JPH09239489A - Pattern and mold for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the damage of a sleeve and to obtain a good quality casting without sand mark by separating the heat insulating sleeve for feeder head from a casting pattern and holding. SOLUTION: Firstly, the lower end 14a of the heat insulating sleeve 12a for feeder head covered on a positional member 13a is supported with pins 15a projected from the casting pattern 11a, and the lower end 14a of the sleeve is forcedly separated from the pattern 11a. At the time of filling up molding sand in there, the molding sand is inserted even in the gap between the lower end 14a of the sleeve and the pattern 11a. Thereafter, at the time of compressing the molding sand, since the pins 15a are gradually stuck into the lower end 14a of the sleeve, the compressed force is absorbed and the heat insulating sleeve 12a is hardly broken. Further, since the molding sand in the gap between the lower end 14a of the sleeve and the pattern 11a is sufficiently hardened, the dropping of the molding sand in a process after separating from the mold and the wash-away at the time of pouring are eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding. In particular, the present invention relates to a mold making model provided with a feeder heat retaining sleeve, and also relates to a mold made using such a mold making model.

[0002]

Molds are required to make castings. Also, in order to make a mold, a casting model in the shape of a casting is required. That is, in order to make a mold, it is necessary to fill the molding sand around the molding sand, compress and compact the molding sand, and then remove the casting sand mold, leaving behind the casting mold cavity to form the mold. To be done.

Further, when the casting is made, the molten metal poured into the mold cavity shrinks as it cools, so in order to avoid the formation of "shrinkage cavities" in the casting, above the casting mold cavity,
And / or feeders are provided laterally. The riser needs to be kept warm in order to keep the molten metal in the riser molten for as long as possible. For this reason, the feeder is provided with a heat-generating or heat-insulating feeder sleeve around the feeder.

The feeder heat retaining sleeve is made of a refractory material and has a circular or elliptical cross section, and its inner surface is tapered to facilitate removal from the mold during molding. There are an open feeder heat retaining sleeve whose both ends are open and a blind feeder heat retaining sleeve whose one end is closed. There are two types of blind feeder heat retaining sleeves, one having a closed upper end made of a flat plate and the other made of a dome-shaped spherical plate. The upper part of the riser heat retaining sleeve, which has a dome-shaped spherical plate at the upper end, has the same cylindrical shape as the open upper heat retaining sleeve, and the upper and lower parts are made separately and glued together. Both have dome-shaped feeder sleeves. Further, a blind riser heat retaining sleeve with a hole in the top is turned upside down and a flat plate lid is placed on the top.

In order to make a mold provided with a feeder heat retaining sleeve, a mold making model in which a positioning member for determining the position of the feeder heat retaining sleeve is integrated with a casting model is prepared and used as a model. For example, in the case of attaching a feeder heat retaining sleeve of which both ends are open, as shown in FIG. 1, a positioning member 3a is integrally attached to a casting model 1a to form a mold for molding, and the positioning member therein. 3a was covered with a feeder heat retaining sleeve 2a, and casting sand was filled and compacted around this, and then the model for molding a mold was removed, and later the casting mold cavity and the feeder retaining sleeve were left as a mold. In this method, the lower end of the feeder heat retaining sleeve should be in close contact with the casting model.

Further, when using a blind hot water heat retaining sleeve having a dome-shaped upper end, the blind hot water heat insulating sleeve 2b is attached to a positioning member 3b having a dome-shaped end, for example, as shown in FIG. Covering, the lower end 4b of the sleeve 2b is brought into close contact with the casting model 1b, and the molding sand is filled and compacted around this, and then the positioning member is removed together with the casting model to form the casting mold cavity and riser. As a mold. The positioning member 3b does not have to occupy the entire cavity of the feeder heat retaining sleeve, and if the height of the feeder heat retaining sleeve can be positioned, as shown in FIG. It ’s okay.

Similarly, when a blind feeder sleeve having a flat upper end is used, for example, as shown in FIG. 3, the blind feeder heat retaining sleeve 2c is covered on the positioning member 3c, and the lower end 4c of the sleeve 2c is covered. The casting model 1c may be brought into close contact with the casting model, and the molding sand may be filled and compacted around the casting model 1c. Then, the positioning member may be removed together with the casting model, and later the casting mold cavity and the feeder may be formed to form a casting mold.

