JPH1161673A - Head box for paper making machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate a basis weight in the width direction of a paper without affecting a orientation angle of fiber of a paper stock in a head box for a paper making machine. SOLUTION: This head box 10 for a paper making machine, having many pipes for introducing diluting water, arranged in parallel in the machine direction of a mixing room 13 has a pressure drop-imparting device 15 for narrowing an outlet side flow path 21 of a mixing room 13, a center line of each distribution path of a guiding device 12 arranged outside of the region of the narrowed flow path 21 formed by the pressure drop-imparting device 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a head box for a paper machine.

[0002]

2. Description of the Related Art Conventionally, a paper machine head box has a raw material introduction pipe and a guide device connected to the raw material introduction pipe and having a number of distribution passages arranged in parallel in the machine width direction. Equally distributed in the machine width direction. As a result, the pulp raw material supplied to the head box is allowed to flow out of the slicing opening whose opening is adjustable by the profile lip to the wire part via the raw material introduction pipe, the guide device, and the like.

In the prior art, when adjusting the basis weight in the width direction of paper, the opening degree of the slicing opening is adjusted in the machine width direction by bending and deforming the profile lip in the machine width direction, and the discharge flow rate of the stock is adjusted. Adjustments are made in the machine width direction.

[0004]

However, in the prior art, the profile lip is flexed and deformed in the machine width direction to change the opening degree of the slice opening so as to form an uneven shape in the machine width direction. The flow of the stock from the mouth forms a diagonal flow with respect to the papermaking advancing direction. For this reason, the orientation angle of the fibers of the product paper is disturbed, resulting in curls and other irregularities, which may cause operational troubles in a printing machine or the like.

An object of the present invention is to provide a head box for a paper machine without affecting the orientation angle of stock fibers.
The purpose is to adjust the basis weight in the width direction of the paper.

[0006]

According to the present invention, there is provided a guide device which is connected to a raw material introduction pipe and has a plurality of distribution passages arranged in parallel in the machine width direction. Having a mixing chamber connected to the device, and a number of dilution water introduction pipes arranged in parallel in the machine width direction of the mixing chamber,
In a paper machine headbox that evenly distributes stock in the machine width direction, a pressure loss applying device is provided to narrow the outlet flow path of the mixing chamber, and the center line of each distribution passage of the guide device is formed by the pressure loss applying device. It is arranged outside the area of the restricted flow path.

According to a second aspect of the present invention, in the first aspect of the present invention, the pressure loss applying device further includes a throttle adjusting device for expanding and contracting the area of the throttle channel. It is.

[0008]

According to the first aspect of the present invention, the following operations are provided. When trying to reduce the basis weight of a section with an excessive basis weight in the width direction of the paper, increase the amount of water supplied from the dilution water inlet pipe corresponding to the section to the mixing chamber and increase the stock density of the section. Dilute. Conversely, when attempting to increase the basis weight of a section having a basis weight that is too small in the width direction of the paper, reduce the amount of water supplied from the dilution water introduction pipe corresponding to the section to the mixing chamber, and reduce the amount of water for that section. Increase the stock density.

At this time, since the center line of each distribution passage provided in the machine width direction of the guide device is outside the region of the throttle passage formed by the pressure loss applying device, the raw material passing through each distribution passage is removed. A vortex is generated in the mixing chamber on the front side of the throttle channel without passing straight through the area of the throttle channel. Therefore, the dilution water supplied from each dilution water introduction pipe to each section in the machine width direction of the mixing chamber is:
At the front side of the throttle channel, it is well mixed with the above-mentioned vortex of the raw material to locally and sufficiently adjust the stock density of the section as described above. In this manner, the stock whose density has been locally and sufficiently adjusted in each section in the machine width direction of the mixing chamber is discharged from the slicing port to the wire part after passing through the squeezing flow path. Are made equal.

In the present invention, when the basis weight in the width direction of the paper is adjusted, the stock density is locally adjusted in the machine width direction, and the discharge flow rate of the stock from the slicing port is adjusted in the machine width direction (constant). It does not adjust). For this reason, the flow of the stock from the slicing port does not form an oblique flow with respect to the papermaking advance direction, and the basis weight in the width direction of the paper can be adjusted without impairing the orientation angle of the stock fibers.

According to the second aspect of the present invention, the following operations are provided. When the flow rate of the raw material is small, if the area of the throttle flow path formed by the pressure loss applying device is excessive, the raw material passing through each distribution passage passes straight through the area of the throttle flow path, Vortex cannot be created in the mixing chamber on the front side of In this case, the diluting water supplied from the diluting water introducing pipe is not mixed well with the raw material and is discharged from the slicing port as it is, resulting in a stripe defect on the product paper.

