WCA January 2020

By simulating the damage to copper rod and cross section in the continuous rolling process, the damage situation and damage distribution of copper rod in the continuous rolling process are obtained, which can accurately predict the damage location of copper rod in the hot rolling process and improve the quality of copper rod production. The damage of copper rod during hot rolling is mainly concentrated on the surface and some edges and corners, while the damage of the core is relatively small. The surface of copper rod is easily damaged during hot rolling. The small process fluctuation of the rolling mill will directly affect the surface quality of finished copper rod and reduce the mechanical properties of copper rod. 4.3 Optimising measures of hot strip rolling process Combining with the process characteristics of the SCR3000 continuous casting and rolling line and its analysis and simulation of key process parameters, and aiming at the speed and cooling process of continuous rolling mill, optimisation measures are put forward to solve the problem of high content of sticky copper and copper powder in the production line in order to improve the quality of copper rod. Because the calculation of stacking rate depends on the cross-sectional area of the rolled parts in each pass and there is no way to measure the cross-sectional area of each pass in the production site, the feasibility of matching the rotational speed of each stand motor based on stacking rate is poor. Therefore, a method of matching motor speed with elongation coefficient is proposed, and field debugging is carried out, as shown in Table 4 . According to Table 4 , the motor speed of 1 and 2 is adjusted to 1,549 rpm and 1,586 rpm, respectively, by matching the motor speed with the elongation coefficient, and the copper powder content of the finished copper rod is measured. The results show that the content of copper powder in copper rod decreases from 4.3 and 4.8mg/20mm to 3.9mg/20mm. The content of copper powder can be effectively reduced by optimising the speed of roll.

❍ ❍ (a) 2# Frame spraying device and structural diagram

❍ ❍ (b) Structural optimisa- tion of spraying device for 2# rack

In view of the serious phenomenon of copper sticking on the second roll in the field, the simulation analysis of hot rolling deformation shows that the roll has large deformation and surface damage, and rolling temperature has a great influence on it. The measures for optimising and reforming the spray cooling system are put forward ( Figure 5 ). Two nozzles were added to the inlet of the number two stand, the gap of roll was adjusted to 6.6mm and 0.5 was added to the spraying platform after optimisation. The surface of rolled copper rod and roll was observed. After optimisation, the imprint on the surface of copper rod disappeared completely, and the phenomenon of non-sticking copper on the roll surface was effectively solved. 5 Conclusions (1) The coupling model of temperature field and flow field in solidification of copper liquid in continuous casting crystallising cavity was established to reveal the forming law of copper billet in the casting cavity of SCR3000 continuous casting and continuous casting. Through the corresponding finite element numerical simulation analysis, the influence of casting temperature, casting speed and heat transfer coefficient on the temperature distribution, flow characteristics and freezing point location in the crystallisation zone is explored. ❍ ❍ Figure 5 : 2# Frame spraying device structural optimisation scheme

❍ ❍ Table 4 : Matching table for extension coefficient of stands of continuous rolling mill in SCR3000 production line

Production speed

Casting bar speed(m/s)

25.03 t/h Forward slip

0.216

v(m/s)

16.349

n(r/min) 1037

Motor speed(r/min)

Elongation coefficient

Roll speed(n)

Roll speed(v)

Frame

D/mm

Theoretical

Actual

Theoretical

Actual

1H 304.80 1.050 2V 304.80 1.055 3H 204.50 1.075 4V 204.50 1.094 5H 204.50 1.074 6V 204.50 1.080 7H 204.50 1.058 8V 204.50 1.060 9H 204.50 1.040 10V 204.50 1.047

1496 1508 1510 1566 1525 1529 1630 1496 1542 1476

1533 1583 1560 1611 1578 1580 1681 1538 1536 1404

21.38 43.64 99.26

0.331 0.644 1.027 1.688 2.717 4.176 6.501 8.523

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1.899 1.620 1.650 1.600 1.539 1.560 1.315 1.462 1.293

1.945 1.594 1.643 1.610 1.537 1.557 1.311 1.417 1.234

164.00 251.03 390.32 594.83 792.38

1114.66 12.073 1376.47 14.903

*D – Diameter of roll body, n – Rotational speed of crystallisation wheel, v – Copper rod conveying speed

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Wire & Cable ASIA – January/February 2020