EP1353008A1

EP1353008A1 - Method and apparatus for measuring the hardness or compactness of a clothing

Info

Publication number: EP1353008A1
Application number: EP02004783A
Authority: EP
Inventors: Raymond P. Shead
Original assignee: Voith Paper Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2002-03-01
Filing date: 2002-03-01
Publication date: 2003-10-15
Also published as: DE60216226D1; ATE346187T1; DE60216226T2

Abstract

A method for the manufacture or treatment of a material web, in particular of a paper or a card board web, while using a respective machine, in particular a paper machine, comprises the step of measuring the hardness and/or the compactness of at least one clothing, in particular of at least one felt, fabric, belt and/or the like, of said machine and apparatus suitable for performing the method.

Description

The invention relates to a method for the manufacture or treatment of a material web, in particular of a paper or cardboard web, while using a respective machine, in particular a paper machine. A method of this kind is described, for example, in US-A-5 611 893 and DE 691 29 788 T2.
The invention further relates to an apparatus for measuring the hardness and/or the compactness of at least one clothing, in particular of at least one felt, fabric, belt and/or the like, of a machine, in particular of a paper machine, for the manufacture or treatment of a material web, in particular of a paper or cardboard web.
Previous technologies for studying machine clothing involved online studies of moisture and/or permeability of machine clothing on order to determine their condition and performance. These studies were unable to provide information regarding the compaction (or density) of the machine clothing in cross direction or in machine direction over time. Apart from this, such measurements were unable to provide any indication of nip profile in situations where the clothing had passed through a pressing operation.
It is therefore an object of the present invention to provide an improved method and an improved apparatus of the kind initially mentioned with which the above-mentioned problems can be eliminated.
In accordance with the invention, this object is satisfied by the provision of a method for the manufacture or treatment of a material web, in particular of a paper or cardboard web, while using a respective machine, in particular a paper machine, comprising the step of measuring the hardness and/or the compactness of at least one clothing, in particular of at least one felt, fabric, belt and/or the like, of said machine.
In accordance with a preferred practical embodiment of the method of the invention, the hardness and/or the compactness of said machine clothing is continuously measured.
Preferably, the measurement of the hardness and/or the compactness of said machine clothing are carried out in machine direction and/or in cross machine direction.
In an expedient practical embodiment, an online measurement of the hardness and/or the compactness of said machine clothing is carried out.
The measurement of the hardness and/or the compactness of said machine clothing can, e.g., be carried out in at least one of the following sections of the machine: forming section, pressing section, drying section.
In accordance with another expedient practical embodiment of the method of the invention, a hardness and/or compactness control of said machine clothing is carried out.
In accordance with an expedient embodiment of the method of the invention, the measurement values obtained by said measurement of the hardness and/or the compactness of that machine clothing are used for optimizing the nip profile of at least one press section.
Alternatively or additionally the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing can be used for monitoring the life and/or condition of said machine clothing and as an indicator for their replacement.
Alternatively or additionally the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing can be used for optimizing the use of cleaning showers in order to minimise compaction and extend clothing life.
Alternatively or additionally the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing can be used for a high-frequency analysis of said machine clothing and/or associated rotating machine elements which affect clothing compaction.
In accordance with an expedient embodiment of the method of the invention, the measurement values obtained by that measurement of the hardness and/or the compactness of said machine clothing are used for controlling the condition of that machine clothing.
Such a control of the condition of said machine clothing can, for example, be carried out by controlling at least one sectionalized nip profiling and/or crown profiling equipment in order to optimize cross direction clothing compaction, nip impression and/or cross-machine web quality.
In accordance with another advantageous embodiment, the control of the condition of that machine clothing is carried out by controlling the average load pressure of a nip in order to optimize the pressing deficiency clothing compaction and extend the life of the machine clothing.
In accordance with the invention, the above-mentioned object is further satisfied by the provision of an apparatus for measuring the hardness and/or the compactness of at least one clothing, in particular of at least one felt, fabric, belt and/or the like, of a machine, in particular of a paper machine, for the manufacture or treatment of a material web, in particular of a paper or cardboard web, in particular for carrying out the method in accordance with any one of the preceding claims, said apparatus comprising at least one rotating wheel which contacts said machine clothing at its region of rotation around a counter roll, and at least one hardness and/or compactness sensor associated with said rotating wheel or with said counter roll.
The sensor is preferably embedded in said rotating wheel or counter roll, respectively. In the latter case, a plurality of sensors can be embedded in the counter roll in cross machine direction.
In accordance with a preferred practical embodiment of the apparatus of the invention, the rotating wheel is displaceable in cross machine direction.
The rotating wheel is preferably displaceable along a support rail.
In accordance with a preferred embodiment of the apparatus of the invention, the sensor is laid out for providing a signal which is proportional to the hardness and/or compaction of said machine clothing.
The sensor can, e.g., be a piezo crystal sensor.
In some cases it might be expedient to use a contacting caliper sensor.
The sensor is preferably positioned by means of a pressure controlled apparatus.
With the method and apparatus of the invention it is possible, e.g., to establish a continuous hardness and/or compaction measurement and control of, for example, a felt, fabric or belt on a paper machine.
The apparatus can provide continues machine direction and cross machine measurement of the hardness of paper machine clothing often referred to as felts, fabrics and belts. The apparatus may consist of a rotating wheel which contacts the paper machine clothing at its point of rotation around a turn roller or counter roll. The contacting roller may contain an embedded hardness sensor, or a plurality of sensors, which provide a signal which is proportional to the hardness or compaction of the paper machine clothing.
The apparatus may be able to provide the following information to the user:

