JP4430468B2 - Copper-based sintered friction material - Google Patents

Description

  The present invention relates to a copper-based sintered friction material mainly composed of copper and iron used for brake lining, clutch facing and the like.

  In motorcycles, automobiles, railway vehicles, airplanes, various industrial machines, and the like, various friction materials are used as brake materials such as brake linings and brake pads and clutch materials such as clutch facings.

  The friction material is roughly classified into an organic friction material in which a filler component is combined with a resin and rubber as a binder, and a metal friction material in which a metal or alloy is sintered as a matrix. Metallic friction materials are useful as friction materials used under severe conditions because they have higher wear resistance, heat resistance, and the like than organic friction materials.

  In addition, with the recent increase in speed and size of vehicles, the output has increased, the load on various friction materials including brakes has become severe, and the friction coefficient and wear resistance required for friction materials have higher performance. Has come to be required.

  For example, according to Patent Document 1, a friction material having a high friction coefficient, little change in friction coefficient due to temperature, and having excellent wear resistance, a metal material as a matrix, a friction modifier, a lubricant, and the like In the composition to which the filler is added, the component constituting the matrix contains 10 to 70% of Ni and 30 to 80% of Cu by weight% in the matrix, and the total of Ni and Cu is 60% or more. Material compositions have been proposed.

  Further, in Patent Document 2, hard particles made of an iron-based intermetallic compound such as FeMo, FeCr, and FeTi having a maximum particle size of 15 μm or less and an average particle size of 5 μm or less are uniformly dispersed in a Cu—Sn-based copper alloy substrate. A sintered sliding member having a structure is disclosed.

Further, in Patent Document 3, as a friction pad suitable for a brake rotor made of titanium or a titanium alloy, the hard phase of the iron-based intermetallic compound and the solid lubricating component are uniformly dispersed in the base material, and the base material is a copper alloy powder. When the sintered body is frictionally slid in the atmosphere with titanium or a titanium alloy as a counterpart material, 0.3 or more without causing seizure between the sliding surfaces. A copper-based sintered friction material that stably expresses the friction coefficient is disclosed.
Japanese Patent Laid-Open No. 63-030617 Japanese Patent Laid-Open No. 07-102335 JP 09-269026 A

  In order to cope with the higher output due to higher speed and larger size, sintered metal friction materials have a high friction coefficient and wear resistance, as well as a decrease in friction coefficient and wear resistance even at high temperatures. Therefore, a friction performance that can be maintained at a high value is required, and according to the above prior art, a sintered metal-based friction material having a high friction coefficient and wear resistance is provided.

  However, a friction material that requires a high speed reduction with an increase in speed and output cannot sufficiently satisfy the required performance only with a high friction coefficient and high wear resistance. That is, not only can a high coefficient of friction and wear resistance be maintained even during high-load braking that requires a high speed reduction, but the brakes can be smoothly stopped and smoothly stopped without sudden braking force being activated. Therefore, it is required to brake and stop so as not to give a large impact.

  For example, when used on a brake pad such as a motorcycle, a large impact is generated due to sudden braking, and in particular, sudden braking force works immediately before stopping, causing not only discomfort to the occupant but also dangerous. is there.

  Therefore, the present inventor, for example, conducted research on a policy capable of operating a high braking force on a two-wheeled vehicle operating at high speed and stopping it smoothly, and as a result, when electrolytic iron powder and stainless steel powder were used in combination, The component acts as a component that inhibits sinterability, creating voids around the iron component of the matrix phase, and acts similar to pores and abrasives in the friction material, and functions smoothly during high braking It was confirmed.

  The present invention has been completed on the basis of the above-mentioned knowledge, and its purpose is to brake a high-speed vehicle or the like with a high deceleration to decelerate, and further to maintain a high friction coefficient and smoothly brake when stopping. Then, it is providing the copper-type sintered friction material which can give a passenger | crew a feeling of high braking effectiveness (braking feeling).

