Attività

mig welding torchWhat is your welding torch power?

When choosing a mig welding torch for our equipment, one of the most important factors is the power of the gun, or what is the same, the maximum intensity of use that it can endure.

Most manufacturers use the maximum intensity of use as a reference when selecting the right torch, but this reference should be understood only as that, a reference. The intensity in real circumstances will be notably lower for the following reasons.

When you think of the dangers of welding, the usual suspects immediately come to mind: In addition to obvious things like harmful UV radiation during arc welding, sparks and welding spatter, or even hazards from electrical current, there are also the invisible dangers of welding, for example, by inhaling harmful welding fumes.

There are multiple ways to protect the welder from all these hazards: Wearing personal protective equipment (PPE) when welding is considered a matter of course and protects the skin and, above all, the eyes from radiation and injuries caused by welding spatter and flying sparks. Fume extraction torches, ventilated welding helmets or fume extraction systems can filter toxic welding fumes from the air and thus protect the welder’s respiratory organs.

But how can welders protect themselves in the long term against damage to their musculoskeletal system? What helps against permanently tense muscles, signs of fatigue and back pain?

An often underestimated aspect of welding is the tig welding torch itself!

Unhandy, heavy torches, which are not ergonomically adapted to the work processes, make the daily work for welders more difficult. Often long seams have to be welded without stopping and the heavy hose assembly is dragged behind or has to be lifted into the correct position.

Or when welding is done in an overhead position. Every welder knows what we are talking about: The welding material drips, the muscles are aching, the back hurts and the weight of the welding torch including the hose assembly quickly becomes a burden.

The hose assembly in particular is an important factor when it comes to weight reduction. Lightweight hose assemblies can weigh 30-50% less than a regular hose assembly, which has a significant effect. Of course, you shouldn’t skimp on the material inside, because the plasma welding torch still has to be just as powerful as before.

Using light metal components for current-carrying cables in the hose assembly instead of the usual copper ensures a significantly lower weight, makes welding more comfortable and maintains performance – that of the welding torch and that of the welder.

The position of the trigger on the welding torch also has a decisive influence, because during a long working day this trigger has to be pressed countless times. If the welding torch lies comfortably in the hand and the distance and angle between the finger and the trigger are optimally selected, less energy is needed to reach the trigger and apply the required pressure.

A ball joint at the transition between the handle and the hose assembly specifically relieves the welder’s wrist: the hose assembly is flexibly guided downwards directly behind the handle, thus reducing the leverage effect on the wrist. In addition, a ball joint facilitates oscillation during welding.

This study investigated the effects of welding current and torch position parameters, including torch-aiming position, travel angle, and work angle, on bead geometry in single-lap joint gas metal arc (GMA) welding. High-speed filming and macrographs of weld cross section were used to observe the effect of each welding parameter on the properties of the bead geometry, including penetration, leg length, and toe angle. Response surface methodology was used to establish the relationship between the welding parameters and properties of bead geometry and to estimate regression models for predicting bead geometry. Both welding current and torch-aiming position were found to have significant effects on bead geometry, with strong linearity between them and bead geometry. The coefficient of determination (R2) of the estimated response surface models was 0.7226 for penetration, 0.8802 for leg length, and 0.8706 for toe angle. Further, experimental results indicate that the estimated models are very effective.

This paper aims to develop a novel tungsten inner gas (TIG) wp-26v tig torch in order to join thin sheets efficiently. Using a narrowing nozzle (constricted nozzle) inside a conventional TIG torch can critically improve the position accuracy of the tungsten electrode and also the arc plasma characteristics and heat input density. In order to evaluate the efficiency of this new torch, weld bead appearance and cross-section images were examined by an optical microscope, scanning electron microscope (SEM), and electron back scatter diffraction patterns (EBSD). The results showed that in all cases, the weld bead profile was stable without undercut and burn-through. Full penetration weld was seen. The width of weld bead on the bottom surface was increased much in comparison to conventional TIG welding. However, the results from SEM and EBSD images indicated that in the case of low welding current, the blowholes were found out on the side of the thinner material (SS400). The penetration of SUS430 material to SS400 material was not good. It seems that no fusion of SUS430 material to SS400 at the bottom surface can be seen. Meanwhile, no blowholes were seen in the case of high welding current. The penetration was better, and the fusion was reached on the bottom surface.

This work is about the influence rule of inclination of gas cooled tig torch on the formation and characteristics of weld bead during the pulsed-gas metal arc welding (GMAW) process based on the robotic operation. The inclination of welding torch was an important operation condition during the pulsed-GMAW process, because it can affect the formation and quality of weld bead, which was the output of the process. In this work, the different inclination modes and values were employed to conduct actual welding experiments, and some influence rules can be obtained according to examine the surface topography and cross section. Then, to obtain further rules, serious measurements for the geometry characteristic parameters were conducted and corresponding curve fitting equations between inclination angles and the bead width, penetration and bead height were obtained, and the largest error of these curve fitting equations was 0.117 mm, whose corresponding mean squared error (MSE) was 0.0103. Corresponding verification experiments validated the effectiveness of the curve fittings and showed the second order polynomials were proper, and the largest errors between measurements and curve fitting equations for inclination angle under backward mode were larger than those under forward mode, and were 0.10 mm and 0.15 mm, respectively, which corresponded to the penetration and were below 10%, therefore the equations can be used to predict the geometry of the weld bead. This work can benefit the process and operation optimization of the pulsed-GMAW process, both in the academic researches and actual industrial production.

