This made Xia Hongsheng feel shocked, and he was inspired to hear the words from Master Mao's mouth, using iron molds to make cannon barrels. Pen & Fun & Pavilion www.biquge.info

These words were like a key that opened some memories in Xia Hongsheng's mind.

It is still a matter of traveling in later generations, seeing the historical sites of Humen cigarette sales, visiting museums, and seeing red-coated cannons in museums.

At that time, the tour guide told everyone about the backwardness of the artillery technology of the Qing Dynasty at that time, and said that since the Ming Dynasty, the technology of artillery has not been updated, but the red-coated cannon has been lengthened, thickened and aggravated. During the First Opium War, the cannon of Humen Fortress weighed 8,000 catties, but the firing range was not as good as the British naval guns, and after the Second Opium War, Jiangyin Fortress was equipped with 10,000 catties of iron cannon "General Yaowei". These cannons seem to be mighty, but in fact the range is not as good as those Hongyi cannons imported from the Ming Dynasty. And the only place that is more advanced than the great powers is the iron casting method invented by the Chinese after the Opium War. This iron fan casting method is extremely low-tech, cheap and fast, the effect is outstanding, with the cooling self-tightening technology, can create the strongest artillery in ancient times, very powerful, it is simply a must for traversers.

Xia Hongsheng listened to the tour guide at that time, sighed in his heart for a while, and then forgot about it.

When Master Mao said that he would try to make a mold with iron, Xia Hongsheng suddenly remembered.

For a long time before the use of iron fan casting to make cannon bodies, clay models were used to cast guns. This is quite time-consuming. For each artillery, you need to make a wax model first, and then turn the sand into a casting mold to make a clay model. Just a sand turning mold of the drying process, if it is not a very exquisite skill, and work overtime day and night, it often takes a month or two, a little careless, the model may crack and deform and be completely scrapped, even if it is completely in accordance with the process of carefully doing the mud fan, sometimes it is disturbed by factors such as temperature, so finally after a number of processes, a cannon can be cast, and the artillery, each of which can be called a unique work in this world, but relatively speaking, This process is also labor-intensive and time-consuming. Moreover, although the shape of the cast cannon is required to be unified, after all, it is not cast by a mold, and there are still some subtle differences, especially in the inner diameter of the gun chamber, it is not easy to achieve complete unification, and if the mold of turning sand is not completely dried, the water in the mold will evaporate as soon as the copper water or molten iron is injected into the mold, so that there is a cavity or sand hole in the casting, which seriously affects the casting quality. It is precisely for this reason that it is caused. And when the copper water is poured into the mold, the existing sand turning mold dissipates heat slowly, and when the copper water is cooled in the mold, because of the different components therein, the lighter material will float on the top, and the heavier material will sink below, so that the cast cannon body may appear uneven material, and may also affect the quality of the gun. In the same way, the projectile is made in this way, and the same problem will appear with the projectile. Just imagine, the inner wall of the gun chamber is not uniform, and the outer wall of the projectile is not uniform.

And Tiefan refers to the iron mold. Iron fan casting is a kind of hard mold casting, that is, iron is used to make molds, and the molds can be reused. The advantage of using iron as a mold is that the iron mold itself can be polished very smooth, so that the cast gun chamber is naturally smooth, with less trachoma and high quality.

In addition, due to the low temperature of the iron fan, the temperature of the iron fan will not rise too high at the moment after the molten iron is poured into the iron fan, and then due to the cold water poured into the hollow iron fan, the molten iron will be quickly cooled, hardened and contracted, forming a "gap" between the solidified molten iron and the iron fan, and the molten iron is actually cooled in the "gap". This kind of water-cooled self-tightening makes the cannon that has not yet cooled in the casting start to cool from the inside, so that the cannon has a force from the outside to the inside, which is equivalent to wrapping an iron hoop around the whole body of the gun, so that the cannon can withstand higher chamber pressure and increase the charge.

In fact, Tiefan casting has long appeared in China and has been widely used. For example, in the Han Dynasty, agricultural tools had already begun to be cast with iron fans. Because the mold made of iron is durable and can be used many times, and the casting amount of farm tools is relatively large, if you use clay molds, you have to make a new mold if you don't make a few farm tools, so you generally use iron molds, which can be used for a long time to make many of the same farm tools.

In fact, it is a matter of thinking, but no one thinks of it.

The reason why large items are not made of iron molds but mud molds is that although clay molds are also laborious to make, they are easier than casting iron molds. Moreover, the cost of the clay mold is low, easy to adjust, if there is a problem, just cut that part and re-paste the adjusted one. Therefore, for larger objects, no one has ever considered using iron molds in the past.

The iron fan cast cannon only appeared in the nineteenth century, but these masters got together and broke the convention, crossed the shackles of thinking inertia and daily habits, and allowed it to advance by nearly a thousand years.

This is inseparable from the innovative and enlightened atmosphere and atmosphere carefully created by Xia Hongsheng in the military aircraft workshop.

On the third day of the vigil, when Xia Hongsheng came out of the mourning hall, the master came to find Xia Hongsheng again.

Xia Hongsheng followed the master to the shed, thinking that there was good news, but when he arrived in the shed, he saw several masters with sad faces and locked brows, so he chuckled in his heart again.

"Master Hou, there is a problem again." Master Mao saw that Xia Hongsheng had gone, and after saluting, he said: "Pour it with cold water to make the barrel in the iron mold tighten, and listen to the sound when you knock it, but it is indeed a lot tighter." However, it made the barrel brittle. ”

As he spoke, Master Mao grabbed the thick rope on his side violently, and fell hard, only to hear a sound of gears, and then pulled up a huge iron hammer, and then as soon as he let go, the hammer fell down heavily, and smashed into a cannon barrel directly below.

I only heard a loud bang, and when I looked down, the small barrel of the cannon was smashed.

"Master Hou, look!" Master Fu bent down and picked up a piece from the ground, pointed to the edge of the splinter and said to Xia Hongsheng: "This broken section is white, this is white iron, white iron is too brittle to be used as a cannon barrel." Master Hou, let's discuss it, shouldn't we use cold water to irrigate? ”

Xia Hongsheng frowned, this iron fan casting with water cooling and self-tightening, it is obviously like this, but why is it brittle here? “

After thinking about it, he asked again: "When does this white iron often appear?" “

It was full of masters, and immediately someone replied: "As soon as the hot iron is cold, it will become brittle and become white iron." ”

"This ......" Xia Hongsheng thought about it carefully again, and said, "Is it that the cold water is poured too quickly, which is aroused?" Why don't you try to pour cold water slowly? ”