The four sand boxes are neatly placed on the ground, and even through the wooden planks, you can still feel the heat emitted by them, and now the cannon billets in the sand boxes are slowly dissipating heat to cool naturally.

How long does it take for the cannon blank to cool?

Zhu Mingzhong didn't know that there was another question in his mind.

"Although a hard furnace is used, the furnace temperature can be increased to a certain extent by increasing the air volume by adding a bellows, so that the temperature of the molten iron will increase, so the silicon content in the molten pig iron should also increase, and silica is an important element to promote graphitization. The air permeability of the sand mold is good, so the surface of the molten iron is not easy to produce pores, and the thermal conductivity coefficient is small, so the molten iron has sufficient time to gradually cool from the high temperature, and then precipitate graphite, so as to form high-quality gray cast iron. Gray cast iron is much tougher than white iron, and the graphitized structure is easier for metal cutting......"

The reason why Zhu Mingzhong considered this problem was because there was a hydraulic horizontal chamber bed in the Ordnance Factory, in fact, it was not a horizontal chamber bed at all, but a simple "chamber bed" with a drill bit driven by hydraulic power, although for Zhu Mingzhong, he would like to introduce the "solid drilling technology" invented by Jane Maudsley more than half a century later to cast solid castings and use a horizontal drilling chamber to drill out the gun chamber.

But before the design of the iron-making blast furnace, he would not have ventured to try this technology, and now the simple structure of the "chamber bed" is very simple, and even the shaft of the driving drill is directly connected to the waterwheel, and even the track is just a nanmu track.

It took two days and two nights for the natural cooling of the cannon blank, and after the sand box was opened in everyone's expectation, although the cannon was damaged with more than a dozen spikes formed by cast iron flowing into the vent, after washing the sand of the cannon body, the smoothness of the cannon body was still far beyond everyone's imagination.

"After a while, although the cannon has not been tested, it can be seen from the experience of casting no less than 100 guns, and the four sand-cast cannons are all rare and good products."

Dai Cang's expression looked a little excited, the reason why he was so excited was because he understood the difficulty of casting cannons.

"Not to mention that the cannon body is smooth and clean, that is, on its convenience, it is far better than the clay mold, after a little ignorance, the clay mold needs to be made of very familiar clay, and after the mold is made, it must be slowly baked through with charcoal fire. Moreover, the craftsman's wages are calculated on a daily basis, and once the craftsman wants to delay time, even if there is an official urging him, he can easily make defective products, and then the craftsman will use the excuse that the mold is not dry or the soil is not ripe. Sand Fan does not have these drawbacks. After the sand fan casting cannon is cast, the mold is removed after it cools, and the gun body is naturally smooth and clean, without modification. The crushed mud mold will stick to the cannon body, which needs to be carefully chiseled and polished by craftsmen, and more importantly, this sand mold does not need to be dried and does not contain water vapor, so there is no need to worry about the lack of eyes when casting, so that the casting cannon is naturally crippled and rarely ......"

The experience of casting cannons made Dai Cang very clear about the advantages of sand fan casting cannons, and when he was excited, the iron core was pulled out, and the one-inch thick sand that was originally covered on the iron core was also scattered, although the sand had not been completely removed, Xu Youzheng was already a little anxious to put his hand into the muzzle of the cannon, and touched the gun chamber with his hand to see if it was smooth.

"After a while, this hole is very smooth, and there is no need to wash it at all......

In fact, after the casting of cannons in this era, it is also necessary to "wash" the gun chamber, but this "washing" is more symbolic, because it is impossible to be chambered in white cast iron. At most, the only way to do this is to wash away some of the larger protrusions in the breech.

"Why don't you need to wash!"

Unlike Xu Youzheng's satisfaction with the smoothness of the gun chamber, Zhu Mingzhong shook his head and said.

"Don't forget, this six-pound cannon needs to be milled off at least half an inch before it can hit a six-pound iron bullet......"

But the question is, has the pig iron of the cast gun precipitated graphite to form a high-quality gray cast iron? If it is white cast iron, it is natural that it can no longer be drilled.

The cannon billet weighing nearly 1,300 catties was placed flat on a wooden crane after washing the sand in the gun body and gun chamber, the crane was located on the wooden rail, and the other end of the crane was pulled by a winch. However, this milling cutter is only made of stainless steel, after all, there was no tool steel in this era, but the invention of tool steel was at the end of the 19th century, and before that it was all steel cutters.

"I hope this steel cutter can drill the barrel!"

Zhu Mingzhong still seemed a little apprehensive about the eight square milling cutters inlaid on the drill bit, after all, he had long been accustomed to tool steel, tungsten carbide and other knives, when did he use ordinary steel knives. It was even for this reason that he introduced the cannon drill invented by Jane Maudsley, instead of the drill bits of later generations.

