JP2007038264A - Low pressure casting furnace, and low pressure casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low pressure casting furnace capable of preventing gas from leaking from a pressurizing chamber to a tapping chamber and a holding chamber when molten metal in the pressurizing chamber is pressurized and charged into a cavity, and to provide a low pressure casting method. <P>SOLUTION: The low pressure casting furnace 1 comprises: a holding chamber 20; a pressurizing chamber 30; a tapping chamber 40; and a communicating path 50, and the communicating path 50 allows the holding chamber 20, the pressurizing chamber 30 and the tapping chamber 40 to communicate each other. The pressurizing chamber 30 is provided with: a pressurizing apparatus 31 of pressurizing molten metal in the pressurizing chamber 30 by feeding gas into the pressurizing chamber 30; and a tubular member 34. The tubular member 34 is composed of fine ceramics having a porosity of ≤2%. The outer circumferential face of the tubular member 34 is the part of the low pressure casting furnace body 10 including a first wall part 10A and a second wall part 10B and is the part of the inner wall partitioning the pressurizing chamber 30, and is arranged so as to cover the part to be exposed to the gas fed into the pressurizing chamber 30 by the pressurizing means 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a low-pressure casting method and a low-pressure casting furnace, and in particular, a low-pressure casting furnace in which a holding chamber, a pressurizing chamber, and a tapping chamber communicate with each other through a communication path, and a low-pressure casting method performed using the low-pressure casting furnace. About.

  As a low-pressure casting furnace for performing the low-pressure casting method, the holding chamber, the pressurizing chamber, and the hot water chamber are communicated with each other via a communication path, and the molten metal in the holding chamber is communicated with the communication path, the pressure chamber, And the structure which can be poured into a hot water supply room is conventionally known. Japanese Patent Application Laid-Open No. 11-138250 (Patent Document 1) describes a low-pressure casting furnace having this configuration.

In the low-pressure casting furnace described in the publication, the gas in the pressurizing chamber is supplied to fill the mold cavity with the molten metal in the pressurizing chamber. The holding chamber, the pressurizing chamber, the hot water chamber, and the communication passage are respectively formed in the low-pressure casting furnace body. The main body of the low-pressure casting furnace that defines the pressurizing chamber is made of a refractory material such as a ceramic refractory and has a shape capable of raising the pressure to a set pressure with a small amount of gas. With this configuration, an attempt is made to prevent gas from leaking from the pressurizing chamber via the low-pressure casting furnace body that defines the pressurizing chamber.
Japanese Patent Laid-Open No. 11-138250 (pages 2 to 3, FIGS. 1 to 2)

  However, in the conventional low pressure casting furnace described in the above publication, refractory materials such as ceramic refractories constituting the main body of the low pressure casting furnace that defines the pressurizing chamber sufficiently prevent gas from leaking from the pressurizing chamber. I can't prevent it. Therefore, when gas is supplied into the pressurizing chamber and the molten metal in the pressurizing chamber is pressurized and filled into the cavity, the gas actually leaks from the pressurizing chamber to the hot water supply chamber and the holding chamber via the low pressure casting furnace body. Was.

  Since the molten metal in the hot water chamber is filled from the hot water chamber into the cavity of the mold, if a gas flows in, a cast hole is generated in the cast product. Therefore, even if one bubble leaks into the hot water discharge chamber, it becomes a serious problem in the quality of the cast product. In addition, leakage of gas into the holding chamber will not affect the quality of the cast product if the amount is small, but if the amount is large, the pressure in the pressurizing chamber will decrease when the molten metal is filled into the cavity. Adversely affects quality.

  Therefore, the present invention provides a low-pressure casting furnace and a low-pressure casting method capable of preventing gas from leaking from the pressurizing chamber to the hot water chamber and the holding chamber when the molten metal in the pressurizing chamber is pressurized and filled into the cavity. For the purpose.

