JP2008132526A - Filter installation apparatus, and gas substitution method in runner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter installation apparatus with which a gas substitution in a runner and simultaneous insertion of filters respectively into a plurality of sprues provided at a mold can be performed, and to provide a gas substitution method in a runner using the same. <P>SOLUTION: The filter installation apparatus 70 includes: four holders 72a to 72d for holding the filters 60; and a supporting frame 74 for supporting all holders 72a to 72d. Before mold closing, the filters 60 held by the holders 72a to 72d are inserted into the sprues 54a to 54d, and gaseous argon is fed into a chamber 42 of intermediate strokes 22 via feed passages 88 provided at the flange parts 76 of the holders 72a, 72b. The air in the chamber 42 pressed by the gaseous argon is exhausted from exhaust passages 92 formed at the flange parts 76 of the holders 72c, 72d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a filter installation in which a filter can be disposed in a gate of a casting mold and an atmosphere of a hot water passage communicating with a cavity formed by the casting mold can be replaced with an inert gas. The present invention relates to an apparatus and a gas replacement method for a waterway using the apparatus.

  The low pressure casting method has been widely adopted as a method for mass production of internal combustion engine components for automobile parts. A casting apparatus for carrying out the low-pressure casting method generally includes a molten metal holding furnace that stores molten metal, and a lower mold that is disposed above the molten metal holding furnace and has a gate for allowing the molten metal to pass therethrough. A cavity for obtaining a cast product is formed by having a plurality of side molds and an upper mold, and so-called mold closing is performed by the lower mold, the side mold, and the upper mold.

  The molten metal holding furnace communicates with the cavity through stalk which is a hot water channel. When the pressure in the molten metal holding furnace reaches a predetermined value or more, the pressurized molten metal rises in the stalk and fills the cavity through the gate. That is, the molten metal is poured from below the cavity, and the liquid level rises in the cavity as the amount of molten metal increases. In some cases, an intermediate stalk may be interposed between the stalk and the gate.

  After the predetermined amount of pouring is completed, the molten metal is cooled and solidified to form a cast product. Thereafter, the mold is opened and the cast product is taken out.

  By the way, it is necessary to clean the burrs and core sand residue in the mold before the casting operation is performed. For this reason, during cleaning, the burrs and sand are transferred to the intermediate stalk and stalk through the gate. There is concern to reach. In addition, when the cast product is taken out from the mold after casting, the molten metal stored in the stalk and intermediate stalk returns to the molten metal holding furnace, but at that time, the molten metal comes into contact with the atmosphere, The surface of the molten metal returned to the molten metal holding furnace is oxidized. When such a situation occurs, impurities are mixed into the molten metal during the next casting operation, which causes casting defects.

  In order to eliminate this inconvenience, for example, a net body mounting device described in Patent Document 1 is used. The net body mounting device is installed in a mold during cleaning to cover the gate, and prevents burrs and core sand from entering stalks and intermediate stalks. Further, the filter installed at the gate serves to prevent the oxide in the stalk from being mixed into the molten metal or the cast product.

  Apart from the above, in the casting operation, when the molten metal comes into contact with the air in the middle stalk or stalk, the surface layer portion is oxidized, and this causes the flow of the molten metal to be inhibited. There is a concern that casting defects such as poor filling occur. In order to avoid this problem, it is considered that a mold apparatus having an inlet structure as described in Patent Document 2 is used, and air is replaced with an inert gas through the inlet structure.

Japanese Utility Model Publication No. 6-46606 Japanese Patent Publication No. 52-3889

  The mold apparatus described in Patent Document 2 is provided with a structure for replacing gas in the mold apparatus itself (the inlet structure). Therefore, in the case of a commercially available mold apparatus, a large modification is required, and the apparatus configuration is There is a problem of increasing complexity and size.

  Moreover, since the inert gas supply passage extends in the horizontal direction, there is a concern that the molten metal may enter the supply passage. When the molten metal actually enters, the solidified material adheres to the supply passage, so that complicated maintenance work needs to be performed.

  The present invention has been made in order to solve the above-described problems, and it is possible to replace the atmosphere of the runway with an inert gas without modifying the mold apparatus at all, and to supply an inert gas. It is an object of the present invention to provide a filter installation device capable of wiping out the concern that the molten metal does not enter the passage, and the coagulated material adheres to the supply passage, and a gas replacement method for the hot water passage using the same. .

