Forming of a rolling lobe of an air spring

摘要

A tubular bellows preform(16) of roughly twice the length of the finished product is guided onto a sleeve-like curing bag(10). Compressed air introduced into the heated silicone curing bag inflates the latter and forces the bellows preform against the inner wall(18) of an outer tool(6). Preform length reduces as the preform is inflated. Clamps(12',14') in the ends of the curing bag are moved axially inwards during the inflation stage so that mechanical stress on the curing bag remains low. Vulcanization with the curing bag(10) is effected from inside without preinflation against the heated outer tool(6). On removal of the vulcanized twin rolling bellows(16) from the tool, the latter is divided in the center to give two equal sized rolling bellows. One clamp(12') may be guided by a piston rod(22) which passes through a second clamp(14') and is connected to a linear drive unit. The second clamp is connected via a further piston rod to a linear drive unit and both drive units are moved in opposite directions by a control system as a function of the vulcanization pressure to keep curing bag loading low. Air supply to the internal chamber(20) can be via a central bore in a piston rod connecting the clamps. An Independent claim is included for the process equipment which includes an outer tool(6) divided into upper(6a) and lower(6b) halves and a cylindrical curing bag(10). Both tool halves have a similar, roughly bottle shaped cavity(8a,8b). The center of the common cavity(8) is enlarged relative to the ends. The curing bag extends axially in the twin tool and is about the length of a twin rolling bellows to be vulcanized whose ends are held by axially movable clamps.