JP3386322B2 - Method of manufacturing brake disk for railway vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a disk of a disk brake used in a railway vehicle and mechanically obtaining a braking force by friction, and more particularly to a conventional method. The present invention relates to a method for manufacturing a lightweight brake disc for a railway vehicle made of an aluminum composite material having the same wear resistance, heat resistance, and heat crack resistance as steel. [0002] Mechanical braking systems for railway vehicles, automobiles and motorcycles include block brakes, drum brakes, and disk brakes. Brakes have come to be used heavily. 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. FIG. 1 shows an example of the structure of the brake disk, and shows the upper surface (1/4) and the cross section (1/2) of the brake disk. As is clear from the figure, the brake disc is integrally formed with a sliding surface against which a brake lining (friction material) is pressed and a bolt hole for attachment. In general, a material used for a brake disk is required to have abrasion resistance, heat resistance, and heat crack resistance because of abrasion due to friction during braking and a rapid temperature rise. The term "thermal crack" as used herein means a thermal fatigue crack generated by repetition of thermal stress generated at each braking. Conventionally, brake disks include cast iron, forged steel,
One piece, such as stainless steel, has been used. However, due to demands for higher vehicle speeds, lighter weight as an energy saving measure to protect the global environment, and improved riding comfort by reducing unsprung weight, there is a tendency to use aluminum and aluminum alloys for brake discs. is there. For example, an aluminum-based composite material in which ceramic particles are dispersed has been used for an automobile brake disk in order to improve the wear resistance while reducing the weight of the brake disk. [0005] Usually, the method of producing an aluminum-based composite material can be roughly classified into a molten metal method and a powder method, but the molten metal method is widely used industrially, and among them, a casting method is frequently used. In the manufacture of brake discs, aluminum-based composite materials manufactured by the casting method are often used because the existing manufacturing equipment is available and the Near Net Shape molding is easy. ing. However, in a brake disk made of the aluminum-based composite material manufactured by the above-described casting method, it is difficult to uniformly disperse the ceramic particles, and thus there is a problem that the wear characteristics of the disk are not stable. Further, the strength of the brake disk is improved by the heat treatment, and a predetermined strength is secured.
Therefore, when the brake disk is used under normal conditions for an automobile, heat resistance and heat crack resistance do not matter. However, when used as a brake disk for railway vehicles that require higher load and longer durability, the strength improvement by heat treatment is gradually released during use under severe conditions, and finally thermal cracks there is also a problem that to occur. Further, in order to secure the strength, a method of forging a composite material manufactured by a casting method is also considered. However, such a method cannot be adopted because a trouble such as a forging crack occurs. [0006] In order to solve the above problems, many methods have been proposed in the past. For example, Japanese Patent Publication No. 7-07415 proposes a method of manufacturing a brake disk using powder of an aluminum-based composite material. The main purpose of this proposed manufacturing method is to reduce the cost of a brake disc composed of an aluminum-based composite material. After that, a plurality of disc members are formed by cutting perpendicularly to the axis, and the disc members are hot-cross-rolled (see FIG. 4 described later). [0007] However, the composite material produced by the proposed method is only a compact having insufficient bonding between particles in a metallurgical manner. Tends to occur. For this reason, in hot cross rolling, the rolling reduction must be kept low, and it is difficult to satisfy the characteristics required for the railway vehicle brake disc used under the severe conditions described above. Also, with that the brake disk for rail vehicles having a complex shape, having a large size is required to dimensionally. In addition, since the composite material manufactured by the proposed method is difficult to process and can produce only a disk-shaped disk, there is a problem that the proposed method requires a large cost for machining after cross rolling. SUMMARY OF THE INVENTION The present invention is an improvement of a method for producing an aluminum-based composite material by a powder method, which has been regarded as a problem of the prior art, and is light without causing forging cracks. capacity, high strength is worn, moreover conventional steel equivalent wear resistance, heat resistance, and to provide a method for manufacturing a composed brake disc from the aluminum-based composite material having a thermal crack properties The purpose is. When a powder method is used as a method of manufacturing an aluminum-based composite material used for a brake disk for a railway vehicle, it is premised that a required high strength level is secured. As a material property, the dispersion of the particles is uniform, and it is expected that other properties are improved as compared with the aluminum-based composite material manufactured by the casting method. The present invention has been completed based on such an aspect, and its gist lies in the following method for manufacturing a brake disk for a railway vehicle. [0010] That is, the "aluminum alloy and method for producing a railway vehicle brake disc constituted a mixed powder of an aluminum-based composite material produced by forging later by sealing entering City hot pressing in a sealed can of the ceramic In addition, the sealed can is not removed after the high-temperature press treatment, and the mixed powder is kept in a sealed state of 40% or more in a state where the mixed powder is sealed .
