JP2001205393A - Core structure for casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily position and hold a core in a metal mold and to enhance the impregnatability of molten metal and to enhance the strength of the core. SOLUTION: The sand core 7 is formed to a tapered shape in such a manner that a core outer peripheral surface 8 of an outer ring part 8 abuts on a lower mold outer peripheral surface 2a in the state that the core is arranged into a cavity 3. The core inner peripheral surface 9a of an inner ring part 9 is formed to a tapered shape so as to abut on an upper mold projecting surface 1b. Cut-off parts 9 cut off in such a manner that four points are made flush rectilinearly with a connecting part 10 are formed in the flank pat of the inner ring part 9 facing a sprue 4 at equal intervals in a circumferential direction and are made into a cantilever structure having the outer ring part 8 as a fulcrum within the cavity 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a core structure for casting, for example, a ventilated brake disk rotor.

[0002]

2. Description of the Related Art When casting a brake disc, which is one of the automotive parts, from an aluminum alloy, a porous member such as a porous ceramic body is impregnated with molten metal to form a composite, thereby forming a brake disk rotor sliding surface. Increases heat resistance and wear resistance.

[0003] As a technique for compounding this porous member,
JP-A-8-219203 discloses that after a ceramic porous body is set in a preheated mold, an aluminum alloy melt is filled into the mold by a molten metal forging method and solidified to thereby form a brake disk sliding surface. A method for combining is disclosed.

[0004]

When a ventilated brake disk rotor is partially compounded by a high-pressure casting method, a core for forming a cooling vent is not accurately positioned in a mold. It is conceivable that the rate of non-defective products deteriorates, and that the entry path of the molten metal is blocked by the core, so that the impregnating property of the molten metal into the porous member and the strength of the core are reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a core structure for casting capable of easily positioning and holding a core in a mold and improving the impregnation property of the molten metal and the strength of the core. It is to provide.

[0006]

In order to solve the above-mentioned problems and achieve the object, a casting core structure of the present invention connects an outer ring portion, an inner ring portion, and the outer ring portion and the inner ring portion. In an annular casting core structure having a connecting portion, in a state set in a cavity formed by a pair of dies, the outer peripheral surface of the outer ring portion is in contact with the outer peripheral surface of one of the dies. The inner ring portion is formed in a tapered shape such that a side surface portion into which the molten metal flows is flush with the connecting portion, and has a cantilever structure with the outer ring portion as a fulcrum inside the cavity.

Preferably, the inner peripheral surface of the inner ring portion is formed in a tapered shape so as to contact the inner peripheral surface of the other mold.

Preferably, a surface of the inner ring portion opposite to a side surface into which the molten metal flows abuts on a side surface of the other mold which is substantially perpendicular to a flowing direction of the molten metal.

Preferably, the outer ring portion, the inner ring portion and the connecting portion are formed with a step in the axial direction, and a preform for compounding with the molten metal is arranged at the step.

Preferably, the preform is partially compounded on a sliding surface of a ventilation type brake disk.

[0011]

As described above, according to the first aspect of the present invention, the outer peripheral surface of the outer ring portion is in contact with the outer peripheral surface of one of the dies when set in the cavity formed by the pair of dies. It is formed in a tapered shape so as to abut, the inner ring portion is formed such that the side portion into which the molten metal flows in is flush with the connecting portion,
With the cantilever structure having the outer ring portion as a fulcrum inside the cavity, the core can be easily positioned and held in the mold, and the impregnation property of the molten metal and the strength of the core can be enhanced.

According to the second aspect of the present invention, since the inner peripheral surface of the inner ring portion is formed in a tapered shape so as to come into contact with the inner peripheral surface of the other mold, the core can be accurately placed in the cavity. Positioning can be performed and the product can be easily die-cut.

According to the third aspect of the present invention, the surface of the inner ring portion opposite to the side surface into which the molten metal flows is brought into contact with the side surface of the other mold that is substantially perpendicular to the direction of flow of the molten metal. As a result, the core can be pressed against and adhered to the side surface of the mold, so that the core can be reliably positioned in the cavity, and the insertion of the molten metal can be suppressed to suppress burrs.

