JPH10311802A - Evaluating method for dispersibility of specific fiber in stirred powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating the dispersibility of a specific fiber in stirred powders, capable of properly evaluating the dispersibility of the specific fiber in the stirred powders in units of microregions and of determining with ease and high accuracy whether or not the stirred state of the stirred powders is permissible, without requiring skill, etc. SOLUTION: An image of a specific fiber in the cross-section image of stirred fiber-containing powders is extracted in accordance with a predetermined criterion (step 102), and Voronoi polygons are depicted on the extracted image of the specific fiber to calculate the area of each Voronoi polygon (step 103). Then the distribution, etc., of the areas of the Voronoi polygons are statistically processed to convert the dispersibility of the specific fiber in the cross-section image into a numerical value (step 104), to quantitatively evaluate the dispersibility of the specific fiber (step 105).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for easily and accurately determining the dispersibility of a specific fiber in an agitated mixture of a fiber-containing powder without requiring skill or the like.
The present invention relates to a method for evaluating the dispersibility of a specific fiber in a powder agitated product, which can easily and appropriately maintain and control the quality of a fiber-containing powder agitated product.

[0002]

2. Description of the Related Art For example, a disc brake pad of an automobile is prepared by first mixing various powdery components with a stirrer to form a mixture of friction material raw materials in which various components are dispersed well. The mixture of the friction material raw materials is put into a preforming mold and compression-molded, and then the preformed product is subjected to a thermoforming treatment at a predetermined pressure and temperature to form a predetermined friction material shape. By appropriately performing a post-heat treatment or a polishing treatment on the molded product, a friction material having a desired shape is manufactured.

[0003] Here, constituent components of the mixture of the friction material raw materials include a fiber material, a binder, and various additives. As the fiber material, generally, various heat insulating fiber materials made of metal fibers, inorganic fibers, organic fibers, or the like are used. In addition, a thermosetting resin powder such as a phenol resin is used as the binder. Various additives include, for example, friction modifiers, lubricants, and bulking agents for increasing mechanical strength.Ceramics and rubber dust are used as friction modifiers, graphite is used as a lubricant, and bulking agents are used. Fillers such as calcium carbonate and barium sulfate are used as the agent. In such a mixture of the friction material raw materials, the mixing ratio of the constituent components is adjusted according to the physical performance and the like required as the friction material.

[0004] As a method of stirring and mixing the components of the mixture of the friction material materials, a dry stirring and mixing method in which the components are stirred and mixed with a stirrer while the components are kept in a dry state has been conventionally used. 2. Description of the Related Art A wet-type stirring and mixing method in which the components are put into a stirrer in a state where they are appropriately moistened to perform a stirring and mixing process is widely used.

[0005] The stirring and mixing treatment of the mixture of the raw materials of the friction material, which is performed before the shaping treatment, makes the dispersion of each component uniform, more specifically, each fiber such as metal fiber, inorganic fiber or organic fiber in the component. The purpose of the present invention is to obtain a good dispersion state in which the other components are uniformly entangled with the material at a predetermined ratio. For example, in the mixture of the friction material raw materials, only a part of the components is entangled in a large amount exceeding a predetermined ratio with respect to the fiber material, or a segregation state in which the other components are separated from the fiber material occurs. In the process of molding the mixture of the friction material raw materials, inconveniences such as difficulty in releasing from the molding die may occur, or the produced pad may have a portion with a low friction coefficient or a portion having a reduced wear resistance. And the like, and the quality of the pad may be unstable.

[0006] Therefore, in order to stabilize the quality of the manufactured pad, it is necessary to control the stirring process so that a good dispersion state in which the other components are uniformly entangled with the fibrous material at a predetermined ratio can be obtained. Is essential. In order to maintain the stirring conditions optimally, the mixing ratio of the constituent components of the mixture of the friction material raw materials is changed, or the stirring process is changed from a small-scale trial to a large-scale one for mass production. When the scale up of the stirrer is to be performed for transfer, or when some of the components are changed, the quality of the stirrer is evaluated for the mixture of the friction material raw materials after the stirrer processing is completed. It is indispensable to correct the conditions of the stirring process (for example, the stirring time and the stirring speed) according to the result.

