| 摘要 |
The present invention relates to a method of constructing a multi-grade paperboard tube, in which method the strength of the multi-grade paperboard tube is adjusted on the basis of use conditions or simulating test conditions, in accordance with known or evaluated stress distribution. The strength of groups of structural paperboard plies used in the tube wall becomes stepwise higher, starting from the innermost ply, i.e., the bottom ply, towards the outer circumference of the tube wall, so that at the circumference corresponding to the center of the tube wall or in the immediate vicinity thereof, preferably slightly radially inwardly from the center of the tube wall, is disposed a group of structural plies composed of the strongest paperboard ply in use and that the strength of the groups of structural plies becomes stepwise lower, when moving from said circumference towards the outer circumference of the tube walls. Said strength gradation essentially follows the stress distribution known or evaluated on the basis of use conditions or simulating test conditions of the tube. |
