JP7313007B2 - Low-pressure casting machine and heater unit for low-pressure casting machine - Google Patents

Description

The present invention relates to a low-pressure casting apparatus in which a sub-stalk is arranged between a stalk inserted into a molten metal holding furnace and a mold provided above the stalk, and a heater unit used in the low-pressure casting apparatus.

A low-pressure casting apparatus has a mold consisting of an upper mold and a lower mold above a molten metal holding furnace that stores molten metal such as an aluminum alloy, inserts the lower end of a cylindrical stalk into the molten metal holding furnace, and connects the upper end of the stalk to the lower mold via a sub-stalk. Here, when pressurized in a molten metal holding furnace heated to a predetermined temperature, the molten metal fills the cavity of the mold through the stalk and sub-stalk and solidifies to obtain a predetermined cast product.
In such a low-pressure casting apparatus, the sub-stalk is heated during casting so that the molten metal does not solidify at the sprue portion of the lower mold (sprue clogging). Techniques using a gas burner or an electric heater as disclosed in Patent Documents 1 and 2 are known as means for heating the substoke.

Japanese Utility Model Publication No. 8-4204 Japanese Patent No. 3212208

In the case of a gas burner, since the flame hits the substoke directly, the heating tends to be non-uniform, making it difficult to stabilize the quality of the cast product, and there is also a risk of leakage of molten metal due to distortion of the substoke.
In addition, since the number of man-hours required for ignition and heat adjustment is increased, and the heat adjustment depends on the skill of the operator, there is a risk of a temperature drop due to misfire, resulting in a decrease in work efficiency.
Furthermore, since it is used in a narrow space, combustion cannot be maintained unless the air ratio is high, and the amount of energy consumed increases due to constant combustion. In addition, convection heat heats not only the substoke but also the entire atmosphere, resulting in poor heating efficiency.

On the other hand, the use of an electric heater enables uniform heating, stabilizes quality, and prevents deterioration in work efficiency. Therefore, it is desirable as a heating means, but it is necessary to protect the sealed terminal and wiring from heat. In particular, it is conceivable to employ an infrared lamp heater as an electric heater that emits sufficient radiant heat in a high-temperature atmosphere, but the life of this infrared lamp heater is significantly reduced when the temperature of the sealed terminal portion exceeds 350°C. Since the subtalk is heated in a high temperature atmosphere of 500° C. or higher, durability cannot be ensured unless measures are taken to keep the sealed terminal portion at 350° C. or lower. Also, in order to protect wiring from heat, appropriate protection cannot be achieved unless consideration is given to wiring.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a low-pressure casting apparatus and a heater unit for the low-pressure casting apparatus that can suppress the temperature rise of the sealed terminal portion and wiring to ensure durability even when an infrared lamp heater is used as a means for heating the substoke.

