MOLD PREHEATING SYSTEM AND MOLD PREHEATING DEVICE

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.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present invention in any way.

FIG. 1 is a cross-sectional view of a mold preheating system according to an embodiment of the present invention in the vertical direction for description of the entire configuration of a mold.

FIG. 2 is a cross-sectional view of the mold preheating system in the vertical direction for description of the configuration of a mold preheating device.

FIG. 3 is a plan view of the mold preheating device used in the mold preheating system according to the embodiment when viewed from above.

FIG. 4 is a perspective view showing the mold preheating device in a state in which front-side and back-side burner chips are removed for description.

FIG. 5 is a front view showing the configuration of intermediate-stalk preheating burners in the mold preheating device.

FIG. 6 is a side view for description of the entire configuration of the mold preheating device.

FIG. 7 is a front view for description of the entire configuration of the mold preheating device.

FIG. 8 is a top view for description of a situation in which the intermediate-stalk preheating burners of the mold preheating device preheat the inside of an intermediate stalk.

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 in FIG. 1 are referred to as “upper, lower, right, and left directions”, the near side of the sheet of FIG. 1 is referred to as “front direction”, and the far side of the sheet is referred to as “back direction”.

FIG. 1 shows the disposition relation between a casting mold 1 and a mold preheating device 10 in a mold preheating system 100 according to the embodiment in which the present invention is applied.

Mold Preheating System

The mold preheating system 100 includes the casting mold 1 for obtaining a cast metal product by supplying molten metal to a cavity 2 as a hollow space formed of an upper mold 3 and a lower mold 4. The casting mold 1 includes an opening-closing mechanism (not shown) configured to change the interval between the lower mold 4 and the upper mold 3 in the upper-lower directions by moving the upper mold 3 in the upper-lower directions.

The opening-closing mechanism changes a mold-opened state in which the upper mold 3 is separated upward from the lower mold 4 to a mold-clamped state in which the upper mold 3 is moved downward and in contact with the lower mold 4.

Then, molten metal supplied from a melting furnace 5 provided below the lower mold 4 is poured into the cavity 2 through a molten metal supply path 6, and low-pressure casting is performed.

The opening-closing mechanism moves the upper mold 3 upward to achieve the mold-opened state. Then, a cast metal product is taken out from between the upper mold 3 and the lower mold 4 of the casting mold 1. The casting mold 1 may 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 part 3a that forms the product shape of the cast metal product is provided as an extension to the upper mold 3 of the casting mold 1. The raised part 3a according to the embodiment has a square pyramid trapezoid shape in which outer peripheral walls 3b each having a substantially flat plate shape are provided on four sides and that is tilted and tapered inward toward downward.

A recess part 3g as part of the upper shape of the cast metal product is formed at a lower end surface 3f of the raised part 3a and has a recessed shape that is recessed upward from a bottom surface. In addition, a plurality of stud pins 3h are provided around the recess part 3g as downward extensions to form fastening holes used for stud bolts for fastening components.

A slide mold part 7 that is horizontally movable in a side-opening direction is further provided at the lower mold 4 of the casting mold 1. The slide mold part 7 is provided to be movable closer and away by sliding relative to the center of the cavity 2 in the horizontal direction. In the mold-clamped state, the slide mold part 7 forms the internal space of the cavity 2 and shapes recessed and raised shapes of the side surface of the cast metal product. In the mold-opened state, the slide mold part 7 slides outward and at least one side surface thereof is opened so that the cast metal product can be easily taken out.

A recessed part 4a is formed at the slide mold part 7 of the lower mold 4. The recessed part 4a has an upward opening at an upper part and is tilted inward toward downward. When the upper mold 3 is moved down from the mold-opened state, the raised part 3a is housed in the recessed part 4a and the casting mold 1 is blocked in the upper-lower directions.

Sidewalls 4b and a bottom wall 4c are provided at a lower part of the recessed part 4a. The sidewalls 4b are provided in parallel and separated with a space interposed therebetween, and the internal space of the cavity 2 is formed by the sidewalls 4b, the bottom wall 4c, and the lower end surface 3f of the upper mold 3 in the mold-clamped state.

A plurality of sprues 14 are formed at the bottom wall 4c of the lower mold 4. The sprues 14 are formed at four positions with substantially equal intervals along an inner peripheral wall 15a of an intermediate stalk 15 when viewed from top, and communicate with the melting furnace 5, which is disposed below the lower mold 4, through the molten metal supply path 6.

