JP5471993B2 - Molten metal supply method - Google Patents

Description

  The present invention relates to a molten metal supply method for supplying molten metal to a casting machine.

  Conventionally, Patent Document 1 discloses a holding furnace that stores molten metal (molten metal), a hot water supply pipe that protrudes from the inside of the holding furnace to the outside of the holding furnace, and discharges the molten metal inside the holding furnace toward the casting machine. And a molten metal supply device that discharges hot water from the tip of the hot water supply pipe by pressurizing the inside of the holding furnace is described.

  In the molten metal supply method for supplying molten metal to a casting machine using this type of molten metal supply device, there is a problem that the molten metal is easily oxidized in the hot water supply pipe, and the quality of the molten metal is likely to be deteriorated.

  Therefore, conventionally, Patent Document 2 describes a technique for suppressing oxidation of the molten metal by suppressing the contact of the molten metal with an inert gas rich atmosphere in the vicinity of the hot water supply pipe.

JP-A-2-268957 JP-A-6-23510

  However, the prior art disclosed in Patent Document 2 requires the use of an expensive inert gas and also requires a complicated device for supplying the inert gas.

  An object of this invention is to suppress the oxidation of the molten metal in a hot-water supply pipe | tube in view of the said point.

  In order to achieve the above object, the present inventor has examined the oxidation of the molten metal in the hot water supply pipe, and as a result, has found that the fluctuation of the liquid level of the molten metal in the hot water supply pipe is the dominant factor in the progress of oxidation of the molten metal. That is, the present inventors have obtained new knowledge that as the amount of fluctuation in the liquid level of the molten metal in the hot water supply pipe increases, the progress of oxidation of the molten metal is accelerated.

Based on this knowledge, in the invention described in claim 1, the molten metal (1) stored in the furnace (11) is supplied to the hot water supply pipe (12) by increasing the internal pressure of the furnace (11) that stores the molten metal. Including a hot water supply process for flowing out from the upper end side opening of
In the hot water supply process, the amount of fluctuation (ΔH) in the liquid level of the molten metal (1) inside the hot water supply pipe (12) is set to 1 to 75% of the length dimension (L) of the hot water supply pipe (12). It is characterized by that.

  According to this, since the fluctuation amount (ΔH) of the liquid level of the molten metal (1) in the hot water pipe (12) is suppressed to 75% or less, the molten metal (1) in the hot water pipe (12) Oxidation can be suppressed.

  According to a second aspect of the present invention, in the molten metal supply method according to the first aspect, in the hot water supply step, the amount of fluctuation (ΔH) in the height of the liquid level of the molten metal (1) in the hot water supply pipe (12). Is 1 to 50% of the length dimension (L) of the hot water supply pipe (12).

  Thereby, the oxidation of the molten metal (1) in the hot water supply pipe (12) can be further suppressed.

  According to a third aspect of the present invention, in the molten metal supply method according to the first aspect, in the hot water supply step, the amount of fluctuation (ΔH) in the height of the liquid level of the molten metal (1) in the hot water supply pipe (12). Is 1 to 25% of the length dimension (L) of the hot water supply pipe (12).

  Thereby, the oxidation of the molten metal (1) in the hot water supply pipe (12) can be further suppressed.

The invention according to claim 4 includes a pre-level holding step of keeping the internal pressure of the furnace (11) at the pre-level pressure (P0) in the molten metal supply method according to any one of claims 1 to 3,
In the hot water supply step, the internal pressure of the furnace (11) is raised above the pre-level pressure (P0) to allow the molten metal (1) to flow out from the opening on the upper end side of the hot water supply pipe (12), and then the internal pressure of the furnace (11) is pre-leveled. The hot water cutting pressure (P2) is lower than the pressure (P0),
When the hot water cutting pressure (P2) and the pre-level pressure (P0) are expressed by gauge pressure, the hot water cutting pressure (P2) is set to 60 to 90% of the pre-level pressure (P0).

  Thereby, liquid level fluctuation amount ((DELTA) H) can be restrained small, suppressing jumping out of the molten metal (1) by generation | occurrence | production of surge pressure.

  As in the fifth aspect of the invention, in the molten metal supply method of the fourth aspect, if the hot water cutting pressure (P2) is set to 70 to 90% of the pre-level pressure (P0), the liquid level fluctuation amount (ΔH ) Can be kept smaller.

