Spot welding machine based on Arduino. Battery spot welding machine Spot welding control unit on an arduino microcontroller

In some cases, it is more profitable to use spot welding instead of soldering. For example, this method may be useful for repairing batteries consisting of several batteries. Soldering causes excessive heating of the cells, which can lead to cell failure. But spot welding does not heat the elements as much, since it operates for a relatively short time.

To optimize the entire process, the system uses Arduino Nano. This is a control unit that allows you to effectively manage the energy supply of the installation. Thus, each welding is optimal for a particular case, and as much energy is consumed as necessary, no more and no less. The contact elements here are copper wire, and the energy comes from a regular car battery, or two if higher current is required.

The current project is almost ideal in terms of complexity of creation/efficiency of work. The author of the project showed the main stages of creating the system, posting all the data on Instructables.

According to the author, a standard battery is enough for spot welding two nickel strips 0.15 mm thick. For thicker strips of metal, two batteries will be required, assembled in a circuit in parallel. Pulse time welding machine adjustable and ranges from 1 to 20 ms. This is quite sufficient for welding the nickel strips described above.

The author recommends making the board to order from the manufacturer. The cost of ordering 10 such boards is about 20 euros.

During welding, both hands will be occupied. How to manage the entire system? Using a foot switch, of course. It's very simple.

And here is the result of the work:

According to the author, a standard battery is enough to spot weld two nickel strips 0.15 mm thick. For thicker strips of metal, two batteries will be required, assembled in a circuit in parallel. The pulse time of the welding machine is adjustable and ranges from 1 to 20 ms. This is quite sufficient for welding the nickel strips described above.

The author recommends making the board to order from the manufacturer. The cost of ordering 10 such boards is about 20 euros.

During welding, both hands will be occupied. How to manage the entire system? Using a foot switch, of course. It's very simple.

And here is the result of the work:

Hello, brainwashes! I present to your attention a spot welding machine based on the Arduino Nano microcontroller.

This machine can be used to weld plates or conductors, for example, to the terminals of a 18650 battery. For the project, we will need a power source with a voltage of 7-12 V (12 V recommended), as well as car battery 12 V voltage as the power source for the welding machine itself. Typically, a standard battery has a capacity of 45 Ah, which is sufficient for welding 0.15 mm thick nickel plates. To weld thicker nickel plates, you will need a larger capacity battery or two connected in parallel.

The welding machine generates a double pulse, where the value of the first is 1/8 of the second in duration.
The duration of the second pulse is adjusted using a potentiometer and is displayed on the screen in milliseconds, so it is very convenient to adjust the duration of this pulse. Its adjustment range is from 1 to 20 ms.

Watch the video, which shows in detail the process of creating the device.

Step 1: Making the PCB

To make a printed circuit board, you can use Eagle files, which are available at the following.

The easiest way is to order boards from manufacturers printed circuit boards. For example, on the site pcbway.com. Here you can purchase 10 boards for approximately 20 €.

But if you are used to doing everything yourself, then use the included diagrams and files to make a prototype board.

Step 2: Installing components on the boards and soldering the conductors

The process of installing and soldering components is quite standard and simple. Install small components first and then larger ones.
Tips welding electrode made of solid copper wire with a cross-section of 10 square millimeters. For cables, use flexible ones. copper wires with a cross section of 16 square millimeters.

Step 3: Foot Switch

To operate the welding machine, you will need a foot switch because both hands are used to hold the welding rod tips in place.

For this purpose I took wooden box, in which the above switch was installed.

An acquaintance came, brought two LATRs and asked if it was possible to make a spotter out of them? Usually, when hearing a similar question, what comes to mind is an anecdote about how one neighbor asks another if he knows how to play the violin and in response he hears “I don’t know, I haven’t tried” - so I have the same answer - I don’t know , probably “yes”, but what is a “spotter”?