The melting furnace 5 feeds molten metal of metallic material upward at low speed under relatively low pressure into the cavity 2 through the molten metal supply path 6 provided between the melting furnace 5 and the casting mold 1. The molten metal supply path 6 includes the intermediate stalk 15 having a tubular shape. The upper end surface of the intermediate stalk 15 is connected to the lower surface of the bottom wall 4c of the lower mold 4.

The molten metal pushed upward from the melting furnace 5 through the intermediate stalk 15 is distributed into the four sprues 14 and fed into the cavity 2. The molten metal poured into the cavity 2 is cured into a cast product due to heat release from the molds.

Mold Preheating Device

As shown in FIG. 2, the mold preheating system 100 includes the mold preheating device 10 configured to preheat the casting mold 1. Before low-pressure casting is performed, the mold preheating device 10 is interposed between the upper mold 3 and the lower mold 4 in the mold-opened state and preheats the casting mold 1 to a desired temperature by ejecting flame from a plurality of burner chips.

The mold preheating device 10 according to the embodiment includes upper-mold preheating burners 11 that are disposed along the outer peripheral walls 3b of the raised part 3a and preheat the outer peripheral walls 3b. The mold preheating device 10 also includes a lower-mold preheating burner 12 that is disposed inside the recessed part 4a and preheats the sidewalls 4b and the bottom wall 4c of the recessed part 4a, and intermediate-stalk preheating burners 13.

As shown in FIGS. 3 and 4, the mold preheating system 100 includes a mixture supply device 20 configured to supply mixture of air and gas (hereinafter also referred to as mixture). The mixture supply device 20 is connected to the upper-mold preheating burners 11 and the lower-mold preheating burner 12 and supplies the mixture to each burner chip.

The mixture supply device 20 according to the embodiment is connected to a pipe bifurcation part 23 through a mold pipe 22. The pipe bifurcation part 23 has connection openings communicating with one another on four sides, the upper connection opening being connected to the mold pipe 22, the right and left connection openings being connected to upper-mold pipes 11c, the lower connection opening being connected to a lower mold pipe 25.

The pipe bifurcation part 23 distributes, to the upper-mold pipes 11c and the lower mold pipe 25, the mixture transferred from the mixture supply device 20 through the mold pipe 22. The distributed mixture is supplied to the upper-mold preheating burners 11 and the lower-mold preheating burner 12.

Upper-Mold Preheating Burner

The upper-mold preheating burners 11 include the upper-mold pipes 11c (see FIG. 2) surrounding the outer peripheral walls 3b (see FIG. 1) formed at the raised part 3a of the upper mold 3.

The upper-mold pipes 11c have a substantially U shape when viewed from top and are disposed to surround at least three of the plurality of outer peripheral walls 3b formed at the raised part 3a of the upper mold 3. The upper-mold pipes 11c in the present example have the U shape but are not limited thereto and may have, for example, a square shape.

The upper-mold pipes 11c according to the embodiment include two straight pipes 11f disposed in parallel to the right and left outer peripheral walls 3b of the raised part 3a at predetermined intervals.

The upper mold 3 is preheated by flame ejected from a plurality of upper-mold preheating burner chips.

Each upper-mold pipe 11c is provided with first lined burner chips 11a, second lined burner chips 11b, a front-side burner chip 11d, and a back-side burner chip 11e that eject flame as upper-mold preheating burner chips. The front-side burner chips 11d and the back-side burner chips 11e are omitted in a perspective view in FIG. 4.

Although the first lined burner chips 11a and 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 burners 11 eject flame from the upper-mold preheating burner chips toward mainly the lower end surface 3f and the outer peripheral walls 3b of the raised part 3a. Accordingly, the upper-mold preheating burners 11 can efficiently and substantially uniformly preheat the four surfaces of the lower end surface 3f and the outer peripheral walls 3b of the raised part 3a of the upper mold 3, which is difficult to preheat in the cavity 2.

First Lined Burner Chip

Specifically, the pair of left and right straight pipes 11f are disposed obliquely below the left and right outer peripheral walls 3b. A plurality of extension pipes are provided as extensions on the outer surface of each straight pipe 11f at 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 chip 11a is mounted. The first lined burner chips 11a are disposed such that their leading ends are equally spaced from facing corners 3d.

