WO2003083471A1 - Method and apparatus for defining the tearing strength of paper material or the like - Google Patents

Method and apparatus for defining the tearing strength of paper material or the like Download PDF

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Publication number
WO2003083471A1
WO2003083471A1 PCT/FI2002/000210 FI0200210W WO03083471A1 WO 2003083471 A1 WO2003083471 A1 WO 2003083471A1 FI 0200210 W FI0200210 W FI 0200210W WO 03083471 A1 WO03083471 A1 WO 03083471A1
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WO
WIPO (PCT)
Prior art keywords
cylinders
tape
sample
strips
separating
Prior art date
Application number
PCT/FI2002/000210
Other languages
French (fr)
Inventor
Risto-Antti Paju
Original Assignee
Metso Field Systems Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metso Field Systems Oy filed Critical Metso Field Systems Oy
Priority to PCT/FI2002/000210 priority Critical patent/WO2003083471A1/en
Priority to AU2002240977A priority patent/AU2002240977A1/en
Publication of WO2003083471A1 publication Critical patent/WO2003083471A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/34—Paper
    • G01N33/346—Paper sheets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0017—Tensile
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/006—Crack, flaws, fracture or rupture
    • G01N2203/0067—Fracture or rupture
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0091—Peeling or tearing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/0278—Thin specimens
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/0278—Thin specimens
    • G01N2203/0282—Two dimensional, e.g. tapes, webs, sheets, strips, disks or membranes

Definitions

  • the invention relates to a method for determining the internal bond strength of paper material or the like, in which two strips of one-sided tape are continuously taped to both sides of a sample, after which the tape and the sample are guided in between two separating cylinders, set one against the other, in which the tape strips are separated from one another using re-directing cylinders, which function as pulling elements, located a distance away from the separating cylinders, while at the same time, the force needed to separate the tape is measured and used to calculate the internal bond strength of the sample.
  • the invention also relates to an apparatus for applying a method which is in accordance with claim 1, which comprises a frame, to which is mounted at least two separating cylinders, set one against the other, and re-directing cylinders, placed a distance away from the separating cylinders, for guiding the tape strips, which have been separated from the sample, apart from one another and for measuring the strain required in separating them.
  • the method most frequently used for determining the internal bond strength of paper is the so-called Scott Internal Bond Test method. It is as follows: A sample piece of paper of a specified size is mounted with double-sided tape between block anvils and the strength and durability of the connection is assured by a specified pressure. One block anvil is fixed to a base, while the other one is knocked off by the force of a pendulum, whereupon the sample splits. The force exerted in the splitting of the sample is calculated from the beginning and ending height level of the swing of the pendulum.
  • the method is laborious and time-consuming, since precision and tidiness are necessary when mounting the sample, to ensure the attachment of the sample and that splitting occurs on the entire surface area. Furthermore, after measuring, the tape must be removed from the block anvils and the surfaces must be cleaned of glue residue.
  • Another previously known method for determining internal bond strength is the use of two strips of one-sided strips of tape, which are first taped onto both sides of a sample. Then the tape strips are pulled apart from one another, and as they are being pulled apart, the force applied to the tape strips is measured and used to calculate the internal bond strength of the sample.
  • the method per se is functional. However, it is based on a one-test-per-cycle principle, in the same way as the method described in the previous paragraph. Thus, each test requires that many separate tasks and time-consuming pre and post-test preparation phases, such as manual application of the tape and removal of the used tape, cleaning up, etc., be carried out for each individual sample.
  • the object of the invention is to provide a method for measuring the internal bond strength of paper material or the like, whereby the previously mentioned disadvantages will be avoided.
  • the object of the invention is to provide a method, by which internal bond strength can be measured continuously, reliably and advantageously.
  • the object of the invention is to provide an apparatus for the application of the method, whereby the apparatus can be used to determine internal bond strength continuously and without separate preliminary preparation phases for each sample.
  • the object of the invention is accomplished by a method and an apparatus for determining the internal bond strength of paper material or the like, the characteristics of which are presented in the claims.
  • a characteristic of the method formed in accordance with the invention is that the strips of tape are guided to the re-directing cylinders, such that the non-adhesive surfaces of the tape strips serve as the contact surface between the tape and the redirecting cylinders, and such that, after separated, the tape strips and the sample are guided in between cylinders, which are set one against the other, and where the tape strips and the sample become taped together again.
  • internal bond strength can be measured continuously.
  • the separating process of the tape strips is symmetrical, the result of which is that the tape strips separate from one another in opposite directions, evenly, reliably and in a controlled way.
  • the internal bond strength can be determined with accuracy and reliability, without complicated and time-consuming processing phases for the measurements.
  • the mechanism necessary for the application of a method like this is easily made to be reliable, compact in size, simple in structure and advantageous in manufacturing costs.
  • the tape strips are moved by the re-directing cylinders primarily in a crosswise direction in relation to the separating cylinders before they are re-taped to one another.
  • sections of tape strip can easily be guided into the re-directing cylinders past the sections of tape strip which are being re-taped to one another.
  • the tape strips can be re-taped to one another either by guiding the tape strip sections which have been separated from one another once again between the separating cylinders, or by using separate re-taping cylinders.
  • re-directing cylinders of this kind can prevent the adhesive surface of the tape strips from having to touch the cylinder surfaces in any phase of the method, rather, they touch only the surfaces of the sample and the tape strips. This is a particularly advantageous feature from the point of view of reliability and accuracy of measurements, because when the adhesive sticks to the cylinders, it produces an opposing force which causes unpredictable tape movements and interferes significantly with the measuring of the force needed to separate the tape strips.
  • the tape strips are taped to the sample and/or to one another by being fed between taping cylinders which press the tape strips to one another and/or against the sample.
  • taping cylinders which press the tape strips to one another and/or against the sample.
  • the taping cylinders can also simultaneously function as separating cylinders.
  • a mechanism formed in accordance with the method can be made simpler and smaller in size than that of the application which makes use of separate taping cylinders, however, in this case, the adhesive on the tape strips does not have time to stick and dry, as previously mentioned.
  • the tape strips and the sample are guided back again in between the separating cylinders after being separated.
  • the same separating cylinders can be advantageously used for both separating the tape strips and for retaping the used tape strips. This cuts down on the number of components and cylinders for the mechanism, thus simplifying it.
  • the internal bond strength of a sample is determined by measuring the strain on at least one of the re-directing cylinders while the tape strips are being pulled apart.
  • the separating cylinders allow the separation of the tape strips occurs evenly and symmetrically, causing the direction of the tape going into and out of the redirecting cylinders to be constant and easily measured.
  • the internal bond strength can be determined quite reliably by measuring the force exerted on just one of the re-directing cylinders.