Heretofore, the agitation state of a fiber-containing powder such as the above-mentioned mixture of friction material raw materials has been evaluated for the agitation state (ie, the dispersibility of specific fibers in the agitated substance). As a method of performing, a method of measuring bulk density, a sieve measurement method of evaluating the passing rate and passing time of the sieve by passing the agitated material through a sieve with a dropping method and a low tap method, a method using glycerin, and the like have been attempted. I have.

[0008]

However, the conventional evaluation method described above can quantify the stirring state of the powder stirrer by the measured value, but in any case, the tendency of the stirring state of the whole stirrer can be determined. (Average value), it is not possible to detect the dispersibility of the fiber or the state of fibrillation (the state in which the fiber is loosened and easily entangled with other powders or fibers) in units of minute regions. That is, in the conventional evaluation method, the dispersibility and the like of the specific fiber can be evaluated only as an average tendency in the entire local maximum region. However, there is a problem that the agitated product may have poor quality and the reliability of evaluation is low.

For this reason, conventionally, a final evaluation is often obtained by adding a subjective evaluation of the operator such as visual appearance and touch to the above-described evaluation method, but the subjective evaluation of the operator is skilled. Was required.
The present invention has been made in view of the above circumstances, and it is possible to appropriately evaluate the dispersibility of a specific fiber in a minute area unit with respect to a stirrer of a powder containing a fiber such as the above-described mixture of the friction material raw materials. Provide a method for evaluating the dispersibility of a specific fiber in a powder agitated material, and determine whether the dispersibility of the specific fiber is good or not, without requiring skill, etc., easily and with high accuracy, and include a fiber. It is an object of the present invention to easily and appropriately maintain and control the quality of a powder agitated product.

[0010]

To achieve the above object, the method for evaluating the dispersibility of specific fibers in a powder agitated product according to the present invention comprises the steps of mixing and mixing various types of powdery and granular components with fibers. A cross-sectional image of the agitated body is photographed, and an image of a specific fiber in the photographed image is extracted based on a predetermined criterion based on characteristics of the fiber, and Voronoi is applied to the extracted image of the specific fiber. The polygons are drawn to calculate the area of each Voronoi polygon, and the distribution of the area of each Voronoi polygon is statistically processed to quantify the dispersibility of the specific fiber in the cross-sectional image. The dispersibility of the specific fibers in the powder agitated product is evaluated by comparing the dispersibility of the fibers.

As a criterion for extracting an image of a specific fiber from the cross-sectional image of the powder agitated material, it is preferable to use a color tone, a particle size, a difference in lightness from other components, and the like of the specific fiber.

Further, the Voronoi polygon may be drawn by a method in which each side of the polygon circumscribing the extracted specific fiber image is expanded at a constant speed.

According to the above configuration, Voronoi polygons are drawn for each specific fiber appearing in the cross section of the photographed powder agitated object, and the area of each Voronoi polygon is calculated. By calculation, the occupied area on the cross section is calculated for all the specific fibers. Then, if statistical processing such as dispersion or average is performed on the calculated area value of each Voronoi polygon, not only can the dispersibility of the specific fiber be comprehensively evaluated as a whole cross section of the stirred material, but also the cross section of the stirred material can be evaluated. Appropriate evaluation can be performed even in the unit of the above minute area.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 6 show one embodiment of the method for evaluating the dispersibility of a specific fiber in a powder agitated product according to the present invention. FIG. 1 shows the dispersibility of a fiber in a powder agitated product of this embodiment. 2 is a flowchart showing a processing procedure in the evaluation method, FIG. 2 is a cross-sectional image of the powder agitated object to be evaluated, FIG. 3 is an image of a specific fiber extracted from the cross-sectional image shown in FIG. 2, and FIG. 5 is an image in which a specific fiber image is emphasized, FIG. 5 is an image in which a Voronoi polygon is drawn on the specific fiber image shown in FIG. 4, and FIG. 6 is an image in which the Voronoi polygon image shown in FIG. 5 is emphasized. It is a video. In addition, the powder agitated material of this embodiment is a mixture of friction material raw materials used for a friction material of a brake, and includes a reinforcing fiber material, a binder, various additives, and the like as constituent components. It is assumed that aramid fibers have been used.

