JPH01202381A - Manufacture of lamination brake disk - Google Patents

Abstract

PURPOSE:To eliminate the dispersion in quality and to improve the safety of a working environment as well by opposing the disk of a gray cast iron and that of steel in a closed chamber, introducing a reducing gas into the hollow part of a brake disk and executing diffusion joining by pressing both disks from the back face respectively with heating them. CONSTITUTION:The disk 3 of a gray cast iron and the disk 4 of steel are placed inside the closed chamber 2 provided with a pressing means 1 by opposing the respective joining face 6, 7, a reducing gas is introduced to the hollow part 16 of a brake disk, the air interposed between the joining faces 6, 7 is eliminated and a reducing atm. is formed. The chamber inside is subjected to temp. rising uniformly by electrifying an exothermic body 8 and the specified pressure is uniformly applied from the upper and lower parts in specified temp. zone. The joining face has no oxide film, an active atom interchange is performed via an insert material and a strong and defectless joining face can be formed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to brake discs used in railway vehicles, etc.
This is a new proposal regarding a method for manufacturing a laminated brake disc that is particularly resistant to repeated thermal shock and thermal stress during braking.

[Prior Art] Brake discs for vehicles use friction to reduce or stop the rotational force of the wheel by pressing against the brake plate fixed to the wheel. Materials with good wear resistance are most suitable; gray cast iron with graphite precipitates (with low alloying proportions) is used. However, thermal cracks form on the sliding surfaces due to the thermal shock caused by the heat generated from the sudden friction during braking, and as the sliding surfaces gradually increase in length and depth, they must be replaced during intermediate vehicle checks. We have set standards to prevent accidents from occurring.

As a countermeasure to this problem, a laminated brake disc and its manufacturing method have already been proposed, in which the back surface is supported by a steel material that is resistant to thermal shock, and the extension of thermal cracks is prevented. 134089) and ``Method for producing composite cast iron material with excellent wear resistance and durability'' (Japanese Unexamined Patent Publication No. 148463/1989, Figure 1).

The former aims to make the brake disc a composite structure of gray cast iron and other materials, and merely indicates that the composite (joining) means is by casting or high-temperature pressure bonding. On the other hand, the latter is not limited to brake discs, but focuses on the manufacturing method itself for general composite materials, and uses steel of 1,000 to 1
It is a method of heating to 200'C in a non-oxidizing state (using a non-oxidizing furnace and rice husk) and then casting molten cast iron containing a small amount of 3N and Cu onto the surface. Figure 3 shows the procedure. It shows. In the figure, the steel is 4a, the surface to be bonded is 6a,
The heating furnace is shown as 8a, the rice husk is shown as 19, and the molten cast iron is shown as 3a.

Incidentally, the structure itself in which components in a mechanical device are manufactured by laminating them in a composite manner is understood to be well known without even looking at clad steel. In addition, high-temperature adhesion, which has been shown as a means of bonding, has been widely researched and put into practical use.
@ P27], Yuki et al. “Solid phase joining of spheroidal graphite cast iron J [(
Proceedings of the Welding Society Vol. 4 (1986) No. 1 P66]
, Ohmae et al. [Development and practical application of diffusion welding technology JK, Mitsubishi Heavy Industries Technical Report Voffi 19 No. 4 (1982-7) P
1] etc. have been published.

The principle is to heat the bonding material to a high temperature and then pressurize it to bond by mutual diffusion of atoms, and it has already been put into practical use as a member that is forced to work under harsh conditions.