  • the measurement of the strain on a redirecting cylinder of this kind of apparatus can be carried out simply, for example, using a strain gauge or a telltale which can be attached to a mounting structure on the re-directing cylinder. Measurements taken in this way conveniently yield much measurement data, which can be used to accurately determine the force applied to the tape strips, even for relatively short sample pieces.
  • the strips of tape are pulled by a driving mechanism which is located after the separating cylinders.
  • a driving mechanism placed in this way is simple and the production costs are low.
  • the strips of tape and the sample are moved to a collection roll, located after the separating cylinders after being re-taped.
  • the used tape strips can be conveniently and advantageously collected onto one roll after they have been used.
  • an apparatus formed in accordance with the method can have fairly large tape rolls, whereupon they would not need to be changed often.
  • the adhesive surfaces of the used tape strips always remain against one another, which makes handling them later easier and cleaner.
  • a characteristic of an apparatus according to the method formed in accordance with the invention is that the re-directing cylinders are set at an angle in respect to the separating cylinders, to move the tape strips crosswise to the separating cylinders in order to restore their position against one another when they come back around.
  • the tape strips would be also on the re-directing cylinders in a way which is in accordance with a method formed in accordance with the invention, with their non-adhesive side against the outer surface of the cylinder, and in order to cause the tape strips to return to their original direction of movement after passing through redirecting cylinders, the direction of movement of the tape strips must first be reversed back to the direction of the tape rolls, and then from this direction again back to their original direction.
  • the direction of the tape strips changes on the re-directing cylinders after which (either on separating cylinders or on separate re- taping cylinders) it is 180° in total.
  • This kind of shift in the direction of movement of the tape strips will cause the tape strip, which is coming out of the re-directing cylinder, to collide with the tape strip, which is going into the re-directing cylinder, if the tape strips are not positioned in a crosswise direction in relation to the redirecting cylinders.
  • the tape strips can be positioned in a crosswise direction in relation to the separating cylinders most simply and most advantageously when done in the previously mentioned way, by turning/setting the re-directing cylinders at an appropriate angle in relation to the separating cylinders, such that the tape strip coming out of the re-directing cylinders are guided past the tape strip which is going into the re-directing cylinders.
  • a driving mechanism and a unit of pulling cylinders located after the separating cylinders and rotated by the driving mechanism, are mounted on the frame in order to move the tape strips and the sample.
  • the unit of pulling cylinders In order to obtain reliable and accurate measurements, it is important that the unit of pulling cylinders not slip and that the tape strips move steadily. After coming out of the separating cylinders, the non-adhesive (smooth) surfaces of the tape strips are against the moving cylinders.
  • the unit of pulling cylinders enables the tape strips to move reliably at a constant speed, and the structure of the unit of pulling cylinders allows for a great amount of contact area between the tape strips and the cylinders with a simple mechanism and with a small number of cylinders, thus preventing detrimental sliding of the tape strips.
  • a collection roll which is rotated by a driving mechanism and used for winding the used tape and the sample back onto a roll, is mounted to the frame after the unit of pulling cylinders.
  • a large amount of tape fits onto the collection roll, thus many measurements can be taken using a measuring mechanism equipped with a collection roll like this one before the collection roll gets full/has to be changed.
  • a unit of tape-unwinding cylinders moved by a driving mechanism, is mounted to the frame in order to unwind the roll of tape.
  • Some of the force necessary to move the tape strips is obtained from the force necessary to unwind the rolls of tape.
  • this force also affects the measurements of the separating force obtained from the re-directing cylinders.
  • the force necessary to unwind the tape roll must be as small and/or as steady as possible.
  • the mechanism comprises a unit of tape-unwinding cylinders which are moved by a driving mechanism, the force from the act of unwinding the tape can be made fairly small and/or steady relative to the separating force.
  • this kind of unit of tape- unwinding cylinders improves the accuracy of measurements obtained using the measuring mechanism.
  • FIG. 1 illustrates a basic drawing of a certain mechanism for measuring internal bond strength according to the method formed in accordance with the invention
  • Figure 2 illustrates a basic drawing of a certain second mechanism for measuring internal bond strength according to the method formed in accordance with the invention
  • Figure 3 illustrates a basic drawing of a certain third mechanism for measuring internal bond strength according to the method formed in accordance with the invention
  • Figure 4 illustrates a unit of tape-unwinding cylinders belonging to a certain mechanism for measuring internal bond strength according to the invention.
  • the mechanism for measuring internal bond strength constructed according to Figure 1 comprises a frame 12, tape rolls la and lb fit with bearings to the frame, taping cylinders 2a and 2b, separating cylinders 3a and 3b, re-directing cylinders 4a and 4b, a unit of pulling cylinders, comprising three pulling cylinders 5, 6 and 7, set against each other and one on top of the other, rotated by a driving mechanism 8, and a collection roll 9, which functions as a collecting apparatus and is rotated by a spooler (not shown in Figure 1) which is equipped with a driving mechanism.
  • a mechanism for measuring internal bond strength formed in accordance with Figure 1 comprises gauges, known as such, for measuring the strain on the redirecting cylinders, as well as an apparatus for data collection, known as such, whereby the measurements from the gauges are collected and in which the measurements are transformed into values of internal bond strength.
  • the measuring gauges and the data collection apparatus are not shown in Figure 1.
  • the frame 12 of a mechanism for measuring internal bond strength constructed according to Figure 1 is a plate structure, to which the other components of the mechanism are mounted as shown in Figure 1.
  • the frame also comprises the necessary fastening elements and structures, known as such, for mounting the taping, separating, re-directing and pulling cylinders and the ball bearings for the axles of the tape rolls and the collection apparatus to the frame.
  • Two tape rolls la and lb which comprise part of the measuring mechanism, placed vertically at a distance from one another as shown in Figure 1, are detachably mounted to the frame 12, in a way known as such, to freely rotating axles with bearings (not shown in Figure 1).
  • the locations for the axles and tape rolls have been chosen, such that a sample can be fed in between the taping cylinders 2a and 2b, situated a distance in front of the tape rolls, in a suitable way.
  • the bearings of the axles can evenly slow down the rotating motion of the tape roll in an appropriate way.
  • the taping cylinders 2a and 2b are mounted with bearings to the frame 12 a distance away from the tape rolls, against one another and set one on top of the other.
  • the surface of the taping cylinders is an elastic rubbery material, so that the tape strips and the sample moving between them are pressed against each other with the appropriate force.
  • the taping cylinders in this application do not have a driving mechanism, instead, they move with the tape strips and the sample.
  • the separating cylinders 3a and 3b located a distance in front of the taping cylinders 2a and 2b in the direction of movement of the tape strips, are mounted with bearings to the frame 12. They are placed, as are the taping cylinders, against one another and one on top of the other. Above and below them, the re-directing cylinders 4a and 4b are mounted with bearings at an angle.
