There are many methods for processing copper tubes used in radiators, but they can be broadly categorized into two types: hot processing and cold processing.
Methods such as extrusion to produce tube blanks and oblique rolling and piercing involve heating the tube blanks to temperatures far above the recrystallization temperature of copper for deformation processing, thereby obtaining the tube blanks. The tube blanks are then processed into tubes at room temperature using cold rolling and cold drawing methods. This traditional process has been in use for many years. The extrusion billet supply method remains the primary method in use today. This is a traditional method for producing copper tube billets. The production process involves melting electrolytic copper into solid ingots, heating them in a furnace to above 850°C, then feeding them into an extruder one by one to form tube blanks. These blanks are then cold-rolled or subjected to multiple passes of straight-line drawing to achieve the required tube blank specifications for disk drawing.
Extrusion is categorized into high extrusion ratio and low extrusion ratio. Both methods result in refined grain structure and excellent surface quality.
High extrusion ratio tube blanks have smaller dimensions and thinner walls, allowing them to be processed directly on continuous direct machines or disk stretching machines; low extrusion ratio extrusion uses large ingots to produce large-sized tube blanks, which are then extended via cold rolling machines. For ingots of the same dimensions, high extrusion ratio requires higher extrusion tonnage, and the wall thickness tolerance of the extruded tubes is significantly larger.
Currently, the most popular method in China is the continuous casting and rolling billet supply method, a new type of billet supply method that emerged in the 1990s. The production process involves cutting the horizontally cast hollow tube blanks to length, milling the surfaces, and then directly feeding them into a three-roll planetary tube rolling mill to produce small-diameter thin-walled copper tubes.
Since the three-roll tube rolling mill allows the rolled copper tubes to remain stationary, they can be easily coiled into spools online. Its advantages include a short production process, elimination of reheating and extrusion processes, and benefits in terms of energy savings, reduced equipment investment, and cost reduction.
Continuous casting and rolling can provide tube blanks weighing over 1,500 kilograms per spool, which is impossible to achieve with the extrusion method. Heavy-weight tube blanks create highly favorable conditions for subsequent stretching processes. From its initial stages to full-scale production, and from being able to produce only thick-walled tubes to becoming the primary blanking process for thin-walled tubes, the continuous casting and rolling production line has overcome numerous challenges, gained experience, and learned lessons. Through the efforts of relevant professionals in China, this process is gradually becoming more refined and mature.
The company has a cluster of leading copper processing production lines in China, including:
German imported precision copper tube production line (annual output of 30,000 tons)
Japanese technology copper foil rolling line (thinnest up to 6μm)
Fully automatic copper bar continuous extrusion line
Intelligent copper sheet and strip finishing mill unit
Digitalized control and management of the whole production process is realized through MES system, and the dimensional accuracy of the products can reach ±0.01mm.