In general, while the tea was boiling and brewing, I listened to a short lecture about how you shouldn’t do what you shouldn’t do, that you need to be closer to the people and then people will be drawn to me, and also briefly plunged into the history of car repair shops, illustrated with delicious tales from the life of “chiropper” and “tinsmith”. Then I realized that a spotter is a small “welder” that works on the principle of a spot welding machine. Used for “grabbing” metal washers and other small fastening elements to the dented car body, with the help of which the deformed sheet is then straightened. True, there is also “ reverse hammer“is needed, but they say that this is no longer my concern - only the electronic part of the circuit is required from me.

Having looked at spotter circuits online, it became clear that we needed a one-vibrator that would “open” the triac for a short time and supply mains voltage to the power transformer. The secondary winding of the transformer should produce a voltage of 5-7 V with a current sufficient to “grab” the washers.

To generate a triac control pulse, use different ways– from simple capacitor discharge to the use of microcontrollers with synchronization to the mains voltage phases. We are interested in the simpler circuit - let it be “with a capacitor”.

Searches “in the nightstand” showed that, in addition to passive elements, there are suitable triacs and thyristors, as well as many other “small things” - transistors and relays for different operating voltages ( Fig.1). It’s a pity that there are no optocouplers, but you can try to assemble a capacitor discharge pulse converter into a short “rectangle” that includes a relay, which will open and close the triac with its closing contact.

Also, while searching for parts, we found several power supplies with DC output voltages from 5 to 15 V - we chose an industrial one from “Soviet” times called BP-A1 9V/0.2A ( Fig.2). When loaded with a 100 Ohm resistor, the power supply produces a voltage of about 12 V (it turned out that it had already been converted).

We select TS132-40-10 triacs, a 12-volt relay from the available electronic “garbage”, take several KT315 transistors, resistors, capacitors and begin to prototype and test the circuit (on Fig.3 one of the setup stages).

The result is shown in Figure 4. Everything is quite simple - when you press the S1 button, capacitor C1 begins to charge and a positive voltage equal to the supply voltage appears at its right terminal. This voltage, having passed through the current-limiting resistor R2, is supplied to the base of the transistor VT1, it opens and voltage is supplied to the winding of relay K1, and as a result, the contacts of relay K1.1 close, opening triac T1.

As capacitor C1 charges, the voltage at its right terminal gradually decreases and when it reaches a level less than the opening voltage of the transistor, the transistor will close, the relay winding will be de-energized, the open contact K1.1 will stop supplying voltage to the control electrode of the triac and it will close at the end of the current half-wave of the mains voltage . Diodes VD1 and VD2 are installed to limit the pulses that occur when the S1 button is released and when the relay winding K1 is de-energized.

In principle, everything works like this, but when monitoring the time of the open state of the triac, it turned out that it “walks” quite a lot. It would seem that even taking into account possible changes in all on-off delays in electronic and mechanical circuits, it should be no more than 20 ms, but in fact it turned out to be many times more and plus this, the pulse lasts 20-40 ms longer, and then for all 100 ms.

After a little experimentation, it turned out that this change in pulse width is mainly due to a change in the supply voltage level of the circuit and the operation of transistor VT1. The first one was “cured” by installing wall-mounted inside the power supply of a simple parametric stabilizer consisting of a resistor, a zener diode and a power transistor ( Fig.5). And the cascade on transistor VT1 was replaced by a Schmitt trigger on 2 transistors and the installation of an additional emitter follower. The diagram took the form shown in Figure 6.

The principle of operation remains the same, the ability to discretely change the pulse duration using switches S3 and S4 has been added. The Schmitt trigger is assembled on VT1 and VT2, its “threshold” can be changed within small limits by changing the resistance of resistors R11 or R12.

When prototyping and testing the operation of the electronic part of the spotter, several diagrams were taken, from which time intervals and the resulting delays of edges can be assessed. At that time, the circuit had a timing capacitor with a capacity of 1 μF and resistors R7 and R8 had a resistance of 120 kOhm and 180 kOhm, respectively. On Figure 7 the top shows the state on the relay winding, the bottom shows the voltage at the contacts when switching a resistor connected to +14.5 V (the file for viewing by the program is in the archived appendix to the text, the voltages were taken through resistor dividers with random division coefficients, so the “Volts” scale not true). The duration of all relay power pulses was approximately 253...254 ms, the contact switching time was 267...268 ms. “Expansion” is associated with an increase in shutdown time - this can be seen from pictures 8 And 9 when comparing the difference that occurs when closing and opening contacts (5.3 ms vs. 20 ms).