  In order to achieve the above object, the present invention provides a low pressure casting furnace main body 10, a pressure chamber 30 formed in the low pressure casting furnace main body 10 and provided with a pressurizing means 31, and a molten metal formed in the low pressure casting furnace main body 10. A holding chamber 20 for holding the molten metal, a pouring chamber 40 formed in the low-pressure casting furnace main body 10 and arranged below the mold 3 for supplying the molten metal 2 to the mold 3 and filling it, and the heating chamber The communication passage 50 and the holding chamber 20 are communicated with each other at a communication passage 50 that connects the pressure chamber 30, the holding chamber 20, and the hot water discharge chamber 40 to each other, and a communication portion between the communication passage 50 and the holding chamber 20. A stopper 21 movable between the communication position / blocking position for blocking, and the molten metal 2 in the holding chamber 20 passes through the communication path 50, the communication path 50, the pressurizing chamber 30, and The pressurizing means 31 can supply gas into the pressurizing chamber 30. Thus, the inside of the pressurizing chamber 30 can be pressurized, and the pressurizing chamber 30 and the holding chamber 20 are separated by the first wall portion 10A constituting the low-pressure casting furnace body 10, and the pressurizing chamber 30 and the hot water chamber 40 are separated from each other by a second wall portion 10B constituting the low pressure casting furnace main body 10, and the pressurizing chamber 30 is made of a material having a porosity of 2% or less. The tubular member 34 is provided, and the peripheral surface of the tubular member 34 is a portion of the low-pressure casting furnace main body 10 including the first wall portion 10A and the second wall portion 10B, and defines the pressurizing chamber 30. The low pressure casting furnace 1 is provided so as to cover a portion of the inner wall that is exposed to the gas supplied into the pressurizing chamber 30 by the pressurizing means 31.

  The present invention also provides a low pressure casting method for performing low pressure casting using the low pressure casting furnace 1.

  According to the low pressure casting furnace of claim 1 of the present invention, a tubular member made of a material having a porosity of 2% or less is provided in the pressurizing chamber, and the peripheral surface of the tubular member includes the first wall portion and the second wall portion. It is a portion of the low pressure casting furnace main body including the wall portion, and is a portion of the inner wall that defines the pressurizing chamber, and is disposed so as to cover the portion exposed to the gas supplied into the pressurizing chamber by the pressurizing means. Therefore, when pressurizing the molten metal in the pressurizing chamber and filling the cavity, it is possible to prevent gas from leaking from the pressurizing chamber to the holding chamber and the hot water discharge chamber via the first wall portion and the second wall portion. it can.

  According to the low pressure casting method of the second aspect of the present invention, since the low pressure casting is performed using the low pressure casting furnace of the first aspect, the first wall is formed when the molten metal in the pressure chamber is pressurized and filled into the cavity. Low pressure casting can be performed while preventing gas from leaking from the pressurizing chamber to the holding chamber and the hot water chamber via the first and second walls.

  A low-pressure casting method and a low-pressure casting furnace according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the low-pressure casting furnace 1 includes a low-pressure casting furnace main body 10 made of a ceramic refractory, and the low-pressure casting furnace main body 10 includes a holding chamber 20, a pressurizing chamber 30, a tapping chamber 40, and a communication passage 50. Is formed. The pressurizing chamber 30 and the holding chamber 20 are separated by a first wall portion 10A that constitutes the low-pressure casting furnace main body 10, and the pressurizing chamber 30 and the tapping chamber 40 are the second wall portion 10B that constitutes the low-pressure casting furnace main body 10. Separated by The communication passage 50 is disposed below the holding chamber 20, the pressurizing chamber 30, and the hot water chamber 40, and communicates the holding chamber 20, the pressurizing chamber 30, and the hot water chamber 40 with each other. The low pressure casting furnace main body 10 has a configuration in which an outer periphery is made of a steel plate and a heat insulating material is stretched on the inner side.

