Shaving board capable of being routed and milled and preparation method thereof

Abstract

The invention discloses a shaving board capable of being routed and milled and a preparation method thereof, and relates to the technical field of shaving board preparation. The shaving board capable of being routed and milled comprises an upper surface layer, a core layer and a lower surface layer, the shaving board is mainly made of a mixture of wood shavings and sawdust, and the sawdust accounts for 10-20% of the total weight of the mixture; in the shaving board, the weight ratio of the surface layer material is 40-50%, and the weight ratio of the core layer material is 50-60%; the size of the surface layer material is 0.2-0.9 mm, and the screening value is greater than or equal to 70; the size of the core layer material is gt; and the screening value is greater than or equal to 85. The sawdust and the wood chips are mainly used as raw materials, and the problems that an existing shaving board is soft, low in surface smoothness, poor in plastic absorption performance and incapable of being used for routing machining are solved by optimizing the preparation process. The prepared shaving board is uniform in structure, fine and dense in texture and high in surface smoothness, fluffing and cracking are avoided when the surface of the shaving board is routed, and the shaving board can be used for engraving and routing.

Description

Technical Field

[0001] The invention relates to the technical field of particleboard preparation, and in particular to a millable particleboard and a preparation method thereof. Background Art

[0002] Particleboard is a type of man-made board made by processing wood or non-wood plant fiber raw materials into shavings or scraps, applying adhesives and other additives, and hot pressing after the embryos are formed. Particleboard has a wide range of raw materials, and the product has the advantages of easy secondary processing and high environmental protection coefficient. It also has the characteristics of smooth surface, sound absorption and sound insulation, heat insulation, pollution resistance, aging resistance and low price, making it widely used in furniture manufacturing, packaging and decoration.

[0003] At present, the main type of wood-based panels that can be engraved and milled is fiberboard, which has a high density, fine texture, and symmetrical structure. It can be used for engraving and milling, but fiberboard is heavy, and there is a demand for light and engraved wood-based panels in the market. The existing wood-based panels cannot meet the requirements of furniture manufacturers. Therefore, how to make light particleboards that can be engraved and milled is an urgent problem to be solved.

[0004] In summary, the present invention mainly provides a millable particle board and a preparation method thereof. Summary of the invention

[0005] In view of the above shortcomings, the present invention provides a millable particle board and a preparation method thereof, which solves the problem that the existing particle board is relatively soft, has low surface finish, poor plasticity, and cannot be used for milling processing. The specific technical solution is as follows:

[0006] A millable particle board comprises an upper surface layer, a core layer and a lower surface layer. The raw material of the particle board is mainly a mixture of wood chips and sawdust, and the sawdust accounts for 10-20% of the total weight of the mixture; in the particle board, the weight proportion of the surface layer material is 40-50%, and the weight proportion of the core layer material is 50-60%; the size of the surface layer material is 0.2mm-0.9mm, and the screening value is ≥70; the size of the core layer material is>0.9mm, and the screening value is ≥85.

[0007] The present invention also provides a method for preparing the above-mentioned millable particle board, comprising the following process steps:

[0008] (1) Flaking: Flaking wood chips into shavings by a ring flaker; the wood chips are wood chips cut from branch wood and / or veneer sheets;

[0009] (2) Mixing wood shavings with sawdust: Mixing wood shavings with sawdust in a certain proportion to obtain a mixture;

[0010] (3) Drying: drying the mixed material to obtain a dry mixed material;

[0011] (4) Screening: Screening the dry mixed material to obtain a surface layer material and a core layer material;

[0012] (5) Applying glue and additives: adding glue and additives to the surface layer material and the core layer material respectively, and adjusting the moisture content of the materials to obtain a surface layer mixture and a core layer mixture;

[0013] (6) Paving and pre-pressing: first, the surface layer mixture and the core layer mixture are paved into a flat slab by a gradual paving method, and then pre-pressed into shape by a pre-pressing machine;

[0014] (7) Hot pressing: A continuous flat press machine is used for multi-step temperature-controlled gradient hot pressing. After hot pressing, the thickness is 18.35-18.45 mm and the density is 650-660 kg / m 3 plain board;

[0015] (8) Sanding and sawing: The plain board is cooled, sanded with a 150-mesh sanding belt, and then cross-sawing is performed to obtain the millable particle board.

