Technical Field

The present invention relates to engineering of an apparatus for predicting cracking resistance properties of paper and the method thereof.

Background Art

In the production of corrugated boxes, there is an increasing use of paper made from recycled pulp. Coating, such as starch, is applied to increase the paper strength. During wintertime or when the humidity level in the air is low, the paper normally cracks on its creased line when it is folded to form a box. A lot of research has been done and found that cracks occur because the fibers of the paper surface are overly stressed when the paper is folded. When the cracks start, due to the unbearable tension, they spread across the thickness of the paper. This problem mostly happens during a very dry winter season when the moisture content in the paper is not at an appropriate level. As a result, the paper surface is more brittle than usual.

Beside the moisture content affecting the brittleness of the paper surface, it has been found that the characteristics of a creasing blade used to create a creased line on the paper and its pressing force applied onto the paper can also lead to cracks in the created creased line. It is therefore necessary to select an appropriate blade profile and its pressing force that match the type of the paper and the properties of the raw materials used to make that paper.

It is preferable to have an apparatus for predicting cracking resistance properties of paper so that the quality of corrugated boxes from a production process is controllable and the boxes are ensured to be strong. The paper surfaces are not fragile and crack easily when the paper is folded to form a box. Therefore, it is necessary to have an apparatus to test the cracking resistance properties of paper, so that the paper box manufacturing factory can perform tests on the appropriate compression strength values for the raw materials used in each production lot. The apparatus should be able to simulate the characteristics of the crease that would occur in the same manner as the actual creasing line that would occur in the production process.

In Chinese Patent App. No. CN106610360A, the method for evaluating the folding or crack resistance of a cardboard used to make cartons is disclosed. This method is characterized in that it uses a horizontal folding tool to fold a cardboard. Cracks appear at different areas in the creased line on the cardboard where they have less crack resistibility. After the cardboard is folded, the image of the folded cardboard is captured by a scanner. Color contrast on the image is processed to differentiate coating and the cardboard fiber by an image processing software (ImageJ). The processed image is further analyzed to obtain the proportions of the creased area on the cardboard and to evaluate its crack resistance by determining the proportion of the creased area. If the area is large, cracking may be severe, and the cardboard has less crack resistance.

Japanese Pub. No. JP2005024355A has disclosed a crack testing apparatus for a sheet-like article. The apparatus can adjust a folding angle of the article to create a test article that is like a real article made from a production process. The examples of the article are a paper sheet, a book cover, a paper bag, a coated paper, a cardboard, and a multi-layer sheet, etc. The crack testing apparatus in the disclosure comprises a hinge and a stand that adjust the folding angle of the hinge. The apparatus can simulate a folded corrugated paper used in carton making process. However, the apparatus does not have a tool that can create a creased line on a tested article or paper. Therefore, the test still requires a sheet of paper or sample article from real production process. This creates difficulties when performing a test because it cannot be done in one apparatus. Moreover, the apparatus cannot be used to determine an appropriate pressing force to form a creased line on any paper. Human experience is needed to find the right pressing force on the paper when setting up a machine in the production process. The resulting paper is tested repeatedly to find the appropriate pressing force needed, which is very inconvenient.

Thai Petty Patent App. No. 1403001694 has disclosed the invention of an apparatus for testing outside cracks of a paper and cardboard for corrugated boxes. The apparatus uses a circular creasing blade, which moves by a transverse rail, to create a creased line on a sample paper and performs further crack analysis for the creased line. The disclosed apparatus is designed such that the depth of a creased line can be specified. However, the initial depth adjustment process is complicated. As a result, each testing result by using the apparatus has a discrepancy. The resulting creased line, created by the apparatus, cannot be a good representative of the actual creased line that would be created by a real production process.

