Seeing the frustrated expressions of Zhao Jie and the Portuguese people, Li Xiao also felt sorry in his heart. Pen, fun, pavilion www. biquge。 info

It's just that he didn't blame them for this, because Li Xiao knew how difficult it was to successfully cast an artillery piece in this late Ming era.

Before the middle of the 19th century, regardless of whether it was in the East or the West, because of the immaturity of the casting process, the scrap rate of artillery casting was actually quite high.

It is recorded in the "Fire Attack Essentials" that because the casting process was not very stable at that time, even in Europe, where artillery technology was relatively mature, "those who can get two or three guns for casting ten guns are called masters." In other words, the scrap rate of cast guns can be as high as 70~80%! At the same time, because the scrap rate is too high, it also leads to the casting price of artillery, which has remained high for a long time.

Li Xiao remembered that it was said in the history books that there were two very important reasons why the scrap rate of artillery casting was so high at this time.

One is the difference in cooling rate between the inside and outside of the barrel. Due to this difference in cooling speed, if you are not careful when casting the barrel, it will cause cracks in the barrel due to thermal expansion and contraction during cooling. And once there is a crack in the barrel, it is naturally a scrap.

The other is that the problem of uneven internal stress of the barrel will cause small cracks to appear in the barrel, and these small cracks are not visible on the outside, but are hidden in the metal of the pipe wall, and once released, they will be exposed.

Therefore, Sun Yuanhua, the governor of Denglai on the same day, stipulated that every time a finished artillery was built, even after passing the inspection of appearance, it would need to be tested three times.

That is to say, those who fill the barrel with gunpowder but do not load the shells, fire it three times in a row, and then check that there are no cracks in the pipe wall are qualified. If there is an internal injury to the pipe wall, it will definitely crack and expose in these three shots, and such a gun barrel can only be eliminated.

Li Xiao noticed that in the test area of the artillery factory, such scrapped gun barrels are piling up. In the finished product area, only ten light Hongyi guns weighing about 2,000 catties were successfully cast, and they were placed in a small column in the empty warehouse, which looked very inconspicuous.

Li Xiao sighed secretly in his heart, nearly a year has passed, and only ten doors have been built, and the output is too low. And the reason why artillery casting has not been able to scale up for a long time, this scrap rate is too high, should be an important reason.

Although Li Xiao only has a little knowledge of artillery casting, he has only obtained a little knowledge from books. But he suddenly thought that perhaps, he could briefly explain these experiences of later generations to them, let Zhao Jie and them grasp the direction, and then solve them.

Li Xiao remembered that in the history books he had read in his previous life, it was recorded that if the artillery barrel could be strengthened during the casting process, the scrap rate could be greatly reduced.

The so-called strengthening of the barrel of the artillery body is to use various means to apply a prestress from the outside to the inside of the barrel when the barrel is manufactured, which can offset the outward pressure generated by the explosion of some shells when they are fired. First, it can greatly extend the life of the barrel, greatly reduce the scrap rate, and speed up the casting speed. Second, the barrel wall can also not be so thick, so as to achieve the effect of obtaining the same chamber pressure endurance with a thinner barrel, so it can greatly reduce the weight of the gun and save costs, in the nineteenth century European experience, the weight of the barrel can be reduced by as much as 20~50%.

Li Xiao plans to replace the current copper-tired iron-core barrel with steel with better ductility and compactness, so that the weight of the gun body can be greatly reduced, perhaps, the reduction of nearly 50% is completely achievable.

Next, Li Xiao introduced the following two techniques to Zhao Jie and the three Portuguese.

The first is the internal mold water cooling technology.

This technology was invented by Rodman, an American in the mid-19th century, during the Civil War, so it is also known as the Rodman Law. At that time, it was said to increase the life of the gun barrel by as much as five times in one fell swoop. This technology can also be called the controllable cooling technology of the inner mold, or the water cooling technology of the internal mold.

And this technology, in fact, to put it bluntly, is also very simple, that is, because water cooling is faster than air cooling, if you want to let the inner layer of the cast barrel cool before the outer layer, then pour water into the barrel and implement water cooling.

Generally speaking, the natural cooling of the cast red-hot barrel when it is standing is from the outside to the inside, the reason is that the outer surface area of the barrel is larger than that of the inner tube, and the second is that the air circulation outside is faster than that of the inside, so that the natural outer layer is cooler than the inner layer. However, if the inner layer of the barrel can be cooled at the same time, or even cooled down before the outer layer, it can not only increase the cooling rate of the entire barrel, but also improve the performance of the barrel.