  The holding chamber 20 holds the molten metal 2 that is filled in a cavity 3a in a mold 3 to be described later and becomes a cast product. The molten metal 2 in the holding chamber 20 can flow into the pressurizing chamber 30 and the hot water chamber 40 via the communication passage 50. The holding chamber 20 is not connected to the melting furnace, and the molten metal 2 held in the holding chamber 20 is transported from a melting furnace (not shown) by a forklift and injected into the holding chamber 20. The holding chamber 20 is always open to the atmosphere.

  A stopper 21 for communicating / blocking the communication path 50 and the holding chamber 20 is provided in the communication portion 10 a between the communication path 50 and the holding chamber 20 in the holding chamber 20. The stopper 21 has a substantially rod shape as shown in FIGS. 1 and 2 and is disposed vertically above the communication portion 10a. The stopper 21 can be moved in its axial direction, that is, vertically up and down by being controlled by a control device (not shown) having a display output device (not shown).

  The stopper 21 moves vertically downward, and the tip of the stopper 21 closes the communication portion 10a, whereby the communication between the inside of the holding chamber 20 and the communication passage 50 can be blocked. When the tip of the stopper 21 does not block the communication portion 10a, the molten metal 2 can go back and forth between the communication passage 50 and the holding chamber 20 through the communication portion 10a. The position of the stopper 21 when the tip of the stopper 21 is blocking the communication portion 10a corresponds to the blocking position, and the position of the stopper 21 when the communication portion 10a is not blocked corresponds to the communication position.

  As shown in FIGS. 1 and 2, the hot water discharge chamber 40 is disposed below the mold 3, communicates with the cavity 3 a of the mold 3, and supplies the molten metal 2 to the cavity 3 a of the mold 3. The pressurizing chamber 30 includes a pressurizing device 31, a decompressing device 32, a sensor 33, and a tubular member 34. The pressurization device 31 and the decompression device 32 are connected to a control device (not shown). The pressurization device 31 can pressurize the inside of the pressurization chamber 30 by supplying gas into the pressurization chamber 30. The device 32 can depressurize the inside of the pressurizing chamber 30. When the communicating part 10a is closed, the pressurizing device 31 pressurizes the inside of the pressurizing chamber 30 so that the surface of the molten metal 2 in the hot water discharge chamber 40 rises. Further, when the communication part 10 a is not blocked, the pressure chamber 30 is decompressed by the decompression device 32, thereby sucking the molten metal 2 in the holding chamber 20 into the pressure chamber 30 through the communication path 50. It is configured to be able to. The pressurizing device 31 corresponds to a pressurizing unit, and the decompressing device 32 corresponds to a decompressing unit. The control device corresponds to control means and correction means.

  As shown in FIGS. 1 and 2, the sensor 33 includes a cylinder part 33B and a sensor part 33A, and is connected to a control device (not shown). The sensor portion 33A has a substantially rod shape, and can detect that one end is in contact with the molten metal surface, and the other end is located inside the cylinder portion 33B. That is, one end side of the sensor portion 33A protrudes from the one end of the cylinder portion 33B toward the outside of the cylinder portion 33B in the axial direction of the cylinder portion 33B, and the other end side is located inside the cylinder portion 33B. Is movable in the axial direction.

  Therefore, one end of the sensor unit 33A is always in contact with the molten metal surface, and when the molten metal surface position changes, the one end of the sensor unit 33A follows the movement of the molten metal surface to detect a change in the molten metal surface position. it can. Further, the sensor part 33A is separated from the molten metal 2, and the sensor part 33A is temporarily fixed to the cylinder part 33B so as not to move, and the molten metal position is changed so that the molten metal 2 comes into contact with one end of the sensor part 33A. It is comprised so that it can detect that the hot water surface reached | attained the predetermined position. As the sensor 33, a moving electrode type sensor is used, and examples thereof include CE2 manufactured by SMC Corporation (Monosaku with brake).

