Paper machine

Abstract

This invention provides a papermaking machine for manufacturing thin paper webs. It is characterized by comprising: a forming section, a pressing section, and a drying section. The pressing section includes a pressing assembly, which includes a main pressing roll, a first pressing roll, and a second pressing roll. The forming section includes a forming fabric belt, and the pressing section includes a transfer fabric belt. The transfer fabric belt includes a transfer base surface and a plurality of recessed units arranged in an array on the transfer base surface. Each recessed unit includes four strip-shaped recesses, with adjacent recesses spaced equidistantly and oriented perpendicularly. Each recess has a depth of 0.08–0.4 mm. This configuration allows for the production of extremely low basis weight tissue paper. This method allows for the use of lower pressing pressure during the papermaking process, significantly reducing the burst point and thus improving the quality of extremely low basis weight tissue paper.

Description

Technical Field

[0001] This invention relates to a papermaking machine, and more particularly to a papermaking machine for producing low-basic-weight tissue paper. Background Technology

[0002] Household paper is widely used in people's daily lives. With the improvement of living standards, people have higher and higher requirements for the softness, thickness, strength, and touch / feel of household paper. In order to take into account the requirements for softness, touch / feel, strength, and thickness, more and more three-layer and four-layer thin paper are used to form multi-layer household paper.

[0003] Meanwhile, in order to make tissue paper thicker, tougher, and more comfortable to the touch, technologies such as TAD (hot air penetration drying) have been developed. After years of development, the high energy consumption and other technical defects of this technology have received increasing attention from the industry. In order to further improve the performance of tissue paper produced by traditional DCT technology, people have combined TAD technology or improved existing DCT technology to develop technologies such as NTT and ATMOS to achieve lower energy consumption and higher bulk of paper.

[0004] These devices, such as those shown in CN103890264A and US6743339B1, are used for making tissue paper. However, with the improvement of living standards, people have increasingly higher requirements for the softness, thickness, strength, and feel / hand feel of tissue paper. In order to take into account the requirements for softness, feel / hand feel, strength, and thickness, more and more three-layer and four-layer thin sheets of paper are used to form multi-layer tissue paper. This has led to an increasingly strong demand for single-layer tissue paper with extremely low basis weight, such as below 12g / m², or below 11g / m², or even below 10g / m². By stacking these single-layer tissue papers with extremely low basis weight, tissue paper with excellent feel / hand feel, strength, and softness can be formed. However, whether it is the traditional DCT, TAD or the improved NTT, ATMOS, they are generally suitable for making tissue paper with a basis weight of more than 12g / m², and are difficult to use for making tissue paper with extremely low basis weight, especially tissue paper below 10g / m².

[0005] In addition, when using traditional NTT technology, a felt as shown in CN101952506A is usually used. When making tissue paper with extremely low basis weight, such as below 9g / m², the paper sheet is extremely thin and the felt has a certain degree of elasticity, which makes it necessary to use higher pressure during the pressing process to achieve better dehydration. When higher pressure is used, these extremely thin paper sheets are more prone to problems such as pitting or dead lines.

[0006] Therefore, an improved technical solution is needed to address the aforementioned technical problems. Summary of the Invention

[0007] Therefore, the present invention provides a papermaking machine to solve the above-mentioned technical problems.

[0008] A papermaking machine for manufacturing thin paper webs, characterized in that it comprises:

[0009] The forming section is used to form the wet paper web;

[0010] The pressing section includes a pressing assembly, which includes a main pressing roll, a first pressing roll that cooperates with the main pressing roll to form a first pressing zone, and a second pressing roll that cooperates with the main pressing roll to form a second pressing zone. The wet paper web passes through the first pressing zone and the second pressing zone to form a pressed paper web.

[0011] The drying section includes a drying cylinder for drying the press paper web to form a dry paper web and a doctor blade for creping the dry paper web to form a thin paper web;

[0012] The forming section further includes a forming fabric belt that supports the wet paper web on the first and second press rolls and passes through the first and second press zones. The pressing section also includes a transfer fabric belt that is wound around the main press roll and transfers the pressed paper web formed after passing through the first and second press zones to the drying cylinder.