In the present invention, the area of the throttle flow path formed by the pressure loss applying device can be enlarged or reduced by the throttle adjusting device. Therefore, when the flow rate of the raw material is small, the area of the throttle flow path is reduced, and each of the distribution passages is reduced. The vortex is reliably generated in the mixing chamber on the front side of the throttle flow path without the raw material having passed through the area of the throttle flow path straight through. Consequently, no matter how the flow rate of the raw material changes, the dilution water supplied from each dilution water introduction pipe is mixed well with the vortex of the raw material that is more reliably generated as described above, and the stock concentration is sufficiently increased. The weight can be adjusted well, and the basis weight in the width direction of the paper can be equalized without causing streak-like defects in the paper due to the outflow of dilution water from the slicing opening. Thus, the present invention can be well adapted to a multi-type papermaking machine in which the change width of the raw material flow rate is large.

[0013]

FIG. 1 is a schematic view showing an example of a head box for a paper machine, FIG. 2 is a schematic view showing a modification of the head box for a paper machine, and FIG. 3 is a view taken along line III-III of FIG. FIG. 4 is an enlarged view of a main part of FIG.

As shown in FIGS. 1 and 3, the paper machine head box 10 includes a raw material introduction pipe 11, a guide device 12, a mixing chamber 13, a dilution water introduction pipe (white water introduction pipe) 14, a pressure loss applying device 15, After passing through the stock material dispersing device 16, it is caused to flow out from the slicing opening 18 whose opening is adjustable by the profile lip 17 to the wire part 19.

The guide device 12 is connected to the raw material introduction pipe 11, and has a number of distribution passages 12A arranged perpendicular to the flow direction of the raw material introduction pipe 11, and arranged in parallel in the machine width direction.

The mixing chamber 13 is connected to the guide device 12, and has a plurality of dilution water introduction pipes 14 arranged in respective sections in the machine width direction and arranged in parallel with each other, and open to the inner wall surface thereof. Each dilution water introduction pipe 14 includes a flow control valve 14A.

The pressure loss applying device 15 is provided in the mixing chamber 1.
Upper and lower throttle gates 15 for narrowing the outlet flow path 21 of the third from above and below
A, 15A. At this time, as shown in FIG.
The center line 12B (extended line) of each distribution passage 12A of the guide device 12 is arranged outside the area of the throttle passage 21 formed by the throttle gate 15A of the pressure loss applying device 15.

The pressure loss applying device 15 is configured to screw the throttle adjusting screw 15B into the throttle gate 15A, adjust the amount of protrusion of the throttle gate 15A into the throttle channel 21 by the throttle adjusting screw 15B, and Area (FIG. 4) can be enlarged or reduced.

The stock dispersing device 16 follows the mixing chamber 13, applies a pressure loss to the stock again, and disperses the stock in the machine width direction. The stock dispersion device 16 is expanded in a two-step shape from the inlet side to the outlet side.

The head box 10 shown in FIG. 1 is provided with a pulsation damping device for damping pulsation generated by a raw material pressure pump and a screen on a pipe for introducing a raw material into a raw material introduction pipe 11. However, the headbox 10 may include a pulsation damping device 22 as shown in FIG.

Therefore, the head box 10 operates as follows. (1) Detecting the basis weight distribution in the width direction of the product paper made from the stock supplied from the head box 10.

(2) Based on the detection result of the above (1), the basis weight of a section whose basis weight is larger than the standard value in the width direction of the paper is controlled to reduce the basis weight. The opening of the flow control valve 14A of the dilution water introduction pipe 14 is increased in order to increase the supply amount of dilution water such as white water and fresh water from the mixing chamber 14 to the mixing chamber 13 to reduce the stock concentration. On the other hand, in the case where the basis weight is smaller than the standard value in the width direction of the paper, the basis weight is controlled to increase, so that the water supply amount of the dilution water from the dilution water introduction pipe 14 corresponding to the section to the mixing chamber 13 is adjusted. The opening degree of the flow control valve 14A of the dilution water introduction pipe 14 is reduced in order to increase the stock concentration by reducing the density. The dilution water introduction pipes 14 in the section whose basis weight in the width direction of the paper is the standard value maintain the opening of the flow control valve 14A at the standard opening (for example, 50%).

