JP5713709B2 - Cast iron casting method - Google Patents

Description

The present invention relates to a cast iron casting method , and more particularly to a cast iron casting method capable of increasing the strength as a dense and uniform structure by crushing the inner nest of a cast product during high temperature casting.

  Unlike non-ferrous metals, cast iron casting is a very hot casting. Conventionally, in order to improve the structure of castings and improve internal defects such as nests, a method of combining a material having a high cooling effect called a cooling die or improving by a casting method has been generally employed. However, in these methods, it is the present situation that the inner nest of the cast iron product is crushed and sufficient strength cannot be achieved as a dense and uniform structure. Thus, a conventional casting apparatus has been proposed that can be inserted into a cavity of a mold and includes a pressure pin that pressurizes molten cast iron poured into the cavity (for example, Patent Documents). 1). Such partial pressurization of the pressure pin effectively improves the structure of the cast iron product.

JP 2006-122971 A

  However, in the technique of Patent Document 1 described above, since the molten cast iron in the cavity is partially pressurized using the pressure pin, the pressure action does not reach the entire cast iron in the cavity, and the pressure of the pressure pin is increased. It is difficult to set the timing appropriately. For this reason, it becomes difficult to mass-produce cast iron products stably. In addition, it is thought that the above-mentioned problem arises similarly when obtaining castings, such as a copper alloy and a titanium alloy.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a cast iron casting method capable of increasing the strength as a dense and uniform structure by crushing the inner nest of a cast product during high temperature casting. And

The present invention is as follows.
1. A cavity is formed between the lower mold that is a fixed mold, the upper mold that is a movable mold that can move toward and away from the lower mold, and the upper mold and the lower mold. A mold structure comprising an intermediate mold that is movable in the vertical direction with respect to the lower mold so as to pressurize the molten cast iron to be hot water, and a floating means for levitating the intermediate mold with respect to the lower mold A cast iron casting method using
The upper mold is brought close to the lower mold during pouring of the molten cast iron into the cavity, and the intermediate mold is moved downward with the upper mold in contact with the intermediate mold. A cast iron casting method characterized by pressurizing the molten iron inside .
2. The intermediate mold is fitted to the lower mold so as to be movable in the vertical direction,
A gap for degassing is formed at the fitting part between the intermediate mold and the lower mold, and the gap (s2) is 0.1 to 0.4 mm.
The said clearance gap has the 1st clearance gap distribute | arranged to the vicinity of the gate, and the 2nd clearance gap which is distribute | arranged far from the said gate gap from the said 1st clearance gap, and has a clearance gap larger than the said 1st clearance gap . The cast iron casting method described.
3. One of the lower mold and the intermediate mold is provided with a guide pin extending in the vertical direction, and the other mold is provided with a guide hole for guiding the guide pin in the vertical direction. Or 2. Cast iron casting method according to.

According to the cast iron casting method of the present invention, the molten metal is poured into the cavity formed by the upper mold, the lower mold, and the intermediate mold that is floated by the floating means, and the floating force of the floating means is resisted during the pouring. Then, the upper mold and the lower mold are brought close to each other, and the entire molten metal in the cavity is pressurized as the intermediate mold moves in the vertical direction. Due to the rapid cooling effect of the molten metal due to the pressurization, the inner nest of the cast iron product as a cast product is crushed and formed into a dense and uniform structure during high temperature casting, and high strength can be achieved.
The intermediate mold is fitted to the lower mold so as to be movable in the vertical direction, and a gap for degassing is formed at a fitting portion between the intermediate mold and the lower mold. When (s2) is 0.1 to 0.4 mm, the gap interval (s2) is 0.1 mm or more. Therefore, the surface properties of the cast product can be obtained by degassing while suitably absorbing the thermal expansion of the mold. And the fitting property of the intermediate mold to the lower mold can be improved. Further, since the gap interval (s2) is 0.4 mm or less, the generation of burrs can be suppressed.
Further, when one of the lower mold and the intermediate mold is provided with a guide pin and the other mold is provided with a guide hole, the intermediate mold moves in the vertical direction with respect to the lower mold. Since the guide pin is guided to the guide hole when doing so, the positioning accuracy in the plane direction of the intermediate mold can be improved.