  The tubular member 34 is made of fine ceramics having a porosity of 2% or less, and the outer peripheral surface of the tubular member 34 has a first wall portion 10A and a second wall portion 10B as shown in FIGS. A portion of the low pressure casting furnace main body 10 including the portion of the inner wall that defines the pressurizing chamber 30 and that is exposed to the gas supplied into the pressurizing chamber 30 by the pressurizing means 31. Has been. Therefore, the shape of the outer peripheral surface of the tubular member 34 cut along the longitudinal direction of the tubular member 34, that is, the vertical direction in FIGS. 1 and 2, is the first wall portion 10A and the second wall cut along the same surface. The portion of the low-pressure casting furnace main body 10 including the portion 10 </ b> B substantially matches the shape of the portion of the inner wall that defines the pressurizing chamber 30. The molten metal surface of the molten metal 2 in the pressurizing chamber 30 is always located on the inner peripheral surface of the tubular member 34.

  At the upper end of the tubular member 34, as shown in FIG. 1, a flange portion 34 </ b> A following the outer surface of the low-pressure casting furnace main body 10 at the position of the opening end of the pressurizing chamber 30 opening to the outside of the low-pressure casting furnace main body 10. Is provided. On the upper side of the flange portion 34A, that is, on the opposite side of the flange portion 34A facing the outer surface of the low pressure casting furnace main body 10, a metal lid 34C is provided via a packing 34B. A through hole is formed at a position in the vicinity of the peripheral edge of the lid 34C. A bolt 34D passes through the through hole, and the bolt 34D is screwed to the outer surface of the low pressure casting furnace main body 10, whereby the lid 34C is pressurized. The chamber 30 is fixed to the low-pressure casting furnace main body 10 with the opening thereof sealed.

  A heater 51 is provided in the communication path 50 at a position from the connection position between the hot water discharge chamber 40 and the communication path 50 to the connection position between the pressurizing chamber 30 and the communication path 50. A heater 22 is also provided near the bottom of the holding chamber 20. These heaters 22 and 51 maintain the molten metal 2 in the communication passage 50, the hot water discharge chamber 40, and the holding chamber 20 at a temperature suitable for casting.

  Next, a low-pressure casting method using the above-described low-pressure casting furnace 1 will be described with reference to the flowcharts of FIGS. 1, 2, and 3. First, the sensor 33 is set to the first predetermined position A before performing the low pressure casting method. Specifically, the sensor portion 33A of the sensor 33 is moved in the axial direction, and fixed to the cylinder portion 33B at the first predetermined position A as shown in FIG. The first predetermined position A, which is the position of the sensor portion 33A of the sensor 33 that is fixed so as not to move, is the amount of the molten metal 2 for filling the cavity 3a once with the pressurized chamber 30 and the continuous chamber 3a. The hot water surface position when stored in the passage 50 and the hot water supply chamber 40.

  Further, the position of the sensor portion 33A is set to be considerably lower than the position B shown in FIG. By setting it low in this way, when the stopper 21 cannot be closed due to some trouble, the mold 3 is not closed by the molten metal 2 flowing from the holding chamber 20 into the hot water discharge chamber 40 through the communication passage 50. It is possible to prevent the molten metal 2 from overflowing from the hot water supply chamber 40. For this reason, the safety | security of casting operation can be improved.

  Next, a communication process is performed. In the communication step, the holding chamber 20, the pressurizing chamber 30, and the hot water chamber 40 are opened to the atmosphere, and the molten metal 2 in the holding chamber 20 is supplied to the communication passage 50 with the stopper 21 as the communication position (S1). At this time, the molten metal 2 flows from the holding chamber 20 into the pressurizing chamber 30 and the hot water chamber 40 through the communication passage 50.

  Next, whether or not the sensor 33 is turned ON within a preset time, that is, the molten metal 2 is supplied from the holding chamber 20 to the communication passage 50, so that the hot water surface position in the pressurizing chamber 30 is raised. Then, a predetermined hot water surface position detecting step for detecting whether or not the first predetermined position A has been reached is performed (S2).

  If the sensor 33 is turned on within a preset time (S2: YES), a pre-pressurization step is performed. In the pre-pressurization step, first, when one end of the sensor portion 33A of the sensor 33 comes into contact with the molten metal surface and the sensor 33 is turned on, the communication portion 10a is closed by the stopper 21, and the communication passage 50 is connected from the holding chamber 20. The supply of the molten metal 2 is stopped (S11). Then, the inside of the pressurizing chamber 30 is sealed.

