JP3073105B2 - Manufacturing method of light alloy composite member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a preform containing a reinforcing material such as ceramic short fibers, ceramic whiskers and particles, which is impregnated with a light alloy melt by means such as a high-pressure casting method. The present invention relates to a method for manufacturing an alloy composite member.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a preform of this type, for example, a suction dehydration forming method as shown in FIG. 5 has been generally used. According to this suction dehydration molding method, the preform is prepared by mixing and stirring a reinforcing material and a small amount of an inorganic binder (silica sol, etc.) in water to prepare a raw material slurry 1, Type 2
And a step of suction dehydration through the filter 3, and thereafter, a molded body 4 made of a reinforcing material deposited on the filter 3.
Taking out, heating and drying this, then firing and partially binding the reinforcing material with an inorganic binder,
It is manufactured through

[0003] Such a preform can be obtained not only in a disk shape shown in Fig. 5 but also in a shape corresponding to a portion requiring reinforcement. For example, Japanese Patent Publication No. 4-25335 discloses an engine preform. There is disclosed a technique for performing suction dehydration molding of a cylindrical preform used for strengthening a cylinder liner.

[0004]

However, the conventional suction dehydration molding method has the following problems. That is, the molded body 4 after suction dehydration contains a large amount of water and has poor shape retention, and easily collapses in the handling process from drying to firing. Cracks, deformations and dimensional changes are liable to occur in the course of drying and firing. Cracks are likely to occur in the preform during the process of setting it in a high-pressure casting mold or the process of impregnating with a molten alloy.

In order to solve such problems, it is effective to improve the strength of a molded article by using an organic binder such as polyvinyl alcohol or increasing the amount of an inorganic binder. However, when the amount of the binder is increased, the suction moldability is greatly reduced due to the increase in the viscosity of the slurry, and the alloy component (Mg) in the impregnated light alloy melt is consumed by reacting with the inorganic binder SiO _2, and the composite member is consumed. However, there is a drawback such as a decrease in the performance of the binder, and there is a limit in increasing the amount of these binders.

On the other hand, since the reinforcing material used for forming the preform is generally expensive, from the viewpoint of using the minimum necessary reinforcing material in a necessary portion, recently, with the thinning of the shape of the preform, There is a need for a reduction in the volume fraction of the reinforcement. For example, a cylindrical preform used to reinforce the liner portion of an engine cylinder requires a thickness of about 3 mm from the viewpoint of the reinforcement effect, and the volume ratio of the reinforcer is conventionally 10 to 30%. It is known that even if this is set to about 5%, there is no particular problem from the viewpoint of the reinforcing effect.

However, when the thickness of the preform is reduced in this way, the shape retention of the molded body after suction dehydration and the strength after firing are further deteriorated, while the volume ratio of the reinforcing material is 5%.
It is difficult to reduce to the extent by the normal suction dehydration molding method, and also the shape retention of the molded body after the suction dehydration and the strength after firing are reduced, so the above-mentioned problems are more than before. It is inevitable that it will become apparent.

Further, in the case where, for example, a cylindrical preform is formed by a conventional suction dehydration molding method, as shown in the above-mentioned Japanese Patent Publication No. 4-25335, the number of steps required until a preform is obtained is large. However, there is a problem that the preform material may be damaged in the process of removing the cylindrical filter (referred to as a mold in the same publication).

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and does not have the above-mentioned problems. In addition, the present invention is intended to reduce the thickness of the preform and reduce the volume ratio of the reinforcing material. It is another object of the present invention to provide a method of manufacturing a light alloy composite member that can flexibly cope with the above and can simplify the process.

[0010]

In order to achieve the above object, a method for producing a light alloy composite member according to the present invention comprises immersing a porous metal body having continuous air holes in a liquid containing a reinforcing material, By applying a suction action to the body, the reinforcing material is dispersed in the pores and dried to form a preform, which is then placed in a molding die and the light alloy melt is impregnated in the pores. I do. The same effect can be obtained by applying a pressurizing action to the slurry from the outside instead of the suction action.

As described above, the preform according to the present invention comprises the porous metal body and the reinforcing material dispersed in the pores. Here, the porous metal body refers to a three-dimensional porous body having continuous ventilation holes and having a filter function. For example, a conductive substance is attached to the inner surface of the foamed urethane resin to make it conductive, and then the metal is plated. And then a commercially available foamed metal produced by burning off the urethane resin (see FIG. 4)
Is preferable, and its porosity is about 70 to 98%. The reinforcing material may be any material that improves the strength and abrasion resistance of a light metal serving as a base material, such as particles of ceramic short fibers, whiskers, and graphite, and may be used in combination.

When the present invention is applied to, for example, a cylinder of a cylinder block for an engine, a cylindrical metal porous body is used, and preferably a fine-grained filter (filter paper or the like) is brought into contact with an inner peripheral surface of the cylindrical metal porous body. It is preferable to apply a suction action from the inside of the body to disperse the reinforcing material at a high concentration inside the cylindrical porous metal body. Further, after the light alloy impregnation, heat treatment may be performed to form an intermetallic compound between the porous metal body and the light alloy base material.

