JPH10137920A - Production of brake disk composite material for railway vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method for a brake disk composite material for railway vehicle dispersing ceramic particles into aluminum alloy as a matrix. SOLUTION: In a process for producing a cast block by depositing and solidifying the unsolidified fine powders atomizing molten aluminum alloy with inert gas on a base board, the composite dispersing 5-30wt.% particles in the aluminum alloy matrix by mixing the ceramic particles having 1-20μm average particle diameter into the molten atomizing, is made to the block and press-worked. As this matrix, the aluminum alloy of the alloy containing 2-5% Mg, 0.1-1% Mn and 0.05-0.35% Cr or the alloy containing 5-10% Fe and 0.2-3% total of one or more kinds among V, Mo, Zr, Ti, Cr, Mn or Ni or the alloy containing <=4% total of one or more kinds among Cu, Mg, Fe, Ni, Mn, Cr, Ti, Zn or Zr, etc., is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a disk of a disk brake for mechanically obtaining a braking force by friction used in a railway vehicle.

[0002]

2. Description of the Related Art There are block brakes, drum brakes, disc brakes, and the like as mechanical braking systems for railway vehicles, automobiles, motorcycles, and the like. It has come to be. This disc brake is a device that obtains a braking force by friction between a brake disc and a brake lining (friction material). For example, in the case of a railway vehicle, a donut-shaped disk-shaped sliding surface and its sliding surface are used. A base is mounted on a rotating part such as a wheel while supporting the surface at a rear portion, and a braking force is obtained by pressing a brake lining against a sliding surface that is rotating during traveling. A disc-shaped component having this sliding surface is called a brake disc.

[0003] The material used for the brake disk has abrasion due to friction during braking and a sharp temperature rise.
Abrasion resistance, heat resistance, and heat crack resistance are required. The thermal crack is a thermal fatigue crack generated due to repetition of thermal stress generated at each braking.

Conventionally, cast iron, forged steel, stainless steel and the like have been used for this brake disc. However, due to demands for higher speed of vehicles, weight reduction as an energy saving measure to protect the global environment, and improvement of ride comfort by reducing unsprung weight, there has been a trend to use aluminum and aluminum alloy for brake discs. Was. Aluminum and aluminum alloys are significantly inferior in wear resistance, heat resistance, and heat crack resistance as compared to cast iron and forged steel, but because the thermal conductivity is good, the generated frictional heat is quickly dissipated, It is possible to keep the temperature rise of the sliding surface much lower than the steel brake disc. Therefore, the heat resistance and the heat crack resistance do not decrease as much as estimated from the material strength. However, since the strength is low, the wear resistance is significantly poor, and it has been said that it is difficult to apply aluminum or an aluminum alloy itself to a brake disc.

However, as a method for improving the wear resistance of an aluminum alloy itself, Japanese Patent Application Laid-Open No. 59-173234 discloses a method of improving the wear resistance of a particulate or fibrous aluminum alloy for automobiles and motorcycles.
There has been proposed an invention of a brake rotor (disk) in which ceramics such as ₂ O ₃ , SiC, and Si ₃ N ₄ are dispersed. Japanese Patent Application Laid-Open No. 2-25538 discloses that an aluminum metal matrix having a particle size of 5 to 100 μm is used for railway vehicles.
The invention of a brake disk material in which the reinforcing particles of the above are dispersed in the range of 1 to 7% by weight is disclosed. Further, Japanese Patent Application Laid-Open No. 3-47945 discloses that The invention has been presented. Since these materials have poor castability and forgeability, Japanese Patent Application Laid-Open No. 8-176712 discloses an invention in which magnesium or nickel is added to a matrix aluminum alloy to improve the aluminum alloy.

[0006] All of these composite materials developed for use as brake discs in railway vehicles are manufactured by the compo-cast method. The compo-cast method is a method of dispersing particles such as non-metals in a metal, lowering the molten metal to near the melting point, stirring it in a semi-solid state, mixing particles that are not easily compatible with the molten metal, and dispersing and solidifying it. Things.
Therefore, there is a problem that the molten composite material has extremely poor fluidity, and it is difficult to obtain a sound material when a large cast product such as a railway brake disk is used. This method makes a simple ingot of shape and forges it,
Although there is a method of molding into a required shape, cracks due to forging are liable to occur when a large number of particles having poor compatibility with the matrix metal are contained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to apply a composite material in which ceramic particles having an aluminum alloy as a matrix are dispersed as a brake disk of a railway vehicle. An object of the present invention is to provide a method of manufacturing a brake disk from a material which is small, uniform, and has excellent workability such as forging.

