What is a weld leg

Welding leg and welding seam: what is it in simple words, table and measurement

Welding joints are characterized by several parameters. These include: the presence of cavities, thickness, convexity, width, etc. Depending on the type of joint - straight or angular, there are various criteria and parameters.

For a rectangular joint, one of the main indicators is the leg of the weld. This criterion determines the strength characteristics of the joint, the heating area of ​​the parts during cooking, etc.

Types of seams during the welding process

The place where parts of metal parts meet is called a weld. It is formed due to the melting of the contacting parts of the product and their subsequent cooling.

Depending on the spatial arrangement of parts, butt and fillet welds are distinguished. In the first case, the docking is carried out in one plane. The metal parts are positioned with their ends facing each other, and the welding itself is carried out in a horizontal position.

The influence of welding mode on the shape of the seam.

In addition to the types noted above, the connection can be a T-joint or an overlap. The first type involves the arrangement of parts normal to each other with the letter “T”. It can be located either on one or both sides.

In a T-type joint, the parts are often placed obliquely to each other. This arrangement reduces the spreading of the bath metal. As a result, a seam is formed between the sides of the product.

Overlapping is used to join sheets of small thickness. Welding in such cases can also be carried out on one or both sides.

So, what is a weld leg? This criterion determines the shortest distance from the first part to the corner joint on the second. To better understand what a leg is, it’s easier to say that it is the side of the largest isosceles triangle inscribed in the cross section of the connected parts.

This parameter is very important and determines the quality and reliability of welding.

This criterion affects:

• product strength;
• calculation when welding products of different thicknesses;
• indirectly characterizes the deformation of products due to their heating during operation.

When choosing this parameter, you need to understand what the welding seam should correspond to. Depending on the type of product, their thickness, as well as the scope of application, the optimal value of the leg is calculated.

Seam geometry

The weld leg must comply with the geometric parameters specified in the regulatory documents. They are also used to carry out mathematical calculations of the main geometric characteristics using formulas and tables.

The geometry of the welding joint is determined by the type of connection. The cross-section of the joint will depend on the type and size of the parts being welded.

In production, all parameters and strength of joints are calculated using formulas. At home, you can limit yourself to ready-made templates.

The most convenient and widespread is the universal template, which is a set of plates fastened together. Applying them alternately to the surface of the products, select the one that fits most tightly to them.

When welding metal structures that do not require high strength and reliability, the minimum weld size is determined based on the thickness of the metal.

It is very easy to assess contact by eye. It usually corresponds to the thickness of the metal. So, for welding products with a thickness of 7 mm, the leg should also be 7 mm. You can make more accurate calculations using the appropriate formula.

After performing the calculations, select the required current and voltage, and then begin welding.

Leg selection

This parameter directly determines the reliability of manufactured parts. This is explained by the area of ​​their connection and the filling material. If everything is done correctly, then the load on the structure will be distributed evenly over the entire contact area. Such a product can withstand strong impacts, etc.

At the same time, a large seam does not always indicate high reliability. In this matter, subtle calculations of loads are required. The metal must not be overstressed, otherwise the part may simply bend and become unusable.

In connection with the above, the welding joint must be selected in accordance with the tasks assigned and the materials being welded. The result of the work will depend on this.

In order to choose the right leg in a given situation, you need to understand what properties it should have. First of all, you need to pay attention to its shape. It should be homogeneous and uniform. In this case, even visual control is sufficient.

The seam height should be the same along the entire contact area. Its width should also be the same. This will allow the loads on the metal structure to be distributed evenly along the entire connection.

An important parameter is its homogeneity. Typically, materials with different compositions do not weld well. To obtain high-quality welding, it is necessary to choose the right electrodes.

The contact must have the correct geometric location and cover the fastened products as much as possible.

An equally important parameter is the penetration depth. The workpieces must be in contact over the entire possible area, otherwise they will not be able to withstand significant loads.

The seam is calculated depending on the type of parts being welded. To make the right choice, it is necessary to take into account all the parameters of the materials: dimensions, width, etc. The resistance characteristics of the connection depend on its thickness and length.

It is the length that is the main criterion for calculating and choosing a seam, since strength depends on it. If the length is sufficiently large, consumption of product materials and their deformation may occur.

Correct use of templates will help avoid the appearance of defects characteristic of welding. In most cases, it is enough to use a universal template to obtain a high-quality and reliable metal structure.

How to measure the leg of a seam?

To control the work performed, it is necessary to accurately measure. This will allow you to determine whether errors were made in the calculations and evaluate the quality of the product.

The required size of the joints is measured in accordance with geometric formulas. To do this, it is enough to calculate the leg of the maximum equilateral triangle inscribed in the cross section of the contact between the parts.

Depending on the situation, the calculation is performed differently. For example, if the welding was done by overlapping sheets up to 4 mm thick, then they try to make the leg of the same thickness. In other cases, its size should be 40% of the thickness.

Bottom line

The weld leg is an important characteristic that determines the most important parameters of the resulting product. The durability, quality and reliability of welding directly depends on this criterion.

You can make a connection in accordance with all standards using ready-made templates. They will greatly simplify welding, eliminating the need for additional calculations.

In many cases, it is enough to follow the rule that the leg of the joint must be equal to the thickness of the materials being welded. However, this applies to designs that do not require high reliability.

Source: https://tutsvarka.ru/vidy/katet-svarnogo-shva

How to calculate and measure a weld leg

In industry and manufacturing, most metal structures are formed as a result of welded joints. In the construction industry, mechanical engineering and automotive industry, these connections are constantly subject to enormous stress. It is possible to obtain high quality welded joints only with proper calculation of its parameters.

The technology of the welding process is quite complex; it is filled with a number of mathematical formulas that reflect methods for calculating parameters. Today, the master’s task is simplified as much as possible, since there are special programs that are ready-made calculators for calculations.

In addition, tables of calculated values ​​have been developed corresponding to one or another type of connection, material of construction, and its geometry.