In order to achieve the above object, the invention according to claim 1 is a low-pressure casting apparatus comprising a molten metal holding furnace, a stalk inserted into the molten metal holding furnace, a mold arranged above the stalk and comprising an upper mold and a lower mold, a sub-stalk arranged between the stalk and the lower mold, and a heating means for heating the sub-stalk,
The heating means is an infrared lamp heater, which is arranged in a heating space formed around the sub-stoke and comprises a heat-generating part having a heat-generating body, and a sealed terminal provided at the end of the heat-generating part for leading out a lead wire electrically connected to the heat-generating body,
A peripheral portion of the substoke in the heating space is partitioned into an upper space and a lower space by a metal partition member having a heat insulating layer,
The infrared lamp heater is bent between the heating portion and the sealing terminal portion so that the heating portion is disposed in the upper space and the sealing terminal portion is disposed in the lower space.
The invention according to claim 2 is characterized in that, in the structure of claim 1, the infrared lamp heater is a bar-shaped body bent into an L shape, the heating part is arranged sideways in the upper space, and the sealing terminal part is arranged downward in the lower space.
The invention according to claim 3 is characterized in that, in the configuration of claim 1 or 2, the heat generating part of the infrared lamp heater is formed by enclosing a thin plate -shaped carbon fiber filament serving as a heating element in a glass tube, and in the outer surface of the glass tube, an infrared reflective paint is applied to a region outside the carbon fiber filament opposite to the substoke, or a metal reflector is arranged outside the carbon fiber filament opposite to the substoke in the glass tube .
According to a fourth aspect of the present invention, in the structure of the third aspect, the carbon fiber filament is arranged in the glass tube with the irradiation surface facing obliquely upward toward the sub-stalk side .
The invention according to claim 5 is characterized in that, in the structure according to any one of claims 1 to 4, the outer surface of the sub-stoke is coated with an infrared absorbing material.
According to a sixth aspect of the present invention, there is provided a lower die base for supporting the lower die and through which the sub-stalk penetrates.
The invention according to claim 7 is characterized in that, in the configuration according to any one of claims 1 to 6, the partition member has a circular shape surrounding the outer side of the sub-stalk, and the plurality of infrared lamp heaters are supported by the partition member along the circular shape.
In order to achieve the above object, the invention according to claim 8 is provided in a low-pressure casting apparatus including a molten metal holding furnace, a stalk inserted into the molten metal holding furnace, a mold arranged above the stalk and composed of an upper mold and a lower mold, and a sub-stalk arranged between the stalk and the lower mold, and a heater unit for heating the sub-stalk,
a metal partition member disposed in a heating space formed around the sub-stoke, having a heat insulating layer, and dividing a portion around the sub-stoke in the heating space into an upper space and a lower space;
an infrared lamp heater comprising a heat generating portion having a heat generating element and a sealed terminal portion provided at an end of the heat generating portion for leading out a lead wire electrically connected to the heat generating element;
The infrared lamp heater is bent between the heating portion and the sealing terminal portion, and is characterized in that the heating portion is supported above the partition member and the sealing terminal portion is supported below the partition member.

According to the inventions of claims 1 and 8, an infrared lamp heater is used as a heating means for the sub-stoke, and the heating part of the infrared lamp heater is arranged above the partition member having the heat insulating layer, and the sealed terminal part is arranged below the partition member. Therefore, even if the infrared lamp heater is used, the temperature rise of the sealed terminal part and wiring can be suppressed and durability can be ensured. In addition, since the wiring is led out to the lower space, the handling property is also improved.
According to the second aspect of the present invention, in addition to the above effects, the infrared lamp heater is a bar-shaped body bent into an L shape, the heating part is arranged sideways in the upper space, and the sealed terminal part is arranged downward in the lower space. Therefore, it is possible to reliably withdraw the sealed terminal part into the lower space while effectively heating the sub-stalk by the heating part.
According to the third aspect of the present invention, in addition to the above effects, the heating portion of the infrared lamp heater is configured such that the carbon fiber filament is enclosed in the glass tube, and the outer surface of the glass tube is coated with a reflective paint on the outer side of the carbon fiber filament opposite to the substoke, or the outside of the carbon fiber filament on the opposite side to the substoke in the glass tube is provided with a reflector . In addition, since the reflective paint and reflector do not oxidize even at high temperatures, infrared rays can be prevented from leaking out, and an improvement in heating efficiency can be expected.
According to the fourth aspect of the present invention, in addition to the above effect, the carbon fiber filament is arranged in an obliquely upward posture with the irradiation surface facing the sub-stalk side, so that the upper part of the sub-stalk and the lower mold, which are at a distance from the infrared lamp heater, can be uniformly heated by being irradiated with infrared rays. Therefore, the quality of cast products is stabilized.
According to the fifth aspect of the present invention, in addition to the above effects, the outer surface of the sub-stalk is coated with an infrared absorbing material, so that the infrared absorption rate of the sub-stalk increases, leading to an improvement in heating efficiency.
According to the sixth aspect of the invention, in addition to the above effects, the through hole of the sub-stalk in the die base of the lower mold is formed to be larger than the outer shape of the sub-stalk so that the lower mold is exposed in the upper space. In addition, since a large upper space can be secured, the layout of the infrared lamp heater is less likely to be restricted, and installation can be easily performed.
According to the seventh aspect of the present invention, in addition to the above effects, the partition member has a frame shape surrounding the outside of the sub-stoke, and a plurality of infrared lamp heaters are supported by the partition member along the frame shape, so that the sub-stoke can be uniformly heated from the entire circumference.