[0008]

The present inventors have paid attention to the features of the aluminum alloy matrix composite and have studied various applications as a material for a brake disk of a railway vehicle. A method of manufacturing a composite material in which aluminum or an aluminum alloy is used as a matrix and in which hard ceramic particles and the like are dispersed includes a powder metallurgy method in which raw material powders are mixed and compressed and sintered at a high temperature. There are laws. Although these methods can be effectively applied to relatively small components, various problems arise when the object becomes large.

A brake disk for a vehicle which is large as a composite material and which is required to withstand performance under severe operating conditions is important for its internal soundness and mechanical properties. It is desirable to adopt forging processing. In the powder metallurgy method, if the size is large, it takes too much cost, such as enlargement of equipment, to manufacture the whole uniformly, and the workability, such as forgeability, is poor. Also,
Since the casting temperature of the aluminum alloy is too low in the compocast method, there is a concern about the soundness of the ingot when the casting temperature is large, and in addition, cracks are easily generated by forging.

In order to address these problems, the present inventors have focused on a spray casting method which is considered to be applicable to an alloy having a chemical composition used in powder metallurgy to improve workability. In this method, a molten metal is sprayed with an inert gas, and droplet spray particles immediately before solidification are deposited on a substrate or injected into a mold to solidify.
Since the particles adhere in a semi-molten state, a material having a higher true density than that of the powder metallurgy method can be obtained, and a much more uniform and fine solidified structure can be obtained as compared with ordinary casting. The ceramic particles are mixed during the spraying of the molten metal and solidified together. In the component casting method, the composition of the particles is limited by the wettability of the mixed particles with the molten metal, and the particle diameter is also limited in order to obtain a uniform dispersion.However, according to the method for producing a composite material by this spray casting method, These restrictions are eliminated.

Since the ingot of the composite material obtained by the above-mentioned method applying the spray casting method, that is, the raw material before processing, is called a preform, the workability or forgeability of the composite material having the same composition is determined by powder metallurgy. It was much better than that produced by the method or component casting method. Then, as a result of subjecting the preform to hot pressing or hot forging, the true density ratio was improved, and the strength and elongation of the obtained material were greatly improved. The composite material produced in this manner was evaluated for various properties required for a brake disk for a railway vehicle, and it was found that the composite material produced was superior in performance to a composite material produced by a conventional method. .

[0012] Based on the above results, the influence of the composition of the aluminum alloy used as the matrix, the mixing amount of the ceramic particles, and the particle size, etc. on the properties and manufacturing problems were investigated, and the respective limitations were clarified. This led to the present invention. The gist of the present invention is as follows.

(1) In the process of depositing and solidifying unsolidified fine powder obtained by spraying a molten aluminum alloy with an inert gas on a base to form an ingot (preform), the average particle diameter of the molten aluminum spray during spraying is 1 By mixing ceramic particles of ~ 20μm, by weight% in aluminum alloy matrix
A method of manufacturing a composite brake disc for railway vehicles by forming a composite in which 5 to 30% of particles are dispersed and subjecting the composite to pressure processing.

(2) In weight%, Mg: 2-5%, Mn:
(1) The method of manufacturing a composite material brake disk for a railway vehicle according to (1), wherein the matrix contains 0.1 to 1% and Cr: 0.05 to 0.35%, and the balance is an aluminum alloy including Al and unavoidable impurities.

(3) Fe: 5 to 10% by weight, V,
A matrix containing at least one of Mo, Zr, Ti, Cr, Mn or Ni in a total amount of 0.2 to 3%, with the balance being an aluminum alloy composed of Al and unavoidable impurities.
The method for producing a composite brake disc for a railway vehicle according to (1).

(4) In weight%, Si: 5-10%, C
u, Mg, Fe, Ni, Mn, Cr, Ti, Zn or Zr in total of at least 4%, with the balance being Al
And a method for producing a composite material brake disk for a railway vehicle according to (1), wherein the matrix is an aluminum alloy comprising unavoidable impurities.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Alloy composition of matrix The aluminum alloy serving as the matrix of the composite material according to the method of the present invention may be pure aluminum for industrial use, and various alloys generally used as wrought materials, for example, JIS
Alloys such as H-4000 and H-4140. However, if the effects of the present invention are to be effectively utilized, it is necessary to use the following alloy depending on the purpose. The following chemical composition is% by weight in the aluminum alloy.

