摘要 |
A headbox for stock suspension for a machine for forming a web from the stock suspension. The headbox having an outlet duct formed by a relatively stationary duct wall below and a relatively movable duct wall above. The duct walls converge in the direction of suspension flow to form an outlet slot. The upper duct wall is pivoted at its upstream end to enable adjustment of the clear width, i.e. the inter-wall spacing of the outlet slot. A beam extends across the machine above the movable duct wall. A pressurizable back pressure cushion is disposed between the beam and the movable duct wall. The pressure of the cushion is adjustable for maintaining the desired pressure level exerted by the movable wall on the stock suspension in the outlet slot. A lifting appliance is connected with the beam, but not with the movable duct wall, for adjusting the height position of the beam, which adjusts the width of the pressurized outlet slot. |