Plant for building tyres

Abstract

A plant for building tyres is described, with a shaping station having engagement devices for a carcass sleeve, shaping devices, an expandable toroidal forming drum, actuator and application devices, and an annular contrast element. The annular contrast element is positionable around the forming drum and the carcass sleeve in the shaping station.

1 . A plant for building tyres, including:
 a shaping station including engagement devices of a carcass sleeve;   shaping devices operating in the shaping station for shaping the carcass sleeve according to a toroidal configuration;   an expandable toroidal forming drum engageable in the shaping station in a radially inner position in the carcass sleeve;   actuator devices operating in the shaping station for radially expanding the forming drum inside the carcass sleeve;   at least one application device of additional components;   transfer devices configured for transferring the forming drum carrying said toroidally shaped carcass sleeve from the shaping station to said at least one application device of additional components,   at least one annular contrast element positionable around the forming drum and the carcass sleeve in the shaping station and carrying at least one radially inner surface operating against the carcass sleeve itself during the action of the actuator devices or of the shaping devices.   
     
     
         2 . The plant according to  claim 1 , wherein the annular contrast element has an inner diameter smaller than an outer diameter that would be taken by the carcass sleeve on the action of the actuator devices in the absence of the annular contrast element. 
     
     
         3 . The plant according to  claim 2 , wherein the annular contrast element has an inner diameter substantially equal to an outer diameter of the forming drum in an expanded condition, added to twice the thickness of a radially outer portion of the shaped carcass sleeve. 
     
     
         4 . The plant according to  claim 3 , wherein the forming drum in a first radially contracted operational condition has a maximum outer diameter smaller than a minimum inner diameter of the carcass sleeve. 
     
     
         5 . The plant according to  claim 4 , wherein the forming drum includes a central shaft and a plurality of sectors circumferentially distributed around the central shaft and movable from a first operational condition, in which said sectors are adjacent the central shaft, to a second operational condition in which said sectors are moved away from the central shaft. 
     
     
         6 . The plant according to  claim 5 , wherein said engagement devices include a pair of flange elements coaxially facing each other and operationally engageable with respective annular anchoring structures carried by respective axially opposite ends of the carcass sleeve. 
     
     
         7 . The plant according to  claim 6 , further including a carriage carrying one of said flange elements and movable towards the other flange element for switching the shaping station between a loading/unloading condition, in which the flange elements are mutually spaced by an extent greater than an axial dimension of the unshaped carcass sleeve and a working condition in which the flange elements are mutually spaced by an extent substantially corresponding to the axial dimension of the carcass sleeve. 
     
     
         8 . The plant according to  claim 7 , wherein in the loading/unloading condition, the flange elements are mutually spaced by an extent at least twice the axial dimension of the unshaped carcass sleeve. 
     
     
         9 . The plant according to  claim 8 , wherein said annular contrast element is radially movable to fit between the flange elements arranged in the loading/unloading condition. 
     
     
         10 . The plant according to  claim 8 , wherein the annular contrast element is movable coaxially to the forming drum, between a working position axially interposed between the flange elements, and a stand-by position laterally arranged with respect to said flange elements.