In order to achieve the above-mentioned object, the present invention provides a method in which a filter is simultaneously disposed in each of a plurality of gates of a casting mold, and the gate is connected to a water channel communicating with a cavity formed by the casting mold. A filter installation device for supplying an inert gas from at least one of the locations,
A plurality of holders having a flange portion having a large diameter compared to the opening diameter of the gate;
A support frame for supporting the holder;
Have
A supply passage for supplying the inert gas to at least one of the plurality of holders is provided;
A discharge passage for discharging the gas purged from the hot water passage is provided in at least one of the plurality of holders,
When the filter held by the holder is inserted into the gate, the inert gas supplied from the inert gas supply mechanism is supplied from the supply passage to the hot water passage, while the inert gas is supplied. Along with this, the gas purged from the hot water passage is discharged from the discharge passage.

  With the configuration described above, the filter held in the holder can be simultaneously inserted into the gate in one operation, and the gas (usually air) in the runner is turned into an inert gas such as argon gas. Substitution is also possible. That is, according to the present invention, it is possible to perform the filter installation and the gas replacement with a single device, so that it is more cost effective than when the filter mounting operation and the gas replacement operation are performed with separate devices. In addition, there is no need to switch the apparatus in accordance with switching between the filter mounting operation and the gas replacement operation. For this reason, work efficiency improves.

  Further, since gas replacement is performed by the filter installation device, there is no need to modify the casting device (molding device). This is also advantageous in terms of cost, and the casting apparatus is neither enlarged nor complicated. Note that the holder provided with the gas supply passage and the holder provided with the gas discharge passage may be separate or the same.

  Further, since the filter installation device is detached from the mold before the mold is closed, the molten metal does not enter the gas supply passage provided in the filter installation device along with the pouring of the cavity. For this reason, the solidified product of the molten metal does not adhere to the gas supply passage, and therefore the frequency of the cleaning operation of the gas supply passage is remarkably reduced.

  And it can avoid that a molten metal contacts air and a surface layer oxidizes by substituting a hot water path with an inert gas. Therefore, it is possible to avoid the flow of the molten metal from being hindered, and eventually it becomes possible to obtain a cast product having no casting defects.

  In addition, intermediate stalk can be illustrated as a runway. That is, if an inert gas is mainly supplied into the intermediate stalk, the gas in the intermediate stalk can be purged.

Further, the present invention is a gas replacement method for a water channel that replaces the atmosphere of the water channel communicating with the cavity formed by the casting mold with an inert gas,
Using a filter installation device having a plurality of holders having a flange portion having a diameter larger than the opening diameters of the plurality of gates of the casting mold, and a support frame for supporting the holder,
By inserting the filter held by the holder into the gate, a filter is disposed in each of the gates,
On the other hand, the inert gas supplied from the inert gas supply mechanism is supplied to the hot water passage from a supply passage provided in at least one of the holders, and the inert gas is supplied. Accordingly, the gas purged from the hot water channel is discharged from a discharge passage provided in at least one of the plurality of holders.

  As described above, according to the present invention, the filter installation work and the gas replacement work are performed by the same device, which is advantageous in terms of cost and improves work efficiency. Moreover, it is possible to avoid oxidation of the surface layer of the molten metal by substituting the atmosphere of the hot water channel with an inert gas, and as a result, a cast product having no casting defects can be obtained as described above.

  Preferable examples of the inert gas include argon gas. The density of the argon gas is larger than that of air, so that argon stays below the hot water channel while air is unevenly distributed above the hot water channel. For this reason, if the molten metal is poured from below, the molten metal can be prevented from coming into contact with air.

  And since argon gas is comparatively cheap, it can also suppress that casting cost rises.

  In addition, as a specific example of the runway, intermediate stalk can be mentioned as described above.

  According to the present invention, since the gas replacement of the runner is performed by the filter installation device capable of simultaneously attaching the filters to all the gates, there is no need to modify the casting apparatus. For this reason, it can avoid that a casting apparatus enlarges or a structure becomes complicated, and can avoid that capital investment soars.

  In addition, since the atmosphere at the gate is replaced with an inert gas, it is avoided that the molten metal comes into contact with an oxidizing atmosphere such as air and the surface layer is oxidized. Therefore, since the fluidity of the molten metal is maintained, a cast product free from casting defects can be obtained. In other words, the manufacturing yield is improved.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a hot water gas replacement method according to the present invention will be described in detail with reference to the accompanying drawings by giving preferred embodiments in relation to a filter installation device for carrying out the method. In the present embodiment, a case where gas substitution is mainly performed inside the intermediate stalk will be described as an example.