[0013] The transfer fabric tape includes a transfer base surface and a plurality of recessed units arranged in an array on the transfer base surface. Each recessed unit includes four strip-shaped recesses. The spacing between adjacent recesses is equal, and the orientation of adjacent recesses is perpendicular. Each recess has a depth of 0.08 to 0.4 mm.

[0014] The shaped fabric strip includes a shaped base surface and a plurality of protruding units arranged in an array on the shaped base surface. The protruding units and the recessed units are arranged correspondingly. The protruding unit includes four strip-shaped protrusions. The protrusions and recesses on the corresponding protruding units and recessed units are perpendicular to each other.

[0015] The height of the protrusion is less than the depth of the recess, and the protrusion has a height of 0.05 to 0.35 mm.

[0016] In the first pressing zone, the first pressing roller applies a first pressure to the main pressing roller, and in the second pressing zone, the second pressing roller applies a second pressure to the main pressing roller. The first pressure is 200-400 KN / m, and the second pressure is 300-450 KN / m.

[0017] The pressing assembly includes an intermediate pressing zone located between the first pressing zone and the second pressing zone, held by a forming fabric belt and a transfer fabric belt. The pressing assembly includes an intermediate pressing device corresponding to the intermediate pressing zone. The intermediate pressing device includes a plurality of third pressing rollers and a pressing belt wound around the plurality of third pressing rollers. The pressing belt includes an intermediate region that abuts against the intermediate pressing zone. The third pressing rollers are configured to apply a third pressure to the forming fabric belt in the intermediate region.

[0018] The main pressing roller includes a rigid sidewall and an accommodating space enclosed by the rigid sidewall. The rigid sidewall includes several through holes extending through the thickness direction of the rigid sidewall. An adsorption box is provided in the accommodating space. The adsorption box includes an adsorption cavity, and the adsorption cavity includes an adsorption port. The adsorption port is correspondingly provided with the first pressing zone, the intermediate pressing zone, and the second pressing zone.

[0019] The recessed portion has an aspect ratio of 2.5 to 4, a length of 0.6 to 0.9 mm, a width of 0.2 to 0.4 mm, and a diameter of 0.1 to 0.4 mm. 2 The area.

[0020] The spacing between adjacent recesses is equal to the spacing between adjacent recessed units.

[0021] Among them, several recessed units are arranged in rows along the X-axis direction, and several rows of recessed units are arranged in columns along one side of the Y-axis direction, with the X-axis direction having an angle of 5° to 15° with the CD direction.

[0022] The distance between adjacent recesses is less than the width of the recess.

[0023] Beneficial Effects: This invention provides a papermaking machine for manufacturing thin paper webs, characterized in that it comprises: a forming section for forming a wet paper web; a pressing section including a pressing assembly, wherein the pressing assembly includes a main pressing roll and a first pressing roll that cooperates with the main pressing roll to form a first pressing zone, and a second pressing roll that cooperates with the main pressing roll to form a second pressing zone, wherein the wet paper web passes through the first pressing zone and the second pressing zone to form a pressed paper web; a drying section including a drying cylinder for drying the pressed paper web to form a dried paper web and a doctor blade for creasing the dried paper web to form a thin paper web; the forming section further includes forming sections on the first pressing roll and the second pressing roll, on which the wet paper web is placed and passed through the first pressing zone and the second pressing zone. The press section further includes a transfer fabric belt wound around the main press roll and transferring the pressed paper web formed after passing through the first press zone and the second press zone to the drying cylinder. The transfer fabric belt includes a transfer base surface and a plurality of recessed units arranged in an array on the transfer base surface. Each recessed unit includes four strip-shaped recesses with equal spacing between adjacent recesses and perpendicular orientation. Each recess has a depth of 0.08 to 0.4 mm. With the above arrangement, it is possible to produce extremely low basis weight tissue paper. This method allows for the use of lower pressing pressure during the papermaking process, which significantly reduces the burst point and thus improves the quality of extremely low basis weight tissue paper. Attached Figure Description

