Who has the technical methods and steps of ancient sword casting?

The basic method of casting sword is casting, and there are roughly five processes in casting sword.

(1) Molding is to make a model for casting. Fan Jian is usually made of clay, which is then dried in a kiln with fire and then trimmed. The texture is like pottery, so it is called mud fan or pottery fan. The model is based on the shape design of bronze sword, and whether the shape of bronze sword can meet the design requirements, neat and harmonious, symmetrical and beautiful depends on whether the model is fine or not. The model also lays the foundation for the later decoration, such as the patterns and inscriptions cast on the sword body, and the inner wall of the sword model must be engraved with patterns with opposite yin and yang in advance. In fact, the first step of bronze sword decoration is the model.

(2) The adjustable casting sword is made of bronze, which is copper and tin or an alloy of copper and tin and lead. Dosage refers to the proportion of each component in bronze alloy, which was written as "gas" in ancient times. Before smelting bronze, copper, tin or copper, tin, lead and other raw materials must be mixed in a reasonable proportion, which is called batching. This is the key link to determine the performance of bronze sword. In a certain range, the increase of tin content in bronze can correspondingly improve the hardness and strength of the alloy; However, if the content of tin exceeds the limit of the total amount, the bronze alloy will become very fragile and easy to break. Adding a small amount of lead to bronze alloy can adjust the castability and machinability of metal, but too high lead content will also reduce the hardness and strength of the alloy. Therefore, only by mixing the components in a reasonable proportion can we get strong bronze suitable for sword materials.

The composition proportion of bronze sword alloy has been recognized in the Spring and Autumn Period and the Warring States Period. The "Six Kinds of Gold" recorded in "Flower King Gong Ji" indicates the composition proportion of six types of bronzes, of which the fourth category is: the big blade is the sword; Gold and tin each account for one third, that is to say, bronze alloy is divided into four parts, copper (gold) accounts for three parts (75%) and tin accounts for one part (25%).

In recent years, researchers of metallurgical history have analyzed and tested some bronze swords in the Central Plains in the late Spring and Autumn Period and during the war, and found that the copper content in their alloy composition is very close to that of "the gas of the big blade", which is about 75%. However, the content of tin is quite different, the actual content is only about 16%, and the higher content is only over 20%. This difference may be due to the fact that "Liu Qi" in Kao Gong Ji only represents the two most important bronze alloys-copper and tin, and copper often contains a small amount of lead and other elements (iron, zinc, etc. ). So Liu Qi's copper-tin ratio method probably generally represents the proportion of copper and other non-copper elements in bronze alloys, so the total amount of other non-copper elements in the actual composition of bronze swords is roughly close to percent.

Aside from the above differences between literature and objects, two things are clear. First, the record of "Qi of Big Blade" in Kao shows that craftsmen in the Central Plains had already known and summarized the collocation rules of bronze sword alloys during the Spring and Autumn Period and the Warring States Period, and used them as guidance for casting swords. Secondly, the actual alloy ratio of about 75% copper to about 16% tin is reasonable. Some researchers have tested the mechanical properties and hardness of this copper sword, which proves that it has good strength and hardness.

The ancients cast swords without advanced smelting equipment, pure raw materials and accurate detection methods. In this case, artisans have summed up the proportioning law of bronze alloys through long-term practice, which has strong regularity. The alloy proportioning of bronze swords will be different, but it will fluctuate up and down in the proportioning constant.

(3) After the smelting raw materials are prepared, they are put into a crucible for smelting. The purpose of smelting is to melt copper, tin, lead and other raw materials into liquid, and at the same time further remove impurities contained in the raw materials, such as charcoal attached to the raw materials, and other metal elements such as oxides, sulfides and iron contained in the raw materials, so as to make the alloy pure.

The key to melting is to observe the temperature and judge whether the melting is mature or not. This is described in detail in "Flower King Gong Ji":

Where gold is cast, gold and tin are exhausted, followed by yellow and white; Black pollution gas is produced by burning hydrocarbons such as charcoal and branches attached to raw materials. The yellow-white gas mainly melts tin with low melting point first, and at the same time, the oxides, sulfides and other elements contained in the raw materials volatilize to form different colors of smoke; Yellow and white gas is exhausted, followed by blue and white; With the increase of temperature, the blue flame color of copper melt is somewhat mixed, so it is now blue and white; Green and white gas is exhausted, followed by green gas; No matter how high the temperature is, copper is completely melted, and the amount of copper is greater than tin. As soon as it enters, there is only green gas. Moreover, the color of the flame is pure, indicating that too many impurities in the raw materials have evaporated and the remaining residues can be removed; Then you can vote. The pin is ripe and can be cast.

