GB872240A - Improvements in and relating to the re-treading of pneumatic tyres - Google Patents

Abstract

872,240. Cutting-machines. MICHELIN & CIE. Jan. 25, 1960 [Jan. 27, 1959], No. 2655/60. Class31(1). A machine for removing a worn tread together with the crown reinforcement of a pneumatic tyre comprises means for supporting the tyre and rotating it about its axis, a cutter having a blade mounted so that it can be made to penertate the tyre between the tread and the carcase, and means for setting the blade at an adjustable distance from the axis of the tyre, for displacing it parallel to that axis and for varying its angularity relative to that axis. The tyre 1, Fig. 4, is carried by discs 15, 16 mounted on the screw-threaded end of a rotatable shaft 13 having fixed thereto a platform 12 for supporting the tyre. A cutter 26 having a blade 31 is carried at the end of a screw-threaded rod 25 which is movable by means of a hand wheel 27 in the direction of arrow F2 relative to the bore of a carriage 22 which is displaceable in the direction of arrow F1 in a support 21 by means of a hand wheel 24 on a screw-threaded rod 23. The support 21 is fixed to an arm 19, Fig. 3, carried by a table 20 which can be moved as indicated by arrow F2, Fig. 5, by means of a hand wheel 37 on a screwthreaded rod 35. A slide 39 is displaceable along a table 20 in the direction of arrow F3, to vary the position of the arm 19 relative to the axis Z-Z of the tyre, by means of a hand wheel 41 on a screw-threaded rod 40. The arm 19 is fixed to a pivotally mounted plate 44, Fig. 5, which can be turned in the direction of arrow F4, to vary the angularity of the cutter axis Y-Y relative to the axis of the tyre, by means of a hand wheel 51 on a screw-threaded rod 50. In operation, the platform 12 is set in rotation and by operation of the hand wheels 41, 24, 27 and 51, the cutter blade 31 is brought close to the base of the crown reinforcement and at the angularly Y<SP>1</SP>-Y<SP>1</SP>, Fig. 4, relative to the axis of the tyre which approximately corresponds to the curved transverse contour of the tyre carcase. The blade 31 is then slowly lowered until it penetrates the tyre. As it does so, the stock of the cutter follows and, as shown in Fig. 9, forces the tread 6 and crown reinforcement 5 away from the carcase thus facilitating further penetration by the blade. As the penetration increases, the angularity of the cutter relative to the axis of the tyre is reduced to suit the transverse contour of the carcase. When the blade has been caused to penetrate as far as the medial plane X-X of the tyre, the cutter is lifted while its angularity is adjusted and the rotation of the platform 12 stopped. The tyre is then turned over so as to enable the other half of the tread and its reinforcement to be separated. The angularity of the cutter may be adjusted automatically, e.g. by means of a cam having a profile corresponding to that of the carcase. Specifications 628,060, 677,166, 698,915 and 808,824 are referred to.