JPS60174236A - Casting mold for fiber reinforced metallic casting mold and casting method using said mold - Google Patents

Abstract

PURPOSE:To decrease the energy loss in the stage of preheating a casting mold and to reduce at the same time the time for casting in the stage of manufacturing a titled casting by a molten metal forging method by constituting the casting mold of a master mold and liner molds split to >=2 parts. CONSTITUTION:A liner mold 1 in the case of producing, for example, a connecting rod of an internal combustion engine consists of a liner mold 2 to serve as a vessel for a molten metal and a liner cope 3 to be fitted to the tapered inside wall surface 2 on the inside circumferential surface thereof from above. The mold 1 is first preheated and is once cooled after coating of a parting material thereon. A fiber bundle is disposed in the drag 2 and the cope 3 is placed on the top side of the drag 2 to assemble the mold 1. The mold 1 is then preheated to remove the coating material on the surface of the fiber bundle and to improve run and thereafter the mold is put into a drag 6 and while the top surface of the cope 3 is lightly pressed by the cope 7, the molten metal is poured through a hole 5a for a pressurizing punch and a sprue 5 into the mold space 11 of the mold 1. The cope 7 is thereafter clamped by pressing and a punch 4 is lowered to press the molten metal. The punch 4 and the cope 7 are released of the pressurization after waiting for the solidification of the molten metal. Knock-out pins 9 are risen after the rise of the cope 7 to remove the cope 3 and a produce 12. The drag 2 is further removed from the cope 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fiber-reinforced metal casting mold for manufacturing fiber-reinforced metal parts by a molten metal forging method (high-pressure casting method) and a casting method using this mold.

(Background technology) Generally, when making fiber-reinforced alloys by molten metal forging, a relatively thick mold consisting of an upper mold, a lower mold, knockout pin holes, etc. is used, and this mold is preheated to form a fiber reinforced alloy. After preheating (inserting a bundle or inserting a fiber bundle) and pouring the molten metal into the molten metal, the molten metal is solidified under pressure.

A feature of producing mm-reinforced alloys using this molten metal forging method is that fiber-reinforced alloys containing 30 to 60 volume % of fibers can be obtained relatively easily. However, when the volume of fibers is large relative to the matrix metal, for example, carbon fiber bundles of 8 pmφ are ideally placed at equal intervals of 5
When the content is 0% by volume, a fairly narrow gap between fiber bundles (
For example, about 31 Lm), the A pattern molten metal is infiltrated, and even though it is a molten metal forging method, the fiber bundle is generally at least 40 Lm thick.
If it is not heated to a high temperature of 0℃ or higher, the AM molten metal will not circulate properly.
Penetration is not sufficient.

Therefore, in this case, it is necessary to preheat the mold sufficiently, but if the mold is overheated, not only will its life be shortened, but the fiber bundle will also be inserted.

This makes it difficult to arrange the tIA fibers regularly. In addition, because conventional molds have a relatively large heat capacity, it takes a long time to heat the mold, and
Another problem has arisen: a large amount of energy is consumed. Furthermore, when using a mold, the large heat IIfi of the mold during solidification
There are also disadvantages such as stress generated in the casting due to No. 1, and its removal becomes a problem.

(Objective of the Invention) The object of the present invention is to reduce the energy loss consumed during preheating when manufacturing fiber-reinforced metal parts by molten metal forging, reduce casting time, and maintain good quality of the product. The aim is to improve productivity while at the same time improving productivity.

(Summary of the structure of the invention) The fiber-reinforced metal casting mold of the present invention is provided with a lower mold that is separably housed inside the outer mold, and the lower mold is made up of at least two split molds. It has a mold space inside.

The lower mold is divided vertically, horizontally, or as appropriate depending on the product shape and molten metal forging equipment. The pouring hole provided in the lower mold may be formed at any position as long as it communicates the mold space with the outside, and a corresponding pouring hole is formed in the outer mold. The outer mold is placed in a pressing mechanism of a molten metal forging device, and divided into shapes suitable for mounting and pressing a lower mold.

In the casting method of the present invention, a predetermined amount of fiber bundles are placed in a lower mold, heated in a furnace for a predetermined period of time, and the lower mold is placed in an outer mold (mold) divided into at least two parts. A predetermined amount of molten metal is poured into the lower mold, the molten metal is pressed through the outer mold and the molten metal is pressurized with a punch, and after solidification, the product is removed.

