CN114274282B - A kind of cross-laminated wood joined by dowels and preparation method thereof - Google Patents

Abstract

The invention discloses an orthogonal glued lumber joined by wooden nails, comprising the orthogonal glued lumber, each layer of the orthogonal glued lumber is formed by assembling a plurality of laminates (3); The intersecting part of the laminates (3) is an overlapping unit (5), the wooden dowels (6) are staggered, the nailing point is located on the center line of the overlapping unit (5), and the wooden dowels (6) that are driven into the same level are one In the nail layer (7), the wooden nails (6) of the adjacent nail layers (7) are staggered from each other in the vertical direction, and the nailing angles (9) of the wooden nails (6) of the adjacent nail layers (7) are opposite. The invention also discloses a preparation method of the cross-laminated wood joined by wooden pegs. The present invention does not need to use any adhesive as a gluing medium, can effectively reduce the release of harmful gases such as formaldehyde, lighten the burden on the environment, and has high processing efficiency, and the nailing components are also convenient for post-processing and recycling.

Description

A kind of cross-laminated wood joined by dowels and preparation method thereof

technical field

The invention relates to an orthogonal glue-laminated wood joined by wooden pegs and a preparation method thereof, and belongs to the technical field of wood engineering material production technology innovation.

Background technique

Cross-laminated timber (CLT) is a factory prefabricated form of rectangular, straight and flat panels made of at least 3 layers of solid wood sawn timber or structural composite panels orthogonally assembled and pressed with structural adhesives. Engineered wood products. CLT can be used to construct middle and high-rise civil and non-civilian buildings. It can not only completely replace traditional reinforced concrete and brick-concrete structures, but also form a hybrid structure with reinforced concrete or other engineered wood products. It has the advantages of fast assembly and low noise, which is conducive to promoting the leap-forward development of on-site prefabricated wood structure buildings and contributing to a lower-carbon and more environmentally friendly sustainable urban development.

Most of the CLT wood used in residential buildings now uses cold-curing adhesives. The currently used adhesives mainly include one-component polyurethane adhesives, two-component polyurethane adhesives, polyvinyl acetate-isocyanate adhesives and Resorcinol formaldehyde resin adhesive. Most glues have poor heat resistance, strong acid resistance and strong alkali resistance, and are easily hydrolyzed under high temperature and high humidity to reduce the bonding strength, thereby reducing its service life; and during construction and use, it will release irritating toxic gases. To a certain extent, it harms people's health; the use of glue is not conducive to the recycling of CLT, and the large area of glue layer increases the difficulty of its disassembly, which not only increases construction waste, but also reduces the resource recovery rate. Therefore, it is particularly important to find a more environmentally friendly, efficient and convenient connection method.

my country has a history of using wooden nails in ancient buildings. In traditional wooden structures, wooden nails are used to strengthen the tenon-and-mortise structure, that is, the tenon-and-mortise joint and wooden nails need to be used together in traditional wooden structures to strengthen the structure. .

With the development of the industrial revolution, various metal nails, metal connectors and industrial glues continue to emerge, and traditional wooden nails gradually fade out of people's sight.

Based on the design concept of strong joints and weak components in modern wood structure buildings, joint connection is usually an important link in wood structure research. Pin-type metal connectors represented by nails, bolts, pins, etc. have been widely used in modern heavy wood structures due to their good toughness and safety and reliability. However, metal fasteners will inevitably loosen and rust over time (as shown in Figure 1), reducing the stability of the structure; and also form thermal bridges in the wood, reducing the indoor thermal insulation effect, etc. (Figure 2).

As the most environmentally friendly pin-type connector, wooden dowels have been around since ancient times. They have the advantages of light weight, strong compatibility, no need for pre-drilling, and high construction efficiency. Compared with dowel-type fasteners made of metal, dowels No hot and cold bridges are formed and no signs of corrosion are left in the wood.

However, traditional wood dowels are mainly made of hardwood or bamboo, and the traditional dowels are driven vertically, which often cause irreversible bending deformation when exposed to a humid environment, which is difficult to meet the requirements of large-sized components in heavy wood buildings. Connectivity and complex structural design needs.