  Next, a correction process is performed. In the correction process, the sensor portion 33A of the sensor 33 is moved to the cylinder portion 33B, and the molten metal surface position of the molten metal 2 in the pressurizing chamber 30 is measured by the sensor 33 (S12). And based on the measured molten metal surface position, the pressure applied to the molten metal 2 in the pressurizing chamber 30 by the pressurizing device 31 is corrected in the control device (S13). The corrected pressure value is added to the molten metal 2 in the pressurizing chamber 30 by the pressurizing device 31, so that the molten metal surface of the molten metal 2 in the tapping chamber 40 becomes the constant molten metal surface position B (FIGS. 1 and 2). Value. The above is the correction process. And the pre-pressurization which pressurizes the molten metal 2 in the pressurization chamber 30 with the said correct | amended pressure by the pressurization apparatus 31 is performed (S30). As a result, the surface of the molten metal in the pressurizing chamber 30 is lowered to the position B ′ shown in FIG. 1, and the surface of the molten metal in the tapping chamber 40 is raised, as shown in FIG. The position is directly below the mold 3, that is, the constant hot water surface position B. The above is the pre-pressurization step.

  Next, the sand core is set in the mold 3 and the casting preparation for clamping the mold 3 is performed (S31). Next, a filling process is performed. In the filling step, first, the inside of the pressurizing chamber 30 is hermetically sealed, the sensor portion 33A of the sensor 33 is moved to the cylinder portion 33B, and the molten metal 2 in the pressurizing chamber 30 is pressurized by the pressurizing device 31. By performing the filling and pressurization, the molten metal 2 at the constant hot water surface position B is raised in the hot water supply chamber 40 and filled into the cavity 3a in the mold 3 (S32). During the filling and pressurization by the pressurizing device 31, one end of the sensor portion 33A of the sensor 33 moves in the axial direction following the molten metal surface in contact with the molten metal surface, and the position of the molten metal surface is displaced. Continue to detect.

  The displacement of the ideal hot water surface position is predicted in advance and recognized by a control device (not shown). While the molten metal 2 is being pumped from the pressurizing chamber 30, the displacement of the molten metal surface position detected by the sensor 33 continues to be compared with the displacement of the ideal molten metal surface position. On the other hand, an appropriate applied pressure is continuously calculated, and control for correcting the pressure applied to the inside of the pressurizing chamber 30 by the pressurizing device 31 to the appropriate applied pressure is continued. For this reason, when the molten metal 2 is filled, the molten metal 2 in the pressurizing chamber 30 can always be pressurized with an optimum pressure, and the molten metal 2 can be filled into the cavity 3a.

  Next, when the predetermined time has elapsed, the position of the molten metal surface of the molten metal 2 in the pressurizing chamber 30 is measured by the sensor 33. The ideal position of the hot water surface at this time is predicted in advance and recognized by a control device (not shown). The position of the molten metal surface detected by the sensor 33 is compared with the ideal position of the molten metal surface, and an appropriate equilibrium pressure (pour water pressure) is calculated with respect to the position of the molten metal surface. Control is performed to correct the pressure at which the inside of the chamber 30 is pressurized to push the hot water to the appropriate equilibrium pressure. For this reason, the hot water can be performed with an optimal equilibrium pressure. For example, when the hot water level in the pressurizing chamber 30 is higher than the ideal hot water surface position, the pressurizing force applied by the pressurizing device 31 is lowered, and the hot water level in the pressurizing chamber 30 is reduced. When the position is lower than the ideal hot water surface position, the pressurizing device 31 adjusts the pressurizing force to push the hot water higher.

