Four days later, in the backyard of the North Slope Mine.
Two deep holes were dug on the ground in the yard. Each hole was round, narrow at the top and wide at the bottom. The inner diameter of the front was about 20 centimeters, and the inner diameter of the back was expanded to 26 centimeters.These holes were the molds that Roland intended to use to cast the cannon embryos. The inner walls of the holes had been baked by Anna, and the soil on the surface had been sintered into a whole body, like a shell. The lower the chamber was to obtain a better quality tube wall, and the higher it was, the more scum and bubbles there would be. The dimensions of all the holes were calculated from the cannonball. He roughly remembered that the so-called six-pound cannons and eight-pound cannons were named after the weight of the cannonball. So, he first cast a few twelve-pound iron balls, and then calculated the inner diameter of the mold according to the diameter of the iron balls and the thickness of the cannon tube.
In the absence of measuring tools, Roland simply set his own standard. He cut off a piece of iron bar as wide as the nail of his ring finger and set it as the basic unit, one centimeter. Then, he made other iron bars of different sizes and engraved segmented lines on them.
The diameter of the twelve-pound iron balls was about twelve centimeters, and he set the thinnest part of the tube wall at four centimeters. In order to prevent the chamber from exploding, the thickness of the rear chamber was expanded to seven centimeters, and the inner diameter of the mold was calculated from that. As for the length, although he knew that cannons could be doubled in diameter, he only had an impression of the main cannons of battleships and main station tanks. As for the antique front-loading cannon, he really didn't know.
Considering that the shorter the barrel, the lighter the weight, and the more materials would be saved, Roland waved his hand and took a value of 1.5 meters. If the test results were not satisfactory, he could adjust it later.
When the cannon was first invented, the wooden core was surrounded by iron bars and iron powder, and then reinforced with iron hoops. Finally, the core in the chamber was burned, just like a wooden storage barrel. Of course, Roland knew that this kind of cannon could easily leak air and explode, so he directly used the whole casting process and the boring machine to drill the holes. For a steam boring machine, there was no essential difference in the difficulty of drilling a six-pound cannon or a twelve-pound cannon.
Based on the idea that caliber was justice, he naturally chose a twelve-pound cannon with a larger muzzle and a thicker barrel. If he went any higher, it would not be easy to use as a field cannon. As for the weight of the shell, it didn't matter whether it was a lead ball or an iron ball, as long as it could shoot out. After all, he was learning from history and not playing with replicas.
"Let's begin." Roland took a deep breath and said to Anna. The latter nodded, grabbed a piece of steel ingot, and hung it above the hole. The green flame ignited, and the steel ingot quickly turned red, then melted, forming a small waterfall of molten steel that flowed into the cave. The surface of the molten steel was reddish-orange, and the inner core turned incandescent, so bright that it was difficult to look at it directly. In order to protect the witch's eyesight, Roland also deliberately set up a cushion at the entrance of the cave. She only needed to determine the position in advance and lean her arm on the cushion, so that she wouldn't have to stare at the molten steel to see if it flowed into the cave.
These steel ingots were slowly accumulated during normal times. Anna alone could not start the era of large-scale steelmaking, but a small batch production was not a problem for her. After the most difficult to achieve temperature was solved, the method of frying steel could produce better quality steel.
This was also the reason why Roland dared to set the size of the cannon barrel.Compared to pig iron and bronze cannon barrels, steel cannon barrels were obviously more durable. Even if the size was wrong, the cannon would not easily explode.
The molten steel gradually rose, and the remaining steel ingots were also rapidly decreasing. Roland could not help but feel a little heartache. In the end, when would he be able to build a bunch of chimneys and blast furnaces in his territory, and smelt an endless supply of steel? For a long time, the output of steel was one of the standards to measure the strength of the great powers, and now he personally felt it.
After filling the two molds, Anna's cheeks became bright red. Roland took out a handkerchief and gently wiped the sweat on the tip of her nose. At first, Anna showed some resistance, but now she obediently stayed motionless, closing her eyes and letting Roland do whatever he wanted.
Under the reflection of the molten steel, her bangs were dyed red, and her soft neck made people want to bite it. When he looked down from above, the other side's slender clavicle that was exposed through the collar would enter his field of view.When he was close, he could also smell the bursts of delicate fragrance coming from her body.
"Ahem, alright …" Roland put away the handkerchief and at the same time, withdrew his restless emotions. "Let's call it a day. Well done, I will ask the kitchen to reward you with an extra black pepper steak for dinner. "
Not now, he thought. If he did that, he would inevitably be suspected of taking advantage of her. Wait, wait until she really gets her freedom …
Anna opened her eyes. Although the sweat had been wiped away, her face seemed to be redder than before. She nodded at Roland and replied softly, "Yes.
*****
In the next few days, Roland went back and forth between the castle and the North Slope Mine.
In addition to the cannon barrel, he also needed to make a sufficient number of boring tools.
This drilling tool was made in a similar way to the cannon barrel, and its diameter was exactly the same as the shell. After taking it out of the mold, Anna heated it again and used the iron hammer to shape it. It was very different from the ordinary spiral knife in shape. At first glance, it looked like a blunt iron rod. The only difference was that there was a gap at the top for discharging metal debris. Finally, it was quenching to improve the hardness of the boring tool.
Unlike the high-precision drills of modern boring machines, Roland only needed an iron rod that could drill holes. Taking into account the high wear rate, he and Anna made five simple boring tools in a week.Before this, the steam boring machine had fully proved its ability — the production of pig iron barrels rapidly increased from two per month to ten per day.
When everything was ready, the cannon embryos were dug out from the pit by the miners. After cleaning the surface scum, they were carried to the carriage and transported to the blacksmith shop.
These two cannon embryos almost consumed all the steel that Roland had accumulated. It was not an exaggeration to say that they were priceless treasures.During the transportation, the prince ordered Carter and two Knight to be responsible for the whole process, which made the Chief Knight feel that it was a bit unnecessary. Who would steal such a heavy thing?
The blacksmiths flattened and polished the surface of the cannon embryos according to the prince's request. After the grinding stones were finished, they were immediately sent to the castle's backyard.At this time, the two round solid steel rods were dark gray, exuding a thick metallic luster.
Roland couldn't wait to replace the boring tool, and together with Carter, they fixed the cannon embryos in place, so that the top of the boring tool was just in the center of the steel rods.
In the face of this historic moment, Roland pulled the valve of the steam engine. The boring tool began to run slowly, and it didn't take long for it to rise to a stable speed.
"Enter!" The prince shouted.