JP2009101404A - Low-pressure casting machine, and low-pressure casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-pressure casting machine whose cost can be made low and which can produce a casting of high quality, and a low-pressure casting method. <P>SOLUTION: Disclosed is a low pressure casting machine provided with: a holding furnace 4 having a molten metal waiting tank 2 and a molten metal pouring tank 3; a stoke 9 communicating the molten metal pouring tank 3 and a mold 5; a check valve 11 interposed in a communication path 10 between the molten metal waiting tank 2 and the molten metal pouring tank 3, allowing the flow of the molten metal from the molten metal waiting tank 2 to the molten metal pouring tank 3 and regulating the flow of the molten metal from the molten metal pouring tank 3 to the molten metal waiting tank 2; and an inner pressure regulation means 12 capable of individually regulating the inner pressure of the molten metal waiting tank 2 and the molten metal pouring tank 3, and increasing the inner pressure of the molten metal waiting tank 2 and replenishing the molten metal in the molten metal waiting tank 2 to the molten metal pouring tank 3 till the molten metal in the molten metal pouring tank 3 reaches a set level LS. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a low pressure casting machine and a low pressure casting method.

  As a casting method for metal materials such as aluminum alloy and magnesium alloy, a mold is placed on the upper side of the holding furnace, the holding furnace and the inside of the mold are communicated with each other by stalk, and the lower end of stalk is immersed in the molten metal. A low pressure casting method is widely known in which a molten metal is supplied into a mold through stalk and cast by increasing the internal pressure of the furnace.

  By the way, in this low-pressure casting method, the molten metal for a plurality of castings is stored in the holding furnace, and the continuous casting is performed. There was a problem that the supply pressure fluctuated and the quality of the cast product varied. In addition, when the molten metal is supplied into the holding furnace, the oxide generated on the surface of the molten metal is supplied together with the molten metal into the holding furnace, resulting in a problem that the quality of the cast product is deteriorated.

  In order to solve such a problem, for example, Patent Document 1 includes a holding furnace including a molten metal standby tank and a pouring tank, a stalk communicating the molten metal tank and the mold, and the molten metal standby tank and the pouring tank. A molten metal shut-off valve that opens and closes the communication path, a hot water holding means that places the molten metal shut-off valve in the open position when the amount of hot water in the pouring tank is less than the reference amount, Low-pressure casting machine comprising suction means for reducing pressure, pressurizing means for pressurizing the molten metal surface in the pouring tank, and drive means for driving the suction means and the pressurizing means sequentially or simultaneously as the casting process starts. Has been proposed. Patent Document 1 describes a molten metal standby tank divided into a molten metal dust removal tank and a holding temperature control, and a filter provided in a passage from the molten metal dust removal tank to the holding temperature control tank.

  In the low-pressure casting machine described in Patent Document 1, the amount of molten metal used in one casting is sequentially replenished every time casting is performed from the molten metal standby tank to the molten metal tank, so that the molten metal level in the molten metal tank is always uniform. Thus, it is possible to prevent the deterioration of the quality of the cast product due to the sequential decrease in the melt level, and it is possible to obtain effects such as the ability to remove oxides contained in the melt with a filter.

JP 2001-321914 A

  However, the low-pressure casting machine described in Patent Document 1 requires a driving means for opening and closing the molten metal shut-off valve, which increases the manufacturing cost of the low-pressure casting machine and drives the molten metal shut-off valve. Since the rod moves up and down, oxides are likely to be generated at the contact portion between the molten metal surface and the rod, and there is a problem that the generated oxide is mixed into the molten metal and the quality of the molten metal is deteriorated.

  Further, when removing foreign substances such as oxides with a filter, it is necessary to periodically replace the clogged filter, which causes a problem that the operation is complicated and the running cost is increased.

  An object of the present invention is to provide a low-pressure casting machine and a low-pressure casting method that can be manufactured at low cost and can produce a cast product with good quality.

  The low-pressure casting machine according to the present invention is interposed in a holding furnace having a molten metal standby tank and a pouring tank, Stoke communicating the molten metal tank and the mold, and a communication path between the molten metal standby tank and the molten metal tank, A check valve that allows the flow of molten metal from the molten metal standby tank to the molten metal tank and regulates the flow of molten metal from the molten metal tank to the molten metal standby tank, and an internal pressure that can individually adjust the internal pressure of the molten metal standby tank and the molten metal tank And adjusting means.