To check the temporal stability of pulse formation, four sequential switchings were carried out with control of the voltage in the load (file in the same application). On a generalized Figure 10 it can be seen that all the pulses in the load are quite close in duration - about 275...283 ms and depend on where the half-wave of the mains voltage occurs at the moment of switching on. Those. the maximum theoretical instability does not exceed the time of one half-wave of the mains voltage - 10 ms.

When setting R7 = 1 kOhm and R8 = 10 kOhm with C1 = 1 μF, it was possible to obtain a duration of one pulse of less than one half-cycle of the mains voltage. At 2 µF - from 1 to 2 periods, at 8 µF - from 3 to 4 (file in attachment).

IN final version spotter, parts with the values indicated on Figure 6. What happened on the secondary winding of the power transformer is shown in Figure 11. The duration of the shortest pulse (the first in the figure) is about 50...60 ms, the second - 140...150 ms, the third - 300...310 ms, the fourth - 390...400 ms (with a timing capacitor capacity of 4 μF, 8 μF, 12 μF and 16 µF).

After checking the electronics, it's time to tackle the hardware.

A 9-amp LATR was used as a power transformer (right on rice. 12). Its winding is made of wire with a diameter of about 1.5 mm ( Fig.13) and the magnetic core has an internal diameter sufficient to wind 7 turns of 3 parallel folded aluminum bars with a total cross-section of about 75-80 sq. mm.

We disassemble the LATR carefully, just in case we “fix” the entire structure in the photo and “copy” the conclusions ( Fig.14). It’s good that the wire is thick - it’s convenient to count the turns.

After disassembly, carefully inspect the winding, clean it of dust, debris and graphite residues using paint brush with hard bristles and wipe soft cloth lightly moistened with alcohol.

We solder a five-amp glass fuse to terminal “A”, connect the tester to the “middle” terminal of coil “G” and apply a voltage of 230 V to the fuse and the “unnamed” terminal. The tester shows a voltage of about 110 V. Nothing buzzes or gets hot - we can assume that the transformer is normal.

Then we wrap the primary winding with fluoroplastic tape with such an overlap that we get at least two or three layers ( Fig.15). After this, we wind a test secondary winding of several turns flexible wire in isolation. By applying power and measuring the voltage on this winding, we determine required quantity turns to obtain 6...7 V. In our case, it turned out that when 230 V is supplied to the “E” and “unnamed” terminals, 7 V is obtained at the output with 7 turns. When power is applied to “A” and “unnamed”, we get 6.3 V.

For the secondary winding, “very used” aluminum busbars were used - they were removed from an old welding transformer and in some places had no insulation at all. To prevent the turns from shorting with each other, the tires had to be wrapped with sickle tape ( Fig.16). The winding was carried out so that two or three layers of coating were obtained.

After winding the transformer and checking the functionality of the circuit on the desktop, all the parts of the spotter were installed in a suitable housing (it looks like it was also from some kind of LATR - Fig.17).

The terminals of the secondary winding of the transformer are clamped with M6-M8 bolts and nuts and are brought out to the front panel of the housing. Power wires leading to the car body and the “reverse hammer” are attached to these bolts on the other side of the front panel. Appearance at the home inspection stage is shown in Figure 18. At the top left are the mains voltage indicator La1 and the mains switch S1, and on the right is the pulse voltage switch S5. It switches the connection to the network of either terminal “A” or terminal “E” of the transformer.

Fig.18

At the bottom there is a connector for the S2 button and the secondary winding leads. Pulse duration switches are installed at the very bottom of the case, under the hinged lid (Fig. 19).

