One of the most commonly used in the production of mass and small-scale products methods of joining parts is welding. With its help, you can assemble almost any pairing of elements - tee, corner, end and lap. Over time, the technological methods by which metal structures are welded are improved, becoming more efficient.
Classic welding methods
Standard methods of welding metal elements imply the use of two main sources of energy: a gas flame or an electric arc.
Gas and arc welding can be automatic, semi-automatic and fully manual. The latter option involves the formation of a weld only with the master’s own hands. In addition, manual arc (RD) welding of metal structures includes manual control of the processes of feeding the electrode, or filler wire, and the process of welding parts.
Manual mode is most effective only in domestic conditions. When using it, they mainly use submerged arc welding technologies, gas soldering, or the classical method of electric arc welding.
The first option - automatic welding - is based on the process of applying to the seam area without the direct participation of a person. All work is done by a special mechanism that is pre-configured. Naturally, the range of functions for this unit is very limited, but this significantly reduces the cost of finished products, so that it becomes very popular in large-scale production.
The assembly of metal structures, welding in automatic mode allows the use of contact technology, including heating and pressure testing of elements, stun welding and other “manual” methods. The only difference is that it is not the master who rules it, but the specially created and programmed robot.
Semi-automatic mode involves the imposition of a weld by the master, but the electrodes or wire are automatically fed into the work area, which significantly increases the productivity of the work on the site.
In this mode, almost any technology for welding metal structures is used, using non-meltable electrodes, gas fluxes and automated feeding of filler wire into the heating zone. In everyday life and small-scale production, semi-automatic welding of metal structures is the most profitable and effective version of the technical process.
Technological innovations
In modern welding, not only a superheated gas flame and an electric arc are used to connect metal parts, but also the thermal effect of friction, laser energy, ultrasound and even the power of electron beams.
Simply put, the welding technology itself is constantly being improved. Regularly invented new ways to implement this technical process. The following types of welding can be attributed to such innovations - plasma, thermite, and electron beam.
Using thermite technology, welding of critical metal structures is carried out, the components of which are melted along the seam during combustion of a special mixture introduced into the junction. Termite is also used to eliminate defects and cracks in ready-made metal structures by the "influx" of metal.
Plasma welding is carried out under conditions of transmission of ionized gas through two electrodes. The latter acts as an electric arc, but at the same time its efficiency is much higher. Superheated gas is used not only for welding metal, but also for cutting it, so that an automatic and multifunctional welding system can be created around the plasma generator.
Using electron beam technologies, deep seams are welded up to 20 centimeters, while the width of such a seam will not exceed one centimeter. The only drawback of such a generator is that you can work with it only in a complete vacuum. Accordingly, such technology is used only in highly specialized areas.
To assemble small-sized metal structures, it is most effective to use gas or electric arc manual welding. Semi-automatic device pays off when working with small-scale objects. Modern welding technologies, respectively, are used only in mass production.
Welding of metal structures: features
Welding technology is used not only when working with metal, but also with various polymers. The whole process is heating and deformation of the surfaces, which are then combined into one.
All welding work consists of two main stages: assembly and connection.
The most time-consuming and difficult is the first stage. Reliability and structural strength largely depends on compliance with all requirements. More than half of all the time falls on the assembly of components.
Ensuring the correct assembly of metal structures
High quality, durability and reliability of the final result is ensured by compliance with certain requirements.
- When choosing parts, you must strictly adhere to the dimensions laid down in the project.
- The gaps must be of a certain size - with their increase, the strength of the finished product will significantly decrease.
- Angles are measured and controlled using special tools. It is important that they fully comply with those specified in the design, otherwise there will be a risk of collapse of the entire structure.
Welding advantages
In addition to the fact that welding metal structures significantly saves time for all work, and the seam is high-quality, the process has other characteristics:
- The mass of the finished solder does not change, since only two main parts are used, which saves material.
- No restrictions on the thickness of the metal.
- The ability to control and adjust the forms of metal structures.
- Availability of welding equipment.
- Possibility to use welding for repair and reconstruction.
- High tightness and durability of joints.
Additional points
In order for the resulting design to be of high quality and reliable, it is necessary to comply with all technological requirements.
Properly selected materials, components and equipment allow you to get high-quality seams. Otherwise, the finished design not only loses its presentation, but also its operational characteristics.
Weld defects
To obtain accurate dimensions and simplify the work when creating a metal structure, a conductor is used. Despite this, the RD welding of metal structures, cranes can turn around during the process with certain defects - influxes, cracks, burns, porosity, burns, undercuts, and others.
Causes of defects
Sagging is formed on metal structures as a result of leakage of molten metal. Most often, such a defect is typical for work on creating horizontal seams. They are removed with a hammer, and then the product is checked for lack of fusion.
The causes of the burnout may be poor-quality processing of the edges of structures, an increase in the gap, low speed of work and low flame power. Eliminate it by cutting and welding the seam.
The lack of penetration is considered the most dangerous type of defect, since it negatively affects the reliability and strength of the weld. Such areas are completely eliminated, metal structures are cleaned and re-welded.