Method for adjusting sheet expansion / contraction and adjustment system for sheet expansion / contraction

Abstract

To provide a method for adjusting sheet expansion / contraction and an adjustment system for sheet expansion / contraction that can minimize a dimensional change, curling, etc. that would be caused by a temperature and humidity change of the sheet after produced.SOLUTION: A method for adjusting sheet expansion / contraction includes: an expansion / contraction determination step of detecting marks and, by calculating a distance between the marks, determining whether expansion / contraction of sheet is adequate; a characteristics determination step of, when expansion / contraction has been determined as inadequate in the expansion / contraction step, determining from a basis weight or a moisture content of the sheet to be produced whether the sheet has adequate characteristics; a characteristics adjusting step of, when the characteristics have been determined as inadequate in the characteristics determination step, adjusting the basis weight or the water content to be within the adequate characteristics; and an expansion / contraction adjusting step of after the characteristics adjusting step adjusting the expansion / contraction to be adequate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for adjusting paper shrinkage and expansion and a system for adjusting paper shrinkage and expansion in the manufacture of paper used as securities such as banknotes, stock certificates, bonds, various certificates, and important documents.

Background Art

[0002] In a paper machine, the position of a print mark formed in synchronization with a dandy roll pattern on the paper is measured by a measuring device installed at a position immediately before winding after the calendar part, and it is determined whether the position of the print mark with respect to the flow direction and width direction of the paper is within a previously stored allowable range. A paper shrinkage state management device has been proposed that can control the shrinkage and expansion behavior of paper without requiring the skilled technique of an operator by automatically controlling the temperature of a plurality of dry cylinders, the draw of a size roll, and an expander roll in accordance with the determination result (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, if the shrinkage and expansion behavior is controlled while the basis weight and moisture content of the paper fluctuate, stress strain will remain in various parts of the finished paper. Furthermore, when the paper is gravure printed, it undergoes printing stretch due to a large pressure and shear force. If there is stress strain inside the paper, the paper will partially stretch and deform.

[0005] An object of the present invention is to provide a method for adjusting paper shrinkage and expansion and a system for adjusting paper shrinkage and expansion that can reduce dimensional changes and curling due to temperature and humidity changes of the paper after manufacture.

Means for Solving the Problems

[0006] The method for adjusting paper expansion / contraction according to the present invention as recited in claim 1 is a method for adjusting paper expansion / contraction from marks periodically formed on paper manufactured by a paper-making machine, comprising: a stretching determination step of detecting marks and calculating the distance between the marks to determine whether the paper has appropriate expansion / contraction; a characteristic determination step of determining whether the paper has appropriate characteristics from the basis weight or moisture content of the paper to be manufactured when it is determined in the stretching determination step that the expansion / contraction is not appropriate; a characteristic adjustment step of performing characteristic adjustment by adjusting the basis weight or moisture content so as to obtain appropriate characteristics when it is determined in the characteristic determination step that the characteristics are not appropriate; and a stretching adjustment step of performing adjustment so as to obtain appropriate expansion / contraction after the characteristic adjustment step. The paper expansion / contraction adjustment system according to the present invention as recited in claim 2 is a paper expansion / contraction adjustment system for adjusting paper expansion / contraction from marks periodically formed on paper manufactured by a paper-making machine, comprising: mark detection means 82 for detecting marks; characteristic detection means 83 for detecting the basis weight or moisture content of the paper; characteristic adjustment means 91 for adjusting the basis weight or moisture content; stretching adjustment means 92 for adjusting the expansion / contraction of the paper; and control means 100 for operating the characteristic adjustment means 91 and the stretching adjustment means 92 by determining the detection values from the mark detection means 82 and the characteristic detection means 83.

[0007] In the control means 100, there are provided: a stretching determination unit 110 for determining whether the paper has appropriate expansion / contraction by calculating the distance between the detected marks; a characteristic determination unit 120 for determining whether the paper has appropriate characteristics from the basis weight or moisture content of the measured paper when it is determined by the stretching determination unit 110 that the expansion / contraction is not appropriate; a characteristic adjustment unit 130 for operating the characteristic adjustment means 91 so as to obtain appropriate characteristics when it is determined by the characteristic determination unit 120 that the characteristics are not appropriate; and a stretching adjustment unit 140 for operating the stretching adjustment means 92 so as to obtain appropriate expansion / contraction after the characteristic adjustment unit 130 has made the characteristics appropriate.

