Lightweight fiberboard manufacturing method based on semi-dry process

Abstract

The invention discloses a light fiberboard manufacturing method based on a semi-dry process. The light fiberboard manufacturing method comprises the following steps that S1, wood is cut into wood chips; s2, the wood chips are screened; s3, the wood chips are preheated and cooked through a defibrator, fibers are obtained through mechanical separation, and the fibers enter a downstream pulp pool; s4, adding water to dilute the fibers in the pulp tank, and stirring to prepare fiber pulp; step S5, paving into a continuous plate blank through a fourdrinier forming machine; s6, the continuous plate blanks are dehydrated; s7, the continuous plate blanks are cut into fiber plate blanks; step S8, pressurizing and heating the fiber board blank through a hot press to prepare a semi-dry light board; step S9, carrying out drying treatment on the semi-dry light board; s10, the light fiberboard is sawn and cut; the production method has the advantages that glue adding is not needed, formaldehyde release is avoided, and the produced light fiberboard is low in density, light in weight and low in transportation cost; the sound absorption and noise reduction functions are realized, and the heat insulation performance is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiberboard manufacturing, in particular to a light fiberboard manufacturing method based on a semi-dry process. BACKGROUND

[0002] With the progress of society and the continuous improvement of human environmental protection consciousness, artificial boards gradually replace natural wood in the field of building decoration, and fiberboard is widely used. In China, fiberboard is divided into four categories according to its density: fiberboard with nominal density less than or equal to 0.45 g / cm 3 is light fiberboard, nominal density between 0.45-0.65 g / cm 3 is low-density fiberboard, nominal density between 0.65-0.80 g / cm 3 is medium-density fiberboard, and nominal density greater than 0.80 g / cm 3 is high-density fiberboard; among them, light fiberboard is made of wood fiber or other plant fiber as raw material, with or without adhesive and other auxiliary materials, which has the advantages of light weight, low transportation cost, low raw material consumption, good sound absorption and heat preservation, and is widely used in indoor building decoration, furniture, high-fidelity sound, composite board core material and other fields; patent No. CN102806591A discloses a manufacturing process of ultra-light fiberboard, which specifically discloses the steps of peeling, slicing, screening, washing, cooking, fiber separation, glue application, drying and sorting, laying and forming, pre-pressing, hot pressing, turning plate cooling, sanding, inspection and sorting, packaging and warehousing; but there are problems such as the need to add glue, the release of formaldehyde, poor environmental performance, high production cost, complicated preparation process, low production efficiency and the like. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the existing defects and provide a light fiberboard manufacturing method based on a semi-dry process, which does not need to add glue, does not release formaldehyde, has excellent environmental performance, low production cost, high production efficiency, low density, light weight, low transportation cost, sound absorption and noise reduction function, especially better high-frequency noise absorption effect, good heat insulation performance, and can effectively solve the problems in the background art.

[0004] To achieve the above purpose, the present application provides the following technical scheme: a light fiberboard manufacturing method based on a semi-dry process, comprising the following steps: Step S1, slicing process: slicing machine is used to slice wood into wood chips meeting the specifications; Step S2, screening process: the sliced wood chips are screened by a vibrating screen, and the wood chips meeting the specifications are subjected to the next process, and the wood chips larger than the specifications are subjected to slicing treatment again; Step S3, hot grinding process: the wood chips screened out are preheated and cooked by a hot grinder, and fibers are mechanically separated and enter the downstream pulp tank; Step S4, dilution process: the fibers in the pulp tank are diluted and stirred by adding water to make fiber slurry; Step S5, laying process: the obtained fiber slurry is laid into continuous board blanks by a long net forming machine, and the water content of the board blanks is controlled at 80% to 97%; Step S6, dewatering process: the continuous board blanks are dewatered by a dewatering device combining vacuum dewatering and mechanical dewatering, and the water content of the dewatered continuous board blanks is controlled at 40% to 60%; Step S7, first sawing process: the continuous board blanks are divided into one by one fiber board blanks; Step S8, hot pressing process: the fiber board blanks are pressed and heated by a hot press to make semi-dry lightweight boards; the pressure on the fiber board blanks is 0.44MPa to 0.70MPa, the hot pressing time is 10min to 20min, the hot pressing temperature is 150℃ to 200℃, and the water content of the semi-dry lightweight boards after hot pressing is controlled at 15% to 30%; Step S9, drying process: the semi-dry lightweight boards are dried by a drying room, the drying temperature is 65℃ to 95℃, and the drying time is 2h to 3h to ensure that the water content of the finished lightweight fiber boards is controlled at 5% to 15%; Step S10, second sawing process: the dried lightweight fiber boards are sawed according to the required specifications.

[0005] Further, the length of the wood chips prepared in step S1 is 3cm to 6cm.