The method for evaluating the dispersibility of specific fibers in the powder agitated product is performed according to the procedure shown in FIG. That is, first, a cross-sectional image of a powder agitated material obtained by agitating and mixing various powdery constituent components and various fibers is taken (step 101). FIG. 2 is a cross-sectional image 1 of the powder agitated material photographed in step 101. In the image 1, an aramid fiber 2 which is a specific fiber to be evaluated for dispersibility and the specific fiber 2 are entangled. Binders, various additives, and other components 3 are shown.

Next, an image of the aramid fiber 2 in the photographed image 1 is extracted based on a predetermined criterion based on the characteristics of the fiber (step 102). In this case, the extraction of the image of the aramid fiber 2 refers to a judgment criterion set based on properties of the aramid fiber 2 such as the color tone, the particle diameter, the fiber width of the specific fiber 2 and the brightness difference from other components. Means that the image of the video 1 is analyzed by a computer, and the image is recognized so that the image area of the specific fiber 2 is identified from the area of the other component. In the image 1 shown in FIG. 3, the reference numeral 5 indicates an area of the extracted aramid fiber. As shown in FIG. 4, the extracted area 5 is emphasized by changing the display color or the like as necessary so that it can be clearly distinguished from other areas.

Next, a Voronoi polygon is drawn on the extracted image of the aramid fiber 2 (ie, region 5),
Calculate the area of each Voronoi polygon (step 10)
3). In FIG. 5, a polygon 6 surrounding the area 5 of the aramid fiber 2 is a drawn Voronoi polygon image. The drawn Voronoi polygons may be emphasized, if necessary, for easy viewing. FIG. 6 shows an image in which the Voronoi polygon image is emphasized.

In this embodiment, the Voronoi polygon inflates the contour of the area 5 or each side of the polygon circumscribing the contour at a constant speed until the sides of the adjacent polygons come into contact with each other. It is drawn by the thing. The area of the Voronoi polygon drawn in this way is the occupied area (territory area) of each aramid fiber 2 on the cross section of the powder agitated material shown in the image 1, and is calculated for each Voronoi polynomial. Variations in the area value of the square form variations in the dispersibility of the aramid fibers 2 as they are, and the dispersibility of the aramid fibers 2 can be measured quantitatively. That is, if the calculated area values of the many Voronoi polygons are substantially constant, the aramid fibers 2 are evenly dispersed. Also, where the area of the Voronoi polygon is large, the dispersion density of the aramid fiber 2 is low, and where the area of the Voronoi polygon is small,
Since the dispersion density of the aramid fiber 2 is high, it can be understood that the dispersion of the aramid fiber 2 is non-uniform if the area of the Voronoi polygon is largely dispersed.

The Voronoi polygon is formed by drawing the outline of the region 5 or the side of the polygon circumscribing the region 5 by expanding the outline of the region 5 or the center of gravity of the region 5 as in this embodiment. It can also be drawn by expanding the sides of the polygon at a constant speed. However, since the region 5 is for the aramid fiber 2 and may be an elongated region,
The method of drawing by expanding the outline of the region 5 or the sides of the polygon circumscribing the region 5 is more convenient because the aramid fiber 2 fits properly in the drawn Voronoi polygon.

Next, the distribution of the area of each Voronoi polygon is statistically processed to quantify the dispersibility of the aramid fiber 2 in the sectional image 1 (step 10).
4) Further, if the dispersibility of the aramid fibers 2 in the powder agitated product is evaluated by comparing the numerically-dispersed dispersibility of the aramid fibers 2, the processing by the evaluation method of the present embodiment is completed. There is (step 105).