The copper-based sintered friction material according to the present invention for achieving the objects of the tin powder; 0.5 to 15 wt%, zinc dust; 0.1 to 30 wt%, nickel powder; 5-25 wt%, Iron powder: 5 to 25% by mass , stainless steel powder; 0.1 to 20% by mass , copper powder: 55 to 80% by mass of the matrix metal component of the balance, and filler components such as a lubricant and a friction modifier are 20 to 20%. 45% by mass of a sintered body ,
(1) The total amount of iron powder and stainless steel powder is 8 to 28% by mass
(2) Electrolytic iron powder having a particle size range of 40 to 150 μm, wherein the iron powder is heat-treated at a temperature of 600 to 1200 ° C. in an atmosphere of hydrogen gas or ammonia gas,
This is a structural feature.

Further, the matrix metal component includes 0.1 to 5% by mass of manganese powder, and has a build-up rate in a torque curve of 40 degrees or more. However, the build-up rate, in the dynamo testing machine, the SUS disk as partner material, after fully fit sliding, and the inertia 12.5kgm ^2, initial velocity 200km / h, the hydraulic pressure 1.96MPa, braking number of times 3 times This is the angle at which the torque suddenly increases again immediately after the start of braking of the torque curve measured under the test conditions, 2.4 seconds per cm with the horizontal axis as the time axis and 1 cm with the vertical axis as the torque axis. Recorded as 250 Nm .

  According to the present invention, excellent friction performance is maintained as a friction material that brakes a high-speed vehicle or the like at a high reduction ratio to decelerate and stop, and the brake is smoothly braked to provide a high braking effectiveness (braking feeling) to the occupant. There is provided a copper-based sintered friction material capable of providing Therefore, it is extremely useful as a copper-based sintered friction material used for brake lining and clutch facing for braking at high speed.

The copper-based sintered friction material of the present invention is characterized in that it contains a large amount of iron and iron-containing stainless steel containing copper as a main component. That is, the metal component used as a matrix is tin powder; 0.5-15 mass %, zinc powder; 0.1-30 mass %, nickel powder; 5-25 mass %, iron powder; 5-25 mass %, stainless steel It consists of steel powder; 0.1-20 mass %, copper powder; balance.

As the matrix metal component, the tin powder is set in the range of 0.5 to 15% by mass because when the tin powder is less than 0.5% by mass , the material becomes brittle and easily causes adhesion, and 15% by mass . This is because the friction coefficient decreases and the wear increases. Further, to the zinc powder 0.1 to 30% by weight, reduces the coefficient of friction with the material becomes brittle is less than 0.1 wt%, whereas, increased wear and exceeds 30 mass%, further, The reason why the nickel powder is 5 to 25% by mass is that when the content is less than 5% by mass , the friction coefficient decreases, and when the content is more than 25% by mass , the strength decreases and wear increases. Furthermore, it is preferable to contain 0.1 to 5% by mass of manganese powder, but when the content exceeds 5% by mass , the material becomes hard and the attacking property to the counterpart material becomes high.

In addition to this component composition, the copper-based sintered friction material of the present invention sets iron powder to 5 to 25% by mass , stainless steel powder to 0.1 to 20% by mass , and the balance to copper powder. The total amount of powder and stainless steel powder is adjusted to a range of 8 to 28% by mass . When the iron powder is less than 5% by mass and the stainless steel powder is less than 0.1% by mass , the friction coefficient is low, and when the iron powder exceeds 25% by mass and the stainless steel powder exceeds 20% by mass, the wear resistance and fade resistance deteriorate. It will be. When the total amount of iron powder and stainless steel powder is less than 8% by mass, the strength and build-up rate are low. On the other hand, when it exceeds 28% by mass , the strength is decreased, the build-up rate is decreased, and the fade resistance is reduced. Getting worse.

  In the present invention, the use of iron powder and stainless steel powder containing iron as a matrix metal component is one of the main constituents, and the iron component of iron powder and stainless steel powder shrinks during sintering. It functions as a component that has a small rate and inhibits sinterability. That is, from the result of the structure observation by the SEM image, in the metal matrix, fine voids of about 0.5 to several μm are confirmed around the iron component, and these voids are similar to pores and abrasives in the sintered body. It is thought that it works.

