Patent Description:
In general, a vehicle brake is mainly divided into a disc brake and a drum brake. The disc brake generates a braking force based on friction created using calipers to squeeze pads against both sides of a disc that rotates together with a wheel. The drum brake obtains a braking force by squeezing brake shoes with linings (a friction material) into a drum that rotates together with a wheel.

Currently, since many technologies for achieving stability of a vehicle based on braking, e.g., anti-lock braking (ABS) and vehicle dynamic steering (VDS) /electronic stability program (ESP), have been developed, the drum brake which does not provide a sufficient braking force due to expansion when used repeatedly is not used and the disc brake is used for rear wheels as well as front wheels.

A conventional brake disc manufacturing method includes a method of manufacturing a brake disc by bond-casting cast iron and aluminum (Al) and a method of manufacturing a brake disc by using cast iron and then inserting Al foam thereinto. Even when nodular cast iron is used, upper and lower plates of the conventional cast iron disc need to have a thickness of at least <NUM> to prevent thermal deformation.

<CIT> discloses a brake disk with an inner friction ring, an outer friction ring, and a wire structure element arranged between the inner and outer rings. The element is designed as an open-cell three-dimensional wire structure, with a porosity of between <NUM> and <NUM> percent, and comprises metallic wires, where diameter of the wires lies in the range between <NUM> and <NUM>. Connection elements designed as rods or fins are formed in an inner side of the element.

<CIT> discloses a brake disc with a friction ring and a support pot, wherein at least the friction ring is cast from a casting material. In order to minimize the weight and at the same time to permit simple and operationally reliable production, an insert having a lower density or increased strength in comparison to the casting material is cast into the brake disc.

<CIT> discloses a foam body for a brake disc, comprises a foam body area for connecting the foam body with a corresponding friction ring of the brake disc, and a further foam body area. The foam body is formed as a metal foam body or ceramic foam body.

<CIT> discloses a method for forming a casted brake rotor using a porous structure. The casted component may include a visible design feature formed in part by the casted component and in part by a body material also forming other parts of the component. The brake rotor has a mixed-material composite formed in part by the casted component and in part by a body material also forming other parts of the rotor. The porous structure can include a ceramic foam or a metal mesh.

However, the method of manufacturing a brake disc by bond-casting cast iron and aluminum (Al) merely achieves a weight reduction rate of only about <NUM>%. The method of manufacturing a brake disc by casting cast iron and then inserting metal foam thereinto has a very complex manufacturing process, does not easily achieve uniformity in closed-cell-type metal foam, and is not easily applicable due to a difference in continuous heating.

The present invention provides a brake disc and a brake disc manufacturing method capable of ensuring a weight reduction effect, achieving high heat radiation efficiency and durability, and thus achieving an increase in fuel efficiency and a reduction in braking distance. However, the scope of the present invention is not limited thereto.

According to a first aspect of the present invention, there is provided a brake disc manufacturing method as set out in claim <NUM>.

In the filler filling operation, the filler may include one of sand, plaster, metal powder, magnet powder, resin powder, and molding sand.

The filler removal operation may include an operation for removing the filler filled in the brake disc manufactured in the insert casting operation, by at least one of vibration, sandblasting, and vacuum suction.

According to a second aspect of the present invention, there is provided a brake disc manufacturing method as set out in claim <NUM>.

According to a third aspect of the present invention, there is provided a brake disc as set out in claim <NUM>.

The porous metal block may include an open-cell-type porous metal block having therein a plurality of pores connected to each other and fillable with a filler.

When insert-cast, the porous metal block may be partially buried by a casting material at a boundary between the first disc plate and the porous metal block and a boundary between the second disc plate and the porous metal block.

As described above, according to an embodiment of the present invention, since a cast iron brake disc is manufactured by inserting a porous metal block thereinto, a weight reduction effect may be ensured and the thickness of upper and lower plates may be reduced to about <NUM>. Since an open-cell-type porous metal block having a pore size of <NUM> pores per inch (ppi) (<NUM> to <NUM>) has a surface area of <NUM>,<NUM><NUM>/m<NUM> and thus achieves high heat radiation efficiency and durability, an increase in fuel efficiency and a reduction in braking distance may be achieved. In addition, since the open-cell-type porous metal block has an extremely high surface area ratio per unit volume, an ultra light weight, a high strength, a high processability, a high impact resistance, a high noise absorbability, and sound absorption and electromagnetic shielding characteristics, the above-described effects may be achieved when the brake disc is manufactured using the open-cell-type porous metal block. A brake disc and a brake disc manufacturing method having the above effects may be implemented. However, the scope of the present invention is not limited thereto.