[0016] Furthermore, in step (1), the blade extension of the flaker is 0.9-1.0 mm, and the blade door clearance is 2.0-2.5 mm.

[0017] Furthermore, in step (3), the parameters of the drying treatment are: furnace temperature is 600-900°C; press heat transfer oil temperature is ≤275°C; drying roller inlet temperature is ≤300°C, outlet temperature is 105-125°C; moisture content after drying is 1.5-4.0%.

[0018] Furthermore, in step (5), the amount of glue applied to the surface material is 45-48 kg / m 3 , the application amount of waterproofing agent is 2-2.2kg / m 3 ; The amount of glue applied to the core material is 42-43kg / m 3 , MDI application amount is 3.3-3.5kg / m 3 , the application amount of waterproofing agent is 3.8-3.95kg / m 3 , the curing agent application amount is 1.8-2.0kg / m 3 ; The glue is one or more of isocyanate, melamine-modified urea-formaldehyde resin, and soybean meal glue resin.

[0019] Furthermore, in step (5), after applying the glue and the additive, 0-3.5% urea water is added to the surface layer material to adjust the moisture content of the surface layer material to 8-9%, and 0-1% urea water is added to the core layer material to adjust the moisture content of the core layer material to 5-6%, thereby obtaining a surface layer mixture and a core layer mixture that can be paved.

[0020] Furthermore, in step (6), the gradient paving method is: first paving the surface layer mixture, then paving the core layer mixture, and finally paving the surface layer mixture. The specific paving steps are:

[0021] S1: Lay the lower surface mixture: First, the lower surface mixture is screened by the surface paving fan, and the lightest material is recovered by the dovetail groove recovery fan. The wind direction is set opposite to the running direction of the paving line conveyor belt. The lighter material is blown to the front end of the paving line and falls naturally by gravity. The heavier material cannot be blown to the front end and falls naturally due to gravity. As the paving line runs, the wind direction is opposite to the running direction of the paving line. The lighter and smaller surface materials are blown to the front end and fall on the paving line first. The heavier the mixture, the later it will fall freely onto the paving line, so that the lower surface layer is paved gradually from bottom to top from light to heavy and from small to large.

[0022] S2: Spread the core layer mixture evenly on the lower surface mixture through the paving head;

[0023] S3: Lay the upper surface mixture: follow the paving method of the lower surface mixture, but set the wind direction to be the same as the running direction of the paving line conveyor belt. The heavier and larger surface materials will fall onto the core mixture first. Due to the effect of wind, the lighter mixture will fall freely onto the paving line later, making the upper surface layer paved gradually from light to heavy and from small to large from top to bottom.

[0024] Furthermore, in step (6), the pre-pressing pressure is 10-30%.

[0025] Furthermore, in step (7), the hot pressing speed is 250-350 mm / s, and the temperature distribution of the continuous flat press is divided into five zones, and the temperature of each zone is: zone 1 235-250°C, zone 2 235-255°C, zone 3 235-255°C, zone 4 230-253°C, zone 5 190-210°C.

[0026] Furthermore, in step (8), the sanding thickness is 17.70-17.90 mm.

[0027] The particle board of the present invention can be processed by engraving and milling on the surface.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention mainly uses wood chaff and wood chips as raw materials, and solves the problem that the existing particleboard is relatively soft, has low surface finish, poor plasticity, and cannot be used for milling by optimizing the preparation process. The particleboard prepared by the present invention has a symmetrical structure, fine texture, dense texture, high surface finish, and no fuzz or cracking on its surface during milling, and can be used for carving and milling.

[0030] 2. The present invention sets the proportion of wood husk to 5-20%, the proportion of surface material to 40-50%, the proportion of core material to 50-60%, the size of surface material to 0.2mm-0.9mm, the screening value ≥70, the size of core material to >0.9mm, the screening value ≥85, which can meet the physical and mechanical properties of particleboard while ensuring a good milling effect. At the same time, the present invention adopts a gradual paving method, which can achieve uniform paving of materials and make the upper and lower surface layers have a good milling effect.

[0031] 3. The raw materials used in the present invention are low in price, the production process is simple, the production efficiency is high, it has good economic benefits, and it is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below.