He was even glad that he had read the paper on the relationship between Caron's guns and iron-molded guns, and it was in that paper that he learned about Jane Maudsley's invention of the recumbent chamber bed and the gun drill.

"Big, big lord, do you want to drill now?"

In the craftsman's somewhat nervous inquiry, Zhu Mingzhong nodded and said.

"Drilling, destined to cool down ......"

When he said this, Zhu Mingzhong realized that when designing the rifling bed, he seemed to ignore the cooling measures during the rifling hole, if he could not cool the knife, the drill bit would soon become soft.

Just when Zhu Mingzhong was thinking about postponing the drilling because of this discovery, those experienced craftsmen gave him a solution to the problem.

"Master, if it cools down, you can lead water into the blast hole, you can nail a wooden frame next to the car, the rack is filled with wooden barrels, drill holes on the side of the barrel, and then use bamboo to introduce water from the bottom of the barrel into the blast hole......"

The explanation of the craftsman on the side made Zhu Mingzhong's eyes light up.

"I'll do it, that's it!"

He looked again at the proposed craftsman, who looked to be thirty years old at most.

"What's your name?"

"Master Hui, Sun Xingquan, a grass man, was originally a blacksmith in the shipyard?"

"You put forward this method very well, well, this month will be rewarded with a stone of rice grain as a commendation, and in the future, for each drill car made, as long as you use your method, each locomotive will be given five dollars of silver."

The old man's words made Sun Xingquan's eyes widen, and his eyes were full of incredible looks, and when he was surprised and wanted to kneel down to thank him, Zhu Mingzhong, whose strength was much greater than that of ordinary people, stretched out his hand and supported the other party with a slight force.

Then he looked at his frightened appearance, frowned, and scolded loudly.

"Stand, don't act like you don't have bones. This scripture needs a craftsman here, not a minion! ”

"Alas, yes, yes, grass, grass people obey!"

Sun Xingquan couldn't kneel anymore, so he had to respond with a trembling voice, and kept thanking him with a long bow.

"Thank you, thank you, thank you, thank you, for your ......"

"This is not a reward, it is what you Sun Xingquan deserves! Since this method was conceived by you, Sun Xingquan, it should naturally be patented! ”

Looking at the panicked craftsman in front of him, Zhu Mingzhong looked at the other craftsmen again, and then said loudly.

"In the future, in my arsenal, if the big guy thinks of any good ideas in other places, he can also say it together, as long as it is useful, not only will he be rewarded with silver, but also ...... Royalty for your personal benefit! ”

Patent!

This is Zhu Mingzhong's temporary thought of the method, most of the Chinese craftsmen in this era like to cherish their brooms, even when teaching apprentices, they also like to hide a hand, I don't know how many stunts, it is in this style of hiding a hand, disappeared in the long river of history, if you want to change their habits, you must lure them to profit.

As he spoke, Zhu Mingzhong turned his head and said to Dai Cang.

"You go to Qian Lei in a while and ask him to give an order in the name of the Jianghuai Economic Envoy. Whoever knows about the new methods of making iron, cannons, and weapons can go to the engineering department to report and apply for a patent. As long as what he reports, the armory factory can use it. Give him a reward according to the size of the use, the wider the use, the higher the bounty, at least one or two silver, no cap! If so, there is also a patent ......"

"The subordinate obeys!"

Dai Cang, who knew that he wanted to let these craftsmen show their unique skills, naturally replied extremely loudly. And the eyes of the craftsmen who were originally watching from the sidelines lit up instantly. They are all from artisan households, although the Qing Dynasty released the artisan registration, but for hundreds of years, the father has been passed down from son to son, son to grandson, and from generation to generation.

In the past, everyone was afraid that the ancestral secrets would be stolen and learned, and they were secretly hidden when they worked. But now that Master Jinglu has promised a heavy reward, whether to keep those unique skills in his family and pass them on to his son, or to exchange them for silver, makes them not think about it.

With this in mind, the onlookers began to talk about it, trying to come up with ideas for improving the craftsmanship of the drill. There are also some who have no special skills in their stomachs, and they will focus all their energy on the current weapon manufacturing, and maybe they will be rewarded in the future.

When the drill bit rotated at the muzzle, the craftsman at the winch kept turning the winch to pull the car, so that the drill bit went deep into the gun chamber, and in the harsh metal sound, the drill bit slowly stretched into the gun chamber, and when the water flowing down the bamboo piece flowed out along the gun mouth, it brought out a lot of metal debris......

When the metal chips flowed out, Zhu Mingzhong deliberately reached out and took some, looking at the iron filings in his hand, the corners of his lips were slightly raised - this cannon is done!