The primary problem of electric welding, the problem of welding knowledge

My understanding of arc starting is the moment when a spark is made on the workpiece, my personal habit of arcing is that the electrode is not directly put on the workpiece, but (a bit similar to spot welding) instant contact, after the arc starting, the electrode and the workpiece can continue to weld within a certain distance, of course, if the speed is too slow, the coating of the welding rod may not be there, you will definitely be like this when you start to learn, there is no coating to protect the electrode, you will definitely be stained on the welding on the workpiece. In fact, if you pay attention to those masters, the moment they weld is to quickly touch the workpiece a few times (I don't know how to say that word).

In general, if you are a novice, you should pay attention to whether the electrode coating wraps the welding core, if not, it is to take a quick contact to start the arc first, if the coating falls off too much, you can also take drag welding (that is, the welding rod moves quickly backwards or other directions at the moment when the electrode arcs off the workpiece.

In fact, I don't make it very clear to you, this is mainly to rely on yourself to explore, since you have a master, you can ask him for more advice. If conditions permit, find some scrap heads to practice more, the most important thing is to look at other people's techniques, how others operate at the moment of arcing. However, many masters can't tell you everything, the key is to have your own vision, watch more, ask more, practice more, and don't be afraid of getting tired.

Arc initiation is also the arc initiation of electric welding. Generally, there are two methods, one is to wipe the arc, which is similar to the technique we use to wipe matches, but after leading the arc, the welding rod should not be too far away from the wood, and it should be kept at about 2-3 mm. The second is the collision hair, that is, the welding rod is used to hit the base metal to cause arc, and after causing the arc, a certain arc must be maintained as well as the arc wiping.

The arc current is different with different electrodes.

Pay attention to the current, you can also adjust it too high, not too low, the reference material is not different! More experience in practice. Isn't it just beginning? Keep trying! Good luck with your studies!

Arc starting is generally divided into scratch type and contact type. The electrode you use should be 120A.

The scratch type is like a match, but the arc should not be too high, and the arc length and height should be controlled after the arc is drawn, and the hand should be steady.

The contact type is easy for the electrode to stick, and the joint is prone to porosity.

Pressure vessel welders generally use the scratch type.

Summary. Hello dear, I am happy to answer for you, dear hello, welding questions: 1. Crack phenomenon, crack phenomenon has two kinds of hot cracks and cold cracks, and hot cracks are the gaps that appear when the metal develops from a liquid state to a solid state, which generally appears in the middle position and is easy to find.

Cold crack is the fusion of the base metal produced when the weld metal is cooled or after a period of aging after welding, or the area where the base metal and the weld merge. 2. Undercut. Undercut refers to the pit at the edge of the weld, and there may be two reasons for the formation of undercut, one is caused by too large welding current or too fast speed or too long arc drawing, and the other is caused by the welding speed of submerged arc welding too fast or the unequal track of the welding machine.

3. Stomatae. The most common cause of porosity is that the edge of the groove has not been cleaned, leaving dirt or moisture. 4. Not welded through, not fused.

Failure to penetrate is when the root of the joint is not fully penetrated during welding. Unfused is a phenomenon of local unmelted bond between the weldment and the weld metal or weld layer. Lack of penetration and fusion are serious defects in the welding of metal materials, which will lead to the discontinuity of the weld, reduce the strength of the weld, and then cause cracks.

5. Slag inclusion. Slag inclusion refers to the slag left in the weld, if mine is helpful to you, you can give me a thumbs up after the consultation, I wish you all the best.

I would like to ask how to identify a solar panel weld virtual weld.

Hello dear, I am happy to answer for you, dear hello, welding questions: 1. Crack phenomenon, crack phenomenon has two kinds of hot cracks and cold cracks, and hot cracks are the gaps that appear when the metal develops from a liquid state to a solid state, which generally appears in the middle position and is easy to find. Cold crack is the fusion of the base metal produced when the weld metal is cooled or after a period of aging after welding, or the area where the base metal and the weld merge.

2. The cherry blossom bite. Undercut refers to the pit at the edge of the weld, and there may be two reasons for the formation of undercut, one is caused by too large welding current or too fast speed or too long arc drawing, and the other is caused by the welding speed of submerged arc welding too fast or the unequal track of the welding machine. 3. Stomatae.

The common reason for the collapse of the pores is that the edge of the groove is not cleaned, leaving dirt or moisture. 4. Not welded through, not fused. Failure to penetrate is when the root of the joint is not fully penetrated during welding.

Unfused is a phenomenon of local unmelted bond between the weldment and the weld metal or weld layer. Lack of penetration and fusion is a serious defect in the welding of metal materials, which will lead to intermittent clumps of welds, reduce the strength of the weld, and then cause cracks. 5. Slag inclusion.

Slag inclusion refers to the slag left in the weld, if mine is helpful to you, you can give me a thumbs up after the consultation, I wish you all the best.

There are two types of electric welding machines: AC and DC, and most of the ordinary welding machines used in our daily work are AC. The AC welding machine has the advantages of simple structure, convenient maintenance, high efficiency, saving electric energy and materials, long service life, and no magnetic bias blowing during welding

The AC welding machine is generally single-phase, and before use, it is necessary to check whether the rated voltage of the winding is consistent with the power supply voltage (whether it is 380V or 220V), and check whether the wiring on the terminal board is correct. If it is an AC welding machine that has been put into operation for the first time or has been out of service for a long time, the insulation resistance of each winding to the core and each other should be measured with a 500V megohmmeter before use, and it should not be lower.

The primary side power cord of the AC welding machine can use BXR type rubber insulated copper core flexible wire, and the secondary side welding cable can use YHH type rubber sheathed copper core flexible cable.