At present, there is no report on the application of wooden nails as a connector to the connection of CLT, and there is no report on the application of CLT connected only by wooden nails in large-sized components of heavy wood buildings. The research results of the present invention can provide strong scientific support for the realization of this technology. As countries around the world pay more and more attention to the environment, wooden dowels will have broad application prospects in the context of green and low-carbon, healthy life, and building ecological civilization, and will help my country's green manufacturing, carbon reduction and carbon reduction "3060" goals to be realized as soon as possible .

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is that the present invention provides a cross-laminated wood joined by dowels. The cross-laminated wood has high bearing capacity, high stiffness and good ductility.

At the same time, the present invention provides a method for preparing cross-laminated wood joined by dowels. The cross-laminated wood produced by the method using only dowels as connectors can be applied to large-sized components of heavy wood buildings.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

An orthogonal glued lumber joined by wooden nails, including the orthogonal glued lumber, each layer of the orthogonal glued lumber is formed by a plurality of laminates; In the intersection unit, the wooden nails are staggered, the nailing point is located on the center line of the overlapping unit, the wooden nails of the same nailing level are a nail layer, the wooden nails of the adjacent nail layers are staggered in the vertical direction, and the adjacent nail layers are The driving angle of the wooden nails is opposite, that is, the driving angle of the wooden nails of one nail layer is 45~60°, and the driving angle of the wooden nails of the adjacent nail layer is 120~135°.

Preferably, the driving angle of the dowels of one nail layer is 60°, and the driving angle of the wood dowels of the adjacent nail layer is 120°.

Preferably, the cross-laminated lumber is composed of three or more odd-numbered layers orthogonally assembled, and the two adjacent layers are parallel layers and vertical layers.

Preferably, the parallel layers are odd-numbered layers, and the vertical layers are even-numbered layers.

Preferably, the laminate is made from softwood by chord-wise sawing, and the laminate has a minimum width of 50mm and a minimum thickness of 12mm.

Preferably, the softwood includes fir, poplar or pine and the like.

Preferably, the coniferous wood includes a single tree species or mixed tree species, and the laminates used in the same layer are of the same tree species in principle. When different tree species are mixed, select tree species with similar wood properties; Basic physical and mechanical properties such as compressive strength, flexural strength and shear strength.

For tree species with similar wood properties, it is necessary to evaluate the origin of the same wood, the differences between different wood species, whether it is modified, the degree of modification, etc.

Preferably, the dowel is a densified dowel made of hardwood; the dowel is a circular dowel with a cone at one end and a capless head at the other end; the diameter of the dowel is 2.5mm to 6.5mm, and the length The range is 35mm ~ 90mm.

Preferably, the hardwood includes beech, oak or teak and the like.

Preferably, the thickness of the nail layer is not less than twice the width of the laminate.

A preparation method of cross-laminated wood joined by dowels, comprising the following steps:

S01, according to the size specification of the cross-laminated wood to be prepared, formulate the size of the laminate and the dowel, the thickness of the nail layer, the method of assembling the laminate and the air pressure of the pneumatic nail gun;

S02, prepare laminates, after drying treatment, flat press and plan the four symmetrical planes of the laminates along the length direction, and saw vertically at both ends, all the laminates are required to have the same size;

S03, to debug the pneumatic nail gun, it is required that the air pressure of the pneumatic nail gun is just right to drive the wooden nails into the nail layer, and ensure that the wooden nails do not protrude from the uppermost layer of the nail layer, and the layers around the wooden nails will not crack;

S04, the laminates are assembled, on the horizontal workbench, the above-mentioned laminates are lengthened to the required length, the lengthening steps are repeated to make the laminates wide, and another group of extended laminates and adjacent groups are alternately arranged To the required width, the staggered interface is required to be parallel to the central cross section of the laminate, and finally the laminate is laterally compressed by the hydraulic device;

S05, interlayer grouping of blanks, the parallel layers are required to be odd-numbered layers, the vertical layers are even-numbered layers, and the total number of layers is odd-numbered layers. The layers required for the first nail layer are aligned and laid from bottom to top in turn, keeping the layers horizontally. Press tightly and fit the upper and lower layers closely;