trend information covering the life of the felt, fabric or belt in order to assess the condition of the machine clothing
profil information (cross machine measurement) of the felt, fabric or belt to indicate the uniformity of the clothing's compaction
profil information used to determine the condition of any nip the clothing has passed through
individual measurement for each felt or fabric in the manufacturing process, particularly for a press section where the performance and condition of each nip, felt/fabric can be optimized for paper quality and felt/fabric life
a historical database system providing archive data for use in comparative and absolute analysis of felts, fabrics, belts and rotating mechanical elements of the paper machine
high frequency machine direction analysis for the rotating machine clothing and the mechanical elements that may imprint their signature into the said clothing

The present invention provides direct measurement of clothing compaction and is able to be used as a continuous online analysis and troubleshooting tool in paper machine form sections, pressing operations and drying sections.
There may be a certain sensor size to wheel width ratio. A situation, where the wheel presses into the felt and as a consequence provides an inaccurate measurement, should be avoided.
The measurement signal could, for example, be transmitted down a scanner power track and processed in an off-sheet electronics box, i.e. a so called NIC (network intelligent controller).
It might be expedient to measure the average compactness over time from average data. This data could be plotted on an x-y-graph with a lower limit defined for the limit of felt compactness. Once the compactness of the felt reaches this limit then it will be described as reaching the end of its life.
Felts should have a certain compactness value to be successful in any given press position. Consequently, felt data could be archived such that the machine operators could access this information remotely and use it to provide customer support and competitive felt analysis.
As to the optimization of the felt life time and the press efficiency/quality, the CD (cross direction) felt compactness profile will most certainly reflect the press nip profile. The aim could be to have a flat compactness profile in order to deliver uniform dewatering across the web. The nip profiling system could be used to flatten the compactness profile. It could also be interesting to adjust the nip load and observe felt compactness and express moisture value. A control strategy could be realized which provides maximum dewatering with minimum press load while extending felt life. For controlling the sectionalised nip profiling and crown profiling means in order to optimize CD-clothing compaction and paper quality (e.g. moisture CD profile), closed loop control could be applied using the compactness profile with the nip controlled zones.
An exemplary embodiment of the apparatus of the invention is described in the following with reference to the drawing; there are shown in this:

Figure 1: a simplified schematic illustration of an apparatus for measuring the hardness and/or the compactness of machine clothing, which apparatus comprises a rotating wheel, and
Figure 2: a part illustration of the wheel of figure 1 in a larger scale.

Figure 1 shows an apparatus 10, in a schematic illustration, for measuring the hardness and/or the compactness of at least one clothing 12, in particular of at least one felt, fabric, belt and/or the like, of a machine, in particular of a paper machine, for the manufacture or treatment of a material web, in particular of a paper or card board web.
In the present exemplary embodiment, the apparatus 10 comprises a rotating wheel 14 which contacts said machine clothing 12 at its point of rotation around a counter or turn roll 16.
At least one embedded hardness and/or compactness detection sensor 18 is mounted in the rotating wheel 14. Such a hardness and/or compactness sensor could also be embedded in the counter roll 16. In the latter case, a plurality of sensors 18 could be embedded in the counter roll 16 in cross machine direction.
As indicated by arrow F, the rotating wheel 14 is displaceable in a cross machine direction. With the present embodiment, the rotating wheel 14 is displaceable along a support rail 20.
Figure 2 shows a part illustration of the rotating wheel 14 of figure 1 in a larger scale. In this figure 2, the radius profile for the rotating wheel 14 is indicated at 22.
The sensor 14 can be laid out for providing a signal which is proportional to the hardness and/or compaction of the machine clothing 12.
The sensor 14 can be, for example, a piezo crystal sensor. In some cases it is might be possible to use a contacting caliper sensor.
The sensor 14 can be positioned, for example, by means of at least one pressure cylinder, in particular at least one light air pressure cylinder.
The apparatus 10 provides continuous machine direction (MD) and cross machine (CD) measurement of the hardness of paper machine clothing 12 often referred to as felts, fabrics and belts. One or a plurality of hardness and/or compactness sensors 18 can be embedded in the rotating wheel 14 or the counter roll 16, respectively. The signal provided by a respective sensor 14 can be proportional to the hardness or compaction of the machine clothing 12.
The apparatus 10 can, for example, be used on machine measurement for the condition of clothing in terms of machine direction (MD) and cross direction (CD) compaction (and/or hardness). The information obtained by the at least one sensor 14 can be used to:

optimise the nip profiles of press sections
monitor the life and condition of machine clothing to use as an indicator for their replacement
optimise the use of cleaning showers in order to minimise compaction and extend felt/fabric life
high-frequency analysis of machine clothing and associated rotating machine elements which affect clothing compaction

