JP2820895B2 - Method of improving hot water supply accuracy in pre-level hot water supply control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply system for a molten metal in which a molten metal (a molten metal or a molten metal) is supplied to a mold such as a die casting machine by pressurizing a molten metal in a thermal insulation furnace with a gas into the thermal insulation furnace. It is about the method.

[0002]

2. Description of the Related Art Conventionally, various methods are known for supplying molten metal to a mold or a plunger sleeve of a die casting machine. For example, Japanese Patent Publication No. 51-3670
4, JP-A-60-152356, Japanese Utility Model Laid-Open No. 3-85156,
Japanese Patent Publication No. 63-61110, JP-A-2-127555, JP-A-6-23510 and JP-A-6-155005.

[0003] Each of these methods has a proven track record and has played a significant role in improving casting techniques in recent years.
However, efforts to improve productivity and reduce labor have been made for the purpose of improving casting technology and reducing costs.

[0004] When evaluated from such a viewpoint, it can be said that there are many problems to be solved.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in order to improve the casting technique and to reduce the cost and to improve the productivity and reduce the demand for labor saving. In order to respond to the more severe increase, in order to further enhance the technology invented in JP-A-6-155005, use the microcomputer control technology which has been rapidly advanced in recent years, and to increase the accuracy of hot water supply, The purpose is to individually address and solve the variation factors in the span and the variation factors in the short span.

At the same time, another object of the present invention is to prevent the deterioration of the accuracy of hot water supply due to a subtle state change of the inner surface of the hot water supply pipe due to the deposition of an oxide thin film generated each time hot water is supplied. It is an object of the present invention to significantly reduce the frequency of maintenance of the removal of oxides and the like or the time loss in the operation at a portion where the contact is made.

[0007]

Means for Solving the Problems A gas as a compressible fluid is pressurized by a change in the furnace space from the time when the amount of retained molten metal stored in the furnace of the pressurized water heater is the maximum to the time when the amount is small. The following means is provided as claim 1 of the present invention with respect to the tendency of decreasing the amount of hot water supply inevitably accompanying the use as a source, that is, fluctuations in the accuracy of hot water supply.

That is, the pressure in the furnace immediately before the start of individual hot water supply control is measured, and the measured value is stored in advance in a computing unit of the hot water supply control device as a reference pre-level holding pressure value when the molten metal in the furnace is at the reference maximum holding amount. The pressure control is corrected by calculating the relational expression of the following equation 1 using the measured and stored values.

[0009]

(Equation 1)

In a continuous operation in which the molten metal stored in the pressurized hot water supply furnace is supplied to the die casting machine plunger sleeve, the molten metal is provided with a molten metal outlet in contact with a hot water receiving port of the die casting machine plunger sleeve. Except when the molten metal is actually supplied from a hot water supply pipe equipped with a molten metal sensor having a molten metal inlet and detecting the arrival of the molten metal to a fixed position of the molten metal outlet, the molten metal stored in the furnace is used as described above. Error in the short span of the hot water supply amount coming from the individual shift of the pre-level height position at the start of hot water supply caused by holding the pre-level at a height position having a preset constant width of the hot water supply pipe, That is, the following means is provided as claim 2 of the present invention with respect to fluctuations in hot water supply accuracy.

The time from the start of the individual hot water supply control to the time when the molten metal sensor, which is provided at the fixed position of the molten metal outlet of the hot water supply pipe and detects the arrival of the molten metal at the fixed position of the molten metal outlet, detects the molten metal. Then, from the start of the hot water supply control in the hot water supply control for the ten times before the individual hot water supply, which is measured and stored each time, similarly to the measured value, and to the fixed position of the hot water supply pipe melt outlet provided at the fixed position of the hot water supply pipe melt outlet. Using the average value of the time data until the molten metal sensor that detects the arrival of the molten metal of the above-described type, and the average value of the data, the pressure is controlled by the relational expression of the following equation (2).

[0012]

(Equation 2)

[0013] When replenishing molten metal to the pressurized hot water supply furnace from the outside, the continuous hot water receiving apparatus is composed of a continuous hot water receiving pipe, a hot water receiving hopper, and a hot water receiving hopper lid for performing replenishing without stopping continuous operation. With the replenishment of the molten metal, the amount of molten metal in the furnace inevitably increases, the volume of gas held in the furnace decreases, and the furnace pressure rises in inverse proportion to the predetermined height position of the hot water supply pipe. The amount of change in the height of the molten metal held at the pre-level is also larger than that in the normal hot water supply control, and the following means is provided as claim 3 of the present invention for changing the hot water supply accuracy.

A load cell signal value for recognizing the open state of the hot water receiving hopper lid of the continuous hot water receiving apparatus as continuous hot water receiving by a sensor signal of a limit switch or the like and constantly tracking and measuring a quantitative transition of the molten metal in the furnace. The degree of change is compared and determined, and a correction corresponding to the degree of change is calculated by the following relational expression 3 to correct the pressurization control.

[0015]

(Equation 3)

Deterioration of the accuracy of hot water supply due to subtle changes in the state of the inner surface of the hot water supply pipe due to the deposition of an oxide thin film generated each time hot water is supplied, and the frequency of maintenance in the hot water supply pipe or at the connection with the die casting machine plunger sleeve or the like. The following means is provided as claim 4 of the present invention in order to greatly reduce the operational time loss.

In the pressurized hot water supply furnace, an inert gas outlet is disposed toward the molten metal outlet of the hot water supply pipe, and a high-temperature inert gas supplied from an external inert gas supply source via an inert gas heating device is provided. An inert gas supply pipe equipped with a parallel pipe with individual inert gas valves that can open and close the pipe by a signal from the hot water supply control device is additionally equipped to generate thin films such as oxides around the hot water pipe. Suppress and prevent the deterioration of the accuracy of hot water supply due to the subtle state change of the inner surface of the hot water pipe by blowing off the thin film such as the oxide around the hot water pipe immediately after the individual hot water supply operation, and the connection with the inside of the hot water pipe or the die casting machine plunger sleeve Significantly reduce the frequency of maintenance or operational time loss in parts and the like.