One of the calculated parameters is the leg of the weld. And if some values ​​can be averaged, others can be taken ready-made from tables, then the leg will have to be calculated independently. This is why many questions arise about the essence of this parameter. We will give a precise definition later, since a number of related issues need to be addressed first. We only note that this parameter directly determines the strength of the weld.

Without going into details, we are inclined to believe that there is no need to calculate the geometry of the seam, since the maximum values ​​of all parameters will improve the strength. This statement is incorrect, since, for example, an excessively wide seam can lead to overstresses in the metal or to its deformation, which will significantly worsen the technological parameters of the connection.

• Welded joints
• Geometric parameters
• Calculation
• Control methods

Welded joints

To date, more than 150 methods of connecting parts using electric welding have been developed and mastered. But the technology does not stop there, and various innovative methods are constantly being introduced.

Almost all attention is focused on the weld, as the area of ​​​​the junction of two metals, formed during their crystallization. Depending on the relative orientation of structural elements relative to each other, several types of welds are distinguished.

In the most trivial classification they are divided into corner and butt.

• Corner joints are formed with T-joints, cross joints or directly corner joints. Such seams are formed after one-sided or two-sided cutting of the edges. The cutting method depends on the dimensions of the structure. Such joints can be divided into continuous and discontinuous, depending on the type of longitudinal section.
• A butt joint involves welding two products adjacent to each other at their ends. An overlap seam is a special case of a butt joint. The edges of the parts can be beveled or remain straight. The most common are horizontal seams. If the thickness of the parts does not exceed 8 mm, the edges are not cut.

Geometric parameters

In order to start talking about calculating parameters, you need to clearly know their definitions. Unfortunately, dry scientific phrases do not always give the idea that, for example, a novice master wants to see. A striking example of one of these terms is weld leg.

According to the definition, the leg of a seam is the side (leg) of the largest isosceles triangle that can be inscribed in the cross section.

The above definition is so full of mathematical terms that even if you wanted to, it is difficult to understand what this value is. Let's look at the illustration.

Firstly, we note that we can only talk about a leg if there is a corner connection. Secondly, in our concept, a leg is a side of a right triangle. Here, a right triangle is highlighted in purple, which theoretically should be isosceles, according to the requirements for welds.

In practice, this triangle does not always have equal legs, which, of course, indicates a defect. That is why this parameter must be calculated and the resulting value adhered to.

By cross section we mean a section of a part with a plane perpendicular to the seam. From the figure the meaning of the word “greatest” in the definition also becomes clear. But what to do if the connection is not made at a right angle. In this case, too, we are talking about a certain leg, although an error is introduced into its calculation, and it is even more so the more the angle differs from the right angle. Now let's give a more clear definition.

A leg can be called the distance from the plane of one part to the extreme boundary of the weld on the plane of another part.

The weld leg alone is calculated extremely rarely, so we will give an example of other important parameters that are taken into account when carrying out welding work.

The figure shows the following values:

• S – part thickness;
• e – width of the weld;
• q – seam convexity;
• h – penetration depth (measured from the plane of the part);
• t – weld thickness;
• b – gap between the edges (its value depends on the method of cutting the edges);
• k – leg;
• a – seam thickness (for corner joint);
• p – seam height (for corner joints).

Calculation

In a strict sense, to determine the size of the weld leg, it is necessary to take into account a number of factors. The most significant of them is the thickness of the workpiece. Even a novice craftsman knows that the geometry of the weld directly depends on the required penetration depth. This relationship becomes somewhat more complicated if you have to connect two parts of different thicknesses.

Additional factors include such as the position of the electrode, the type of connection, and the physical properties of the metal. A complete calculation of a welded joint involves the use of a number of complex formulas. In practice, if the metal structure will not be subject to ultra-high loads, simplified calculation principles are used.

For example, when connecting two parts of the same thickness, the leg is considered equal to the edge of the part. If the thickness of the material is different, then they are guided by the parameters of the thinner workpiece. Let us remind you once again that errors in calculations lead to undesirable consequences. An excessively small leg degrades the strength of the weld, while a large leg can cause internal stress in the metal.

The above calculation method is valid for average material thicknesses. An increase in thickness leads to a violation of the linear relationship between these parameters. Sufficiently thick parts are welded with a seam to a leg, the size of which is 40% of the thickness. As can be seen from the example, it is problematic to observe such a complex relationship; however, the leg size is a value defined by the GOST 5264-80 standard.

In some cases, the approximate value of the leg gives too large an error, so it is customary to use a simplified formula. They look like this:

T=Scos45°, where T is the size of the leg, and S is the width of the seam. Since we illustrated the geometric parameters, in our notation this formula will look like: K=ecos45°. Considering that the cosine of the angle is a constant value, we come to the conclusion that in this case the leg is linearly “tied” to such a parameter as the width of the weld (but not the thickness of the edge).

Control methods

Welding seam control is an integral part of the technological process. First of all, the connection must be examined for resistance to destructive loads. Forms of control can be different. They depend on the principles on which they are based.

Advanced techniques include radiography, x-ray, gamma ray, ultrasonic and eddy current testing. Magnetic probing should also be added here, as well as the capillary method of examining seams.

The presented types of control require expensive equipment and cannot always be implemented, especially in small-scale production conditions.

A ready-made template can serve as a handy device for measuring legs. To be precise, it is not just one template that is of practical importance, but a whole set.

In its simplest design, the template is a set of plates held together at one end. At the other end there are slots corresponding to the shape of the cross section of the seam. The master one by one applies the templates to the workpiece and determines the most appropriate one. Each template is marked with the size of the corresponding leg.

There are several other devices that, by their operating principle, represent templates, only the way they measure legs is slightly different. The Krasovsky template is designed to determine the gaps between workpieces.

Universal welder's template (UNS-2) - a set of plates with cutouts. The length of the legs can be determined by the shape of the convex hypotenuse. The Marshak-Usherov template allows you to measure not only the leg, but also determine the root of the seam.

