CN104227804A - Method for manufacturing plywood by pressing, repairing and primary hot-pressing - Google Patents

Abstract

The invention provides a method for manufacturing plywood by pressing, repairing and primary hot-pressing and belongs to the technical field of wood processing. According to the technical scheme, the method includes that 1), raw wood is cut, boiled and peeled; 2), the raw wood is subjected to veneer rotary cutting, drying, repairing, glue splicing and chopping, wherein moisture content of each veneer ranges from 8% to 12% after the veneers subjected to rotary cutting and slicing is dried; 3), the well-cut veneers are subjected to gluing, assembling, preloading, hot pressing and cooling with a glue spraying or gluing method; 4), finally, edge cutting and sanding are performed to obtain a finished product. The method is simple in process, small in space occupation and low in material loss and energy consumption.

Description

The preparation method of a hot-press gluing plate is repaired in precompressed

Technical field

The invention belongs to wood processing technique field, particularly relate to the preparation method that a hot-press gluing plate is repaired in a kind of precompressed.

Background technology

Glued board is peeled into veneer by juggle or becomes veneer by flitch slicing, then stick with glue three layers of agent gummed or the board-like material of multilayer, usually uses odd-level veneer, and the orthogonal gummed of the machine direction of adjacent layer veneer is formed.

Glued board is one of sheet material with fastest developing speed in current China wood-based plate.Mainly there is the problems such as surface smoothness, thickness deviation and buckling deformation in glued board in the market.Medium and high classes plywood production technology is in continuous change in recent years, to improving product quality.

The surface smoothness of glued board, thickness deviation and buckling deformation are important quality index, major influence factors:

1, the impact of plate core core bar unit: the plate core that glued board is mainly put together by core bar is formed, because core bar size is large, and the impact of machining accuracy and moisture content, be difficult to reach identical plastic deformation and homogeneous wood property at one time.

2, the impact of plate core core bar material: even if plate core core bar selects identical material, also can because of land occupation condition, early, late wood, the age of tree, the impact such as defects in timber and variant.When the wood property difference of adjacent core bar is larger, common process is difficult to produce high-quality glued board.And be unpractical to core strip material in large-scale production by quality of material separator.

3, the impact of central layer: produce the face of glued board, backboard slimming increasingly.Produce the glued board of high surface smoothness with sake, backboard, require very high to central layer.Adopt the domestic fast growing wood such as poplar, paulownia to carry out rotary-cut at present, because material is poor, rotary cut venner hole is many, rough surface, and burr groove is many more, and thickness deviation is large, and the impact of effects on surface flatness is very large.Existing factory adopt shear draw materials after the technique of multiple manual splits or machine automatization split.The thickness deviation of each veneer in individual central layer after split, moisture content height, the heart, sapwood or early, the wood property etc. of late wood still affects the surface smoothness of glued board, dimensional stability and thickness deviation.

4, the impact of layer of structure: normal plywood is generally panel, central layer, plate core, central layer, backboard five-layer structure.Because layers of material there are differences, easily cause board dimension and change in shape.Panel, backboard and two central layers in seeds, wood property, thickness, moisture content etc. to deserving to be called in addition difficulty, also have impact on the stable of size and dimension.

The moulding process of glued board:

1, the moulding process once suppressed, once compressing technique is by the plate core of mating formation by hand or directly glue is good, directly enters press suppress with paddle core together with panel, backboard after forming base.Shortcoming is A. central layer quality influence flatness.B. after compacting, the thickness deviation of accumulation is large.C. the aberration of plate core has a strong impact on product appearance.D. the difference between core bar unit size, material etc. are very large to the quality influence of sheet material.

2, precompressed is repaired the concise and to the point flow process that technology with hot pressings twice precompressed repairs technology with hot pressings twice and is: central layer single spreading → two central layer and plate core assembly → slab precompressed → repairing → hot pressing → repairing → ageing are shaped → sanding thick → face, backboard hot pressing veneer calmly.This technological advantage: A. repairs, sanding substantially increases flatness.B. the slab ageing sanding more two days later after hot pressing finishing, residual stress is released, and sheet material is more stable.C. fixed thick sanding ensure that the thickness deviation of plate surface flatness and permission.D. the presentation quality of sheet material improves.This technique at present by, integrated mill generally adopts.Shortcoming is that process is complicated, and take up an area large, material unaccounted-for (MUF) and energy resource consumption are greater than a heat pressing process.

Summary of the invention

The invention provides the preparation method that a hot-press gluing plate is repaired in a kind of precompressed, preparation method manufacturing process of the present invention is simple, takes up room little, material unaccounted-for (MUF) and energy resource consumption little.

