JPH0230365A - Method for removing sprue in casting - Google Patents

Abstract

PURPOSE:To surely execute cutting of a gate by forming gap part at lower part of runner bottom in low part of a sprue, applying impact force on upper face of the sprue after solidifying by pouring molten metal into cavity in a mold from the sprue, and pushing down the runner to the gap part. CONSTITUTION:At the time of applying the impact force on the upper face of the sprue 14c with a drop hammer 30 by forming the gap part 23a at the lower part of the runner bottom 14b in the mold, the sprue 14c and the runner 14a are pushed down toward the gap part 23a, which is set to weak in strength, to cut the gate 14d. Therefore, the sprue 14c and the runner 14a can be surely removed from the casting product 11 in the cavity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improved method for removing sprues from castings.

(Prior Art) Conventionally, as shown in FIG. 5, in the shell mold casting method, a shell mold is housed in a casting box I, and the surrounding area is backed up with aggregate 2 such as steel shot and then poured.
After pouring and before demolding, an impact force is continuously applied to the upper surface of the sprue 4 of the casting in the casting box l using the impact tool 3, and the weir 6 is cut. A method for removing the sprue of shell mold castings has been proposed in which the sprue 4 and the like are removed from the product 5 (see Japanese Unexamined Patent Publication No. 56-9056).

(Problem to be Solved by the Invention) However, since the shell mold in the casting box l is backed up (tightened) with aggregate 2,
There was a problem in that the downward movement of the weir 6 could not be ensured sufficiently, and the cutting of the weir 6 tended to be uncertain.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to facilitate the downward movement of the sprue so that the weir can be cut reliably.

(Means for Solving the Problems) For this reason, in the present invention, when forming a mold, a cavity is formed in advance below the four bottoms continuous to the sprue, and the cavity of the mold is formed from the sprue through the runner and weir. After solidifying the molten metal, the weir is cut by applying an impact force to the top surface of the sprue and pushing down the runner including the sprue toward the cavity. The feature is that the road is removed.

(Operations and Effects of the Invention) The present invention provides a structure in which, by forming a void below the runner bottom of the mold, when an impact force is applied to the top surface of the sprue, the sprue and the runner are formed with a void that is set to have a weak strength. Since the sprue and the runner can be pushed down toward the bottom, the sprue and runner can be easily moved downward, and the weir can be reliably cut.

Therefore, the sprue and the runner can be reliably removed from the cast product within the cavity.

Note that the term "gate" here may be used as a general term for a gate and a runner, as the case may be.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 to 3, the skew table 10
To do this, a mold I5 having a pattern 12 for molding the cavity bottom 12a of the cast product 11 and a runner mold 14 for molding the runner 14a and the runner bottom +4b is placed upside down and the mold is placed upside down. The lower frame 19 for molding the lower mold 18 of the mold 17 is positioned upside down on the mold 15 by positioning pins 20, 20 of the mold 15.

In addition, the skewer plate 22 of the skewer head 21
In this case, the cavity 23a is formed at the same position as the runner bottom +4b formed by the runner mold 14 of the mold I5, facing the runner bottom I4b at a predetermined distance (for example, 100 mm or more). The void forming die 23 to be formed is the bolt 24. ..., is fixed at 24.

Then, the lower frame 19 is filled with molding sand 25, and as shown in FIG. 2, the skewer table 10 is raised and the skewer plate 22 pressurizes the molding sand 25.

As a result, the lower mold 18 has the runner 14a and the i-button 14b1.
A cavity bottom 12a and a cavity 23a are formed.

On the other hand, in the same molding process as the lower mold 18, molten metal is injected into the upper frame 27! 4c, the upper cavity 12b of the cast product 11, each part 12a12b of the cavity, and the runner +
The upper mold 2 of the mold 17 in which the weir 14d connected to the weir 4a is formed
8 is molded.

Then, as shown in FIG. 3, the lower mold 1 is placed on the surface plate 29.
The lower frame 19 formed with 8 is placed under vertical pressure, and this lower frame! When the upper frame 27 with the upper mold 28 molded thereon is placed on top of the mold 17, the mold 17 is completed.

After that, when molten metal is injected from the sprue 14c of the upper mold 28,
The molten metal flows from the runner 14a through the weir +4d to each part of the cavity 12a,! 2b, each part of the cavity 12
A cast product 11 is formed between a and 12b.

By pouring this molten metal, the runner bottom +4 due to the high heat of the molten metal.
The molding sand 25 between the gap 23a and the runner bottom 14b
The strength deteriorates at a predetermined depth (for example, 20 to 30 mm) (see crosshatching in FIG. 3).

After the molten metal has solidified, as shown in FIGS. 3 and 4, when an impact force is applied to the upper surface of the sprue 14c of the upper die 28 using an impact mechanism such as a drop hammer 30 or a cylinder, the sprue 14c and the molten metal are The path 14a is pushed down toward the cavity 23a.

When the sprue 14c and the runner 14a are pressed down, the cast product 11
Compared to the sand pressure of the foundry sand 25 (indicated by a in FIG. 4) below the foundry sand 25 between the runner bottom 14b and the cavity 23a,
5 (indicated by b in Fig. 4) has deteriorated in strength due to the thermal influence of the molten metal, and has weak strength and low sand pressure due to the voids 23a, so the downward direction of the sprue 14c and runner 14a It becomes easier to move.

On the other hand, since the cast product 11 is held under high sand pressure,
When the sprue 14c and the runner 14a are pushed down, cracks occur in the thin weir 14d and are cut, and the sprue 14c and the runner 14a are reliably removed from the cast product 11.

Thereafter, the molding sand 25 of the lower mold 18 and the upper mold 28 is broken down, and the separated cast product 11, sprue 14c, and runner 14a are taken out.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional front view of the main parts of the lower mold molding device, Figure 2 is a cross-sectional front view of the main parts during lower mold molding, Figure 3 is a cross-sectional front view of the main parts of the upper and lower molds after casting, and Figure 4 is a front view of the main parts of the lower mold molding device. FIG. 5 is a cross-sectional front view of the main parts of the upper and lower molds when folded at the weir, and FIG. 5 is a cross-sectional view of the conventional mold when folded at the weir. lg... Casting product, 14a... Runway, +4b... Runway bottom, 14c... Sprue, 14d... Weir, 1... Lower mold,
23. Gap mold, 23a... Gap portion, 25... Foundry sand, 28. Upper mold, 30. Drop hammer

Claims (1)

[Claims] (1) When forming the mold, a void is formed in advance below the runner bottom below the sprue, and after solidifying the molten metal by pouring it from the sprue into the cavity of the mold through the runner and weir, A sprue characterized in that the weir is cut by pressing down the runner including the sprue toward the cavity by applying an impact force to the upper surface, and the sprue and the runner are removed from the cast product within the cavity. Removal method.