Late Ming sea owl

Chapter 241 Breakthrough in Iron Mold Casting Cannon Technology
After Xu Letian left, Lin Hai ordered the recall of the vanguard bureau that was clearing out the Daukas in Taoyuan, Hsinchu, and Miaoli so that they could rest before going out on the expedition.

The war with the Daukas has lasted for nearly half a year. After the formation of the army, the Vanguard Bureau only underwent one month of training and then went directly to the battlefield.

This war was actually nothing more than a cat-and-mouse game. The Vanguard Bureau took turns to fight in units of 100 people, half infantry and half cavalry, searching for traces of the Daukas people in the endless plateaus and hills. Once they captured 100 slaves, they could return to Tamsui for rotation.

This area is basically uninhabited, and the combat operations of the Vanguard Bureau are very difficult. Often, their rations are used up before the mission is completed. At this time, they can only rely on prey and wild fruits to fill their stomachs.

The troops returning to Tamsui only had a short rest period before they had to engage in daily training: the cavalry sentries had to train in semi-turn tactical formations, while the foot sentries had to train in subjects such as musket shooting and grenade throwing, and occasionally they had to train together with the Army Department.

After half a year, of course some people backed out. As long as the soldiers of the Vanguard Bureau were not on combat missions, they could apply to their superiors for withdrawal at any time. After withdrawal, they would be arranged to the auxiliary troops of the Army Ministry, and their monthly salary would drop sharply.

At the same time, in addition to slave labor, all male citizens of the Jinhe Kingdom and its vassal Iron Kingdom can sign up to join the Vanguard Bureau. However, the selection criteria are very strict, with high requirements for body shape, strength, speed, endurance, and Chinese proficiency.

In addition, one must pass the test in archery or horse riding. The requirements for horse riding are relatively low, mainly because the people of Jinhe Kingdom do not have horses. As long as you can ride a donkey or mule and run two laps around the training ground quickly, you will pass.

The Vanguard Bureau was already on track, but the Army's Artillery Bureau was abolished. But more than a month ago, Lin Hai established an artillery post directly under the Central Army in the Army, and the post commander was Jiang Yu, who had just returned from Java. He was originally a trial chief promoted from the captain of the auxiliary troops, and had always enjoyed the treatment of a post commander, so it was not considered a demotion.

The equipment of this artillery post is the latest light mortar developed by the Firearms Bureau. Currently, there are only two sample guns produced in the trial stage for their training, and the formal equipment has not yet been delivered for use.

After ordering the recall of the Vanguard Bureau, Lin Hai immediately went to the Firearms Bureau to inspect the production progress of this batch of mortars.

The development project of the light mortar has been launched for more than eight months. The design and trial production of the prototype gun took more than four months. A total of three models were trial-produced, with two prototype guns produced for each type. Finally, one model was selected after testing to equip the troops.

The caliber of this type of gun is close to four inches, roughly equivalent to the ten-jin gun (12 pounds) used by the navy, but the caliber is less than two times the gun diameter. Together with the gun mother, the total weight is about jin, and a strong mule can carry it for a hundred miles a day.

However, this gun mother is only a tool for carrying the cannon. When it is actually used, it must be installed on a special base. The base is not light and requires another mule to carry it.

Now, another four months have passed. According to calculations, the official equipment will be available soon. The main reason is that the production cycle of the clay mold is too long. The drying alone takes three to four months.

"General, two of the thirteen mortars are now being cast on the gun casting platform, and the other eleven are in line. The clay molds have been dried." The director of the Firearms Bureau reported to Lin Hai that the artillery post only needed ten mortars, but considering the possible scrapping, the Firearms Bureau made a total of thirteen clay molds.

This is mainly because the mortar has a small caliber and short multiples, so the yield rate is relatively high. If the navy uses a 10-jin cannon, 50 guns will have to be produced if 10 are delivered, which also means that 50 clay molds need to be made, which is really too much effort.

"How long do you expect it will take to be delivered for use?" The last time Lin Hai came to the Firearms Bureau was before he went to Japan, and the clay mold was still drying.

"Another month should be enough." The director of the Firearms Bureau said, "The main reason is that we only have two gun casting platforms. It will take several days to install the core and cast the gun. Machining and testing are easier. The mortar has a short caliber, so drilling the bore is not difficult. We also have a lot of boring machines in the bureau."

"So the current bottleneck is the gun casting platform?" Lin Hai nodded when he heard this. The Firearms Bureau had previously applied to build several more gun casting platforms, but because the production efficiency of the clay molds could not keep up, it was ultimately rejected. Unexpectedly, it has now become a bottleneck.

