JPH0465594A - Detection of web break in papermaking drying machine and dryer canvas as used thereof - Google Patents

Abstract

PURPOSE:To accurately detect web break in a drying cylinder group free from oven draw, by receiving reflecting light from wet paper having different color from that of a canvas and detecting difference in light amount of reflecting light between paper passage and web break. CONSTITUTION:Color of wet paper 4 is different from that of a canvas 2, in paper passage, reflecting light from the wet paper is received by a web break detecting means 8 of reflecting light method and in web break, reflecting light from the canvas 2 is received to detect web break by difference in light amount between the cases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting paper breakage in a paper making dryer and a dryer canvas used therein.

[Conventional technology]

Conventionally, as a multi-tube paper dryer, as shown in Figure 3,
A plurality of drying cylinders (1)... are arranged in two stages, upper and lower, and upper and lower two canvases (2) (2) are placed on the upper and lower drying cylinders (1) (1) with guide rollers (3) (3). )・・
A two-canvas system has been generally used, in which the wet paper (4) is guided through the upper and lower drying cylinders (1) in a zigzag pattern in sequence.

In this type of paper dryer, if there is a paper break, the wet paper (4
) is the drying cylinder (1) (1) or guide roller (3)
(3) If it gets wrapped around the canvas, it may cause breakage or breakage (2) (2)
Since cutting of paper may occur, a means to detect paper breakage is installed.
When paper is cut, it is necessary to cut the wet paper (4) just before the drying cylinder group and stop the machine at the same time. Conventionally, the paper breakage detection means is as follows. ! In the case of the upper and lower two canvas method, when the wet paper (4) is transferred from the upper drying cylinder (1) to the lower drying cylinder (1) and vice versa, the canvas (2) (2) accompanies it. Since the wet paper (4) runs independently, this part, part number 2, which is usually called the dryer pocket, and the floodlight (5)
and a light receiver (6) are installed facing each other across the running path of the wet paper (4), and when the paper is passed through, the light beam from the emitter (5) is blocked by the wet paper (4) and the light receiver ( 6) is inoperative, and when the paper is cut, the light beam from the projector (5) is received by the light receiver (6), the wet paper (4) is cut just before the drying cylinder group, and the machine is stopped. That is, a paper breakage detection means using a transmitted light method is adopted.

[Intelligence B that the invention attempts to solve] In the case of the conventional two-canvas method, upper and lower, canvas (2) (
There are many open draw (free run) locations where the wet paper (4) runs independently without the accompanying part 2), so if the paper making speed is increased, the wet paper (4) runs at the open draw locations.
4) Fluttering occurs, resulting in problems such as frequent paper breaks.

As a measure to prevent the above fluttering, a drying cylinder (
1) A single-run or unoran system (see Figure 2) in which (1) is arranged in two upper and lower stages, and a single canvas (2) guides and runs the wet paper (4), or a drying cylinder (1).
are arranged in a single row, and wet paper (4) is attached by one canvas (2).
For example, the Berran method (trademark name of Heloit Co., Ltd., USA, see Figure 1) has been proposed, and it has become possible to make high-speed paper.

However, since all of the above methods consist of a group of drying cylinders without open draw, it is not possible to employ the conventional transmitted light method paper breakage detection means.

[Means to solve the problem]

One of the present invention is a paper breakage detection method in a group of drying cylinders without open draw of a multi-tube paper dryer, comprising:
The color of the wet paper and the canvas is different, and the light is emitted onto the wet paper running attached to the dryer canvas, and the reflected light is received, and the difference in the amount of reflected light between when the paper passes and when the paper is cut is detected. The system is designed to detect paper breaks.

Another aspect of the present invention is a dryer canvas used in the paper breakage detection method, in which the canvas is colored in a different color from the wet paper, and the color of the canvas is measured using a spectrophotometer. 380-780n of the spectral reflection curve
It is characterized by being colored with a reflectance of 40% or less at each wavelength in the a+ range.

In the present invention, canvas should be understood to include both woven canvas and felt.

[Effect]

The paper breakage detection method of the present invention distinguishes the colors of wet paper and canvas and uses a reflected light type paper breakage detection means. When paper is being processed, light reflected from the canvas is received, and paper breakage is detected based on the difference in the amount of light received. It is possible to accurately detect without being obstructed by the canvas and prevent damage to the machine.

Since the dryer canvas of the present invention is colored in a color that allows the paper breakage detection means to sufficiently reliably identify the color of the wet paper, paper breaks can be detected by the difference in the amount of reflected light between the paper passing and the paper breakage. It can be detected reliably.

〔Example〕

FIG. 1 is a schematic explanatory diagram of the first embodiment of the method of the present invention, in which (1) is a drying cylinder (2) is a canvas, (3) is a guide roller (4) is a wet paper, (7)
(8) indicates a paper breakage detection means using a reflected light method, and in this case, the drying cylinder (1) is
The drying cylinders are arranged in a single row, and each group is composed of a plurality of drying cylinders, and each group is supported in a drivable manner, and a sacsijin roller (7) is arranged between each of the drying cylinders (1) (1). The canvas (2) is connected to the drying cylinder (1) and the suction roller (7) constituting each group through guide rollers (3), independently for each group. An example in which the present invention is applied to the Berran method (trademark name of Heloit Co., Ltd., USA) in which the hooks are passed in an endless manner in close connection with the next group will be shown.

