First, drawing

1, wire drawing: metal rod under a certain tensile force, through a series of holes with gradually smaller apertures, resulting in a smaller section and increased length of plastic deformation process. Simply speaking, wire drawing is the stretching of metal wire under the same volume.

2. The mold that achieves metal deformation when drawing wire is called wire die or wire drawing die.

3. Four working areas of the wire drawing die and their functions:

(1) Lubrication area: lubricant stays here and is brought into the work area.

(2) Working area: The metal is deformed here, the diameter is reduced and the length is increased.

(3) Sizing area: so that the size of the drawn wire is accurate, the shape meets the requirements, the mold should have a certain life, not quickly wear, so that the diameter exceeds the tolerance.

⑷ Exit area: do not scratch the wire coming out of the sizing area. At the same time, it prevents the breaking of the line caused by the inverted line when the middle of the drawing machine stops.

4. Drawing mold should meet the requirements:

(1) The size, shape, mechanical properties and surface quality of the drawn wire should meet the standard requirements.

(2) Each deformation should be as large as possible, make full use of metal plasticity, improve production efficiency.

(3) There is no broken line and thinning phenomenon, that is, to ensure sufficient safety factor.

5. The role of drawing oil and temperature (concentration) control

(1) The main function of wire drawing oil is to lubricate and cool metal wires and molds during drawing; At the same time, the metal powder produced in the process of compression deformation of the metal wire is taken away. It can improve the surface quality of metal wire and prolong the service life of mold.

(2) Temperature control of wire drawing oil: the best working temperature of aluminum drawing is 40~50℃, the maximum is not more than 60℃; Copper pull < 40℃.

(3) Copper soap liquid concentration: 3~8% PH value 7.5~8.5

⑷ Copper cooling water concentration: 0.5~1%, the outlet temperature is not more than 55 ° C, the water temperature is not more than 33 ° C.

(5) Copper wire drawing oil is made of low viscosity mineral oil as base oil and a variety of additives. Its main ingredients are amide soap of natural oil, synthetic ester, surfactant, anti-rust agent, infiltrating agent, antioxidant, anti-mildew preservative, defoamer and other additives.

6. The main features of copper wire drawing oil are:

a, good lubrication performance, lubrication film strength, can reduce the wear of high-speed copper large drawing machine tire, wire drawing die;

b, low foam, good cooling effect, good oxidation resistance to copper, processed copper is not easy to oxidize;

c, good cleaning, can effectively prevent copper soap in the wire drawing die, drum, bearing, chassis bonding, prolong the life of wire drawing die, drum;

d, good stability, not easy to stink deterioration, long service cycle, can save costs;

e, safe and hygienic, non-toxic and odorless, no irritating effect on the skin, normal use of no adverse effects on the human body;

7. Main features of aluminum wire drawing oil:

Aluminum wire-drawing oil is prepared from oil lubricating fraction by solvent refining and clay treatment, and is prepared by adding many oil additives such as anti-oxygen, anti-rust, anti-wear, anti-foam and low temperature condensation reduction. The main features of aluminum wire drawing oil are:

a, good lubricity, can improve the surface finish of aluminum wire, reduce mold loss;

b, good stability, strong aging resistance, long service cycle, not easy to deteriorate and stink;

c, good oxidation stability, thermal stability, corrosion resistance and extreme pressure friction resistance;

d, safety and health, this product is non-toxic and odorless, no irritating effect on the skin, normal use of no adverse effects on the human body;

8. The biggest difference between copper and aluminum wire drawing oil

When copper wire drawing oil is used in actual wire drawing, a certain proportion of water is added to the stock solution of wire drawing oil for modulation, and its concentration should meet the requirements of our process regulations. The water content in aluminum wire drawing oil is strictly controlled, and the water content in aluminum wire drawing oil should be less than 0.2%.

Two, annealing

1. Purpose of annealing:

1), the plasticity of the cold work hardening is restored to the level before cold work in order to continue processing.

2) In order to restore the finished product to the mechanical and electrical properties before the wire drawing, the finished product is annealed.

3) In order to obtain high strength wire, hardening and aging should be carried out for aluminum-Mg-Si alloy wire.

4), for the finished aluminum wire, using the appropriate process, you can get a semi-hard wire between hard wire and flexible wire.

5), for the copper brush wire, annealing is carried out after the bunching and stranding is completed to eliminate the internal stress due to the bunching and stranding single wire, so that the finished product is soft and suitable.

6), for alloy products in places with higher temperatures or when the conductor itself heats up, in order to avoid changes in electrical properties during use, pre-annealed. This annealing temperature is slightly higher than the use temperature, and the annealing time is shorter.

2. The basic principle of annealing

After plastic deformation in cold working, the internal grain fragmentation, lattice distortion and residual internal stress of the metal are unstable, and it has a spontaneous tendency to change to the stable state. But at room temperature, the diffusion of atoms is weak and the change is difficult to carry out. So we go through the will

The deformed metal is heated to increase the kinetic energy of the atoms, which causes it to change in the shortest time to return the metal to the level before cold working.

3, the basic process of annealing

1), reply stage

2) Recrystallization

3) The stage of grain growth after recrystallization

Because the surface oxide of copper is loose, it can be continuously oxidized, so the copper wire must be annealed "bright", that is, it must be heated in a vacuum without oxygen, or heated in an environment full of inert gas. Common protective gases are:

1), inert gases - helium (He), neon (Ne), argon (Ar), xenon (Xe).

2), neutral gas - carbon dioxide (CO2) nitrogen (N2) or their mixture of gases, water vapor.

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