JP3376975B2 - A method and apparatus for forming a wet sheet for inspection of impurities and the like in pulp. - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is an invention relating to a method for measuring impurities such as contaminants mixed in a pulp raw material process by producing a wet sheet for inspection from a slurry pulp raw material, and measuring the impurities. It also includes an invention relating to an apparatus used for carrying out the method. Furthermore, the present invention can be applied to the measurement of the whiteness of pulp in addition to the measurement of impurities.

[0002]

2. Description of the Related Art Dust, pitch, and contaminants such as black residue and toner residue derived from recycled raw materials are easily mixed in pulp used for papermaking. These contaminants cause troubles in the paper manufacturing process, and if they are mixed in the product, the quality is deteriorated. Therefore, it is necessary to manage the contaminants in the raw material process. It is a conventional practice to periodically sample raw materials to prepare a hand-made sheet and measure the amount of contaminants present in the pulp slurry visually or by an offline measuring machine.

[0003] Conventionally, the method for producing a handmade sheet is formed on the assumption that the sedimentation of fibers does not hinder the formation of a sheet horizontally below the slurry sample container to produce a sheet of uniform thickness. It is usually done. The on-line measuring device for the raw material process previously developed by the applicants (Japanese Patent Laid-Open No. 7-200825) also forms a wet sheet horizontally downward on the transparent plate at the bottom of the tubular container, like a hand-made sheet. Is the way. Illumination light is applied to the wet sheet, and the image of the wet sheet is CCD by the reflected light method.
This is a method of measuring the amount of impurities by capturing the image in a camera and processing the image to measure the area of the impurities per unit area of the wet sheet. In this method, since the transparent plate, which is the image capturing target surface, has a sealed structure in which the transparent plate is integrated with the slurry capturing container, it is not easy to remove stains on the image capturing target surface.

[0004]

Although the dust measuring instrument for hand-made sheets has high measurement accuracy, it takes time and manpower to make hand-made sheets, and there is a time delay in management in the raw material process. May result in defective products. On the other hand, in the sheet-shaped online measuring instrument in the raw material process, it is limited to the pulp sheet formed by the drum type filter,
The surface condition of the sheet is coarse with respect to contaminants, and a satisfactory resolution cannot be obtained. An on-line measuring instrument for measuring a raw material in a slurry state must produce a fixed and constant raw material concentration and a flow rate at the time of measurement, and requires equipment and time for pretreatment of the measurement. In order to improve such drawbacks, a method and an apparatus capable of detecting impurities as a sample directly from a slurry-like raw material online at a high resolution (Japanese Patent Laid-Open No. 7-200825).
No.) has been developed and provided, the method of forming a wet sheet state that can be measured as an inspection target as it is from the slurry-like raw material is downward.

When making a handmade sheet, it is usual to form a sheet below the container to make a sheet of uniform thickness on the assumption that the sedimentation of fibers does not hinder the thickness. In the method of forming a wet sheet used in Japanese Patent Laid-Open No. 7-200825, a sheet having a uniform thickness can be obtained even if fiber settling occurs. Form a sheet. Therefore, the arrangement and adjustment method of the constituent devices are limited. Also, in the method of measuring the slurry by direct transmission or reflection, the container of the device is hermetically sealed, and the surface that directly contacts the slurry gradually accumulates dirt, which cannot be easily cleaned and requires measures such as calibration. The problem is that Therefore, it takes a long time to perform the measurement, and the measurement cannot be performed a sufficient number of times.If the content of contaminants exceeds the control value, the measurement results are immediately reflected in the pulp manufacturing process, and the countermeasures such as contaminant removal can be promptly taken. I hated that I couldn't do it.

The present invention is an invention of a method for forming a wet sheet as a sample directly from a slurry-like raw material and an apparatus for the method. INDUSTRIAL APPLICABILITY According to the present invention, a wet sheet can be formed that is stable for a long period of time, is online, and has a high resolution to detect impurities and the like. Another object of the present invention is to provide a method and apparatus for forming a wet sheet state at an arbitrary angle without giving directionality to the method.