Thai Patent App. No. 2101004549 has disclosed a portable crack testing device. The device uses a blade mounted on a sliding rail to press down on a sample paper under the test. It utilizes a horizontal movement of the blade to simulate a creased line on the sample paper. The pressing force of the blade on the device is controllable. The device can be conveniently carried by one person from place to place. However, the direction of the pressing force is perpendicular to the sample paper. The direction of the pressing force is not the same as the actual force exerted by the machine in a production process, where a roller blade is used. The creased line simulated by the device, therefore, does not represent the actual creased line that would be created by a real production process.

Moreover, the previously mentioned inventions do not have an image recording device for recording an image of cracks on a creased line. The operator must remove the sample paper that a creased line has been simulated and inspect it by other tools. The inspection of inside and outside cracks requires different image capturing devices and testing equipment. It is therefore inconvenient for an operator to perform the test.

Brief Summary of the Invention

The present invention relates to an apparatus for predicting cracking resistance properties of paper comprising a creasing device, a folding device, a bending device, an image capturing device, and a control device, wherein: the creasing device is used to create a creased line on a sample paper. The creasing device comprises a creasing blade, a guide rail, and a blade holder whereas the creasing blade acts to press down on the sample paper to create a creased line on it, the guide rail controls the movement of the creasing blade by controlling the moving part of the guide rail, and the blade holder is used to attach the creasing blade to the moving part of the guide rail. The creasing blade comprises an outer case and a circular blade rotatably disposed to the outer case so that the circular blade rotates over the sample paper when the moving part of the guide rail moves.

The folding device is used to attach the sample paper and fold it along the creased line, wherein the folding device comprises a base portion and a foldable top portion wherein the base portion and the foldable top portion are foldably disposed together via a first flap and a second flap, which allow the foldable top portion to fold.

The bending device is used to bend the sample paper that has been creased to show the creased line on the paper, wherein the bending device comprises a first paper holder, a second paper holder, and a convex base. The first paper holder is fixedly attached to the first end of the convex base and the second paper holder is fixedly attached to the second end of the convex base, whereas the first paper holder and the second paper holder have a first slot and a second slot, respectively, for inserting the side edges of the sample paper laid on top causing the sample paper to bend over the surface of the convex base. The image capturing device is used to record a crack area or the size of a crack line on the sample paper when the sample paper is folded by the folding device or bent by the bending device. The image capturing device comprises a camera, an illuminator, and a camera pole.

The control device is used to control the movement of the guide rail, wherein the control device comprises a control unit and a user input device.

In some embodiments of this invention, the creasing device may further comprise a vertical guide rail whereas the blade holder is slidably disposed onto the vertical guide rail. And the blade holder may further comprise a blade lock to fix the blade holder to the vertical guide rail. The vertical guide rail and the blade lock allow the pressing force of the creasing blade on the sample sheet being caused by the blade's weight and gravity.

In some embodiments of this invention, the blade holder may further comprise a scale to adjust the height of the creasing blade so that the depth of a creased line on the sample paper can be specified.

In some embodiments of this invention, the circular blade may comprise a circular blade section disposed in between two pre-creasing rolls, each having a circular shape that is slightly smaller than the circular blade section to simulate a creased line on the sample paper that would be used to form a box. The simulated creased line is for testing the outside crack on the creased line of the sample paper.

