Headbox of low-gram-weight paper machine and pulp homogenizing control system

Abstract

The invention provides a low-gram-weight paper machine headbox and a pulp homogenizing control system, which solve the problems of large transverse quantitative fluctuation of pulp and the like, and comprise a headbox body, a pulp distribution device arranged in the headbox body, an adjustable weir plate device arranged on the pulp distribution device, a pulp distribution taper pipe arranged on the inner wall of the pulp distribution taper pipe, and a spiral flow guide groove arranged on the inner wall of the spiral flow guide groove. The pulp distribution taper pipe is connected with a variable cross-section pore plate; and the variable cross-section pore plate is connected with a turbulence generator. The device has the advantages of good structural stability, uniform slurry flowing and the like.

Description

Technical Field

[0001] This invention belongs to the field of papermaking headbox technology, specifically relating to a low basis weight paper machine headbox and a headbox control system. Background Technology

[0002] The fundamental task of the headbox is to provide favorable conditions for paper sheet formation, namely, to distribute the pulp evenly along the width of the paper machine, ensuring uniform pressure, speed, flow rate, and concentration, as well as controllable and uniform fiber orientation; to effectively disperse pulp fibers, prevent fiber flocculation, and provide and maintain a stable feed head and wire speed ratio according to process requirements. However, in actual use, traditional headbox feed elements are prone to causing large transverse basis weight fluctuations in low-basis-weight paper production, affecting paper uniformity. Furthermore, the turbulence generator has a simple structure and cannot effectively control the flocculation of low-concentration pulp, easily forming fiber clusters, resulting in surface spots or uneven strength on the paper.

[0003] To address the shortcomings of existing technologies, people have conducted long-term explorations and proposed various solutions. For example, Chinese patent literature discloses a novel headbox [201910218941.5], which includes an air cushion chamber body and a turbulence generator. The air cushion chamber body is equipped with a top cover, and the air cushion chamber body is surrounded by wall panels with overflow ports. The lower part of the air cushion chamber body is connected to a mixing chamber through a gap. The turbulence generator is connected to the mixing chamber. The turbulence generator includes a rectangular tube, a transition plate, a circular tube, and a support plate. The support plate is provided with a support plate through hole corresponding to the circular tube, and the support plate through hole is connected to the inlet end of the circular tube. One end of the transition plate is provided with a circular tube through hole corresponding to the circular tube, and the other end of the transition plate is provided with a rectangular through hole corresponding to the rectangular tube. The circular tube through hole of the transition plate is connected to the outlet end of the circular tube, and the rectangular through hole of the transition plate is connected to the inlet end of the rectangular tube.

[0004] The above solution has solved the problem of pulp fiber clusters to some extent, but it still has many shortcomings, such as large lateral quantitative fluctuations in pulp. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a reasonably designed low-grammage paper machine headbox that effectively suppresses lateral quantitative fluctuations in the pulp.

[0006] Another object of the present invention is to provide a homogenization control system for preventing fiber clustering, in order to address the above-mentioned problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a low basis weight paper machine headbox, including a headbox body, a built-in headbox distribution device, the headbox body being equipped with an adjustable weir plate device, the headbox having a headbox cone tube, a spiral guide groove being provided on the inner wall of the headbox cone tube, the headbox cone tube being connected to a variable cross-section orifice plate, and the variable cross-section orifice plate being connected to a turbulence generator.

[0008] In the aforementioned low grammage paper machine headbox, both ends of the feed cone are connected to feed joints via flanges, and support plates are arranged axially on the outer side of the feed cone.

[0009] In the aforementioned low-grammage paper machine headbox, the variable cross-section perforated plate includes a movable perforated plate. The movable perforated plate has circular holes that are evenly distributed in a centrally symmetrical manner, and the inner side of the circular holes is conical. The movable perforated plate is attached to a fixed base plate, and the fixed base plate has through holes that correspond one-to-one with the circular holes. A conical valve core located in the circular holes is installed between the movable perforated plate and the fixed base plate. The conical valve core is connected to the synchronous adjustment component through a linkage rod passing through the through holes.

