Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing toroidal work
Reexamination Certificate
1998-07-01
2001-03-20
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing toroidal work
C425S058100
Reexamination Certificate
active
06203748
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tire configuration control method, a holding apparatus for post cure inflation, and a post cure inflation apparatus.
2. Description of the Related Art
The uniformity characteristics of a tire are determined by a force variation in a radial direction of the tire (i.e., a weighing direction of the tire) (RFV: Radial Force Variation), a force variation in a lateral direction of the tire (LFV: Lateral Force Variation), and a force variation in a tangential direction of the tire (TFV: Tangential Force Variation). RFV, LFV, and TFV each having lower values are evaluated to be able to maintain superior uniformity characteristics. Further, since excessive force is generated at a circumferential portion which protrudes outwardly from the tire, RFV of uniformity characteristics is correlated with such ununiformity of size that may occur in the radial direction of the tire (RR: radial runout).
Conventionally, in order to correct uniformity characteristics of a tire by increasing RFV, the reducing of RR of the tire has been carried out.
In order to reduce RR of a tire, a method in which the aforementioned protruding portion of the tire is abraded is employed. As an apparatus for which this method has been applied, for example, a post cure inflation apparatus (i.e., a post cure inflator which is referred to as PCI, hereinafter) has been proposed in which the outer diameter of a tire is measured by a tire diameter sensor, and a portion having a larger outer diameter of the tire is abraded by an outer diameter buffing apparatus, during the steps after vulcanization (Post Cure Inflation which is referred to as PCI, hereinafter) in which a tire after vulcanization (post cure) is maintained constant so as to stabilize the configuration of the tire (Japanese Patent Application Laid-Open (JP-A) No. 3-153319).
Further, there is also provided a method in which uniformity characteristics can be improved not by abrading a tire but by deforming permanently a carcass reinforcing member of a tire after vulcanization at an ordinary temperature (Japanese Patent application Laid-open (JP-A) No. 6-507858). As an apparatus to which this method has been applied, an apparatus in which a tire product is previously tested for its uniformity characteristics, and a portion of the tire at which uniformity characteristics are needed to be controlled is specified, and a relatively high inflation pressure is applied to the tire for a predetermined period of time in a state in which this portion is restrained by a restraining ring. By this apparatus, the tire is inflated until it has the pressure which is equal to or greater than a recommended operational pressure of the tire, the portion of the carcass reinforcing member is pulled, and permanent elongation is thereby generated so that uniformity characteristics of the tire can be improved.
However, in the above-described method in which a tire is abraded, the appearance/the quality of the tire may deteriorate by abrasion. Further, there arises a problem in that dust is caused by abrade so that workshops may be polluted. Moreover, in the method in which a portion of the carcass reinforcing member is deformed permanently without abrading the tire, there may be a case in which the pressure needed for generating permanent deformation on a portion of the carcass reinforcing member is extremely large due to the type/the physical properties of the carcass reinforcing member(s). As a result, due to such excessive pressure, a tire may be broken.
SUMMARY OF THE INVENTION
In view of the aforementioned facts, it is an object of the present invention to provide a tire configuration control method, a holding apparatus for PCI, and a PCI apparatus by which uniformity characteristics of a tire can be improved more effectively without causing a damage to the appearance of the tire and without demolition of the tire.
The first aspect of the present invention is a tire configuration control method which controls the configuration of a tire after vulcanization, comprising: the steps of restraining at least a portion of the area which extends from the side surfaces of the tire whose internal portion is in a high temperature state after vulcanization; and carrying out post cure inflation in state in which the tire is restrained.
In accordance with the present invention, during PCI, a portion or the entire circumferential portion, of the tire, which extends from the side surfaces to the circumferential surface thereof is restrained, and the current configuration is maintained. The carcass cord member is disposed in a toroidal state between the bead portions so as to extend from the side surfaces to the circumferential surface thereof. During PCI, the length of the cord member between the bead portions is controlled by this restraint. Because the configuration of the tire in a radial direction thereof depends on the length of the cord member, the elongation of the cord member at the restrained portion of the tire is controlled and the length of the cord member is thereby controlled. Accordingly, the tire configuration after PCI can be controlled appropriately.
This arises from the physical properties of the carcass cord member which may vary as the temperature of the tire changes during PCI. As an example, the relationship between a heat shrinkage (contraction) percentage and a tensile test elongation, and the relationship between the tensile test elongation and the temperature, of a polyester cord are shown respectively in
FIG. 9A and 9B
. By controlling the internal pressure, the temperature, and the restraining time, of the tire, it is possible to change the physical properties of the cord from point A to point B in FIG.
9
. As shown in
FIG. 9B
, it should be understood from a standpoint that the heating temperature for a tire is changed by maintaining the internal pressure and the restraining time constant so that the tensile test elongation can be changed. Namely, it is possible to vary the length of the cord at an ordinary temperature by changing the physical properties of the tire from point A to point B in FIG.
9
A.
Because there is neither abrasion of the tire nor the application of a large amount of pressure into the tire, the tire configuration can be controlled more effectively without causing damage to the appearance of the tire and without the demolition of the tire so that uniformity characteristics of the tire can be corrected.
In the present invention, at least one of the restraining position, the restraining pressure, the restraining time, and the pushing amount at the restraining position of the tire are determined as restraining conditions on the basis of configuration characteristics of a tire before vulcanization or configuration characteristics of a tire after vulcanization.
If restraining conditions are determined on the basis of the aforementioned configuration characteristics of the tire, the manufacturing of another tire is not needed for determining the restraining conditions. Accordingly, it is possible to manufacture a tire whose configuration can be controlled more effectively.
The restraining position of the tire can correspond to the peak position of the measured RR.
If a tire is restrained at the peak position of the measured RR which is highly correlated to RR and RFV of a tire product, equalization of RR and RFV of the finished tire is thereby facilitated. RR may be measured in a tire before vulcanization, or may be measured in a tire product after vulcanization. In the case in which RR of a tire is measured before vulcanization it is possible to directly specify the restraining position of the tire, and the configuration of the tire can be controlled more reliably.
In the waveform resulted from the measuring of RR of the tire, because the position of the peak and the magnitude of the peak are expressed, the peak position of the waveform can be set as the restraining position, and the restraining pressure and the pushing amount can be specified from the magnitude
Bridgestone Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Vargot Mathieu D.
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