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"Nan Huairen, you want to make me more of this kind of small Hongyi cannon. This thing is amazing! Geng Jingzhong tried several shots in a row, and the results were very good, and he rubbed his hands happily and said to him.

"Yes, Your Highness the Prince, we have been casting cannons for more than a month. Oh, please go inside and take a look. "Nan Huairen has indeed worked very hard for more than a month, and as soon as the Western craftsmen arrived, he organized the craftsmen to start working. This non-stop, not a day of rest.

Geng Jingzhong entered the cannon casting workshop, which was much larger than the musket workshop. Although the personnel are relatively small, the tools used to cast the cannon are quite large. Seeing that the facilities here were quite complete, Geng Jingzhong was a little skeptical that his previous decision to move the workshop to Longyan was correct.

Nan Huairen walked beside Geng Jingzhong, watching the prince look around curiously, immediately turned around, stretched out his hand and said, "Your Royal Highness the prince, please go this way, I will take you to see the specific process of casting cannons." ”

When Geng Jingzhong heard this, he immediately walked in the direction he was pointing. Nan Huairen followed him and explained to him: "Your Royal Highness, this is the first step in casting cannons. The first thing to do is to make a mold. It's all there, and it's being left here to dry, and this step is very important. ”

Geng Jingzhong looked inside through the window, the space inside was very large, separated from the place where they were, and there were many barrel-shaped clay molds inside. Nan Huairen walked a few steps forward quickly, opened the door and led Geng Jingzhong in.

Geng Jingzhong was a little strange, "Why don't you put these molds in the sun to dry, isn't it faster?" As soon as these words came out, Geng Jingzhong regretted it, it was easy to dry out when exposed to the sun, and he had read so many years of books in vain!

Nan Huairen now knew that Geng Jingzhong was a complete rookie, and he didn't understand anything, so he continued: "Your Royal Highness the Prince, these clay molds must be dried in a ventilated place and where the sun does not shine, otherwise they will easily dry up and break quickly." On a sunny day, it takes almost a month, but if it's raining and cloudy, it takes even longer, maybe two or three months. If the craftsman is in a hurry and starts casting the cannon without waiting for the clay mold to dry completely, the cast cannon will not work. ”

Nan Huairen pointed to these molds that were drying in the shade: "These clay molds must be let dry before they can start casting cannons, otherwise the outside is dry, but the inside is still damp, when it encounters molten metal, the moisture is dissipated, and the cast artillery has many bubbles, so that the cast artillery is very easy to explode." "What Nan Huairen said is the truth, and this method is used in both China and the West at this time. No one dares to use a cannon with bubbles, and the consequences of forcibly using it will be very miserable, not to die on the spot, but to be blown up to a bloody blur!

"Not only that, but each cannon cast has its own clay mold, because when the cannon is taken, the mud tire inside is broken. So, we started by having the craftsmen cast a large number of molds. ”

Now Geng Jingzhong understands that this kind of clay casting method, each cannon corresponds to a mold, and the mold takes a long time to dry. These also have higher requirements for the craftsmanship of the craftsmen, none of the molds in front of them are the same, there are some differences more or less, can not be completely unified, after each cannon is cast, it can be said to be a unique work. This is not good, the cannon cast by this method cannot achieve the same inner diameter and diameter of the same model. There is still a little bit of moisture in the dry mud mold, and it is impossible to avoid the appearance of bubbles of different sizes in the gun body. This leaves a big safety hazard for the users of the artillery, and this problem must be solved. Unconsciously, Geng Jingzhong frowned again.

"Since this clay mold cannon has so many shortcomings, why not replace it with an iron mold cannon? The mold is cast with molten iron, isn't there no water vapor, and the specifications are unified? Geng Jingzhong suddenly said to Nan Huairen.

Nan Huairen was stunned when he heard this, can this iron mold cast a cannon? It sounds like no problem, but no one has ever done it.

Geng Jingzhong saw that he was a little stunned, so he continued: "I basically don't know anything about casting cannons, but I know that the difference between building cannons and building muskets shouldn't be too big. I think that's probably possible. For example, this clay mold I saw, maybe it would be better to replace it with iron! ”

Geng Jingzhong really doesn't know anything about casting cannons, but he once read the post on the post bar that someone invented this method of casting iron mold cannons in modern times, which is decades earlier than Europe, and there are few inventions in modern times that are ahead of Europe. In fact, this person's name is Gong Zhenlin. Gong Zhenlin was originally a county magistrate in Jiaxing County, Zhejiang Province, who had innovative ideas, was good at studying Western studies, and had a certain degree of research on Western arithmetic and firearms. At the outbreak of the ** war, that is, in 1840, he was transferred to the Ningbo military camp to supervise the production of ordnance, and wrote the book "Diagram of Iron Molds for Cast Cannons".

Gong Zhenlin said in the preface of his book "Casting Cannon Iron Mold Diagram": "Xin Chouqiu August, Jiaomen wrecked, the provincial city added to the Bureau of manufacturing, awarded Zhenlin to cast artillery, cast artillery to the soil as a model, after ten months, a mold is formed, a casting is scrapped, can not be reused, when the military side noon, slow and difficult, and when the winter season, rain and snow continue, the system is not easy, try to plan once and for all, think hard, to iron and soil as a model, and there is no way, so to create a private fantasy. That is to say, in the event of rain and snow, the clay mold will not be dry for a long time, and the construction period will be delayed, and he will be beheaded, so there is no way to start innovating on his own. This innovation is good, only continuous innovation can promote the progress of the times! As a result, the iron mold casting method came into being. In this way, Gong Zhenlin pioneered the casting of artillery with iron molds, which greatly accelerated the speed of cannon making.

