MOLD PREHEATING SYSTEM AND MOLD PREHEATING DEVICE

A mold preheating system includes a casting mold for obtaining a cast metal product by supplying molten metal to a cavity formed by an upper mold and a lower mold, a melting furnace provided below the lower mold, a molten metal supply path through which molten metal in the melting furnace is supplied to the cavity, and a mold preheating device configured to preheat the casting mold. A raised part that forms a product shape is formed in the upper mold, and a recessed part in which the raised part is housed is formed in the lower mold. The mold preheating device includes an upper-mold preheating burner that is disposed along an outer peripheral wall of the raised part and preheats the outer peripheral wall, and a lower-mold preheating burner that is disposed inside the recessed part and preheats a sidewall and a bottom wall of the recessed part.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of foreign priority to Japanese Patent Application No. 2023-020166, filed on Feb. 13, 2023, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a mold preheating system and a mold preheating device.

BACKGROUND

A conventionally disclosed mold preheating system has a structure in which an electrothermal heater configured to preheat a mold internal space is inserted into a sprue from the mold internal space (see Japanese Patent No. 5555078, for example).

In a known configuration, a sleeve is inserted into the intermediate stalk and air heated by a burner is sent into the intermediate stalk from one end of the sleeve (see Japanese Patent No. 5359718, for example).

SUMMARY

In a conventional mold preheating system, when supplied into a cavity, molten metal is cooled and solidified in a case where the temperature of a mold is low as compared to that of the molten metal, which leads to product yield degradation, molding quality degradation, deformation due to demolding defect, and the like. Thus, each mold component needs to be sufficiently preheated before casting.

However, in a case where each mold component cannot be sufficiently preheated by using heated air of an electrothermal heater or a burner, what is called a waste molding method of preheating a mold by using the temperature of molten metal is applied. A cast product manufactured by waste molding in this manner has low quality and is discarded or recycled. Accordingly, a time needed for waste molding increases and manufacturing efficiency decreases, and thus there has been room for further modification.

The present invention is intended to provide a mold preheating system and a mold preheating device that are capable of finishing a preheating process in a short time without waste molding.

To solve the problem, a mold preheating system of the present invention includes a casting mold for obtaining a cast metal product by supplying molten metal to a cavity formed by an upper mold and a lower mold, a melting furnace provided below the lower mold, a molten metal supply path through which molten metal in the melting furnace is supplied to the cavity, and a mold preheating device configured to preheat the casting mold. A raised part that forms a product shape is formed in the upper mold, and a recessed part in which the raised part is housed is formed in the lower mold. The mold preheating device includes an upper-mold preheating burner that is disposed along an outer peripheral wall of the raised part and preheats the outer peripheral wall, and a lower-mold preheating burner that is disposed inside the recessed part and preheats a sidewall and a bottom wall of the recessed part.

DETAILED DESCRIPTION

Embodiment

An embodiment of the present invention will be described below with reference to the accompanying drawings as appropriate. Identical constituent components are denoted by the same reference sign, and duplicate description thereof is omitted. In the description, identical elements are denoted by the same number, and duplicate description thereof is omitted. For the purpose of description of directions, directions shown with arrows inFIG.1are referred to as “upper, lower, right, and left directions”, the near side of the sheet ofFIG.1is referred to as “front direction”, and the far side of the sheet is referred to as “back direction”.

FIG.1shows the disposition relation between a casting mold1and a mold preheating device10in a mold preheating system100according to the embodiment in which the present invention is applied.

Mold Preheating System

The mold preheating system100includes the casting mold1for obtaining a cast metal product by supplying molten metal to a cavity2as a hollow space formed of an upper mold3and a lower mold4. The casting mold1includes an opening-closing mechanism (not shown) configured to change the interval between the lower mold4and the upper mold3in the upper-lower directions by moving the upper mold3in the upper-lower directions.

The opening-closing mechanism changes a mold-opened state in which the upper mold3is separated upward from the lower mold4to a mold-clamped state in which the upper mold3is moved downward and in contact with the lower mold4.

Then, molten metal supplied from a melting furnace5provided below the lower mold4is poured into the cavity2through a molten metal supply path6, and low-pressure casting is performed.

The opening-closing mechanism moves the upper mold3upward to achieve the mold-opened state. Then, a cast metal product is taken out from between the upper mold3and the lower mold4of the casting mold1. The casting mold1may be provided with a temperature sensor and detected mold temperature may be reflected on a preheating condition of a preheating process to be described later.

A raised part3athat forms the product shape of the cast metal product is provided as an extension to the upper mold3of the casting mold1. The raised part3aaccording to the embodiment has a square pyramid trapezoid shape in which outer peripheral walls3beach having a substantially flat plate shape are provided on four sides and that is tilted and tapered inward toward downward.