Hereinafter, the present invention will be described in detail by explaining embodiments of the invention with reference to the attached drawings.

The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to one of ordinary skill in the art. In the drawings, the thickness or sizes of layers may be exaggerated for clarity and convenience of explanation.

<FIG> is a flowchart of a brake disc manufacturing method useful for understanding the present invention, <FIG> is a cross-sectional view of a brake disc <NUM> according to some embodiments of the present invention, and <FIG> is a flowchart of a brake disc manufacturing method useful for understanding the present invention.

As illustrated in <FIG>, the brake disc manufacturing method may basically include a porous metal block preparation operation S1 and an insert casting operation S2.

Specifically, the brake disc manufacturing method may include the porous metal block preparation operation S1 for preparing a porous metal block having a plurality of pores therein, and the insert casting operation S2 for mounting the porous metal block in a mold and casting a disc plate material to manufacture the brake disc <NUM>.

<FIG> is a cross-sectional view for describing the porous metal block preparation operation S1 of <FIG>, and <FIG> is a cross-sectional view for describing the insert casting operation S2 of <FIG>.

Herein, as illustrated in <FIG>, in the porous metal block preparation operation S1, a part of the brake disc <NUM> in which no friction surfaces are provided may be made of a porous metal block <NUM> to reduce a weight of the brake disc <NUM>.

Specifically, for example, the porous metal block preparation operation S1 may be an operation for preparing an open-cell-type porous metal block O having therein a plurality of pores connected to each other and fillable with a filler S.

Herein, in the porous metal block preparation operation S1, the porous metal block <NUM> may be metal foam, and the metal foam may be porous metal having a three-dimensional reticular structure and having a very high porosity. The metal foam may be produced by adding a gas-creating material into molten metal or by filling metal in empty spaces of resin foam and burning up the resin.

Although not shown in <FIG>, the porous metal block <NUM> may be made of iron (Fe)-, titanium (Ti)-, magnesium (Mg)-, or aluminum (Al)-based metal, and may include one of bronze, Al foam, stainless steel having a high corrosion resistance or thermal resistance, nickel (Ni), and Ti.

Specifically, for example, the porous metal block <NUM> may be classified into a closed-cell-type porous metal block O and an open-cell-type porous metal block C. Herein, the closed-cell-type porous metal block C may be made of metal including independent pores not connected to each other, and the open-cell-type porous metal block O may be made of metal including pores connected to each other, may allow a gas or a fluid to easily pass therethrough, and may have the above-described effects.

Herein, the open-cell-type porous metal block O may have a composition the same as that of metal of a first disc plate <NUM> and a second disc plate <NUM>. In this case, the first and second disc plates <NUM> and <NUM> and the open-cell-type porous metal block O may have a composition of Fe (a main component), carbon (C) (<NUM> wt% to <NUM> wt%), silicon (Si) (<NUM> wt% to <NUM> wt%), manganese (Mn) (equal to or lower than <NUM> wt% (higher than <NUM> wt%)), phosphorus (P) (equal to or lower than <NUM> wt% (higher than <NUM> wt%)), sulfur (S) (equal to or lower than <NUM> wt% (higher than <NUM> wt%)), and unavoidable impurities.

As described, when the first and second disc plates <NUM> and <NUM> and the open-cell-type porous metal block O have the same composition, the first and second disc plates <NUM> and <NUM> and the open-cell-type porous metal block O may have the same thermal expansion coefficient and thus stability of a bonding structure therebetween may be maintained.

As illustrated in <FIG> and <FIG>, the brake disc manufacturing method may further include a filler filling operation S3 for filling the filler S in the open-cell-type porous metal block O prepared in the porous metal block preparation operation S1, after the porous metal block preparation operation S1 such that cast iron and the disc plate material do not permeate thereinto in the insert casting operation S2.

