19 18. After World War I, Japan allocated huge sums of money to build new battleships. The Longmen class battleship completed in 1920 was the world's first battleship with a main gun caliber of 4 10 mm, and it was the most powerful battleship at that time.
So, how powerful is the main gun of Nagato Battleship? According to the shell weight, muzzle velocity and impact point lethality, the1410mm main gun was equivalent to the190 75mm field gun of the army at that time. If auxiliary guns, anti-aircraft guns, torpedoes and other weapons are added, the attack power of 1 Nagato battleship is equivalent to that of 1400 Japanese 75mm field guns, which is even more powerful than several artillery divisions.
So, how is the powerful gun like the main gun of Nagato Battleship made? The following is a detailed introduction to the manufacturing process of the main gun of the Japanese Changmen class battleship.
1, exquisite steel production technology is the foundation.
First of all, superb steel production technology is the necessary foundation for manufacturing this large-caliber gun.
After the Meiji Restoration in Japan, a modern army was established, and the demand for new weapons increased rapidly, which could not be met only by purchasing from abroad. With the development of military enterprises and the birth of Lu Haijun, Japanese steel manufacturing industry developed rapidly in the middle of Meiji period. 1880, the Japanese navy introduced the crucible steelmaking method to the arsenals in Tokyo and Tsukiji, which is the most advanced modern steelmaking enterprise in Japan. Subsequently, in order to produce naval guns, 1890, Yokosuga Arsenal introduced the latest 3-ton open hearth steelmaking furnace and began to produce high-quality steel.
After nearly 20 years of development, in the Taisho era of 19 1 1 year, Japanese steelmaking technology has reached a considerable level. It is no longer a problem for Yokosuga Arsenal to produce medium and small caliber guns for warships, and Wu Jungang is also capable of producing large caliber naval guns and turrets. The equipment of these factories has been improved to produce 100 tons of high-grade gun barrel steel. At the same time, Japan has mastered a variety of technologies suitable for the production of main gun tubes, and can produce battleship main guns.
So how much equipment do steel mills need to produce large-caliber naval guns? We only make a rough calculation by taking the then Japanese Muroran Iron and Steel Company as an example. The foundry of Japan Muroran Steel Works covers an area of 479 1 m2, including two 50-ton steelmaking furnaces, six 2 5-ton steelmaking furnaces and two 10-ton steelmaking furnaces. It was a large-scale steelmaking plant in Japan at that time. In order to transport large castings in the workshop, 50-ton and 120-ton crown blocks were installed in the door.
100t hydraulic forging press is the most basic equipment in forging workshop. As a 400-ton hydraulic forging press attached to the annealing furnace, the main equipment is 1000 ton and 2000 ton hydraulic forging presses for producing gun shafts, 650mm edge crusher and 450mm rolling mill.
In addition, there are large-scale equipment such as steel heating tank of gun barrel, embedded tower of gun barrel and stress adjustment tower of gun barrel. It was the most advanced equipment in East Asia at that time. There are only two Japanese private weapons manufacturers that can compete with it, Mitsui's Japan Steel Works and Mitsubishi's Nagasaki Weapons Institute. All of them are mainly engaged in shipbuilding, and have many large workshops such as casting, forging, construction machinery, motor and metal processing. , and has a fairly strong arms production capacity. Until today, Japan Steel Works is still the most important military production enterprise in Japan, and almost all the barrels of the Japanese Self-Defense Force are produced here. As the most important weapon of warship, the production of 1 large caliber main gun barrel requires very complicated technology. After the Meiji Restoration in Japan, the main gun barrel was completely imported from abroad for a long time when building modern warships. By introducing technology and digestion and absorption, by the late stage of 19 10, Japan had been able to produce large-caliber naval guns by itself. Roughly speaking, starting from casting steel, it takes dozens of processes to complete a main gun barrel, which is quite complicated and requires a lot of skilled workers and professional equipment.
2. Blank manufacturing that needs the support of super-large equipment
Roughly speaking, the manufacture of 1 main gun can be divided into two parts: rough blank and fine assembly.
