Cross-machine direction stiffened dividers for a papermaking headbox

A papermaking machine headbox comprising:

• (a) an inlet manifold;
• (b) a step diffuser tube bank;
• (c) spaced apart upper and lower headbox walls;
• (d) the upper wall having an upper lip, and the lower wall having a lower lip;
• (e) the space between the upper and lower lips forming a slice opening;
• (f) a flexible divider;
• (g) the divider having upstream, middle, and downstream sections, the downstream section making up no more than 30% of the total length of the divider;
• (h) the upstream end of the flexible divider being adjacent to the step diffuser tube bank;
• and,
• (i) cross-machine direction reinforcements located only on the downstream section of the divider;
• and,
• (j) the cross-machine stiffness of the downstream section being greater than or equal to the cross-machine stiffness of the middle and upstream sections;
• and, the cross-machine stiffness of the downstream section increasing from the point adjacent the middle section to the downstream end of the downstream end section.

A flexible extended divider in a papermaking headbox comprising:

• an upstream end and a downstream end;
• an upstream end section corresponding to the upstream end, a middle section located adjacent and between the upstream end section and a downstream end section corresponding to the downstream end;
• the thickness of the divider decreasing from the upstream end to the downstream end in a gradual and uniform taper;
• the cross-machine stiffness of the downstream end section being greater than or equal to the cross-machine stiffness of the middle and upstream end sections;
• and, the cross-machine stiffness of the downstream end section increasing from the point adjacent the middle section to the downstream end.

A flexible extended divider in a papermaking headbox comprising:

• an upstream end and a downstream end;
• an upstream end section corresponding to the upstream end, a middle section located adjacent and between the upstream end section and a downstream end section corresponding to the downstream end;
• the thickness of the divider decreasing from the upstream end section to the downstream end section;
• the downstream end section having reinforcements so as to increase the cross-machine stiffness of the downstream end;
• the cross-machine stiffness of the downstream end section being greater than or equal to the cross-machine stiffness of the middle section and upstream end section;
• and, the cross-machine stiffness of the downstream end section increasing from the point adjacent the middle section to the downstream end of the downstream end section;
• whereby the machine direction stiffness of the down stream end is not significantly effected by the reinforcements while the cross-machine direction stiffness of the downstream end is increased.

A multilayered headbox comprising:

• (a) an upper wall having an upper lip and a lower wall having a lower lip;
• (b) a space between the upper and lower lips forming a slice opening for aqueous suspensions of papermaking fibers to exit the headbox;
• (c) a cross-machine reinforced extended divider having an upstream end, a middle and a reinforced downstream end sections, the upstream end being positioned within the headbox, the downstream end extending beyond the slice opening from about 5 to 15 times the height of that opening;
• (d) the cross-machine direction stiffness of the downstream end of the divider is greater than the machine direction stiffness of the downstream end of the divider;
• and,
• (e) the cross-machine stiffness of the downstream end section being greater than or equal to the cross-machine stiffness of the middle and upstream end sections;
• and, the cross-machine stiffness of the downstream end section increasing from the point adjacent the middle section to the downstream end.

A multilayered headbox comprising:

• (a) an upper wall having an upper lip and a lower wall having a lower lip;
• (b) a space between the upper and lower lips forming a slice opening for aqueous suspensions of papermaking fibers to exit the headbox;
• (c) a cross-machine reinforced extended divider having an upstream end, a middle and a reinforced downstream end sections, the upstream end being positioned within the headbox, the downstream end extending beyond the slice opening from about 5 to 15 times the height of that opening;
• (d) in which the reinforced flexible extended divider is reinforced with graphite fibers in only the down stream end;
• and,
• (e) the cross-machine stiffness of the downstream end section being greater than or equal to the cross-machine stiffness of the middle and upstream end sections;
• and, the cross-machine stiffness of the downstream end section increasing from the point adjacent the middle section to the downstream end.

A multilayered headbox comprising:

• (a) an upper wall having an upper lip and a lower wall having a lower lip;
• (b) space between the upper and lower lips forming a slice opening for aqueous suspensions of papermaking fibers to exit the headbox;
• (c) upstream end and a downstream end, the upstream end being positioned within the headbox, the downstream end extending beyond the slice opening from about 5 to 15 times the height of that opening;
• and,
• (d) a first and a second cross-machine direction reinforced flexible dividers the second cross-machine direction reinforced flexible divider having an upstream end and a downstream end, the downstream end extending beyond the slice opening about 5 to 15 times the height of the slice opening;
• both reinforced flexible dividers having an increasing cross-machine stiffness from the upstream end to the down stream end and a decreasing machine direction stiffness from the upstream end to the down stream end.