In the insert casting operation S2, the porous metal block <NUM> prepared in the porous metal block preparation operation S1 may be mounted in a mold and the disc plate material may be cast together with the porous metal block <NUM>.

<FIG> is a cross-sectional view for describing the filler filling operation S3 of <FIG>.

Specifically, for example, the filler filling operation S3 may be an operation for filling the filler S in the open-cell-type porous metal block O. Since the porous metal block <NUM> is provided as the open-cell-type porous metal block O, the filler S may be filled in the open-cell-type porous metal block O. In the filler filling operation S3, the filler S may include one of sand, plaster, metal powder, magnet powder, resin powder, and molding sand.

Although not shown in <FIG>, the filler S may be a liquid or solid material capable of being filled in the open-cell-type porous metal block O. In this case, the filler S may include a material which does not spill in the insert casting operation S2 after being injected into the open-cell-type porous metal block O, and is removable in a filler removal operation S4.

The brake disc manufacturing method may further include the filler removal operation S4 for removing the filler S filled in the brake disc <NUM> manufactured in the insert casting operation S2, after the insert casting operation S2.

<FIG> is a cross-sectional view for describing the filler removal operation S4 of <FIG>.

Specifically, for example, the filler S filled in the filler filling operation S3 may be removed to reduce the weight of the cast brake disc <NUM>. Therefore, the filler S may be removed from the open-cell-type porous metal block O by, for example, vacuum suction.

Although not shown in <FIG>, the filler S may be removed by using gravity and vibration, by blowing air into the open-cell-type porous metal block O, by injecting a liquid such as water or oil into the open-cell-type porous metal block O, or by using centrifugal force.

<FIG> is a perspective view of a brake disc <NUM> according to other embodiments of the present invention, <FIG> is a vertical cross-sectional view of the brake disc <NUM> of <FIG>, and <FIG> is a horizontal cross-sectional view of the brake disc <NUM> of <FIG>.

Herein, as illustrated in <FIG>, the brake disc <NUM> according to other embodiments of the present invention may include the first and second disc plates <NUM> and <NUM> corresponding to each other and having friction surfaces 10a and 20a to generate friction forces in contact with brake pads BP, and the porous metal block <NUM> made of porous metal and insert-cast between the first and second disc plates <NUM> and <NUM>.

Herein, the first and second disc plates <NUM> and <NUM> may be generated in the insert casting operation S2 and may include the friction surfaces 10a and 20a squeezed by calipers (not shown).

Herein, although not shown in <FIG>, the friction surfaces 10a and 20a may include a plurality of holes and linear holes to efficiently increase heat dissipation characteristics.

As illustrated in <FIG>, the porous metal block <NUM> includes through holes <NUM> penetrating from a surface to the other surface of the porous metal block <NUM>, and the first and second disc plates <NUM> and <NUM> includes connection parts <NUM> configured to interconnect the first and second disc plates <NUM> and <NUM> through the through holes <NUM>.

Specifically, for example, the connection parts <NUM> may be a sort of bridge structures which are integrally connected to the first and second disc plates <NUM> and <NUM> through the through holes <NUM> of the porous metal block <NUM> in the insert casting operation S2 to integrate and firmly fix the first and second disc plates <NUM> and <NUM> with and to the porous metal block <NUM>.

Although not shown in <FIG>, when the first and second disc plates <NUM> and <NUM> are cast by inserting the porous metal block <NUM> therebetween, in addition to a cylindrical shape, the through holes <NUM> may be generated in a rectangular shape or a linear shape and thus the connection parts <NUM> may be generated in a rectangular shape or a linear shape corresponding to the through holes <NUM>.

Although not shown in <FIG>, the brake disc <NUM> may include a fixing part at a center of the first and second disc plates <NUM> and <NUM> to fix the brake disc <NUM> to a shaft, and the fixing part may have various shapes fixable to a shaft.

Therefore, according to some embodiments of the present invention, since a cast iron brake disc is manufactured by inserting a porous metal block thereinto, a weight reduction effect may be ensured, high heat radiation efficiency and durability may be achieved, and thus an increase in fuel efficiency and a reduction in braking distance may be achieved. In addition, since an open-cell-type porous metal block has an extremely high surface area ratio per unit volume, an ultra light weight, a high strength, a high processability, a high impact resistance, a high noise absorbability, and sound absorption and electromagnetic shielding characteristics, the above-described effects may be achieved when the brake disc is manufactured using the open-cell-type porous metal block.

