A welding seam tracking visual sensor based on laser scanning is designed to solve the problems, such as indistinct image, difficulty in processing image etc., caused by serious arc light interference during welding. This visual sensor is mainly composed of a scanning motor, a linear-array CCD, a scanning rotating mirror and a semiconductor laser. Because the sensor measurement precision relies...

Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd : YAG laser device (Fotona Fidelis III, λ = 1064 nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- a...

In this study, a three-dimensional (3D)finite elementmodel is developed to investigate thermally induced stress field during hybrid laser–gas tungsten arc welding (GTAW) process. In the hybridwelding case, we focus on the GTAWprocess sharing commonmolten poolwith laser beam and playing an augment role in thehybridweldingsystem.Anexperiment-based thermalanalysis isperformedtoobtain the temperatu...

The most common problem of welding dissimilar metals (DMWs) with respect to residual stresses is the differences in the coefficient of thermal expansion and heat conductivity of the two welded metals. In the present work, a CO2 continuous laser welding process was successfully applied and optimized for joining a dissimilar AISI 316 stainless steel and low carbon steel plates. The Taguchi approa...

Welding-induced distortion is an intrinsic problem arising due to the mismatch of thermal expansions in the weld and surrounding material. The distortion can be minimized through the pre-process, in process, or post-process methodology. In the present paper, the laser forming (LF) technology is utilized for the post correction of the welding-induced distortion. Three types of weld paths are app...

There are two laser welding mechanisms, keyhole mode and conduction mode. Keyhole welding is widely used because it produces welds with high aspect ratios and narrow heat affected zones. However keyhole welding can be unstable, as the keyhole oscillates and closes intermittently. This intermittent closure causes porosity due to gas entrapment. Conduction welding, on the other hand, is more stab...

The Nd:YAG laser welding was used to join the binary NiTi alloy wires with different compositions(Ti–50.0 at.%Ni and Ti–50.9 at.%Ni) which had the same diameter of 1 mm. The wires were welded with different parameters, including impulse width and welding current. The aim was to assess the influence of the laser-welding process on the microstructure and mechanical properties of the welded joint ...

The purpose of vision-based sensing devices in the welding industry is to electronically replicate the role of a skilled welder and emulate the human eye with a light-sensing device such as camera and the human brain with a computer algorithm that interprets the images. Just as an optical feedback from human eye guides the human welder, optical feedback in this electronic system would be used t...

Schlieren interferometry is found to be an alternative tool for temperature measurement during thermoplastic laser welding with regard to methods based on thermocouples or optical pyrometers. In fact, these techniques are not easily applied when materials to be processed have reduced thickness, negligible heat conduction, and low emissivity, as is the case of welding high-density polyethylene f...

The in-process monitoring and real-time control of the penetration depth during laser welding is evaluated. An optical collimator collects the optical emission for measurement with a fast spectrometer. The sensor data are used to calculate the electron temperature and subsequently to determine the weld quality of overlap welds in AISI 304 stainless steel sheets performed both with CW Nd:YAG and...