The distribution of the area of the Voronoi polygons can be quantified by statistical processing such as calculating the sum of the areas of the respective Voronoi polygons or calculating the mode of the area of the Voronoi polygons. By the digitization, the dispersibility of the aramid fiber 2 can be quantitatively captured.

According to the above dispersibility evaluation method, Voronoi polygons are drawn for each of the aramid fibers 2 appearing in the cross section of the photographed friction material agitated material, and the area of each Voronoi polygon is drawn. Is calculated, the occupied area on the cross section is calculated for the total number of the aramid fibers 2. Then, by performing statistical processing such as dispersion and average on the calculated Voronoi polygon area values, the dispersibility of the aramid fiber 2 can be comprehensively evaluated as a whole cross section of the stirred material, It is possible to appropriately evaluate even a small area unit on the cross section of the above, and it is possible to easily and accurately determine the dispersibility of the aramid fibers 2 in the agitated friction material without requiring skill or the like. And, with the highly reliable evaluation result,
By modifying the stirring conditions (stir time, stirring amount, etc.) for the friction material agitated material, it is possible to easily and properly maintain and control the quality of the friction material agitated material containing fibers, It is possible to stably produce a friction material stirring product.

Next, the evaluation results by the above-described dispersibility evaluation method and the use of the evaluation results for quality control of the friction material stirrer will be described with specific examples. FIG. 7 is a distribution diagram of the Voronoi polygon area obtained by the dispersibility evaluation method of the above-described embodiment with respect to the friction material agitated products of different production lots. The distribution curve f ₁ in FIG. 7 is for the production lot A, the distribution curve f ₂ is for the production lot B, and the distribution curve f ₃ is for the production lot C.
This evaluation test was performed to evaluate the quality variation of each lot.

In the case of the production lot B, the peak value of the distribution curve is lower than in the case of the production lots A and C, and the distribution curve extends gently with a gentle slope. This means that in the production lot B, the dispersion of the aramid fibers 2 varies greatly, and the stirring state of the friction material agitated material in the lot B is poor, and the friction material agitated material of the lot B is determined to be of poor quality. be able to.

FIG. 8 is a distribution diagram of Voronoi polygon areas obtained by the dispersibility evaluation method of the above-described embodiment with respect to friction material agitated materials produced by agitators having different production scales. In this evaluation test, when the stirrer is scaled up from a small-scale (small-scale) stirrer for trial production to a large-scale (large-scale) stirrer for mass production, a large-scale stirrer is used. This was performed in order to optimize the stirring conditions.

The agitated friction material with a large-scale agitator forms five types of agitated friction material with stirring times of 5 minutes, 4 minutes, 3 minutes, 2 minutes and 1 minute. Create a distribution map of the Voronoi polygon area for each friction material stirrer, and map each distribution map with the Voronoi polygon area distribution map for the friction material stirrer agitated by a small-scale stirrer. By comparing, the optimum value of the stirring time in the large-scale stirrer is determined. In the illustrated example, in the area distribution curve f _b1 ~f _b5 of the Voronoi polygons for friction material stir treated with large-scale stirrer, a stirring time is f _b5 which was 5 minutes, in small-scale stirrer almost completely match the Voronoi polygon area distribution f _s for friction material stir was treated, when scaled up, the stirring time 5
It turns out that you only need to set the minutes.

FIG. 9 shows a distribution diagram of Voronoi polygon areas obtained by the method for evaluating dispersibility of the above-described embodiment for powder agitated products manufactured under different stirring conditions, and the respective area distributions are shown. The optimum stirring conditions are estimated by comparing the curves. Each area distribution curve shows the stirring time as 1
Minutes, 2 minutes, 3 minutes, 4 minutes, 5 minutes, and 6 minutes, and the peak value increases as the stirring time increases to 1 minute, 2 minutes, and 3 minutes, and thereafter becomes constant. That is, stirring is
Three minutes is sufficient, and setting it longer than that does not affect the dispersibility. Therefore, it is understood that the optimum value of the stirring time should be 3 minutes.