<FIG> is a flowchart of a brake disc manufacturing method according to other embodiments of the present invention.

As illustrated in <FIG>, the brake disc manufacturing method according to other embodiments of the present invention further includes a bridge hole generation operation S5 and a hole filler filling operation S6 before the filler filling operation S3 described above in relation to <FIG>, and further includes a hole filler removal operation S7 and a boundary filler removal operation S8 after the filler filling operation S3.

<FIG> is a cross-sectional view for describing the porous metal block preparation operation S1 of <FIG>, <FIG> is a cross-sectional view for describing the bridge hole generation operation S5 of <FIG>, <FIG> is a cross-sectional view for describing the hole filler filling operation S6 of <FIG>, <FIG> is a cross-sectional view for describing the filler filling operation S3 of <FIG>, <FIG> is a cross-sectional view for describing the hole filler removal operation S7 and the boundary filler removal operation S8 of <FIG>, <FIG> is a cross-sectional view for describing the insert casting operation S2 of <FIG>, and <FIG> is a cross-sectional view for describing the filler removal operation S4 of <FIG>.

The brake disc manufacturing method according to other embodiments of the present invention will now be described in detail with reference to <FIG>. As illustrated in <FIG>, the above-described porous metal block <NUM> may be prepared and then, as illustrated in <FIG>, the bridge hole generation operation S5 is an operation for generating bridge holes <NUM> in the porous metal block <NUM>. In this case, as illustrated in <FIG>, a hub hole H may also be generated based on the shape or type of a brake disc.

As illustrated in <FIG>, the hole filler filling operation S6 is an operation for temporarily filling a hole filler <NUM> to be removed before the insert casting operation S2 or to be melted away in the insert casting operation S2, e.g., sand, expanded polystyrene, or paraffin wax, in the bridge holes <NUM>.

As illustrated in <FIG>, the filler filling operation S3 is an operation for filling the filler S, e.g., sand, in the porous metal block <NUM> except for spaces in which the hole filler <NUM> is filled. In this case, the filler S may be hardened by applying heat or pressure thereto.

As illustrated in <FIG>, the hole filler removal operation S7 is an operation for removing the hole filler <NUM> temporarily filled in the bridge holes <NUM>, and the boundary filler removal operation S8 is an operation for removing the filler S filled in boundaries B between the porous metal block <NUM> and a casting material by using an air blower such that cast iron and the disc plate material partially permeate into and are firmly fixed to the boundaries B in the insert casting operation S2.

As illustrated in <FIG>, the insert casting operation S2 is an operation for performing insert casting by inserting the porous metal block <NUM> into a mold M.

In this case, a core MM corresponding to the hub hole H of the porous metal block <NUM> may be mounted in the mold M and a brake disc having the hub hole H may be manufactured. Alternatively, for a hub-integrated brake disc, a hub cavity may be generated in the mold M.

As illustrated in <FIG>, the filler removal operation S4 is an operation for removing the filler S filled in the porous metal block <NUM> to reduce a weight of the cast brake disc. Thus, the filler S may be removed from the open-cell-type porous metal block O by, for example, vacuum suction.

<FIG> is a cross-sectional view of a brake disc <NUM> according to other embodiments of the present invention.

Therefore, as illustrated in <FIG>, in the insert casting operation S2, the casting material may permeate into the boundaries B from which the filler S is partially removed using an air blower and thus the first and second disc plates <NUM> and <NUM> and the connection parts <NUM> may be generated. At the same time, the porous metal block <NUM> may be partially buried by and structurally firmly bonded to the casting material at the boundary B between the first disc plate <NUM> and the porous metal block <NUM> and the boundary B between the second disc plate <NUM> and the porous metal block <NUM>.

As illustrated in <FIG>, the brake disc manufacturing method according to other embodiments of the present invention further includes the bridge hole generation operation S5, the hole filler filling operation S6, and a boundary filler filling operation S9 before the filler filling operation S3 described above in relation to <FIG>.