The main reason is that this batch of clay molds were made in parallel by additional staff, and Lin Hai's task to the Firearms Bureau was to deliver this batch of mortars before the end of the year, which means that it is very likely that they will not be able to make it in time for the decisive battle with Zheng Zhilong.

"Is there any way to speed up the progress?" Lin Hai asked again.

"Yes, Deputy Director He has a small gun casting platform, but if we want to use that platform, we have to ask the general manager to come forward." The Director of the Firearms Bureau added, "Half a month ago, Director Lun came to the Firearms Bureau and asked to requisition the small platform, but he couldn't persuade Deputy Director He."

Half a month ago, not long after Zheng Zhilong sent out his troops, Lun Diyi was quite clever. But He Liangtao was really stubborn and didn't even listen to his boss.

Starting with the imitation of flintlocks, the Construction Department established a research institute, with Deputy Director He Liangtao as the director. The small gun casting platform was an asset of the institute, not under the jurisdiction of the Firearms Bureau, and was mainly used for the iron mold casting cannon project. The project was launched after the trial production of the prototype of the four-inch mortar was completed, and no achievements had been made before Lin Hai went to Japan.

The current research projects of the Construction Bureau Research Institute are all related to firearms, and are also located in the middle reaches of Xindian Creek. Lin Hai then came to the institute again.

When He Liangtao heard that Lin Hai was coming, he hurried out to greet him in person. Since the iron mold casting cannon project was launched, he has lived in the middle reaches of Xindian Creek and has not been to Guandu for several months.

"Deputy Director He, how is the iron mold casting cannon project going?" Lin Hai was very concerned about this project. Even if it wasn't for the small casting platform, he would have come to the research institute to take a look this time.

"General Manager, we are casting a sample cannon. I think there is great hope this time." He Liangtao looked tired, but his eyes were full of excitement.

"Oh? Why are you so confident?" Lin Hai felt a little surprised. The last time he came to the institute, He Liangtao still seemed at a loss.

The mortars cast with iron molds at that time were brittle and hard. They exploded several times during testing and were ruined several times during the machining process. Everyone proposed various ideas for improving the process, but they all failed in the end.

"It's like this, Boss. Not long after you went to Japan, a craftsman who joined the Firearms Bureau half a year ago came to me and said he had a solution. I listened to his ideas and suddenly felt enlightened, so I transferred him to the Research Institute..."

"What's the idea?" Lin Hai interrupted He Liangtao. He actually knew the problem with the iron mold cast cannon and also knew the direction to solve the problem.

"He said that the reason why cannons cast from iron molds are hard and brittle is mainly because they cool down too quickly. I think it makes sense..." As soon as He Liangtao said this, Lin Hai knew he had found the crux of the problem. The biggest difference between iron molds and clay molds is indeed heat dissipation.

"This person joined the company half a year ago. Is he a new immigrant this year? What did he do before?" Lin Hai was very happy to hear that the institute had solved the problem on its own without his involvement. This was good news. "Yes, he is from Chongming. It is said that his hometown is in northern Zhili. He was originally a blacksmith." He Liangtao replied after hearing this.

"Oh? It's the blacksmith? What's his name? Ask him to come over so I can talk to him." Lin Hai felt a little surprised. After all, the Qing Dynasty had not solved the problem of white cast iron since it invented iron mold cast cannons, which meant that this problem was very difficult for the metallurgical field at that time.

"The name is a bit strange, it's Zuo Wuwei." He Liangtao said and asked someone to invite Zuo Wuwei over.

After half a cup of tea, a man with gray hair, unshaven beard and a slightly high hairline was invited over. He looked to be at least 40 or 50 years old. After seeing Lin Hai, he crossed his arms and said in a slightly reserved manner: "I am Zuo Wuwei, and I am honored to meet you, General Manager."

"No need to be so polite. How old are you?" Lin Hai was a little disappointed when he saw the visitor. He always believed that great innovations were made by young people.

"To reply to the commander-in-chief, I am 25 years old this year." Zuo Wuwei's words almost made Lin Hai spit out the tea in his mouth. It turned out that this guy had white hair at a young age, and his face did look a little older.

However, knowing that this person was not very old, Lin Hai was quite happy, and then asked: "Why do you say that the problem with the iron mold casting cannon is that it cools down too quickly?"

"Because when I was young, I saw my father using iron molds to cast farm tools such as plowshares. After casting, the iron farm tools had to be placed in a kiln to simmer, and then slowly cooled, so that they would not be so brittle..."

Lin Hai suddenly realized what Zuo Wuwei was talking about. It was an annealing process, or more specifically, pig iron softening technology.