Typically, the outer mold is divided into two parts, an upper mold and a lower mold, and in the case of simple-shaped castings, the lower mold is divided into upper and lower parts and is placed inside the outer mold. It includes at least a spout communicating with the upper mold, and typically also includes a no-kout pin hole that passes through the lower outer mold and the upper nest mold. The pouring spout is generally also used as a hole for pressurizing the molten metal.

The present invention is particularly effective when using long fibers as the fiber bundle, but it is also possible to use short fibers or a combination thereof, or it is also possible to pour a molten metal in which short fibers are dispersed and mixed in the molten metal in advance. can.

According to the present invention, the above-mentioned drawbacks of the conventional method are basically eliminated, and fiber-reinforced metal castings of various shapes and sizes can be stably mass-produced with fiber distribution/orientation according to a given purpose. It becomes possible.

Preferred embodiments of the present invention will be described below based on Examples, but the present invention is not necessarily limited to the disclosed matters, and modifications that are obvious to those concerned belong to the present invention.

(Preferred Embodiment) As a typical example, the lower inserting mold is composed of an upper inserting mold and an upper inserting mold having a shape corresponding to the manufacturing part (casting product),
The upper nesting die is formed with an opening that is closed by the upper nesting die and a hole through which a knockout pin is inserted when taking out the cast product. The upper nesting mold has an appropriate draft angle so that the outer peripheral side surface fits into the upper part of the inner peripheral wall surface of the upper nesting mold, and this upper nesting mold has holes for pressurizing punches and holes for pouring molten metal. . When a nesting upper mold is fitted into a nesting upper mold, the top surface of the nesting upper mold is always located above the outer edge top surface of the nesting upper mold so that sufficient clamping force is applied when the mold is clamped with the outer mold upper mold. Set it to do so.

It is desirable that the dimensions of the lower mold fit exactly within the upper and lower molds, taking into account thermal expansion, and the wall thickness should be set to ensure rigidity to the extent that it will not deform under the pressure of molten metal forging. .

It is preferable to use die steel or heat-resistant steel as the material for the lower mold, but carbon steel, ordinary cast iron, ductile cast iron, etc. are also sufficient for use. When silicon carbide, alumina, etc. are used as reinforcing fibers in a cast product, steel or ductile cast iron is preferred. In the present invention, it is also preferable that the lower mold is made of ceramic having a small thermal wPi coefficient. That is, in that case, the coefficient of thermal expansion of #1 Ifa reinforced metal is generally 50 vol.
In the case of %m fibers (SiC, C, etc.), the coefficient of thermal expansion is approximately αζ3' It is extremely useful in preventing the occurrence of

The external structure of the outer mold that accommodates such a lower mold may be the same as that of a mold used in conventional molten metal forging methods. That is, the outer mold typically consists of an upper mold and a lower mold, and its accessories include a punch for pressurizing the molten metal,
Equipped with a knockout bin for removing molded products from the mold.

The material of the upper mold and the lower mold is preferably molded steel as in the past, but cheaper alloy steel, carbon steel, etc. may also be used. Since the molten metal does not come into direct contact with the upper mold and the lower mold, it is not necessary to use expensive steel materials having heat resistance and heat fatigue resistance. In addition, the shapes of the upper mold and lower mold are set in relation to the above-mentioned materials so that they can sufficiently withstand the pressure applied after pouring. In this way, the fiber bundle is placed inside, the preheated lower mold is fitted into the lower mold as an outer mold, and the upper mold is placed over the lower mold to drain the molten metal and forge the predetermined molten metal.

After waiting for the metal to solidify, the suppressing (pressurizing) force is released, and the mold is demolded using a knock-out bin, etc. After demolding, the lower mold is removed from the pass-through mold, and then the fiber bundle is preheated with seriton. A new lower mold is attached to the outer mold and the next cycle is performed.

The fiber bundle may be appropriately bonded with a temporary (heat-disappearing) binder (e.g., polyvinyl alcohol (PVA), ethyl alcohol) so as to maintain the desired external shape when it is charged into the lower mold. Preferably, in that case, the binder is volatilized or gasified during preheating (preferably above 500° C.).