High-purity iron powder is suitable, and electrolytic iron powder having a purity of 99% by mass or more is used. As the electrolytic iron powder, one having a particle size range of 40 to 150 μm, which has been heat-treated in a hydrogen gas or ammonia gas atmosphere at a temperature of 600 to 1200 ° C., is used. When the particle size is less than 40 μm, the friction coefficient decreases. When the particle size exceeds 150 μm, the strength decreases and the build-up rate decreases, and the attacking property against the counterpart material also increases.

The copper-based sintered friction material of the present invention comprises a composition of 55 to 80% by mass of the matrix metal component and 20 to 45% by mass of a filler component such as a lubricant and a friction modifier, and has a build-up rate in a torque curve of 40. It is characterized by being at least degrees. However, the build-up rate, in the dynamo testing machine, the SUS disk as partner material, after fully fit sliding, and the inertia 12.5kgm ^2, initial velocity 200km / h, the hydraulic pressure 1.96MPa, braking number of times 3 times This is the angle at which the torque suddenly increases again immediately after the start of braking of the torque curve measured under the test conditions, 2.4 seconds per cm with the horizontal axis as the time axis and 1 cm with the vertical axis as the torque axis. Recorded as 250 Nm .

  In other words, the build-up rate eliminates the disadvantage that it is difficult to detect a smooth and sufficient braking force due to the impact of a sudden braking force when braking a high-speed vehicle or the like with a high reduction ratio and then decelerating and stopping. The present inventor has indexed the smoothness and sufficient braking effectiveness (braking feeling) felt by the occupant and is measured by the following method.

  When using a dynamo testing machine to brake a disk pad with a friction material on a metal disk against a rotor at a constant pressure and decelerate from a predetermined speed, the torque exerted by the brake pad against time When plotted, it changes as schematically shown in FIG. That is, in FIG. 1, the horizontal axis is the elapsed time since the pressure was applied, the vertical axis is the magnitude of the torque, and the torque curve showing the change with time of the torque varies depending on the material of the friction material and the braking condition, Specifically, it is represented by the pattern shown in FIG.

  That is, regardless of the material of the friction material and the braking conditions, as shown in FIG. 1A, the torque rapidly increases immediately after the start of braking, and once reaches a peak at B, it gradually decreases as in C. Thereafter, the torque increases rapidly again like D, and then gradually decreases like E toward deceleration and stop, and finally the torque becomes zero and stops.

Then, the torque increases immediately after the start of braking in FIG. 1 and after the peak B has elapsed, after C when the torque gradually decreases, the build-up rate has an angle of D at which the torque rapidly increases again. Define That is, a tangent line F is drawn to a point where the slope of D is maximized, and an angle θ between the tangent line F and a horizontal line is defined as a build-up rate. When the build-up rate is 40 degrees or more, the occupant can obtain a smooth and sufficient braking effect (braking feeling) during braking. In FIG. 1, the build-up rate is obtained by recording a torque curve at 2.4 N / cm with the horizontal axis as the time axis and 250 Nm per cm with the vertical axis as the torque axis as described above.

The filler, which is a filler component, is a powder such as graphite, MoS ₂ , CaF ₂ , BaF ₂ , BN, fluorinated graphite and mica, and the friction modifier is a metal such as Al ₂ O ₃ , SiO ₂ , ZrO _2. Hard particles such as oxide, metal nitride such as Si ₃ N ₄ , metal carbide such as SiC, or coke, barium sulfate, diatomaceous earth, or the like is applied.

  In addition, silicon carbide fiber, carbon fiber, silicon carbide whisker, boron fiber, silica-alumina fiber, glass fiber, aramid fiber, brass fiber, steel fiber, other inorganic fibers and metal fibers are added to these components as necessary. It can also be added as a reinforcement.

