When will I have a long tassel?

"Xingwang, haven't you figured it out yet?"

At Longhu Machinery Factory, director Zhao Xinggen led a few people into the workshop, came to his younger brother Zhao Xingwang who was squatting in front of the baling machine in a daze, and asked softly.

A week has passed since the counterfeit baler failed, and Zhao Xingwang is still wondering what the problem is with this baler. Relying on his past friendship with Yu Changfa, he went to the packaging workshop of Yuntang Recycling Materials Company more than a dozen times and measured the dimensions of the Changying brand packaging machine several times. Of course, Yu Changfa would not allow him to disassemble the baler again, so he could only guess at some of the components hidden inside.

Zhao Xingwang focused on the machining accuracy and shape of the support shaft. He asked workers to make more than a dozen different support shafts, some smooth, some rough, some straight, some spindle-shaped, and some dumbbell-shaped. Each shaft is assembled to the baler and tested to determine whether it meets the original design.

In addition to the support shaft, Zhao Xingwang also had other related components remanufactured. In just one week, the cost of manufacturing various components alone was almost tens of thousands.

Zhao Xingwang's persistence in finding out the problem has two other purposes besides being diligent and studious.

The first is of course to stop the loss. If he can find out the reason why the baler broke the shaft, not only can the baler be repaired and sold, but Longji can also develop new business and then make up for it with the profits of the new business. It had previously compensated Yun Tang Company for the losses caused.

The second point is that he must understand the reason. This is not only related to whether he can imitate a qualified baler, but also involves imitating other equipment in the future.

The counterfeiting of a baler failed, and the loss was more than 300,000 yuan, which was still within the range that the Zhao brothers could bear. If other subsequent devices have the same problem and fail to imitate again and again, the brothers will be hungry.

"Brother, I still can't find the reason." Zhao Xingwang raised his head and said to his brother. His current appearance makes people feel really distressed. His hair is messy, his face is covered with stubble, his face is thin, and his eyes are red.

There is no way, this kind of experiment is really time-consuming and labor-intensive. Every time, the relevant parts have to be disassembled and put back together, and then turned on to test the pressure, which takes an hour or two. Noise and other tossing is secondary, the most important thing is tiredness...

"Xingwang, look who's here." Zhao Xinggen pointed to his side with his hand and said to Zhao Xingwang with a smile.

Zhao Xingwang looked up, quickly stood up, and greeted with a joyful face: "Brother Wen, you are back!"

The man called Brother Wen is about the same age as Zhao Xinggen. He wears a suit and wears glasses on the bridge of his nose. He looks like a gentleman. This person is Zhao Xinggen’s junior high school classmate, named Wen Weiming.

At that time, Zhao Xinggen dropped out of school after finishing junior high school, and Wen Weiming went to high school. Then as the first college student after the resumption of the college entrance examination, he entered the Department of Mechanical Engineering of Tsinghua University. He then continued his master's and doctoral studies without interruption. After graduation, he stayed at the school to teach. He is currently Associate professor in the Department of Mechanical Engineering, Tsinghua University.

The chief engineer of Longhu Machinery Factory is Zhao Xingwang, but Zhao Xingwang's two brushes can still deal with ordinary technical problems. For slightly more troublesome problems, he can only turn to foreign aid, and Wen Weiming is a die-hard Longji fan. foreign aid.

This time when Longji failed to imitate the baling machine, Zhao Xinggen considered asking Wen Weiming to come back for guidance. But the time Yu Chang gave him was only two days, and he didn't have time to find Wen Weiming.

After paying the compensation to Yu Changfa, Zhao Xinggen called Wen Weiming and told him about the incident, but many situations were unclear on the phone. Wen Weiming told Zhao Xinggen that he would take a group of students to Jinnan for a winter vacation internship in a few days, and would visit Longji at that time.

At this time, Wen Weiming came with his own students. There were three men and one woman following Wen Weiming, all of whom were Grade 91 students in the Department of Mechanical Engineering.

"Xingwang, how did you end up like this?"

Wen Weiming did not dislike Zhao Xingwang's greasy hands, shook hands with him, then pointed at his face and asked with concern. Zhao Xingwang is two years younger than Zhao Xinggen. When he was a child, he followed Zhao Xinggen, Wen Weiming and others as followers. Wen Weiming became very familiar with him.

Zhao Xingwang said frustratedly: "Brother Wen, I'm in trouble again. As for this baler, I think there is nothing wrong with the design, but the locking mechanism on the front end just can't lock and the shaft breaks repeatedly. All I've checked all the reasons and can't find anything."

"Broken shaft? There should be a design problem. Has the pressure exceeded the bearing limit of the shaft?" Wen Weiming asked.

Zhao Xingwang said: "No, we copied the baling machine from Linyi Machinery, and nothing else has been changed except the outer casing. But their machine has been used by Yuntang Company for almost a month, and there is nothing wrong with it." None, our machine can only punch a dozen packages at most, and the shaft will break."