A recess part3gas part of the upper shape of the cast metal product is formed at a lower end surface3fof the raised part3aand has a recessed shape that is recessed upward from a bottom surface. In addition, a plurality of stud pins3hare provided around the recess part3gas downward extensions to form fastening holes used for stud bolts for fastening components.

A slide mold part7that is horizontally movable in a side-opening direction is further provided at the lower mold4of the casting mold1. The slide mold part7is provided to be movable closer and away by sliding relative to the center of the cavity2in the horizontal direction. In the mold-clamped state, the slide mold part7forms the internal space of the cavity2and shapes recessed and raised shapes of the side surface of the cast metal product. In the mold-opened state, the slide mold part7slides outward and at least one side surface thereof is opened so that the cast metal product can be easily taken out.

A recessed part4ais formed at the slide mold part7of the lower mold4. The recessed part4ahas an upward opening at an upper part and is tilted inward toward downward. When the upper mold3is moved down from the mold-opened state, the raised part3ais housed in the recessed part4aand the casting mold1is blocked in the upper-lower directions.

Sidewalls4band a bottom wall4care provided at a lower part of the recessed part4a. The sidewalls4bare provided in parallel and separated with a space interposed therebetween, and the internal space of the cavity2is formed by the sidewalls4b, the bottom wall4c, and the lower end surface3fof the upper mold3in the mold-clamped state.

A plurality of sprues14are formed at the bottom wall4cof the lower mold4. The sprues14are formed at four positions with substantially equal intervals along an inner peripheral wall15aof an intermediate stalk15when viewed from top, and communicate with the melting furnace5, which is disposed below the lower mold4, through the molten metal supply path6.

The melting furnace5feeds molten metal of metallic material upward at low speed under relatively low pressure into the cavity2through the molten metal supply path6provided between the melting furnace5and the casting mold1. The molten metal supply path6includes the intermediate stalk15having a tubular shape. The upper end surface of the intermediate stalk15is connected to the lower surface of the bottom wall4cof the lower mold4.

The molten metal pushed upward from the melting furnace5through the intermediate stalk15is distributed into the four sprues14and fed into the cavity2. The molten metal poured into the cavity2is cured into a cast product due to heat release from the molds.

Mold Preheating Device

As shown inFIG.2, the mold preheating system100includes the mold preheating device10configured to preheat the casting mold1. Before low-pressure casting is performed, the mold preheating device10is interposed between the upper mold3and the lower mold4in the mold-opened state and preheats the casting mold1to a desired temperature by ejecting flame from a plurality of burner chips.

The mold preheating device10according to the embodiment includes upper-mold preheating burners11that are disposed along the outer peripheral walls3bof the raised part3aand preheat the outer peripheral walls3b. The mold preheating device10also includes a lower-mold preheating burner12that is disposed inside the recessed part4aand preheats the sidewalls4band the bottom wall4cof the recessed part4a, and intermediate-stalk preheating burners13.

As shown inFIGS.3and4, the mold preheating system100includes a mixture supply device20configured to supply mixture of air and gas (hereinafter also referred to as mixture). The mixture supply device20is connected to the upper-mold preheating burners11and the lower-mold preheating burner12and supplies the mixture to each burner chip.

The mixture supply device20according to the embodiment is connected to a pipe bifurcation part23through a mold pipe22. The pipe bifurcation part23has connection openings communicating with one another on four sides, the upper connection opening being connected to the mold pipe22, the right and left connection openings being connected to upper-mold pipes11c, the lower connection opening being connected to a lower mold pipe25.

The pipe bifurcation part23distributes, to the upper-mold pipes11cand the lower mold pipe25, the mixture transferred from the mixture supply device20through the mold pipe22. The distributed mixture is supplied to the upper-mold preheating burners11and the lower-mold preheating burner12.

The upper-mold preheating burners11include the upper-mold pipes11c(seeFIG.2) surrounding the outer peripheral walls3b(seeFIG.1) formed at the raised part3aof the upper mold3.

The upper-mold pipes11chave a substantially U shape when viewed from top and are disposed to surround at least three of the plurality of outer peripheral walls3bformed at the raised part3aof the upper mold3. The upper-mold pipes11cin the present example have the U shape but are not limited thereto and may have, for example, a square shape.

The upper-mold pipes11caccording to the embodiment include two straight pipes11fdisposed in parallel to the right and left outer peripheral walls3bof the raised part3aat predetermined intervals.

The upper mold3is preheated by flame ejected from a plurality of upper-mold preheating burner chips.

Each upper-mold pipe11cis provided with first lined burner chips11a, second lined burner chips11b, a front-side burner chip11d, and a back-side burner chip11ethat eject flame as upper-mold preheating burner chips. The front-side burner chips11dand the back-side burner chips11eare omitted in a perspective view inFIG.4.

