JPH05337601A - Core for feeder in sand mold - Google Patents

Abstract

PURPOSE:To provide a core for feeder securing the feeding effect and the separating effect, in a casting by arranging to the feeder in a sand mold. CONSTITUTION:Relation between the opening ratio A of a net body 3 in the core for feeder composed by stretching the heat resistant net body in the opening part 2 arranged at the center of a refractory-made plate body 1 and the area ratio S1/S2=B of the area S1 of the center opening part 2 to the area S2 of the cross sectional area of the feeder at the upper surface of the plate body 1 is set as the follows. In the case of 20%<=A<30%, 20%<B<=47%; 30%<=A<40%, 16%<B<39%; 40%<=A<50%, 12%<B<31%; 50%<=A<=60% 12%<B<28%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sand core for a sand mold which is installed and used in a sand mold for casting a molten metal such as a high melting point metal.

[0002]

2. Description of the Related Art Conventionally, for example, a molten metal of a high-melting point metal is poured from a sprue using a planer sand mold which is provided with a sprue and a riser separately.
Filling the product casting space, casting with the molten metal pushed up to the feeder, after casting, the cast product and the feeder solidification part were cut and separated with a burner or a blade, but the separation work efficiency was Poorly, dust and the like were generated, which caused inconvenience such as a problem in hygiene. Further, in order to facilitate the separation work, as disclosed in Japanese Patent Laid-Open No. 60-82248 and the like, a core made of a refractory plate having a neck-down opening in the center thereof is pushed. At the base of the hot water, there is proposed a sand mold that is interposed between the space for casting products and after casting,
It has been proposed to separate the feeder coagulation part by hitting it with a hammer, but if the area of the central opening is too small, the feeder effect is hindered, and as a result, a defective product having a shrinkage cavity is produced and the production efficiency is increased. When the area of the central opening is too large, on the other hand, the cutting efficiency by the hammer is deteriorated and often the cutting cannot be performed. On the other hand, Japanese Patent Publication Sho 47-
At the base of the riser which doubles as the sprue disclosed in Japanese Patent No. 14631,
A core formed by stretching a heat resistant mesh is installed in a central opening having a diameter substantially the same as the diameter of the feeder, and the molten metal is filtered by the mesh of the core, and after casting, the mesh The core is designed to be easily divided, but the core has a diameter of the central opening and a diameter of the sprue which are substantially equal to each other. The impact is large and may cause deformation of the mesh body, resulting in deterioration of filterability, biting into the cast product due to hanging of the mesh body, and damage. Further, depending on the porosity of the net, the effect of the feeder is reduced and the separability is reduced. Applicant previously filed Japanese Patent Application No. 3-4
As No. 0989, an improved type of core for a feeder of a plan type sand mold provided with the feeder also serving as the above-mentioned gate is proposed. According to this, by setting the porosity of the mesh body in the range of 20 to 35%, impact resistance is imparted, and filterability, feeder effect, and separability are improved. Depending on the values of various factors such as the area of the opening, the porosity of the mesh and the area ratio of the central opening to the feeder cross-section of the heat-resistant plate, the above effects can be ensured. There is no guarantee that it will work. These conditions also apply to the core for the feeder of the plan type sand mold equipped with the sprue and the feeder separately, and the feeder effect and the condition value can be determined by examining the above various factors. It is desirable if possible.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and provides a feeder core of a sand mold that satisfies the above-mentioned demands.
A sand-type mold for holding a sand mold, which is made of a fire-resistant plate that holds a heat-resistant mesh stretched in the central opening, and is equipped with a sprue and a riser. In the child,
The area of the central opening is in the range of about 8 cm ² to about 40 cm ² , and the porosity A of the heat resistant netting and the area ratio B of the central opening to the feeder cross-section of the plate are The feature is that the relationship is set as follows. 20% <A <30% 20% <B <47%; 30% <A <40% 16% <B <39%; 40% <A <50% 12% <B <31%; 50% 12% <B <28% when ≦ A ≦ 60%. Further, the second invention comprises a refractory plate holding a heat-resistant mesh stretched in the central opening, and is installed at the feeder of a planer sand mold provided with a feeder also serving as a gate. In the sand-casting core for the feeder, the area of the central opening is about 8 cm.
The range of ² to about 40 cm ² , and the relationship between the porosity A of the heat-resistant mesh and the area ratio B of the central opening to the feeder cross section of the plate is set as follows. Is characterized by. 16% <B <47% at 20% ≦ A <30%; and 12% <B <43% at 30% ≦ A ≦ 35%.

