What is pulse welding

Pulse-arc welding: essence, types, scope of application, algorithm, advantages and disadvantages of the method

Pulse-arc welding is a type of arc welding in which higher current pulses are applied to the pilot arc. The method is applicable when welding both in shielding gases and with consumable and non-consumable electrodes.

Pulsed arc welding technology

Pulse-arc welding is carried out using welding equipment that assumes the possibility of applying a pulse to a constant arc whose current strength is several times greater than that of the pilot arc.

Pulse-arc welding occurs according to the following algorithm:

• against the background of the base current, a high-power pulse melts the end of the electrode and forms a drop of the required size at its end;
• then the formed drop is separated and transferred to a metal workpiece;
• the current drops to a base value that allows maintaining a pilot arc;
• metal deposition occurs in the weld pool;
• this process is then repeated.

Advantages and disadvantages

The pulse-arc welding method was developed as a more versatile and productive alternative to the arc method. Among its advantages are:

• eliminating possible defects in the form of burns and non-fusion;
• no metal spattering during the welding process;
• economical consumption of welding wire and electrodes;
• Possibility of welding metals of different compositions;
• Due to the small number of defects that occur, the processing of weld seams is significantly simplified.

Disadvantage of the pulse-arc welding method: this method is not applicable for large welding volumes.

Scope of use

Initially, this method was invented for welding stainless steel. Its first application was the construction of the American train Pioneer Zephyr in 1932, where the use of stainless steel welded in this way made it possible to reduce the weight of the train and, therefore, increase its speed parameters.

Later it turned out that pulsed-arc welding can be successfully used when joining together both different grades of steel and non-ferrous metals: aluminum, copper, nickel alloys and titanium.

The range of workpieces that can be welded using the pulse welding method is from 1 to 50 mm.

Nowadays, the pulse-arc method is widely used in the installation of pipelines for various purposes. It provides a high-quality weld with virtually no defects, a well-formed return bead that does not require stripping, and sufficient strength of the welded joint, which is a priority for these types of structures.

Types of pulse welding and their brief characteristics

The classification of types of pulsed-arc welding is based on the difference in methods of converting current to create a pulse. There are four of them in total: magnetic pulse, battery, inertial and capacitor.

Magnetic pulse view

The essence of this type of welding is the connection of metal parts by impact using a pulsed electromagnetic field in the process.

During the welding process, one part remains stationary, and the second is driven by the electromagnetic field generated by the welding installation. At the moment they come together, an arc is formed that welds the workpieces.

Magnetic pulse welding is relevant in mechanical engineering for connecting tubular parts to each other and to other parts. It is also used for welding flat parts along their outer and inner contours .

Magnetic pulse welding can be used to join parts with a workpiece thickness range of 0.5-2.5 mm.

This type of welding is not widely used due to the complexity of the technological adjustment process and the rapid wear of welding equipment.

Battery view

In welding machines designed for this type of welding, the required current for the pulse is generated using alkaline batteries. Their distinctive design feature is a low value of internal resistance, which allows them to produce a short-circuit current that is many times stronger than the standard discharge current . This type of welding is currently in the development stage and is not widely used.

Inertial view

Inertial welding uses the accumulated energy of a rotating flywheel, which is driven by the common shaft of a rotary power generator.

Friction welding scheme

At the moment of welding, the speed of the flywheel slows down, and it transforms the stored kinetic energy in the form of a welding current pulse.

Capacitor type

In capacitor welding, the impulse required for the welding process is provided by the energy of a short current pulse when the capacitor is discharged. This type of welding has restrictions on the maximum cross-section of the workpieces being welded.

Its scope is the connection of sheet metal with fasteners of various designs (studs, bushings, nails, etc.).

It is also successfully used in the production of electronic components and instrument making, where it is necessary to weld small parts and thin metals together.

Source: https://elsvarkin.ru/texnologiya/impulsno-dugovaya/

Pulse welding: welding machine design, application and principle of operation

Welding technologies never lag behind the speed of scientific and technological progress. New methods, materials or equipment are constantly adding to the already wide list of various ways to join metals and non-metals.

Pulse welding is one of the new methods that has already found the widest application in the installation of modern powerful pipelines and construction: both industrial and civil.

Features of pulse welding

This type of welding is capable of joining such capricious metals as copper alloys, steel and many other non-ferrous alloys, including aluminum. Pulse welding is excellent for complex butt welds when joining metal workpieces with thick edges.

Historically, pulsed welding was invented and developed as a competitive method to electric arc technology, which has certain disadvantages in terms of productivity and weld quality.

The essence of the process

The principle of pulse welding.

In short, this is a process of sequential melting of the metal of the workpiece at certain points with the next stage in the form of coating.

The main element of this process is the so-called low-power pilot arc, which continues to operate in stops between repeating pulses and transmits the pulse current only partially.

This arc has virtually no effect on the metal between pulses; it burns perfectly and steadily in space. The second state of the same arc is pulsed, which melts the metal at the points of application.

The ratio of currents from the arc in different states - pulsed and standby - must be correct, which can speed up welding and improve the quality of the seam.

The possibilities of classical gas-shielded arc welding are greatly expanded if the metal is melted under the influence of a pulsed arc.

Short pulses are produced using the energy of a special battery, which is pre-charged from an electrical circuit. The technological feature and advantage of the method is the ability of pulse welding to form permanent joints of metals with completely different compositions.

Equipment for pulse welding requires special equipment - this is a special specialized pulse welding machine with certain consumables. The pulse machine generates dosed welding pulses.

Consumable materials include various types of electrodes - consumable and non-consumable.

The pulse welder includes the following elements:

• low frequency rectifier;
• another high-frequency rectifier;
• welding inverter device;
• transformer;
• electronic control unit - plateau;
• working shunts.

Electrical diagram of a pulse welding device.

The two pulse welding methods are determined by the choice and use of electrodes:

• using non-consumable electrodes;
• using consumable electrodes, eliminating the disadvantage of the process in the form of splashing drops of molten metal.

One way or another, this is a controlled, repeating process of transferring molten consumable metal in a protective gas environment.