Although the first lined burner chips11aand the other burner chips are disposed toward four surfaces, the present invention is not limited thereto. For example, flame may be ejected toward two surfaces or three surfaces, and flame only needs to be ejected toward at least two surfaces.

The upper-mold preheating burners11eject flame from the upper-mold preheating burner chips toward mainly the lower end surface3fand the outer peripheral walls3bof the raised part3a. Accordingly, the upper-mold preheating burners11can efficiently and substantially uniformly preheat the four surfaces of the lower end surface3fand the outer peripheral walls3bof the raised part3aof the upper mold3, which is difficult to preheat in the cavity2.

First Lined Burner Chip

Specifically, the pair of left and right straight pipes11fare disposed obliquely below the left and right outer peripheral walls3b. A plurality of extension pipes are provided as extensions on the outer surface of each straight pipe11fat equal intervals in the pipe length direction. Each extension pipe has a substantially L shape in a side view and has an obliquely upward leading end at which a first lined burner chip11ais mounted. The first lined burner chips11aare disposed such that their leading ends are equally spaced from facing corners3d.

With the above-described configuration, the first lined burner chips11aeject flame obliquely upward from below toward the lower end surface3f(seeFIG.1) of the raised part3aformed at the upper mold3. Accordingly, mainly the corners3dand part of the lower end surface3fand the outer peripheral walls3badjacent to the corners3dare equally heated.

Second Lined Burner Chip

As shown inFIG.3, the plurality of second lined burner chips11bare disposed on the outer surface of each straight pipe11f. The second lined burner chips11bare each provided as an extension above the middle position between the first lined burner chips11adisposed adjacent to each other and are alternately positioned with the first lined burner chips11ain the pipe length direction.

The leading ends of the second lined burner chips11bare disposed obliquely below the outer peripheral walls3bof the raised part3ashown inFIG.1at equal distances.

The leading ends of the second lined burner chips11bare directed obliquely upward. The second lined burner chips11beject flame obliquely upward toward the outer peripheral walls3bof the raised part3aof the upper mold3and a recessed corner part3epositioned between a lower surface3cof the upper mold3and each outer peripheral wall3b. Accordingly, mainly the outer peripheral walls3bof the upper mold3to part of the lower surface3cadjacent to the recessed corner parts3eare heated.

In this manner, flame from the plurality of second lined burner chips11bis ejected obliquely upward from below to uniformly heat a wide range that is oblique relative to the outer peripheral walls3b.

The corners3dare positioned between flame ejected from the first lined burner chips11aand flame ejected from the second lined burner chips11b. Accordingly, the efficiency of preheating the corners3dis excellent and a desired temperature can be reached at an early timing.

Each recessed corner part3epositioned between the corresponding outer peripheral wall3band the lower surface3cof the upper mold3is typically difficult to preheat with flame ejected in a direction orthogonal to the lower surface3cor the outer peripheral wall3bbecause temperature partially increases.

However, in the mold preheating device10according to the embodiment, each recessed corner part3epositioned between the lower surface3cand the corresponding outer peripheral wall3bis included in the range of flame obliquely toward the recessed corner part3e. Accordingly, heating efficiency is excellent at the recessed corner part3elike the outer peripheral wall3b.

Front-Side and Back-Side Burner Chips

As shown inFIG.3, each upper-mold preheating burner11according to the embodiment also includes the front-side burner chip11dand the back-side burner chip11e.

The front-side burner chip11dand the back-side burner chip11eare mounted at the leading ends of extension pipes11gextended from each of the two straight pipes11fof the upper-mold pipes11c(seeFIGS.6and7).

The extension pipes11gare extended in Z bending shapes from the outer surface of the straight pipe11fin the vicinities of the front and rear ends, respectively, of the straight pipe11f.

Accordingly, the front-side burner chip11dor the back-side burner chip11eis fixed to an angle at which flame is ejected obliquely upward from below. The ejected flame can directly heat a wide range of front-side and back-side outer peripheral walls (not shown) orthogonal to the outer peripheral walls3bof the raised part3awithout contacting the upper mold3.

Accordingly, the front-side and back-side outer peripheral walls of the raised part3aare preheated to a uniform temperature equivalent to those of the left and right outer peripheral walls3bat an early timing.

The lower-mold preheating burner12includes a burner chip assembly12adisposed inside the recessed part4ashown inFIG.1at preheating, and the lower mold pipe25having a base end part25bconnected to the lower connection opening of the pipe bifurcation part23(seeFIG.4).

The lower mold pipe25has a crank shape bifurcated downward from the pipe bifurcation part23, horizontally extended to a middle position in the lower mold4, and having a leading end part bent downward. The burner chip assembly12ais connected to a leading end part25aof the lower mold pipe25.

