A kind of manufacturing approach of laminated veneer lumber
Technical field
The present invention relates to a kind of manufacturing approach of laminated veneer lumber, relate to a kind of method of utilizing the fast-growing woods material to make laminated veneer lumber in particular.
Background technology
Along with improving constantly of China's rapid economic development and people's living standard, people are more and more stricter to the performance requirement of home decoration material, and green, ecology, healthy wood materials receive people's welcome again and like.China is the country of a forest reserves wretched insufficiency; The forest reserves are very poor; According to the 7th forest assessment result of China; The not enough world occupancy volume per person's of China's area of woods per capita 1/4th adds the enforcement of " wildwood protected project ", the problem of further having aggravated China's timber resource shortage.For alleviating the nervous problem of timber resources, timber industry begins sight is turned to the artificial fast-growing woods resource that becomes increasingly abundant.
Though artificial fast-growing woods material such as poplar, Eucalyptus etc. have fast growth, the short advantage of time of becoming a useful person, and all have the shortcoming that the footpath level is little, yielding, size variation property is big.How to utilize small diameter grade low-quality fast growing wood to make laminated veneer lumber and wait to substitute the big specification sawn timber use that to use big footpath level log saw system; Become the emphasis and the focus of current research day by day; Because so not only can realize the excellent usefulness of bad material, the big usefulness of small wood; Realize the efficient utilization of fast growing wood and widen its application, also also have great importance by the contradictory problems that the timber shortage is brought simultaneously alleviating China.
Laminated veneer lumber (be called for short LVL) compare with solid wood have even structure, the intensity advantages of higher, can satisfy the instructions for use in fields such as timber buildings, bridge, furniture and traffic.Application publication number is CN101947799, Shen Qing Publication day to be the production method that the Chinese invention patent on January 19th, 2011 discloses a kind of laminated veneer lumber, and the process of its making is following: the blocking of the preparation-gluing of veneer and assembly-discontinuous precompressed-assembly plate-hot pressing-edging and saw cut open-sanding-packaging and warehousing.But, adopt aforementioned production method also to have weak point:
1, in the preparation of veneer; The veneer that adopts the rotary-cut of small diameter grade fast growing wood to go out; Because the huge growth stress that exists in the fast growing wood; The veneer that screws out is easy to occur defectives such as warpage, distortion, in the gluing process, is prone to cause the inhomogeneous of gluing, thereby causes the low waste that reaches adhesive of bonding strength between veneer;
When 2, utilizing the laminated veneer lumber of fast growing wood manufacturing, owing to problems such as fast growing wood have shortcoming yielding, of light color, that superficial makings is outstanding, and it is poor that the LVL product of processing has decorate properties, and the grain of wood is unintelligible and yielding;
3, laminated veneer lumber adopts the assemble pattern of texture single direction, and poor dimensional stability, structural strength are low.
Summary of the invention
The manufacturing approach that the purpose of this invention is to provide a kind of laminated veneer lumber, its process is simple, and the laminated veneer lumber dimensional stability of making is good, structural strength is high, and is not yielding.
In order to solve the problems of the technologies described above, technical scheme of the present invention is following: a kind of manufacturing approach of laminated veneer lumber may further comprise the steps:
1) gets the raw materials ready; With the fast growing wood log cooking softening after, on peeler, be peeled into former veneer, former veneer is cut into veneer as required; Then the water content of veneer is adjusted to 8-20%;
2) carbonization; Veneer is put into hot press hot pressing carbonization, and hot pressing temperature 190-210 ℃, hot pressing pressure is 0-1.5MPa, and hot pressing time is 1-5min;
3) health; Veneer after the carbonization is cooled to below 80 ℃, puts into natural conditions or temperature adjustment, the damping room carries out health, makes that the veneer moisture content after the carbonization is adjusted to 5-10%;
4) gluing and assembly; Veneer after the health is carried out double spread, the veneer behind the gluing is carried out assembly, wherein, the second layer of laminated veneer lumber and layer second from the bottom are horizontal assembly, and all the other are the rift grain assembly;
5) cold pressing; The laminated veneer lumber that assembly is folded utilizes the cold press pre-molding;
6) hot pressing; Utilize hot press hot-forming the laminated veneer lumber of pre-molding;
7) edging and saw cut open; With edging around the hot-forming laminated veneer lumber, sawing becomes piece as required then;
8) sanding and packing; Sawing is become sanding, packaging and warehousing then around the laminated veneer lumber of piece.
