Appearing in Ye Qing's eyes, it was a silver-white standard hexagon nut. Picking up the nut gently, his first finding was that the nut was heavy. The standard nut with the same size was about seven grams. He often dealt with these things and was very accurate in grasping its weight. But starting with this nut, it weighed about 15 grams. The increase in weight indicated that this nut was made of a higher density high-hard alloy.
When Ye Qing pinched this alloy nut in his hand and aimed at the crystal lamp above his head to observe the inner thread, already hardened by monsters, he could not help but be surprised. There was no thread in this nut. Inside the crystal nut, under the light, there was a faint reflection of metal.
With reflection, it means there was a metal mirror. The inner wall of the nut was as smooth as a mirror, like a seamless precision tube. A nut without thread. Can this be called a nut, perhaps a metal washer is more appropriate?
What is this nut?
Nuts are the most common metal parts in the modern industry and life. Nuts and screws, the two are tightly combined together to fix the principle of objects, even the first-grade children know. The inside of the nut is called an internal test thread, and the top of the screw or bolt is called outside thread. Only two nuts and screws of the same specification can be connected together. The diameter is the same, and the pitch between the threads is the same. If there is no thread, how to tighten the connection with the screw?
Ye Qing believed that Japan Science and Technology could not make such a mistake that would violate the common sense of physics. Since they proudly gave this nut as a gift, there should be something in this nut.
"Is there a magnifying glass?"
Professor Cai Chenning nodded a little seriously and handed a Carland 300x portable microscope.
A portable microscope with a light source is usually used to observe the surface of jewelry and the roughness of metal materials. It is only the size of a mobile phone and is very suitable for carrying.
After adjusting the resolution and the light source, Ye Qing aligned the lens of the portable microscope with the inner hole of the nut, and his face also became serious. At 300 times magnification, the inner hole of the nut, which was originally as smooth as a mirror. There was even a thread of internal tests, these threads are surrounded by a circle, the spacing between the pattern teeth is too small to be incredible.
Under the observation of the portable microscope of three hundred, it was possible to barely see a trace of depression between the lines and teeth. How fine were these striated teeth?
The thickness of a hair strand is 0.06 mm on average, but a hair strand can be easily seen with the naked eye. If the hairs are lined up neatly and there are gaps of the same thickness in the middle, can it be seen by the human eye?
A closer look can found clues. Ye Qing tore off one of his hair, placed it under the portable microscope, observed the focal length and approximate width in his heart, and then aligned it to the inner wall of the alloy nut to compare the hair silk with the thread, the pitch of the thread was too small to judge. This shows that the gap between the striated teeth was much smaller than one-tenth of the hair silk. As for how small it was, it has exceeded the human eye's visual analysis ability.
"We have measured with a laser interferometer, and the thread pitch is 0.2 wires, and the thread depth is 3 wires." Professor Cai Chenning gave the answer.
"No wonder."
Ye Qing understood the human eye could distinguish much thinner things than the silk of hair. Under sufficient light source and contrast of different colors, even silk could be seen. But such a small thing has reached the limit of visual recognition.
For one single silk, it is okay. If two silks are close together with a gap of the same thickness between them, the human eye will default to one. The same principle applies to these threads in front of him. It is too thin, only one-thirtieth of the hair silk.
A circle of ultra-fine threads surrounded, as a matter of course, the visual recognition limit of the human eye has been exceeded resulting in the illusion that the surface of this nut did not have any thread.
1 millimeter, in industrial processing, is often referred to as 1 wire which is equal to 0.01 mm.
The accuracy of the current international five-axis machining center is usually 0.2 wires. The domestic accuracy is 0.8 silk.
This is only theoretical data. In actual operation, if you want to reach the accuracy of 0.2 wires you must adjust the machine tool to the best level, use the laser to adjust the tool and the tool wear is automatically compensated.
The nut in Ye Qing's hands already represents the processing limit of an ordinary five-axis machining center.