In the case where workability is particularly important simultaneously with the strength, Mg: 2 to 5%, Mn: 0.1 to 1%, and Cr: 0.05 to 0.35% are contained, and the balance is from Al and inevitable impurities. Alloy. These three elements are
Simultaneous inclusion can increase the strength of the matrix without impairing workability. However, when the content of each element is below the lower limit of the above range, the effect of improving the strength is small, and when the content exceeds the upper limit, the workability may be deteriorated and the corrosion resistance may be deteriorated.

In order to further increase the strength and improve the high-temperature stability, Fe is contained in an amount of 5 to 10%.
At least one of Mo, Zr, Ti, Cr, Mn or Ni is contained in a total amount of 0.2 to 3%, and the remainder is an alloy composed of Al and unavoidable impurities. Fe is contained in a preform manufactured by the spray casting method at 10 μm.
By forming fine intermetallic compounds of m or less, the strength can be greatly improved. If the content is less than 5%, the effect of increasing the strength is poor, and if it exceeds 10%, cracks tend to occur during forging. V, Mo, Zr, Ti, Cr,
A small amount of Mn or Ni stabilizes the Al-Fe intermetallic compound and improves the high-temperature strength. It is effective if any one or more of these elements are contained. However, if the total content is less than 0.2%, the effect is not sufficient, and if it exceeds 3%, there is a risk of cracking during forging.

In order to obtain a composite material having not only increased strength but also a higher friction coefficient and improved seizure resistance, it is necessary to use Si.
5-11%, and in addition to this, Cu, Mg, Mo, F
One or more of e, Ni, Mn, Cr, Ti, Zn or Zr are contained in a total of 4% or less, with the balance being an alloy matrix composed of Al and unavoidable impurities. The inclusion of Si not only increases the strength, but also increases the coefficient of friction,
It has the effect of improving the performance as a brake disc, such as improving seizure resistance. In the case of casting, coarse primary crystals are formed and cracks are easily generated at the time of forging. However, in the preform of the method of the present invention, crystal grains are refined and a large amount can be contained. If the content of Si is less than 5%, a sufficient effect cannot be obtained, and if it exceeds 11%, the forgeability deteriorates. Therefore, the content range is set to 5 to 11%. Cu, Mg, Mo,
Each element of Fe, Ni, Mn, Cr, Ti, Zn or Zr may not be added. However, by adding a small amount in addition to Si, the strength can be increased. When adding one or more, the total content of them is desirably 0.1% or more, and at most 4%. This is because if the content is less than 0.1%, the effect is not sufficiently exhibited, and if it exceeds 4%, the forgeability deteriorates.

(2) Ceramic Particles By uniformly dispersing hard ceramic particles in a matrix of an aluminum alloy, abrasion resistance, a coefficient of friction, and seizure resistance as a composite brake disk are exhibited. The ceramics may be any of oxides, carbides, and nitrides as long as the ceramics have sufficiently high hardness. For example, Al ₂ O ₃ , SiC, AlN, Si ₃ N _{4 and the} like can be applied.

The size of the ceramic particles is an average particle size of 1 to 20 μm. If the particle size is too small, less than 1 μm, the particles will not coagulate and disperse uniformly in the preform by the spray casting method, and the performance as a brake disc such as wear resistance and friction coefficient will not be sufficiently obtained. On the other hand, when the thickness exceeds 20 μm, not only the uneven distribution of particles in the preform tends to occur, but also the machinability deteriorates and the toughness also deteriorates.

The amount of ceramic particles in the composite material is 5 to 30% by weight. If the content is less than 5%, sufficient abrasion resistance and seizure resistance cannot be obtained, and if it exceeds 30%, cracks are liable to occur during forging, and the machinability also deteriorates.
Note that the desirable content range for obtaining excellent performance is 9
~ 23%.

(3) Production of a composite preform.

In manufacturing an ingot, that is, a preform, in which the ceramic particles are uniformly dispersed in an aluminum alloy matrix, an aluminum alloy having a predetermined chemical component is first melted to obtain a molten metal in a castable state. This molten metal is atomized and atomized with an inert gas such as nitrogen in the same manner as in a gas atomizing method for producing ordinary aluminum powder. When producing powder, the temperature and spray rate are selected so as to solidify while in the spray state.However, in the method of the present invention, the spray solidifies when deposited on the substrate and melts when in the spray state. To be.

The ceramic particles are mixed with an inert gas used for spraying, or are dispersed from a separately prepared nozzle onto a base on which a finely divided molten metal is deposited and solidified, through a nozzle prepared separately. In this case, the supply speed of the ceramic particles is adjusted to a predetermined content in accordance with the spraying speed of the molten metal.