However, the mold thus produced has a drawback. When the molding sand is filled and compacted by the green molding machine, the lower end (4a, 4b, 4
c) The vicinity is damaged, the feeder heat retaining sleeve moves, and a gap is created between the casting model and the casting sand, and the casting sand enters the gap, and the casting sand that has entered falls into the mold cavity, or sideways. In the case of the feeder, it was washed by the molten metal flow and carried into the mold cavity, causing the sand biting defect of the casting.

For example, when using an AMF type green molding machine manufactured by Shinto Kogyo Co., Ltd., the mold is rotated 90 degrees and the molding sand is dropped from above by air pressure. Since it receives wind, the riser heat retaining sleeve floats up due to the wind pressure, creates a gap with the casting model, and the casting sand enters there. Also, when jolting is performed by applying vibration to the foundry sand using a raw molding machine such as AVS type manufactured by Shinto Kogyo Co., Ltd., the riser keeps the riser heat retaining sleeve and creates a gap between it and the foundry model. And the foundry sand invades. In this way, the mold filled with the foundry sand is further compressed and compacted. However, since the molding sand does not uniformly penetrate into the entire gap between the casting model and the lower end of the feeder heat retaining sleeve, compaction is insufficient. For this reason, foundry sand falls into the mold cavity or is washed away by the molten metal flow and enters the mold cavity, causing defective sand biting.

At present, in order to prevent the above sand entrapment, the foundry sand that has entered the lower end of the feeder heat retaining sleeve is manually removed. This is because the molding sand that has entered is relatively strongly attached to the feeder heat retaining sleeve, and it is not possible to completely remove the attached molding sand by mechanical means such as blowing air. . For this,
Removal of this foundry sand has been time consuming and has made mold manufacturing inefficient.

[0011]

SUMMARY OF THE INVENTION The present invention seeks to remedy the above-mentioned drawbacks. That is, the present invention reduces damage to the feeder heat retaining sleeve attached to the feeder when making a mold with a feeder using a molding machine, and also fills the molding sand around the casting mold with the molding sand. Then, by firmly compacting the molding sand between the feeder heat retaining sleeve and the casting model, the molding sand is prevented from falling into the mold cavity and being washed away by the molten metal flow, and the inclusion of the molding is prevented. The purpose is to eliminate defects.

[0012]

The inventor of the present invention supports the lower end of a feeder heat retaining sleeve covered by a positioning member with a pin projecting from a casting model, and intentionally separates the lower end of the sleeve from the casting model, and the casting is placed there. Forming a sand mold by positively letting sand in does not only eliminate casting sand in the subsequent steps of mold removal, mold matching, and washing during pouring, but also less damage to the feeder heat retaining sleeve. I found that. In other words, in the past, the lower end of the feeder heat retaining sleeve was brought into close contact with the casting model, so a slight gap was sometimes created between them, and as a result, the amount of casting sand that entered there was also small, and thorough compaction was required. Without doing so, the foundry sand will fall, but if this gap is made larger to some extent and a mold wall with a certain thickness is formed there, the gap will no longer exist. It has been found that the foundry sand that has entered does not fall or be washed away by the molten metal flow.

The minimum thickness of the molding sand that enters the gap and prevents the compacted molding sand from falling depends on the nature of the molding sand. In particular, it depends on the properties and amount of the binder used to make the foundry sand, and the size of the sand grains. Therefore, it is difficult to precisely determine the minimum thickness. However, to date, the minimum value of the thickness is about 3 mm in the result confirmed by the experiment by the present inventor. On the contrary, what is the maximum value of the thickness? Since there is a decrease in the effect of the feeder as the thickness increases, there is a restriction from this aspect. Since the effect of the feeder is different depending on the material that makes up the feeder heat retaining sleeve, it is difficult to specify the maximum thickness exactly.However, from a rough perspective, the thickness equivalent to the inner diameter of the feeder heat retaining sleeve is roughly Is. From the standpoint of the effect of the feeder, the preferable thickness is 5 mm or more and half the inner diameter of the feeder heat insulating sleeve or less. The inner diameter in this case refers to the inner diameter at the lower end of the sleeve. The present invention has been completed based on such knowledge.

According to the present invention, there is provided a casting model for forming a casting mold cavity and a positioning member for integrally determining the position of the feeder heat retaining sleeve, which is integrally attached to the casting model. The present invention provides a model for molding a mold, characterized in that means for holding the mold away from the casting model is provided near the boundary between the casting model and the positioning member.

