3 Fundamentals of press design

Bending
W
W
t t
W
Wma
s
Fig. 4.8.28 Straightening roller geometry
Example:
Sheet steel St 37 (material number 1.0037) with a thickness of 2 mm has to be
straightened. The straightening roller pitch of the straightening machine is tw =
22 mm, the roller diameter Rw = 20 mm. The maximum feed value is calculated as
2 2
zwmax = 220 ⋅ + 2– ( 220 ⋅ + 2) – 22= 62 . mm
Roller straightening machines
Generally speaking, roller straightening machines for straightening sheet
metal comprise an upper and a lower row of straightening rollers with
the same diameter. The two rows are generally arranged horizontally. The
rollers in the top row are generally arranged precisely above the gaps
between the rollers of the bottom row.
To allow modification of the rolling gap, the upper rollers must be
adjustable in height. The type of adjustment characterizes the straightening
machine type. While in one case each upper roller can be separately
height adjustable, in the other type of machine all the upper
rollers are grouped together in a block to form an assembly, and are fed
towards the lower rollers by a tilting motion of the block.
The thickness range, the yield strength and the modulus of elasticity
of the coil stock to be processed determine the diameter and pitch of
the straightening rollers. In the case of materials with particularly sensitive
surfaces, intermediate rollers embedded between the straighten-
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
387