Page 59 - 《橡塑技术与装备》英文版2026年3期

THEORY AND RESEARCH

(Note: J=N·M, Pa=N/m Substitute the above unit and steel carbon content under different temperature conditions
2
formula) (Appendix 5)
(2) The heat required to heat nitrogen to the process Table 4 Material composition table
temperature (210 ℃): material C content Mn content Si content S content P content
Q235A ≤ 0.22% ≤ 1.4% ≤ 0.35% ≤ 0.050% ≤ 0.045%
Conditions: Specific heat capacity of nitrogen is 1,038 Q235B ≤ 0.20% ≤ 1.4% ≤ 0.35% ≤ 0.045% ≤ 0.045%
J/Kg·K, nitrogen mass is 4 kg, and nitrogen temperature ranges Q235C ≤ 0.17% ≤ 1.4% ≤ 0.35% ≤ 0.040% ≤ 0.040%
Q235D ≤ 0.17% ≤ 1.4% ≤ 0.35% ≤ 0.035% ≤ 0.035%
from 20 to 210℃ (converted to unit interval: 180+273=453K)
Calculation: Φ 内 =c·M·δ t =1 038×4×180·J/kg·k·kg·k=74 7 Table 5 Carbon content of steel under different
400 J≈747.4 kJ temperature conditions
Option 1: If nitrogen is directly heated inside the capsule, Temperature °C Carbon content of steel (%)
0.09 0.224 0.3 0.54 0.61
it is required to reach the process temperature within 40 s 100 0.465 0.465 0.469 0.473 0.477
200 0.477 0.477 0.482 0.482 0.486
(including the primary/secondary setting time). The power 300 0.494 0.498 0.502 0.507 0.511
consumption is calculated as follows: 400 0.515 0.515 0.515 0.523 0.523
500 0.532 0.532 0.536 0.536 0.54
747.4 kJ
P= ≈18.69 kW
40 s
Option 2: Preheat nitrogen outside the capsule, which can The calculation process for the heat required to maintain
reach the process temperature within 10 minutes. The power the hot plate at 180℃ is as follows:
demand is calculated as follows: Q=c·M·δ t =0.47×460×180( kJ . kg . ℃)=38 916 kJ
kg∙℃
Time T=10 min=600 s The preheating time is set to t=1.5 hours and 5400 s,
747.4 kJ
The power P= ≈1.25 kW The electric heating power required to meet the heat
600 s
2.2.2 Regarding the calculation of external demand of the hot plate is calculated as follows:
temperature for tire electric heating P= 38 916 kJ ≈7.2 kW
5 400 s
2.2.2.1 Regarding the calculation of external If the temperature drops by 2℃ (δ t ) during normal
temperature of the hot plate production, the rapid temperature rise calculation is as follows:
Hot plate structure plan: Currently, the thickness of the kJ
δ Q =c·M·δ t =0.47×460×2( . kg . ℃)=433 kJ
steam channel of the hot plate is 60 mm, while the thickness kg∙℃
can be reduced to 40 mm for the electrically heated hot plate, Heating time for 7.2Kw power: T 升 =δ Q /7.2=433/7.2=60 s
with the material being Q235A; 2.2.2.2 Regarding the calculation of external
The temperature of the hot plate needs to be maintained temperature of the mold sleeve
at 180℃, and the mass of the hot plate is 460 kg; According to the first law of thermodynamics,Q=c·M·δ t
Calculation basis: First Law of Thermodynamics, Q— heat (J), J
Q=c·M·δ t (the amount of heat absorbed or released by a c—specific heat capacity of the substance（ kg∙℃ ）,
substance due to temperature change) M—Mass (kg);
Q—heat (J), δ t—Temperature change, ℃
J Mold sleeve material: Q235A,
c—specific heat capacity of the substance（ ）;
kg∙℃ kJ
M—Mass (kg), δt- Temperature Change (℃) C Q235A =0.47 kg∙℃
The specific heat capacity of Q235A material is related to Upon checking the mold specification sheet, the mold
its carbon content. According to Tables 4 and 5, it is found to sleeve of the largest mold has a mass of approximately 400 kg;
kg If the material of the mold sleeve is the same as that of
be C Q235A =0.47 kg
kJ∙℃ the hot plate and its quality is comparable to that of the hot
Carbon steel material composition table (Appendix 4) plate, then:

Vol.52，2026 ·13·