All other elements of the circuit are fixed to the bottom of the case and the front panel ( Fig.20, Fig.21, Fig.22). Doesn't look very neat, but here main task there was a reduction in the length of the conductors in order to reduce the influence of electromagnetic pulses on the electronic part of the circuit.

The printed circuit board was not wired - all transistors and their “piping” were soldered to a breadboard made of fiberglass, with foil cut into squares (visible on Fig.22).

Power switch S1 - JS608A, allowing switching of 10 A currents ("paired" terminals are paralleled). There was no second such switch, so S5 was installed as TP1-2, its terminals are also paralleled (if you use it with the mains power off, it can pass quite large currents through itself). Pulse duration switches S3 and S4 - TP1-2.

Button S2 – KM1-1. The connector for connecting the button wires is COM (DB-9).

Indicator La1 - TN-0.2 in the corresponding installation fittings.

On drawings 23, 24 , 25 photographs taken when checking the functionality of the spotter are shown - a furniture corner measuring 20x20x2 mm was spot welded to a 0.8 mm thick tin plate (mounting panel from a computer case). Different sizes"piglets" on Fig.23 And Fig.24– this is at different “cooking” voltages (6 V and 7 V). In both cases, the furniture corner is welded tightly.

On Fig.26 shown reverse side plate and you can see that it heats up through and through, the paint burns and flies off.

After I gave the spotter to a friend, he called about a week later and said that he had made a reverse “hammer”, connected it and checked the operation of the entire device - everything is fine, everything works. It turned out that long-duration pulses are not needed in operation (i.e. elements S4, C3, C4, R4 can be omitted), but there is a need to connect the transformer to the network “directly”. As far as I understand, this is so that the surface of the dented metal can be heated using carbon electrodes. It is not difficult to supply power “directly” - they installed a switch that allows you to close the “power” terminals of the triac. The insufficiently large total cross-section of the cores in the secondary winding is a little confusing (according to calculations, more is needed), but since more than two weeks have passed, and the owner of the device was warned about the “weakness of the winding” and did not call, then nothing terrible happened.

During experiments with the circuit, a version of a triac assembled from two T122-20-5-4 thyristors was tested (they can be seen in Figure 1 in the background). The connection diagram is shown in Fig.27, diodes VD3 and VD4 - 1N4007.

Literature:

Goroshkov B.I., “Radio-electronic devices”, Moscow, “Radio and Communications”, 1984.
Mass radio library, Ya.S. Kublanovsky, “Thyristor devices”, M., “Radio and Communications”, 1987, issue 1104.

Andrey Goltsov, Iskitim.

List of radioelements

Designation	Type	Denomination	Quantity	Note	My notepad
	To picture No. 6
VT1, VT2, VT3	Bipolar transistor	KT315B	3		To notepad
T1	Thyristor & Triac	TS132-40-12	1		To notepad
VD1, VD2	Diode	KD521B	2		To notepad
R1	Resistor	1 kOhm	1	0.5 W	To notepad
R2	Resistor	330 kOhm	1	0.5 W	To notepad
R3, R4	Resistor	15 kOhm	2	0.5 W	To notepad
R5	Resistor	300 Ohm	1	2 W	To notepad
R6	Resistor	39 Ohm	1	2 W	To notepad
R7	Resistor	12 kOhm	1	0.5 W	To notepad
R8	Resistor	18 kOhm	1	0.5 W

2017-08-22 at 01:31

There was a need to weld 18650 batteries. Why weld and not solder? Yes, because soldering is not safe for batteries. Soldering may damage the plastic insulator, resulting in short circuit. Welding high temperature is achieved for a very short period of time, which is simply not enough to heat the battery.

Internet search ready-made solutions led me to very expensive devices, and only with delivery from China. Therefore, it was a pleasant decision to assemble it yourself. Moreover, “factory” spot welding machines use some basic homemade components, namely a transformer from a microwave oven. Yes, yes, it is he who will be useful to us in the first place.