  As in the invention described in claim 6, in the molten metal supply method according to claim 4, if the hot water cutting pressure (P2) is set to 80 to 90% of the pre-level pressure (P0), the liquid level fluctuation amount (ΔH ) Can be further reduced.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure showing the whole molten metal supply device composition in one embodiment of the present invention. It is a figure which shows each operation state of the molten metal supply apparatus of FIG. It is a time chart which shows the internal pressure change of the furnace in the molten metal supply apparatus of FIG. It is a figure explaining the hot_water | molten_metal surface fluctuation | variation in the hot-water supply pipe | tube in the molten metal supply apparatus of FIG.

  FIG. 1 is a diagram illustrating an overall configuration of a molten metal supply apparatus according to the present embodiment. The molten metal supply apparatus is an apparatus for supplying molten metal (molten metal) to the casting machine, and is configured as a molten metal supply apparatus for die casting in the present embodiment. The molten metal supply apparatus of this embodiment can also be expressed as a molten metal supply apparatus.

  As shown in FIG. 1, the molten metal supply device 10 includes a furnace 11 for storing the molten metal 1 and a hot water supply pipe 12 for supplying the molten metal 1 in the furnace 11 to the casting machine. The furnace 11 is formed using, for example, a ceramic refractory and a heat insulating material. In FIG. 1, the up and down arrows indicate the up and down direction (height direction) when the furnace 11 is installed.

  The molten metal 1 is a molten metal obtained by melting a metal material. When producing an aluminum die-cast product, an aluminum alloy ingot is used as the metal material. In addition, aluminum, zinc, magnesium, or the like can be used as the metal material.

  An electric heater 13 is provided in the upper part of the furnace 11 as a heat retaining means for keeping the molten metal 1 at a predetermined temperature. A direct-fire type holding burner may be provided instead of the electric heater 13.

  A temperature sensor (not shown) for detecting the temperature of the molten metal 1 is provided in the furnace 11. Based on the detection signal from the temperature sensor, for example, the output of the electric heater 13 is controlled, and the molten metal 1 is maintained at a predetermined temperature.

  The hot water supply pipe 12 is disposed to be inclined with respect to the horizontal direction, the lower end portion is located in the molten metal 1 in the furnace 11, and the upper end portion protrudes outside the furnace 11 and is connected to the injection sleeve 31 of the casting machine. Yes. In order to prevent the molten metal 1 from being cooled when the molten metal 1 is discharged from the hot water supply pipe 12, an electric heater is incorporated in the hot water supply pipe 12.

  An air pipe 14 is connected to the furnace 11, and a pre-level pressurization valve 15, a pre-level exhaust valve 16, a hot water supply pressurization valve 17, and a hot water supply exhaust valve 18 are provided in parallel to the air pipe 14.

  The pre-level pressurization valve 15 and the pre-level exhaust valve 16 constitute pre-level pressure adjusting means for adjusting the internal pressure of the furnace 11 to the pre-level pressure. When the pre-level pressurization valve 15 is opened, compressed air from a compressed air supply device (not shown) is supplied into the furnace 11 and the internal pressure of the furnace 11 increases. When the internal pressure of the furnace 11 rises above the pre-level pressure, the pre-level exhaust valve 16 is opened to exhaust the compressed air in the furnace 11 to the atmosphere and lower the internal pressure of the furnace 11.

  The hot water supply pressurizing valve 17 and the hot water supply exhaust valve 18 are used during hot water supply operation. When the hot water supply pressurizing valve 17 is opened, compressed air from a compressed air supply device (not shown) is supplied into the furnace 11. The pressure of the compressed air supplied at this time is higher than the pre-level pressure. For this reason, the internal pressure of the furnace 11 further rises from the pre-level pressure, and the liquid level of the molten metal 1 in the hot water supply pipe 12 rises. As a result, the molten metal 1 is discharged from the upper end side opening (molten outlet) of the hot water supply pipe 12 to be in a hot water supply state.

  When the hot water supply is stopped, the hot water supply exhaust valve 18 is opened. As a result, the compressed air in the furnace 11 is exhausted to the atmosphere, and the internal pressure of the furnace 11 decreases, so that the liquid level of the molten metal 1 in the hot water supply pipe 12 is lowered and hot water from the hot water supply pipe 12 is stopped.

  The pre-level pressurization valve 15, the pre-level exhaust valve 16, the hot water supply pressurization valve 17 and the hot water supply exhaust valve 18 are opened and closed by electromagnetic solenoids. The electromagnetic solenoid that opens and closes each of the valves 15 to 18 is controlled by a control device (control means) 19.

  The control device 19 is a microcomputer having a CPU, a RAM, a ROM, an I / O, a timer, etc., and the CPU executes a program in the ROM to execute a desired process.