[0010] In the aforementioned low basis weight paper machine headbox, the synchronous adjustment assembly includes several adjusting rings connected to conical valve cores located in the same circumferential position, with the centers of the adjusting rings coinciding. Each adjusting ring is connected to an adjusting sleeve, and the adjusting sleeves connected to each adjusting ring slide and nest with each other. The adjusting sleeves are connected to sliding push rods, which are hydraulically or electrically driven. When the conical valve core is fully fitted and pressed against the inner side of the circular hole, the adjusting ring is fitted against the fixed base plate and completely blocks the through hole.

[0011] In the aforementioned low-grammage paper machine headbox, the adjustable weir plate device includes a fixed upper lip plate and a lower lip plate hinged to the upper lip plate. A spray nozzle is provided between the upper lip plate and the lower lip plate. Spray holes adjacent to the spray nozzle are arranged along the axial direction on the lower lip plate. A flow adjustment component is provided between the upper lip plate and the lower lip plate.

[0012] In the aforementioned low basis weight paper machine headbox, the headbox adjustment assembly includes an adjustment rod rotatably mounted inside the upper lip plate and extending axially. The adjustment rod is driven by an adjustment motor via a gear set. Several eccentric connecting rods are arranged axially on the adjustment rod. The eccentric connecting rods are driven by a lower lip plate. Guide plates are rotatably mounted inside the upper and lower lip plates. The eccentric connecting rods are driven by a compensating connecting rod.

[0013] In the aforementioned low basis weight paper machine headbox, the turbulence generator includes a turbulence generating pipe installed between the pulp distribution device and the adjustable weir plate device. Inside the turbulence generating pipe, several nested impact pipes are arranged, and the impact pipes are connected by impact plates arranged in a spiral center symmetrical arrangement. Impact holes are opened on the impact plates and impact pipes respectively. Inside the turbulence generating pipe, partition plates are arranged axially, and partition cavities are provided between the turbulence generating pipe, adjacent impact pipes, and partition plates. The partition cavity near the central axis of the turbulence generating pipe is connected through the impact pipes, and the partition cavity near the inner wall of the turbulence generating pipe is connected to the pulp distribution device and the adjustable weir plate device through vortex pipes.

[0014] In the aforementioned low-grammage paper machine headbox, the impact tube is made of polymer material, and the impact tube, partition plate, and turbulence generating tube are joined together using a tenon and mortise structure.

[0015] In the headbox of a low basis weight paper machine described above, an axially extending vibrating rod is installed in the impact tube near the central axis of the turbulence generating tube, and the vibrating rod is connected to a vibrating motor.

[0016] A pulp equalization control system for a low basis weight paper machine headbox is provided. The low basis weight paper machine headbox is described above and includes a controller. The controller is connected to a sensor, a servo control unit, and a frequency converter via the 485 communication protocol. The servo control unit is connected to an adjustable weir plate device. The frequency converter is connected to a feed pump, and the feed pump is connected to a pulp distribution device.

[0017] Compared with existing technologies, the advantages of this invention are as follows: the pulp distribution device adopts a conical tube structure with a built-in guide groove, and the synchronous conical valve core of the variable cross-section orifice plate and the linkage eccentric linkage mechanism of the adjustable weir plate realize the fine and uniform control of the flow rate / velocity distribution of the pulp cross section, effectively eliminating transverse basis weight difference; through spiral guidance, multi-stage turbulence generation and vibration assistance, the problem of easy flocculation and uneven distribution of low basis weight paper fibers is solved; the adjustable lower lip plate angle, independent spray holes and the linkage mechanism of the guide plate with compensation ensure that the pulp flow is stable and the angle is controllable on the web, forming a uniform wet paper web. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the headbox structure of the present invention;

[0019] Figure 2 This is a structural schematic diagram of the headbox of the present invention from another perspective;

[0020] Figure 3 This is a schematic diagram of the headbox structure of the present invention;

[0021] Figure 4 This is a structural schematic diagram of the headbox of the present invention from another perspective;

[0022] Figure 5This is a cross-sectional view of the headbox structure of the present invention;

[0023] Figure 6 This is a structural cross-sectional view of the adjustable weir plate device of the present invention;