With the above-described configuration, the first lined burner chips 11a eject flame obliquely upward from below toward the lower end surface 3f (see FIG. 1) of the raised part 3a formed at the upper mold 3. Accordingly, mainly the corners 3d and part of the lower end surface 3f and the outer peripheral walls 3b adjacent to the corners 3d are equally heated.

Second Lined Burner Chip

As shown in FIG. 3, the plurality of second lined burner chips 11b are disposed on the outer surface of each straight pipe 11f. The second lined burner chips 11b are each provided as an extension above the middle position between the first lined burner chips 11a disposed adjacent to each other and are alternately positioned with the first lined burner chips 11a in the pipe length direction.

The leading ends of the second lined burner chips 11b are disposed obliquely below the outer peripheral walls 3b of the raised part 3a shown in FIG. 1 at equal distances.

The leading ends of the second lined burner chips 11b are directed obliquely upward. The second lined burner chips 11b eject flame obliquely upward toward the outer peripheral walls 3b of the raised part 3a of the upper mold 3 and a recessed corner part 3e positioned between a lower surface 3c of the upper mold 3 and each outer peripheral wall 3b. Accordingly, mainly the outer peripheral walls 3b of the upper mold 3 to part of the lower surface 3c adjacent to the recessed corner parts 3e are heated.

In this manner, flame from the plurality of second lined burner chips 11b is ejected obliquely upward from below to uniformly heat a wide range that is oblique relative to the outer peripheral walls 3b.

The corners 3d are positioned between flame ejected from the first lined burner chips 11a and flame ejected from the second lined burner chips 11b. Accordingly, the efficiency of preheating the corners 3d is excellent and a desired temperature can be reached at an early timing.

Each recessed corner part 3e positioned between the corresponding outer peripheral wall 3b and the lower surface 3c of the upper mold 3 is typically difficult to preheat with flame ejected in a direction orthogonal to the lower surface 3c or the outer peripheral wall 3b because temperature partially increases.

However, in the mold preheating device 10 according to the embodiment, each recessed corner part 3e positioned between the lower surface 3c and the corresponding outer peripheral wall 3b is included in the range of flame obliquely toward the recessed corner part 3e. Accordingly, heating efficiency is excellent at the recessed corner part 3e like the outer peripheral wall 3b.

Front-Side and Back-Side Burner Chips

As shown in FIG. 3, each upper-mold preheating burner 11 according to the embodiment also includes the front-side burner chip 11d and the back-side burner chip 11e.

The front-side burner chip 11d and the back-side burner chip 11e are mounted at the leading ends of extension pipes 11g extended from each of the two straight pipes 11f of the upper-mold pipes 11c (see FIGS. 6 and 7).

The extension pipes 11g are extended in Z bending shapes from the outer surface of the straight pipe 11f in the vicinities of the front and rear ends, respectively, of the straight pipe 11f.

Accordingly, the front-side burner chip 11d or the back-side burner chip 11e is 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 walls 3b of the raised part 3a without contacting the upper mold 3.

Accordingly, the front-side and back-side outer peripheral walls of the raised part 3a are preheated to a uniform temperature equivalent to those of the left and right outer peripheral walls 3b at an early timing.

Lower-Mold Preheating Burner

The lower-mold preheating burner 12 includes a burner chip assembly 12a disposed inside the recessed part 4a shown in FIG. 1 at preheating, and the lower mold pipe 25 having a base end part 25b connected to the lower connection opening of the pipe bifurcation part 23 (see FIG. 4).

The lower mold pipe 25 has a crank shape bifurcated downward from the pipe bifurcation part 23, horizontally extended to a middle position in the lower mold 4, and having a leading end part bent downward. The burner chip assembly 12a is connected to a leading end part 25a of the lower mold pipe 25.

Mixture of air and gas supplied from the mixture supply device 20 through the mold pipe 22 is supplied into the burner chip assembly 12a through the lower mold pipe 25.

As shown in FIG. 4, the burner chip assembly 12a has a rectangular parallelepiped shape and includes a plurality of burner chips densely disposed on left and right side surfaces (see FIG. 6). The burner chips eject flame outward to left and right.

The lower mold 4 is positioned directly above the intermediate stalk 15 and its temperature is increased by flame from the intermediate-stalk preheating burners 13. Thus, the burner chip assembly 12a according to the embodiment is inserted to a central position of the relatively large internal space of the cavity 2 and disposed away from each sidewall 4b. Accordingly, preheating temperature of the entire cavity 2 can be uniformized by adjusting heating power used for preheating of the lower mold 4.