This device is considered the most versatile of all those described above.

Source: https://svarkoy.ru/teoriya/katet-svarnogo-shva.html

Welding leg: how and what to measure

The geometric parameters of the weld, along with the correctly selected mode, have a significant impact on strength, as well as durability. In the case of joining two parts end-to-end, the main geometric characteristic is the width of the seam bead. In the case of fillet welding, the leg takes its place.

Weld leg

What is a weld leg

The cross section of the corner suture bead is an isosceles right triangle. The hypotenuse runs along the surface of the suture material, and the legs run from the edges of the weld joint to the top of the corner.

The dependence of strength on the size of the leg is not linear. If the value is too small, the strength will be insufficient due to the small cross-sectional area; if the length is too large, the excessive amount of deposition can cause deformation of the workpiece metal. In addition, an overestimated value leads to increased consumption of welding materials and electricity. In addition, the unit cost of welding work is increasing.

During the design and technological preparation of production, the optimal value of this parameter is selected. If parts of different thicknesses are connected, the seam leg is selected according to the thinner part.

Weld dimensions

After welding, it is necessary to check whether the dimensions of the actual connection correspond to the design ones. For this purpose, special sets of templates are used - cathetometers.

Weld geometry

The geometry of the butt joint is completely described by the following set of parameters:

• width;
• thickness;
• gap between workpieces;
• deepening the welding zone;
• elevation of the surfacing area above the plane of the workpiece.

When welding at an angle, a modified set of parameters is used:

• weld leg;
• thickness of the surfacing zone, equal to the sum of the calculated height and elevation;
• elevation of the surfacing zone;
• design height.

Geometric parameters of the weld seam

The calculated height is the length of the segment restored perpendicular to the hypotenuse of the roller from the point of maximum penetration.

Properties

Having gained an idea of ​​the geometric parameters, you can understand the properties of the welded joint. The main properties are:

• uniformity of weld bead surfacing;
• uniformity of surfacing;
• penetration depth.

Uniformity means the constancy of geometric parameters along the suture line, first of all:

• height of suture material;
• its width.

If in any place the width turns out to be less than the design one, then during operation of the product under external load mechanical stresses will concentrate. At this point, structural failure is most likely.

Uniformity is the absence of welding defects, such as porosity or inhomogeneity of the suture material.

Uniform weld seam

Compliance with the design welding depth, its constancy ensures a given area of ​​fusion of the workpieces, which guarantees the ability of the structure to withstand heavy loads.

Selecting a weld leg

Determination of the length of the weld leg during welding is carried out for each specific product. Should be considered:

• thickness of welded workpieces;
• their material;
• one-sided connection or two-sided (on how many sides will the corner be welded);
• characteristics of electrodes or wire.

The length must be sufficient to ensure the specified welding strength. Extending the length is also unacceptable.

Overestimation leads to increased consumption of materials, increased labor intensity, and also makes the structure heavier. To facilitate the selection of length, based on practical experience as well as scientific research, standard templates have been developed for each type of welded joint.

How to measure

To check the quality of the work performed, it is necessary to measure its main parameters. Measurements are carried out using sets of specially calibrated plates - cathetometers. They are applied alternately perpendicular to the line of suture material until a complete fit is achieved.

Cathetometer

If a cathetometer is not at hand, measurements can be made using a caliper and a square. The square is applied to one of the parts so that its top rests against the top of the welding bead. The caliper probe is lowered from behind the square to the other top of the roller. The reach of the probe will be equal to the desired length.

The accuracy of such measurements will be somewhat lower, and it will take much more time to check the welded joint, especially a long one.

Why do you need a calculation?

It would seem, why even bother with calculating and measuring the leg of the welding seam? Weld more metal - the welding will take centuries. This approach has the right to exist only when welding the frame of a fence around a summer cottage. If the surfacing height is too high, the opposite effect can occur:

• If the surfacing thickness is exceeded, the heating zone and the volume of molten metal expand unreasonably. Parts may be bent.
• The increased consumption of welded materials and excess of planned labor intensity will make welding work economically ineffective, especially when producing large series of products.
• When welding parts of different thicknesses, the length is selected according to the thin part to avoid its deformation.

Underestimating the length or too narrow a bead will not provide sufficient welding reliability. Therefore, calculation is extremely important for creating durable and economical connections.

How to make a calculation

In practice, approximate calculation rules are used. According to them, the thickness of a thinner workpiece is taken as the parameter value.

The exact calculation is performed using the formula:

Т=S×cos(α),

• where T is the fillet weld leg;
• S is the width of the roller between the parts;
• α is the angle between the plane of the part and the hypotenuse of the roller section.

In most cases, the angle is taken to be 45°, its cosine is 0.7.

and the formula simplifies:

T= 0.7×S.

After carrying out the work, be sure to check the dimensions of the actual suture material for compliance with the calculated ones. Determination of the leg of the weld is carried out using a cathetometer or caliper.

Source: https://stankiexpert.ru/spravochnik/svarka/katet-svarochnogo-shva-kak-i-chem-pomerit.html

What is the calculation of a weld leg?

The quality criteria for a seam when [welding metal parts] are varied—several parameters influence the strength and durability of the joint. Welding corner structures (corner connection) requires the correct size of the contact point and the influx of metal - calculating the leg of the weld using the formula. We will tell you what the requirements and criteria are in this article.  

Weld quality and leg definition 

When assembling a metal structure, joining parts by welding is considered one of the most reliable technologies.

The reliability and strength of the weld depends on the distribution of forces across the metal, and this in turn is determined by the geometric parameters of the joint zone.

The peculiarity of the technology is that the joint is filled with metal, and during its cooling the weld pool acquires a single structure. The integrity and connections further depend on the ability of this structure to withstand loads.  

