Small welding machine
In view of the fact that in everyday life, ordinary people often need to work with metal, many use welding machines.
But not everyone can afford the purchase of expensive equipment, which is why the question arises, how to assemble a welding machine with your own hands.
The manufacturing process will differ depending on the type and design features of the welding device.
The modern market is filled with a fairly large variety of the best welding machine brand, but not all of them are advisable to assemble with your own hands.
Depending on the operating parameters of the devices, the following types of devices are distinguished::
- AC-output AC voltage from the power transformer directly to the welding electrodes.
- the direct current-output constant voltage at the output of the welding transformer.
- three-phase – connected to a three-phase network.
- inverter devices-issuing a pulse current to the working area.
The first version of the welding unit is the simplest, for the second you will need to modify the classic transformer device with a rectifier unit and a smoothing filter. Three-phase welding machines are used in industry, so we will not consider the manufacture of such devices for household needs. An inverter or pulse transformer is quite a complex device, so to assemble a homemade inverter, you must be able to read the circuits and have basic skills in assembling electronic circuit boards. Since the base for the creation of welding equipment is a step-down transformer, consider the order of manufacture from the simplest to the more complex.
According to this principle, classical portable welding machines work: the voltage from the primary winding of 220 V is lowered to 50 – 60 V on the secondary and is fed to the welding electrode with the workpiece.
Before you start manufacturing, select all the necessary elements:
Magnetic core-composite cores with a sheet thickness of 0.35 – 0.5 mm are considered more profitable since they provide the least losses in the iron of the welding machine.
It is better to use a ready-made core made of transformer steel, since the tightness of the plates plays a fundamental role in the operation of the magnetic circuit.
Wire for winding coils-the cross-section of the wires is selected depending on the magnitude of the currents flowing in them.
Insulation materials-the main requirement, both for sheet dielectrics and for the native coating of wires-resistance to high temperatures.
Otherwise, the insulation of the welding semi-automatic or transformer will melt and a short circuit will occur, which will lead to the failure of the device.
The most profitable option is to assemble the unit from a factory transformer, in which both the magnetic core and the primary winding are suitable for you.
But, if there is no suitable device at hand, you will have to make it yourself. The principle of manufacturing, determining the cross-section and other parameters of a homemade transformer can be found in the corresponding article:
In this example, we will consider the option of manufacturing a welding machine from a microwave power supply.
It should be noted that transformer welding should have sufficient power, for our purposes, a welding machine of at least 4 – 5KW is suitable.
And since one transformer for a microwave oven has only 1-1.2 kW, we will use two transformers to create the device.
To do this, you will need to perform the following sequence of actions:
Take two transformers and check the integrity of the wingdings powered by the 220V power supply.
Cut the magnetic core and remove the high-voltage winding,
Fig. 1: Cut the core
Figure 2: Remove the high-voltage winding
leaving only the low-voltage one, in this case, you do not need to wind the primary coil, since you use the factory one.
Remove the current shunts from the coil circuit on each transformer, this will increase the power of each winding.
For the secondary coil, take a copper bus with a cross section of 10mm2 and wind it on a pre-made frame made of any available materials.
The main thing is that the shape of the frame repeats the dimensions of the core.
Figure 3: Wind the secondary winding on the frame
Make a dielectric gasket for the primary winding, any non-flammable material will do. In length, it should be enough for both halves after connecting the magnetic circuit.
Figure 4: Make a dielectric gasket
Place the power coil in the magnetic core. To fix both halves of the core, you can use glue or pull them together with any dielectric material.
Figure 5: Place the coil in the magnetic core
Connect the primary leads to the power cord, and the secondary leads to the welding cables.
Figure 6: Connect the power cord and cables
Install the holder and the 4 – 5mm diameter electrode on the cable. The diameter of the electrodes is selected depending on the strength of the electric current in the secondary winding of the welding machine, in our example it is 140 – 200A.
With other operating parameters, the characteristics of the electrodes change accordingly.
In the secondary winding, 54 turns turned out, to be able to adjust the voltage value at the output of the device, make two taps from the 40 and 47 turns.
This will allow you to adjust the current in the secondary by reducing or increasing the number of turns. The same function can be performed by a resistor, but only in a smaller direction from the nominal value.
