JP6832587B2 - Cast iron brake shoes, their manufacturing method, steel sheets for casting and coating agents used for them - Google Patents

Description

The present invention relates to a cast iron brake shoe to be incorporated in a railway vehicle or the like, a method for manufacturing the same, a steel plate for casting and a coating agent used therein.

Cast iron brake shoes have the advantage of having high adhesive strength and not damaging the wheels, but they have the problem of being heavy and have low versatility, and have been mainly used in mountainous areas and snowy areas. However, in recent years, engine braking has been developed, and it has become possible to use brake shoes in the low speed range. Therefore, cast iron brake shoes, which have high adhesive strength and do not damage wheels, have been reviewed again. Since cast iron brake shoes are braking parts for railway vehicles and important safety parts, steel plates are often cast as reinforcing parts. As a method for manufacturing such a cast iron brake shoe containing a steel plate, a method of setting a steel plate in a mold of the cast iron brake shoe and casting it is known. In such a steel sheet, even if a crack occurs in the cast iron material, it stops at the cast steel sheet and does not extend to the steel sheet. Therefore, the cast iron material and the cast steel sheet are non-welded, and the outer circumference of the steel sheet It is important that the surface and the cast iron material have high adhesion. Conventionally, the following methods have been known in order to obtain a cast iron brake shoe having high adhesion to a cast iron steel plate. (1) Protects the sand surface of the mold and core from the heat of the molten metal and improves the casting surface. (2) The coating material to be applied to the mold surface is used for the purpose of preventing seizure. As an example, a water-based coating material in which graphite is turbid is applied.

Patent Documents 1 and 2 propose that a block containing ceramics and carbon fibers is embedded in a part of a cast iron friction material portion. The applicant proposes a copper-based sintered brake shoe in Patent Document 3. Patent Document 4 proposes that an iron-based sintered metal friction material and a reinforcing plate are pressure-bonded and sintered to form a brake shoe.

JP 2015-165162 Japanese Unexamined Patent Publication No. 2012-189175 Japanese Unexamined Patent Publication No. 2014-218723 JP-A-2007-309368

However, in the conventional cast iron brake shoes, the cast iron material and the steel plate are welded and integrated, and the structure of the surface of the steel plate welded to the cast iron material is transformed and brittle. Therefore, for example, if the brake shoe body is cracked, the steel plate is also cracked. Therefore, there is a problem that it is difficult to sufficiently exert the effect as a reinforcing material.

In order to solve the above-mentioned conventional problems, the present invention uses a cast iron brake shoe, a method for manufacturing the same, and a method for manufacturing the cast iron brake shoe, which is non-welding to the cast iron material and has excellent adhesion, and even if the brake shoe body is cracked, it is difficult to reach the steel plate. Provided are a steel plate for casting and a coating agent.

The cast iron brake shoe of the present invention is a cast iron brake shoe including a back plate made of a steel plate for casting and a cast iron brake shoe main body laminated on the lower surface of the back plate, and at least the cast iron of the back plate. A coating layer containing heat-resistant inorganic fine particles is formed on the surface of the brake shoe main body, and the coating layer is a crack barrier layer.

The method for producing a cast iron wheel according to the present invention is the method for producing a cast iron ring, wherein a coating agent is applied to a steel plate for casting, dried, placed in a mold, and a molten cast iron is cast and insert-formed. The coating agent contains 20 to 45% by mass of heat-resistant inorganic fine particles having an average particle size of 25 to 45 μm, 10 to 30% by mass of silica particles having an average particle size of 30 μm or less, and a binder when the whole is 100% by mass. It is a suspension in which 2 to 10% by mass and 30 to 60% by mass of water are mixed.

The steel sheet for casting of the present invention is a steel sheet for casting for use in the cast iron brake shoe, and a crack barrier layer containing heat-resistant inorganic fine particles is formed on the surface of the steel sheet for casting. It is characterized by that.

