Copper wire workshop design and vacuum heat treatment

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The workshop design of a copper processing plant that uses copper and copper alloy ingots or wire billets as raw materials to produce copper wires by extrusion, rolling and drawing processes.

The specification range of copper wire is φ0.02~6mm for red copper, φ0.05~6 mm for brass and cupronickel wire, and φ0.03~6 mm for bronze wire; the most round wires and less special-shaped wires. The wires are delivered in a soft state or a different degree of hard state according to the requirements of use.

The design content of copper wire workshop mainly includes: process selection, equipment selection and workshop configuration.

Selection of process flow The production process of wire rod is to first perform hot processing to produce wire billet, and then to make wire rod by drawing or rolling and drawing.

There are four production methods of wire billet: hot rolling, extrusion, continuous casting and continuous casting and rolling.

(1) Hot rolling method. The billet is heated and rolled into a wire billet with a diameter of 7~12 mm by the pass rolling method. This method is used to produce brass, some bronze and alloy wire billets with high hot working temperature and high deformation resistance. (2) Extrusion method. The round ingot is heated and extruded into a wire billet of φ6.5~18mm. For the production of common brass and lead brass wire billets not suitable for hot rolling. (3 Continuous casting method. Used to produce φ8~20 mm oxygen-free copper, brass and tin phosphor bronze and lead brass wire billets that are not easy to hot work. (4) Continuous casting and rolling method. Used to produce φ6.35 Red copper wire billets of ~12 mm. Among them, hot-rolled and extruded wire billets are generally produced in copper tube and rod workshops, and continuous casting and continuous casting and rolling wire billets are provided by copper melting and casting workshops. Among the above four production methods, the latter two It has the advantages of short production process, heavy roll and low cost.

(2) The surface quality of the wire billet produced by the extrusion method and the continuous casting and rolling method is good, and it can be directly cold rolled or rough drawn; the wire billet produced by the continuous casting method and the hot rolling method has a processing rate of 30% after one pass. After stretching about %, it must be peeled off to remove casting defects such as ash inclusion, and then continue cold rolling or rough stretching. The wire billet is subjected to medium and fine drawing, annealing, pickling, and then drawing to the finished size and then annealing or quenching-aging treatment to obtain different physical and mechanical properties. When the annealing furnace or vacuum furnace with protective gas is used for annealing, the surface of the wire rod is not oxidized and can no longer be pickled.

Schematic diagram of copper and copper alloy wire production process flow

Equipment selection includes the selection of heating furnaces, billet hot rolling mills, extruders, wire drawing machines, wire cold rolling mills, annealing furnaces and pickling equipment.

Wire drawing machines are available in single vertical, single horizontal, multiple sliding and multiple non-sliding types. (1) Single vertical stretching machine. It is used for rough drawing and hardening of alloy wire rod or large diameter wire rod. (2) Single horizontal stretching machine. It is used to stretch the special-shaped wire of human cross-section. The diameter of the reel is φ650~1000 mm, and the stretching speed is 0.3~1.8 m/s. (3) Multiple sliding type stretching machine. Equipped with 5~25 drawing dies, used to draw various specifications of copper wire or medium and fine alloy wire, the drawing speed is 10~50 m/s, the billet coil weight is 2~4t, and the drawing wire diameter range is φ16~0.01mm. (4) Multiple times without sliding type stretching machine. There are three types of structure types: storage line type, straight type and looper type. Generally equipped with 2~10 drawing dies, the diameter of the reel is φ250~600 mm, which is used for rough drawing copper wire and thick and medium drawing various alloy wires. The wire diameter range is φ16~0.35 mm, and the drawing speed is 10~ 20m/s. Among them, the storage wire type is low in cost and is often used for drawing round wires; the straight type and looper type are often used for drawing medium and small cross-section special-shaped wires and round wires.

The wire rod cold rolling mill consists of an uncoiler, 3 to 12 serial stands and a coiler. The specification of the wire billet is φ8~20 mm, and the diameter after rolling is φ2~8mm. The total deformation of cold rolling is larger than that of stretching, which can reduce the number of annealing and low production cost. It is mainly used for cold rolling of alloy wire or red copper wire.

There are five types of annealing furnaces: water seal type, continuous type, bell type, vacuum furnace and contact annealing device. (1) Water-sealed annealing furnace. Water vapor protection annealing has low thermal efficiency. After annealing, the surface of the wire has oxidation color and water traces, which is used for intermediate annealing of red copper wire. (2) Tubular continuous annealing furnace. A single wire is continuously annealed under the protection of protective gas. The annealed wire has uniform performance and smooth surface. It is often used for annealing of finished and semi-finished products of high-quality medium and fine wires. (3) Bell annealing furnace. The coil is placed in an inner cover filled with protective gas, and forced to circulate with a fan. It is often used for finished annealing and intermediate annealing of alloy wires. (4) Vacuum annealing furnace. Used for annealing finished copper wire. (5) Contact annealing device. It is often combined with multiple drawing machines to make drawing-annealing continuous, and is often used in the production of red copper wires and some alloy wires.

The pickling equipment is composed of acid tank, cold and hot water washing tank, neutralization tank, drying box and tank side exhaust. During pickling, the coiled wire blanks are suspended and transported by chains or hoisted by cranes.

Workshop configuration The hot processing workshop for the production line billet must be separated from the cold processing workshop for cold rolling and drawing wire rods; the annealing and pickling equipment is generally arranged in a separate room. The wire drawing machines are arranged in the order of thick, medium and thin, and the same type of wire drawing machines are often configured with the same side of the incoming and outgoing wires. Die repair equipment and medium and fine wire drawing equipment can be configured in multi-storey workshops.

Equipment selection: RVA series vacuum heat treatment furnaces produced by SIMUWU are high-quality products for vacuum heat treatment of tooling and moulds. Good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum heat treatment process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum air quenching furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.