If the welding point is covered with a layer of flux, the arc will be buried under the flux and cannot be seen, this welding process is called submerged arc welding. This feature of submerged arc welding makes the weld pool protected by flux, and there are fewer impurities in the weld, resulting in higher welding quality. Submerged arc welding is rarely done by hand, but is automatically completed by a special submerged arc welding machine, so it is also called submerged arc automatic welding. For Class II pressure vessel manufacturing enterprises, having a submerged arc welding machine is one of the important inspection indicators.

Fan Shibin, the head of the technical section, and Feng Xu, the director of the container workshop, have both visited submerged arc welding in the petrochemical machine, and have some understanding of the working principle of the submerged arc welding machine, but they are not clear about how it works internally.

As a graduate student majoring in mechanical engineering, Lin Zhenhua is naturally very familiar with the working principle of submerged arc welding. Submerged arc welding was a relatively new technology in that era, but in the era of Lin Zhenhua's life, it was a very ordinary technology, and there would be a schematic diagram of the welding machine on any welding process tutorial. Zhu Tiejun inadvertently told Lin Zhenhua about submerged arc welding, originally just wanted to ask Lin Zhenhua if he had heard of this technology, but who knew that a few days later, Lin Zhenhua actually directly handed over a set of welding machine drawings to him.

With drawings, it does not mean that a submerged arc welding machine can be manufactured immediately, and many related technical parameters, such as welding current, arc voltage, wire diameter, wire inclination, welding speed, etc., need to be determined through experiments. Of course, there are also contents of these parameters in the textbooks of later generations, but Lin Zhenhua cannot remember them so clearly. What's more, some parameters are to be adjusted according to the practical situation, and the different composition of flux and the different types of steel will affect the selection of parameters, and these problems can only be solved through repeated experiments.

The research team was set up under the leadership of Zhu Tiejun, and the first thing Lin Zhenhua did was to give a lesson to everyone, explaining the principle and process essentials of submerged arc welding, and a group of engineers and welders at the most level of Hanhua Machinery Factory sat down to listen to the class, including Lin Zhenhua's quasi-father-in-law Yang Chunshan. Zhu Tiejun also held a notebook and sat on the side to record, although this little old man was born in the army, he also has a deep interest in industrial technology.

"Xiaolin, after listening to your introduction, I feel like I have a number in my heart. However, if you say that so many parameters need to be tested, then don't we have to do thousands of experiments? Fan Shibin questioned.

"Thousands of experiments? When do you have to go? Hao Songlin, a welder, muttered.

"A few thousand experiments isn't a lot." Hu Yang interjected, "It is very normal to master a technology and conduct thousands of experiments. In the past, when our country introduced a certain torpedo technology from the Soviet Union, in order to master the trajectory of the torpedo, hundreds of torpedoes were fired, and one torpedo was tens of thousands of yuan. ”

"Since Master Hu has said so, let's start trying. Xiaohua, you open a work order, and we will do it according to your requirements. We have more than a dozen welders, and we all work together, and thousands of experiments are also very fast. Yang Chunshan said briskly, he is Lin Zhenhua's iron-clad backing.

Zhu Tiejun hesitated: "How much does it cost to spend thousands of experiments?" Kobayashi, is there a better way, it is better to do less experiments. ”

Lin Zhenhua sighed and said: "Alas, in fact, you don't need to experiment so many times, if you can construct a change curve of several parameters, then it is enough to select a few nodes to carry out experiments." ”

Zhu Tiejun asked: "Xiaolin, I don't understand what curve you are talking about." However, how can you make a curve like you said, what kind of curve or something? ”

Lin Zhenhua said: "Constructing these curves requires some calculations, which are quite easy if you have a computer. But where are I going to get a computer now? ”

Fan Shibin smacked his tongue and said: "Forget it, I just heard that there is a computer in the provincial computing center, which costs hundreds of yuan for an hour, and you have to open a letter of introduction to use it, how can we afford it." ”

Hu Yang asked, "Xiao Lin, what kind of knowledge do you need to use for the calculations you said?" We don't have computers, so if we mobilize all the literate workers in the factory to count together, is it okay? ”

Lin Zhenhua shook his head: "Lao Hu, this calculation is not a four-rule operation, I want to do a finite element analysis ......."