[0018]

By implementing the means for solving these problems, the following effects can be obtained. By carrying out the means of the invention based on claim 1 of the present application, the change in the furnace space from the maximum amount to the minimum amount of the retained amount of the molten metal stored in the furnace of the pressurized hot water supply furnace is compressed. By gradually increasing and correcting the inevitable tendency of the amount of hot water supplied due to the use of a gas as a pressurizing source as a pressurizing source, the present invention acts on hot water supply control in order to significantly improve hot water supply accuracy.

By implementing the means of the invention based on claim 2 of the present application, the pre-level height position at the start of hot water supply caused by holding the pre-level at a height position having a predetermined constant width of the hot water supply pipe. In the short span, an error in the hot water supply amount due to the individual deviation of the hot water supply, that is, a change in the hot water supply accuracy is suppressed, and the hot water supply amount in the short span acts as a level.

By implementing the means of the invention based on claim 3 of the present application, the supply of molten metal from the continuous hot water receiving device to the pressurized hot water supply furnace without stopping the continuous operation from the outside is inevitable. Despite the fact that the amount of molten metal in the furnace is increased and the accuracy of the hot water supply fluctuates, the hot water supply amount is corrected, and hot water supply control corresponding to changes in the state of replenishment of the molten metal from outside the furnace It works to perform smoothly.

By implementing the means of the invention based on claim 4 of the present application, it is possible to prevent deterioration of the accuracy of hot water supply due to a subtle state change of the inner surface of the hot water supply pipe due to deposition of an oxide thin film generated each time hot water is supplied. It works to greatly reduce the frequency of maintenance or the loss of time in operation in a pipe or at a connection portion with a plunger sleeve of a die casting machine.

By implementing the means of the invention based on claim 5 of the present application, the change in the furnace space from the time when the retained amount of the molten metal stored in the furnace of the pressurized hot water supply furnace is the maximum to the time when the amount is the minimum is obtained. In order to improve the accuracy of hot water supply by gradually increasing and correcting the inevitable tendency of the hot water supply due to the use of gas as a compressible fluid as a pressurized source, the pre-level height at the start of hot water supply Errors in the hot water supply amount within the short span due to individual deviations in the position, that is, fluctuations in the hot water supply accuracy are suppressed, which acts as a leveling of the hot water supply amount in the short span, and the continuous operation without stopping the continuous operation. With the replenishment of the molten metal from the hot water system, the amount of retained molten metal in the furnace is inevitably increased even though the molten metal is being supplied, and the correction of the amount of molten metal is performed, Responding to changes in the state of supply of molten metal It acts to perform hot water supply control smoothly, prevents deterioration of hot water supply accuracy due to subtle changes in the state of the inside of the hot water supply pipe due to the deposition of an oxide thin film that occurs each time hot water is supplied, and prevents the hot water supply pipe or the die-casting machine plunger sleeve. It works to greatly reduce the frequency of maintenance or the time loss in operation at the connection part.

[0023]

FIG. 1 is a conceptual diagram of a system configuration based on one embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 1 of the present invention, and FIG.
FIG. 3 is a conceptual diagram showing the behavior of the molten metal 1 in the pressurized hot water supply furnace 17 based on one embodiment of a method for improving the accuracy of hot water supply in a pre-level hot water supply control method based on the present invention. An embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method based on the embodiment will be described.

Prior to the start of the casting operation with the die casting machine, a hot water receiving hopper lid of a continuous hot water receiving apparatus composed of a continuous hot water receiving pipe 23, a hot water receiving hopper 24 and a hot water receiving hopper lid 25 in the pressurized hot water supply furnace 17 is provided. 25 is opened, the molten metal 1 is received, and the hot water receiving hopper lid 25 is closed. The amount of the molten metal 1 received is continuously measured by the load cell 22, and data sampled in a constant cycle is transmitted to a control panel (not shown).

When the conditions for starting the casting operation are satisfied, the start of the pre-level control is input and activated by a switch on the control panel (not shown). Immediately, the pre-level pressurizing valve A71 disposed in the conduit of the pressurizing conduit 8 connected to an external pressurizing source (not shown) is opened and the pressurized water heater 1 is opened.
A pressurized gas is supplied from a pressurizing source (not shown) into the inside 7, and the molten metal 1 in the pressurized hot water supply furnace 17 rises in the hot water supply pipe 16, and at the same time, a pressure measuring port is provided in the pressurized hot water supply furnace 17. The pressure in the pressurized water heater 17 is transmitted to the hot water supply control device 5 in the control panel (not shown) via the pressure measurement conduit 4 in which the pressure is measured, and is continuously measured, and the pre-level is maintained from the steady state in FIG. Move to state.

The pressure in the pressurized hot water supply furnace 17 increases, and the hot water supply control in the control panel (not shown) is performed based on the retained amount of the molten metal 1 measured by the load cell 22 and transmitted to the control panel (not shown). When the lower limit of the predetermined width of the pressure for maintaining the pre-level calculated by the apparatus 5 is reached, the pre-level pressurizing valve A71 is closed, and the air supply amount rises in the hot water supply pipe 16 from the pre-level pressurizing valve A71. The pre-level pressurizing valve B72 arranged in the conduit of the pressurizing conduit 8 connected to an external pressurizing source (not shown) in which the behavior of the molten metal 1 to be heated is quiet and stable is opened, and the hot water supply control is performed. When the pre-level control value calculated by the device 5 is reached, the pre-level pressurizing valve B72 is closed, and the pre-level is maintained.

The pressurized water heater 17 is difficult to prevent gas leakage from the sealing surface as a completely sealed structure within an appropriate cost range due to the temperature conditions at the time of its use. Even if the amount is small, the gas inside leaks out and the internal pressure decreases. As a result, the pressurized water heater 1
When the internal pressure of 7 becomes the lower limit value of a certain width of the pre-level holding pressure calculated and set by the hot water supply control device 5, the pre-level pressurizing valve B72 is opened again. Thus, in the pre-level holding state, the pre-level pressurizing valve B7
2 is repeatedly opened and closed.

