JP2552026B2 - Core molding equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a core molding device for molding a core having a thin portion.

[Prior Art] Conventionally, as such a core molding device, one shown in FIG. 5 is known.

In FIG. 5, 1 is a lower mold having a cavity 2, 3 is a squeeze mold having a squeeze allowance L, 4 is a blow squeeze mold having a blowing port 5 for blowing sand into the cavity 2 of the lower mold 1. (Upper mold). The upper mold 4 is designed to descend by a distance L after the cavity 2 of the lower mold 1 is filled with sand. That is, the upper die 4 squeezes the squeeze allowance L.

The cavity 2 of the lower mold 1 has a shallow portion 2a and a deep portion 2b.
Therefore, the sand blown from the blow-in port 5 of the upper mold 4 is filled from the deep portion 2b of the cavity 2.

When molding the core, first, as shown in FIG. 5, the molding 3 is placed on the lower die 1, and the upper die 4 is placed on the embossing die 3 to perform die matching. . Then, sand is blown into the cavity 2 of the lower mold 1 from the blowing port 5 of the upper mold 4 to fill the cavity 2 with sand. After the deep part 2b and the shallow part 2a of the cavity 2 are filled with sand, as shown in FIG.
The upper die 4 is lowered by a distance L and squeezed.

By this squeeze, the sand in the cavity 2 is compressed and the core is molded. That is, the core 6 is molded. The core 6 is held by the mold with a constant strength. This is because the sand is composed of the sand particles and the clay that is a binder that coats the sand particles, and the sand is bonded to each other by the clay due to the compression.

Then, after removing the upper die 4 and the mold die 3 and demolding the core 6, the core 6 is cured by heat treatment or the like to complete the core 6 as shown in FIG. Becomes

[Problems to be Solved by the Invention] By the way, in the core molding apparatus, since the upper mold 4 is lowered by the distance L to squeeze when molding the core, the depth D is larger than the depth D in the deep portion 2b of the cavity 2. Since the compression rate is L / D, the compression rate is L / D, which is small, but the compression rate is L / d because the compression is L for the depth d (d <D) in the shallow portion 2a. Its value becomes large. That is, the sand in the shallow portion 2a is highly compressed, and the clay covering the sand grains is destroyed. Therefore, as shown in FIG. 7, the problem that the thin-walled portion 6a of the core 6 is reduced in the caking strength and the mold release of the core becomes poor, or cracks 7 occur in the thin-walled portion 6a. was there.

Further, if the squeeze pressure is weakened, it is possible to prevent the thin portion 6a of the core 6 from cracking or the like.
As shown by the chain line in Fig. 7, the upper part of
The problem arises that the thickness of the is different from the design value.

[Object of the Invention] The present invention has been made in view of the above problems,
The purpose is to reduce the caking strength of the thin-walled part of the core without weakening the squeeze pressure and to make the thin-walled part have an appropriate caking strength without causing cracks in the thin-walled part. An object of the present invention is to provide a core molding device that can be used.

[Means for Solving the Problems] In order to achieve the above object, the present invention forms a sand filling cavity having a deep portion and a shallow portion by combining an upper die and a lower die, and In a core forming apparatus for squeezing by moving at least one mold after filling sand from the position of the deep portion, a closing member provided in the shallow portion for closing the shallow portion of the cavity is provided. When the sand is filled, the closing member is inserted to a position where the shallow portion is closed, and when the squeeze is performed, the sand in the deep portion of the cavity flows into the shallow portion by the squeeze and the closing is performed until the shallow portion is filled with the sand. A driving means for retracting the member is provided.

[Operation] With the above configuration, the drive means inserts the closing member to the position where the shallow portion of the cavity is closed when the sand is filled.
The shallow part is not filled with sand. When the squeeze is performed, the drive means retracts the closing member from the shallow portion, so that the sand in the deep portion of the cavity flows into the shallow portion by the squeeze and the shallow portion is filled with sand.

[Embodiment] An embodiment of the core molding apparatus according to the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a lower mold having a cavity 12, which has a deep portion 13 and a shallow portion 14, and a bottom portion 14a of the shallow portion 14 and a peripheral wall corresponding to the shallow portion 14. The upper surface 15a of 15 is coplanar. 1
6 is a squeeze type with a squeeze allowance L. The peripheral wall 17 of this squeeze type 16
A concave portion 18 is formed on the opposite side to face the upper surface 15a and communicates the cavity 12 with the outside. An insert (closing member) 19 which is inserted and retracted in the shallow portion 14 of the cavity 12 is arranged in the recess 18, and the insert 19 is a cylinder provided on the mold die 16 as shown in FIG. When the (driving means) 20 is operated, it is inserted into the shallow portion 14 of the cavity 12 and the shallow portion 14 is closed. The insert 19 is retracted from its shallow portion 14 to the position shown in FIG. 1 by the operation of the cylinder 20.

