Integral closed machine barrel, Nitrided steel, quenched and tempered, gas nitrided after processing;The sleeves of the bimetal bushing barrel can be divided into C-shaped sleeves and integral sleeves, which are wear-resistant; nickel-based alloys are resistant to corrosion and wear. There is also a water-cooled circulation channel in the cylinder wall of the closed-end machine cylinder, which is close to the ∞-shaped working cavity. It can achieve high-precision cylinder temperature control in conjunction with the casting electric heating tile (± 2 ℃)