JPS62101367A - Molten metal stopping and holding device for low-pressure casting machine - Google Patents

Abstract

PURPOSE:To extend the life of a protective pipe and heating means by providing the protective pipe which projects into a crucible and is built in with a heater and supplying a pressure fluid into the protective pipe as well thereby making pressurization. CONSTITUTION:The crucible 4 is housed and fitted into a heat insulated holding furnace 1 and the crucible 4 is communicated with the cavity 20 of a metallic mold 19 via a stalk 12. The protective pipe 21 which projects horizontally into the crucible 4 and consists of a refractory material is disposed. A heating coil 24 is provided to the pipe 21 to heat the molten metal A in the crucible 4. The pressurized air is supplied into the crucible 4 and at the same time the pressurized air is supplied into the protective cylinder 21 as well through a communicating passage 28 when the mold 19 is set. The difference between the inside and outside pressures of the cylinder 21 is thereby eliminated and the penetration of the metallic Na into the pipe 21 is suppressed. The cracking of the protective pipe 21 is prevented by the above-mentioned method and therefore, the life of the pipe 21 and the heating means therein are extended.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention supplies molten metal in a crucible to the main 11 bits of a mold via a storage by applying pressurized air pressure to the surface of the molten metal. The present invention relates to an improvement of a lagoon heat-retaining device for heating and maintaining molten metal in a crucible at a predetermined temperature in a low-pressure casting machine that is equipped with a high-pressure casting machine.

(Prior Art) In general, such a lagoon heat insulation device is constructed by embedding a heating coil in the side wall of a heat retention furnace that houses a crucible, and heating the crucible from its outer periphery using the heating action of the heating coil. An indirect heating type that keeps the molten metal stored in the crucible warm is well known.

However, since this method indirectly heats the molten metal in the crucible as described above, it has the drawback of increasing power consumption δ) and being uneconomical.

Therefore, in order to efficiently utilize the thermal energy required to keep the molten metal warm in the heating coil, for example,
As disclosed in Japanese Patent No. 102251, a protective tube made of a refractory material (such as ceramic) containing a heating coil is protruded into the crucible, and the molten metal in the crucible is directly heated. Direct heating type devices have been proposed that significantly reduce consumption.

To give you an example of comparing the power consumption of the indirect heating type and the direct heating type mentioned above under the same conditions, the indirect heating type has 22KW/Hr, while the direct heating type has 7KW/Hr. )-1r, making it possible to significantly reduce the consumption of Mino J.

(Problems to be Solved by the Invention) By the way, when making a cylinder head for use in an automobile engine using an aluminum alloy, for example, it is possible to add metallic sodium to the molten metal to refine the aluminum structure. This is commonly done. When such an aluminum alloy cylinder head is cast using a low-pressure casting machine equipped with a direct heating type heat retention device, pressurized air is applied to the surface of the molten metal to push the molten metal up into the mold. Due to the effect of this pressure, the metallic sodium in the Pj layer penetrates into the protective tube, and the difference in thermal expansion coefficient between the metallic sodium and silicon nitride, which constitutes the protective tube, causes cracks in the protective tube. There was a problem in that it was more likely to occur. Further, due to this, there is a possibility that the heating coil within the protection tube may be disconnected.

The present invention has been made in view of the above, and its purpose is to use pressurized air for low-pressure FA production in the direct heating type crucible with a protective tube protruding into the crucible as described above. By increasing the pressure inside the protective tube against the pressure of The aim is to extend the life of the means.

(Means for solving the problem) In order to achieve the above object, the solution of the present invention is to stoke the molten metal in the crucible kept at a predetermined temperature by applying pressure of pressurized air to the surface of the molten metal. A protective tube made of a refractory material that protrudes into the crucible and contains a heating means is provided for a low-pressure casting machine that supplies the crucible to the cavity of the mold through the crucible. Furthermore, 1, a pressurized fluid supply means for supplying pressurized fluid into the protective tube is provided.

(Function) With the above configuration, in the present invention, when pressurized air is supplied into the crucible, the molten metal in the crucible is heated to a predetermined temperature by the heating means in the protective tube made of refractory material that protrudes into the crucible. The pressure from the pressurized air acts on the molten metal surface, and the molten metal flows through the stalk into the mold hole V.
Supplied to Bitay.

