Page 58 - 《橡塑技术与装备》英文版2026年3期

HINA R&P TECHNOLOGY AND EQUIPMENT

c—specific heat capacity of rubber, J/kg℃; The above calculation is under ideal conditions, and the
M —Mass (kg), 15 kg for 51-inch semi-steel tires actual problem to be solved is:
δ t—For the increased (decreased) temperature (℃), the Preheat to process temperature externally: upper and
specific heat capacity of rubber is: instantaneous value 1,700 J/ lower molds at 180℃ (heated by hot plate), pattern blocks
kg·℃, average value 1,275 J/kg·℃, (calculated based on the at 180℃ (heated by mold sleeve), maintaining a temperature
highest value), temperature range: from 0℃ to 210℃, then difference of ±2℃;
δ t =210℃. When the internally heated nitrogen enters the capsule, it
Q x =c . mδ t =1 700×15×210=5 355 000 J=5 355 kJ needs to quickly reach the process temperature of 210℃ within
Steam heat loss (excluding pipeline loss): 20 s;
7 599−5 355 After the secondary vulcanization, the temperature should
η= Φ−Φ x ×100%= =29.53%
Φ 7 599 be maintained at a process temperature of 210℃ for the first 5
2.2 Calculation of heat quantity for electric minutes;
heating in tire vulcanization Hot plate, mold sleeve, internal temperature nitrogen,
Electric heating is used to simulate the calculated heat
power required to reach temperature, and temperature control
for vulcanized tires, and the required heat distribution of the
module;
electric heating components is shown in figure 4.
2.2.1 Regarding the calculation of internal
temperature of tire electric heating
According to the maximum tire size for 51-inch
vulcanization: (see table 1 above)
Sulfurization internal pressure is 2.5MPa, and internal
temperature is 210℃ (converted to 210+273=483K), both
provided by nitrogen gas;
Equation of state for ideal gas: pV=nRT
p—pressure (Pa),
V—gas volume (m³),

1-Upper airbag; 2-Heat shield; 3-Outer insulation layer; 4-Tire mold; T—Temperature (K),
5-Capsule; 6-Tire The amount of substance (mol) of n-gas,
A: Steam inlet; B: Steam and water outlet R—Molar gas constant (J/(mol·K))
Figure 4 Cross-sectional view of the structure of the
electric heating component If the gas is an ideal gas with a mass of m and a molar
m
mass of M, andn= , its state equation can be expressed as:
M
In electromechanics, 1j=1w·s represents the energy m
PV=nRT= . RT calculation. The value of R in the formula is
released when a current of 1A flows through a resistor of 1Ω M
for 1 second; related to the units of the state parameters. In the International
System of Units (SI), R=8.314J/(mol . K).
Semi-steel tire curing time:
15 min=0.25 h=900 s According to the table, the molar mass of nitrogen is
Based on the high-value heat calculation of 7,599 kj from M=28 g/mol.
steam heating, (1) Mass of nitrogen gas inside the capsule
Formula: Power required for the green tire to reach the From: Ideal gas equation:
m
optimal vulcanization time: PV=nRT= . RT, we can derive: gas mass
M
7 599 kJ Pa . m gmol
.
3
P= =8.4 kW 6
900 s m= PVμ ( J )= 2.5×10 ×0.23×28 =
Preliminary estimation shows that it takes 8.4 kW to RT mol . k . K 8.314×483
vulcanize one tire. 4 009.3 g≈4 kg
·12· Vol.52，No.3