Features of butt and corner connections of workpieces 

The main parameters by which the connection is assessed and calculated take into account its geometric features. There are clear definitions for them. They, in turn, depend on the type of connection - butt, corner, end or overlap. In this case, the preparation of the edges and ends of the parts is of great importance. A number of features of the workpieces and the seam itself are taken into account.  

1. The joint of sheets with a thickness of 4 mm or more must be carried out with the preparation of the edges and ends in such a way that a triangular curvilinear gap is formed for complete welding to the entire depth. 

2. Sheets 2 mm thick are welded only with an overlap, avoiding through-burning of the metal. 

3. Full penetration of the joint is achieved only when the metal is heated to the entire depth of the joint. This is why they resort to beveling the edges of parts. When welding corners of large thickness, the bevel is performed as for sheets.  

4. When corner and T welding of parts, a characteristic bead is formed, the width and shape of which determines the strength and durability of the joint. 

IMPORTANT TO KNOW: Diffusion welding of metals

When joining parts with beveled edges, as with a corner connection, the seam in the section has a triangular shape. In the first case, the ratio of the width, depth and height of the seam is taken into account. In the second, the bead forms an inclined surface - the distance from its edge to the other part is the leg of the weld, the parameters of which are determined by GOST 5264-80.  

Dependence of welding quality on machine settings

[Arc welding] is performed with certain values ​​of current and voltage, which ultimately affects the depth of penetration and the quality of fusion of the metal of two parts within the boundaries of the weld pool. Basic techniques used by experienced welders to form a high-quality seam:

• the depth of penetration increases with increasing current strength at a constant voltage - the temperature and depth of heating of the metal increases;
• the width of the seam and leg increases with increasing voltage and constant current strength, however, if the balance is upset, the joint may lack penetration;
• as the electrode speed increases, the penetration depth decreases and the width decreases, and if the standard value of 50 m/h is exceeded, a number of [weld defects] may appear due to insufficient heating of the metal;
• Convex and concave surfaces along the leg of the weld have different strength characteristics, while the first is obtained when using viscous electrodes. 

When calculating, the thickness of the two workpieces is taken into account, but the maximum current and voltage parameters are taken for a thin part to avoid burn-through. The maximum and minimum length of the welding seam is calculated according to the table given in GOST.  

IMPORTANT TO KNOW: Tips for semi-automatic welding with and without gas

Errors when incorrectly calculating the weld leg 

Inexperienced welders may make mistakes due to incorrect calculation of the weld leg parameters for fillet joints. Excess metal along the joint line does not impart strength; it causes increased energy and electrode consumption, leads to metal spattering and the appearance of a sagging not associated with the surface of the part. The formula for calculating the weld leg is used to determine its maximum and minimum size.  

Since the seam has the shape of a triangle, it is enough to use a coefficient of 0.7 for the width of the resulting roller. This also applies to butt welding, when the ends of the parts form a slope. But it should be borne in mind that with such a connection the angle can be from 30 to 60 degrees, and other coefficients may apply here.

Calculation of the minimum leg for the smallest thickness of parts for welding 

Example: to weld two sheets less than 4 mm thick, you can take a minimum weld leg of 4 mm for a corner connection. If the metal thickness exceeds 4 mm, then for the calculation you can take 40% of the thickness of the sheet (part) and add another 2 millimeters. You should not underestimate the value - the seam will turn out fragile. Exceeding can lead to the occurrence of [stresses and deformations] in the metal, and this will reduce the strength and durability of the structure.

IMPORTANT TO KNOW: Methods for soldering gold at home

All parameter values ​​can be found in the table - this is an appendix to GOST. For welders, there are special cathetometer templates that allow you to quickly and accurately check the quality and correctness of the joint shape.  

Source: https://rezhemmetall.ru/chto-takoe-raschet-kateta-svarnogo-shva.html

What is a weld leg and its calculation

The strength of welds is determined not only by the correctly selected welding mode of two metal workpieces or the correctly selected consumables, but also by the exact dimensions of the weld itself. And if in the butt welding the width of the bead is taken as the basis, then in the fillet weld the leg of the weld is used. What is it and why exactly does this parameter affect the strength characteristics of the connecting section.

• 1 What is a weld leg
• 2 Calculation of the seam leg
• 3 Conclusions

Calculation of the seam leg

Since the cross-section of the weld is a right-angled isosceles triangle, the size of its leg is easy to calculate. To do this, you can use the trigonometric formula: T = S cos 45º, where

• T is the size of the seam leg;
• S is the width of the roller or the hypotenuse of the triangle.

To find out the leg size, you must first measure the width of the weld. This is not difficult to do. In this case, cos 45° is equal to 0.7. By substituting all the values ​​into the formula, you can determine the size of the weld leg with great accuracy.

For example, if the width of the roller is 3 mm, then its leg will be equal to: 3x0.7 = 2.1 mm. And since there are certain standards that guarantee the quality of the final result depending on the width of the welding bead, it is possible to set standard values ​​for the leg itself. So, when welding two workpieces with a thickness of 12-19 mm, the optimal value of the seam width is within about 6 mm, which means that the standard leg size will be 4.2 mm or a range of 4-5 mm is selected.

That is, by welding two workpieces of a given thickness, you can measure the leg of the seam by choosing a cathetomer of a certain size. If it does not match, it means that the welding was carried out incorrectly, and its high quality cannot be guaranteed.

conclusions

When defining the leg of a weld, it is necessary to understand that this indicator belongs to the category of quality. The strength and reliability of the structure being welded largely depends on it, therefore, when creating a welding scheme in large industries, this parameter must be specified. And if in non-critical structures the attitude towards it is “cool”, then for those connections that will be subject to heavy loads, this value plays an important role.

In complex welding technologies, the leg is selected individually for each joint. But, in essence, standard general selection principles are used for it. And this, as mentioned above, is the thickness of the metals being joined, their chemical composition, welding mode, type of electrode or filler wire.

Source: https://svarkalegko.com/tehonology/katet-svarnogo-shva.html

What is a weld leg

» Welding work at the dacha.