As shown in FIG. 7, a plurality of extension pipes 12b are provided as extensions from the burner chip assembly 12a. A single lower-mold preheating burner chip 12c is mounted at the leading end of each extension pipe 12b. The extension pipe 12b is bent such that the direction of flame ejected from the lower-mold preheating burner chip 12c has a predetermined tilt angle relative to the corresponding sidewall 4b or the bottom wall 4c in the cavity 2.

Intermediate-Stalk Preheating Burner

As shown in FIG. 4, the mold preheating device 10 further includes the intermediate- stalk preheating burners 13 inserted into the intermediate stalk 15 through the plurality of sprues 14, respectively.

The intermediate-stalk preheating burners 13 are connected to the mixture supply device 20 (see FIG. 3) through an intermediate-stalk pipe 24. The intermediate-stalk pipe 24 is extended to downward chip mounting pipes 28 through an intermediate-stalk pipe connection part 26. In other words, the intermediate-stalk pipe 24 has a path different from the mold pipe 22.

As shown in FIG. 5, lower parts of the chip mounting pipes 28 are inserted to a middle position of the intermediate stalk 15. A plurality of supply path burner chips 27 are mounted at the lower part of each chip mounting pipe 28. The plurality of supply path burner chips 27 each eject flame along the inner peripheral wall 15a of the intermediate stalk 15 (see FIG. 8). Accordingly, the intermediate stalk 15 provided in the molten metal supply path 6 is efficiently preheated.

Specifically, the intermediate-stalk preheating burners 13 include the intermediate-stalk pipe 24 bent toward below the upper-mold preheating burners 11. The intermediate-stalk pipe 24 is connected to the intermediate-stalk pipe connection part 26 that is bifurcated into two in parallel to the straight pipes 11f of the upper-mold preheating burners 11 below the outer peripheral walls 3b positioned on the left and right sides of the raised part 3a.

Lower parts of the intermediate-stalk preheating burners 13 as the intermediate-stalk pipe connection part 26 further extended downward and bent in L shapes are each further bifurcated into two chip mounting pipes 28, and accordingly, a total of four chip mounting pipes 28 are extended downward.

Each chip mounting pipe 28 includes the plurality of supply path burner chips 27. Three supply path burner chips 27 are provided as extensions in the pipe axial direction from the outer surface of the lower part of the chip mounting pipe 28. The number of burner chips may be set as appropriate and is not limited.

As shown in FIG. 5, at preheating, the chip mounting pipes 28 are inserted into the intermediate stalk 15 from the cavity 2 through the sprues 14. The supply path burner chips 27 are disposed away from the inner peripheral wall 15a at the middle position of the intermediate stalk 15 in the upper-lower directions.

As shown in FIG. 7, the supply path burner chips 27 are mounted on the outer surface of each chip mounting pipe 28 at 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 chips 27 are disposed to eject flame in a direction intersecting the radial direction of the intermediate stalk 15.

Typically, the inner peripheral wall 15a is locally heated and potentially damaged when flame from the supply path burner chips 27 is ejected in a direction orthogonal to the inner peripheral wall 15a.

The intermediate-stalk preheating burners 13 of the mold preheating device 10 according to the embodiment are inserted into the intermediate stalk 15 through the plurality of sprues 14 and preheat the intermediate stalk 15 by ejecting flame along the inner peripheral wall 15a of the intermediate stalk 15 as shown with arrows in FIG. 7.

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

The intermediate-stalk preheating burners 13 may be inserted into the intermediate stalk 15 except for at least one of the plurality of sprues 14. For example, three chip mounting pipes 28 may be inserted into respective sprues 14 at three places among the sprues 14 formed at four places as shown in FIG. 8, but no chip mounting pipe 28 may be inserted into the remaining sprue 14 at one place.

In this case, a sufficient amount of air for combusting mixture can be supplied by using, as a vent, the sprue 14 into which no intermediate-stalk preheating burner 13 is inserted. Accordingly, flame from the intermediate-stalk preheating burners 13 does not misfire and preheating can be stably performed.

The mold preheating system 100 according to the embodiment further includes a positioning device 30 shown with phantom lines in FIG. 6.