[0024] Figure 1 A schematic diagram of a papermaking machine according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 A schematic diagram of the pressing components;

[0026] Figure 3 A schematic diagram of a recessed element on the transfer base surface;

[0027] Figure 4 A schematic diagram of the raised unit for forming the base surface;

[0028] Figure 5 This is a schematic diagram showing the correspondence between the raised and recessed units during pressing.

[0029] Component descriptions in the diagram:

[0030] Forming section 10; headbox 11; forming roller 12; forming net 14; forming fabric belt 15; forming base surface 150; protrusion unit 1500; first protrusion 1501; second protrusion 1502; third protrusion 1503; fourth protrusion 1504; transfer fabric belt 16; transfer base surface 160; recessed unit 1600; first recessed portion 1601; second recessed portion 1602; third recessed portion 160 3; Fourth recess 1604; Press section 20; Press assembly 200; First press roll 21; First pressing zone 210; Second press roll 22; Second pressing zone 220; Main press roll 23; Intermediate pressing zone 240; Third press roll 241; Press belt 242; Drying section 30; Drying cylinder 31; Air hood 32; Doctor blade 33; Wet paper web 401; Pressed paper web 402; Dry paper web 403; Thin paper web 404. Detailed Implementation

[0031] Please refer to Figure 1 This invention provides a papermaking machine for manufacturing thin paper webs 404, which have a density of 5-25 g / m². 2 The basis weight is particularly suitable for manufacturing materials with a basis weight of 6–12 g / m³. 2 For thin paper width 404, a basis weight of 7-9 g / m² is more suitable. 2 Meanwhile, these thin paper webs 404 are creped, formed from cellulose fibers, and can have a thickness of 40–300 μm, or further a thickness of 60–200 μm, and a thickness of 6–20 cm. 3 / g of bulk thickness, or, at the same time, its MDT is in the range of 40 to 200 N / m and its CDT is in the range of 20 to 180 N / m.

[0032] The paper machine includes a forming section 10, a pressing section 20, and a drying section 30.

[0033] The forming section 10 includes a headbox 11, a forming roller 12, a forming net 14, and a forming fabric belt 15. The headbox 11 is used to spray the cellulose fiber suspension onto the forming net 14. At least a portion of the forming roller 12 is covered by the forming fabric belt 15 and dehydrates the cellulose fiber suspension. The forming fabric belt 15 is an endless loop, at least a portion of which covers the forming roller 12 and supports the movement of the wet paper web 401. At least a portion of the forming net 14 is attached to the forming fabric belt 15 covering the forming roller 12 to form a clamping area. The partially dehydrated cellulose fiber suspension passes through the clamping area to form the wet paper web 401.

[0034] Understandably, on one side of the clamping area, the forming net 14 and the forming fabric belt 15 form a forming area. The headbox 11 includes a plurality of nozzles for spraying cellulose fiber suspension. The nozzles are located in the forming area. The cellulose fiber suspension is sprayed onto the forming net 14. Typically, the position where the cellulose fiber suspension is sprayed onto the forming net 14 is called the landing point. Understandably, the landing point is spaced apart from the clamping area.

[0035] Understandably, the forming net 14 is wound around a plurality of forming rollers and forms an endless loop so that the forming net 14 can circulate, and the forming fabric belt 15 is wound around a plurality of first rollers and forms an endless loop.

[0036] The pressing section 20 is located downstream of the forming section 10 and includes a pressing assembly 200. The pressing assembly 200 includes a main pressing roller 23, a first pressing roller 21, and a second pressing roller 22. The first pressing roller 21 and the main pressing roller 23 cooperate to form a first pressing zone 210, and the second pressing roller 22 and the main pressing roller 23 cooperate to form a second pressing zone 220. The cooperation allows the first pressing roller 21 and the main pressing roller 23 to apply a first pressure to the wet paper web 401 passing through the first pressing zone 210, and the second pressing roller 22 and the main pressing roller 23 to apply a second pressure to the wet paper web 401 passing through the second pressing zone 220.