Moreover, the present invention further relates to a method for inside cracking resistance testing of paper comprising the steps of: a) installing a creasing blade to a blade holder, b) placing a sample paper under a creasing device so that the flute direction of the paper is parallel to the moving direction of the creasing blade, c) releasing a lock to allow the creasing blade to move up and down freely, d) adjusting the scale of the creasing device so that the distance of the creasing blade shows as 0 micrometers, e) allowing the creasing blade to move down freely to touch the sample paper, f) securing a blade lock to restrict the blade holder from its vertical movement, g) adjusting the distance of the creasing blade that presses down on the sample paper so that a creased line having its depth equal to the adjusted distance is created, h) operating a pneumatic guided cylinder to control the moving part of the creasing device, i) controlling a user input device so that the creasing blade moves on the sample paper, j) analyzing the cracking resistance of the sample paper, and k) reporting the test results. In another embodiment, the present invention also relates to a method for outside cracking resistance testing of paper comprising the steps of: a) installing a creasing blade to a blade holder, b) placing a sample paper under a creasing device so that the flute direction of the paper is parallel to the moving direction of the creasing blade, c) releasing a lock to allow the creasing blade to move up and down freely, d) adjusting the scale of the creasing device so that the distance of the creasing blade shows as 0 micrometers, e) allowing the creasing blade to move down freely to touch the sample paper, f) securing a blade lock to restrict the blade holder from its vertical movement, g) adjusting the distance of the creasing blade that presses down on the sample paper so that a creased line having its depth equal to the adjusted distance is created, h) operating a pneumatic guided cylinder to control the moving part of the creasing device, i) controlling a user input device so that the creasing blade moves on the sample paper, j) disposing the sample paper onto a folding device by arranging the surface with the creased line facing away from the base portion, k) arranging the folding device so that the creased line is aligned with the direction of view of the camera, 1) folding the paper by folding the foldable top portion towards the base portion, m) illuminating light on the ridge of the creased line by the illuminator, n) recording the image of the ridge of the creased line on the sample paper, o) analyzing the cracking resistance of the ridge of the creased line on the sample paper from the recorded image, and p) reporting the test results.

The present invention objective is to provide an apparatus for predicting cracking resistance properties of paper comprising a creasing device, a folding device, a bending device, an image capturing device, and a control device, and the method thereof. This invention makes it possible to perform a crack test along a creased line on a paper. The invention creates a creased line on a sample paper using the creasing blade comprising an outer case and a circular blade rotatably disposed to the outer case so that the circular blade rotates over the sample paper. The creasing blade can be released to freely press down on the sample paper with the weight generated by the gravitational force of the earth. And the operator can lock the blade firmly and adjust the distance of the blade to create a desired depth on a creased line. The arrangement of the creasing blade in the present invention replicates the actual creased line created by a real paper box production process. It can be used to test and find the appropriate pressing force for paper produced from diverse raw materials.

In addition, this invention also provides a folding device, a bending device, and an image capturing device that are suitable for detecting either inside or outside cracks on a creased line of a sample paper. These devices are arranged appropriately to allow a creased line image to be captured easily. The image can be automatically analyzed by image processing software, such as ImageJ. The software helps the analysis of the image to perform faster with more accurate results.

Brief Description of the Drawings

Fig. 1 shows the schematic representation of the apparatus for predicting cracking resistance properties of paper in the present invention.

Fig. 2 shows the schematic representation of a paper with a creased line.

Fig. 3 shows the creasing device.

Fig. 4 shows the arrangement of a creasing blade on the sample paper.

Fig. 5 shows the folding device.

Fig. 6 shows the bending device.

Fig. 7 shows the circular blade; 7(a) the circular blade for the inside cracking resistance testing; and 7(b) the circular blade for the outside cracking resistance testing.

Fig. 8 shows the method for inside cracking resistance testing of paper.

Fig. 9 shows the use of the bending device to analyze the cracks on the sample paper.

Fig. 10 shows the example images of inside cracks on creased lines; 10(a) high-strength paper; and 10(b) low-strength paper.

Fig. 11 shows the method for outside cracking resistance testing of paper.

Fig. 12 shows the example images of outside cracks on creased lines; 12(a) high-strength paper; and 12(b) low-strength paper.

Detailed Description of the Invention

An apparatus for predicting cracking resistance properties of paper 100 as shown in FIG.l comprising a creasing device 1, a folding device 2, a bending device 3, an image capturing device 4, and a control device 5.

To perform a cracking resistance test, the apparatus 100 involves the main steps of creating a creased line on a piece of a paper sheet, where the line is used to fold the paper and form it into a paper box, and inspecting cracks that appear on the creased line.