  Next, after the molten metal 2 is cooled to a predetermined temperature, the pressurization of the molten metal 2 in the pressurizing chamber 30 by the pressurizing device 31 is stopped, and the position of the molten metal surface of the molten metal 2 in the pressurizing chamber 30 is again measured. 33. When there is a difference in the position of the molten metal surface, the molten metal 2 leaks from the pressurizing chamber 30, and a control device (not shown) outputs an abnormality display via a display output device (not shown). . Thus, after stopping the pressurization of the molten metal 2 in the pressurizing chamber 30, the position of the molten metal surface of the molten metal 2 in the pressurizing chamber 30 is measured again, so that the pressurizing chamber 30 can be removed from the pressurizing chamber 30. The presence or absence of leakage of the molten metal 2 can be detected. Then, the mold 3 is opened and the cast product is taken out (S33).

  By repeatedly performing the above steps (S1, S2, S11 to S13, S30 to S33), low pressure casting is repeatedly performed, and the amount of the molten metal in the holding chamber 20 decreases. In the communication step, the amount of the molten metal 2 in the holding chamber 20 is so small that the molten metal surface position in the pressurizing chamber 30 does not reach the first predetermined position A, so that the sensor 33 is turned on within a preset time. If not (S2: NO), the sensor 33 is set to the second predetermined position C. Specifically, the sensor portion 33A of the sensor 33 is moved in the axial direction, and fixed to the cylinder portion 33B at the second predetermined position C so as to be immovable as shown in FIG. 2 (S21).

  Next, the inside of the pressurizing chamber 30 is hermetically sealed and the inside of the pressurizing chamber 30 is decompressed by the decompression device 32, whereby the molten metal 2 in the holding chamber 20 is sucked into the pressurizing chamber 30 through the communication portion 10a (S22). ). And a pre-pressurization process is performed. In the pre-pressurization step, as shown in FIG. 2, when the hot water surface in the pressurizing chamber 30 reaches the second predetermined position C, and one end of the sensor portion 33A of the sensor 33 contacts the hot water surface within a predetermined time. (S23: YES), the communication portion 10a is closed by the stopper 21, and the supply of the molten metal 2 from the holding chamber 20 to the communication passage 50 is stopped (S24). At this time, the hot water surfaces of the molten metal in the holding chamber 20 and the hot water supply chamber 40 are at the position C ′ shown in FIG. Next, the pressurizing chamber 30 is opened to the atmosphere (S25). As a result, the hot water surfaces of the molten metal in the hot water supply chamber 40 and the pressurizing chamber 30 are at positions D shown in FIG.

  Next, a correction process is performed. In the correction step, the sensor portion 33A of the sensor 33 is brought into a movable state with respect to the cylinder portion 33B, and the molten metal surface position of the molten metal 2 in the pressurizing chamber 30 is measured by the sensor 33 (S26). Then, based on the measured molten metal surface position, the pressure applied to the molten metal 2 in the pressurizing chamber 30 by the pressurizing device 31 is corrected in the control device (S27). The corrected pressure value is a value at which the surface of the molten metal 2 in the hot water discharge chamber 40 becomes the constant molten metal surface position B by being added to the molten metal 2 in the pressure chamber 30 by the pressurizing device 31. The above is the correction process. Then, the inside of the pressurizing chamber 30 is hermetically sealed, and preliminary pressurization is performed in which the molten metal 2 in the pressurizing chamber 30 is pressurized by the pressurizing device 31 with the corrected pressure (S30). As a result, the molten metal level in the pressurizing chamber 30 is lowered to the position B ″ shown in FIG. 2, and the molten metal surface position in the tapping chamber 40 is raised, as shown in FIG. The position is just below the mold 3, that is, the constant hot water surface position B. The above is the pre-pressurizing step.

  Next, the steps (S31 to S33) are performed in the same manner as described above, and the above steps (S1, S2, S21 to S27, S30 to S33) are repeatedly performed, whereby the low pressure casting is repeatedly performed. The amount of molten metal will further decrease.