[0007]

The main part of the apparatus of the present invention is, as shown in FIGS. 1 to 5, introduced with a transparent plate 11 held vertically or at a constant inclination angle, and a pulp slurry to be used for measurement, It is composed of a tubular container 3 that forms a wet sheet, and a CCD camera 41 that captures an image of the wet sheet M is used when measuring impurities and the like. A seal 10 is provided at the tip opening of the cylindrical container 3, and the cylindrical container 3 can be brought into close contact with the transparent plate 11 held vertically or at a constant inclination angle through the seal 10. The structure is held independently of the transparent plate 11 and movable in the vertical direction with respect to the transparent plate 11 so that it can be detached from the transparent plate 11 if necessary. Further, the cylindrical container 3 is provided with a slurry inlet 8 for introducing a pulp slurry, a slurry outlet 9 for discharging the pulp slurry after measurement, and a backwater inlet 6 for introducing water and a backwater inlet 6. A water outlet 7 is attached.

In order to form a wet sheet M for use in measuring impurities and the like according to the present invention, first, the tip opening of the cylindrical container 3 is brought into close contact with the transparent plate 11 to fill the inside with water, and then Then, the pulp slurry is introduced into the slurry receiving space S between the piston 4 in the cylindrical container and the transparent plate 11 that is in close contact with the container and is replaced with water. Then, the pulp slurry is dehydrated in a fluidized state immediately after the introduction of the pulp slurry to form flocs and concentrate.

In order to dehydrate the pulp slurry, a piston 4 which slides in the container is built in the cylindrical container 3 and the tip of the piston is composed of a mesh 5. The pulp slurry introduced into the slurry receiving space S is dehydrated and concentrated by moving the piston 4 toward the transparent plate 11, and the wet sheet M is formed between the mesh 5 and the transparent plate 11. In order to maintain a head larger than or equal to the head of pulp slurry in the space W on the rear side of the mesh 5 in the tubular container 3, that is, on the rod side of the piston 4, water is previously introduced from the backwater inlet 6 and filled with water. Keep it.

A seal 10 made of an elastic material such as rubber or resin is attached to the opening of the tip of the cylindrical container 3 so as to be in close contact with the transparent plate 11 and prevent the filling water and the pulp slurry from leaking. is doing. The amount of contamination is measured from the opposite side of the transparent plate 11 on which the wet sheet M is formed.
While illuminating with the illumination device 38, a CCD camera is photographed by a reflected light method with a CCD camera, and the image is subjected to image processing to calculate the number of contaminants and the amount of contaminants. As the amount of impurities, the area of impurities per unit area of the wet sheet is calculated by image processing. Similarly, when measuring the whiteness, it is possible to measure the whiteness of the wet sheet by a CCD camera and image-process the image.

When the measurement of foreign matters is completed, the piston 4
Is retracted from the transparent plate 11. When the piston 4 is retracted, backwater on the piston rod side passes through the mesh and flows into the slurry receiving space S, so that the wet sheet M attached to the transparent plate 11 is
It is peeled off from the mesh 5 as the backwater moves. Further, the pulp fibers attached to the mesh 5 are also separated from the mesh by the backwater. continue,
Cleaning water is introduced from the slurry inflow port 8 and the backwater inflow port 6, the wet sheet M after the measurement is dissolved in water to return to the original pulp slurry, and the pulp slurry is discharged from the slurry outflow port 9 and the inside of the cylindrical container is discharged. To wash.