  In this low pressure casting machine, with the molten metal supplied to the molten metal standby tank and the molten metal tank to the set level, the internal pressure of the molten metal tank is increased by the internal pressure adjusting means, and the molten metal is supplied from the stalk into the mold cavity. After low-pressure casting, the internal pressure of the pouring tank is released, the molten metal in the stalk is returned to the pouring tank, and then the internal pressure of the molten metal standby tank is increased, and the molten metal waits until the molten metal in the molten metal tank reaches the set level. By replenishing the molten metal of the tank to the pouring tank, the height of the molten metal surface of the pouring tank is prevented from fluctuating every time casting is performed, and the molten metal supply pressure to the mold fluctuates. Quality variation can be prevented. Moreover, it is only necessary to newly provide a check valve, and it is not necessary to provide a driving means for driving the valve, so that the manufacturing cost of the low-pressure casting machine can be reduced and the entire check valve can be immersed in the molten metal. Therefore, generation of oxides due to contact between the check valve and the molten metal surface can be prevented, and the quality of the molten metal can be improved.

  Here, the check valve is a casing provided in the lower part of the molten metal standby tank, wherein an upper end portion is opened in the molten metal standby tank, a lower end portion is formed in a hemispherical shape, and a lower end of the communication path is formed in the lower end portion. It is a preferred embodiment to provide a check valve having a casing formed with an opening communicating with the end, and a spherical valve body that is accommodated in the casing and can close the opening of the casing. In this case, since the check valve can be configured with a simple structure consisting of a casing and a spherical valve body, the manufacturing cost of the check valve can be reduced, and the check valve structure using gravity makes long-term stable operation. Can be secured.

  Moreover, it is preferable embodiment to provide the said check valve in the molten metal below a Stoke lower end. In this case, since the entire check valve can always be immersed in the molten metal, generation of oxides due to contact between the check valve and the molten metal surface can be reliably prevented, and the quality of the molten metal can be improved.

  The molten metal standby tank is divided into a first molten metal standby tank on the hot water inlet side and a second molten metal standby tank on the molten metal tank side, and a filter is provided in a communication path between the first molten metal standby tank and the second molten metal standby tank, It is also preferable that the internal pressure of the both molten metal standby tanks can be individually adjusted by the internal pressure adjusting means. When such a filter is provided, foreign substances such as oxides contained in the molten metal supplied to the first molten metal standby tank can be removed by this filter, and the quality of the cast product can be further improved. In addition, by configuring the internal pressure of both molten metal standby tanks individually by the internal pressure adjusting means, when the filter is clogged, the internal pressure of the second molten metal standby tank is set to be higher than the internal pressure of the first molten metal standby tank. Adjusting to be higher, the molten metal in the second molten metal standby tank can be made to flow back to the first molten metal standby tank to remove foreign matters such as oxide adhering to the filter, thereby extending the life of the filter. It is possible to reduce the frequency of filter replacement work and to suppress an increase in running cost due to filter replacement.

  Moreover, when providing a filter in this way, the said filter can be arrange | positioned substantially horizontally in the lower part of a 1st molten metal standby tank. When configured in this way, when the foreign material such as oxide clogged in the filter is removed by causing the molten metal to flow backward from the second molten metal standby tank to the first molten metal standby tank, the foreign material is not caught in the communication path, It becomes easy to float on the molten metal surface of a 1st molten metal standby tank, and it becomes possible to remove a foreign material easily with a handle.

  The low-pressure casting method according to the present invention uses the low-pressure casting machine to increase the internal pressure of the pouring tank by the internal pressure adjusting means while supplying a set level of molten metal to the molten metal standby tank and the pouring tank. After supplying the molten metal into the cavity and performing low-pressure casting in the cavity, the internal pressure of the pouring tank is released, the molten metal in the stalk is returned to the pouring tank, and then the internal pressure of the molten metal standby tank is increased. Is provided with a low-pressure casting step of supplying the molten metal in the molten metal standby tank to the pouring tank until it reaches the set level.