"Open your eyes, who can imagine that Japan University of Science and Technology can make a nut like this?" Professor Cai Chenning said with some sadness, "when we got this nut, we still had students who didn't know how to do it. We laughed at the fact that Japan University of technology couldn't even distinguish the nut from the washer. They sent a washer without thread saying it was just a nut."
"Someone asked me that the commercial five-axis center can control the precision to 0.2 wires. In theory, the precision can be controlled higher in the laboratory. Why can't a screw be made?"
Ye Qing responded: "Because this screw must be made in one go, hundreds of threads that are invisible to the naked eye are machined out. The point was I still needed a tool that can be tapped, not to mention the market is not available for purchase, I will make my own stupid words. Making a tool that can tap a screw is far more difficult than making a screw like this. Also, the thread of this screw or nut is too thin. If the factory machine tool cuts lightly from the alloy steel, it will cut the thickness of a wire. The cut thread will never be a vertical metal piece, but a roll like a lollipop. This is due to the stress of the metal, thermal deformation, cutting angle of the tool, metal toughness, etc."
Professor Cai Chenning thought to himself: "how does Japan University of Science and Technology do this? In a nut with a height of five millimeters, hundreds of ultra-precision threads with only 0.2 wire pitch are processed?"
The threads processed by the most critical people are not deformed.
"The answer is on the metal material used for this nut." Ye Qing gazed at this nut, which represents the most cutting-edge processing technology, and said softly: "Japan has made a lot of achievements in the special alloy, and ordinary metals are not resistant to high temperatures. Alloy materials should avoid metal stress and thermal deformation."
"I also guess this is the case." Professor Cai Chenning asked cautiously: "But no matter what kind of alloy is as thin as 0.2 wire, it will deform with a light touch."
"The disciple I brought with me ground a very thin probe by hand to test the hardness of the thread. I thought it would deform with a light touch, but the thread of this nut did not."
"It may be that the nano-level coating has increased hardness. Using plasma vapor deposition, it can be coated with a diamond grinding layer with a thickness of only a few nanometers." Ye Qing brought out by a group of top monsters, said with some uncertainty.
Professor Cai Chenning who also knew a little about this process fell into a long bitter smile. He could not do any of the craftsmanship mentioned by Ye Qing. Not only could he not do it at Shanghai University, but none of the Seiko companies that Professor Cai Chenning knew could do this. Therefore, he went to see Ye Qing brazenly and wanted to invite him to dinner.
Even the headmaster, who was always on his sleeve and never participated in the dinner, came to see Ye Qing.
"Ye Ye… Master, then… Can you make this kind of screw?" Confucian principal Wang Hongnian, blushing at this moment. He was a typical old-school educator. When he saw students, he always kept his stereotyped image in a stretched face.
Ye Qing was also his student. At this time, President Wang Hongnian asked Ye Qing for help with an old face, and he felt his image was completely destroyed. Especially in the case of more than a dozen students sitting on the table. But at this time, no one had to worry about the image of the principal.
The face of Shanghai University would disappear. In the campus forum, the mechanical engineering department has become a national sinner. This screw could not be done. They could not even find the target. Are they free to care about the principal? Everyone was staring at Ye Qing which holding his chin: "It's easy to make the screw, and the key is that I am now graduated. This academic exchange meeting is between students at school."
Making the screw is easy! Making the screw is simple…
President Wang Hongnian, who had summoned the wolf from the Japan University of Technology, didn't hear the next sentence at all. His head was hot, and he slammed up from his chair. His expression was even more exciting than when he became the director of the Education Bureau: "Quickly take the screw out and teach the arrogant guy hard."
"Mr. Ye… Didn't the school send out the graduate application form when you graduated?" Professor Cai Chenning's eyebrows were almost flying, and he rubbed his hands excitedly.
"It seems there is…" Ye Qing, of course, remembered this form. He knew Professor Cai Chenning had not received this piece of material he didn’t fill it up and it was rubbed when it changed hands.
Professor Cai Chenning snapped a blank form on the rotary table.
"Welcome Mr. Ye to our school to study for graduate students. You are not used to taking courses. As for this damn program, it's not a problem to take a doctorate directly with your professional knowledge."