  A pressure sensor 20 and a hot water supply sensor 21 are connected to the input side of the control device 19. The pressure sensor 20 serves as an internal pressure detection unit that detects the internal pressure of the furnace 11. The hot water supply sensor 21 is provided on the distal end side of the hot water supply pipe 12 and constitutes a molten metal outflow detection means for detecting the outflow of the molten metal from the molten metal outlet of the hot water supply pipe 12.

  Furthermore, operation signals from various operation switches and operation buttons provided on the operation panel 22 are also input to the control device 19. As various operation switches and operation buttons provided on the operation panel 22, for example, a hot water supply preparation button 22a, a hot water supply preparation release button 22b, a hot water supply start button 22c, and the like are provided.

  The controller 19 is supplied with a hot water supply command signal from the control panel 32 of the casting machine.

  Next, the operation in the above configuration will be described. Drawing 2 is a figure showing each operation state of a molten metal supply device. Each operating state of the molten metal supply apparatus includes a steady state shown in FIG. 2A, a pre-level holding state shown in FIG. 2B, and a hot water supply state shown in FIG.

  The steady state shown in FIG. 2A is a state where the internal pressure of the furnace 11 is the same as the atmospheric pressure. Therefore, in the steady state, the liquid level of the molten metal 1 in the hot water supply pipe 12 becomes the same height as the liquid level of the molten metal 1 in the furnace 11.

  The pre-level holding state shown in FIG. 2B is a state in which the internal pressure of the furnace 11 is held at a pre-level pressure higher than atmospheric pressure. In this pre-level holding state, the liquid level of the molten metal 1 in the hot water supply pipe 12 rises compared to the steady state.

  The hot water supply state shown in FIG. 2 (c) is a state where the internal pressure of the furnace 11 has reached a hot water supply pressure higher than the pre-level pressure. In this hot water supply state, the liquid level of the molten metal 1 in the hot water supply pipe 12 further rises from the pre-level holding state, and the molten metal 1 is discharged from the molten metal outlet of the hot water supply pipe 12.

  Switching control between the steady state, the pre-level holding state, and the hot water supply state will be described. When the hot water supply preparation button 22a of the operation panel 22 is pressed in the steady state, the pre-level holding state is entered. Specifically, the control device 19 controls the pre-level pressurization valve 15 and the pre-level exhaust valve 16 based on the detection signal of the pressure sensor 20, thereby maintaining the internal pressure of the furnace 11 at the pre-level pressure.

  When the hot water supply preparation release button 22b is released in the pre-level holding state, the steady state is restored. Specifically, when the control device 19 opens the pre-level exhaust valve 16, the compressed air in the furnace 11 is exhausted into the atmosphere, and the internal pressure of the furnace 11 becomes equal to the atmospheric pressure.

  When the hot water start button 22c of the operation panel 22 is pressed or a hot water supply command signal is received from the control panel 32 of the casting machine in the pre-level holding state, the hot water supply state is entered. Specifically, when the control device 19 opens the hot water supply pressurizing valve 17, the internal pressure of the furnace 11 further increases from the pre-level pressure. Thereby, the liquid level of the molten metal 1 in the hot water supply pipe 12 further rises from the pre-level holding state, and the molten metal 1 is discharged from the molten metal outlet of the hot water supply pipe 12. When the molten metal 1 is discharged from the molten metal outlet of the hot water supply pipe 12, a detection signal from the hot water supply sensor 21 is input to the control device 19.

  In the hot water supply state, the control device 19 determines whether or not the internal pressure of the furnace 11 has reached a hot water supply pressure higher than the pre-level pressure, based on the detection signal of the pressure sensor 20. When it is determined that the internal pressure of the furnace 11 has reached a hot water supply pressure higher than the pre-level pressure, the control device 19 closes the hot water supply pressurizing valve 17. Thereby, the internal pressure of the furnace 11 is maintained at the hot water supply pressure. Note that the control device 19 may determine whether or not the internal pressure of the furnace 11 has reached a hot water supply pressure higher than the pre-level pressure, based on an elapsed time after the detection signal of the hot water supply sensor 21 is input.

  When a predetermined time elapses after the detection signal of hot water supply sensor 21 is input, control device 19 determines that the amount of hot water discharged from molten metal 1 has reached a predetermined amount, and stops the hot water discharged from molten metal 1.

