JPS59137153A - Molding method of shell mold for flanged article - Google Patents

Abstract

PURPOSE:To reinforce locally the required part of a shell mold by forming a shell rib extending in the direction where the columnar pattern part of a pattern plate and the step part of the split surface having a rugged shape are connected. CONSTITUTION:A pattern plate P and a dummy plate 14 are heated, and molding is peformed by practicing a dump method. Not only the shell sand in the part conforming to the plate P but also the shell sand in the part conforming to the plate 14 are heated and solidified and therefore a shell rib 17 extending in the direction where a columnar pattern 8a and a step part d3 are connected is formed in a formed shell mold Sa along the plate 14. The construction wherein the solidified layer S1 of the shell sand of the mold Sa is reinforced is provided to said mold by such rib 17. Even if backup force upon the layer S1 is insufficent in the stage of casting vertically the mold Sa, the deformation of the layer S1 is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shell molding method used when vertically casting an article having seven flange on one end side of a columnar part using back-up material.

Incidentally, in the present invention, the term "column-shaped part" includes a part whose inside is substantially hollow.

As is well known, one of these shell-shaped methods is
There is a dump method in which a shell type S& is formed by the steps shown in FIGS. 1(a) to (e). In this method, a pattern plate P having a desired shape is attached to a dump box 1 as shown in FIG. By dropping shell sand 6 such as resin sand on the plate P and covering it, shell sand 6 around the pattern plate P is removed.
solidify.

After that, as shown in FIG. 2(Q), the dump box 1 is inverted, the unconsolidated shell sand 6 is separated from the shell shape Sa formed by the consolidation, and then the shell sand is heated to form a shell shape. The strength of Sa is increased, and finally, as shown in the same figure (θ), the shell 3JI Sa is formed into a ta shape from the pattern plate P. In this case, if necessary, release tfiI
In this case, the dump box 1 is turned over again as shown in FIG. 2(d).

A method of vertical casting using the shell mold Sa formed by such a dumping method is shown in FIG. A pair of half-shell shell molds Sa and Sb, which were molded by
Load the back-up material 5 such as green mold sand and make the shell mold Sa.
, sb is backed up, and in this state, the upper sprue 6
A method of pouring the metal into the shell-shaped Sa or Sb is more commonly used.

Tokorochi is a half-split type used when casting an article 7 having seven flange 9 at one end of a columnar part 8, such as the exhaust manifold of an automobile engine shown in Fig. 6, by the above-described vertical casting. When molding the shell type Sa, a pattern plate P shown in FIGS. 4(a) and 4(b) is used. This pattern plate P has a convex split surface d1 at a position corresponding to the longitudinal middle part of the columnar part 8 of the article 7, and a concave split surface d1 at a position corresponding to the joint surface of the 7 flange 9 of the article 7. Each has a surface d2, the convex split surface d1 and the concave split surface d are continuous by the step part d1, and the concave printed surface d2,
It has a columnar pattern part 8a and a flange pattern part 91L. In such a pattern plate P, since a flange portion 9a protrudes from the tip end side of the columnar pattern portion 8a, the stepped portion d3 is connected to the columnar pattern portion 8a.
The stepped portion d3 cannot be provided closer than a certain level to the
The distance between the columnar pattern portion 8& and the columnar pattern portion 8& is relatively large. Therefore, when this pattern plate P is used to mold a shell type Sa by the dumping method explained in FIG. 1, the columnar pattern part of the pattern plate 8a and step part d
Deep depressions IQa, 10b are formed between the shell sand solidified layers formed around each of the shell sand layers IQa and 10b.

When vertically casting the article 7 described in FIG. 6 using such a shell type SIL, as shown in FIG. Align the split surfaces and place in the casting box 4 (see Figure 2),
Next, a back-up material 5 (see FIG. 2) is loaded around the shell molds Sa and Sb.

At this time, the hollow portion 10b located above the shell sand consolidated layer S around the columnar pattern portion 8a (see FIG. 4(b))
Although the back-up material 5 is sufficiently filled with the back-up material 5, the recess 10a located below the shell sand compacted layer S1 is not sufficiently filled with the back-up material 5, and the shell sand compact layer S1 is Backup power is insufficient. on the other hand,
The shell sand consolidated layer El.

is formed by covering the columnar pattern portion 8IL shown in FIG. 4(b) with shell sand 6 (see FIG. 1(b)) from above, so the shell sand 6 (see FIG. 1(b)) is formed near the tip of the columnar pattern portion 8a. Since the sand compaction layer S inevitably becomes thinner, a decrease in the strength of the shell sand compaction layer s1 is unavoidable. Due to this lack of backup power and reduced strength, the fifth
During the vertical casting shown in the figure, the shell sand solidified layer S is deformed downward as shown by the two-dot chain line, causing bulges and sometimes cracks in the cast product. In addition, the fifth
(Here, it is a 20I/'i core.