[0033] Figure 1 This is a physical picture of the product of the present invention;

[0034] Figure 2 This is a milling effect diagram of the product of the present invention. DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0036] Example 1

[0037] The present embodiment provides a millable particle board, comprising an upper surface layer, a core layer and a lower surface layer. The raw material of the particle board is mainly a mixture of wood chips and sawdust. The preparation method thereof comprises the following process steps:

[0038] (1) Flaking: The wood chips are shaved into shavings by a ring-type flaker; the blade extension of the flaker is 0.9 mm, and the blade clearance is 2.0 mm; the wood chips are wood chips cut from branches and veneer sheets.

[0039] (2) Mixing wood shavings and sawdust: Mix wood shavings and sawdust in a ratio of 1:9 to obtain a mixture.

[0040] (3) Drying: The mixed material is dried to obtain a dry mixed material; the parameters of the drying process are: furnace temperature is 600°C; press heat transfer oil temperature is 270°C; drying roller inlet temperature is 250°C, outlet temperature is 105°C; moisture content after drying is 4.0%.

[0041] (4) Screening: The dry mixture is screened to obtain a surface material and a core material; the size of the surface material is 0.2 mm, and the screening value is 70; the size of the core material is 1 mm, and the screening value is 85; the weight proportion of the surface material in the particleboard is 40%, and the weight proportion of the core material is 60%.

[0042] (5) applying glue and additives: adding glue and additives to the surface layer material and the core layer material respectively, adjusting the moisture content of the surface layer material to 8% by the glue and additives, adding 0.2% urea water to the core layer material, adjusting the moisture content of the core layer material to 6% by the glue, additives and urea water, to obtain a surface layer mixture and a core layer mixture;

[0043] The amount of glue applied to the surface material is 45kg / m 3 , the amount of waterproofing agent applied is 2kg / m 3 ; The amount of glue applied to the core material is 42kg / m 3 , MDI application amount is 3.3kg / m 3 , the amount of waterproofing agent applied is 3.8kg / m 3 , the curing agent application amount is 1.8kg / m 3 ; The glue is isocyanate.

[0044] (6) Paving pre-pressing: first, the surface layer mixture and the core layer mixture are paved into a flat slab by a gradual paving method, and then pre-pressed by a pre-pressing machine, and the pre-pressing machine pressure is 10%;

[0045] The gradient paving method is: first lay the surface mixture, then lay the core mixture, and finally lay the surface mixture. The specific paving steps are:

[0046] S1: Lay the lower surface mixture: First, the lower surface mixture is screened by the surface paving fan, and the lightest material is recovered by the dovetail groove recovery fan. The wind direction is set opposite to the running direction of the paving line conveyor belt. The lighter material is blown to the front end of the paving line and falls naturally by gravity. The heavier material cannot be blown to the front end and falls naturally due to gravity. As the paving line runs, the wind direction is opposite to the running direction of the paving line. The lighter and smaller surface materials are blown to the front end and fall on the paving line first. The heavier the mixture, the later it will fall freely onto the paving line, so that the lower surface layer is paved gradually from bottom to top from light to heavy and from small to large.

[0047] S2: Spread the core layer mixture evenly on the lower surface mixture through the paving head;

[0048] S3: Lay the upper surface mixture: follow the paving method of the lower surface mixture, but set the wind direction to be the same as the running direction of the paving line conveyor belt. The heavier and larger surface materials will fall onto the core mixture first. Due to the effect of wind, the lighter mixture will fall freely onto the paving line later, making the upper surface layer paved gradually from light to heavy and from small to large from top to bottom.

[0049] (7) Hot pressing: The hot pressing was carried out by a continuous flat hot press machine through multi-step temperature-controlled gradient hot pressing, the hot pressing speed was 250 mm / s, the temperature distribution of the continuous flat hot press machine was divided into five zones, and the temperature of each zone was: zone 1 235°C, zone 2 235°C, zone 3 235°C, zone 4 230°C, zone 5 190°C, and the thickness after hot pressing was 18.35 mm and the density was 650 kg / m 3 plain board.

[0050] (8) Sanding and sawing: The plain board is cooled, and sanded with a thickness of 17.70 mm using a 150-mesh sanding belt, and then cross-sawing is performed to obtain the millable particle board.

[0051] Example 2

[0052] In the present embodiment, the weight proportion of the surface material in the particleboard in step (4) is 50%, and the weight proportion of the core material is 50%. The other preparation methods are the same as those in embodiment 1.

