JPH07301266A - Manufacture of frictional member - Google Patents

Abstract

PURPOSE:To manufacture a frictional material such as a brake pad or the like being excellent in corrosion resistance and adhesiveness in a simple process. CONSTITUTION:A back plate consisting of ferreous metal is processed into soft nitriding, and the surface is provided with a soft nitriding process A forming a compound layer mainly composed of a Fe-N-C system, a cooling- washing process B cooling and washing the back plate after subjected to the soft nitriding, a vacuum desication process C drying the back plate after being washed by means of vacuum desiccation, and a frictional material adhesive process D making a frictional material integrally adhere to a surface of the back plate after being desiccated, respectively. In this connection, in the soft nitriding process A, pretreatment of the back plate to remove press oil and rust preventive oil sticking to the back plate by mans of washing is omissible. Likewise, soft nitriding in the back plate can be processed in low cyanate baths.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention integrally joins a metal backing and a surface of a ferrous metal such as a disc brake pad, a drum brake shoe, or a clutch plate used for brakes and clutches of automobiles and industrial machines. The present invention relates to a method for manufacturing a friction member made of a friction material.

[0002]

2. Description of the Related Art Conventionally, an automobile disc brake,
Frictional members such as brake pads and brake shoes used for drum brakes and the like are generally manufactured by integrally bonding a friction material with an adhesive to the surface of a backing metal made of an iron-based metal such as steel.

Since these friction members press the rotating disk rotor and brake drum to perform braking by the frictional force, a large shearing force is applied between the friction material and the back metal. Therefore, a strong adhesive force is required between the friction material and the back metal. When rust is generated on the joint surface due to long-term use, running on salt-damaged land, or the like, the adhesive force of the rust may be reduced, and the friction material may eventually peel off from the backing metal, resulting in an unexpected danger.

As described above, the joint surface between the friction material and the back metal is required to have a strong adhesive force and excellent corrosion resistance. Such a requirement is due to the increase in speed and the sophistication of automobiles. It is becoming more and more severe due to an increase in heat load, etc., and a longer life due to improved quality of friction materials.

In response to such demands, the back metal is previously subjected to a soft nitriding treatment to form a compound layer mainly composed of Fe—C—N on the surface thereof, and a friction member is bonded to this compound layer through an adhesive. It is known to bond (for example, Japanese Patent Publication No. 53-
47218). According to this, since the compound layer has excellent corrosion resistance and has a fine mesh-like uneven structure, the corrosion resistance and adhesiveness of the joint surface between the friction material and the back metal can be significantly improved.

The friction member including the soft nitriding treatment of the back metal is generally manufactured as follows. That is, after soft nitriding the back metal, cooling and washing with water,
In order to remove the water, it is treated with water-repellent rust preventive oil.
Next, before adhering the friction material, the water-substituted rust preventive oil is washed with an organic solvent such as trichlorethylene and degreased. After that, according to a general method for manufacturing a friction member, the friction material is bonded and the post-treatment is performed.

[0007]

As described above, according to the method of manufacturing a friction member, which includes the step of soft-nitriding the back metal and forming the compound layer mainly composed of Fe-C-N on the surface thereof. Therefore, a friction member having excellent corrosion resistance and adhesiveness can be obtained.

However, the conventional method including such a soft nitriding treatment step uses the water-replacing rust preventive oil as a means for removing the water adhering to the surface of the backing metal by washing with water, and therefore chlorine is used as the subsequent treatment. Since it requires cleaning and degreasing with a system organic solvent, it takes time and labor, and the manufacturing cost of the friction member tends to increase accordingly. However, such a water-dispersed rust preventive oil was used because when the back metal after washing with water is dried as it is with hot air, the moisture permeated into the porous compound layer by nitrocarburizing treatment is completely removed. In order to remove it, it is necessary not only to dry it at a relatively high temperature for a long time, but especially if there is a dent on the back metal, water is likely to accumulate and rust may occur due to heat during drying. is there.

Therefore, as a measure for improving this method, in JP-A-5-230438, the back metal after soft nitriding, cooling and washing with water is immersed in an aqueous solution of an ethanolamine anion surfactant having a pH of 8 to 9. To form an anticorrosion film,
Then, it is proposed to directly bond the friction material.