[0006] Further, the temperature of the hot grinding process in step S3 is 150℃ to 180℃, the hot grinding pressure is 0.8MPa to 0.9MPa, and the hot grinding time is 3min to 5min.

[0007] Further, a cooling process is performed after step S3, and a cyclone separator is used to separate the fibers and high-temperature steam ground out by the hot grinder, the high-temperature steam rises and is discharged, and the fibers are cooled and fall into the downstream pulp tank.

[0008] Further, the fiber concentration of the fiber slurry in step S5 is 25% to 30%.

[0009] Further, the waste water discharged in step S6 is transported to the pulp tank in step S4 to realize internal circulation of production waste water.

[0010] Further, a board blank inspection process is performed after step S7: the sawed fiber board blanks are inspected, the qualified fiber board blanks enter the next process, and the unqualified fiber board blanks are transported to the pulp tank in step S4.

[0011] Further, after the step S10, a board inspection process is carried out, and unqualified light fiber boards are crushed into fibers by a plate crusher and a refiner and then transported to the pulp tank of step S4.

[0012] Further, the dehydration equipment combining vacuum dehydration and mechanical dehydration in step S6 comprises a rack, a board blank conveying roller, a vacuum dehydration machine, a pre-pressing dehydration mechanism, a pressure maintaining dehydration mechanism and a squeezing dehydration mechanism are arranged on the rack in sequence; the pre-pressing dehydration mechanism comprises a lower pre-pressing frame fixedly arranged on the rack, an upper pre-pressing frame arranged above the lower pre-pressing frame on the rack, and a plurality of pre-pressing rollers arranged on the lower pre-pressing frame and the upper pre-pressing frame for pre-pressing dehydration of the board blank; the pressure maintaining dehydration mechanism comprises a lower pressure maintaining frame fixedly arranged on the rack, an upper pressure maintaining frame arranged above the lower pressure maintaining frame on the rack, and a plurality of pressure maintaining rollers arranged on the upper pressure maintaining frame and the lower pressure maintaining frame for pressure maintaining dehydration of the board blank; the squeezing dehydration mechanism comprises a lower squeezing roller arranged on the rack, and an upper squeezing roller arranged above the lower squeezing roller on the rack; the pre-pressing rollers on the upper pre-pressing frame, the pressure maintaining rollers on the upper pressure maintaining frame and the upper squeezing roller are provided with an annular upper mesh belt, the board blank conveying roller, the pre-pressing rollers on the lower pre-pressing frame, the pressure maintaining rollers on the lower pressure maintaining frame and the lower squeezing roller are provided with an annular lower mesh belt, and the lower mesh belt is attached to the upper side of the vacuum dehydration machine; a plurality of worm and gear elevators are arranged on the rack, and worm and gear elevators are arranged between the rack and the upper pre-pressing frame, between the rack and the upper pressure maintaining frame, and between the rack and the upper squeezing roller, the worm and gear elevators are fixedly arranged on the rack, a hinge joint is arranged on the lifting output shaft of the worm and gear elevator, the upper pre-pressing frame, the upper pressure maintaining frame and the upper squeezing roller are connected to the corresponding hinge joints through the hinge seats, and the hinge joint is a long circular hole structure; the rack and the upper pre-pressing frame and the rack and the upper pressure maintaining frame are provided with a pressurized air bag; a tensioning roller is arranged on the rack at a position corresponding to the upper mesh belt and the lower mesh belt, and a driving device is arranged on the rack to drive the upper squeezing roller and the lower squeezing roller to rotate.

[0013] Further, the drying room in step S9 comprises a heat preservation room, a plurality of heating sources are arranged on one side of the length direction of the heat preservation room in a transverse manner, and the inner side of each heating source is provided with a circulating fan; a uniform air distribution plate is vertically arranged on the inner side of the circulating fan on the bottom plate of the heat preservation room, a plurality of air holes are uniformly arranged on the uniform air distribution plate, the height of the uniform air distribution plate is lower than the height of the heat preservation room, a circulating partition plate is transversely arranged at the top end of the uniform air distribution plate, and a flowing gap is left between the circulating partition plate and the two side walls in the length direction of the heat preservation room; a drying position is arranged in the heat preservation room at a position corresponding to the circulating fan; and a dehumidification system is arranged at the top end of the heat preservation room. The drying process in step S9 is automatically operated according to a preset drying process curve in the drying initial stage, the drying middle stage and the drying later stage, in the drying initial stage, the water evaporation amount is large, the drying moisture removal amount is large, and the drying temperature cannot be too high; in the drying middle stage, the evaporation amount is reduced, the drying moisture removal amount is reduced accordingly, and the drying temperature can be appropriately increased; in the drying later stage, the evaporation amount is further reduced, the moisture removal amount is further reduced, and the drying temperature should be reduced.