[0053] Example 3

[0054] The present embodiment provides a millable particle board, comprising an upper surface layer, a core layer and a lower surface layer. The raw material of the particle board is mainly a mixture of wood chips and sawdust. The preparation method thereof comprises the following process steps:

[0055] (1) Flaking: The wood chips are shaved into shavings by a ring-type flaker; the blade extension of the flaker is 1.0 mm, and the blade clearance is 2.5 mm; the wood chips are wood chips cut from branches.

[0056] (2) Mixing wood shavings and sawdust: Mix wood shavings and sawdust in a ratio of 1.5:8.5 to obtain a mixture.

[0057] (3) Drying: The mixed material is dried to obtain a dry mixed material; the parameters of the drying process are: furnace temperature is 900°C; press heat transfer oil temperature is 260°C; drying roller inlet temperature is 200°C, outlet temperature is 125°C; moisture content after drying is 1.5%.

[0058] (4) Screening: The dry mixture is screened to obtain a surface material and a core material; the size of the surface material is 0.9 mm, and the screening value is 75; the size of the core material is 2 mm, and the screening value is 95; the weight proportion of the surface material in the particleboard is 40%, and the weight proportion of the core material is 60%.

[0059] (5) Applying glue and additives: After adding glue and additives to the surface layer material and the core layer material respectively, 3.5% urea water is added to the surface layer material, and the glue, additives and urea water are used to adjust the moisture content of the surface layer material to 9% and the moisture content of the core layer material to 5%, thereby obtaining a surface layer mixture and a core layer mixture;

[0060] The amount of glue applied to the surface material is 48kg / m 3 , the amount of waterproofing agent applied is 2.2kg / m 3 The amount of glue applied to the core material is 43kg / m 3 , MDI application amount is 3.5kg / m 3 , the amount of waterproofing agent applied is 3.95kg / m 3 , the curing agent application amount is 2.0kg / m 3 ; The glue is melamine modified urea-formaldehyde resin.

[0061] (6) Paving pre-pressing: first, the surface layer mixture and the core layer mixture are paved into a flat slab by a gradual paving method, and then pre-pressed by a pre-pressing machine, and the pre-pressing machine pressure is 30%;

[0062] The gradient paving method is: first lay the surface mixture, then lay the core mixture, and finally lay the surface mixture. The specific paving steps are:

[0063] S1: Lay the lower surface mixture: First, the lower surface mixture is screened by the surface paving fan, and the lightest material is recovered by the dovetail groove recovery fan. The wind direction is set opposite to the running direction of the paving line conveyor belt. The lighter material is blown to the front end of the paving line and falls naturally by gravity. The heavier material cannot be blown to the front end and falls naturally due to gravity. As the paving line runs, the wind direction is opposite to the running direction of the paving line. The lighter and smaller surface materials are blown to the front end and fall on the paving line first. The heavier the mixture, the later it will fall freely onto the paving line, so that the lower surface layer is paved gradually from bottom to top from light to heavy and from small to large.

[0064] S2: Spread the core layer mixture evenly on the lower surface mixture through the paving head;

[0065] S3: Lay the upper surface mixture: follow the paving method of the lower surface mixture, but set the wind direction to be the same as the running direction of the paving line conveyor belt. The heavier and larger surface materials will fall onto the core mixture first. Due to the effect of wind, the lighter mixture will fall freely onto the paving line later, making the upper surface layer paved gradually from light to heavy and from small to large from top to bottom.

[0066] (7) Hot pressing: The hot pressing was carried out by a continuous flat hot press machine with multi-step temperature-controlled gradient hot pressing. The hot pressing speed was 350 mm / s. The temperature distribution of the continuous flat hot press machine was divided into five zones. The temperature of each zone was: 250°C in zone 1, 255°C in zone 2, 255°C in zone 3, 253°C in zone 4, and 210°C in zone 5. After hot pressing, the obtained thickness was 18.45 mm and the density was 660 kg / m 3 plain board.

[0067] (8) Sanding and sawing: The plain board is cooled, and sanded with a thickness of 17.90 mm using a 150-mesh sanding belt, and then cross-sawing is performed to obtain the millable particle board.

[0068] Example 4

[0069] In the present embodiment, the weight proportion of the surface material in the particleboard in step (4) is 50%, and the weight proportion of the core material is 50%. The other preparation methods are the same as those in Example 3.

