Headbox for a machine for producing a fibrous web

Abstract

A headbox for a machine for producing a fibrous web, in particular a paper, cardboard or tissue web from at least one fibrous stock suspension, includes a feeding device for feeding the at least one fibrous stock suspension; a perforated distribution pipe plate which is arranged immediately downstream from the feeding device in the flow direction of the at least one fibrous stock suspension and which includes a plurality of flow channels arranged in rows and columns; an intermediate channel which is arranged immediately downstream from the perforated distribution pipe plate in the flow direction of the at least one fibrous stock suspension and which extends in a width direction of the headbox and includes two walls, for example having the width of the machine; a turbulence generator which is arranged immediately downstream of the intermediate channel in the flow direction of the at least one fibrous stock suspension and which has a plurality of flow channels arranged in rows and columns; and a headbox nozzle which is arranged immediately downstream of turbulence generator in the flow direction of the at least one fibrous stock suspension and which has a nozzle gap. Feeding device, perforated distribution pipe plate and intermediate channel are arranged in a first alignment plane, and turbulence generator and headbox nozzle are arranged in a second alignment plane. The two alignment planes form an angle in the range of >90 and <180°, for example ≧100 and ≦170°, or ≧110 and ≦160°.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of PCT application No. PCT / EP2010 / 056135, entitled “HEADBOX FOR A MACHINE FOR PRODUCING A FIBROUS WEB”, filed May 6, 2010, which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a headbox for a machine for producing a fibrous web, a paper, cardboard or tissue web from at least one fibrous stock suspension, including a feeding device for feeding the at least one fibrous stock suspension; a perforated distribution pipe plate which is arranged immediately downstream from the feeding device in a flow direction of the at least one fibrous stock suspension and which includes a plurality of flow channels arranged in rows and columns; an intermediate channel which is arranged immediately downstream from the perforated distribution pipe plate in the flow direction of the at least one fibrous stock suspension and which extends in a width direc...

AI Technical Summary

Benefits of technology

[0012]The headbox according to the present invention allows realization of a technically simple and reliable dilution water system. Even with possibly locally greatly differing dilution water or respectively fluid volumes, a good volume flow consistency is achieved across the entire machine width and, due to the addition of the dilution water or respectively the fluid into the direct catchment area of the turbulence generator a narrow and sharply defined effective response in the fibrous web is produced. “Straying” of the partial stream of dilution water or respectively fluid can occur only to a very limited extent. Due to the targeted, locally stable and, for example controlled, metered addition of the dilution water or respectively the fluid and the intensive blending in the flow channels of the turbulence generator downstream from the metering zone, with separate guidance of the blended streams to the beginning of the headbox nozzle, the demands upon an optimum dilution water system are extensively, even completely met.

[0029]The inventive headbox is extremely well suited for utilization in a machine for the production of a fibrous material web, especially a paper or cardboard web. The fibrous material web produced in the machine with at least one inventive headbox possesses outstanding properties throughout, since among other advantages, control of its fiber orientation cross profile as well as its base weight cross profile is possible.

Problems solved by technology

All known dilution water systems by well-known manufacturers of machinery for the production of a fibrous web are systems which can only more or less effectively, or in other words only partially fulfill the demands for effective blending of fibrous stock suspension and dilution water, sufficient volume flow consistency, a small effective width and a small mapping offset.

Due to these missing parts the headbox is not usable during this period.

Moreover, retrofitting the removed headbox is very expensive and possibly also associated with technological risks.