  • the angles of the redirecting cylinders are determined such that the tape strips 11a and l ib, which go around them, are guided a distance to the side on the re-directing cylinders that is at least equal to the width of the tape strips, whereupon the tape strips can be returned to the position in between the separating cylinders beside the tape which is passing through the separating cylinders for the first time, as shown in Figure 1.
  • the re-directing cylinders 4a and 4b are mounted with bearings to the frame 12, which comprise measuring gauges, by which the strain concentrated on the redirecting cylinders can be measured.
  • the gauges that measure the strain are strain- gauge transducers mounted to the fastening structures of the bearings.
  • the points with bearings of the re-directing cylinders also include a deflection angle control, allowing the re-directing cylinders to be turned to an appropriate position to guide the tape strips in between the separating cylinders beside the incoming tape strips.
  • the deflection angle control is realized in the form of bearing housing fastening mechanisms, which are moved by screwing apparatuses.
  • the unit of pulling cylinders which is comprised of pulling cylinders 5, 6 and 7, which have been fastened one on top of the other with bearings to the frame.
  • the tape strips pass from a nip of the pulling cylinders, as shown in Figure 1, in an s-form, so that there is a relatively large amount of contact area between the pulling cylinders and the tape strips.
  • a driving mechanism 8 is mounted underneath the lowest pulling cylinder 7 and is connected to cylinder 7 by a cogwheel in the way shown in Figure 1.
  • All of the pulling cylinders are coated with the same elastic rubbery material as the taping and separating cylinders and they are fastened to the frame by bearings with adequate firmness, one against the other, so that pulling cylinders 5 and 6 do not necessarily need a gear or other separate transmission apparatus in order for them to turn.
  • a collection apparatus which comprises a winding apparatus, to which a tape collection roll 9 is mounted.
  • the spooler is not shown in Figure 1, but it comprises an axle/cylinder, which is rotated by a driving mechanism, onto which, a detachable collection roll can be detachably fastened after use.
  • the collection roll is a cylindrical component made of cardboard, around which the used tape is wound, moving the tape strips forward.
  • a sample 10 used in an apparatus for measuring internal bond strength, formed according to Figure 1, must be a strip with a width equal to that of the tape (or, for example, the roll).
  • the measuring apparatus is prepared for use in the following way: First, the tape rolls la and lb are mounted on their axles. Then, an adequate amount of the tape 11a and l ib is pulled out and the tape strip ends are taped together, taking care that they are precisely matched together. Next, the tape strip ends which have been taped together are passed together through taping cylinders 2a and 2b, and further through separating cylinders 3a and 3b.
  • the tape strip ends are pulled apart from one another and the tape strips are passed around the redirecting cylinders 4a and 4b (the non-adhesive side of the tape against the cylinder) and back to the separating cylinders or to the separate re-taping cylinders (3c, 3d), which are beside the tape strips which have already gone through, such that the ends of the tape strips are against one another (according to Figure 1).
  • the ends of the tape strips are taped back together in the same way as was done before they were passed through the taping cylinders. After this, the tape strips, which are taped together, are guided to the pulling cylinder unit, through which they pass in the way shown in Figure 1, in an s-form.
  • the ends of the tape strips which are taped together, are fastened to a collection roll 9, which is mounted on the axle of the spooler.
  • the tape strips can be moved slightly forward, using the driving mechanism of the measuring apparatus, in order to test the functionality of the assembly of the tape, to see that the tape strips move in the appropriate way on the apparatus. If necessary (for example if the tape strips ride off to the side), the course of the tape strips can be controlled by adjusting the deflection angle of the redirecting cylinders.
  • Measurements taken with a measuring apparatus are carried out as follows: The end of the sample 10 is placed in the opening of the nip, which is formed by the taping cylinders 2a and 2b. The measuring apparatus is activated. The sample is guided between the tape strips 11a and l ib and between the taping cylinders. At this point, it is necessary to make sure that the sample is as precisely in line with the tape strips as possible as it is fed in between the taping cylinders.
  • the measuring apparatus can include a suitable steering apparatus for feeding the sample, or, for example, a sample roll, around which the sample is wound and which guides the sample between the taping cylinders so that it is in line with the tape in the previously mentioned way.
  • the sample When the sample is passed through the mechanism, it is first taped between the strips of tape in the taping cylinders 2a and 2b, and then it is torn in two in the separating cylinders 3a and 3b, and finally, it is guided into the re-taping cylinders 3c and 3d, re-taped, and from there it is guided through the pulling cylinders 5, 6 and 7 to the collection cylinder 9.
  • the data collection apparatus gathers the results of the measurements, taken by the gauges on the re-directing cylinders 4a and 4b, of the force needed to pull the tape strips apart and to tear the sample, which is in between the tape strips, and then stores them in its memory. Then the data collection apparatus converts the measured results into the internal bond strength values of the sample.
  • the internal bond strength values can be written out, for example, on the data collection apparatus monitor screen, or printed out on a printer connected to it.
  • the measuring apparatus is always ready to take a new measurement as long as there is enough tape on the tape rolls and/or the collection roll is not too full.
  • tape rolls and/or collection roll can be replaced with new ones, whereupon it is necessary to carry out the preliminary preparations for the measuring apparatus described in the previous paragraph.
  • the structure of the different components, and the material used in them, of the apparatus that measures internal bond strength and is constructed according to the method in accordance with the invention may vary.
  • the frame the main purpose of which is to connect the tape rolls and units of cylinders together, in the way shown in Figure 1, or in some corresponding way, can be made in different ways, for example, as a casing from sheet metal, onto which the other components are mounted.
  • the frame can also be formed as an open-bar structure, or a casing with transparent walls, so that the course of the tape and the sample are easier to monitor. If necessary, the frame can comprise different accessory components for ease of use, such as adjustable support legs, or the like.
  • any kind of roll-tape known as such and suited for the purpose, may be used as tape, the width of which may be selected based on the width of the samples, for example.
  • the simplest way to mount the tape rolls is merely with a sufficiently tight adaptor in between the tape roll and the axle.
  • the axle may comprise different fastening units, such as, for example, detachable interlocking components mounted on both sides of the tape roll.
  • the tape-unwinding cylinders, taping cylinders, separating cylinders, pulling cylinders and re-directing cylinders can be made from different materials, and their diameters, width, placement and number can vary in different applications of the invention.
  • the outer surface of the cylinders can be coated with some kind of rubbery material, or other very durable material, or the cylinders can, for example, be produced entirely from such material.
  • the cylinder bearings are slide bearings. However, roller bearings or groove-ball bearings, for example, may also be appropriate to use in larger apparatuses intended for stronger paper.
  • Figures 2 and 3 illustrate examples of two other alternative applications.
  • the tape strips in the application in Figure 2 are re-taped to one another in separate re- taping cylinders 3c and 3d, instead of in the separating cylinders.
  • separate taping cylinders 2a and 2b have been removed and separating cylinders 3a and 3b function additionally as taping cylinders.
