JPS6340640A - Core for pressure casting and its production - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a core used for pressure J-casting such as a die-casting method and its %j base method.

(Prior art) Generally, when casting a casting having a hollow part by a pressure casting method such as a die casting method, the molten metal is inserted into the shell core by the hot water pressure, so the inner wall of the hollow part of the casting after casting is There is a risk that some of the core sand that makes up the core may get caught. If a casting with part of this core sand entrapped is used as a product, the core sand will separate from the inner wall of the hollow part during use and mix with liquids such as oil and water flowing inside the hollow part. Therefore, in order to prevent such a situation from occurring, for example, as disclosed in Japanese Patent Publication No. 60-15418, a slurry containing a mixture of powdered refractories and colloidal silica is applied to the surface of the shell core. Apply the liquid [dry to form the first coating layer, then
By applying a mica aqueous solution on the first coating layer to form a second coating layer, the first coating layer smoothes the surface of the shell core and equalizes the hot water pressure acting on the core surface. It is known that the second coating layer is used to prevent molten metal from penetrating into the shell core.

(Problems to be solved by the invention) However, above 3. The outermost surface layer (second coating) of the shell core formed as in FS has poor dispersibility of mica particles in the sea urchin aqueous solution, so the mica particles are uniformly distributed in the figure. However, due to the liquid dripping phenomenon, since the particles are large, the amount of d3 in the above layer is mm.
becomes uneven.

If the distribution of mica particles in the outermost surface layer (second coating layer) becomes uneven in this way, the degree of shrinkage due to heating during layer formation, that is, during drying, will vary throughout the layer, causing nucleation. There is a risk that cracks may occur in the layer, and shell cores with cracks should not be used for casting.
If it is old, there will be a problem that the molten metal will enter the core body from the cranking point.

In addition, when casting is performed using a core as described above, it is necessary to fire the core once after casting and remove it from the casting by applying external force such as vibration or water jet. There is a risk that the coating layer (sea urchin layer) may peel off due to the action of rotation and remain attached to the inner wall of the hollow part of the casting, making it impossible to finish the casting surface well.

The present invention has been made to solve this problem, and its purpose is to specify the material constituting the outermost surface layer of the core, so that it can be used in the outermost surface layer of the core as in the conventional example. The purpose of this invention is to reliably prevent the penetration of molten metal into the core body, which is opened during casting, without controlling the condition of the components, and to make it possible to cast a casting with a good casting surface.

In summary, the present invention provides a manufacturing method for efficiently manufacturing the above-mentioned core.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention forms a conductive layer made of conductive particles on the outer surface of the core body. Generally, a metal plating layer is formed on the conductive layer.

Roughly speaking, the present invention provides a manufacturing method for manufacturing the above-mentioned core, in which a solution containing conductive particles is first applied to the outer surface of the core body, and then a conductive layer is formed by passing through a drying process. do. Next, a metal plating is applied on the conductive layer to form a metal layer.

(Function) Based on the above configuration 1, in the present invention, a metal plating layer is formed on the outer surface of the core body via a conductive layer, so that the molten metal poured into the mold during casting It is completely separated from the core body by the metal plating layer, thereby reliably preventing the molten metal from penetrating into the core body. In addition, the core body is fired after casting and is then collapsed and removed by the action of external force such as vibration, or the metal plating layer is integrally attached to the inner wall of the casting hollow formed by removing the core body. As a result, good quality castings are cast.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIGS. 1 and 2 show a pressure casting medium according to an embodiment of the present invention, which is a two-part type consisting of a first core 1 and a second core 2, which is applied when casting a rotor for a rotary engine of an automobile. A core 3 is shown, and the dual use 1 and 2 of the core 3 are shown.
Since the cores 1 and 2 have the same structure except for their different shapes, the first core 1 will be explained below, and the second core will be explained below.
Regarding the core 2, the same constituent parts are given the same reference numerals and detailed explanation thereof will be omitted.

4 is the core body of the first core 1;
For example, about 200 mesh of sand is mixed with a binder and resin coated with phenolic resin.
It is molded by filling it into a core mold (not shown) heated and maintained at 50'C.