Depending on the nature of the connection between two parts, welds can be butt and corner welds. Parameters characterizing their quality are convexity, concavity, penetration depth and geometric dimensions.

Geometric dimensions of seams

During visual inspection, welded joints are checked not only for the presence of defects, but also for compliance of the obtained geometric dimensions with the indicators regulated by the design and technological documentation.

If the main parameter on butt welds is the width, then on T-joints, overlaps and corner welds it is the leg. This is the length of the perpendicular, conditionally lowered from the vertex of the angle to the hypotenuse. In simple words - the distance from the plane of one workpiece to the edge of the seam on the surface of the second part.

Corner joints can have different shapes:

• Convex ones are impractical from a technical point of view. In addition to a larger amount of deposited metal (and therefore material consumption), they lead to stress concentration.
• Concave - difficult to obtain. It is necessary to fine-tune the operating parameters of the welding machine and maintain the appropriate speed of electrode guidance, which requires considerable experience from the welder. More often than not, the concave configuration is created by machining. Such seams are used extremely rarely in the manufacture of metal structures.

Fillet welds of normal outline (without convexities or concavities) are widely used. When developing design documentation, the leg is taken to be equal to the thickness of the thinner part, but it can be smaller - it is important to ensure maximum joint strength. So, for workpieces with a thickness of 4-5 mm it should be 4 mm, and for thicker parts it is calculated or determined structurally, but is accepted at least 5 mm.

How are leg values ​​checked?

Unlike the quality of penetration, which is controlled by special devices, the leg of the weld is measured using a special device UShS-2 (universal welder’s template). It is also called a cathetomer.

The template consists of several thin-sheet metal plates with recesses with a certain leg size. They are connected to each other by a hinge or a connecting ring.

Measurements are carried out using a stepwise selection of the most suitable leg size. And it is determined when one of the recesses on the plates is adjacent to the weld with a minimum gap between the template arc and the joint surface.

Source: http://samanka.ru/katet-svarnogo-shva-chto-eto-takoe.html

How to calculate the leg of a weld yourself: instructions, formula and system, evaluation of the result

The weld seam has many parameters such as force height, width, length or thickness. The difference in these parameters appears due to the fact that the seams can be different, for example angular or straight, and these two are made for many other types.

But we are interested in how to calculate the leg of a welding joint; all the listed characteristics will help us with all this.

It seems to you why go so deep into geometry, this is welding, but everything is not so easy, calculating the leg will allow you to significantly increase the level of connection and achieve the desired result.

But at this stage, many people are faced with the problem that they don’t even know what a seam leg is and how to calculate it. And even more so, how to measure it, and why all this is generally necessary when working with welding.

Our article wants to lift the curtain on such a popular question, how to still calculate the leg of a weld based on the thickness of the metal.

Even for novice welders, it will be enough to read our article to understand everything well and apply their knowledge in practice, with good success.

General Information

So we’ll start with the fact that what is a connection leg, why does it exist and why do we even need to calculate it? This is actually the leg of the triangle into which the longitudinal section can fit.

Of course, it’s not realistic to fit in. But still the question “Why do this?” It remains with everyone why, in principle, calculate this for corner or straight joints, overlapping or end seams.

You should know that on the market you can find a special mechanical device, such a ruler, but we all advise you to learn how to do such calculations yourself, this will significantly increase your professionalism, and you will acquire a new skill.

Such calculations can also show you the level of quality of the connection you made, because quality is the first on the list of priorities for the master who will begin such a difficult job.

You will not be able to make a seam leg if you are working with a large structure; this will not solve the issue that the seam may not be reliable. Sometimes visually it may seem quite durable and of high quality, but in fact it will let you down later.

It may seem to beginners that it is not difficult to solve such a problem, melt more and you are done, but this is far from true and is a big mistake.

While you are welding mountains of metal, the surface of the part is increasingly exposed to temperature, which will lead to inevitable defects such as oxidation, bending and corrosion in the future, and of course all this will make the quality of the connection much lower.

This calculation will be useful if you need to calculate an estimate, that is, in an enterprise, or even in a large home construction project.

By measuring the leg, you will be able to almost accurately calculate the required amount of consumables and forces, and you will no longer have to urgently buy something in addition when you realize that the seam is too thin or narrow.

Calculation will also be a good option if you have to work with metals of different thicknesses. If you have to weld thick and thin metals, just do the math and you won’t have any problems. For such calculations, the parameters of thin metal are taken into account.

If you take our advice and do the math, your seam will never be too narrow.

And this is worth a lot in cases where there is important work to be done with a problematic metal structure, which will then be meticulously checked.

This calculation will be especially useful when working with seams at corners, because this is where cracks, corrosion, and deformations most often occur.

The deception is often that the welded element visually looks strong, but when it is put into use, uncalculated fragments can seriously fail. It's really worth calculating the leg. Read below about how to do it correctly.

Welding leg calculation system

On the Internet you will be able to find a lot of different formulas according to which it is recommended to calculate the leg of a connection.

The formulas are varied because they work on different types of seams, such as T-joints, overlapped joints, straight joints, and corner seams. And these are not all types, but each has an even more detailed classification.

That is, each individual seam needs to be calculated according to a special formula in the total mass - this is close to a dozen formulas, if we take into account all the nuances.

But, as you understand, this is too much information and it is impossible to fit it into the regulations of one article.

But we will tell you how to calculate the most famous and frequently used type of connection - we will count by the width of the seam. Below you can see the formula we need:

This is a simple formula. It allows you to easily calculate the size of the fillet weld leg. And then it’s even simpler: the leg of the corner connection is the value of the leg of the triangle that can fit.

We will also tell you how to calculate the length of a seam based on its thickness. But here you don’t even need elementary formulas, it will be enough to take the thickness over the smallest area and this number will be your indicator.

The examples are elementary: if we have a metal whose thickness is 4 millimeters and we need to weld it, then we need to calculate the thickness of the leg.