  • the apparatus constructed according to the application in Figure 4 comprises a special unit of tape- unwinding cylinders, whereby the appropriate tension of the tape strips can be ensured during measuring.
  • the unit of tape-unwinding cylinders is comprised of two tape-unwinding cylinders with bearings 13a and 13b, which move linearly in relation to the frame, and an apparatus which moves these cylinders (not illustrated in Figure 4).
  • the unit of tape-unwinding cylinders 13a and 13b comprising tape-unwinding cylinders formed in accordance with Figure 4, move away from the other cylinders (for example, backwards in relation to the frame of the mechanism) using their own driving mechanism, which is part of the unit of tape-unwinding cylinders. This means that the strips of tape unwind from the roll.
  • the movement of the tape-unwinding cylinders stops and the movement mechanism is released, such that the tape-unwinding cylinders 13a and 13b can move along with the strips of tape back towards the other units of cylinders.
  • the cylinders are opposing the course of movement of the tape strips through the mechanism with the appropriate constant force, so that the tape strips stay taut the whole time, but not so taut that any more tape unwinds from the roll before the entire sample has gone through the separating cylinders.
  • the number, placement and diameters of the pulling cylinders in the unit of pulling cylinders which moves the strips of tape can vary in different applications of the invention.
  • the grip of the unit of pulling cylinders can be improved.
  • One alternative is to simply use a collection roll as a pulling mechanism. In this case, at least two matters must be noted: first, the rotation speed of the collection roll must be automatically controlled, such that the speed of movement of the tape strips and the sample remain constant, despite the increased diameter of the collection roll; second, the tape strips must initially be sufficiently well attached to the collection roll, so that sliding cannot occur during the first rotations.
  • the collection apparatus which collects the used tape can be realized in several different ways in different applications of the invention.
  • the collection apparatus may comprise, for example, an immovable collection roll rotated by a spooler, onto which the used tape, and the sample adhered to it, are reeled.
  • the collection apparatus is emptied by removing the tape and the samples by unwinding the collection roll, or by some other suitable method.
  • the collection apparatus can also be realized in many other ways. It can, for example, merely be comprised of an empty box or frame component, into which the used tape is conveyed, pushed by the pulling cylinders, or other type of mechanism which can move the tape strips.
  • the gauges of the re-directing cylinders of the internal bond strength measuring apparatus can be any kind of gauge, which is suitable for measuring the strain, which is concentrated on the re-directing cylinders, such as, for example, different force gauges or telltales.
  • the measurement data gathered by the gauges can be processed using many different kinds data collection apparatuses. Collection of data and processing of measured results can be easily realized, for example, using a computer with software installed for processing the measurement card and measured results.
  • the measuring mechanism can be integrated into the factory's process data system and local area network, whereupon the measured results can be used directly in the factory's process and quality management, among other things.

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Abstract

The invention relates to a method for determining the internal bond strength of paper material or the like, in which two strips of one-sided tape (lla, llb) can continuously be taped to both sides of a sample (10), after which the tape and the sample are guided in between two separating cylinders (3a, 3b), set one against the other, in which the tape strips are separated from one another using re-directing cylinders (4a, 4b), which function as pulling elements, located some distance away from the separating cylinders, while at the same time, the force needed to separate the tape is measured and used to calculate the sample's internal bond strength. The invention also relates to an apparatus for applying a method, which is in accordance with Claim 1, which comprises a frame (12), to which is mounted at least two separating cylinders (3a, 3b), set one against the other, and re-directing cylinders (4a, 4b), placed some distance away from the separating cylinders, for guiding the tape strips (11 a, 11 b), which have been separated from the sample (10), apart from one another and for measuring the strain required in separating them. A characteristic of a method formed in accordance with the invention is that the tape strips (11 a, 11b) are guided to the re-directing cylinders (4a, 4b), such that the non­adhesive surfaces of the tape strips serve as the contact surface between the tape strips and the re-directing cylinders, and such that, after separated, the tape strips (lla, llb) and the sample (10) are guided in between cylinders (3a, 3b, 3c, 3d), which are set one against the other, and in between which the tape strips and the sample become taped together again. A characteristic of an apparatus constructed in accordance with the invention is that the re-directing cylinders (4a, 4b) are set at an angle in respect to the separating cylinders (3a, 3b), to move the tape strips primarily in a crosswise direction in relation to the separating cylinders (3a, 3b), in order to return them once again against one another.

Description

Method and apparatus for defining the tearing strength of paper material or the like
The invention relates to a method for determining the internal bond strength of paper material or the like, in which two strips of one-sided tape are continuously taped to both sides of a sample, after which the tape and the sample are guided in between two separating cylinders, set one against the other, in which the tape strips are separated from one another using re-directing cylinders, which function as pulling elements, located a distance away from the separating cylinders, while at the same time, the force needed to separate the tape is measured and used to calculate the internal bond strength of the sample. The invention also relates to an apparatus for applying a method which is in accordance with claim 1, which comprises a frame, to which is mounted at least two separating cylinders, set one against the other, and re-directing cylinders, placed a distance away from the separating cylinders, for guiding the tape strips, which have been separated from the sample, apart from one another and for measuring the strain required in separating them.
The method most frequently used for determining the internal bond strength of paper is the so-called Scott Internal Bond Test method. It is as follows: A sample piece of paper of a specified size is mounted with double-sided tape between block anvils and the strength and durability of the connection is assured by a specified pressure. One block anvil is fixed to a base, while the other one is knocked off by the force of a pendulum, whereupon the sample splits. The force exerted in the splitting of the sample is calculated from the beginning and ending height level of the swing of the pendulum. The method is laborious and time-consuming, since precision and tidiness are necessary when mounting the sample, to ensure the attachment of the sample and that splitting occurs on the entire surface area. Furthermore, after measuring, the tape must be removed from the block anvils and the surfaces must be cleaned of glue residue.
Internal bond strength is of great importance in printing and coating machines, because the ink on the surface of the paper tends to stick to the cylinders, thus, paper that has greater internal bond strength can withstand greater speeds. Based on this, a determining method, which clearly deviates from the former, has been developed, in which paper, which is wet with ink, is guided through rotating cylinders at a regulated speed. The minimal speed at which the sample splits yields the durability index. With the method, measurements which are easily usable in printing and coating processes can be obtained. One defect of the method is that when using the method, ink and the samples which are wet with ink must be processed, so that using this method is messy and unpleasant. Furthermore, the ink affects the internal bond strength of the paper, whereupon the measurements obtained with the method deviate from the true internal bond strength values (with dry paper) obtained by the previously described method.