In order to deposit the fine particles of the molten metal on the substrate immediately before solidification, for example, a molten metal spray nozzle is installed on the upper portion of the substrate,
Although the device structure is such that the substrate is moved downward according to the deposition rate, it is preferable to apply vibration such as rotation or oscillation to the substrate in order to make the deposition thickness uniform. Thereby, the structure of the matrix becomes finer, and the forgeability can be improved.

(4) Formation of Brake Disk The preform is formed into a brake disk shape by plastic working by hot forging or hot pressing followed by hot forging. In this case, the forging ratio is desirably 1.5 or more, and the performance is further improved at 2.0 or more. The forging ratio is the true number of the maximum strain among the main strains in three directions obtained from dimensional changes before and after forging or pressing. For example, in the case of the upsetting forging, it is expressed by a height ratio in a deformation axis direction before and after compression deformation or an area ratio of a cross section perpendicular to the deformation axis.

Although the true density ratio of the preform is about 97 to 99%, the plastic working with the forging ratio of 1.5 or more allows
The true density ratio becomes 99% or more, toughness and strength are improved, and the performance as a brake disk is improved.

[0030]

【Example】

[Example 1] When an aluminum alloy for a matrix having a chemical composition shown in A of Table 1 was melted, sprayed with an atomizing nozzle using nitrogen gas to form fine droplets, and deposited and solidified on a rotating disk-shaped substrate, At the same time, using a nitrogen gas as a carrier, SiC particles having an average particle size of 8 μm are jetted onto the same substrate,
About 180mm in diameter and about 900mm in height containing 12% SiC particles
Was produced.

A composite material containing the same SiC particles in a matrix having the same chemical composition as A in Table 1 was produced by a compo-casting method. In this case, after melting the aluminum alloy having the above composition, the above-mentioned SiC particles are added little by little with vigorous stirring while maintaining the temperature at 620 ° C. in a crucible so that the solid-liquid two-phase coexistence state is obtained. Thereafter, the temperature was lowered to 605 ° C. while continuing strong stirring, and poured into a mold to form an ingot having a diameter of about 120 mm and a height of about 130 mm.

[0032]

[Table 1]

From these preforms and ingots,
In each case, cut out a cylinder with a diameter of 100mm and a height of 100mm,
After being heated to 00 ° C., a kind of upsetting test was performed in which the cylinder was sandwiched between two flat plates by a hydraulic press and pressed vertically in the axial direction of the cylinder. At that time, the compression speed is 2mm / s
Then, the occurrence of cracks was observed by variously changing the forging ratio of the compression working. From the disc-shaped composite material after the compression processing, a JIS No. 4 type tensile test piece was cut out in the diameter direction, and a tensile test was performed at room temperature. In addition, the specific gravity of the composite material after the compression processing was measured, and the true density ratio was determined in comparison with the theoretical density.

Table 2 also shows the production method, the forging pressure ratio, and the test results. As can be seen from the comparison of these results, in the case of the preform by spray forming according to the present invention, no cracking is observed until the forging ratio is up to 3, but the forging ratio is increased in the ingot by compo-casting. Cracks occur. In the preform state, the tensile strength is low and the elongation is not good. However, as the forging pressure ratio increases, both the tensile strength and the elongation are greatly improved.

[0035]

[Table 2]

Example 2 A composite material preform comprising the matrixes of sample symbols B to Q in Table 1 and ceramic particles was prepared by a spray forming method. The dimensions of all preforms are about 180 mm in diameter and about 300 in height
mm. From these, a cylinder having a diameter of 100 mm and a height of 100 mm was cut out, and a forging pressure ratio of 2 was obtained under the same conditions as in Example 1.
Forging process. Sample symbols L, M, N, O, P and Q cracked at this stage and were not tested further. In any of these, the Al alloy of the matrix contained an alloy element exceeding the range included in a general wrought Al alloy, or was out of the composition range regulated by the present invention.

After the forging, a tensile test was conducted at room temperature using a JIS No. 4 type tensile test piece taken in the diameter direction, and a high-temperature tensile test was conducted at 300 ° C. for some of them.
The wear resistance was evaluated by a pin disk type abrasion tester in which a pin was pressed against a rotating disk to measure the amount of abrasion. The disk-shaped disk test piece had a diameter of 60 mm, the sliding radius of the pin was 16 mm, and the pin was a copper-based brake pad material having a diameter of 5 mm. The test conditions were: surface pressure: 1 MPa, friction speed: 5 m /
s, Lubrication: None, the friction time was 10 minutes, and the amount of wear was measured. For comparison, a test using a test piece cut from a preform in which forging pressure was not applied was also performed.