Effect of the Invention

[0008] According to the present invention, by performing characteristic adjustment of the paper before performing expansion / contraction adjustment of the paper, dimensional changes, curl, etc. caused by temperature and humidity changes of the paper after manufacturing can be reduced.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0010] The paper expansion / contraction adjustment method according to the embodiment of the present invention includes an expansion / contraction determination step of detecting marks and calculating the distance between the marks to determine whether the paper has appropriate expansion / contraction, and if it is determined in the expansion / contraction determination step that the expansion / contraction is not appropriate, detecting at least one of the basis weight or moisture content of the paper to be manufactured and determining whether the paper to be manufactured has appropriate characteristics, and if it is determined in the characteristic determination step that the characteristics are not appropriate, a characteristic adjustment step of adjusting the basis weight or moisture content so as to have appropriate characteristics, and after the characteristic adjustment step, an expansion / contraction adjustment step of performing expansion / contraction adjustment so as to have appropriate expansion / contraction. According to this embodiment, by performing characteristic adjustment of the paper before performing expansion / contraction adjustment of the paper, dimensional changes, curl, etc. caused by temperature and humidity changes of the paper after manufacturing can be reduced.

[0011] In the paper expansion / contraction adjustment method, if it is determined in the characteristic determination step that the characteristics are appropriate, the expansion / contraction adjustment step is performed without performing the characteristic adjustment step. According to this embodiment, by performing appropriate expansion / contraction adjustment while maintaining appropriate characteristics, there is no partial residual strain, and dimensional changes, curl, etc. caused by temperature and humidity changes of the paper after manufacturing can be reduced.

[0012] Also, in the paper expansion / contraction adjustment method, in the characteristic adjustment step, at least one of the basis weight of the paper stock supplied by slicing, the paper stock concentration in the paper stock concentration adjustment means, the amount of white water in the white water adjustment means, the suction force in the suction box, and the press pressure in the dandy roll or the press section roll is adjusted. According to the present embodiment, for example, characteristic adjustment is performed at locations that can be adjusted according to the papermaking conditions.

[0013] Also, in the paper expansion / contraction adjustment method, in the expansion / contraction adjustment step, at least one of the draw in the expander roll or size roll, the temperature or steam pressure in the dry cylinder, and the tension of the canvas in the dry cylinder is adjusted. According to the present embodiment, for example, expansion / contraction adjustment can be performed at locations that can be adjusted according to the papermaking conditions.

[0014] The paper expansion / contraction adjustment system includes mark detection means for detecting a mark, characteristic detection means for detecting at least one of the basis weight or moisture content of the paper, characteristic adjustment means for adjusting the basis weight or moisture content, expansion / contraction adjustment means for performing expansion / contraction adjustment of the paper, and control means for operating the characteristic adjustment means and the expansion / contraction adjustment means in this order based on the detection values from the mark detection means and the characteristic detection means. According to the present embodiment, by performing characteristic adjustment of the paper before performing expansion / contraction adjustment of the paper, dimensional changes and curling due to temperature and humidity changes of the paper after manufacturing can be reduced.

[0015] Also, in the paper expansion / contraction adjustment method, when it is determined that the detected values from the mark detection means and the characteristic detection means are appropriate characteristics, the expansion / contraction adjustment means is operated without operating the characteristic adjustment means. According to the present embodiment, by performing appropriate expansion / contraction adjustment while maintaining appropriate characteristics, there is no partial residual strain, and dimensional changes and curling due to temperature and humidity changes of the paper after manufacturing can be reduced.

[0016] In the paper expansion / contraction adjustment method, the characteristic adjustment means adjusts at least any one of the basis weight of the paper stock supplied by the slice, the paper stock concentration in the paper stock concentration adjustment means, the amount of white water in the white water adjustment means, the suction force in the suction box, and the press pressure in the dandy roll or the press section roll. According to this embodiment, for example, characteristic adjustment can be performed at locations adjustable according to the papermaking conditions.

[0017] Also, in the paper expansion / contraction adjustment method, the expansion / contraction adjustment means adjusts at least any one of the draw in the expander roll or size roll, the temperature or steam pressure in the dry cylinder, and the tension of the canvas in the dry cylinder. According to this embodiment, for example, expansion / contraction adjustment can be performed at locations adjustable according to the papermaking conditions.