Mixture of air and gas supplied from the mixture supply device20through the mold pipe22is supplied into the burner chip assembly12athrough the lower mold pipe25.

As shown inFIG.4, the burner chip assembly12ahas a rectangular parallelepiped shape and includes a plurality of burner chips densely disposed on left and right side surfaces (seeFIG.6). The burner chips eject flame outward to left and right.

The lower mold4is positioned directly above the intermediate stalk15and its temperature is increased by flame from the intermediate-stalk preheating burners13. Thus, the burner chip assembly12aaccording to the embodiment is inserted to a central position of the relatively large internal space of the cavity2and disposed away from each sidewall4b. Accordingly, preheating temperature of the entire cavity2can be uniformized by adjusting heating power used for preheating of the lower mold4.

As shown inFIG.7, a plurality of extension pipes12bare provided as extensions from the burner chip assembly12a. A single lower-mold preheating burner chip12cis mounted at the leading end of each extension pipe12b. The extension pipe12bis bent such that the direction of flame ejected from the lower-mold preheating burner chip12chas a predetermined tilt angle relative to the corresponding sidewall4bor the bottom wall4cin the cavity2.

As shown inFIG.4, the mold preheating device10further includes the intermediate- stalk preheating burners13inserted into the intermediate stalk15through the plurality of sprues14, respectively.

The intermediate-stalk preheating burners13are connected to the mixture supply device20(seeFIG.3) through an intermediate-stalk pipe24. The intermediate-stalk pipe24is extended to downward chip mounting pipes28through an intermediate-stalk pipe connection part26. In other words, the intermediate-stalk pipe24has a path different from the mold pipe22.

As shown inFIG.5, lower parts of the chip mounting pipes28are inserted to a middle position of the intermediate stalk15. A plurality of supply path burner chips27are mounted at the lower part of each chip mounting pipe28. The plurality of supply path burner chips27each eject flame along the inner peripheral wall15aof the intermediate stalk15(seeFIG.8). Accordingly, the intermediate stalk15provided in the molten metal supply path6is efficiently preheated.

Specifically, the intermediate-stalk preheating burners13include the intermediate-stalk pipe24bent toward below the upper-mold preheating burners11. The intermediate-stalk pipe24is connected to the intermediate-stalk pipe connection part26that is bifurcated into two in parallel to the straight pipes11fof the upper-mold preheating burners11below the outer peripheral walls3bpositioned on the left and right sides of the raised part3a.

Lower parts of the intermediate-stalk preheating burners13as the intermediate-stalk pipe connection part26further extended downward and bent in L shapes are each further bifurcated into two chip mounting pipes28, and accordingly, a total of four chip mounting pipes28are extended downward.

Each chip mounting pipe28includes the plurality of supply path burner chips27. Three supply path burner chips27are provided as extensions in the pipe axial direction from the outer surface of the lower part of the chip mounting pipe28. The number of burner chips may be set as appropriate and is not limited.

As shown inFIG.5, at preheating, the chip mounting pipes28are inserted into the intermediate stalk15from the cavity2through the sprues14. The supply path burner chips27are disposed away from the inner peripheral wall15aat the middle position of the intermediate stalk15in the upper-lower directions.

As shown inFIG.7, the supply path burner chips27are mounted on the outer surface of each chip mounting pipe28at different angles spaced from each other by 90° approximately with their leading ends aligned in the same circumferential direction. In other words, the supply path burner chips27are disposed to eject flame in a direction intersecting the radial direction of the intermediate stalk15.

Typically, the inner peripheral wall15ais locally heated and potentially damaged when flame from the supply path burner chips27is ejected in a direction orthogonal to the inner peripheral wall15a.

The intermediate-stalk preheating burners13of the mold preheating device10according to the embodiment are inserted into the intermediate stalk15through the plurality of sprues14and preheat the intermediate stalk15by ejecting flame along the inner peripheral wall15aof the intermediate stalk15as shown with arrows inFIG.7.

Accordingly, the direction of flame can be rotated in the circumferential direction to perform heating without unevenness.

The intermediate-stalk preheating burners13may be inserted into the intermediate stalk15except for at least one of the plurality of sprues14. For example, three chip mounting pipes28may be inserted into respective sprues14at three places among the sprues14formed at four places as shown inFIG.8, but no chip mounting pipe28may be inserted into the remaining sprue14at one place.

In this case, a sufficient amount of air for combusting mixture can be supplied by using, as a vent, the sprue14into which no intermediate-stalk preheating burner13is inserted. Accordingly, flame from the intermediate-stalk preheating burners13does not misfire and preheating can be stably performed.

The mold preheating system100according to the embodiment further includes a positioning device30shown with phantom lines inFIG.6.