It is an explanatory view of a low-pressure casting apparatus. FIG. 4 is a perspective view of the heater unit (the inside of the infrared lamp heater is omitted). 4 is a plan view of the heater unit (the inside of the infrared lamp heater is omitted); FIG. (A) is a sectional view taken along the line AA of FIG. 3, and (B) is a sectional view taken along the line BB. It is a top view of a heater unit. It is a side view of a heater unit. 6 is a cross-sectional view taken along line CC of FIG. 5; FIG. It is explanatory drawing of the example of a change using a reflector.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.
[Overall description of low-pressure casting equipment]
FIG. 1 is a cross-sectional view showing an example of a low-pressure casting apparatus. This low-pressure casting apparatus 1 includes a molten metal holding furnace 2, a mold 3 disposed above the molten metal holding furnace 2, and a stalk 4 and a sub-stalk 5 connecting the molten metal holding furnace 2 and the mold 3.
The molten metal holding furnace 2 holds molten metal obtained by melting a casting metal such as an aluminum alloy at a predetermined temperature (for example, 700° C.) by heating means (not shown). The upper opening is closed by a lid 6, and a gas such as air can be supplied from a pressurizing port 7 at a predetermined pressure.
The mold 3 has a lower mold 8 and an upper mold 9 , and the lower mold 8 is horizontally supported above the lid 6 by a lower mold die base 10 installed above the molten metal holding furnace 2 . The upper mold 9 forms a cavity 11 with the lower mold 8, and can be brought into contact with and separated from the lower mold 8 by a drive mechanism (not shown).

The stalk 4 is a cylindrical body vertically supported by a cover 6 in the center of the molten metal holding furnace 2. The lower end is inserted into the molten metal, while the upper end penetrates the cover 6 and opens upward.
The sub-stalk 5 has a cylindrical portion 12 whose lower end is coupled to the upper end of the stalk 4, and an expanded portion 13 which expands from the upper portion of the cylindrical portion 12 into a rectangular shape in plan view. The expanded portion 13 has connection ports 15 on the upper surface that are connected to a plurality of sprues 14 formed in the lower mold 8, and penetrates through holes 16 formed in the lower mold die base 10 to be connected to the lower mold 8. The through hole 16 is formed to be larger in front, rear, left, and right than the expanded portion 13 , and exposes the lower surface of the lower mold 8 around the expanded portion 13 .
A heating space 17 for accommodating the sub-stalk 5 is formed between the lid 6 and the lower mold die base 10 , and a heater unit 20 for heating the sub-stalk 5 is arranged in this heating space 17 .

[Explanation of heater unit]
As shown in FIGS. 2 and 3, the heater unit 20 includes a partition plate 21 made of metal (for example, stainless steel) and having a square frame shape in plan view through which the expanded portion 13 of the sub-stalk 5 penetrates, and a plurality of rod-shaped infrared lamp heaters 22, 22, . . . The partition plate 21 here has a rectangular shape in plan view, with the width of one side 21A, 21A parallel to each other being larger than the width of the other side 21B, 21B.
First, the partition plate 21 has an upper plate 23 and a lower plate 24 having a rectangular frame shape in plan view, a heat insulating board 25 arranged between the upper plate 23 and the lower plate 24, and a support base 26 arranged below the lower plate 24. As shown in FIG. 4, the outer and inner edges of the upper plate 23 are formed with folded pieces 27, 27, . When both plates 23 and 24 are assembled by screws or welding, outer edge folded pieces 27 and 28 overlap each other, and inner edge folded pieces 27, 27, . The heat insulating board 25 is accommodated throughout the space.

The support base 26 has a rectangular tubular shape with an opening area slightly larger than the inner opening surrounded by the inner edge of the lower plate 24 , and its upper end is joined to the lower surface of the lower plate 24 .
The outer shape of the partition plate 21 is one size smaller than the through hole 16 of the lower mold die base 10 . Therefore, as shown in FIG. 1, the partition plate 21 is positioned below the through hole 16 of the lower mold die base 10 in a state where the lower end of the support table 26 is placed on the upper surface of the lid body 6 with the sub-stalk 5 penetrating therethrough.

