1. welding: a method of connecting two workpieces with or without filler by using heat energy or pressure, or both.

2. Welding types: brazing, oxygen-acetylene welding, CO2 shielded welding, argon arc welding and manual arc welding.

Third, safe operation.

1, electric shock prevention: check whether the welding machine is well grounded before work; Check whether the electrode holder cable is in good condition.

Special attention: 380 volts behind the welder.

2. Prevention of electric arc burns and scalds: Arc light contains a lot of ultraviolet rays, infrared rays and strong visible light, which is irritating to eyes and skin. Do not touch the welded workpiece. When tapping welding slag, use proper force and pay attention to the direction.

3. Protective equipment: welding mask, leather gloves and rubber-soled shoes.

4, equipment safety, AC arc welding machine, electrode holder don't put on the worker or workbench, in order to avoid short circuit, burn out the welding machine. If you find a high fever or a burning smell at work, stop working immediately, turn off the power and report to the teacher.

5, self-prevention of eye burns: human milk drops, eye drops, cold and wet towels are applied to the eyes.

Fourth, the process

1. current selection: 2.5mm recommended value 70-90A (welding position (horizontal, horizontal, vertical and upward))

Formula: I(A)=K*D(mm) empirical coefficient k: d (mm)1-23-45-6.

k25-30 30-40 40-60

2, arc contact friction method gently contact, quickly lift 2-4 mm.

3. Grasp the covered electrode coating angle of the rod, which is basically perpendicular to the workpiece, and the advancing direction is inclined by 5 degrees-15 degrees.

Forward speed: slow, straight forward at a constant speed.

Feed speed (arc length)

4, lateral swing (widen the weld)

dotted line

half moon

circular

Step 5 pause at the beginning

6. After the arc is broken, cool the arc again.

Verb (abbreviation of verb) Note:

1. When you enter the workshop for internship, you should wear work clothes, tie up big cuffs and put your shirt into your pants. Sandals, slippers, high heels, vests, skirts and scarves are not allowed to enter the workshop.

2. It is forbidden to chase and make noise in the workshop, read books and periodicals unrelated to the internship, recite foreign words, listen to the radio and listen to MP3.

3. Practice should be carried out on the designated welding machine. Without permission, other equipment, tools or electrical switches shall not be changed without authorization.

4. Before welding, check whether the grounding of welding machine is good, and the insulation of electrode holder and cable must be good.

5, when welding should stand on the board, no barefoot operation. It is forbidden to touch the conductive part by hand to prevent electric shock.

6. In order to prevent harmful ultraviolet rays and infrared rays, gloves and masks must be worn to prevent arc injuries and burns.

7. Pay attention to the direction of slag discharge to prevent welding slag from flying out and hurting people.

8. After welding, the workpiece is not allowed to be held directly by hand, and it should be clamped with iron tongs.

9, oxygen bottles, argon bottles and carbon dioxide bottles shall not impact and baking exposure.

10, oxygen cylinder mouth is not allowed to have grease or other flammable items, wrench can not have oil pollution.

1 1. Mars is not allowed around the acetylene cylinder, and it should be placed at a certain distance from the oxygen cylinder.

12, clean up the site, equipment and tools after the internship.

Six, equipment safety:

1, the connection points of the lines must be in close contact to prevent heating due to looseness and poor contact.

2, electrode holder shall not be placed on the workbench at any time, so as to avoid short circuit burning out the welding machine.

3, found that the welding machine or circuit fever, should immediately stop working.

4, after operating or checking the welding machine and circuit system must switch, turn off the power supply.

Welder experience

This is the first time for me to enter the welding machine room in person, and it is also the first time for me to weld covered electrode by myself. I used to listen to others talk about the experience of welders. I think it's nothing. It's easy to learn. However, becoming a welder is not that simple. The second theoretical lesson is over, and it's finally my turn to practice by myself! I am very happy in my heart, but I am also very nervous and afraid. After all, it is the first time to contact a welder! I recited the teacher's theory in my mind again, put on a mask and started to do it, thinking it would be very simple and easy, but the covered electrode just stuck to the iron plate, and my heart immediately became nervous. According to the teacher, I immediately swayed from side to side, and the covered electrode really fell off the iron plate! Later, I felt much better, and my heart was not so scared. ...

During the second internship, although the weather was very hot, we still wore our clothes tightly, almost airtight, because we knew the danger! At first, after I rubbed the arc, I held covered electrode very high, only to see the flames rushing down, just like when the rocket lifted off! I think if I hold covered electrode higher, the momentum will be less, so after the first welding, nothing is left on the iron plate except the scattered small iron balls! It's unpleasant to see others welding so well. In this way, all four are welded, and I feel that I have learned nothing! Later, I asked Mr. Lu, only to know that covered electrode had to hold it lower and move it slowly to weld it! After I finished welding, my "masterpiece" obviously still failed the teacher's inspection. I asked my teacher what shortcomings I had, and the teacher analyzed my "masterpiece" one by one. I also compared my own works with others, found out my own shortcomings, accumulated considerable experience and won confidence for myself.

During the third internship, I always adjust the positions of some students. I thought I was learning well, but after I changed my position, I was in a mess! My heart is empty, I don't know why. Later, I asked Mr. Lu again, only to know that I didn't study well! Teacher Lu said: "As a good welder, he can weld well regardless of horizontal, vertical, lying and supine." Yes, only by recognizing your own shortcomings and practicing hard can you make continuous progress.

In short, this internship taught me to be single-minded, rigorous and careful in everything. Only in this way can we do what we should do. I think this internship will be a good start for so many internships in the future.