[0037] In this embodiment, the first press roller 21, the second press roller 22, and the main press roller 23 are all rollers with a coating layer, which can be a polyurethane coating layer. In other embodiments, the first press roller 21 and the second press roller 22 can also be shoe-type presses. Specifically, the main press roller 23 is a rigid roller or a roller with a coating layer, while the first press roller 21 and the second press roller 22 include a shoe-shaped component, a ring belt sleeved outside the shoe-shaped component, a roller that drives the ring belt, and an application component located inside the shoe-shaped component and applying pressure to the shoe-shaped component.

[0038] The press section 20 also includes a transfer fabric belt 16 wound around a plurality of idler rollers and a main press roller 23. The transfer fabric belt 16 passes through the first press zone 210 and the second press zone 220 and transfers the press paper web 402 formed after passing through the first press zone 210 and the second press zone 220 to the downstream direction.

[0039] Understandably, the transfer fabric belt 16 is also in the form of an endless loop so that it can be circulated.

[0040] It is understood that the forming fabric belt 15 also passes through the first press zone 210 and the second press zone 220, and the forming fabric belt 15 and the transfer fabric belt 16 form a clamping shape for the wet paper web 401 in the area between the first press zone 210, the second press zone 220, and the area between the first press zone 210 and the second press zone 220. For ease of description, the area between the first press zone 210 and the second press zone 220, clamped by the forming fabric belt 15 and the transfer fabric belt 16, is referred to as the intermediate press zone 240. It is understood that the wet paper web 401 is subjected to pressure and dewatering in the first press zone 210, the second press zone 220, and the intermediate press zone 240. Specifically, in the first press zone 210, the first press roll 21 applies a first pressure to the main press roll 23, squeezing the water on the wet paper web 401 to form dewatering. In the second press zone 220... The second press roll 22 applies a second pressure to the main press roll 23, squeezing the water on the wet paper web 401 to form dewatering. In the intermediate press zone 240, pressure is applied by the forming fabric belt 15 and the transfer fabric belt 16 to form dewatering. Studies have found that compared with the traditional single pressure application, the wet paper web 401 in this embodiment has a longer pressing time in the press assembly 200, thus having better dewatering efficiency. At the same time, for extremely low basis weight, such as 7-9 g / m² thin paper web 404, the first pressure and the second pressure can be only 30%-50% of the pressing pressure in the prior art, thereby reducing the average burst point by more than 20%. This makes the paper machine of this embodiment particularly suitable for producing extremely low basis weight tissue paper. Specifically, the first pressure can be 200-400 KN / m, and the second pressure can be 300-450 KN / m.

[0041] Meanwhile, the second pressure can be set to be greater than the first pressure. Further research has found that after passing through the first pressing zone 210, the fibers are compacted. Due to the reduced pressure in the intermediate pressing zone 240, the fibers rebound, increasing the gaps between the fibers. Then, the wet paper web 401 is squeezed again through the second pressing zone 220 to form dewatering. Under this action, the wet paper web 401 forms a squeezing-rebounding-squeezing action, which can improve the dewatering efficiency by an average of about 5% compared to conventional pressing.

[0042] Furthermore, the dryness of the wet paper web 401 is 15-30%, and the dryness of the press paper web 402 is 45-70%. Furthermore, after passing through the first press zone 210, the dryness of the wet paper web 401 is 25-40%, and after passing through the second press zone 220, the press paper web 402 is formed.

[0043] Furthermore, the upstream of the first pressing zone 210 includes a front idler roller, and the forming fabric belt 15 is wound around the front idler roller. The forming fabric belt 15 includes a first pressing section between the first pressing zone 210 and the front idler roller, and the included angle between the first pressing section and the transfer fabric belt 16 is 18° to 32°.