(3) The raw material that has passed from the raw material introduction pipe 11 through the distribution passages 12A of the guide device 12 is supplied to the pressure loss applying device 15
Without passing straight through the throttle flow path 21 of the throttle flow path 21, and generates a vortex in the mixing chamber 13 on the front side of the throttle flow path 21. Therefore, in the above (2), the dilution water supplied from each dilution water introduction pipe 14 to each section of the mixing chamber 13 in the machine width direction is mixed well with the above-mentioned vortex of the raw material on the front side of the throttle channel 21. Then, the stock density of the relevant section is locally sufficiently improved and adjusted as described in (2) above.

(4) The stock whose density has been locally and sufficiently adjusted as described in (3) above in each section of the mixing chamber 13 in the machine width direction passes through the narrowing flow path 21 and then is fed to the stock dispersion apparatus. At 16, a pressure loss is applied again, dispersed in the machine width direction, discharged from the slicing port 18 to the wire part 19, and the basis weight of the paper in the width direction is equalized.

Therefore, according to the present embodiment, the following operations are provided. When adjusting the basis weight in the width direction of the paper, the stock density shall be locally adjusted in the machine width direction, and
It does not adjust (constant) the discharge flow rate from 8 in the machine width direction. For this reason, the flow of the stock from the slicing port 18 does not form an oblique flow with respect to the papermaking advance direction, and the basis weight in the width direction of the paper can be adjusted without impairing the orientation angle of the stock fibers.

When the flow rate of the raw material is small and the area of the throttle passage 21 formed by the pressure loss applying device 15 is too large, the raw material passing through each distribution passage 12A passes straight through the area of the throttle passage 21. As a result, a vortex cannot be generated in the mixing chamber 13 on the front side of the throttle channel 21. In this case, the diluting water supplied from the diluting water introducing pipe 14 is discharged from the slicing port 18 as it is without being mixed well with the raw material, resulting in a stripe defect on the product paper.

In the present invention, the area of the throttle passage 21 formed by the pressure loss applying device 15 can be expanded or reduced by the throttle adjusting screw 15B. Therefore, when the flow rate of the raw material is small, the area of the throttle passage 21 is reduced. The vortex is reliably generated in the mixing chamber 13 on the front side of the throttle flow path 21 without the raw material passing through each distribution passage 12A passing straight through the area of the throttle flow path 21. As a result, no matter how the flow rate of the raw material changes, the dilution water supplied from each dilution water introduction pipe 14 is mixed well with the vortex of the raw material that is more reliably generated as described above, and the stock density is sufficiently increased. In this case, the basis weight in the width direction of the paper can be equalized without causing streak defects in the paper due to the outflow of dilution water from the slicing port 18. Thus, the present invention can be well adapted to a multi-type papermaking machine in which the change width of the raw material flow rate is large.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed within a range not departing from the gist of the present invention. The present invention is also included in the present invention.

[0029]

As described above, according to the present invention, in the paper machine head box, the basis weight in the width direction of the paper can be adjusted without affecting the orientation angle of the stock fiber.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a head box for a paper machine.

FIG. 2 is a schematic view showing a modified example of a head box for a paper machine.

FIG. 3 is an arrow view along the line III-III in FIG. 1;

FIG. 4 is an enlarged view of a main part of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Head box 11 Raw material introduction pipe 12 Guide device 12A Distribution passage 13 Mixing chamber 14 Dilution water introduction pipe 15 Pressure loss giving device 15A Throttle gate 15B Throttle adjustment screw (throttle adjustment device) 21 Throttle flow path

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Sano 2-1-1 Mitoshima, Fuji City, Shizuoka Prefecture Inside Kobayashi Manufacturing Co., Ltd. (72) Inventor Ikuhiro Kato 2-1-1 Mitoshima, Fuji City, Shizuoka Prefecture, Ltd. Inside Kobayashi Works

Claims (2)

[Claims] 1. A raw material introduction pipe, a guide device connected to the raw material introduction tube and having a number of distribution passages arranged in parallel in the machine width direction, a mixing chamber connected to the guide device, and a mechanical width of the mixing chamber. A plurality of dilution water introduction pipes arranged in parallel in the direction, and in a paper machine head box for evenly distributing the stock in the machine width direction, a pressure loss applying device for narrowing the outlet flow path of the mixing chamber is provided, A head box for a paper machine, wherein a center line of each distribution passage of the guide device is arranged outside a region of a throttle channel formed by the pressure loss applying device. 2. The head box for a paper machine according to claim 1, wherein said pressure loss applying device includes a throttle adjusting device for expanding and contracting the area of the throttle channel.