Here's how it happens:

• A drop of molten metal from the consumable wire is separated and moved to the workpiece under the influence of a powerful impulse.
• Immediately after this, the strength of the welding current drops to a level that can only support the arc - the arc becomes “standby”, of low power.
• The process of cooling the metal in the weld pool begins instantly.
• An exact repetition of the same cycle of droplet transfer under a pulse begins, with a drop in current, cooling, etc.

From the point of view of the electrical component of the pulse welding process, the device uses the transformation of mains voltage into rectified direct voltage, after which it turns into voltage with a high frequency.

Technical nuances

Before starting work, the energy receiver must be connected to the power supply to charge it to the required level. Pulse welding itself takes very little time, since it uses the energy stored in the receiver. This kind of welding can be done with your own hands; it is not at all overly complicated.

With this method, the unpleasant phenomenon of splashing droplets of molten metal is perfectly controlled and minimized. There is an excellent opportunity to produce high-quality welds almost at home.

Seams are formed due to the melting of individual portions of metal followed by coating.

The most important point is the correct setting of the pulse and pilot arc modes. If the mode is correct, the process will go quickly, correctly and, most importantly, safely, without any craters in critical joint areas.

Pulsed DC welding

The rigidity of the regime is a technological feature of this method. It's all about the pulse duration. If you change it, all welding parameters will change.

One of the important advantages is the ability to control and minimize metal crystallization. You can change the shape of the weld pool. Additionally, the risk of weld deformation can be controlled and reduced.

This method is often used to join metal with edge thicknesses greater than 3 mm.

Classification of species

Pulse welding is divided into four types:

• capacitor using devices with a huge range of current. Excellent for welding aluminum parts;
• rechargeable, which uses devices with alkaline batteries, copes well with short circuits in the network;
• inertial using the kinetic energy of a powerful flywheel;
• electromagnetic with the production of mechanical energy using a magnetic field. The elements are attached by magnetic forces combined with high pressure.

Algorithm of actions

This is one of the best types of welding overall. There is no spattering, no lack of fusion is formed, you can cook in any position, electrodes are used very sparingly. The seams are formed of exceptional quality without any burns.

Capacitor welding scheme.

The principle of operation of a welding inverter in combination with pulse technology is as follows: transfer of the electrode metal into the weld pool while simultaneously regulating the current.

It all starts with the formation of a drop of metal at the end of the electrode, which, when the current increases, enters the weld pool. Now this hot moment should be replaced by a cold stage with the cooling of the metal. This can happen many times.

The electrode wire must be well heated. This is especially important at low current values.

These devices are very easy to use with clear adjustments for proper and fine tuning. They are usually equipped with good software support, which makes them even more effective in all respects.

The main advantages of the method

Advantages of pulse welding:

• The first thing is the excellent quality of the weld. Let us immediately note that pulse devices are very expensive things. But they are worth it and will definitely pay off all costs in the future.
• Pulse welds everything from steel to aluminum.
• A minimum of additional tools and consumables are required.
• No metal spattering.
• There are no burns or failures of fusion.
• Ability to control the arc.
• Excellent ability to control the metal transfer process.
• Economical consumption of materials, including welding wire and electrodes.
• Easy seam cleaning at the end.
• Easy to perform even for beginners.

Drawing of a pulse welding device.

Today, this method has only one competitor in popularity and efficiency - semi-automatic welding. It is characterized by high productivity and, importantly, process continuity.

But a serious drawback is metal spattering, which results in the loss of up to 30% of the material. In addition to losses, these spatters must be cleaned after welding, which is very difficult and spoils the appearance of the weld. Pulse welding eliminates such a problem.

The area of ​​application of the method is the installation of pipelines of the most critical type, where the strength of the seam with a firmly formed back bead without finishing stripping is especially important.

This method has only two disadvantages:

• it is not suitable for large welding areas;
• serious cooling of the inductor is always necessary.

Micropulse welding

Imagine, this method has found a separate and very wide application in dentistry - dental prosthetics. We are talking about microwelding using titanium in the form of thin sheets. A special micropulse device is capable of welding dental alloys, including titanium.

The quality of such sutures is in no way inferior to laser dental equipment, but its cost is much lower. For this reason, they are quite popular in small dental clinics.

 DIY pulse welder

The design of the welding machine makes it possible to make it at home for domestic use. The components are easy to buy, there are no problems here. But we must not forget about some nuances.

Before you start working, you need to think about and calculate the strength of the welding current and the power of the device. There are a huge number of examples with similar calculations on the Internet; they can help in developing the right solution.

Source: https://tutsvarka.ru/vidy/impulsnaya-svarka

Pulse and resistance welding - features, advantages and disadvantages

Semi-automatic welding is most widespread in modern production. Its main advantages are high productivity and a wide range of thicknesses of welded metals. However, it is not without its shortcomings.

Disadvantages of semi-automatic welding

The main disadvantage of semi-automatic welding is metal spattering. This is especially noticeable when using carbon dioxide as a protective agent. In this case, about 30% of the welding wire does not enter the seam.

When using a mixture of argon and carbon dioxide, the situation improves, but the problem is not completely solved. Metal splashes require cleaning and spoil the appearance of the product. This is especially critical when working with thin materials or non-ferrous metals.

Pulse welding is designed to solve this problem.

Welding of metals can be performed in several ways: gas flame, electric arc, electron beam, laser radiation, friction and even ultrasound.

What is pulsed arc welding

Pulse-arc welding became possible after the invention of the inverter energy source. It is a controlled process of metal transfer in a protective gas environment. This method is used when working with aluminum and stainless steel. Its essence consists in cyclically repeating the following process:

1. Under the influence of a powerful current pulse, one drop of welding wire metal is separated and transferred to the product.
2. The current is reduced to a value that allows the welding arc to be maintained, but not enough to separate and transfer metal.
3. The weld pool at the junction of the products cools down.
4. The cycle repeats.

High quality seams are possible thanks to precise control of welding current pulses. At the same time, no splashing is ensured. The pulse frequency varies in the range of 30-300 Hertz. Each of them ensures the transfer of only one drop of metal into the weld pool. An example of such a welding machine is MERKLE HIGHPULSE 350 DW.