The positioning device30includes a mount31placed on the lower mold4(seeFIG.3). The mount31includes front, back, right, and left frames32and33connected to one another in a substantially rectangular frame shape in a plan view, and a plurality (in the present embodiment, three) of cylindrical parts34provided as upward extensions from parts where the frames32and33perpendicularly intersect.

The positioning device30also includes an upper-mold preheating burner positioning part40that positions the upper-mold preheating burners11on the mount31, and a lower-mold preheating burner positioning part50that positions the lower-mold preheating burner12. The positioning device30also includes an intermediate-stalk preheating burner positioning part60that positions the intermediate-stalk preheating burners13.

The upper-mold preheating burners11and the lower-mold preheating burner12are positioned and held in the space between the upper mold3and the lower mold4by the upper-mold preheating burner positioning part40and the lower-mold preheating burner positioning part50. The supply path burner chips27of the intermediate-stalk preheating burners13are positioned and held at the middle position in the intermediate stalk15by the intermediate-stalk preheating burner positioning part60.

Accordingly, in the preheating process, each burner chip is disposed at a desired interval and angle with favorable preheating efficiency relative to the upper mold3and the lower mold4. The upper mold3and the lower mold4are held at an appropriate interval by the cylindrical parts34.

In the preheating process in which the intermediate-stalk pipe connection part26is positioned by the positioning device30shown inFIG.6, two parts into which the intermediate-stalk pipe connection part26is bifurcated on the lower side are offset downward relative to the position of the burner chip assembly12aof the lower-mold preheating burner12in the upper-lower directions.

Accordingly, flame ejected to sides from the burner chip assembly12aachieves sufficient efficiency of preheating toward the sidewalls4bof the lower mold4while avoiding the two bifurcated parts and the chip mounting pipes28.

As described above, the mold preheating system100according to the embodiment includes the casting mold1for obtaining a cast metal product by supplying molten metal to the cavity2formed by the upper mold3and the lower mold4, the melting furnace5provided below the lower mold4, the molten metal supply path6through which molten metal in the melting furnace5is supplied to the cavity2, and the mold preheating device10configured to preheat the casting mold1.

The raised part3athat forms a product shape is formed in the upper mold3, and the recessed part4ain which the raised part3ais housed is formed in the lower mold4.

The mold preheating device10includes the upper-mold preheating burners11that are disposed along the outer peripheral walls3bof the raised part3aand preheat the outer peripheral walls3b, and the lower-mold preheating burner12that is disposed inside the recessed part4aand preheats the sidewalls4band the bottom wall4cof the recessed part4a.

The mold preheating system100according to the embodiment thus configured has improved heat efficiency and can finish the preheating process with reduced energy in a short time.

Specifically, as shown inFIG.1, the upper-mold preheating burners11eject flame toward the outer peripheral walls3bof the raised part3athat is raised from the upper mold3, thereby efficiently preheating the upper mold3in accordance with the shape of the raised part3athat is difficult to preheat in the cavity2.

Accordingly, similarly to the sidewalls4band the bottom wall4cof the lower mold4, which are preheated from the inside of the recessed part4aby the lower-mold preheating burner12, the upper mold3is uniformly preheated and the entire cavity reaches a temperature at which a non-defective cast metal product is obtained at an early timing.

Thus, waste molding is unnecessary, sufficient preheating temperature is provided to the entire cavity2from the beginning of a casting process, and the preheating process can be finished in a short time.

As shown inFIG.3, the upper-mold preheating burners11include the upper-mold pipes11csurrounding the outer peripheral walls3bof the raised part3a. The upper-mold preheating burners11also include the first lined burner chips11athat eject flame from the upper-mold pipes11ctoward the outer peripheral walls3bof the raised part3aand the lower end surface3fof the upper mold3.

In the mold-clamped state, the corners3dof the raised part3aformed at the upper mold3are positioned at corners of an upper surface where the flow speed of molten metal decreases in the cavity2. Accordingly, the upper-mold preheating burners11of the upper-mold pipes11csurrounding the outer peripheral walls3bof the raised part3aeject flame from the first lined burner chips11atoward the corners3dand directly preheat parts at the corners of the upper surface in the cavity2.

Accordingly, in a casting process, the flow speed of molten metal does not decrease at the corners of the upper surface, and molten metal can smoothly and thoroughly reach the corners in the cavity2.

The upper-mold pipes11care disposed to surround the outer peripheral walls3bof the raised part3a. Accordingly, the upper-mold preheating burners11do not interfere with the raised part3awhen the upper mold3is moved down to the same height position as the upper-mold pipes11cin the direction toward the lower mold4.

Thus, the first lined burner chips11aand the other burner chips can be disposed close to the raised part3ato eject flame toward a central part of the upper mold3. Moreover, in the preheating process, the interval between the upper mold3and the lower mold4can be narrowed as compared to a configuration in which the upper-mold pipes11care positioned directly below the raised part3a.

