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
  • G01N3/20—Investigating strength properties of solid materials by application of mechanical stress by applying steady bending forces
• • 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
  • G01N2203/0023—Bending
• • 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
• • 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
  • G01N2203/04—Chucks, fixtures, jaws, holders or anvils
  • G01N2203/0405—Features allowing alignment between specimen and chucks
• • 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

Definitions

• the present invention relates to a method for positioning a sample of an item to be tested, which comprises a crease line or similar embossment. More specifically the invention relates to a method for positioning a sample of a packaging web. The invention also relates to a device for carrying out this method.
• a crease line in a packaging web can be regarded as a fold notch, along which a package, which is manufactured from the packaging web, is folded. Each package is thus provided with a number of crease lines, which can go in different directions on the packaging web.
• a primary function for the crease line is to define a line on a packaging web, where the packaging web is to be folded in order to form a complete package. In the absence of a crease line the packaging web will not be folded at the correct position and the packaging web material is likely to crack where it is folded.
• the crease line is important from an aesthetic point of view, i.e. a package that is to contain liquid, such as a milk carton, will not obtain the correct shape in the absence of crease lines.
• the package will appear as bulgy and shapeless if the corners of the package are not distinct.
• crease lines are thus introduced to weaken the flexural rigidity at selected portions of the packaging web material.
• a crease line is visible as a generally very weak embossment on the backside of a packaging web.
• a typical crease line can have a width of 1.8 mm and a height of only 0.03 mm.
• the crease line is further not especially well defined in its shape.
• the height of the crease line is further so small that irregularities of the packaging web make it difficult to perceive the location of a crease line .
• An important characteristic of the crease line is how much it reduces the amount of force needed to fold the packaging web in order to produce a complete package. If the crease line is to weak, the package will not obtain the correct shape when folded, i.e. the difference in flexural rigidity of the material, at a position where a crease line exists and at a position some distance from the crease line, is to small.
• the crease line is too strong, the tenacity of the packaging web material will be redu- ced. This may in some cases cause the folded package to break, with leakage as a consequence in the case of a liquid container, e.g. a milk carton. For that reason, it is very important to measure the strength of crease lines on a regular basis throughout the package manufac- turing process .
• the strength of a crease line is coupled to the amount of force needed to fold the packaging web. More specific, the strength of a crease line is defined through a so-called RCS-value (Remaining Crease Stiffness) , which " is commonly known throughout the packaging manufacturing industry.
• the RCS-value is measured according to the following procedure: 1) Measure the flexural resistance of a sample, arranged so that the bending takes place at a crease line. 2) Measure the flexural resistance of the same sample, arranged so that the bending takes place where no crease line is present. 3) Obtain the RCS-value, in percent, by dividing the result from 1) with the result from 2) and multiply by 100.
• the method described above which is commonly known and practiced throughout the packaging manufacturing industry, demands that the crease line sample is properly positioned in the test equipment. Further, as mentioned above, the width of the crease line is very small, and consequently the positioning of the sample in the test equipment is very cumbersome to perform.
• crease line Due to the nature of the crease line, the only way, up until know, to position the crease line is by performing a manual position- ing, i.e. the operator of the test equipment has to locate the crease line on the web sample and position the sample by hand. As can be understood, this action will claim a great amount of time.
• the solution to the problems mentioned above for positioning a packaging web sample or similar, which comprises a crease line or a similar embossment, in a test equipment for test of selected characteristics of the sample is a method, which includes the steps of: detecting a crease in the packaging web sample by means of a sensor arrangement, receiving a signal, from the sensor, in a control unit, which signal indicates a presence of the crease line, and providing a control signal from the control unit to a driving device based on the received signal from the sensor, and placing the packaging web sample in a test position by means of the driving device depending on a value of the control signal .