Why is shielding gas needed?

During the welding process, the molten metal in the weld pool may come into contact with ambient air. In this case, as a result of reaction with oxygen, a metal oxide is formed. This is a porous and fragile compound. Shielding gas is needed to prevent its formation. It displaces oxygen from the working area and serves as a kind of barrier.

Neat seam welded with pulsed arc welding

Differences between pulsed arc welding and classical semi-automatic welding

Pulse-arc welding with a consumable electrode has a number of differences from classical semi-automatic:

• pulse welding is more efficient;
• there is no spattering of metal and no need to clean up the heat-affected area;
• metal burnout is reduced;
• welding is possible in any spatial position, which the classical method cannot provide;
• the zone of temperature influence and, accordingly, the deformation of products is reduced.

Advantages of pulsed arc welding

• absolute controllability of the metal transfer process;
• ability to work with thin materials;
• ensuring better metal penetration;
• reduction of metal overheating and smoke formation.

Flaws

• the maximum wire feed speed is lower than in classical semi-automatic welding;
• limited choice of shielding gases.

Contact welding of products

Resistance pulse welding

Pulse resistance welding is another well-known method of joining metals. Its other name is resistance welding or fusion welding. It is fundamentally different from pulsed arc welding. In this case, an electric current is passed through two separate products in pulses.

At the point of contact of the elements being connected, resistive heating occurs due to high resistance. As the current increases, the temperature at the point of contact between the products rises so much that the metal melts. The result is a spot weld.

For such purposes, for example, the BLUEWELD PCP 28 resistance welding machine is intended.

Resistance welding is an effective and economical way to join metals. If you limit the amount of electric current, you can achieve a weak connection between metals. This phenomenon can be used to tack parts before welding.

Pulse welding is an absolute achievement in the technology of joining metals using electric current. It allows high-quality performance of types of work that classical semi-automatic welding cannot provide.

Source: https://www.Toool.ru/articles/impulsnaya_i_kontaktnaya_svarka_osobennosti_preimushchestva_i_nedostatki.html

What is pulse welding

The process of creating continuous welds by melting at specific points and then coating them is called pulse welding. Equipment that has this function, during breaks between regularly repeated pulses, operates in a state of low-power pilot arc, passing only part of the pulse current.

Such an arc in pauses between pulse excitations does not have a significant effect on the depth of metal melting. Due to this, stable arc burning in space is achieved, craters from weld points are completely eliminated while reducing the required overlap areas at the weld site.

Choosing an appropriate ratio of arc currents (pulse and standby) can also significantly speed up the welding process.

By using a pulsed arc as a heat source, the capabilities of traditional gas shielded arc welding can be significantly expanded. Pulsed-arc welding technology is characterized by arc pulsation modes (volume and speed of heat introduction into the workpiece). They are determined by a specific program, based on the thickness and properties of the materials being joined, as well as the position of the seams in space, etc.

If welding is carried out with non-consumable electrodes, then a pulsed (or pulsating) arc serves as a tool for influencing the base metal to form a weld.

When using consumable electrodes, it is intended to regulate the melting and transfer operations of the electrode metal. During the pulsed-arc welding process using tungsten electrodes, the arc pulsation has a constantly set ratio of pulses to pauses.

Obtaining a continuous connection is achieved by melting individual points when covering them subsequently.

Application of pulse welding

The most important parameters characterizing this process include the duration of pulses with pauses, the entire cycle and the pitch of points with the welding speed. The ability to penetrate a pulsating arc with a predetermined cycle and pulse duration is determined by the pulsed welding mode and its rigidity. This technology parameter in its extreme value is characteristic of the arc welding option.

With traditional welding with a continuous arc, it is equal to zero, and with spot welding with an arc it tends to infinity. By adjusting the impulse characteristics, it is possible to influence both the size and shape of the welding zone, the process of crystallization of metals, and the formation of seams, residual or temporary deformations, and other characteristics of the welding progress.

When determining the welding mode using this method, important importance is attached to the pitch of the points, especially when connecting thin-sheet materials.

The ability to penetrate a pulsating arc gives the greatest effect when pulsed welding aluminum with sheet thicknesses less than 3 mm.

The possibility of rational use of the surface tension of metals during pulsed-arc welding creates the necessary conditions for the proper formation of a seam, regardless of its position in space.

This explains the active use of the properties of a pulsed arc when making seams in the ceiling, vertical or horizontal position on metal products of the widest range of thicknesses and for automatically welding sections of pipes with non-rotating joints.

Pulse welding machines most often use welding converters as a power source, equipped with current regulators with interrupters, operating at direct currents.

The use of consumable electrodes in them is advisable in situations where the arc is constantly burning, and a pulsed current is superimposed on the normal welding current from time to time. The predominance of the electrodynamic force leads to the separation of the droplet.

In this way, a directed transfer of metal is carried out in frequency commensurate with pulses at a current value an order of magnitude less than the critical one.

Therefore, in contrast to the use of non-consumable electrodes, pulsed spot welding using a consumable electrode is much more productive and can significantly reduce welding deformation with equal quality characteristics of the resulting joints.

It is most effective in important structures made of various grades of steel, copper, nickel, aluminum and titanium alloys for seams of any spatial orientation. This welding option contributes to good stabilization of the arc in space.

Considering the ability of long electrodes to extend, it is effectively used when making butt joints when processing edges with narrow slots from thick sheets of metal.

Features of magnetic pulse welding

The principle of magnetic pulse welding is the use of the electromechanical force of eddy currents. When pointed at the walls of the workpiece, they intersect with the lines of magnetic forces of the pulsed field and with the magnetic flux. At the same time, electrical energy is converted into mechanical energy, and magnetic field pressure pulses act on the parts directly, without the help of special transmission media.

The process of such welding involves the instantaneous transfer of pressure to the workpiece at the speed of magnetic fields, and not only certain areas, but the entire part are set in motion.