The present invention will be further described in the following detailed description with reference to the drawings referred to, with reference to non-limiting examples of exemplary embodiments according to the present invention. Similar parts are shown throughout the several figures.
It is a longitudinal cross-sectional view of the metal mold | die structure which concerns on an Example. It is a disassembled perspective view of the upper mold | type, lower mold | type, and intermediate mold | type which comprise the said metal mold | die structure. It is a disassembled perspective view of the nested type which comprises the said lower mold | type. It is a principal part enlarged view of FIG. It is explanatory drawing for demonstrating the casting effect | action of the said metal mold | die structure. It is explanatory drawing for demonstrating the casting effect | action of the said metal mold | die structure. It is explanatory drawing for demonstrating the casting effect | action of the said metal mold | die structure. It is explanatory drawing for demonstrating the casting effect | action of the said metal mold | die structure. It is a disassembled perspective view of the metal mold | die structure of another form. It is explanatory drawing for demonstrating the form of the clearance gap for degassing of the intermediate | middle type | mold and lower mold | type of another form.

  The items shown here are exemplary and illustrative of the embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

1. Mold structure Embodiment 1 The mold structure according to the present invention is a mold structure for casting, and an upper mold (5) and a lower mold (6) that can be brought close to and separated from each other, and a cavity ( C) and an intermediate mold (7) that is movable in the vertical direction between the upper mold and the lower mold so that the molten metal poured into the cavity can be pressurized, and an intermediate with respect to the lower mold And a floating means (3) for floating the mold (see, for example, FIG. 1).

  Examples of the levitation means include a fluid pressure cylinder and an elastic body (for example, a spring and rubber). Of these, a fluid pressure cylinder is preferable from the viewpoint of durability and controllability of flying height. Further, the flying height of the intermediate mold is appropriately selected according to the shape, size, etc. of the cast product. From the standpoint of pressurization in the cavity, it is preferable that the flying height (s3) of the intermediate mold is 0.3 to 2 mm (preferably 0.5 to 0.9 mm) (for example, see FIG. 4 and the like).

  Embodiment 1 For example, [1] the intermediate mold is fitted to the lower mold so as to be freely movable in the vertical direction, and a gap (25 for degassing is provided at a fitting portion between the intermediate mold and the lower mold. ), And the gap interval (s2) is 0.1 to 0.4 mm (preferably 0.1 to 0.3 mm) (see, for example, FIG. 4), [2] lower mold A plurality of split molds (12, 13) constituting the gas pipe are fitted in the vertical direction, and a degassing gap (24) is formed between the plurality of split mold fitting portions. The interval (s1) may be one or a combination of two or more of forms (for example, see FIG. 4 and the like) that are 0.1 to 0.4 mm (preferably 0.1 to 0.3 mm). it can.

  In the above [1] and [2] modes, for example, the gap for degassing includes the first gap (25a) and the second gap (25b) connected to the first gap and having a gap interval larger than the first gap. (See, for example, FIG. 10). Thereby, for example, if the first gap is arranged in the vicinity of the gate and the second gap is arranged far from the gate, the first gap can more reliably suppress the occurrence of burrs of a relatively high temperature molten metal, and the second gap. The surface property of the cast product and the fitting property of the intermediate mold can be further improved by the gap.

  In the above [1] mode, for example, the fitting part of the intermediate mold with the lower mold can be formed in a stepped shape (for example, see FIG. 4 and the like). As a result, it is possible to more reliably suppress the occurrence of burrs by reducing the fitting surface area between the intermediate mold and the lower mold to the necessary minimum.

  Embodiment 1 As the mold structure according to the above, for example, one of the lower mold and the intermediate mold is provided with a guide pin (17) extending in the vertical direction, and the other mold is provided with a guide for guiding the guide pin in the vertical direction. The form in which the hole (18) is provided can be mentioned (for example, refer FIG. 9 etc.). The guide pins and the guide holes are preferably arranged outside the cavity in plan view of the intermediate mold. This is because the thermal expansion of the intermediate mold can be more reliably suppressed.

  Embodiment 1 As the mold structure according to the above, for example, the upper mold and the lower mold are brought close to each other against the levitation force of the levitation means, the intermediate mold is moved in the vertical direction, and the molten metal in the cavity is pressurized with a pressure of less than 18 MPa. The form can be mentioned. Thereby, it is possible to obtain a high-quality cast product with a small pressing force compared to aluminum die casting or the like.

