JPH1058112A - Method for controlling supplying quantity of molten metal and instrument for detecting molten metal surface level - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect molten metal surface level and to improve the responsiveness of the detection by detecting that the molten metal reaches the reference level, with an electric short circuit between an electrode body and an injection sleeve and stopping the supply of the molten metal after passing a prescribed time. SOLUTION: In a control for supplying the molten metal, the molten metal in a furnace at a fixed molten metal surface is supplied into an injection sleeve 13 through a nozzle 21 and a timer 36 is worked. When the molten metal surface level risen in the injection sleeve 13 reaches the reference level L1 and contacts with the electrode 41, the short circuit is electrically generated between the electrode 41 and the injection sleeve 13. A detected signal with this short circuit is given to a CPU 38. The CPU 38 measures the time from the level L0 to the level L1 with a timer 36, and this time is stored in a memory. After passing the prescribed time since the reach of molten metal to the reference level L1 is detected with a detecting sensor 40, the driving of the molten metal supplying device 23 is stopped through the CPU 38. Thereafter, a plunger tip is elevated and the molten metal supplied in the injection sleeve 13 is injected into a cavity in a metallic mold.

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 amount control method and a molten metal level detecting device used for a vertical injection device of a die casting machine, and more particularly, to an improvement in level detection accuracy and responsiveness of a molten metal in an injection sleeve. TECHNICAL FIELD The present invention relates to a hot water supply amount control method and a molten metal level detecting device which enable accurate control of a hot water supply amount.

[0002]

2. Description of the Related Art Conventionally, in a hot water supply device using an electromagnetic pump for supplying hot water to an injection sleeve of a die casting machine, the operation time of the electromagnetic pump is set by a timer. In such a case, a small amount of time is initially set, the hot water is supplied into the injection sleeve and solidified, and the time until the target hot water supply weight is gradually obtained while measuring the solidified weight. However, such a method not only complicates the adjustment of the amount of hot water supply but also has an effect on productivity.

Therefore, the present applicant has previously proposed a hot water supply amount control method which has solved these problems (Japanese Patent Laid-Open No. 7-1995).
No. 80621). In this method, first and second temperature sensors are provided at a predetermined distance in the side wall of the injection sleeve, and the time during which the molten metal passes between the temperature sensors is measured. And the operation of the hot water supply device is stopped after the lapse of the time from when the molten metal reaches the second temperature sensor.

This hot water supply amount control method uses a temperature sensor as a sensor for detecting the level of the molten metal in the injection sleeve.

In a vacuum casting method in which the inside of a mold cavity is depressurized by using a vent valve, a tip is disposed above the mold as a sensor for detecting the tip of the molten metal to close the vent valve. 2. Description of the Related Art A sensor of a type configured to detect the arrival of a molten metal by an electrical short circuit with the mold when contacting the electrode bar is known (for example, Japanese Utility Model Application Laid-Open No. 02-482).
No. 58)

[0006]

However, in the conventional hot water supply amount control, when the level of the molten metal supplied to the injection sleeve is detected by the temperature sensor, the temperature of the molten metal is measured via the wall surface of the injection sleeve. However, there is essentially a problem in response due to the thermal conductivity of the injection sleeve, and there is a limit in improving the accuracy.

In addition, in the case of a vertical injection device, when the molten metal is supplied in the injection sleeve, undulation on the molten metal surface is inevitably generated, and this undulation is a major cause of the detection error of the molten metal level. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot water supply amount control method which solves the above-mentioned problems of the prior art and improves the detection accuracy of the molten metal level in the injection sleeve.

It is another object of the present invention to provide a molten metal level detecting device capable of quickly and accurately detecting the level of molten metal and improving the responsiveness of a level detection sensor.

[0010]

To achieve the above object, the present invention relates to a hot water supply amount control method for controlling the amount of hot water supplied by a hot water supply device into an injection sleeve of a vertical injection device. An electrical short between the electrode body attached to the injection sleeve and the injection sleeve via an insulator so as to be able to contact the molten metal of the reference level located at a predetermined height from the initial level of the reference level causes the reference level. Along with detecting the arrival of the molten metal to the molten metal, the time until the molten metal reaches the reference level from the initial level is measured, and a required amount of hot water is supplied based on the measured time, and the molten metal reaches the reference level. And calculating a time until the required hot water supply amount is reached, and stopping the operation of the hot water supply device after the calculated time has elapsed.

According to the hot water supply amount control method of the present invention, the electrode body is attached to the injection sleeve, and the electrical short circuit generated when hot water is supplied into the injection sleeve and the molten metal comes into contact with the electrode body is detected. , The responsiveness is improved, the arrival of the molten metal can be detected quickly, and the accuracy of measuring the time until the molten metal reaches the reference level in the injection sleeve is improved. Then, the time from the measurement time to when the required hot water supply amount is reached is immediately calculated, and after the lapse of the time, the operation of the hot water supply device is stopped, so that the hot water supply amount can be accurately controlled in real time.