Note that this preheating is performed in a non-oxidizing atmosphere to avoid damage to the fibers.

(Effects of the Invention) According to the molten metal forging method (high-pressure forging method) of the present invention, a fiber bundle is placed in advance in the lower mold that is taken out from the outer mold, and the fiber bundle is heated (preheated) together with the lower mold. Therefore, the heat capacity of the lower mold is smaller than that of conventional molds, and the energy consumption required for heating can be reduced.

When inserting the fiber bundle into the lower mold, the fiber bundle can be placed while the surroundings are at room temperature, so the fiber bundle can be placed in a predetermined location accurately and skillfully.
The fear of damaging the fiber bundle can also be avoided. therefore,
The quality of the finished product is maintained well without any casting defects.

In addition, because the lower heat capacity mold is heated separately outside the molten metal forging equipment, sufficient preheating can be achieved in a short time, and the pouring cycle of the equipment is significantly shortened, improving productivity. do. This also uniformly improves the running characteristics during pouring and the course of solidification temperature, resulting in a sound product. Roughly, the mold for molten metal forging has been simplified, and only the lower mold comes into contact with the molten metal, so damage to the mold due to cracks caused by thermal fatigue, etc. can be avoided, and even if damage occurs, the lower mold can be easily removed. An exchange is sufficient.

This increases the degree of freedom in selecting the material of the mold and makes it possible to minimize the difference in thermal expansion between the mold and the fiber-reinforced casting, thereby preventing large stress from occurring in the casting during the solidification process.

(Example) An example of the lower mold of the present invention will be explained based on the drawings.

FIG. 1 shows a lower mold for manufacturing a connecting rod for an internal combustion engine using the mold of the present invention.

The inserting lower mold 1 consists of a nesting lower mold 2 that serves as a container for molten metal, and a nesting mold 2 3 that fits into this inner circumferential wall surface 2a from above. A predetermined draft angle for removing the upper die 3 is provided. In this case, a pouring port 5 for pouring metal (not shown in FIG. 2) is provided through the nested upper die 3 from the top surface to the bottom surface. Other nested lower mold 2
A hole 10 is formed in the hole 10 for inserting a knockout bin for pushing up the bottom of the product (casting) from below with a knockout pin when the product (cast product) is extracted.

Next, to explain in detail an example of the casting method using this lower mold l, first, a JIS standard 355G lower mold is preheated to 600°C, and a mold release agent such as graphite powder is sufficiently applied to it. Cool once. Thereafter, approximately 500 Nicalon fiber bundles are properly placed inside the lower mold 2. At this time, while soaking the Nicalon fiber bundle with ethanol, tightly pack the connecting rod (product) so that each cross section has 300 yarns. The upper nesting mold 3 is placed above this lower nesting mold 2.
and assemble the lower mold 1 as shown in Figure 1(A).

The assembled lower mold 1 is heated (preheated) at 600° C. for 20 minutes in the atmosphere to remove the surface coating agent from the fiber bundles and improve the flow of the hot water during pouring.

Then, as shown in Fig. 2, the heated lower mold 1 is placed in the lower mold 6 as an outer mold, and then the upper mold 7 is pressed while lightly pressing the top surface of the upper mold 3. Punch hole 5a
, pour hot water into the mold space ll of the lower mold 1 through the pouring spout 5. At this time, the upper mold 7 is tightened to a pressure that does not cause poor water flow. This is to vent air during pouring.

When the pouring is completed, the upper mold 7 is heated to 50 mm as shown in FIG.
Tighten firmly with a pressure of 0 kg/cm'10, then lower the punch 4 to tighten it to, for example, 500 kg/cm.
Press the molten metal with cm'. The reason why the upper mold clamping pressure is made larger than the punch pressure is to prevent the occurrence of frizz and to avoid the occurrence of disorder in the orientation of the fibers.

After applying pressure with the punch 4 (molten metal forging), wait for the molten metal to solidify, remove the pressure between the punch 4 and the upper mold 7, and raise the upper mold 7 to a predetermined height as shown in Fig. 4. A cutting die metal frame 8 having a U-shaped cross section is inserted between the upper die 7 and the lower die 6 from the side. The outer edge of the lower insert die 2 is positioned at the lower end of this metal frame 8 for cutting die.

