JPH0583674B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications This invention relates to a headbox for a paper machine.

Conventional technology In the paper industry, low-concentration pulp liquid, usually less than 1%, is jetted out from a head box in a two-dimensional jet and placed on a dewatering net to be dewatered from below, or it is squeezed between two dewatering nets. A paper layer is formed by dehydrating both sides, and the head box shown in Japanese Utility Model Application Publication No. 147296/1983 has been devised. As shown in FIG. 4, this headbox has upper and lower surfaces 21,
22, a plurality of protrusions 23 having a triangular cross section protruding in a direction perpendicular to the flow direction of the pulp liquid are provided facing each other in the flow direction, and the height of these protrusions 23 gradually decreases toward the downstream side. The dispersion section 25 is constructed in this way, and according to this headbox, the pulp liquid is dispersed to some extent by the protrusions 23 and is ejected from the outlet 24 in a stable state.

Problems to be Solved by the Invention However, in this type of head box, the flow of pulp liquid at the location where one protrusion 23 is formed is once expanded and then reduced at a constant slope. , its dispersion is insufficient. Further, since the boundary portion 26 from the enlarged portion to the reduced portion has an acute angle shape, unnecessary turbulence is generated, which causes a decrease in stability during jetting.

The present invention solves the above-mentioned problems, and aims to provide a headbox for a paper machine that can effectively disperse pulp flow while ejecting it in a sufficiently stable state.

Means for Solving the Problems In order to solve the above problems, the present invention provides an initial dispersion section that distributes the flow of pulp liquid almost uniformly, a rectification section provided downstream of this initial dispersion section, and a rectification section that distributes the flow of pulp liquid almost uniformly. A rapidly expanding channel that is provided downstream of the rectifying section and expands at an expanding angle of 90 degrees or more, a contracting channel that gradually narrows at a contracting angle smaller than the expanding angle, and a channel from the rapidly expanding channel to the contracting channel. It has a dispersion section in which a plurality of elements are formed in the flow direction of the pulp liquid, each consisting of an intermediate channel connecting the intermediate flow path with a curved section, and the size of each element in the dispersion section is adjusted from the upstream side to the downstream side. It was gradually made smaller.

Effect With the above configuration, in each element, in addition to the rapidly expanding channel and the contracting channel, an intermediate channel connecting the rapidly expanding channel and the contracting channel is provided, so that the pulp liquid in one element is After being dispersed in the rapidly expanding channel, the expanded pulp liquid is then dispersed at the boundary to the intermediate channel, and further dispersed at the boundary between the intermediate channel and the contracting channel, so that the pulp liquid are effectively separated. In addition, this intermediate channel smoothly connects the rapidly expanding channel to the contracting channel with a curved section, and the size of each element in the dispersion section is gradually reduced from the upstream side to the downstream side. As a result, unnecessary turbulence is not generated in each element, and the turbulence strength gradually weakens near the downstream end of the dispersion section while dispersing small flocs, and as a result, re-flocking of the fibers is prevented. A smooth jet of pulp liquid can be obtained.

Embodiment Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 is a longitudinal sectional front view of a paper machine headbox. A dispersion section 7 provided downstream of the channel 4 and consisting of an upper slice plate 5 and a lower slice plate 6; and upper and lower slice lips 8, 9 provided downstream of this dispersion section 7, that is, at the downstream end of the head box 1. The upper slice plate 5 and the upper slice lip 8 can be rotated via a hinge 10 provided above the boundary between the sulfur regulation channel 4 and the dispersion section 7. The dispersion section 7 includes a rapidly expanding flow path 11 that expands almost linearly at an expansion angle of 90 degrees or more, a contraction flow path 12 that gradually narrows almost linearly at a contraction angle smaller than the expansion angle, and the From rapidly expanding channel 11 to contracting channel 1
A plurality of elements 14 are formed in the flow direction of the pulp liquid, each consisting of an intermediate flow path 13 that smoothly connects the portion between the two in a substantially parallel manner with a curved portion at both ends and a straight portion in the center without a step. , this element 14
The size gradually decreases from upstream to downstream.

