JPH0285526A - Rotor for disc brake - Google Patents

Abstract

PURPOSE:To provide a disc brake rotor having a thermal crack resistance, a vibration suppressing ability and a wear resistance which are excellent, by forming a disc brake from a flake graphite cast steel containing specific weight percents of C, Si, Mn, and Mo, a specific weight percent of Ti as necessary, and the remainder of Fe and impurities and having a pearlite basic structure. CONSTITUTION:A disc brake rotor 1 is formed of flake graphite cast steel containing 3.5 to 4.0wt.% of C, 1.6 to 2.0wt.% of Si, 0.5 to 0.8wt.% of Mn, 0.4 to 1.2wt.% of Mn, 0.05 to 0.10wt.% of Ti as necessary, and remainder of Fe and impurities and having a pearlite basic structure. Accordingly, the disc brake rotor 1 is excellent in thermal crack resistance, vibration suppressing ability and wear resistance. In particular, the following excellent advantages can be obtained: When the rotor is used in such a way that braking during high speed running is repeated several times, no thermal crack occurs while sounding upon braking may be low.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention relates to a disc brake Rogue which has excellent heat crack resistance, vibration damping properties and wear resistance and is particularly used in disc brake devices of vehicles such as automobiles. (Prior Art) In general, there is a rotor for a heavy vehicle disc brake having a structure as shown in FIG. 1, for example. This disc brake rotor 1 has a sliding part 2 and a fastening part 3, the sliding part 2 has a ventilation hole 2a, and the fastening part 3 has a plurality of bolt holes 3a for mounting. (Regarding this type of disc brake rotor, see 1.
ed.> It is described on pages 2-13 to 2-14, published by Automobile Tokyo Technical Association, Inc., on May 26, 1981. ). (Problem to be Solved by the Invention) By the way, as vehicles have become faster due to the improvement of the expressway network in recent years, there have been an increase in the number of vehicles being used that require repeated braking from the point of high-speed travel. , especially in regions such as Europe where expressways are developed and there are no speed limits, and the conventional rotor material JIS Fe12
Disc brake rotors made of (gray cast iron) do not rub! There is a possibility that thermal cracks will occur in section a, and the friction between the rotor and the pad may be transmitted to the driver as vibrations through the steering stirrup due to roughening of the rotor surface due to the cracks. The so-called brake squeal during braking is a problem related to brakes, but even if thermal cracking is solved, the squeal characteristics will be impaired. The wear resistance of the rotor often becomes a problem due to repeated braking.Therefore, rotors for disc brakes, especially for high-speed cars, have excellent heat cracking resistance and abrasion resistance, as well as suppressing noise or vibration. It is desired that the performance of the disc brake is not impaired, and there is a problem in that there is a desire to develop a material suitable for such a disc brake Kawaguchi-ter. This was made in view of the above-mentioned demands, and the object is to provide a rotor for disc brakes that has excellent thermal crack resistance, vibration damping properties, and wear resistance.

[Structure of the invention]

(Means for Solving the Problems) The disc brake rotor according to the present invention has a weight ratio of C: 3.5 to 4.0%, Si: 1.6 to 2.0%,
Mn: 0.5-0.8%, Mo: 0, 4-1.
It is characterized by a structure consisting of flake graphite cast iron containing 2% and 0.05 to 0.10% of TX2 as necessary, the balance consisting of Fe and impurities, and whose matrix structure is pearlite. This disc brake rotor configuration is a means for solving the above-mentioned conventional problems. Hereinafter, the disc brake rotor according to the present invention will be explained in more detail. Generally, it is known that the heat cracking resistance of cast iron is affected by high temperature strength, Young's modulus, thermal conductivity, coefficient of thermal expansion, etc. That is, the heat crack resistance is determined by the material strength under heat load and the thermal stress due to volume change in a state where strain caused by heat load is restrained. However, the IW ratio, where these material properties affect heat cracking resistance, varies greatly depending on the part.
The required material strength differs depending on the part. Therefore, we investigated the material properties necessary for heat cracking resistance of Rogue for disc brakes, and completed this invention. According to the studies conducted by the present inventors, it is clear that the most necessary property for the heat cracking resistance of a disc brake rotor is improvement in thermal conductivity, and that mere improvement in strength has little effect on the rotor's thermal cracking resistance. was made into In addition, in general, increasing the thermal conductivity of cast iron tends to decrease the strength, so it is necessary to improve the thermal conductivity and compensate for the strength without sacrificing the improvement in thermal conductivity. Something was also revealed. Furthermore, it has also become clear that the added element for strength compensation needs to be an element that can effectively compensate for the strength at the temperature at which thermal cracks occur in the rotor. ” - issued based on consideration of