Pulsed-gas metal arc welding (GMAW) is a commonly employed arc welding process which was employed in industrial metal joining process and other relative areas [1,2,3]. In this process, the pulsed welding current generated from the welding power source is used to control the metal droplet included in the electrical arc. Using this process, stable electrical arc can be induced even various welding parameters are so small. Because the process can accurately control the heat energy of the electrical arc, the pulsed-GMAW process is more and more commonly employed for joining types of base metals [4]. Compared to the conventional GMAW process, the pulsed-GMAW process has various advantages, such as high productivity and process robustness, and obtains the products with fine grain size [5]. It can not only adjust the value and duration of base current to decrease the heat delivery, so as to avoid very large deformation and burn-off the base metals, but can also utilize the high peak current to realize the desired one-droplet-per-pulse (ODPP) metal transfer mode. The metal transfer mode can directly affect the formation and the surface of the weld bead [6]. The various merits of this technology make it being increasingly used for joining a wide variety of industrial occasions, due to its inherit advantages such as deep penetration, smooth weld bead, high welding speed, large metal deposition rate, lower spatter, lower distortion and shrinkage, lesser probability of porosity and fusion defects, and controllable heat input and all-position welding [7,8,9]. It is an advanced spray transfer process with low mean current, and the welding current is pulsed between high and low levels of short or long time intervals so that it brings the weld zone to the melting point during the pulse current period and allows the molten weld pool to cool and solidify during the background current period [7]. Hence, this process can realize a stable and controllable metal transfer process, and obtain weld beads with desired surface topography.

The evaluation of the welding quality is so important for process improvement and product optimization. Different welding processes had different evaluation criteria. For example, the nugget size or tensile-shear strength can be used to evaluate the quality of resistance spot welding [10,11]. During the GMAW process, the formation and characteristic of weld bead is the most commonly employed criterion to evaluate the quality of the operation, and this criterion involves more elements, such as crack, appearance, geometry characteristics, microstructure, and so on [12].

To meet the huge requirements of the actual industrial applications, many scholars and experts took efforts to explore the influences of the different operational conditions on the formation and characteristic of weld bead. Some relative contributions have been reported in the past decades. Rodrigues et al. [13] investigated the influences of three kinds of shielding gases and two activating fluxes on the geometry of welds produced by the tungsten inert gas (TIG) welding processes, which was other commonly used arc welding process. Shoeb et al. [14] studied the effects of some process parameters, such as welding speed, voltage and gas flow rate on the weld bead geometry, such as penetration, width and height, and in the work, mathematical equations were developed to describe the relations between the parameters and geometry parameters using factorial technique. In addition, to explore the weld bead forming rule during the double-pulsed GMAW process, our research group [15] employed the grey relational analysis method to quantitative establish the relations between some key operational parameters and the geometry characteristic parameters of the weld bead. The results showed that the average welding current and welding speed were the key elements which affected the characteristic parameters of the weld bead. Additionally, the same group [16] studied the effects of the operational parameters on the ripples of the weld bead; corresponding analyses showed that the most influential element on the distances of ripples was the welding speed, and the following was the twin pulse frequency. Moreover, recently, to increase the productivity during the actual production, the GMAW process usually collaborated with the industrial robot operation, which can significantly improve the accuracy of the real time control and make the operations more and more convenient. Aviles-Viñas et al. [17] proposed a real time computer vision algorithm to extract training patterns in order to acquire knowledge for predicting specific geometries, and the proposal was implemented and tested by an industrial KUKA robot and a GMAW type machine within a manufacturing cell. Chen et al. [18] employed a welding robot to acquire and optimize the weld trajectory and pose information, based on a laser sensor, charge-coupled device and other auxiliary instrument. Yang et al. [19] used an arc welding robot to detect the welding quality based on three-dimensional reconstruction using a special algorithm, and the results showed the system can quickly and efficiently fulfill the detection task of welding quality. These works denoted that using an industrial robot combined other technologies, many tasks which cannot be accomplished by traditional operations can be realized.

Despite that many reported contributions concerned that the influences of different operational parameters on the quality of weld bead, the relative works were mainly about the welding current, robot welding speed, and other common real-time control parameters. However, as a special and important operational condition, the inclination of the welding torch can also affect the formation and surface topography of the weld bead, because the welding torch is an executive component which is directly related to the energy delivery from the power source to the objective base metal. In general, the inclination of the welding torch was difficult to accurately adjust in the conventional GMAW operation because relative reported contributions were so few. Recently, as there has been fast improvement of the welding process based on robotic operation, online controlling of the inclination can achieve a high accuracy. Hence, in this work, an industrial robot was employed to accurately control the inclination and detailed influence rule of the different modes and values on the formation and characteristics of the weld bead during the pulsed-GMAW process can be seriously examined, in order to improve the GMAW process and obtain weld bead with high quality. To obtain the detailed influence rule, corresponding curve fittings between inclination angles and geometry characteristic parameters were also conducted. Corresponding verification experiments validated the accuracy of the curve fittings. The work is supposed to serve the academic researches of this type of metal joining technology, and promote the process improvement in actual industrial production.