Example

[0018] The paper expansion / contraction adjustment method and paper expansion / contraction adjustment system according to an embodiment of the present invention will be described. FIG. 1 is a conceptual diagram showing the paper expansion / contraction adjustment system according to this embodiment. The paper expansion / contraction adjustment system according to this embodiment performs expansion / contraction adjustment of the paper using marks formed on the paper produced by the paper machine. In the present invention, the marks formed on the paper to be produced are patterns formed by slitting or patterns formed by printing.

[0019] The paper machine performs a sheet forming step 10, a press step 20, an expander step 30, a drying step 40, a size part step 50, and a calendar step 60. In the sheet forming step 10, the paper stock 1 is formed into a sheet-like paper stock mat while promoting the basis weight balance in the width direction and the dispersion of fibers.

[0020] The paper stock 1 flows from the head box 11 to the apron 12 and then to the wire 13 forming a net shape. The wire 13 is spanned between the suction couch roll 14a and the breast roll 14b and is supported by a plurality of table rolls 14c.

[0021] The headbox 11 is disposed upstream of the wire 13. The headbox 11 is supplied with the furnish 1 and the white water 2 and maintains a predetermined liquid level. The furnish 1 mainly consists of pulp fibers, water, chemicals, sizing agents, etc. The supply amount of the white water 2 is adjusted by the white water adjusting means 3. The furnish concentration is adjusted by the furnish concentration adjusting means 4.

[0022] The headbox 11 is provided with a baffle plate 11a for dispersing the furnish 1 and suppressing turbulent flow. By the baffle plate 11a, the furnish 1 is dispersed and the supply balance is made uniform.

[0023] A slice 15 is disposed downstream of the headbox 11. The furnish 1 supplied from the headbox 11 onto the upper surface of the wire 13 flows through the gap between the slice 15 and the wire 13 and forms a furnish mat on the wire 13.

[0024] The apron 12 is laid from the headbox 11 to the slice 15. The downstream portion of the apron 12 is oscillated by the shaking device 16.

[0025] The wire 13 is supported by the table roll 14c and conveys the furnish 1 supplied from the headbox 11 while dewatering it.

[0026] The slice 15 adjusts the flow velocity of the furnish 1 supplied to the wire 13 and the flow rate in the width direction, that is, the basis weight in the width direction of the paper. The slice 15 is divided into a plurality in the width direction, and the partial basis weight can be adjusted by raising and lowering a part of the divided slice.

[0027] The deckle rubber 17 suppresses the supply of the furnish 1 circulating on the wire 13 in the width direction. The shaking device 16 oscillates the wire 13 in the width direction (left - right direction) while the furnish 1 is supplied onto the wire 13 to become a furnish mat, improving the dispersibility of the fibers and adjusting the formation.

[0028] Downstream of the wire 13, a suction box 18 and a dandy roll 19 are arranged. The suction box 18 forcibly sucks and dewater the water contained in the furnish mat. The dandy roll 19 improves the formation of the wet paper and smooths the surface of the wet paper.

[0029] In the press step 20, pressure is applied to the wet paper by at least a pair of press section rolls 21, 22 to dewater it. Downstream of the pair of press section rolls 21, 22, a plurality of paper rolls 23 are arranged.

[0030] In the expander step 30, an expander roll 31 prevents the occurrence of wrinkles and creases in the paper generated in the drying step 40. The expander roll 31 has a curved shape, and adjusts the twist of the paper by changing the arrangement angle, arrangement position, and amount of curvature of the expander roll 31 with respect to the flow method of the paper.

[0031] In the drying step 40, the dehydrated wet paper is dried by a pre-dryer section 40A and an after-dryer section 40B, and the expansion and contraction behavior of the paper is adjusted.

[0032] The pre-dryer section 40A is composed of a plurality of dryer cylinders 41. In the first dryer cylinder 41a, the moisture of the paper is dehydrated at a low temperature to prevent sticking and curling, and in the second dryer cylinder 41b and the third dryer cylinder 41c, the paper is dried to absolute dryness at a high temperature. Also, the adjustment of the paper width is performed by adjusting the temperature in the second dryer cylinder 41b and the third dryer cylinder 41c where the paper moisture has decreased and paper deformation is less likely to occur in the first dryer cylinder 41a.

[0033] The after-dryer section 40B is composed of a plurality of dryer cylinders 42. In the after-dryer section 40B, all the dryer cylinders 42 are used at substantially the same temperature to dry the paper and adjust the paper moisture within the management target value.