[0024] Figure 7 This is a cross-sectional view of the turbulence generator of the present invention;

[0025] Figure 8 This is a schematic diagram of the control system of the present invention;

[0026] In the diagram, the components are: headbox body 1, slurry distribution device 2, adjustable weir plate device 3, upper lip plate 31, lower lip plate 32, slurry nozzle 33, slurry hole 34, adjusting rod 35, adjusting motor 36, eccentric connecting rod 37, guide plate 38, compensation connecting rod 39, slurry distribution cone 4, slurry distribution joint 41, support plate 42, spiral guide channel 5, variable cross-section orifice plate 6, movable orifice plate 61, round hole 62, fixed base plate 63, through hole 64, conical valve core 65, linkage rod 66, adjusting ring 67, adjusting sliding sleeve 68, sliding push rod 69, turbulence generator 7, turbulence generating pipe 71, impact pipe 72, impact plate 73, impact hole 74, partition plate 75, partition cavity 76, vortex tube 77, vibrating rod 78, vibrating motor 79, controller 8, sensor 81, servo control unit 82, frequency converter 83, and slurry pump 84. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1-8 As shown, a low-basis-weight paper machine headbox includes a headbox body 1, a built-in distribution device 2, and an adjustable weir device 3. The distribution device 2 has a distribution cone 4, and a spiral guide groove 5 is provided on the inner wall of the distribution cone 4. The depth and pitch of the spiral guide groove 5 are gradually designed along the axial direction of the distribution cone 4, with a larger groove depth and pitch at the inlet end and a smaller groove depth and pitch at the outlet end, to adapt to the pulp flow acceleration process and enhance the guiding effect. The distribution cone 4 is connected to a variable cross-section orifice plate 6, which is connected to a turbulence generator 7. The variable cross-section orifice plate 6 and the turbulence generator 7 work together to achieve multi-stage turbulence generation, wherein the adjustable weir device 3 stabilizes the output pulp flow to ensure uniform pulp flow.

[0029] Specifically, the two ends of the slurry distribution cone 4 are connected to slurry distribution joints 41 via flanges, and support plates 42 are arranged axially on the outer side of the slurry distribution cone 4. An elastic damping pad is provided between the support plate 42 and the outer wall of the slurry distribution cone 4 to absorb operating vibrations. The lower side of the slurry distribution cone 4 is connected to the variable cross-section orifice plate 6 and the turbulence generator 7 via a vortex tube 77.

[0030] Specifically, the variable cross-section orifice plate 6 includes a movable orifice plate 61. The movable orifice plate 61 has centrally symmetrically distributed circular holes 62, the inner sides of which are tapered. The inner wall surface of the circular holes 62 is coated with a wear-resistant and drag-reducing coating. A fixed base plate 63 is attached to the movable orifice plate 61, and the fixed base plate 63 has through holes 64 corresponding to the circular holes 62. A tapered valve core 65 is installed between the movable orifice plate 61 and the fixed base plate 63, located within the circular holes 62. The end of the tapered valve core 65 is typically equipped with a precision sealing ring to ensure a line seal with the tapered inner wall of the circular holes 62. The tapered valve core 65 is connected to a synchronous adjustment assembly via a linkage rod 66 passing through the through holes 64. The synchronous adjustment assembly drives the tapered valve cores 65 to move in groups, thereby adjusting the gap between the circular holes 62 and the tapered valve cores 65 to achieve fine-tuning of the flow rate, or completely blocking the variable cross-section orifice plate 6.

[0031] In addition, the synchronous adjustment assembly includes several adjusting rings 67 connected to conical valve cores 65 located in the same circumferential position, with the centers of the adjusting rings 67 aligned. Each adjusting ring 67 is connected to an adjusting sleeve 68, and the adjusting sleeves 68 connected to each adjusting ring 67 slide and nest together. A low-friction guide bushing layer is provided between the adjusting sleeves 68. Sliding push rods 69 are connected to the adjusting sleeves 68 via hydraulic or electric drive. Under the action of the sliding push rods 69, adjusting sleeves 68, and adjusting rings 67, the conical valve cores 65 in the same circumferential position move synchronously along the axial direction. The variable cross-section orifice plate 6 can create a slurry flow state where the flow rate in the middle is greater than that on the outer side, forming a larger pressure drop in the central region, thereby consuming more kinetic energy and helping to balance the flow velocity difference, making the slurry flow more uniform. Furthermore, when low-basis-weight fiber slurry flows at high speed, the high-speed flow rate in the center can suppress boundary layer thickening, prevent fiber separation from the fluid flow, and improve stability. The high-flow-rate region in the center can also generate shear force, ensuring uniform fiber distribution.

