Page 27 - 《橡塑技术与装备》英文版2025年12月

NEW TECHNOLOGIES AND PRODUCTS

rolling resistance 4.2 Strength performance
The belt structure primarily refers to the number of ply The strength test was conducted in accordance with GB/
layers, cord angle, density, as well as the structure and type of T 4502—2023 "Laboratory Test Methods for Passenger Car
cords used. This design adopts a 2-ply belt structure: both 1# Tyres Capabilities". The test conditions were: inflation pressure
and 2# belt layers utilize 4×0.225UT steel cord, with a density of 220 kPa and a pressure head diameter of 19 mm. The results
of 79 EPD, a belt angle of 24°, and a tire safety multiple of 8.5 showed that the average failure energy of the tire reached 545 J
times. (touching the rim), meeting the national standard requirements
3.4 Bead and proving the excellent strength of the tire.
The design and strength of the tire bead directly 4.3 Bead unseating performance
determine whether the tire can work stably and safely with the The bead unseating performance test was conducted
rim. It bears the internal pressure, braking torque, centrifugal in accordance with the GB/T 4502—2023 "Laboratory Test
force, and interference force of the rim during tire operation. Methods for Passenger Car Tyres Capabilities" standard.
The bead wire adopts Φ1.30 mm bead wire, with a rubber The test conditions were as follows: inflation pressure of
covering diameter of 1.60 mm, arranged in a 4-5-4 hexagonal 220 kPa, and a horizontal distance of the pressure block
pattern, with a total of 13 pieces. The inner diameter of the P=318 mm. The test results indicated that the maximum bead
bead wire is designed to be 466.9 mm, with a safety factor of unseating resistance of the tire was 15586 J (already unseated),
9.0. The winding method uses a single bead wire, ensuring significantly exceeding the regulatory requirement of 11120 J,
uniform stress during winding to ensure sufficient rigidity and reaching 140% of the regulatory standard. The bead unseating
strength when the tire bead is fitted with the rim. The height performance is safe and reliable.
of the apex is 30 mm, which meets the design specification 4.4 Durability
requirements. The durability test was conducted in accordance with the
3.5 Molding and vulcanization process GB/T 4502—2023 standard titled "Laboratory Test Methods
3.5.1 Forming process for Passenger Car Tyres Capabilities". The test parameters were
Using a one-step building machine, the deformation and set as follows: inflation pressure at 220 kPa, test speed at 120
misalignment issues during component transfer are reduced. km/h, and rated load at 750 kg. After completing the 35.5-hour
The head diameter is 442 mm, and the building method is procedure specified by the national standard, the test continued
crown-side, ensuring precise fit of various components of the for four additional phases, with each phase lasting 8 hours.
tire body. The test concluded when the total operating time reached 67.5
3.5.2 Sulfurization process hours, with the actual cumulative driving time being 67 hours
Using a hydraulic curing press and employing a and 30 minutes.
conventional nitrogen curing process, the curing parameters After the test, the tire exhibited no visible damage,
are set as follows: external steam pressure (0.1±0.02) MPa, with its durability meeting 190% of the national standard
external temperature (178±2) ℃ , internal pressure (2.4±0.05) requirements, and demonstrating an excellent service life.
MPa, internal temperature (200±2) ℃ , and a curing time of 12 4.5 High-speed performance
minutes, ensuring sufficient tire curing and stable performance. The high-speed performance test was conducted in
accordance with GB/T 4502-2023 "Laboratory Test Methods
4 Finished product performance for Passenger Car Tyres Capabilities", and the test conditions
4.1 Outer edge dimensions are shown in Table 2.
Mount the finished tire on a standard rim and measure The results showed that the tire achieved a maximum test
under standard inflation pressure: the inflated outer diameter is speed of 290 km/h, and after continuous running for 1 hour,
668 mm, and the inflated section width is 236 mm, both within its appearance remained undamaged, with good high-speed
the design requirements and meeting the expected goals. performance, meeting the Y-grade speed standard requirements

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