To ensure consistent movement of the contact zone, the workpieces are placed with their edges to be joined at an angle to each other. The connection is formed during collisions of mating parts.

At the same time, the cumulative jet cleanses the joined surfaces from dirt and oxides and plastic deformation of the surface layers of materials with the formation of chemical bonds between them.

The magnetic-pulse connection is carried out according to three traditional pulse welding schemes: compression of products made of tubular materials, their distribution and deformation of sheet material.

In the first case, an inductor that wraps around the product is used, in the second, it is placed inside the workpiece, and in the third, a flat inductor is used.

To avoid deformation of thin-walled parts during welding, special metal mandrels are inserted into the inside of the pipes, which are removed upon completion of the work.

The use of this welding technology is most effective in the production of various structures from tubular parts, welded both among themselves and in combination with other workpieces. Using the capabilities of pulsed laser welding is necessary when connecting flat workpieces along internal or external contours. At the same time, it is possible to weld various materials in any combination in a wide range of thicknesses.

Source: https://promplace.ru/svarka-metallov-staty/impulsnaya-svarka-1541.htm

Understanding pulse welding

Today, many welding technologies are successfully used: contact, electric arc, pulse, laser welding, and several highly specialized metal welding techniques. The modern and most effective method is pulsed high-quality welding, which uses special welding equipment. This technique was developed as an alternative to arc welding, more productive and universal in application.

Features of pulse welding technique

The essence of this technology is to connect metals using short micropulses, the current source for which is a battery connected to an electrical circuit. A distinctive feature of the method is the ability to obtain permanent connections of individual parts made of metals of different compositions. To carry out welding work using pulsed current, you need to use specialized tools: a welder, consumables.

Welding unit is a device that provides dosage of welding pulse energy.

Consumables can be non-consumable or consumable electrodes, depending on the choice of which welding work can be carried out in two ways:

• pulsed arc using non-consumable electrodes;
• with the use of consumable electrodes, control over penetration, transfer of electrode metal into the mass of the weld, and splashing of molten metal particles is carried out.

Pulse welding is a controlled cyclic process of metal transfer in a protective gas environment:

• a high-power micropulse separates one drop of electrode metal and transfers it to a metal workpiece;
• the current drops to a value that only allows maintaining the welding arc, but does not allow the separation of a drop of metal and its transfer;
• Next comes the cooling of the product in the weld pool;
• the work cycle repeats.

The operating principle of pulsed units is based on converting the mains voltage into direct voltage and then into high-frequency voltage. The welder includes:

• electronic control unit;
• inverter;
• low frequency, high frequency rectifier;
• transformer;
• working shunt.

The scheme is quite simple, it allows you to carry out the work yourself, while obtaining reliable, high-strength connections of products made of different compositions of steels, non-ferrous metals, and other materials. The welding process does not require a lot of time; the energy reserve of the battery (mains receiver) is used for operation, which is pre-charged from the mains to the required value.

Pulse-type welding units prevent molten metal particles from splashing and allow you to produce homemade seams.

The pulse and duty arcs must be set to the exact value so that the work process is as efficient and safe as possible, and craters will not form in the areas where individual metal elements are joined.

This technology has its own distinctive features, the main one of which is the rigidity of the regime. This parameter characterizes the duration of the micropulse. If the welder changes some settings in the welding process, he may change the welding parameters. Plus, the shape of the weld pool can be adjusted, and the crystallization process of the metal can also be controlled.

It is possible to normalize a homemade weld and adjust the limits of possible deformation thanks to some settings functions.

Pulse welding is often used to join sheet metal with a thickness of more than 3 mm. The technology is ideal for forming seam joints in different spatial projections.

Advantages of the technique

Thanks to this technology for joining metal samples, the operating mode of which is adjusted by the welder, its following advantages can be noted:

• High-quality, durable, perfectly straight welded seam.
• When connecting individual parts by weight, the formation of burns is virtually eliminated.
• Possibility of metal transfer when using consumable electrodes.

Conclusion

By using pulsed welding mode, the most effective result can be achieved using consumable electrodes. It is especially important to use such welding when it is necessary to apply a root layer.

Source: https://electrod.biz/vidy/razbiraemsya-v-impulsnoy-svarke.html

Pulse welding: advantages and capabilities

Semi-automatic welding in protective gas environments is by far the most advanced technological approach to the implementation of metal joints.

But this group of welding methods is not free from drawbacks, which manifest themselves in melt spattering and difficulties in maintaining standard arc parameters.

Pulse welding helped to solve these problems in many ways, which requires the use of special equipment and compliance with special organizational rules, but from the point of view of the quality of the weld it is completely justified.

Features of the technology

The method involves applying additional current pulses to the base weld, the frequency of which can reach tens of hertz. What is noteworthy is that the percentage of pulse current relative to the main indicator is up to 15%. Today, technologies for delivering double pulses under modulation conditions are also being developed.

This makes it possible to change the angles of thermal exposure, shape and gables. For the operator, this means increased process functionality in terms of the ability to control fine droplet metal transfer.

In other words, pulsed-arc welding does not minimize the same effect of melt spattering with increasing consumption of electrode powder, but provides more means for its regulation.

If we talk about differences from conventional semi-automatic welding, then the pulsed-arc technique also eliminates the need to clean the work area, is characterized by reduced metal burnout, and also provides more space for directing the current. And all this is achieved in the same temperature conditions.

What equipment is used

These are mainly devices that operate in MIG/MAG welding modes and support the ability to smoothly adjust currents. There are two groups of pulse welding machines:

• Models with an integrated (automatic) gas-cooled wire feed system.
• Models with an optional (connected) wire feed system. In this case, liquid cooling is provided.

In both options, the operator can count on the ability to precisely control the frequency and size of droplets of the metal melt that are transferred to the weld pool. Similar functions are present in standard semi-automatic machines, but there is a fundamental difference in two points. Firstly, the current adjustment range extends from the minimum to the maximum value.

Secondly, the pulsed arc, regardless of operator control, prevents short circuits and almost eliminates spatter. When working with non-ferrous metals, the possibilities of detailed configuration of the device for specific operating modes are especially evident. For example, a modern semi-automatic machine with a pulse mode for welding aluminum supports synergetic control, which allows automatic adjustment of the thickness of the workpiece and the speed of the wire direction.