Of course, if you really stupidly pour cold water directly into the red-hot barrel, the result will only be that the barrel will burst quickly. In fact, the specific method is to replace the mold used as the inner mold of the barrel with a hollow one, add a cooling water pipe in the middle, and then pour cooling water into it. Of course, the cooling water pipe must be made into a recirculating style, such as a U-shaped pipe, or the outlet of the water pipe must be placed at the end of the gun and water must be filled from the inside, so that the cooling can be continuously circulated.

Seeing this, all readers may feel that this gun barrel cooling method is very similar to the CPU water cooling of the computer. The only problem with this water cooling method is that the cooling rate (that is, the water circulation speed) is still particular, and the inner tube will still break if it is cooled too quickly. And now Zhao Jie and if they want to adopt this method, they can also experiment slowly and find the right technical parameters, but it should not be difficult.

Once this method is adopted, the biggest benefit for Zhao Jie and his team is that it can greatly reduce the scrap rate.

The internal mold water cooling technology can ensure that the cooling rate of the inner and outer tubes is the same, or after experiments and adjustments, the speed difference is controlled within a safe range, so that the body tubes will not be suspected and injured due to inconsistent cooling temperatures. At the same time, because the internal and external tightness of the gun body is consistent, it is more robust, there is no dark damage, and the average life can be increased by nearly five times!

In other words, if an ordinary iron cannon can only shoot 600 rounds before it cracks and can no longer be used, this kind of artillery made by the water-cooling method can shoot 3,000 rounds before reaching its service life.

According to Rodman's data that year, after the Americans adopted this water-cooled cooling technology, the scrap rate of cast guns dropped from 70% to 80%, which was reduced to single digits!

Another very important advantage of this technology is that it is easier to cast large-caliber guns.

Because, when casting super-large caliber guns, the larger the caliber, the greater the difference between the internal and external cooling speeds. Therefore, in the era of natural cooling, the higher the caliber of the cannon, the higher the scrap rate when casting. And the price of minting will also rise exponentially as a result. And if the cannon to be cast is large enough to a certain extent, it is almost a 100% failure rate.

This is also the reason why Sun Yuanhua, the governor of Denglai, has very few large-caliber cannons cast in Dengzhou in the past few years, and most of them are small and medium-caliber artillery.

And among the 10 artillery pieces that Zhao Jie and they have cast now, all of them are light Hongyi cannons that can only shoot 6 or 8 catties of shells, and none of the heavy Hongyi cannons weighing more than 3,000 catties have been made.

And now, if the internal mold water cooling technology is used, this problem can be completely solved, and the heavy artillery that Li Xiao has always wanted to have that can shoot 12 or 16 kg shells can be officially produced.

After Li Xiao finished talking to Zhao Jie and the others about this technique, Zhao Jie and the three Portuguese were all excited, and they recorded it in detail with pen and paper.

Li Xiao could clearly feel that the eyes of Zhao Jie and the other craftsmen looking at him were full of admiration, which was very similar to the way those steelmakers looked at him.

Next, Li Xiao introduced them to the second artillery barrel strengthening technology.

This method is known as double-layer or multi-layer barrel nesting technology, also known as body barrel tightening technology. There are some similarities with the copper-tire iron core cannon that Zhao Jie and they are making now. But the specific production method is very different.

This method is designed to prevent uneven internal stresses from causing cracks in the barrel.

It's just that Sun Yuanhua's copper tire core method is to directly use the iron pipe as the inner mold, and then cast the copper pipe outside, in this way, there is no way to create inward prestress, which is why even if the cast barrel is not cracked, it often bursts during the test gun.

In the middle of the 19th century, there was a multi-layer nesting technology of gun barrels in Europe, which is simply to build an inner tube and an outer tube when the barrel is manufactured, and the inner diameter of the outer tube is smaller than the outer diameter of the inner tube, which is called interference. Theoretically, it is impossible to stuff such an inner tube into the outer tube, but the clever place is here, as long as the outer tube is heated and burned to hundreds of degrees, the outer tube will expand due to thermal expansion and cold contraction, and its inner diameter will also be enlarged, and when his inner diameter expands enough to exceed the outer diameter of the inner tube, the inner tube can be put into the outer tube. Then, when the outer tube shrinks after cooling, it will naturally clamp the inner tube inward, providing an inward prestress, making the inner barrel dense and compact, greatly reducing the space for cracks.

Moreover, this technology is very simple to use, as long as the outer barrel can be burned red to expand and trap the relatively low temperature of the inner tube.

