Wood welding is an environmentally-friendly and very quick technique to yield wood joints in just a few minutes and without using any adhesives. The only limitation of welded wood is that the joint ...is suitable only for interior use. Exterior use, or use in an environment with varying
humidity requires water resistance of the welded joints. An investigation was performed to determine the effects of welding parameters and wood properties on water absorption in the weldline and how to reduce it through controlling the production parameters. The influences of welding pressure,
welding time, and heartwood/sapwood on water absorption in the weldline of Scots pine (Pinus sylvestris) joints were investigated. Specimens composed of two pieces of heartwood or sapwood, each of dimensions 200 mm × 20 mm × 20 mm, were welded together to form specimens
of dimensions 200 mm × 20 mm × 40 mm. The specimens were allowed to stand in 5-mm-deep tap water and then they were taken out of the water one at a time and scanned in 10-min intervals until the first crack appeared in the weldline. An X-ray Computerized Tomography scanner was
employed to monitor water movement and density change in weldlines during water absorption-desorption. All three evaluated parameters showed significant effect on water absorption. Samples of heartwood welded by 1.3 MPa welding pressure and 1.5 s welding time showed the lowest water
absorption.
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Exterior use of welded wood laminates without further treatment is not recommended. Frictional welded joints have poor resistance to moisture variation, especially to drying. Therefore, application ...of welded woods is limited to interior use without exposure to highly variable air
humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood/sapwood on weldline density of Scots pine (Pinus sylvestris) joints were investigated. Interdependence between density and water resistance of weldline (in terms of crack time)
was also studied by comparing the results of this investigation with those of the earlier studies. Specimens composed of two wood pieces, each measuring 20 mm × 20 mm × 200 mm, were welded together to form a specimen measuring 40 mm × 20 mm × 200 mm by a vibration movement
of one wood surface against another at a frequency of 150 Hz. An X-ray Computerized Tomography scanner was used to measure weldline density. Weldlines of sapwood produced by 1.3 MPa welding pressure and 1.5 s welding time showed the highest density. No correlation between weldline density
and crack time was evident.
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The optimum phasing of the electrodes and the conditions of four-arc submerged-arc welding of thin wall pipes (6-10 mm), resulting in the height of the convex region and the width of the welded joint ...not greater than 2.5 and 20 mm, respectively, are determined.
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Wood grain orientation differences in the two surfaces to be bonded yield bondlines of different strengths in linear wood welding. End-grain-to-end-grain welds of good strength were obtained for both ...beech and oak woods. The tendency to defibration in end-grain-to-end-grain welding
indicated that for wood densities higher than or equal to the density of beech wood, end-grain-to-end-grain welding is possible and yields sufficient joint strength. A higher density seemed to yield a stronger joint. Wood pieces having other grain directions were also vibration welded. These
were: (1) with the grain perpendicular to the wood longitudinal grain direction, (2) with the grain of both wood pieces at 45° to the wood longitudinal grain direction and (3) with the grain of both wood pieces at 45° to the wood longitudinal grain direction but at 90° to each
other to form a fishbone-like pattern. The first of these yielded results comparable to end-grain-to-end-grain welding. The other two yielded much lower strength of the joints, indicating that fibre orientation in the interphase composite formed during welding had considerable influence on
joint strength. These differences in joint strength have been explained by the very marked effect that anisotropy of the interphase composite has on fibre/matrix composites.
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A simple and easily understandable model was developed for predicting the relative importance of different factors (composition of the steels and welding processing conditions) in order to obtain an ...efficient welding joint. An application on the interstitial free (IF) steel sheets welded by LASER, TIG and also by resistance spot welding (RSW) for automotive industry as well as an application of multipass welds of structural steels for offshore and pressure vessel are given in this study.
This model is based on thermal, metallurgical and mechanical and also in situ test conditions. It operates easily on the PC type computer. This approach is an efficient way to separate the responsibilities of the steel maker and welding designer for increasing the reliability of the welded structures. The construction of welding limit diagrams (WLD) that allows us to predict the values of the parameters in order to obtain an efficient welding joint is presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The authors proposed the switch back welding method to make the stable back beads in the first layer weld during one side multilayer welding. In the proposed welding method, the torch motion is ...important to control the weld pool, i.e., the welding torch is moved backward and forward like switch back. It is important to investigate the behavior of the weld pool to get the optimum welding parameters such as the traveling speed, the forward distance, the backward distance, the welding current and so on. There are many welding parameters. In order to find the optimum welding parameters, the numerical simulations are useful method instead of the welding experiments. Since the deposited metal is considered in the numerical models of the welding in the thick plates, the numerical analysis becomes complicated. In order to simplify the analysis, the authors discussed the numerical simulations of the welding in the thin metal plates because the effect of the deposited metal can be minimized. First, the fundamental welding experiments were carried out in MIG welding. By using the experimental results, the numerical models in the switch back welding are determined. Next, the behaviors of the temperature are investigated under the change of the traveling speed and the backward distance. If the traveling speed is constant in the switch back welding, the weld pool size may sometimes become big. In this case, the burn trough may take place due to the flow in the weld pool. When the traveling speed of the forward movement is faster than backward movement, the weld pool length becomes shorter than the case of the constant traveling speed. Moreover, if the backward distance is longer than half of the forward distance of the switch back welding, the authors can obtain continuous back bead regardless of the disturbance such as the variation of the arc length, i.e., the stability of the weld pool is increased. The switch back welding method is useful to make the stable back bead in the MIG welding.
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