  First, the low-pressure casting apparatus 10 will be described with reference to FIG. The low pressure casting apparatus 10 includes a molten metal holding furnace 12 and a mold 16 that forms a cavity 14. The inner chamber 18 of the molten metal holding furnace 12 and the cavity 14 are communicated with each other via a stalk 20 and an intermediate stalk 22. ing.

  The molten metal holding furnace 12 is a container for storing the molten metal L, and is heated from the outside by heating means (not shown) in order to avoid the molten metal L from being cooled and solidified in the inner chamber 18. The molten metal holding furnace 12 is connected to a compressed gas supply mechanism (not shown), and the compressed gas supplied from the compressed gas supply mechanism pressurizes the molten metal L stored in the molten metal holding furnace 12.

  The upper end of the opening of the molten metal holding furnace 12 is closed by a furnace lid 24. In the furnace lid 24, a through hole 26 is formed at a location corresponding to the approximate center of the virtual upper end surface of the molten metal holding furnace 12. An annular step portion 28 is provided in the through hole 26, and the large-diameter portion 30 of the stalk 20 is placed on the annular step portion 28.

  The stalk 20 is a tubular body having a long small diameter portion 32 and the large diameter portion 30 protruding like a flange. In other words, the stalk 20 is formed with an inner hole 34 extending along the axial direction thereof. And while the front-end | tip of the small diameter part 32 is immersed in the molten metal L, the large diameter part 30 is mounted in the cyclic | annular step part 28 of the through-hole 26 of the furnace cover 24 as mentioned above.

  The intermediate stalk 22 disposed above the stalk 20 includes a flange portion 36 having a diameter substantially corresponding to the diameter of the large-diameter portion 30 of the stalk 20, and a tapered portion 38 having a diameter increased outward from the flange portion 36 in the diametrical direction. And an equal diameter portion 40. Inside the intermediate stalk 22, a chamber 42 is provided from the flange portion 36 to the equal-diameter portion 40, and this chamber 42 serves as a hot water channel together with the inner hole 34 of the stalk 20.

  The mold 16 has a lower mold 44 disposed above the intermediate stalk 22, two side molds 46 and 48, a rear mold 50, a front mold (not shown), and an upper mold 52. As shown in FIG. 2, the middle lower mold 44 is provided with four gates 54 a to 54 d for filling the cavity 14 with the molten metal L. Of course, all of the four gates 54a to 54d are formed at positions where the chamber 42 of the intermediate stalk 22 and the cavity 14 can communicate with each other.

  Each of the gates 54a to 54d includes a tapered tapered diameter path 56 on the lower side and a tapered diameter expanded path 58 on the upper side. Among these, the filter 60 shown in FIG.

  The filter 60 is made of a material having a melting point higher than the molten metal temperature. When aluminum or an aluminum alloy is used as the molten metal L, an iron-based material or the like is suitable. As shown in FIG. 3, the filter 60 has a substantially truncated cone shape, and a bulging portion 62 that protrudes in the axial direction is formed at the center of the bottom surface. Moreover, the outer peripheral part 64 of the filter 60 is diameter-expanded in the taper shape by the angle corresponding to the taper angle of the taper-shaped diameter expansion path 58 of the gates 54a-54d as it goes upwards of FIG. The shape of the filter 60 substantially corresponds to the shape of the tapered enlarged diameter path 58, but its height dimension is slightly smaller than the height dimension of the tapered enlarged diameter path 58, and the diameter of the outer peripheral portion 64. Is set slightly larger than the diameter of the corresponding portion in the tapered diameter-expanding path 58.

  The two side molds 46, 48, the rear mold 50 and the front mold (not shown) together with the lower mold 44 and the upper mold 52 form a closed space, that is, the cavity 14 filled with the molten metal L. The upper mold 52 is formed with a vent hole 66 for allowing air to escape from the cavity 14 when the cavity 14 is filled with the molten metal L.

  Next, a filter installation device 70 for inserting the filter 60 into the gates 54a to 54d (tapered enlarged diameter path 58) will be described.

  FIG. 2 shows an overall schematic perspective view of the filter installation device 70 according to the present embodiment, in addition to the lower mold 44. This filter installation device 70 is for simultaneously inserting the filter 60 into each of the four gates 54 a to 54 d provided in the lower mold 44, and includes four holders 72 a to 72 d for holding the filter 60, And a support frame 74 that supports all the holders 72a to 72d.