The positioning device 30 includes a mount 31 placed on the lower mold 4 (see FIG. 3). The mount 31 includes front, back, right, and left frames 32 and 33 connected to one another in a substantially rectangular frame shape in a plan view, and a plurality (in the present embodiment, three) of cylindrical parts 34 provided as upward extensions from parts where the frames 32 and 33 perpendicularly intersect.

The positioning device 30 also includes an upper-mold preheating burner positioning part 40 that positions the upper-mold preheating burners 11 on the mount 31, and a lower-mold preheating burner positioning part 50 that positions the lower-mold preheating burner 12. The positioning device 30 also includes an intermediate-stalk preheating burner positioning part 60 that positions the intermediate-stalk preheating burners 13.

The upper-mold preheating burners 11 and the lower-mold preheating burner 12 are positioned and held in the space between the upper mold 3 and the lower mold 4 by the upper-mold preheating burner positioning part 40 and the lower-mold preheating burner positioning part 50. The supply path burner chips 27 of the intermediate-stalk preheating burners 13 are positioned and held at the middle position in the intermediate stalk 15 by the intermediate-stalk preheating burner positioning part 60.

Accordingly, in the preheating process, each burner chip is disposed at a desired interval and angle with favorable preheating efficiency relative to the upper mold 3 and the lower mold 4. The upper mold 3 and the lower mold 4 are held at an appropriate interval by the cylindrical parts 34.

In the preheating process in which the intermediate-stalk pipe connection part 26 is positioned by the positioning device 30 shown in FIG. 6, two parts into which the intermediate-stalk pipe connection part 26 is bifurcated on the lower side are offset downward relative to the position of the burner chip assembly 12a of the lower-mold preheating burner 12 in the upper-lower directions.

Accordingly, flame ejected to sides from the burner chip assembly 12a achieves sufficient efficiency of preheating toward the sidewalls 4b of the lower mold 4 while avoiding the two bifurcated parts and the chip mounting pipes 28.

As described above, the mold preheating system 100 according to the embodiment includes the casting mold 1 for obtaining a cast metal product by supplying molten metal to the cavity 2 formed by the upper mold 3 and the lower mold 4, the melting furnace 5 provided below the lower mold 4, the molten metal supply path 6 through which molten metal in the melting furnace 5 is supplied to the cavity 2, and the mold preheating device 10 configured to preheat the casting mold 1.

The raised part 3a that forms a product shape is formed in the upper mold 3, and the recessed part 4a in which the raised part 3a is housed is formed in the lower mold 4.

The mold preheating device 10 includes the upper-mold preheating burners 11 that are disposed along the outer peripheral walls 3b of the raised part 3a and preheat the outer peripheral walls 3b, and the lower-mold preheating burner 12 that is disposed inside the recessed part 4a and preheats the sidewalls 4b and the bottom wall 4c of the recessed part 4a.

The mold preheating system 100 according 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 in FIG. 1, the upper-mold preheating burners 11 eject flame toward the outer peripheral walls 3b of the raised part 3a that is raised from the upper mold 3, thereby efficiently preheating the upper mold 3 in accordance with the shape of the raised part 3a that is difficult to preheat in the cavity 2.

Accordingly, similarly to the sidewalls 4b and the bottom wall 4c of the lower mold 4, which are preheated from the inside of the recessed part 4a by the lower-mold preheating burner 12, the upper mold 3 is 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 cavity 2 from the beginning of a casting process, and the preheating process can be finished in a short time.

As shown in FIG. 3, the upper-mold preheating burners 11 include the upper-mold pipes 11c surrounding the outer peripheral walls 3b of the raised part 3a. The upper-mold preheating burners 11 also include the first lined burner chips 11a that eject flame from the upper-mold pipes 11c toward the outer peripheral walls 3b of the raised part 3a and the lower end surface 3f of the upper mold 3.

In the mold-clamped state, the corners 3d of the raised part 3a formed at the upper mold 3 are positioned at corners of an upper surface where the flow speed of molten metal decreases in the cavity 2. Accordingly, the upper-mold preheating burners 11 of the upper-mold pipes 11c surrounding the outer peripheral walls 3b of the raised part 3a eject flame from the first lined burner chips 11a toward the corners 3d and directly preheat parts at the corners of the upper surface in the cavity 2.

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 cavity 2.

The upper-mold pipes 11c are disposed to surround the outer peripheral walls 3b of the raised part 3a. Accordingly, the upper-mold preheating burners 11 do not interfere with the raised part 3a when the upper mold 3 is moved down to the same height position as the upper-mold pipes 11c in the direction toward the lower mold 4.