The reasons for limiting the composition (weight %) of the materials that make up the disc brake rotor will be explained. C: 3.5 to 4.0% Generally, C is an element that improves the thermal conductivity of cast iron, and the Cl required for the material of the disc brake rotor according to the present invention is 3.5% or more. However, the amount of C is 4.
If it exceeds 0%, the composition will exceed the eutectic point, and coarse graphite will precipitate, reducing the strength and impairing heat cracking resistance. Therefore, the amount of C was set at 3.5 to 4.0%. Si: 1.6 to 2.0% Si dissolves in the matrix structure of cast iron and lowers the thermal conductivity, so it cannot be added in excess of 2.0%, and it is not possible to add a good flake shape. In order to precipitate graphite and maintain good wear resistance, it is necessary to add 1.6% or more. Therefore,
The amount of Si was set at 1.6 to 2.0%. Mn: 0.5-0.8% Mn is 0.5% to maintain the strength necessary for the rotor.
If the amount of addition exceeds 0.8%, M n S, which is detrimental to toughness, will precipitate in the matrix. Therefore, the Mn amount was set at 0.5 to 0.8%. Mo: 0, 4-1.2% MO is an element necessary for supplementing the strength of the rotor,
Elements other than MO are not effective in supplementing the strength to ensure heat cracking resistance of the rotor, and the effective addition amount for supplementing the strength is 0.4% or more, but if it exceeds 1.2%, it is costly. Not only is it not possible to obtain a H-modifying effect commensurate with the amount added, but also carbides and casting defects that are harmful to heat cracking resistance are likely to occur. Therefore, the amount of MO was set at 0.4 to 1.2%. Ti: 0, 05-0.10% It has also been revealed that by adding Ti as necessary, it is possible to impart excellent roughness and W itching resistance. At this time, if the amount of Ti is not added at least 0.05%, there will be no effect, and if it exceeds 0.10%, flaky graphite will become finer and the wear resistance effect will be weakened. was set at 0.05 to 0.10%. (Function of the Invention) The disc brake rotor according to the present invention has the above-mentioned composition and is made of flaky graphite cast iron whose matrix structure is pearlite, so it can withstand repeated braking from high-speed running. As a result, it has excellent heat cracking resistance, wear resistance, and vibration damping properties, making it a disc brake rotor that produces less squeal during braking. (Example) Table 1 shows the composition of the cast iron that is the material for the disc brake rotor used in this example, along with the composition of the cast iron that is the material for the comparative disc brake rotor. The cast iron used in this example was flake graphite cast iron, and the disc brake rotor 1 had the shape shown in FIG.
We made a prototype. The structure of each of the disc brake rotors 1 manufactured here was examined and found to be as shown in Figs. 2 to 7. The disc brake rotors 1 of this example were all pieces whose base structure was pearlite. It was made of graphite cast iron. Next, the prototype disc brake rotor 1 was installed in a brake dynamo testing machine, and a severe high-speed braking test was conducted in which the brake pad was pressed from a rotation speed equivalent to 260 km/h and stopped in 30 seconds, repeating 100 cycles. Ta. The brake pads used in this high-speed braking test are so-called non-asbestos (low steel) brake pads made of steel fiber and aromatic polyamide (trade name: Kevlar) fiber. Then, the occurrence of cracks in the disc brake rotor 1 after the test was investigated using a crack metallizing material for crack inspection. The results are shown in Table 2. In addition to the above-mentioned high-speed braking test, each disc brake rotor 1 was tested by repeating braking from 1100 km/h to a stop 100 times using a force of 0.6 g. The amount of surface wear was measured. The results are also shown in Table 2. As shown in Table 2, the disc brake rotors 1 of products No. 001 to 3 of the present invention exhibit far superior thermal cracking resistance than the disc brake rotors 1 of comparative products No. 4 made of current JISFC25. was confirmed. In addition, the disc brake rotors 1 of comparative products No. 5, No. 6, which have improved strength by adding alloying elements, are as follows:
Both of them meet the current JIS Fe12 in terms of thermal cracking properties.
The results were inferior to the comparison product No. 4 made of JIS Fe12, and simply increasing the strength did not improve the thermal cracking property, and because the thermal conductivity was inferior, the result was actually inferior to that made of the current JIS Fe12. I understand. Further, it was confirmed that the disc brake rotor 1 of the present invention has less rotor wear than the current disc brake rotor 1 and has excellent wear resistance. Regarding the rotor wear amount, among the products of the present invention, the wear resistance of the present invention products No. 3 containing Ti is particularly excellent, and the wear resistance can be further improved by adding Ti. It was confirmed that it is possible. In addition, the coefficient of friction between the rotor and pad, which indicates the braking performance (braking performance), is the same as that of the current JIS Fe12 even if the product of the present invention is used, and the braking performance is improved by adopting the product of the present invention. It was confirmed that there was no decline. In order to confirm the vibration damping properties of the disc brake rotor 1 according to the present invention, a plate-shaped test piece was cut out from the rotor.
The vibration damping ability was measured. The results are also shown in Table 2. As shown in Table 2, the vibration damping ability of one product of the present invention is:
This value was better than the current JISFC25. This is because the product of the present invention has a high C content in order to improve heat cracking resistance, and as a result, the vibration damping ability also has an excellent value. Therefore, it was confirmed that the product of the present invention also has excellent vibration damping properties. Effects of the Invention As explained above, the disc brake rotor according to the present invention has a weight ratio of C: 3.5 to 4.0%;
Si: 1.6-2.0%, Mn: 0.5-0.8%,
Mo: 0.4-1.2%, Ti: 0.05 as necessary
Contains ~0.10%, the balance consists of Fe and impurities,
Since it is made of flaky graphite cast iron with a pearlite base structure, it is a disc brake rotor with excellent heat cracking resistance, vibration damping performance, and wear resistance, and is especially suitable for applications where braking is repeatedly performed from high-speed driving. Even when used repeatedly, thermal cracks do not occur in the sliding parts, and the occurrence of squeal during braking can be reduced, which is an extremely excellent effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram illustrating the structure of a disc brake rotor, and FIGS. 2, 3, 4, 5, 6, and 7 are inventive product Nos., respectively. 1, No. 2, No. 3, Comparative product No. 4
, No. 5, and No. 5 and No. 006 disc brake rotors.
00 times). 1... Disc brake rotor, 2... Sliding part, 3... Fastening part. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] (1) Weight ratio: C: 3.5-4.0%, Si: 1.
6-2.0%, Mn: 0.5-0.8%, Mo: 0.4
~1.2%, Ti: 0.05~0.10% as necessary
A disc brake rotor having excellent heat crack resistance, vibration damping properties, and wear resistance, characterized in that it is made of flake graphite cast iron containing iron with the balance being Fe and impurities, and the base structure is pearlite.