Then we evaluate whether the thickness is really 4 millimeters over the entire surface area and conclude that the thickness is 4 millimeters.

It is convenient to calculate the leg of a welding joint based on its thickness when you are going to weld using an overlapped seam or dialectal, thin areas. And if your part is impressively thick, then find 40 percent of the figure.

Below we have found for you a diagram of the smallest welding joint legs for T-joints.

It will serve you if you don’t have time to calculate for a long time, or the table simply already contains accurate data for your parameters. Add it and try to use it at work.

Characteristics of a well-executed seam

You have already read above how to calculate the leg of a welding joint. This will be a big plus, but still this is not enough for a quality connection. The welding seam has its own parameters that you cannot ignore.

In the first place there should be uniformity of the seam along its entire length, there should be no sagging or penetration, or any “snakes”; everything should be beautiful and neat. Pay close attention to what you do and how, try to do everything carefully.

Something may seem trivial to you, but later the structure may simply collapse, and it’s good if not on someone’s head. The width of the seam should be the same along the entire length.

If the connection is wider somewhere, narrower somewhere, then support points will appear, and this point will not be able to bear the weight of the structure, it will begin to crack and later may collapse.

It is also important to ensure that your connection is at sufficient depth. It is important to brew evenly to a depth or internal cracks may occur.

Factories carry out professional calculations of all these characteristics. Welders calculate depth, width, length down to millimeters. And they often use all the calculation techniques we have listed.

Of course, an amateur or a complete beginner may not complicate the already difficult task of welding with such calculations, but understanding the basics is very important, you should know how all this should look ideally.

The more similar those prepared for welding are to each other, the better.

Naturally, there are also welding methods that work on welding dissimilar metals, the chemical composition of which is completely different, but still the connection of such metals will not be very strong no matter what you do with it.

For a good result, you need the correct current strength, high-quality professional equipment, if you are not new to this business, it is also important to purchase high-quality consumables, first of all, an electrode, because they form the seam.

Only if you can provide such working conditions will counting the connection leg be useful for you.

You can calculate everything down to millimeters, but at the same time working on old, faulty equipment or with low-quality electrodes that are full of slag, the result will never be strong.

How to measure a weld leg

The geometric parameters of the weld, along with the correctly selected mode, have a significant impact on strength, as well as durability. In the case of joining two parts end-to-end, the main geometric characteristic is the width of the seam bead. In the case of fillet welding, the leg takes its place.

Weld leg

How to properly thread fishing line into a trimmer? — Metals, equipment, instructions

How to correctly wind the fishing line onto the trimmer reel

Many people, having worn out the factory line on a recently received trimmer, try to wind a new one, but cannot, because they do not know how to correctly wind the line onto the trimmer’s reel (spool). How to quickly insert fishing line into the trimmer reel, how to wind fishing line onto the reel.

The article talks about such an indispensable device for summer residents as a trimmer, about its varieties and scope of application, as well as how to correctly thread the fishing line into it so that the technique. No matter how there is an abstract, it still doesn’t come out.

Let's try to deal with this issue in this article.

So, in order to wind the fishing line , you must first remove the reel from the trimmer - it will be more convenient. The removal method will depend on the type of trimmer.

Remove the coil from the trimmer

On small electronic trimmers with a bottom-mounted motor (where the motor is near the ground when operating), the coil usually has two buttons on the edges. Click on them and disconnect one half of the coil body from the second, which remains on the trimmer. Together with the first half, the inner part is also removed, onto which the fishing line is wound. When disassembling, be careful: there is a spring inside that can fly out and get lost.

On electronic and gasoline trimmers with a bent rod (on such trimmers there is still no ability to place a knife), you need to grab the coil body itself with one hand, and with the other hand you need to start turning the thumb on it counterclockwise. Specifically, he attaches the coil to the trimmer rod. Having unscrewed the thumb, carefully remove the entire coil, trying not to lose the spring inside.

On electronic and gasoline trimmers with a straight rod and a gearbox at its end (on such trimmers, in addition to the fishing line, you can also install a knife), look for a hole under the coil, insert, for example, a screwdriver into it, quietly rotate the coil until the screwdriver gets even deeper , and the coil will lock.

Now we twist the entire coil clockwise (because the thread is left-handed) and remove it from the trimmer. How to thread line into a trimmer reel. How to properly put fishing line on a reel. Next we disassemble the coil. How to thread line into a trimmer. It can be assembled using latches or twisted with a lamb.

If the coil is on latches, then press along the edges on the base of the latches so that they bend and release one half of the coil body from the other. We just twist the lamb.

There may also be a third type of connection of two halves of such a coil: with it you need to grab the lower part with one hand, and the upper part with the other, and begin to turn them in the opposite directions. When disassembling such a coil, you must also ensure that the spring inside is not lost.

How to wind fishing line onto the mowing head of a trimmer or brush cutter

The video carefully shows how to wind the fishing line onto the reel of a trimmer or brush cutter. Refilling the mowing line.

How to wind fishing line onto a trimmer reel?

Answer to the question after the previous video .

More than 200 types of trimmers in one place at the lowest prices. Click and watch

Now, having removed and disassembled the coil, we begin to actually wind it.

Winding process

If your reel is designed to work with only one antenna, then everything is simple. You need to unwind 2-4 m of fishing line (depending on the size of the reel), find a hole on the inside of the reel that fixes the fishing line, insert one end of the fishing line there and start winding the fishing line in the direction opposite to the direction of rotation of the reel on the trimmer.

How to thread fishing line into a trimmer reel and never. On the inside of the reel there is usually an arrow indicating which direction to wind the line. How to wind fishing line onto a reel, how to unwind fishing line, help thread the fishing line into. Having wound the fishing line, we leave a small piece of it unwound in order to expose it outside.

We fix this piece in a special groove located on the inside of the reel and designed to prevent the line from unwinding when the reel is assembled. If there is no such groove, then you will have to hold the line with your finger to prevent it from unwinding during further assembly of the reel.