As preferably, in the said step 4), the thickness of the laminate that the second layer of laminated veneer lumber and layer second from the bottom are formed by horizontal assembly is identical with the thickness of the laminate that the rift grain assembly forms.
As preferably, in the said step 5), preload pressure is 0.8-1.0MPa, and the time is 1-2h.
As preferably, in the said step 6), hot pressing temperature is 110-120 ℃, and hot pressing pressure is 1.0-1.2MPa, and hot pressing time is 0.3-0.5h.
As preferably, said step 2) in, the heating platen surface temperature difference of hot press should be less than 5 ℃.
As preferably, in the said step 1), the thickness of said veneer is 1-2mm.
As preferably, in the said step 1), said fast growing wood log is Eucalyptus, poplar.
As preferably, the number of plies of said laminated veneer lumber is the 6-12 layer.
As preferably, in the said step 4), the glue-spread of veneer is 300-320g/cm
2
As preferably, said step 2) in, 230 ℃ of hot pressing temperatures, hot pressing pressure is 1.0MPa, hot pressing time is 5min.
Beneficial effect of the present invention is:
1) veneer is carried out carbonization treatment, not only can deepen the color of veneer, improve the definition of texture; Reduce aberration, and can discharge and have huge growth stress in the fast growing wood veneer, improve the flatness of veneer; Not only can improve the uniformity of gluing; Improve the bonding strength of laminated veneer lumber, but also can reduce the distortion and the warpage of laminated veneer lumber, strengthen structural strength;
2) assembly has adopted the second layer and layer second from the bottom to be the mode of horizontal assembly, and top layer and other layers are the mode of rift grain assembly, further improve the dimensional stability and the structural strength of laminated veneer lumber, are not easy distortion.
Description of drawings
Below in conjunction with accompanying drawing the present invention is done further explanation:
Fig. 1 is the assembly sketch map of one embodiment of the invention.
The specific embodiment
The following stated is merely preferred embodiment of the present invention, is not scope of the present invention is limited.
Embodiment sees accompanying drawing 1, the manufacturing approach of laminated veneer lumber, and fast growing wood can adopt poplar, Eucalyptus etc.; What this embodiment adopted is Eucalyptus, and the number of plies of laminated veneer lumber is at least 6 layers, and the number of plies of laminated veneer lumber can be 6,7,8,9,10,11, the 12...... layer, and concrete can select according to actual conditions; The thickness of veneer is 1-2mm, below, be example with the preparation method of Eucalyptus laminated veneer lumber; Be described in detail down manufacturing process, Eucalyptus laminated veneer lumber gross thickness is 12mm, and long is 0.9m; Width is 0.5m, and the Eucalyptus veneer of employing is 6 layers, and the Eucalyptus veneer thickness is 1.7mm.
1) gets the raw materials ready; With the Eucalyptus log cooking softening after, on peeler, be peeled into the thick former veneer of 1.7mm, then former veneer is cut off as required, form the Eucalyptus veneer; Through drying naturally or drying, the water content of Eucalyptus veneer is adjusted to 8-20%;
2) carbonization; The Eucalyptus veneer is put into hot press hot pressing carbonization, and hot pressing temperature 190-210 ℃, hot pressing pressure is 0-1.5MPa, and hot pressing time is 1-5min; In the time of the hot pressing carbonization, the heating platen surface temperature difference of hot press should be less than 5 ℃, improving the uniformity of Eucalyptus veneer carbonization, can improve dimensional stability, durability and the color of Eucalyptus veneer and the added value that can promote through carbonization treatment.See attached list 1; What the hot pressing pressure in the table was that 0MPa representes is to only depend on the heating platen deadweight of hot press that the Eucalyptus veneer is compressed.