The present invention also provides a method for manufacturing a mold using the above-described mold for molding.
The manufacturing method is to cover the positioning member in the mold making model with a riser heat retaining sleeve, fill the molding sand around the mold making sand with compaction, and then remove the mold making model and then cast it. It is characterized by forming a cavity and leaving a feeder heat retaining sleeve.

Further, the present invention also provides a mold manufactured using the above-described mold for molding. The mold is a mold in which a feeder heat retaining sleeve is provided above and / or to the side of the casting mold cavity, the feeder retaining heat insulating sleeve is separated from the casting mold cavity, and the distance is 3 mm or more,
It is characterized in that it is less than the inner diameter of the feeder heat retaining sleeve and is filled with foundry sand within the distance.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The greatest feature of the present invention is that the casting mold model is provided with means for holding the feeder heat retaining sleeve away from the casting model. The holding means may be provided on the casting model side or the positioning member side. The holding means has a different structure depending on which side is provided. A specific example in which the holding means is provided on the casting model side is shown in FIGS. 4 to 7, and a specific example in which the holding means is provided on the positioning member side is shown in FIG.

4 to 7, 11a and 11b are casting models, 12a and 12b are feeder heat retaining sleeves, and 1
3a and 13b are positioning members, 14a and 14b are lower ends of the feeder heat insulating sleeves 12a and 12b, 15a and 15b are pins constituting holding means, 16a is foundry sand, and 17a is an annular portion. The positioning members 13a and 13b are fixed on the casting models 11a and 11b, and the feeder heat retaining sleeves 12a and 12b are covered on the positioning members 13a and 13b. 4 to 6 show a process in which a mold is manufactured using the same mold for molding. Although another feeder heat retaining sleeve 12b is used in FIG. 7, the feeder retaining sleeve 12b has a dome shape in both upper and lower portions, and a hole 20b is formed in the lower dome portion.
The positioning member 13b fixed to the casting model is inserted in the.

4 to 7, the holding means is the pin 15
It is composed of a and 15b. Pins 15a, 15
b is a cast model 11a, 11b and a positioning member 13a,
It is fixed to the casting model side near the boundary where 13b contacts. When the feeder heat retaining sleeves are covered on the positioning members 13a, 13b, the tips of the pins 15a, 15b are attached to the lower ends 14a, 14b of the feeder heat retaining sleeves 12a, 12b.
To support the feeder heat retaining sleeve. The pins 15a and 15b are arranged around the positioning members 13a and 13b at equal intervals, and are located slightly away from the positioning members. Pin 15a,
The tip of 15b is sharp. Therefore, when the hot water retaining sleeves 12a, 12b are strongly pressed from above, the pins 15a, 1
The tip 5b digs into substantially the center or the lower surface of the wall thickness of the feeder heat retaining sleeves 12a and 12b, and the pins 15a and 15b firmly support the feeder heat retaining sleeves 12a and 12b.

FIG. 4 shows a state in which the feeder heat retaining sleeve 12a is put on the positioning member 13a of the mold making model according to the present invention. At this time, the tip of the pin 15a is in contact with the lower end 14a of the feeder heat retaining sleeve 12a, but it has not yet penetrated deeply into the inside. FIG. 5 shows that the molding sand 16a is filled around the casting mold shown in FIG.
The state is shown after compression and compaction. When the casting sand heat retaining sleeve 12a is filled with the molding sand and compressed, it is strongly pushed toward the casting model 11a and descends.
The tip of 5a bites into the lower end 14a of the feeder heat retaining sleeve 12a. At the same time, the molding sand 16a filled in the gap between the casting model 11a and the lower end 14a of the feeder heat retaining sleeve 12a is compacted by compression, and the pin 15
annular part 17a surrounding the positioning member 13a including a
To form After that, when the mold making model is removed, the pin 15a is removed together with the mold making model, and as shown in FIG. 6, the feeder 1 heat retaining sleeve 12a is left.
8a is formed, and a casting mold cavity 19a is formed.
FIG. 7 shows an embodiment of a riser heat retaining sleeve in which both upper and lower parts are dome-shaped, and the method and procedure for making a mold making model are the same as those in FIGS. 4 to 6.

As shown in FIG. 6, the mold thus produced has an annular portion 17a formed between the lower end 14a of the feeder heat retaining sleeve 12a and the casting mold cavity 19a. The annular portion 17a includes a cavity as a mark of the pin 15a, but since it has a considerable thickness and height and constitutes a part of the mold, there is no possibility of peeling or dropping.
Therefore, it can be used as it is as a mold, and a desired casting can be produced.

