The cannon workshop was built earlier than the time required by Yu Xiaotian, and the thunder blacksmith was completely frightened this time, since Yu Xiaotian went out, he didn't dare to hang his son anymore, as if he was on a clockwork, first he asked Li Gouzi to make a bunch of lists, and then he had to go to seven or eight to start.

Among the laymen, two people were captured from the mixed river dragon, and after knowing that they could strike iron, they were put on the shore as reserve talents to work, and this time they were allocated to the thunder blacksmith.

Blacksmith Zhang also transferred an apprentice to Blacksmith Lei as his helper, so that the rack for the cannon was set up first.

As soon as the manpower was in place, the blacksmith took these people to start building a molten iron furnace in the cannon work, and the iron furnace used for casting cannons was much larger than the iron furnace used by ordinary blacksmiths, and it was necessary to ensure that a sufficient amount of molten iron was melted at one time, and one cannon could be cast at a time, otherwise it would not be possible to cast a qualified cannon.

Therefore, building such a furnace is something that a blacksmith who can cast cannons must do, and blacksmiths have their own skills in this regard, and they are kept secret from each other, and it is difficult for ordinary people to learn their skills.

For this artillery work, Yu Xiaotian paid great attention to it, and almost every day he took a little time to check the progress of the artillery construction site, forcing Lei Blacksmith to dare not slack off a little, and led people to be busy here from morning to night.

Although this guy's character is not good, his skills are still good, and when he really works hard, he is also quite hard-working, and he is fast at hand, which makes Yu Xiaotian very satisfied.

However, Yu Xiaotian didn't praise him twice because of this, because he knew that this kind of person can't be praised, once he is given a good face, such a person will immediately kick his nose in the face, so it is better to make him nervous.

When building the iron furnace, although Yu Xiaotian couldn't help much, he knew a little bit about this aspect, melting iron requires a very high temperature, and the furnace temperature must reach more than 1,500 degrees to melt pig iron, with the current technology, it is not easy to achieve such a furnace temperature.

One way to effectively increase the furnace temperature is to find a way to heat the air temperature at the air inlet first, and the higher the air temperature entering the furnace, the higher the furnace temperature.

Therefore, after listening to the introduction of the iron melting furnace by the blacksmith Lei, Yu Xiaotian immediately proposed to build an air preheating furnace or regenerative furnace before the air inlet of the melting iron furnace, and blow the air into the regenerative furnace through the bellows to heat, and then enter the melting iron furnace, so that the furnace temperature can be greatly improved, so that the temperature of the iron furnace can reach the required temperature faster.

After listening to Yu Xiaotian's suggestion, this Lei blacksmith was a little skeptical, and didn't believe that Yu Xiaotian said that the method was useful, but he didn't dare to say no, so he agreed to try.

This guy is also a smart person, and after thinking about it for a while, Yu Xiaotian carefully put forward some suggestions, and he knew what to do.

So the guy asked for help, and added a furnace in front of the furnace to heat the passing air, and a new type of furnace was built.

As for what kind of fuel is used for the furnace, Lei Blacksmith asked that coal should not be used, although Longyan in Fujian Province also produces coal, and it is not very difficult for Nanri Island to purchase coal, but Lei Blacksmith asked that only charcoal be used as fuel.

Yu Xiaotian understood the truth after thinking about it for a while, because people in this era did not know much about the sulfur contained in coal, and sulfur would reduce the quality of iron, but they also found that the iron made from coal was not as good in quality as the iron made from charcoal.

In this way, this also caused the quality of Guangdong iron, which was far better than the quality of iron in other places during the Ming Dynasty, so the quality of the iron cannons cast in Guangdong was naturally much higher than that of the iron cannons cast in the north.

This is also for what kind of court in the north of the country, will send people to Guangdong to buy Guangdong cast iron cannons, transported to the north for use, and the quality of the iron cannons cast in the north is always not as good as the quality of the iron cannons cast in Guangdong, the key reason is this.

So after Yu Xiaotian figured it out, he immediately nodded and agreed to Lei Blacksmith's request, and asked Li Yi to inform Li Yi and a few merchants who had set up a merchant on Nanri Island, asking them to find a way to procure good charcoal for the sea wolf.

In any case, charcoal is not a rare thing, in addition to being used to make iron, it is also indispensable for making gunpowder.

In addition, compared to coal, charcoal is easier to obtain nearby, and at the same time, it is easy to transport, and the price is not necessarily higher than coal.

So with the help of the merchants, several ships of charcoal were immediately sent to Nanri Island, which became the fuel for the next step of iron smelting.

With the efforts of the blacksmiths, the new cannon was quickly erected, and with the help of the carpenters, the hangers and other objects used to cast the cannon were also quickly built and installed in the ironwork shed.

When everything was ready, Lei Blacksmith was urged by Xiaotian to hurry up and start making the gun mold of the first cannon, Yu Xiaotian felt that casting a cannon was not a difficult thing, but when he really let him cast the cannon himself, he found that things were not as simple as he thought.

Before opening the cannon mold, we must first determine the size of the cannon to be cast, and after setting the size of the cannon, we must first make a male mold with wood, and then we can use the male mold to make a clay model for casting the cannon.

After the clay model is done, it cannot be poured immediately, and the gun mold must be thoroughly dried or dried to ensure that there is no excessive water in the gun mold.