The new MIG-Pulse modes, for example, also prevent the formation of beads by crushing the crystals in the melt zone.

Preparing the device for operation and setting up

First of all, the main components of the welding station are connected. The design will include the inverter itself, transformers or converters from the power source, a gas cylinder and a burner. Next, optimal modes are installed.

For example, how to set up the pulse mode of TIG welding? This is done through the control panel of the device, where you can set the type of welding process, as well as specific parameters for current strength, wire thickness, etc. By the way, the range of frequency pulses is usually from 0.5 to 300 Hz. The higher the frequency, the more operational effects can be realized automatically. In particular, this concerns reducing the size of pores in the structure of the seam and narrowing the arc.

Conversely, in the low range more efficient control is realized in terms of position selection. Thus, experienced welders consider the arc direction from bottom to top (PF mode) to be the most optimal.

Advantages of contact pulse current

This type of welding with frequency regulation is also called resistance welding or fusion welding. What distinguishes it from arc techniques is that a pulsed current is passed through two separated products.

What advantages does this give? New opportunities and advantages of pulsed contact welding are determined by an increase in the current strength that occurs at the point of contact of two products. To melt the metal, less load on the equipment is required, and the current strength and temperature conditions increase.

The result is a reliable and precise connection with a neat seam. By the way, all regulatory capabilities are preserved when performing resistance welding.

Advantages of pulsed TIG welding

The combination of pulsed current mode and TIG welding is not often used, but it has a number of important advantages. To the greatest extent, they relate to the possibility of reducing heat input, but are not limited to this. When working with thin sheets of stainless steel at high frequencies, precise weld formation can be achieved.

Changing the current parameters during TIG welding from maximum to minimum with pauses also allows you to minimize heating of the workpiece and its warping. At medium frequencies, it is possible to achieve a more efficient concentration of currents, which promotes deep penetration at standard heat input rates. Also, due to the fine-crystalline structure, welding of stainless steels at a medium pulse frequency ensures high corrosion resistance of the weld.

In the future, there is no need to apply special protective coatings, since the structure of the material itself does not support the development of rust.

Advantages of pulsed MIG welding

The main feature of this method is the non-contact method of transferring the melt from the wire to the welding zone. In combination with a pulsed current mode, this approach provides the following advantages:

• Saving gas and wire resources. Consumables with lower parameters are used, and the protective gas environment can be used for various tasks without the selection of additional torches and tips.
• Low smoke and spatter. Again, due to a higher degree of control and power costs, the thermal impact process is, in principle, optimized and negative factors are reduced.
• High performance. In the MIG mode, pulsed welding provides higher melt efficiency with the same technical and operational parameters of the equipment.
• Reliability and safety. Comprehensive control of the welding process is expressed not only in the regulation of spatter and automation of individual functions, but also in the support of a whole set of protective options with shutdown in case of overheating.

When to use pulsed current welding

The technology was developed primarily for stainless steel and today is one of the most effective methods for welding such steels.

At the same time, the scope of its application has expanded significantly, covering operations related to the processing and joining of low-carbon steels, aluminum, copper, as well as silver and titanium.

Spot pulse welding also works well when connecting thin-walled parts made of both ferrous and non-ferrous metals. Especially the combination of pulsed current with a tungsten electrode makes it possible to minimize the risk of burning through workpieces in the form of thin sheets from 1 to 50 mm.

Weaknesses of pulse welding

Like all welding technologies, including modern ones, the pulse method is not without its drawbacks. Despite its pronounced advantages, it is rarely used in solving typical problems due to the high cost of equipment, increased organizational costs and a number of negative technological nuances.

In particular, the TIG pulse welding mode is characterized by low productivity and low wire feed speed. The use of other modes is limited by high requirements in terms of the selection of mixtures with protective gases.

That is, the method is mostly highly specialized and is only suitable for use in individual operations under certain conditions.

Conclusion

The ability to precisely regulate the current is a logical continuation of the concept of inverter semi-automatic welding, which makes welding processes more flexible and functional. Another thing is that along with the expansion of the optional, various restrictions on the use of the method are also imposed.

At the amateur level, of course, the need for pulsed welding, with all its advantages, is not yet so obvious. The same investments in equipment and consumables are unlikely to be justified even taking into account the production of a high-quality seam.

The situation is different in industry and professional construction, where minimizing melt spatter in in-line welding justifies organizational difficulties.

Source: https://www.alfamag.pro/poleznoe/poluavtomaticheskaya-svarka/1032-impulsnaya-svarka-preimushchestva-i-vozmozhnosti.html

Pulse welding: modes, circuit, device

10.01.2019

Pulsed welding is based on the traditional electric arc method, but the current is supplied to the poles in a pulsed mode. What is it from an applied point of view - a seam formed by even drops of melt. The pulse welding mode allows you to control the process of pool formation, significantly expands the capabilities of the traditional arc method, is used for dissimilar metals, and forms a diffuse joint.

Types of pulse welding

Selection of connection parameters depending on the type of metals being fused. There are four possible device options:

1. Capacitor, they are used for stainless alloys and aluminum. They differ in power characteristics, there are models over 100 kA. They are characterized by a strong, maximally dosed energy burst.
2. Magnetic pulse welding is characterized by the connection of parts under high pressure arising from an induced magnetic field. The seam is formed under the influence of temperature and compression. This type of apparatus allows you to weld homogeneous and dissimilar metals with good productivity. The magnetic-pulse type of welding is based on the principle of eddy current electromechanics. When they intersect with a magnetic field, mutual attraction of the parts occurs; they are pressed with great force into the melt zone, forming a homogeneous structure. The edges of the parts are positioned at an angle relative to each other. As a result of plastic deformation, chemical bonds are formed.
3. In inertial models, a design feature is a powerful flywheel driven by an electric motor. The kinetic energy of the flywheel is transferred to pulsed currents, causing inertial resonance.
4. Rechargeable ones are characterized by a durable design and low impact of network drawdown on the operation of the device. Short circuits that occur when igniting the electrode or filler wire in semi-automatic machines are instantly stabilized. Alkali is used as an electrolyte filler for the battery.