Generally speaking, the thickness of the pin is preferably as thin as possible so as not to disturb the compaction of the molding sand when compacting it, but the pin should have sufficient strength to withstand the pressure during molding. It is necessary to have. The thickness of the pin also depends on the thickness of the feeder heat retaining sleeve and the molding pressure. If the pin is made of iron or stainless steel,
Preference is given to using rods with a diameter of 1-5 mm. If the inner diameter of the feeder heat retaining sleeve is 40-100 mm, the diameter of the rod may be about 1-3 mm, but if the inner diameter exceeds 100 mm, the diameter of the rod is preferably about 3-5 mm. However, if the inner diameter of the feeder heat retaining sleeve is increased, the number of pins may be increased, and therefore, a pin having a diameter of 5 mm or more is not usually required. The cross-sectional shape of the pin is not specified,
Usually, it is preferable that the shape is circular or square. The upper end of the pin may be left cut in the case of a thin one, but it is preferable that the upper end of the pin be sharp only in the case of a thick one or be tapered over the whole.

When the tip of the pin is tapered, when the riser heat retaining sleeve descends when the molding sand is filled and compressed,
The pin gradually penetrates deeply into the lower end of the pin, and the molding pressure is absorbed thereby, so that damage to the feeder heat retaining sleeve is reduced. Further, when the die is removed, the pin can be smoothly removed without scraping off the molding sand. Furthermore, since the lower end of the feeder heat retaining sleeve is locked by the tip of the pin when the molding sand is filled, it is possible to prevent the feeder heat retaining sleeve from slipping or coming off due to blowing of the molding sand or vibration.

The pin is required to leave a certain distance between the lower end of the feeder heat retaining sleeve and the casting model at the final stage of filling and compressing the casting sand. This can be easily achieved by using an iron rod having a diameter of 1 to 5 mm in comparison with the feeder heat retaining sleeve which has been used so far. This is because the feeder heat insulating sleeves used up to now include fire resistant fibers and have an appropriate degree of flexibility and elasticity, and allow an appropriate amount of pin penetration by pressure during molding.

When the casting mold model shown in FIGS. 4 to 7 is used, the feeder heat retaining sleeve is held by the pin at the stage of filling the casting sand, and is located away from the upper surface of the casting model. Initially, the gap between the lower end of the hot water retaining sleeve and the casting model is also loosely filled with the casting sand. Then, when the molding sand is compressed, the pin gradually penetrates deeply into the lower end of the feeder heat retaining sleeve. Since the compressive force is absorbed by such movement of the feeder heat retaining sleeve, the feeder heat retaining sleeve is less likely to be broken. In addition, the keep warm sleeve
As mentioned above, since it contains refractory fibers, when a strong compressive force is applied at the time of molding and the pressure is released by the die afterwards, it generally tries to return to the original size, and for this reason, Although loosening occurs in the surrounding molding sand, such a phenomenon does not occur when the casting mold according to the present invention is used. On top of that, the molding sand that has entered the gap between the lower end of the feeder heat retaining sleeve and the casting model is also sufficiently compacted, so that the molding sand falls into the casting mold cavity and is washed away by the molten metal flow. There is no.

A mold made using the above-described mold for molding has a structure as described below. That is,
As shown in FIG. 6, a casting mold heat retaining sleeve 12a is provided above the casting mold cavity 19a, wherein the feeder heat retaining sleeve 12a is separated from the casting mold cavity, and the casting metal mold is kept between these distances. It is filled with sand. This filled foundry sand has a considerable height to form a solid annulus and is part of the mold. The height of the annular portion is usually not more than the inner diameter of the feeder heat retaining sleeve and not less than 3 mm.

In the above, the holding means of the feeder heat retaining sleeve is attached to the casting model side, but the retaining means of the feeder heat retaining sleeve can also be attached to the positioning member side. FIG. 8 shows means 2 for holding the lower end 24 of the dome-shaped blind riser heat retaining sleeve 22 away from the casting model 21.
5 shows an example in which 5 is attached to the positioning member 23. A plurality of holding means 25 are provided in the vicinity of the boundary between the casting model 21 and the positioning member 23 at equal distances in the circumferential direction of the positioning member 23, and each has a shape of a rib extending in the vertical direction. The upper end of each rib becomes lower as it goes up, so that it is easy to bite into the inner surface of the feeder heat retaining sleeve 22. Therefore, the riser heat retaining sleeve 22 covered by the positioning member 23 is fixed by the biting of the upper ends of the ribs, leaving a gap between the lower end 24 and the casting model 21. For this reason, the molding sand will enter this gap during molding.