[0032] The variable cross-section orifice plate 6 can also form a slurry flow state in which the flow rate in the middle is less than that on the outside by adjusting the position of the regulating ring 67. This state is mainly used for rapid cooling of the pipeline in the shutdown state to achieve edge reinforcement of the heat exchange zone.

[0033] When the conical valve core 65 is fully pressed against the inner side of the circular hole 62, the adjusting ring 67 is pressed against the fixed base plate 63 and completely blocks the through hole 64. At this time, the sealing surface of the through hole 64 forms a second-level sealing surface, and the double sealing ensures the sealing effect of the variable cross-section orifice plate 6.

[0034] Meanwhile, the adjustable weir plate device 3 includes a fixed upper lip plate 31 and a lower lip plate 32 hinged to the upper lip plate 31. A slurry nozzle 33 is provided between the upper lip plate 31 and the lower lip plate 32. Slurry holes 34 adjacent to the slurry nozzle 33 are arranged along the axial direction on the lower lip plate 32. The diameter of the slurry holes 34 is distributed in a specific manner along the transverse direction of the paper machine according to the process requirements. A slurry flow adjustment component is provided between the upper lip plate 31 and the lower lip plate 32.

[0035] As can be seen, the slurry flow regulating assembly includes an regulating rod 35 rotatably mounted within the upper lip plate 31 and extending axially. The regulating rod 35 is connected to the regulating motor 36 via a speed-changing gear set, which typically includes a self-locking worm gear mechanism to ensure the regulating position is locked. Several eccentric connecting rods 37 are arranged axially on the regulating rod 35. The eccentric connecting rods 37 are connected to the lower lip plate 32. A guide plate 38 is rotatably mounted within the upper lip plate 31 and the lower lip plate 32. The eccentric connecting rods 37 are connected to the guide plate 38 via a compensating connecting rod 39. The compensating connecting rod 39 and the eccentric connecting rod 37 work together to rotate the guide plate 38, ensuring that the slurry outflow is aligned with the slurry nozzle 33.

[0036] Clearly, the turbulence generator 7 includes a turbulence generating pipe 71 installed between the slurry distribution device 2 and the adjustable weir plate device 3. Inside the turbulence generating pipe 71 are several nested impact pipes 72, the number of which is determined according to the design flow range. Impact plates 73, arranged spirally and centrally symmetrically, connect the impact pipes 72. Impact holes 74 are formed on the impact plates 73 and the impact pipes 72. The arrangement angle and density of the impact holes 74 on the impact plates 73 and impact pipes 72 are optimized using CFD to generate vortices of a specific scale. Inside the turbulence generating pipe 71, partition plates 75 are arranged axially. A partition cavity 76 is provided between the turbulence generating pipe 71 and adjacent impact pipes 72 and partition plates 75. The partition cavity 76 near the central axis of the turbulence generating pipe 71 is connected through the impact pipes 72, and the partition cavity 76 near the inner wall of the turbulence generating pipe 71 is connected to the slurry distribution device 2 and the adjustable weir plate device 3 through a vortex pipe 77.

[0037] Preferably, the impact tube 72 is made of a polymer material, typically PEEK material with excellent wear resistance and chemical stability. The impact tube 72, the partition plate 75, and the turbulence generating tube 71 are joined by a tenon and mortise structure for easy modular disassembly and maintenance.

[0038] Clearly, an axially extending vibrating rod 78 is installed inside the impact tube 72 near the central axis of the turbulence generating tube 71, and the vibrating rod 78 is connected to the vibrating motor 79. The surface of the vibrating rod 78 is provided with guide fins, and its vibration frequency and amplitude are independently adjustable, used to break up fiber flocculation online.

