JPH04135038A - Casting method using consumable pattern - Google Patents

Abstract

PURPOSE:To prevent defect in a product and to manufacture a good quality casting by forming a consumable pattern in such a manner that a non-product molding part is formed at the part consumed last and most far away from a sprue part and facing material is applied on the outer face except the non- product molding part. CONSTITUTION:The consumable pattern 4 composed of runner molding part 1, product molding part 2 and the non-product molding part 3 is manufactured. The facing agent 5 is applied on the surface of the runner molding part 1 and the product molding part 2. On the non-product molding part 3 and the upper face of the sprue part 1a, the facing agent is not applied. The consumable pattern 4 is set in a flask 6 and packed with molding sand 8, and while sucking the air in a sand mold 8 from a sucking hole 9, molten metal is poured from the sprue part 1a. The molten metal is allowed to flow while burning the consumable pattern 4 and finally, flowing into the non-product molding part 3. As the burnt waste, etc., are collected into the non-product molding part 3 after removing the mold, by rejecting these, the product molding part 2 with the good quality is obtd. without any defect.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a casting method using a fugitive pattern.

[Prior art]

In general, full mold casting is widely used as a casting method when producing relatively large articles in small quantities, as it is inexpensive to produce a model and is easy to produce a mold.

Normally, in the above-mentioned full mold casting method, a fugitive model is produced by molding a foamed polystyrene base material, a coating agent is applied to the surface of this fugitive model to form a coating mold, and then the fugitive model is is set in the formwork and filled with sand, the formwork is vibrated with a vibrating device to tighten the sand, and then the molten metal is poured into the fugitive model while sucking the air inside the formwork. The combustion gas of the fugitive model is discharged to the outside of the cavity and the fugitive model is replaced with molten metal to produce a cast product having the same shape as the fugitive model. (see official bulletin).

[Problem to be solved by the invention]

As mentioned above, even if the molten metal is poured into the fugitive model while sucking the air inside the formwork, the air permeability of the coating formed on the surface of the fugitive model is not very good, so the fugitive model The combustion gas cannot be discharged out of the cavity quickly, and the residual combustion gas may cause product defects on the surface of the cast product. Further, when the fugitive model is burned, a small amount of burnt residue is generated, and this burnt residue remains in the product, resulting in a reduction in quality.

An object of the present invention is to provide a casting method using a fugitive model that can prevent deterioration in quality due to residual combustion gas and burnt scum of the fugitive model.

[Means for Solving the Problems] The casting method using the fugitive model according to the present invention has a non-product molded part in the last part of the fugitive model that is farthest from the sprue and disappears by burning with molten metal. A mold coating agent is applied to the outer surface of the fugitive model other than the non-product-molded part, the fugitive model is set in the mold and molten metal is poured, and then the cast product is removed from the mold. This removes the non-product parts molded by the product molding section.

[Effect]

In the casting method using the fugitive model according to the present invention,
A non-product molding part is formed in the part of the fugitive model that is farthest from the sprue and last to disappear, and this fugitive model is set in the mold.
Since the melt is poured by pouring the melt, the burnt residue of the fugitive model is pushed by the molten metal and moves toward the non-product molding section, where it is collected in the cavity formed by the non-product molding section. Since the non-product part formed by the non-product molding section is removed after demolding the cast product, most of the burnt residue is removed together with the non-product part, and a high-quality product containing no burnt residue can be manufactured.

On the other hand, a coating agent is applied to the outer surface of the fugitive model other than the non-product-molded parts, forming a coating with poor air permeability. A portion remains in the cavity formed by the product molding section, is pushed by the molten metal, and is collected together with the burnt residue in the cavity formed by the non-product molding section. Then, it is efficiently discharged out of the cavity from the wall surface of the cavity formed by the non-product molded part whose outer surface is not coated with the mold coating agent. For this reason, there is almost no combustion gas remaining in the demolded cast product, and even if some residual combustion gas remains in the cavity formed in the non-product molding area where the residual combustion gas collects, the non-product molding Since the non-product parts formed in the molding section are removed after the casting is demolded, product defects due to residual combustion gas can be reliably prevented and high-quality products can be manufactured.

〔Effect of the invention〕

According to the casting method using the fugitive model according to the present invention, as detailed in the [Operation] section above, product defects caused by burning residue and combustion gas from the fugitive model remaining in the product can be prevented. It is possible to produce high-quality cast products.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

First, a foamed polystyrene base material is molded into a predetermined shape,
As shown in FIG.
A fugitive model 4 consisting of a pair of non-product molding parts 3 is manufactured. The non-product molding part 3 is provided in a protruding manner at the upper end of the product molding part 2, and is provided at the part furthest from the sprue 1a formed at the upper end of the channel molding part 1 and disappearing last.

