082] As can be seen from the above description, although various embodiments of the present invention have been described and shown, the present invention is not limited thereto, but may be embodied in other ways within the scope of the subject matter defined by the appended claims.

Claims

1. A counter-pressure roller (102) for applying pressure to a longitudinal sealing portion (202) of a roll of packaging material, wherein, The reverse pressure roller (102) includes: A first back panel support portion (104) having a first radius (R1) and a second back panel support portion (106) having a second radius (R2) are respectively used to support the first back panel (108) and the second back panel (110) of the roll material. Wherein the first radius (R1) is greater than the second radius (R2), A groove (112) located between the first back panel support portion (104) and the second back panel support portion (106) is used to hold the longitudinally overlapping portion (204) formed by the first edge portion and the second edge portion of the first back panel (108) and the second back panel (110), respectively. The first edge portion is arranged to be placed outside the second edge portion, such that the first edge portion faces the bottom (302) of the groove (112). The bottom (302) has a third radius (R3) smaller than the second radius (R2). The groove (112) has a first groove edge portion (304) with a first inclination angle (α) between the first back panel support portion (104) and the bottom portion (302), and a second groove edge portion (306) with a second inclination angle (β) between the second back panel support portion (106) and the bottom portion (302), wherein the first inclination angle (α) is smaller than the second inclination angle (β).

2. The counter-pressure roller (102) according to claim 1, in, The first tilt angle (α) is 10-30 degrees relative to the central axis (114) of the counter-pressure roller (102).

3. The counter-pressure roller (102) according to claim 1 or 2, wherein, A roll gap edge (116) is formed between the first back panel support portion (104) and the groove (112) such that when the longitudinal overlap portion (204) faces the bottom (302), the roll gap edge (116) faces the longitudinal sealing strip portion (206).

4. The counter-pressure roller (102) according to claim 1 or 2, wherein, The depth (D4) of the groove (112) from the second back panel support portion (106) to the bottom (302) of the groove (112) is less than or equal to 1.5 times the thickness of the packaging material.

5. The counter-pressure roller (102) according to claim 1 or 2, wherein, The bottom (302) of the groove (112) is closer to the second back panel support portion (106) than the first back panel support portion (104).

6. The counter-pressure roller (102) according to claim 1 or 2, wherein, The second tilt angle is 80-90 degrees relative to the central axis (114) of the counter-pressure roller (102), such that the second groove edge portion (306) is arranged to face the end of the first edge portion of the packaging material.

7. The counter-pressure roller (102) according to claim 1 or 2, wherein, The counter-pressure roller (102) is made of a rigid material.

8. A pressure roller device (600) for applying pressure to a longitudinal sealing portion (202) of a roll of packaging material, comprising, Roller pair (608) for applying pressure to the longitudinal sealing strip portion (206), The roller pair (608) includes: Pressure roller (610), and The counter-pressure roller (102) according to any one of claims 1-7 is disposed opposite to the pressure roller (610).

9. The pressure roller device (600) according to claim 8, further comprising: Additional roller pair (602) for applying pressure to the longitudinal overlap portion (204) of the packaging material, The additional roller pair (602) includes: Additional pressure roller (606), and An additional counter-pressure roller (604) is arranged opposite to the additional pressure roller (606). The additional rollers are arranged to apply general pressure to the longitudinal seal (202).

10. The pressure roller device according to claim 9, in, The additional roller pair (602) is arranged upstream of the roller pair (608).

11. A method (400) for forming a longitudinal seal (202) of a roll of packaging material, the method comprising, Receive (402) the packaging material roll, A longitudinal sealing strip (118) is provided (404) along one edge of the packaging material roll. A (406) tube is formed from the packaging material roll. Heat (408) is applied to the first and second edge portions of the packaging material roll. A longitudinal overlap (204) is formed (410) between the first edge portion and the second edge portion of the packaging material roll. The roll material is fed (412) to a pressure roller assembly (600), the pressure roller assembly (600) comprising: Roller pair (608) for applying pressure to the longitudinal sealing strip portion (206), The roller pair (608) includes: Pressure roller (610), and A counter-pressure roller (102) arranged opposite to the pressure roller (610) is used to apply pressure to the longitudinal sealing portion (202) of the packaging material roll, wherein the counter-pressure roller (102) comprises: A first back panel support portion (104) having a first radius (R1) and a second back panel support portion (106) having a second radius (R2) are respectively used to support the first back panel (108) and the second back panel (110) of the roll material. Wherein the first radius (R1) is greater than the second radius (R2), A groove (112) located between the first back panel support portion (104) and the second back panel support portion (106) is used to hold the longitudinally overlapping portion (204) formed by the first edge portion and the second edge portion of the first back panel (108) and the second back panel (110), respectively. The first edge portion is arranged to be placed outside the second edge portion, such that the first edge portion faces the bottom (302) of the groove (112). The bottom (302) has a third radius (R3) smaller than the second radius (R2). The groove (112) has a first groove edge portion (304) with a first inclination angle (α) between the first back panel support portion (104) and the bottom (302), and a second groove edge portion (306) with a second inclination angle (β) between the second back panel support portion (106) and the bottom (302), wherein the first inclination angle (α) is smaller than the second inclination angle (β). The pressure roller device (600) applies pressure (414) along the longitudinal sealing portion (202) to seal the first edge portion and the second edge portion of the packaging material roll together with the longitudinal sealing strip (118).

12. The method (400) of claim 11, wherein the step of applying pressure comprises: The sub-step of applying general pressure to the longitudinal seal (202) using an additional pair of rollers (602), the additional pair of rollers (602) being included in the pressure roller assembly (600) for applying pressure to the longitudinal overlap portion (204) of the packaging material. The additional roller pair (602) includes: Additional pressure roller (606), and An additional counter-pressure roller (604) is arranged opposite to the additional pressure roller (606). The additional rollers are arranged to apply general pressure to the longitudinal seal (202).

13. The method (400) of claim 11, wherein the step of feeding the roll to the pressure roller device includes a sub-step of feeding the longitudinal overlap (204) into the groove (112), the groove having a depth (D4) from the second back panel support portion (106) to the bottom (302) of the groove (112), the depth (D4) being less than or equal to 1.5 times the thickness of the packaging material.

14. The method according to any one of claims 11 to 13, wherein the step of applying pressure includes a sub-step of aligning the longitudinal sealing strip portion (206) with the roll gap edge (116) formed between the first back panel support portion (104) and the groove (112).

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