S06, interlayer bonding, use a pneumatic nail gun to stagger and drive the wooden nails into the center line of each overlapping unit, and the nailing angle is 45~60°. Nail, repeat S04 and S05, so that the thickness of the laminate reaches the depth of the second nail layer, use a pneumatic nail gun to drive the wooden nails staggered into the center line of each overlapping unit, and the nailing angle is opposite to the first nail layer, That is, 120~135°, it is required that two adjacent nail layers have wooden nails in the overlapping unit with only one nail layer in the vertical direction;

S07, repeat S04 ~ S06, until the cross-laminated lumber of the required size is prepared.

The application of cross-laminated wood joined by dowels in large-sized components of heavy wood buildings.

Heavy wood buildings include leisure clubs, schools, gymnasiums, libraries, exhibition halls, conference halls, restaurants, churches, railway stations, walkways, porches, bridges, outdoor landscape facilities, residences, etc.; large-scale components include walls, floors, beams and columns Wait.

The present invention has the following beneficial effects:

The invention studies the influence of the nailing angle on the shear performance of the dowel, and the test finds that when the dowel is driven into the test piece obliquely, when the test piece is subjected to a shear-compression (CS: Compressive-shear, shear-compression) composite stress test piece There is no significant contrast in the bearing capacity, stiffness and ductility of the specimen, and it can be determined that the angle has no significant effect on its shear performance in this state; when the specimen is subjected to a shear-tension (TS: Tensile shear, shear-tension) composite stress test The bearing capacity and stiffness of the components are significantly improved. The maximum bearing capacity of TS45° is 2.45 kN, and the bearing capacity of TS60° is 2.33 kN. Comparing the two, the bearing capacity of TS45° is only 0.12 kN higher than that of TS60°. But in stiffness and ductility, TS60° is 9.70% and 7.51% higher than TS45°, respectively. From the overall evaluation, under the two composite stress states of shear-compression and shear-tension, 60° is the best nailing angle, which has high bearing capacity, high stiffness and good ductility.

The wood fibers on both sides of the interface between the wood peg and the substrate of the present invention are obviously crushed and damaged, and the color of the substrate becomes darker along the driving path of the wood peg. After the wooden nail is pulled out, the surface of the nailed part adheres to the wood fiber and is not easy to fall off. In this study, it was found that the wood pegs were driven into the wood under high pressure by an air gun. Due to the high-speed friction on the surface of the material, the heat generated could soften and fuse the lignin and hemicellulose on the contact surface between the pegs and the wood. The glue-free gluing of the two is realized, and the glue-free glued wooden dowel will not undergo irreversible bending deformation when exposed to a humid environment, which fully meets the needs of large-sized component connection and complex structural design of heavy-duty wood buildings.

The present invention does not need to use any adhesive as a gluing medium, can effectively reduce the release of harmful gases such as formaldehyde, lighten the burden on the environment, and has high processing efficiency, and the nailing components are also convenient for post-processing and recycling.

Description of drawings

Fig. 1 is the rust diagram of the wood structure building using metal connectors in the prior art;

2 is a schematic diagram of the formation of thermal bridges of metal connectors in the prior art;

Fig. 3 is the structural representation of the present invention;

4 is a schematic diagram of a laminate blank of the present invention;

Fig. 5 is the schematic diagram of the interlayer blank of the present invention;

6 is a schematic diagram of a staggered arrangement of wooden pegs of the present invention;

FIG. 7 is a diagram of the orthogonal assembly method of the laminates of the present invention;

Fig. 8 is the final rendering diagram of the implementation case (three layers) of the present invention;

Fig. 9 is the test piece loading design drawing of the wooden nails of the present invention being driven into different angles;

Fig. 10 is the nail groove phenomenon diagram of each group of test pieces with different nailing angles of the present invention;

Figure 11 is a schematic diagram of the ultimate load of each group of specimens with different nailing angles of the present invention;

12 is a schematic diagram of the stiffness of each group of test pieces with different nailing angles of the present invention;

FIG. 13 is a schematic diagram of the ductility coefficient of each group of test pieces with different nailing angles of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention.