Next, we take the outer part of the reel and thread the outer piece of fishing line into the existing hole, assemble and put the reel back on the trimmer.

If the coil is designed to work with two antennae, then do the following. On the inside of the reel we look at how many grooves there are for winding fishing line. In this article, we will describe in detail the procedure on how to remove the trimmer coil. Step-by-step instructions with the attached video will help a beginner and... There may be one or two. For the reel, how to properly thread the fishing line into the trimmer reel.

And immediately assemble the coil. If there is only one groove, then both tendrils are wound along this one groove. If there are two grooves, then each tendril is wound along its own groove. A single-groove reel must have a through hole through which the line is threaded. We unwind 2-4 m of fishing line, thread it through this hole so that the fishing line sticks out equally on each side.

And we simultaneously wind both tendrils of the fishing line in the same direction, opposite to the direction of rotation of the reel on the trimmer and coinciding with the direction indicated by the arrow on the inside of the reel. We leave a little of the fishing line unwound, fix the resulting ends in special grooves, and if there are none, hold them with your fingers.

We thread both ends into the existing holes on the outer body of the coil. We assemble the coil and attach it to the trimmer.

If there are two grooves, fold a piece of fishing line 2-4 m long in half, insert the resulting loop at the bend into the groove between the two grooves, and simultaneously wind both ends of the fishing line, each along its own groove. Further actions are similar to the previous option.

There are also reels in which the fishing line is threaded through a through hole on the inside; the ends of the fishing line, without winding, are threaded completely through the holes on the outer body of the reel, assemble the reel and begin to rotate the button, which is usually pressed, so that during operation the fishing line is released along the as it wears out. You turn the button and the fishing line winds itself inside.

How to thread the fishing line into the trimmer reel and the reels into the fishing line are not. However, you won’t be able to twist it in the “wrong” direction, since it can only spin in one direction.

That's all on this issue. The video below will clearly show how to thread the line into the trimmer reel and. Happy winding!

Source: https://spb-metalloobrabotka.com/kak-vybrat-katet-svarnogo-shva/

How to determine the leg of a weld?

When performing electric arc welding, there is a need to evaluate the quality of the seam connection of parts using non-destructive methods. For this purpose, defect meters based on various physical principles are used. In addition, a visual assessment of quality and geometric parameters is carried out, in which the concept of weld leg is used.

Depending on a number of conditions, a preliminary calculation of the leg is made using the appropriate tables, which allows its characteristics to be included in the design documentation at different stages of work. We will talk in detail about this concept and its impact on the strength of the workpiece joint.

Types of welds

The connection of parts can occur in different ways and this entirely depends on the shape of the workpieces and the tasks being solved. Welders can connect elements in the same plane or at an angle to each other using an internal or external seam, the parameters of which depend on the requirements for the strength and thickness of the workpieces.

It is also important to take into account the degree of edge processing and possible changes in the geometric shape of parts due to overheating associated with non-compliance with the technological regime. Sometimes the use of a continuous seam is not economically justified and an intermittent connection in a checkerboard or other pattern is chosen.

Regardless of the type of welding, workpiece material and number of passes, the welding speed according to standards and tables rarely exceeds 50 m/hour. This optimal value allows the workpieces to be heated sufficiently well and at the same time to prevent overheating, leading to deformation of the component parts of the product.

According to the method of connecting parts, the following types of welds are distinguished, namely:

• overlap joint, which is made with a relatively small thickness of the workpieces and is made from two opposite sides;
• butt joint, carried out with processing of the edges of the joint at an angle of 45° with a metal thickness of more than 4 mm;
• end method used to connect two sheets of metal superimposed on each other;
• corner weld, both external and internal, with mandatory edge processing for the best penetration;
• T-joint, in which the parts are located at right angles with double-sided welding.

The choice of type of connection depends on the technical specifications and the required strength of the connection, therefore it is necessary to take into account the presence of workpieces of different thicknesses that require special attention when processing and joining edges. It is necessary to select flux and additives, as well as electrode material, in exact accordance with the material being welded in order to prevent the formation of a porous and weak weld.

Parameters and geometric characteristics of the seam

The dimensions of the weld and the depth of penetration depend on several factors, which include the chemical composition of the workpieces and electrode material, the composition of additives and flux, as well as the current strength and welding speed. It is these circumstances that determine the properties and geometric dimensions of the seam joints, which determine the rigidity and strength of the entire structure as a whole.

The butt joint is characterized by a convex shape, which is leveled during final processing with abrasive materials. This is done if the height of the roller should not exceed certain parameters according to the technical specifications.

With an overlap, corner or T-joint, the cross-sectional shape of the seam has the form of a right triangle with legs and a convex or concave hypotenuse, and the recommended dimensions of this geometric figure depend on the thickness of the materials being welded.

The strength of the joint of the workpieces is determined by the following parameters of the seam connection:

• the root part of the seam, which is closest to the joint of the parts;
• the body of the seam joint is characterized by one or more passes to achieve the required dimensions;
• seam width indicator, which is the conditional hypotenuse of a right triangle with a convex or concave surface;
• parameter of the weld legs, which most fully characterizes the rigid strength properties of the connection.

To understand what a leg of a welded joint is, it is necessary to imagine a seam in section. In cross-section, it looks like a right triangle with two legs on the sides of the blanks and a hypotenuse between them, which is the width of the seam. These parameters are considered the basis for visual quality control during welding. When joining thin (up to 4 mm) sheets with an overlap, the leg is chosen equal to the thickness of the workpieces, and with greater thickness this parameter is equal to 40-45% of the thickness of the parts.

Weld leg: methods of visual inspection of parameters

For non-destructive welding quality control, there are several fairly effective methods based on different physical principles. This is a radiographic method, transmission with X-rays and gamma rays, and safe methods include eddy current flaw detection and ultrasonic testing.

