Shield machine.
This is still a novel concept for New Kyushu.
Even in Zhang Zhi's time, ordinary people had never heard of this kind of machine.
It's not as simple as the superficial principles. It's not what everyone thinks. A drill bit in front can push forward.
Shield actually means the two integrated into one.
A complete shield machine should have a boring machine at the front to advance forward, and a construction machine at the rear to lay the tunnel while digging. Prevent the excavated tunnel from collapsing, or the upper soil and rock layers falling due to vibration and filling the tunnel.
The principle of a tunnel boring machine is not difficult, but it is not as simple as a drill bit.
And the difficulty of building the machine seems to be as high as the sky. At least for New Kyushu, it is as difficult as climbing to the sky.
Ma Jianbin convened the Institute of Physics to set up a special shield machine team. After studying it for a month or two, he still failed to understand the principle of the shield machine.
The more I study it, the more I feel that the scientific principles here are simply bizarre. It seems like it’s just a matter of digging a hole, so why is it so difficult
Ma Jianbin said: "Master Li, I'm afraid the shield machine is really not that simple. Because when we dig tunnels, we are not facing the soil layer, but the rock layer. It is extremely difficult to dig tunnels in rocks. First of all, we have to face The right thing is the design of the drill bit.”
Li Zhen asked: "Is it difficult to design a drill bit?"
"The strength requirements of the drill bit can be met, but the design of the drill bit is difficult. There are electric drills in Xinjiuzhou. We got inspiration from the electric drills and designed drill bits with spiral patterns and expansion patterns. But later we found that this was It won't work. The TBM is not a big electric drill at all. You can easily drill holes in wood with an electric drill, and you can even drill holes in metal. But you can't drill holes in stone.
Stone is not like other substances. It will break if it is vibrated at that high frequency. If a large electric drill is placed in a rocky mountain to burrow into the rocky mountain, it may cause landslides and ground cracks. Security issues were greatly troubled. Therefore, the shield machine is by no means as simple as a large electric drill. It should have some way of achieving a stable balance that can make holes in the stone but not crack it. "
Li Zhen nodded, feeling a little embarrassed.
Zhang Zhi also found some information for him from the Internet for his reference, but Li Zhen did not fully understand it. That thing was also highly sophisticated science and technology in Zhang Zhi's time, and even many countries needed to import it. You simply can’t produce it yourself.
Li Zhen said: "There should be two aspects that cause cracks in the stone..."
Before Li Zhen finished speaking, Ma Jianbin interrupted: "High-frequency vibration and expansion development."
The so-called expansion development is a term invented by Ma Jianbin and others, which means that the drill bit is tapered, with a sharp front and a thick back. Like a wedge. The front is drilled in, and the back is forced in. This causes expansion and expansion, which will break the hard stone.
"Yes, these are the two reasons. Therefore, the design of this drill bit must meet the rigid requirements in two aspects."
"What?"
"One is that the rotation speed of the drill bit is not high, but the torque is high. The second is that the drill bit must be cylindrical and parallel. It is easy to meet the first requirement, but the second requirement is relatively difficult, that is, the drill bit must be in contact with the mountain. The contact surface is very large. And the front cannot be sharp, it must be flat.”
Ma Jianbin smiled bitterly: "Yes, Master Li, we have also discovered this problem. We built a cylindrical drill bit with a completely flat front to drill holes in the stone. This completely flat drill bit uses a Rotating it at high speed like grinding a stone actually made an extremely smooth hole in the stone. The structure was fully formed. But... "
"but what?"
"But is such a drill needed to dig a tunnel? It doesn't require any technology, just a solid cylinder with a diameter of several meters or even more than ten meters? This is impossible. A drill with a diameter of several centimeters that drills holes in stone is different from a drill with a diameter of nearly Drill bits with a diameter of more than ten meters to drill holes in the mountain are not of the same grade. First of all, a solid cylindrical rotor with a diameter of more than ten meters weighs at least more than ten tons. Our science and technology are completely incapable of making such a drill bit rotate at high speed.
If mechanical principles are used, large torque and low-speed rotation are generated. The maximum rotation speed of the drill bit can only reach dozens of revolutions per minute, or even more than ten revolutions. Such a low speed is as efficient as dripping water piercing stone. It's not as fast as blasting and crafting. Moreover, even if we have the ability to produce such a powerful engine, even a ten-meter-diameter drill bit has the same high speed as an electric drill. Then the vibration caused by the weight of the drill bit of more than ten tons will increase exponentially, and it will not be a problem to collapse a mountain. "
Ma Jianbin sighed deeply: "So, it's difficult."
Li Zhen smiled and said: "Actually, it doesn't hurt to think differently. What if the front end of a large flat drill bit with a diameter of several meters is equipped with hundreds of small drill bits that rotate at high speed?"
"What's the meaning?"
"The principle of a whetstone. Use a flat drill bit to remove a diamond head. This principle is the same as a whetstone. It does not drill through the stone, but grinds the stone through. But you just think of adding sand patterns on the flat drill bit. and roughness, increasing friction. Why can't we think about how to increase this friction by hundreds of times? Imagine if a large drill bit rotates slowly, and hundreds of cracks appear on the side in front of the drill bit that is in contact with the mountain. If a small drill bit rotates in the opposite direction, or rotates along the trend, will the friction force increase by a hundred or a thousand times?"
Ma Jianbin's eyes suddenly lit up and he stood up suddenly. He hit his head on the wall so hard that he didn't care about the pain. He exclaimed: "Is that so? Yes, why didn't I think of that? Master Li, you It is simply the light God has given to this world.”
"That's right. When a main drill bit rotates slowly, hundreds of high-speed rotating small drill bits are attached to the main drill bit. Isn't this equivalent to hundreds of people using hundreds of electric drills equipped with those grindstone electric drill bits? , to dig tunnels by hand? A mountain cannot withstand a large drill bit that rotates at an ultra-high speed and emits an ultra-high vibration frequency. But it can definitely withstand hundreds of small electric drills polishing it. The vibrations emitted by the small electric drills are not enough for a mountain. It’s said to be incalculably weak.”
"Master Li, you are a genius!"
Li Zhen smiled: "I just put forward an idea. But the specific design, there are many difficulties that you need to overcome. Even insurmountable. I don't know if you have the ability to do this kind of craftsmanship, in a On a drill that is already rotating, it is a headache to think about designing hundreds of small drill bits that rotate at high speed inside the drill bit at the same time.”
"This idea is already amazing. You said that going from zero to one is the hardest, but going from one to a thousand is the easiest. Everything is difficult at the beginning. Now we have an idea, at least we know where to start. Which direction do you go in. This is a step to the sky!"
Ma Jianbin was excited and ecstatic.
Others got excited too.
This kind of excitement and ecstasy of breaking through the natural barriers of thought in the midst of scientific difficulties is something ordinary people cannot experience.
Use a slang to express this feeling, that is:
Compared to love, it makes people feel more happy and excited.
(End of chapter)