Accordingly, the heat amount of flame that escape to the outside through the gap between the upper mold3and the lower mold4can be reduced and preheating efficiency can be further improved.

In the embodiment, the pair of left and right straight pipes11fprovided to the upper- mold preheating burners11are disposed obliquely below, in parallel to, and around the pair of respective outer peripheral walls3boppositely positioned on the left and right sides of the raised part3a.

The plurality of first lined burner chips11aprovided at each straight pipe11feject flame toward the corners3deach positioned between the corresponding outer peripheral wall3band the lower end surface3fof the raised part3a. In addition, the second lined burner chips11beject flame toward the recessed corner part3epositioned between the lower surface3cand the outer peripheral wall3bof the upper mold3.

Accordingly, as shown inFIG.1, in the raised part3a, the range of the lower end surface3fto the corners3d, the outer peripheral walls3b, the recessed corner parts3e, and the lower surface3cof the upper mold3is uniformly preheated around the corners3d.

More specifically, the plurality of first lined burner chips11aaccording to the embodiment eject flame obliquely upward from below, thereby uniformly heating a wide range obliquely toward the lower end surface3fin the opposite directions from left and right. For example, parts such as the corners3deach positioned between the lower end surface3fand the corresponding outer peripheral wall3bare unlikely to be heated by flame that directly heats the lower end surface3for the outer peripheral walls3b.

However, with the mold preheating device10according to the embodiment, the lower end surface3fcan be included in a range in which heating efficiency is favorable similarly to the corners3d, and can be heated with flame toward the corners3deach positioned between the lower end surface3fand the corresponding outer peripheral wall3b, and thus preheating efficiency is excellent.

Flame from the plurality of second lined burner chips11balternately arrayed with the first lined burner chips11ais ejected obliquely upward from below, thereby uniformly heating a wide range obliquely toward the outer peripheral walls3b. For example, parts such as the recessed corner parts3eeach positioned between the corresponding outer peripheral wall3band the lower surface3cof the upper mold3are typically unlikely to be heated with flame ejected in a direction orthogonal to the lower surface3cor the outer peripheral walls3b.

However, with the second lined burner chips11b, the recessed corner parts3ecan be included in a range in which heating efficiency is favorable with flame obliquely toward the recessed corner parts3eeach positioned between the lower surface3cand the corresponding outer peripheral wall3b. Accordingly, similarly to the outer peripheral walls3b, the recessed corner parts3ecan be uniformly heated to improve preheating efficiency.

As shown inFIG.3, each upper-mold preheating burner11according to the embodiment includes the front-side burner chip11dand the back-side burner chip11e.

The front-side burner chip11dand the back-side burner chip11eare mounted at the leading ends of each of the extension pipes11gextended from the two straight pipes11fof the upper-mold pipes11c(seeFIGS.6and7).

The extension pipes11gare extended in Z bending shapes from the outer surface of the straight pipe11fin the vicinities of the front and rear ends, respectively, of the straight pipe11f.

Accordingly, the front-side burner chip11dor the back-side burner chip11eis fixed to an angle at which flame is ejected obliquely upward from below. The ejected flame can directly heat a wide range of front-side and back-side outer peripheral walls (not shown) orthogonal to the outer peripheral walls3bof the raised part3awithout contacting the upper mold3.

Thus, similarly to the pair of left and right outer peripheral walls3bof the raised part3a, the front-side and back-side outer peripheral walls are preheated at excellent efficiency and the preheating process can be finished in a short time.

Thus, in the cavity2of the casting mold1clamped in a casting process, sufficient preheating temperature is entirely and uniformly provided to four sides positioned at the corners of the upper surface as well as corners between adjacent sides from the beginning, and the first casting can be started in a short time.

As shown inFIG.8, the lower mold4includes the plurality of sprues14communicating with the molten metal supply path6.

As shown inFIG.5, the molten metal supply path6includes the intermediate stalk15through which molten metal is distributed to the plurality of sprues14.

The mold preheating device10further includes the intermediate-stalk preheating burners13inserted into the intermediate stalk15through the plurality of sprues14. As shown inFIG.8, the intermediate-stalk preheating burners13eject flame along the inner peripheral wall15aof the intermediate stalk15.

Flame ejected at an angle from the intermediate-stalk preheating burners13instead of directly toward the inner peripheral wall15aflows in a vortex along the annular inner peripheral wall15aand uniformly heats the inner peripheral wall15a. Thus, the inner peripheral wall15ais equally preheated with flame from the plurality of intermediate-stalk preheating burners13, and molten metal can smoothly pass through the intermediate stalk15at an early timing.