Example 1

As shown in Figure 3, a kind of cross-laminated wood joined by dowels, the cross-laminated wood is composed of three or more odd-numbered layers of orthogonal blanks, and the adjacent two layers are the parallel layer 1 and the vertical layer 2. Each layer is formed by arranging the blanks along the transverse staggered interface 4 after being longitudinally lengthened by a plurality of laminates 3. The intersecting part of two mutually perpendicular laminates 3 is an overlapping unit 5, and the dowels 6 are staggered. On the center line of each overlapping unit 5, the same level of nails 6 is driven into one nail layer 7, the wooden nails 6 of the adjacent nail layers 7 are staggered from each other in the vertical direction by 8, and the wooden nails of the adjacent nail layers 7 are staggered. The nailing angles 9 of the nails 6 in the direction of the length of the cross-glued wood are opposite.

The laminate 3 is made from coniferous wood by chord-direction sawing, such as fast-growing wood such as fir, poplar, and pine, and the laminate 3 has no obvious defects, and its minimum width is 50mm and the minimum thickness is 12mm.

Described wooden nail 6 is made by densification of hardwood, such as beech, oak, teak, etc. The wooden nail 6 is a circular nail with a cone at one end and a capless head at the other end. The diameter range is 2.5mm ~ 6.5mm, and the length range is 35mm ~ 90mm.

The parallel layer 1 and the vertical layer 2 are formed by longitudinally extending a plurality of laminates 3 and then staggered along the transverse direction to form blanks, the staggered interface 4 is parallel to the central cross section of the laminates 3, and the laminates 3 used in the same layer have the same size, The parallel layer 1 and the vertical layer 2 are orthogonally assembled.

The overlapping unit 5 is the intersection of the two adjacent laminates 3 up and down, the dowels 6 are staggered and placed in the center of each overlapping unit 5, and each embedded wooden dowel 6 is at least one overlapping unit 5. intersect.

The nail layer 7 is composed of wooden nails 6 that are driven into the same level, and the orthogonal glulam contains at least two nail layers 7, and the wooden nails 6 of the upper and lower two nail layers 7 are required to be staggered to ensure adjacent nails. The nailing angle 9 of the wooden nails 6 of the layer 7 in the perpendicular direction of the length of the glulam is opposite, the nailing angle 9 is 60°, and the thickness of the nail layer 7 is not less than twice the width of the laminate 3 .

A preparation method of cross-laminated wood joined by dowels, comprising the following steps:

S01, according to the size specification of the cross-laminated lumber to be prepared, formulate an implementation plan, including the size of the material (layer 3 and dowel 6), the thickness of the nail layer 7, the method of assembling the layer 3 and the pneumatic nail gun air pressure, etc.;

S02, preparing the laminate, requires that after the drying treatment, the four symmetrical planes of the laminate 3 along the length direction are flat-pressed and planed, and the two ends are vertically sawed, and all laminates 3 are required to be the same size;

S03: Debug the pneumatic nail gun. It is required that the air pressure of the nail gun is just enough to drive the wooden nails 6 into the nail layer 7, and ensure that the wooden nails 6 do not protrude from the uppermost layer 3 of the nail layer 7, and the layers 3 around the wooden nails 6 will not crack;

S04, as shown in Figure 4, the laminates are assembled into blanks, the above-mentioned laminates 3 are lengthened to the required length on the horizontal workbench, the lengthening step is repeated to make the laminates 3 wide, and another group of laminates 3 is extended. It is staggered with adjacent groups to the required width, and the staggered interface 4 is required to be parallel to the central cross section of the laminate 3, and the joints and sides of the laminate 3 do not need to be glued or tenoned. Finally, the laminate 3 is pressed laterally by hydraulic devices. tight;