[0070] Example 5

[0071] The present embodiment provides a millable particle board, comprising an upper surface layer, a core layer and a lower surface layer. The raw material of the particle board is mainly a mixture of wood chips and sawdust. The preparation method thereof comprises the following process steps:

[0072] (1) Flaking: The wood chips are shaved into wood chips by a ring-type flaker; the blade extension of the flaker is 0.95 mm, and the blade clearance is 2.2 mm; the wood chips are wood chips cut from branches and veneer sheets.

[0073] (2) Mixing wood shavings and sawdust: Mix wood shavings and sawdust in a ratio of 2:8 to obtain a mixture.

[0074] (3) Drying: The mixed material is dried to obtain a dry mixed material; the parameters of the drying process are: furnace temperature is 800°C; press heat transfer oil temperature is 250°C; drying roller inlet temperature is 250°C, outlet temperature is 115°C; moisture content after drying is 3%.

[0075] (4) Screening: The dry mixture is screened to obtain a surface material and a core material; the size of the surface material is 0.5 mm, and the screening value is 80; the size of the core material is 1.5 mm, and the screening value is 90; the weight proportion of the surface material in the particleboard is 40%, and the weight proportion of the core material is 60%.

[0076] (5) Applying glue and additives: After adding glue and additives to the surface layer material and the core layer material, respectively, adding 2% urea water to the surface layer material to adjust the moisture content of the surface layer material to 8.5%, and adding 0.8% urea water to the core layer material to adjust the moisture content of the core layer material to 5.5%, thereby obtaining a surface layer mixture and a core layer mixture;

[0077] The amount of glue applied to the surface material is 46kg / m 3 , the amount of waterproofing agent applied is 2.1kg / m 3 The amount of glue applied to the core material is 42.5kg / m 3 , MDI application amount is 3.4kg / m 3 , the amount of waterproofing agent applied is 3.85kg / m 3 , the curing agent application amount is 1.85kg / m 3 ; The glue is soybean meal glue resin.

[0078] (6) Paving pre-pressing: first, the surface layer mixture and the core layer mixture are paved into a flat slab by a gradual paving method, and then pre-pressed by a pre-pressing machine, and the pre-pressing machine pressure is 20%;

[0079] The gradient paving method is: first lay the surface mixture, then lay the core mixture, and finally lay the surface mixture. The specific paving steps are:

[0080] S1: Lay the lower surface mixture: First, the lower surface mixture is screened by the surface paving fan, and the lightest material is recovered by the dovetail groove recovery fan. The wind direction is set opposite to the running direction of the paving line conveyor belt. The lighter material is blown to the front end of the paving line and falls naturally by gravity. The heavier material cannot be blown to the front end and falls naturally due to gravity. As the paving line runs, the wind direction is opposite to the running direction of the paving line. The lighter and smaller surface materials are blown to the front end and fall on the paving line first. The heavier the mixture, the later it will fall freely onto the paving line, so that the lower surface layer is paved gradually from bottom to top from light to heavy and from small to large.

[0081] S2: Spread the core layer mixture evenly on the lower surface mixture through the paving head;

[0082] S3: Lay the upper surface mixture: follow the paving method of the lower surface mixture, but set the wind direction to be the same as the running direction of the paving line conveyor belt. The heavier and larger surface materials will fall onto the core mixture first. Due to the effect of wind, the lighter mixture will fall freely onto the paving line later, making the upper surface layer paved gradually from light to heavy and from small to large from top to bottom.

[0083] (7) Hot pressing: The hot pressing was carried out by a continuous flat hot press machine through multi-step temperature-controlled gradient hot pressing. The hot pressing speed was 300 mm / s. The temperature distribution of the continuous flat hot press machine was divided into five zones. The temperature of each zone was: 240°C in zone 1, 245°C in zone 2, 245°C in zone 3, 243°C in zone 4, and 200°C in zone 5. After hot pressing, the thickness was 18.40 mm and the density was 655 kg / m 3 plain board.

[0084] (8) Sanding and sawing: The plain board is cooled, and sanded with a thickness of 17.80 mm using a 150-mesh sanding belt, and then cross-sawing is performed to obtain the millable particle board.