The use of the method for evaluating dispersibility of the present invention is as follows.
The present invention is not limited to the evaluation of the dispersibility of the aramid fiber in the mixture of the friction material materials. It can be widely used for evaluation of the dispersibility of specific fibers in the agitated product in general with respect to the agitated product of the fiber-containing powder.

[0029]

According to the method for evaluating the dispersibility of specific fibers in a powder agitated product according to the present invention, specific fibers appearing in a cross section of a photographed powder agitated product are individually Voronoi-like. A polygon is drawn, and the area occupied on the cross section is calculated for all the specific fibers by calculating the area of each Voronoi polygon. Then, if statistical processing such as dispersion or average is performed on the calculated area value of each Voronoi polygon, not only can the dispersibility of the specific fiber be comprehensively evaluated as a whole cross section of the stirred material, but also the cross section of the stirred material can be evaluated. The above fine area unit can be appropriately evaluated, and the dispersibility of the specific fibers of the powder agitated material can be easily and accurately determined without requiring skill or the like. By modifying the stirring conditions for the powder agitated product based on the highly reliable evaluation result, it is possible to easily and appropriately maintain and control the quality of the fiber agitated product containing the fiber. It is possible to stably produce high-quality powder agitated products.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of one embodiment of a method for evaluating the dispersibility of a specific fiber in a powder agitated product according to the present invention.

FIG. 2 is a cross-sectional image of a powder stirring object to be evaluated.

FIG. 3 is an image showing a specific fiber extracted from the cross-sectional image shown in FIG. 2;

4 is an image in a state where the image of the specific fiber shown in FIG. 3 is emphasized.

5 is an image in which a Voronoi polygon is drawn on the image of the specific fiber shown in FIG. 4;

6 is an image in which the Voronoi polygon image shown in FIG. 5 is emphasized.

FIG. 7 is a distribution diagram of Voronoi polygon areas obtained by a method for evaluating the dispersibility of fibers in a powder agitated product according to an embodiment of the present invention for powder agitated products of different production lots.

FIG. 8 shows a distribution of Voronoi polygonal areas determined by a method for evaluating the dispersibility of fibers in a powder agitated product according to an embodiment of the present invention with respect to powder agitated products produced by agitators having different production scales. FIG.

FIG. 9 is a distribution diagram of Voronoi polygon areas obtained by a method for evaluating the dispersibility of fibers in a powder agitated product according to an embodiment of the present invention with respect to a powder agitated product manufactured under different stirring conditions. .

[Explanation of symbols]

 Reference Signs List 1 Cross-sectional image 2 Specific fiber (aramid fiber) 3 Various constituents (granules) 5 Extraction area 6 Voronoi polygon

Claims (3)

[Claims] 1. A method of stirring various kinds of powdery constituent components and fibers.
A cross-sectional image of the mixed powder stirrer is photographed, and an image of a specific fiber in the photographed image is extracted based on a predetermined criterion based on the characteristics of the fiber, and the extracted image of the specific fiber is extracted. On the other hand, a Voronoi polygon is drawn to calculate the area of each Voronoi polygon, and the distribution of the area of each Voronoi polygon is statistically processed to quantify the dispersibility of a specific fiber in the cross-sectional image. A method for evaluating the dispersibility of a specific fiber in a powder stirrer, wherein the dispersibility of the specific fiber in the powder stirrer is evaluated by comparing the dispersibility of the converted specific fiber. 2. A criterion for extracting an image of a specific fiber from a cross-sectional image of a powder agitated product, wherein a color tone, a particle size, a lightness difference from other constituent components, and the like of the specific fiber are used. The method for evaluating the dispersibility of a specific fiber in a powder agitated product according to claim 1. 3. The powder according to claim 1, wherein the Voronoi polygon is drawn by a method of expanding each side of the polygon circumscribing the extracted image of the specific fiber at a constant speed. Method for evaluating dispersibility of specific fiber in body agitated product.