PRESSURE CONTROL FORMING SECTION

摘要

A method and apparatus are disclosed whereby the rate of drainage of the stock on a paper making machine can be controlled for the full length of an open surface forming section. A continuous sealed drainage box is used from adjacent the head box slice to the end of the forming section, within which the air pressure can be controlled. In the area adjacent the head box slice drainage is hindered by the use of a positive (above ambient atmospheric) pressure, whilst further along the forming section the pressure is decreased to a negative value (below ambient atmospheric). Improved paper formation and first pass retention are obtained.