Patent GB-1508822-A (GB)
Title: X-ray inspection machines for pneumatic tyres
IPC: G01M17/03
Filed: 1975-03-25
Abstract: 1508822 Tyre inspection by radiography USS ENGS & CONSULTANTS Inc 25 March 1975 [28 March 1974] 12435/75 Heading H5R [Also in Division B7] An X-ray tyre inspection machine comprises at least one X-ray source, a plurality of fluorescent screens on which shadow pictures of an entire sector of a tyre are produced, at least one video camera for receiving the images of the shadow pictures and producing corresponding electronic images, electronic means for transferring the electronic images to a storage device so that a complete composite image of the tyre sector, with the parts in proper order and orientation, is produced in the device, and means for display of the composite image on the picture tube of a monitor. When the tyre is positioned at the inspection station of the illustrated machine, the beads are spread apart a distance proportional to the tyre width and an X-ray tube 62 is positioned co-planar with the midcircumferential plane of the tyre and adjacent or between the tyre beads. The tube is rotatable about its axis by a stepping motor 64 so that the beam can be directed independently through initially the upper bead and sidewall, secondly the tread and thirdly the lower bead and sidewall. Rotation of the tyre through a predetermined arc is effected by appropriate simultaneous rotation of spools 50, 51. X-ray images presented on three fluorescent screens are viewed by respective cameras which transmit the pictures to a monitor which shows the composite picture of a section of the tyre or, as illustrated, by a single camera 105 via mirrors. The image from central screen 101 passes via mirrors 107-110 to the camera and mirror 110 is rotatable between four positions by a geneva drive mechanism. In two of its positions the mirror 110 directs images on screens 102, 103 to the camera (intermediate adjustable mirrors 111, 112 for screen 102 are not shown), while in its fourth position no image is transmitted to the camera and rotation of the tyre is effected by spools 50, 51 to bring another sector into the path of X-ray beam. The three images for each sector of the tyre are stored in a storage tube and the composite image is presented as a still picture on a television monitor and continues to be displayed until the three images for the next tyre sector stored in a second storage tube are transferred to the monitor immediately prior to the tyre keeping advanced to bring the next sector to the inspection position. After the whole tyre has been inspected, the X- ray source, and bead spreader are retracted, and the spools are lowered to deposit the tyre on the rollers 52. A tyre is advanced by driven rollers 52 until photocell 71 beam is interrupted, when rollers stop, rollers 53 are removed from paths of swingable spools 51 which move the tyre until photocell 72 is not interrupted by the tyre. Simultaneously with stopping of spools 51, spools 50 are advanced. When the latter spools engage the tyre with a predetermined force, their advance is terminated, and vertical movement of flanges 55 commences to lift the tyre to a position in which its midcircumferential plane is at a preset location. (Motion of the spools 50 into engagement with the tyre is used to determine its section height. Accordingly, if the tyres are of the same aspect ratio, the extent of lift can be easily programmed. When the tyres are of different aspect ratios, the spools are each provided with an upper and a lower flange movable simultaneously towards and away from each other.) In a further embodiment similar to that illustrated a mirror (125) Figs. 8-10, not shown) common to all the image paths is not only rotated by a geneva drive but is also tilted in a yoke (126) by a cam and follower arrangement (128, 129) to accurately reflect images into the camera 105. In another similar embodiment the rotating mirror is replaced by appropriately angled mirrors each corresponding to a fluorescent screen and each reflecting its image onto a respective third of the light sensitive plate of the camera. The system may include more than two storage tubes e.g. four, and the composite images of successive tyre sectors, e.g. three, may be presented on the monitor simultaneously. If the tyres being tested have the same bead diameters, sensing of the section height by movement of spools 50 can be employed to automatically calculate the number of times the spools 50, 51 have to be driven to rotate the tyre through one revolution. Where the tyres have different bead diameters an additional automatic measurement is carried out (see U.S. Patent 3,758,723). Reference has been directed by the Comptroller to Specification 1,420,527.