As shown in FIGS. 5 and 6, the infrared lamp heater 22 includes a pair of carbon heaters 31, 31 housed in an elongated cylindrical transparent glass outer tube 30 closed at both ends in the longitudinal direction.
The outer tube 30 is L-shaped and has a horizontal straight portion 32 that is laterally supported along the sides 21A and 21B of the partition plate 21, a bent portion 33 that curves downward from the horizontal straight portion 32, and a lower straight portion 34 that extends downward from the bent portion 33. A sealing terminal portion 35 is provided at the lower end of the lower straight portion 34.

The carbon heater 31 is formed by enclosing a thin plate-like carbon fiber filament 37 having slits alternately formed on both longitudinal side edges thereof together with an inert gas in an inner tube 36 made of transparent glass and having a slender cylindrical shape with a diameter smaller than that of the outer tube 30. Both ends of the inner tube 36 are provided with internal sealing terminal portions 39, 39 from which lead wires 38, 38 electrically connected to the carbon fiber filament 37 are led out, respectively. On the closed end side of the horizontal straight portion 32 of the outer tube 30, the lead wires 38, 38 are electrically connected to each other, and the carbon fiber filaments 37, 37 are connected in series. On the opposite end side, the lead wires 38 , 38 are led out to the sealed terminal portion 35 through the bent portion 33 and the lower straight portion 34 .

The carbon heaters 31, 31 are accommodated in parallel in the horizontal straight portion 32 of the outer tube 30. Here, as shown in FIGS. 6 and 7, on each side 21A, 21B of the partition plate 21, the carbon fiber filaments 37, 37 are fixed in the horizontal straight portion 32 so as to assume an obliquely upward posture facing the center side (substoke 5 side) of the partition plate 21 at an angle of 45° with respect to the upper plate 23. In addition, the outer carbon heater 31 is positioned above the inner carbon heater 31, and the inner and outer carbon fiber filaments 37, 37 are vertically shifted and fixed in the horizontal straight part 32 so that they are aligned in a cross section. In addition, as shown in FIGS. 2 and 3, a reflecting surface 40 coated with an infrared reflective paint is formed on the outer surface of the horizontal straight portion 32 in a half-peripheral area outside the carbon fiber filaments 37 .

The infrared lamp heaters 22 thus formed are supported on the partition plate 21 by fixed covers 41, 41 . That is, each horizontal linear portion 32 is supported on the upper plate 23 in parallel with the upper plate 23 by inserting the outer tube 30 across the insertion holes 42 formed in the mutually facing surfaces of the fixed cover 41 . However, the positions of the two infrared lamp heaters 22, 22 on the side 21A are vertically shifted so that the outer infrared lamp heater 22 is positioned higher than the inner infrared lamp heater 22, similarly to the carbon fiber filaments 37, 37.
The lower straight portions 34 of the infrared lamp heaters 22 pass through the through holes 43, 43, .

In the heating space 17 in which the heater unit 20 is installed, the infrared lamp heaters 22 provided on the respective sides 21A and 21B of the partition plate 21 surround the substalk 5 from the outside in the upper space 17A, and the irradiation surfaces 37a of the carbon fiber filaments 37 and 37 of the carbon heaters 31 are oriented toward the expanded portion 13 side. The outer surface of the sub-stalk 5 here is coated with a paint containing an infrared absorbing material. In the upper space 17A, each infrared lamp heater 22 is positioned below the lower mold 8 exposed through the through hole 16 provided in the lower mold die base 10. As shown in FIG.
On the other hand, in the lower space 17B, the sealed terminal portions 35 of the infrared lamp heaters 22 are arranged outside the support base 26, respectively. The lead wires 38, 38 of the carbon heaters 31, 31 are respectively covered with a heat-resistant tube and lead out from the sealed terminal portion 35, pass outside the support base 26, and as shown in FIG.