Reference numeral 21 is a blow squeeze mold (upper mold) having a blow port 22 for blowing sand into the cavity 12 of the lower mold 11. This upper model
21 is designed to descend by a distance L after filling the cavity 12 of the lower mold 11 with sand. That is, the upper die 21 squeezes the squeeze allowance L.

When molding the core, first, as shown in FIG. 1, place the mold 16 on the lower mold 11, and then the upper mold 21 on the mold 16 to align the molds. To do. Then, the cylinder 20 is operated to insert the insert 19 into the shallow portion 14 of the cavity 12 as shown in FIG. This allows the shallow part 14 to nest.
It will be blocked at 19. Next, the sand is blown into the cavity 12 of the lower mold 11 from the blowing port 22 of the upper mold 21,
Fill with sand. At this time, the shallow portion 14 of the cavity 2
Since the insert 19 is inserted into the groove and the shallow portion 14 is closed, only the deep portion 14 of the cavity 12 is filled with sand.

When sand filling is completed, operate cylinder 20 to insert
19 is retracted from the shallow portion 14 of the cavity 12 (see FIG. 3). Then, as shown in FIG.
If you lower it, that is, if you squeeze,
As it descends, the sand filled in the deep portion 13 of the cavity 12 flows into the shallow portion 14, and the shallow portion 14 is also filled with sand. Then, after the upper mold 11 descends by a predetermined distance,
The sand filled in the deep portion 13 and the shallow portion 14 of the cavity 12 is compressed as the upper die 11 descends, and the core is molded to form the core.

Then, after removing the upper die 21 and the mold die 16 to remove the core 30, the core 30 is cured by heat treatment or the like, as shown in FIGS. 4 (A) and 4 (B). Child 30 will be completed.

By the way, when starting the squeeze of the upper mold 21,
The shallow part 14 of the mold is not filled with sand, and as the upper mold 21 descends, the shallow part 14 is filled with sand, and then the sand is compressed. The sand is not highly compressed. That is, the density of the core 30 is substantially uniform regardless of the wall thickness.

Since the sand filled in the shallow portion 14 is not highly compressed, the clay coating the sand grains of the sand is not destroyed, and the thin portion 30a of the core 30 has a crack or a thin portion. The caking strength of 30a does not decrease.
Therefore, an appropriate caking strength can be obtained even in the thin portion 30a of the core 30, and the core 30 can be easily released from the mold.

Also, as the upper mold 21 descends, the deep part of the cavity 12
Although the sand of 13 flows into the shallow portion 14, the amount of the inflow is small with respect to the volume of the deep portion 13, so that the squeeze pressure hardly decreases.

If the control device controls the operation of the sillin 20 in response to the sand filling and the lowering operation of the upper die 21, a series of core forming operations can be automatically performed.

[Effects] As described above, according to the present invention, the thin-walled portion can be formed without lowering the caking strength of the thin-walled portion of the core and without causing cracks in the thin-walled portion without weakening the squeeze pressure. Can be made to have an appropriate caking strength, and the core can be easily demolded.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a core molding device according to the present invention, FIGS. 2 and 3 are explanatory views showing a core molding process, and FIGS. 4 (A) and (B) are molding processes. FIG. 5 is a side view showing a core that has been formed, FIG. 5 and FIG. 6 are cross-sectional views showing the configuration of a conventional core molding device, and FIG. 7 is a core molded by the conventional core molding device. FIG. 11 …… Lower mold 12 …… Cavity 13 …… Deep part 14 …… Shallow part 19 …… Insertion (blocking member) 20 …… Cylinder (driving means) 21 …… Upper mold

Claims (1)

(57) [Claims] 1. An upper mold and a lower mold are combined to form a sand filling cavity having a deep portion and a shallow portion, and the cavity is filled with sand from the position of the deep portion.
In a core forming device for squeezing by moving at least one mold, a closing member that is inserted and retracted in the shallow portion of the cavity is provided to close the shallow portion of the cavity, and the closing is performed up to a position where the shallow portion is closed during sand filling. A driving means for inserting the member and for retracting the closing member to a position where the sand in the deep portion of the cavity flows into the shallow portion by the squeeze during the squeeze and the shallow portion is filled with the sand. Core molding equipment.