Another previously known method for determining internal bond strength is the use of two strips of one-sided strips of tape, which are first taped onto both sides of a sample. Then the tape strips are pulled apart from one another, and as they are being pulled apart, the force applied to the tape strips is measured and used to calculate the internal bond strength of the sample. The method per se is functional. However, it is based on a one-test-per-cycle principle, in the same way as the method described in the previous paragraph. Thus, each test requires that many separate tasks and time-consuming pre and post-test preparation phases, such as manual application of the tape and removal of the used tape, cleaning up, etc., be carried out for each individual sample.
The object of the invention is to provide a method for measuring the internal bond strength of paper material or the like, whereby the previously mentioned disadvantages will be avoided. In particular, the object of the invention is to provide a method, by which internal bond strength can be measured continuously, reliably and advantageously. Furthermore, the object of the invention is to provide an apparatus for the application of the method, whereby the apparatus can be used to determine internal bond strength continuously and without separate preliminary preparation phases for each sample.
The object of the invention is accomplished by a method and an apparatus for determining the internal bond strength of paper material or the like, the characteristics of which are presented in the claims.
A characteristic of the method formed in accordance with the invention is that the strips of tape are guided to the re-directing cylinders, such that the non-adhesive surfaces of the tape strips serve as the contact surface between the tape and the redirecting cylinders, and such that, after separated, the tape strips and the sample are guided in between cylinders, which are set one against the other, and where the tape strips and the sample become taped together again. With such a method, internal bond strength can be measured continuously. Furthermore, in this way, the separating process of the tape strips is symmetrical, the result of which is that the tape strips separate from one another in opposite directions, evenly, reliably and in a controlled way. As a result of this, the internal bond strength can be determined with accuracy and reliability, without complicated and time-consuming processing phases for the measurements. Moreover, the mechanism necessary for the application of a method like this is easily made to be reliable, compact in size, simple in structure and advantageous in manufacturing costs.
In an advantageous application of a method formed according to the invention, the tape strips are moved by the re-directing cylinders primarily in a crosswise direction in relation to the separating cylinders before they are re-taped to one another. Thus, sections of tape strip can easily be guided into the re-directing cylinders past the sections of tape strip which are being re-taped to one another. The tape strips can be re-taped to one another either by guiding the tape strip sections which have been separated from one another once again between the separating cylinders, or by using separate re-taping cylinders. Using re-directing cylinders of this kind, likewise, can prevent the adhesive surface of the tape strips from having to touch the cylinder surfaces in any phase of the method, rather, they touch only the surfaces of the sample and the tape strips. This is a particularly advantageous feature from the point of view of reliability and accuracy of measurements, because when the adhesive sticks to the cylinders, it produces an opposing force which causes unpredictable tape movements and interferes significantly with the measuring of the force needed to separate the tape strips.
In a second advantageous application of the invention, the tape strips are taped to the sample and/or to one another by being fed between taping cylinders which press the tape strips to one another and/or against the sample. When measuring internal bond strength using the tape strips, the tape strips must adhere so firmly, that when the tape strips are pulled apart, they will not come off of the sample, rather, the sample should tear or split evenly along its horizontal plane, somewhere between the top and bottom surfaces of the sample. Using the taping cylinders, the tape strips taken from the tape rolls can be taped to both sides of the sample reliably and uniformly, such that there are no badly taped places/areas between the tape strips and the sample. Furthermore, if the taping cylinders are separate from the separating cylinders, the adhesive on the tape has a moment to stick and dry before being torn off. This further improves the evenness and effectiveness with which the tape strips adhere to the sample. In one particular implementation of this application, the taping cylinders can also simultaneously function as separating cylinders. In this case, a mechanism formed in accordance with the method can be made simpler and smaller in size than that of the application which makes use of separate taping cylinders, however, in this case, the adhesive on the tape strips does not have time to stick and dry, as previously mentioned.
In a third advantageous application of a method formed according to the invention the tape strips and the sample are guided back again in between the separating cylinders after being separated. In this way, the same separating cylinders can be advantageously used for both separating the tape strips and for retaping the used tape strips. This cuts down on the number of components and cylinders for the mechanism, thus simplifying it.
In a fourth advantageous application of a method formed according to the invention, the internal bond strength of a sample is determined by measuring the strain on at least one of the re-directing cylinders while the tape strips are being pulled apart. The separating cylinders allow the separation of the tape strips occurs evenly and symmetrically, causing the direction of the tape going into and out of the redirecting cylinders to be constant and easily measured. Thus, the internal bond strength can be determined quite reliably by measuring the force exerted on just one of the re-directing cylinders. Furthermore, the measurement of the strain on a redirecting cylinder of this kind of apparatus can be carried out simply, for example, using a strain gauge or a telltale which can be attached to a mounting structure on the re-directing cylinder. Measurements taken in this way conveniently yield much measurement data, which can be used to accurately determine the force applied to the tape strips, even for relatively short sample pieces.
In a fifth advantageous application of a method formed according to the invention, the strips of tape are pulled by a driving mechanism which is located after the separating cylinders. In this way, the speed at which the tape strips are pulled can easily be kept steady, whereupon variations in measurements caused by an inconsistent pulling speed will remain small. Furthermore, a driving mechanism placed in this way is simple and the production costs are low.
In a sixth advantageous application of a method formed according to the invention the strips of tape and the sample are moved to a collection roll, located after the separating cylinders after being re-taped. In this way, the used tape strips can be conveniently and advantageously collected onto one roll after they have been used. Furthermore, as a result of this, an apparatus formed in accordance with the method can have fairly large tape rolls, whereupon they would not need to be changed often. In addition, the adhesive surfaces of the used tape strips always remain against one another, which makes handling them later easier and cleaner. A characteristic of an apparatus according to the method formed in accordance with the invention is that the re-directing cylinders are set at an angle in respect to the separating cylinders, to move the tape strips crosswise to the separating cylinders in order to restore their position against one another when they come back around. In order that the tape strips would be also on the re-directing cylinders in a way which is in accordance with a method formed in accordance with the invention, with their non-adhesive side against the outer surface of the cylinder, and in order to cause the tape strips to return to their original direction of movement after passing through redirecting cylinders, the direction of movement of the tape strips must first be reversed back to the direction of the tape rolls, and then from this direction again back to their original direction. Thus, the direction of the tape strips changes on the re-directing cylinders after which (either on separating cylinders or on separate re- taping cylinders) it is 180° in total. This kind of shift in the direction of movement of the tape strips will cause the tape strip, which is coming out of the re-directing cylinder, to collide with the tape strip, which is going into the re-directing cylinder, if the tape strips are not positioned in a crosswise direction in relation to the redirecting cylinders. The tape strips can be positioned in a crosswise direction in relation to the separating cylinders most simply and most advantageously when done in the previously mentioned way, by turning/setting the re-directing cylinders at an appropriate angle in relation to the separating cylinders, such that the tape strip coming out of the re-directing cylinders are guided past the tape strip which is going into the re-directing cylinders.