FIG. 2 is a schematic explanatory diagram of a second embodiment of the method of the present invention. In this case, a plurality of drying cylinders (1) are arranged in two rows, one above the other, and one canvas (2) The hangings are passed in a zigzag pattern to the upper and lower drying cylinders (1), and multiple groups are connected with this as one group, and each group has a canvas (
The present invention is applied to a single run system in which drying cylinders 2) are independently stretched in an endless manner and each drying cylinder (1) is driven.

The canvas (2) of both of the above types is colored in a different color from the wet paper (4), and when the color of the canvas (2) is measured using a spectrophotometer, the color of the canvas (2) is 380% of the spectral reflection curve.
It is colored with a reflectance of 40% or less at each wavelength in the range of ~780 nm (visible light range).

FIG. 4 shows spectral reflection curves of canvases of various colors, with wavelength plotted on the horizontal axis and reflectance plotted on the vertical axis. In Figure 4, (a) is a standard white board, (b) and (c)
shows the spectral reflection curves of a dark blue canvas, (d) a pale yellow canvas, (e) an orange canvas, (f) a light brown canvas, and (g) a black canvas.

Each of the above spectral reflection curves was measured using the following spectrophotometer and conditions according to JIS standards.

Color measurement: JIS Z 8722 d OSa
10W1O Hitachi Model 607 Color Analyzer Light source: Halogen lamp Standard light: C In the above spectral reflection curve, if the standard white board (a) is viewed as wet paper (reflectance is slightly lower), the difference in reflectance will vary depending on each wavelength. In contrast, the paper breakage detection means (8) having a sufficiently large size enables the paper breakage detection means (8) with any light source to detect paper breakage without malfunction. It would be safest to color the canvas in these colors.

The above difference in reflectance is such that the canvas is colored with a color that is below the boundary reflectance that can be safely distinguished from the reflectance of wet paper, taking into account the characteristics of the adopted paper break detection means (8). For example, if you use a color with a reflectance of 40% or less of each wavelength in the range of 380 to 780r+s+, which is the reflectance of wet paper,
First of all, it's probably safe.

The paper breakage detection means (8) uses a reflected light type in the present invention, and although FIGS. 1 and 2 show an integrated type of light emitter and receiver, these may be separated. It may be the body.

As shown in FIGS. 1 and 2, the reflected light type paper breakage detection means (8) is arranged to place a wet paper (4) at an appropriate position on the running path of the wet paper (4) attached to the canvas (2). ), and the installation is installed so that the light can be emitted toward the target and the reflected light can be received.
Paper breakage is detected by sensing the difference in the amount of reflected light between paper passing and paper breakage, the wet paper (4) is cut just before the drying cylinder group, and the machine operation is stopped. The number of the reflected light type paper breakage detecting means (8) to be installed is one in one paper dryer, one in each drying cylinder group, or an appropriate number.

〔Effect of the invention〕

According to the invention of claim 1, it is possible to accurately detect paper breakage in a multi-tube paper dryer consisting of a group of drying cylinders without open draw without being obstructed by the canvas, and to prevent damage to the machine. The present invention can be applied to a multi-tube paper dryer that is increasing in speed, and can reliably prevent damage to the machine due to paper breakage with a simple means.

According to the invention of claim 2, simply by coloring the canvas in a specific color relative to the wet paper, paper breakage can be detected reliably by the reflected light type paper breakage detection means, and damage to the machine due to malfunction can be prevented. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic illustration of a first embodiment of the method of the present invention, FIG. 2 is a schematic illustration of a second embodiment of the method of the present invention, and FIG. 4 shows spectral reflection curves of canvases of various colors. FIG. 3 shows an explanatory diagram of a paper breakage detection means in a conventional paper dryer. (1)--Drying cylinder (2)--Canvas,
(3)-1-guide roller, (4)-wet paper, (7
) - Suction roller, reflected light method paper break detection means. Patent applicant Mitsubishi Paper Mills Co., Ltd. Shikishima Canvas Co., Ltd. Agent Gangwon Province 5th 1st! ! 1

Claims (2)

[Claims] (1) A method for detecting paper breakage in a group of drying cylinders without open draw in a multi-tube paper dryer, in which the wet paper and the canvas are colored differently, and the paper is thrown onto the wet paper running attached to the dryer canvas. A method for detecting paper breakage in a paper making dryer, characterized in that paper breakage is detected by emitting light, receiving the reflected light, and detecting the difference in the amount of reflected light between paper passing and paper breakage. (2) In the dryer canvas used in the method according to claim 1, when the canvas is colored in a different color from the wet paper, and the color of the canvas is measured using a spectrophotometer, A dryer canvas characterized by being colored with a reflectance of 40% or less at each wavelength in the range of 380 to 780 nm on a reflection curve.