[0039] A headbox homogenization control system for a low basis weight paper machine employs the aforementioned low basis weight paper machine headbox. Its key feature is that the controller 8 is connected to sensors 81, a servo control unit 82, and a frequency converter 83 via the 485 communication protocol. Sensor 81 includes an inlet pressure sensor for the distribution cone 4, a differential pressure sensor before and after the variable cross-section orifice plate 6, a pulp flow velocity sensor for the spray nozzle 33, and a signal from an online paper basis weight / moisture scanner. The servo control unit 82 is connected to an adjustable weir plate device 3, achieving precise closed-loop control of the lip plate opening and the cone valve core 65 opening based on a PID algorithm. The frequency converter 83 is connected to a feed pump 84, which is connected to the distribution device 2. The controller 8 dynamically adjusts the output of the frequency converter 83 based on the signals from sensor 81 to stabilize the total pulp pressure and flow rate.

[0040] Example 1

[0041] This example is used for producing a quantitative quantity of 40g / m³. 2 For thin paper with high pulp flow rate, it is necessary to prevent the pulp flow in the center from being too fast, which could lead to uneven basis weight distribution across the width. Controller 8 receives signals from the pulp flow rate sensor at the spray nozzle 33 and the online basis weight scanner, detecting that the flow rate in the central area is too high and the basis weight is too large. Controller 8 drives the sliding push rod 69 through the servo control unit 82, pushing the adjusting sleeve 68 and the adjusting ring 67. The synchronous adjustment component causes the conical valve core 65 at the center circumferential position to move slightly backward along the linkage rod 66, increasing the gap between the circular hole 62 in the central area of ​​the movable orifice plate 61 and the conical valve core 65.

[0042] The variable cross-section orifice plate 6 creates a slurry flow state where the flow rate in the middle is greater than that on the outer side. The increased pressure drop in the central region consumes more kinetic energy, effectively suppressing the high-speed flow in the center. At the same time, the regulating motor 36 of the adjustable weir plate device 3 drives the regulating rod 35 through a gear set, which in turn drives the eccentric connecting rod 37 to finely adjust the local opening of the lower lip plate 32. This, in conjunction with the compensating connecting rod 39, links the rotation angle of the guide plate 38 to ensure uniform slurry ejection. After the high-speed flow in the center is suppressed, the boundary layer thickening is slowed down, the risk of fiber-fluid separation is reduced, and the uniformity of the horizontal flow is improved.

[0043] Example 2

[0044] This embodiment uses a high proportion of recycled fiber pulp to produce low basis weight paper. The fibers are prone to flocculation, affecting paper uniformity. The vibration motor 79 at the central axis of the turbulence generator 7 is activated. The vibration motor 79 drives the vibration rod 78 to perform high-frequency, low-amplitude vibration along the axial direction. The guide fins on the surface of the vibration rod 78 vibrate with the rod, applying strong shear force and disturbance to the pulp flowing through the central impact pipe 72, efficiently breaking down fiber flocculations online and promoting the dispersion of individual fibers.

[0045] The variable cross-section orifice plate 6 maintains a uniform opening or is finely adjusted based on feedback from sensor 81 to ensure that the pulp enters the turbulence generator 7 in a uniform state. Optimized impact holes 74 on the impact plate 73 and impact tube 72 generate vortices of a specific scale, further dispersing the fibers. Ultimately, this significantly improves paper uniformity and surface quality.

[0046] Example 3

[0047] This embodiment produces high-value-added, low-basis-weight specialty paper, requiring extremely high consistency in basis weight across the paper machine. An online basis weight / moisture scanner scans the paper machine's transverse direction in real time, transmitting the basis weight distribution signal to the controller 8. The controller 8 runs an advanced control algorithm, combining data from multiple sensors 81, including the inlet pressure of the distribution cone 4, the pressure difference before and after the variable cross-section orifice plate 6, and the pulp flow velocity at the injection nozzle 33. Through the servo control unit 82, it finely adjusts the regulating rings 67 at different circumferential positions in groups: driving the corresponding sliding push rods 69 to move the conical valve cores 65 in specific areas, independently adjusting the flow rate in different radial areas of the variable cross-section orifice plate 6.