In an advantageous application of an apparatus constructed in accordance with the invention, a driving mechanism and a unit of pulling cylinders, located after the separating cylinders and rotated by the driving mechanism, are mounted on the frame in order to move the tape strips and the sample. In order to obtain reliable and accurate measurements, it is important that the unit of pulling cylinders not slip and that the tape strips move steadily. After coming out of the separating cylinders, the non-adhesive (smooth) surfaces of the tape strips are against the moving cylinders. The unit of pulling cylinders enables the tape strips to move reliably at a constant speed, and the structure of the unit of pulling cylinders allows for a great amount of contact area between the tape strips and the cylinders with a simple mechanism and with a small number of cylinders, thus preventing detrimental sliding of the tape strips.
In a second advantageous application of an apparatus constructed in accordance with the invention, a collection roll, which is rotated by a driving mechanism and used for winding the used tape and the sample back onto a roll, is mounted to the frame after the unit of pulling cylinders. A large amount of tape fits onto the collection roll, thus many measurements can be taken using a measuring mechanism equipped with a collection roll like this one before the collection roll gets full/has to be changed.
In a third advantageous application of an apparatus constructed in accordance with the invention, a unit of tape-unwinding cylinders, moved by a driving mechanism, is mounted to the frame in order to unwind the roll of tape. Some of the force necessary to move the tape strips is obtained from the force necessary to unwind the rolls of tape. Thus, this force also affects the measurements of the separating force obtained from the re-directing cylinders. As a result of this, the force necessary to unwind the tape roll must be as small and/or as steady as possible. When the mechanism comprises a unit of tape-unwinding cylinders which are moved by a driving mechanism, the force from the act of unwinding the tape can be made fairly small and/or steady relative to the separating force. Thus, this kind of unit of tape- unwinding cylinders improves the accuracy of measurements obtained using the measuring mechanism.
Next, the invention will be described in more detail with reference to the accompanying drawings, in which Figure 1 illustrates a basic drawing of a certain mechanism for measuring internal bond strength according to the method formed in accordance with the invention,
Figure 2 illustrates a basic drawing of a certain second mechanism for measuring internal bond strength according to the method formed in accordance with the invention, Figure 3 illustrates a basic drawing of a certain third mechanism for measuring internal bond strength according to the method formed in accordance with the invention,
Figure 4 illustrates a unit of tape-unwinding cylinders belonging to a certain mechanism for measuring internal bond strength according to the invention.
The mechanism for measuring internal bond strength constructed according to Figure 1 comprises a frame 12, tape rolls la and lb fit with bearings to the frame, taping cylinders 2a and 2b, separating cylinders 3a and 3b, re-directing cylinders 4a and 4b, a unit of pulling cylinders, comprising three pulling cylinders 5, 6 and 7, set against each other and one on top of the other, rotated by a driving mechanism 8, and a collection roll 9, which functions as a collecting apparatus and is rotated by a spooler (not shown in Figure 1) which is equipped with a driving mechanism. In addition, a mechanism for measuring internal bond strength formed in accordance with Figure 1 comprises gauges, known as such, for measuring the strain on the redirecting cylinders, as well as an apparatus for data collection, known as such, whereby the measurements from the gauges are collected and in which the measurements are transformed into values of internal bond strength. The measuring gauges and the data collection apparatus are not shown in Figure 1.
The frame 12 of a mechanism for measuring internal bond strength constructed according to Figure 1 is a plate structure, to which the other components of the mechanism are mounted as shown in Figure 1. The frame also comprises the necessary fastening elements and structures, known as such, for mounting the taping, separating, re-directing and pulling cylinders and the ball bearings for the axles of the tape rolls and the collection apparatus to the frame.
Two tape rolls la and lb, which comprise part of the measuring mechanism, placed vertically at a distance from one another as shown in Figure 1, are detachably mounted to the frame 12, in a way known as such, to freely rotating axles with bearings (not shown in Figure 1). The locations for the axles and tape rolls have been chosen, such that a sample can be fed in between the taping cylinders 2a and 2b, situated a distance in front of the tape rolls, in a suitable way. In order to prevent the tape strips from getting mixed up with one another and with the sample, and in order to ensure that there is enough tension in the tape strips, the bearings of the axles can evenly slow down the rotating motion of the tape roll in an appropriate way.
The taping cylinders 2a and 2b are mounted with bearings to the frame 12 a distance away from the tape rolls, against one another and set one on top of the other. The surface of the taping cylinders is an elastic rubbery material, so that the tape strips and the sample moving between them are pressed against each other with the appropriate force. The taping cylinders in this application do not have a driving mechanism, instead, they move with the tape strips and the sample.
The separating cylinders 3a and 3b, located a distance in front of the taping cylinders 2a and 2b in the direction of movement of the tape strips, are mounted with bearings to the frame 12. They are placed, as are the taping cylinders, against one another and one on top of the other. Above and below them, the re-directing cylinders 4a and 4b are mounted with bearings at an angle. The angles of the redirecting cylinders are determined such that the tape strips 11a and l ib, which go around them, are guided a distance to the side on the re-directing cylinders that is at least equal to the width of the tape strips, whereupon the tape strips can be returned to the position in between the separating cylinders beside the tape which is passing through the separating cylinders for the first time, as shown in Figure 1.
The re-directing cylinders 4a and 4b are mounted with bearings to the frame 12, which comprise measuring gauges, by which the strain concentrated on the redirecting cylinders can be measured. The gauges that measure the strain are strain- gauge transducers mounted to the fastening structures of the bearings. The points with bearings of the re-directing cylinders also include a deflection angle control, allowing the re-directing cylinders to be turned to an appropriate position to guide the tape strips in between the separating cylinders beside the incoming tape strips. In the application in Figure 1, the deflection angle control is realized in the form of bearing housing fastening mechanisms, which are moved by screwing apparatuses.
Located after the separating and re-directing cylinders, in the line of direction of movement of the tape strips and mounted to the frame 12, is the unit of pulling cylinders, which is comprised of pulling cylinders 5, 6 and 7, which have been fastened one on top of the other with bearings to the frame. The tape strips pass from a nip of the pulling cylinders, as shown in Figure 1, in an s-form, so that there is a relatively large amount of contact area between the pulling cylinders and the tape strips. A driving mechanism 8 is mounted underneath the lowest pulling cylinder 7 and is connected to cylinder 7 by a cogwheel in the way shown in Figure 1. All of the pulling cylinders are coated with the same elastic rubbery material as the taping and separating cylinders and they are fastened to the frame by bearings with adequate firmness, one against the other, so that pulling cylinders 5 and 6 do not necessarily need a gear or other separate transmission apparatus in order for them to turn.
Next in line, going in the direction of movement of the tape strips, is a collection apparatus, which comprises a winding apparatus, to which a tape collection roll 9 is mounted. The spooler is not shown in Figure 1, but it comprises an axle/cylinder, which is rotated by a driving mechanism, onto which, a detachable collection roll can be detachably fastened after use. The collection roll is a cylindrical component made of cardboard, around which the used tape is wound, moving the tape strips forward.