[0014] Compared with the prior art, the beneficial effects of the present application are: the light fiberboard produced by the light fiberboard manufacturing method based on the semi-dry process has performance indicators of water content, static bending strength and water absorption thickness expansion rate meeting the national industry standard; the light fiberboard has low density, light weight and low transportation cost; has sound absorption and noise reduction function, especially better sound absorption effect on high frequency noise; has good heat insulation performance; does not need to add glue, does not release formaldehyde, and has excellent environmental protection performance; has low production cost and high production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The light fiberboard manufacturing method of the present application is shown in the flow chart; Figure 2 The structure of the dehydration equipment of the present application is shown in the schematic diagram; Figure 3 The front view of the dehydration equipment of the present application is shown in the schematic diagram; Figure 4 The local enlarged view of the dehydration equipment of the present application is shown in the schematic diagram; Figure 5 The structure of the dehydration equipment of the present application is shown in the schematic diagram; Figure 6 The internal structure of the drying room of the present application is shown in the side view.

[0016] In the figure: 1, rack; 2, board blank conveying roller; 3, vacuum dehydration machine; 4, pre-pressing dehydration mechanism; 41, upper pre-pressing frame; 42, lower pre-pressing frame; 43, pre-pressing roller; 5, pressure maintaining dehydration mechanism; 51, upper pressure maintaining frame; 52, lower pressure maintaining frame; 53, pressure maintaining roller; 6, pressing dehydration mechanism; 61, upper pressing roller; 62, lower pressing roller; 7, upper mesh belt; 8, lower mesh belt; 9, worm and gear elevator; 91, hinged joint; 92, pressurized air bag; 11, tensioning roller; 100, heat preservation room; 101, heating source; 102, circulating fan; 103, uniform air distribution plate; 104, moisture removal system; 105, drying parking space; 106, circulating partition. DETAILED DESCRIPTION

[0017] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application. Embodiment one

[0018] Please refer to Figure 1 The present application also provides a technical solution: a light fiberboard manufacturing method based on a semi-dry process, comprising the following steps: Step S1, slicing process: wood is sliced into wood chips with a side length of 3-6 cm by a chipper; Step S2, screening process: the sliced wood chips are screened by a vibrating screen, and the wood chips meeting the specifications are subjected to the next process, and the wood chips larger than the specifications are subjected to slicing again; Step S3, hot grinding process: the screened wood chips are preheated and cooked by a hot grinder, and fibers are obtained by mechanical separation; the temperature of the hot grinding process is 150°C, the hot grinding pressure is 0.8 MPa, and the hot grinding time is 3 min; the fibers obtained by mechanical separation are subjected to a cooling process, i.e., the fibers and high-temperature steam obtained by hot grinding are separated by a cyclone separator, the high-temperature steam is discharged upward, and the fibers are cooled and lowered to enter a downstream pulp pool; the cooling process prevents the fermentation of high-temperature fiber pulp and the generation of peculiar smell, and prevents the temperature of the subsequent dilution process from being too high; Step S4, dilution process: the fibers in the pulp pool are diluted and stirred by adding water to prepare fiber pulp, and the fiber concentration of the fiber pulp is 25%; Step S5, laying process: the obtained fiber pulp is laid into a continuous board blank by a long net forming machine, and the water content of the board blank is controlled at 80%; Step S6, dehydration process: the continuous board blank is dehydrated by a dehydration device combining vacuum dehydration and mechanical dehydration, and the water content of the dehydrated continuous board blank is controlled at 40%; the waste water discharged in this process is transported to the pulp pool in step S4, realizing the internal circulation of production waste water; Step S7, first sawing process: the continuous board blank is divided into one fiber board blank after another; the sawed fiber board blank is subjected to a board blank inspection process, and the qualified fiber board blank enters the next process, and the unqualified fiber board blank is transported to the pulp pool in step S4; Step S8, hot pressing process: the fiber board blank is subjected to pressure and heating by a hot press to prepare a semi-dry light board; the pressure intensity to which the fiber board blank is subjected is 0.44 MPa, the hot pressing time is 10 min, the hot pressing temperature is 150°C, and the water content of the semi-dry light board after hot pressing is controlled at 15%; Step S9, drying process: the semi-dry light board is dried by the drying room, the drying temperature is 65℃, the drying time is 2h, and the moisture content of the finished light fiber board after drying is controlled at 5%; Step S10, secondary sawing process: the dried light fiber board is sawed according to the required specification; the sawed light fiber board is subjected to a board inspection process, and the unqualified light fiber board is crushed and ground into fibers by a board crusher and a precision grinder and then conveyed to the pulp tank of step S4.