At this time, since pressurized fluid is supplied into the protective tube made of the refractory material by the pressurized fluid supply means, the pressure inside the protective ffl is increased by the pressurized fluid, and the surface of the molten metal is pressurized. Even when air pressure is applied, the metal sodium added to the molten metal is prevented from penetrating into the protective tube.
Over a long period of time, the occurrence of cracks in the protective tube due to the difference in coefficient of thermal expansion between silicon nitride and silicon nitride is prevented, and the life of the protective tube is extended. Moreover, by preventing the occurrence of this crack, In damage to the heating means in the protective tube is also prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

The drawing shows a low-pressure Ti casting machine equipped with a sump heat-insulating device according to an embodiment of the present invention, in which 1 is an adiabatic heat-insulating furnace installed on a floor 2 via a support frame member 3, and 4 is an interior of the heat-insulating furnace 1. The crucible 4 is fitted and housed in a crucible 4, and a molten metal A made of an aluminum alloy is stored in the crucible 4. The above-mentioned heat retention furnace 1 is
A case 5 as an outer wall thereof, a first heat insulating material layer 6 housed in the case 5 so as to cover its inner wall surface and made of a heat insulating material such as a Hiramic fiber shade, and an inner side of the first heat insulating layer 6. 3! with a second heat insulating material layer 7 made of a heat insulating material such as a killable refractory, for example. f! It is formed in such a structure that it suppresses heat radiation of the molten metal Δ stored in the crucible 4.

Reference numeral 8 denotes two heat insulating material layers forming the upper surface openings of the heat insulating furnace 1 and the crucible 4 (insulating material layers 6, 8 constituting the insulating furnace 1).
The earth wall member 9 is made of the same material as 7), and 9 is a top plate provided on the upper surface thereof, and the substantially central portion of the upper wall member 8 and the top plate 9 is open.

Further, 10 is a furnace lid placed on the top plate 9,
A through hole 11 is formed in the center of the furnace cover 10 to correspond to the openings of the upper wall member 8 and the top plate 9 and penetrates in the vertical direction. A facing cylindrical stalk 12 extending in the vertical direction is supported with an engaging flange 12a at its L end engaged with an engaging recess 11a at the peripheral edge of the through hole 11. Further, a mold 19 is removably installed on the upper surface of the furnace lid 10, and a mold 20 in the mold 19 is inserted into the crucible via the slot 12.
communicated within. Holes 13 and 14 extending from the outer surface to the inner surface of the through hole 11 are provided in the furnace cover 10 in a radial direction so as to be substantially opposite to each other, and one of the hole portions 13 (on the right side of the figure) is a valve. J3 is connected to a pressurized air supply device (not shown) through a supply pipe 15 having a valve 18, while the other hole 14 (on the left side of the diagram) is connected to an exhaust pipe 16 having a valve 17. With the valve 17 on the pipe 16 side closed, the valve 18 on the supply pipe 15 side is turned on, and the pressurized air supply device is operated to supply pressurized air into the crucible 4 through the supply pipe 15. By applying the pressure of pressurized air to the phlebotomy of lysed iA in the crucible 4, the lysed ff1A
is supplied and filled into the cavity 20 of the mold 19.

Furthermore, 21 penetrates the side wall of the above-mentioned heat retention furnace 1 and the crucible 4
It is a protective tube made of a refractory material such as Hiramic, which protrudes horizontally from the outside within the crucible 4.
The tapered part protruding inward is closed to form a cylindrical shape at the bottom right.
The frontage opening to the outside of the heat-retaining furnace 1 communicates with a sealed chamber 26 that is sealed by the side wall of the case 5 of the heat-retaining furnace 1 and the fixing plate 25 so as to surround the opening. Above protection tube 2
A plurality of insulators 23.2 are placed on the side corresponding to the inside of the crucible 4 of 1.
3. ... is attached, and a heating coil 24 made of nichrome wire or the like as a heating means is stretched around each insulator 23, and the heating coil 24 is connected to the outside of the protection tube 21 via the core material 22 for power supply. It is connected to terminal 33. Further, the inside of the base side of the storage Ra pipe 21 is filled with a heat-resistant breathable material 27 made of glass, wool, or the like. Similarly, a heat-resistant breathable material 27 is also filled in a sealed chamber 26 formed by the fixing plate 25 and the side wall of the heat-retaining furnace 1 (case 5).