  The holder 72a is formed by a large-diameter flange portion 76 for positioning and a projection 78 having a smaller diameter than the flange portion 76. The flange portion 76 and the projection 78 are integrally formed. Yes. Further, as the material of the flange portion 76 and the projecting portion 78, a material having a small degree of magnetization by a magnet 80 (see FIG. 4) described later, such as aluminum, is selected.

  As shown in FIG. 4, a recess 82 extending in the axial direction until reaching the flange portion 76 is formed in the protrusion 78. In the recess 82, a magnet 80 is screwed up and down via a bolt 84, and the entire holder 72a is suspended by the magnet 80. The position of the magnet 80 can be adjusted by a nut 86 disposed on the upper portion of the holder 72a. The nut 86 is screwed into the bolt 84.

  The diameter of the flange portion 76 is set larger than the opening diameter of the tapered enlarged diameter path 58 of the gates 54a to 54d. For this reason, as shown in FIG. 4, when the protrusion 78 is inserted into the tapered enlarged diameter path 58, the flange portion 76 is finally dammed to the bottom surface of the lower mold 44.

  A supply passage 88 is formed through the flange portion 76. An argon gas supply pipe (not shown) is connected to the supply passage 88 via an L-shaped joint 90. Of course, the argon gas supply pipe is bridged with an argon gas supply source (not shown) such as an argon gas cylinder.

  Of the remaining holders 72b to 72d, the holder 72b has the same configuration as the holder 72a. On the other hand, the holders 72c and 72d are configured in the same manner as the holders 72a and 72b, except that the discharge passage 92 is formed through the flange portion 76. Accordingly, the same components as those of the holder 72a are denoted by the same reference numerals, and detailed description thereof is omitted.

  The support frame 74 is formed in a substantially U shape by bending downward and is bridged to the two first frames 94a and 94b that are parallel to each other and the leading ends of the first frames 94a and 94b. Rod-shaped second frames 96a and 96b. Further, a grip portion 98 that is bent downward is attached to the approximate center of the first frames 94a and 94b. In addition, a bolt 84 is implanted at each tip of the first frames 94a and 94b, and the magnet 80 constituting the holders 72a to 72d is engaged with each of the bolts 84.

  The insertion of the filter 60 into the gates 54a to 54d and the gas replacement in the chamber 42 of the intermediate stalk 22 are performed as follows using the filter installation device 70 configured as described above.

  First, the bulging portions 62 of the four filters 60 are attracted to the magnets 80 of the holders 72a to 72d through magnetic force. At this time, the bulging portion 62 enters, for example, a space formed by the protrusion 78 of the holder 72 a and the bottom of the magnet 80 and is attracted to the magnet 80.

  Next, the grip portion 98 of the filter installation device 70 is gripped, and the filters 60 held by the holders 72 a to 72 d of the filter installation device 70 are simultaneously inserted into the tapered diameter expansion paths 58 of the low pressure casting device 10.

  When each filter 60 attracted by the magnet 80 is inserted into each tapered enlarged diameter path 58, the diameter of the outer peripheral portion 64 of the filter 60 is larger than the diameter of the corresponding portion of the tapered enlarged diameter path 58 as described above. Therefore, the outer peripheral portion 64 is pressed against the side wall of the tapered enlarged diameter path 58. As a result, the outer peripheral portion 64 is compressed inward in the diameter direction.

  Along with this compression, an elastic biasing force directed to the side wall of the tapered enlarged diameter path 58 is generated at the outer peripheral portion 64 of each filter 60. Further, the lower end surfaces of the flange portions 76 of the holders 72a to 72d are in contact with the bottom surface of the lower mold 44, while the tip of the filter 60 is dammed near the bottom of the tapered enlarged diameter path 58, whereby the filter 60 is tapered. It is positioned at a predetermined position of the expanded diameter path 58.

  Then, argon gas as an inert gas is supplied from the argon gas supply source (not shown). The argon gas reaches the chamber 42 of the intermediate stalk 22 through the L-shaped joint 90 connected to the flange portions 76 of the holders 72a and 72b, the supply passage 88, and mainly the gates 54a and 54b.

  The density of argon gas is larger than that of air. For this reason, the argon gas that has reached the inside of the chamber 42 flows downwardly of the chamber 42, while the air below the chamber 42 is pressed by the argon gas and rises. The argon gas may reach the inner hole 34 of the stalk 20.