In the embodiment, the sprues14are disposed at four places in an annular shape. However, the present invention is not limited thereto, and the number and disposition thereof may be determined such that the sprues14are disposed at a single place or a plurality of places, other than four places, in a lattice shape, in a honeycomb shape, or at random.

The intermediate-stalk preheating burners13may be inserted into the intermediate stalk15except for at least one of the plurality of sprues14.

A sufficient amount of air can be supplied through ventilation by using, as a vent, a sprue14into which no intermediate-stalk preheating burner13is inserted, and flame from the intermediate-stalk preheating burners13can be stably ejected without misfire.

The mold preheating system100includes the mixture supply device20configured to supply mixture of air and gas, and the mold pipe22through which the mixture is supplied from the mixture supply device20to the upper-mold preheating burners11and the lower-mold preheating burner12. The mold preheating system100further includes the intermediate-stalk pipe24through which the mixture is supplied from the mixture supply device20to the intermediate-stalk preheating burner13shown inFIG.4.

The intermediate-stalk pipe24has a path different from the mold pipe22.

The intermediate-stalk pipe24through which the mixture of air and gas is supplied to the intermediate-stalk preheating burners13has a path different from the mold pipe22.

Thus, the amount of supply from the mixture supply device20can be easily differentiated. The preheating temperature of the intermediate stalk15can be maintained in a high temperature state by independently increasing the amount of mixture supplied to the intermediate-stalk preheating burners13and the amount of mixture supplied to the mold pipe22.

Specifically, the intermediate stalk15in which molten metal is temporarily accumulated for distribution to the plurality of sprues14needs to be constantly preheated to a high temperature state otherwise the molten metal is cooled and solidified. In such a case, the molten metal supply path6or the sprues14are clogged and blocked and a casting process cannot be performed.

In the mold preheating system100according to the embodiment, desired mixture is supplied to the intermediate-stalk preheating burners13through the intermediate-stalk pipe24having a path different from the mold pipe22. Accordingly, preheating temperature needed for passing of molten metal can be reached. Thus, molten metal can smoothly pass inside the intermediate stalk15sufficiently preheated from the beginning of a casting process and can be poured into the cavity2.

Since the intermediate-stalk pipe24has a path different from the mold pipe22, the amount of mixture supply from the mixture supply device20can be easily controlled.

Moreover, in the embodiment, although the same mixture is supplied to the upper-mold preheating burners11and the lower-mold preheating burner12at the same flow rate, the burner chip assembly12adisposed at the center in the lower mold4can adjust the amount of heat in accordance with the number of flames by closing unnecessary chips. The burner chip assembly12acan be densely provided with a plurality of burner chips to reduce preheating unevenness.

Thus, although mixture is supplied to the upper-mold preheating burners11and the lower-mold preheating burner12through the same path by using the pipe bifurcation part23, preheating that is suitable for each component in the cavity2can be performed, and the preheating process can be substantially simultaneously finished in a short time with favorable preheating efficiency in the entire cavity2.

Accordingly, a preheating time can be shortened and the number of pipe components can be reduced to reduce manufacturing cost of the mixture supply device20.

The cavity2of the casting mold1is formed by the upper mold3in which the raised part3ais formed and the lower mold4in which the recessed part4ais formed, the raised part3abeing housed in the recessed part4aand to form a product shape. The mold preheating device10preheats the casting mold1for obtaining a cast metal product by supplying molten metal from the melting furnace5provided below the lower mold4through the molten metal supply path6into the cavity2. The mold preheating device10includes the upper-mold preheating burners11that are disposed along the outer peripheral walls3bof the raised part3aand preheat the outer peripheral walls3b, and the lower-mold preheating burner12that is disposed inside the recessed part4aand preheats the sidewalls4band the bottom wall4cof the recessed part4a.

Accordingly, the mold preheating device10that can finish a preheating process in a short time without waste molding is provided.

Specifically, the upper-mold preheating burners11eject flame toward the outer peripheral walls3bof the raised part3athat is raised from the upper mold3. Thus, preheating can be efficiently performed in accordance with the shape of the raised part3aof the upper mold3even when the shape of the raised part3ais difficult to preheat in the cavity2.

Accordingly, the upper mold3is preheated uniformly with the inner wall of the lower mold4preheated by flame ejected from the lower-mold preheating burner12, and thus the entire cavity2can be preheated to a predetermined temperature.

Thus, waste molding is unnecessary, sufficient preheating temperature is provided to the entire cavity2from the beginning of a casting process, and the preheating process can be finished in a short time.

The lower mold4further includes the plurality of sprues14communicating with the molten metal supply path6. The molten metal supply path6includes the intermediate stalk15through which the molten metal is distributed to the plurality of sprues14. The mold preheating device10further includes the intermediate-stalk preheating burners13inserted into the intermediate stalk15through the plurality of sprues14. The intermediate-stalk preheating burners13eject flame along the inner peripheral wall15aof the intermediate stalk15.