[0044] Meanwhile, downstream of the second press zone 220, the forming fabric belt 15 includes a second press section. The angle between the second press section and the transfer fabric belt 16 is also 18 to 32°, so that the wet paper web 401 can easily enter the first press zone 210, and the pressed paper web 402 can easily separate from the forming fabric belt 15 and move with the transfer fabric belt 16.

[0045] Furthermore, the main press roller 23 includes a rigid sidewall and an accommodating space enclosed by the rigid sidewall. The rigid sidewall includes several through holes extending through the thickness direction of the rigid sidewall. Simultaneously, the rigid sidewall can rotate around its axis under the drive of the driving device. An adsorption box is provided in the accommodating space. The adsorption box includes an adsorption chamber and an adsorption port. The adsorption port is correspondingly provided with the first press zone 210, the intermediate press zone 240, and the second press zone 220 to make the first press zone 210, the intermediate press zone 240, and the second press zone 220 a negative pressure state. It can be understood that the adsorption chamber is connected to a negative pressure device. In this case, when the wet paper web 401 is pressed, on the one hand, a dewatering effect is formed under the action of negative pressure, and on the other hand, the water dewatered from the wet paper web 401 is adsorbed and transferred out of the press assembly 200 by the adsorption box.

[0046] The pressing assembly 200 includes an intermediate pressing device corresponding to the intermediate pressing zone 240. The intermediate pressing device includes a plurality of third pressing rollers 241 and a pressing belt 242 wound around the plurality of third pressing rollers 241. The pressing belt 242 includes an intermediate region that abuts against the intermediate pressing zone 240. The third pressing rollers 241 are configured to apply a third pressure to the formed fabric belt 15 in the intermediate region, thereby making the intermediate pressing zone 240 have a larger pressing area, thereby forming a better dehydration effect.

[0047] Furthermore, the third pressure is less than the first and second pressures.

[0048] Please refer to this as well. Figure 3 The transfer fabric belt 16 includes a base portion, and the base portion includes a transfer base surface 160. The transfer base surface 160 refers to the side facing the wet paper web 401 and supporting the press paper web 402. The transfer base surface 160 includes a plurality of recessed units 1600, which are arranged in an array on the transfer base surface 160.

[0049] The array configuration refers to a number of recessed units 1600 arranged in a row along the X-axis direction, and a number of rows of recessed units 1600 arranged in a column along one side of the Y-axis direction. The X-axis direction and the Y-axis direction refer to the X-axis and Y-axis of the Cartesian coordinate system.

[0050] Furthermore, the recessed units 1600 are arranged in an equidistant array, meaning that the spacing between the recessed units 1600 in adjacent rows and columns is equal.

[0051] Each recessed unit 1600 includes four strip-shaped recesses, with adjacent recesses spaced equidistantly and oriented perpendicularly. Each recess is elongated, including length, width, and depth directions. Along the length direction, it includes a pair of ends, and along the width direction, it includes a pair of sides connecting the ends. The aspect ratio of the recess is greater than or equal to 2; preferably, the aspect ratio is 2.5 to 4. Preferably, the ends are arc-shaped. Each recess has a depth of 0.08 to 0.4 mm. In specific embodiments, the recesses can have specific dimensions such as 0.1 mm, 0.012 mm, 0.15 mm, 0.20 mm, 0.24 mm, 0.28 mm, 0.3 mm, and 0.35 mm. In another specific embodiment, the recess has a length of 0.6 to 0.9 mm and a width of 0.2 to 0.4 mm. Additionally, the recess has a depth of 0.1 to 0.4 mm. 2 The area.