Further, a coating mold +/I layer 5 is formed on the outer surface of the core body 4, and the coating material layer 5 is made of a slurry 1 no solution containing powdered refractories, metal oxides, etc. After coating the outer surface of the child body 4, the drying temperature is 150°C for 20 minutes, for example.
For example, 200
The layer thickness is μ7n.

This coating material layer 5 is intended to improve the smoothness of the outer surface of the core water body 4 and the adhesion of a tetraelectric layer 6, which will be described later. As for the composition of the slurry liquid, it!
For example, 3i0257.5 Heavy Research Institute%, Af' 203 2.
0'fil'4%, Fe203 4.0 Futsubaki? Mo, c
aOo, 5a=%, MCI○ 25゜0 elements%, 2
j”Oz 0.5% by weight, C6.0 mold open%, etc.
4.5% Juken diluted to 50% with ethyl alcohol is used.

Further, a conductive layer 6 is provided on the coating material layer 5 of the core body 4.
is formed, and the conductive layer 6 has an average particle size of, for example, 0.5 to
″!Apply R liquid (containing Oμ7rl graphite particles)Tfi
For example, by going through a drying process,
It is formed to a layer thickness of μm. The reason why the particle size of the graphite particles constituting the conductive layer 6 is set within the above range is as follows.
If it's less than 0.5μm, it's time! On the other hand, 10 μm
If it exceeds this, the layer becomes denser or becomes difficult. Also,
The reason why the layer thickness of the graphite particles was set in the above range is that it is difficult to form a uniform conductive layer with a side of less than 5 μm; This is because a proportional effect cannot be expected.The solution containing the conductive particles is, for example, a solution containing 50 graphite particles in a heavy-duty tank and 5 Q insects fi% of water.

Further, on the conductive layer 6 of the core body/1, a metal plating layer 7 of nickel, chromium, etc., for example, layers 195 to 195, is formed by metal plating.

The reason for setting the layer 1 of the metal plating layer 7 to the above range is that if the thickness is less than 5 μm, it is difficult to form a uniform plating layer and there is a risk of cracks occurring due to the hot water pressure during casting.
This is because if it exceeds the sides, it cannot be expected that the molten metal will be prevented from penetrating in proportion to the increase in the layer thickness of the core body 4.

The drying conditions required to form the coating material layer 5 and the conductive layer 6 are, for example, drying temperature 1b O'C.
Although the drying time is 20 minutes, the drying temperature and time are not limited to this, as long as the volatile components in the solutions constituting each of the layers 5 and 6 can be evaporated.

Next, a method of manufacturing the pressure casting core 3 according to the above embodiment will be explained.

First, resin coated sand is filled into a mold and fired to form each core water body 4 of the first and second cores 1.2. Thereafter, the operation of dipping each core body 4 in the slurry liquid mixed as described above is repeated an appropriate number of times to apply the slurry liquid to the outer surface of the core body 4, and then,
Each core body 4 that has been coated with the slurry liquid is transported to a drying process and dried under conditions such as a drying temperature of 150° C. and a drying time of 20 minutes to form a thick layer on the outer surface of the core body 4. A mold coating material layer 5 of 200 μm is formed.

Next, on this coating material layer 5, a solution containing graphite particles blended as shown above is applied by spray coating.
or by immersing the core body 4 on which the mold coating layer 5 has been formed in the above solution and drying it under the same drying conditions as when forming the mold coating material layer 5, A conductive layer 6 made of graphite with a spacing of 30 μTn is formed.

Roughly, electroplating is performed on this conductive layer 6 to form a metal plating layer 7 made of nickel and having a thickness of 5 μm.

The first and second cores 1 and 2 in which the mold coating layer 5, the conductive layer 6, and the metal plating layer 7 are sequentially laminated on the outer surface of the core body in this way are as shown in FIG. A core 3 is formed by interposing the reinforcing material 8 so that the first core 1 is on top and the second core 2 is on the bottom. Plunge I
- By the operation of ``!2, for example, molten aluminum alloy △
A rotor 13 of a mortar-tally engine as shown in FIG. 4 is cast by injecting it into a mold 11 at a hot water pressure of 350 KFJ/cri.

At this time, the outermost surfaces of the first J5 and the second cores 1, 2 are covered with the metal plating layers 7, 7 without any gaps, and the molten metal A and the core bodies 4, 4 are covered with the metal plating layers 7, 7. Since they are completely separated, it is possible to reliably prevent the molten metal A from entering the core bodies 4, 4.

