Bridgestone Corporation

Yukio Saegusa

Teruo Tanaka

Tomohiro Irie

Tetsuo Tsujimoto

Noriaki Kurabayashi

In a tire molding process, a mutual positional deviation or angular deviation between the axis of a carcass member and the axis of a bead core takes place in a produced tire when the bead core is set on the outer periphery of cylindrical carcass member. By the use of an estimation formula for estimating the primary harmonic component in the waveform of a radial force, an inverse waveform with the primary harmonic component inversed is found with respect to the measurement waveform of the produced tire or with respect to the treatment waveform with a numerical value treatment applied thereto. Thereafter, in producing a tire of the same size by the mold used for producing the preceding tire, the mutual positional deviation or angular deviation between the axis of the carcass member and the axis of the bead core found by a backward calculation from the estimation formula is changed to set the bead core on the carcass member.

Tire producing method and tire molding machine

In order to manufacture a radial tire, first, in an average waveform recording step, a waveform component of radial force variation (RFV) by a molding factor in each molding machine, and a waveform component of RFV by a vulcanization factor in each vulcanizer are respectively acquired and recorded in a computer. In a waveform synthesizing step, a radial run-out (RRO, that is, vibrations resulting from non-uniformity of a tire surface) waveform of a green tire is substituted by an RFV waveform component and is made to overlap with respective RFV waveform components of waveforms of a molding factor and a vulcanization factor, thereby obtaining an RFV composite waveform. In a selection step, a circumferential position on the green tire at which an amplitude of the RFV composite waveform becomes minimum, and the circumferential position in a vulcanization mold are selected. Further, in a vulcanization step, based on the selected circumferential positions, the green tire is disposed and vulcanized in the vulcanization mold. As a result, a radial tire of which RFV is sufficiently reduced can be obtained.

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Tokyo, Japan

Yukio Saegusa