JP4909238B2 - Composite casting method - Google Patents

Description

  The present invention relates to a method for casting a composite material in which a preform is integrally formed on both surfaces of a metal substrate.

As a braking device installed in a vehicle, for example, there is a disc brake of a type in which a brake pad is pressed against a disc rotor.
In order to reduce the weight of the disk rotor, the base material may be made of a light alloy such as an aluminum alloy. In light alloys, since wear resistance is lowered, it is desirable to integrally form a wear-resistant member called a preform in the main part of the disk rotor.

Conventionally, a technique for integrally casting a preform is known (for example, see Patent Document 1).
JP 2003-139172 A (FIGS. 1 and 3)

Patent document 1 is demonstrated based on the following figure.
FIG. 6 is a diagram for explaining the basic principle of the prior art. As shown in FIG. 6A, the first preform 101 is placed on the lower mold body 102. The second preform 103 is held in the air. Next, the lower mold body 102 is lowered together with the upper sliders 104 and 104. The upper sliders 104, 104 move horizontally as indicated by arrows (1), (1) by the guide action of the inclined pins 105, 105. As a result of this movement, the second preform 103 is sandwiched between the core elements 106 and 106 as shown in FIG. Further, the first preform 101 is held by the bottom surfaces of the core elements 106 and 106.

  In this state, the molten metal is supplied as indicated by an arrow (2), the upper mold 107 is lowered as indicated by an arrow (3), and the molten metal is pressurized. When the hot water solidifies, the lower mold body 102 is raised together with the upper sliders 104 and 104. Thus, a cast product can be obtained.

However, since the first preform 101 is held by the core elements 106 and 106 and the second preform 103 is held between the core elements 106 and 106, the structure of the core elements 106 and 106 is complicated. This increases the equipment cost.
Simplification or reduction of the core elements 106, 106 is desired.

  An object of the present invention is to provide a casting technique that can eliminate the core element holding the first and second preforms and simplify the structure.

According to the first aspect of the present invention, the first preform is integrally formed on one surface of the metal base material, and the second preform having a smaller bulk specific gravity than the metal base material is formed on the other surface of the metal base material. In a casting method of a composite material formed by integrally forming a reform,
Preform mounting surface provided on the bottom of the lower die cavity, a first preform placing step of placing in close contact with the entire end surface of the first preform,
A pouring step of pouring a predetermined amount of molten metal into the cavity , so as to pour the molten metal from above onto the first preform which is placed on the preform placement surface and is not suppressed from above;
A second preform supplying step of floating the second preform on the poured molten metal;
Using the upper mold movable in the direction of pressurizing the molten metal against the lower mold, the molten metal is pressurized through the floated second preform, and the molten metal is used as the first preform and the second preform. And a molten metal impregnating step for impregnating the liquid.

  The invention according to claim 2 is a first preform having a shape in which the area of the upper surface is smaller than the area of the lower surface, and the outer periphery gradually decreases from the lower surface toward the upper surface. It is characterized by using.

  In the invention according to claim 1, the first preform is suppressed by the pressure of the molten metal, and the second preform is floated on the molten metal. As a result, the core element that holds the first and second preforms can be eliminated, and the equipment cost can be reduced.

In the invention according to claim 2, the first preform has a shape in which the area of the upper surface is smaller than the area of the lower surface, and the outer periphery gradually decreases from the lower surface toward the upper surface. adopt. When the first preform has a bulk specific gravity smaller than that of the molten metal and the molten metal wraps under the first preform, the first preform is lifted based on Archimedes' principle.
If the peripheral portion is a tapered portion, the tip of the tapered portion is more easily bent, and the taper portion adheres well to the preform mounting surface with the pressure of the molten metal from above, preventing the molten metal from wrapping around. . As a result, even the first preform having a bulk specific gravity smaller than that of the molten metal can be prevented from floating.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a composite material according to the present invention. The composite material 10 is integrally provided with a first preform 12 on one surface of an aluminum base material 11, and the other side of the aluminum base material 11 is shown. The second preform 13 is integrally provided on the surface, and a brake disc can be formed by performing bolt hole processing or the like.

  The first preform 12 is a molded product in which ceramic particles are integrated with a binder or a molded product formed by compressing ceramic fibers. By forming the molded article into a porous structure, the bulk specific gravity can be adjusted to 0.1 to 1.0. Since the specific gravity of aluminum is about 2.7, the first preform 12 having a bulk specific gravity in the range of 0.1 to 1.0 floats on the molten aluminum. The same applies to the second preform 13.

A method of casting the composite material having the above configuration will be described next.
FIG. 2 is a view for explaining the first preform placing step to the pouring step according to the present invention. As shown in FIG. 2A, a lower mold having a preform placing surface 15 provided at the bottom. 16, an upper mold 17 that enters the lower mold 16, and a rod 18 that raises and lowers the upper mold 17 are prepared. Then, the first preform 12 is placed in close contact with the preform placement surface 15 (first preform placement step).

  Next, as shown in (b), a predetermined amount of molten aluminum 19 is poured into the cavity 21 in the direction of pressing the first preform 12 against the preform mounting surface 15 from above. (Pour process).

