RU2216443C1 - Method of wood preparation for drying - Google Patents

Abstract

FIELD: methods of preparation of lumber, mainly, cant and thick boards up to 100 mm thick before their drying; applicable widely at wood-working plants in manufacture of furniture, houses, etc. SUBSTANCE: drying is carried out both, in chambers, and by self drying. Method consists in that sawn preliminarily from log intended for producing of cants is heart board, and cants are cut from remaining two halves of log. In this case, inner faces of cants are oriented parallel to faces of sawn heart board, and further-on, additionally to end faces, inner and side faces of sawn cants are coated with aqueous emulsion substance possessing adhesion to damp wood. Offered method of preparation of cant wood and thick boards and their drying by active and natural drying is tested on the following species of wood: pine, spruce, oak, larch. Obtained moisture content in all said wood species during preparation and further drying does not exceed 6-8%. Time of cant drying for wood of coniferous species was lower by a factor of 2-3 as compared with that of prototype. Faces and end faces of dried cants were free of cracks of any type. EFFECT: higher efficiency of method. 1 dwg

Description

 The invention relates to woodworking, and in particular to a technology for the preparation of lumber, mainly timber and thick boards (up to 100 mm thick) before drying. The invention can be used in woodworking enterprises in the manufacture of boards, furniture, houses, etc.

 A known method of drying wood for the production of timber, in which the preliminary preparation of wood before drying is that along the longitudinal axis of the timber on its opposite sides, grooves are made and then, when drying, they direct the air flow along these grooves. The disadvantage of this method is that the presence of longitudinal grooves on opposite sides of the beam allows to some extent reduce the total drying time of the beam itself, but does not protect the beam from cracks that form during drying. So, in opposite layers, in which grooves, cracks are located, they form and develop in the grooves themselves. In some cases, cracks in the grooves during the drying process reach significant sizes and are the cause of the collapse of the beam along the longitudinal guide in the layers. In addition, in the known method, in the process of drying the beam, end cracks are formed, which in the course of their development pass into the central cracks of the layers [RF patent 2163328, cl. F 26 In 3/04, 2001].

 The disadvantage of this method is the uneven drying of the timber along its length. The unevenness of the drying of the beam along the length is explained by the fact that the ends of the beam, on which the larger capillaries go (in comparison with the microcapillaries extending to the sides of the beam), dry much faster than the middle of the beam. This non-uniformity of drying, in turn, causes additional stresses that arise in the sheets of the timber during the drying process, and is the cause of additional cracks.

 Slowing down the drying of the middle part of the timber also leads to a general slowdown in the drying of the timber as a whole.

 A known method of preparing wood for drying core boards, in which to protect the wood from cracks, the ends and parts of the plank layers are coated with an aqueous emulsion substance having adhesion to raw wood boards. A known method of preparing wood before drying effectively protects the wood from cracks, but the scope of this method is to protect only wood from boards from cracks [RF patent 2164467, cl. B 27 K 5/00, 2001].

 Closest to the invention is a method of preparing wood, in particular boards, for drying them, in which the ends of the boards (side) are coated with an aqueous emulsion substance having adhesion to raw wood [RF patent 2164466, cl. B 27 K 5/00, 2001].

 The known method of the prototype is used mainly to protect against end cracks that form during the drying process, but it does not protect against longitudinal cracks that form in the beam.

 The basis of the invention is the task of developing a method for preparing a bar for drying, in which a core board is cut out from a log intended for producing beams, and the beams are cut from the remaining two halves of the log, and the inner planks of the beams are oriented parallel to the sawn core planks, then in addition to the ends, the inner and outer layers of sawn timber are coated with an aqueous emulsion substance having adhesion to raw wood. This ensures the redistribution of the moisture output along the closed water emulsion substance to the planks of the timber and on its uncovered layers. In this case, the moisture output over the areas of the layers is more uniform.

 As a result of the redistribution of the moisture yield across the layers and a more uniform distribution of the moisture yield over the areas of the beam layers themselves, the following practical problems are solved, namely, the elimination of all types of cracks on the layers and ends of the dried beam, and a reduction in drying time.

 The problem is solved by the fact that a method of preparing a bar for drying is proposed, in which a core board is cut out from a log intended for receiving the beams, and the beams are cut from the remaining two halves of the log, and the inner faces of the beams are oriented parallel to the sawn core plates, in addition to the ends of the aqueous emulsion substance having adhesion to raw wood, cover the inner and outer layers of sawn timber.

 As an aqueous emulsion substance having adhesion to wood planks, water-based glue of the emulsion type, water-based varnish of the emulsion type, water-based paint of the emulsion type, and the like can be used.