In FIG. 8, the holding means 25 is formed separately and attached to the feeder model 23 side, but the holding means 25 may be formed integrally with the feeder model.

As described above, according to the present invention,
An example of a dome-shaped blind riser heat retaining sleeve and a blind riser heat retaining sleeve in which both upper and lower parts are dome-shaped has been described.
The present invention is not limited to the feeder heat retaining sleeve having the above-described shape, and a relatively large hole is formed at the top of the dome-shaped blind feeder heat retaining sleeve of FIG. 2 and the top flat type blind feeder heat retaining sleeve of FIG. It can be applied upside down and also to other types of feeder sleeve heat retaining sleeves such as a blind feeder heat retaining sleeve on which a flat plate lid is placed.

[0030]

EFFECT OF THE INVENTION In the model for molding a mold according to the present invention, means for holding the feeder heat retaining sleeve covered by the positioning member apart from the casting model is provided. In the casting mold, a tightly compacted casting annular portion is formed between the lower end of the feeder heat insulating sleeve and the casting model. Therefore, the foundry sand does not drop and is not washed away by the molten metal flow. Further, the above-mentioned holding means can be provided on the casting model side or the positioning member side, and therefore the holding means can be removed from the mold at the same time when the mold for molding is removed, which facilitates the production of the mold. . As a result, a desired mold can be easily made, and a good quality casting without sand entrapment can be easily made. The present invention provides such benefits.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical cross-sectional view showing a usage state of a conventional mold making model.

FIG. 2 is a partially cutaway vertical sectional view showing a use state of another conventional mold for molding.

FIG. 3 is a partially cutaway vertical sectional view showing a usage state of still another conventional mold-making model.

FIG. 4 is a partially cutaway vertical sectional view showing an initial stage of a use state of the mold for molding according to the present invention.

FIG. 5 is a partially cutaway vertical sectional view showing a further advanced stage of the use state of the mold-making model shown in FIG.

FIG. 6 is a partially cutaway vertical sectional view showing a further advanced stage of a use state of the mold for molding shown in FIG.

FIG. 7 is a partially cutaway vertical sectional view showing a usage state of another mold-making model according to the present invention.

FIG. 8 is a partially cutaway vertical perspective view showing a usage state of another mold making model according to the present invention.

[Explanation of symbols]

1a, 1b, 1c, 11a, 11b, 21 Casting model 2a, 2b, 2c, 12a, 12b, 22 Feeder heat insulating sleeve 3a, 3b, 3c, 13a, 13b, 23 Positioning member 4a, 4b, 4c, 14a, 14b , 24 Lower end of heat retaining sleeve 15a, 15b Pin 16a Foundry sand 17a Annular portion 18a Feeder 19a Foundry cavity 20b Hole 25 Rib

Claims (6)

[Claims] 1. A casting model for forming a casting mold cavity, wherein a positioning member for determining the position of the feeder heat retaining sleeve is integrally attached to the casting model, wherein the feeder heat retaining sleeve covered by the positioning member is cast. A model for molding a mold, characterized in that means for holding the model away from the model is provided near the boundary between the casting model and the positioning member. 2. The mold-making model according to claim 1, wherein the means is a pin attached to the casting model side. 3. The rib is a rib extending upward from the lower end on the surface of the positioning member.
The casting mold according to claim 1. 4. The mold-making model according to claim 3, wherein the ribs have a taper with a protruding height decreasing toward the upper end. 5. A mold molding model according to claim 1, wherein a positioning member is covered with a riser heat retaining sleeve, and molding sand is filled around the model molding mold and compacted. A method for producing a mold, characterized in that after that, the model for molding a mold is pulled out, a casting mold cavity is later formed and a feeder heat retaining sleeve is left. 6. In a mold having a feeder heat retaining sleeve provided above and / or to the side of the casting mold cavity, the feeder heat retaining sleeve is separated from the casting mold cavity by a certain distance, and the distance is 3 mm or more. A mold, characterized in that it is less than or equal to the inner diameter of the feeder heat retaining sleeve and is filled with molding sand in the distance.