To start the test, the operator takes a piece of a sample paper 9 and presses it with the creasing device 1 to create a creased line 91 on the sample paper 9 as shown in FIG.2. The resulting creased line is a simulated creased line that would be folded to form a paper box. The creased line 91 is intended to have same characteristics as an actual creased line that would appear on a paper obtained from a manufacturing process.

When the sample paper 9 with the creased line 91 is folded, the creased line 91 is considered to have two sides. One is an inner creased line 911 and the other one is an outer creased line 912. The inner creased line 911 is on the side that two pieces of the paper are folded toward each other compressing the liner paper 93 on the inner side. The outer creased line 912 is on the side that two pieces of the paper are folded apart. The liner paper 93 on the outer side is stretched out when the creased line is folded.

The creasing device 1, as shown in FIG.3, is a device that creates the creased line 91 on a sample paper 9. The creasing device 1 comprises a creasing blade 11, a guide rail 12, and a blade holder 13. The creasing blade 11 acts to press down on the sample paper 9 to create the creased line 91 on it. The guide rail 12 controls the movement of the creasing blade 11 on the paper by controlling the moving part 121 of the guide rail 12. The blade holder 13 is used to attach the creasing blade 11 to the moving part 121 of the guide rail 12.

The creasing blade 11 comprises an outer case 112 and a circular blade 114 rotatably disposed to the outer case 112 so that the circular blade 114 rotates over the sample paper 9 when the moving part 121 of the guide rail 12 is controlled to move as shown in FIG.4.

To create the creased line 91 on the sample paper 9, the circular blade 114 is placed in contact with the top surface of the sample paper 9. By controlling the moving part 121 to move on the guide rail 12, the circular blade 114 rotates on the top surface of the sample paper 9 and the creased line 91 is formed.

In some embodiments of the present invention, the creasing device 1 may further comprise a vertical guide rail 14, as shown in FIG.4, whereas the blade holder 13 is slidably disposed onto the vertical guide rail 14. The blade holder 13 may be fixedly disposed onto the vertical guide rail 14 by knots and screws so that the vertical movement of the blade holder 13 is controlled by the movement of the guide rail 14. The use of the vertical guide rail 14 allows the blade holder 13 to press freely against the sample paper 9 by gravity. In practice, the blade holder 13 has a definite weight that creates the creased line 91 on the sample paper 9. Under this condition, the creased line 91 is formed due to the weight of the blade holder 13 as well as the weight of the circular blade 114 being vertically pressed down onto the sample paper 9 due to the gravitational force of the earth. In another embodiment of the present invention, the blade holder 13 may further comprise a blade lock 131 to fix the blade holder 13 to the vertical guide rail 14. The blade lock 131 prevents the movement of the blade holder 13 from moving up or down and maintaining the level of the blade holder when the moving part 121 of the guide rail 12 is moving. This helps maintaining the pressing force that the creasing blade exerts on the sample paper 9 to a stable level.

In some embodiments of this invention, when the pressing distance of the creasing blade 11, which is the depth of the creased line on the sample paper caused by the circular blade 114, is required to be fixed to a specific distance, the blade holder 13 may be equipped with a distance scale 132 to adjust the pressing distance of the creasing blade 11. The scale 132 is used to adjust the distance of the blade holder 13. The adjustment of this distance directly affects the pressing depth that the circular blade 114 presses onto the sample paper 9.

Preferably, the distance scale 132 is further adjusted after locking the blade holder 13 to a distance that the blade holder 13 is freely pressed on the sample paper 9 by the gravitational force. To lock the blade holder 13, the blade lock 131 is a locking mechanism. When the blade holder 13 was locked at the distance caused by the gravity, the distance that the blade presses onto the paper can be further adjusted to a desired distance by the distance scale 132. The preferred distance scale 132 may be made from a screw threaded between the top and bottom screw holes. The rotation of the screw will cause the blade holder 13 to move vertically up or down.