Even if the pre-level pressurizing valve B72 is closed, the furnace internal pressure rises for some reason and exceeds the upper limit of a certain range of the pressure for maintaining the pre-level calculated by the hot water supply controller 5. When the value reaches the preset value, the pre-level exhaust valve A91 is opened. At this time, the unit discharge amount of the gas discharged from the pre-level exhaust valve A91 is adjusted so that the molten metal 1 in the hot water supply pipe 16 exhibits a stable behavior without large pulsation. When the furnace pressure again reaches the pre-level control value calculated and set by the hot water supply control device 5, the pre-level exhaust valve A91 is closed.

When the die casting machine is ready and a hot water supply request command is issued from the die casting machine to a control panel (not shown), the pressurized water heater 17 shifts from the pre-level holding state to the hot water supply state, and the pre-level pressurizing valve B72. And the pre-level exhaust valve A91 waits for the origin (both are closed and waits for a command), the pressure in the furnace at that time is measured, and the measured value is stored in the arithmetic unit of the hot water supply control device 5 in the control panel (not shown). The reference pre-level holding pressure at the time of holding the reference maximum of the molten metal 1 in the pressurized water heater 17 previously stored in the above-described calculator and measured when the pressurized water heater 17 is installed and adjusted for trial operation. Along with the value, the time required to increase the pressure as the differential pressure time value after the molten metal sensor 1 is detected by the molten metal sensor 18 is calculated by the relational arithmetic expression of the following equation 1. A hot water supply control unit 5 as a control value
Is set to That is, the hot water supply is increased and corrected based on the ratio of the difference from the reference pre-level holding pressure value.

[0030]

(Equation 1)

Here, TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. PDS: Furnace pressure value measured at the start of hot water supply and transmitted to the arithmetic unit of the hot water supply control device in the control panel. PPHI: Reference pre-level holding pressure value at the time of holding the reference maximum of the molten metal in the pressurized water heater. K: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. By the way, the unit of time that is calculated and set for practical use is 10 ms
ec.

In parallel with the above series of controls, the pressurizing valve 7 is opened, the furnace pressure of the pressurizing type hot water supply furnace 17 rises, and the molten metal 1 further rises in the hot water supply pipe 16 from the pre-level holding state to the hot water supply state. And then the molten metal outlet 1 of the hot water supply pipe 16
The molten metal is detected by a molten metal sensor 18 provided in the vicinity of the molten metal 4, and the molten metal is supplied to the plunger sleeve 19 from the molten metal outlet 14. The molten metal 1 is detected by the molten metal sensor 18 and, as described above, the hot water supply control device 5 in the control panel (not shown).
When the time corresponding to the actual differential pressure time value calculated by the arithmetic unit and set as the control value in the hot water supply control device 5 has elapsed, a closing command is issued from the hot water supply control device 5 to the pressure valve 7 and the pressure valve 7 Is closed.

Thereafter, the pressurizing valve 7 is closed for a preset hot water supply timer setting time on a control panel (not shown) based on actual measurement data verified as a correlation value with the required hot water supply amount. The outflow of the molten metal 1 in the pressurized hot water supply furnace 17 is continued by the residual pressure in the pressurized hot water supply furnace 17.

When the set time of the hot water supply timer elapses,
Hot water supply to the plunger sleeve 19 is accurately controlled by the hot water supply control device 5, and when the exhaust valve 9 is opened, the molten metal 1 in the hot water supply pipe 16 returns to the furnace. The amount of the molten metal 1 held in the pressurized hot water supply furnace 17 is measured by the load cell 22 and data is transmitted to a control panel (not shown). The furnace pressure for holding the pre-level is calculated and set based on the transmitted holding amount after the completion of hot water supply, and since the furnace pressure is controlled to be held at the pre-level within a certain range from this value, After the completion of the hot water supply, the pre-level pressurizing valve B72 and the pre-level exhaust valve A91 are again subjected to the pre-level holding control according to the newly calculated pre-level control value, and the hot water supply pipe 16 is moved toward the furnace. The lowered molten metal 1 is held at the pre-level holding height position without completely returning to the furnace.

The quantitative control of the amount of hot water supply is performed by a well-known Japanese Patent Publication No. 51-3.
Based on the proven control method of 6704,
Under the applicant of the present invention, which has been conducting further improvement and development research based on the improvement / development by the original applicant of -36704 and the introduction of technology from the original applicant, as a known technique of the differential pressure control of the furnace internal pressure. Although being established, as described above, the pressurization from an external pressurization source (not shown) is applied as one embodiment of the method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to claim 1 of the present invention. If the gas supply is compensated for at a constant pressure and a constant flow rate, time control can be applied with high precision instead of differential pressure control.

In this manner, the pre-level holding and the hot water supply based on the hot water supply request command from the die casting machine are repeated, and when the holding amount of the molten metal 1 in the pressurized hot water supply furnace 17 becomes less than an appropriate amount, the molten metal replenishment request is issued. 17 or a hot water receiving hopper lid 25 of a continuous hot water receiving apparatus composed of a continuous hot water receiving pipe 23, a hot water receiving hopper 24, and a hot water receiving hopper lid 25 at an appropriate time. It is opened and the molten metal 1 is supplied.

In this case, the weight equivalent to the supplied molten metal 1 is added to the holding amount of the pressurized hot water supply furnace 17, and the load cell 2
2 is measured and transmitted to a control panel (not shown), and the pre-level control is changed to a pre-level control value calculated and set by the hot water supply control device 5 based on the value, and control naturally acts in a direction to lower the furnace internal pressure. On the other hand, if the molten metal 1 is replenished, the pressurized hot water supply furnace 17 having an amount equivalent to the replenished volume is provided.
As the gas volume of the gas is compressed, the pressure increases. These two conditions cause the necessity of releasing the gas in the pressurized hot water supply furnace 17 and reducing the pressure at the same time as the supply of the molten metal from the continuous hot water receiving apparatus starts.

