DE2335602C3 - Headbox for paper machines - Google Patents

Description

45

The invention relates to a headbox for paper machines, with a machine-wide outlet channel, in which several distributor pipes one behind the other open in the direction of the machine width and which consists of several sections lying one behind the other in the machine direction, each in a Angle to each other are arranged.

Under "paper machines" in the context of the invention are not only machines for the production of Understand paper webs, but also other machines of this type, provided they are used for the production of Fiber webs can be used, for example, for the production of plastic fiber webs.

From DT-OS 21 29 717 a headbox for the production of fiber webs from a fiber suspension is far less dilution than is otherwise known. In this case, a so-called three-dimensional network structure created, from which the actual path is then formed. This means that those already known and as disadvantageous perceived fiber agglomerations deliberately used to form the fiber webs will.

In contrast, the object of the invention be solved to form the headbox so that significantly lower dilution ratios in the Fiber suspension can be applied and still fiber clumps within the headbox be avoided.

This object is achieved according to the invention in that the angle (α) between two successive Sections of the channel towards the exit end of the fiber suspension is larger, but between the penultimate and the last section of the outlet channel having the outlet end at most 170 °, and that of an upper part and a Converge lower part formed boundary walls of each outlet channel section.

At the surrounding points, Taylor vortices a very high microturbulence is achieved in the fiber suspension, as a result of the convergence and the resulting conditional increase in speed is retained until the exit end, so that even with relatively high fiber concentrations do not cause fiber agglomeration.

Although it is still known from US-PS 25 06 678, it becomes larger and larger in the course of the outlet channel Provide deflection angles, but there are considerable between the individual channel sections Cross-sectional enlargements in the form of vortex chambers, so that uncontrolled fiber flows, flow calming and lumps of fiber can arise, the latter from time to time from the current be caught and carried away. This significantly disrupts the formation of the path.

Appropriate refinements of the invention are contained in the subclaims.

An exemplary embodiment is shown in the drawing Invention shown, which is described below:

A fourdrinier wire 1 is guided over a breast roll 2. The Fourdrinier is a headbox 3 (nozzle headbox) assigned, which consists of a lower part 4 and an upper part 5, between which an outlet channel 6 is formed, which extends over the width of the machine. This outlet channel 6 is several juxtaposed ; | end distribution pipes, only one of which is shown. The outlet channel 6 has several successive sections 16, 26, 36,46,56 and 66, of which two adjacent each enclose an angle α with one another. This angle α is between the section 16 connected to the distribution pipes 7 and the section adjoining it 26 is the smallest and becomes larger and larger towards the end and lies between 70 and 170 °. The from sub or. Upper part 4 and 5 formed boundary walls of the outlet channel sections converge, whereby the cross-section of the individual section becomes smaller in the direction of flow. The output cross-section can be of the individual sections must be larger than the entry cross-section of the following section or at most equal to this, so that a cross-section reduction over the entire Auslaul'kanalllänge is achieved.

The lower part 4 of the headbox is fixed and at most for setting the suspension jet adjustable compared to the Fourdrinier. The upper part 5, on the other hand, is displaceable via a sliding surface 8 on the lower part stored, whereby the distance between these two parts and thus the width of the outlet channel

is adjustable.

It is also possible, as indicated by dash-dotted lines, to convert the upper part to one with reference to the lower part 4 to arrange stationary axis of rotation 9 pivotable.

The transition from an outlet channel section

the following is sharp-edged in the drawing formed, but both the outer and the inner edges can be rounded to Avoid fiber build-up.

1 sheet of drawings

Claims (6)

Patent claims: 1. Headbox for paper machines, with a machine-wide outlet channel into which several in In the direction of the machine width, one behind the other manifold pipes and that of several in the machine direction consecutive sections, each ir. an angle are arranged to each other, characterized in that the angle («) between two consecutive sections (16,26,36,46,56, 66) of the channel (6) towards the exit end of the fiber suspension is larger, but between the penultimate and the last section (56, 66) of the outlet channel having the outlet end (6) is at most 170 °, unu that formed by an upper part (5) and a lower part (4) Boundary walls (4, 5) of each outlet channel section converge. 2. Headbox according to claim 1, characterized in that the output cross section of an outlet channel section (16, 26, 36, 46, 56) equal to the entry cross section of the following section (26,36,46,56,66) is. 3. Headbox according to claim 1, characterized in that the output cross section of an outlet channel section (16, 26, 36, 46, 56) is larger than the inlet cross-section of the following Section (26,36,46,56,66). 4. Headbox according to one of the preceding claims, characterized in that the upper part (5) and the lower part (4) are mutually adjustable. 5. Headbox according to claim 4, characterized in that the lower part (4Ϊ and fixedly arranged the upper part (5) can be pivoted about a horizontal axis (9) facing away from the outlet end is arranged. 6. Headbox according to one of the preceding claims, characterized in that the transitions are rounded from a section of the outlet channel to the following section.