By the way, as a measure to locally increase the strength of the shell-shaped shell sand consolidation layer, as shown in Fig. 6,
An auxiliary heating bottle 12 is provided upright on the split surface d5 of the pattern plate P having the protruding pattern part 11 in close proximity to the corner 11a of the pattern part 11, and both the pattern plate P and the bottle 12 Heat the
There is a method that implements the dumping method shown in FIG. The shell mold 5old formed by this method, the side surface of the pattern part 11, and the part of the sand 5 corresponding to 'y-+11a are heated by both the pattern plate P and the bottle 12, and the shell sand condensation layer in this part is heated by both the pattern plate P and the bottle 12. The wall thickness of the shell is equal to or thicker than that of the shell sand consolidation layer in other parts, resulting in greater strength.

Therefore, in order to reinforce the shell sand consolidation layer S1 described in FIG. 5 and prevent deformation during vertical casting, it is possible to apply the method described in FIG. 6.

However, in the method explained in FIG. 6, it is only possible to locally thicken the shell sand solid layer and increase its strength by arranging the bottle 12 close to the side surface of the pattern section 11. It is. However, in the pattern plate P explained in FIGS. 4(a) and 4(b), since the seven flange pattern portions 9& protrude from the lower end side of the columnar pattern portions 8IL, the flange pattern portions 9& become an obstacle. Therefore, as a measure to prevent deformation of the shell sand solidified layer S1 in FIG. 5, the method explained in FIG. The problem is that it cannot be used.

The present invention provides a shell-type tooth pattern method that can be particularly advantageously adopted in cases where the above-mentioned difficulties exist. dummy plate,
It is used for auxiliary heating of shell sand, and by forming shell ribs that extend in the direction connecting the columnar pattern part of the pattern plate and the step part of the uneven split surface, necessary parts of the shell mold are locally reinforced. It is intended to.

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

As shown in FIG. 7<tt), (b), a holding bottle 16 is erected with a gap on the side of the flange pattern portion 9a of the concave split surface d2 of the pattern plate P. A metal dummy plate 14 is locked to the end of this holding pin 16.

As shown in FIG. 8, the holding pin 13 has a cross-shaped slit 15 formed at its end, into which the dummy plate 14 is inserted. by this,
The dummy plate 14 is elastically held by the protrusions 16 that are divided by the slits 15, and is firmly fixed without wobbling.

The above-mentioned dummy play) 141d needs to be arranged in the concave space of the pattern plate P so as to face the columnar pattern part 8IL with a gap therebetween.

This is because if the dummy plate 14 is placed in contact with the columnar pattern portion 8a, the end surface of the dummy plate 14 will be exposed to the cavity of the shell type Sa, which will be described later.
This is because casting cannot be performed smoothly.

After this, pattern plate P and dummy plate 14
is heated and molded by carrying out the dumping method explained in FIG. In this way, not only the shell sand along the pattern play) P but also the shell sand along the dummy plate 14 is heated and solidified, so that the molded shell mold sa is tt), as clearly shown in (b), a shell rib 17 is formed along the dummy plate 14 and extends in the direction connecting the columnar pattern SSa and the stepped portion d3, and this shell rib 17 allows
The shell type Sa has a structure in which the above-mentioned shell sand consolidation layer S1 is reinforced. Therefore, when vertically casting the shell type Sa in the state shown in FIG. 9, even if the above-mentioned backup force against the shell sand consolidation layer S is insufficient, the shell sand consolidation layer S will not be deformed. There isn't. Note that when the dummy plate 14 is released from the shell type Sal pattern plate P, the holding pin 16 (7) 7. It is pulled out from the IJ foot 5 and remains buried in the above-mentioned shell rib 17.