 The moisture discharge mechanism from the timber prepared according to this method differs from the moisture discharge in the prototype method. So, in a dried timber with external and internal layers and ends, previously closed with an aqueous emulsion substance that has adhesion with raw wood, there is a redistribution of moisture removed from it. Moreover, most of the moisture is released through the plank of the timber, not closed by the aqueous emulsion substance, i.e. plast, perpendicular to the outer and inner layers of the timber. Moisture output through the closed surface of the outer and inner layers, as well as through the ends of the beam is reduced. At the same time, due to the colloid and wettability of the aqueous emulsion substance covering the outer and inner layers and the ends of the beam, the moisture is released from these surfaces uniformly over all their surfaces. Despite the limitation of the moisture output through the external and internal layers coated with the aqueous emulsion substance, as well as through the covered ends of the beam due to the redistribution of the moisture output through the non-closed layers and due to the large area of the latter, the total rate of moisture release from the timber increases in comparison with the rate of moisture release according to the prototype . This explains the acceleration of the drying of the timber by this method and the reduction of the drying time.

 Due to the uniform discharge of moisture over areas covered by an aqueous emulsion substance, local stresses are removed in them during the entire time of drying the beam. This, in turn, prevents the formation of cracks in the outer and inner layers, as well as in the ends of the timber during its drying. Preparation of timber for drying timber by coating its inner and outer layers, as well as coating and ends of the timber with an aqueous emulsion substance having adhesion to raw wood, is effective for timber, the manufacturing (sawing) scheme of which is described in the claims of the present application. A core board is cut out from a log intended for producing beams, and from the resulting two longitudinal halves of a log, predetermined sizes of beams are cut. In this case, the inner faces are oriented parallel to the layers of the sawn core board. Sawed beams according to this scheme have pronounced inner and outer layers and adjacent to them perpendicular to the side faces. In such a beam, the inner and outer layers are more susceptible to the appearance of cracks in the process of drying the beam. The greatest tendency to cracks is the outer layer. This is primarily due to the action of differential forces acting on the gap along the wood fibers during drying of the timber. The next highest risk of cracks during drying is the inside of the bar. As a result of the preparation of wood, i.e. After coating the outer and inner layers, as well as the ends of the beam with an aqueous emulsion substance, most of the moisture goes out through the uncovered formations of the beam. This, in turn, significantly reduces (and virtually eliminates) the possibility of cracks in the beam.

 The method according to this invention is as follows. As an aqueous emulsion substance having adhesion with raw wood, a PVA type water-based adhesive (polyvinyl acetate), VD-AK-1101 type water-based varnish (based on acrylic dispersion) or VD-VA-224 type water-based paint [Savinykh V. P. Craftsman about ornamental materials. Mn .: Polymya, 1997, p. 309].

 Cutting the logs onto the bars according to this method can be illustrated in the drawing, depicting a log 1 in a section, a core board 2 in a section, 3 and 4 - bars; 5 - the outer layer of the beam 3; 6 - the outer layer of the timber 4; 7 - the inner face of the beam 3; 8 - the inner face of the beam 4; 9 - side plate of the beam 3; 10 - side plate of the beam 4.

 The method according to this invention is as follows. From the log 1, the core board 2 is cut, which divides along the log 1 into two halves. From the resulting two halves of the logs sawed beams 3 and 4 of the required size. Moreover, the internal faces 7 and 8 of the beams 3 and 4, when cutting, are oriented parallel to the layers 11 of the core board 2. Sawed in this way, the boards, before drying them, cover (paint) the inner and outer layers, as well as the ends of the boards with adhesive like PVA or water-based VD-AK-1101 varnish or VD-VA-224 water-based paint.

 Further, the bars thus prepared, i.e. with closed external and internal layers and ends, dried, for example, using the method of natural drying, or in thermal chambers using additional energy.

 Tests of the described method for preparing the timber of timber and their drying by active and natural methods were carried out on the following species of wood: pine, spruce, oak, larch. The humidity reached in the process of preparation and further drying on all the listed rocks of the boards did not exceed 6-8%. The drying time of the beams for coniferous wood was 2-3 times less in comparison with the method of the prototype. All types of cracks were absent on the layers and ends of the dried bars. All technological methods (processes) for preparing and drying the bars for further drying, which provide a solution to the tasks in this invention, are easily mechanized, automated, and automatically controlled. This in turn provides the possibility of wide industrial implementation of the proposed method. This in turn provides a wide industrial implementation of the proposed method.

Sources of information
1. The method of convective drying of wood, patent 2163328.

 2. A method of preparing boards for their natural drying, patent 2164467.

 3. A method of preparing boards for their natural drying, patent 2164466.

Claims (1)

 A method of preparing wood for drying, in which the ends are coated with an aqueous emulsion substance having adhesion with raw wood, characterized in that a core board is cut out from the logs intended for the production of the beams, and the beams are cut from the remaining two halves of the log, with the inner layers the bars are oriented parallel to the layers of the sawn core board, then, in addition to the ends, they cover the inner and outer layers of the sawn bars with an aqueous emulsion substance having adhesion to raw wood.