[Description of operation of low-pressure casting equipment]
In the low-pressure casting apparatus 1 configured as described above, during casting, the lower mold 8 and the upper mold 9 are preheated by a mold heater or the like, and the molds are clamped. Then, pressure is applied from the pressurization port 7 to the molten metal holding furnace 2, and the molten metal is filled into the cavity 11 from the sprue 14 of the lower mold 8 through the stalk 4 and the sub-stalk 5.
Simultaneously with this or after a predetermined time has elapsed, each infrared lamp heater 22 is energized to heat the carbon fiber filament 37 of each carbon heater 31 to red heat at 1200 to 1400.degree. Therefore, the sub-stalks 5 are heated from substantially the entire periphery by radiant heat from the irradiation surfaces 37a of the carbon fiber filaments 37 arranged on the sides 21A and 21B of the partition plate 21, and the molten metal in the sub-stalks 5 and the sprue 14 is prevented from solidifying. At this time, since the entire circumference of the expanded portion 13 and the lower surface of the lower mold 8 are exposed in the upper space 17A by the through hole 16 of the lower mold die base 10, the expanded portion 13 is evenly heated to the upper end, and the molten metal in the sprue 14 is also effectively heated.

After the molten metal solidifies in the cavity 11 , the unsolidified molten metal returns into the molten metal holding furnace 2 via the stalk 4 when the pressurization to the molten metal holding furnace 2 is released. At this time, since the molten metal in the sub-stalk 5 and the sprue 14 is not solidified by the heating of the infrared lamp heater 22, it returns to the molten metal holding furnace 2 via the stalk 4.
Even if the upper space 17A is heated to a high temperature (approximately 500° C.) by heating the substalk 5 in this way, the lower space 17B is partitioned by the partition plate 21 having the heat insulating board 25, so that the temperature rise of the lower space 17B is suppressed. The heat-resistant temperature of molybdenum used for the sealed terminal portion 35 is 350° C., and if this temperature is exceeded, the life of the molybdenum is significantly reduced.

[Effects of Low Pressure Casting Apparatus and Heater Unit Invention]
Thus, in the low-pressure casting apparatus 1 and the heater unit 20 of the above-described embodiment, the heating means for the sub-stalk 5 is the infrared lamp heater 22 which is arranged in the heating space 17 formed around the sub-stalk 5 and comprises the horizontal straight portion 32 (heat generating portion) having the carbon fiber filament 37 (heating element), and the sealing terminal portion 35 which is provided at the end of the horizontal straight portion 32 and leads out the lead wire 38 (wiring) electrically connected to the carbon fiber filament 37. The heating space 17 is formed of the heat insulating board. The upper space 17A and the lower space 17B are partitioned by a metal partition plate 21 (partition member) having 25 (heat insulating layer), and the infrared lamp heater 22 is bent between the horizontal straight portion 32 and the sealing terminal portion 35 so that the horizontal straight portion 32 is arranged in the upper space 17A and the sealing terminal portion 35 is arranged in the lower space 17B.

As a result, even if the infrared lamp heater 22 is used as the heating means for the sub-stoke 5, the temperature rise of the sealed terminal portion 35 and the lead wire 38 can be suppressed and the durability can be ensured. In addition, since the lead wire 38 is led out to the lower space 17B, it is easy to handle.
Furthermore, the sub-stoke 5 can be heated without heating the entire atmosphere of the heating space 17 due to the infrared radiation effect. In addition, by adopting the infrared lamp heater 22, temperature control can be automated, and the work man-hours for ignition and heat adjustment like a gas burner can be reduced, leading to improved workability, and temperature drop due to misfire can be avoided. In addition, since it is not necessary to keep the infrared lamp heater 22 energized all the time, the amount of energy used can be saved.

