Method for manufacturing two-sided laminated cardboard, as well as two-sided laminated cardboard manufactured by such a method

A method for manufacturing two-sided laminated cardboard, wherein on both sides of an intermediate cardboard layer a first outer layer and a second outer layer, respectively, are laminated, and wherein during said laminating:

• the intermediate layer is conveyed in a conveying direction through a laminating apparatus;
• the first outer layer is glued together with the upper side of the intermediate layer by means of a rotating upper roller under exertion of a first torque, and the second outer layer is glued together with the lower side of the intermediate layer by means of a rotating lower roller under exertion of a second torque;
• a measuring roller measures a measured band tension, in the conveying direction, of the intermediate layer being conveyed;
• for the purpose of a taut running of the intermediate layer, the intermediate layer being conveyed is kept at a pre-determined constant operational band tension in the conveying direction in dependence of said measured band tension and in dependence of said pre-determined constant operational band tension;
• and
• for the purpose of counteracting concaveness or convexness, in the conveying direction, of the two-sided laminated cardboard to be manufactured, band tensions of the first outer layer and the second outer layer are controlled;
• wherein in said controlling of said band tensions of the first outer layer and the second outer layer:
• a torque addition sum of the first torque and the second torque is controlled towards a pre-determined constant value of said torque addition sum, said pre-determined constant value being obtained from experience;
• and
• a torque difference between the first torque and the second torque is controlled towards a pre-determined value of said torque difference, said pre-determined value of said torque difference being obtained from experience, while maintaining said controlling of said torque addition sum towards said pre-determined constant value of said torque addition sum.