On direct current
Such a device differs from the previous one by more stable characteristics of the electric arc, since it is obtained not directly from the secondary winding of the transformer, but from a semiconductor converter with a smoothing element.
Figure 7: Rectification circuit diagram for welding transformer
As you can see, you do not need to wind the transformer for this, it is enough to modify the scheme of the existing device.
Thanks to this, it will be able to produce a more even seam, cook stainless steel and cast iron. For manufacturing, you will need four powerful diodes or thyristors, about 200 A each, two capacitors with a capacity of 15,000 UF, and a choke.
Figure 9: Connection diagram of the smoothing device
Install the semiconductor elements on the cooling radiators.
Figure 10: Install the diodes on the radiators
Exercise machines for home for all muscles:
Due to overheating of the transformer during operation, the diodes can quickly fail, so they need forced heat removal.
Connect the diodes to the bridge, as shown in the figure above, and connect them to the transformer terminals.
Figure 11: Connect the diodes to the bridge
For connection, it is better to use tinned clamps, as they will not lose their original conductivity from high currents and constant vibration.
Figure 12: Use tinned clamps
The wire thickness is selected according to the operating current of the secondary winding.
Connect the power capacitors and the choke to the secondary circuit of the diode bridge.
Figure 13: Connect the power capacitors
Connect the welding loops to the terminals of the smoothing device, install the electrode holders – the DC welding machine is ready.
When welding metals with such a device, it is always necessary to control the heating of not only the transformer but also the rectifier. And when the critical temperature is reached, pause to cool the elements, otherwise, the welding unit, made with your own hands, will quickly fail.
It is a rather complex device for novice radio amateurs. An equally complex process is the selection of the necessary elements.
The advantage of such a welding machine is significantly smaller dimensions and lower power, in comparison with classic devices, the ability to implement spot welding, etc.
Figure 14: schematic diagram of the pulse unit
In operation, such a circuit converts an alternating voltage from the mains to a constant voltage, then, using a pulse unit, outputs a high-amplitude current to the welding area.
This results in a relative saving of the device’s power in relation to its performance.
Structurally, the inverter circuit of the welding machine includes the following elements
control system based on a driver and two transistors
the power part consists of a control transistor and an output transformer
the output of the diodes and choke
cooling system from the cooler
current feedback system for monitoring the output parameter of the welding machine.
To make a welding inverter, you will need to wind a power transformer yourself, a current transformer based on a fer rite ring. For the bridge, it is better to use a ready-made assembly of high-speed semiconductor elements.
Unfortunately, most of the other items are unlikely to be at hand in the garage or at your home, so they will have to be ordered or purchased in specialized stores.
Because of this, the assembly of the inverter unit with your own hands will not be cheaper than the factory version and taking into account the time spent, it will also be more expensive.
Therefore, for inverter welding, it is better to purchase a ready-made device with the specified operating parameters.
APC Mini ARC-200D
Welding in domestic conditions (in rural areas, farm households, in a cottage).
Details – corner, pipe, up to 6 mm thick, sheet, strip with a thickness of 3-5 mm.
Welding mode – medium duration (PV=40-50%).
Network – 220V, network voltage-low, 170-190V, power cable extension more than 30m.
Welding current – 50-150A.
The electrodes are 2.0 – 4.0 mm.
The fast and the furious-180 NEON VD-183 torus-200 classic
Why it is profitable to buy a welding inverter the “SAWAKO-ST”
We have extensive experience with welding equipment, we do not have untested and unreliable products.
We test the equipment before selling and sending it to the buyer, perform warranty and post-warranty repairs of inverters, so we know everything about them.
We guarantee you low prices.
For buyers from the regions of the Russian Federation, we deliver the goods free of charge to the terminal of the transport company.
You can buy a welding inverter in St. Petersburg in LLC “SEVEKO-ST” with a guarantee, maintenance, and convenient delivery in Russia.
Read more :
All parts of this article:
- How to choose a welding inverter. Household models, brands, examples of choice.
- How to use the welding inverter correctly? Popular models.
- Choose a professional welding inverter.
- Selection and features of the power supply network for a professional inverter.