Source: https://svarkaprosto.ru/tehnologii/impulsnaya-svarka

Pulse welding

More and more advanced technologies are appearing in welding. One of them is pulse welding. Pulse welding technology is used in various fields: in the construction of modern pipelines, in industrial and civil construction and in everyday life.

This type of welding is effective in working with structures made of steels and alloys of copper, aluminum, nickel, titanium and other non-ferrous metals. It is used in welding butt joints when processing edges with narrow slots made of thick sheet metal.

Pulsed arc welding was developed as an alternative to arc welding, which has many complaints about quality and productivity.

Condenser

Capacitor welding is carried out by units of both low and high power. The maximum output current of powerful units can reach 100,000 A or more. Capacitor-type welding machines are distinguished by high accuracy in dosing the energy spent on the welding pulse. This welding is carried out using a strong burst of energy and is intended for joining aluminum and stainless steels.

Inertial

This type of welded joint is based on the use of the accumulated energy of a rotating massive flywheel of a generator. To accelerate and rotate the flywheel, the design contains an electric motor. The kinetic energy accumulated by the flywheel, after reducing the speed, is transferred to welding current pulses. To perform inertial welding, a pulse welding inverter is used - a device whose operating principle is to use pulse resonance.

Magnetic pulse

Magnetic pulse welding equipment converts electrical energy into mechanical energy. This occurs due to the induction of a magnetic field. Under its action, and under the influence of high pressure, a welded connection occurs between the parts. Magnetic pulse welding is used in joining any materials, both homogeneous and dissimilar in composition.

Rechargeable

Machines designed for cordless welding use alkaline batteries. They have a robust design and can withstand short circuits well.

What to choose – semi-automatic welding or pulsed arc welding?

Recently, semi-automatic pulsed arc welding has become widespread. It consists of a welding torch and an automated welding wire feeder. I must say that this is the only automated operation.

The advantages of this type of welding include high productivity and continuity of the welding process. But the method also has disadvantages. This is, first of all, metal spattering during welding. Almost 30% of the wire does not fall exactly into the seam.

Metal splashes require additional labor to clean them up, which in turn spoils the appearance of the product.

Manual pulse welding does not have these disadvantages. The use of this welding technology allows us to obtain the highest quality welding parameters. It combines the best achievements of other technologies. Here are its main advantages:

• The welding joint is reliable, with smooth edges;
• Defects in the form of burns and non-fusion are practically eliminated;
• Effective arc monitoring;
• Controllability of the metal transfer process;
• No metal splashes;
• Rational wire consumption;
• Welding is performed on metals of different compositions;
• Minor costs for processing seams.

Pulse welding is used in the installation of pipelines for various purposes. For these designs, seam penetration and a well-formed back bead that does not require stripping are very important. This seam is highly durable.

The disadvantages of the technology include the impossibility of using it over large welding areas and the need for intensive cooling of the inductor.

DIY pulse welding machine

At home, you can make a welding machine with your own hands. Spare parts for this device can be easily found on sale, but some subtleties must be taken into account.

Particular attention must be paid to transistors, as they quickly fail. Therefore, it is better not to skimp on these details. A homemade welding inverter is equipped with four transistors, which are connected to insulated radiators.

In order to correctly assemble a pulse welding machine, it is necessary to calculate its power and current. Examples of calculations can be viewed on the Internet. The installed filter will help maintain a voltage of 220 V. To assemble your device, you will need tools and special devices, such as an oscilloscope, soldering iron, multimeter, voltmeter, etc. During assembly, safety precautions must be observed.

Source: https://svarkalegko.com/oborudovanie/impulsnaya-svarka.html

Welding: technology :: Pulse welding - what is it and how to use it?

Electric arc welding has been around since the 1880s, and the technology has remained essentially the same since then - creating an arc by applying a voltage between an electrode and a workpiece made up of separate parts that need to be joined together.

But in most cases of application of this type of welding at that time, it had significant limitations in terms of controlling the welding process.

Most power supplies were equipped with only an adjustable output to set the DC voltage, and this limited the evolutionary progress in terms of further development of power supplies.

By 1950, there were three main types of metal transfer: short arc, a low-current metal transfer process, a process that occurs at higher currents than short arc welding, resulting in droplets of molten metal larger in diameter than the wire and electrode itself, and a jet arc welding process that uses higher currents to join parts together.

In 1960, welding technology developers found a way to quickly adjust the current. This opened the door for the emergence of pulsed welding, which helped eliminate the controversial aspects inherent in the transfer of molten metal by traditional welding methods.

In pulsed arc welding, the voltage is not constant; The welding current increases to a peak value when a droplet is formed, and then the current decreases to reduce the excess heat input to ensure uniform formation and transfer of droplets into the weld pool and, ultimately, to stabilize the welding process.

These oscillations or pulses depend on the shape of the current wave, a controlled change in the characteristics of the welding process, which significantly changes the very technology with which the welder performs high-quality welding.

In the 1990s, welding current wave characteristics were improved as companies moved to inverter platforms that were fully digitally controlled, as opposed to the analog control networks used in power supplies. Welding process developers have greatly expanded their ability to control the welding process using digital commands.

What can a wave do?

It can significantly speed up the pulse welding process. In the early 2000s, US industry experienced a boom in an attempt to remain competitive in the face of globalization. Manufacturers who wanted to maintain their advantage in the local market needed to improve the productivity of their production processes to maintain and improve their position relative to companies from countries with low labor costs.

This has led to the development of technologies with improved arc impulse transfer and shorter arc lengths than traditional pulsed welding. As a result, the metal transfer speed and technology productivity have increased.

Due to the higher speed of the electrode, it was possible to achieve a significant reduction in heat input, in addition, metal spattering was reduced compared to traditional pulsed processes.

Short and dense current fluctuations enable precise control of droplet transmission. Once the droplet is transferred, it contacts the weld pool and short-circuits the current. The short circuit signal immediately corrects the waveform of the operating current, which allows the process to be more stable and faster.

