Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream header and a downstream slice lip. Each block and an adjacent block of a plurality of blocks defines therebetween a flow tube for the flow therethrough of the stock. An upstream ramp is defined by a first surface for generating an upstream vortex adjacent to the first surface. A downstream ramp is defined by a second surface for generating a downstream vortex adjacent to the second surface. Adjacent blocks also generate downstream vortices which rotate in opposite directions relative to each other within the flow tube so that impact of the upstream and downstream vortices on a flow consistency and a velocity uniformity of the stock is reduced.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream header and a downstream slice lip. Each block and an adjacent block of a plurality of blocks defines therebetween a flow tube for the flow therethrough of the stock. An upstream ramp is defined by a first surface for generating an upstream vortex adjacent to the first surface. A downstream ramp is defined by a second surface for generating a downstream vortex adjacent to the second surface. Adjacent blocks also generate downstream vortices which rotate in opposite directions relative to each other within the flow tube so that impact of the upstream and downstream vortices on a flow consistency and a velocity uniformity of the stock is reduced.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream location and a downstream slice lip. The apparatus includes a plurality of blocks which are anchored within the flow path between the upstream location and the slice lip. Each block and an adjacent block of the plurality of blocks define therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion having an upstream and a downstream end. The flow tube has a downstream portion having an upstream and a downstream extremity, the upstream extremity of the downstream portion extending from the downstream end of the upstream portion. The downstream portion of the flow tube has a volume which is greater than a further volume of the upstream portion of the flow tube such that when the stock flows from the upstream portion to the downstream portion of the flow tube, the stock is mixed within the downstream portion.

Abstract: A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage. The downstream end of the bore has a cross-sectional area which is less than a further cross-sectional area of the upstream extremity of the passage. Also, the downstream extremity of the passage has a cross-section of trapezoidal configuration.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream location and a downstream slice lip. The apparatus includes a plurality of blocks which are anchored within the flow path between the upstream location and the slice lip. Each block and an adjacent block of the plurality of blocks define therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion having an upstream and a downstream end. The flow tube has a downstream portion having an upstream and a downstream extremity, the upstream extremity of the downstream portion extending from the downstream end of the upstream portion. The downstream portion of the flow tube has a volume which is greater than a further volume of the upstream portion of the flow tube such that when the stock flows from the upstream portion to the downstream portion of the flow tube, the stock is mixed within the downstream portion.

Abstract: A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage. The downstream end of the bore has a cross-sectional area which is less than a further cross-sectional area of the upstream extremity of the passage. Also, the downstream extremity of the passage has a cross-section of trapezoidal configuration.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream location and a downstream slice lip. The apparatus includes a plurality of blocks which are anchored within the flow path between the upstream location and the slice lip. Each block and an adjacent block of the plurality of blocks define therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion having an upstream and a downstream end. The flow tube has a downstream portion having an upstream and a downstream extremity, the upstream extremity of the downstream portion extending from the downstream end of the upstream portion. The downstream portion of the flow tube has a volume which is greater than a further volume of the upstream portion of the flow tube such that when the stock flows from the upstream portion to the downstream portion of the flow tube, the stock is mixed within the downstream portion.

Abstract: A headbox apparatus for a papermaking machine is disclosed. The headbox apparatus defines a flow path for stock flowing between an upstream location and a downstream slice lip. The apparatus includes a plurality of blocks which are anchored within the flow path between the upstream location and the slice lip. Each block and an adjacent block of the plurality of blocks define therebetween a flow tube for the flow therethrough of the stock. The flow tube has an upstream portion having an upstream and a downstream end. The flow tube has a downstream portion having an upstream and a downstream extremity, the upstream extremity of the downstream portion extending from the downstream end of the upstream portion. The downstream portion of the flow tube has a volume which is greater than a further volume of the upstream portion of the flow tube such that when the stock flows from the upstream portion to the downstream portion of the flow tube, the stock is mixed within the downstream portion.