The coating agent of the present invention is a coating agent for use in the cast iron ring control wheel, and when the whole is 100% by mass, 20 to 45% by mass of heat-resistant inorganic fine particles having an average particle size of 25 to 45 μm. The suspension is a mixture of 10 to 30% by mass of silica particles having an average particle size of 30 μm or less, 2 to 10% by mass of a binder, and 30 to 60% by mass of water.

According to the present invention, a crack barrier layer containing heat-resistant inorganic fine particles is formed on the surface of a back plate made of a steel plate for casting, so that it is non-welding to a cast iron material and has excellent adhesion. It is possible to provide a cast iron brake shoe that is difficult to reach the back plate even if a crack is formed, a method for manufacturing the same, and a steel plate for casting and a coating agent used for the same.

FIG. 1 is a front sectional view of a vehicle brake shoe according to an embodiment of the present invention. FIG. 2 is a plan view seen from the back plate of the brake shoe. FIG. 3 is a sectional view taken along line II-II of FIG. FIG. 4 is a sectional view taken along line III-III of FIG. FIG. 5 is a perspective view of the brake shoe. FIG. 6A is a schematic cross-sectional view for explaining that a crack is formed in the brake shoe main body, and FIG. 6B is a crack explanatory view of a conventional example. FIG. 7 is a front sectional view of a vehicle brake shoe according to another embodiment of the present invention. FIG. 8 is a plan view seen from the back plate of the brake shoe. FIG. 9 is a sectional view taken along line IV-IV of FIG. FIG. 10 is a sectional view taken along line VV of FIG. FIG. 11 is a perspective view of the brake shoe. 12A-B are photomicrographs (magnification of 100 times) of the boundary portion of the cast iron brake shoes obtained by casting a cast iron material using the steel plate of Example 1.

The cast iron brake shoe of the present invention is a cast iron brake shoe including a back plate made of a steel plate for casting and a cast iron brake shoe main body laminated on the lower surface of the back plate, and at least the cast iron brake shoe of the back plate. A crack barrier layer containing heat-resistant inorganic fine particles is formed on the surface of the brake shoe body. The crack barrier layer may be formed over the entire surface of the cast iron brake shoe main body side, or may be partially formed. When it is partially formed, the area is preferably 70%, more preferably 80% or more, and further preferably 90% or more. In the present invention, the heat resistance of the inorganic fine particles is preferably higher than the casting temperature (melting temperature) of 1400 ° C. Preferred refractory inorganic fine particles, zircon (ZrSiO _4: mp 2700 ° C.), aluminum oxide (Al ₂ O _3: mp 2072 ° C.), magnesium oxide (MgO: mp 1850 ° C.) or mullite _{(3Al 2 O 3 · 2SiO 2} : Melting point 2852 ° C.) and the like. Of these, zircon is preferable because it is easy to handle and has a high crack barrier effect.

The average thickness of the crack barrier layer is preferably 30 to 150 μm. By setting it within this range, the adhesion between the steel plate of the back plate and the cast iron material can be strengthened. If the average thickness of the crack barrier layer is less than 30 μm, the adhesion between the steel plate and the cast iron material cannot be maintained and welding tends to occur. Further, if the average thickness of the crack barrier layer exceeds 150 μm, a gap is generated between the steel plate and the cast iron material, which tends to inferior in adhesion, and there is a concern that the steel plate may come off from the cast iron material. A more preferable average thickness is 40 to 125 μm, and even more preferably 50 to 100 μm.

When the crack barrier layer is 100% by mass, the heat-resistant fine particles are preferably in the range of 40 to 80% by mass (solid content), more preferably 45 to 75% by mass, and further preferably 50 to 70% by mass. is there. As a result, it is non-welded to the cast iron material and has excellent adhesion, and even if the brake shoe body is cracked, it is difficult to reach the steel plate. The crack barrier layer preferably further contains silica. This provides a uniform crack barrier layer.

The back plate preferably has a plurality of irregularities on the side surface. As a result, more robust adhesion to the cast iron material can be achieved. Further, it is preferable that the plurality of irregularities is at least one selected from the notch portion and the groove portion extending inward from the side surface. As the notch, a notch having a curved shape toward the inside is more preferable. By forming notches and grooves, it is possible to more effectively achieve strong adhesion to the cast iron material.

