T. Sendzimir, Inc. offers two shapemeter designs: the first, patented in 1994, utilizes a fixed (non-rotating) shaft that spans the width of the strip and is supported in stationary support blocks. A separate bearing is mounted upon this shaft at each measuring zone, and on the outside of this bearing a plain or urethane-covered steel ring is mounted, covering the full width of the zone.
On the inside of each bearing, a fixed transducer is mounted within the shaft to measure the radial force on the bearing. The output signal from each transducer can be directly wired to a computer or other display device, usually through an axial hole passing through the shaft and provided for this purpose. The transducers are loaded for the full 360° rotation of the roll.
This shapemeter is available in two versions: version 1 for cases where the unit can operate at a fixed wrap angle, and version 2 where the unit must replace an existing billy roll and so is designed to operate at a variable wrap angle with only minor change in sensitivity as the wrap angle varies.
Our newer low-cost shapemeter has been in service for several years. This extremely compact invention uses a very simple design to measure the tension of the strip across its width during rolling and was originally developed for the narrower strip marketplace (30" and less).
By measuring the tension in multiple zones across the strip width, Sendzimir's Shapemeter displays the actual shape of the strip, which is otherwise impossible to see when rolling strip under tension. The systems comprise extremely compact, self-contained assemblies mounted inboard of the deflector rolls. The simplicity of the design has resulted in T. Sendzimir, Inc. being able to offer the Shapemeter at a highly competitive price.
The Shapemeter functions by measuring tension distribution across the width of the strip. This is achieved by passing the strip, under tension, over the Shapemeter sensor roll at a fixed wrap angle. The radial force thus generated is measured by load cells mounted beneath the roll, each cell sensing the load on a 1" (25mm) or 1.375" (35mm) band of the strip (the measuring zone). Differences between forces on the various measuring zones are displayed on a color monitor. Before displaying, the differences are converted by a computer to tension stress differences, taking into account the known width and thickness of the strip. Tension stress distribution relates directly to flatness error (I units).
In the case of reversing mills, the Shapemeter rolls are mounted on the left and right sides of the mill, so flatness readings are available when rolling in either direction.
To keep the cost reasonable and to avoid complications caused by slip rings, etc., each sensor is a stationary load cell. The sensing roll is a segmented design divided into zones. Each zone is supported by a pair of support rollers, this pair of rollers being mounted on top of the stationary load cell. By this means, an independent measure of the tension in the strip passing over each segment is obtained. In addition, a number of features virtually eliminate crosstalk between measuring zones.
All components of the Shapemeter are very small, thus enabling the units to be fitted into very restricted areas and keeping the weight, the inertia, and the cost to a minimum. The load cells are wired directly to the computer used for generating the display. The use of standard commercial computers and input boards also ensures that the greatest possible performance is achieved at minimum cost.
The Shapemeter assemblies are mounted on a retractable frame, which enables quick retraction in the case of emergency and minimizes exposure of the devices to damage. The units incorporate heavy guards for additional protection.
T. Sendzimir, Inc. also supplies Sendzimir Shapemeter Systems for other applications.
Readings from the Shapemeter, which are generated at a rate of about 10 scans per second, are displayed on a color monitor at the operator's station. Each red column refers to a specific measuring zone.
The examples here show how the Shapemeter can show flatness defects that are entirely invisible to the naked eye during rolling.
In the top view, the strip edges are loose (normal practice) and there is a tight zone in the center of the strip.
In the bottom view, in addition to the loose edges, there is a loose band about two-third across the strip that would appear as a slight buckle after tension is removed. This band could be caused by a blocked coolant spray nozzle or a defective work roll profile, for example.