Chapter 69: Cannon Making

Four days later, the backyard of the North Slope Mine firing room.

Two deep holes have been dug in the ground in the yard, each hole is circular, narrow at the top and wide at the bottom. The inner diameter of the front section is about 20 centimeters, and the inner diameter of the rear end is enlarged to 26 centimeters. These holes are the molds that Roland intends to use to cast the cannon blanks. The inner walls of the holes have been baked by Anna, and the surface soil is sintered into a whole, as if a shell is attached. The medicine chamber faces downwards to obtain better pipe wall quality during casting, and the more upwards it contains more scum and air bubbles. The dimensions of all the caves were calculated from the shells. He roughly remembered that the so-called six-pound guns and eight-pound guns in history were named after the weight of the shells, so he first poured a few twelve-pound iron balls, and then The diameter of the ball plus the wall thickness of the gun tube is used to calculate the inner diameter of the mold.

In the absence of measuring tools, Roland simply made his own standard. He cut out a piece of iron bar about the width of his ring fingernail as the basic unit, one centimeter, and then made iron bars of other sizes, and engraved the points on it. segment line.

The diameter of a 12-pound iron ball is about 12 centimeters when measured with a rough iron ruler. He set the thickness of the tube wall at the thinnest point as 4 centimeters. In order to prevent the chamber from exploding, the wall thickness of the back-end chamber was enlarged to 7 centimeters. , so as to obtain the inner diameter of the mold. As for the length, although he knew that artillery had multiple diameters, he only had the impression of the multiple diameters of the main guns of battleships and main station tanks. As for the antique front-mounted guns, he really didn't know.

Considering that the shorter the barrel, the lighter the weight and the less material, Roland waved his hand and took the value of 1.5 meters. If the test shooting effect is not satisfactory, it will be fine to adjust it later.

When the cannon was first invented, the wooden core was ringed with iron bars and closed with iron powder, then reinforced with iron hoops, and finally the core material in the barrel was burned away, just like a storage barrel. Of course, Roland knew that this kind of artillery had the risk of air leakage and explosion, so he directly adopted the process of integral casting and boring machine drilling. For steam boring machines, there is no essential difference in the difficulty of drilling six-pound guns or twelve-pound guns.

Based on the idea that caliber is justice, he naturally chose the twelve-pound gun with a larger muzzle and a thicker barrel. Further up, it is not easy to use as a field gun. It doesn't matter whether the weight of the shell is calculated by shot put or iron ball, as long as it can be shot out. After all, he is drawing from history, not playing with replica models.

"Let's get started," Roland took a deep breath and said to Anna. The latter nodded, grabbed a steel ingot, and hung it over the hole. The green flame ignited, and the steel ingot quickly turned red, and then melted, forming a fine waterfall of molten steel, which flowed into the hole. The surface of molten steel is reddish-orange, and the inner core turns incandescent, making it difficult to see directly. In order to protect the witch's eyesight, Roland also specially set up a support beside the hole. She only needs to determine the position in advance and rest her arm on the support pad, so she doesn't have to stare at the molten steel to see if it flows into the hole.

These steel ingots are accumulated slowly at ordinary times. Anna alone cannot start the era of large-scale steelmaking, but small batch production is no problem for her-after the most difficult temperature level is solved, use fried steel Higher quality steel can be obtained by this method.

This is why Roland dared to customize the barrel size. Compared with pig iron barrels and bronze barrels, cast steel barrels obviously have higher strength. Even if the size is wrong, the artillery will not easily explode.

The molten steel was gradually rising, and the remaining steel ingots were also rapidly decreasing. Roland couldn't help but feel a little heartbroken. When will he be able to build a bunch of chimneys and blast furnaces on the territory to smelt inexhaustible steel? For a long time, steel output was one of the criteria to measure the strength of great powers, and now he feels it personally.

After filling the two molds, Anna's cheeks became bright red. Roland took out a handkerchief and gently wiped the sweat from the tip of her nose. At first Anna would show some resistance, but now she obediently remained motionless, closing her eyes and letting Roland do whatever she wanted.

The drooping bangs are dyed with red edges under the reflection of molten steel, and the soft neck makes people want to take a bite. When I am condescending, the half of the slender collarbone exposed through the collar of the other party will enter my field of vision. Even if they were so close, they could still smell the fragrance coming from her body.

"Ahem, okay..." Roland put away the handkerchief, and at the same time withdrew all the emotions that were ready to move, "Let's stop here today. Good job, I will order the kitchen to reward you with an extra black pepper steak for dinner."

It's not now, he thought, it would inevitably be suspected of taking advantage of others' danger. Wait, wait until she is truly free...

Anna opened her eyes, and although the sweat had been wiped off, her face seemed redder than before. She nodded to Roland, and said yes softly.

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In the next few days, Roland traveled back and forth between the castle and the North Slope mining area.

In addition to the barrel, he also needs to make a sufficient amount of boring tools.

The manufacturing method of this drilling tool is similar to that of a gun barrel. Its diameter is exactly the same as that of a cannonball. After it is taken out of the mold, Anna heats it again and shapes it with an iron hammer. It is very different from the ordinary spiral knife in appearance, at first glance it looks like a blunt iron rod. The only difference is that a gap is knocked out on the top of the head to discharge metal debris. Finally, it is quenched to improve the hardness of the boring tool.

Unlike the high-precision drill bits of modern boring machines, Roland only needs an iron rod that can punch holes. Considering the high wear rate, he and Anna made five simple boring tools within a week. Before this, the steam boring machine has fully verified its ability - the output of pig iron barrels has rapidly increased from two per month to ten per day.

When everything was ready, the cannon blanks were dug out of the pit by the miners, and after cleaning the surface scum, they were loaded onto a carriage and transported to the blacksmith shop.

These two cannon embryos almost consumed all the steel that Roland had accumulated, so it is not an exaggeration to say that they are priceless treasures. During the transportation, the prince ordered Carter and the two knights to take care of the whole process, which made the chief knight feel that it was unnecessary. Who would come to steal something so dead?

The blacksmiths leveled and polished the surface of the cannon blanks according to the prince's requirements. After the grindstone was polished, they were sent to the backyard of the castle non-stop. At this time, the two round solid steel rods were dark gray in appearance, exuding a thick metallic luster.

Roland couldn't wait to replace the boring tool, and together with Carter, fixed the cannon blank in place so that the tip of the tool tip was just in the center of the steel rod.

Facing this historic moment, Roland pulled the valve of the steam engine. The boring tool started to run slowly, and it didn't take long for it to rise to a stable speed.

"Into the knife!" cried the Prince.

The chief knight pushed the sliding base to control the contact depth between the cannon blank and the boring knife. When the knife head touched the barrel, the ear-piercing noise immediately overwhelmed the roar of the steam engine. Lard oil, which served as a lubricant, was squeezed into the borehole, and what came out was black foam and coiled wire. All the witches watching left the wooden shed one after another, only Lightning remained in place. It seemed to her that these dark machines were more beautiful than any scenery.

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