my scientific age

Chapter 226 Homework!

"Students, this class is about the basics of mechanical manufacturing. Who can tell me what the definition of mechanical manufacturing is?" In the classroom of the Department of Mechanical Engineering, the voice of Professor Zhuang Qianding, the head of the department, echoed around, he stood On the podium, he opened the pure English version of the foreign textbook "Mechanical Engineering" and asked the whole class.

There are about 20 students in the classroom, basically all freshmen from the Department of Mechanical Engineering, and a small number of elective students from the Department of Civil Engineering.

Yu Hua is the only student in the Department of Mathematics.

As one of the very few top mechanical experts in Tsinghua Park, Professor Zhuang Qianding is very talented and excellent. His personal experience is like that of Professor Zhao. After returning from studying abroad, he established the Department of Mechanical Engineering of Tsinghua University by himself.

Bachelor of Nanyang College, Master of Mechanical Engineering from Cornell University, Member of the Honor Society for Scientific Research, Master of Chemical Engineering, former engineer of Boston SW Engineering Company and Detroit Edison Company Power Plant Test Engineer.

This is Professor Zhuang Qianding's education and resume. He has a high attainments in the field of mechanical engineering and is one of the few in the country.

Yu Hua sits quietly at the back of the classroom and systematically learns the knowledge in the field of mechanical engineering. Most of his knowledge of mechanical manufacturing comes from TV, and the knowledge points are extremely basic and one-sided. Only through systematic study can he improve himself at a fundamental level.

With the participation of Professor Zhuang Qianding, the level of the Department of Mechanical Engineering of Tsinghua University is no less than that of the old and famous Nanyang Public School.

"The process of producing mechanical parts and assembling them into city machines, instruments or equipment is called mechanical manufacturing." A boy wearing glasses immediately stood up.

"It seems that this classmate has already previewed it. Yes, this is the definition of machinery manufacturing. The machinery manufacturing industry serves all the needs of people's lives. It is one of the most important industrial categories in the complete industrial system, on a par with the metallurgical industry. ."

Professor Zhuang Qianding nodded with satisfaction, motioned the classmate to sit down, and looked around the crowd: "Processing metal materials into mechanical parts is the main part of machinery manufacturing, and its processing methods are usually divided into three categories, namely hot working, cold working and special Processing, which classmate will come up and talk about the method of thermal processing?"

"There are three methods of thermal processing, casting, forging, and welding." Immediately afterwards, another student who was slightly thinner wearing glasses stood up and elaborated on the three methods of thermal processing.

"Casting, forging, welding, these three methods have their own advantages and disadvantages. The advantage of casting is that it can manufacture parts with very complex geometric shapes. The shape and size are usually close to the parts. Low."

Zhuang Qianding nodded and pressed his hand on the classmate: "The disadvantage is that there are many production processes, the process is difficult to control, the quality is not stable enough, the scrap rate is high, and shrinkage holes, looseness, cracks, gaps, and pores are prone to appear inside. There are defects such as blisters, and the performance of castings is not as good as that of forgings, which classmate will talk about the pros and cons of forging?"

Zhuang Qianding pays great attention to the interaction with students in his lectures, because this can improve the quality of lectures.

If the teacher just writes on the blackboard and speaks on the podium, the students below will be at a loss, the quality of the lectures is very low, and the students have not mastered the knowledge at all.

As soon as this question came out, the classroom was quiet.

"The main advantage of forging is to improve the internal structure of the metal, eliminate the internal defects of the structure, such as cracks, pores and blisters, etc., and improve the mechanical properties of the metal blank. For heavy-duty mechanical parts, such as heavy spindles, connecting rods, etc. Gears, barrels and barrels of military weapons must be processed through a forging process. Then, it has high production efficiency and a wide range of applications. The geometry ranges from simple bolts and nuts to complex crankshaft connecting rods, and the mass ranges from 1 gram to [-] The large shafts of ton-level warships can be manufactured by forging methods.”

Feeling the cold field in the classroom, Yu Hua stood up and elaborated on the forging concept and advantages and disadvantages he just read in the textbook:
"The disadvantage of forging is that it is impossible to obtain parts with complex inner cavities. The material of parts needs to have a certain degree of plasticity, which is powerless for brittle materials such as cast iron, and the forging equipment is expensive. The price of a single air hammer may be as high as tens of thousands of tons. The price of a hydraulic press is as high as 20 yuan, and the price of the first [-]-ton hydraulic press in the United States as an example in the textbook is as high as millions of silver dollars."

"This classmate answered very well, classmate, what's your name?" After hearing Yu Hua's answer, Zhuang Qianding's eyes lit up, and he didn't hesitate to praise himself, and then asked.

"Hello professor, my name is Yu Hua, I just signed up for your elective course, a student of the Department of Mathematics." Yu Hua replied softly.