"Is there such a thing?" Wen Weiming frowned. Of course he knew that Long Ji started his business by copycats, which was a very common thing in Jinnan. Wen Weiming quite recognized the manufacturing level of Longji, knowing that it was impossible not to be able to imitate even one such machine.

"What problem are you analyzing?" Wen Weiming asked.

Zhao Xingwang said: "Our initial analysis was whether the test was wrong during the imitation test, and which part was different from the original one. Later, we checked many times and basically ruled out this possibility. The remaining possibility is There is a problem with processing accuracy. Brother Wen, look, there is a newspaper here with an article. It is said that the reporter interviewed the engineers of Linyi Machinery. Their engineers said that if the processing accuracy is insufficient, something like this may occur. Broken shaft failure..."

Wen Weiming took the newspaper handed over by Zhao Xingwang, read it a few times, then handed it to his students and said, "You all should read it and tell us your opinions."

"Insufficient machining accuracy will cause the bearing to break? There is no such thing, right?"

"How can a bearing break? The ball is at most deformed, right? If it's a shaft...but what does this have to do with machining accuracy?"

"There's no need to use a grinder to process such a shaft..."

The three boys read the newspaper and found it incredible. However, in front of the teacher, they did not dare to talk too much. What if there was something that they had not considered carefully?

"Wen Jun, take a look too." Wen Weiming shouted to the only girl.

Just now, several boys were listening to Wen Weiming chatting with the Zhao brothers, but the girl didn't know when she picked up the drawings of the baler, put them on a trolley where the workpieces were placed, looked at them, and took them. A drawing pencil is writing on the drawing paper, looking quite focused.

When she heard the teacher calling her, she turned around, reached out to take the newspaper from a boy, glanced at the contents of the newspaper, and then inadvertently glanced at a signature under the title, and burst out laughing. .

Because she was out for an internship, the girl wore a semi-old work clothes and her hair was curled into a bun on the top of her head. She was no different from the ordinary female workers in the workshop and was not particularly eye-catching.

But when she smiled, the aura flowing in her eyes and the smile on her face immediately made everyone look a little crazy. A few boys even grinned to the back of their heads, smiling like a canopy guy at a peach banquet.

"Her name is Xiao Wenjun, the student with the best grades in the first class of our Department of Mechanical Engineering." Wen Weiming introduced the Zhao brothers. After that, he smiled and asked Xiao Wenjun: "Wenjun, what, is this article ridiculous? "

"No, no." Xiao Wenjun raised a hand, covered his mouth slightly with the back of his hand, tried hard to hold back his laughter, and said, "Teacher Wen, I'm sorry, I just saw this reporter's name, so I thought it was funny."

"The reporter's name?" Zhao Xingwang was stunned. "I remember that the signature of this article was our newspaper's correspondent Bao Nana. Does this name have any special meaning?"

Xiao Wenjun said: "I know this person. We were both in the same class from elementary school to the first year of high school. She is my best friend. However, she...well, don't believe what she writes anyway. That’s it.”

Speaking of this, she couldn't help covering her mouth and snickering. She didn't know why this girl's laughing point was so low.

"Don't believe it..." Zhao Xingwang grinned, how weird this Bao Nana must be for people to make such comments about her. If a reporter cannot believe what he writes, is he still a reporter?

"Wenjun, so you think the reason why the baler's shaft broke was not a processing problem?" Wen Weiming asked.

"Of course not, it has nothing to do with processing accuracy." Xiao Wenjun said firmly. When talking about technical issues, her eyes became very clear, with a look of wisdom.

"So, what do you think is the reason?" Wen Weiming asked again.

"There is a problem with steel." Xiao Wenjun said. She held up the drawing she was looking at just now, pointed to several schematic diagrams and a series of formulas on it and said, "I have done calculations just now. According to the design of this equipment, at the extreme Under such conditions, the tensile stress on the front-end mechanism support shaft will exceed 1,000 MPa, and may even reach a maximum of 1,200 MPa.

"Director Zhao and the others are currently using No. 45 carbon steel. If I remember correctly, the standard tensile strength of this steel is 600 MPa, with positive and negative fluctuations of around 100 MPa, which means that the maximum Reaching 700 MPa. In this way, it does not matter when pressing some low-strength scrap steel, but if high-strength steel is pressed, the tensile stress of the support shaft far exceeds the maximum tensile strength of the material, and breakage will definitely occur. , which has nothing to do with machining accuracy.”

"1000 MPa, my mother is such a bastard..."

Zhao Xingwang couldn't help but spit out a mouthful of old blood.

Damn it, can you not bring someone so deceptive? This Changying brand baler is full of pitfalls from design to marketing. It is just a scam.

Looking at the comment area, everyone is a mechanical expert. Cheng Zi is a liberal arts student. I checked dozens of papers on failure analysis, but in the end I couldn't distinguish between pressure and pressure. Let's just make do with it. The general idea should be correct. In addition, it seems that the focus of this chapter is not on pressure...