A sample 10 used in an apparatus for measuring internal bond strength, formed according to Figure 1, must be a strip with a width equal to that of the tape (or, for example, the roll). The measuring apparatus is prepared for use in the following way: First, the tape rolls la and lb are mounted on their axles. Then, an adequate amount of the tape 11a and l ib is pulled out and the tape strip ends are taped together, taking care that they are precisely matched together. Next, the tape strip ends which have been taped together are passed together through taping cylinders 2a and 2b, and further through separating cylinders 3a and 3b. Next, the tape strip ends are pulled apart from one another and the tape strips are passed around the redirecting cylinders 4a and 4b (the non-adhesive side of the tape against the cylinder) and back to the separating cylinders or to the separate re-taping cylinders (3c, 3d), which are beside the tape strips which have already gone through, such that the ends of the tape strips are against one another (according to Figure 1). Before passing through the separating cylinders, the ends of the tape strips are taped back together in the same way as was done before they were passed through the taping cylinders. After this, the tape strips, which are taped together, are guided to the pulling cylinder unit, through which they pass in the way shown in Figure 1, in an s-form. Finally, the ends of the tape strips, which are taped together, are fastened to a collection roll 9, which is mounted on the axle of the spooler. Before beginning to take measurements, the tape strips can be moved slightly forward, using the driving mechanism of the measuring apparatus, in order to test the functionality of the assembly of the tape, to see that the tape strips move in the appropriate way on the apparatus. If necessary (for example if the tape strips ride off to the side), the course of the tape strips can be controlled by adjusting the deflection angle of the redirecting cylinders.
Measurements taken with a measuring apparatus according to Figure 1 are carried out as follows: The end of the sample 10 is placed in the opening of the nip, which is formed by the taping cylinders 2a and 2b. The measuring apparatus is activated. The sample is guided between the tape strips 11a and l ib and between the taping cylinders. At this point, it is necessary to make sure that the sample is as precisely in line with the tape strips as possible as it is fed in between the taping cylinders. The measuring apparatus can include a suitable steering apparatus for feeding the sample, or, for example, a sample roll, around which the sample is wound and which guides the sample between the taping cylinders so that it is in line with the tape in the previously mentioned way. When the sample is passed through the mechanism, it is first taped between the strips of tape in the taping cylinders 2a and 2b, and then it is torn in two in the separating cylinders 3a and 3b, and finally, it is guided into the re-taping cylinders 3c and 3d, re-taped, and from there it is guided through the pulling cylinders 5, 6 and 7 to the collection cylinder 9. The data collection apparatus gathers the results of the measurements, taken by the gauges on the re-directing cylinders 4a and 4b, of the force needed to pull the tape strips apart and to tear the sample, which is in between the tape strips, and then stores them in its memory. Then the data collection apparatus converts the measured results into the internal bond strength values of the sample. After measurements are taken, the internal bond strength values can be written out, for example, on the data collection apparatus monitor screen, or printed out on a printer connected to it. To take the following measurements, it is only necessary to reset the data collection apparatus/save the previous measurements on a disc, or to take other such preliminary preparations. Otherwise, the measuring apparatus is always ready to take a new measurement as long as there is enough tape on the tape rolls and/or the collection roll is not too full. When tape runs out/when the collection roll is full, tape rolls and/or collection roll can be replaced with new ones, whereupon it is necessary to carry out the preliminary preparations for the measuring apparatus described in the previous paragraph.
The structure of the different components, and the material used in them, of the apparatus that measures internal bond strength and is constructed according to the method in accordance with the invention, may vary. The frame, the main purpose of which is to connect the tape rolls and units of cylinders together, in the way shown in Figure 1, or in some corresponding way, can be made in different ways, for example, as a casing from sheet metal, onto which the other components are mounted. The frame can also be formed as an open-bar structure, or a casing with transparent walls, so that the course of the tape and the sample are easier to monitor. If necessary, the frame can comprise different accessory components for ease of use, such as adjustable support legs, or the like.
Any kind of roll-tape, known as such and suited for the purpose, may be used as tape, the width of which may be selected based on the width of the samples, for example. The simplest way to mount the tape rolls is merely with a sufficiently tight adaptor in between the tape roll and the axle. Alternatively, the axle may comprise different fastening units, such as, for example, detachable interlocking components mounted on both sides of the tape roll.
The tape-unwinding cylinders, taping cylinders, separating cylinders, pulling cylinders and re-directing cylinders can be made from different materials, and their diameters, width, placement and number can vary in different applications of the invention. In order to attain the best possible grip on the outer surface of the cylinders, the outer surface of the cylinders can be coated with some kind of rubbery material, or other very durable material, or the cylinders can, for example, be produced entirely from such material. In the application in Figure 1, the cylinder bearings are slide bearings. However, roller bearings or groove-ball bearings, for example, may also be appropriate to use in larger apparatuses intended for stronger paper. Figures 2 and 3 illustrate examples of two other alternative applications. The tape strips in the application in Figure 2 are re-taped to one another in separate re- taping cylinders 3c and 3d, instead of in the separating cylinders. In the application in Figure 3, separate taping cylinders 2a and 2b have been removed and separating cylinders 3a and 3b function additionally as taping cylinders. The apparatus constructed according to the application in Figure 4 comprises a special unit of tape- unwinding cylinders, whereby the appropriate tension of the tape strips can be ensured during measuring. The unit of tape-unwinding cylinders is comprised of two tape-unwinding cylinders with bearings 13a and 13b, which move linearly in relation to the frame, and an apparatus which moves these cylinders (not illustrated in Figure 4). Using the unit of tape-unwinding cylinders according to Figure 4, a sufficient number of tape rolls can be unwinded in advance before the next internal bond strength measurements are taken. The purpose of this is to avoid the incidental influence that the fluctuation in force caused by unwinding the tape roll would have on the internal bond strength measurement. The unit of tape-unwinding cylinders 13a and 13b, comprising tape-unwinding cylinders formed in accordance with Figure 4, move away from the other cylinders (for example, backwards in relation to the frame of the mechanism) using their own driving mechanism, which is part of the unit of tape-unwinding cylinders. This means that the strips of tape unwind from the roll. When the sample is fed in between the strips of tape, and then into the separating cylinders, the movement of the tape-unwinding cylinders stops and the movement mechanism is released, such that the tape-unwinding cylinders 13a and 13b can move along with the strips of tape back towards the other units of cylinders. This means that the cylinders are opposing the course of movement of the tape strips through the mechanism with the appropriate constant force, so that the tape strips stay taut the whole time, but not so taut that any more tape unwinds from the roll before the entire sample has gone through the separating cylinders.