The advanced pulse technology can be used for a variety of semi-automated and robotic applications, increasing electrode speed by more than 50% compared to a simple pulse process.

Nowadays, welding speeds of 50 inches per minute are no longer unusual in automated applications in modern factories. New pulse welding technology allows the process to be focused. The use of improved waveform characteristics is not limited to large companies that require miles of finished welds every day.

The new technology is also useful for manual welding. Typical pulsed arc welding produced better droplets of weld metal than other types of welding, but the process was not ideal for joining metal when the electrode was in an awkward position. Adjusting the operating current waveform solves this problem.

Advanced Control works in the same way as the conventional pulse process, but controls the frequency, increasing the consistency of the seam. The arc is produced at a lower voltage than conventional welding, allowing the welder to work with a smaller weld pool volume. This provides an additional sense of freedom for welding professionals.

They can change the focus and size of the droplets at any time, improving and simplifying control of the weld pool formation process.

Advanced Pulsed Aluminum Welding

Aluminum is increasingly used in the manufacture of various structures that require maximum reliability with minimum weight. The obvious advantages of this metal have attracted increased attention to improving aluminum welding technology. In turn, this has necessitated the development of welding methods that utilize efficient adjustment of the welding current waveform.

One of the latest developments is the technology of alternating current welding of aluminum with variable current amplitude , which significantly improves existing pulsed methods of joining parts, even taking into account the fact that this somewhat contradicts the generally accepted method of using direct current for aluminum welding.

This method reduces excess heat input by redirecting incoming energy to negative polarity (Figure 2). Moreover, switching the polarity removes a layer of oxide film from the metal surface. This process is easily digitally controlled.

The welder can fine-tune the amount of alternating current to increase or decrease the heat delivered to the part. In this case, the frequency of the power source current is not fixed at 60 Hz, in contrast to the traditional technology of aluminum welding with alternating current.

This, in turn, allows novice welders to minimize the risk of burn-through when working with aluminum parts, and experienced welders to facilitate the process of welding thin metal and ensure high-quality filling of seams.

The technology for adjusting the welding current waveform has great promise. The development and improvement of pulse welding is proceeding at an astonishing rate thanks to the ability of digital control, and the range of combinations of different welding processes is limitless.

Fortunately, the development of practical applications determines the direction of development and research in this direction. Since there is always an interest in achieving greater productivity in welding processes, this leads primarily to improving and increasing the speed of pulse transmission in the welding process.

In fact, the development of pulsed welding technology has reached the point where welders in operation can easily change the parameters of the welding current waveform to achieve the greatest efficiency.

In some cases, depending on the power source used, experienced welders have the ability to change the characteristics of the welding current waveform, depending on the heat output required for a given wire feed speed or electrode movement.

Digital current adjustment systems have not eliminated the need for skilled technicians, but they do help provide greater stability to the welding process. The current challenge is to promptly inform specialists about new methods and technologies, since now, in our time, welding processes change dramatically within a few months, and not decades, as was the case in the 20th century

Source: https://kovkapro.com/svarka/impulsnaya-svarka-chto-eto-takoe-i-kak-ispolzovat/

Do-it-yourself pulse welding: instructions, diagram, characteristics and use of the device

First, let's figure out what it is. If, when using electric arc welding, we also turn on short electric pulse signals, then we will get pulsed welding.

In this case, the main thing is not to draw a parallel of this type with spot welding.

Pulse spot welding and pulsed arc welding are completely different methods of welding metal parts.

Converter

To begin with, it is necessary to consider the process of assembling a pulse converter. It is accordingly designated as the power element of the welding unit.

The diagram shows the transducer assembly model.

In technical literature and reference books you can find information on the components that are included with the converter.

Control mechanism

In this figure you can see a clear and understandable control diagram, as well as elements of the diagram, which shows the process of starting the electric unit.

Adapter

A descriptive representation of the pulse adapter is shown in the accompanying diagram.

“Soft Launch” is located here.

Assembled device

Just look at the figure below to have a simple idea of ​​the appearance of this type of welding.

The body is also attached to a frame with airflow, a control adapter (it is an integral part of the body), and a plug for welding current.

The electrical fuse and power adapter must also be located on the housing.

Practice of use

Devices assembled as stated in the instructions work for a long time. Welding joints are quite strong.

A homemade pulse welder is only suitable for household use, but it is not suitable for professional work. The costly part of assembling such a welder will not leave any owner indifferent.

The voltage required for the operation of such a device should be within 220 V. But sometimes there may be voltage failures, especially if the work is carried out in a country house.

Despite this, the arc has stable and easy ignition. The most suitable type of electrodes for a homemade welding device are electrodes that melt.

This type of welding is quite strong and has a completely stable arc ignition.

In order to assemble a homemade pulse welding machine, you only need to allocate a little free time. And the result will not remain unjustified.

This will be the most economical option, based on the need to perform welding work. And this does not in any way affect the quality of the work performed.

Priorities of a welding machine manufactured in-house

The pulse welder differs from factory models in many characteristics. A serious advantage is low energy consumption.

The energy costs for performing a minor weld using a factory machine will be high. And of course, not all electrical wiring can withstand such power.

Regarding the weight of the homemade device, we can say that it is small. And its dimensions can be several times smaller than the factory ones. It is very difficult to move a factory apparatus without much effort.

To avoid moving it from place to place, you can use special electrical extension cords. But their cost is very high.

Therefore, a homemade welding machine would be a suitable option for use at home. And its weight will not exceed 10 kg.

The production resource of production welding devices has a limitation. And often it may not exceed 50-80%.

Therefore, the totality of all available technical capabilities cannot always be revealed. Based on this, the duration of welding work will be insignificant, within 3 minutes without a break.

A homemade welding machine does not lead to loss of electrical energy because there are no reactive currents. Non-critical power allows you to use the outlet even in the house, without worrying that the network may not be able to withstand it.

The power of such a pulse welder is exactly the same as in household appliances.