The casting steel plate (back plate) is preferably at least one selected from high-strength steel and structural rolled steel. High-strength steel or structural rolled steel is suitable for backboards because of its high strength and elasticity. The size of the back plate is preferably 200 to 350 mm in length, 25 to 90 mm in width, and 4.5 to 9.0 mm in thickness.

The cast iron is preferably phosphorus-containing cast iron. This is because phosphorus-containing cast iron has high wear resistance. The ratio of phosphorus is preferably 0.1 to 3.5% by mass. As an example, the size of the cast iron brake shoe main body is preferably 250 to 400 mm in length, 70 to 130 mm in width, and 40 to 80 mm in thickness.

The method for producing a cast iron wheel controller of the present invention is a method in which a coating agent is applied to a steel plate for casting, dried, placed in a mold, and a molten cast iron is cast and insert-formed. %, 20 to 45% by mass of heat-resistant fine particles having an average particle size of 25 to 45 μm, 10 to 30% by mass of silica particles (silica flower) having an average particle size of 30 μm or less, and 2 to 10% by mass of a binder. And a suspension in which 30 to 60% by mass of water is mixed is used. Zircon flower is preferable as the heat-resistant fine particles. Zircon flower refers to zirconium silicate (ZrSiO ₄ ) particles, and silica flower refers to silica fume particles.

The coating agent for casting is required to have a role of preventing the molten metal from being seized (welded) to the casting material and a function of a heat insulating material for controlling the cooling rate in order to obtain an appropriate material. As an example, zircon flower and silica flower serve as a base material for a coating agent. In the coating agent used in the present invention, the average particle size of zircon flower is a factor that determines the surface roughness, and silica flower is a crack barrier layer. It plays a role in obtaining the uniformity of. Further, the binder plays a role of joining them together to secure the strength of the coating material, and examples of the binder used in the present invention include bentonite and starch.

The amount of water has the role of uniformly adjusting the surface thickness. In the present invention, a uniform surface thickness can be obtained by mixing and using each of the above components in a specific ratio. The maximum surface thickness is determined by the mixing ratio of zircon flower and silica flower. That is, the higher the ratio of zircon flower, the thicker the surface thickness.

In the present invention, for example, when the ratio of zircon flower to silica flower is constant, the coating thickness becomes excessive when the average particle size of zircon flower exceeds 45 μmm, and the thickness becomes excessive when it is less than 25 μm. Not preferable. Further, if the blending amount of the binder is less than 2% by mass, the thickness becomes excessive, and if it exceeds 10% by mass, the thickness becomes too small, which is not preferable. Further, if the silica flower content is less than 10% by mass, the coating mold becomes non-uniform, and if it exceeds 30% by mass, the coating thickness becomes too small, which is not preferable. The particle size is measured by the laser diffracted light scattering method, and the median size (d50) is taken as the average particle size. As this measuring instrument, for example, there is a laser diffraction / scattering type particle distribution measuring device LA-950S2 manufactured by HORIBA, Ltd.

In the method for producing a steel sheet of the present invention, a steel sheet coated with a coating material is dried in a mold, and then a molten cast iron is cast in the mold for molding. The coating method may be any method such as dipping, spray coating, brush coating, and roller coating.

This will be described below with reference to the drawings. In the drawings below, the same reference numerals indicate the same parts or the same objects. FIG. 1 is a front sectional view of a cast iron brake shoe 1 for a vehicle according to an embodiment of the present invention (cross-sectional view taken along the line II of FIG. 2), and FIG. 5 is a perspective view of the brake shoe. In the cast iron brake shoe 1, a crack barrier layer 3 is formed on the lower surface of the back plate 2, and the cast iron brake shoe main body 4 is cast under the crack barrier layer 3. Reference numeral 5 denotes a friction surface that comes into contact with the wheel. When the crack barrier layer 3 is formed on the lower surface of the back plate 2, as shown in FIG. 6A, even if the crack 11 enters the brake shoe main body 4 for some reason, it stops at the crack barrier layer 3 and reaches the back plate 2. Does not reach or is hard to reach. As a result, damage to the back plate 2 can be prevented and a major accident can be prevented. On the other hand, in the conventional example of FIG. 6B without the crack barrier layer 3, if the brake shoe 12 is cracked, the back plate 2 may be cracked.

