Counter-pressure roller, an arrangement and a method thereof

A counter-pressure roller for applying pressure on a longitudinal sealing of a web of packaging material, wherein the counter-pressure roller comprises,

• a first back-panel support section having a first radius and a second back-panel support section having a second radius, for supporting a first and a second back-panel of the web, respectively,
• wherein the first radius is greater than the second radius,
• a groove between the first and second back-panel support sections, for holding a longitudinal overlap section formed by a first and second edge section of the first and second back-panels, respectively,
• wherein the first edge section is arranged to be placed outside the second edge section such that the first edge section is facing a bottom of the groove,
• wherein the bottom of the groove has a third radius that is less than the second radius,
• wherein the groove has a first groove edge section, between the first back-panel support section and the bottom of the groove, having a first inclination and a flat shape in a longitudinal cross-section, and a second groove edge section, between the second back-panel support section and the bottom of the groove, having a second inclination, the first inclination being less than 90 degrees from a central axis of the counter-pressure roller.

A counter-pressure roller for applying pressure on a longitudinal sealing of a web of packaging material, wherein the counter-pressure roller comprises,

• a first back-panel support section having a first radius and a second back-panel support section having a second radius, for supporting a first and a second back-panel of the web, respectively,
• wherein the first radius is greater than the second radius,
• a groove between the first and second back-panel support sections, for holding a longitudinal overlap section formed by a first and second edge section of the first and second back-panels, respectively,
• wherein the first edge section is arranged to be placed outside the second edge section such that the first edge section is facing a bottom of the groove,
• wherein the bottom of the groove has a third radius that is less than the second radius,
• wherein the groove has a first groove edge section, between the first back-panel support section and the bottom of the groove, having a first inclination, and a second groove edge section, between the second back-panel support section and the bottom of the groove, having a second inclination,
• the first inclination being 10-30 degrees from a central axis of the counter-pressure roller.

A counter-pressure roller for applying pressure on a longitudinal sealing of a web of packaging material, wherein the counter-pressure roller comprises,

• a first back-panel support section having a first radius and a second back-panel support section having a second radius, for supporting a first and a second back-panel of the web, respectively,
• wherein the first radius is greater than the second radius,
• a groove between the first and second back-panel support sections, for holding a longitudinal overlap section formed by a first and second edge section of the first and second back-panels, respectively,
• wherein the first edge section is arranged to be placed outside the second edge section such that the first edge section is facing a bottom of the groove,
• wherein the bottom of the groove has a third radius that is less than the second radius,
• wherein the groove has a first groove edge section, between the first back-panel support section and the bottom of the groove, having a first inclination, and a second groove edge section, between the second back-panel support section and the bottom of the groove, having a second inclination,
• a depth of the groove, from the second back-panel support section to the bottom of the groove, being less than or equal to 1.5 times a thickness of the packaging material.

A counter-pressure roller for applying pressure on a longitudinal sealing of a web of packaging material, wherein the counter-pressure roller comprises,

• a first back-panel support section having a first radius and a second back-panel support section having a second radius, for supporting a first and a second back-panel of the web, respectively,
• wherein the first radius is greater than the second radius,
• a groove between the first and second back-panel support sections, for holding a longitudinal overlap section formed by a first and second edge section of the first and second back-panels, respectively,
• wherein the first edge section is arranged to be placed outside the second edge section such that the first edge section is facing a bottom of the groove,
• wherein the bottom of the groove has a third radius that is less than the second radius,
• wherein the groove has a first groove edge section, between the first back-panel support section and the bottom of the groove, having a first inclination, and a second groove edge section, between the second back-panel support section and the bottom of the groove, having a second inclination,
• the bottom of the groove being placed closer to the second than to the first back-panel support section.

A method for forming a longitudinal sealing of a web of packaging material, the method comprising:

• receiving the web of packaging material, the web of packaging material comprising first and second back panels having respective first and second edge sections,
• providing a longitudinal sealing strip along one of the edge sections of the web of packaging material,
• forming a tube of the web of packaging material,
• applying heat to the first and the second edge sections of the web of packaging material,
• forming a longitudinal overlap section between the first and the second edge sections of the web of packaging material,
• feeding the web to a pressure roller arrangement comprising:
• a roller pair for applying pressure on a longitudinal sealing strip section,
• wherein the roller pair comprises,
• a pressure roller, and
• a counter-pressure roller, arranged opposite to the pressure roller, for applying pressure on the longitudinal sealing of the web of packaging material, wherein the counter-pressure roller comprises,
• a first back-panel support section having a first radius and a second back-panel support section having a second radius, for supporting the first and the second back-panels of the web, respectively,
• wherein the first radius is greater than the second radius,
• a groove placed between the first and second back-panel support sections, for holding the longitudinal overlap section,
• wherein the first edge section is arranged to be placed outside the second edge section such that the first edge section is facing a bottom of the groove,
• wherein the bottom of the groove has a third radius that is less than the second radius,
• wherein the groove has a first groove edge section, between the first back-panel support section and the bottom of the groove, having a first inclination, and a second groove edge section, between the second back-panel support section and the bottom of the groove, having a second inclination, the first inclination being less than the second inclination,
• applying pressure, using the pressure roller arrangement, along the longitudinal sealing such that the first and second edge sections of the web of packaging material, and the longitudinal sealing strip are sealed together.