- Professional inverter-examples of selection for specific tasks.
BARS welding inverters-decent quality and reasonable prices >
In addition, the tool is easy to learn and quite effective. The choice of a semi-automatic for carrying out bodywork has its own characteristics and nuances.
Which welding semi-automatic machine to choose for car repair
To carry out a successful repair of the car body, you need to choose the right welding equipment.
When purchasing a semi-automatic machine, pay attention to a number of parameters, such as the power source, the power of the device, the adjustment of the wire feed speed, the volume of cylinders for technical gases.
When choosing equipment, the first thing you need to pay attention to is the power source of the device.
According to the connection principle, there are inverter and transformer semi-automatic machines. Inverters are light, compact and easy-to-use equipment.
It is equipped with a number of additional functions that significantly facilitate the welding process: easy ignition, anti-sticking, smooth current control.
The semi-automatic inverter is equipped with a device used to convert AC to DC. Transformers are necessary if there is no need to regularly move the equipment from place to place. A direct current source is used to power such equipment.
welding of the car body
Wire and its influence on the welding result
Semi-automatic welding machines use wire. It acts as an electrode and is designed to connect the elements to be welded. Welding wire is divided into the following types:
With a solid cross-section.
The advantage of the first type is that it is designed for welding metals, and has different alloys in its composition.
The cored wire is hollow inside, it is filled with a special substance. When it is used, a cloud of protective gases is formed.
As for the activated electrode, it has only 7% of the powder substance in its composition, which allows it to be pressed into a solid wire.
wire for welding
Also, when choosing a wire, you should pay attention to its marking. Electrodes marked SV are used for welding parts, and the NP marking says that the consumable material is used for surfacing.
In addition, attention is paid to the diameter of the wire, and the elements that make up it.
Read also: How to choose an anti-corrosion paint for your car
About the balloons
To prevent the interaction of molten metal and the environment, use cylinders with protective gases: argon, helium, carbon dioxide and their mixtures.
The live wire is passed through the gas nozzle. To supply gas to the working area, use a hose.
Working with protective gases requires a gearbox. The device allows you to adjust the gas consumption. For ease of use, the device is equipped with a pressure gauge.
When performing welding work, it should be borne in mind that an excessively small amount of protective gases will affect the quality of the seam, and too much will also affect the density of the welded joint, in addition, the gas will run out quite quickly.
When choosing a cylinder, you should pay attention to 10-liter copies: with the correct setting of the gas flow, this volume is enough for long-term work. The dimensions of the container make it possible to transport it in the trunk of the car.
When buying, it is worth considering that the cylinder must be certified. A corresponding mark will be placed near the valve.
It is necessary to check the date of certification in order to avoid the acquisition of “delay”.
What else to consider in the selection
When choosing a device for welding of a car body, take into account the following factors:
Load capacity of the electrical network. In the presence of a single-phase network, it is recommended to choose a device that operates from a voltage of 220V.
These can be both amateur and professional welding semi-automatic machines operating from both three-phase and single-phase networks.
When using the latter, the network is provided with a uniform load. This prevents the risk of short circuits and disconnecting traffic jams.
The type and thickness of the materials to be welded. The device is selected depending on what metals to work with (low – carbon or stainless steel, non-ferrous metals, aluminum, etc.).
Also pay attention to the thickness of the metal-the larger it is, the more powerful the device is required.
Requirements for the quality of welding and the type of welded joints. The key role in the choice of a semi-automatic welding machine is played by the degree of responsibility of the welded structure.
In addition, in some cases, there are situations where it is necessary to use a burner longer than the standard dimensions. As a rule, they occur when welding long structures.
The burners are 3, 4 and 5 meters long, and for fast and high-quality metal connection, use burners with a maximum length.
The intensity of device usage. Depending on the frequency of use of the device, buy amateur or professional welding semi-automatic machines.
Technical complexity of the device. The more complex the device, the more difficult it is to repair it yourself. However, technically more complex devices are convenient to use and provide high quality of the weld.
Semi-automatic welding machine – a tool for carrying out body repairs. The choice is made depending on the complexity and intensity of the work, the type of electrical network from which the device will be powered, as well as the technical complexity of the device.