The nuts, copper lugs and wires on the terminal board on the primary and secondary sides of the AC welding machine must be in close contact and reliable, if the contact is not good, the bolts, nuts and lugs will burn rings. Therefore, after running the welding machine for a period of time, the oxide layer on each contact surface should be wiped clean with a fine abrasive cloth, and then the bolts should be tightened.

The housing of the welding machine must be grounded, and a separate wire should be connected to the grounding trunk. When a plurality of welding machines are connected with a grounding device, the method of parallel connection should be adopted, and it is forbidden to connect them in series. Before the welding work is completed, the grounding wire cannot be removed at will.

If multiple AC welding machines are required to work at the same time, the welding machines should be evenly tapped on the three-phase electricity to make the three-phase load balanced.

The welding machine should not work in high humidity (relative humidity more than 90%), high temperature (above 40), and unventilated occasions, and should be kept away from flammable and explosive materials. The placement of the welding machine should be stable, and violent vibration and knocking should not be avoided, so as not to damage the performance of the reactor and make the welding machine unable to work normally. The welding machine should be kept clean and dry, and the cleaning should be carried out regularly with low-pressure dry compressed air.

Short circuit between the electrode and the welding piece should be avoided for a long time to prevent the welding machine from being burned.

In case of faults such as the welding machine does not arc, the winding is overheated, the welding current cannot be adjusted, and the welding machine vibrates or makes too loud noise, the machine should be stopped in time to find the cause and carry out maintenance.

1: The arc temperature of argon arc welding is generally between plasma arc and manual arc welding arc, the arc temperature is 9000-10000k, the plasma arc is 16000-32000k, the manual arc is 5000-6000k, the melting pole argon arc welding arc temperature is 10000-14000k, and the oxyacetylene flame is 3100-3200k

It is mainly caused by welding dust and respiratory tract infections and lung infections; Electricity is welding, arc light causes myopia; Noise causes hearing loss.

2: Electric welding is the workpiece and the electrode connected to the different poles of the power supply (positive or negative), the electrode and the workpiece instant contact with Sun Yinyin makes the air ionized to produce an arc, the arc has a very high temperature, about 5000-6000K, so that the surface of the workpiece melts to form a molten pool, and the metal of the electrode is coated on the surface of the workpiece to form a metallurgical bond.

Roughly divided into: Fusion welding. Pressure welding.

There are three kinds of brazing, but what you call electric welding is all the welding with electricity, then it is wide, or arc welding, the full name of arc welding, that is, electrode arc welding, is also the most widely used, belonging to the scope of fusion welding, fusion welding also includes gas shielded welding (etc.), submerged arc welding, electroslag welding, gas-electric vertical welding, laser welding, electron beam, etc. CO2 is mainly used in heavy industries such as shipbuilding, characterized by high production efficiencyLarge penetration depth. The welded joint has good plasticity, etc. TIG is non-MIG/MAG welding, that is, tungsten TIG welding, TIG welding is suitable for thin parts, high quality requirements, accurate construction, this welding method has shallow penetration and low production efficiency, MIG is MIG, MIG, is MIG/MAG, mostly used for aluminum-magnesium alloy welding, this welding is similar to carbon dioxide, submerged arc welding is mainly used for welding large and thick parts, and the production efficiency is extremely high, and other applications are not very wide, roughly that's all.

My personal opinion is as follows:

Looking at the second picture, there is only 1 weld, and the first picture does not look like 1, because if there is 1, there should not be an obvious inflection point of the fusion line at the circle part; Unless there is a gap in the base metal;

In the first picture, the base metal and the weld on the upper surface are almost flat, and it is difficult to achieve this effect by welding, and it is suspected that it has been polished and processed after welding;

However, if there is an over-penetration protrusion, it is basically that the arc is too concentrated, and the shape of the fusion line can be improved by increasing the voltage and decreasing the current;

The joint is a lap joint, and the requirements for strength and fatigue will not be very high, as long as the root is fused, there is no obvious stress concentration between the weld fusion zone and the base metal, which should be acceptable.

Due to different products and different processes, there will be different acceptance ranges for welding defects. Whether the first picture is qualified or not, I dare not assert. The above comments are for your reference.

Apprentice, do you think your current skills can handle all the welding work on the construction site? You can go and find a place to work. Find an older master to help you.

I spent a few months on the construction site to see the various problems of welding and to get in touch with different welding methods. I felt like I couldn't do it and then went back and practiced hard. He was an apprentice in a year!

Increase the voltage a little bit, and increase the angle of the welding torch (welding torch and defective parts) appropriately. Try.

What kind of material are you? What are the performance requirements after welding? What is it used for?

In the welding process, it is common for the molten pool to produce bubbles, and there are many reasons, generally due to the current is too small, the weldment is oily, the welding rod is wet and rusty, the carbon content of the welding material is too high, or the welding material is not a national standard product with too many impurities.

The weld pool is formed after a normal time, a normal temperature, and a slow cooling. If the air, oil and impurities in the molten pool cannot be volatilized and burned off in time during this period, bubbles will be easily generated.

Increase the current appropriately, remove the oil stain and rust spots of the weldment before welding, and dry (sun-dry) the electrode.

In the specific operation, the arc column can not be stretched too long, and a reciprocating transport bar should be adopted.

Pay attention to the above points to avoid bubbles in the weld.

In addition, as an aside, many people who are engaged in carbon dioxide gas shielded welding and beginner welding do not have the habit of wearing face masks, which is not good. To be corrected, it is strictly forbidden to use chemical fiber fabrics in tooling, and it is strictly forbidden to be shirtless and barefoot. Finally, I wish you all the best in your work and your technology to the next level.