JPS59191542A - Investment casting method - Google Patents

Abstract

PURPOSE:To obtain a casting having no casting defects such as shrinkage cavity, etc. without using a riser by adhering a solid cooling medium to the thick walled part of a pattern corresponding to the thick walled part of the casting and charging a molten metal therein in this state. CONSTITUTION:A solid cooling medium of an iron chiller 10, etc. is attached by using an adhesive agent 9, etc. to the thick walled part 8 in the product part 1 of a pattern. A separately manufactured casting plan part 2 is attached thereto by an adhesive agent to manufacture the pattern. Such pattern is embedded in mold sand 6 which is a heat resistant granular material in a molding flask 5 and finally a pouring bush 7 is provided. A melt of an Al alloy, etc. is cast into the mold through the bush 7, and the mold is knocked out upon solidification, then the casting is subjected to a post treatment such as gate breaking. The casting having no defects such as shrinkage cavity, etc. in the thick walled part is obtd. by said investment casting method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a filling casting method using a fugitive pattern, and particularly to a filling casting method suitable for producing a casting having a thick wall portion.

The filling casting method involves embedding a fugitive model (hereinafter simply referred to as the model) such as expanded polystyrene in a heat-resistant granular material such as molding sand, and then pouring the molten metal into it without removing the model from the heat-resistant granular material. It is publicly known.

Generally, molten metal contracts during solidification and during the cooling process after solidification. For this reason, when a casting has a thick part, a casting defect called a shrinkage cavity occurs because the solidification rate of the thick part after casting is slow. This sentence is the same for the filling and casting method.

Conventionally, countermeasures against shrinkage cavities in the filling casting method have been carried out using a riser. This prior art will be explained based on FIG.

In FIG. 1, 1 is a product part of the model, and a feeder part 3 is integrally attached to this product part 1 together with a casting plan part 2 such as a runner by appropriate means such as adhesive, forming a model 4. ing. The model 4 is embedded in heat-resistant granules 6 in a flask 5, and a weir 7 is attached to the upper part of the heat-resistant granules 6.

The molten metal poured from the hanging weir 7 replaces the model 4 by burning the model 4, but solidification of the molten metal is delayed in the thick part 8 of the product part 1 compared to other parts. Therefore, at the end, the molten metal solidifies and contracts and begins to form voids, but the molten metal is replenished from the feeder section 3 to prevent the generation of shrinkage cavities.

However, in this conventional method, it is necessary to separately manufacture a feeder part when making the model, and the product yield is poor because the molten metal is introduced into this feeder part.In addition, the feeder part needs to be cut after casting, etc. There were problems in terms of man-hours and costs.

The present invention was made in order to solve the problems of the prior art described above, and provides a filling casting method that is easy and inexpensive with good workability and produces castings without casting defects such as shrinkage cavities without using a riser. The purpose is to provide.

According to the filling casting method according to the present invention, this object is achieved by attaching a solid cooling medium to the thick part of the model corresponding to the thick part of the casting, and pouring the metal in this state.

In the present invention, the solid cooling medium is generally referred to as a cooling metal, and iron pieces, copper pieces, etc. can be used. The shape, material and size of the solid cooling medium should be appropriately determined depending on the shape and size of the thick walled part to which it is attached, the material of the molten metal to be cast, etc.

The following methods are available for attaching the solid cooling medium to the model.

The first method is to use adhesive to fix the solid cooling medium to the model, as shown in FIG.

The second method, as shown in FIG. 3, is a method in which a model installation jig is used to hold the thick part of the model with a solid cooling medium interposed therebetween.

The third method is the same as the second method in that it uses a model setting jig, but differs in that the model setting jig is fixed to the flask as shown in FIG.

The second method uses the commonly used model installation jig as is, and the model installation method is buried in the mold together with the rear model, so it is much easier to work with than the first method. . Moreover, the model installation jig can be used repeatedly. Furthermore, since it has good stability, it has the advantage that molding work can be carried out efficiently.

The third method has all the advantages of the second method, and since the model installation jig is fixed to the flask, the stability of the mold is guaranteed and the molding work is extremely easy. .

As described above, according to the present invention, since the solid cooling medium is attached to the thick wall part of the model, a sound casting without casting defects such as shrinkage cavities can be obtained without providing a feeder part as in the conventional case. In addition, the workability is improved compared to the conventional method, and the casting cost is reduced.

In addition, the method for attaching the solid cooling medium to the model is as per the above-mentioned No. 2.
When a model setting jig is used as in the above method and the third method, work efficiency is significantly improved.

Next, embodiments of the present invention will be described with reference to the drawings.

Example 1 A first example of the present invention will be described with reference to FIGS. 2 and 5. As shown in FIG. 2, the thick part 8 of the product part 1 of the model
An iron chiller 10, which is a solid cooling medium, is attached using adhesive 9.
I installed it. Next, the separately manufactured casting plan part 2 is attached with adhesive to create a model 4, and this model 4 is buried in molding sand 6, which is a heat-resistant granular material, in the casting flask 5, and finally a hanging weir 7 is installed. Ta.

Next, 750° C. molten aluminum alloy was poured from the weir 7. After the molten metal solidified, it was demolded and subjected to post-processing such as weir folding to obtain the desired casting.

When the thick part of this casting was cut and the inside was observed, no casting defects such as sinkholes were observed.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG.

A model installation jig 11 was installed in the flask 5 in advance and fixed to the flask 5. This model installation jig 11 has a cooling metal 10 at its tip.
A plurality of bolts 12 are attached. A separately produced model 4 was placed in a casting flask 5, and the thick part 8 was clamped from the left and right sides at a cooling point 10, thereby fixing the model 4 to a model setting jig 11. Next, molding sand 6 was loaded into the flask 5 to obtain the state shown in FIG.

Thereafter, the same operations as in the first example were performed to obtain the desired casting. Similar to the first example, this casting was sound, with no casting defects such as shrinkage cavities occurring even in the thick wall portion.

According to the second embodiment, since the chiller is attached to the model installation jig in advance, there is no need to separately attach the chiller to the model, and the fixing of the model and attachment of the chiller are easy. Since they can be done simultaneously, the work efficiency has been significantly improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the prior art, Fig. 2 is a sectional view showing a cold metal model used in the first embodiment of the present invention, and Fig. 3 is a sectional view showing the use of the model installation jig according to the present invention. FIG. 4 is a sectional view showing a second embodiment of the present invention, and FIG. 5 is a sectional view showing a first embodiment of the present invention. 1-・-111 Product Department 2--------Casting Plan Department 3--・-Leader Section 4--・-Model 5--・Casting Frame 6--・-Molding Sand (Heat-resistant Granular Materials) ) 7 ---- One weir 8 - - m - Thick part 9 ---- One adhesive 10 ---- One cooling metal (solid cooling medium) 11 -------
1. Model installation jig 12 ------- Bolt Applicant: Toyota - No Taku 1 Match Company Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] (1) A filling casting method in which a fugitive model is buried in heat-resistant granules in a casting flask, and molten metal is poured into the casting without removing the fugitive model, wherein the fugitive model is A filling casting method characterized by a solid cooling medium being attached to the thick part of the sex model. (2. The filling casting method according to claim 1, characterized in that the solid cooling medium is held by a model installation jig. (3) The method according to claim 1, wherein the solid cooling medium is held by a model installation jig. A filling casting method characterized by the installation jig being fixed to the casting flask.