EuroWire November 2019

Technical Article

analysed, which will lay a foundation for studying the deformation law of hot strip copper rod during hot strip rolling.

Liquidus temperature

1,083°C

Density (kg/m 3 )

8,960

ν

0.326

Friction coefficient

0.45

▲ ▲ Table 2 : Physical performance parameters of low-oxygen copper bar

4 Results and discussion 4.1 Effect of technological parameters on temperature field and flow field of copper billet In order to explore the influence of different temperatures on the temperature field and flow field of copper slab, the casting temperatures 1,110°C, 1,120°C, 1,130°C and 1,140°C were selected. the crystallisation zone increases with the increase of casting temperature, especially at the exit and entrance. Because of the latent heat of solidification in the crystallisation process of copper liquid, the temperature growth at the outlet is non-linear. Solidification position is closely related to casting temperature. When pouring temperature is at its lowest, the solidification point of the copper liquid will affect the fluidity and increase the friction force of the contact surface and the amount of gas escaping in the liquid, and the slab is more likely to produce surface defects. With the increase of casting temperature, the solidification point gradually approaches the exit of the crystallisation zone. Analysis of the influence of different superheat on the flow field in the crystallisation zone shows that increasing the casting temperature did not significantly change the flow distribution characteristics of the flow field in the The overall temperature of

▲ ▲ Figure 3 : Cloud maps of (a) temperature field and (b) flow field in crystallisation zone

3 Numerical simulation 3.1 Parameter selection Combined with the SCR3000 on-site process, simulation parameters are selected separately. The physical and chemical properties of copper determine its physical parameters in high temperature deformation, and solve the thermal physical properties of copper. The physical properties of bright hypoxic copper are shown in Table 2 . 3.2 Flow field simulation of temperature field in continuous casting Selection of process parameters: Casting temperature 1,120°C, casting speed 12.4m/min, casting angle 40°, wheel groove thickness 43mm. Numerical simulation based on the established mathematical mode, clouds of the temperature field and flow field in the crystallisation zone are shown in Figure 3 . As shown in Figure 3(a) , different colours represent different temperature ranges. The temperature distribution of the temperature field can be observed by the length of colour block interval. The temperature gradient exists in different decreasing speeds of temperature. The casting temperature is 1,120°C and outlet temperature of the crystallisation zone is 1,031°C.

It is in accordance with the temperature range of the exit position of the crystallisation zone measured in the production site, and shows that the simulation model is in line with the actual situation. Figure 3b , the flow field nephogram, conforms to the law of solidification and crystallisation of liquid copper in the mould. 3.3 Deformation simulation of copper rod in hot continuous rolling The field process data in Table 3 is collected and the numerical simulation model is established based on the theoretical mathematical model. The simulation results are shown in Figure 4 . In order to facilitate analysis and increase calculation speed, the hot strip mill is divided into four groups (1#+2#, 3#+4#+5#, 6#+7#+8#, 9#+10#). The stress, strain, temperature and damage of each pass of hot strip copper rod will be

▼ ▼ Figure 4 : Simulation of hot strip mill stand group rolling

▼ ▼ Table 3 : Technological parameters of SCR3000 continuous mill unit

1H

2V

3H

4V

5H

6V

7H

8V

9H 95 65

10V

A A

/mm 2 /mm 2

3,800 2,500

2,500 1,320 18.75

1,320

800 480

480 300 6.00 1.00 6.29

300 195 7.65 1.00 4.05

195 125 3.60 1.00 2.83

125

65

0

800

95

50.27

1

H /mm 11.50 G /mm 8.20

10.30

12.40

5.35 1.00 1.94

2.80 1.00 1.38

3.50 1.00 1.02

5.80

1.00

1.00 9.82

ƒ

71.69 0.329

36.27 0.650

15.72 1.023

r /m·s -1

1.664

2.658

4.075

6.411

8.468

12.514 16.441

v

* A

0 – into rolling area, A 1

– out rolling area, H – pass depth, G – roll gap, f – total transmission ratio, v r

– roll circumferential velocity

53

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November 2019