[0004]

In the feeder core according to the first aspect of the present invention, the cutting effect of the hammer is surely brought about by the range of the area of the central opening. Further, by selecting the area ratio B in the above range in each of the open area ratios A of the above nets,
It guarantees the effect of the feeder and the effect that it can be easily divided by hitting it with a hammer 1 to 3 times, and a good quality cast product without shrinkage cavities can be surely obtained, resulting in an improvement in production efficiency. Second
The feeder core according to the present invention maintains good filtration performance, and brings about the same effects as those of the feeder core according to the first invention. In this case, it is preferable that the heat-resistant net body stretched over the central opening of the fireproof plate body of the core is stretched at a height of at least 2 mm from the lower surface of the plate. In this case, particles such as slag and slag in the molten metal can be floated and retained in the retention portion formed by the inner peripheral wall surface of the plate surrounding the portion on the lower surface of the net A good quality product that does not contain such particles can be obtained.

[0005]

EXAMPLES Next, examples of the present invention will be described in detail. Figure 1
2 and FIG. 2 show a riser molten iron core according to an embodiment of the present invention.
The core is a circular refractory plate 1 made of shell sand having an appropriate thickness, and a neck opening central opening 2 provided at the center of the plate 1 with its peripheral portion buried in a state. The heat-resistant net body 3 is held and stretched. Preferably, in order to keep the riser warm, a circular sleeve 4 is formed by binding a peripheral edge of the plate body 1, in the illustrated example, the lower end to the upper surface of the peripheral edge with a heat-resistant adhesive or the like.
There is a space 5 for the feeder having an inner diameter D and a volume therein.
It is preferable to use a feeder core having a sleeve for forming a feeder. The circular sleeve 4 is made of a heat-resistant material, and is preferably an exothermic sleeve for heating the feeder inside. The heat-resistant net body 3 is formed of a woven fabric made of carbon fiber or glass fiber, and is preferably made of SiO 2.
Woven fabrics composed of high silicate glass fibers containing 95% or more of ² are preferred. Further, the thickness is preferably about 0.5 to 2 mm.

[0006] First, in order to obtain the limits for producing the feeder effect and the dividing effect, the area S ₁ of the central opening 2, the open area ratio of the mesh body 3, the inner diameter D _{1 of the} sleeve 4, that is, the feeder space 5 for the feeder. A large number of feeder cores having the same structure as that of FIG. 1 with different inner diameters D ₁ are prepared, and these have the same structure as shown in FIG. 3, but various feeder cores are set. Each of the castings was carried out by setting them in the feeders of the sand molds of the plan type which were equipped with the feeders 7 and were suitable for casting. As a result, the area of the central opening is in the range of about 8 cm ² to about 40 cm ² and the open area ratio of the net is about 20% in order to bring about the effect of the feeder and enable the cutting with the hammer.
~ 60% range, feeder space, ie the inner diameter D of the sleeve
_{It has been determined that 1} is preferably in the range of about 70 mm to about 160 mm.

In the range of the porosity of the net body of 20 to 60%, the porosity and the area S ₁ of the central opening are the crossing area S ₂ of the feeder on the upper surface of the plate 1, that is, the sleeve in the embodiment. The ratio of the area ratio B to the area S _{2 of the} cross section of the feeder having the inner diameter D ₁ formed by section 4, that is, S ₁ / S ₂ = B, is important for the feeder effect and the cutting effect by the hammer. Focusing on the factor, the following tests were conducted to examine this relationship. That is, as the fireproof plate 1, a shell sand fireproof plate having a thickness of 10 mm and an outer diameter of 140 mm is used, and an outer diameter D ₂ 140 mm, an inner diameter D ₁ 100 mm, and a height 100 mm are attached to the upper surface of the peripheral portion thereof. , 0.8 liter container for the feeder space 5, plate 1
The cross section of the feeder has a common area of S ₂ 78.5 cm ² , but the area S ₁ of the central opening is variously changed as shown in Table 1 below, so that the area ratio (%) S ₁ / By changing S ₂ = B, the porosity of these central openings 2 is 20 to 60.
%, A large number of feeder cores each having a mesh body 3 of high silicate glass fiber stretched are set in the feeder 7 of the mold shown in FIG. 1 and the casting conditions shown in Table 2 are set. Was cast in. As the sleeve 4, a heat generating sleeve was used.