  In this low-pressure casting method, every time casting is performed, the molten metal in the molten metal standby tank is replenished to the molten metal tank so that the molten metal in the molten metal tank reaches the set level. It is possible to prevent variations in the quality of cast products due to fluctuations in the supply pressure of the molten metal to the mold by preventing the height from fluctuating. In addition, it is only necessary to newly provide a check valve, and it is not necessary to provide a valve driving means or the like. In addition, since the entire check valve can be immersed in the molten metal, generation of oxide due to contact between the check valve and the molten metal surface can be reliably prevented, and the quality of the molten metal can be improved.

  Here, a low pressure casting machine in which the molten metal standby tank is divided into a first molten metal standby tank on the hot water side and a second molten metal standby tank on the pouring tank side is used, and the internal pressure of the first molten metal standby tank is set to the second molten metal standby. It is a preferred embodiment to provide a cleaning step for cleaning the filter by setting the pressure lower than the internal pressure of the tank and causing the molten metal in the second molten metal standby tank to flow backward to the first molten metal standby tank. If comprised in this way, clogging of the filter by foreign substances, such as an oxide, can be prevented, and the replacement frequency of a filter can be decreased.

  In the low pressure casting process, when the internal pressure in the pouring bath is increased and the molten metal is supplied into the mold cavity, the internal pressure of the pouring bath is set so that the internal pressure of the second molten metal standby bath is equal to or lower than the internal pressure of the pouring bath. It is also a preferred embodiment that the molten metal in the second molten metal standby tank is made to flow back to the first molten metal standby tank. That is, the cleaning of the filter by the reverse flow of the molten metal can be performed separately regardless of the low pressure casting process, but if it is performed as part of the low pressure casting process as in the present invention, the work time of the filter cleaning work is reduced. This is preferable because it can be shortened.

  According to the low-pressure casting apparatus and the low-pressure casting method according to the present invention, every time casting is performed, the molten metal in the molten metal standby tank can be replenished to the molten metal tank so that the molten metal in the molten metal tank reaches a set level. The height of the molten metal surface of the pouring tank is prevented from fluctuating every time, and the quality variation of the cast product due to the fluctuation of the supply pressure of the molten metal to the mold can be prevented. In addition, it is only necessary to newly provide a check valve, and it is not necessary to provide a valve driving means or the like. In addition, since the entire check valve can be immersed in the molten metal, generation of oxide due to contact between the check valve and the molten metal surface can be reliably prevented, and the quality of the molten metal can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the low-pressure casting machine 1 moves up and down a holding furnace 4 having a molten metal standby tank 2 and a pouring tank 3, an upper mold 6 and a lower mold 7 as a mold 5, and an upper mold 6. An upper mold lifting / lowering means 8, a stalk 9 for communicating the pouring tank 3 and the mold 5, a check valve 11 interposed in the communication passage 10 between the molten metal standby tank 2 and the molten metal tank 3, and the molten metal standby tank 2 An internal pressure adjusting means 12 capable of individually adjusting the internal pressure of the pouring bath 3 is provided.

  The holding furnace 4 heats and stores a molten metal made of a metal material such as an aluminum alloy or a magnesium alloy at a constant temperature, and is made of a wall material having heat resistance such as a refractory brick. The holding furnace 4 is partitioned into a molten metal standby tank 2 and a pouring tank 3 by a partition wall 13, and the molten metal standby tank 2 and the pouring tank 3 are each provided with a heater 14 for heating. The upper surface of the molten metal standby tank 2 is closed with a lid 15 so that it can be opened and closed. The upper surface of the molten metal tank 3 is closed with a furnace lid 16, and the molten metal standby tank 2 and the molten metal tank 3 are sealed in a substantially airtight manner. . A communication passage 10 is provided at the lower end of the partition wall 13 to communicate the molten metal standby tank 2 and the pouring tank 3, and a check valve 11 is connected to the end of the communication path 10 on the pouring tank 3 side.