When the measurement of the foreign matters on the sheet is repeated, the contact surface between the transparent plate 11 and the wet sheet M becomes soiled gradually. Therefore, if necessary, the cylindrical container 3 is removed from the transparent plate 11 after the measurement. The transparent plate 11 that is the image capturing surface is moved backward and is scraped off and washed by the portion in contact with the wet sheet M.
Always keeps clean. As described above, the measurement of impurities contained in the pulp has been described, but the characteristics such as the whiteness of the wet sheet have a correlation with the characteristics such as the whiteness of the paper manufactured from the raw pulp, and thus the wet sheet. By measuring or inspecting characteristics such as whiteness of the paper, the whiteness of the paper can be managed. For example, when measuring the whiteness of a wet sheet, the conventional method for measuring the whiteness of paper may be used, or the wet sheet is photographed with a CCD camera and the image is processed in the same manner as the measurement of impurities. It depends on the method.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The mesh 5 used in the present invention has a function of trapping fibers such as plastic wires, metal wires, and perforated plates and allowing the contained water to pass through. However, it is practically 80 to 200 mesh.

When the pressure of the drive cylinder 1 for driving the piston 4 having the mesh 5 attached thereto is sequentially increased with the progress of the piston 4 using a proportional control valve, the concentration of the slurry and the formation of flocs can be promoted smoothly. it can. As the concentration of the slurry progresses, the mesh 5 becomes clogged to increase the dehydration resistance. Therefore, if the pressure is constant over time, the concentration will proceed too much at first and the concentration will gradually decrease, so that the wet sheet M is uniformly formed. It tends to be difficult to be done. Therefore, if the pressure is gradually increased as the concentration proceeds using the electropneumatic proportional valve, the sheet surface in contact with the transparent plate 11 becomes more precise and smooth.

The concentration of the wet sheet M is 20% or more suitable for measuring impurities and the like, and the pressure for forming the wet sheet M of this concentration depends on the type and properties of the pulp slurry, but the sheet unit area is 0.3 to 0.6
About kg / cm ² is suitable. The minimum thickness of the wet sheet M capable of measuring impurities and brightness is about 2 mm, but this sheet thickness can be formed substantially even at a pulp concentration of 0.3 to 0.5%.

When the concentration range of the sampling slurry is large, or when there are a plurality of sampling points and the respective slurry concentrations are different, an appropriate sheet thickness is set to, for example, 3
The distance between the mesh 5 and the transparent plate 11 in FIG. 1, that is, the stroke position of the piston 4 is automatically changed according to the concentration of the sample slurry so that the range of 6 mm is reached, and the amount of the sample slurry to be introduced is changed. By increasing or decreasing, it is possible to form a stable wet sheet M. In this case, it is easier to change the stroke position of the piston 4 by driving the piston 4 with a hydraulic cylinder than with an air cylinder.

[0017]

The method for forming a wet sheet according to the present invention can be applied to a transparent container held vertically or at a certain angle in a state of fluidity after the pulp slurry is introduced into a cylindrical container held in close contact with the transparent plate. By immediately starting dehydration, forming flocs and concentrating, there is an effect that a pulp sheet does not settle and a wet sheet having a uniform sheet thickness and a dense surface state can be formed on a flat transparent plate. The surface of the vertically formed wet sheet has no fine irregularities and is a flat and smooth surface. In this state, the image of the surface of the wet sheet is captured by a CCD camera, and the measurement and inspection of impurities etc. is done manually. You can do it just like a sheet.

Since the transparent plate is vertically or at an angle and the cylindrical container is detachable from the transparent plate on which the wet sheet is formed, the wet sheet formed on the transparent plate is vertically or at an angle. Therefore, it can be easily removed from the transparent plate and returned to the slurry. Furthermore, by making the cylindrical container detachable from the transparent plate, the surface of the transparent plate can be cleaned after each measurement, and a calibration operation is required for a long period of time by keeping it clean at all times. Not. Therefore, the next measurement can be started immediately after the measurement.