It is a manufacturing method of a brake for rail vehicles disks ", characterized in that it is forged at a reduction rate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will now be given of a brake disk constituting material used for a railway vehicle, that is, an aluminum-based composite material and a method of manufacturing the same, which are features of the method of the present invention. (1) Material for Brake Disc The material for the brake disc is a material in which particulate or fibrous ceramics are dispersed in an aluminum alloy as a matrix material. If the volume ratio of the ceramic to be dispersed is too low, the wear resistance is not sufficiently satisfied, and if it is too high, the toughness is reduced, and the machinability is deteriorated, so it is preferable to be in the range of 5 to 30%. . In particular, the volume ratio of the ceramic is more desirably in the range of 10 to 20%. As ceramic materials, SiC, Al ₂
Although such O ₃ and the like, the hardness of the ceramic material, SiC is most appropriate to the characteristics of thermal conductivity such as brake discs. Further, the shape may be either particulate or fibrous, but particulate is desirable in order to reduce the anisotropy of the composite material. The aluminum alloy used as the matrix material of the brake disc may be selected from aluminum alloys for forging as specified in JIS-H-4140. At this time, when used as a casting material, if the amount of Si in the aluminum alloy as the matrix material is not large (for example, 1
(0% or more), there is a possibility that SiC particles as a reinforcing material may be melted in the matrix during melting before casting. However, when the powder method is adopted as in the method of the present invention,
It is not necessary to consider the situation where the SiC particles are melted in the matrix material, and there is no particular restriction on such material components. However, since the disk temperature becomes high in the actual brake braking state, a material having high high-temperature strength (for example, Al-
It is desirable to use an Mg-based aluminum alloy). [0015] (2) Manufacturing Method FIG 2 is a diagram showing a flowchart of a brake disc production process of the present invention described in Examples below, shows one example of a manufacturing method of the present invention. As shown in the figure,
Powder mixed aluminum alloy powder and ceramic particles or fibers is a matrix material is sealed entry into the hermetically sealed housing, is then hot pressing, the aluminum-based composite material. Next, in order to further increase the strength of the composite material , forging is performed at a rolling reduction of 40% or more in a state where the mixed powder, that is, the composite material is sealed, without removing the sealed can enclosing the mixed powder. [0016] The high-temperature press treatment increases the filling ratio of the mixed powder and crushes the oxide film on the surface of the particles, so that the bonding between the particles is strengthened. As a result, the forgeability of the manufactured aluminum-based composite material is improved to some extent. However, in order to obtain sufficient strength and a required disk shape, it is necessary to further perform forging, and it is necessary to secure a reduction ratio of 40% or more in forging at this time. On the other hand, if forging is performed after removing the can enclosing the composite material after the high-temperature press treatment, forging cracks are likely to occur, and a rolling reduction of 40% cannot be secured. On the other hand, when forging is performed in a state where the composite material is sealed in a can, such a problem is solved, and forging can be sufficiently performed even when the rolling reduction is 40% or more. There are various methods for high-temperature pressing.
Generally, HIP processing is frequently used. When performing the HIP treatment, if the treatment pressure is low, the filling rate and strength of the material to be molded become insufficient, which is not preferable. On the other hand, the effect is saturated even if a certain processing pressure is applied.
It is preferable in the range of ~1200kgf / cm ^2. Further, if the treatment temperature in the HIP treatment is low, the above effect cannot be expected.On the other hand, if the treatment temperature is high, the mixed powder is melted, and the distribution of the ceramic particles or fibers may become non-uniform. It is preferable to set the processing temperature. Furthermore, the effect of the HIP processing is short if the time is short, and the effect is saturated even if the time is longer than a certain time. Therefore, the time is preferably in the range of 30 minutes to 2 hours. In some cases, it is effective to employ another processing method as the high-temperature pressing. In other words, the size of the brake disc used in railway vehicles is about 700 mm in diameter, and it is necessary to ensure that the material has a size of about 500 mm before forging, but equipment required for HIP processing of this size of material Costs and manufacturing costs are enormous. For this reason, as shown in FIG. 2 described above, after increasing the powder filling rate by CIP processing as a high-temperature pressing processing,
A method of performing hot pressing is effective. When employing the CIP process, the filling rate of the material processing pressure to be molded is less than 500 kgf / cm ² is low, whereas, the process pressure is 2000 kgf / c
Since effect exceed m ² is saturated, it is in the range of 500~2000kgf / cm ^2. In particular, it is desirable to perform CIP treatment in a pressure range of 1200 to 1800 kgf / cm ² . When hot pressing is performed after the CIP treatment, if the pressure is low, the effect of the hot press is low, and if the pressure is high, the mold may be damaged. Therefore, the processing pressure is 1500 to 3500 kg.