  The raised air mainly passes through the discharge passages 92 provided in the flange portions 76 of the gates 54c and 54d and the holders 72c and 72d where the holders 72c and 72d are seated. At this time, the mold is not closed, and the discharge passage 92 is open to the atmosphere. Therefore, the air discharged from the chamber 42 of the intermediate Stoke 22 and the inner hole 34 of the Stoke 20 is discharged to the atmosphere. .

  As described above, the air in the chamber 42 of the intermediate stalk 22 and the air in the inner hole 34 of the stalk 20 are replaced with argon gas. Note that it is not particularly necessary to replace all of the air with argon gas. For example, half of the volume of the intermediate stalk 22 may be replaced with argon gas.

  Thus, in the present embodiment, gas replacement in the chamber 42 of the intermediate stalk 22 is performed via the filter installation device 70. Therefore, there is no need to modify the low-pressure casting apparatus 10, and therefore, the configuration of the low-pressure casting apparatus 10 does not become complicated and large.

  After the replacement with the argon gas is completed, the filter 60 is lifted to lift the filter 60 from the holders 72a to 72d. As described above, the outer peripheral portion 64 of each filter 60 presses the side wall of the tapered diameter-expanding path 58 by its elastic urging force, and the bulging portion 62 is formed by this elastic urging force. It is further strengthened. As a result, the elastic biasing force of the outer peripheral portion 64 of the filter 60 is larger than the magnetic attractive force of the magnet 80. For this reason, the filter 60 can be easily detached from the magnet 80 only by moving the filter installation device 70 upward.

  That is, according to this filter installation device 70, not only can the gas in the chamber 42 of the intermediate stalk 22 be replaced, but a plurality of filters 60 can be simultaneously inserted into the gates 54a to 54d in one operation. Therefore, it is not necessary to prepare the gas replacement device and the filter installation device as separate devices, which is advantageous in terms of cost. Further, since the gas replacement device is not removed after the gas replacement is performed and the filter 60 is not inserted into the gates 54a to 54d by the filter installation device, the operation is simplified and the operation time is shortened.

  The casting operation will continue. That is, as shown in FIG. 1, the mold is closed, and the cavity 14 is formed by the lower mold 44, the two side molds 46 and 48, the rear mold 50, the front mold and the upper mold 52 (not shown). Next, a compressed gas, preferably an inert gas such as argon gas, is supplied into the molten metal holding furnace 12, and the molten metal L is pressurized by this to raise the molten metal L. The molten metal L finally reaches the cavity 14 via the gates 54a to 54d.

  At this time, even if impurities such as the peeled coating agent are mixed in the molten metal holding furnace 12, the filter 60 is fitted to the gates 54a to 54d, so that the impurities are blocked by the filter 60, It is reliably separated from the molten metal L.

  In addition, since the filter installation device 70 is detached from the lower mold 44 before the molten metal L starts to rise, the molten metal L does not enter the supply passage 88 for supplying argon gas. For this reason, since the solidified material does not adhere to the supply passage 88, the frequency of the cleaning operation of the supply passage 88 is significantly reduced.

  As the molten metal L rises to the cavity 14, the argon gas supplied to the inner hole 34 of the stalk 20 and the chamber 42 of the intermediate stalk 22 also rises and reaches the cavity 14 before the molten metal L. Therefore, the air in the cavity 14 rises as it is pressed by the argon gas, and is discharged from the vent hole 66 provided in the upper mold 52.

  As can be understood from this, according to the present embodiment, the molten metal L is prevented from coming into contact with air in the chamber 42 or the cavity 14 of the intermediate stalk 22. Therefore, it is possible to avoid the surface layer of the molten metal L from being oxidized. For this reason, the fluidity of the molten metal L can be maintained. And as a result of maintaining the flow rate of the molten metal L in this way, it becomes possible to obtain a product free from casting defects.

  Even when about half of the volume of the chamber 42 is replaced with argon gas, the density of the argon gas is larger than that of air as described above, so that the argon gas stays below the chamber 42. In addition, since the air is unevenly distributed above the chamber 42, the molten metal L is prevented from coming into contact with the air in the chamber 42 after all.

