Method and apparatus for detecting defects in pneumatic tire
First Claim
1. A method of detecting internal defects formed within a pneumatic tire in a non-destructive manner comprising the steps of:
- rotating an inflatable pneumatic tire inflated with a predetermined internal presusre;
uriging at least one displacement sensor against an outer surface of said inflated pneumatic tire;
deriving from siad displacement sensor a first set of displacement signals S1n which represent displacements of the outer surface of tire at N measuring points on the outer surface of the tire along a circumference thereof when the displacement sensor is urged against the tire at a first pressure and a second set of displacement signals S2n which represent displacements of the outer surface of tire at said N measuring points when the displacement sensor is urged against the outer surface of the tire at a second pressure which is different from said first pressure;
deriving displacement differences Δ
Sn at the N measuring points on the tire from said first and second sets of displacement signals; and
determining the presence of a defect within the tire on the basis of an analysis of said displacement differences.
1 Assignment
0 Petitions
Accused Products
Abstract
Internal defects formed within a substrate tire for manufacturing a retreaded tire are detected in a non-destructive manner by rotating the inflated tire at a constant speed of 1 r.p.m. while a displacement sensor is urged against an outer surface of the tire at different pressures to derive first and second sets of displacement signals, deriving displacement differences between the first and second displacement signals at corresponding measuring points on the outer surface of the tire, deriving a minimum value of the displacement differences, calculating deviations between the displacement differences and the minimum value, deriving the maximum deviation, and by comparing the maximum deviation with a first threshold value. When the maximum deviation exceeds the first threshold value, it can be judged that the tire includes a local separation. Further an average of the displacement differences is derived and is compared with a second threshold value. When the average of the displacement differences exceeds the second threshold value, it is judged that the tire includes a circumferential separation or fatigue. Moreover, a standard deviation of the displacement differences is calculated and is compared with a third threshold value. When the standard deviation exceeds the third threshold value, it is judged that the tire has the circumferential separation or fatigue.
30 Citations
23 Claims
-
1. A method of detecting internal defects formed within a pneumatic tire in a non-destructive manner comprising the steps of:
-
rotating an inflatable pneumatic tire inflated with a predetermined internal presusre; uriging at least one displacement sensor against an outer surface of said inflated pneumatic tire; deriving from siad displacement sensor a first set of displacement signals S1n which represent displacements of the outer surface of tire at N measuring points on the outer surface of the tire along a circumference thereof when the displacement sensor is urged against the tire at a first pressure and a second set of displacement signals S2n which represent displacements of the outer surface of tire at said N measuring points when the displacement sensor is urged against the outer surface of the tire at a second pressure which is different from said first pressure; deriving displacement differences Δ
Sn at the N measuring points on the tire from said first and second sets of displacement signals; anddetermining the presence of a defect within the tire on the basis of an analysis of said displacement differences. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. An apparatus for detecting defects formed within pneumatic tires in a non-destructive manner comprising:
-
a supporting means for supporting a rotatable a pneumatic tire inflated with a predetermined internal pressure; a tire rotating means for rotating the inflated tire at a given speed; a position detecting means for generating a position signal representing N measuring points set along a circumference of an outer surface of the tire; a displacement detecting means for detecting displacements of an outer surface of the tire and including at least one displacement sensor and a pushing means for urging the displacement sensor against the outer surface of the tire at at least first and second pressures while the tire is rotated by said tire rotating means to derive first and second sets of displacement signals S1n and S2n at said N measuring points; a memory means for storing said first and second sets of displacement signals S1n and S2n supplied from said displacement detecting means in conjunction with said position signal; a calculating and processing means for calculating from the stored first and second sets of displacement signals S1n and S2n displacement differences Δ
Sn =|S1n -S2n | at said N measuring points; anda judging means for detecting an internal defect or defects within the tire on the basis of said displacement differences Δ
Sn. - View Dependent Claims (18, 19, 20, 21, 22, 23)
-
Specification