  Specifically, when the control device 19 opens the hot water supply exhaust valve 18, the compressed air in the furnace 11 is exhausted into the atmosphere, and the internal pressure of the furnace 11 decreases. Thereby, since the liquid level of the molten metal 1 in the hot water supply pipe 12 falls below the molten metal outlet of the hot water supply pipe 12, the hot water discharge of the molten metal 1 is stopped. That is, the hot water is drained. At this time, the control device 19 determines whether or not the internal pressure of the furnace 11 has decreased to a hot water cutting pressure lower than the pre-level pressure, based on the detection signal of the pressure sensor 20. When the control device 19 determines that the internal pressure of the furnace 11 has decreased to the hot water cutting pressure, the hot water supply pressurizing valve 17 is closed. Note that the control device 19 may determine whether or not the internal pressure of the furnace 11 has reached a hot water supply pressure higher than the pre-level pressure, based on an elapsed time since opening the hot water supply exhaust valve 18.

  When the hot water supply pressurization valve 17 is closed, the control device 19 controls the prelevel pressurization valve 15 and the prelevel exhaust valve 16 based on the detection signal of the pressure sensor 20, thereby maintaining the internal pressure of the furnace 11 at the prelevel pressure. As a result, the pre-level holding state is restored.

  FIG. 3 is a time chart showing a change in internal pressure of the furnace 11 in a series of operations of pre-level holding state → hot water supply state → pre-level holding state. A solid line in FIG. 3 indicates a change in the internal pressure of the furnace 11 in the present embodiment, and a broken line in FIG. 3 indicates a change in the internal pressure of the furnace 11 in the comparative example.

  In the present embodiment and the comparative example, when the internal pressure of the furnace 11 exceeds 11 kPa (gauge pressure), the molten metal 1 is discharged from the molten metal outlet of the hot water supply pipe 12 (tapping area> 11 kPa), and the pre-level pressure P0 is 10 kPa (gauge pressure) and hot water supply pressure P1 are set to 17 kPa (gauge pressure).

  The hot water cutting pressure P2c in the comparative example is set to 4 kPa (gauge pressure), whereas in the present embodiment, the hot water cutting pressure P2 is set to 8 kPa (gauge pressure). In other words, in the comparative example, the hot water cutting pressure P2c is set to 40% (gauge pressure ratio) of the pre-level pressure P0, whereas in the present embodiment, the hot water cutting pressure P2 is 80% (gauge) of the pre-level pressure P0. Pressure ratio).

  Next, a molten metal supply method (molten metal supply method) using the molten metal supply device (molten metal supply device) of the present embodiment will be described.

  In the pre-level holding step, the internal pressure of the furnace 11 is maintained at the pre-level pressure P0. Next, the molten metal 1 in the furnace 11 is supplied to the casting machine by increasing the internal pressure of the furnace 11 in the hot water supply process.

  In the hot water supply process, the internal pressure of the furnace 11 is raised to a hot water supply pressure P1 higher than the pre-level pressure P0 to cause the molten metal 1 to flow out of the upper end side opening of the hot water supply pipe 12, and then the internal pressure of the furnace 11 is lower than the pre-level pressure P0. The hot water is cut down to the cutting pressure P2.

  As described above, in the present embodiment, the difference between the pre-level pressure P0 and the hot water cutting pressure P2 is reduced as compared with the comparative example. Thereby, since the hot_water | molten_metal surface fluctuation | variation (variation of the liquid level of the molten metal 1) in the hot water supply pipe | tube 12 can be suppressed, the oxidation of the molten metal 1 in the hot water supply pipe | tube 12 can be suppressed.

  This will be described with reference to FIG. The hot water level (liquid level height) in the hot water supply pipe 12 at the time of hot water supply (hot water supply) reaches the maximum hot water level H1 shown in FIG. 4 in both the comparative example and the present embodiment. The maximum hot water level H1 is the same as the height of the molten metal outlet of the hot water supply pipe 12.

  In the comparative example, the hot water level in the hot water supply pipe 12 at the time of hot water cutting (when hot water supply is stopped) drops to the hot water level H2c shown in FIG. 4, whereas in this embodiment, the hot water cutting pressure is lower than that in the comparative example. Therefore, it is lowered only to the hot water level H2 shown in FIG.

  That is, in the comparative example, since the difference between the hot water supply pressure P1 and the hot water cutting pressure P2c is large, the difference ΔHc between the hot water surface level H1 at the time of hot water cutting and the hot water surface level H2c at the time of hot water discharge becomes large, and the inner wall of the hot water supply pipe 12 However, in this embodiment, the difference between the hot water supply pressure P1 and the hot water cutting pressure P2 is smaller than that of the comparative example. The difference ΔH between the surface level H1 and the hot water surface level H2c at the time of pouring can be kept small, and the amount of molten metal to be oxidized can be reduced.

