Application of bonding technique in solid wood furniture manufacture

Bonding technology is to use the adhesive objects will engage securely in the process and technology, application of bonding technology in modern industrial and agricultural production is widely used in the production of wood furniture, also cannot do without adhesive, which relates to the manufacturing process of solid wooden furniture in the mortise and tenon joint, finger joint, thin wooden sticks, jigsaw process all cannot do without gluing technology, thus, adhesive plays a very important role in the production of solid wood furniture.

1 adhesive used furniture

The adhesion effect, can make the rubber compound with a substance known as an adhesive. Many kinds of adhesives, the nature is not a, wood is a polar material, adhesive and polar substances, can make wood and adhesive solid adhesive. The use of wood industry adhesive accounted for about 60% of all adhesive production, the use of solid wood furniture in the production of adhesive are mainly urea formaldehyde resin adhesive (UF), phenolic resin (PF), the main characteristics and requirements is the excellent performance, low price, abundant raw materials, non-toxic or low toxic, they are of low molecular weight, wettability good, high bonding strength, and contains a lot of reactive groups, can produce chemical adsorption and wood fiber. Among them, heat resistance, water resistance of urea formaldehyde resin adhesive is good, but easy to aging. The phenolic resin glue, water resistance, aging resistance, heat resistance are better than that of urea formaldehyde resin adhesive, but the color is deep, certain brittleness. In addition, polyvinyl acetate emulsion, epoxy resin emulsion, polyester resin emulsion, polyurethane emulsion, polyurethane emulsion and solid wood furniture commonly used in the production of adhesive, wherein, polyvinyl acetate emulsion (PVAC) is the most widely used emulsion adhesive production of solid wood furniture, it is also called the milk white glue, curing at room temperature faster, non-toxic, is transparent and has toughness, but its poor water resistance. The modified water soluble isocyanic acid lipid emulsion adhesive is a kind of excellent adhesive, in Glulam, spell plank has been widely used, and its amount is increasing year by year.

The 2 bonding mechanism

Adhesive two is process of rubber compound is firmly connected together are called adhesive. Solid wood furniture in the parts of the bonding process, a series of physical and chemical changes of wood surface, through long-term research formed a series of bonding theory.

2.1 mechanical bonding mechanism

Adhesive penetration into cell cavity through the tube holes of wood wood surface, with the adhesive cured or hardened, forming many small hooks or plastic nails in them, which will be two pieces of wood glued together.

2.2 adsorption bonding mechanism

That the adhesive is adhesive molecules and adherend molecules in the interfacial layer between adsorption produced, the bonding effect is a physical adsorption and chemical adsorption and physical adsorption results, annex is a common cause of bonding effect.

The 2.3 diffusion bonding mechanism

Occurrence of miscible in the bonding interface, resulting in adhesive and adherend molecules through mutual diffusion and the formation of a tight joint.

2.4 chemical bonding bonding mechanism

The adhesive and adherend intermolecular chemical reaction to obtain primary valence bond high bonding strength, chemical bond force than the much larger intermolecular force. In the bonding process is mainly through the adhesive and active group, be glued materials of coupling agent, the adhesive and adherend molecules to form a chemical bond between the surface treatment and the active group and adhesive. One side, several mechanisms are more than only reflect gluing phenomenon in fact, wood glue is the interaction results of several forces.

The 3 bonding technology

In the production of solid wood furniture, plywood mainly occurs in the mortise and tenon joint, finger joint, plate, thin wooden stick in the process. Adhesive bonding technology mainly includes the joint design, surface treatment, adhesive and coating, curing and quality inspection etc.. The following discusses the engagement of these aspects.

The 3.1 tenon joint of glue

Bonded solid wood furniture Zhang mainly has three forms: square end mortise and tenon joint, (elliptic) round tenon joint, dowel joint, as shown in figure 1. In a square tenon and (an) round tenon joint, the adhesive is coated in the tenon and mortise around, in also injected adhesive, and then inserted into the mortise and tenon connection, form a layer of film between the tenon and mortise joint, so as to achieve good effect, therefore, to use -0.2-0.5mm fit in tenon and mortise process, namely the tenon mortise smaller than 0.2 0.5mm to form an adhesive layer in between, if interference is tenon mortise, than large, it will reduce the bonding strength, because in the assembly due to excessive adhesive tenon out and lost the adhesive for. At the same time, with the same cross section oval tenon) round Zhang comparison (elliptic), the bonding strength of dowel than tenon, because, (elliptic) round mortise bonding area for example tenon big.

Dowel according to its surface has no texture is generally divided into: smooth type, straight pattern, twill and reticulate type 4 (see Figure 2), the joint effect of Shen smooth type is the worst, a type of the best, reticulate type and straight type secondary, because twill twill in type can accommodate more adhesive and the formation of dense plastic nail, screw and the twill is similar to screw with locking function, reticulate although twill type can hold more adhesive, but the dense reticulate destroyed the wooden dowel itself and reduce the bonding strength,

3.2 finger joint of glue

Zhang is a solid wood furniture production in the process, it will board and square lumber splicing growth material of small, so that not only do the small material use, but also can eliminate stress, material deformation is reduced, in this process, the adhesive has played an important role