[Problems to be Solved by the Invention] Among the conventional techniques, the joining method of casting molten cast iron onto heated steel is a technique called double casting or casting (a technique that has been adopted for a long time in 117 and has been put into practical use in some cases). I hear that heating steel materials to 1000-1200℃ in a non-oxidized state requires large equipment and precise work management in actual production, which places a heavy burden on the factory.On the other hand, it requires cast iron melting equipment. There are concerns that the work of casting into high-temperature steel materials is a much more difficult and high-temperature work than casting into a normal mold, and that even with the help of protection, it will be far from easy or safe work. Since the steel material is heated to a temperature close to the melting temperature of cast iron, it is easy to mix the molten metal into the cast iron, so there may be no need to worry too much about whitening of the carbon content or thermal stress, but it is important to ensure that the wide joint surfaces are evenly joined. However, it is not hard to imagine that in order to obtain a product that is uniformly cooled and defect-free, quite advanced and complicated management is required.

Next, when considering high-temperature compression bonding (diffusion bonding), the bonding atmosphere in this method is an extremely important factor, and if an oxide film is formed on the bonding surface heated to high temperature, it will significantly interfere with the atomic diffusion phenomenon. In some cases, joining becomes impossible. For example, the following formula calculates the number n of gas molecules colliding (recoiling) against a 1d joint surface per second.

n = 3.52x1022e - n: pcs/S/cri P: Pressure (Torr) M: Molecular weight (y> T: Absolute temperature (°K) This formula calculates the number of recoil molecules of oxygen, but in the atmosphere For example 1C) 'Tor
Since there is a difference of 107 points between r and under vacuum, the degree of vacuum is an important factor, and in order to obtain a good bonding surface, at least 10 = T
orr, preferably 10'' Torr.

In actual manufacturing, if the vacuum state is broken immediately after completing the bonding under vacuum, the bonding surfaces and heaters will easily oxidize, so in order to maintain product quality and equipment, we will not hold the bonding until the temperature cools down. Since the operating cycle of the vacuum equipment is poor, it is necessary to install a huge amount of vacuum equipment for mass production, which is the biggest obstacle to increasing productivity.

In order to solve the above-mentioned problems, the present invention aims to provide a method for manufacturing a laminated brake disc with less variation in the quality of joint surfaces and high productivity through safe work.

[Means for Solving the Problems] A method for manufacturing a hollow disc-shaped laminated brake disc according to the present invention involves placing a disc made of gray cast iron and a disc made of steel facing each other in a closed chamber equipped with a pressing means. The above problem is solved by introducing reducing gas into the hollow part of the brake disc to replace the air between the bonding surfaces, and uniformly pressing both discs from their respective back surfaces while heating to perform diffusion bonding. did.

Of the methods mentioned above, for brake discs of the type that have cooling ribs protruding from the back side of the sliding surface, which are widely used on high-speed vehicles such as the JR Shinkansen,
A cooling rib protrudes from the back surface of the opposing joint surface, and the problem is solved by adding a requirement that a groove into which the cooling rib fits is carved in the corresponding position of the pressing surface that presses the back surface. solved.

[Operation] The operation of the present invention will be explained based on FIG. 1 showing a preferred embodiment. In a sealed chamber 2 equipped with a pressing means 1, a gray cast iron disc 3 and a steel disc 4 are placed with their joint surfaces 6.7 facing each other, and a reducing gas is introduced into the hollow part 16 of the brake disc. First, air present between the bonding surfaces 6 and 7 is removed to form a reducing atmosphere. In this example, the insert material 5 is inserted between the respective joint surfaces in order to further activate the action, but there may be cases where the insert material 5 is not inserted. In this state, the heating element 8 is energized to uniformly raise the temperature in the room, and when a predetermined pressing force is applied evenly from above and below within a predetermined temperature range, the bonding surface has no oxide film, and in this example, there is no oxide film through the insert material. Active exchange of atoms takes place, forming a strong and defect-free bonding surface.

Insert material is interposed between cast iron and steel and prevents the formation of a brittle layer and unnecessary precipitates through active atomic diffusion between the insert material and cast iron, and between the steel material and the insert material. fulfill. Furthermore, if no insert material is used, separate surface treatment of the joint surfaces is required. The reducing gas that is sufficiently pressurized and necessary for bonding is discharged or recovered to the outside through the outlet 9, and the product is taken out of the sealed chamber and transferred to a non-oxidizing cooling chamber (reducing atmosphere is sufficient). After cooling, the sealed chamber 2 can be used again for the next joining operation.