[0034] The dry cylinders 41 and 42 can adjust the temperature and the speed. Also, with the dry cylinders 41 and 42, it is possible to adjust the tension of the canvas for restraining the paper. When the tension of the canvas is increased, the restraining force for pressing the paper against the dry cylinders 41 and 42 becomes stronger, so the amount of shrinkage of the paper becomes smaller.

[0035] Between the processes of the pre-dryer section 40A and the after-dryer section 40B, there is a sizing part process 50. In the sizing part process 50, a chemical solution is applied to the surface of the paper in order to reduce paper dust on the paper and improve printability by passing the paper between a pair of sizing rolls 51 to which a predetermined pressure is applied.

[0036] The sizing roll 51 can adjust the draw by changing the rotation speed, and can perform expansion and contraction adjustment in the paper flow direction. Draw is a dimensionless number representing the magnitude of the rotation speed of the roll with respect to the paper flow.

[0037] When the draw is adjusted in the plus direction, the rotation speed of the sizing roll 51 becomes larger with respect to the paper flow, and a stronger tension is applied to the paper between the outlet of the pre-dryer section 40A and the sizing roll 51. When the draw is adjusted in the minus direction, the rotation speed of the sizing roll 51 becomes smaller with respect to the paper flow, and the tension applied to the paper becomes weaker.

[0038] When the draw is increased and a strong tension is applied to the paper, the width direction shrinks and the flow direction elongates. Conversely, when the draw is decreased and the tension applied to the paper is weakened, the width direction elongates and the flow direction shrinks. In this way, by adjusting the draw, the expansion and contraction of the width direction and the flow direction of the paper can be adjusted.

[0039] In the calender process 60, the smoothness of the paper surface and the paper thickness are adjusted by passing the paper between calender rolls 61 to which a predetermined pressure is applied. The paper that has passed through the calender roll 61 is wound up by the reel section 70.

[0040] A dandy roll 19 is arranged on the downstream side of a wire 13 where a furnish mat is formed. By providing a plurality of uneven portions for forming a punched pattern on the surface of the dandy roll 19, a plurality of marks can be periodically imparted in the flow direction and width direction of the wet paper. In the present invention, the method of imparting marks is not limited to the punching process such as the dandy roll 19, and may be imparted by a printing method such as inkjet printing or flexographic printing downstream of the drying step 40.

[0041] Downstream of the calendar roll 61 and up to the reel section 70, there are provided a mark detection means 82 for detecting periodically formed marks and a characteristic detection means 83 for detecting the basis weight of the paper. The characteristic detection means 83 may detect the moisture content. In that case, it is preferable to provide the characteristic detection means 83 at a position upstream of the drying step 40 and downstream of the sheet forming step 10. This is because, based on the result of the detected moisture content, the moisture can be immediately adjusted by the pressing step 20 or the suction box 18 of the sheet forming step 10 on the immediately upstream side. Although the moisture of the dried paper can be adjusted by the drying step 40, adjustment by the temperature or steam pressure in the dry cylinder is not preferable because of its low responsiveness.

[0042] The paper expansion / contraction adjustment system according to this embodiment includes a characteristic adjustment means 91 for adjusting the basis weight or moisture content, an expansion / contraction adjustment means 92 for adjusting the expansion / contraction of the paper, and a control means 100 for operating the characteristic adjustment means 91 and the expansion / contraction adjustment means 92 based on the detection values from the mark detection means 82 and the characteristic detection means 83.

[0043] The control means 100 includes a stretching determination unit 110 that determines whether the paper has appropriate stretching by calculating the distance between marks from the detected marks, a characteristic determination unit 120 that determines whether the paper has appropriate characteristics based on the basis weight or moisture content of the paper to be manufactured when the stretching determination unit 110 determines that the stretching is not appropriate, a characteristic adjustment unit 130 that operates the characteristic adjustment means 91 so as to have appropriate characteristics when the characteristic determination unit 120 determines that the characteristics are not appropriate, and a stretching adjustment unit 140 that operates the stretching adjustment means 92 so as to have appropriate stretching after the characteristic adjustment unit 130 makes the characteristics appropriate.

[0044] When the control means 100 determines that the characteristics are appropriate by the characteristic determination unit 120, the control means 100 operates the stretching adjustment means 92 by the stretching adjustment unit 140 without operating the characteristic adjustment means 91.