The required unit release amount of gas in the pressurized water heater 17 required in this case is determined by the normal pre-level control. Even if the pre-level pressurizing valve B72 is closed, the furnace internal pressure rises for some reason. When the pressure for maintaining the pre-level, which is calculated and set by the hot water supply control device 5, exceeds the upper limit value of the certain width, the amount of the unit released from the pre-level exhaust valve A 91 that is opened becomes larger. Therefore, when the hot water receiving hopper lid 25 of the continuous hot water receiving device is opened, it is determined that the operation of replenishing the molten metal 1 from the continuous hot water receiving device is started, and the valve used for the pre-level exhaust in the pre-level control is set. The pre-level exhaust valve A91 is switched to the pre-level exhaust valve B92 which is set to an appropriate unit discharge amount in accordance with the increased unit discharge amount as described above.

Thereafter, the hot water receiving hopper lid 25 of the continuous hot water receiving apparatus
Is closed, the valve used for the pre-level exhaust in the pre-level control is returned from the pre-level exhaust valve B92 to the pre-level exhaust valve A91. Thus, the pre-level holding control and the hot water supply control are repeated again.

Next, one embodiment of a method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to claim 2 of the present invention will be described with reference to FIGS.

In the process of repeating a series of controls in the same manner as described in the embodiment of the method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to the first aspect of the present invention, the die casting machine is ready and illustrated. A hot water supply command of the die casting machine is issued to the control panel that is not in operation, and the pressurized hot water supply furnace 17 shifts from the pre-level holding state to the hot water supply state. Is performed.

When the pressurizing valve 7 is opened upon the start of the individual hot water supply control, the molten metal 1 rises from the pre-level holding position in the hot water supply pipe 16 and the hot water supply pipe provided at a fixed position of the molten metal outlet 14 of the hot water supply pipe 16. The time until the molten metal sensor 18 for detecting the arrival of the molten metal 1 to the fixed position of the molten metal outlet 14 detects the molten metal 1 (that is, the individual molten metal sensor detection time) is measured. From the start of the hot water supply control in the 10 hot water supply controls before the individual hot water supply that has been measured and stored, the molten metal 1 is moved to the fixed position of the molten metal outlet 14 of the hot water supply pipe 16 installed at the fixed position of the molten metal outlet 14 of the hot water supply pipe 16.
Using the average value of the time data until the molten metal sensor 18 that detects the arrival of the molten metal 1 detects the molten metal 1 (that is, the average value of the detection time of the previous 10 shot molten metal sensor), the pressure is calculated by the following relational expression 2 Correct control. That is, an individual shift of the pre-level height position at the start of hot water supply caused by holding the pre-level at a predetermined height position of the hot water supply pipe 16 is recognized as a shift of the molten metal sensor detection time. The hot water supply is increased or decreased based on the ratio of the difference from the average value of the previous 10 shots.

[0043]

(Equation 2)

Here, TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. TEKAV: Average value of the previous 10 shot molten metal sensor detection time. TEK: Individual molten metal sensor detection time. F: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. By the way, the unit of time that is calculated and set for practical use is 10 ms
ec.

That is, in claim 2 of the present invention, the following equation 4 is obtained by combining the equation 1 and the equation 2 in claim 1 of the present invention.

[0046]

(Equation 4)

Here, TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. PDS: Furnace pressure value measured at the start of hot water supply and transmitted to the arithmetic unit of the hot water supply control device in the control panel. PPHI: Reference pre-level holding pressure value at the time of holding the reference maximum of the molten metal in the pressurized water heater. K: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. TEKAV: Average value of the previous 10 shot molten metal sensor detection time. TEK: Individual molten metal sensor detection time. F: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. By the way, the unit of time that is calculated and set for practical use is 10 ms
ec.

Then, the molten metal 1 is detected by the molten metal sensor 18 and the molten metal flows out and is supplied to the plunger sleeve 19 from the molten metal outlet 14.

The molten metal 1 is detected by the molten metal sensor 18,
As described above, when the actual differential pressure time value calculated by the arithmetic unit of the hot water supply control device 5 in the control panel (not shown) and set as a control value is reached, the hot water supply control device 5 sends the pressure valve 7
Is issued, and the pressurizing valve 7 is closed.

Thereafter, the pressurizing valve 7 is closed for a preset hot water supply timer setting time on a control panel (not shown) based on actual measurement data verified as a correlation value with the required hot water supply amount. The outflow of the molten metal 1 in the pressurized hot water supply furnace 17 is continued by the residual pressure in the pressurized hot water supply furnace 17.

Thereafter, the control according to claim 1 of the present invention continues, and the state again returns to the pre-level holding state. Thus, the pre-level holding and the hot water supply based on the hot water supply request command from the die casting machine are repeated.

Next, one embodiment of a method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to claim 3 of the present invention will be described with reference to FIGS.

A series of controls is repeated in the same manner as described in the embodiment of the method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to the first aspect of the present invention. When the holding amount of the hot water falls below an appropriate amount, a molten metal replenishment request is issued from a control panel (not shown) of the pressurized hot water supply furnace 17 or, at an appropriate time, the continuous hot water receiving pipe 23, the hot water receiving hopper 24, and the hot water receiving hopper lid. 25, the hot water receiving hopper lid 25 of the continuous hot water receiving apparatus is opened to supply the molten metal 1 and the following control is performed.

If the hot water supply control device 5 of the control panel (not shown) recognizes the open state of the hot water receiving hopper lid 24 of the continuous hot water receiving apparatus by a sensor signal of a limit switch (not shown) or the like, the hot water is being received. Load cell 22 for constantly tracking and measuring the quantitative transition of molten metal 1 in pressure type hot water supply furnace 17
Then, the degree of change of the measurement signal value is compared and determined, and a correction corresponding to the degree of change is calculated by the following relational expression 3 to correct the pressurization control. That is, according to the amount of supply to the pressurized water heater 17, the furnace pressure naturally increases more than necessary and the amount of hot water increases.

