Reference Manual

17−2
Figure 17-2.
Drawing is from TAPPI’s Making Pulp and
Paper Series and is used with permission.
Figure 17-3. Multitube Tapered Manifold
Drawing is from TAPPI’s Making Pulp and
Paper Series and is used with permission.
Headbox
From the manifold, stock enters the headbox
through a series of tubes. The headbox has
several purposes. It needs to eliminate the
turbulence coming out of the tubes from the
manifold, it has to break up the fiber flocs, and it
must ensure the amount of stock coming out of
the slice is uniform all the way across the width of
the machine. Below are the major types of
headboxes:
D Rectifier Roll (Air-padded) — This type of
headbox has a number of hollow rolls within the
stock stream, inside the headbox. The rolls are
perforated with approximately one inch diameter
holes throughout the surface of the roll (figure
Figure 17-4. Rectifier Roll (or Air-Padded) Headbox
Drawing is from TAPPI’s Making Pulp and
Paper Series and is used with permission.
17-4). Typically, there is one roll at the entrance of
the box, a second roll in the main pond area, and
a third roll near the discharge of the headbox. The
stock fills the box almost to the top of the rectifier
roll so a cushion of air remains above the stock.
This cushion of air helps to lessen pressure
variations, thus lessening changes in the basis
weight of the paper being produced. The rolls
rotate slowly to help eliminate any large-scale