And the process of iron mold casting cannon and the method of technical measures are recorded in detail in the "Diagram of Iron Mold".

Specifically, Gong Zhenlin's method of casting cannons with iron molds is not complicated at all. According to the record in the book, the cannon was first divided into several sections according to the size of the cannon, and the mud cannon was made first. Then according to the number of sections of the mud cannon, the iron mold mud type is divided, and the whole set of iron molds with layers of tenon and tenon is poured out one by one. After obtaining a qualified iron mold, the iron cannon is cast with an iron mold. First, the inner surface of the iron mold is brushed with fine rice husk ash and fine sand mud and water to form the paint, and then the second layer of paint prepared by ultra-fine pulverized coal is painted, and then the iron mold is tightened, the mud core is heated and assembled, and the molten iron is poured. After it solidifies, the iron mold is immediately removed, and when the gun body is still red, the burr is removed, the mud core is removed, and the finished product is obtained.

In this way, the casting process has become much simpler, and the most important thing is that the iron mold used for casting the cannon is no longer a one-time use like the clay mold, but can be used repeatedly, which completely saves the time and process of making the clay fan first, and greatly saves the time spent on casting the cannon. At the same time, because after the molten iron is cast into the iron mold, it is evenly heated, which eliminates the situation that there are air holes and pores in the gun body caused by water vapor during the original clay mold casting, and the quality of the cast artillery is greatly improved, which basically ensures that there will be no more accidents due to quality problems. At the same time, all guns made of one gun mold were all of the same size. The inner wall of the gun chamber is very smooth, which saves a lot of grinding the gun chamber process, and basically after casting, it can be used; Even if you polish the inner wall of the barrel, you only need to simply remove the burr. This also makes it much easier to supply logistics, and when casting shells, you can also unify the specifications. The inner diameter of the gun chamber is exactly the same, which fundamentally eliminates the situation that some of the same shells can be loaded into some gun chambers, but cannot be loaded into the gun chambers of other guns.

Gong Zhenlin's "Diagram of Iron Mold for Cast Cannon" also specifically summarized the seven advantages of iron mold casting cannon. Among them, the characteristics of the iron mold are that one mold is multi-cast, low cost, less man-hours, "with the cost of one work and the profit of hundreds of workers", "the province of the craftsman is not calculated"; Reduce the workload of surface cleaning and milling of the inner chamber; The mold does not contain water, less air pores, collects after use, is easy to maintain, and can be quickly put into production for emergency needs if it is urgent in wartime. All of this is quite true and realistic; In some major technical issues, it is consistent with the understanding of metal molds in modern foundry. It is very difficult to cast large iron castings weighing hundreds to thousands of catties from ferrous metal molds, and it is not easy even in modern times. Gong Zhenlin's first iron mold casting cannon is undoubtedly an outstanding technical achievement.

"Nan Huairen, I don't care if you have any difficulties, immediately order all the craftsmen to discuss the real yàn together, and use iron mold casting cannons instead. I believe that the iron mold casting cannon will not have as many problems as clay molds. After all, there is no moisture in the iron mold, and it should not be dried in the shade, and an iron mold can be used many times, so that all the artillery caliber is unified! I can think of a benefit that you professionals can solve. Geng Jingzhong introduced the advanced method with an advanced vision, which has absolute self-confidence, after all, this has been proven by facts in later generations.

"Okay, Your Highness the Prince, let's start doing this next." Nan Huairen was still in shock at the moment. The method of casting cannons with iron molds did not go beyond the technical range of this era. In the next two hundred years, there will be no change in the casting process, and it will always be a clay mold casting cannon. When a knowledgeable person like him listens to this, he knows what to do. Often before a new thing is born, it is only missing a hand to open that door; Now that Geng Jingzhong has pushed open this door, a bright avenue is in front of him, and Nan Huairen has decided in his heart that this is an excellent method.

"By the way, I forgot to ask you just now, how many cannons have you cast so far?" Geng Jingzhong suddenly remembered that the biggest purpose of this trip was to check the specific number of guns, and the others were just incidental, but now it's good, I've become an instructor!

"Back to His Royal Highness the Prince, a total of six cannons have been built since the start of construction, including the two that were test-fired just now."

"Six?" Geng Jingzhong was disappointed again, hundreds of Western craftsmen plus hundreds of local workers who were transferred to fight only made six cannons in more than a month! This efficiency is indeed low enough!

"Mr. Nan Huairen, to be honest, I am not satisfied with this kind of work efficiency. As you know, I'm short of artillery, especially high-powered artillery, and my warships are waiting for them to be installed! Therefore, the casting technology must be reformed, I think the iron mold casting cannon does not need to be dried for so long, presumably your work efficiency can be greatly improved, I look forward to your good news! ”

"I said a long time ago that His Royal Highness the Prince is a messenger sent by God, and you can come up with such a method without knowing how to cast cannons, you are so clever! Thank you for your teaching, I'm right away! ”