Rapid-Air STRAIGHTENER and PUSHBUTTON RAPID-ROLL: SC SERIES - Manual (Page 3)


Adjustable Platen
Stock Straighteners
vs.
Straighteners with
Traditional
Vertical Roll
Adjustment
concept: The concept behind a movable
platen containing the upper bank of rolls for
straighteners can be somewhat difficult to
grasp, but once the principles are understood
the superiority of this system becomes obvious.
To explain the differences between the adjust-
able platen system and one that uses traditional
single-point vertical roll adjustment, we are
describing both types of systems here.
Vertically adjustable upper rolls:
For centuries the bending of materials has been
done by variations of a three-roll arrangement as
illustrated in
Figure 1.
Bending occurs when one roll is forced into the
space between the other two rolls for downward
curvature of the material to remove coil set.
Pressroom straighteners add multiple three-roll
combinations in order to level the material in
small increments at each stage. This method can
provide acceptable results for some materials,
but is limited because correction of material
curvature is effective in only one direction as
illustrated in
Figure 2.
If the straightener is made to correct a clockwise
curvature, it is often impossible to correct a
counterclockwise curvature. The only available
adjustment is the variation of the degree of bend
at each station. This is true even for straighteners
that have banked upper rolls that pivot for
two-point adjustment.
six-way upper roll adjustment: After
manufacturing straighteners with vertically
adjustable rolls for many years, Rapid-Air
developed and patented the adjustable platen
type straightener as illustrated in
Figure 3.
This design mounts the upper rolls in a platen
which can be adjusted for degree of bend as
illustrated in Figure 4 and Figure 5
and for curvature direction as shown in
Figure 6 and Figure 7.
To more easily explain the concept, Figure 8
shows a three-roll combination with the upper
roll forward and
Figure 9 shows a three-roll
combination with the upper roll to the rear.
Notice that the sharpest bend occurs where two
rolls are in close proximity. When the upper
roll is forward, the curvature will be up and
when the forward roll is adjusted to the rear,
the bend will be down. The degree of bend can
be adjusted by a combination of vertical and
horizontal adjustments.
adVantages: The high degree of flexibility
afforded by the adjustable platen design provides
a predictable straightening method for a wide
variety of materials and takes a lot of the “Black
Magic” out of pressroom straightener setup.
The reduction in the flexing and distortion of
the strip of material and the reduction of the
straightening power required allows effective-
ness with heavy materials. Additionally, the ability
to place rolls in a proper close proximity allows
effective straightening with very thin materials.
roll diameter: The smaller the roll
diameter in a straightener the better it is able to
remove distortions in the strip of material, but
this factor is compromised by the requirement
of larger rolls in wider models of straighteners
in order to prevent deflection of the rolls
themselves. Rapid-Air straighteners are designed
to optimize all factors (including number
of rolls, diameter and position) within the
published material capacities and specifications
for each model.
swing-open top: Rapid-Air developed and
introduced the swing-open top for straighteners
in order to facilitate the cleaning of rolls and the
threading of a new strip of material through the
straightening rolls. For convenience and safety,
each top is counterbalanced and held in the
open position until it is clamped for operation.
Roll adjustment settings are maintained when the
top is closed and locked.
aVailability: All models of Rapid-Air straight-
eners are presently available with the adjustable
platen design with an expanded range of models
being introduced in the coming months.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8 Figure 9
Downward curvature of material
to remove coil set
Material curvature is effective
in only one direction
Forward/Back
Up/Down
Up/Down Slant
Less deflection
Deeper deflection
Light material distortion
Heavy material distortion
Rolls forward – curve up
Rolls back – curve down