[0019] Please refer to Figures 2-4 The dehydration equipment combining vacuum dehydration and mechanical dehydration in step S6 includes a rack 1, the rack 1 is sequentially provided with a board conveying roller 2, a vacuum dehydration machine 3, a pre-pressing dehydration mechanism 4, a pressure maintaining dehydration mechanism 5 and a pressing dehydration mechanism 6; the pre-pressing dehydration mechanism 4 includes a lower pre-pressing frame 42 fixedly arranged on the rack 1, an upper pre-pressing frame 41 arranged above the lower pre-pressing frame 42 on the rack 1, and a plurality of pre-pressing rollers 43 for pre-pressing dehydration of the board blank arranged on the lower pre-pressing frame 42 and the upper pre-pressing frame 41; the pressure maintaining dehydration mechanism 5 includes a lower pressure maintaining frame 52 fixedly arranged on the rack 1, an upper pressure maintaining frame 51 arranged above the lower pressure maintaining frame 52 on the rack 1, and a plurality of pressure maintaining rollers 53 for pressure maintaining dehydration of the board blank arranged on the upper pressure maintaining frame 51 and the lower pressure maintaining frame 52; the pressing dehydration mechanism 6 includes a lower pressing roller 62 arranged on the rack 1, and an upper pressing roller 61 arranged above the lower pressing roller 62 on the rack 1; the pre-pressing rollers 43 on the upper pre-pressing frame 41, the pressure maintaining rollers 53 on the upper pressure maintaining frame 51 and the upper pressing roller 61 are provided with an annular upper mesh belt 7, the board conveying roller 2, the pre-pressing rollers 43 on the lower pre-pressing frame 42, the pressure maintaining rollers 53 on the lower pressure maintaining frame 52 and the lower pressing roller 62 are provided with an annular lower mesh belt 8, and the lower mesh belt 8 is attached above the vacuum dehydration machine 3; a plurality of worm and gear elevators 9 are arranged on the rack 1, the worm and gear elevators 9 are arranged between the rack 1 and the upper pre-pressing frame 41, between the rack 1 and the upper pressure maintaining frame 51, and between the rack 1 and the upper pressing roller 61, the worm and gear elevators 9 are fixedly arranged on the rack 1, a hinge joint 91 is arranged on the lifting output shaft of the worm and gear elevator 9, the upper pre-pressing frame 41, the upper pressure maintaining frame 51 and the upper pressing roller 61 are connected to the corresponding hinge joints 91 through hinge seats, and the hinge joints 91 are long circular hole structures; the rack 1 and the upper pre-pressing frame 41 and the rack 1 and the upper pressure maintaining frame 51 are provided with pressure air bags 92; the rack 1 is provided with tensioning rollers 11 at positions corresponding to the upper mesh belt 7 and the lower mesh belt 8, and the rack 1 is provided with a driving device for driving the upper pressing roller 61 and the lower pressing roller 62 to rotate; The vacuum dehydration machine 3 is a prior art, and can refer to the online dehydration system for fiber board blanks disclosed in patent publication No. CN211194270U, which will not be described in detail herein; The dewatering device shown in the embodiment first performs vacuum dewatering on the continuous board blank through the vacuum dewatering machine 3, and then performs mechanical dewatering on the continuous board blank through the pre-pressing roller 43, the pressure maintaining roller 53 and the press roller, so as to improve the dewatering effect on the continuous board blank and meet the dewatering requirement on the board blank with high water content; the pressure maintaining roller 53 is closely arranged between the pre-pressing roller group and the press roller group in the mechanical dewatering stage, so as to increase the length of the board blank pressure dewatering section and reduce the rebound effect of the board blank in the pressing process; the wrap angle of the upper mesh belt 7 and the lower mesh belt 8 in driving the press roller is increased through the tensioning roller 11, and the driving force of the upper mesh belt 7 and the lower mesh belt 8 is increased, so as to avoid the phenomenon that the upper mesh belt 7 and the lower mesh belt 8 slip due to the pressure of the press roller; and the pressure pressing force and the pressure pressing position of the pre-pressing roller 43, the pressure maintaining roller 53 and the upper press roller 61 and the lower press roller 62 can be adjusted according to the process requirement through the pressure pressing air bag 92 and the worm and gear elevator 9.