[0055]

(Equation 3)

Here, TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. J: a constant that is determined and adjusted at the time of trial operation adjustment based on the degree of change in the measured signal value from the load cell during continuous hot water reception and previously stored in the arithmetic unit. By the way, there are three kinds of constants: a zero value when the molten metal is not replenished even though the hot hopper lid is opened, and two constant values to be selected based on the amount of unit time of replenishment. Is determined from the value of. The unit of time calculated and set for practical use is 10 msec.

That is, in claim 3 of the present invention, the following equation 5 is obtained by combining equation 1 and equation 3 in claim 1 of the present invention. In this case,
Equation 1 and Equation 3 are not simply added together, but the correction of Equation 3 is involved in the state of addition and correction in Equation 1; Is formed.

[0058]

(Equation 5)

Here, TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. J: a constant that is determined and adjusted at the time of trial operation adjustment based on the degree of change in the measured signal value from the load cell during continuous hot water reception and previously stored in the arithmetic unit. By the way, there are three kinds of constants: a zero value when the molten metal is not replenished even though the hot hopper lid is opened, and two constant values to be selected based on the amount of unit time of replenishment. Is determined from the value of. PDS: Furnace pressure value measured at the start of hot water supply and transmitted to the arithmetic unit of the hot water supply control device in the control panel. PPHI: Reference pre-level holding pressure value at the time of holding the reference maximum of the molten metal in the pressurized water heater. K: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. The unit of time calculated and set for practical use is 10 msec.

FIG. 2 is a conceptual diagram of a system configuration based on one embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 4 of the present invention, and FIG. 3 is a pre-level hot water supply control method according to claim 1 of the present invention. FIG. 5 is a conceptual diagram showing the behavior of the molten metal in the pressurized hot water supply furnace based on one embodiment of the method for improving hot water supply accuracy in the present invention. One embodiment of the method for improving hot water supply accuracy in the pre-level hot water supply control method according to claim 4 of the present invention. One embodiment of a method for improving the accuracy of hot water supply in a pre-level hot water supply control method according to claim 4 of the present invention, which can also be applied as a conceptual diagram showing the behavior of molten metal 1 in pressurized hot water supply furnace 17 based on an example, with reference to the accompanying drawings. An example will be described.

A series of hot water supply control is repeated in the same manner as described in the embodiment of the method for improving hot water supply accuracy in the pre-level hot water supply control method according to claim 1 of the present invention. A hot water supply furnace 17 is provided with a melt outlet 14 of a hot water supply pipe 16.
An inert gas outlet is disposed toward the apparatus, and the supply of a high-temperature inert gas supplied from an external inert gas supply source (not shown) via an inert gas heating device (not shown) is not shown. A pipe having a replacement inert gas valve 21 which can be opened and closed by a signal from the hot water supply control device 5 in the control panel, and a high temperature inert gas supply by opening and closing the pipe similarly. An inert gas supply pipe 20 having a pipe line having a blowing inert gas valve 31 that can be blown in parallel is additionally provided. These pipes perform a control operation described later in the above-described series of hot water supply control processes. Do.

When a pre-level control start command is issued from a control panel (not shown), the pre-level control is executed in parallel with the execution of the pre-level control according to the first embodiment of the present invention. Is connected to an external inert gas supply source (not shown) and has a molten metal outlet 14 in contact with the molten metal receiving port of the plunger sleeve 19, and has a molten metal inflow port in the stored molten metal 1 of the pressurized hot water supply furnace 17. One of the replacement inert gas valves 21 arranged in parallel in the conduit of the inert gas supply pipe 20 in which the inert gas outlet is disposed toward the molten metal outlet 14 of the hot water supply pipe 16 having the opening 15 is opened. Then, a high-temperature inert gas is supplied to the vicinity of the molten metal outlet 14, and the state shifts from the steady state in FIG. 3 to the pre-level holding state. Then, the hot water supply by the pressurized hot water supply furnace 17 is repeated as in the above-described embodiment according to the first aspect of the present invention, and during this time, the inert gas is continuously supplied to the vicinity of the molten metal outflow port 14 and the hot water supply pipe 16 has the above-described configuration. The generation of thin films such as oxides around the melt outlet 14 is suppressed.

The blow-off inert gas valve 31 arranged in parallel with the other inert gas supply pipe 20 is used to control the molten metal 1 in the process of hot water supply control based on a hot water supply command from a die casting machine. When the time corresponding to the actual differential pressure time value calculated by the calculator of the hot water supply control device 5 in the control panel (not shown) and set as the control value has passed, the hot water supply control device 5 7
And a pressurizing valve 7 is closed.
The pressurized water heater 17 remains open after the pressurizing valve 7 is closed for a preset hot water supply timer setting time on a control panel (not shown) based on actual measurement data verified as a correlation value with the required hot water supply amount. The flow of the molten metal 1 in the furnace is continued by the residual pressure in the pressurized hot water supply furnace 17, and the set time of the hot water supply timer elapses, and the hot water supply to the plunger sleeve 19 is accurately controlled by the hot water supply control device 5. The exhaust valve 9 is opened at the same time as the exhaust valve 9 is opened, and a sufficient amount of high-temperature inert gas is supplied through the conduit of the inert gas supply pipe 20 to blow off a thin film such as oxide around the hot water supply pipe 16. It is supplied to the vicinity of the outlet 14.

Then, the thin film such as oxide around the molten metal outlet 14 of the hot water supply pipe 16 is blown off, thereby preventing deterioration of the hot water supply accuracy due to a subtle state change of the inner surface of the hot water supply pipe 16. Alternatively, the frequency of maintenance or the time loss in operation at a portion where the die casting machine plunger sleeve 19 is engaged is greatly reduced.

The fact that the temperature of the inert gas is high and the position of the inert gas outlet located near the melt outlet 14 are very important factors. That is, when the temperature of the inert gas supplied here is not high near the melting point of the molten metal 1, the molten metal 1 is solidified as a thin film in the vicinity of the molten metal outlet 14 in a solid-liquid mixed state which is not solidified as a thin film. If the position of the inert gas outlet is not appropriate, foreign matter masses which are inconvenient to be present beyond the thin film at an undesired position in the hot water supply pipe 16 may be formed if the position of the inert gas outlet is not appropriate. It could even be a nucleus to do.
This is also a matter that has come to my mind intensely from the experience of the inventor's repeated experiments.