[0052] The adjacent recesses are oriented perpendicularly. Specifically, in this embodiment, the recessed unit 1600 includes a first recess 1601, a second recess 1602, a third recess 1603, and a fourth recess 1604. The length direction of the first recess 1601 is perpendicular to the length direction of the second recess 1602. Meanwhile, the length direction of the second recess 1602 is perpendicular to the length direction of the third recess 1603. The length of the third recess 1603 is perpendicular to the length direction of the fourth recess 1604. The length direction of the fourth recess 1604 is perpendicular to the length direction of the first recess 1601.

[0053] Meanwhile, the spacing between adjacent recesses is equal. Specifically, the spacing between the first recess 1601 and the second recess 1602, the spacing between the second recess 1602 and the third recess 1603, the spacing between the third recess 1603 and the fourth recess 1604, and the spacing between the fourth recess 1604 and the first recess 1601 are equal, so that the entire recess unit 1600 is centrally symmetrical.

[0054] Furthermore, the spacing between adjacent recesses is equal to the spacing between adjacent recessed units 1600.

[0055] Furthermore, the distance between adjacent recesses is less than the width of the recess.

[0056] Understandably, the base portion is typically elastic. Studies have found that, through the above-mentioned configuration, it is possible to effectively press and dewater extremely low basis weight thin paper web 404. At the same time, combined with the configuration of the press assembly 200, the pressing time is extended, effectively reducing the generation of burst points and achieving efficient dewatering under low pressing pressure.

[0057] Please refer to this as well. Figure 4 and Figure 5 The formed fabric belt 15 includes a forming base surface 150, which refers to the side facing the wet paper web 401 and supporting the wet paper web 401. The forming base surface 150 includes a plurality of protruding units 1500, which are arranged in an array on the forming base surface 150. At the same time, each protruding unit 1500 is correspondingly arranged with a recessed unit 1600. The corresponding arrangement means that when entering the first pressing zone 210, at least a part of a protruding unit 1500 covers a recessed unit 1600, and each protruding unit 1500 covers only one recessed unit 1600, so that the protruding unit 1500 and the recessed unit 1600 have a one-to-one correspondence. At the same time, the protruding unit 1500 may only cover a part of the recessed unit 1600.

[0058] Understandably, each protruding unit 1500 also includes four strip-shaped protrusions, the height of which is less than the depth of the recess. Specifically, in this embodiment, the protruding units 1500 are also arranged in an array, with adjacent protrusions facing perpendicularly, and each protrusion facing perpendicularly to the corresponding recess. In this embodiment, the protruding unit 1500 includes a first protrusion 1501, a second protrusion 1502, a third protrusion 1503, and a fourth protrusion 1504. The length direction of the first protrusion 1501 is perpendicular to the length direction of the second protrusion 1502. Meanwhile, the second protrusion 1502... The length direction of the third protrusion 1503 is perpendicular to the length direction of the third protrusion 1503, the length of the third protrusion 1503 is perpendicular to the length direction of the fourth protrusion 1504, the length direction of the fourth protrusion 1504 is perpendicular to the length direction of the first protrusion 1501, and the length direction of the first protrusion 1501 is perpendicular to the length direction of the first recess 1601, the length direction of the second protrusion 1502 is perpendicular to the length direction of the second recess 1602, the length direction of the second protrusion 1502 is perpendicular to the length direction of the second recess 1602, and the length direction of the second protrusion 1502 is perpendicular to the length direction of the second recess 1602.

[0059] The above settings ensure that when pressing the extremely low basis weight wet paper web 401, the protrusions and corresponding recesses will not completely overlap, causing the wet paper web 401 to be completely crushed and deformed by the nested protrusions and recesses, or further causing quality problems in subsequent wrinkling.

[0060] Understandably, in this configuration, even if the length of the forming fabric belt 15 and the transfer fabric belt 16 changes or their lateral position changes slightly during operation, the protrusions and recesses will not be completely nested.

[0061] In another embodiment, the X-axis direction can be tilted to the CD direction to further prevent the protrusion from being completely nested with the recess. In a preferred embodiment, the X-axis direction and the CD direction have an angle of 5° to 15°, where the CD direction refers to the direction in which the paper is perpendicular to the machine direction.