Flame ejected along the inner peripheral wall15aof the intermediate stalk15from the intermediate-stalk preheating burners13inserted into the intermediate stalk15can annularly flow in a vortex along the inner peripheral wall15a. Thus, the inner peripheral wall15aof the intermediate stalk15is equally preheated by flame from the plurality of intermediate-stalk preheating burner13. Accordingly, such a unique effect of the present application is exerted that the preheating process can be finished in a short time and molten metal can smoothly pass inside the intermediate stalk15.

The mold preheating system100according to the embodiment further includes the positioning device30as shown inFIG.3.

As shown inFIG.6or7, the positioning device30supports the upper-mold preheating burners11and improves the positioning accuracy of each of the first lined burner chips11aand the second lined burner chips11b. Accordingly, the positioning device30can accurately dispose each burner chip close to a preheating target site.

Thus, preheating efficiency is excellent as compared to a configuration in which, for example, burner chips are disposed away from wall surfaces without sufficient position accuracy.

Moreover, in the embodiment, since the position accuracy of burner chips is excellent although flame is obliquely upward ejected, preheating can be performed at heating efficiency equivalent to or higher than in a case where flame is closely and vertically directly ejected. Accordingly, the lower end surface3fand the corners3deach positioned between the lower end surface3fand the corresponding outer peripheral wall3bare substantially uniformly preheated to a desired temperature at an early timing by the plurality of first lined burner chips11aon the left and right sides.

In this case, although the recess part3gthat shapes the upper part of a cast metal product exists at the center of the lower end surface3f, flame ejected obliquely from below on the left and right sides by the first lined burner chips11athoroughly reaches the inside of the recess part3gobliquely above, and the recess part3gcan be heated at an early timing like the other part of the lower end surface3f.

The lower-mold preheating burner12is disposed at a desired position inside the recessed part4aand can preheat the sidewalls4band the bottom wall4cof the recessed part4a.

In the embodiment, the dimension between the sidewalls4bfacing each other with the internal space of the cavity2interposed therebetween is formed to be large as compared to that of the recessed part4a, and the burner chip assembly12ais provided at a central position of the internal space.

Thus, flame ejected from a plurality of burner chips concentratively disposed on the side surfaces of the burner chip assembly12ais moderately dispersed, thereby uniformly preheating the sidewalls4b.

As described above, the upper-mold preheating burners11, the lower-mold preheating burner12, and the intermediate-stalk preheating burners13according to the embodiment are disposed in a gap across which the upper mold3is close to the lower mold4, and can preheat each site in the cavity2at an early timing.

Accordingly, when a casting process is started and molten metal in the melting furnace5is supplied into the cavity2through the molten metal supply path6for the first time, the entire cavity2is already uniformly heated to a temperature at which favorable cast metal is obtained.

Thus, waste molding is unnecessary and a cast product can have favorable quality from an early timing. Accordingly, a time necessary for waste molding is eliminated, and a mold preheating system and a mold preheating device with favorable manufacturing efficiency can be provided.

The present invention is not limited to the above-described embodiment but may be modified in various kinds of manners. The above-described embodiment is exemplarily described to facilitate understanding of the present invention and is not necessarily limited to a configuration including all described components. Any component according to one embodiment may be replaced with a component according to another embodiment, and a component according to one embodiment may be added to a component according to another embodiment. Moreover, any component according to each embodiment may be deleted or another component may be added or replaced. Possible modifications of the above-described embodiment are as follows, for example.

In the present embodiment, each upper-mold preheating burner11includes the front-side burner chip11dand the back-side burner chip11eas shown inFIG.3. However, the present invention is not limited thereto, and only one or none of the front-side burner chip11dand the back-side burner chip11emay be provided. Moreover, no slide mold part7may be provided at the lower mold4of the casting mold1.

The mixture supply device20according to the embodiment supplies different mixtures to the mold pipe22and the intermediate-stalk pipe24as different paths, respectively.

The mixture supply device20may supply alone different mixtures to the mold pipe22and the intermediate-stalk pipe24as different paths, respectively. Alternatively, a mixture supply device dedicated to the mold pipe22and a mixture supply device dedicated to the intermediate-stalk pipe24may be configured as separate devices and supply different mixtures, respectively.

The mold preheating system100according to the embodiment includes the positioning device30as shown inFIG.3. However, the present invention is not limited thereto, and the positioning device30does not necessarily need to be provided as long as the upper-mold preheating burners11that preheat the outer peripheral walls3bare disposed along the outer peripheral walls3bof the raised part3a. In other words, the shape, number, and material of the positioning device30are not particularly limited as long as at least the upper-mold preheating burners11are disposed at appropriate positions.