According to the fourth aspect of the invention, the outer ring portion, the inner ring portion, and the connecting portion are formed with a step in the axial direction, and the preformed body for compounding with the molten metal is arranged at the step. Using this step, the porous member can be reliably positioned.

According to the invention of claim 5, the preform is
By being partially combined with the ventilation type brake disk rotor sliding surface, the preform can be held in the cavity through a core for forming a cooling ventilation hole.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First Embodiment FIG. 1 is a partial cross-sectional view of a ventilated brake disk rotor casting mold in which a casting core and a composite porous member according to a first embodiment are arranged.
FIG. 2 is a front view of the casting core. FIG. 3 is a perspective view of a product after finishing processing, which is formed by the casting mold of the present embodiment.

The casting mold illustrated in FIG. 1 is used for high-pressure casting of a ventilated disc brake rotor made of an aluminum alloy.

The casting mold has a cavity 3 formed therein by closing a pair of an upper mold 1 and a lower mold 2. The lower mold 2 has a sprue 4 for filling a molten metal, and a sprue 4. The apparatus includes a sleeve 5 forming a communicating molten metal passage, and a movable plunger 6 for slidingly contacting an inner wall of the sleeve 5 to press-fit the molten metal to the gate 4. The molten metal is pushed up by the movable plunger 6 and introduced into the cavity 3 from the gate 4 at a high pressure.

The cavity 3 extends downward and is inclined (tapered) toward the center in the radial direction while lowering. The lower surface 2a extends downward from the lower end of the outer surface 2a toward the center in the radial direction. An upper die flat portion 1a extending radially from the upper end of the lower die outer peripheral surface 2a toward the radial center, and a lower die projecting surface 2c extending downward from the inner end of the lower die flat portion 2b and inclined (tapered) toward the radial center. A lower die protruding surface 2d extending radially from the lower end of the lower die protruding surface 2c, and an upper die protruding surface 1b extending downward from the inner end of the upper die flat portion 1a and inclined (tapered) toward the radial center. And an upper mold projecting surface 1c extending from the lower end of the upper mold projecting surface 1b to the center in the radial direction. Lower die outer peripheral surface 2
a and the upper mold projecting surface 1b are inclined so as to be substantially parallel to each other.

In the cavity 3, the lower die flat portion 2b and the upper die flat portion 1a form a rotor sliding surface forming space 3a, and the lower die protruding surface 2c, the lower die protruding flat surface 2d, and the upper die protruding surface 1d.
b and the upper mold protruding surface 1c form a hub mounting surface forming space 3b and also form a gate 4.

In the cavity 3, a sand core 7 for forming a cooling ventilation hole in the pressure portion of the rotor is disposed.

The sand core 7 is disposed in the cavity 3 so that the axis of rotation of the rotor and the axis of the sleeve 5 coincide with the line R. The outer ring portion 8, the inner ring portion 9, the outer ring portion 8, and the inner ring portion 9 are provided. Are formed in a disk shape concentric with a line R having a connecting portion 10 that connects the two. The connecting portions 10 are formed at equal intervals radially around the line R in the circumferential direction.

The sand core 7 is formed in a tapered shape such that the core outer peripheral surface 8a of the outer ring portion 8 abuts on the lower die outer peripheral surface 2a when placed in the cavity 3. The child inner peripheral surface 9a is formed in a tapered shape so as to contact the upper die projecting surface 1b. As a result, the sand core 7 is placed in the cavity 3
Can be positioned accurately within Also, since the lower die outer peripheral surface 2a and the upper die projecting surface 1b are inclined so as to be substantially parallel to each other, it is easy to remove the die from the product.

The side surface of the inner ring portion 9 facing the gate 4 includes:
For example, four portions are connected at equal intervals in the circumferential direction.
A deleted portion 9b is formed so as to be flush with the side surface portion 9c of the inner ring portion 9 opposite to the gate 4.
The upper die 1 comes into contact with the vicinity of the inner end of the upper die flat portion 1a substantially perpendicular to the inflow direction S of the molten metal. The sand core 7 has a cantilever structure with the outer ring portion 8 as a fulcrum in the cavity 3.