[0020] Please refer to Figures 5-6 The drying room includes a heat preservation room 100, a plurality of heating sources 101 are arranged transversely on one side of the heat preservation room 100 in the length direction, and a circulating fan 102 is arranged on the inner side of each heating source 101; a uniform air distribution plate 103 is vertically arranged on the bottom plate of the heat preservation room 100 on the inner side of the circulating fan 102, the uniform air distribution plate 103 is uniformly provided with air holes, the height of the uniform air distribution plate 103 is lower than the height of the heat preservation room 100, the top end of the uniform air distribution plate 103 is transversely provided with a circulating partition plate 106, and the circulating partition plate 106 is provided with a flowing gap with the two side walls of the heat preservation room 100 in the length direction; a drying vehicle position 105 is arranged in the heat preservation room 100 at a position corresponding to the circulating fan 102; and a dehumidification system 104 is arranged at the top end of the heat preservation room 100. The plurality of circulating fans are arranged transversely in the drying room, one circulating fan 102 corresponds to one multi-layer drying vehicle of the semi-dry light fiber board, the hot air circulation distance is shortened, the hot air can flow through the fiber board more quickly and directly, and the heat loss of the airflow in the transmission process is reduced, that is, the temperature difference of each semi-dry light fiber board in the whole vehicle is very small. The drying process in step S9, the drying temperature of the drying room is automatically controlled by PLC, the drying of the board is automatically operated according to the preset drying process curve in the initial drying stage, the middle drying stage and the later drying stage, the drying process is accurately controlled, and the balance and stability of the board drying are ensured. In the initial stage of drying, the moisture evaporation amount is large due to the high water content of the plate, and the drying and moisture removal amount is large, so the drying temperature should not be too high to avoid the rapid evaporation and drying of the surface water of the semi-dry light fiberboard, forming a dense "hard shell" that hinders the diffusion of internal moisture through the pores, making it difficult to remove internal moisture, resulting in the phenomenon of dry outside and wet inside. In severe cases, due to the large difference between the surface and internal moisture content, strong internal stress may occur, the surface shrinks due to water loss, and the interior is still in a high moisture state. This stress difference may cause the fiberboard to bend, warp, or even crack on the surface or inside; In the middle stage of drying, the evaporation amount is reduced, and the drying and moisture removal amount is reduced accordingly, so the drying temperature can be appropriately increased. In the late stage of drying, the evaporation amount is further reduced, and the moisture removal amount is further reduced, so the drying temperature should be reduced to avoid quality changes or even cracking of the plate due to high-temperature baking of the plate surface, and to balance the drying performance of the plate. Example Two

[0021] Please refer to Figure 1 The present application provides a technical solution: a light fiberboard manufacturing method based on semi-dry process, which includes the following steps compared to Example One: Step S1, chip cutting process: wood is cut into wood chips with a side length of 3cm to 6cm by a chip cutting machine; Step S2, screening process: the wood chips after cutting are screened by a vibrating screen, and the wood chips that meet the specifications are subjected to the next process, and the wood chips that exceed the specifications are subjected to re-chipping; Step S3, hot grinding process: the screened wood chips are preheated and cooked by a hot grinder, and fibers are obtained by mechanical separation; the hot grinding process temperature is 165℃, the hot grinding pressure is 0.85MPa, and the hot grinding time is 4min; the fibers obtained by mechanical separation are subjected to a cooling process, i.e. the hot ground fibers and high-temperature steam are separated by a cyclone separator, the high-temperature steam is discharged upward, and the fibers are cooled downward and enter the downstream pulp pool; Step S4, dilution process: the fibers in the pulp pool are diluted and stirred with water to produce fiber slurry, and the fiber concentration of the fiber slurry is 27%; Step S5, laying process: the obtained fiber slurry is laid into a continuous board blank by a long net forming machine, and the water content of the board blank is controlled at 90%; Step S6, dehydration process: the continuous board blank is dehydrated by a dehydration device combining vacuum dehydration and mechanical dehydration, and the water content of the dehydrated continuous board blank is controlled at 50%; the waste water discharged in this process is transported to the pulp pool of step S4, realizing the internal circulation of production waste water; Step S7, a first sawing process: the continuous board blank is divided into one by one fiberboard blank; the sawed fiberboard blank is subjected to a board blank inspection process, the qualified fiberboard blank enters the next process, and the unqualified fiberboard blank is transported to the pulp tank of step S4; Step S8, a hot pressing process: the fiberboard blank is pressed and heated by a hot press to produce a semi-dry lightweight board; the pressure intensity of the fiberboard blank is 0.57 MPa, the hot pressing time is 15 min, the hot pressing temperature is 175℃, and the moisture content of the semi-dry lightweight board after hot pressing is controlled to be 20%; Step S9, a drying process: the semi-dry lightweight board is subjected to drying treatment by a drying room, the drying temperature is 80℃, the drying time is 2.5h, and the moisture content of the finished lightweight fiberboard after drying is controlled to be 10%; Step S10, a second sawing process: the dried lightweight fiberboard is sawed according to the required specifications; the sawed lightweight fiberboard is subjected to a board inspection process, and the unqualified lightweight fiberboard is crushed and finely ground into fibers by a board crushing machine and a refiner and then transported to the pulp tank of step S4. Example three