• the packaging web sample will be placed in a correct position in the test equipment almost independently of the sample size. Furthermore, the packaging web sample and the associated crease line will be placed in a correct position faster and more accurately than is possible with the present equipment. The result is that a large number of measurements may be performed over a short period of time. This is advantageous since the measurement result will vary from sample to sample even if identical web samples are tested and, as indicated above, there is a need to perform many measurements over a short period of time.
• Another object of the present invention is to pro- vide an apparatus for positioning a sample of an item, which comprises a crease line or a similar embossment, for test of selected characteristics of the item sample. This is accomplished by an apparatus comprising a sensor arrangement , and a driving device .
• FIG 1 is a schematic top view of an apparatus for positioning a web sample according to the present invention
• FIG 2 is a schematic side view of the apparatus of FIG 1;
• FIG 3 is a view of a web sample, comprising crease lines, in greater detail, and
• FIG 4 is a schematic block diagram illustrating the interconnection of the different parts of the apparatus according to the present invention.
• FIG 1 illustrates a preferred embodiment of the present invention i which web samples 1 of roughly the same sizes can be positioned in a correct position for measure of selected characteristics.
• the web samples 1 are cut out from a larger packaging web by use of a pair of scissors or a similar tool.
• the web samples 1 may be cut out by use of a punching device which will provide a set of almost fixed size web samples 1.
• a punching device will be very accurate in producing fixed size web samples 1
• the crease lines 2 residing on the web samples 1 will not be located in the same positions from sample to sample, i.e. the location of the crease lines depends upon how accu- rately the punch is positioned on the packaging web when performing the cut out.
• the angle of direction of the crease lines 2 across the web sample 1 may also vary from sample to sample.
• the crease lines 2 will stretch across the web sample 1 in a right angle relative to the long side of the packaging web, but this is however not always the case.
• An apparatus according to the present invention will place the web sample 1 in a correct measuring position even if the crease line 2 does not stretch across the web sample 1 in a right angle.
• a set of web samples 1 are placed in a retainer 3, where they may be kept in place and pressed against the base 4 by a spring clip 5 if needed, and a feeding device, such as a feeding belt or, as seen in FIG 1, a spring loaded feeding wheel 6.
• a small rotary device, such as an electric or pneumatic motor 7 receives control signals from a control unit 8, and controls the rotation of the feeding wheel 6 in accordance with these signals.
• the control unit 8, via the motor 7 and the feeding wheel 6, thereby controls the transportation of the web sample 1.
• the feeding wheel 6 is normally located in the center of the path that the web sample 1 will follow on its way towards a pair of positioning wheels 9a, b.
• the main purpose of the feeding wheel 6 is hence to transport the web sample 1 from the retainer 3 to the positioning wheels
• the feeding wheel 6 has sufficient friction and is pressed enough against the web sample 1 to be able to drag the web sample 1 out of the retainer 3.
• the feeding wheel 6 and the posi- tioning wheels 9a, b is for instance manufactured from a high friction material, such as rubber. Alternatively a toothed feeding wheel 6 and toothed positioning wheels 9a, b may be used.
• the positioning wheels 9a, b are located on opposite long side edges of the web sample 1.
• the positioning wheels 9a, b are coupled to a pair of motors 11a, b in the same way as the feeding wheel 6 and act as to feed/position the web sample 1 to a correct position. If the motors 11a and lib rotate at the same angular velocity, the web sample 1 will perform a rectilinear movement perpendicular to a folding edge 12 of the positioning apparatus 13, thereby making it possible to position the crease line 2 directly at the folding edge 12. On the other hand, if the motors 11a and lib do not rotate at the same angular velocity, or even not in the same direction, e.g.
• the web sample 1 will turn clockwise or counter-clockwise. Normally though, the turning movement of the web sample 1 will be performed by rotating one of the motors llab at a higher angular velocity than the other.
• a pair of crease line sensors 14a, b are placed immediately in front of the folding edge 12 and are connected to the control unit 8.
• the crease line sensors 14a, b are invented and developed by the applicant.
• the crease line sensors 14a, b are thoroughly described in the patent document 09525941. It is however possible to use other types of crease line detectors, e.g. based on mechanical or acoustic technologies, without departing from the scope of the invention.
• the crease line sensors 14a, b make it possible to accurately detect a crease line 2 without the need for the operator of the machine strain his eyes trying to locate the crease line 2.
• crease line sensors 14a, b spaced apart in front of the folding edge 12, looking at two different spots 15a, b of the web sample 1, it is possible to detect a crease line 2 as well as determine its angular displacement relative the folding edge 12.
• the crease line 2 is stretched across the web sample 1 at an angle ⁇ of e.g. 80 degrees relative to the long side of the web sample 1, as is shown in FIG 3.