  As shown in FIGS. 1 to 3, the check valve 11 opens and closes a bottomed cylindrical casing 17 whose upper end is opened and whose lower end is hemispherical, and a lower end opening 18 of the casing 17. The check valve 11 allows the molten metal to flow from the molten metal standby tank 2 to the molten metal tank 3, and from the molten metal tank 3 to the molten metal standby tank 2. The molten metal flow is regulated. The casing 17 and the spherical valve body 19 are made of a heat-resistant ceramic material or the like, and are immersed in the melt below the lower end of the stalk 9, that is, below the lower limit level LL of the melt in the pouring tank 3. Is provided. A support member 20 is provided on the lower side of the casing 17, and a partially spherical recess 21 is formed on the upper surface of the support member 20. The casing 17 is supported by the support member 20 with its lower end fitted into the recess 21. ing. The support member 20 is formed with a connection path 22 that communicates the communication path 10 formed in the partition wall 13 with the lower end opening 18 of the casing 17. A press plate 23 extending upward of the casing 17 is provided in the middle of the partition wall 13 in the height direction, and the casing 17 is held between the press plate 23 and the support member 20 so as not to drop off. A cutout portion 24 having an opening width through which the spherical valve body 19 cannot be inserted is formed in the upper portion of the casing 17, and the inside of the casing 17 and the pouring tank 3 are communicated with each other through the cutout portion 24.

  In the check valve 11, when the internal pressure of the molten metal standby tank 2 becomes higher than the internal pressure of the pouring tank 3, the molten metal in the molten metal standby tank 2 passes through the communication path 10 and the connection path 22 as shown in FIG. In addition, the spherical valve body 19 is introduced into the casing 17 while being pushed upward, and is supplied to the pouring tank 3 through the notch 24. However, when the internal pressure of the pouring tank 3 becomes higher than the internal pressure of the molten metal standby tank 2, The spherical valve element 19 is pushed down by the molten metal introduced from the pouring tank 3 through the notch 24, and the lower end opening 18 of the casing 17 is closed by the spherical valve element 19 as shown in FIG. The flow of the molten metal from the hot water tank 3 to the molten metal standby tank 2 is restricted. In addition, as the check valve 11, a valve having an arbitrary configuration can be adopted. Although the casing 17 of the check valve 11 can be formed integrally with the wall of the holding furnace 4, it is possible to reduce the manufacturing cost of the holding furnace 4 by configuring it as a separate member from the holding furnace 4. This is preferable because it can easily cope with replacement of parts of the casing 17 due to wear or the like.

  The upper mold lifting / lowering means 8 will be described. As shown in FIG. 1, a fixed platen 25 is horizontally installed on the upper side of the holding furnace 4, and tie bars 26 are erected at four corners of the fixed platen 25. A base plate 27 is fixed horizontally at the upper end of the tie bar 26, and a guide shaft 28 is inserted through the base plate 27 so as to be movable up and down. A movable platen 29 is supported substantially horizontally at the lower end of the guide shaft 28, and an upper mold 6 is detachably attached to the lower surface of the movable platen 29 via a clamper (not shown). A main cylinder 30 is erected on the base plate 27, a piston rod 30 a of the main cylinder 30 is connected to an upper end portion of the guide shaft 28, and the upper die 6 is supported by the main cylinder 30 together with the movable platen 29 so as to be movable up and down. .

  A stalk 9 extending through the furnace lid 16 and into the pouring bath 3 is inserted and supported at the center of the fixed platen 25, and the lower mold 7 is fixed to the upper surface of the fixed platen 25 via a clamper (not shown). . The upper end portion of the stalk 9 is opened to the pouring gate 7 a of the lower mold 7, and the lower end portion of the stalk 9 is immersed in the molten metal of the pouring tank 3. It is communicated within.

  The internal pressure adjusting means 12 will be described. As shown in FIGS. 1 and 2, a gas body supplying means 35 (not shown) for supplying a non-oxidizing gas such as nitrogen gas or argon gas is provided. Are connected to the pouring tank 3 and the molten metal standby tank 2 via supply pipes 36A and 36B, respectively, and supply valves 37A and 37B are interposed in the middle of both supply pipes 36A and 36B, respectively. Further, exhaust pipes 38A and 38B for releasing the internal pressure are connected to the pouring tank 3 and the molten metal standby tank 2, respectively, and exhaust valves 39A and 39B are interposed in the middle of the exhaust pipes 38A and 38B. And it is comprised so that the pressure of the pouring tank 3 and the molten metal waiting tank 2 can be adjusted separately by opening and closing supply valve 37A, 37B and exhaust valve 39A, 39B.