[0022] Please refer to Figure 1 The application also provides a technical solution: a lightweight fiberboard manufacturing method based on a semi-dry process, which comprises the following steps in comparison with example one: Step S1, a slicing process: wood is sliced into wood chips with a side length of 3cm to 6cm by a slicing machine; Step S2, a screening process: the sliced wood chips are screened by a vibrating screen, the wood chips meeting the specifications are subjected to the next process, and the wood chips larger than the specifications are subjected to slicing treatment again; Step S3, a hot grinding process: the screened wood chips are preheated and cooked by a hot grinder to obtain fibers by mechanical separation; the hot grinding temperature is 180℃, the hot grinding pressure is 0.9MPa, and the hot grinding time is 5min; the fibers obtained by mechanical separation are subjected to a cooling process, that is, the fibers and high-temperature steam obtained by hot grinding are separated by a cyclone separator, the high-temperature steam is discharged upward, and the fibers are cooled and dropped into a downstream pulp tank; Step S4, a dilution process: the fibers in the pulp tank are diluted and stirred by adding water to prepare fiber slurry, and the fiber concentration of the fiber slurry is 30%; Step S5, a laying process: the obtained fiber slurry is laid into a continuous board blank by a long net forming machine, and the moisture content of the board blank is controlled to be 97%; Step S6, a dehydration process: the continuous board blank is dehydrated by a dehydration equipment combining vacuum dehydration and mechanical dehydration, and the moisture content of the dehydrated continuous board blank is controlled to be 60%; the waste water discharged in this process is transported to the pulp tank of step S4 to realize internal circulation of production waste water; Step S7, a first sawing process: the continuous board blank is divided into one by one fiber board blank; the sawed fiber board blank is subjected to a board blank inspection process, and the qualified fiber board blank enters the next process, and the unqualified fiber board blank is transported to the pulp tank of step S4; Step S8, a hot pressing process: the fiber board blank is subjected to pressure and heating by a hot press to produce a semi-dry lightweight board; the pressure intensity of the fiber board blank is 0.70 MPa, the hot pressing time is 20 min, the hot pressing temperature is 200℃, and the moisture content of the semi-dry lightweight board after hot pressing is controlled at 30%; Step S9, a drying process: the semi-dry lightweight board is subjected to drying treatment by a drying room, the drying temperature is 95℃, the drying time is 3h, and the moisture content of the finished lightweight fiber board after drying is controlled at 15%; Step S10, a second sawing process: the dried lightweight fiber board is sawed according to the required specifications; the sawed lightweight fiber board is subjected to a board inspection process, and the unqualified lightweight fiber board is crushed and finely ground into fibers by a board crushing machine and a fine grinding machine and then transported to the pulp tank of step S4.

[0023] Comparative Example 1: compared with the lightweight fiber board manufacturing method of the present application, the pressure intensity of the fiber board blank in the hot pressing process is 1.62 MPa, the hot pressing time is 14 min, and the hot pressing temperature is 182℃; Comparative Example 2: compared with the lightweight fiber board manufacturing method of the present application, the pressure intensity of the fiber board blank in the hot pressing process is 0.25 MPa, the hot pressing time is 18 min, and the hot pressing temperature is 161℃; Comparative Example 3: compared with the lightweight fiber board manufacturing method of the present application, the pressure intensity of the fiber board blank in the hot pressing process is 0.66 MPa, the hot pressing time is 10 min, and the hot pressing temperature is 280℃; Comparative Example 4: compared with the lightweight fiber board manufacturing method of the present application, the pressure intensity of the fiber board blank in the hot pressing process is 0.51 MPa, the hot pressing time is 20 min, and the hot pressing temperature is 120℃; Comparative Example 5: compared with the lightweight fiber board manufacturing method of the present application, the pressure intensity of the fiber board blank in the hot pressing process is 0.48 MPa, the hot pressing time is 30 min, and the hot pressing temperature is 172℃; Comparative Example 6: compared with the lightweight fiber board manufacturing method of the present application, the pressure intensity of the fiber board blank in the hot pressing process is 0.68 MPa, the hot pressing time is 3 min, and the hot pressing temperature is 195℃; Experimental verification: the lightweight fiber boards produced by the manufacturing methods of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6 are compared and analyzed respectively; the test data is shown in Table 1: Table 1: Comparative experimental data of lightweight fiber boards produced by different hot pressing processes

