Chapter 227: Chapter 223: Designing the Tunnel Boring Machine
To build the shelter, there is a problem that Perfikot must solve, which is the shield machine.
Although the shield machine may not be impossible for the engineers and alchemists of this era to build if the requirements are known, clearly, in an era where even the swinging arm drill hasn’t been invented yet, making a shield machine that meets Perfikot’s requirements is quite difficult for these people.
In Perfikot’s original world, the most primitive shield machine was indeed invented during the same era, but rather than being a shield machine, it was more of a construction method.
The engineers at the time found inspiration through the method of shipworm drilling wood, dividing the tunnel boring working surface into several small work windows, with each window having a worker responsible for excavation. After digging the underground soil and rocks, the worker would transport the excavated soil and rocks away, and the frame of the entire working surface would move forward, with the excavated parts being supported by bricks and cement walls.
This working method was the earliest shield tunnel boring model, providing the foundation for modern shield machines, but it is hard to call it a shield machine.
Moreover, although this method’s work efficiency is higher than purely relying on manpower, the excavation speed is still too slow.
One must know that in the original world, the world’s first tunnel built using shield technology took several years to complete, and they only dug a tunnel beneath the Thames River in London.
Thus, Perfikot obviously cannot choose this method; she wants to create a boring device that at least conforms to the concept of a shield machine.
This kind of boring device also appeared in the history of the original world, or rather, it was the true ancestor of the modern shield machine.
The front end of this machine has a huge rotating arm equipped with sharp and robust blade heads that can cut down rocks and soil and then transport them away via conveyor belts, with the entire machine being continually pushed forward using hydraulic devices.
Though this equipment is still extremely crude compared to the modern shield machines of later generations, it at least meets the basic requirements of a shield machine in Perfikot’s mind.
So, after Perfikot spread open the drawings, she began to draft designs according to the style of this old-fashioned machine.
The structure of this old-fashioned machine is relatively simple compared to modern shield machines of later generations; its main working components are the rotating arm and blade heads at the front, which appear overly simple and crude to Perfikot.
She referenced the design of modern shield machine cutterheads, designing the head of her shield machine as a continuously rotating cutterhead, identical in structure to modern shield machines.
The advantage of this cutterhead design is that it can grind different kinds of rock on the work surface more evenly, while also better resisting potential soil collapse issues at the work surface.
Additionally, as the cutterhead is a circular whole, it can better advance forward aided by the rear propulsion device.
However, a qualified shield machine cutterhead not only has high design requirements but also poses a tremendous test to materials science.
It should be noted that in later generations, the shield machine is dubbed the crown jewel of the industrial world, and the most critical part is arguably the cutterhead and its various blade heads.
To handle various underground rocks with different textures, the blade heads on the cutterhead are not of a single type, but utilize multiple different types of blade heads in cooperation to achieve boring.
Different types of blade heads employ slightly different cutting principles.
Among them, hard rock blade heads primarily rely on impact force to cut hard rocks, while soft soil blade heads primarily depend on pressure and shear force to cut loose soft soil layers.
The material for soft soil blade heads is relatively straightforward, with sufficient wear resistance and robustness being adequate, but the material for hard rock blade heads has very high requirements, as nobody knows what kind of rock texture might be encountered underground; encountering a rock with excessively high hardness could shatter the blade head, which would be difficult to repair.
In later generations, the materials for such blade heads have evolved to composite structures. While manufacturing the blade heads with hard alloys, diamond micropowder is added, or a layer of diamond is sprayed onto the surface of the drill bit to enhance the durability and hardness of the blade heads.
This is also why some industrial powerhouses in later generations, having exhausted the crown jewel of the industrial world, became a significant producer of synthetic diamonds.
In the industry, the application fields for synthetic diamonds are incredibly extensive.
If it’s only about manufacturing diamond drill bits, this isn’t difficult for an alchemist like Perfikot; it’s merely transforming graphite into diamonds using alchemy, which, once the principle is understood, can be achieved even by an apprentice.
The truly complex aspect is creating high-strength alloys, which is where the real challenge in materials science lies and cannot be achieved through alchemical cheating.
Moreover, Perfikot has little memory from later generations that might help in this regard, as despite her exposure to these matters, she does not specialize in them; besides recalling manganese in alloy formulas, she can’t recall much.
There’s also a crucial factor: the development of metal material processing technology.
The same homogeneous steel from the 21st century is clearly of much higher hardness than the homogeneous steel from the 20th century for tank armor, which undoubtedly reflects the progress in metal processing technology (although differences in metal formulas also play a role).
As of now, the material Perfikot can utilize is nickel-chromium alloy that she produced herself.
While this material cannot compare with the metal materials used in shield machines in later generations, it is sufficiently effective for now, so Perfikot does not dwell excessively on material aspects, except for designing the blade heads to incorporate diamonds for increased hardness, using nickel-chromium alloy elsewhere.
Solving the problems of the cutterhead and blade heads simplifies the rest of the shield machine: a steam engine to drive the cutterhead rotation, a conveyor belt to transport crushed stone and soil, a propulsion device to push the shield machine forward, and a pipe laying system to construct tunnel wall pipes.
In modern shield machines of later generations, the pipe laying system generally adopts an assembly method, mechanically piecing together prefabricated pipe segments and installing them onto the tunnel walls.
However, this doesn’t affect the overall situation for Perfikot, as she isn’t digging deep tunnels, merely excavating an underground city; even using the relatively old grouting operations is feasible.
The truly critical part remains the shield machine body at the front, requiring the most time and effort from her.