[0048] The adjustable weir plate device 3, through the adjustment motor 36 driving the adjustment rod 35, drives the eccentric connecting rod 37 and the compensation connecting rod 39 to precisely fine-tune the local opening of the lower lip plate 32 at different positions along the axial direction and the angle of the guide plate 38. The regional flow regulation of the variable cross-section orifice plate 6 and the lip opening / guide angle adjustment of the adjustable weir plate device 3 work together to achieve high-resolution closed-loop control of the transverse pulp distribution of the paper machine, ensuring that the basis weight fluctuation in the cross width is minimized.

[0049] Example 4

[0050] In this embodiment, planned shutdown or short-term fault shutdown requires rapid cooling of the internal piping of the headbox to prevent slurry deposition and solidification, and to ensure sealing. The feed pump 84 stops, and the controller 8 drives all sliding push rods 69 via the servo control unit 82. The sliding push rods 69 push the adjusting sleeve 68 and adjusting ring 67, causing all conical valve cores 65 to move forward significantly along the linkage rod 66 axially. The variable cross-section orifice plate 6 creates a slurry flow state where the flow rate in the middle is less than that on the outer sides. The gap is smallest in the central region and relatively larger on the outer sides.

[0051] Continue pushing the conical valve core 65 until its conical surface is completely pressed against the conical inner wall of the circular hole 62 of the movable orifice plate 61, forming a first-stage line seal. Simultaneously, the adjusting ring 67 tightly presses against the fixed base plate 63, completely sealing the through hole 64, forming a second-stage sealing surface, achieving a double seal to prevent leakage of cooling water or cleaning fluid. With the double seal ensuring airtightness, cooling water is introduced. The cooling water preferentially flows through the larger gap channel formed by the variable cross-section orifice plate 6, achieving preferential and enhanced cooling of the pipeline edge area, accelerating the overall system cooling process, and facilitating rapid maintenance and restart.

[0052] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0053] Although this paper uses a lot of terms such as headbox body 1, slurry distribution device 2, adjustable weir plate device 3, upper lip plate 31, lower lip plate 32, slurry nozzle 33, slurry hole 34, adjusting rod 35, adjusting motor 36, eccentric connecting rod 37, guide plate 38, compensation connecting rod 39, slurry distribution cone 4, slurry distribution joint 41, support plate 42, spiral guide channel 5, variable cross-section orifice plate 6, movable orifice plate 61, round hole 62, fixed base plate 63, through hole 64, conical valve core 65, linkage rod 66, adjusting ring 67, adjusting sliding sleeve 68, sliding push rod 69, turbulence generator 7, turbulence generating pipe 71, impact pipe 72, impact plate 73, impact hole 74, partition plate 75, partition cavity 76, vortex tube 77, vibrating rod 78, vibrating motor 79, controller 8, sensor 81, servo control unit 82, frequency converter 83, and slurry pump 84, the possibility of using other terms cannot be ruled out. The use of these terms is merely for the convenience of describing and explaining the nature of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

Claims

1. A low grammage paper machine headbox, comprising a headbox body (1), wherein the headbox body (1) has a built-in pulp distribution device (2), and the pulp distribution device (2) is equipped with an adjustable weir plate device (3), characterized in that, The slurry distribution device (2) has a slurry distribution cone tube (4), the inner wall of the slurry distribution cone tube (4) is provided with a spiral guide groove (5), the slurry distribution cone tube (4) is connected to a variable cross-section orifice plate (6), and the variable cross-section orifice plate (6) is connected to a turbulence generator (7).

2. The low basis weight paper machine headbox according to claim 1, characterized in that, The two ends of the slurry cone pipe (4) are respectively connected to slurry connectors (41) via flanges, and support plates (42) are arranged axially on the outer side of the slurry cone pipe (4).