  (C) is the c section enlarged view of (b), and the molten aluminum 19 has poor wettability with the first preform 12. Therefore, a hollow portion 23 having a substantially triangular cross section is generated at a corner portion where the side surface 22 of the first preform 12 and the preform placement surface 15 intersect. As a result, the molten aluminum 19 does not enter between the lower surface of the first preform 12 and the preform placement surface 15.

  It is known from Archimedes' principle that buoyancy acting on an object submerged in liquid corresponds to the mass of the liquid rejected by the object. However, this principle cannot be applied when there is no liquid on the lower surface of the first preform 12 as in this example. That is, as indicated by the downward arrow, the hydraulic pressure acts downward, and the first preform 12 does not rise.

  In (a), between the preform mounting surface 15 and the first preform 12 may be bonded with an adhesive having a weak adhesive force. “Adhesive strength is weak” means such a force that the molded product can be easily removed from the lower mold 16 during demolding. As a result, production time can be shortened and productivity can be improved.

  FIG. 3 is a view for explaining the process from the second preform supply hot water process to the molten metal impregnation process according to the present invention. As shown in FIG. 3A, the second preform 13 is gently placed on the molten aluminum 19. And as shown in (b), since the 2nd preform 13 has a bulk specific gravity smaller than the molten aluminum 19, it floats on the molten aluminum 19 (2nd preform supply hot water process).

  Next, as shown in (c), the molten aluminum 19 is pressurized through the floated second preform 13 using the upper mold 17 that can move in the direction of pressurizing the molten metal against the lower mold 16. The first preform 12 and the second preform 13 are impregnated with the molten aluminum 19 (melt impregnation step). Thus, the composite material 10 shown in FIG. 1 can be obtained.

  As shown in FIG. 3B, the first preform 12 was suppressed by the pressure of the molten metal 19, and the second preform 13 was floated on the molten metal 19. As a result, the core element that holds the first and second preforms 12 and 13 can be eliminated, the structure can be simplified, and the equipment cost can be reduced.

Next, another embodiment of the present invention will be described.
FIG. 4 is a diagram showing another embodiment of FIG. 1. Elements common to those in FIG. The difference from FIG. 1 is the shape of the first and second preforms 12B and 13B. That is, the first preform 12B has a shape in which the area of the upper surface 26 is smaller than the area of the lower surface 25, and the outer periphery gradually decreases from the lower surface toward the upper surface. This is a tapered portion 27 having a pointed tip. The second preform 13 is the same as the first preform 12 except that the top and bottom are reversed.

  FIG. 5 is another embodiment of FIGS. 2B and 2C. As shown in FIG. 5A, the first preform 12B is placed on the first preform 12B from above as shown in FIG. A predetermined amount of molten aluminum 19 is poured into the cavity 21 in the direction of pressing to 15 (a pouring step).

  (B) is an enlarged view of part b of (a), and the pressure of the molten aluminum 19 is applied to the first preform 12B as indicated by a downward arrow. At this time, since the tip of the taper portion 27 is thinner, the taper portion 27 is easily bent, and as a result, the taper portion 27 is more closely attached to the preform placement surface 15. As a result, it is possible to more reliably avoid the molten aluminum 19 from wrapping around the lower surface of the first preform 12B.

  The taper part 27 should just become thin toward the front, for example, can be changed into a step part.

  In addition, although the metal material which comprises the base material 11 has preferable aluminum or aluminum alloy other than an aluminum alloy, the alloy which uses another metal as a matrix may be sufficient.

  Further, the composite material of the present invention is not limited to a vehicle disk rotor, and may be a vehicle brake drum or other mechanical parts.

  The present invention is suitable for a casting method of a vehicle disk rotor.

It is sectional drawing of the composite material which concerns on this invention. It is a figure explaining from the 1st preform mounting process to a pouring process concerning the present invention. It is a figure explaining from the 2nd preform supply hot water process to a molten metal impregnation process concerning the present invention. It is another Example figure of FIG. It is another Example figure of FIG.2 (b) and (c). It is a figure explaining the basic principle of the prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Composite material, 11 ... Aluminum base material, 12, 12B ... 1st preform, 13, 13B ... 2nd preform, 15 ... Preform mounting surface, 16 ... Lower mold | type, 17 ... Upper mold | type, DESCRIPTION OF SYMBOLS 19 ... Molten aluminum, 21 ... Cavity, 25 ... Lower surface of 1st preform, 26 ... Upper surface of 1st preform, 27 ... Tapered part.

Claims (2)

A composite in which a first preform is integrally formed on one surface of a metal substrate, and a second preform having a bulk specific gravity smaller than that of the metal substrate is integrally formed on the other surface of the metal substrate. In the material casting method,
Preform mounting surface provided on the bottom of the lower die cavity, a first preform placing step of placing in close contact with the entire end surface of the first preform,
A pouring step of pouring a predetermined amount of molten metal into the cavity , so as to pour the molten metal from above onto the first preform which is placed on the preform placement surface and is not suppressed from above;
A second preform supplying step of floating the second preform on the poured molten metal;
Using the upper mold movable in the direction of pressurizing the molten metal against the lower mold, the molten metal is pressurized through the floated second preform, and the molten metal is used as the first preform and the second preform. And a molten metal impregnation step for impregnating the composite material.   The first preform has a shape in which the area of the upper surface is smaller than the area of the lower surface and the outer periphery gradually decreases from the lower surface toward the upper surface. The method for casting a composite material according to claim 1.

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