Particularly, in this case, the infrared lamp heater 22 is a rod-shaped body bent into an L shape, the horizontal straight portion 32 is arranged sideways in the upper space 17A, and the sealing terminal portion 35 is arranged downward in the lower space 17B. Therefore, the sub-stalk 5 can be effectively heated by the horizontal straight portion 32, and the sealing terminal portion 35 can be reliably retracted into the lower space 17B.
Further, the horizontal straight portion 32 of the infrared lamp heater 22 is formed by enclosing a thin plate-shaped carbon fiber filament 37 serving as a heating element in an outer tube 30 (glass tube), and on the opposite side of the sub-stalk 5 sandwiching the carbon fiber filament 37, a reflecting surface 40 is formed by coating the outer surface of the outer tube 30 with an infrared reflective paint, so that the infrared rays that the sub-stalk 5 easily absorbs can be effectively emitted. Furthermore, since the reflective paint does not oxidize even at high temperatures, infrared rays can be prevented from leaking out, and an improvement in heating efficiency can be expected.
Since the carbon fiber filament 37 is arranged in the outer tube 30 in such a posture that the irradiation surface 37a on the side of the sub-stalk 5 faces obliquely upward, the upper part of the sub-stalk 5 and the lower mold 8 which are distant from the infrared lamp heater 22 are also irradiated with the infrared rays and can be uniformly heated. Therefore, the quality of cast products is stabilized.

On the other hand, since the outer surface of the sub-stoke 5 is coated with an infrared absorbing material, the infrared absorption rate of the sub-stoke 5 is increased, leading to an improvement in heating efficiency.
In addition, since the through hole of the sub-stalk 5 in the lower mold die base 10 is formed larger than the outer shape of the sub-stalk 5 and the lower mold 8 is exposed in the upper space 17A, the upper part of the sub-stalk 5 and the lower mold 8 are easily irradiated with infrared rays, and the lower mold 8 can be effectively heated. In addition, since the upper space 17A can be secured widely, the layout of the infrared lamp heater 22 is less likely to be restricted, and the installation can be easily performed.
Further, the partition plate 21 has a frame shape surrounding the outside of the sub-stalk 5, and a plurality of infrared lamp heaters 22 are supported by the partition plate 21 along the frame shape, so that the sub-stalk 5 can be uniformly heated from substantially the entire circumference.

[Description of modification example]
In the above embodiment, an infrared lamp heater having sealed terminals at one end of the heat generating part is used, but an infrared lamp heater having sealed terminals at both ends of the heat generating part can also be used. In this case, the sealing terminal portions at both ends protrude into the lower space, instead of being L-shaped, but being U-shaped with both ends bent. The support structure of the infrared lamp heater is not limited to the above-described form, and a support plate or the like fixed on the partition plate may be used.
The infrared lamp heater has a form in which a pair of carbon heaters are accommodated, but may be formed with only one carbon heater. In this case, the inner tube is omitted and one carbon fiber filament is enclosed. One infrared lamp heater may be arranged on each side.
The shape of the carbon fiber filament is not limited to the above-mentioned form, and it may be one without slits or the like. As the heating element, a tungsten heating element can be used instead of the carbon heating element.
The tilted attitude of the heating element with respect to the sub-stoke is not limited to 45°, but can be appropriately changed within the range of about 30 to 60°. However, if the required amount of heat is obtained, the horizontal or vertical posture may be used instead of the tilted posture, or the tilted posture may be combined with the tilted posture.

On the other hand, in the above embodiment, the reflecting surface is formed on the outer tube, but instead of this, as shown in FIG. Also in this case, infrared rays can be effectively radiated. In addition, since the reflector 45 does not oxidize even at high temperatures, leakage of infrared rays can be prevented, and an improvement in heating efficiency can be expected. However, the reflecting surface and the reflecting plate may be omitted, and the substoke's infrared absorbing paint may be omitted.
As for the partition member, although the partition plate has a square shape in plan view in the above embodiment, it may have another shape such as a triangle, polygon, or circle in plan view as long as it surrounds the outer circumference of the sub-stalk. Conversely, the shape of the partition is not limited to the frame shape, and a U-shaped or C-shaped partition member may be used in plan view, or a plurality of these partition members may be arranged around the sub-stalk. In this case, the number and arrangement of the infrared lamp heaters may be changed according to the form of the partition member.

The heat insulation layer of the partition member is not limited to the heat insulation board of the form described above, and may be formed by laminating a plurality of heat insulation sheets or by filling heat resistant glass long fibers.
In the above embodiment, the heating space is vertically partitioned by the horizontal partition plate positioned below the through-hole so that the lower space is semi-closed. However, depending on the shape of the sub-stalk or the partition member, the lower space may be closed by fitting the partition member into the through-hole or by providing a wall surrounding the lower space on the outer periphery of the partition member. Similarly, it is possible to suppress the temperature rise by arranging, for example, a partition member whose cross section is inverted U-shaped or inverted U-shaped in the heating space and arranging the sealed terminal portion in the lower space closed inside the partition member.

