Bel-2000 Gen II - Theory

The Bel-2000 analyzes the digital wave-shape generated by the impulse hammer when it is tapped against a roll of wound material. The force of the impact is captured by a transducer in the Bel-2000 hammer. The force and the duration of the impact varies with the hardness of the material.

When a roll of material tapped, the force signal from the hammer rises from zero to a maximum peak value and then returns to zero. The shape of that wave is used to calculate the hardness value, called RHO.

The Graph shows examples of 2 different wave shapes and the hardness they indicate.

The Bel-2000 hammer produces an analog signal that is digitized by the system microprocessor using an analog-to-digital converter (ADC), The digitized wave shape is analyzed by the system to calculate a RHO value.

Special note: Users of both the Mill Assist Bel-2000 and it's predecessor, the Mill Assist RHO-METER, may see small differences in the RHO values produced by these 2 units, when measuring the same material. To avoid confusion, users should note the type of instrument when recording RHO values.

Roll Profiles

• By measuring RHO at many places across the face of a wound roll, a PROFILE of the roll hardness can be obtained. The Profile shows the uniformity of roll hardness across the width of the roll. Ideally, a roll should show the same RHO value across it's entire width.
• As data is collected by the Bel-2000, It shows a graph of the roll profile. The graph makes it easy to see if the profile is uniform. When the graph is flat, the profile is uniform. Profiles that are not uniform (flat) can lead to many later problems with the roll - wrinkles, stretching, or breakage. Some examples of these problems are shown in the following figures.