<FIG> is a cross-sectional view for describing the bridge hole generation operation S5 of <FIG>, <FIG> is a cross-sectional view for describing the hole filler filling operation S6 of <FIG>, <FIG> is a cross-sectional view for describing the boundary filler filling operation S9 and the filler filling operation S3 of <FIG>, and <FIG> is a cross-sectional view for describing the insert casting operation S2 of <FIG>.

The brake disc manufacturing method according to other embodiments of the present invention will now be described in detail with reference to <FIG>. As illustrated in <FIG>, the bridge hole generation operation S5 is an operation for generating the bridge holes <NUM> in the porous metal block <NUM>. In this case, as illustrated in <FIG>, the hub hole H may also be generated based on the shape or type of a brake disc.

As illustrated in <FIG>, the hole filler filling operation S6 is an operation for temporarily filling the hole filler <NUM> to be removed before insert casting or to be melted away in the insert casting operation S2, e.g., sand, expanded polystyrene, or paraffin wax, in the bridge holes <NUM>.

As illustrated in <FIG>, the boundary filler filling operation S9 is an operation for temporarily filling a boundary filler F to be melted away in the insert casting operation S2, e.g., expanded polystyrene or paraffin wax, in the boundaries B between the porous metal block <NUM> and the casting material. The filler filling operation S3 is an operation for filling the filler S, e.g., sand, in the porous metal block <NUM> except for spaces in which the hole filler <NUM> and the boundary filler F are filled. In this case, the filler S may be hardened by applying heat or pressure thereto.

As illustrated in <FIG>, the insert casting operation S2 is an operation for performing insert casting by inserting the porous metal block <NUM> into the mold M.

In this case, the core MM corresponding to the hub hole H of the porous metal block <NUM> may be mounted in the mold M and a brake disc having the hub hole H may be manufactured. Alternatively, for a hub-integrated brake disc, a hub cavity may be generated in the mold M.

Therefore, as illustrated in <FIG>, in the insert casting operation S2, the hole filler <NUM> and the boundary filler F may be removed by high temperature, the casting material may permeate into the spaces from which the hole filler <NUM> and the boundary filler F are removed, and thus the first and second disc plates <NUM> and <NUM> and the connection parts <NUM> may be generated. At the same time, the porous metal block <NUM> may be partially buried by and structurally firmly bonded to the casting material at the boundary B between the first disc plate <NUM> and the porous metal block <NUM> and the boundary B between the second disc plate <NUM> and the porous metal block <NUM>.

While the present invention has been particularly shown and described with reference to embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the scope of the present invention as defined by the following claims.

Claim 1:
A brake disc manufacturing method, the method comprising:
a porous metal block preparation operation (S1) for preparing a porous metal block (<NUM>) having a plurality of pores therein; and
an insert casting operation (S2) for mounting the porous metal block (<NUM>) in a mold and casting a disc plate material to manufacture a brake disc (<NUM>);
wherein the porous metal block preparation operation (S1) comprises an operation for preparing an open-cell-type porous metal block (<NUM>) having therein a plurality of pores connected to each other and fillable with a filler (S);
wherein the method further comprises:
a filler filling operation (S3) for filling the filler (S) in the open-cell-type porous metal block (<NUM>) prepared in the porous metal block preparation operation (S1), after the porous metal block preparation operation (S1) such that cast iron and the disc plate material do not permeate thereinto in the insert casting operation (S2);
a filler removal operation (S4) for removing the filler (S) filled in the brake disc (<NUM>) manufactured in the insert casting operation (S2) after the insert casting operation (S2);
a bridge hole generation operation (S5) for generating bridge holes (<NUM>) in the porous metal block (<NUM>); and
a hole filler filling operation (S6) for temporarily filling a hole filler (<NUM>) to be removed before the insert casting operation (S2) or to be melted away in the insert casting operation (S2), e.g. sand, expanded polystyrene, or paraffin wax, in the bridge holes (<NUM>) before the filler filling operation (S3);
and wherein the method further comprises:
a hole filler removal operation (S7) for removing the hole filler (<NUM>) temporarily filled in the bridge holes (<NUM>); and
a boundary filler removal operation (S8) for removing the filler (S) filled in boundaries between the porous metal block (<NUM>) and a casting material by using an air blower such that cast iron and the disc plate material partially permeate into and are firmly fixed to the boundaries in the insert casting operation (S2) after the filler filling operation (S6).