Next, a coating agent obtained by kneading the aggregate with a binder and a solvent is applied to the surfaces of the channel forming section 1 and the product forming section 2, and then dried for a predetermined period of time, as shown in Fig. 2. A coating mold 5 is formed on the surface of the fugitive model 4 as shown in FIG. Note that no mold coating agent is applied to the upper surfaces of the non-product molding section 3 and the sprue section 1a.

Next, the fugitive model 4 with the coating mold 5 formed on the surface is
As shown in the figure, the sand mold 8 is manufactured by setting it in a mold 6, filling the mold 6 with sand, and then vibrating the mold 6 using the vibration generator 7 to tighten the sand. In the sand mold 8 thus manufactured, a runner molding cavity IA is formed at a position corresponding to the runner molding section 1, a product molding cavity 2A is formed at a position corresponding to the product molding section 2, and a non-product molding section is formed. A non-product molding cavity 3A is formed at a position corresponding to 3.

Next, as shown in FIG. 4, while the air inside the sand mold 8 is sucked through the suction port 9 to reduce the pressure inside the sand mold 8, a molten metal (for example, molten aluminum alloy) 10 is poured from the sprue portion 1a.

At this time, the molten metal 10 burns the fugitive model 4 with its heat and flows into the two product molding cavities via the hot water path molding cavity IA, and finally flows into the non-product molding cavity 3A and flows into the cavities IA, 2A, and 3A. filled inside.

On the other hand, the burnt residue 11 of the burnt dissipative model 4A is
As shown in FIGS. 6 and 7, the leading end of the inflowing molten metal 10 is swept toward the non-product molding section side 3, collected in the non-product molding cavity 3A, and the fugitive model 4 is combusted. The combustion gas 12 generated during this process is discharged into the sand mold 8 under reduced pressure through the coating mold 5, but since the coating mold 5 does not have very good air permeability, a part of it is discharged into the product molding cavity 2A. According to the flow of the molten metal 10, it moves to the non-product molding section 3 side and is collected in the non-product molding cavity 3A, where the coating mold 5 is not formed.
The sand is directly and smoothly discharged from the inner wall of A into the sand mold 8.

Next, the molten metal 10 is left to solidify, and then the cast product 1
3 is removed from the mold, and as shown in FIG. 5, the runner IB and the non-product part 3B, which were cast in the runner molding cavity IA and the non-product molding cavity 3A, respectively, are removed, and the mold is cast in the product molding cavity 2A. A product 2B is obtained.

In this way, the burnt residue 11 of the fugitive model 4 generated during pouring can be collected in the non-product molding cavity 3A, and the non-product part 3B molded in the non-product molding cavity 3A is removed after demolding. As a result, a high-quality product 2B with almost no residual burnt residue 11 can be obtained.

On the other hand, since the coating mold 5 is not formed in the non-product molding part 3, the fugitive model 4 remaining in the product molding cavity 2A
The combustion gas 12 is smoothly discharged, and even if some combustion gas 12 remains in the non-product molding cavity 3A, the non-product part 3 is cast in the non-product molding cavity 3A.
Since B is removed after demolding, product defects due to residual combustion gas 12 do not occur, and a high-quality product 2B can be manufactured.

In this embodiment, two non-product molded parts 3 are provided at the part that is farthest from the sprue 1a and disappears last, but one or more than three non-product molded parts 3 may be provided. It may be formed into a columnar or rectangular shape.

In addition, when the upper part of the product molding part 2 is divided into a plurality of parts, the non-product molding part 3 may be formed in a projecting shape at the upper end of each divided body.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a fugitive model, FIG. 2 is a view corresponding to FIG. 1 in a state where a coating mold is formed, and FIG. 3 is a sand mold and a fugitive model. Longitudinal cross-sectional view of
Figure 4 is a vertical cross-sectional view of the sand mold after pouring the metal, Figure 5 is a vertical cross-sectional view of the cast product, Figure 6 is a vertical cross-sectional view of the main part near the product molding part during pouring, and Figure 7 is a vertical cross-section of the sand mold after pouring the metal. FIG. 3 is a vertical cross-sectional view of the non-product molding section 3 side at the time. 2. Product molding department, 3. Non-product molding department, 4. Erasable model, 5. Paint mold, 8. Sand mold, 3B. Non-product molding department. Figure 6 Figure 7 Patent applicant Mazda Motor Corporation

Claims (1)

[Claims] (1) Form a non-product molded part in the last part of the fugitive model that is farthest from the sprue and disappear by burning with molten metal, and paint the outer surface of the fugitive model other than the non-product molded part. A fugitive method characterized by applying a molding agent, setting the fugitive model in a mold and pouring the melt, and then removing the non-product part formed by the non-product molding part after demolding the cast product. A casting method that uses a model.