FI117396B - Arrangement at the paper machine's inlet box - Google Patents

Description

117396

Arrangement in a paper machine headbox

The invention relates to an arrangement according to the preamble of claim 1 in a hydraulic headbox flow passage of a papermaking machine, whereby a pulp suspension is led into the headbox lip chamber and through its lip opening to a papermaking machine wire. width, plus the headbox cover with side walls and bottom 10.

The purpose of the arrangement used in the hydraulic headbox of a papermaking machine subject to the invention is to increase the stiffness of the headbox against the stresses and internal loads which are partially due to the pressure of the pulp suspension flowing through the headbox and its possible temperature variations.

It is a further object of the present invention to provide a flow arrangement in the headbox, whereby the distribution of the fiber suspension fed to the paper machine 20 is as uniform as possible * · * Ι / 'over the entire width of the headbox.

* «· •«

Many prior art hydraulic headboxes include, for example, various perforated plates in the flow passage to::::: try to provide a uniform fiber distribution in the pulp fed to the paper machine wire. However, these structures do not always give the headbox sufficient structural strength.

The object of the invention is to eliminate the above problem. The invention is characterized in that the headbox has a cover part with side walls and a tear-off connecting beam supporting the bottom part corresponding to the width of the headbox,! ···. and that a plurality of inlet conduits extending at least partially through the holes therein and a corresponding number of outlets are arranged at the connection beam: ·: · | and that the holes in the connecting beam have a diameter of 8-24 mm in the direction of flow, that each hole in the connecting beam is provided with outflow tubes of at least four and up to ten times the diameter of the outflow tube fitting end.

2,117,396

The invention will now be explained in more detail with reference to the accompanying drawing, in which

Fig. 1 is a schematic longitudinal section showing the main parts of the flow channel section of the headbox of the invention; and

Fig. 2 is a fragmentary sectional view of a flow pipe fitted upstream of a stator according to the invention.

The headstock 1, schematically illustrated in Figure 1, includes a cover structure 10 and a base member 4 which together with the longitudinal side walls of the headbox form a flow channel support structure. The headbox-wide flow channel support structure thus formed is rectangular in cross-section. The bottom portion 4 may extend in a continuous plane up to the lip opening 2a of the headbox. Instead, the direction of the lid portion 3 is pivoted downward at 3a to form a lip chamber 2 having a triangular longitudinal cross-section extending across the entire width of the headbox and terminating in the aforementioned lip opening 2a.

. . In the flow passage there is a connecting beam 5, which corresponds to the width of the headbox * between the cover structure 3 and the base part 4, e.g.

bolted connection connects said parts 3 and 4. These parts may advantageously be provided with grooves (not shown) for the connecting beam 5. For control of these grooves, the connecting beam 5 can be pulled transversely out of the headbox, for example, for replacement or maintenance. The grooves le-: T: The width must be greater than the thickness of the joint.

“The connecting beam 5 has a sufficient number of closest empirically selected • t · round holes 6 for the flow of fiber suspension through the beam 5. In Figure 1, these holes 6 are shown as straight, drilled through the junction. Alternatively, the holes may be machined cone shaped or • formed of at least two straight portions, the first of which is always smaller in the flow direction of the suspension ··· Λ. Depending on the type and consistency of the fiber suspension, the diameter of the holes 6 v in the upstream direction may be 8-24 mm, for example.

1, inlet flow tubes 7 for a fiber suspension, one corresponding to each hole 6 117396 3, are provided at the connection point 5. The pipes 7 may extend partially within the connecting beam, in which case their outer diameter must be smaller than the inside diameter of the corresponding hole 6 at the fitting joint.

On the opposite side of the connecting beam 5 relative to the inlet flow, a number of outlet pipes 8 corresponding to the number of tubes 7 are arranged which are rounded at their initial end connected to the connecting beam 5 and expanding rectangularly to form a flow channel. The tubes are connected to the beam 5 by some known fitting connection si-10 and can extend beyond the vertical plane of the connecting beam 8. The length of the outflow pipes 8 may preferably be about 6 times the diameter of their circular upstream end. The extreme values for this length are 4-10 times the diameter of the pipe fitting head.