[0008]

[Table 1]

[0009]

[Table 2]

As is apparent from Table 1, it is understood that the feeder effect which does not cause the shrinkage cavity is exhibited when the porosity A and the area ratio B of the net are set in the following relationship. 20% <B at 20% <A <30%; 16% <B at 30% <A <40%; 12% <B at 40% <A <50%; 12% <at 50% <A <60% B.

After casting as described above, the feeder solidification portion of each cast taken out from the mold was hammered by a 3.6 Kg hammer.
It was tapped until it was separated from the cast product section. If the number of hits required for the division is 1 to 3 times, the division effect is easy,
Those having four or more times were judged to be defective in dividing effect. The test results are shown in Table 3 below. For reference, those having no net in each central opening are shown in Table 3.

[0012]

[Table 3]

As is clear from Table 3, when the area ratio S ₁ / S ₂ = B with respect to the open area ratio of the mesh is set as follows, it is understood that an excellent dividing effect is brought about. B <47% at 20% <A <30%; B <39% at 30% <A <40%; B <31% at 40% <A <50%; B <28 at 50% <A <60% %.

From the results of the feeder effect test and the fragmentation effect test described above, in order to secure the effect of the feeder without sinkhole and the easy fragmentation effect by hitting up to 3 times with a 3.6 kg hammer, A feeder core in which the area ratio S ₁ / S ₂ = B of the central opening S ₁ to the feeder cross-section S _{2 with} respect to the porosity A is set to have the following relationship is constructed. It was concluded that this was necessary. 20% <A <30% 20% <B <47%; 30% <A <40% 16% <B <39%; 40% <A <50% 12% <B <31%; 50% 12% <B <28% when ≦ A ≦ 60%.

Next, when a feeder core having the same structure as that described above is used in a planer sand mold equipped with a feeder also serving as a sprue, in order to obtain the same feeder effect and dividing effect as described above,
In order to examine whether the application ratio of the area ratio S ₁ / S ₂ = B to the open area ratio of the net body should be examined, a test similar to the above was carried out on the gate 7b of the sand mold 9a shown in FIG. After being installed, the casting was performed under the same casting conditions as shown in Table 2 above. In the drawing
8a indicates a space for casting products. However, the porosity of the mesh is
In order to maintain impact resistance when pouring the molten metal and excellent filterability, a porosity within the range of 20% to 35% proposed in Japanese Patent Application No. 3-40989 was used. .. The feeder effect test results are shown in Table 4 below.

[0016]

[Table 4]

As is clear from Table 4, the feeder effect without shrinkage cavities was found to be achieved by setting the area ratio B to the open area ratio A of the net body in the following relationship. 16% <B at 20% ≦ A <30%; 12% <B at 30% ≦ A ≦ 35%.

Table 5 below shows the results of the cutting effect test of the feeder solidification portion of each casting obtained by the above casting.

[0019]

[Table 5]

As is clear from Table 5, the relationship between the open area ratio A and the area ratio B of the net which can be divided by the number of times of hitting with a hammer of 3 times or less must be set as follows. B <47% at 20% ≦ A <30%; B <43% at 30% ≦ A ≦ 35%.

From the above test results, the relationship between the porosity A of the net and the area ratio B has the following relationship between the feeder effect without the occurrence of shrinkage cavities and the cutting effect with a hammering frequency of 3 or less. It can be ensured by producing a core for a feeder. 16% <B <47% at 20% ≦ A <30%; 12% <B <43% at 30% ≦ A ≦ 35%.

The above test results of the feeder effect and the cutting effect are as follows: sleeve inner diameter 100 mm, feeder cross section 78.5 cm ²
I used a feeder core with a sleeve inner diameter of about 70 ~
Range of about 160 mm, that is, the cross-sectional area of the feeder gate is about 30 cm ²
The same test results as above were obtained even when the feeder core with a sleeve having a range of about 200 cm ² was used.

In the feeder core of the present invention, the inner peripheral surface surrounding the central opening 2 of the plate 1 is formed in a wedge shape which becomes thin as it reaches the tip as is conventionally known. May be. Further, in the case of the feeder core with sleeve, the surface area surrounded by the inner diameter of the sleeve 4 bound to the upper surface or the end surface of the outer peripheral edge of the plate body 1 becomes the feeder area S ₁ .
When installed in the mold, the internal space of the sleeve 4 regulates the feeder, but in the case of a feeder core consisting only of the plate 1 without the sleeve, it is exposed to the feeder of the mold. The surface becomes the feeder cross section S ₂ .