  The gas body supply means 35 includes a cylinder filled with a non-oxidizing gas and a compressor that pressurizes the non-oxidizing gas, a separating means for separating nitrogen from the atmosphere, and pressurizing the separated nitrogen. Various configurations such as those provided with a compressor to be supplied can be employed. However, the internal pressures of the pouring tank 3 and the molten metal standby tank 2 can be adjusted by a gas body such as an inert gas or air.

Next, the low pressure casting method will be described.
First, the lid 15 is opened, and the molten metal is supplied to the molten metal standby tank 2. At this time, the molten metal supplied to the molten metal standby tank 2 passes through the communication path 10 and the connection path 22, pushes up the spherical valve body 19 of the check valve 11, and is supplied from the check valve 11 to the molten metal tank 3. . Thus, after supplying the molten metal to the molten metal standby tank 2 and the pouring tank 3 to the set level SL, the lid 15 is closed and the molten metal supplied by the heater 14 is heated to the set temperature.

  To perform casting after the molten metal reaches the set temperature, as shown in FIG. 4, the supply valve 37B and the exhaust valves 39A and 39B are closed and the supply valve 37A is opened to increase the internal pressure of the pouring bath 3. Then, the molten metal is supplied into the cavity 31 of the mold 5 through the stalk 9. At this time, as shown in FIG. 3A, the spherical valve body 19 of the check valve 11 is closed to the lower end opening 18 of the casing 17, so that even if the internal pressure of the pouring bath 3 increases, The movement of the molten metal to the molten metal standby tank 2 is prevented, and the molten metal is reliably supplied into the cavity 31 via the stalk 9.

  Thus, after supplying the molten metal into the cavity 31, this state is maintained until the molten metal solidifies. After the molten metal in the cavity 31 is solidified, the supply valve 37A is closed and the exhaust valve 39A is opened. Then, the internal pressure of the pouring tank 3 is lowered to atmospheric pressure, the molten metal in the stalk 9 is returned to the pouring tank 3, and the mold 5 is opened to release the cast product.

  When the next casting is performed, the molten metal is supplied into the cavity 31 by increasing the internal pressure of the pouring tank 3 in the same manner as described above with the mold 5 closed, but used in the previous casting. Since the molten metal surface of the pouring tank 3 is lowered by the amount of the molten metal, it is necessary to increase the internal pressure of the pouring tank 3 as compared with the previous casting. However, when the internal pressure is increased in this way, there is a problem that the quality of the cast product is likely to vary. Therefore, in the present invention, before increasing the internal pressure of the pouring bath 3, as shown in FIG. 5, the exhaust valve 39A and the supply valve 37B are opened, and the supply valve 37A and the exhaust valve 39B are closed, By setting the pouring tank 3 to atmospheric pressure and increasing the internal pressure of the molten metal standby tank 2, the molten metal in the molten metal standby tank 2 is replenished to the molten metal tank 3 through the communication path 10, the connection path 22, and the check valve 11. It will be.

  Thus, after the molten metal is replenished until the molten metal surface of the pouring tank 3 reaches the set level SL, the supply valve 37B and the exhaust valves 39A and 39B are closed and the supply valve 37A is opened as described above, 3 is increased, and the molten metal is supplied into the cavity 31 of the mold 5 through the stalk 9 to perform casting. In this way, in the present invention, the pouring tank 3 is always filled with the molten metal at the set level SL, and it is not necessary to change the internal pressure of the pouring tank 3 during casting every time casting is performed. Can improve the quality.

  When a plurality of casting operations are performed as described above and the molten metal in the molten metal standby tank 2 reaches the lower limit level LL or approaches the lower limit level LL, a new molten metal is added to the molten metal standby tank 2. Will be replenished.