[0045] The characteristic adjustment means 91 adjusts at least any one of the basis weight of the furnish 1 supplied at the slice 15, the furnish concentration at the furnish concentration adjustment means 4, the amount of white water at the white water adjustment means 3, the suction force at the suction box 18, and the press pressure at the dandy roll 19 or the press section rolls 21, 22. For example, at the slice 15, the basis weight of the furnish 1 supplied can be increased by raising the slice 15, and when the basis weight is partially low in the width direction, the slice 15 corresponding to the portion with the low basis weight is partially raised.

[0046] At the white water adjustment means 3, the furnish concentration can be increased by closing the supply valve for supplying the white water 2. At the suction box 18, the moisture content can be decreased by increasing the suction force. At the dandy roll 19 or the press section rolls 21, 22, the moisture content can be decreased by increasing the press pressure.

[0047] The stretching adjustment means 92 adjusts at least any one of the draw of the expander roll 31 or the size roll 51, the temperature or steam pressure of the dry cylinders 41, 42, and the tension of the canvas at the dry cylinders 41, 42.

[0048] (Paper Stretching Adjustment Method) Figure 2 is a flowchart showing the paper expansion / contraction adjustment method according to this embodiment. The paper expansion / contraction adjustment method according to this embodiment includes an expansion / contraction determination step (S10), a characteristic determination step (S20), a characteristic adjustment step (S30), and an expansion / contraction adjustment step (S40).

[0049] In the expansion / contraction determination step in S10, marks are detected and the distance between the marks is calculated (S11), and it is determined whether the paper has appropriate expansion / contraction based on the calculated distance between the marks (S12). The determination of whether it is appropriate is, for example, to make a positive / negative determination by comparing the calculated distance between the marks with data such as a database in which a normal range is stored in advance.

[0050] In the characteristic determination step in S20, when it is determined in the expansion / contraction determination step that the expansion / contraction is not appropriate (No in S12), the basis weight or moisture content of the paper is detected (S21), and it is determined whether the paper has appropriate characteristics based on the detected basis weight or moisture content of the paper (S22).

[0051] When it is determined in the expansion / contraction determination step that the expansion / contraction is appropriate (Yes in S12), the process ends without performing the characteristic determination step in S20.

[0052] In the characteristic adjustment step in S30, when it is determined in the characteristic determination step that the characteristics are not appropriate (No in S22), characteristic adjustment is performed by adjusting the basis weight or moisture content so as to have appropriate characteristics.

[0053] In the characteristic adjustment step in S30, at least any one of the basis weight of the paper stock 1 supplied in slice 15, the paper stock concentration in the paper stock concentration adjustment means 4, the amount of white water in the white water adjustment means 3, the suction force in the suction box 18, the press pressure in the dandy roll 19 or the press rolls 21, 22, the temperature or steam pressure in the dry cylinder in the drying process 40, is adjusted.

[0054] When adjustments in the characteristic adjustment step (S30) are made at multiple locations, it may be a system that makes adjustments in a preset order or determines and adjusts the locations where adjustments can be made according to the papermaking conditions.

[0055] For example, when adjusting the moisture content of the wet paper, if the white water adjustment means 3 and the suction box 18 are adjusted, it will also affect the texture of the paper. Therefore, it may be set to prioritize the pressure adjustment of the press section rolls 21 and 22. Further, the characteristic adjustment unit 130 may be configured to include a database regarding the adjustment amounts of the press section rolls 21 and 22 for adjusting the difference with respect to the appropriate characteristics of the moisture content, and perform control to refer to the database and adjust the pressure of the press section rolls 21 and 22 in order to correct the detected moisture content. The control of the characteristic adjustment unit 130 with the above configuration is the same for the white water adjustment means 3, the suction box 18, the dandy roll 19, and the temperature or steam pressure in the dry cylinder for adjusting the moisture content.

[0056] In the expansion / contraction adjustment step in S40, after the characteristic adjustment step (S30), expansion / contraction adjustment is performed so as to achieve appropriate expansion / contraction. In the expansion / contraction adjustment step in S40, at least one of the draw of the expander roll 31 or the size roll 51, the temperature or pressure of the dry cylinders 41 and 42, and the tension of the canvas at the dry cylinders 41 and 42 is adjusted.