FIGS. 10(a) and 10(b) show the case where a shell type Sa is molded according to a modification of the above embodiment. That is, the degassing bottle shown in FIG. 11 is used as the holding pin 16, and the dummy plate 14 is locked in the slit 15 at the end of the bottle, and the dummy plate 14 is attached to the dummy plate 14 as shown in FIG. 10<a>. , (b) As shown in h, the notch groove 18 formed in the stepped portion d3 of the pattern plate) P is also engaged, and in this state, the dumping method shown in FIG. /"11 s a. In this case, there is an advantage that the dummy plate 14 is firmly held by the holding bottle 16 and the notched groove 18. As shown in FIG. 12, this method It is necessary to form a groove 19 in the half-split shell mold sb, which is the counterpart of the shell mold sa molded in , for accommodating the end of the dummy plate 14 buried in the shell rib 17. Other configurations and effects are shown in Figure 7(a).
, (b) and as explained in FIG.

In addition, in the drawings, for convenience of explanation, the same reference numerals are given to the same or corresponding parts, and the explanation is omitted.

As detailed above, according to the present invention, within the concave space of the pattern plate, the columnar pattern portion and the stepped portion of the pattern plate are arranged along the dummy plate that faces the columnar pattern portion with a gap therebetween. Since shell ribs extending in the connecting direction are formed, a locally reinforced shell shape is left behind by the shell ribs. Therefore, when vertically casting an article having seven flange at one end of a two-column part, even if the back-up force against the shell mold is locally insufficient, the product has the strength to compensate for the lack of back-up force against the shell mold. This makes it possible to form a shell mold, and prevents deformation and cracks in the cast product due to deformation of the shell mold.

[Brief explanation of the drawing]

Figures 1 (a) to (θ) are explanatory diagrams showing an example of a general shell molding method, Figure 2 is an explanatory diagram showing a vertical casting method, and Figure 6 is an example of a flanged article. FIG. 4(&) is a perspective view of the exhaust manifold in the engine shown in FIG.
Figure (b) is a cross-sectional view taken along line G in figure (a),
Figure 5 is an explanatory diagram of vertical casting using a shell mold formed by the conventional method, Figure 6 is an explanatory diagram showing the other side of the conventional shell mold manufacturing method, and Figure 7 (a) is A plan view showing the state of the shell mold before release in the embodiment method of the present invention, FIG. 7(b) is a cross-sectional view taken along the line ■-■ in FIG. - Fig. 9 is an explanatory diagram of vertical casting using a shell mold formed by the method according to one embodiment of the present invention, and Fig. 10 (a) is an enlarged perspective view of the method according to another embodiment of the present invention. A plan view showing the state of the shell mold before release, FIG. 10(b) is FIG. 10(IL) No.
A cross-sectional view taken along the X-ray, FIG. 11 is an enlarged perspective view of a degassing pin as a holding bottle, and FIG. 12 is a case of vertical casting using a shell mold formed by the method according to the other embodiments above. FIG. 1... Dump box, 6... Shell sand, 7-# product-8... Columnar part of article, 8a... Column pattern part,
9... Flange of article, 9a... Flange pattern portion, 16... Holding bottle, 14... Dummy plate,
15...Slit, 17...Shell rib, P...
Pattern plate, dl...convex split surface, modified...
Concave split surface, d3...stepped portion, Sa-...shell type. Patent applicant Toyo Kogyo Co., Ltd. Figure 1 (a) (b) (C)
(d) (e) Figure 2 Figure 3 a 8a Figure 5 Figure 6

Claims (2)

[Claims] (1) A method of directly expanding a halved shell mold for casting an article having seven flange on one end side of a columnar part, which method comprises directly expanding a joint surface between the longitudinal middle part of the columnar part and the flange in the article. Prepare a groove plate having a concave and convex split surface at a position corresponding to , and having a columnar pattern part and a 7-lunge pattern part on the concave split surface. 7. A holding bottle is erected on the side of one of the lunge pattern parts, and a metal dummy plate, which is opposed to the columnar pattern part with a gap in the concave space of the pattern plate, is engaged with the end of the holding bottle. By heating the pattern plate and dummy plate, and using a dump box to cover the pattern plate with shell sand, the columnar pattern portion and the stepped portion of the uneven split surface are removed along the dummy plate. A chevron method for shell-shaped articles with 7 lunges to form a shell lip extending in the joining direction. (2) The method of manufacturing a shell-shaped article with seven flanges according to claim 1, wherein the dummy plate is inserted into and locked into a slit formed at the end of the holding bottle.