The proposed method does not require treatment with a water-repellent rust preventive oil, cleaning with an organic solvent such as trichlorethylene, or degreasing treatment, so that the steps are simpler and less troublesome than conventional methods. Moreover, there is an advantage that no special equipment is required. However, according to this method, an adhesive such as a phenolic resin cannot be applied to the backing metal coated with the surfactant aqueous solution by the dipping treatment, so that the backing metal after the dipping treatment must be dried to remove water. However, this requires long-time drying at a relatively high temperature, and since the rust preventive power of the surfactant is not so strong, rust tends to occur during drying. Further, since the surfactant does not act as an adhesive, if it remains on the surface of the backing metal, it tends to be an obstacle to adhesion with the friction material.

Therefore, the present invention aims to provide a method for manufacturing a friction member, which is a further improvement of the above-mentioned method according to the prior art, and which can obtain a friction member excellent in corrosion resistance and adhesiveness in a simpler process. To do.

[0012]

Means for Solving the Problems The present inventors have conducted various comparative studies in view of the above-mentioned points, and as a result, have been well-known as a drying means itself as a drying means for a backing metal which has been cooled and washed with water after soft nitriding. However, by adopting the vacuum drying which has not been attempted in the field,
Moreover, they have found that a friction member having excellent corrosion resistance and adhesiveness can be obtained.

That is, in the method for manufacturing a friction member according to the first aspect of the present invention, the soft metal is formed by soft nitriding the back metal made of an iron-based metal and forming a compound layer mainly composed of Fe-NC on the surface thereof. Nitriding treatment step, cooling and rinsing the back metal after soft nitriding, washing with water, reduced pressure drying step of drying the back metal after water washing by reduced pressure drying, and friction material integrated on the surface of the back metal after drying And a friction material adhering step for adhering.

Further, in the method for manufacturing a friction member of the present invention according to claim 2, in the soft nitriding treatment step of claim 1, the backing metal is softened without removing the press oil and the rust preventive oil adhering thereto by washing. The nitriding treatment is performed.

Further, in the method for manufacturing a friction member according to the third aspect of the present invention, in the soft nitriding treatment step of the first or second aspect, the back metal is subjected to the soft nitriding treatment in a low cyanide salt bath.

[0016]

In the invention according to claim 1, since the backing metal after being washed with water is dried by reduced pressure drying, the moisture adhering to the backing metal can be removed in a short time and at a relatively low temperature. Therefore, the friction member can be easily manufactured, and the generation of rust on the back metal during drying is further reduced, so that the friction member having excellent corrosion resistance and adhesiveness can be obtained.

Further, in the invention according to claim 2,
Since the back metal is soft nitrided without removing the press oil and rust preventive oil attached to it by cleaning, the press oil and the rust preventive oil adhered to the back metal are decomposed during the soft nitriding process. Since the washing of the back metal before the soft nitriding treatment is eliminated, the treatment process is further simplified.

Further, in the invention according to claim 3,
Since the soft nitriding treatment of the back metal is performed by the low cyanide salt bath, in addition to the above-mentioned effects, the safety of the work is improved and the treatment of the waste liquid becomes simpler.

[0019]

EXAMPLES The present invention will be described in more detail below with reference to examples.

FIG. 1 is a process diagram schematically showing the manufacturing process of the method for manufacturing a friction member of the present invention. Then, as shown in FIG. 1, according to the method for manufacturing a friction member of the present invention, the back metal made of an iron-based metal is soft-nitrided to form a compound layer mainly composed of Fe-NC on the surface thereof. A treatment step A, a cooling step of cooling and rinsing the back metal after the soft nitriding treatment, and a water washing step B,
Vacuum drying step C in which the back metal after washing with water is dried by vacuum drying
And a friction material adhering step D for integrally adhering the friction material to the surface of the back metal after drying.