  Embodiment 1 For example, the upper mold and the intermediate mold are made of hot tool steel, and at least one divided mold (12) of a plurality of divided molds constituting the lower mold is made of a copper alloy. A form can be mentioned (for example, refer FIG. 2 etc.). Thus, the heat resistance and rigidity of the entire mold structure can be improved by the upper mold and the intermediate mold made of hot tool steel, and the quenching effect of the molten metal can be further improved by at least one divided mold made of copper alloy. it can. As this hot tool steel, for example, SKD61 or the like can be used. Moreover, as a copper alloy, chromium copper etc. can be used, for example.

  Embodiment 1 As the mold structure according to the above, for example, a form further provided with preheating means (4) inserted between the upper mold and the lower mold in the mold open state to preheat the upper mold, the lower mold and the intermediate mold can be mentioned. (For example, see FIG. 5 etc.). Thereby, the hot water roundness at the time of pouring can be improved, and the tensile strength and elongation of the resulting cast product can be improved.

  Embodiment 1 As the mold structure according to the above, for example, there may be mentioned a form further comprising pressing means (8) for pressing down the gate mold (15) placed on the upper mold or the intermediate mold (for example, FIG. 6). reference). Thereby, the rise of the gate type at the time of pouring can be prevented. Examples of the pressing means include a fluid pressure cylinder and an elastic body (for example, a spring and rubber). Of these, a fluid pressure cylinder is preferable from the viewpoint of durability and controllability of the pressing amount.

  The type of the “molten metal”, the pouring temperature, etc. are not particularly limited. Examples of the molten metal include cast iron, copper alloy, and titanium alloy. Examples of the cast iron include spheroidal graphite cast iron, gray cast iron, and malleable cast iron. Of these, spheroidal graphite cast iron is preferable from the viewpoint of tensile strength and elongation of cast iron products. Moreover, the pouring temperature of the cast iron melt can be, for example, 1200 to 1400 ° C. (preferably 1250 to 1350 ° C.). The cast iron melt can be poured into the cavity so as to be in a semi-solid state, for example. As a result, the strength of the resulting cast iron product can be further increased. The semi-solid state is intended to be a solid-liquid coexistence state, for example, a state where the cast iron melt is filled into the cavity at a pouring temperature of 1200 to 1400 ° C. (preferably 1250 to 1350 ° C.). Can be mentioned. Moreover, the viscosity coefficient of the cast iron melt can be 9 to 11 cps at 1300 to 1400 ° C., for example.

2. Casting method Embodiment 2 The casting method according to the first embodiment is the same as in the first embodiment. A casting method using a mold structure according to the above-mentioned method, in which a molten cast iron is poured into a cavity formed by an upper mold, a lower mold, and an intermediate mold, and the upper mold and the lower mold during or after the pouring And a step of bringing the mold close to each other and moving the intermediate mold in the vertical direction to pressurize the molten cast iron in the cavity.

  Hereinafter, the present invention will be specifically described with reference to the drawings. In this embodiment, a mold structure for casting a plurality of cast iron products using spheroidal graphite cast iron (hereinafter also simply referred to as “cast iron”) is illustrated.

(1) Configuration of Mold Structure As shown in FIGS. 1 and 2, the mold structure 1 according to the present embodiment includes an upper mold 5 and a lower mold 6, and the upper mold 5 and the lower mold 6. An intermediate mold 7 (also referred to as a “shield block”) that forms the cavity C, and a levitation cylinder 3 that levitates the intermediate mold 7 relative to the lower mold 6 (illustrated as “levitation means” according to the present invention). It is equipped with. The mold structure further includes a preheating heater 4 (see FIG. 5) and a pressing cylinder 8 (see FIG. 6).

  The upper mold 5 is made of hot tool steel (for example, made of SKD61). The upper die 5 is connected to a driving mechanism (not shown) (for example, a fluid pressure cylinder) via a connecting portion 9, and can be moved toward and away from the lower die 6 by driving the driving mechanism. .

  The lower mold 6 has a main body mold 6a made of hot tool steel (for example, made of SKD61) disposed on the base 10, and a plurality of nested molds 6b disposed on the main body mold 6a. ing. As shown in FIG. 3, each nesting die 6b includes an inner divided die 12 made of a copper alloy (for example, made of chrome copper), and a hole 13a fitted in the inner divided die 12 in the vertical direction (see FIG. 4). And an outer split mold 13 made of hot tool steel (for example, made of SKD61). As shown in FIG. 4, a degassing gap 24 having a distance s1 of about 0.2 mm is formed between the fitting portions of the inner split mold 12 and the outer split mold 13.