From such a viewpoint, Japanese Patent Laid-Open No.
The technical content of "Prevent clogging due to growth of burrs at the hot water supply port" disclosed in 106330 is practical in terms of temperature conditions of supply gas and uncertainty of position due to movability of the discharge port, and further, timing of the discharge. I have to ask big questions. Further, the present inventor disclosed in Japanese Patent Application Laid-Open No.
Unless a low oxygen concentration condition under the conditions disclosed in US Pat. No. 5,005,005 is created, there is no doubt that the deposited material will gradually and surely become a laminated deposit that is not merely a thin film.

In this respect, the invention based on claim 4 of the present invention
It has been established based on trial and error of experiments repeated over a long period of time since the inventor of the present invention disclosed the invention in JP-A-6-155005, and can be said to be a very reliable and important technique in practical use.

Finally, an embodiment according to claim 5 of the present invention will be described. FIG. 2 is a conceptual diagram of a system configuration based on one embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 4 of the present invention, and FIG. 3 is a hot water supply accuracy in a pre-level hot water supply control method according to claim 1 of the present invention. FIG. 5 is a conceptual diagram showing the behavior of the molten metal 1 in the pressurized hot water supply furnace 17 based on one embodiment of the improvement method. Claim 5 of the present invention relates to the accuracy of the hot water supply of Claims 2, 3 and 4. Since the improvement methods are combined, FIGS. 2 and 3 are appropriate as the related drawings as one embodiment according to claim 5 of the present invention.

Basically, the method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to claim 5 of the present invention is, as described above, a pressurized hot water supply furnace based on the method for improving hot water supply accuracy in the pre-level hot water supply control method of claim 1. In the course of the hot water supply control of the seventeenth aspect, the correction according to the second and third aspects is carried out each time, and furthermore, the method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to the fourth aspect, that is, the outside by the blow-off inert gas valve 31. A high-temperature inert gas supplied from an inert gas supply source (not shown) through an inert gas heating device (not shown) is oxidized around the hot water supply pipe 16 through a pipe of the inert gas supply pipe 20. A control operation for supplying a sufficient amount of the thin film such as an object to the vicinity of the molten metal outlet 14 is added.

In other words, in one embodiment according to claim 5 of the present invention, the following equation (6), which is obtained by combining Equations (4) and (5), is formed as a correction system operation equation, is operated, and is corrected. A high-temperature inert gas supplied from an external inert gas supply source (not shown) by a blowing inert gas valve 31 via an inert gas heating device (not shown) is supplied to the inert gas supply pipe 20 through a line. This can be described as a method of improving the accuracy of hot water supply in a pre-level hot water supply control method in which a control operation in which a thin film of oxide or the like around the hot water supply pipe 16 is blown off through the hot water supply pipe 16 and the control operation is performed without contradiction.

[0071]

(Equation 6)

Here, TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. J: a constant that is determined and adjusted at the time of trial operation adjustment based on the degree of change in the measured signal value from the load cell during continuous hot water reception and previously stored in the arithmetic unit. By the way, there are three kinds of constants: a zero value when the molten metal is not replenished even though the hot hopper lid is opened, and two constant values to be selected based on the amount of unit time of replenishment. Is determined from the value of. PDS: Furnace pressure value measured at the start of hot water supply and transmitted to the arithmetic unit of the hot water supply control device in the control panel. PPHI: Reference pre-level holding pressure value at the time of holding the reference maximum of the molten metal in the pressurized water heater. K: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. TEKAV: Average value of the previous 10 shot molten metal sensor detection time. TEK: Individual molten metal sensor detection time. F: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. The unit of time calculated and set for practical use is 10 msec.

In the first aspect of the present invention, if the die casting machine is ready and a hot water supply request command is issued from the die casting machine to a control panel (not shown), the pressurized water heater 17 is switched from the pre-level holding state to the hot water supply state. Then, the pre-level pressurizing valve B72 and the pre-level exhaust valve A91 wait for the origin (both are closed and wait for a command), the furnace pressure at that time is measured, and the measured values are stored in a control panel (not shown). The data is transmitted as data to the arithmetic unit of the hot water supply control device 5, measured at the time when the pressurized hot water furnace 17 is installed and adjusted for trial operation, and is measured in advance in the molten metal 1 in the pressurized hot water furnace 17 stored in the arithmetic unit. Equation 1 together with the reference pre-level holding pressure value when the reference maximum is held
Is calculated as the differential pressure time value after the molten metal sensor 1 is detected by the molten metal sensor 18, and is set in the hot water supply control device 5 as a control value. The correction of the increase in the amount of hot water supply is performed based on the ratio of the difference.

Here, the change in the furnace pressure at the time when the hot water supply request command from the die casting machine is issued each time of the pressurized hot water supply furnace 17 and the pressurized hot water supply at the time when the hot water supply request command from the die casting machine is issued each time. Since it can be said that the change in the weight of the molten metal 1 stored in the furnace 17, that is, the change in the measured value measured by the load cell 22, has an inversely proportional relationship, the arithmetic correction is performed by using the following equation (7) instead of equation (1). As a result, the same effect is naturally achieved.

[0075]

(Equation 7)

TP: Actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. WPHI: Measured value of the reference load cell at the time of maintaining the reference maximum of the molten metal in the pressurized water heater. WDS: Load cell measurement value measured at the start of hot water supply control and transmitted to the arithmetic unit of the hot water supply control device in the control panel. K: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. The unit of time calculated and set for practical use is 10 msec.

Incidentally, the above-mentioned "K: variable constant to be increased / decreased by the setting device on the control panel in accordance with the required hot water supply amount" has a basic role of a variable constant which is not different from K in equation (1). If compared from a value aspect, the same value is not set because it is a value that is preliminarily empirically defined based on actually measured data according to the required hot water supply amount.