The obtained sensor signals can further be used for controlling the condition of machine closing through:

control of sectionalized nip profiling and crown profiling equipment in order to optimize cross direction clothing compaction, nip impression and cross-machine paper quality
control the average load pressure of a nip in order to optimize the pressing efficiency felt/fabric compaction and extend the life of the machine clothing.

The apparatus 10 can generally be used as an analysis tool for the products to be manufactured.

Reference numeral list

10: apparatus for measuring the hardness and/or the compactness of at least one machine clothing
12: machine clothing
14: rotating wheel
16: counter roll, turn roll
18: hardness and/or compactness sensor
20: support rail
22: radius profile for the rotating wheel

Claims

A method for the manufacture or treatment of a material web, in particular of a paper or cardboard web, while using a respective machine, in particular a paper machine, comprising the step of measuring the hardness and/or the compactness of at least one clothing, in particular of at least one felt, fabric, belt and/or the like, of said machine.
The method in accordance with claim 1, characterized in that the hardness and/or the compactness of said machine clothing is continuously measured.
The method in accordance with claim 1 or claim 2, characterized in that the measurement of the hardness and/or the compactness of said machine clothing is carried out in machine direction and/or in cross machine direction.
The method in accordance with any one of the preceding claims, characterized in that an online measurement of the hardness and/or the compactness of said machine clothing is carried out.
The method in accordance with any one of the preceding claims, characterized in that the measurement of the hardness and/or the compactness of said machine clothing is carried out in at least one of the following sections of the machine: forming section, pressing section, drying section.
The method in accordance with any one of the preceding claims, characterized in that a hardness and/or compactness control of said machine clothing is carried out.
The method in accordance with any one of the preceding claims, characterized in that the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing are used for optimizing the nip profile of at least one press section.
The method in accordance with any one of the preceding claims, characterized in that the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing are used for monitoring the life and/or condition of said machine clothing and as an indicator for their replacement.
The method in accordance with any one of the preceding claims, characterized in that the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing are used for optimizing the use of cleaning showers in order to minimise compaction and extend clothing life.
The method in accordance with any one of the preceding claims, characterized in that the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing are used for a high-frequency analysis of said machine clothing and/or associated rotating machine elements which affect clothing compaction.
The method in accordance with any one of the preceding claims, characterized in that the measurement values obtained by said measurement of the hardness and/or the compactness of said machine clothing are used for controlling the condition of said machine clothing.
The method in accordance with claim 13, characterized in that said control of the condition of said machine clothing is carried out by controlling at least one sectionalized nip profiling and/or crown profiling equipment in order to optimize cross direction clothing compaction, nip impression and/or cross-machine web quality.
The method in accordance with claim 13, characterized in that said control of the condition of said machine clothing is carried out by controlling the average load pressure of a nip in order to optimise the pressing efficiency clothing compaction and extend the life of the machine clothing.
An apparatus (10) for measuring the hardness and/or the compactness of at least one clothing (12), in particular of at least one felt, fabric, belt and/or the like, of a machine, in particular of a paper machine, for the manufacture or treatment of a material web, in particular of a paper or cardboard web, in particular for carrying out the method in accordance with any one of the preceding claims, said apparatus comprising at least one rotating wheel (14) which contacts said machine clothing (12) at its region of rotation around a counter roll (16), and at least one hardness and/or compactness sensor (18) associated with said rotating wheel (14) or with said counter roll (16).
The apparatus in accordance with claim 14, characterized in that said sensor (18) is embedded in said rotating wheel (14) or counter roll (16), respectively.
The apparatus in accordance with claim 14 or claim 15, characterized in that a plurality of sensors (18) is embedded in the counter roll (16) in cross machine direction.
The apparatus in accordance with any one of the preceding claims, characterized in that said rotating wheel (14) is displaceable in cross machine direction.
The apparatus in accordance with any one of the preceding claims, characterized in that said rotating wheel is displaceable along a support rail (20).
The apparatus in accordance with any one of the preceding claims, characterized in that said sensor (14) is laid out for providing a signal which is proportional to the hardness and/or compaction of said machine clothing (12).
The apparatus in accordance with any one of the preceding claims, characterized in that said sensor (14) is a piezo crystal sensor.
The apparatus in accordance with any one of the preceding claims, characterized in that said sensor (14) is a contacting caliper sensor.
The apparatus in accordance with any one of the preceding claims, characterized in that said sensor (14) is positioned by means of a pressure controlled apparatus.