1 low-pressure casting apparatus 2 molten metal holding furnace 3 mold 4 stalk 5 sub-stalk 6 lid 8 lower mold 9 upper mold 10 lower mold die base 11 cavity 12 cylindrical portion 13 expanded portion 14 sprue 16 through hole 17 heating space 17A upper space 17B lower space 20 heater unit 21 partition plate 2 2 infrared lamp heater, 23 upper plate, 24 lower plate, 25 heat insulation board, 26 support, 30 outer tube, 31 carbon heater, 32 horizontal straight portion, 33 bent portion, 35 sealed terminal portion, 36 inner tube, 37 carbon fiber filament, 37 a irradiation surface, 38 lead wire, 40 reflection surface, 45 reflection plate.

Claims (8)

a molten metal holding furnace;
a stalk inserted into the molten metal holding furnace;
a mold disposed above the stalk and comprising an upper mold and a lower mold;
a sub-stalk disposed between the stalk and the lower mold;
a heating means for heating the substoke, comprising:
The heating means is an infrared lamp heater which is arranged in a heating space formed around the sub-stoke and comprises a heat-generating portion having a heat-generating body, and a sealed terminal provided at an end of the heat-generating portion for leading out a lead wire electrically connected to the heat-generating body,
A peripheral portion of the sub-stoke in the heating space is partitioned into an upper space and a lower space by a metallic partition member having a heat insulating layer,
The infrared lamp heater is bent between the heat generating portion and the sealing terminal portion, and the heat generating portion is disposed in the upper space, and the sealing terminal portion is disposed in the lower space. 2. The low-pressure casting apparatus according to claim 1, wherein the infrared lamp heater is a bar-shaped body bent into an L shape, the heat generating portion is arranged sideways in the upper space, and the sealing terminal portion is arranged downward in the lower space. 3. The low-pressure casting apparatus according to claim 1, wherein the heat generating portion of the infrared lamp heater is formed by enclosing a thin plate-shaped carbon fiber filament serving as the heating element in a glass tube, and an infrared reflective paint is applied to an area outside the carbon fiber filament on the outer surface of the glass tube opposite to the sub-stalk, or a metallic reflector is arranged outside the carbon fiber filament on the opposite side to the sub-stalk in the glass tube . 4. The low-pressure casting apparatus according to claim 3, wherein the carbon fiber filament is arranged in the glass tube with an irradiation surface facing obliquely upward toward the sub-stalk side . 5. The low-pressure casting apparatus according to claim 1, wherein the outer surface of said sub-stalk is coated with an infrared absorbing material. 6. The low-pressure casting apparatus according to any one of claims 1 to 5, further comprising a lower mold die base that supports the lower mold and through which the sub-stalk penetrates, wherein a through-hole of the sub-stalk in the lower mold die base is formed to be larger than an outer shape of the sub-stalk so that the lower mold is exposed in the upper space. 7. The low-pressure casting apparatus according to claim 1, wherein the partition member has a circumferential shape surrounding the outer side of the sub-stalk, and the plurality of infrared lamp heaters are supported by the partition member along the circumferential shape. A heater unit provided in a low-pressure casting apparatus comprising a molten metal holding furnace, a stalk inserted into the molten metal holding furnace, a mold arranged above the stalk and composed of an upper mold and a lower mold, and a sub-stalk arranged between the stalk and the lower mold, the heater unit for heating the sub-stalk,
a metal partition member disposed in a heating space formed around the sub-stoke, having a heat insulating layer and dividing a portion around the sub-stoke in the heating space into an upper space and a lower space;
an infrared lamp heater comprising a heat generating part having a heat generating element and a sealed terminal part provided at an end of the heat generating part and leading out a lead wire electrically connected to the heat generating element,
The infrared lamp heater is bent between the heating portion and the sealing terminal portion, and the heating portion is supported above the partition member, and the sealing terminal portion is supported below the partition member.

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