[0024] As can be seen from Table 1: The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Example 1, Example 2 and Example 3 has the performance indexes of water content, static bending strength and water absorption thickness expansion rate meeting the national industry standard; no glue is needed, the production cost is low, no formaldehyde is released, and the environmental protection performance is excellent; the density is low, the quality is light, the transportation cost is low; the sound absorption and noise reduction function is good, especially the sound absorption effect on high frequency noise is better; the heat insulation performance is good; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 1 has a high hot-pressing pressure, the density of the semi-dry board produced is large, and the "light-weight" property is lost, that is, the produced product is not a light-weight fiberboard; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 2 has a small hot-pressing pressure, and the board blank is easily cracked under the influence of temperature, so it cannot be pressed into a semi-dry light-weight fiberboard; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 3 has a high hot-pressing temperature, a thick solidification layer is formed on the surface of the semi-dry light-weight fiberboard, the water in the middle cannot be discharged, and the light-weight fiberboard is layered; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 4 has a low hot-pressing temperature, the semi-dry light-weight fiberboard has a high water content, cannot form internal bonding strength, and has a soft texture and cannot be lifted; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 5 has a long hot-pressing time, and the semi-dry light-weight fiberboard produced is prone to carbonization and spontaneous combustion, which easily causes fire; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 6 has a short hot-pressing time, and the semi-dry light-weight fiberboard is not enough to be pressed into a shape; Comparative Example 7 and the light-weight fiberboard manufacturing method of the present application are compared, in the paving process, the water content of the continuous board blank is controlled to be 62.37%; in the dehydration process, the water content of the continuous board blank after dehydration is controlled to be 43.22%; in the hot-pressing process, the water content of the semi-dry light-weight board after hot-pressing is controlled to be 26.44%; Comparative Example 8 and the light-weight fiberboard manufacturing method of the present application are compared, in the paving process, the water content of the continuous board blank is controlled to be 82.65%; in the dehydration process, the water content of the continuous board blank after dehydration is controlled to be 78.77%; Comparative Example 9 and the light-weight fiberboard manufacturing method of the present application are compared, in the paving process, the water content of the continuous board blank is controlled to be 96.31%; in the dehydration process, the water content of the continuous board blank after dehydration is controlled to be 30.22%; Compared with the manufacturing method of the light fiberboard of the present application, the moisture content of the continuous mat laid in the laying process of Comparative Example 10 is controlled at 88.36%; the moisture content of the continuous mat after dehydration in the dehydration process is controlled at 57.32%; and the moisture content of the semi-dry light fiberboard after hot pressing in the hot pressing process is controlled at 42.34%; Compared with the manufacturing method of the light fiberboard of the present application, the moisture content of the continuous mat laid in the laying process of Comparative Example 11 is controlled at 91.72%; the moisture content of the continuous mat after dehydration in the dehydration process is controlled at 55.38%; and the moisture content of the semi-dry light fiberboard after hot pressing in the hot pressing process is controlled at 12.77%; Experimental verification: the light fiberboards produced by the manufacturing methods of Example 1, Example 2, Example 3, Comparative Example 7, Comparative Example 8, Comparative Example 9, Comparative Example 10 and Comparative Example 11 are compared and analyzed respectively; the test data are shown in Table 2: Table 2 Comparison of moisture contents of mats and semi-dry light fiberboards after different processing processes

[0025] As can be seen from Table 2: The light fiberboards produced by the manufacturing methods of Example 1, Example 2 and Example 3 have qualified surface quality and performance indexes meeting the national industry standards; The light fiberboard produced by the manufacturing method of Comparative Example 7 has poor fiber isotropy in the laid continuous mat due to the too low moisture content of the laid continuous mat in the laying process, which directly affects the physical properties of the semi-dry light fiberboard after hot pressing; The light fiberboard produced by the manufacturing method of Comparative Example 8 is prone to mat burst in the subsequent hot pressing process due to the too high moisture content of the continuous mat after dehydration in the dehydration process; The light fiberboard produced by the manufacturing method of Comparative Example 9 is prone to fracture of the mat after dehydration due to the too low moisture content of the continuous mat after dehydration, which cannot form a qualified mat and needs to be recycled and treated by a slurry tank; The light fiberboard produced by the manufacturing method of Comparative Example 10 has too high moisture content of the semi-dry light fiberboard after hot pressing, which cannot form internal bonding strength and has soft texture and cannot be lifted up; The light-weight fiberboard produced by the light-weight fiberboard manufacturing method of Comparative Example 11 is prone to spontaneous combustion in subsequent processes due to the over-drying of the semi-dry light-weight fiberboard after hot pressing, because the moisture content of the semi-dry light-weight fiberboard after hot pressing is too low; While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences and modifications and not limitations of the scope of the application, which is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a lightweight fiberboard based on a semi-dry process, characterized in that The following steps are involved: Step S1, chipping process: chipping the wood into wood chips that meet the specifications through a chipper; Step S2, screening process: The chipped wood chips are screened using a vibrating screen. The wood chips that meet the specifications will proceed to the next process, and the wood chips that are larger than the specifications will be chipped again; Step S3, hot grinding process: using a hot grinder to preheat and cook the screened wood chips, mechanically separate the fibers and send them to the downstream pulp tank; Step S4, dilution process: adding water to dilute and stir the fibers in the pulp pool to form fiber slurry; Step S5, paving process: the obtained fiber slurry is paved into a continuous slab through a Fourdrinier forming machine, and the moisture content of the slab is controlled at 80% to 97%; Step S6, dehydration process: using a dehydration device that combines vacuum dehydration and mechanical dehydration to dehydrate the continuous slab, and the moisture content of the dehydrated continuous slab is controlled at 40% to 60%; Step S7, primary sawing process: dividing the continuous slab into fiber slabs one by one; Step S8, hot pressing process: the fiberboard is pressurized and heated by a hot press to form a semi-dried lightweight board; the pressure on the fiberboard is 0.44MPa to 0.70MPa, the hot pressing time is 10min to 20min, the hot pressing temperature is 150°C to 200°C, and the moisture content of the semi-dried lightweight board after hot pressing is controlled at 15% to 30%; Step S9, drying process: drying the semi-dried lightweight board in a drying room at a drying temperature of 65°C to 95°C for 2 hours to 3 hours to ensure that the moisture content of the finished lightweight fiberboard after drying is controlled within 5% to 15%; Step S10, secondary sawing process: sawing the dried lightweight fiberboard according to the required specifications.

2. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: The side length of the wood chips cut in step S1 is 3 cm to 6 cm.

3. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: In step S3, the temperature of the hot grinding process is 150° C. to 180° C., the hot grinding pressure is 0.8 MPa to 0.9 MPa, and the hot grinding time is 3 min to 5 min.

4. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: After step S3, a cooling process is performed, in which the fibers and high-temperature steam produced by hot grinding are separated by a cyclone separator, the high-temperature steam rises and is discharged, and the fibers are cooled and flow into the downstream pulp pool.

5. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: The fiber concentration of the fiber slurry in step S5 is 25% to 30%.

6. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: The wastewater removed in step S6 is transported to the pulp pool in step S4 to achieve internal circulation of production wastewater.

7. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: After step S7, a slab inspection process is performed: the sawn fiber slab is inspected, qualified fiber slabs enter the next process, and unqualified fiber slabs are conveyed to the pulp pool of step S4.

8. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: After step S10, a board inspection process is performed, and unqualified lightweight fiberboards are crushed and finely ground into fibers using a board crusher and a fine grinder, and then transported to the pulp pool in step S4.

9. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: The dewatering equipment combining vacuum dehydration and mechanical dehydration described in step S6 includes a frame, on which a slab conveying roller, a vacuum dehydrator, a pre-pressing dehydration mechanism, a pressure-keeping dehydration mechanism and a pressing dehydration mechanism are sequentially provided; the pre-pressing dehydration mechanism includes a lower pre-pressing frame fixedly provided on the frame, an upper pre-pressing frame provided on the frame above the lower pre-pressing frame, and a plurality of pre-pressing rollers for pre-pressing and dehydrating the slab are provided on the lower pre-pressing frame and the upper pre-pressing frame; the pressure-keeping dewatering mechanism includes a lower pressure-keeping frame fixedly provided on the frame, an upper pressure-keeping frame provided on the frame above the corresponding lower pressure-keeping frame, and a plurality of pressure-keeping rollers for pressure-keeping and dehydrating the slab are provided on the upper pressure-keeping frame and the lower pressure-keeping frame; the pressing dewatering mechanism includes a lower pressing roller provided on the frame, and an upper pressing roller provided on the frame above the corresponding lower pressing roller; the pre-pressing roller on the upper pre-pressing frame, the pressure-keeping roller on the upper pressure-keeping frame and the upper pressing roller The worm gear is fixed to the upper and lower pre-pressing frames, and the upper and lower pressing rollers are connected to each other through hinged joints, and the upper and lower pressing rollers are connected ...

10. The method for manufacturing a lightweight fiberboard based on a semi-dry process according to claim 1, characterized in that: The drying room described in step S9 includes a heat preservation room, and a plurality of heating sources are arranged horizontally on one side of the length direction of the heat preservation room, and a circulation fan is provided inside the heating source; an air uniformity plate is vertically provided on the inner side of the circulation fan on the bottom plate of the heat preservation room, and air holes are evenly opened on the air uniformity plate, and the height of the air uniformity plate is lower than the height of the heat preservation room, and a circulation partition is horizontally provided on the top of the air uniformity plate, and a flow gap is left between the circulation partition and the two side walls of the heat preservation room in the length direction; drying parking spaces are provided at the positions corresponding to the circulation fans in the heat preservation room; and a dehumidification system is provided on the top of the heat preservation room; In the drying process described in step S9, the drying of the board is automatically operated according to the preset drying process curves in the early stage of drying, the middle stage of drying and the late stage of drying. In the early stage of drying, due to the high moisture content of the board, the water evaporation amount is large, the drying dehumidification amount is large, and the drying temperature cannot be too high; in the middle stage of drying, the evaporation amount decreases, and the drying dehumidification amount is reduced accordingly, and the drying temperature can be appropriately increased; in the late stage of drying, the evaporation amount further decreases, and the dehumidification amount is reduced again, and the drying temperature should be lowered.

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