f / cm ² , especially 2700-3200 kgf / cm ²
Is desirable. If the heating temperature of the hot press is low, the effect is low, and if it is high, the mixed powder may melt and the distribution of ceramic particles or fibers may become uneven,
The temperature should be in the range of 350 to 550 ° C. [0020] In the production method of the present invention, later mixed powder was sealed entrance City hot pressing in sealed cans, after the sealed can is hot pressing Without being removed, 40% a mixed powder in a sealed off to the state It is characterized by being forged at the above reduction ratio . As described above, during forging, when the molded material is removed from the sealed can and forging occurs, forging cracks are likely to occur, the reduction rate cannot be increased to a certain level or more, and the strength of the composite material can be sufficiently increased. It becomes difficult. For this reason, forging is performed in a state where the material is sealed without removing the sealed can. At this time, if the thickness of the sealed can is thin, cracks occur during forging, and if it is thick, only the can is forged during forging. Therefore, the thickness of the can is preferably 6 to 40 mm. In particular, it is desirable to set it to 11 to 30 mm. The material of the sealed can may be selected from aluminum alloys for forging specified in JIS-H-4140.
Alloys 6061 and A6063 are particularly desirable because of their excellent toughness and ductility. As described above, in order to have sufficient strength with the manufactured aluminum-based composite material and obtain a required disk shape, it is necessary to secure a rolling reduction in forging of 40% or more. In particular, if the rolling reduction during forging is 60% or more, sufficient strength can be ensured, so that it is more desirable. Also, if the strain rate in the forging process is low, the productivity will deteriorate, and if the strain rate is too high, cracks will easily occur during forging, so it should be in the range of 10 ^-2 to 10 ¹ s ^-1. Good. In particular, 10 ^-1
10 ⁰ is preferable to forge at s ^-1 of about strain rate.
If the heating temperature during forging is low, the forgeability deteriorates and cracks easily occur.If the heating temperature is high, the material is melted, the distribution of ceramic particles or fibers becomes uneven, and cracks may occur. Desirably, it is in the range of 〜550 ° C.
In particular, it is desirable to forge at a heating temperature of about 450 ° C. The forged aluminum-based composite material is machined as required to be processed into a required shape. At this time, there is no problem even if the aluminum alloy used as the sealed can remains except for the sliding surface of the brake disk. EXAMPLES The effects of the method of the present invention will be described in comparison with examples of the present invention and comparative examples. (Example of the Present Invention) FIG. 2 is a flowchart showing a method of manufacturing a brake disk employed in an example of the present invention. In the example of the present invention, a brake disk for a railway vehicle having the shape shown in FIG. 1 was manufactured by the above manufacturing method. The matrix material of the composite material includes samples 1 to
Three types of aluminum alloys 3 were used. Sample 1 is an Al-Mg JIS A5083 aluminum alloy, Sample 2 is Al8Si1Cu to which 8% by weight of Si and 1% by weight of Cu are added, and Sample 3 is 8% by weight of Fe and 1% by weight of V Added Al8Fe
1V. SiC particles having an average particle size of 5 μm were used as the reinforcing material, and the volume ratio was 10%. Using samples 1 to 3 as matrix materials and aluminum-based composite materials manufactured by the manufacturing method shown in FIG. 2 as examples 1 to 3, their general characteristics are shown in Table 1. [Table 1] Various experiments were conducted during the production of the composite material. First, three kinds of aluminum alloy powder and SiC
Particles, each having a thickness of 30 mm and a diameter of 500 m.
m, sealed in a sealed can made of an aluminum alloy of material A6063, and subjected to vacuum degassing. Next, after performing CIP processing and hot pressing, forging was performed.
At this time, the CIP treatment is performed at a pressure of 1530 kgf / cm ^2.
The hot press is 450 ° C and the pressure is 3055kgf
/ Cm ² . The forging was performed under the conditions of a heating temperature of 450 ° C. and a strain rate of 10 ⁻¹ s ⁻¹ .
By the CIP process and the hot pressing, the filling ratio of the mixed powder is about 80% in the CIP process and 99% or more in the hot press, respectively, and the material before forging has a diameter of 500%.
mm and a disk having a thickness of 260 mm. Thereafter, by forging, for example, a disc having a diameter of about 750 mm and a thickness of about 105 mm was formed at a draft of about 60% . In the above-mentioned forging, the relationship between the thickness of the sealed can and the forgeability was investigated. Table 2 shows Example 1 (sample 1).
+ SiC particles) are shown. As is clear from the table, when forging is performed while being sealed in a can, good forgeability can be obtained without forging cracks. In particular, the thickness of the sealed can is desirably in the range of 11 to 30 mm. In the table, the case where the thickness of the can is set to 0 mm indicates the result when the can is removed after hot pressing and forging is performed. In this case, forging cracks occurred at a rolling reduction of 30%. In other processing, in Example 2, the rolling reduction was 35%.
