Head box for cylinder molds having a flexible lid element

In a papermaking machine of the cylinder type having a rotatable cylinder mold upon which fiber stock is deposited for forming a continuous fibrous web, the combination therewith comprising head box means supported adjacent said cylinder mold and including a dispersion chamber housing defining an internal stock dispersion chamber, said housing having an inlet for introducing fibrous stock into said internal chamber and having an elongated outlet located to deposit fibrous stock under pressure from said chamber onto the peripheral surface of said cylinder mold, said head box means further including a unitary curved lid element having a leading edge pivotally connected to said housing adjacent said outlet and having a trailing edge extending downstream from said outlet such that said lid element is in concave spaced relation to said cylinder mold, adjustment means secured to said lid element at a position intermediate said leading and trailing edges and operable to adjust selectively the spaced relation of said lid element to said cylinder mold, said unitary lid element being sufficiently rigid to facilitate positioning of said lid element relative to said cylinder mold by said adjustment means to establish a pressurized stock formation area between said lid element and said cylinder mold but having a free cantilevered trailing edge portion spaced downstream from said adjustment means sufficient for predetermined flexing to vary the spatial relation of said cantilevered trailing edge portion to said cylinder mold in response to pressure changes within said stock dispersion chamber and to accommodate out-of-round cylinder molds, and at the same time maintain a substantially stable pressure within said pressurized stock formation area between said lid element and said cylinder mold from said outlet to said trailing edge of said lid element.