"What do you say? Finite Element? There was a strange light in the poplar's eyes.

"Well, it's a calculation anyway, it doesn't matter what it's called." Lin Zhenhua hurriedly sloppily said, the word finite element is too difficult for the people of Hanhua Factory.

Who knows, Hu Yang is biting and not letting go: "Xiaolin, I once saw the concept of finite element in mechanical magazines, but I don't know what is going on, could it be you?" ”

Lin Zhenhua stubbornly said: "I also barely know some, but to do the simplest finite element analysis, it also involves operations such as matrices and differential equations, which may be ......."

Hu Yang turned his head to Zhu Tiejun and Fan Shibin and said: "Director Zhu, Section Chief Fan, as you all know, I have a high school degree, and I also like to read some books over the years, I know a little bit about matrices and differential equations that Xiaolin said." Otherwise, I will take the initiative to ask Ying to cooperate with Xiaolin to do finite element analysis, do you think it is okay? ”

"Absolutely." Fan Shibin and Zhu Tiejun looked at each other, and immediately said: "Speaking of which, I also learned these things when I was in college, but they have been useless for more than ten or twenty years, and I have almost forgotten them." I just calculated that our factory can do matrix operations, and it is estimated that a slap can be calculated, and their situation is similar to mine. If Master Hu could still remember and help Xiao Lin do this calculation, it would be great. ”

Zhu Tiejun stood up and said, "Okay, let's stop here today, Master Hu, you and Xiao Lin discuss what this is called, and see if you can help Xiao Lin do it." Submerged arc welding is something we must do. It would be best if you could do less experimentation through calculations. It's really not good, thousands of experiments are thousands of experiments, and it's worth spending some money to get the Class II container certificate. ”

Everyone dispersed with their admiration for Lin Zhenhua, and only Populus euphratica remained. Lin Zhenhua looked at Populus Hu and said with a sad face: "Master Hu, do you really plan to do finite element analysis by hand?" ”

Hu Yang nodded and said, "That's right, what computers can do, people can also do." It's just that I haven't studied finite element analysis, I don't know what it's going on, can you tell me? ”

Lin Zhenhua said: "Master Hu, tell me first, how well you have mastered matrices and differential equations, you said that you have a high school degree, these things are not high school knowledge." ”

Hu Yang smiled and said: "Xiaolin, I don't have any other hobbies, I just like to learn something new." Although I only have a high school degree, I have also taught myself all advanced mathematics. Let me say a big thing, matrices and differential equations, the general topics must not be difficult for me. ”

"Okay, I'll tell you about finite element analysis." Lin Zhenhua said, "The so-called finite element analysis is to replace complex problems with some relatively simple problems and then solve them. The core idea is to treat the solution domain of a complex problem as composed of many small interconnected subdomains called finite elements, assume a suitable and relatively simple approximate solution for each element, and then deduce the total satisfaction conditions of the solution domain to obtain the solution of the problem. ”

Hu Yang listened carefully to Lin Zhenhua's explanation, repeating it in his mouth, as if he wanted to forcibly fill this knowledge into his mind.

After Lin Zhenhua said this, he asked a little uneasily: "Master Hu, you see me say this, can you understand?" ”

Hu Yang nodded: "I roughly understand, this idea should actually have a long history, the idea of calculus, isn't that?" ”

"That's right." Lin Zhenhua said, "However, the finite element method was officially proposed in the 60s. In just over a decade, this method has been widely used in Western engineering circles, involving almost all technical fields. ”

A haze flashed in Hu Yang's eyes: "Alas, look at us for more than ten years, we have been tossing blindly, and I don't know how far we have traveled abroad." ”

Lin Zhenhua hurriedly comforted him and said, "Master Hu, don't worry, it's too late for us to start chasing now." Hasn't the Party Central Committee already proposed a scientific spring? A self-taught engineer like you would be useful. ”

"Don't talk about that." Hu Yang waved his hand, "Xiaolin, you still tell me how finite element analysis is done." ”

"Okay, let's start with a simple example...... Lin Zhenhua spread out a piece of paper, wrote a model for Populus euphratica, and then began to introduce the basic idea of finite element analysis to Populus Hu step by step.

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Asking for recommendation votes, I have to stand on the new book list before I can get a strong push and be able to put it on the shelves......