The number, placement and diameters of the pulling cylinders in the unit of pulling cylinders which moves the strips of tape can vary in different applications of the invention. In order to produce a unit of pulling cylinders which functions according to the principle in Figure 1, there must be at least two cylinders. By increasing the diameter of the pulling cylinders and by changing their placement, the grip of the unit of pulling cylinders can be improved. One alternative is to simply use a collection roll as a pulling mechanism. In this case, at least two matters must be noted: first, the rotation speed of the collection roll must be automatically controlled, such that the speed of movement of the tape strips and the sample remain constant, despite the increased diameter of the collection roll; second, the tape strips must initially be sufficiently well attached to the collection roll, so that sliding cannot occur during the first rotations.
The collection apparatus which collects the used tape can be realized in several different ways in different applications of the invention. In a second application similar to the one in Figure 1 , the collection apparatus may comprise, for example, an immovable collection roll rotated by a spooler, onto which the used tape, and the sample adhered to it, are reeled. In this case, the collection apparatus is emptied by removing the tape and the samples by unwinding the collection roll, or by some other suitable method. The collection apparatus can also be realized in many other ways. It can, for example, merely be comprised of an empty box or frame component, into which the used tape is conveyed, pushed by the pulling cylinders, or other type of mechanism which can move the tape strips.
The gauges of the re-directing cylinders of the internal bond strength measuring apparatus can be any kind of gauge, which is suitable for measuring the strain, which is concentrated on the re-directing cylinders, such as, for example, different force gauges or telltales. The measurement data gathered by the gauges can be processed using many different kinds data collection apparatuses. Collection of data and processing of measured results can be easily realized, for example, using a computer with software installed for processing the measurement card and measured results. In factory applications, the measuring mechanism can be integrated into the factory's process data system and local area network, whereupon the measured results can be used directly in the factory's process and quality management, among other things.
The invention is not limited to the advantageous applications presented. It can vary within the frames of the inventive idea established in the claims.

Claims

1. A method for determining the internal bond strength of paper material or the like, in which two strips of one-sided tape (11a, 1 lb) are continuously taped to both sides of a sample (10), after which the tape and the sample are guided in between two separating cylinders (3a, 3b), set one against the other, in which the tape strips are separated from one another using re-directing cylinders (4a, 4b), which function as pulling elements, located some distance away from the separating cylinders, while at the same time, the force needed to separate the tape is measured and used to calculate the sample's internal bond strength, c h a r a c t e r i z e d in that the strips of tape (11a, lib) are guided to the re-directing cylinders (4a, 4b), such that the non-adhesive surfaces of the tape strips serve as the contact surface between the tape and the re-directing cylinders, and such that, after separated, the tape strips (11a, lib) and the sample (10) are guided in between cylinders (3a, 3b; 3c, 3d), which are set one against the other, and in between which the tape strips and the sample become taped together again.
2. A method formed according to Claim 1, c h a r a c t e r i z e d in that the strips of tape (11a, lib) are moved by the re-directing cylinders primarily in a crosswise direction in relation to the separating cylinders before being re-taped to one another.
3. A method formed according to Claim 1 or 2, c h a r a c t e ri z e d in that the strips of tape (11a, 1 lb) are taped to the sample and/or to one another by being fed into taping cylinders (2a, 2b), which press against them, the sample and/or against one another.
4. A method formed according to any of Claims 1-3, c h a r a c t e r i z e d in that, after being separated, the tape strips (11a, 1 lb) and the sample (10) are brought back in between the separating cylinders (3a, 3b) again.
5. A method formed according to any of Claims 1-4, c h a r a c t e r i z e d in that the internal bond strength of the sample is determined by measuring the strain applied on at least one of the re-directing cylinders (4a) while the tape strips (11a, 1 lb) are being separated.
6. A method formed according to any of Claims 1-5, c h a r a c t e r i z e d in that the tape strips (11a, 1 lb) are pulled along by a driving mechanism (8) which is located after the separating cylinders (3 a, 3b).
7. A method formed according to any of Claims 1-6, c h a r a c t e r i z e d in that, after being retaped, the tape strips (11a, lib) and the sample (10) are moved to a collection roll (9), which is located after the separating cylinders (3a, 3b).
8. An apparatus for the application of a method formed according to Claim 1, which comprises a frame (12), to which is mounted at least two separating cylinders (3a, 3b), set one against the other, and re-directing cylinders (4a, 4b), placed some distance away from the separating cylinders, for guiding the tape strips (11a, lib), which have been separated from the sample (10), apart from one another and for measuring the strain required in separating them, c h a r a c t e r i z e d in that the re-directing cylinders (4a, 4b) are set at an angle in respect to the separating cylinders (3a, 3b), to move the tape strips (11a, lib) primarily in a crosswise direction in relation to the separating cylinders (3 a, 3b) in order to return them once again against one another.
9. An apparatus formed according to Claim 8, c h a r a c t e r i z e d in that a driving mechanism (8) and a unit of pulling cylinders (5, 6, 7), used for moving the tape strips (11a, lib), and the sample (10), located after the separating cylinders (3a, 3b) and rotated by the driving mechanism, are mounted to the frame (12).
10. An apparatus formed according to Claims 8 or 9, c h a r a c t e r i z e d in that a collection roll (9) for winding the tape strips (11a, lib) and the sample (10) back onto a roll, located after the unit of pulling cylinders (5, 6, 7) and rotated by the driving mechanism, is mounted to the frame (12).
11. An apparatus formed according to any of Claims 8-10, c h ar a c t e r iz e d in that a unit of tape-unwinding cylinders (13a, 13b) for unwinding the tape roll, moved by a driving mechanism, is mounted to the frame (12).
PCT/FI2002/000210 2002-03-15 2002-03-15 Method and apparatus for defining the tearing strength of paper material or the like WO2003083471A1 (en)

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Citations (3)

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Publication number Priority date Publication date Assignee Title
JPH04177146A (en) * 1990-11-13 1992-06-24 Kawasaki Steel Corp Continuous measuring device for t-shaped separation strength of laminated body
GB2336915A (en) * 1998-02-25 1999-11-03 Lorentzen & Wettre Ab Method and device for tensile strength testing paper or board
FI20002314A (en) * 2000-10-20 2002-04-21 Metso Field Systems Oy Method and apparatus for determining a bond strength of paper or equivalent material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04177146A (en) * 1990-11-13 1992-06-24 Kawasaki Steel Corp Continuous measuring device for t-shaped separation strength of laminated body
GB2336915A (en) * 1998-02-25 1999-11-03 Lorentzen & Wettre Ab Method and device for tensile strength testing paper or board
FI20002314A (en) * 2000-10-20 2002-04-21 Metso Field Systems Oy Method and apparatus for determining a bond strength of paper or equivalent material

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 16, no. 491 (P - 1434) 12 October 1992 (1992-10-12) *

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