The duration of operation of a homemade pulse apparatus can be more than 15-20 minutes. Which exceeds the operating time of the mechanism that was bought in the store. And of course, the light weight (8-10 kilograms) will not cause difficulties in home use.

By assembling a pulse unit on your own, you can minimize the cost of assembled materials.

For example, instead of welding cables, use a regular cable with a cross-section of up to 12 square millimeters. And use the wire from electrical household appliances for power supply.

Peculiarities

Let us dwell on the advantages of homemade impulse welding machines.

To stabilize the ignition of the welding arc, it is best to resort to working with a transformer, which has a significant degree of inductance.

But at the same time, a decrease in current strength may occur, since alternating current is mainly used, and the efficiency is very low.

Despite this, if the devices operate on direct current, a special choke helps regulate the current itself. Because of this, the recovery process of the arc is reduced.

It goes without saying that direct current is used. But do not forget to monitor the inductance of the inductor. If it exceeds the standard values, the electrode may simply stick to the surface, which must be welded.

If you keep the inductance of the inductor at a low level, and the frequency of the current on the contrary, then you can still achieve arc ignition without delay.

A little conclusion

Everyone who has a summer cottage or a car garage needs a device for pulsed arc welding. It would be perfect to do it yourself.

Anyone who sets such a goal can have such a welding machine. And you don’t even have to call a specialist to repair any metal structure.

The reliability of a homemade pulse apparatus is low, since it consists of the most common parts. And to increase the service life, you can use just a sheet of durable metal.

Source: https://prosvarku.info/tehnika-svarki/impulsnaya-svarka-svoimi-rukami

Pulse arc welding - review of technology and equipment

Pulsed arc welding is a type of arc welding, only with additional impulses of current, which constantly changes from direct to alternating. The frequency ranges from 20-250 Hz. The converted signal varies in waveform and angle, changing porosity and deflection. These indicators affect welding modes and properties.

Inverter-pulse welding machines have a number of advantages and are used in various industrial niches. The method is a process of melting wire under the influence of high temperature heating of the arc and transferring the molten material into the bath with virtually no dispersion of particles. When a current pulse is generated, a drop of liquid metal is formed, which falls into the zone of connection of two metal surfaces.

When the temperature decreases, when there is no current pulse, the surface cools. This method allows you to work with thin metals without burning through them. Spot welding is another method of joining metals that involves mechanical force. This technology was invented at the beginning of the twentieth century, found its recognition and began to actively develop.

Nowadays, even a beginner who has not fully studied all the basics of welding can use a machine for this type of welding.

What are the types of welding arc?

The order of formation of the welding arc is distinguished into four types:

• drip. There is no short circuit during the formation of this type. Almost no metal drops are created. The process requires predominantly an argon mixture and high current;
• long. To form this arc, great power will be required, and the presence of carbon dioxide in the gas mixture will be at least twenty-five percent. Forms large droplets;
• short. Metal transfer is due to the formation of large droplets;
• impulse. A pinch effect occurs when the arc becomes hotter than usual. The pulsed current creates conditions for the formation of a drop. Easy to adjust using frequency and current. Ideal for tight work spaces.

There are other metal transfer technologies. If the current strength is higher than the arc current values, then a drip arc of increased power occurs. It is capable of cutting deeper into the metal, but it can lead to distortion of the joint. As the voltage increases, the arc will spin. This leads to an increase in the melting zone. This method is used for working with thick metals, but in a completely mechanized process.

What should be highlighted when selecting equipment

According to their characteristics, installations for inverter-pulse welding are more powerful than those for arc welding. This is due to the fact that during the work a wider pool is created, the filler rod is fed faster, and a large selection of welding parameters requires additional resources. Here are the main characteristics considered first:

• The greater the power of the unit, the more preferable it is. But be guided by the capabilities of the electrical network from which the device will operate. It should not be lower;
• built-in functions of the pulse machine ensure correct control and do not require in-depth knowledge of the welder, pay attention to synergetic control;
• choose a large burner with quick switching to another type of work;
• the device indicating voltage should not be attached to the machine; purchase ones that have the ability to work remotely and are transferred to the welder’s field of vision.

Adjusting the amplitude and wavelength helps make the welder's work easier. This improves the quality of welding and creates the most favorable conditions for choosing an individual mode. Previously, the power setting was automatic, and it had to be set by pressing a certain button. Nowadays, modern devices are equipped with built-in memory, which remembers all previous settings in the appropriate mode.

Use the required cable meter that will suit your workplace. Long cables need to be coiled, which will lead to a change in the current wave and a decrease in the efficiency of pulse welding, and a cable that is too short will not allow precise movements of the torch.

If you are a novice welder, be sure to read the article on how to choose welding equipment for a beginner.

Advantages of MIG welding

Pulse-arc welding according to international standards is usually designated MIG (Metal Inert Gas). Its application is extensive and has a number of positive aspects:

• cost-effectiveness of wire. It is enough to have one medium-sized coil without changing rods of different diameters;
• saving on gas. Gas mixtures are used for different processes in the same composition;
• no need to spend money on consumables in the form of mouthpieces, solders and burners. The devices are fully equipped;
• high welding speed does not require cleaning from droplets and additional processing of the device;
• the ability to weld thin sheets of metal from 0.7 to 2 mm;
• eliminating seam deformation.

Every technological process has its downsides, but here there are not many of them:

• such welding machines are an order of magnitude more expensive than conventional ones;
• claim more thorough care.

Application area of ​​pulse welding

There is no manufacturing industry where welding processes are not used. Here are some of them:

• when working with different pipe diameters;
• in the automotive industry;
• production of railway cars;
• in the construction of bridges and buildings;
• manufacturing of cargo and heavy equipment;
• in the ship repair business.

Pulse welding has unlimited possibilities. With its help, you can join any metal with an unbreakable and durable seam due to the minimum hydrogen content. This technology makes the joint susceptible to environmental influences, especially under conditions of significant loads.

In addition, pulse welding is used in small repair shops and service stations. It is a priority for most American industries.

Source: https://svarka-weld.ru/impulsnaya-dugovaya-svarka