In the soft nitriding step A, the soft nitriding of the backing metal made of an iron-based metal such as steel can be carried out by any conventionally known method. It can be performed by any method. In the case of the method performed in the gas phase, the soft nitriding treatment can be generally performed by holding for 30 minutes to 8 hours in a heating atmosphere of 500 to 650 ° C. containing a mixed gas of an endothermic shift gas and ammonia gas. . Further, in the case of the method performed in a salt bath, the soft nitriding treatment is carried out in a salt bath mainly containing cyanate and cyanate, for example, at a temperature of 570 to 610 ° C. for 40 to 1
Generally, the treatment can be performed for 50 minutes. In the case of the method performed in this salt bath, the cyan concentration of the salt bath is generally 18 to 20% in the past, but the soft nitriding treatment is performed by a low cyan salt bath having the cyan concentration of 0.1 to 6%. It is preferable to carry out. The soft nitriding treatment using such a low cyanide salt bath is safe in terms of work, and the waste liquid treatment is simple, which is preferable in terms of pollution prevention.

By this soft nitriding treatment, Fe on the surface of the back metal is
A compound layer mainly composed of -CN system is formed. Generally, the longer the treatment time and the higher the treatment temperature, the thicker the compound layer and the deeper the surface irregularities. The thickness of this compound layer is generally at least 5 μm, preferably 10 μm or more, in order to ensure sufficient corrosion resistance and adhesion of the joint surface between the backing metal and the friction material. However, a thickness of 50 μm or more is not generally required in practice because the corrosion resistance and the adhesiveness are already too high.

In the soft nitriding step A, the soft nitriding treatment of the back metal can be performed after the press oil and the rust preventive oil adhering thereto are removed by cleaning in advance, but the back metal cleaning treatment is omitted. You can also in this case,
Press oil and rust preventive oil attached to the back metal are thermally decomposed and volatilized during the soft nitriding treatment. Then, according to this, since the cleaning process is omitted, the processing process can be further simplified.

Next, in the cooling and rinsing step B, the soft nitriding backing metal is gradually or rapidly cooled to room temperature, and then the contaminants or salt bath agent adhering to the surface of the backing metal are washed off with water. It should be noted that this cooling and washing with water can be performed together.

Then, in the reduced pressure drying step C, the back metal after washing with water is dried to remove water adhering to it.
Dry under reduced pressure. This reduced pressure drying can be performed at any temperature, pressure (atmospheric pressure), and time. However, pressure (atmospheric pressure)
Since the lower the drying time, the shorter the drying time.
Further, the higher the drying temperature is, the shorter the drying time can be. However, the excessively high temperature is not preferable because it accelerates the corrosion reaction due to moisture, and therefore, the temperature is preferably 100 ° C. or lower.

The steps after treating the back metal as described above are the same as the conventional ones. In the friction material bonding step D, the friction material is integrally bonded to the surface of the back metal via an adhesive such as a phenol resin.

Here, the friction material is a fiber base material forming a skeleton, a resin binder for binding and holding the fiber base material, and various fillers dispersed and filled in a matrix of these fibers and the binder. It is generally composed of fillers. As the fiber base material, inorganic fiber such as glass fiber, organic fiber such as aramid fiber, metal fiber such as steel fiber, and the like can be used, and as the resin binder, thermosetting resin such as phenolic resin Alternatively, a crosslinkable rubber can be used. Further, as the filler, a body filler such as barium sulfate or calcium carbonate, a solid lubricant such as graphite or molybdenum disulfide, an organic polymer powder such as cashew dust which is a cured product of cashew oil, or the like can be used. If desired, an abrasive agent such as silica or other additives for adjusting friction can be used.

Adhesion of such a friction material can be generally carried out by pressing and heating a preformed or preformed friction material on a backing metal coated with the adhesive. Further, the friction material and the back metal can be bonded simultaneously with the molding of the friction material by directly press-molding a mixture of materials forming the friction material on the back metal coated with the adhesive.

[Examples 1 to 4 and Comparative Examples 1 to 4] Next, examples in which the present invention is applied to manufacture of brake pads for disc brakes will be described together with comparative examples.

Here, the back metal of the brake pad is made of steel SHP45 (JIS), and the friction material is made of the following composition.

[0031]

[Table 1]

<Embodiment 1> The back metal is coated with a cyan concentration of about 20%.
In the salt bath of No. 1, nitriding treatment was performed at 600 ° C. for 90 minutes. As a result, a compound layer mainly composed of Fe—N—C system, that is, a soft nitride layer having a thickness of about 14 μm was formed. Then, the back metal after the soft nitriding treatment was rapidly cooled, washed with water, and then dried by vacuum drying. This vacuum drying was performed at a temperature of 80 ° C. and a pressure (atmospheric pressure) of 60 mmHg for 10 minutes. Then, a friction material was adhered and joined to the back metal by a conventional method using a phenol resin to manufacture a brake pad.