If the clay fan is not dry enough, once you are in a hurry to cast the cannon, then the result will be that the moisture in the clay fan will vaporize, causing a large number of bubbles to appear in the cast iron of the cannon body, then this cannon iron must be a waste product, if you use it forcibly, there is only one result, that is, the bore!

At that time, whoever operates this cannon will be poured blood mold, and if he doesn't hang up on the spot, he will at least be blown up to a bloody blur!

And this kind of clay fan casting cannon method, not only the craftsman craftsmanship is very high, many times basically rely on the experience of the craftsman, each time the cannon mold is opened, can not achieve the unity of shape, after each cannon casting, it can be said that it is a unique work.

The craftsmen never communicate with each other, each pondering their own so-called secret methods, so that the casting methods of artillery can not be used for mutual reference, which greatly limits the progress of artillery development, and even regresses in history, there are historical records, after the middle of the Qing Dynasty, because of the continuous loss of artillery casting skills, so that the quality of artillery casting in the middle of the Qing Dynasty can not even catch up with the quality of the last years of the Ming Dynasty, the artillery is getting more and more stupid, and the quality is getting worse and worse, and the range power is not as good as before.

The most important thing is that the inner diameter of the gun cast by this method cannot be uniform, and the inner wall is difficult to make very smooth, and it is impossible to avoid bubbles of different sizes in the gun body.

This is a great safety hazard for the users of artillery, and at the same time, it is impossible to achieve a uniform caliber of shells, and it is also very troublesome to produce shells.

Therefore, if you want to cast a qualified cannon, this era is by no means an easy thing, this matter is not in a hurry, Yu Xiaotian looked at such progress, and couldn't help but sigh.

Just when Xiaotian was worried about the matter of casting cannons, in the blink of an eye, he remembered a person again, that is, a person named Gong Zhenlin in the late Qing Dynasty.

He once inadvertently browsed about this Gong Zhenlin on some websites, and this person can be said to have left a strong mark in the history of China's military science and technology, especially in the history of China's artillery development.

Gong Zhenlin was once an official in the late Qing Dynasty, during the Opium War, many forts along the coast of China were destroyed by the British army, and the Qing Dynasty urgently needed to purchase a large number of artillery batteries to equip the coastal batteries and arm their own ships.

Therefore, at that time, the Qing Dynasty ordered all kinds of artillery in large quantities in various places, but the result was that because of the backward artillery-making technology and the rush to build the project, the quality of the artillery cast was very poor, and it is said that the pores in some cannons were so large that they could be filled with a bowl of water.

This Gong Zhenlin was appointed as the official who supervised the artillery, so he racked his brains to come up with a new way of casting cannons, and immediately popularized this method of casting cannons, and finally made the Qing Dynasty obtain a large number of usable cannons in a short period of time.

Specifically, his method of casting iron cannons is not complicated, according to the records at the time, he first made mud cannons according to the size of the iron cannon, divided into 4-7 sections. Then according to the number of mud cannon sections, the iron mold mud type is divided, each section of the mud type is divided into two petals, and the inner surface is rotated to make the surface smooth and clean, the shape is regular, and then dried for later use. A prefabricated handle is placed in the clay mold, and it is cast into one piece with the iron mold when poured.

Then, when turning the cast iron mold with the mud mold, first put the section of the muzzle upside down on the mud plate, fill one of the petals with mud, after drying, cover the mud plate, tighten the mold, and get a petal of the first iron mold after pouring. Then remove the filling mud, and cast another iron mold in the same way. In this way, the section by section pouring can be cast into a complete set of iron molds with layers of tenons.

After obtaining the qualified iron mold, when casting the iron cannon with the iron mold, first brush the inner surface of the mold with fine rice husk ash and fine sand mud and add water to form the coating, and then paint the second layer of paint prepared by extremely fine pulverized coal, and then hoop the iron mold, bake and assemble the mud core, and pour the molten iron. After solidification, the iron mold is taken off immediately, and when the gun body is still red-hot, 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, the most important thing is that the iron fan used for casting the cannon is no longer a one-time use, it can be used repeatedly and continuously, and the time and process of making the mud fan are completely omitted, and the time spent on casting the cannon is greatly saved, and at the same time, because the molten iron is cast into the iron cannon mold, the heating is uniform, and there will be no more water vapor in the gun body to cause air holes and pores, and the quality of the cast cannon is greatly improved, which basically ensures that there will be no more accidents that blow up the chamber because of quality problems.

This is undoubtedly the best thing for the user of the artillery, which can ensure the safety of the user, and at the same time greatly boost the morale of the user, so that they do not have to worry about whether their cannon will explode in the next moment, so there is no need to deliberately reduce the loading of gunpowder for their own safety, resulting in a significant reduction in the range and power of the artillery.

In addition, there is a very big advantage that all the guns cast by such a gun mold are all unified, and the inner wall of the gun chamber is also very smooth, which saves a lot of grinding the process of the gun chamber.

This also makes the logistics supply much easier, when casting shells, you can try to ensure that the inner diameter of the barrel is exactly the same, anyway, there is no need to worry about the same shells can be loaded into some barrels, but not into the chambers of others.

In short, the iron fan casting method is in the words of the ancients, "use the cost of one work and collect the benefits of hundreds of labors, and the province of labor is not counted!" ”

(Good news!) After discussing with the editor, the release time of this book has been postponed, and I will notify you separately once there is news! Thank you, brethren, for your help! In addition, special thanks to qshh2006 friends for their tips! ）