  When a predetermined amount of molten metal L is poured into the cavity 14, pressurization of the molten metal L in the molten metal holding furnace 12 is finished, and the molten metal L is cooled and solidified. This cooling and solidification leads to a cast product. As described above, since the impurities are prevented from reaching the cavity 14 by the filter 60 inserted into the gates 54a to 54d, the obtained casting has very few casting defects and the like. In other words, it is possible to obtain a high-quality cast product with a high yield.

  In the above-described embodiment, the filter installation device 70 having four holders 72a to 72d has been described as an example. However, the number of holders can be appropriately set according to the number of gates. Needless to say. Further, the number of holders provided with the supply passage 88 for supplying argon gas and the number of holders provided with the discharge passage 92 can be set as appropriate. In addition, both the supply passage 88 and the discharge passage 92 may be provided in the same holder.

  The provision of the intermediate stalk 22 is not essential, and the stalk 20 and the gates 54a to 54d may communicate with each other.

  Further, it is not essential to provide the bulging portion 62 in the filter 60. In other words, you may make it insert the filter 60 which does not comprise the bulging part 62 in the gates 54a-54d. In this case, it is preferable to use a magnet 80 having a height dimension smaller than that of the recess 82 in the height direction. As a result, the magnetic attraction force of the magnet 80 becomes smaller than the elastic urging force of the filter 60, so that the filter 60 can be easily inserted and fitted into the gates 54a to 54d.

  Furthermore, the inert gas is not particularly limited to argon gas, and may be any kind of gas as long as it does not cause a chemical change of the molten metal. A suitable example of an inert gas other than argon gas is xenon gas.

It is a principal part schematic longitudinal cross-sectional view of a low pressure casting apparatus. FIG. 2 is a schematic perspective view of the lower mold constituting the mold of the low-pressure casting apparatus and the entire filter installation apparatus according to the present embodiment. It is a whole schematic perspective view of the filter inserted in the said lower mold gate. It is a principal part schematic longitudinal cross-sectional view which shows the state which inserted the said filter hold | maintained at the holder of the said filter installation apparatus in the said lower mold gate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Low pressure casting apparatus 12 ... Melt holding furnace 14 ... Cavity 16 ... Mold 18 ... Inner chamber 20 ... Stoke 22 ... Intermediate stalk 34 ... Inner hole 42 ... Chamber 44 ... Lower mold 46, 48 ... Side mold 50 ... Rear mold 52 ... Upper molds 54a to 54d ... Pouring gate 58 ... Tapered diameter expansion path 60 ... Filter 62 ... Expanded portion 66 ... Vent hole 70 ... Filter installation device 72a to 72d ... Holder 74 ... Support frame 76 ... Flange portion 78 ... Protrusion 80 ... Magnet 82 ... Recess 88 ... Supply passage 92 ... Discharge passage L ... Molten metal

Claims (5)

A filter for simultaneously disposing a filter in each of a plurality of gates of a casting mold and supplying an inert gas from at least one of the gates to a water channel communicating with a cavity formed by the casting mold An installation device,
A plurality of holders having a flange portion having a large diameter compared to the opening diameter of the gate;
A support frame for supporting the holder;
Have
A supply passage for supplying the inert gas to at least one of the plurality of holders is provided;
A discharge passage for discharging the gas purged from the hot water passage is provided in at least one of the plurality of holders,
When the filter held by the holder is inserted into the gate, the inert gas supplied from the inert gas supply mechanism is supplied from the supply passage to the hot water passage, while the inert gas is supplied. A filter installation device characterized in that the gas purged from the hot water passage is discharged from the discharge passage.   The apparatus according to claim 1, wherein the inert gas is supplied into the intermediate stalk as the hot water path to purge the gas in the intermediate stalk. A hot water gas replacement method for replacing the atmosphere of the hot water channel communicating with the cavity formed by the casting mold with an inert gas,
Using a filter installation device having a plurality of holders having a flange portion having a diameter larger than the opening diameters of the plurality of gates of the casting mold, and a support frame for supporting the holder,
By inserting the filter held by the holder into the gate, a filter is disposed in each of the gates,
On the other hand, the inert gas supplied from the inert gas supply mechanism is supplied to the hot water passage from a supply passage provided in at least one of the holders, and the inert gas is supplied. Accordingly, the gas purged from the runner is discharged from a discharge passage provided in at least one of the plurality of holders.   4. The gas replacement method according to claim 3, wherein argon gas is used as the inert gas.   5. The gas replacement method according to claim 3 or 4, wherein a gas in intermediate stalk is replaced with the inert gas as the hot water channel.

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