JP2002226832A - Method for evaluating mixed state of stirred friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a friction material having stable quality and performances by quantitatively evaluating a mixed state of the stirred material of friction material for a brake. SOLUTION: This method for evaluating the mixed state of the stirred friction material is characterized by quantitatively evaluating the mixed state of the stirred material of friction material by discriminating between the objective material of evaluation of the friction material and nonobjective materials thereof and dividing the materials into two values with using an image analysis device and quantitatively measuring a size, an amount and a dispersed state of the objective material of evaluation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the mixing state of a friction material stirrer, and more particularly to an automobile,
The present invention relates to a method for evaluating a mixed state of friction material in order to know in real time an accurate quantitative evaluation of the quality of a mixed state of a mixture of friction material agitated materials in the production of friction materials for brakes of railway vehicles, industrial machines, and the like. .

[0002]

2. Description of the Related Art Conventionally, in the production of friction materials for brakes of automobiles, railway vehicles, industrial machines, etc., friction materials mainly used for brakes and the like generally contain various kinds of fillers and reinforcing materials as components. In addition to various fibers, abrasives, lubricants, and friction modifiers, various resins are compounded as binders for binding these materials. In a manufacturing process of a brake pad for a disc brake, which is one example of a conventionally known method of manufacturing a friction material, the brake pad is formed into a predetermined shape by a sheet metal press, subjected to a degreasing treatment and a primer treatment, and then coated with an adhesive. Pressure plate, heat-resistant organic fibers, inorganic fibers, reinforcing fibers such as metal fibers, and inorganic and organic fillers, friction modifiers, and powder materials such as binders (specifically, phenolic resin) A preformed body produced by molding (preforming) the raw material sufficiently homogenized by stirring at room temperature at a predetermined pressure, and thermoforming at a predetermined temperature and pressure in a thermoforming step to integrate both members. , After-curing, and finally finishing.

As described above, the production of a friction material includes the steps of compounding the friction material, stirring, preforming, thermoforming, heating, polishing, machining, etc. Among them, the mixing state in the first stirring step is included. Is an important step that greatly affects the quality and performance of the post-process and the finished product, and it is necessary to perform an accurate evaluation and maintain a good mixed state. Therefore, in order to evaluate the quality of the mixed state, evaluation by measuring the temperature, apparent / bulk density, moisture content, sieving and the like of the agitated material is currently being carried out.

[0004]

However, since these methods cannot always sufficiently evaluate the quality of the mixed state, it is necessary to reproduce the good mixed state set at the time of trial production at the time of mass production transfer (scale-up of the stirrer). However, there are problems such as the need for many trials again, changes in the stirring environment due to seasonal fluctuations, and the occurrence of stirring problems due to changes in characteristics due to lot fluctuations in the compounding materials. It is very difficult to do. Under such circumstances, it is desired to quickly establish a method for accurately and quantitatively evaluating the quality of the mixed state. The present invention
The present invention has been made in view of such a conventional problem, and an object of the present invention is to obtain a friction material having stable quality and performance by quantitatively evaluating a mixed state of a friction material stirrer for a brake.

[0005]

Means for Solving the Problems The present inventors have achieved the above object by the following means. (1) Friction material evaluation target material and non-target material are discriminated and binarized, and the size, quantity and dispersion state of the evaluation target material are quantitatively measured to determine the mixing state of the friction material agitated material. A method for evaluating the mixing state of a stirrer of a friction material, characterized by performing a quantitative evaluation. (2) The method according to (1), wherein the identification and binarization are performed using an image analyzer. (3) The method for evaluating a mixed state of a stirrer material according to (1), wherein the stirrer material is fixed with a resin and polished prior to the identification and binarization.

[0006]

Embodiments of the present invention will be described below. In the present invention, in order to accurately evaluate the quality of the mixing state of the materials occurring there during the stirring process of the friction material stirrer, cutting the friction material material fixed with resin, the observation surface after polishing, The mixed state is quantified and evaluated using an image analyzer such as a stereo microscope, a fluorescence microscope, and an electron probe micro analyzer (EPMA). In practical measurement, preparation of an evaluation sample,
The evaluation is performed in four stages: binarization of the evaluation target material, measurement of the size and quantity of the target material, distribution measurement of the occupied area per unit, and evaluation of the mixed state. Based on the optimal mixing conditions of the agitated product obtained from the evaluation method of the present invention, reinforcing fibers,
The raw materials including the friction modifier and the binder are blended, and the agitated and mixed agitated material is preformed according to a normal manufacturing method.
An optimal friction material can be manufactured by thermoforming.

In the friction material of the present invention, the reinforcing fibers include, for example, organic fibers such as aramid fibers and oxidized acrylic fibers, copper fibers, metal fibers such as steel fibers, glass fibers, potassium titanate fibers, and Al ₂ O _3. and inorganic fibers such as -SiO ₂ based ceramic fibers. Examples of the inorganic filler include inorganic particles such as barium sulfate and calcium carbonate, and scaly inorganic substances such as vermiculite and mica. Examples of the binder include a phenol resin (including various modified phenol resins such as straight phenol resin and rubber), a melamine resin, an epoxy resin,
A thermosetting resin such as a polyimide resin can be used. Examples of the friction modifier include metal powders such as copper powder and zinc powder, and organic friction modifiers such as synthetic rubber and cashew resin, and examples of the lubricant include graphite and molybdenum disulfide. Examples of the abrasive include metal oxides such as alumina, silica, magnesia, zirconia, and chromium oxide. As the composition of the friction material, various composition ratios can be adopted. That is, these are the friction properties required for the product, for example,
Depending on the coefficient of friction, wear resistance, vibration characteristics, squeal and the like, they may be used alone or in combination of two or more.