Then, the knockout pin 9 penetrated by the lower die 6 is pushed upward to the nested upper die 3 and the connecting rod (product) 12.
is pulled out to the outside, and the knockout pin 9 is further raised to push the bottom surface of the nested lower die 2 upward with its stepped portion 9a, and the knockout pin 9 is extracted from the lower die 6.

In this way, the series of molten metal forging steps is completed, and in this embodiment, from this last nest extraction step, the process returns to the above-mentioned fiber bundle arrangement step (first step), and these continuous operations are repeated.

The material of the lower mold in this example was 355C, but
If a molded product such as the connecting rod product 12 contains a large amount of carbon fiber or has a complicated shape, the thermal *i coefficient of carbon fiber is relatively small, so it is necessary to The mold is preferably made of ceramic/resist, such as silicon nitride or silicon carbide, which has a low coefficient of thermal expansion. In the present invention, the upper mold and the lower mold do not necessarily need to be made of the same material.

In the above example, by using a lower mold, it is possible to significantly reduce the energy consumption in the preheating process during high-pressure casting, and by preparing a large number of lower molds, continuous and rapid operation can be achieved. This makes it possible to further increase casting efficiency (molten metal forging efficiency), and can be expected to improve productivity.

In addition, as the fiber material for reinforcing the fiber reinforced metal produced by the mold of the present invention, for example, A-mon 203 (thermal expansion coefficient α 8×10/'C) C system (carbon, graphite) (αqO) SiC (trade name Two carons.

az 3 Zn alloy (additional element A pattern, etc.), Mg alloy (additional element A pattern, etc.) etc. are common, but are not limited to these.

In this case, the ratio of fiber material and matrix metal is 3
Production becomes easy in the range of 0 to 60vo 1%. This is because if it exceeds 60vo1%, the hot water flow deteriorates, and if it is less than 30, the strength decreases significantly. The fiber material may be either short fiber or long fiber. When using carbon fibers as the fiber material, it is desirable to heat (preheat) in an inert gas such as N2 or Ar. When using fiber materials such as alumina and silicon carbide, they may be heated in the atmosphere.

[Brief explanation of the drawing]

FIG. 1(A) is a sectional view taken along line II in FIG. 1 (CB) showing a nested mold according to an embodiment of the present invention, FIG. 1(B) is a plan view of the lower nested mold, and FIG. ) is a bottom view of the upper nesting mold. 2 to 4 are process explanatory diagrams showing the casting process in an embodiment of the present invention. 1 , , , , , , , , , Nested type 2 , , , , , , , , , , Nested lower type 3 , , , , , , , , , Nested type 2 4 , , , ,
,,,,,Punch 5......Pouring port 5 a,,,,,,,0. Pressure punch hole 6...
・・・・・・Lower die 7 ・・・・・・・・・Upper die 9 , , , , , , Knockout pin 10 ,,
,,,,,,, Knockout pin insertion hole 12,,,
,,． 0. ,, Connecting rod product applicant Toyota Central Research Laboratory Co., Ltd. Toyota Automatic Loom Works Co., Ltd. Agent Patent attorney Heating Asamichi Figure 1 (A) (B) (C) Figure 2 Figure 3

Claims (1)

[Scope of Claims] (A nested mold is provided inside the outer mold so as to be separable from the outer mold, and the nested mold is comprised of at least two split molds and has a mold space inside. A mold for fiber-reinforced metal casting. (2) The nested mold is composed of an upper nested mold and a lower nested mold, and the upper part of the nest is formed with a hole for pouring molten metal and a hole for a pressure punch, and the other part of the nested mold is The mold for fiber-reinforced metal casting according to claim 1, characterized in that the lower mold has an opening whose upper part is closed by the upper nesting mold and a hole for inserting a knockout pin. (3) At least A step of arranging a predetermined amount of a predetermined fiber bundle in a nested mold consisting of two split molds and heating it for a predetermined time, a step of assembling the nested mold into an outer mold divided into at least two parts, and a step of placing a predetermined molten metal in the nested mold. 1. A method for casting a fiber-reinforced metal casting, comprising the steps of pouring the poured metal, solidifying the poured metal under pressure, and taking out the solidified product.