  In the case where the amount of the molten metal 2 in the holding chamber 20 is too small and the molten metal surface position of the molten metal 2 in the pressurizing chamber 30 does not rise to the second predetermined position C, in the hot press chamber 40 in the preliminary pressurizing step. The molten metal 2 cannot be set to the constant molten metal surface position B (FIGS. 1 and 2). For this reason, when one end of the sensor portion 33A of the sensor 33 does not contact the molten metal surface within a predetermined time (S23: NO), the control device (not shown) displays that the amount of molten metal in the holding chamber is too small. Output is performed via a display output device (not shown). On the other hand, the worker who performs the casting work injects the molten metal 2 into the holding chamber 20 to make the molten metal 2 in the holding chamber 20 a sufficient amount that can be cast (S28), and the pressure chamber is again opened to the atmosphere. Then, the stopper is opened (S1). Then, the steps (S1, S2, S11 to S13, S30 to S33) are repeated again.

  The tubular member 34 is made of fine ceramics having a porosity of 2% or less, and the outer peripheral surface of the tubular member 34 is a portion of the low-pressure casting furnace main body 10 including the first wall portion 10A and the second wall portion 10B, and a pressurizing chamber. 30 is disposed so as to cover the portion of the inner wall that defines the portion 30 and the portion exposed to the gas supplied into the pressurizing chamber 30 by the pressurizing means 31, so that the inside of the pressurizing chamber 30 is filled in the filling process. When the gas is supplied to pressurize the molten metal 2 in the pressurizing chamber 30 to fill the cavity 3a, the holding chamber 20 and the hot water chamber from the pressurizing chamber 30 through the first wall portion 10A and the second wall portion 10B. Gas can be prevented from leaking to 40.

  Further, since the pre-pressurization step is performed, it is not always necessary to maintain the molten metal surface position of the molten metal 2 in the holding chamber 20 at a position that coincides with the constant molten metal surface position B in the hot water discharge chamber 40. For this reason, it is not necessary to always connect the holding chamber 20 to a melting furnace (not shown) so that the molten metal 2 can always be supplied from the melting furnace to the holding chamber 20, thereby reducing restrictions on the installation place of the low pressure casting furnace 1. Can do. Further, it is not necessary to supply the molten metal 2 into the holding chamber 20 every time the molten metal 2 is filled into the cavity 3a, and the molten metal can be filled a plurality of times by one injection of the molten metal into the holding chamber 20.

  In addition, since the correction process is performed, the molten metal 2 is accurately set to the constant molten metal surface position B in the hot water chamber 40 even when the molten metal surface of the molten metal 2 is not in a desired position in the pressurizing chamber 30. be able to.

  Further, when the amount of the molten metal 2 in the holding chamber 20 is so small that the hot water surface position in the pressurizing chamber 30 does not reach the first predetermined position A detected by the sensor 33 in the communication process, Is closed, and the pressure in the pressurizing chamber 30 is reduced by the pressure reducing device 32, and the molten metal 2 in the holding chamber 20 is sucked into the pressurizing chamber 30 so that the sensor 33 can detect the molten metal surface position of the molten metal 2. Since the molten metal 2 in the holding chamber 20 is reduced, the remaining amount in the holding chamber 20 is small in order to raise the molten metal 2 in the hot water discharge chamber 40 to the constant hot water surface position B even if the molten metal 2 in the holding chamber 20 decreases. Molten metal 2 can be used. For this reason, the effective utilization rate of the molten metal 2 in the holding chamber 20 can be increased, and the frequency of the molten metal supply to the holding chamber 20 can be reduced. In addition, when changing the type of molten metal, it can be performed after reducing the amount of remaining molten metal by casting, so that the working time can be shortened.

  The low-pressure casting method and the low-pressure casting furnace according to the present invention are not limited to the above-described embodiments, and various modifications and improvements can be made within the scope described in the claims. For example, in the present embodiment, the tubular member 34 is made of fine ceramics, but is not limited thereto. For example, it may be made of iron having a porosity of 2% or less, nickel, titanium, or the like. In this case, it is preferable to take measures against melting damage by applying a ceramic coating or the like to the inner peripheral surface of the tubular member.

