IE33591B1 - Improvements in or relating to the manufacture of pneumatic tyres - Google Patents

Abstract

1284397 Moulding tyres DUNLOP HOLDINGS Ltd 16 Oct 1969 [17 Oct 1968] 49327/68 Heading B5A An uncured pneumatic tyre is inserted into a mould having a tread pattern moulding matrix and initially heated for a predetermined period to reduce the viscosity of at least part of the tread rubber whilst applying little or no pressure to the tyre interior, and then applying pressure to the tyre interior up to the full moulding pressure and continuing to heat at least the said part of the tread rubber so as to cause it gradually to flow into said matrix. The temperature of the tread rubber, the pressure of the tyre interior and/or the rate of increase of either may be varied according to a predetermined programme; such pressure and temperature values may be sensed continuously to detect any variation from the programme and any required correction applied. Alternatively the etread rubber temperature and/or rate of increase thereof is sensed and the pressure of the tyre interior and/or rate of increase thereof adjusted according to such sensing. The programming apparatus may include a cam-shaft with a cam controlling the said pressure and a second cam the said temperature; the former cam controls the operation of valves or pumps controlling pressurizing fluid flow and the latter cam the flow of current to an electric heater. Alternatively the said temperature control may include one or more thermocouples embedded in the mould matrix which produce voltages which are compared with voltages tapped from variable resistances associated with the aforementioned cams; an error voltage is amplified to adjust an associated valve or pump. [GB1284397A]