  The intermediate mold 7 is made of hot tool steel (for example, SKD61). As shown in FIGS. 1 and 2, the intermediate die 7 has a hole portion 7 a that is fitted in the vertical direction to the nested die 6 b of the lower die 6, and is a cast iron melt that is poured into the cavity C. It is possible to move in the vertical direction between the upper mold 5 and the lower mold 6 so that the pressure can be pressurized. As shown in FIG. 4, a degassing gap 25 having an interval s2 of about 0.2 mm is formed at a fitting portion between the intermediate die 7 and the nested die 6b of the lower die 6. Further, the fitting portion with the intermediate type nesting die 6b is formed in a stepped shape.

  As shown in FIG. 1, the levitation cylinder 3 includes a cylinder body 3 a that is supported by a pedestal 10 and a piston rod 3 b that is connected to the intermediate mold 7 at the tip side. As shown in FIG. 4, the flying height s3 of the intermediate mold 7 by the flying cylinder 3 (that is, the separation distance s3 of the intermediate mold 7 with respect to the lower mold 6) is about 0.3 mm. Therefore, as will be described later, when the upper die 5 is brought close to the lower die 6 to pressurize the cavity C against the levitation force of the levitation cylinder 3, the intermediate die 7 becomes the lower die. 6 is moved downward by the flying height s3.

  As shown in FIG. 5, the preheating heater 4 can be inserted and removed between the upper mold 5 and the lower mold 6 in the mold open state. The preheater 4 preheats the upper mold 5, the lower mold 6 and the intermediate mold 7. Further, as shown in FIG. 6, the pressing cylinder 8 fixes the mold structure 1 so as to press down the gate mold 15 placed on the intermediate mold 7 through the center hole of the upper mold 5. It is provided on the side (for example, a frame or the like).

(2) Action of mold structure Next, the casting action of the mold structure 1 having the above configuration will be described. As shown in FIG. 5, the preheating heater 4 is inserted between the upper mold 5 and the lower mold 6 in the mold open state, and the upper mold 5, the lower mold 6, and the intermediate mold 7 are preheated by the preheating heater 4. . Next, as shown in FIG. 6, the upper die 5 is brought close to the lower die 6, and the cavity C is formed between the floating intermediate die 7 by the upper die 5, the lower die 6 and the flying cylinder 3. . In this state, the gate mold 15 is placed on the intermediate mold 7 through the center hole of the upper mold 5, and the gate mold 15 is pressed against the upper mold 5 by the pressing cylinder 8 to prevent lifting. Next, the cast iron melt is poured into the cavity C using the ladle 11. The pouring temperature is about 1250 to 1300 ° C., and the cast iron melt is filled in the cavity C to be in a semi-solid state.

Thereafter, as shown in FIG. 7, the upper die 5 is brought closer to the lower die 6 against the levitation force of the levitation cylinder 3 at an appropriate timing during the pouring. Then, the intermediate mold 7 moves downward together with the upper mold 5, and the entire cast iron melt in the cavity C is pressurized with a predetermined pressure, whereby a plurality of cast iron products P are obtained. Next, as shown in FIG. 8, the pressing of the gate mold 15 by the pressing cylinder 8 is released, and then the upper mold 5 is separated from the lower mold 6 to open the mold and the cast iron attached to the upper mold 5. Remove product P. When the upper mold 5 and the lower mold 6 are in the mold open state, the intermediate mold 7 is lifted again by the action of the floating cylinder 3. Thereafter, the above operation is repeated and the cast iron product P is mass-produced.