[Example] To avoid duplication and to supplement the explanation of the example shown in FIG. The top and bottom of 4 are sandwiched between press plates 10 and 11. A support stand 12 is further installed at the bottom of the suppression plate 11.

The press plate 11 opens at the center of its upper surface and has an air supply hole 15 that communicates with an external gas source.

As the insert material, a thin part of Ni is most preferable, and other materials such as Cu and pure iron are also effective. Hydrogen gas is effective as the reducing gas, but other gases may be used as long as an atmosphere can be formed, or pure hydrogen gas may be mixed with another neutral gas such as argon gas. In the figure, gas cylinder 13° gas valve 14. Reducing gas is first introduced into the hollow part 16 of the hollow disk through the air supply hole 15 bored in the pressure plate 11, and then further transmitted through the gap between the joining surfaces of both disks and the gap between the back surface of both disks and the pressure plate. It fills all the rooms.

The heating element 8 is suitably a carbon electrode rod, a heating coil wire, or the like. To show an example of such an embodiment numerically, the joint surface of gray cast iron (equivalent to FC20) and steel (S841) is #
After polishing with 600 emery paper, a 0.05 m thick nickel foil was placed between them and set as shown in Figure 1. The temperature was raised to 850°C while flowing argon gas containing 5% hydrogen gas at 0.1/min from the hollow part, and the temperature was increased to 2 to 9/m.
A pressure of 1.5 m'' was applied and held for 1 hour.A test piece was taken across the bonded surface from the bonded body obtained by diffusion bonding as described above, and a tensile test was performed. ( ).The strength at this time was 22.3 Kg/mm 2 .

In high-speed vehicles such as the JR Shinkansen, many cooling ribs are provided radially on the back of the sliding surface of the brake disc to further stabilize the braking effect and extend the service life. An embodiment of the present invention is shown in FIG. In the figure, since cooling ribs 17 are protruded from the back surface of the disc 4, grooves 18 are carved in corresponding positions on the pressing plate 11 that presses this surface. The disk 4 and the cooling rib 17 can be integrally manufactured as a forged product.

[Effects of the Invention] Since the laminated brake disc according to the present invention has the structure and function described above, the connection between the gray cast iron material and the steel material is perfect, and there is almost no variation during manufacturing. close. The reliability of the joint surface is evidenced by the fact that the test piece that crosses the joint surface breaks on the cast iron base metal side, not at the joint surface, in a tensile test. Construction in a closed room significantly improves the working environment and safety for workers, and one of the major advantages is that it also improves productivity and is easier to adapt to the mother production system.

When the pressure is released after pressurized bonding, the reducing gas constantly flows from the hollow part 16 of the brake disc between both pressing plates 10 and 11 and both backs of the bonded product, thereby promoting cooling of the bonded product without oxidation. It also has the effect of shortening the bonding cycle in a closed chamber and greatly improving production efficiency.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention, FIG. 2 is an exploded sectional perspective view showing another embodiment, and FIG. 3 is a procedure explanatory diagram showing an example of a conventional technique.

Claims (2)

[Claims] (1) In a manufacturing method for a laminated brake disc in which the sliding surface of a hollow disc-shaped brake disc is made of gray cast iron and the back surface is joined with steel, a gray cast iron disc is placed in a sealed chamber equipped with a pressing means. Reducing gas is introduced into the hollow part of the brake disc while facing the steel disc, displacing the air between the joint surfaces, and uniformly pressing both discs from their respective back surfaces while heating to diffuse the gas. A method for manufacturing a laminated brake disc characterized by joining. (2) Manufacture of a laminated brake disc according to claim 1, in which cooling ribs protrude from the back surface of the steel material, and grooves into which the cooling ribs fit are carved at corresponding positions on the pressing surface that presses the back surface. Method.