The preferred pressing distance for the blade for this invention can be selected from 400 micrometers, 600 micrometers, and 800 micrometers.

The folding device 2, shown in FIG.5, is used to test the outside cracking resistance of the sample paper. The folding device 2 is used to attach the sample paper with a creased line on it and fold the sample paper along the creased line created by moving the creasing blade 11 over the sample paper 9.

The folding device 2 comprises a base portion 21 and a foldable top portion 22 wherein the base portion 21 and the foldable top portion 22 are foldably disposed together via a first flap 23 and a second flap 24 on the comers of the flaps, allowing the foldable top portion (22) to fold.

The folding unit 2 is designed with a groove 231 between the base portion 21 and the foldable top portion 22 for testing the outside cracking resistance of the sample paper. The sample paper 9 that has been creased by the creasing device 1 is attached or inserted to the base portion 21 and the foldable top portion 22 so that the sample paper 9 lies inward when the two portions are folded together. The creased line 91 is placed along the hinges of the two portions. When the two portions are folded together, the sample paper folds along the creased line 91, with the folded side facing inward as the inner creased line 911. On the outside, there is a ridge line or the outer creased line 912. The groove 231 is designed to allow the outer crease line 912 of the sample paper 9 to be seen through the groove 231. It makes a crack on the outer crease line 912 to be observable.

The bending device 3, as shown in FIG.6, is used to test the inside cracking resistance of the sample paper. The bending device 3 pushes the sample paper upward to show the creased line 91 on the sample paper 9. To test the inside cracking resistance, the sample paper 9 that has been creased by the creasing device 1 is attached to the upper side of the bending device 3 in the way that the creased line 91 is facing upward. This allows a crack on the inner crease line 912 to be observable.

The bending device 3 comprises a first paper holder 31, a second paper holder 32 and a convex base 33. The first paper holder 31 is fixedly attached to the first end of the convex base 33 and the second paper holder 32 is fixedly attached to the second end of the convex base 33. The first paper holder 31 and the second paper holder 32 have a first slot 311 and a second slot 321, respectively, for inserting the side edges of the sample paper laid on top causing the sample paper to bend over the surface of the convex base 33. The curvature of the convex base 33 bends the sample paper and stretches the liner paper 93 that covers the inner creased line 911 so that cracks occurred on the inner creased line 911 can be seen.

The image capturing device 4 is arranged to be a part of the apparatus for predicting cracking resistance properties of paper to record images of the creased line on a sample paper. The device is used to record images when the paper is folded by the folding device 2 for testing an outside cracking resistance, or when the paper is bent by the bending device 3 for testing an inside cracking resistance.

The image capturing device 4 comprises a camera 41, an illuminator 42, and a camera pole 43. The image capturing device 4 should be positioned where the view angle of the camera of the image capturing device 4 can record images on both the folding device 2 and the bending device 3. The camera pole 43 should be at an appropriate height so that the recorded images are sharp enough to be used for analysis.

In a preferred embodiment, the camera 41 should be adjusted so that its Direction-Of-View (DOV) is perpendicular to the folding device 2 and the bending device 3. The illuminator 42 should be adjusted such that light is projected onto the creased line 91 on the sample paper 9. In some embodiments, the camera 41 and the illuminator 42 may be mounted to the camera pole 43 that can be adjusted its mounting angle so that the camera 41 and the illuminator 42 can be directed in the direction of the folding device 2, and the camera 41 and the illuminator 42 can be directed in the direction of the bending device 3 as needed.

In a preferred embodiment, the camera 41 and the illuminator 42 are fixedly disposed onto the camera pole 43, where the camera 41 is positioned in such a way that its DOV is perpendicular to the bending device 3 and the position of the camera 41 on the camera pole 43 can be adjusted to find the right focal length of the camera. In this case, the folding device 2 may be further comprised a base 25 for rotatably disposed to the first paper holder 31 so that the folding device 2 can be aligned with the bending device 3 or rotated away from the bending device 3. This allows the camera 41 to be fixed for each recording without the need to pan the camera away to other directions. The recorded images should have the same reference point and they can be further processed automatically by image processing.