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Fig. 2, which shows a partial cross-sectional view of the beginning of the headbox lip chamber 2a at the point indicated by the line R-R, shows how the flow tubes 8, when rectangular, are arranged relative to one another. It is essential that the vertical seams of the parallel pipe rows not-20 may be in the same position as the seams of the pipe rows above or below them. As a whole, the outflow pipeline thus formed: ... 2 fills the area corresponding to the 2 ends of the lip chamber.

* a: T: An advantage of the present invention is that a small diameter of inlet flow pipes can be passed through the connecting beam 5 before the larger diameter of the outflow pipes 8 is obtained. The invention achieves the highest possible rigidity of the headbox without affecting the internal flow of the headbox.

In addition, due to the rectangular design of the rear end of the outflow conduit 8 according to the invention, space loss before the lip chamber 2 is possible X ·. as small as possible so that the mass jet into the lip chamber 2 is as smooth as possible.

a a 4 117396

Some embodiments of the invention are disclosed in the specification. However, the invention is not limited to these special cases, but various aspects of the invention can be modified without departing from the scope of the invention.

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Claims (9)

117396 An arrangement in the flow passageway 5 of a hydraulic headbox (1) of a papermaking machine through which a pulp suspension is led to a mouthwash chamber (2) and through a lip opening (2a) to a papermaking wire comprising a fibrous pension feeding system from the pulp compartment suspension evenly over the entire width of the headbox, and furthermore, the headbox cover part (3) with side walls io and bottom parts (4), characterized in that the head box has a hole corresponding to the width of the headbox (1) and a plurality of inlet conduits (7) extending at least partially through the holes (6) therein, and a corresponding number of outflow conduits (8), and that a plurality of holes (5) in the interconnector beam (5) 6) a diameter of 8-24 mm in the direction of flow flow so that the holes in the connecting beam (5) on the side of the lip chamber (2) are provided with detachable pipes (8) of a length of not less than four and not more than ten times the length. . diameter of the fitting end of the outflow pipe (8). • · · ** 20 • «2 * v Headbox according to Claim 1, characterized in that the holes (6) have a smaller diameter in the upstream direction than in the outflow side. • · · • · »• * ·: T: 25 Headbox according to claim 1 or 2, characterized in that the holes (6) in the connecting beam (5) are circular and have a major part. conical. • · «• · · ··» »· • ♦ Headbox according to one of Claims 1 to 3, characterized in that the holes (6) in the connecting beam (5) extend stepwise in the flow ·· ♦ direction between the smallest and largest hole diameters. has at least one step and the portions of the holes are in the form of straight cylinders. • · Headbox according to Claim 1, characterized in that the holes (6) in the connecting beam (5) expand in the flow direction such that the diameter of the hole on the inlet flow pipe (7) is always smaller 117396 than the hole on the outlet pipe (8) form, Headstock according to Claim 5, characterized in that the end fitting of the end of the outflow pipe (8) in the connecting beam (5) is preferably at least 5 mm. The headstock according to claim 5, characterized in that the outflow pipes (8) fitted to the holes (6) of the headbox (1) connecting beam (5) are shaped such that their cross-sectional leading end extends substantially into a rectangle and 8) arranged adjacent to each other to form a flow passage the extent of which substantially corresponds to the upstream cross-section of the lip chamber (2). 15 The headstock according to any one of the preceding claims, characterized in that the diameter of the inlet flow pipes (7) fitted to the connecting beam (5) is up to 80% of the diameter of the outflow pipes (8). * 1 Headstock according to one of the preceding claims, characterized in that the headbox cover portions (3) and the bottom portions (4) can advantageously be machined with grooves for the connecting beam (5). »* ♦ 4 • · · ♦ ♦ ♦ ♦ ·« »I I I I I · · · · ♦ ♦ ♦ ♦ ♦ ♦ »» • · · • · 9 • · 117396