"Department of Mathematics?" The words spread throughout the classroom, and almost all the students in the Department of Mechanical Engineering present were full of confusion, and their heads were a little hard to turn.

what's going on?
People from the Department of Mathematics, apply for the elective of the Department of Mechanical Engineering?

Confused, confused.

However, this is not the end, everyone quickly came to their senses and realized another problem-why did this person enroll in elective courses now?
General education electives are chosen at the beginning of the semester, and now the situation is that the year of study is coming to an end and the summer vacation is approaching.

"Student Yu Hua, please take a seat."

When Zhuang Qianding heard this, his eyes narrowed and he felt very familiar. He suddenly remembered it, smiled, motioned Yu Hua to sit down, and then explained to the other students, "Student Yu Hua is the champion of this year's college entrance examination, so he should report to the school newspaper in advance. to study."

excuse me……

Almost instantly, everyone in the classroom returned to normal, sorted out the logical order and reasons, and silently turned their attention to Zhuang Qianding.

The existence of the champion level of the joint entrance examination is unprovoked.

It's not that they are cowardly. After all, none of the students who can get into Tsinghua University are idiots, but they have self-knowledge.

"Just now, what Yu Hua said was very good. Let's take a note. In addition, let me say a little more. In addition to hot forging, there is also cold forging. Cold forging refers to the processing of metals below the recrystallization temperature. There are model cold forging. And cold extrusion and other processes, at present, the cold forging process is a high-end process method, and I do not have a cold forging machine in China in the true sense.”

Zhuang Qianding continued his lecture, turned around and wrote down the English and Chinese terms of welding on the blackboard: "Next, we will talk about welding. Welding is a process of permanently joining metal materials, and the combination of metal atoms is caught by means of heat or pressure. With diffusion, the two pieces of metal material are firmly connected together..."

This section on the basis of mechanical manufacturing mainly talks about the three methods of thermal processing and their respective advantages and disadvantages, as well as specific methods and types, from sand casting, which is subdivided by casting, to free forging and model forging in the field of forging, and finally to welding. fusion welding.

The fusion welding of welding is very interesting. After Zhuang Qianding’s description, Yu Hua now understands that the so-called welding methods such as arc welding, gas welding, submerged arc welding, etc., all belong to the characteristics of metal hot melting and are classified as fusion welding.

Professor Zhuang Qianding spoke very carefully and in-depth. After explaining the basic concepts, he focused on the relevance of each process method.

Generally speaking, in order to obtain a part with good mechanical properties, such as a gun barrel, it is necessary to first cast the barrel blank, and then perform forging treatment to improve the internal structure of the metal of the gun barrel blank and obtain finer grains, thereby The mechanical properties are greatly improved.

In the classroom, Yu Hua and a group of students are like a long-dry riverbed, absorbing fresh and fresh rainwater continuously to replenish themselves.

Outside the window, the sun gradually went down, and a red halo gradually appeared on the edge of the horizon.

At 10:[-] and [-] minutes, the mechanical engineering elective course ends.

"Simply arrange a job, design and manufacture a part, the processing method is not limited, and the shape of the part requires a certain degree of practicability. We will talk about metal cutting in a few lessons. At that time, the parts you design and manufacture will use As a teaching aid, you can do it alone or as a team project.”

Zhuang Qianding is meticulous and serious, standing on the podium and looking around, assigning new homework: "Okay, get out of class is over."

After he finished speaking, he turned around and walked off the podium, heading out of the classroom.

"Thank you for your teaching." In a flash, all the students stood up, showing respect, and said goodbye to Zhuang Qianding in unison.

"Designing and manufacturing a part...Interesting." After class, Yu Hua quietly left the classroom and went to the dormitory for fasting. He was interested in the homework assigned by Professor Zhuang Qianding, and thought about what part to make.

"How about, practice your hands in advance and build a gun barrel to try?"

The beauty of machinery is timeless. As a hardcore military fan, Yu Hua, the first 'machine' part that comes to mind is of course the most interesting barrel for military fans.

It's no exaggeration to call firearms a killing machine.

The soul and central foundation of the barrel lies in the barrel.

"The Department of Mechanical Engineering has a lathe and a gantry milling machine. There is no problem in making the barrel with precision. As for the rifling, you can try manual rifling along the way. That's the decision." Yu Hua thought about it carefully and prepared to take this opportunity to try it. Craftsmanship, anyway, what parts are made is not made.

Happy to make a decision, Yu Hua left the school and returned to Ping Zhai soon. Roommate Han Yujin was not in the dormitory and did not know where he went.

After changing his clothes and getting ready, Yu Hua left the dormitory and still went to the east gate of the school instead of the previously agreed west gate.

After coming out of Tsinghua Garden, Yu Hua habitually made a few laps to test whether anyone was following him behind him.

There is no rush for homework and the like, the most important thing at the moment, complete the plan of technology replacement equipment!
(End of this chapter)