  Next, another embodiment in which the configuration of the low-pressure casting machine 1 is partially changed will be described. The same members as those in the above embodiment are given the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 6 and 7, this low-pressure casting machine 40 is replaced with the holding furnace 4 of the above embodiment, and a first molten metal standby tank on the hot water side divided by a pouring tank 3 and a partition wall 44. 42 and a second molten metal standby tank 43 on the side of the pouring tank 3 are provided, and a communication passage 45 that communicates the first molten metal standby tank 42 and the second molten metal standby tank 43 is provided below the partition wall 44. The filter 46 is provided substantially horizontally in the first molten metal standby tank 42 at the upper position of the communication passage 45, and instead of the internal pressure adjusting means 12 of the above embodiment, the internal pressure of the molten metal tank 3 and both molten metal standby tanks 42, 43 are provided. The internal pressure adjusting means 47 capable of individually adjusting the internal pressure is provided, and lid bodies 48 and 49 for opening and closing the first molten metal standby tank 42 and the second molten metal standby tank 43 are provided in place of the lid body 15. .

  The internal pressure adjusting means 47 will be described. A gas body supply means 35 (not shown) for supplying a non-oxidizing gas such as nitrogen gas or argon gas is provided. The gas body supply means 35 is connected to supply pipes 36A, 36C, 36D. Are connected to the pouring tank 3 and the molten metal standby tanks 42, 43, respectively, and supply valves 37A, 37C, 37D are respectively provided in the middle of both supply pipes 36A, 36C, 36D, and both supply valves 37A, 37C. , 37D are connected to exhaust pipes 38A, 38C, 38D for releasing the internal pressure in the middle of the supply pipes 36A, 36C, 36D on the holding furnace 4 side, and in the middle of the exhaust pipes 38A, 38C, 38D, respectively. Exhaust valves 39A, 39C, and 39D are interposed. And it is comprised so that the internal pressure of the pouring tank 3 and the both molten metal waiting tanks 42 and 43 can be adjusted separately by opening and closing supply valve 37A, 37C, 37D and exhaust valve 39A, 39C, 39D.

  Next, in the low pressure casting method using the low pressure casting machine 40, when the supply valve 37B of the low pressure casting machine 1 in the above embodiment is opened and closed, the supply valves 37C and 37D are opened and closed instead of the supply valve 37B, and the exhaust valve is opened. By opening and closing the exhaust valves 39C and 39D instead of the exhaust valve 39B when opening and closing 39B, low pressure casting can be performed in the same manner as the low pressure casting machine 1. In addition, since the filter 46 is provided in the lower portion of the first molten metal standby tank 42, foreign matter such as oxide mixed in the molten metal supplied to the first molten metal standby tank 42 is filtered by the filter 46. Then, since it supplies to the pouring tank 3 through the 2nd molten metal waiting | standby tank 43, it can prevent a quality fall to the casting product by the foreign material mixed in molten metal. When the supply valve 37A is opened to pressurize the pouring tank 3, the supply valve 37D is opened and the second molten metal standby tank 43 is abbreviated as the pouring tank 3 as shown in FIG. While pressurizing to the same pressure or a little lower pressure, the exhaust valve 39C is opened, and the internal pressure of the first molten metal standby tank 42 is released, so that the molten metal in the second molten metal standby tank 43 is kept in the first molten metal standby state. The foreign matter such as oxide clogged in the filter 46 is discharged back into the tank 42 and discharged into the first molten metal standby tank 42, and the foreign matter is scavenged with a handle or the like, so that the filter 46 can be cleaned. The frequency of replacement work can be reduced, and an increase in running cost due to filter 46 replacement can be suppressed.

  The filter 46 may be cleaned each time casting is performed as described above, or may be performed after performing casting a plurality of times. In addition, the filter 46 can be cleaned periodically or as needed separately from the casting process.

Longitudinal section of low pressure casting machine Top view of the holding furnace with the lid and furnace lid removed (A) is a longitudinal sectional view of the vicinity of the check valve in the closed state, and (b) is a longitudinal sectional view of the vicinity of the check valve in the opened state. Explanatory drawing which shows the state of the molten metal at the time of casting Explanatory drawing which shows the state of the molten metal at the time of the molten metal supply to a pouring tank Plan view of holding furnace with lid and furnace lid removed in low-pressure casting machine of other configuration VII-VII sectional view of FIG. Explanatory drawing explaining the state of the molten metal of the molten metal waiting tank at the time of filter cleaning