Accordingly, the correction formulas described in the second, third, and fifth formulas, formulas 4, 5, and 6
It is naturally possible to replace the equation (1) with the relational operation expression based on the load cell measured value, as in the case where the equation (1) is replaced by the equation (7).

The hot water supply method of supplying the molten metal flowing out of the hot water supply pipe to the plunger sleeve through a gutter without using the hot water supply method as in the invention of Japanese Patent Application Laid-Open No. 2-127555 is also used. Naturally, the method for improving the accuracy of hot water supply in any of the pre-level hot water supply control methods according to the present invention can be effectively applied.

When the length of the hot water supply pipe 16 provided from the combined structure of the die casting machine and the pressurized hot water supply furnace 17 is increased, there is a risk that the molten metal 1 in the hot water supply pipe 16 is cooled and solidified depending on the length. In some cases, the outside of the hot water supply pipe 16 may be forcibly heated. In addition, as equipment for heating the outside of the hot water supply pipe 16, a ceramic fiber having both heat resistance and heat insulation effects is formed from the surrounding environment of the hot water supply pipe 16, that is, the structure near the hot water receiving port of the plunger sleeve 19 of the die casting machine. A structure in which a heating element is embedded is effective.

[0081]

As described above, according to the present invention, the invention of Japanese Patent Application Laid-Open No. 2-127555 by the applicant of the present invention has opened up a great possibility in view of the future development of casting technology such as die casting technology. Is JP-A-6-15
The invention of 5005 can be further developed.

That is, Japanese Patent Application Laid-Open No. 2-127
In the case of the invention of No. 955 and the invention of Japanese Patent Application Laid-Open No. 6-155005, while a great effect on the progress of the casting technology and the improvement of the product quality is recognized, the improvement of the casting technology and the cost reduction required daily are the main objects. Efforts to improve productivity and demand for labor savings are becoming finer and more stringent.

For example, regarding the accuracy of hot water supply, that is, the accuracy of hot water supply weight, the invention disclosed in Japanese Patent Application Laid-Open No. 2-127555 and
In the case of the invention of -155005, the continuous weight was about ± 3.5% in a general weight, and about ± 5.0% in a hot water supply of 500 g or less. However, what is required is a technology developed in various ways based on Japanese Patent Publication No. 51-36704, for example, Japanese Patent Application Laid-Open No. Hei 5-
According to 15966, the general hot water supply amount is ± 1.8%, and when the hot water supply amount is 500 g or less, ± 2.5% is realized as a normal state. However, the same hot water supply accuracy is required to be realized.

With respect to such a required level, the implementation of claim 1 of the present invention provides a general hot water supply of ± 3.0% and a hot water supply of 500%.
g and below 3.8 g are realized as normal, and according to claims 2, 3 and 4, the general hot water supply is generally 2.5% and the hot water supply 500 g or less is normally realized 3.0%. According to the fifth aspect of the present invention, a general hot water supply amount is ± 2.0% and a hot water supply amount is 500 g or less.
2.1% can be realized as normal.

Further, while the implementation of the invention of claim 4 and the course of the invention of claim 5 are of course affected,
Techniques developed in various ways based on 36704, for example, Japanese Patent Application Laid-Open No. H5-15966 filed by the present applicant.
The frequency of maintenance of removal of oxides and the like in a hot water supply pipe or at a portion where a plunger sleeve is connected to a die casting machine is approximately once every two hours.
In the case of the invention of No. 05, it was improved drastically from eight hours to once every ten hours, and, as a matter of course, the operational time loss was greatly reduced.

As described above, according to the present invention, in order to cope with finer and more severe demands for efforts to improve productivity and labor saving for the purpose of improving casting technology and reducing costs, the invention was disclosed in Japanese Patent Application Laid-Open No. Hei 6-155005. The improved technology has been further improved, and the accuracy of hot water supply has been improved, and the respective problems of the fluctuation factor in the long span and the fluctuation factor in the short span have been solved.

[0087]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a system configuration based on an embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 1 of the present invention.

FIG. 2 is a conceptual diagram of a system configuration based on one embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 4 of the present invention.

FIG. 3 is a conceptual diagram showing behavior of molten metal in a pressurized hot water supply furnace based on one embodiment of a method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 1 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molten metal 2 Heat source 3 Pressure measuring port 4 Pressure measuring conduit 5 Hot water supply control device 6 Pressurizing port 7 Pressurizing valve 8 Pressurizing conduit 9 Exhaust valve 10 Exhaust port 11 Exhaust conduit 12 Furnace port 13 Furnace lid 14 Melt outlet 15 Melt Inlet 16 Hot water supply pipe 17 Pressurized hot water supply furnace 18 Molten metal sensor 19 Plunger sleeve 20 Inert gas supply pipe 21 Replacement inert gas valve 22 Load cell 23 Continuous hot water receiving pipe 24 Hot water receiving hopper 25 Hot water receiving hopper lid 31 Inactive for blowing off Gas valve 71 Pre-level pressurizing valve A 72 Pre-level pressurizing valve B 91 Pre-level exhaust valve A 92 Pre-level exhaust valve B

(Equation 7)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B22D 39/06

Claims (5)