The preparation method of a hot-press gluing plate is repaired in precompressed of the present invention, is realized by following technical proposals:

(1) log block, boiling, peeling;

(2) Veneer Cutting, drying, repairing, splicing and shearing, after drying, Veneer moisture is at 8%--12% for rotary-cut and sliced veneer;

(3) the veneer pouring glue sheared or the method gluing of gluing, assembly, precompressed, hot pressing and cooling;

(4) eventually pass cutting edge, sanding, go out finished product.

Detailed description of the invention

Below by specific embodiment, the present invention is further illustrated.

Take timber as the glued board of main material production, due to the retrofit in the reasonability of its structure and production process, the defect that can overcome timber substantially improves the physical and mechanical property of timber greatly, and plywood production is the important method sufficiently and reasonably utilizing timber, improve wood performance.

The constitution principle of glued board:

Symmetry principle: the veneer of ymmetry center plane both sides, the moisture content of seeds veneer thickness, the number of plies, manufacture method, machine direction and veneer all should in correspondence with each other, and namely the stress intensity of each respective layer in symmetry principle glued board central plane both sides different directions is equal.Therefore, when moisture content of plywood changes, its Stability Analysis of Structures, can not produce distortion, the defects such as cracking; Otherwise, if ymmetry center plane both sides respective layer has some difference, the stress of ymmetry center plane both sides veneer will be made unequal, make glued board produce distortion, cracking.

Odd-level principle: the structure due to glued board is that the machine direction of adjacent layer veneer is hung down mutually, must meet symmetry principle again, and therefore its total number of plies must be odd number.As: three ply board, five laminates, seven laminates etc.; Horizontal shearing stress maximum when odd-level glued board bends acts on core veneer, makes it have larger intensity; Horizontal shearing stress maximum when even level glued board bends acts on glue-line instead of acts on veneer, easily makes glue-line destroy, reduces Strength of Plywood.

The height of plate core quality affects quality and the cost of glued board, therefore, plate core be produce the crucial workshop section of glued board by material and processing technology;

1, the core bar of plate core and processing thereof, dried sheet material is scraped through two-sided, and be sawn into core bar with the with nothing left alloy of multi-disc, the face of scraping becomes bar side, and sawing face becomes bar front, therefore core bar is fixed thick by multiple blade saw.Processes efficiency is high, and core bar accuracy to size is high, and material unaccounted-for (MUF) is few, but the processing dimension of General Requirements material is larger;

2, plate core forming technology, smears the plate core of splicing synthesis certain specification by core bar, then through scraping or sanding.Jigsaw mode is varied.Continuous hydraulic plate joggling apparatus is the jigsaw machinery of current extensive use, and jigsaw efficiency is high, and quality is good, and mechanization degree is higher;

3, plate core aft-loaded airfoil, the plate core after splicing also needs to carry out sanding or to scrape etc. aft-loaded airfoil, to improve surface smoothness, reduces thickness deviation.Plate core downstream equipment generally adopts three sand machines or two sand frame sander, can good whole thicknessing.In recent years have also appeared sanding and the fixed thick plane sand machine connected together of scraping.

For the shortcoming of technology with hot pressings twice, occurred that a heat pressing process is repaired in a kind of new precompressed, concise and to the point flow process is: thick → face, backboard hot pressing veneer are determined in slab precompressed → repairing → sanding.Requirement to raw material and technological parameter: the requirement of A. to central layer improves relatively.Groove can not be dark, and hole must use single board repair, can not add Putty, the strict generation controlling gap.B. the initial strength after slab precompressed requires higher, and have particular/special requirement to adhesive, one is to have high viscosity, and two is to have the longer active phase.C. technique need carry out certain adjustment.This technique material and technological requirement high.

The juggle preparatory stage: the operations such as log blocks, boiling, peeling;

The veneer fabrication stage: Veneer Cutting, drying, repairing, splicing and shearing, rotary-cut and sliced veneer are after drying, Veneer moisture is at 8%--12%, gluing assembly glues together in hot press, almost various adhesive can produce glued board by this kind of method, and gluing time is short, and bonding strength is high, plate face is smooth bright and clean, not yielding;

The plywood making stage: veneer gluing, assembly, precompressed, hot pressing and cooling;

The glued board process segment: cutting edge, finishing and Surface Machining;

The veneer sheared drench glue or gluing method gluing, assembly, precompressed, hot pressing, eventually pass cutting edge, sanding, go out finished product.

Claims (1)

1. a preparation method for a hot-press gluing plate is repaired in precompressed, it is characterized in that comprising the following steps:

(1) log block, boiling, peeling;

(2) Veneer Cutting, drying, repairing, splicing and shearing, after drying, Veneer moisture is at 8%--12% for rotary-cut and sliced veneer;

(3) the veneer pouring glue sheared or the method gluing of gluing, assembly, precompressed, hot pressing and cooling;

(4) eventually pass cutting edge, sanding, go out finished product.