Example 2 Under the same conditions as in Example 1, the back metal was soft-nitrided, quenched, washed with water, dried under reduced pressure, and then,
A friction material was adhered to the back metal to manufacture a brake pad. However, drying under reduced pressure was performed for 5 minutes under the conditions of a temperature of 80 ° C. and a pressure of 5 mmHg.

Example 3 Under the same conditions as in Example 2, the back metal was soft-nitrided, quenched, washed with water, dried under reduced pressure, and then,
A friction material was adhered to the back metal to manufacture a brake pad. However, in Examples 1 and 2, the press oil and rust preventive oil adhering to the back metal were removed by washing before soft-nitriding the back metal, but in this embodiment, this treatment is omitted and the back metal is directly softened. Nitrided. It should be noted that this embodiment particularly corresponds to the aspect of claim 2.

Example 4 The back metal was soft-nitrided at 600 ° C. for 180 minutes in a low cyanide salt bath having a cyan concentration of about 2%. This gives a thickness of about 14 as in Examples 1-3.
A compound layer mainly composed of Fe—N—C system having a thickness of μm, that is, a soft nitride layer was formed. Other conditions were the same as in Example 3, the soft nitriding backing metal was rapidly cooled, washed with water, and then dried under reduced pressure.
Then, a friction material was adhered to the back metal to manufacture a brake pad. It should be noted that this embodiment particularly corresponds to the aspect of claim 3.

Comparative Example 1 The back metal was soft-nitrided under the same conditions as in Example 1, quenched and washed with water, and then water-dispersible rust preventive oil (NOX-RUST30) was used to remove water adhering to the back metal.
7 manufactured by Nihon Parkerizing Co., Ltd., and then
It was washed with trichlorethylene. After that, a friction material was adhered in the same manner as in the example to manufacture a brake pad.

Comparative Example 2 The back metal was soft-nitrided under the same conditions as in Example 1, quenched and washed with water, and then dried in an electric heating oven at 105 ° C. for 60 minutes to remove water adhering to the back metal. That is, the drying process was performed under atmospheric pressure. After that, the friction material was similarly adhered to manufacture a brake pad.

Comparative Example 3 The back metal was soft-nitrided under the same conditions as in Example 1, quenched and washed with water, and then a 5 wt% aqueous solution of an ethanolamine anion surfactant (Perchem 6003 manufactured by Nihon Parkerizing Co., Ltd.) (PH8. 5). This immersion treatment was carried out for 3 minutes, and it was attempted to apply the adhesive after draining, but the adhesive could not be applied because the aqueous solution remained on the surface of the backing metal. Therefore, in this comparative example 3, the brake pad could not be manufactured.

Comparative Example 4 Then, as Comparative Example 4, the backing metal after the immersion treatment with the ethanolamine anion surfactant aqueous solution in Comparative Example 3 was prepared in the same manner as in Comparative Example 2.
It was dried at 5 ° C. for 60 minutes. After that, the friction material was similarly adhered to manufacture a brake pad.

[Evaluation Test] With respect to the brake pads of Examples 1 to 4 and Comparative Examples 1 to 4 obtained as described above, in order to evaluate their corrosion resistance and adhesiveness, the backing metal before adhering a friction material was used. The appearance was visually observed, and the adhesive strength and the adhesive area of the brake pad when it was new and the adhesive strength and the rust area after the rusting test were measured.
The result is shown in FIG.

The adhesive strength is JASO C 437-.
It was measured according to 84. In addition, the rust test
After spraying the brake pad with 5 wt% concentration of salt water for 72 hours, the process of leaving it at room temperature for 24 hours is defined as one cycle,
This was repeated 20 cycles.

As shown in the test results of FIG. 2, the brake pads obtained in Examples 1 to 4 were treated with a water-displacing rust preventive oil and then washed with trichlorethylene according to the conventional method of Comparative Example 1. It can be seen that, although the process of removing the water adhering to the back metal after washing with water is much simpler than that of the above products, it has corrosion resistance and adhesiveness equivalent to or higher than these. On the other hand, Comparative Example 2 in which normal drying treatment was performed to remove water adhering to the back metal after washing with water and Comparative Example 4 in which immersion treatment with an ethanolamine anion surfactant aqueous solution was performed were Comparative Examples. 1
Although it is simpler than the above method, there is a tendency that the corrosion resistance and the adhesiveness become insufficient especially in a severe corrosive environment.