[0062] Understandably, each protrusion is also elongated, and each protrusion has the same size and shape as its corresponding recess. Each protrusion has a height of 0.05–0.35 mm. In specific embodiments, the protrusions may have specific dimensions such as 0.06 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.20 mm, 0.24 mm, 0.28 mm, 0.3 mm, and 0.35 mm. In specific embodiments, the protrusions have a length of 0.6–0.9 mm and a width of 0.2–0.4 mm. The recesses have a width of 0.1–0.4 mm. 2 The area.

[0063] Furthermore, the forming section 10 is also provided with several auxiliary dewatering devices. Typically, the auxiliary dewatering devices can be vacuum dewatering rollers or vacuum dewatering boxes. More specifically, the vacuum dewatering box has an adsorption space connected to a negative pressure device. The adsorption space includes an adsorption port adjacent to and facing the forming fabric belt 15. Water in the forming fabric belt 15 and the wet paper web 401 is adsorbed, collected, and discharged through the adsorption port, thereby increasing the dryness of the wet paper web 401 before entering the first pressing zone 210.

[0064] Furthermore, a heating device may be provided in the press section 20. The heating device is configured to increase the dryness of the paper web 402 by passing a hot air stream through it. The hot air stream may be a high-temperature steam stream or a hot air stream.

[0065] Furthermore, the heating device includes a hot airflow box and an adsorption box opposite to the hot airflow box. The hot airflow box and the adsorption box are respectively located on the outer side of the press paper web 402 and the inner side of the transfer fabric belt 16. The hot airflow box includes an airflow opening, and the adsorption box includes an adsorption port. The hot airflow passes through the airflow opening, passes through the press paper web 402 and the transfer fabric belt 16, and flows to the adsorption port. In this case, on the one hand, the dryness of the press paper web 402 can be further improved, and the energy consumption of the subsequent drying section 30 can be reduced. On the other hand, the press paper web 402 can be kept attached to the transfer fabric belt 16 and run. It is understood that the heating device is located in the downstream direction of the press assembly 200.

[0066] The drying section 30 includes a drying cylinder 31 for drying the press paper web 402 to form a dry paper web 403 and a scraper 33 for wrinkling the dry paper web 403 to form a thin paper web 404.

[0067] Understandably, the drying cylinder 31 includes an outer drying surface for attaching and drying the pressed paper web 402, and the pressing section 20 includes a transfer roller for attaching the transfer fabric belt 16 to the outer drying surface. The transfer roller applies pressure to the drying cylinder 31 to form a pressing zone, and the pressed paper web 402 is attached and transferred to the outer drying surface after passing through the pressing zone.

[0068] Understandably, the transfer roller is located inside the transfer fabric belt 16 so that the outer side of the transfer fabric belt 16 adheres to the outer drying surface, thereby transferring the press paper web 402 to the outer drying surface.

[0069] Furthermore, in order to facilitate the easy transfer of the press paper web 402 to the outer drying surface, the outer drying surface has a smooth surface. Additionally, an adhesive material such as a roller adhesive can be sprayed onto the outer drying surface.

[0070] The scraper 33 is disposed downstream of the drying process, and at least one part of the scraper 33 remains attached to the outer drying surface, so that the formed dried paper web 403 impacts the scraper 33 to form wrinkles, and finally forms a thin paper web 404 with wrinkles.

[0071] The scraper 33 can be made of steel, cemented carbide or hard ceramic material, and there is no limitation.

[0072] In addition, an air hood 32 is provided outside the drying cylinder 31, and a medium for drying the press paper web 402, such as high-temperature steam or hot air, is introduced into the air hood 32.

[0073] Furthermore, the forming fabric belt 15 and the transfer fabric belt 16 operate at the same speed.

[0074] The following table shows the results of testing the paper products manufactured using the aforementioned equipment.