Making rough blanks is the most basic work. Although it does not need fine processing, it needs a lot of large machinery. Referring to 1934 "Gun Production Reference Book" formulated by Japanese Naval Academy, we can learn step by step how a pile of iron ore changed from ingot to 4 10 mm gun mounted on a battleship.
The most basic raw materials are very complicated, including 44 tons of iron filings, 33 tons of fine steel filings, 2 tons of nickel chromium, 36 tons of limestone and other auxiliary materials for decarbonization and deoxidation of iron slag, totaling 1 15 tons. They are sent to an open-hearth furnace and heated to 1700 degrees. After being melted into molten steel, they are cast into huge ingots. Then the ingot is heated to 1300℃ and quenched and tempered, so that the crystallization of the ingot is more uniform and more suitable for forging.
If the barrel is made of only one layer of metal, it is called a single-layer gun; If it is made of multiple layers of metal sheathed together, it is called a multi-layer gun; If the inner cylinder is reinforced with steel wire, it is called a steel wire sheathed gun. The Longmen 4 10 mm main gun consists of two layers of barrels, inner and outer, and reinforced with steel wire to resist the huge bore pressure during shooting. Each barrel needs to be cast with four steel ingots, and then made into muzzle sleeve, tail sleeve, outer tube and inner tube respectively.
The quenched and tempered ingot is sent to a forging press for preliminary forming, then forged into a cylinder, and then annealed to eliminate the internal stress generated during cooling.
Because the bottom of the ingot is the most prone to problems in the casting process, it needs to be cut with a large saw blade cutting machine, and the cut part accounts for about 5% of the total volume of the ingot. At the same time, the top that is prone to problems should also be cut off. Cut more here, about 20%. That is to say, about 1 15 tons of steel ingots are useless wastes. In addition, the center of the ingot is also a part that is prone to problems during casting, so the center of the ingot should be drilled off with the super-long drill of a large drilling machine before forging.
The drilled hollow cylinder is sent to a heating furnace and heated to 1600 degrees. In order to ensure its uniform heating, the heating furnace uses carbon monoxide as fuel. It was not until the steel column was burned red and the temperature was uniform that it was pulled to a large hydraulic press and forged into the shape of a barrel, which became the most basic rough blank.
In the process of making the blank, every working procedure must be carefully checked, especially the inner barrel, so as to ensure that there are no cracks. Because when shooting, even the smallest crack in the inner cylinder may collapse under the action of huge bore pressure. If the collapsed steel chips lead to an explosion in the bore, then the huge warship will be blown up by its own shells in an instant.
In fact, the best material for the barrel should be alloy steel doped with nickel and chromium. Just because the amount of nickel and chromium is too small, if the manufacturing cost of the whole barrel is too high, a double-layer barrel will appear, but the inner tube is made of nickel-chromium alloy steel and the outer tube is made of other alloy steels with lower cost, thus reducing the manufacturing cost of the barrel.
After forging, the inner cylinder needs to be heated to 600 degrees for annealing to eliminate internal stress. Then put it on a large milling machine, turn out the shape of the outer wall of the barrel, and then finish the inner wall of the barrel with a large-caliber milling handle.
The formed blank should be hardened inside and outside to improve the strength of the barrel. Mainly to prevent the barrel from deforming when it is placed horizontally, such a long barrel can only be heat treated with large vertical Gagetta and high temperature mineral oil as media. After surface hardening, it should be annealed at 650℃ again to eliminate internal stress.
Finally, through a series of tests, the elastic strength, yield strength, ductility, area shrinkage, impact resistance, hardness and other indicators can meet the requirements. Only the blanks with qualified indexes can enter the next stage of finishing and finally be assembled into 1 powerful warship main gun barrel.
3. Precise assembly to the extreme
Through a series of previous processes, we have obtained four components that make up the 1 barrel: muzzle sleeve, tail sleeve, outer barrel and inner barrel.