(3) Effects of the Embodiment As described above, according to the mold structure 1 of the present embodiment, the cavity C formed by the intermediate mold 7 that is floated by the upper mold 5, the lower mold 6 and the floating cylinder 3. The cast iron melt is poured, and the upper mold 5 and the lower mold 6 are brought close to each other against the lifting force of the floating cylinder 3 during the pouring, and the cast iron melt in the cavity C is moved downward as the intermediate mold 7 moves downward. The whole is pressurized. Due to the rapid cooling effect of the cast iron melt by this pressurization, when casting high-temperature cast iron, the inner nest of the cast iron product is crushed into a dense and uniform structure, and high strength can be achieved. Also, compared to the conventional case where the cast iron melt in the cavity is partially pressurized using a pressure pin, the entire cast iron melt in the cavity is pressurized, so there is no defect and high strength cast iron. The product P can be stably mass-produced. In particular, in this embodiment, the upper die 5 and the lower die 6 are brought close to each other against the levitation force of the levitation cylinder 3 and the intermediate die 7 is moved in the vertical direction so that the molten cast iron in the cavity C is heated to 4.5 MPa. Since pressurization is performed with pressure, a high-quality cast iron product P can be obtained with extremely small pressure. In contrast, aluminum die casting usually requires a large pressure of 30 to 200 MPa, and even what is called hot chamber die casting usually requires a pressure of 7 to 40 MPa.

  In this embodiment, the intermediate die 7 is fitted to the nested die 6b of the lower die 6 so as to be movable in the vertical direction, and the interval s2 is about 0.2 mm at the fitting portion between the intermediate die 7 and the nested die 6b. Since the degassing gap 25 is formed, the surface properties of the cast iron product P can be improved by the degassing effect while suitably absorbing the thermal expansion of the mold. Moreover, the fitting property of the intermediate mold 7 with respect to the lower mold 6 can be improved. Further, the generation of burrs can be suppressed.

  Further, in this embodiment, the inner divided mold 12 and the outer divided mold 13 constituting the lower mold 6 are fitted in the vertical direction, and the interval s1 is approximately between the fitting portions of the inner and outer divided molds 12 and 13. Since the 0.2 mm degassing gap 24 is formed, the surface properties of the cast iron product P can be improved by the degassing effect while suitably absorbing the thermal expansion of the mold. Moreover, the fitting property of each division type | mold 12 and 13 can be improved. Further, the generation of burrs can be suppressed.

  Further, in this embodiment, since the fitting portion of the intermediate die 7 with the nested die 6b is formed in a step shape, the fitting surface area between the intermediate die 7 and the nested die 6b is minimized and the generation of burrs is further reduced. It can be reliably suppressed.

  Further, in this example, since the pouring temperature was set to about 1250 to 1300 ° C. and the spheroidal graphite cast iron melt was poured into the cavity C, the cast iron melt was filled into the cavity C to be in a semi-solidified state. Further strengthening of the cast iron product P can be achieved.

  Further, in this embodiment, since the main die 6a and the outer split die 13 constituting the upper die 5, the intermediate die 7, and the lower die 6 are made of hot tool steel, the heat resistance and rigidity of the entire mold structure are improved. Can be improved. Moreover, since the inner split mold 12 constituting the lower mold 6 is made of copper alloy, the rapid cooling effect of the cast iron melt can be further improved.

  Further, in this embodiment, since the preheating heater 4 for preheating the upper die 5, the lower die 6 and the intermediate die 7 is further provided, the hot water runnability during pouring is improved, and the tensile strength of the resulting cast iron product P is increased. The thickness and elongation can be improved.

  Furthermore, in the present embodiment, since the pouring cylinder 8 is further provided for pressing downward the pouring die 15 placed on the intermediate die 7 through the center hole of the upper die 5, the pouring die 15 at the time of pouring is provided. Can be prevented from lifting.

  In the present invention, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention depending on the purpose and application. That is, in the above embodiment, for example, as shown in FIG. 9, the lower mold 6 is provided with a guide pin 17 extending in the vertical direction, and the intermediate mold 7 is provided with a guide hole 18 for guiding the guide pin 17 in the vertical direction. May be. Thereby, when the intermediate mold 7 moves in the vertical direction with respect to the lower mold 6, the guide pin 17 is guided to the guide hole 18, and the positioning accuracy of the intermediate mold 7 in the planar direction can be improved. In particular, in the present embodiment, since the guide pin 17 and the guide hole 18 are disposed outside the cavity C in plan view of the intermediate mold 7, the thermal expansion of the intermediate mold 7 can be more reliably suppressed.

