ABB PFVL141V-1.25MN high-performance, rectangular roll force load cell

ABB  PFVL141V-1.25MN  high-performance, rectangular roll force load cell

The standard electrical equipment, including the load cells, constitutes a force measuring system

for nominal forces from 0.1 up to 1.6 MN.

QGPR 102/104 load cells constitute the force sensing units of the equipment. These are annular in

shape and are therefore suitable for installation on shafts where the axial forces are to be meas

ured, e.g., in rolling mills where they are installed between the millscrew nuts and the mill stand. In

this case, two load cells are used, one at each end of the rolls. Due to their location, the load cells

sense the main forces acting on the mill stand. See figure Load cell location in a mill stand.

Typical application area of QGPR 102/104 load cells are in pipe and tube mills particularly for instal

lation in (metallic) pipe extrusion and pipe straightening machines.

QGPR 102/104 load cells can also be used in flat rolling mills where the magnitude of the roll

forces is smaller than the force magnitudes that can be measured with other smallest availa

ble ABB Roll Force load cell types (i.e. when rolling hot or cold strips of smaller dimensions).

Due to the smaller installation height of QGPR 104 load cells, they are particularly suitable for

installations where the available space in the measuring direction of the load cell is too small for

using QGPR 102 load cells.

The signals from the load cells are processed in a control unit which also includes supply equip

ment for the load cells.

Four signals can be received from the equipment: one which is proportional to the total roll force,

i.e. the sum of the output signals from both loads, one which is proportional to the difference

between the forces acting on both load cells, and two which are proportional to the forces acting

on each individual load cell.

Measurement Principle

Pressductor® technology is based on the change of the magneto-elastic properties in the material

which the load cell core is made of. The load-dependent change of the magnetic properties of the

material is in this way used for inducing a voltage over a secondary measurement winding in the

load cell core.

The core of a load cell consists of a large number of turns. The turns are made of magneto-elastic

plate winded around an inner ring. One single measuring zone will consist of the four holes in a turn

plate with associated excitation and measurement signal windings.

The primary excitation winding is supplied with a special alternating current, creating a magnetic

f

lux in the adjacent steel. As long as no load is applied to the transducer element, no net magnetic

f

lux will occur around the secondary, signal, winding at the standard excitation. When the trans

ducer is exposed to a force in the measurement direction, the magneto-elastic change in the steel

will allow the magnetic flux to incorporate the secondary winding, inducing an AC voltage propor

tional to the applied force.

Load Cell Design

The load cell is built up around a laminated and epoxy-impregnated annular core of magneto-elas

tic steel. The core has several measuring zones where each steel laminate constitutes a force

transducer. Excitation and sensing windings penetrate through the entire core.

The core is provided with an outer and an inner steel ring and cover plates which protect the wind

ings.

The load-bearing surfaces are ground flat and parallel.

The load cell is provided with a permanently fixed cable, of which the free end is connected to an

enclosed matching device.

The QGPR 102/104 load cells utilise a unique method to compensate for the undesired tensile

forces which are generated when a cylindrical tube is subjected to load