FIG. 2 is a plan view seen from the back plate 2 of the brake shoe. A plurality of (8 in this example) curved notches 7 having a curved shape are formed on the side surface of the back plate 2. Since the cast iron brake shoe main body is cast so as to be flush with the upper surface of the back plate 2, the back plate 2 and the cast iron brake shoe main body 4 can be firmly brought into close contact with each other by the plurality of notches 7. A mounting portion 6 is formed in the center of the back plate 2. The side surface 8 of the cast iron brake shoe main body 4 on the opposite flange side is straight. The side surface 9 on the flange side of the cast iron brake shoe main body 4 is straight in the center, but the ears 10a and 10b are formed at both ends.

FIG. 3 is a sectional view taken along line I-I of FIG. 1, and FIG. 4 is a sectional view taken along line II-II of FIG. As is clear from FIGS. 3 to 4, the cast iron brake shoe main body 4 is cast so as to be flush with the upper surface of the back plate 2.

FIG. 7 is a front sectional view of the vehicle brake shoe 13 according to another embodiment of the present invention (VI-VI line sectional view of FIG. 8), FIG. 8 is a plan view of the brake shoe 13 as viewed from the back plate, and FIG. 7 is a sectional view taken along line IV-IV of FIG. 7, FIG. 10 is a sectional view taken along line VV of FIG. 7, and FIG. 11 is a perspective view of the brake shoe 13. The difference from the brake shoes 1 in FIGS. 1 to 5 is that the ears 10a and 10b are not provided. Other points are the same.

The present invention will be described below with reference to examples. The present invention is not construed as being limited to the following examples.

In each example, phosphorus-containing cast iron (0.5 mass% phosphorus) was used as the cast iron. A high-strength steel plate was used as the steel plate (back plate) for casting, and the steel plate thickness was 6 mm.
Each cast iron brake shoe was manufactured using each coating agent having the composition shown in Table 1 below. Specifically, each coating agent was spray-coated on the surface of the steel sheet so that the average thickness was 50 to 150 μm, dried, placed in a mold, and molten cast iron was poured into the mold for casting. The shape of the cast iron brake shoe was shown in FIGS. 7 to 11 (without ears), and the casting conditions were a molten metal temperature of 1400 ° C. and a casting time of 25 sec. The contents of each coating agent are shown in Table 1.

(Examples 1 to 17)
In the cast iron brake shoes, the adhesion between the steel plate and the cast iron material, which were formed into a crack barrier layer by coating the above coating agents 1 to 4 by a spray coating method, was examined. For the evaluation of adhesion, after casting, the cast iron brake shoes in which the steel plate is cast are cut into small pieces, and the steel plate and cast iron material that do not peel off to 10 mm square are A, those that do not peel to 20 mm square are B, and more. The one that peeled off by size was evaluated as C, and the one that was welded was evaluated as D. The results are shown in Table 2.

From Table 2, it can be seen that good adhesion can be obtained when the average thickness of the coating layer is within the range of 50 to 150 μm. Further, FIG. 12A-B shows a micrograph (magnification of 100 times) at the boundary portion of the cast iron brake shoe obtained by casting a cast iron material using the steel plate of Example 1. In FIGS. 12A-B, the crack barrier layer 15 made of a coating layer was interposed between the steel plate 14 and the cast iron 16, and the average thicknesses L1 and L2 of the crack barrier layer 15 were both 50 μm. It can be seen that when the steel sheet of Example 1 is used, it is non-welded to the cast iron material and has excellent high adhesion.

(Comparative Example 1)
It was carried out in the same manner as in Example 1 except that the crack barrier layer was not provided. The adhesion evaluation of the obtained cast iron brake shoes was D, and they were welded.