In some embodiments, the camera 41 can adjust its focal length or the camera 41 on the camera pole 43 can be adjusted it position to match the camera focal length. The recorded images are sharp, and they can be further processed accurately.

The control device 5 is used to control the movement of the guide rail 12 to allow the creasing blade 11 to move on the sample paper 9. The control device 5 comprises a control unit 51 and a user input device 52 for controlling the movement of the creasing blade 11.

The user input device 52 may be in different forms such a push button, a trackball, or a control lever (joystick), or in other possible forms that can be understood by a person skilled in the art.

In a preferred embodiment, the moving part 121 of the guide rail 12 should be controlled by a pneumatic guided cylinder so that the movement of the creasing blade 11 has a constant speed. This will make the creased line 91 smooth and be similar to the creased line created by the production process.

FIG.7 shows an example of the preferred circular blade 114 for making the creased line for the inside cracking resistance testing in (a) and outside cracking resistance testing in (b). The circular blade 114 for the inside cracking resistance test has a circular blade section 1141 with sharp edge. The vertical distance of the blade section 1141 should be greater than or equal to the height of the sample paper. The sharp edge of the blade section 1141 is used for pressing and creating a creased line on the surface of the sample paper. The circular blade 114 for the outside cracking resistance test has pre-creasing rolls on the sides of the blade for pressing against the corrugation of the sample paper. In this case, the circular blade 114 comprises a circular blade section 1141 disposed in between two pre-creasing rolls 1142, each having a circular shape that is slightly smaller than the circular blade section 1141. The structural arrangement of the circular blade section 1141 to include the two pre-creasing rolls 1142 is used to create a creased line. The rolls press against the corrugation of the sample paper, which is similar to the edge of the creased line when the paper is folded. The circular blade 114, for the outside cracking resistance test, is intended to create a creased line with sharp folding edges that accelerate the cracking on the opposite surface to the creased line. Therefore, the blade height is less than or equal to half of the thickness of the sample paper and. The pre-creasing rolls 1142 are wide enough to press on both sides of the edges of the creased line on the sample paper.

Both types of the circular blade 114 have a rotary shaft 1143 for installing the blade to the outer case 112 of the creasing device 1. The shape and configuration of the rotary shaft 1143 can take many forms. The shaft may or may not be equipped with bearings to support the rotation of the circular blade 114 as well. It is understood by a person skilled in the art that it can be modified easily.

The method for the cracking resistance testing of paper can be divided into two parts. The former is the method for inside cracking resistance testing and the latter is a method for outside cracking resistance testing.

FIG.8 shows the method for inside cracking resistance testing of paper comprising the steps of: a) installing a creasing blade to a blade holder, b) placing a sample paper under a creasing device so that the flute direction of the paper is parallel to the moving direction of the creasing blade, c) releasing a lock to allow the creasing blade to move up and down freely, d) adjusting the scale of the creasing device so that the distance of the creasing blade shows as 0 micrometers, e) allowing the creasing blade to move down freely to touch the sample paper, f) securing a blade lock to restrict the blade holder from its vertical movement, g) adjusting the distance of the creasing blade that presses down on the sample paper so that a creased line having its depth equal to the adjusted distance is created, h) operating the pneumatic guided cylinder to control the moving part of the creasing device, i) controlling a user input device so that the creasing blade moves on the sample paper, j) analyzing the cracking resistance of the sample paper, and k) reporting the test results. The step for analyzing the cracking resistance of the sample paper can be done in many ways, such as by a visual inspection or by a computer analysis. In this invention, a computer includes the use of any electronic devices or circuits capable of processing in the same manner as a computer, which a person skilled in the art can easily understand or modify it.