He had seen in a military program in later generations that our army's arsenal during the Anti-Japanese War had been troubled by a problem. Specifically, the white iron grenade shells were too brittle and hard to process. The final solution used the German black heart toughening technology and Taihang Mountain stewing technology, which can be described as a combination of local and foreign technologies.

However, Lin Hai did not know that his ancestors actually had the technology to soften pig iron as early as the Warring States Period. By the Han Dynasty, they could use the annealing process to treat thin-walled cast iron parts and obtain blackheart malleable cast iron.

At that time, all agricultural tools were made using this process. However, due to the subsequent development of steelmaking technology, pig iron softening technology was basically eliminated in the field of agricultural tool manufacturing and was only circulated in remote mountainous areas. As a result, the problem of white cast iron in iron mold cast cannons, which was similar to this, was not solved in the Qing Dynasty.

"So your solution is to put the cast mortar into the kiln and simmer it?" Lin Hai asked.

"No, no, that won't work." Zuo Wuwei waved his hands. "The cannon tube is too thick, so that method won't work. But if we heat up the iron mold before casting, and don't let it cool down so quickly after casting, I think it's feasible. There are examples of cannons cast with clay molds, and the advantage of clay molds is that they dissipate heat slowly."

"Very good. I hope your method works." Lin Hai encouraged Zuo Wuwei. Although this man was inspired by his childhood experiences, his following words still reflected his thinking ability.

"General Manager, I have another idea, but I don't know whether I should say it or not." Encouraged by Lin Hai, Zuo Wuwei continued.

"Feel free to speak up if you have any ideas. The institute is not afraid of wild ideas." Lin Hai continued to encourage.

"It's like this. I've discovered a phenomenon in the past six months at the Firearms Bureau, that is, most of the defects of cast iron cannons appear near the inner wall. Although I don't know why this is the case, now that we know this phenomenon, why don't we just cast a solid cannon first, and then drill a hollow barrel. In this way, can't we remove all the defective parts? The yield rate of cast iron cannons will be greatly improved."

Zuo Wuwei went on to say: "Another advantage of doing this is that you don't have to make the core. And there will always be deviations when installing the core. It will be much better to use a drilling machine and a boring machine to process it."

Lin Hai was completely shocked when he heard this. What Zuo Wuwei was talking about was actually the solid bore technology in Europe more than a hundred years later. This was an epoch-making technological change in the history of artillery manufacturing. Its significance was not only the yield and accuracy that Zuo Wuwei mentioned.

Casting defects are a long-standing problem that is difficult to avoid even with modern technology, but in the field of artillery manufacturing, this problem can actually be avoided.

Because casting defects often appear in the center area of ​​the casting, which is determined by the principle of thermal expansion and contraction. Under natural cooling, the outer surface is easy to cool first due to its large area, and the inner part is the last to cool. Cooling requires shrinkage, and the outer surface has been fixed. Finally, air or loose structure is needed to compensate for the total volume. This leads to the defects of the cast iron cannon mentioned by Zuo Wuwei, which are often near the inner wall.

There are two solutions to this problem. One is the so-called inner mold water cooling technology, which allows the barrel to be cooled from the inside out, so that the inner layer is dense and the outer layer is loose, which is actually a bit like a composite gun with inner forging and outer casting. The famous Rodman gun casting method uses this technology, but with the current technical foundation, it will take a lifetime to make it.

The other is the solid drilling technology mentioned by Zuo Wuwei, which is much earlier than the Rodman cannon casting method. In short, it uses machining to circumvent the problem of casting defects, lowering the requirements for casting but increasing the requirements for machining.

The solid bore technology combined with the more breathable sand casting technology ultimately resulted in the lightweighting of cast artillery in Europe in the 18th century. The 12-pound field heavy artillery was almost half as light as before, which directly led to the emergence of cavalry artillery.

"Deputy Director He, what do you think?"

“It’s a good idea, but it’s difficult to implement.”

"Don't you like to do difficult things? I think solid bore drilling technology can be used as a long-term research topic, and sand mold casting cannons..."

Lin Hai had mentioned the sand casting cannon to He Liangtao a long time ago. Huiyou Company was now thriving, and he felt that these two things could be put on the agenda. As long as these two technologies were broken through, the army's field heavy artillery would basically reach the level of the Na-War period, which also meant a huge change in artillery tactics.

Of course, now that we have the technology of iron mold casting guns, the problem of the quantity of naval guns can be initially solved. After all, the navy is not so sensitive to the weight of artillery. The current problem is mainly that the production capacity is too low.

"Deputy Director He, if Engineer Zuo's method really solves the problem of iron mold casting cannons, I think he should be promoted to master craftsman as an exception, and then he can continue to study solid bore and sand mold casting cannons..."

(End of this chapter)