[0013]

According to the present invention, when a porous metal body having continuous air holes is immersed in a liquid containing a reinforcing material and a suction action or a pressurization action is applied to the porous metal body, the porous body performs a filter function, Is discharged through the continuous vent, and most of the reinforcement is trapped in the pores, so that the reinforcement is concentrated and accumulated in the pores. Next, by drying the entire porous metal body, a porous metal body in which the reinforcing material is substantially uniformly dispersed in the pores, that is, a preform can be obtained.

Although it is difficult to form a preform having a low volume ratio of the reinforcing material by the conventional suction dehydration molding method described above, in the present invention, the amount of the reinforcing material deposited can be freely selected. Therefore, a preform having a low volume ratio of, for example, about 5% can be easily formed.

The preform according to the present invention is:
Since the shape is maintained by the porous metal body, collapse and cracks during handling, drying, and firing can be completely prevented, and the dimensional accuracy of the preform is improved. Furthermore, since the rigidity is high even when the preform is thin, it can be easily set and positioned in a casting mold, and cracks do not occur due to the pressure of the molten alloy impregnated at a high pressure. Obtainable.

In the present invention, since the reinforcing material is held in the pores of the porous metal body, unlike the conventional preform molding method, it is not necessary to add an inorganic binder to the liquid, and thus it is not necessary to fire. Absent. However, by baking after drying using a small amount of inorganic binder, it is possible to increase the bonding strength between the reinforcing materials and between the reinforcing material and the porous metal, and to prevent the reinforcing material from falling off near the surface of the porous metal. Therefore, an inorganic binder may be added as needed. In addition, a surface-active agent may be added to improve the dispersibility of the reinforcing material in the liquid, and the like can be appropriately performed.

When it is necessary to reinforce one surface of the composite member, for example, when it is necessary to improve the abrasion resistance of the inner peripheral surface thereof, for example, as in a cylinder of an engine cylinder block, a cylindrical metal porous member is used. A fine filter such as filter paper is brought into contact with the inner peripheral surface of the body to apply a suction action from the inside of the porous metal body. Then, the reinforcing material that tries to flow out through the continuous ventilation holes is blocked by the filter paper and accumulates near the inner surface of the cylindrical porous metal body. Performance can be improved. In addition, it goes without saying that the method of using the filter as described above can be applied to the case of manufacturing other members.

Further, in the present invention, when any one of Ni-base, Cu-base and Fe-base is used as the metal porous body and the heat treatment is performed after the impregnation of the light alloy, the interface between the porous metal body and the light alloy base material is used. A hard intermetallic compound is formed in the composite member, and the strength and wear resistance of the composite member can be further improved. When the intermetallic compound is formed, it is desirable that the preform be fired in a vacuum so that an oxide film is not formed on the surface of the porous metal body.

[0019]

Embodiments of the present invention will be described below.

(Example 1) As a porous metal body, a porosity of 9 was used.
5%, 44-55 pores / inch (2.54 cm) Ni-based foamed metal (5 mm thick disk) was used, and aluminum borate whisker (fiber diameter 1 μm) was used as a reinforcing material.
Hereinafter, the average length was 30 μm). The above whisker and a small amount of silica sol are mixed with water, and the whisker is mixed with water at 5% by weight.
% Raw material slurry was prepared. Next, the above porous metal body is set in the same suction dehydrator as in FIG. 5 (however, a filter is not used), and the above raw material slurry is supplied to perform suction dehydration to concentrate whiskers inside the porous metal body. Deposited.

Subsequently, the porous metal body was taken out of the suction device, dried at 100 ° C., kept at 700 ° C. in a vacuum, and fired to obtain a disc-shaped preform. From the result of the weight measurement of the preform after firing, the volume ratio of the whisker was about 10
% (Including the porous metal body, 15%). This was placed in a high-pressure casting mold, and a molten aluminum alloy (JIS, AC8A) was impregnated at high pressure to obtain a disc-shaped composite member.

Example 2 Porous metal having a porosity of 9 was used.
0%, 26 to 35 pores / inch (2.54 cm) Ni-based cylindrical foamed metal (outer diameter 80 mm, wall thickness 5 mm,
Height 150 mm) as graphite particles (average diameter 2
μm) was used. Graphite particles and a small amount of a surfactant were mixed in water to prepare a raw slurry of about 20% by weight of the graphite particles.

Next, as shown in FIG. 1, a filter paper 11 is applied to the entire inner peripheral surface of the cylindrical porous metal body 10, both ends of which are sealed with jigs 12 a and 12 b, and set in a dewatering tank 13. The raw material slurry 14 was supplied into the dewatering tank 13 and suction-dewatered, and whiskers were concentrated and deposited inside the porous metal body 10.