Further, a communication passage 28 is formed in a portion extending from the upper wall member 8 to the first heat insulating material layer 6 of the heat insulating furnace 1, and communicates the inside of the crucible 4 with the inside of the sealed chamber 26. The sealed chamber 26 and the pressurized air supply device supply pressurized air as a pressurized fluid into the C1 protection tube 21 to protect the same pressure as that applied to the hot water surface of Wja A in the crucible 4. Pressurized fluid supply means 31 designed to avoid acting on the inside of the pipe 21 as well.
consists of.

It's been done.

Note that 29 and 30 are holding members made of a refractory material for stably holding the protective tube 21, and 32 is a discharge mechanism for discharging the molten metal A from the crucible 4.

Therefore, in the above embodiment, the crucible 4 and the heat retention furnace 1
When pressurized air is supplied from the pressurized air supply device into the crucible 4 with the mold 19 sealed and the mold 19 sealed, the pressure inside the crucible 4 increases due to the pressurized air. The surface of the melt 4A in the crucible 4 is pressed, and the melt WA is pushed up and filled into the cavity 20 of the mold 19 through the stalk 12, whereby a cast product is low-pressure cast.

At this time, the inside of the crucible 4 and the inside of the protective tube 21 are connected to the communication path 2.
8, the pressurized air supplied into the crucible 4 through the supply pipe 15 pressurizes the surface of the melt 4A stored in the crucible 4, while the communication path 2
It is also supplied into the protective tube 21 through the tube 8, and pressurizes the inner wall of the protective tube 21 with the same pressure as that for bloodletting. From this, the pressure difference acting between the inner wall and the outer wall of the protective tube 21 is almost equal to that of the protective tube 21, and therefore, it is not the case that metallic sodium is added to the molten metal △ in order to refine the aluminum structure of the casting. However, storage of the above metal sodium 21
Penetration into the protective tube 21 is suppressed, and the occurrence of cracks in the protective tube 21 can be prevented for a long period of time, thereby extending the life of the protective tube 21. In addition, the protection tube 21
Since cracks do not occur in the heating coil 24, breakage of the heating coil 24 caused by such cracks can be effectively prevented.

In the above embodiment, the internal pressure of the protective tube 21 is increased by communicating the inside of the crucible 4 and the inside of the protective tube 21 through the communication passage 28, but the invention is not limited thereto. It is also possible to adopt the method of supplying pressurized fluid into the protective tube 21 from the outside separately.

Further, in the above embodiment, pressurized air was used to increase the internal pressure of the protection tube 21, but this is not limiting, and other gases may be used as long as they do not inhibit the heating function.Furthermore, In the case where the pressurized fluid supply device is provided separately as described above, it is also possible to use liquid as the pressurized fluid.

Further, in the above embodiments, a direct heating type was shown, but an indirect heating type may also be used in combination.

(Effects of the Invention) As explained above, according to the present invention, the pressurized fluid is supplied by the pressurized fluid supply means into the protective tube made of a fireproof material that protrudes into the crucible and has a built-in heating means.
A metal added to the molten metal to refine the casting structure by minimizing the difference between the pressure of pressurized air acting on the molten metal and the pressure acting on the inner wall of the pressurized fluid storage tube. It is possible to suppress sodium from permeating into the protection tube, and thus the lifespan of the protection tube and heating means can be extended.

[Brief explanation of drawings]

The drawing is a longitudinal cross-sectional view of a low-pressure &8-building machine equipped with a water storage preservation device according to an embodiment of the present invention. 4... Crucible, 12... Stoke, 15... Supply pipe, 19... Mold, 20...: 1 Yavitei, 21...
... Protection tube, 24 ... Heating coil, 26 ... Sealed chamber, 28 ... Communication path, 11 ... Pressurized fluid supply means,
△...Molten metal. Patent applicant: Mazda Motor Corporation
Before Rinto 1) Hiroshi'
rjl1. -One.

Claims (1)

[Claims] (1) In a low-pressure casting machine, the molten metal in the crucible kept at a predetermined temperature is supplied to the cavity of the mold via the stalk by applying pressurized air pressure to the surface of the molten metal. 1. A sump heat-insulating device for a low-pressure casting machine, comprising: a protruding protective tube made of a refractory material and having a built-in heating means; and a pressurized fluid supply means for supplying pressurized fluid into the protective tube.