(Reference example 1)
The same procedure as in Example 1 was carried out except that the average thickness of the crack barrier layer was 20 μm. The adhesion evaluation of the obtained cast iron brake shoes was C.

As described above, according to each embodiment of the present invention, when a steel plate is cast and cast on a cast iron material, it has high adhesion to the cast iron material due to non-welding, so that the joint strength between the two and the casting material of the steel plate are obtained. It is possible to obtain a cast-iron product excellent in suppressing changes in the interface structure with and. Therefore, for example, in the case of a cast iron brake shoe, the steel plate and the cast iron material are non-welded and firmly adhered to each other, so that crack growth from the sliding surface can be suppressed immediately before the steel plate.

The vehicle brake shoe of the present invention is suitable for high-speed railways and ordinary railway vehicles because of its low manufacturing cost, and is also suitable for subway vehicles and tram vehicles.

1,13 Cast iron brake shoes 2 Back plate 3,15 Crack barrier layer 4 Cast iron brake shoes body 5 Friction surface in contact with wheels 6 Mounting part 7 Notch part 8 Side of cast iron brake shoes body on the opposite side of flange 9 Cast iron brake shoes body Friction side sides 10a, 10b Ears 11, 12 Cracks 14 Steel plate 16 Cast iron

Claims (12)

A cast iron brake shoe including a back plate made of a steel plate for casting and a cast iron brake shoe main body laminated on the lower surface of the back plate.
A cast iron brake shoe characterized in that a coating layer containing heat-resistant inorganic fine particles is formed on at least the surface of the back plate on the main body side of the cast iron brake shoe, and the coating layer is a crack barrier layer. The heat-resistant inorganic fine particles, zircon (ZrSiO _4), aluminum oxide (Al ₂ O _3), in claim 1 is at least one selected from magnesium oxide (MgO) and mullite _{(3Al 2 O 3 · 2SiO 2} ) The cast iron control wheel described. The cast iron brake shoe according to claim 1 or 2, wherein the average thickness of the crack barrier layer is 30 to 150 μm. The cast iron brake shoe according to any one of claims 1 to 3, wherein the heat-resistant inorganic fine particles are in the range of 30 to 80% by mass (solid content) when the crack barrier layer is 100% by mass. The cast iron brake shoe according to any one of claims 1 to 4, further comprising silica particles in the crack barrier layer. The cast iron brake shoe according to any one of claims 1 to 5, wherein the back plate has a plurality of irregularities on the side surface. The cast iron brake shoe according to claim 6, wherein the plurality of irregularities is at least one selected from a notch portion and a groove portion extending inward from the side surface. The cast iron brake shoe according to any one of claims 1 to 7, wherein the cast iron steel plate is at least one selected from high-strength steel and structural rolled steel. The cast iron brake shoe according to any one of claims 1 to 8, wherein the cast iron cast into the cast iron brake shoe main body is a phosphorus-containing cast iron. The method for manufacturing a cast iron brake shoe according to any one of claims 1 to 9, wherein a coating agent is applied to a steel sheet for casting, dried, placed in a mold, and cast iron molten metal is cast and insert-molded.
The coating agent contains 20 to 45% by mass of heat-resistant inorganic fine particles having an average particle size of 25 to 45 μm, 10 to 30% by mass of silica particles having an average particle size of 30 μm or less, and a binder when the whole is 100% by mass. A method for producing a cast iron wheel controller, which is a suspension in which 2 to 10% by mass and 30 to 60% by mass of water are mixed. A steel plate for casting for use in the cast iron brake shoe according to any one of claims 1 to 9.
A steel sheet for casting, characterized in that a crack barrier layer containing heat-resistant inorganic fine particles is formed on the surface of the steel sheet for casting. A coating agent for use in the cast iron brake shoes according to any one of claims 1 to 9.
The coating agent contains 20 to 45% by mass of heat-resistant inorganic fine particles having an average particle size of 25 to 45 μm, 10 to 30% by mass of silica particles having an average particle size of 30 μm or less, and a binder when the whole is 100% by mass. A coating agent, which is a suspension in which 2 to 10% by mass of water and 30 to 60% by mass of water are mixed.