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.

15

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.

• »ft 1 ft» ft1 # »« «•« «• ft i •» • «• • *« ··· • · ·············································································· quiting a file. · «··· ♦ ♦ · ft · · • • 1 1 1 1 1 1 1 1

Claims (9)

1. Arrangement in the flow channel of a hydraulic inlet carriage (1) of a paper machine through which the pulp suspension is led into the lip chamber (2) of the inlet tray 5 and via its lip opening (2a) to the wire of the paper machine, which inlet saddles (1) are fed to the feed system. the stock which distributes the fiber suspension evenly over the entire cover width, and in addition the inlet drawer lid (3) with side walls and bottom part (4), characterized in that in the inlet drawer ίο there is a perforated connecting beam (5) corresponding to the inlet drawer (1) (3) with side walls and the bottom part (4), that a connection to the connecting beam (5) has been arranged a number of inflow pipes (7) and the corresponding number of frangular flow tubes (8) which at least partially reach through the heel (6) of the connecting beam, (6) in the direction of the feed has a diameter of 8-24 mm and that in each of the connecting beams (5) located on the side of the lip chamber (2) a is fitted into the flow-flow tube (8) whose length is at least four and at most ten times as large as the diameter of the flow-flow tube (8). An inlet carriage according to claim 1, characterized in that the heel (6) of the y: y; diameter in the direction of inflow is smaller than in the direction of outflow. The inlet drawer according to claim 1 or 2, characterized in that the tail (6) in the connecting beam (5) is round and tapered to its main parts. • <«* 25 An inlet drawer according to any one of claims 1-3, characterized in that the heel (6) in the connecting beam (5) in the flow direction extends gradually so that it is at least one step between the smallest and the largest neck diameter and that the tail divides to the shape. are straight cyindra. 30 • M The inlet drawer according to claim 1, characterized in that the heel (6) in the τ 'connecting beam (5) in the flow direction expands such that the diameter v: of the hole on the side of the supply pipe (7) is always smaller than the diameter. of the hole on the side of the frangular flow tube (8) regardless of the shape of the bore between them. 117396 6. An inlet carriage according to claim 5, characterized in that the depth of passage in the connecting bay (5) for the end of the cut-off flow tube (8) is preferably at least 5 mm. 7. An inlet seam according to claim 5, characterized in that the cut-off flow tubes (8) fitted in the heel (6) of the connecting beam (5) fitted to the inlet drawer (1) are designed so that their round ends extend to a substantially square shape and the said angular flow tubes (8) are placed side by side so as to form a flow channel whose circumference substantially corresponds to the cross-section of the entrance chamber of the lip chamber (2). An inlet carriage according to any of the preceding claims, characterized in that the diameter of the inflow pipes (7) fitted in the connection bay (5) is at most 80% of the diameter of the frangible flow pipes (8). 15 9. An inlet carriage according to any of the preceding claims, characterized in that the cap parts (3) and the bottom parts (4) of the inlet carriage can preferably be provided with machined recesses for the connecting bay (5). 20 • · * · • · · t · · · ♦ »• · • M *« • · · • «« * «· • • · ♦ · ·« «· •« I • · «• 1 1 • t • ♦ • »• ·· * *» ·:: «« «« * «• 1 9 • · # • ♦