  The copper-based sintered friction material of the present invention is prepared by mixing each metal powder serving as a matrix metal component, a lubricant serving as a filler component, a friction modifier, and the like at a predetermined ratio, forming a mixed powder, and then sintering. Manufactured by.

  Examples of the present invention will be specifically described below in comparison with comparative examples.

Examples 1-5, Comparative Examples 5-6
For each powder of copper, tin, zinc, nickel, manganese, iron and stainless steel as matrix metals, use CaF ₂ as a lubricant, graphite, zircon sand as a friction modifier, and alumina powder, and change the mass ratio. Mixed. As the iron powder, electrolytic iron powder having a purity of 99.5% was used, which was heat-treated in hydrogen gas at a temperature of 900 ° C. and adjusted to a particle size range of 40 to 150 μm.

  The mixed powder was formed into a predetermined shape, and the formed body was placed on a copper-plated steel plate and sintered at a temperature of 850 ° C. in a reducing atmosphere to prepare a test material for a copper-based sintered friction material.

Each test material was subjected to a dynamo test using a SUS disk as a counterpart material. The test conditions were such that the friction material characteristics were measured by changing the initial speed and the deceleration after changing the initial speed and the deceleration to 12.5 kgm ² . The friction coefficient is the initial speed: 200 km / h, the hydraulic pressure: 0.98 MPa, the number of braking times: 3 times, and the build-up rate is the initial speed: 200 km / h, the hydraulic pressure: 1.96 MPa, the braking frequency: 3 times. Measured under conditions.

Comparative Examples 1-4
In the examples, copper powder was prepared in the same manner as in the examples, except that the mixed powder was prepared by changing the mixing ratio without using heat treatment in hydrogen gas as iron powder and using electrolytic iron powder having a different particle size range. A test material of the system sintered friction material was produced and its characteristics were measured.

  The results obtained in this manner are shown in Table 1 for the preparation conditions of test materials for copper-based sintered friction materials, and Table 2 shows the measurement results of the friction characteristics.

  From the results shown in Tables 1 and 2, the friction material of the example has high strength, and the performance as a friction material such as the wear amount and the friction coefficient is also high, and the braking effectiveness sensed during braking indexed in the present invention ( The build-up rate indicating a braking feeling) is 40 degrees or more, which indicates that it is suitable as a copper-based sintered friction material that brakes a vehicle at high speed and high output at a high speed. On the other hand, it is recognized that the friction material of the comparative example that does not satisfy the requirements of the present invention is inferior in strength, wear amount, friction coefficient, buildup rate, and the like.

It is a schematic diagram of the torque curve which shows the time-dependent change of the torque measured with the dynamo testing machine.

Claims (3)

Tin powder; 0.5 to 15 wt%, zinc dust; 0.1 to 30 wt%, nickel powder; 5-25 wt% iron powder; 5-25 wt%, stainless steel powder; 0.1 to 20 mass %, Copper powder; the balance is composed of a sintered body in which the matrix metal component is 55 to 80% by mass , and filler components such as a lubricant and a friction modifier are 20 to 45% by mass ,
(1) The total amount of iron powder and stainless steel powder is 8 to 28% by mass
(2) Electrolytic iron powder having a particle size range of 40 to 150 μm, wherein the iron powder is heat-treated at a temperature of 600 to 1200 ° C. in an atmosphere of hydrogen gas or ammonia gas,
A copper-based sintered friction material. The copper-based sintered friction material according to claim 1, comprising 0.1 to 5% by mass of manganese powder as a matrix metal component. The copper-based sintered friction material according to claim 1 or 2, wherein a build-up rate in a torque curve is 40 degrees or more.
However, the build-up rate, in the dynamo testing machine, the SUS disk as partner material, after fully fit sliding, and the inertia 12.5kgm ^2, initial velocity 200km / h, the hydraulic pressure 1.96MPa, braking number of times 3 times This is the angle at which the torque suddenly increases again immediately after the start of braking of the torque curve measured under the test conditions, 2.4 seconds per cm with the horizontal axis as the time axis and 1 cm with the vertical axis as the torque axis. Recorded as 250 Nm .

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