  Specifically, the molten metal oxidation can be satisfactorily suppressed by setting the hot-water surface fluctuation amount ΔH between the hot water supply time and the hot water temperature to 1 to 75% of the length L of the hot water supply pipe 12. The length dimension L of the hot water supply pipe 12 is a dimension obtained by measuring the entire length of the hot water supply pipe 12 as shown in FIG. In the example of FIG. 4, a filter 23 is provided on the lower end side of the hot water supply pipe 12.

  If the molten metal surface fluctuation amount ΔH is suppressed to 1 to 50% of the length dimension L of the hot water supply pipe 12, the molten metal oxidation can be suppressed more satisfactorily. If the molten metal surface fluctuation amount ΔH is suppressed to 1 to 25% of the length dimension L of the hot water supply pipe 12, the molten metal oxidation can be further suppressed.

  More specifically, in this embodiment, the molten metal 1 can be prevented from popping out due to the generation of surge pressure by setting the hot water cutting pressure P2 to 60 to 90% (gauge pressure ratio) of the pre-level pressure P0. The surge pressure is a pressure that is instantaneously generated inside the furnace 11 when the hot water is drained.

  If the hot water cutting pressure P2 is set to 70 to 90% (gauge pressure ratio) of the pre-level pressure P0, it is possible to reliably prevent the molten metal 1 from jumping out due to the generation of surge pressure. If the hot water cutting pressure P2 is set to 80 to 90% (gauge pressure ratio) of the pre-level pressure P0, it is possible to more reliably prevent the molten metal 1 from popping out due to the generation of surge pressure.

  Thus, in the present embodiment, by focusing on the fact that the fluctuation amount ΔH of the liquid surface height of the molten metal 1 inside the hot water supply pipe 12 is a dominant factor in the progress of oxidation of the molten metal 1, the fluctuation amount ΔH is calculated as follows. The oxidation of the molten metal 1 is suppressed by a simple method of keeping it small.

  According to this, since the casting cost can be remarkably reduced as compared with the prior art that suppresses the oxidation of the molten metal using an inert gas as in Patent Document 2, the practical merit is extremely large.

(Other embodiments)
In the above embodiment, compressed air is used to adjust the internal pressure of the furnace 11, but the present invention is not limited to compressed air, and various compressed gases may be used.

1 Molten metal (molten metal)
11 Furnace 12 Hot-water supply pipe L Length of hot-water supply pipe P0 Pre-level pressure P1 Hot-water supply pressure P2 Hot-water cutting pressure ΔH Hot-water level fluctuation amount

Claims (6)

A hot water supply step of causing the molten metal (1) stored in the furnace (11) to flow out from the upper end side opening of the hot water supply pipe (12) by increasing the internal pressure of the furnace (11) storing the molten metal,
In the hot water supply step, the amount of fluctuation (ΔH) in the height of the liquid level of the molten metal (1) inside the hot water supply pipe (12) is 1 to 1 of the length dimension (L) of the hot water supply pipe (12). A molten metal supply method characterized in that the molten metal content is 75%.   2. The molten metal supply method according to claim 1, wherein in the hot water supply step, the fluctuation amount (ΔH) is set to 1 to 50% of a length dimension (L) of the hot water supply pipe (12).   2. The molten metal supply method according to claim 1, wherein in the hot water supply step, the fluctuation amount (ΔH) is set to 1 to 25% of a length dimension (L) of the hot water supply pipe (12). A pre-level maintaining step of maintaining the internal pressure of the furnace (11) at a pre-level pressure (P0),
In the hot water supply step, the internal pressure of the furnace (11) is raised above the pre-level pressure (P0) to cause the molten metal (1) to flow out of the upper end side opening, and then the internal pressure of the furnace (11) Reduce to a hot water pressure (P2) lower than the pre-level pressure (P0),
The hot water cutting pressure (P2) is set to 60 to 90% of the prelevel pressure (P0) when the hot water cutting pressure (P2) and the pre-level pressure (P0) are expressed as gauge pressures. The molten metal supply method according to any one of 1 to 3.   The molten metal supply method according to claim 4, wherein the hot water cutting pressure (P2) is set to 70 to 90% of the pre-level pressure (P0).   The molten metal supply method according to claim 4, wherein the hot water cutting pressure (P2) is 80 to 90% of the pre-level pressure (P0).

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