By filling the cylindrical container with water and replacing the pulp slurry with water at the time of introduction, the pulp slurry is introduced without contact with air, and air bubbles accompanying the slurry are removed by substitution flow. Since it has a function of causing degassing from the mesh surface at the time of concentration, there are few bubbles on the surface of the wet sheet, and since it is dispersed and absorbed in the sheet due to compression of the wet sheet, the bubbles contained in the pulp slurry are foreign matters etc. There is almost no disturbance to the measurement of. Furthermore, by filling the cylindrical container with water and replacing the introduced pulp slurry with the filled water, it is possible to completely suppress the initial dehydration of the mesh when the slurry is introduced, and to form a wet sheet without clogging the mesh. It has the effect of facilitating dehydration by pressing the mesh.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to the present invention and a method of using the apparatus will be described with reference to the drawings. 1 to 5 are explanatory views of an embodiment in which a wet sheet M is vertically formed by the apparatus of the present invention. In FIG. 4, first, washing water is introduced from the slurry inlet 8 and the backwater inlet 6 and the washing water is sprayed from the shower nozzles 12 and 13, and the pulp slurry after the measurement is discharged, and the transparent plate 11 and the cylinder are discharged. The inside of the container and the mesh 5 are washed. Next, the drive cylinder 2 is operated to move the cylindrical container 3 to the tip seal 10
It is pressed against the transparent plate 11 via. Water is introduced from the backwater inlet 6 or the slurry introducing pipe 8 into the cylindrical container 3 to fill it, and the valves 20 and 21 are closed (FIG. 1).

Subsequently, the pulp slurry to be measured is introduced from a single or a plurality of line pipes (neither of which is shown) during the raw material manufacturing process or the paper manufacturing process, and the slurry is introduced from the slurry inlet 8 communicating with the cylindrical container 3 into a cylinder. It is taken into the slurry receiving space S in the mold container 3. At this time, the valve 23 is left open to replace the water previously filled in the cylindrical container 3 with the pulp slurry. When the replacement is completed, the slurry inflow valve 22 and the slurry outflow valve 23 are closed to enclose the pulp slurry in the slurry receiving space S (FIG. 2).

After the pulp slurry has been enclosed in the slurry receiving space S, the drive cylinder 1 is actuated, and the piston 4 having the mesh 5 attached thereto is attached to the transparent plate 11.
Slide in to Slurry receiving space S
The pulp slurry therein is dehydrated and concentrated while allowing water to pass through the mesh 5, and a wet sheet is formed on the transparent plate 11 (FIG. 3). It is essential that the drive cylinder 1 be operated promptly before the fibers of the pulp slurry start to settle or before the influence of settling occurs.

After the wet sheet is formed on the transparent plate 11, the wet sheet is illuminated by the illumination device 38 and the wet sheet M is photographed by the CCD camera 41 by the reflected light method. The captured image of the wet sheet M is analyzed by the image processing device. In the image of the wet sheet M taken, the pulp fibers are projected lightly and the impurities are projected darkly, and there is a clear difference in density. Therefore, by processing the image data with a method such as binarization, The number and area of impurities per unit area of the sheet are calculated.

When the above measurement is completed, the drive cylinder 2
The tubular container 3 is separated from the transparent plate 11 and retracted,
The wiper driving cylinder 15 slides the wiper 14 and sprays cleaning water from the shower nozzles 12 and 13 to clean the surface of the transparent plate 11, the seal 10 and the mesh 5. Further, the valve 20 and the slurry inflow valve 22 are opened to allow water to flow into the cylindrical container 3 to clean the inside of the cylindrical container 3 and the mesh 5. The wet sheet M and the cleaning water are collected by the collection tray 18 (FIG. 4).

The wiper 14 is slid on the transparent plate 11 after the wet sheet is formed to scrape off the residual foreign matter on the transparent plate 11, and the shower nozzles 12 and 13 clean the surface of the transparent plate 11. Foreign substances such as attached pulp fibers and foreign substances are removed and kept clean at all times. Therefore, it is almost unnecessary to calibrate the image capturing surface in order to prevent foreign matter remaining on the transparent plate 11 from being captured in the next measurement data. However, as a precaution, when calibrating, the cylindrical container 3 is detached from the transparent plate 11 and retracted so as to be several mm to several tens mm from the image capturing surface of the transparent plate 11.
The calibration white plate 16 is inserted into the remote position by the drive cylinder 17, the illumination light from the illumination device 38 is irradiated, and the image of the transparent plate 11 is captured by the CCD camera 41. Since the captured image is an image of the illumination light that is transmitted through the transparent plate 11 and dispersed / reflected by the calibration white plate 16, it is not affected by the water droplets remaining on the transparent plate 11 and can be used as calibration data. (Fig. 5).