In the present invention, a friction material agitated product obtained by mixing the above-mentioned raw materials is preformed, thermoformed, cut and cut.
For the first time, it was possible to quantitatively evaluate the quality of the mixed state of the evaluation sample obtained by polishing, and to establish a method capable of quantifying it.

[0009]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to only this embodiment.

Example 1 In order to produce a friction material from the friction material materials having the composition ratios shown in Table 1, stirring was performed using a 10-liter Erich mixer so as to obtain a mixture of the friction material materials having the above composition ratios. Stirring was performed while changing the conditions at a rotation speed of 3000 rpm and stirring time at intervals of 1 minute from 1 to 10 minutes, and the mixing state of the obtained stirred product was evaluated according to the following procedure.

[0011]

[Table 1]

(1) Preparation of Sample for Evaluation About 20 g of the agitated material is placed in a mold having a diameter of 45 mm, and 4 MPa
Is applied for about 10 seconds to form a preform, and a low-viscosity epoxy resin is penetrated under reduced pressure into the preform,
After curing at 0 ° C., a sample for evaluation was prepared by cutting and polishing. (2) Binarization of materials to be evaluated Aramid fibers and glass fibers, which greatly affect the physical properties and performance of the friction material, are selected as the materials to be evaluated. The aramid fibers are distinguished from other materials by fluorescence microscopy. Was discriminated from other materials by surface analysis (elemental mapping) of Si and Ca by EPMA, and the observation / analysis image was taken into an image analyzer and binarized.

(3) Measurement of size, quantity, and distribution of occupied area per object After the binarization process, distribution of size, quantity, and occupied area per object were measured. As a measurement example, FIG. 1 shows changes in the sizes of glass fibers and aramid fibers (represented by the circle equivalent diameter) when the stirring time is different from 3, 4 and 5 minutes, and the occupied area (the Voronoi polygon area is represented by the circle equivalent diameter). 2 and FIG. 3 show changes in the distribution of (display). When the stirring time is as short as 3 minutes, the sizes of the glass fiber and the aramid fiber are large and the occupied area varies widely (dispersion is not uniform), but the longer the stirring time, the smaller the size of both the glass fiber and the aramid fiber ( The dispersion of the occupied area is small and the dispersion is uniform (see FIGS. 2 and 3).

(4) Evaluation of mixed state The aramid fiber has a large size because pills remain in the initial stage of stirring, but it becomes smaller and becomes more evenly distributed when it is defibrated. It can be evaluated as being in a good mixed state. On the other hand, as the stirring time of the glass fiber becomes longer, the size becomes smaller and the distribution becomes uniform.However, in the case of the glass fiber, when the size becomes smaller, the strength of the finished product tends to decrease and the brake noise tends to occur. The size should not be too small. Comprehensively judging from the size and distribution of the glass fiber and the aramid fiber, a mixing state of 4 minutes can be evaluated as the best mixing state.

The agitated product evaluated by the above method was processed into a finished product through the subsequent steps, and a bending test, a performance test, and a brake noise test were performed. Although there was no difference in any of the performance tests, as shown in Table 2, the bending strength was slightly lower in the case of the stirring time of 3 minutes, and the occurrence of brake noise was in the case of the stirring time of 5 minutes.
There were a lot of things. Next, in order to shift to mass production of the same compounding material, a stirring trial was performed with a 150-liter Erich mixer, and based on the size and occupied area of the glass fiber and aramid fiber of a good stirred material at the time of trial production, the mixing state was determined. When the stirring conditions were examined during the evaluation, it was found that, in the past, several trials were required to set the appropriate conditions, but this time the appropriate conditions could be set in the second trial.

[0016]

[Table 2]

[0017]

According to the present invention, the stirrer is fixed with a resin, cut and polished, the observation surface is observed by a stereoscopic microscope / fluorescence microscope, element surface analysis (mapping) by EPMA, and a screen analyzer. Is used to discriminate (binarize) the evaluation target material from the non-target material and quantitatively measure the size, number, dispersion state, etc. of the evaluation target material to accurately determine the quality of the mixed state of the agitated material. Quantitative evaluation became possible. As a result, the good mixing state obtained during the trial production of the friction material can be relatively easily reproduced even during the transition to mass production. Problems can now be prevented.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the stirring time and the sizes of glass and aramid fibers (equivalent circle diameter).

FIG. 2 is a bar graph showing the relationship between stirring time and glass fiber occupied area / piece (equivalent circle diameter).

FIG. 3 is a bar graph showing the relationship between the stirring time and the area occupied by aramid fibers / piece (equivalent circle diameter).

Continued on the front page F-term (reference) 2G001 AA03 BA05 CA01 HA01 HA13 JA12 KA01 KA20 LA06 NA07 NA09 2G043 AA03 BA14 EA01 FA02 GA07 GA08 GB21 LA01 NA01 NA06 2G059 AA01 BB08 CC20 DD01 EE07 FF01 KK04 MM01 MM09

Claims (3)

[Claims] 1. A method for mixing and agitating friction material material by discriminating and binarizing a material to be evaluated and a non-object material of the friction material and quantitatively measuring the size, quantity and dispersion state of the material to be evaluated. A method for evaluating a mixed state of a stirrer of a friction material, characterized by quantitatively evaluating a state. 2. The method according to claim 1, wherein the discrimination and binarization are performed using an image analyzer. 3. The method according to claim 1, wherein the agitated friction material is fixed with a resin and polished prior to the identification and binarization.