[0085] Example 6

[0086] In the present embodiment, the weight proportion of the surface material in the particleboard in step (4) is 50%, and the weight proportion of the core material is 50%. The other preparation methods are the same as those in Example 5.

[0087] The properties of the particleboards prepared in Examples 1 to 6 were tested, and the results are shown in Table 1:

[0088] Table 1 Properties of particleboards prepared in various embodiments

[0089]

[0090] The above table shows that the particleboard prepared by the present invention has good physical and mechanical properties. Figure 1 The figure shows that the particleboard of the present invention has a symmetrical structure, fine texture, denseness and high surface finish. Figure 2 After milling the upper surface, it was found that the edge was smooth and had no cracks.

[0091] Comparative Example 1

[0092] In step (2) of this comparative example, wood shavings are mixed with wood shavings in a ratio of 0.5:9.5 to obtain a mixture. The other steps are the same as those in Example 6.

[0093] The properties of the particleboards obtained in Example 6 and Comparative Example 1 were tested, and the results are shown in Table 2:

[0094] Table 2 Performance comparison of particleboards obtained in the embodiments and comparative examples

[0095]

[0096] The above table shows that the present invention sets the wood shavings ratio to 10-20% to meet the physical and mechanical properties.

[0097] Comparative Example 2

[0098] In step (1) of this comparative example, the blade extension of the flaker is 1.5 mm. The other steps are the same as those in Example 6.

[0099] Comparative Example 3

[0100] In this comparative example, the blade extension of the flaker in step (1) is 2 mm. The other steps are the same as those in Example 6.

[0101] Comparative Example 4

[0102] In step (1) of this comparative example, the blade extension of the flaker is 0.8 mm. The other steps are the same as those in Example 6.

[0103] The properties of the particleboards obtained in Example 6, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were tested, and the results are shown in Table 3:

[0104] Table 3 Performance comparison of particleboards prepared in the embodiments and comparative examples

[0105]

[0106]

[0107] The above table shows that the present invention sets the tool extension amount to 0.9-1.0 mm, which basically meets the physical and mechanical properties and can ensure a good milling effect.

[0108] Comparative Example 5

[0109] In this comparative example, step (4) screening: the size of the surface layer material is 1.0 mm (data outside the range of 0.2 mm-0.9 mm); the size of the core layer material is 0.8 mm (data outside the range of >0.9 mm). Other steps are the same as those in Example 6.

[0110] Comparative Example 6

[0111] In this comparative example, step (4) screening: the size of the surface layer material is 2.0 mm (data outside the range of 0.2 mm-0.9 mm); the size of the core layer material is 0.7 mm (data outside the range of >0.9 mm). Other steps are the same as those in Example 6.

[0112] The properties of the particleboards obtained in Example 6, Comparative Example 5 and Comparative Example 6 were tested, and the results are shown in Table 44:

[0113] Table 4 Performance comparison of particleboards obtained in the embodiments and comparative examples

[0114]

[0115] The above table shows that the present invention sets the size of the surface material to 0.2mm-0.9mm; the size of the core material to >0.9mm, which can basically meet the physical and mechanical properties while ensuring a good milling effect.

[0116] In summary, the present invention mainly uses wood chaff and wood chips as raw materials, and solves the problem that the existing particleboard is relatively soft, has low surface finish, poor plasticity, and cannot be used for milling processing by optimizing the preparation process. The particleboard prepared by the present invention has a symmetrical structure, fine texture, dense, and high surface finish. The surface will not fuzz or crack when milling, and can be used for carving and milling. The raw materials used in the present invention are low in price, the production process is simple, the production efficiency is high, it has good economic benefits, and it is easy to realize industrial production.

[0117] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A millable particle board, comprising an upper surface layer, a core layer and a lower surface layer, characterized in that: The raw material of the particle board is mainly a mixture of wood chips and sawdust, and the sawdust accounts for 10-20% of the total weight of the mixture; in the particle board, the weight of the surface material accounts for 40-50%, and the weight of the core material accounts for 50-60%; the size of the surface material is 0.2mm-0.9mm, and the screening value is ≥70; the size of the core material is >0.9mm, and the screening value is ≥85.

