Headbox having adjustable flow passages

Claim 1

A headbox for supplying a stock such as a generated liquid foam suspension of fibers or a high consistency paper making stock to a forming surface for forming a fibrous web comprising in combination: an elongate slice nozzle having an opening through which a stock is ejected for being deposited on a traveling forming surface; a slice chamber leading to the slice nozzle and having first and second slice flow passages converging toward said slice nozzle, and through which passages the stock flows to said slice nozzle; a movable block in said slice chamber having convergently related surfaces defining said flow passages on each side of the block between the block and complementary stationary chamber wall portions; each of said convergently related surfaces and complementary stationary chamber wall portions in each of said flow passages having complementary modulating step configuration cooperative to define a series of restrictions in each flow passage so that the stock flows in continuously changing directions through each of the flow passages for the continuous regeneration of foam or fine scale turbulence of high consistency stock; means for moving said block rectilinearly for increasing or decreasing the cross sectional flow area of each of said slice flow passages and said restrictions substantially equally for increasing or decreasing the flow volume therethrough; header chamber means connected to supply stock to said passages; and supply passage means extending from said header chamber means through said movable block and communicating with said flow passages upstream from said modulating step configuration.