S05, as shown in Fig. 5 and Fig. 7, the interlayer assembly requires that the parallel layer 1 is an odd-numbered layer, the vertical layer 2 is an even-numbered layer, and the total number of layers is an odd-numbered layer. The boards 3 are aligned and laid from bottom to top to keep the laminates 3 pressed horizontally and the upper and lower laminates 3 closely fit;

S06, as shown in FIG. 6, the layers are joined, and the wooden nails 6 are staggered and driven into the center line of each overlapping unit 5 with a pneumatic nail gun, and the nailing angle 9 is 60°, and the overlapping unit 5 required to be nailed is up and down There are no nails in the left and right four overlapping units 5, and steps S04 and S05 are repeated, so that the thickness of the laminate 3 reaches the depth of the second nail layer 7, and the wooden nails 6 are staggered and driven into the center line of each overlapping unit with a pneumatic nail gun. , the nailing angle 9 is opposite to that of the first nail layer 7, that is, 120°, which requires that two adjacent nail layers 7 have nails in the overlapping unit 5 of only one nail layer 7 in the vertical direction;

S07, as shown in Figure 8, repeat steps S04-S06 until the preparation of cross-laminated lumber of the required size is completed.

The present invention further studies the influence of the nailing angle on the shear performance of the dowel. It can be seen from Table 1 and Figures 11 to 13 that the test found that when the dowel was driven into the test piece obliquely, when the test piece was subjected to shear-compression (CS: Compressive -shear, shear-compression) The bearing capacity, stiffness and ductility of the composite stress specimens have no significant contrast, it can be determined that the influence of the angle on its shear performance is not significant in this state; when the specimen is subjected to shear-tension (TS : Tensile shear, shear-tensile) composite stress specimens have significantly improved bearing capacity and stiffness, among which the maximum bearing capacity of TS45° is 2.45 kN, and the second is 2.33 kN of TS60°. Compared with the two, TS45° The bearing capacity of TS60° is only 0.12 kN higher than that of TS60°, but in stiffness and ductility, TS60° is 9.70% and 7.51% higher than TS45°, respectively. From the overall evaluation, under the two composite stress states of shear-compression and shear-tension, 60° is the best nailing angle, which has high bearing capacity, high stiffness and good ductility.

Table 1 Effects of different nailing angles on shear performance

The wooden nails and nail grooves of the specimens with different nailing angles after loading and failure are shown in Figures 9 to 10. It can be seen from the figures that the wood fibers on both sides of the interface between the wooden nail and the substrate are obviously crushed and damaged, and along the Dowels into the path substrate darken. After the wooden nail is pulled out, the surface of the nailed part adheres to the wood fiber and is not easy to fall off. The study found that the wood pegs are driven into the wood under high pressure with an air gun. Due to the high-speed friction on the material surface, the heat generated can soften and fuse the lignin and hemicellulose on the contact surface between the peg and the wood. Glueless gluing of both. And the glue-free glued wood nails will not be irreversibly bent and deformed when exposed to a humid environment, which fully meets the needs of large-sized component connection and complex structural design of heavy-duty wood buildings.

Example 2

The only difference between this embodiment and Embodiment 1 is that the driving angle 9 of the wooden nails 6 of one nail layer 7 is 45°, and the driving angle 9 of the wooden nails 6 of the adjacent nail layer 7 is 135°.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (8)