The operation of the apparatus shown in FIGS. 1 to 4 is as follows.
In the order shown in the figure, operations such as water filling, pulp slurry introduction, pulp slurry dehydration concentration, wet sheet formation, measurement, wet sheet removal / transparent plate and container cleaning, and pulp slurry recovery are performed according to a certain program by a sequencer or the like. It can also be executed automatically.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus of the present invention and a method of using the apparatus.

FIG. 2 is an explanatory diagram of an apparatus of the present invention and a method of using the apparatus.

FIG. 3 is an explanatory diagram of an apparatus of the present invention and a method of using the apparatus.

FIG. 4 is an explanatory diagram of the device of the present invention and a method of using the device.

FIG. 5 is an explanatory diagram of a state in which a calibration white plate is set and calibrated in the present invention.

[Explanation of symbols]

1 drive cylinder 2 drive cylinder 3 cylindrical containers 4 pistons 5 mesh 6 Backwater inlet 7 Backwater outlet 8 Slurry inlet 9 Slurry outlet 10 seals 11 transparent plate 12 shower nozzle 13 shower nozzle 14 wiper 15 Wiper drive cylinder 16 White plate for calibration 17 Drive cylinder 18 Collection tray 19 Optical electronics box 20 valves 21 valves 22 Slurry inflow valve 23 Slurry outflow valve 38 Lighting device 40 lenses 41 CCD camera W Piston rod side space S slurry receiving space M wet sheet

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-200825 (JP, A) JP-A-6-43104 (JP, A) Fukuihei 4-71158 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01N 21/84-21/958 D21C 1/00-11/14

Claims (3)

(57) [Claims] 1. An apparatus for forming a wet sheet for inspecting foreign matters and the like from pulp slurry, which comprises: A transparent plate (1 that is held vertically or at a certain angle of inclination
1) and 2. 2. A cylindrical container (3) having an opening at its tip that is held in close contact with and detachable from the transparent plate (11); A seal (10) which is provided around the opening of the cylindrical container (3) and is in close contact with the transparent plate (11) to seal the opening.
And 4. 4. A mesh (5) capable of capturing pulp fibers is attached to the tip, and a piston (4) slidable in the cylindrical container (3) is provided, 5. The pulp slurry is introduced into the slurry receiving space (S) between the transparent plate (11) and the mesh (5) while the tubular container (3) is in close contact with the transparent plate (11), By sliding the piston (4) in the direction of the transparent plate (11), the pulp slurry is dehydrated by the mesh (5), and pulp fibers are deposited on the surface of the transparent plate (11) to form the wet sheet (M). Forming device. 2. A method for forming a wet sheet for inspecting foreign matters and the like from pulp slurry, wherein the apparatus according to claim 1 is used to bring a cylindrical container (3) into close contact with a transparent plate (11). In this state, the cylindrical container (3) was filled with water, and the pulp slurry was introduced into the slurry receiving space (S) between the transparent plate (11) and the mesh (5) to replace the water with the pulp slurry. Then, by sliding the piston (4) toward the transparent plate (11), the pulp slurry is dehydrated by the mesh (5), and pulp fibers are deposited on the surface of the transparent plate (11) to form a wet sheet. A method for forming a wet sheet, which comprises forming (M). 3. A transparent plate (11) to which a wet sheet adheres.
A wiper (14) for cleaning the surface of the shower head, and a shower nozzle (12) for spraying cleaning water from above or diagonally toward the transparent plate (11) surface and the mesh (5),
(13) is provided, after forming a wet sheet on the surface of the transparent plate (11), the piston (4) is retracted, and washing water is jetted from the shower nozzles (12) and (13) to wipe the wiper ( 14) the surface of the transparent plate (11) is cleaned with a mesh (5) and a seal (1).
0) is cleaned, the apparatus for forming a wet sheet (M) according to claim 1.