Method and apparatus for measuring and removing rotational variability from a nip pressure profile of a covered roll of a nip press

Patent metadata

Field	Value
Publication number	US-9540769-B2
Application number	US-201313792859-A
Country	US
Kind code	B2
Filing date	Mar 11, 2013
Priority date	Mar 11, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

Multiple groups of sensors are circumferentially spaced apart at each cross-directional position along a sensing roll of a nip press to measure and cancel or nearly cancel the effects of rotational variability which may be acting on the sensing roll. The strategically-placed sensors are designed to measure the pressure being placed against the web that is being advanced through the nip press. The average of the measurements of multiple sensors spaced circumferential apart provides a good cancellation of any rotational variability that might be found at a cross-directional position on the sensing roll. In this manner, a more true measurement of the nip pressure profile can be obtained and better adjustments made to reduce nip pressure profile variability. In addition, the nip variability profile may be used as a predictor of cover or bearing failures, resonant frequencies and other roll anomalies.

First claim

What is claimed:

1. A sensing roll for use in a nip press, comprising:
a substantially cylindrical member having an outer surface and adapted for rotational movement;
a roll cover circumferentially overlying the outer surface of the cylindrical member; and
a sensing system associated with the roll cover, comprising:
a first set of pressure-measuring sensors disposed in a particular configuration along the roll cover, each sensor of the first set being located at a particular cross-directional position on the roll cover; and
at least one additional set of pressure-measuring sensors disposed in a particular configuration along the roll cover, each sensor of the at least one additional second set being located at a particular cross-directional position on the roll cover,
wherein each sensor of the first set has a corresponding sensor in each of the at least one additional set of pressure-measuring sensors which is located at the same cross-directional position and spaced apart circumferentially in an evenly spaced manner, and
wherein the first set and the at least one additional set of pressure-measuring sensors comprises n sets of sensors, wherein each sensor of a one of the n sets has a corresponding sensor in the remaining n−1 sets, each corresponding sensor being located at the same cross sectional position and spaced 360°/n apart circumferentially from an adjacent sensor, each set of sensors forming a partial helix which extends about 360°/n around the sensing roll.

2. The sensing roll of claim 1 , comprising:
a transceiver attached to the cylindrical member and each of the sensors of the first set and the at least one additional set of pressure-measuring sensors for transmitting data signals from the sensors.

3. The sensing roll of claim 1 , wherein the pressure being applied to a sensor from the first set and the at least one additional set of pressure-measuring sensors is measured when these sensors enter the nip region of the nip press.

4. The sensing roll of claim 1 , wherein the at least one additional set of pressure-measuring sensors includes a second set and a third set, wherein each sensor of the first set has a corresponding sensor in the second and third sets which is located at the same cross sectional position and spaced 120° apart circumferentially.

5. The sensing roll of claim 1 , wherein the at least one additional set of pressure-measuring sensors includes a second set, wherein each sensor of the first set has a corresponding sensor in the second set which is located at the same cross sectional position and spaced 180° apart circumferentially.

6. The sensing roll of claim 1 , wherein the at least one additional set of pressure-measuring sensors includes a second set, a third set and a fourth set, wherein each sensor of the first set has a corresponding sensor in the second, third and fourth sets, each corresponding sensor being located at the same cross sectional position and spaced 90° apart circumferentially from an adjacent sensor.

7. The sensing roll of claim 1 , wherein the at least one additional set of pressure-measuring sensors includes a second set and a third set, wherein each sensor of the first set has a corresponding sensor in the second and third sets which is located at the same cross sectional position and spaced 120° apart circumferentially from an adjacent sensor, each set of sensors forming a partial helix which extends about 120° around the sensing roll.

8. The sensing roll of claim 1 , wherein the at least one additional set of pressure-measuring sensors includes a second set, wherein each sensor of the first set has a corresponding sensor in the second set which is located at the same cross sectional position and spaced 180° apart circumferentially, each set of sensors forming a partial helix which extends about 180° around the sensing roll.

9. The sensing roll of claim 1 , wherein the at least one additional set of pressure-measuring sensors includes a second set, a third set and a fourth set, wherein each sensor of the first set has a corresponding sensor in the second, third and fourth sets, each corresponding sensor being located at the same cross sectional position and spaced 90° apart circumferentially from an adjacent sensor, each set of sensors forming a partial helix which extends about 90° around the sensing roll.

10. A system for calculating and displaying a nip pressure profile for a nip press, comprising:
a sensing roll configured with a second roll in a nip press, the sensing roll and the second roll adapted to rotatingly press matter therebetween in a nip region,
the sensing roll comprising a plurality of cross-directional positions along its length,
the sensing roll comprising a plurality of sets of pressure-measuring sensors,
each sensor of the plurality of sets of sensors being disposed at a cross-directional position along the sensing roll,
each sensor configured to sense and measure pressure when the sensor enters the nip region of the nip press,
wherein the plurality of sets of pressure-measuring sensors comprises n sets of sensors, wherein each sensor of a one of the n sets has a corresponding sensor in each of the remaining n−1 sets, each corresponding sensor being located at the same cross-directional position and spaced 360°/n apart circumferentially from an adjacent sensor on the sensing roll, each set of sensors forming a partial helix which extends about 360°/n around the sensing roll,
each of the corresponding sensors of the plurality of sets providing a measurement of pressure at the respective cross-directional position which is averaged to supply an average measurement to processing equipment which calculates and displays a nip pressure profile for the nip press.

11. The system of claim 10 wherein a mathematical model is used to analyze the plurality of sensor readings at each cross-directional position to correct the nip pressure and calculate a nip rotational variability profile.

12. The system of claim 10 , further comprising a transceiver attached to the sensing roll and to each of the sensors of the plurality of sets for transmitting data signals from the sensors to a receiver unit.

13. The system of claim 12 , further comprising a processing unit for calculating the nip pressure distribution based on the average of the pressure measurements of each plurality of corresponding sensors of the plurality of sets of pressure-measuring sensors and displaying the nip pressure profile and a nip variability profile on a display unit.

14. The system of claim 10 , wherein the sensors of the each set are disposed in a certain pattern along the sensing roll.

15. A method for determining a nip pressure profile of a sensing roll of a nip press, comprising:
measuring a pressure exerted on a first sensor disposed at a particular cross-directional position on the sensing roll as the first sensor enters a nip region of the nip press;
measuring a respective pressure exerted on one or more additional sensors at the particular cross-directional position as they enter the nip region of the nip press,
each of the one or more additional sensors being located at the particular cross-directional position as the first sensor and spaced apart circumferentially from the first sensor; and
averaging the pressure measurement of the first sensor and the pressure measurement of the one or more additional sensors and determining a nip pressure profile,
wherein the first sensor, the one or more additional sensors and a plurality of further sensors, the further sensors being located at one or more other cross-directional positions along the sensing roll, comprise a

Assignees

• Int Paper Co

Inventors

• Figiel Kerry D

Classifications

• G01L5/0085

  Force sensors adapted for insertion between cooperating machine elements, e.g. for measuring the nip force between rollers · CPC title

• G01L5/00

  Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes · CPC title

• D21F3/06 Primary

  Means for regulating the pressure · CPC title

• D21G9/0036

  controlling the press or drying section · CPC title