MANUFACTURE OF THERMOSET PRODUCTS

摘要

A method of manufacturing a sheet of friction material for an automobile brake shoe, and apparatus therefor, includes forming a plastic lining element of uncured or green thermosetting resin binder containing friction modifiers and reinforcements and curing the resin binder in a heat and pressure regime which cures the resin binder and produces a sheet of defined dimensions and whose major faces are not disrupted by gases evolved during the curing. The need for a closed mould and/or venting stops is avoided by a stabilising press (50) which includes a heated bed (52) between guide plates (56, 57) to receive such lining element in its green state. The guide plates are spaced slightly further apart than the width of a closure member (53) which is, having been preheated, brought down onto the lining element and pressed by a pneumatic ram (70), the loosely sliding closure member comprising a non-sealing closure of the press. The previously heated surface (52) of press bed and closure member (53) combine with the lightly ramped-up pressure to create setting-up of the surface resins and fix final dimensions; the ram position is then clamped to permit internal pressure growth as curing proceeds and gases are vented without disrupting the sealed major surfaces. After less than 1 minute the lining element sheet is sufficiently cured and dimensionally stable to be taken from the press and baked unconstrained to effect final cure.