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low pressure casting machine 2 Molten metal waiting tank 3 Pouring tank 4 Holding furnace 5 Mold 6 Upper mold 7 Lower mold 7a Top 8 Lifting means 9 Stoke 10 Communication path 11 Check valve 12 Internal pressure adjusting means 13 Partition 14 Heater 15 Cover 16 Furnace lid 17 Casing 18 Lower end opening 19 Spherical valve body 20 Support member 21 Recess 22 Connection path 23 Press plate 24 Notch 25 Fixed platen 26 Tie bar 27 Base plate 28 Guide shaft 29 Movable platen 30 Main cylinder 30a Piston rod 31 Cavity 35 Gas body Supply means 36A Supply pipe 36B Supply pipe 37A Supply valve 37B Supply valve 38A Exhaust pipe 38B Exhaust pipe 39A Exhaust valve 39B Exhaust valve 40 Low pressure casting machine 41 Holding furnace 42 First molten metal standby tank 43 Second molten metal standby tank 44 Partition wall 45 Continuous Passage 46 Filter 47 Internal pressure adjusting means 36C Supply pipe 36D Supply pipe 37C Supply valve 37D Supply valve 38C Exhaust pipe 38D Exhaust pipe 39C Exhaust valve 39D Exhaust valve

Claims (8)

A holding furnace having a molten metal standby tank and a pouring tank;
Stoke communicating the pouring tank and the mold;
A check valve that is interposed in the communication path between the molten metal standby tank and the molten metal tank, allows the flow of molten metal from the molten metal standby tank to the molten metal tank, and regulates the flow of molten metal from the molten metal tank to the molten metal standby tank;
An internal pressure adjusting means capable of individually adjusting the internal pressure of the molten metal standby tank and the pouring tank,
A low pressure casting machine characterized by comprising:   As the check valve, a casing provided in the lower part of the molten metal standby tank, the upper end is opened in the molten metal standby tank, the lower end is formed in a hemispherical shape, and the lower end is at the end of the communication path. The low-pressure casting machine according to claim 1, further comprising a check valve having a casing formed with a communicating opening, and a spherical valve body accommodated in the casing and capable of closing the opening of the casing.   The low pressure casting apparatus according to claim 1 or 2, wherein the check valve is provided in the molten metal below the lower end of the stalk.   The molten metal standby tank is divided into a first molten metal standby tank on the hot water inlet side and a second molten metal standby tank on the molten metal tank side, and a filter is provided in a communication path between the first molten metal standby tank and the second molten metal standby tank, The low pressure casting machine according to any one of claims 1 to 3, wherein the internal pressure of both molten metal standby tanks can be individually adjusted by the internal pressure adjusting means.   The low pressure casting machine according to claim 4, wherein the filter is disposed substantially horizontally in a lower portion of the first molten metal standby tank.   Using the low-pressure casting machine according to any one of claims 1 to 5, in a state in which molten metal at a set level is supplied to the molten metal standby tank and the molten metal tank, the internal pressure of the molten metal tank is increased by the internal pressure adjusting means, and the mold is formed from the stalk. The molten metal is supplied into the cavity, and after low pressure casting is performed in the cavity, the internal pressure of the pouring tank is released, the molten metal in the stalk is returned to the pouring tank, and then the internal pressure of the molten metal standby tank is increased, A low-pressure casting method comprising a low-pressure casting step of replenishing the molten metal in the molten metal standby tank to the molten metal tank until the molten metal reaches the set level.   The low pressure casting machine according to claim 4 or 5, wherein the internal pressure of the first molten metal standby tank is set lower than the internal pressure of the second molten metal standby tank, and the molten metal in the second molten metal standby tank is transferred to the first molten metal standby tank. The low-pressure casting method according to claim 6, further comprising a cleaning step of cleaning the filter by backflow. In the low pressure casting process, when the internal pressure in the pouring bath is increased and the molten metal is supplied into the mold cavity, the internal pressure of the pouring bath is set so that the internal pressure of the second molten metal standby bath is equal to or lower than the internal pressure of the pouring bath. The low-pressure casting method according to claim 7, wherein the molten metal in the second molten metal standby tank is made to flow back to the first molten metal standby tank.

Images