Thus, the first lined burner chips 11a and the other burner chips can be disposed close to the raised part 3a to eject flame toward a central part of the upper mold 3. Moreover, in the preheating process, the interval between the upper mold 3 and the lower mold 4 can be narrowed as compared to a configuration in which the upper-mold pipes 11c are positioned directly below the raised part 3a.

Accordingly, the heat amount of flame that escape to the outside through the gap between the upper mold 3 and the lower mold 4 can be reduced and preheating efficiency can be further improved.

In the embodiment, the pair of left and right straight pipes 11f provided to the upper- mold preheating burners 11 are disposed obliquely below, in parallel to, and around the pair of respective outer peripheral walls 3b oppositely positioned on the left and right sides of the raised part 3a.

The plurality of first lined burner chips 11a provided at each straight pipe 11f eject flame toward the corners 3d each positioned between the corresponding outer peripheral wall 3b and the lower end surface 3f of the raised part 3a. In addition, the second lined burner chips 11b eject flame toward the recessed corner part 3e positioned between the lower surface 3c and the outer peripheral wall 3b of the upper mold 3.

Accordingly, as shown in FIG. 1, in the raised part 3a, the range of the lower end surface 3f to the corners 3d, the outer peripheral walls 3b, the recessed corner parts 3e, and the lower surface 3c of the upper mold 3 is uniformly preheated around the corners 3d.

More specifically, the plurality of first lined burner chips 11a according to the embodiment eject flame obliquely upward from below, thereby uniformly heating a wide range obliquely toward the lower end surface 3f in the opposite directions from left and right. For example, parts such as the corners 3d each positioned between the lower end surface 3f and the corresponding outer peripheral wall 3b are unlikely to be heated by flame that directly heats the lower end surface 3f or the outer peripheral walls 3b.

However, with the mold preheating device 10 according to the embodiment, the lower end surface 3f can be included in a range in which heating efficiency is favorable similarly to the corners 3d, and can be heated with flame toward the corners 3d each positioned between the lower end surface 3f and the corresponding outer peripheral wall 3b, and thus preheating efficiency is excellent.

Flame from the plurality of second lined burner chips 11b alternately arrayed with the first lined burner chips 11a is ejected obliquely upward from below, thereby uniformly heating a wide range obliquely toward the outer peripheral walls 3b. For example, parts such as the recessed corner parts 3e each positioned between the corresponding outer peripheral wall 3b and the lower surface 3c of the upper mold 3 are typically unlikely to be heated with flame ejected in a direction orthogonal to the lower surface 3c or the outer peripheral walls 3b.

However, with the second lined burner chips 11b, the recessed corner parts 3e can be included in a range in which heating efficiency is favorable with flame obliquely toward the recessed corner parts 3e each positioned between the lower surface 3c and the corresponding outer peripheral wall 3b. Accordingly, similarly to the outer peripheral walls 3b, the recessed corner parts 3e can be uniformly heated to improve preheating efficiency.

As shown in FIG. 3, each upper-mold preheating burner 11 according to the embodiment includes the front-side burner chip 11d and the back-side burner chip 11e.

The front-side burner chip 11d and the back-side burner chip 11e are mounted at the leading ends of each of the extension pipes 11g extended from the two straight pipes 11f of the upper-mold pipes 11c (see FIGS. 6 and 7).

The extension pipes 11g are extended in Z bending shapes from the outer surface of the straight pipe 11f in the vicinities of the front and rear ends, respectively, of the straight pipe 11f.

Thus, similarly to the pair of left and right outer peripheral walls 3b of the raised part 3a, 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 cavity 2 of the casting mold 1 clamped 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 in FIG. 8, the lower mold 4 includes the plurality of sprues 14 communicating with the molten metal supply path 6.

As shown in FIG. 5, the molten metal supply path 6 includes the intermediate stalk 15 through which molten metal is distributed to the plurality of sprues 14.

The mold preheating device 10 further includes the intermediate-stalk preheating burners 13 inserted into the intermediate stalk 15 through the plurality of sprues 14. As shown in FIG. 8, the intermediate-stalk preheating burners 13 eject flame along the inner peripheral wall 15a of the intermediate stalk 15.