List of required battery welding machine components.
1. Transformer from a microwave oven.
2. Arduino board (UNO, nano, micro, etc.).
3. 5 keys - 4 for setting and 1 for welding.
4. Indicator 2402, or 1602, or some other 02.
5. 3 meters of PuGV 1x25 wire.
6. 1 meter of PuGV 1x25 wire. (so as not to confuse you)
7. 4 tinned copper cable lugs type KVT25-10.
8. 2 tinned copper cable lugs type SC70.
9. Heat shrink with a diameter of 25 mm - 1 meter.
10. A little heat shrink 12 mm.
11. Heat shrink 8 mm - 3 meters.
12. Circuit board - 1 pc.
13. Resistor 820 Ohm 1 W - 1 pc.
14. Resistor 360 Ohm 1 W - 2 pcs.
15. Resistor 12 Ohm 2 W - 1 pc.
16. Resistor 10 kOhm - 5 pcs.
17. Capacitor 0.1 uF 600 V - 1 pc.
18. Triac BTA41-600 - 1 pc.
19. Optocoupler MOC3062 - 1 pc.
20. Two-pin screw terminal - 2 pcs.
In terms of components, everything seems to be there.

Transformer conversion process.
We remove the secondary winding. It will consist of more thin wire, and the number of its turns will be large. I recommend cutting it off on one side. After cutting, we knock out each part in turn. The process is not fast. You will also need to knock out the plates separating the windings, which are glued.

After we have the transformer left with one primary winding, we prepare the wire for winding a new secondary winding. To do this, we take 3 meters of PuGV wire with a cross-section of 1x25. Completely remove the insulation from the entire wire. We put heat-shrinkable insulation on the wire. Heat to shrink. In the absence of an industrial hair dryer, I did the shrinking over a candle flame. Replacing the insulation is necessary so that the wire can fit completely into the place for the winding. After all, the original insulation is quite thick.

After the new insulation has been installed, we cut the wire into 3 equal parts. We put together and wind two turns in this assembly. I needed help with this. But everything worked out. Then we align the wires with each other, strip them and put 2 copper cable lugs with a cross-section of 70 on the 2 ends. I couldn’t find copper ones, I took tinned copper ones. By the way, the wires can get in the way, you just have to try. Once put on, take a crimper for crimping such tips and crimp them. Such crimpers are also hydraulic. It turns out much better than knocking it down with a hammer or something else.

After that I took some 25mm heat shrink and put it over the ferrule and the entire part of the wire coming from the transformer.

The transformer is ready.

Preparation of welded wires.
In order to make it more convenient to cook, I decided to make separate wires. I chose, again, super-flexible power PuGV wire 1x25 red. The cost, by the way, did not differ from other colors. I took one meter of such wire. I also took 4 more tinned copper tips 25-10. I divided the wire in half and got two parts of 50 cm. I stripped the wire 2 cm from each side and put on heat shrink in advance. Now I put on tinned copper tips and crimped them with the same crimper. I applied the heat shrink and that’s it, the wires are ready.
Now we need to think about what we will cook with. I liked a soldering iron tip with a diameter of 5 mm at the local radio market. I took two. Now I had to think about where to attach them and how to attach them. And then I remembered that in the store where I bought the wires, I saw zero tires, just with many holes with a diameter of 5 mm. I also took two of them. In the photo you will see how I screwed them on.

Installation of electronic components.
To build the welding machine I decided to use an Arduino board. I wanted it to be possible to adjust both the cooking time and the number of such boilings. To do this, I used a 24-character display on 2 lines. Although you can use any, the main thing is to configure everything in the sketch. But more about the program later. So, the main component in the circuit is a triac BTA41-600. Here are the diagrams of a welding machine for batteries.

Key block diagram.

Connection diagram of the display to Arduino.

Here's how I soldered it all together. I didn’t bother with the board, I didn’t want to waste time on drawing and etching. I found a suitable case and adjusted everything using hot glue.

Here is a photo of the process of finishing the program.

Here's how to temporarily make a welding key. In the future I want to find a ready-made foot key so that I don’t have to occupy my hands.

We've sorted out the electronics. Now let's talk about the program.