Not least important are magnetic sensing and capillary research. Methods of such control require expensive equipment, radioactive sources or reagents, therefore they are quite expensive and are not used everywhere, but only in critical and particularly important units and are regulated by instruction SN 375-67.

There are computer programs for calculating the strength of joints, where the key parameter is the leg of the weld during welding, and it becomes necessary to measure the main geometric characteristics. Such measurements are carried out during visual inspection of the seam using a variety of universal templates, namely:

• Krasovsky's universal welding template (USHK-1), is used to measure gaps between workpieces and parameters of lap, T-joint and butt joints;
• universal meter UShS-2, which is a set of templates for determining the legs along the convex hypotenuse from 4 to 14 mm;
• a more complex UShS-3 meter, used for measuring joint cutting angles, and also allows you to measure the displacement between parts and the height of the butt weld bead;
• The welder's template UShS-4 with a built-in Marshak-Usherov meter allows you to measure various angles, the size of the leg and root of the weld, and is the most universal meter.

We have become convinced of the importance of such an indicator as the weld leg when visually monitoring the quality of work and calculating the strength of the entire connection as a whole. The method of assessing the compliance of completed work with technical specifications using measurements is the most inexpensive and time-tested method, which does not require the use of high-tech equipment and expensive personnel training.

Let's sum it up

We talked about a relatively accessible and reliable method for calculating the strength of a welding joint using such a parameter as the leg of the weld. With a simplified, approximate calculation, simple work can be performed, but if critical building structures are required, then a balanced engineering approach is required, based on correct measurements using special templates.

Source: https://electrod.biz/varim/seams/katet-svarnogo-shva.html

Calculation of the length of the weld leg from the thickness of the metal for various types of welds

In the production of metal structures and heavy vehicles, welded joints must withstand high loads. The weld will be of high quality only if all parameters are accurately calculated before starting work. One of the important indicators is the seam leg (K).

This is one of the sides of the largest conditional triangle with equal sides, which can be inscribed in the cross section of the connection (GOST R ISO 17659-2009, which came into force on July 1, 2010). It can be measured or calculated based on the dimensions of the elements being welded.

When choosing the length of the side of the triangle, the dimensions of the workpieces, position and type of joint are taken into account. The selection is carried out for each element, but general principles are taken into account. In the household, you can use a template to measure.

https://www.youtube.com/watch?v=8KPusauj5NE

In order for the connection to be strong enough, both identical sides of the triangle must have the same length (if the elements are located at an angle of 90°).

Connections can be:

• butt (without beveled edges, with one-sided, with V-shaped, X-shaped, curved bevel);
• end;
• overlap;
• corner (angle from 30°, one-sided, two-sided without beveled edges, with one or two bevels);
• T-shaped (acute or straight angle, one-sided, two-sided, without beveled edges, with one or two bevels).

Calculation of the length of the leg of the weld depending on the thickness of the metal is possible for three types of welds: fillet, T, and overlap.

Calculation of the length of the weld leg, based on the thickness of the metal, is required in industrial production, since the strength of the weld, the consumption of welding wire, and its diameter depend on this indicator (the longer the side of the triangle, the thicker the wire).

Important! If the side of the triangle is too long, the volume of liquid metal increases (due to the large heating area) and the consumption of the additive increases, and the finished product may become deformed.

The leg is also important if elements of different sizes are welded (calculations are made based on the smaller figure).

Read also: Techniques to relieve metal stress after welding

Calculation formula

The volume of deposited material is equal to the square of the leg. For example, if K increases by 1 mm at a junction length of 10 mm, wire consumption increases by 20%.

For overlapping materials with a thickness of up to 4 mm K=4. If the figure is greater, you need to take 40% of the thickness and add 2 mm.

Corner welded joints are:

• normal (without convexity or concavity) - K is equal to the thickness of the metal;
• concave - K=0.85;
• convex - K= s×cos45°, where s is the width of the junction, cos45°=0.7071;
• special (the triangle is not isosceles).

When calculating the length of the weld leg depending on the thickness of the metal, the formula is not enough - the welding method and the fluidity of the metal being welded are important.

The obtained result must be checked against the requirements of GOST 11534-75 and GOST 5264-80 or reference materials.

When carrying out welding work in the household, it is enough to establish the side of the triangle that exceeds the thickness by 1-1.5 mm, or determine the indicator from the table. There are rules that must be followed at all times. K must be less than the thickness of the thinnest element multiplied by 1.2. The length of the junction should be less than K*4.

Calculation of the leg for a 1m seam

In practice, all calculations are quite conditional, as they are based on the following premises:

• the load is distributed evenly along the entire length of the deposited filler;
• destruction is possible only through an additive layer equal to 0.7 K.

The purpose of design calculations is to determine the optimal weld size for a certain elongation and axial stress.

The optimal length of the deposited filler for tensile load is determined by the formula:

L= F/ρ*[ρ], where

L – length of the junction;

F – planned actual load on the connection;

ρ – permissible load on the connection.

Optimal length for axial stress:

L=F/0.7K*ρ

From this formula we can derive a formula for calculating K for a deposited filler length of 1 m:

K= 0.7*L*ρ

K=0.7*ρ

This means that K completely depends on the magnitude of the permissible load.

Permissible loads in compression, tension and shear for various welding methods are determined in special tables.

When developing design documentation:

• select the welding method, type of welding, brand of electrode (wire);
• determine the standard permissible load;
• calculate the length of the joint for tension and axial stress;
• create a connection drawing;
• specify the technical characteristics and dimensions of the elements being welded.

When developing design documentation for welding, determining the exact size of the weld leg from the thickness of the metal and the optimal length of the weld is carried out in order to improve the quality of the work and minimize its cost. It is important to obtain strong and reliable connections at minimal cost. This indicator is especially important at large industrial enterprises that produce metal structures that must withstand increased loads during operation.

Source: http://solidiron.ru/obrabotka-metalla/svarka/raschet-kateta-svarnogo-shva-ot-tolshhiny-metalla.html