Measuring and testing – Dynamometers – Responsive to multiple loads or load components
Reexamination Certificate
1998-11-30
2001-04-10
Noori, Max (Department: 2855)
Measuring and testing
Dynamometers
Responsive to multiple loads or load components
Reexamination Certificate
active
06212960
ABSTRACT:
The present invention relates to apparatus for measuring the flatness of a strip in movement, particularly of a metal strip in a production line, comprising:
a means for putting the strip under tension in order to apply a longitudinal tension thereto and to pull the strip onto a winding roller.
a measuring roller around which the strip is wound, this roller being equipped with sensors providing signals for determining the local internal tension of the strip.
The flatness of a strip or of a plate, within the meaning of the present invention, is the degree of equilibrium of the internal stresses of the strip or of the plate. In other words, the greater the imbalance of the internal stresses of a product is, the less flat the product will be and vice versa.
In many fields and, in particular, in the manufacture of metal products intended especially for electronics or similar applications, parts for electrical or electronic equipment, connectors, supports for cable components, or water heaters, a metal strip is manufactured by rolling and straightening operations, etc. This strip is then split into smaller strips from which the parts are made.
The rolling performed before these various operations by a surface pressure exerted by rolls reduces the thickness of the strip and makes it proportionally longer.
In practice, owing to bending or expansion of the rolls, the reduction in thickness of the strip is not strictly uniform either in the direction of the width or in the direction of the length. This is translated into local internal compression and tensile stresses. These stresses may have no apparent effect on the strip produced if they remain small enough to avoid local buckling (“blisters”, “crinkling”) of the sheet metal.
However, when this strip is split into smaller strips serving for the manufacture of the above-mentioned products, this equilibrium is broken and the smaller strips are deformed in a disorderly manner under the effect of the internal stresses.
The specifications, particularly the geometrical specifications, set for the products to be cut out are becoming ever stricter. In order to conform to the deflection tolerances, to facilitate the shearing operation, and to prevent burrs after the shearing of the strip, the strip must be free of any internal tension at the input to the splitter.
Installations or apparatus exist for detecting such faults in the strip by measurement of the local internal stresses. However, this known apparatus is extremely complex and expensive.
It is in fact composed of a rigid rotary measuring roller onto which the strip the flatness of which is to be measured or determined is wound. This roller is equipped with pressure sensors incorporated in its outer surface. These pressure sensors, which are fixed to the measuring roller, rotate therewith. It is therefore necessary to transmit the signals by sliding contacts, which is a difficult technical problem requiring very complicated means given the low level of the signals provided by the pressure sensors.
The object of the present invention is to remedy these problems and to create simple, robust apparatus which can provide accurate results, particularly discrete measurements spatially associated with the different portions of the strip with very fine resolution, in order to bring about correction operations upstream, and an installation with a low maintenance cost.
For this purpose, the invention relates to apparatus of the type defined above, characterized in that:
the measuring roller comprises independent peripheral regions deformable by compression,
the sensors are fixed to an associated with the deformable peripheral regions of the roller in order to detect the deformation thereof under the effect of the strip and to provide signals in dependence on the deformation.
a utilization circuit receiving the signals of the sensors in order to derive data and control signals therefrom.
According to a further particularly advantageous characteristic:
each deformable peripheral region of the measuring roller is formed by a ring,
the rings being juxtaposed, independent of one another, and bearing on two reference cylinders,
at least one sensor is associated with each ring in order to detect the deformation thereof under the effect of the strip.
the rings are advantageously fixed for rotation with one another.
The mounting of two facing sensors per ring, measuring the diametral flattening (and not merely the radial flattening) of the corresponding ring, greatly simplifies the numerical analysis of the measurements and increases their accuracy by freeing them from any additional correction for the yielding of the support rollers (“reference cylinders”) which is variable a priori in dependence on the winding pressure.
According to another advantageous characteristic, the rings are identical.
The apparatus according to the invention is of quite simple construction, particularly in the case of a measuring roller formed by juxtaposed rings. It is easily incorporated in a production line for metallurgical processing at the output of rolling mills or straightening machines. The detection of the parameters connected with the flatness, that is, the deformation of the measuring roller (or of the rings of which the measuring roller is composed) is performed by distance sensors which are fixed. This eliminates any difficulties in the transmission of the signals.
The width of the deformable peripheral regions or of the rings of which the measuring roller is composed is selected in dependence on the desired fineness of resolution.
The strip is thus theoretically broken down into smaller strips each applied to a ring of the measuring roller. If this smaller strip has a large tensile stress, this is translated into a compression force acting on and flattening the ring. The flattening is detected by the sensor which thus supplies a signal depending on the internal stress prevailing at the locations corresponding to this smaller strip.
Continuous monitoring of the profile of internal stresses in the strip measured by the flatness-measuring roller at the output of the finishing mill or of the straightening machine permits optimal regulation of all of the operating gear of these machines; the camber and bracing of the rolling rolls, the swing and curvature of the straightening cassettes.
The highly accurate production of the rings corresponds to a set of normal machining operations in order for the two faces of each ring to be perfectly perpendicular to their axis of rotation.
The same care and the same accuracy must be applied to the production of the support rollers which must be not only well balanced but also perfectly parallel.
Finally, the precision of the production of the rings and, in particular, the flatness of their faces and the perpendicularity of these faces to their axis, reduces friction between the rings to a minimum, that is to say, a contrario, that each of the rings can be deformed on the support rollers independently of the others.
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Bourgain Eric
Durand-Texte Gerard
Le Conte Pierre
Noori Max
Seidel Gonda Lavorgna & Monaco, PC
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