As described above, according to the method for manufacturing the brake pad of this embodiment, the back metal made of an iron-based metal is soft-nitrided, and the compound layer mainly composed of Fe-N-C is formed on the surface thereof. Cooling process step A and the back metal after soft nitriding,
A cooling and water washing step B for washing with water, a reduced pressure drying step C for drying the back metal after washing with water by reduced pressure drying, and a friction material adhering step D for integrally adhering a friction material to the surface of the back metal after drying. is there. Therefore, since the back metal after washing with water is dried by reduced pressure drying, the water adhering to the back metal can be removed in a short time, and the brake pad can be easily manufactured. Moreover, it is possible to manufacture a brake pad having excellent corrosion resistance and adhesiveness.

The method for manufacturing a friction member of the present invention can be applied not only to a brake pad for a disc brake but also to a friction member such as a brake shoe for a drum brake or a clutch plate for a clutch. it can.

[0045]

As described above, in the method for manufacturing a friction member of the invention according to claim 1, the back metal made of an iron-based metal is soft-nitrided, and the surface thereof is a compound mainly composed of Fe-N-C. Soft nitriding process to form a layer, cooling the back metal after the soft nitriding process, cooling to wash with water, a water washing process, a reduced pressure drying step to dry the back metal after washing by reduced pressure drying, and the surface of the back metal after drying. And a friction material adhering step for adhering the friction material integrally.

Therefore, since the back metal after washing with water is dried by reduced pressure drying, the water adhering to the back metal can be easily removed in a short time at a low temperature. Therefore, it is possible to prevent the occurrence of rust during drying, it is possible to produce a friction member having excellent corrosion resistance, adhesiveness, treatment with water-displacing rust preventive oil and subsequent cleaning with a solvent such as trichlorethylene. The friction member can be manufactured in a much simpler process as compared with the conventional method having a complicated process that requires treatment.

Further, in the method for manufacturing a friction member of the present invention according to claim 2, in the soft nitriding treatment step of claim 1, the backing metal is softened without removing the press oil and the rust preventive oil adhering to the backing metal by washing. The nitriding treatment is performed.

Therefore, since the cleaning of the back metal before the soft nitriding treatment is eliminated, the manufacturing process of the friction material can be further simplified.

Further, in the method for manufacturing a friction member of the present invention according to claim 3, in the soft nitriding step of claim 1 or 2, the back metal is soft nitrided in a low cyanide salt bath. is there.

Therefore, the soft nitriding treatment can be safely performed and the waste liquid treatment can be easily performed.

[Brief description of drawings]

FIG. 1 is a process diagram showing an outline of a manufacturing process of a method for manufacturing a friction material according to the present invention.

FIG. 2 is a table showing evaluation test results of brake pads manufactured according to Examples and Comparative Examples of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahito Mizuno, Masahito Mizuno 1141 Okawagahara, Iino, Fujioka-cho, Nishikamo-gun, Aichi Prefecture Aisin Kako Co., Ltd. Asahi Chiyoda Industry Co., Ltd.Akatsuki Seto Factory

Claims (3)

[Claims] 1. A soft metal nitriding treatment of a back metal made of an iron-based metal,
A soft nitriding treatment step of forming a compound layer mainly composed of Fe-NC system on its surface, a cooling and water washing step of cooling and washing the back metal after the soft nitriding treatment, and a pressure reduction of the back metal after the water washing. A method of manufacturing a friction member comprising: a reduced pressure drying step of drying by drying and a friction material adhering step of integrally adhering a friction material to the surface of the back metal after the drying. 2. The friction member according to claim 1, wherein, in the soft nitriding treatment step, the back metal is subjected to a soft nitriding treatment without removing the press oil and rust preventive oil adhering to the back metal by washing. Production method. 3. The method for manufacturing a friction member according to claim 1, wherein, in the soft nitriding treatment step, the back metal is soft nitrided in a low cyanide salt bath.