Wood welding technology: applied to the connection of wood products, is this a new technology?
When it comes to welding, what can you think? Is there fire? High temperature and high heat? Blinding? Yeah! You're right.
However, the welding we are talking about today is applied to the connection of wood products, but it is different from the introduction of ultra-high heat sources required for common iron welding. What this article tells you is "welding technology of rotating wood with round rod and tenon".
(Photo source: Furniture Industry-public number, invasion and deletion)
is the connection method of wood products not good now?
Of course not! Since the development of solid wood furniture production and assembly technology, it has become mature and stable, but there is still room for improvement.
Traditional mortise and tenon joint production process is complex and Wood loss is serious; Metal parts in metal parts connection are prone to rust spots or corrosion, which affects the joint strength;
when the round rod is tenon joint, glue must be applied to the tenon hole or Tenon during assembly, so there is a situation that glue is easy to pollute the non-joint surface, and certain pollutants are released in production and use.
(Photo source: Furniture Industry-public number, invasion and deletion)
the round Rod Tenon rotating wood welding technology we want to talk about is a new technology developed from Europe at the end of the 20th century and the beginning of the 21st century. The round Rod tenon is in the pre-drilled drawer front holes (the aperture is slightly smaller than the diameter of the round Rod tenon) high-speed rotation, without adding any adhesive or any other materials, but fixed in the wood base material with holes drilled or relatively fixed the base material, is a kind of instant joint, economical, environmentally friendly, wood bonding technology with great development potential.
What on earth is round Rod Tenon rotating wood welding?
How to define this technology? Relevant scholars described it as follows: without adding any adhesive, the high-speed rotating round Rod Tenon combines with the wood base material in an instant (2-4 seconds) by friction with a connection technology with certain strength, it is called round Rod Tenon rotating wood welding.
(Photo source: Furniture Industry-public number, invasion and deletion)
▲Welding diagram of round Rod Tenon rotating Wood
the key point is that "high-speed rotation", "friction" and "instant joint" are undoubtedly the characteristics of this technology, but what I still don't understand is: why can the so-called "welding" be realized by doing so?
The principle is as follows:
the round Rod Tenon rotates into the tenon hole at high speed. In the contact interface, the friction between the round Rod tenon and the inner wall of the tenon hole generates high temperature, and the polymer polymer (mainly lignin, there are also some semi-cellulose) which is softened and melted, and the fiber forms a tangled net, which is fused in the melted wood polymer. When the round Rod Tenon stops rotating, cooling and curing form a welded tape and are connected together.
(Photo source: Furniture Industry-public number, invasion and deletion)
(Photo source: Furniture Industry-public number, invasion and deletion)
(Photo source: Furniture Industry-public number, invasion and deletion)
▲Appearance and microstructure of welded tape
from the above figure, we can see that the microscopic welding belts are interwoven with each other. After the wood friction welding is completed, lignin and Hemi cellulose (furfural, xylan) are formed at the "New Interface". Polymerization and cross-linking chemical reactions occur, so after the round rod and Tenon stop rotating, in order to ensure a certain joint strength, it is necessary to maintain a certain instantaneous pressure.
How to apply the rotary welding technology of round rod and Tenon?
Round Rod tenon is a common insertion Tenon in furniture industry. The joint and positioning between panel furniture parts and the joint of solid wood frame can assemble several parts together through round Rod Tenon.
In recent years, the high-speed rotating round rod and tenon wood welding technology has been applied and studied in two kinds of connection modes of furniture components directly and corners in Europe, and its structural strength and product stability meet relevant requirements.
How to use the direct combination of solid wood furniture?
Direct combination of solid wood furniture is one of the most basic assembly methods. If round Rod tenon is used for rotary welding, the result must be the most concerned problem.
The researchers selected three furniture parts, namely miter joint, lap joint and dove tail joint, to compare the mechanical properties of the rotating welding body of round Rod tenon with the rubber joint and nail joint of round Rod Tenon, the research results show that the rotating wood welding of round Rod Tenon has better strength and rigidity than that of nail joint, which is equivalent to the joint strength and rigidity of round Rod Tenon, and can be applied in furniture component assembly.
(Photo source: Furniture Industry-public number, invasion and deletion)
▲ miter at different angles and numbers
(Photo source: Furniture Industry-public number, invasion and deletion)
▲ overlapping at different angles and numbers
(Photo source: Furniture Industry-public number, invasion and deletion)
▲ dovetail connection at different angles
(Photo source: Furniture Industry-public number, invasion and deletion)
how to use the combination of solid wood furniture corners?
Corner combination is also an important part of furniture structure, which mainly includes "L" type and "T" type.
"T" connection with good performance can improve the bonding strength of furniture corners, and its strength and rigidity are very important to the quality of furniture products.
(Photo source: Furniture Industry-public number, invasion and deletion)
(Photo source: Furniture Industry-public number, invasion and deletion)
▲ mechanical properties Test of T-type structure
the "L" type combination in furniture is a common form of furniture frame connection. Because the stress point in this combination is on the wood edge, the mechanical properties of the "L" type connection parts are worse than that of the "T" type.
The experiment shows that the "L" type parts combined with mortise and tenon are not added in the connection process through a certain number of round rod and Tenon rotating welding technology, and their mechanical strength conforms to European standards.
Are there any typical technical application cases?
Yes. With the continuous development of rotary welding technology of round rod and Tenon, the research on its application to furniture production and assembly is in full swing in Europe.
For example, the minimalist abstract Z-shaped chair designed by the famous Dutch architectural design master herrit litfeld uses four beech board round tenons with a spacing of 32mm without adding any material, assembled only by Rotary welding of round rod and Tenon.
(Photo source: Furniture Industry-public number, invasion and deletion)
▲Z-shaped chair with round rod and Tenon rotating welding
(Photo source: Furniture Industry-public number, invasion and deletion)
▲ cabinet with rotary welding of round rod and tenon
(Photo source: Furniture Industry-public number, invasion and deletion)
▲ high-speed rotary friction welding machine for round rod and tenon
(Photo source: Furniture Industry-public number, invasion and deletion)
is there any prospect for rotary welding of round rod and Tenon in China?
If the technology is mature and the cost is effectively controlled, this connection technology should have a good prospect.
First of all, disputes caused by the release of toxic substances (such as formaldehyde) are sometimes exposed in the domestic furniture industry, the round Rod Tenon rotating wood welding technology without any material addition can satisfy the Chinese people's pursuit of high quality furniture quality of life;
(Photo source: Furniture Industry-public number, invasion and deletion)
round Rod Tenon rotating wood soldering strength is related to wood species. Foreign countries have carried out research and application in Beech, eucalyptus and other hard broadleaf materials, and it is also feasible to apply this technology in domestic medium and high-grade mahogany furniture;
for the application of wood welding technology in man-made Board, foreign countries have carried out research on particleboard, medium density fiberboard, plywood, directional particleboard, etc., and try to weld man-made Board furniture with round rod and Tenon rotating wood;
in furniture manufacturing enterprises, 32mm series hole processing equipment can be appropriately improved, and it is also feasible to assemble the home by rotating wood welding technology of round rod and Tenon.
(Article Source: Furniture Industry-public number, invasion and deletion)