Table 3 summarizes these results. Test Nos. 13 to 18, 21 and 22 were produced by the method specified in the present invention, and had both excellent strength and elongation and very little wear. In contrast, Test No. 19 has excellent elongation, but has poor wear resistance. This is because the amount of the ceramic particles falls below the range defined by the present invention. If the amount of ceramic particles is too large, test number 20
As you can see, the growth is poor. When no forging is performed, as shown in Test Nos. 23 to 25, the wear resistance is good, but the strength and elongation are poor.

[0039]

[Table 3]

Example 3 A composite material having the same composition as the sample symbol A shown in Table 1 was prepared by a spray forming method to obtain a preform having a diameter of about 370 mm and a height of 500 mm.
From now on, a cylinder with a diameter of 350mm and a height of 450mm will be machined and 4
After heating to 30 ° C., it was forged by a hydraulic press and formed into a disk shape. In this case, the forging ratio exceeded 5, but molding was possible without cracking during forging. Thereafter, machining was performed to produce a brake disk having the shape shown in FIG. The diameter of the brake disc is 700mm and the height is 50mm at the maximum.

Using a wheel tester modeled on a bogie of the JR Shinkansen, a set of two brake discs was mounted on both sides of the wheel with the sliding surface outside, and a brake test was performed. As the brake lining material, a copper-based sintered alloy was used. The test was performed at an initial speed of 350 km / h with the brakes applied.
km / (h · s) constant deceleration, moment of inertia 1300kg ・ m ²
The load test was repeated 200 times under the following conditions. The results showed good performance without any problems such as cracking and abrasion.

[0042]

According to the method of the present invention, it is possible to manufacture a brake disk for a railway vehicle having excellent performance by using a composite material containing an aluminum alloy as a matrix.
The use of this significantly lighter brake disc, which has the same or better performance than steel brake discs used for conventional railway vehicles, not only contributes to energy saving by reducing the weight of the vehicle, It is also effective in improving ride comfort by reducing unsprung weight.

[Brief description of the drawings]

FIG. 1 is a view showing a top surface (1/4) and a cross section (1/2) of a composite brake disc for a railway vehicle according to an embodiment of the present invention.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22C 21/06 C22C 21/06 F16D 65/12 F16D 65/12 E (72) Inventor Seiichi Furuya Shimaya, Konohana-ku, Osaka-shi, Osaka 5-1-1 No. 109 Sumitomo Metal Industries, Ltd. Kansai Works Steel Works (72) Inventor Atsushi Sakaguchi 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries Co., Ltd. (72) Invention Person Taizo Makino Sumitomo Metal Industries Co., Ltd. 4-33, Kitahama, Chuo-ku, Osaka-shi, Osaka (72) Inventor Kazuhisa Shibue 5-1-1-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries, Ltd. (72) Inventor Yoshimasa Okubo 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Naoki Tokomi 5-1-1-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. Within the company

Claims (4)

[Claims] In the process of depositing and solidifying unsolidified fine powder obtained by spraying a molten aluminum alloy with an inert gas on a base to form an ingot, an average particle diameter of 1 to 20 μm is applied during the spraying of the molten metal.
A composite material in which 5 to 30% by weight of a particle is dispersed in an aluminum alloy matrix by mixing ceramic particles of the above, and the resulting mixture is subjected to pressure processing. Manufacturing method of brake disc. 2. Mg: 2 to 5%, Mn: 0.1% by weight.
11% and Cr: 0.05-0.35%, with the balance being A
The method for manufacturing a composite brake disc for a railway vehicle according to claim 1, wherein the matrix is an aluminum alloy comprising l and unavoidable impurities. 3. The method according to claim 3, wherein the content of Fe is 5 to 10% by weight,
o, Zr, Ti, Cr, Mn or at least one of Ni is contained in a total amount of 0.2 to 3%, and the balance is an aluminum alloy composed of Al and inevitable impurities,
A method for manufacturing the composite brake disc for a railway vehicle according to claim 1. 4. The method according to claim 1, wherein Si: 5 to 10% by weight, Cu, M
The aluminum alloy containing at least one of g, Fe, Ni, Mn, Cr, Ti, Zn or Zr in a total amount of 4% or less, and the balance being an aluminum alloy consisting of Al and unavoidable impurities as a matrix. Of manufacturing composite brake discs for railway vehicles.