The analysis by visual inspection relies on experiences of the analyst to assess the quality of the sample paper. On the other hand, the analysis by a computer is performed by a computer program. The program may be developed by software and/or hardware to control the computer to perform the analysis according to an established procedure. Computer analysis can reduce errors that may occur from visual analysis. Errors from visual analysis can be reduced by using the computer. Moreover, computer analysis allows the process to be performed by ordinary operators. No prior analytical experience is required. Computer analysis is therefore preferred for this invention.

To enhance the cracks on the creased line, the step j) analyzing the cracking resistance of the sample paper may further comprise the following sub-steps: j-1) inserting the sample paper into the first slot and the second slot of the bending device by arranging the surface with the creased line facing up, j-2) illuminating light on the creased line by the illuminator, j-3) recording the image of the creased lines on the sample paper, and j-4) analyzing the cracking resistance of the sample paper from the recorded image as shown in FIG.9.

The bending device 3 serves to bend the sample sheet with the creased line. The sample sheet is placed facing up so that the creased line 91 is on top and the creased line 91 is bended to expand slightly. It enhances the visualization of the cracks inside of the creased line. FIG.10 shows example images of creased lines that were created by the creasing blade 11 of this invention. The figure compares the inside cracks on the creased lines between (a) high-strength paper and (b) low-strength paper.

FIG.ll shows the method for outside cracking resistance testing of paper comprising the steps of: a) installing a creasing blade to a blade holder, b) placing the sample paper under a creasing device so that the flute direction of the paper is parallel to the moving direction of the creasing blade, c) releasing a lock to allow the creasing blade to move up and down freely, d) adjusting the scale of the creasing device so that the distance of the creasing blade shows as 0 micrometers, e) allowing the creasing blade to move down freely to touch the sample paper, f) securing a blade lock to restrict the blade holder from its vertical movement, g) adjusting the distance of the creasing blade that presses down on the sample paper so that a creased line having its depth equal to the adjusted distance is created, i) controlling a user input device so that the creasing blade moves on the sample paper, j) disposing the sample paper onto a folding device by arranging the surface with the creased line facing away from the base portion, k) arranging the folding device so that the creased line is aligned with the direction of view of the camera, 1) folding the paper by folding the foldable top portion towards the base portion, m) illuminating light on the ridge of the creased line by the illuminator, n) recording the image of the ridge of the creased line on the sample paper, o) analyzing the cracking resistance of the ridge of the creased line on the sample paper from the recorded image, and p) reporting the test results.

The folding device 2 folds the sample paper by folding the foldable top portion 22 into the base portion 21 with the sample paper inside. The outside portion of the creased line is stretched and the liner sheet 93 on the outside is also stretched. This helps to visualize the cracks on the outside of the creased line.

For outside cracking resistance test, the sample paper is placed in the folding device 2 to fold the sample paper downward. The creased line on the paper faces up so that the camera 41 can take pictures of the outside of the creased line 91. FIG.12 shows example images of the outside of creased lines created by the creasing blade 11 of this invention. The figure compares the outside cracks on the creased lines between (a) high-strength paper and (b) low-strength paper.

In the present invention, the distance of the creasing blade pressing down on the sample paper for both the inside and outside cracking resistance tests should be based on type and thickness of the paper. Preferably, the distance of the creasing blade pressing down on the sample paper can be selected from 400 micrometers, 600 micrometers and 800 micrometers.

In addition, when a computer is used to analyze the inside and outside cracking resistance tests, the processing step of analyzing the cracking resistance of the ridge of creased line on the sample paper from the recorded image may be automatically performed by a computer software. The computer software, according to this invention, includes software, firmware, or microcontroller firmware for the control device 5 that is designed to analyze the cracks from an image. A good example of the software for this purpose is ImageJ.

The process of reporting the test results of the methods of this invention may be in many forms such as displaying the results on the controller's screen if the control device has a display screen, or sending the results to display on another display connected to the control device, or sending the results via the internet to display by a mobile device connected to the internet, etc.