  In the above embodiment, for example, as shown in FIG. 10, the gap 25 formed between the intermediate mold 7 and the lower mold 6 is replaced with a first gap 25 a disposed near the gate 30 and the first gap 25 a. You may make it comprise and comprise the 2nd clearance gap 25b which continues to the 1st clearance gap 25a and has a clearance gap larger than the 1st clearance gap 25a. Accordingly, the first gap 25a is arranged on the upstream side of the hot water passage, and the second gap 25b is arranged on the downstream side of the hot water passage, so that the first gap 25a causes the burring of the relatively high-temperature cast iron melt. While being reliably suppressed, the surface property of the cast iron product and the fitting property of the intermediate die 7 can be further improved by the second gap 25b. In the same manner as the gap 25, a gap 24 formed between the split molds 12 and 13 is a first gap and a second gap that is continuous with the first gap and has a gap gap larger than the first gap. And a gap.

  In the above embodiment, the molten cast iron is poured so as to be in a semi-solid state in the cavity C. However, the present invention is not limited to this. For example, the molten cast iron is in a liquid phase in the cavity C. You may make it pour hot water.

  In the above embodiment, the levitation cylinder 7 is used as the levitation means for levitation of the intermediate mold 7. However, the levitation cylinder 7 is not limited to this. For example, the levitation means is interposed between the intermediate mold 7 and the lower mold 6. A mounted spring or the like can also be employed.

  In the above embodiment, the intermediate mold 7 is moved downward by the flying height s3 when the inside of the cavity C is pressurized. However, the present invention is not limited to this. For example, when the inside of the cavity C is pressurized, the intermediate mold 7 is moved. 7 may be moved downward by an interval smaller than the flying height s3.

  Moreover, in the said Example, when pressurizing the cast iron melt in the cavity C, you may make it further provide the pressurization mechanism which pressurizes the gate of the gate type 15.

Furthermore, in the said Example, the form which made the upper mold | type 5 movable and the lower mold | type 6 fixed was illustrated . As a reference example , for example, the upper mold may be a fixed mold and the lower mold may be a movable mold, or the upper mold and the lower mold may be movable molds.

Furthermore, in the said Example, the metal mold | die structure for casting cast iron was illustrated . As a reference example , for example, a mold structure for casting a copper alloy, a titanium alloy, or the like may be used.

  The foregoing examples are for illustrative purposes only and are not to be construed as limiting the invention. Although the invention has been described with reference to exemplary embodiments, it is to be understood that the language used in the description and illustration of the invention is illustrative and exemplary rather than limiting. As detailed herein, changes may be made in its form within the scope of the appended claims without departing from the scope or spirit of the invention. Although specific structures, materials and examples have been referred to in the detailed description of the invention herein, it is not intended to limit the invention to the disclosure herein, but rather, the invention is claimed. It covers all functionally equivalent structures, methods and uses within the scope.

  The present invention is not limited to the embodiments described in detail above, and various modifications or changes can be made within the scope of the claims of the present invention.

  Widely used as a technology related to cast iron casting. In particular, it is suitably used as semi-solid cast iron casting.

  DESCRIPTION OF SYMBOLS 1; Mold structure, 3; Cylinder for levitation | floating, 5; Upper mold | type, 6: Lower mold | type, 7: Intermediate mold | type, 17; Guide pin, 18;

Claims (3)

A cavity is formed between the lower mold that is a fixed mold, the upper mold that is a movable mold that can move toward and away from the lower mold, and the upper mold and the lower mold. A mold structure comprising an intermediate mold that is movable in the vertical direction with respect to the lower mold so as to pressurize the molten cast iron to be hot water, and a floating means for levitating the intermediate mold with respect to the lower mold A cast iron casting method using
The upper mold is brought close to the lower mold during pouring of the molten cast iron into the cavity, and the intermediate mold is moved downward with the upper mold in contact with the intermediate mold. A cast iron casting method characterized by pressurizing the molten iron inside . The intermediate mold is fitted to the lower mold so as to be movable in the vertical direction,
A gap for degassing is formed at the fitting part between the intermediate mold and the lower mold, and the gap (s2) is 0.1 to 0.4 mm.
The said clearance gap has the 1st clearance gap distribute | arranged to the vicinity of the gate, and the 2nd clearance gap which is distribute | arranged far from the said entrance gap from the said 1st clearance gap, and has a clearance gap larger than the said 1st clearance gap. Cast iron casting method . Said one type of the lower mold and the intermediate mold is provided a guide pin extending in the vertical direction, the other type to the guide pin in the vertical direction to the guide claim guide hole is provided for one or cast iron casting method described in 2.

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