(57) [Claims] An apparatus for storing a molten metal, a heat source for keeping the temperature of the stored molten metal constant, and a load cell for constantly tracking and measuring the quantitative change of the stored molten metal are provided. A pressure measuring port having a pressure measuring port is connected to a hot water supply control device that optimally controls the amount of hot water supplied to the outside of the stored molten metal by controlling to an appropriate pressure condition through a pressure measuring conduit. Via a pressurizing conduit having a pressurizing valve, a pre-level pressurizing valve A and a pre-level pressurizing valve B capable of opening and closing three juxtaposed pipes respectively according to a signal from the hot water supply control device. The exhaust valve, the pre-level exhaust valve A, and the pre-level exhaust valve A are connected to an external pressurizing source, are connected to the exhaust port, and can respectively open and close three pipes arranged side by side by a signal from the hot water supply control device. A continuous exhaust pipe having a level exhaust valve B, a continuous hot water receiving pipe, a hot water receiving hopper, and a hot water receiving hopper lid capable of replenishing the molten metal from the outside without stopping the continuous operation; A hot water device is installed and has a furnace port for cleaning the inside and a furnace lid capable of sealing the furnace port. When the molten metal is supplied to the die casting machine plunger sleeve, the hot water is supplied to the hot water receiving port of the die casting machine plunger sleeve. A hot water supply pipe having a molten metal outlet, a molten metal inlet in the stored molten metal, and a molten metal sensor equipped with a molten metal sensor for detecting the arrival of the molten metal to a fixed position of the molten metal outlet. In the hot water supply method of molten metal for quantitatively supplying the stored molten metal in a pressure type hot water supply furnace to a hot water receiving port of a die casting machine plunger sleeve, the set of pre-level holding controls Continuous feeding of molten metal to the die casting machine by the pre-level pressurizing valve A, the pre-level pressurizing valve B, the pre-level exhaust valve A, the pre-level exhaust valve B, and the set of hot-water supply controlling pressurizing and exhaust valves described above. At the time of operation, except when actually supplying hot water to the die casting machine from the melt outlet of the hot water supply pipe via the hot water supply pipe, the molten metal stored in the furnace is reduced to a predetermined constant width of the hot water supply pipe. In the pre-level hot water supply control method, the hot water is supplied to the die casting machine plunger sleeve from the pre-level height position when the hot water supply request is issued from the die casting machine. Measure the pressure inside the furnace just before the start of hot water supply control,
Using the measured value and the value previously measured and stored as the reference pre-level holding pressure value at the time of the reference maximum holding amount of the molten metal in the furnace in the arithmetic unit of the hot water supply control device, the relational expression of the following equation 1 is used. A method for improving the accuracy of hot water supply in a pre-level hot water supply control method, wherein the pressure control is corrected by calculating the following. Where TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. PDS: Furnace pressure value measured at the start of hot water supply and transmitted to the arithmetic unit of the hot water supply control device in the control panel. PPHI: Reference pre-level holding pressure value at the time of holding the reference maximum of the molten metal in the pressurized water heater. K: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. By the way, the unit of time that is calculated and set for practical use is 10 ms
ec. 2. The method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to claim 1, wherein the molten metal stored in the furnace is supplied to the die casting machine except when the hot water is actually supplied to the die casting machine from the molten metal outlet of the hot water supply pipe. When the pre-level is maintained at a height position having a predetermined constant width of the hot water supply pipe, a small error of the hot water supply accuracy caused by the difference within the width range of the constant height position is individually determined. Measures the time from the start of hot water supply control until the molten metal sensor that detects the arrival of the molten metal at the fixed position of the molten metal outlet of the hot water supply pipe installed at the fixed position of the molten metal discharge outlet detects the molten metal. Before each individual hot water supply which was measured and stored every time
Time from the start of hot water supply control in the zero-time hot water supply control to the time when the molten metal sensor that detects the arrival of the molten metal at the fixed position of the molten metal outlet of the hot water supply pipe installed at the fixed position of the molten metal outlet of the molten steel pipe detects the molten metal. Using the data average value, the following equation 2
A method for improving hot water supply accuracy in a pre-level hot water supply control method, characterized by adding a calculation using a relational arithmetic expression of (1) and (2) to correct pressure control. Where TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. TEKAV: Average value of the previous 10 shot molten metal sensor detection time. TEK: Individual molten metal sensor detection time. F: A variable constant that is increased or decreased by a setter on the control panel according to the required hot water supply amount. By the way, the unit of time that is calculated and set for practical use is 10 ms
ec. 3. A method for improving hot water supply accuracy in a pre-level hot water supply control method according to claim 1, wherein a continuous hot water receiving pipe, a hot water receiving hopper, and a hot water receiving hopper for replenishing molten metal from the outside without stopping continuous operation. With the replenishment of the molten metal from the continuous hot water receiving device consisting of the lid, the amount of molten metal in the furnace inevitably increases, the volume of gas retained in the furnace decreases, and the furnace pressure increases inversely. The above-described hot water receiving hopper lid is used to determine that the height of the molten metal pre-level held at a predetermined constant height position of the hot water supply pipe also has a larger variation compared to the time of the normal hot water supply control and fluctuates the hot water supply accuracy. The open state of the furnace is recognized as a continuous hot water reception by a sensor signal of a limit switch, etc., and the change degree of the load cell signal value for constantly tracking and measuring the quantitative transition of the molten metal in the furnace is determined.
A method for improving the accuracy of hot water supply in a pre-level hot water supply control method, characterized by adding a correction corresponding to the degree of change using a relational expression of the following equation 3 to correct the pressurization control. Where TP: actual differential pressure time. TPMAX: Maximum differential pressure time (the longest possible differential pressure time set by the type of pressurized water heater). %: A variable constant that can be increased or decreased with a setting device on the control panel according to the required hot water supply. J: a constant that is determined and adjusted at the time of trial operation adjustment based on the degree of change in the measured signal value from the load cell during continuous hot water reception and previously stored in the arithmetic unit. By the way, there are three kinds of constants: a zero value when the molten metal is not replenished even though the hot hopper lid is opened, and two constant values to be selected based on the amount of unit time of replenishment. Is determined from the value of. The unit of time calculated and set for practical use is 10 msec. 4. The method for improving the accuracy of hot water supply in the pre-level hot water supply control method according to claim 1, wherein an inert gas outlet is provided in the pressurized hot water supply furnace toward a molten metal outlet of the hot water supply pipe, and an external inert gas supply source is provided. An inert gas supply pipe having a parallel pipe line that has individual inert gas valves that can open and close the pipe line in response to a signal from the hot water supply control unit for the supply of high-temperature inert gas supplied via the inert gas heating device A method for improving the accuracy of hot water supply in a pre-level hot water supply control method, wherein a hot water supply control method is additionally provided. 5. A method for improving hot water supply accuracy in a pre-level hot water supply control method, wherein the method for improving hot water supply accuracy according to claim 2, 3, or 4 is combined.