The above order is also a summary of the long-term practice of ancient craftsmen. Later, people used "perfection" to express their mastery of kung fu, which originated from this.

In order to improve the quality of bronze alloy, artisans also smelt copper and tin many times to further remove impurities. "Suk Kim was bombed" instead of "baked Gong Ji Shili", which means it is changed and fried repeatedly.

(4) Casting The molten bronze is poured into the sword mold, and once it is cooled and solidified, the bronze sword is formed.

(5) After casting, the copper sword made by the machining model is only a blank with a fine and rough surface. Therefore, after removing the model, the following finishing processes must be performed:

-Scraping and polishing to make its surface smooth;

-decoration, such as embedding colored glass and turquoise in the cast pattern groove, or embedding wrong red copper wire, gold wire and silver wire, or even further carving patterns on the device surface. Mosaic was a common decorative craft at that time. It is to cast or carve patterns on the surface of bronzes, then inlay gold, silver and copper wires (or pieces), and polish the surface with staggered stones, showing a vivid image with bright colors and clear lines.

—— Device accessories with swords;

-sharpen the blade.

In this way, the production of bronze sword was finally completed. However, in the process of use, the sword should be tempered from time to time, so there may be a class of craftsmen specializing in this work at that time. In the Han Dynasty, such craftsmen were called "sharpening knives" and their skills were also called "sprinkling". Grinding means grinding; Sprinkling refers to sharpening knives and sprinkling water, and generally refers to repairing swords.

In the Western Han Dynasty, Yuan Ang, a minister, was stabbed and his body was abandoned with a weapon. This is a newly repaired sword. When the government visited the sharpening workers in Chang 'an, a craftsman said: This sword was repaired by a Langguan in Liang Wang. Liang Xiaowang, the mastermind, was discovered.

To sum up, we can summarize the whole process of bronze sword casting with a passage from the great scholar Xunzi at the end of the Warring States Period:

The punishment (type) is gold, skillful work, fire (agent) and sentence termination. However, you can't break the rope without peeling and sharpening; Peel it off, grind it, put a plate on it, and the cows and horses immediately heard it.

Warring States swordsmen once said: white is strong, yellow is tough, yellow and white are strong and tough, and a good sword is also good.

This excellent sword is what we call compound sword today. During the Warring States period, the application of bronze swords reached its peak. In this context, sword casting has been developing and progressing, and some scientific and advanced technologies have appeared, and outstanding achievements have been made, especially the technology of casting compound swords.

The so-called composite sword refers to a bronze sword in which the ridge and blade are cast with bronze alloys with different composition ratios. Its sword ridge is made of bronze alloy with low tin content, which has strong toughness and is not easy to break; The blade is made of bronze alloy with high tin content, which has high hardness and is particularly sharp. Therefore, it is a masterpiece of ancient bronze swords. Its casting method is also different from the general bronze sword. The body of the common sword is cast once, while the composite sword is cast twice: first, the ridge is cast with a special ridge model, and embedded grooves are reserved on both sides of the ridge; Then put the cast ridge in another mold to cast the blade, and the blade and ridge are embedded together to form the whole sword.

From some composite swords detected by metallurgical history researchers, it can be known that the copper content of the sword ridge is higher than that of the general copper sword, but the tin content is lower than that of the general copper sword; On the contrary, the blade has lower copper content and higher tin content than the general copper sword. If the whole sword is made of only the material of ridge or blade, it will be too soft or too rigid and too brittle, but if the ridge and blade are made of it separately, it will get better performance than the general bronze sword. This is a superb technology that creatively uses the composition ratio law of bronze alloy, which shows that the ancient craftsmen have reached a very high level in controlling the composition ratio of bronze sword alloy.

The ridge of the compound sword contains more copper, so it is yellow; The blade contains much tin, so it is white. The ridge and blade of a sword are different colors, just as the fortuneteller said, so some people call it a "two-color sword". Because the surface of this sword looks like the ridge of the sword is inlaid, some people call it "bronze inlaid sword" or "heart inserted sword", which are not scientific names.