Flame ejected at an angle from the intermediate-stalk preheating burners 13 instead of directly toward the inner peripheral wall 15a flows in a vortex along the annular inner peripheral wall 15a and uniformly heats the inner peripheral wall 15a. Thus, the inner peripheral wall 15a is equally preheated with flame from the plurality of intermediate-stalk preheating burners 13, and molten metal can smoothly pass through the intermediate stalk 15 at an early timing.

In the embodiment, the sprues 14 are 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 sprues 14 are 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 burners 13 may be inserted into the intermediate stalk 15 except for at least one of the plurality of sprues 14.

A sufficient amount of air can be supplied through ventilation by using, as a vent, a sprue 14 into which no intermediate-stalk preheating burner 13 is inserted, and flame from the intermediate-stalk preheating burners 13 can be stably ejected without misfire.

The mold preheating system 100 includes the mixture supply device 20 configured to supply mixture of air and gas, and the mold pipe 22 through which the mixture is supplied from the mixture supply device 20 to the upper-mold preheating burners 11 and the lower-mold preheating burner 12. The mold preheating system 100 further includes the intermediate-stalk pipe 24 through which the mixture is supplied from the mixture supply device 20 to the intermediate-stalk preheating burner 13 shown in FIG. 4.

The intermediate-stalk pipe 24 has a path different from the mold pipe 22.

The intermediate-stalk pipe 24 through which the mixture of air and gas is supplied to the intermediate-stalk preheating burners 13 has a path different from the mold pipe 22.

Thus, the amount of supply from the mixture supply device 20 can be easily differentiated. The preheating temperature of the intermediate stalk 15 can be maintained in a high temperature state by independently increasing the amount of mixture supplied to the intermediate-stalk preheating burners 13 and the amount of mixture supplied to the mold pipe 22.

Specifically, the intermediate stalk 15 in which molten metal is temporarily accumulated for distribution to the plurality of sprues 14 needs 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 path 6 or the sprues 14 are clogged and blocked and a casting process cannot be performed.

In the mold preheating system 100 according to the embodiment, desired mixture is supplied to the intermediate-stalk preheating burners 13 through the intermediate-stalk pipe 24 having a path different from the mold pipe 22. Accordingly, preheating temperature needed for passing of molten metal can be reached. Thus, molten metal can smoothly pass inside the intermediate stalk 15 sufficiently preheated from the beginning of a casting process and can be poured into the cavity 2.

Since the intermediate-stalk pipe 24 has a path different from the mold pipe 22, the amount of mixture supply from the mixture supply device 20 can be easily controlled.

Moreover, in the embodiment, although the same mixture is supplied to the upper-mold preheating burners 11 and the lower-mold preheating burner 12 at the same flow rate, the burner chip assembly 12a disposed at the center in the lower mold 4 can adjust the amount of heat in accordance with the number of flames by closing unnecessary chips. The burner chip assembly 12a can be densely provided with a plurality of burner chips to reduce preheating unevenness.

Thus, although mixture is supplied to the upper-mold preheating burners 11 and the lower-mold preheating burner 12 through the same path by using the pipe bifurcation part 23, preheating that is suitable for each component in the cavity 2 can be performed, and the preheating process can be substantially simultaneously finished in a short time with favorable preheating efficiency in the entire cavity 2.

Accordingly, a preheating time can be shortened and the number of pipe components can be reduced to reduce manufacturing cost of the mixture supply device 20.

The cavity 2 of the casting mold 1 is formed by the upper mold 3 in which the raised part 3a is formed and the lower mold 4 in which the recessed part 4a is formed, the raised part 3a being housed in the recessed part 4a and to form a product shape. The mold preheating device 10 preheats the casting mold 1 for obtaining a cast metal product by supplying molten metal from the melting furnace 5 provided below the lower mold 4 through the molten metal supply path 6 into the cavity 2. The mold preheating device 10 includes the upper-mold preheating burners 11 that are disposed along the outer peripheral walls 3b of the raised part 3a and preheat the outer peripheral walls 3b, and the lower-mold preheating burner 12 that is disposed inside the recessed part 4a and preheats the sidewalls 4b and the bottom wall 4c of the recessed part 4a.

Accordingly, the mold preheating device 10 that can finish a preheating process in a short time without waste molding is provided.

Specifically, the upper-mold preheating burners 11 eject flame toward the outer peripheral walls 3b of the raised part 3a that is raised from the upper mold 3. Thus, preheating can be efficiently performed in accordance with the shape of the raised part 3a of the upper mold 3 even when the shape of the raised part 3a is difficult to preheat in the cavity 2.