Welding machine microcontroller program.
I took some part from this article https://mysku.ru/blog/aliexpress/37304.html as the basis for the program. True, we had to change it significantly. There was no encoder. It was necessary to add the number of boils. Make sure that settings can be made using four buttons. Well, so that the welding itself is carried out using a foot button, or something else, without timers.

#include

int bta = 13; //The output to which the triac is connected
int svarka = 9; // Output welding key
int secplus = 10; // Display a key to increase the cooking time
int secminus = 11; // Display the key to reduce cooking time
int razplus = 12; // Display the key to increase the number of brews
int razminus = 8; // Display the key to reduce the number of brews

int lastReportedPos = 1;
int lastReportedPos2 = 1;
volatile int sec = 40;
volatile int raz = 0;

LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

pinMode(svarka, INPUT);
pinMode(secplus, INPUT);
pinMode(secminus, INPUT);
pinMode(razplus, INPUT);
pinMode(razminus, INPUT);
pinMode(bta, OUTPUT);

lcd.begin(24, 2); // Specify which indicator is installed
lcd.setCursor(6, 0); // Set the cursor to the beginning of 1 line

lcd.setCursor(6, 1); // Set the cursor to the beginning of line 2

delay(3000);
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Delay: Milliseconds");
lcd.setCursor(0, 1);
lcd.print("Repeat: times");
}

for (int i = 1; i<= raz; i++) {
digitalWrite(bta, HIGH);
delay(sec);
digitalWrite(bta, LOW);
delay(sec);
}
delay(1000);

void loop() (
if (sec<= 9) {
sec = 10;
lastReportedPos = 11;
}

if (sec >= 201) (
sec = 200;
lastReportedPos = 199;
}
else
( if (lastReportedPos != sec) (
lcd.setCursor(7, 0);
lcd.print(" ");
lcd.setCursor(7, 0);
lcd.print(sec);
lastReportedPos = sec;
}
}

if (raz<= 0) {
raz = 1;
lastReportedPos2 = 2;
}

if (raz >= 11) (
raz = 10;
lastReportedPos2 = 9;
}
else
( if (lastReportedPos2 != raz) (
lcd.setCursor(8, 1);
lcd.print(" ");
lcd.setCursor(8, 1);
lcd.print(raz);
lastReportedPos2 = raz;
}
}

if (digitalRead(secplus) == HIGH) (
sec += 1;
delay(250);
}

if (digitalRead(secminus) == HIGH) (
sec -= 1;
delay(250);
}

if (digitalRead(razplus) == HIGH) (
raz += 1;
delay(250);
}

if (digitalRead(razminus) == HIGH) (
raz -= 1;
delay(250);
}

if (digitalRead(svarka) == HIGH) (
fire();
}

As I said. The program is designed to work on the 2402 indicator.

If you have a 1602 display, replace these lines with the following:

lcd.begin(12, 2); // Specify which indicator is installed
lcd.setCursor(2, 0); // Set the cursor to the beginning of 1 line
lcd.print("Svarka v.1.0"); // Output text
lcd.setCursor(2, 1); // Set the cursor to the beginning of line 2
lcd.print("site"); // Output text
delay(3000);
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Delay: Ms");
lcd.setCursor(0, 1);
lcd.print("Repeat: times");

lcd.setCursor(7, 0);
lcd.print(" ");
lcd.setCursor(7, 0);
lcd.print(sec);
lastReportedPos = sec;

lcd.setCursor(8, 1);
lcd.print(" ");
lcd.setCursor(8, 1);
lcd.print(raz);
lastReportedPos2 = raz;

Everything in the program is simple. We experimentally adjust the cooking time and the number of infusions. Maybe 1 time is enough for you. I just feel like if you cook it twice, it turns out much better. But it may be different for you.

Here's how it worked out for me. First I checked everything on a regular light bulb. Afterwards I went to the garage (just in case).

Using a microcontroller in such tasks may seem too complicated and unnecessary to some. For another person, a car battery may be enough. But it’s interesting for a homemaker to make homemade products using his own homemade products!

Circuit test on an incandescent lamp.

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