After casting the rotor 13, the first and second cores '1 and 2 constituting the hollow part are once t1a o'
After c-c firing to eliminate the phenolic resin as a binder, the first and second cores 1 and 2 are collapsed and removed from the hollow part of the rotor 13 by applying an external force such as vibration or vibration. Obtain Roku 13 as a material.

At this time, each of the core body 4, coating material layer 5, and conductive layer 6 constituting each of the first and second cores 1 and 2 is removed from the hollow part of the rotor 13, but the container 1 and The metal plating layer 7 constituting the outermost surface layer of the second cores 1 and 2 remains integrally fixed to the inner wall of the hollow part of the rotor 13, thereby producing a rotor 13 with a good casting surface.
can be notified.

In this embodiment, the mold coating material layer 5 is formed on the outer surface of the core water body 4, and the conductive layer 6 of graphite particles is formed on the mold coating material layer 5.
, and then roughly coat the conductive layer 6 with a nickel metal f.
Since the fJ metal layer 7 is formed, it is possible to reliably prevent the molten metal Δ from penetrating into the core body 4 during casting, and it is also possible to cast a rotor 13 with a good casting surface.

Further, the above manufacturing method efficiently manufactures a core having the above effects of preventing molten metal A from being inserted into the core water body 4 and improving the casting surface of the rotor 13 without using any special means. I need something that I can do.

Incidentally, in the above embodiment, graphite particles were used as the conductive layer 6, but the present invention is not limited to this, and any material having conductivity can be used.

It goes without saying that the electrodeposited metal used for the metal plating layer 7 is not limited to nickel. For example, when a cast product is used in an environment where it is easily corroded, a corrosion-resistant material may be used depending on the purpose of use. It can be selected as appropriate, and the means for forming the metal plating layer 7 is not limited to electroplating, but may also be electroless plating.

Further, in the above embodiment, the core body 4. Although the case where /1 is made of resin-coated sand is shown, it is not limited to this, but it is also possible to use a composition of, for example, cement 1 - white hard sand such as sand - 1A) 5 blue, etc. If the surface smoothness is relatively good, such as N, the coating material layer 5 formed on the outer surface of the core body 4 may be omitted, and the conductive layer 6 may be formed directly on the core body. It is possible to use it. Further, the core 3 does not need to be limited to the split type.

Generally speaking, the above embodiment shows the case of casting the rotor 13 of a rotary engine of an automobile, but the present invention is not limited to this, and can also be applied to the case of casting cast products other than cylinder blocks, cylinder heads, and other moving vehicle parts. It goes without saying that it is possible.

(Effects of the Invention) As explained above, according to the present invention, since the metal plating layer is formed on the outer surface of the core body via the conductive layer, the molten metal injected into the mold during casting can The core body is completely separated by the metal plating layer, thereby reliably preventing the molten metal from penetrating into the core body. Also, after casting, the core is fired to remove it from the casting,
After that, the core collapses due to the application of an external force such as vibration, but the metal plating layer remains integrally fixed to the inner wall of the hollow part of the casting formed by removing the core. 1 (good tJ3. Can cast hooks.

Further, according to the manufacturing method of the present invention, a core having the above-mentioned effects of preventing molten metal from being inserted into the core body and improving the casting surface of the casting can be efficiently manufactured without using any special means. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of a pressure casting core according to an embodiment of the present invention of a two-part type applied to the casting of rotors for automobile rotary engines; Fig. 2 is an enlarged longitudinal sectional front view of l'Fil; FIG. 3 is a longitudinal sectional front view showing the cast state of the rotor, and FIG. 4 is a perspective view of the cast rotor. 4... Core body, 6... Conductive layer, 7... Metal plating layer. Figure 3 Figure 1 Figure 4

Claims (2)

[Claims] (1) A core body, a conductive layer made of conductive particles formed on the outer surface of the core body, and a metal plating layer formed on the conductive layer. Core for pressure casting. (2) A conductive layer is formed by applying a solution containing conductive particles to the outer surface of the core body, followed by a drying process, and then metal plating is applied on the conductive layer. A method for producing a core for pressure casting, characterized by forming a plating layer.