The answer may be the composite production technology of ancient bronze soldiers; Representative ones are: compound sword, compound kudzu, compound Be, compound graupel and so on.
Composite sword refers to a bronze sword in which the ridge and blade are cast with bronze alloys with different composition ratios. The composite structure of ridge and blade is closely related in technology. The compound sword technique first appeared in the early Warring States period, which was a technological change from stabbing to chopping in ancient China. The casting technology of compound sword can be called the technical peak of bronze age.
The technical mechanism of bronze composite sword is that the middle ridge and the body of the sword are made of bronze with different components, and the middle ridge has low tin content, strong toughness and is not easy to break, while the body has high tin content and high hardness, and the blade is particularly sharp, which improves the lethality in wartime.
Therefore, the compound sword is not only soft inside and rigid outside, but also sharper than the ordinary copper sword and not easy to break. Its length can reach 75 cm, which is 10~20 cm longer than the ordinary bronze sword in the Warring States period, and the war radius is increased.
The Han dynasty also applied the composite technology of bronze soldiers to the production of iron soldiers, forming the buried steel technology of Baotou steel in later generations and spreading it to Japan. Composite structure has become a magic weapon for Japanese knives to stand out from the world.
The casting method of composite sword is very different from that of ordinary copper 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.
The whole sword is made of composite copper, and the blade and ridge are precisely cast by mortise and tenon embedding casting, which embodies the leading and advanced technical ideas of bronze alloy technology and casting technology in ancient China. The composite sword creatively uses the superb technology of bronze alloy composition matching method, which shows that ancient craftsmen have reached a very high level in controlling the composition matching of bronze sword, and it is the crystallization of ancient wisdom.
Because the ridge and blade of the compound sword are made of different proportions of bronze, it can be seen that the colors of the ridge and blade are obviously different due to the different materials, so some people call it "two-color sword" or "bronze inlaid sword". The exquisite casting skills of the ancients are amazing! Composite swords obtained from archaeological excavations in the cultural and cultural circles began to appear in the early 1950s, mostly in the south, especially in Hunan.
195 1~ 1952, 73 tombs of the warring States period were unearthed in Changsha, Hunan. Among the unearthed objects, there are 22 bronze swords, two of which are compound swords with a total length of 56.5 cm and 57.2 cm respectively. From 1952 to 1994, 2048 Chu tombs were excavated in the suburbs of Changsha, and 508 bronze swords were unearthed, including 27 composite swords, the longest being 75.6 cm and the shortest being only 37.9 cm.
During 1956, 44 tombs of the Warring States period were cleared in Changde, Henan Province, and 5 bronze swords were unearthed, including a composite sword with a total length of 62 cm. 197 1 year, four bronze swords were unearthed in Gongcheng County, Guangxi, of which 1 is a composite sword with a residual length of 17.4 cm. 1972, a composite sword with a residual length of 58 cm was unearthed in Taihu Lake, Jiapu Township, Changxing County, Duanjiang.
1978, 80 tombs of the Warring States period were excavated in Zixing Old Town, Hubei Province, and 33 bronze swords were unearthed, including 7 composite swords, with a total length of 49-74 cm. 1978, a pottery urn for destroying soldiers was unearthed in Yanjiba village, Sun Yicheng county, which contained weapon fragments weighing about 30 kilograms, including four compound swords. 1980, unearthed from Meng He's tomb in Wujin, Jiangsu Province 1 bronze composite sword, with a total length of 35cm. 1987, three Chu swords were unearthed in Shan County, Hunan Province, one of which was a compound sword, with a length of more than 60 cm.
Up to now, the proportion of composite swords in bronze swords unearthed in archaeology is relatively rare, which may be related to the complex manufacturing process of composite swords and other factors. Among them, the most famous bronze composite swords in the Warring States Period are Zhou Sentence Composite Sword by Gong Qinlong of Taiwan Province Province, Gu Jian of Hainan Provincial Museum and the sword of the Palace Museum.
The blade and ridge are tightly embedded, sharp and bright, showing a fairly high level of ancient sword-making skills. In addition to concentric circles, turquoise inlays, gold and silver interlaces, diamond patterns and inscriptions, collectors of ancient bronze swords often look for compound swords.