In the present embodiment, the deleted portion 9b is formed so as to be flush with the connecting portion 10 in a straight line.
It becomes easy for the molten metal to penetrate, so that the porous members 11 and 12 can be easily impregnated into the outer ring portion 8 remote from the gate 4.
Sanding out from the mold is also easy. In addition, since the unevenness of the surface of the sand core 7 is reduced, there is an advantage that a pressure-resistant coat layer for suppressing insertion of the molten metal can be easily formed.

The side surface 9c of the inner ring portion 9 opposite to the gate 4 comes into contact with the vicinity of the inner end of the upper die flat portion 1a which is substantially perpendicular to the flow direction S of the molten metal in the upper die 1, so that the pressure of the molten metal is reduced. As a result, the sand core 7 can be pressed against and adhered to the upper mold flat portion 1a, so that the sand core 7 can be reliably positioned in the cavity 3, and the insertion of the molten metal can be suppressed to suppress burrs. [Pressure Coating Jig] FIG. 4 is a view showing a jig used for forming a pressure coating layer on a sand core.

A pressure-resistant coating layer is formed on the surface of the sand core 7 in order to suppress the insertion of the molten metal, but the inner peripheral surface 9a of the inner core 9 and the upper die projecting surface 1b are closely adhered with high precision. The better the distance is, the smaller the gap is, the less likely the product is to be burr. In addition, even if this part does not form the pressure-resistant coat layer, the sand core 7
It is difficult for the molten metal to be inserted into the substrate (however, burrs are generated), and it is necessary to prevent deterioration in accuracy due to the pressure-resistant coating layer. In addition, the other portions are relatively easy to correct even if the pressure-resistant coat layer varies.

Therefore, in the present embodiment, the contact surface 21 of the jig 20 shown in FIG. By impregnating or spraying the pressure-resistant coating liquid in a state in which the pressure-resistant coating liquid is in close contact with and covered with the inner peripheral surface 9a of the inner ring 9, it is possible to prevent the pressure-resistant coating liquid from entering the inner peripheral surface 9a of the inner ring portion 9 A pressure-resistant coat layer can be formed in the portion.

The outer ring portion 8, the inner ring portion 9 and the connecting portion 10 are formed so as to have a step in the direction R in which the upper die 1 is opened with respect to the rotating shaft of the rotor, and both sides of the connecting portion 10 are combined with the molten metal. Member 1 such as a ceramic porous body preformed in advance
Numerals 1 and 12 are respectively disposed and partially combined with the brake disk rotor sliding surface. In other words, the porous member can be reliably positioned via the sand core using this step.

The porous members 11 and 12 are formed in an annular shape concentric with the line R.

As shown in FIG. 3, the ventilated brake disc rotor 20 cast at a high pressure using the casting mold has sliding surfaces 21 and 22 of the brake disc rotor.
The porous members 11 and 12 are formed into a composite, and the surface layer is cut by about 1 mm by finishing, and a plurality of cooling ventilation holes are radially provided between the rotor sliding surfaces 21 and 22 (rotor pressure portions). 25 are formed. Also, a convex hub mounting portion 2 protruding from the brake disk rotor sliding surface 21.
3, three screw mounting holes 24 are formed.

Brake disk rotor sliding surfaces 21, 22
Is formed by arranging a pre-formed body composed of porous ceramic particles / fibrous formed body in a mold, impregnating with an aluminum alloy melt, and solidifying.

As the porous member, besides a ceramic porous body, a metal fiber material made of stainless steel or the like can be used. Tungsten, molybdenum, carbon steel, and the like may be used as the metal fiber material in addition to stainless steel, but the stainless fiber material is practical since it has the highest strength and is inexpensive. [Second Embodiment] FIG. 5 is a partial sectional view of a ventilated brake disk rotor casting mold in which a casting core and a composite porous member according to a second embodiment are arranged.

