Chapter 769 Dealing with Pistons and Cylinders

Sandpaper and emery cloth are specially used to polish tools. Even in the technological era of Luo Chong's previous life, there is still nothing that can replace the role of sandpaper and emery cloth.

The problem now is that although the Han tribe has a pedal-powered grinding wheel, this tool is fine for sharpening knives, or for polishing the outer surface of objects, but it is difficult to polish the inner part.

The method of filling and stirring sand used by the researchers is similar to modern sandblasting and polishing technology, but it is not sandblasting after all, so he urgently needs a soft polishing tool such as emery cloth to polish the inner bore of the cylinder.

Even if you don't know how to make emery cloth, it is not difficult to analyze it based on its structure. First, you need a carrier, either paper or cloth, and then brush a layer of glue on its surface, and then stick a layer of fine sand on it and let it dry. It's actually that simple.

Then we need to analyze the material of the carrier and the fine sand. First of all, no matter what it is, it must not be elastic, otherwise the sand stuck on it will break due to stretching. The existing cloth in the Han tribe can hardly do this, so paper can only be used to carry it.

The next thing is the abrasive, that is, what kind of sand should be selected. First of all, since we want to use this thing to grind steel, the abrasive must be harder than steel. We need to find materials that meet this requirement. It must be easy to obtain, not too expensive, and the hardness must meet the standard. Luo Chong thought for a long time and it seemed that only clay met these standards. Clay

is everywhere, it is not worth much at all, and it is easy to obtain. The hardness of clay is also enough to grind steel, or in other words, the hardness of ceramics sintered with clay is enough to grind steel.

Isn't there a saying that if you don't have a diamond drill, don't take on porcelain work. Ceramics that can compete with diamonds are obviously not low in hardness.

After thinking of a solution, Luo Chong did it. Of course, he didn't do it himself, but temporarily stopped the research and development of steam engines and sent all the researchers to make sandpaper. He

bought a batch of relatively strong and heavy window paper from the paper mill, and then asked people to crush the mixed particles of clay and sandstone and take them to the kiln factory for sintering. After cooling, they smashed them and ground them with a grinding wheel. After passing through a sieve several times, the different sizes of gravel were separated into grades. Finally, glue was applied to the window paper to start sticking gravel. After it was completely dried, the "sandpaper" was obtained.

Although it was still very simple, as an emergency research and development tool, it took only two days to come up with a plan and complete the first batch of samples. It was really fast. Although there was a little sand loss when using it, the effect of use was also very significant.

To put it simply, it means that whatever is polished will shine, and whatever is rubbed will be

smooth. Luo Chong first had people cast a new cylindrical piston, and then had people use sandpaper to polish it smooth. Then he had the craftsmen of the institute dismantle a wooden hand-cranked lathe, put the steam engine cylinder on it, and then had people make a thick wooden stick with the same diameter as the piston and install it in the position of the coaxial turning tool. Then he brushed glue on it, and stuck a layer of sandpaper on it in reverse. Finally, he made a grinding rod, and then used hand-cranked power to insert this grinding rod into the cylinder and rotate it to polish the inner wall.

After changing the sandpaper twice, the cylinder with a mirror effect was polished out. If Luo Chong didn't know its material, he would probably think that the silver steel inner wall was made of stainless steel at first glance. It can be used as a mirror.

Finally, the polished cylinder and piston were assembled together. It is not an exaggeration to describe it as a perfect fit.

The cylinder was erected vertically, and the cylindrical steel ingot piston was placed horizontally. Without applying any lubricant, the piston weighing several kilograms slowly fell along the vertical cylinder as if it was floating in the air, as if something was holding up the heavy steel ingot below, and finally slowly fell to the bottom of the cylinder without making any sound.

Seeing this scene, more than 30 people in the entire institute jumped up excitedly. They finally succeeded, and a great invention was finally created in their hands.

A heavy steel ingot, with nothing underneath, could still float and slowly fall, which undoubtedly proved the airtightness of the combination of the two components. The air holding up the piston below could only be squeezed out little by little by the piston affected by gravity along the gap that was invisible to the naked eye, which would result in this situation.

If the airtightness is very poor, the air will be discharged very quickly, resulting in the piston falling directly into the bottom of the cylinder with a bang.

The fact that there was no sound during the whole process fully demonstrated that the friction between the piston and the cylinder was successfully controlled to a very low level. The contact between the two was very smooth, which led to this situation. If the surface was uneven, there would definitely be a noise like a cat scratching glass.

The researchers were very excited and praised the great invention of sandpaper. Some even boasted that the emergence of sandpaper would bring the manufacturing level of precision instruments of the Han tribe to a new level.

However, Luo Chong knew that the credit for this matter was only a small part of the sandpaper. With such simple equipment and only a few vernier calipers, these craftsmen were able to achieve this level of precision of the piston and cylinder by hand grinding. Each of them could be called a national treasure-level master craftsman.

Even if they were put in Luo Chong's previous life, they must have been the group of people in the Aerospace Science and Industry, who carved hair with their naked eyes, welded spacecrafts with their bare hands, and hammered sheet metal. They were the talents that all countries were vying for.

After the most precise cylinders and pistons were made, everyone couldn't help but want to assemble them with the steam engine to see what the complete form of the steam engine looked like.

To be honest, although there were problems with the previous piston design and manufacturing process, it is undeniable that these prototypes were able to operate normally during the trial run, except for the loud noise. The researchers saw the unparalleled power and advantages of the steam engine, so they would rather endure the harsh noise than stop this violent machine that embodies the aesthetics of industrial technology.

Now that they can see the complete product without noise and can run smoothly, how can they not be excited?

So these guys didn't even bother to eat dinner, and just lit the calcium carbide lamp to continue working.

Luo Chong is also in a more excited state now. A magic weapon that can change the future of mankind is about to be born. He is so excited that he can't eat. He simply waits in the research institute and asks his personal guards to instruct the school cafeteria to prepare a big meal as a reward for these heroes of the research institute.

(End of this chapter)