1. A preparation method of orthogonal glulam jointed by dowels, characterized in that: comprising orthogonal glulam, each layer of orthogonal glulam is formed by a plurality of laminates (3); The intersecting part of the two mutually perpendicular laminates (3) is an overlapping unit (5), the wooden dowels (6) are staggered, and the nailing point is located on the center line of the overlapping unit (5), and the same horizontal wooden dowel is driven into (6) is a nail layer (7), the wooden nails (6) of the adjacent nail layers (7) are staggered in the vertical direction, and the nailing angle of the wooden nails (6) of the adjacent nail layers (7) is ( 9) On the contrary, that is, the nailing angle (9) of the wooden nails (6) of one nail layer (7) is 45~60°, and the nailing angle of the wooden nails (6) of the adjacent nail layer (7) is 45~60°. (9) is 120~135°; Include the following steps: S01, according to the size specification of the cross-laminated lumber to be prepared, formulate the size of the laminate (3) and the dowel (6), the thickness of the nail layer (7), the method of assembling the laminate (3) and the pneumatic nail the air pressure of the gun; S02, preparing the laminate (3), after drying, flat pressing and planing the four symmetrical planes of the laminate (3) along the length direction, and sawing the two ends vertically, all the laminates (3) are required to have the same size; S03, to debug the pneumatic nail gun, it is required that the air pressure of the pneumatic nail gun is just right to drive the wooden nail (6) into the nail layer (7), and ensure that the wooden nail (6) does not protrude from the uppermost layer (3) of the nail layer (7). And the plywood (3) around the dowel (6) will not crack; S04, the laminates are assembled, on the horizontal workbench, the above-mentioned laminates (3) are lengthened to the required length, the lengthening steps are repeated to make the laminates (3) wide, and another group of extended laminates (3) ) and the adjacent groups are staggered to the required width, and the staggered interface (4) is required to be parallel to the central cross section of the laminate (3), and finally the laminate (3) is laterally compressed by a hydraulic device; S05, interlayer assembly, the number of layers where the parallel layer (1) is located is an odd number, the number of layers where the vertical layer (2) is located is an even number, and the total number of layers is an odd number, and the first nail layer (7 ) The required laminates (3) are aligned and laid from bottom to top, keeping the laminates (3) pressed laterally and the upper and lower laminates closely attached; S06, interlayer bonding, use a pneumatic nail gun to drive the wooden nails (6) into the center line of each overlapping unit (5) in a staggered manner, and the nailing angle (9) is 45~60°, and the overlapping unit required to be nailed (5) The upper, lower, left, and right overlapping units (5) have no nails. Repeat S04 and S05 to make the thickness of the laminate (3) reach the depth of the second nail layer (7). ) staggered into the center line of each overlapping unit (5), the nailing angle (9) is opposite to the first nail layer (7), that is, 120~135°, requiring two adjacent nail layers (7) There are wooden nails (6) in the overlapping unit (5) with only one nail layer (7) in the vertical direction; S07, repeat S04 ~ S06, until the cross-laminated lumber of the required size is prepared. 2 . The method for preparing orthogonal glulam joined by wooden nails according to claim 1 , wherein the nailing angle ( 9 ) of the wooden nails ( 6 ) of one nail layer ( 7 ) is 60°, 3 . The driving angle (9) of the wooden dowel (6) of the adjacent dowel layer (7) is 120°. 3. The preparation method of a kind of dowel-joined orthogonal glulam according to claim 1, it is characterized in that: the orthogonal glulam is formed by three or more odd-numbered layers of orthogonal blanks, adjacent The two layers are the parallel layer (1) and the vertical layer (2). 4 . The method for preparing cross-laminated wood joined by dowels according to claim 1 , wherein the laminate ( 3 ) is made from coniferous wood by chord-direction sawing, and the laminate ( 3 ) The minimum width is 50mm and the minimum thickness is 12mm. 5 . The method for preparing cross-laminated wood joined by dowels according to claim 4 , wherein the coniferous wood comprises a single tree species or mixed tree species, and the laminates ( 3 ) used in the same layer are of the same tree species. 6 . , When different tree species are mixed, select tree species with similar wood properties; wood properties include air-dry density, moisture content, dry shrinkage, compressive strength, flexural strength and shear strength. 6 . The method for preparing orthogonal glued wood joined by wooden nails according to claim 1 , characterized in that: the wooden nails (6) are densified wooden nails made from hardwood; the wooden nails (6) It is a circular nail with a cone at one end and a capless head at the other end; the diameter of the wooden nail (6) ranges from 2.5mm to 6.5mm and the length ranges from 35mm to 90mm. 7 . The method for preparing cross-laminated wood joined by wooden nails according to claim 6 , wherein the broad-leaved wood comprises beech, oak or teak. 8 . 8 . The preparation method of cross-laminated wood joined by wooden nails according to claim 1 , wherein the thickness of the nail layer ( 7 ) is not less than twice the width of the laminate ( 3 ). 9 .

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