[0075]

[0076]

[0077] Among them, the tear points were tested according to the test method in 6.7 of GB / T20810-2006 "Toilet Paper (including Toilet Paper Base Paper)". The tear points were calculated based on the total number of holes. According to the test results above, even with a basis weight of only 8.0 g / m², the total number of holes is still far better than the national standard requirement of 6 holes / m².

[0078] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A papermaking machine for manufacturing thin paper webs, characterized in that, include: The forming section is used to form the wet paper web; The pressing section includes a pressing assembly, which includes a main pressing roll, a first pressing roll that cooperates with the main pressing roll to form a first pressing zone, and a second pressing roll that cooperates with the main pressing roll to form a second pressing zone. The wet paper web passes through the first pressing zone and the second pressing zone to form a pressed paper web. The drying section includes a drying cylinder for drying the press paper web to form a dry paper web and a doctor blade for creping the dry paper web to form a thin paper web; The forming section further includes a forming fabric belt that supports the wet paper web on the first and second press rolls and passes through the first and second press zones. The pressing section also includes a transfer fabric belt that is wound around the main press roll and transfers the pressed paper web formed after passing through the first and second press zones to the drying cylinder. The transfer fabric tape includes a transfer base surface and a plurality of recessed units arranged in an array on the transfer base surface. Each recessed unit includes four strip-shaped recesses. The spacing between adjacent recesses is equal, and the orientation of adjacent recesses is perpendicular. Each recess has a depth of 0.08 to 0.4 mm. The forming fabric tape includes a forming base surface and a plurality of raised units arranged in an array on the forming base surface. The raised units are arranged corresponding to the recessed units. Each raised unit includes four strip-shaped protrusions. The protrusions and recesses on the corresponding raised and recessed units are perpendicular to each other.

2. The papermaking machine as described in claim 1, characterized in that, The height of the protrusion is less than the depth of the recess, and the protrusion has a height of 0.05 to 0.35 mm.

3. The papermaking machine as described in claim 1, characterized in that, In the first pressing zone, the first pressing roller applies a first pressure to the main pressing roller, and in the second pressing zone, the second pressing roller applies a second pressure to the main pressing roller. The first pressure is 200-400 KN / m, and the second pressure is 300-450 KN / m.

4. The papermaking machine as described in claim 3, characterized in that, The pressing assembly includes an intermediate pressing zone located between the first pressing zone and the second pressing zone, held by a forming fabric belt and a transfer fabric belt. The pressing assembly includes an intermediate pressing device corresponding to the intermediate pressing zone. The intermediate pressing device includes a plurality of third pressing rollers and a pressing belt wound around the plurality of third pressing rollers. The pressing belt includes an intermediate region that abuts against the intermediate pressing zone. The third pressing rollers are configured to apply a third pressure to the forming fabric belt in the intermediate region.

5. The papermaking machine as described in claim 4, characterized in that, The main pressing roller includes a rigid sidewall and an accommodating space enclosed by the rigid sidewall. The rigid sidewall includes several through holes extending through the thickness direction of the rigid sidewall. An adsorption box is provided in the accommodating space. The adsorption box includes an adsorption chamber and an adsorption port. The adsorption port is provided in correspondence with the first pressing zone, the intermediate pressing zone, and the second pressing zone.

6. The papermaking machine as described in claim 4, characterized in that, The aspect ratio of the recessed portion is 2.5 to 4, the recessed portion has a length of 0.6 to 0.9 mm, a width of 0.2 to 0.4 mm, and an area of ​​0.1 to 0.4 mm².

7. The papermaking machine as described in claim 6, characterized in that, The spacing between adjacent recesses is equal to the spacing between adjacent recess units.

8. The papermaking machine as described in claim 6, characterized in that, Several recessed units are arranged in rows along the X-axis, and several rows of recessed units are arranged in columns along one side of the Y-axis. The X-axis has an angle of 5° to 15° with the CD direction, where the CD direction refers to the direction in which the paper is perpendicular to the machine direction.

9. The papermaking machine as described in claim 8, characterized in that, The distance between adjacent recesses is less than the width of the recess.

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