In Example 3, forging cracks occurred at a rolling reduction of 20%, and forging could not be performed. [Table 2] FIG. 3 is a diagram showing the relationship between the rolling reduction and the tensile strength in forging in Example 1. Reduction rate 50%
By adding, a high strength level with a tensile strength of 350 MPa was obtained, and the elongation was about 14%. Therefore, it can be seen that thereafter, by manufacturing the brake disk by machining, a disk having excellent wear resistance can be obtained. (Comparative Example) For comparison, the sample 1 was mixed with a matrix material of a composite material by a powder method and a casting method.
A brake disk shown in FIG. 1 was manufactured using an Al-Mg alloy or an Al-Si alloy in the same manner as in the example of the present invention. As for the powder method, the above-mentioned Japanese Patent Publication No.
The manufacturing method proposed in Japanese Patent No. 107415 was adopted. That is, the powder of the aluminum alloy of Sample 1 and the SiC particles were mixed, placed in a cylindrical container made of an aluminum alloy, compressed in the axial direction, and then cut perpendicularly to the axis to obtain a plurality of circles. A plate member was formed, and the disk member was hot-rolled cross-rolled. At this time, the rolling reduction is 20% by cross rolling.
Then, the disk (compact) cracked, so the rolling reduction was set to 10% in the cross rolling. After that, a brake disk was manufactured by machining, and Comparative Example 1 was obtained. In Comparative Example 1, the rolling reduction was low, the tensile strength was only about 200 MPa, and the abrasion resistance was inferior to those of the present invention. Next, in the casting method, since it is difficult to produce a composite material using an Al-Mg-based alloy such as Sample 1 as a matrix material, 10% SiC particles are produced using an Al-Si-based alloy as a matrix material. After sand-casting using the dispersed composite material, machining was performed to produce a brake disc, and Comparative Example 2
And The strength of Comparative Example 2 was about 140 MPa in tensile strength and about 0.8% in elongation, and it can be seen that the abrasion resistance was significantly lower than that of the inventive example. Table 3 shows the results of the brake test of the brake disks manufactured in the present invention and the comparative example. [Table 3] Examples of the present invention (Examples) 1 to 3, Comparative Examples 1 and 2
A brake test on a brake disk equivalent to that of a Shinkansen was performed on the brake disk to evaluate its durability. Brake initial speed 350km / h
Comparative Example 2 when the brake corresponding to
In Comparative Example 1, cracks occurred in the bolt hole edge after repeated braking twice and in Comparative Example 1 six times. In contrast, inventive examples 1 to
In No. 3, even when the brake was repeatedly applied 200 times, no damage such as cracks occurred and good performance was obtained. According to the manufacturing method of the present invention, forging cracks are
Weight without producing a high strength is worn, moreover conventional steel equivalent wear resistance, heat resistance, brake <br/> disc composed of an aluminum-based composite material having a thermal crack properties it is possible to easily provide a click.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example showing a structure of a brake disk, showing an upper surface (1/4) and a cross section (1/2) of the brake disk. FIG. 2 is a view showing a flowchart of a method of manufacturing a brake disk employed by an example of the present invention. FIG. 3 is a view showing a relationship between a draft and a tensile strength in forging in Example 1. FIG. 4 is a view showing a flowchart of a method of manufacturing a brake disk proposed in the prior art.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F16D 65/12 F16D 65/12 E (72) Inventor Hiroshi Higashiguchi 5-1-1109 Shimaya, Konohana-ku, Osaka-shi, Osaka Sumitomo Metal Industries Kansai Works Co., Ltd. Steel Works (72) Inventor Sei Furuya 5-1-1109 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd.Kansai Works Steel Works Co., Ltd. (72) Inventor Yoshimasa Okubo Tokyo 5-11-3, Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Hiroki Ezaki Inventor, 5--11-3, Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. (72) Naoki Minami 5-1-1-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Akio Kikuchi 5-1-1-3, Shimbashi, Minato-ku Tokyo, Sumitomo Light Metal Industries Co., Ltd. (56) References JP-A-6-147240 (JP, A) JP-A-63-169340 (JP, A) JP-A-9-125179 (JP, A) JP-A 9-184037 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) B22F 3 / 14,3 / 15 B22F 3 / 17,5 / 00 C22C 1/05 F16D 65/12

Claims (1)

(57) Rail consists Patent Claims 1 aluminum alloy and aluminum-based composite material produced by forging later mixed powder was sealed entrance City hot pressing in a sealed can of the ceramic a method of manufacturing a vehicle brake disc, the sealed can is without being removed after the high-temperature pressing, train, characterized in that it is forged at more than 40% of reduction ratio while still encapsulating the powder mixture A method for manufacturing a brake disc for a vehicle.