According to the feeder core of the present invention, a more preferable embodiment is that the mesh 3 is stretched at a height of at least 2 mm from the lower surface of the plate 1 having a height of 10 mm. ..
According to this, the core of the mold 9 shown in FIG. 3 or FIG.
Or if it is installed in the feeder 7 or 7a of 9a, its mesh 3
A space 10 for accumulating foreign particles such as slag and slag having a height of at least 2 mm from the lower surface of the plate 1 is formed above the product space 8 or 8a having a height of 2 mm or less on the lower surface of the plate. Therefore, it is possible to prevent such foreign particles from biting into the cast product, and after cutting, the foreign particle particle accumulation layer is ground and removed, so that a product with a beautiful surface can be obtained. Therefore, it is desirable that the integrated layer is as thin as possible. Therefore, it is general that the net body 3 of the storage space 10 is secured about 2 to 5 mm from the lower surface of the plate body 1.

[0025]

As described above, according to the present invention, the heat-resistant net body having the above-mentioned predetermined opening portion at the center of the fireproof plate and having the above-mentioned predetermined opening ratio is stretched at the center opening portion. In the case of a feeder core which is provided, when it is used for a planer sand mold having a sprue and a feeder separately, the porosity A of the net and the feeder receiving surface of the plate are Area ratio B of the central opening
By setting and as follows, it is possible to secure the effect of riser that produces cast products without shrinkage cavities and the effect of cutting that can be cut by hitting at most three times with a 3.6 kg hammer. Bring Note 20% <A <30% 20% <B <47%; 30% <A <40% 16% <B <39%; 40% <A <50% 12% <B <31%; 50 12% <B <28% in% ≦ A ≦ 60%. When this is used in a plan sand mold having a feeder that also serves as a pouring port, the open area ratio A of the mesh and the above area ratio B are 16% <B when 20% ≦ A <30%. <47%; when 30% ≤ A ≤ 35% and 12% <B <43%, good impact resistance and filterability at the time of pouring are ensured, and the same effect as the above-mentioned feeder is provided. It has the effect of ensuring the dividing effect. In this case, the net body of the feeder core of the present invention is at least 2 times lower than the lower surface of the plate body.
When stretched to a height of mm, foreign matter particles such as slag and slag can be prevented from invading the surface of the cast product after cutting, which is preferable because a high quality product can be secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a feeder core according to an embodiment of the present invention.

FIG. 2 is a top view of the feeder core shown in FIG.

FIG. 3 is a vertical cross-sectional view of a sand mold, which is a plan system having a sprue and a feeder separately and in which a feeder core of the present invention is installed.

FIG. 4 is a vertical cross-sectional view of a sand mold, which is a plan system having a feeder serving also as a gate and provided with a feeder core of the present invention.

[Explanation of reference numerals] 1 refractory plate 2 central opening 3
Heat resistant net 4 Sleeve 9 Sand mold 9a
Sand mold 10 Space for storing foreign particles A Porosity of mesh B B
Area ratio S ₁ Area of central opening S ₂ Area of cross section of riser

[Table 1] × Generation of shrinkage cavities with a hole diameter of 2 mm or more △ Generation of shrinkage cavities with a hole diameter of 2 mm or less ○ No occurrence of shrinkage cavities

[Table 2]

[Table 3]

[Table 4]

[Table 5]

Claims (3)

[Claims] 1. A sand mold of a plan type sand mold, which comprises a refractory plate holding a heat resistant mesh stretched over a central opening and is provided with a gate and a feeder separately. In the case of the feeder core, the area of the central opening is about 8 cm ² to about 40 cm.
It is in the range of ² , and the relationship between the porosity A of the heat-resistant mesh and the area ratio B of the central opening to the feeder cross section of the plate is set as follows. .. 20% <A <30% 20% <B <47%; 30% <A <40% 16% <B <39%; 40% <A <50% 12% <B <31%; 50% 12% <B <28% when ≦ A ≦ 60%. 2. A sand mold for sand molds, which comprises a refractory plate having a heat-resistant net body stretched over a central opening and is equipped with a riser which also serves as a sprue. The area of the central opening of the feeder core is about 8 cm ² to about 40 cm
It is in the range of ² , and the relationship between the porosity A of the heat-resistant mesh and the area ratio B of the central opening to the feeder cross section of the plate is set as follows. .. 16% <B <47% at 20% ≦ A <30%; 12% <B <43% at 30% ≦ A ≦ 35%. 3. The heat-resistant net body stretched over the central opening of the fire-resistant plate body is stretched at a height of at least 2 mm from the bottom surface of the fire-resistant plate body. Or the core for the feeder of the sand mold of 2.