This is only the first step, and it needs to be assembled through a lot of complicated and delicate work. First of all, the blank should be finished with a large milling machine and boring machine, which is the most critical, requiring extremely high machining accuracy and minimal error rate, because they will be nested together by heating inlay. This requires accurate calculation of metal heat treatment deformation and close cooperation of skilled workers. If it is even a little bigger than the design error or the workers are slightly negligent, they will not be assembled together in the end.
The milled inner barrel must be put into the outer barrel with a special crane. To vertically put an inner barrel weighing 50 tons into an outer barrel with a diameter of only about 1 m, such fine operation requires workers to have very skilled technology and rich experience.
After the inner and outer gun barrels are sleeved, in order to improve their strength, a layer of steel wire should be tightly wrapped on the outer wall, and the steel wire on each gun barrel should be straightened up to meters, that is, 300 kilometers long. As you can imagine, this is a laborious job.
The barrel wrapped with steel wire should be installed in the casing to improve its compressive strength. The outermost shell is divided into two parts: the muzzle and the tail. Their inner diameter is slightly smaller than that of the outer cylinder. Based on the principle of thermal expansion and cold contraction, it is heated first and then sheathed on the outer layer of the inner cylinder. After cooling, they are closely combined.
When all the four layers of cylinders are combined together, the final forming is needed, and the internal and external walls are finally formed and milled with a large milling machine and boring machine. Then determining the accuracy of the gun is the most critical process. Making rifling on the inner wall of gun barrel with large rifling machine is the most demanding step in all processes.
After the rifling is finished, the rifling in the barrel should be chrome-plated, only a few tenths of a millimeter. Don't underestimate this thin layer of chromium, which can resist high temperature and corrosion, and can improve the service life of barrel by two to three times, which is very important for the main gun of ultra-expensive warships. Finally, we must install the bolt. The large-caliber main guns of battleships are generally sub-packed warheads, so the gun tails are generally threaded (of course, there are exceptions, and Krupp guns in Germany generally adopt the classic cross wedge gun tails with closed gas rings in the gun bore), thus making a 4 10 mm caliber 1 main gun.
After the barrel is made, it needs to be tested at the shooting range if it is a developed model. The maximum bore pressure and muzzle velocity, limit range and effective range, hit accuracy, service life and armor-piercing efficiency of all kinds of shells should be tested in all directions. If anything does not meet the design standards, it needs to be redesigned and manufactured. It is conceivable how much research funds will be spent. Without the strong financial support behind the country, it is impossible to carry out such expensive scientific research experiments.
After the barrel is built, warships need to be installed to complete the task. However, Japanese gun factories and shipyards are often located in two cities. How to put these huge barrels on warships? Because most naval gun factories are built in port cities, the main guns are generally shipped by sea. Before 1940, huge barrels similar to Nagato's main guns were transported by the special transport ship "Zhichuang". With the construction of the battleship Yamato, the tonnage of Tombed is not enough to transport the 460 mm main gun barrel used by Yamato. 1in July, 940, the Japanese navy specially built the special transport ship "Jian Ye" to transport the main gun of "Yamato".
The special carrier "Silver Leaf" has a displacement of 10360 tons and adopts a double hull to improve the sinking resistance. Even if you hit the rocks, you won't sink easily. Because the L main gun barrel of the battleship is too expensive. "Threshold Yard" can transport 1 2230 tons triple 460mm main gun turret and 3 doors 160 tons 460mm main gun barrel at one time. At the same time, the ship also has a special cabin for transporting turret armor. Moreover, the special transport ship "Threshold Field" still has a large design margin, because the second largest and class battleship planned by the Japanese Navy at that time would use the 5 10 mm caliber main gun. If this super battleship starts construction, Threshold Field will also transport huge turrets and main guns for it in the future.
From these simple introductions, we can see that the manufacture of the main gun barrel of 1 battleship is a very huge project, which requires a strong industrial foundation, otherwise it cannot be produced only by those large-scale processing equipment. In addition, there must be a large number of skilled professional workers and managers to make overall arrangements for each process, and carefully check the products after each process. Only in this way can we produce L-class qualified warship main guns. Because of this, before the First World War, the number of super-expensive battleships and the size of their main guns will become a symbol to measure a country's comprehensive national strength.