3. The low basis weight paper machine headbox according to claim 1, characterized in that, The variable cross-section perforated plate (6) includes a movable perforated plate (61). The movable perforated plate (61) has circular holes (62) that are evenly distributed in a centrally symmetrical manner, and the inner side of the circular holes (62) is conical. The movable perforated plate (61) is attached to a fixed base plate (63), and the fixed base plate (63) has through holes (64) that correspond one-to-one with the circular holes (62). A conical valve core (65) located in the circular holes (62) is installed between the movable perforated plate (61) and the fixed base plate (63). The conical valve core (65) is connected to the synchronous adjustment component through a linkage rod (66) that passes through the through hole (64).

4. A low basis weight paper machine headbox according to claim 3, characterized in that, The synchronous adjustment assembly includes several adjusting rings (67) connected to conical valve cores (65) located in the same circumferential position, and the centers of the adjusting rings (67) are aligned. Each adjusting ring (67) is connected to an adjusting sleeve (68), and the adjusting sleeves (68) connected to each adjusting ring (67) slide and nest with each other. Each adjusting sleeve (68) is connected to a sliding push rod (69) for transmission. The sliding push rod (69) is hydraulically or electrically driven. When the conical valve core (65) is fully pressed against the inner side of the circular hole (62), the adjusting ring (67) is pressed against the fixed base plate (63) and completely blocks the through hole (64).

5. A low basis weight paper machine headbox according to claim 1, characterized in that, The adjustable weir plate device (3) includes a fixed upper lip plate (31) and a lower lip plate (32) hinged to the upper lip plate (31). A grouting port (33) is provided between the upper lip plate (31) and the lower lip plate (32). The lower lip plate (32) has grouting holes (34) arranged axially adjacent to the grouting port (33). A grout flow adjustment component is provided between the upper lip plate (31) and the lower lip plate (32).

6. A low basis weight paper machine headbox according to claim 5, characterized in that, The slurry flow regulating assembly includes an regulating rod (35) rotatably mounted inside the upper lip plate (31) and extending axially. The regulating rod (35) is connected to the regulating motor (36) via a speed-changing gear set. The regulating rod (35) has several eccentric connecting rods (37) arranged axially. The eccentric connecting rods (37) are connected to the lower lip plate (32). A guide plate (38) is rotatably mounted inside the upper lip plate (31) and the lower lip plate (32). The eccentric connecting rods (37) are connected to the guide plate (38) via a compensating connecting rod (39).

7. A low basis weight paper machine headbox according to claim 5, characterized in that, The turbulence generator (7) includes a turbulence generating pipe (71) installed between the slurry distribution device (2) and the adjustable weir plate device (3). The turbulence generating pipe (71) is provided with a plurality of nested impact pipes (72). The impact pipes (72) are connected to each other with impact plates (73) arranged in a spiral center symmetrical arrangement. The impact plates (73) and the impact pipes (72) are respectively provided with impact holes (74). The turbulence generating pipe (71) is provided with partition plates (75) arranged axially inside. The turbulence generating pipe (71) is provided with a partition cavity (76) between the turbulence generating pipe (71) and the adjacent impact pipes (72) and partition plates (75). The partition cavity (76) near the central axis of the turbulence generating pipe (71) is connected through the impact pipes (72). The partition cavity (76) near the inner wall of the turbulence generating pipe (71) is connected to the slurry distribution device (2) and the adjustable weir plate device (3) through the vortex pipe (77).

8. A low basis weight paper machine headbox according to claim 7, characterized in that, The impact tube (72) is made of polymer material, and the impact tube (72), the partition plate (75) and the turbulence generating tube (71) are spliced ​​together by mortise and tenon structure.

9. A low basis weight paper machine headbox according to claim 7, characterized in that, An axially extending vibrating rod (78) is installed inside an impact tube (72) located near the central axis of the turbulence generating tube (71), and the vibrating rod (78) is connected to a vibrating motor (79).

10. A headbox homogenization control system for a low basis weight paper machine, employing the low basis weight paper machine headbox described in any one of claims 1-9, characterized in that, The device includes a controller (8), which is connected to a sensor (81), a servo control unit (82) and a frequency converter (83) via the 485 communication protocol. The servo control unit (82) is connected to an adjustable weir plate device (3), and the frequency converter (83) is connected to a slurry pump (84), which is connected to a slurry distribution device (2).

Images