Subsequently, the porous metal body 10 is removed from the dewatering tank 13.
, Dried at 100 ° C and cylindrical preform 2
0 was obtained. From the result of the weight measurement, the volume ratio of the graphite particles was about 7
% (Including the metal porous body, 17%). Figure 2
Alternatively, a composite member was obtained by placing in a high-pressure casting mold (detailed in the following paragraph) shown in FIG. 3 and casting a molten aluminum alloy (JIS, AC8A) at high pressure. Further, a solution heat treatment at 500 ° C. × 6 hours was performed to form an intermetallic compound of Ni and Al at the interface between the porous metal body and the aluminum alloy, followed by a tempering heat treatment.

FIG. 2 shows an example of a high-pressure casting apparatus for manufacturing a cylinder liner by impregnating a cylindrical preform 20 with a molten aluminum alloy. This high-pressure casting machine is an upper mold 2
1, a cylindrical preform 20 is set in a cavity formed by an upper mold 21 and a lower mold 22. The cylindrical preform 20 includes a lower mold 22, a sleeve 25 in contact with the lower mold 22, and a punch 26 sliding in the sleeve 25. Then, the Al alloy melt 27 is impregnated into the pores of the preform 20 by the pressing force of the punch 26.

FIG. 3 shows an example of a high-pressure casting apparatus for integrally manufacturing a cylinder block in which a cylindrical preform 20 is impregnated with an Al alloy melt and only a cylinder liner portion is compositely reinforced. The high-pressure casting apparatus includes an upper die 31, a lower die 32, a side die 33, a sleeve 25 that contacts the lower die 32, and a punch 26 that slides inside the sleeve 25.
The upper mold 31 and the lower mold 32, and the side mold 33
The cylindrical preform 20 is set at a predetermined position in the cavity constituted by the following, and the Al alloy melt 27 is caused to flow into the cavity by the pressing force of the punch 26 and at the same time is impregnated into the pores of the preform 20. is there.

[0027]

According to the present invention, since the preform in the present invention is maintained in shape by the porous metal body, collapse and cracks during handling, drying and firing can be completely prevented, and the precision of the preform is improved. In addition, since the rigidity is high even when the preform is thin, it can be easily set and positioned in a casting mold, and no crack is generated by the pressure of the molten alloy impregnated at high pressure. Furthermore, it was difficult to form a preform having a low volume ratio of the reinforcing material by the conventional suction dehydration molding method, but in the present invention, the amount of the reinforcing material deposited can be freely selected, and the preform having a low volume ratio can be obtained. It can be easily formed even by reforming.

Further, in the present invention, since the porous metal itself plays the role of a filter, it is not necessary to peel off the reinforcing material and the filter as in the prior art, so that the process is simplified and the preform material is reduced. There is also an effect that there is no possibility of damage.

In addition, when a hard intermetallic compound is formed between the porous metal body and the light alloy base material, the strength and wear resistance of the composite member can be further improved.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating a suction dehydration molding method in an example of the present invention, and FIG. 1B illustrating a formed cylindrical preform.

FIG. 2 is a sectional view of a main part of a high-pressure casting apparatus according to an embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a high-pressure casting apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic view of a foam metal used in the present invention.

FIG. 5 is a diagram illustrating a conventional suction dehydration molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cylindrical porous metal body 11 Filter paper 12a, 12b Jig 13 Dehydration tank 14 Slurry 20 Cylindrical preform 21, 31 Upper mold 22, 32 Lower mold 25 Sleeve 26 Punch 27 Al alloy melt 33 Side mold

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02F 1/00 C22C 1/09 A (56) References JP-A-60-108157 (JP, A) JP-A-59-212159 ( JP, A) JP-A-2-97629 (JP, A) JP-A-4-22558 (JP, A) JP-A 1-268827 (JP, A) JP-A-3-8551 (JP, A) JP JP-A-4-22559 (JP, A) JP-A-3-18963 (JP, A) JP-A-1-283330 (JP, A) JP-A-60-21306 (JP, A) JP-A-61-105316 (JP) (A) JP-A-61-9537 (JP, A) JP-A-61-144236 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 19/00 B22D 17/00 B22D 18/02 C22C 1/10 C22C 47/08 F02F 1/00

Claims (3)

(57) [Claims] 1. A porous metal body having continuous vents is immersed in a liquid containing a reinforcing material, and the reinforcing material is dispersed in the pores by applying a suction action or a pressurizing action to the porous metal body and dried. Thereafter, a method of manufacturing a composite member made of a light alloy, comprising disposing the porous metal body in a mold and impregnating the pores of the porous metal body with a light alloy melt. 2. The composite member is a cylinder of an engine cylinder block, wherein a filter is brought into contact with an inner peripheral surface of the cylindrical porous metal body, and a suction action is performed from the inside of the cylindrical porous metal body.
The method for manufacturing a light alloy composite member according to claim 1, wherein the reinforcing material is dispersed at a high concentration inside the cylindrical porous metal body. 3. The production of a light alloy composite member according to claim 1, wherein an intermetallic compound is formed between the porous metal body and the light alloy base material by further performing a heat treatment. Method.