Accordingly, the upper mold 3 is preheated uniformly with the inner wall of the lower mold 4 preheated by flame ejected from the lower-mold preheating burner 12, and thus the entire cavity 2 can be preheated to a predetermined temperature.

The lower mold 4 further includes the plurality of sprues 14 communicating with the molten metal supply path 6. The molten metal supply path 6 includes the intermediate stalk 15 through which the molten metal is distributed to the plurality of sprues 14. The mold preheating device 10 further includes the intermediate-stalk preheating burners 13 inserted into the intermediate stalk 15 through the plurality of sprues 14. The intermediate-stalk preheating burners 13 eject flame along the inner peripheral wall 15a of the intermediate stalk 15.

Flame ejected along the inner peripheral wall 15a of the intermediate stalk 15 from the intermediate-stalk preheating burners 13 inserted into the intermediate stalk 15 can annularly flow in a vortex along the inner peripheral wall 15a. Thus, the inner peripheral wall 15a of the intermediate stalk 15 is equally preheated by flame from the plurality of intermediate-stalk preheating burner 13. 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 stalk 15.

The mold preheating system 100 according to the embodiment further includes the positioning device 30 as shown in FIG. 3.

As shown in FIG. 6 or 7, the positioning device 30 supports the upper-mold preheating burners 11 and improves the positioning accuracy of each of the first lined burner chips 11a and the second lined burner chips 11b. Accordingly, the positioning device 30 can 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 surface 3f and the corners 3d each positioned between the lower end surface 3f and the corresponding outer peripheral wall 3b are substantially uniformly preheated to a desired temperature at an early timing by the plurality of first lined burner chips 11a on the left and right sides.

In this case, although the recess part 3g that shapes the upper part of a cast metal product exists at the center of the lower end surface 3f, flame ejected obliquely from below on the left and right sides by the first lined burner chips 11a thoroughly reaches the inside of the recess part 3g obliquely above, and the recess part 3g can be heated at an early timing like the other part of the lower end surface 3f.

The lower-mold preheating burner 12 is disposed at a desired position inside the recessed part 4a and can preheat the sidewalls 4b and the bottom wall 4c of the recessed part 4a.

In the embodiment, the dimension between the sidewalls 4b facing each other with the internal space of the cavity 2 interposed therebetween is formed to be large as compared to that of the recessed part 4a, and the burner chip assembly 12a is 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 assembly 12a is moderately dispersed, thereby uniformly preheating the sidewalls 4b.

As described above, the upper-mold preheating burners 11, the lower-mold preheating burner 12, and the intermediate-stalk preheating burners 13 according to the embodiment are disposed in a gap across which the upper mold 3 is close to the lower mold 4, and can preheat each site in the cavity 2 at an early timing.

Accordingly, when a casting process is started and molten metal in the melting furnace 5 is supplied into the cavity 2 through the molten metal supply path 6 for the first time, the entire cavity 2 is 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 burner 11 includes the front-side burner chip 11d and the back-side burner chip 11e as shown in FIG. 3. However, the present invention is not limited thereto, and only one or none of the front-side burner chip 11d and the back-side burner chip 11e may be provided. Moreover, no slide mold part 7 may be provided at the lower mold 4 of the casting mold 1.

The mixture supply device 20 according to the embodiment supplies different mixtures to the mold pipe 22 and the intermediate-stalk pipe 24 as different paths, respectively.

The mixture supply device 20 may supply alone different mixtures to the mold pipe 22 and the intermediate-stalk pipe 24 as different paths, respectively. Alternatively, a mixture supply device dedicated to the mold pipe 22 and a mixture supply device dedicated to the intermediate-stalk pipe 24 may be configured as separate devices and supply different mixtures, respectively.

The mold preheating system 100 according to the embodiment includes the positioning device 30 as shown in FIG. 3. However, the present invention is not limited thereto, and the positioning device 30 does not necessarily need to be provided as long as the upper-mold preheating burners 11 that preheat the outer peripheral walls 3b are disposed along the outer peripheral walls 3b of the raised part 3a. In other words, the shape, number, and material of the positioning device 30 are not particularly limited as long as at least the upper-mold preheating burners 11 are disposed at appropriate positions.

MOLD PREHEATING SYSTEM AND MOLD PREHEATING DEVICE

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