With the development of the years, many different casting methods have appeared, for example, the outer tube can be entered in a set of several rings instead of a complete sleeve. If it is a complete sleeve with holes at one end and no at the other end, it is called a gun sleeve, and if it is a ring with holes at both ends, it is called a gun hoop. In addition, in addition to the two layers of the inner tube and the outer tube, the third and fourth layers of tubes can also be put on the outer tube if necessary to strengthen the pressure resistance of specific parts, especially the tail of the breech with the greatest pressure.

This layered approach is an additional advantage of this technology.

As we all know, the barrel wall of a cannon is generally not the same thickness as the front and back, usually the muzzle is thin and the tail is thick. This is because the gunpowder explodes at the tail of the gun, so the pressure at the tail of the gun is the highest, while the muzzle is at the lowest. If it is made to be as thick as the front and back, then the thickness of the barrel wall of the muzzle is actually an unnecessary excess weight.

Therefore, the barrel is generally cast in a thin front and thick back, but in this case, it will be more complicated to cast. If you use multiple layers of barrels for nesting, you can use barrels of the same thickness. For example, a 2-meter-long inner tube with the same thickness at the front and back, a 1-meter-long secondary outer tube, and a 50-centimeter-long outermost tube can be used to provide corresponding thickness to different parts of the barrel to withstand different pressures, thereby greatly reducing the difficulty of casting and increasing the manufacturing speed.

Typical examples of this technology are the Krupp cannon in Germany in the mid-19th century and the Armstrong cannon in England, which are the products of multi-layer nesting technology.

The biggest advantage of this technology is that the manufacturing procedures are simple, and it is relatively safe and convenient. In the mid-to-late nineteenth century, in the era of giant ship cannons, the large-caliber main guns of battleships were generally made in this way.

After listening to Li Xiao's introduction to this layer of multi-layer gun barrel nesting technology, Zhao Jie and all the craftsmen had an eye-opening feeling.

The technologies provided by Li Xiao, in fact, are not particularly complicated when it comes to real things, why can't I think of it?

In many cases, the bottleneck of technology, if it really needs to be broken, is a layer of window paper. The two cannon casting technologies provided by Li Xiao, which only appeared in the 19th century, were actually not too complicated when they were actually produced, and they were not limited by the technical base, and they did not need to use any nickel-chromium alloy steel like the cannons used by the modern army in the 21st century, so as to use precision machine tools for the production of modern military guns. Therefore, now that Li Xiao has provided technical ideas and directions, the next experiment, Zhao Jie and the Portuguese, as well as a group of craftsmen, can completely test and produce it.

Moreover, as long as the artillery factory does a good job of keeping key technologies secret, then these technologies will not flow out because the artillery is captured on the battlefield, and it will be difficult to imitate.

"Zhao Jie, this official asks you, under the condition that our army's steel has been successfully produced, to stop testing copper tire core guns in the future, and to change all to steel cannons. Both technologies can be used at the same time, and it is important to produce heavy artillery suitable for our army as soon as possible. ”

Li Xiao said to Zhao Jie and the others in a tone of earnest advice.

"Master Li, with your two skills, Zhao Jie, I can be said to be open! Don't worry, I will try to put the finished product into trial production as soon as possible, and you will be satisfied! Zhao Jie replied briskly.

In the end, Li Xiao and Zhao Jie agreed that it is now September, and they must successfully make the artillery by the end of this year, so that the production process is mature. Then, see that by March next year, at least 20 heavy Hongyi cannons that can fire 12 catties of iron bullets will be produced.

Zhao Jie promised to meet Li Xiao's requirements.

At this time, he seemed to think of something, he blinked at Li Xiao and smiled: "Lord Li, this new cannon has been built, have you ever thought about what name to give it?" ”

Li Xiao laughed, he groaned for a while, and then said aloud: "As the old saying goes, a swift attack is like a dragon strike. In the opinion of this official, this new steel cannon will be named the Dragon Bombardment. ”

"Okay, what a dragon cannon, it's imposing!" Li Xiao's naming made a group of craftsmen applaud.

Afterwards, Li Xiao chatted with everyone for a while, and then left the firearms research and development field.

When he left, he ordered Zhao Jie to transport all the ten copper-tired iron core cannons that had been made to Chifengwei for use.

After Li Xiao returned to Chifengwei, a soldier immediately came to report that the day before yesterday, he had received a flying pigeon message from Ding You, head of Taiwan's colonization group.

"Oh, show me quickly." Li Xiao ordered. (To be continued.) )