2. A method for preparing a millable particle board according to claim 1, characterized in that: The process steps include: (1) Flaking: The wood chips are shaved into shavings by a flaker; (2) Mixing wood shavings with sawdust: Mixing wood shavings with sawdust in a certain proportion to obtain a mixture; (3) Drying: drying the mixed material to obtain a dry mixed material; (4) Screening: Screening the dry mixed material to obtain a surface layer material and a core layer material; (5) Applying glue and additives: adding glue and additives to the surface layer material and the core layer material respectively, and adjusting the moisture content of the materials to obtain a surface layer mixture and a core layer mixture; (6) Paving and pre-pressing: first, the surface layer mixture and the core layer mixture are paved into a flat slab by a gradual paving method, and then pre-pressed into shape by a pre-pressing machine; (7) Hot pressing: A continuous flat press machine is used for multi-step temperature-controlled gradient hot pressing. After hot pressing, the thickness is 18.35-18.45 mm and the density is 650-660 kg / m 3 plain board; (8) Sanding and sawing: The plain board is cooled, sanded with a sanding belt, and then sawed to obtain the millable particle board.

3. The method for preparing a millable particle board according to claim 2, characterized in that: In step (1), the blade extension of the flaker is 0.9-1.0 mm, and the blade door clearance is 2.0-2.5 mm.

4. The method for preparing a millable particle board according to claim 2, characterized in that: In step (3), the parameters of the drying treatment are: furnace temperature is 600-900°C; press heat transfer oil temperature is ≤275°C; drying roller inlet temperature is ≤300°C, outlet temperature is 105-125°C; moisture content after drying is 1.5-4.0%.

5. The method for preparing a millable particle board according to claim 2, characterized in that: In step (5), the amount of glue applied to the surface material is 45-48 kg / m 3 , the application amount of waterproofing agent is 2-2.2kg / m 3 ; The amount of glue applied to the core material is 42-43kg / m 3 , MDI application amount is 3.3-3.5kg / m 3 , the application amount of waterproofing agent is 3.8-3.95kg / m 3 , the curing agent application amount is 1.8-2.0kg / m 3 ; The glue is one or more of isocyanate, melamine-modified urea-formaldehyde resin, and soybean meal glue resin.

6. The method for preparing a millable particle board according to claim 2, characterized in that: In step (5), after applying the glue and the additives, 0-3.5% urea water is added to the surface material to adjust the moisture content of the surface material to 8-9%, and 0-1% urea water is added to the core material to adjust the moisture content of the core material to 5-6%, thereby obtaining a surface mixture and a core mixture that can be paved.

7. The method for preparing a millable particle board according to claim 2, characterized in that: In step (6), the gradient paving method is: first lay the surface mixture, then lay the core mixture, and finally lay the surface mixture. The specific paving steps are: S1: Lay the lower surface mixture: First, the lower surface mixture is screened by the surface paving fan, and the lightest material is recovered by the dovetail groove recovery fan. The wind direction is set opposite to the running direction of the paving line conveyor belt. The lighter material is blown to the front end of the paving line and falls naturally by gravity. The heavier material cannot be blown to the front end and falls naturally due to gravity. As the paving line runs, the wind direction is opposite to the running direction of the paving line. The lighter and smaller surface materials are blown to the front end and fall on the paving line first. The heavier the mixture, the later it will fall freely onto the paving line, so that the lower surface layer is paved gradually from bottom to top from light to heavy and from small to large. S2: Spread the core layer mixture evenly on the lower surface mixture through the paving head; S3: Lay the upper surface mixture: follow the paving method of the lower surface mixture, but set the wind direction to be the same as the running direction of the paving line conveyor belt. The heavier and larger surface materials will fall onto the core mixture first. Due to the effect of wind, the lighter mixture will fall freely onto the paving line later, making the upper surface layer paved gradually from light to heavy and from small to large from top to bottom.

8. The method for preparing a millable particle board according to claim 2, characterized in that: In step (6), the pre-pressing pressure is 10-30%.

9. The method for preparing a millable particle board according to claim 2, characterized in that: In step (7), the hot pressing speed is 250-350 mm / s, and the temperature distribution of the continuous flat press is divided into five zones, and the temperature of each zone is: zone 1 235-250°C, zone 2 235-255°C, zone 3 235-255°C, zone 4 230-253°C, zone 5 190-210°C.

10. The method for preparing a millable particle board according to claim 2, characterized in that: In step (8), the sanding thickness is 17.70-17.90 mm.

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