• the positioning device will posi- tion a web sample 1 in a correct position as long as the crease line 2 stretches across a larger portion of the web sample 1, i.e. the angular displacement may be almost zero degrees.
• the maximum angular displacement relative to the long side of the web sample 1 is dependent upon the mechanical construction and placement of the positioning wheels 9a, b. In this case the following procedure will take place according to a preferred embodiment of the present invention.
• the web sample 1, residing in the retainer 3, is moved from its initial position by rotating the feeding wheel 6 and the positioning wheels 9a, b clockwise until a sensor, such as a mechanical or optical interrupt switch 16 confirms that the web sample 1 is in contact with the positioning wheels 9a, b.
• a sensor such as a mechanical or optical interrupt switch 16
• Both motors 11a, b, which drives the positioning wheels 9a, b, and the optical interrupt switch 16 are connected to the control unit 8. From this point on the positioning wheels 9a, b controls the positioning of the web sample 1, and the motor 7, controlling the feeding wheel 6, is no longer receiving any control signals, i.e. the feeding wheel 6 is free running.
• the crease line 2 is moved towards the folding edge 12 and just as the upper portion 17a of the crease line 2 is crossing the folding edge, it is detected by the upper crease line sensor 14a.
• the upper crease line sensor 14a will immediately send a stop command to the control unit 8, which in turn will stop the upper motor 11a.
• the other motor, lib is however still rotating clockwise, which causes the web sample 2 to turn clockwise until the lower crease line sensor 14b detects the lower portion 17b of the crease line 2.
• the lower crease line sensor 14b send a stop signal to the control unit 8, which in turn will stop the lower motor lib.
• the control unit 8 transports, via the motors 11a, b and the positioning wheels 9a, b, the web sample 1 a predefined distance back towards the folding edge 12 by rotating the positioning wheels 9a, b counter-clockwise.
• a more complex positioning algorithm is however possible within the scope of the invention, which may even move the web sample 1 in a direction perpendicular to the long sides of the web sample 1 by performing a zigzag movement . This is done by alternately rotating the positioning wheels 9a, b back and forth in opposite directions rela- tive each other.
• the web sample 1 is held in that position, e.g. by vacuum device or, as in FIG 1, a clamping device 18, which is also controlled by the control unit 8.
• the clamping device will fix the web sample 1 by pressing it against the base 4, the outer edge of which constitutes the folding edge 12. It is known in the prior art to fix the web sample in a specific position, which is a part of a manual measuring procedure.
• the present invention is based upon this manual measuring procedure .
• a pressure-sensing device 19, originally located next to the web sample 1 as seen in FIG 1, is moved towards the web sample 1 by a small motor 20, controlled by the control unit 8, until an end knob 21 touches the web sample 1. This is the initial measure position, and the pressure-sensing device is thus reset to zero by the control unit 8.
• the pressure-sensing device 19 will measure the force acting on the end knob 21.
• the positioning apparatus 13 is then slowly turned clockwise round an axis of rotation 22 by means of a motor 23, while the pressure sensing device 19 remains at the initial position.
• the absolute amount of rotation may vary, i.e. different measure procedures have been developed where the rotation angle varies from 15 to 45 degrees.
• the pressure- sensing device 19 will prevent the web sample 1 portion, being outside the positioning apparatus 13, from turning. Instead the web sample 1 will bend at the folding edge 12, where the crease line 2 is located.
• the amount of force acting on the knob 21, when the web sample 1 is folded at the crease line 2, is measured and stored in a memory means 24 in the control unit 8. This is a measure of the flexural rigidity of the web sample 1 at the crease line 2.
• the positioning apparatus 13 and the pressure-sensing device 19 then returns to their original positions, preparing for a second measure. It is understood that instead of rotating the positioning apparatus while keeping the pressure-sensing device 19 at a fixed position, the positioning device 13 may be fixed while the pressure-sensing device 19 is moved.
• the control unit 8 sends a control signal to the clamping device 18, whereby the web sample 1 is released and may once again be moved by the positioning wheels 9a, b.
• the control unit 8 via the motors 11a, b and positioning wheels 9a, b, moves the web sample 1 a small ⁇ t ⁇ > o o U ⁇
• TJ cn ⁇ - - : rr cn £-1. ⁇ H- rr SD ⁇ 0 ) ⁇ - ⁇ tr 3 0 3 n 3 £D ⁇ 3 H- ⁇ . ⁇ LQ 0

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
• Control Of Position Or Direction (AREA)
• Folding Of Thin Sheet-Like Materials, Special Discharging Devices, And Others (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20283077

Family Applications (1)

Country Status (2)

Cited By (2)

Citations (4)

• 2001
  • 2001-02-22 SE SE0100588A patent/SE521862C2/sv not_active IP Right Cessation
• 2002
  • 2002-02-22 WO PCT/SE2002/000312 patent/WO2002066957A1/en not_active Application Discontinuation

Patent Citations (4)

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