Little construction is not complete without the use of welding, it is used in the construction of various types of buildings and structures, ranging from offices and ending with houses, skyscrapers. With its help, several components are combined into one. In the process, a weld is formed. It provides reliability and durability. The seam can last for a long time if no mechanical forces damage it.
The weld is able to connect various metal parts, made not only from a homogeneous material, but also from alloys. However, to perform this process, it is necessary to select a specific welding technology and consumables.The worker who will connect the parts must have high qualifications and work experience. It takes into account the peculiarities of the metal and connects it in such a way that when it is subjected to a load, it will not collapse.
The designation of welds, as well as their types and places of use are specified in the regulatory documentation. This information is used for various technical documentation. It is indicated in special teaching aids, which are used in training welders or improving their skills. Describing the welds GOST 5264-80 is the main guide document. That is, from it is taken all the information for tutorials.
It is possible to determine the type of connection without looking at the documentation. The designation of welds in the drawings anywhere in the building structure is carried out with the help of lettering. So, these types of welded joints are distinguished by letter designations:
- "C" - butt;
- "H" - overlap;
- "T" - tavrovoe;
- "U" - angular.
The weld is classified according to several criteria. So, by the form of the final cross-section are divided:
- butt joints - when connecting metal parts must be in the same plane;
- corner - products must be at a certain angle to each other;
- slotted - when welding metal parts fall on each other. In this case, the top product melts completely, and the bottom partly.
The next indicator is the configuration. Welds (GOST 5264-80) can be straight, curved and annular.
Welding can be performed in several ways. It is worth noting the application of a continuous seam or intermittent. In the first case, the weld may have a length of 300 mm or more. The second embodiment is performed in extreme cases, as the seams are staggered. The connection also depends on the technology of the operation. Welding is performed with or without additional gas.
When performing construction work, the seam can be performed a different number of times. That is, it can be single and multi-layered. This is done to strengthen the connection and increase its strength characteristics. In the process, additional fusion may form on the joint. According to this indicator, the seams are classified as normal, reinforced and weakened.
As a rule, such compounds are not separated. They can be performed in various ways and combine several types of work. It depends on the qualification of the welder as well as the quality of the consumables.
The quality of welds depends on the chosen technology of implementation, as well as the qualifications of the worker. Metal parts are attached to each other through the melting process. When using arc welding, they should be located in the same plane.
Such parts may have different shapes and state of the edge. The latter is processed depending on the thickness of the elements. When connecting products with different thicknesses, it is necessary to adjust a large sheet to a smaller one. In this case, the seam will be reliable.
In accordance with this characteristic by type of edges, welded joints are:
- with skewed edge (seam thickness should be 5 mm);
- with curvilinear;
- u-shaped hem. The thickness of the seam should be from 20 to 60 mm;
- an edge with an X-shaped form (thickness of a seam should be from 12 to 40 mm).
One of the main positive properties of welded joints is low voltage. This means that they are not subject to bending and destruction. That is why this type of compound is often used. In addition, the process consumes the minimum amount of metal. To perform high-quality welding, you must carefully carry out the preparatory stage. Let us consider in detail the characteristics of compounds of different types.
To get a T-joint, it is necessary to fasten two parts, which will be located relative to each other perpendicularly. The designation of welds in drawings of this type is represented by the letter T.
Welds can be located not only on one side, but also on the other.
It all depends on where it will be applied, and what requirements are imposed on it. This type is used to construct various columns and frames.
If a certain place will not be a significant load, use an angled view of the connection. Most often it is used in the manufacture of various containers. This should be done such a requirement: to design last longer, the metal thickness should not exceed 3 mm. For the manufacture of such compounds one detail is applied at a certain angle to each other and are welded on both sides. This is done to ensure that moisture does not fall and destroy the structure. The weld in the drawing is denoted by the letter U.
The last type of connection is overlapping, where the parts are attached perpendicular to each other. A seam is formed on the side of the structure. In addition to this procedure, it is necessary to secure the connection by fusing. This consumes a significant amount of metal. In this case, the thickness of the structure should not exceed 12 cm. In order not to get moisture inside the product, the metal is welded on both sides. The designation of the welds of this type is indicated on the drawings by the letter "H".
In the manufacture of any seam using a point welding method. An exception is the case when welding is necessary. Then the seam is made round.
Arc welding can be performed by two methods: manual and mechanized. It all depends on the thickness of the metal. With the manual method, weld elements with a thickness of no more than 4 mm, and with a mechanized method - 18 mm. Details of large thickness can be processed manually. But it is necessary to further process the edge.
Gaps can form between two welded elements, as well as deviations of parts at a certain angle, that is, a bevel and groove angle is formed. To perform high-quality seam, you must correctly determine the bevel angle. This indicator indicates the availability of the arc. Depending on the type of connection, indicators of this angle are in the range from 20 to 60 degrees, including the minimum error.
In the process of welding burns may occur. The main reason is the untapped edge. Welding is not possible if the distance between the two metal parts is too large.
To determine how the weld should be determined with the material and with the degree of difficulty. During the construction of any building will prepare the documentation. It should be made information about the material processing of metal parts. The legend of the welds are indicated in the relevant drawings. They can be seen in the photo below.
As can be seen, the shade of the detail is significantly different, and the thickness of the seam (joint) itself is half the thickness of the others.
Their quality can be controlled in many ways and ways. So, the following methods are applied:
The most common is visual inspection of the finished connection. This is the easiest and most affordable way that does not require material costs. Every weld undergoes visual inspection, regardless of future operations. But you can perform other checks. With the help of external inspection to determine the many visible defects caused in the process. Thanks to him, find various fusion and beading. Visually, they are almost invisible. To determine them, you must use a special magnifying glass, which increases the surface tenfold.
In the course of this operation, not only visible defects are determined, but also they are engaged in checking and measuring pre-prepared edges. In the mass production of welded joints, special templates were developed. They allow you to measure the seam in a short period of time. The remaining methods require financial investments in individual substances and equipment.
So, we found out what is a weld. Requirements for him are pretty high, since it is he who is responsible for the reliable connection of metal structures.