In the above structure, the pulp liquid that has flowed into the head box 1 is first roughly equalized in its flow rate in the initial dispersion section 3, its flow direction is also made uniform, and its concentration unevenness is reduced and made uniform. Then, in the rectifying section 4, the pulp liquids are once combined and then flow into the dispersing section 7. In this dispersion section 7,
Element 1 having a rapidly expanding channel 11 and a contracting channel 12
4 are formed in multiple directions in the flow direction of the pulp liquid, the rapidly expanding channel 11 has the effect of dispersing the fiber blocks due to strong turbulence, while the shrinking channel 12 has the effect of dispersing the fibers by re-frocking and turbulence. increase is suppressed. Then, the rapidly expanding channel 1
1 to the contraction passage 12, the pulp liquid flows between the boundary part from the rapidly expanding passage 11 to the intermediate passage 13 and from the intermediate passage 13 to the contraction passage 12. It is also dispersed at two locations: the border area between the two locations. In this manner, the pulp liquid is effectively dispersed, thereby promoting the dispersion of the fiber flocs. Further, in each element 14, the intermediate flow path 13
The rapidly expanding channel 11 and the contracting channel 12 are smoothly connected, and the size of each element 14 in the dispersion section 7 gradually decreases from the upstream side to the downstream side. In addition to not causing severe turbulence, the turbulence strength gradually weakens near the downstream end of the dispersion section 7 while dispersing small flocs, and as a result, a smooth pulp liquid is created while preventing the fibers from becoming reflocculated. A jet stream is obtained.

According to this head box 1, the hinge 1
Since the distance between the upper slice plate 5 and the lower slice plate 6 in the dispersion section 7 can be changed through the dispersion section 0, if the flow rate of pulp liquid to the head box 1 decreases due to changes in operating conditions, etc. Also, by narrowing the spacing, it is possible to compensate for the decrease in the dispersion effect of the fiber flocs.

FIG. 2 shows another embodiment, in which in each element 14, the shape of the rapidly expanding channel 11 is curved in a direction in which the rate of change gradually decreases from the upstream side to the downstream side, and the contracting channel 12 The shape is curved in a direction in which the rate of change gradually increases from the upstream side to the downstream side, and the part between the rapidly expanding channel 11 and the contracting channel 12 is smoothly curved as the intermediate channel 13. They are connected at the circumference. According to this, the gradient of the flow path changes gradually within the element 14, so that the pulp liquid is dispersed more effectively.

FIG. 3 shows still another embodiment, in which the downstream side of the rectifying section 4 and the pulp liquid passage 15 in the dispersion section 7 are formed into a plurality of passages (two passages in FIG. 3) vertically. According to the paper, thicker paper can be produced.

Effects of the Invention As described above, according to the present invention, in each element, flocs can be dispersed by the rapidly expanding channel that expands at a rapidly expanding angle of 90 degrees or more, while in the contracting channel, this contracting angle is Since it is smaller than the expansion angle of , it is possible to maintain the dispersion state.Furthermore, by providing an intermediate flow path that connects this rapidly expanding flow path to the contraction flow path, in addition to the conventional dividing effect, A dispersion effect also occurs at the boundary between both ends of the intermediate flow path,
The pulp liquid is effectively dispersed. In addition, this intermediate channel smoothly connects the rapidly expanding channel to the contracting channel with a curved section, and the size of each element in the dispersion section is gradually reduced from the upstream side to the downstream side. Therefore, a smooth jet of pulp liquid can be obtained while preventing fiber reflocking.

[Brief explanation of the drawing]

1 to 3 each show an embodiment of the present invention, FIG. 1 is a longitudinal sectional front view of a headbox according to one embodiment of the invention, FIG. 2 is a longitudinal sectional front view of a headbox according to another embodiment, FIG. 3 is a longitudinal sectional front view of a headbox according to yet another embodiment, and FIG. 4 is a longitudinal sectional front view of a conventional headbox. DESCRIPTION OF SYMBOLS 1... Head box, 3... Initial dispersion part, 4... Rectification part, 7... Dispersion part, 10... Hinge, 11... Rapid expansion channel, 12... Contraction channel, 13... Intermediate channel, 14...
element.

Claims (1)

[Claims] 1. An initial dispersion section that distributes the flow of pulp liquid almost uniformly, a rectification section provided downstream of this initial dispersion section, and a rapid expansion section provided downstream of this rectification section that spreads at an expansion angle of 90 degrees or more. The flow of the pulp liquid consists of a channel, a contracting channel that gradually narrows at a contracting angle smaller than the expanding angle, and an intermediate channel that connects the portion between the rapidly expanding channel and the contracting channel by a curved section. 1. A headbox for a paper machine, characterized in that the headbox has a plurality of dispersion sections formed in the direction, and each element in the dispersion section gradually decreases in size from an upstream side to a downstream side.