Table 1 Eucalyptus veneer charing orthogonal test table
3) health; Eucalyptus veneer after the carbonization is cooled to below 80 ℃, and cooling can be adopted nature cooling or force cooling, then with cooled Eucalyptus veneer put into natural conditions or temperature adjustment, the damping room carries out health, makes that the veneer moisture content after the carbonization is adjusted to 5-10%; When in temperature adjustment, damping room, carrying out health, temperature is controlled at 25 ± 3 ℃, relative humidity 60-70%;
4) gluing and assembly; Veneer after the health is carried out double spread, and glue-spread 300 ~ 320g/cm2 carries out double spread to the Eucalyptus veneer, and adhesive is the agent of modified starch gluing; Veneer behind the gluing is carried out assembly, and wherein, the second layer of laminated veneer lumber and layer second from the bottom are horizontal assembly, and all the other are the rift grain assembly; As can beappreciated from fig. 1, the laminate that is made up of the Eucalyptus veneer for the second time is horizontal assembly, and remaining laminate that is made up of the Eucalyptus veneer is all along Eucalyptus grain direction assembly, and two laminate thickness generally equate; Do like this, can improve the structural strength of whole laminated timber, form cross one another structure with ground floor Eucalyptus baffle plate bonding back behind the second layer Eucalyptus veneer assembly; Very firmly, be not easy distortion after processing, structural strength is high; In like manner, with layer Eucalyptus veneer bonding last, also form cross one another structure behind second from the bottom the Eucalyptus veneer assembly; Very firmly, be not easy distortion after processing, like this; Just can make that the structural strength of whole laminated timber is improved, in use be not easy distortion, and if the laminate of horizontal assembly is arranged on the top layer; So, structural strength in the longitudinal direction can descend, if laterally the laminate of assembly is arranged on the 3rd layer or the 4th layer etc.; The laminate of two-layer so above that or three layers rift grain assembly, structural strength is still not high, warps easily, is out of shape, ruptures.
5) cold pressing; The laminated veneer lumber that assembly is folded utilizes the cold press pre-molding; Preload pressure is 0.8-1.0MPa, and the time is 1-2h.
6) hot pressing; Utilize hot press hot-forming the laminated veneer lumber of pre-molding; Hot pressing temperature is 110-120 ℃, and hot pressing pressure is 1.0-1.2MPa, and hot pressing time is 0.3-0.5h.
7) edging and saw cut open; With edging around the hot-forming laminated veneer lumber, sawing becomes piece as required then;
8) sanding and packing; Sawing is become sanding, packaging and warehousing then around the laminated veneer lumber of piece.
For analyzing the bending resistance of laminated veneer lumber of the present invention; The anti-deformation of product when particularly product being used as ground heating timber floor; Above-mentioned Eucalyptus laminated veneer lumber and the Eucalyptus laminated veneer lumber that adopts conventional method to process are made into the timber floor of same size; Through simulation floor heating week after date,, the situation of change of horizontal curved, easement of timber floor and crosswise concaving is tested according to GB/T 6491-1999 Drying quality of sawn timber.If the bending resistance of timber floor is poor more, timber floor is at process floor heating week after date, and the flexibility recruitment of timber floor is also just big more.The floor heating cycle of a simulation is made up of 20 ℃ of temperature and relative humidity 65%, 30 ℃ of temperature and relative humidity 90%, 40 ℃ of temperature and relative humidity 30% and 20 ℃ of temperature and 65% 4 part of relative humidity; The timber floor bending resistance is through contrasting the recruitment of last horizontal curved, the easement in various timber floors stable respectively back in above-mentioned 4 environment, crosswise concaving; The result is as shown in table 2; What conventional group was represented is the bending resistance test result of Eucalyptus laminated veneer lumber timber floor; What adopt is that usual manner is made; What the carbonization group was represented is the bending resistance test result of Eucalyptus laminated veneer lumber timber floor, and what its difference with conventional group was to adopt is carbonization Eucalyptus veneer, and the 1-9 group is the above-mentioned 9 groups test results that adopt the timber floor of the Eucalyptus laminated veneer lumber that modes of the present invention make.
The bending resistance test result of table 2 Eucalyptus timber floor
Can know by table 2 result; Compare with conventional Eucalyptus laminated veneer lumber and carbonization Eucalyptus laminated veneer lumber; Laminated veneer lumber of the present invention can obviously improve the bending resistance of laminated veneer lumber; When laminated veneer lumber of the present invention uses as ground heating timber floor, also can satisfy the requirement of product to plate property.
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