As shown in FIG. 5, the sand core 17 of the second embodiment has two or more circumferentially extending (or two or more) circumferential steps at the step portion where the outer ring portion 8 and the inner ring portion 9 are connected to the connecting portion 10. A projection 18 is formed (over the entire circumference).

By providing these projections 18, the porous member 12 disposed between the lower die flat portion 2b and the lower surface of the connecting portion 10 can be easily pressed, and the upper die flat portion 1a and the connecting portion can be easily pressed. The porous member 11, which is disposed between the upper surface of the upper mold 10 and the upper surface, can be installed in the mold simply by placing the porous member 11 on the step. 1a and the lower die flat portion 2b can be respectively brought into close contact with each other.

Parts that are the same as in the first embodiment are given the same reference numerals, and description thereof is omitted. [Example] The casting conditions of the present embodiment are, as an example, a molten metal forging method in which pressure is applied at about 60 MPa and filling is performed at a filling speed of 50 mm / sec. .

The sand core of the present embodiment has a resin amount of 2.1 to 2.1.
2.3% by weight, bending strength about 6.5 MPa, particle size index (AF
S) The resin-coated shell core having an average particle diameter of 65 to 75 and an average particle diameter of 0.15 mm is formed as an example, and is formed by baking at 573 to 593K, blowing for 3 seconds, and curing for 40 seconds.

The above is a description of the embodiments and examples of the present invention. However, the aluminum alloy casting manufactured by the present invention is not limited to the ventilated brake disk rotor by the high-pressure casting method as in the above-described embodiments. However, the present invention can be applied to other parts requiring wear resistance and weight reduction. According to the present invention, in addition to the aluminum alloy,
For example, it can be applied to other light alloy castings such as a magnesium alloy.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a ventilated brake disk rotor casting mold in which a casting core and a composite porous member according to a first embodiment are arranged.

FIG. 2 is a front view of a casting core.

FIG. 3 is a perspective view of a product after a finishing process formed by a casting mold according to the embodiment.

FIG. 4 is a view showing a jig used for forming a pressure-resistant coat layer on a sand core.

FIG. 5 is a partial cross-sectional view of a ventilated brake disk rotor casting mold in which a casting core and a composite porous member according to a second embodiment are arranged.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Upper mold 2 ... Lower mold 3 ... Cavity 4 ... Gate 5 ... Sleeve 6 ... Plunger 7 ... Sand core 8 ... Outer ring part 9 ... Inner ring part 10 ... Connection part 11, 12 ... Porous member 20 ... Ventilated disc Brake rotor 23: Hub mounting surface 25: Cooling vent

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22D 19/00 B22D 19/00 E F16D 65/12 F16D 65/12 B

Claims (5)

[Claims] 1. An annular casting core structure having an outer ring portion, an inner ring portion, and a connecting portion for connecting the outer ring portion and the inner ring portion, wherein the ring is set in a cavity formed by a pair of molds. In this state, the outer peripheral surface of the outer ring portion is formed in a tapered shape so as to abut against the outer peripheral surface of one of the molds, and the inner ring portion has a side surface into which the molten metal flows in flush with the connecting portion. A core structure for casting, wherein the core structure has a cantilever structure having the outer ring portion as a fulcrum inside the cavity. 2. The casting core structure according to claim 1, wherein an inner peripheral surface of the inner ring portion is formed in a tapered shape so as to abut against an inner peripheral surface of the other mold. 3. The side surface of the inner ring portion opposite to the side surface into which the molten metal flows is in contact with a side surface of the other mold that is substantially perpendicular to the flowing direction of the molten metal. The described core structure for casting. 4. The outer ring portion and the inner ring portion and the connecting portion are formed so as to have a step in an axial direction, and a preform for compounding with the molten metal is disposed at the step. 4. The core structure for casting according to 3. 5. The core structure for casting according to claim 4, wherein the preform is partially compounded on a sliding surface of a ventilation type brake disk.