  Moreover, the cross-sectional shape cut | disconnected by the surface perpendicular | vertical to the longitudinal direction of a tubular member may be what kind of shape. That is, the outer shape of the tubular member may be a cylindrical shape, or may be a prismatic shape such as a triangular prism or a quadrangular prism.

  Further, in the present embodiment, one pressurizing chamber 30 and a hot water supply chamber 40 communicate with one holding chamber 20, and one hot water supply chamber 40 is connected to one mold 3 to perform one casting. However, it is also possible to adopt a so-called multi-piece structure in which a plurality of cast articles are cast by one casting.

  In this case, for example, the communication path is branched at the position a or c shown in FIG. 1, and a plurality of hot water discharge chambers and molds are provided for one holding chamber and one pressurizing chamber, Moreover, what is necessary is just to branch a communicating path in the position of b shown in FIG. 1, and to have two or more hot water supply chambers, a metal mold | die, and a pressurization chamber with respect to one holding chamber.

  Moreover, although the communication part 10a in the low pressure casting furnace 1 according to the present embodiment is arranged at the bottom of the holding chamber 20, it is not limited to this position. For example, the communication portion may be formed at the side surface position of the holding chamber 20 shown in FIG.

  Moreover, the stopper 21 which closes the communication part 10a may not be the structure like the stopper 21 by this Embodiment. It suffices if the communication path 50 can be closed or opened. Moreover, although the hot metal surface position of the molten metal 2 in the hot water supply chamber 40 is set to the fixed hot metal surface position B before the mold clamping, it may be performed simultaneously with the mold clamping or after the mold clamping.

  Moreover, although the moving electrode type sensor was used as the sensor 33, it is not limited to this. For example, a laser sensor or an ultrasonic sensor may be used.

  The low-pressure casting method and low-pressure casting furnace of the present invention are extremely useful in the field of low-pressure casting where high-quality castings are required.

Schematic which shows the low-pressure casting furnace by embodiment of this invention. Schematic which shows the low-pressure casting furnace by embodiment of this invention. The flowchart which shows the low pressure casting method by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low pressure casting furnace 2 Molten metal 3 Mold 3a Cavity 10 Low pressure casting furnace main body 10A 1st wall part 10B 2nd wall part 10a Communication part 20 Holding chamber 21 Stopper 30 Pressurization chamber 31 Pressurization apparatus 32 Decompression apparatus 34 Tubular member 40 Hot water Chamber 50 communication passage

Claims (2)

A low pressure casting furnace body;
A pressurizing chamber formed in the main body of the low pressure casting furnace and provided with pressurizing means;
A holding chamber formed in the low pressure casting furnace main body for holding the molten metal;
A hot water supply chamber formed in the main body of the low-pressure casting furnace and disposed below the mold for supplying molten metal to the mold for filling;
A communication path that connects the pressurizing chamber, the holding chamber, and the hot water chamber to each other;
A stopper that is movable between a communicating position / blocking position for communicating / blocking the communicating path and the holding chamber at a communicating portion between the communicating path and the holding chamber;
The molten metal in the holding chamber can flow into the communication passage, the pressurizing chamber, and the hot water discharge chamber via the communication passage, and the pressurizing means supplies the gas by supplying gas into the pressurizing chamber. A pressure chamber can be pressurized, the pressure chamber and the holding chamber are separated by a first wall portion constituting the low-pressure casting furnace body, and the pressure chamber and the hot water chamber are separated from the low-pressure casting furnace body. In the low pressure casting furnace separated by the second wall part constituting
A tubular member made of a material having a porosity of 2% or less is provided in the pressurizing chamber, and the peripheral surface of the tubular member is a portion of the low-pressure casting furnace main body including the first wall portion and the second wall portion. Low pressure casting characterized in that it is disposed so as to cover a portion of an inner wall that defines the pressurizing chamber and that is exposed to the gas supplied into the pressurizing chamber by the pressurizing means. Furnace.   2. A low pressure casting method comprising performing low pressure casting using the low pressure casting furnace according to claim 1.

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