[0057] When it is determined in the characteristic determination step that the characteristics are appropriate (Yes in S22), the expansion / contraction adjustment step in S40 is performed without performing the characteristic adjustment step in S30. When adjustments in the expansion / contraction adjustment step (S40) are made at multiple locations, adjustments are made in a preset order or the locations where adjustments can be made are determined and adjusted according to the papermaking conditions.

[0058] For example, since the draw adjustment of the expander roll 31 and the size roll 51 is more responsive than the adjustment by temperature or steam pressure in the dry cylinder, it may be set to prioritize the draw adjustment of the expander roll 31 and the size roll 51. Further, similar to the characteristic adjustment unit 130, the expansion and contraction adjustment unit 140 may be configured to include a database regarding the adjustment amount of the draw of the expander roll 31 for adjusting the difference with respect to proper expansion and contraction, and may be configured to refer to the database and control the adjustment of the draw of the expander roll 31 in order to correct the detected expansion and contraction. The control of the expansion and contraction adjustment unit 140 with the above configuration is the same for the temperature or pressure of the size roll 51 and the dry cylinders 41 and 42 and the stretching of the canvas in the dry cylinders 41 and 42.

[0059] Note that in the characteristic adjustment step in S30, when the basis weight or moisture content is adjusted so as to have proper characteristics, it is determined whether the paper has proper expansion and contraction in the expansion and contraction determination step in S10, and it is determined whether the paper has proper characteristics in the characteristic determination step in S20.

[0060] When it is determined in the expansion and contraction determination step that the expansion and contraction is proper (Yes in S12), the process ends without performing the characteristic determination step in S20. When it is determined in the characteristic determination step that the characteristics are proper (Yes in S22), the expansion and contraction adjustment step in S40 is performed.

[0061] In this way, by performing the characteristic adjustment of the paper before performing the expansion and contraction adjustment of the paper, it is possible to reduce dimensional changes and curling due to temperature and humidity changes of the paper after manufacturing.

Explanation of Signs

[0062] 1 Stock 2 White water 3 White water adjustment means 4 Stock concentration adjustment means 10 Sheet forming process 11a Baffle plate 11 Headbox 12 Apron 13 wires 14a Suction couch roll 14b Breast roll 14c Table roll 15 Slice 16 Shaking device 17 Deckle rubber 18 Suction box 19 Dandy roll 20 Press process 21, 22 Press section rolls 23 Paper roll 30 Expander process 31 Expander roll 40 Drying process 40A Predryer section 40B Afterdryer section 41, 42 Dry cylinders 41a First dry cylinder 41b Second dry cylinder 41c Third dry cylinder 50 Sizing part process 51 Sizing roll 52 Paper tension adjustment mechanism 60 Calendar process 61 Calendar roll 70 Reel section 81 Marking means 82 Mark detection means 83 Characteristic detection means 91 Characteristic adjustment means 92 Expansion and contraction adjustment means 100 Control means 110 Expansion and contraction determination section 120 Characteristic determination section 130 Characteristic adjustment section 140 Expansion and contraction adjustment section

Claims

1. A method for adjusting the expansion and contraction of paper based on marks periodically formed on the paper manufactured by a paper-making machine, comprising: a step of determining expansion and contraction, which detects the marks and calculates the distance between the marks to determine whether the paper has appropriate expansion and contraction; a step of determining characteristics, which, when it is determined in the expansion and contraction determination step that the expansion and contraction is not appropriate, detects at least one of the basis weight or moisture content of the paper to be manufactured and determines whether the paper to be manufactured has appropriate characteristics; a step of adjusting characteristics, which, when it is determined in the characteristics determination step that the characteristics are not appropriate, adjusts the basis weight or the moisture content so as to have the appropriate characteristics; a step of adjusting expansion and contraction, which performs adjustment so as to have the appropriate expansion and contraction after the characteristics adjustment step; The method for adjusting the expansion and contraction of paper is characterized by comprising the above steps.

2. A system for adjusting the expansion and contraction of paper based on marks periodically formed on the paper manufactured by a paper-making machine, comprising: mark detection means for detecting the marks; characteristic detection means for detecting at least one of the basis weight or moisture content of the paper; characteristic adjustment means for adjusting the basis weight or the moisture content; expansion and contraction adjustment means for adjusting the expansion and contraction of the paper; control means for operating the characteristic adjustment means and the expansion and contraction adjustment means in this order by determining whether the detection values from the mark detection means and the characteristic detection means are within an appropriate range; The system for adjusting the expansion and contraction of paper is characterized by comprising the above means.

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