Further, the present invention relates to a hot water supply amount control method for controlling a hot water supply amount supplied by a hot water supply device into an injection sleeve of a vertical injection device divided at a mating surface of a fixed mold and a movable mold. Forming a runner for guiding the molten metal to the molten metal detecting means for detecting the molten metal of the reference level at a predetermined height position from the initial level in the divided surface of the injection sleeve,
The arrival of the molten metal to the reference level is detected by the molten metal detection means, and the time required for the molten metal to reach the reference level from the initial level is measured. And the time from when the temperature reaches the reference level to when the required hot water supply amount is reached, and the operation of the water heater is stopped after the calculated time has elapsed.

According to the hot water supply amount control method of the present invention, the influence of the waving of the molten metal level surface generated while the supplied molten metal rises in the injection sleeve is prevented from being exerted on the molten metal detecting means by narrowing the molten metal with the runner. Therefore, the level of the molten metal can be detected more accurately. In this control method, the molten metal detecting means includes an electrode body attached to the injection sleeve via an insulator so as to be able to contact the molten metal at the reference level, and the molten metal introduced into the runner is connected to the molten metal. The arrival of the molten metal at a reference level is detected by detecting an electrical short circuit upon contact with the body.

A molten metal level detecting device according to the present invention comprises: an insulator mounted on an injection sleeve of a vertical injection device;
An electrode body supported by the insulator at a position accessible to the molten metal at a predetermined level in the injection sleeve, and an electrical short circuit when the molten metal enters the injection sleeve and contacts an electrode rod. , The arrival of the molten metal at the predetermined level is detected.

According to the molten metal level detecting device, the molten metal is detected by detecting an electric short circuit generated when the molten metal comes into contact with the electrode body by supplying the molten metal into the injection sleeve, so that the responsiveness is improved. Since the injection sleeve is provided on the injection sleeve in which the internal pressure is not generated as compared with the inside of the mold in which the internal pressure of the molten metal is high, the structure such as a structure for sealing can be simplified.

In this molten metal level detecting device, the injection sleeve is composed of an injection sleeve divided at a mating surface of a fixed die and a movable die, and the molten metal at a predetermined level in the injection sleeve is guided to the divided surface. A runner is formed, and the electrode body is supported by the electrode body so as to be able to contact the molten metal in the runner.

With this configuration, the molten metal rising in the sleeve is narrowed by passing through the runner before coming into contact with the electrode body, thereby eliminating the influence of the undulation of the molten metal level surface and improving the detection accuracy. it can.

According to a preferred embodiment, the electrode body comprises an electrode rod disposed so that the tip thereof faces the runner. The electrode body is opposed to the insulating sleeve and the other divided surface is closed when the mold is closed. An insulating stopper against which the tip of the electrode rod comes into contact is provided, and the electrode rod is urged in a direction to protrude from the dividing surface by the elastic force of an elastic member housed in the insulating sleeve, and the amount of movement of the electrode rod when the mold is opened Is provided so as to be adjustable, and a function of removing small metal pieces solidified in the runner from the electrode rods can be added.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a hot water supply amount control method and a molten metal level detecting device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing the overall configuration of a vertical injection device of a die casting machine to which the present invention is applied, and FIG. 2 is a diagram showing a main part thereof.

In FIG. 1, a vertical injection device 11 is disposed below a mold 1 composed of a fixed mold and a movable mold. The vertical injection device 11 includes an injection sleeve 13 having a hot water supply port 12 opened at a lower portion of a side wall, and an injection cylinder device for injecting the molten metal supplied in the injection sleeve 13 upward toward the cavity 2 of the mold 1. 14.

The injection cylinder device 14 includes a cylinder 15
And a plunger tip 18 slidably provided in the cylinder 15 and a plunger tip 18 connected to the piston 16 via a piston rod 17 and sliding in the injection sleeve 13. Reference numeral 19 denotes a sensor for detecting the position at which the plunger tip 18 is raised and lowered.

In the hot water supply port 12 of the injection sleeve 13,
A constant temperature furnace 22 is connected through a nozzle 21, and a hot water supply device 23 such as an electromagnetic pump for supplying the molten metal in the constant temperature furnace 22 into the injection sleeve 13 is connected to the nozzle 21.
Is provided on the outer periphery. At the time of hot water supply, the level of the molten metal in the constant temperature furnace 22 and the nozzle 21 is set to the constant level furnace 2.
2 is controlled to a constant level (initial level L0).

As shown in FIG.
Of the hot water supply port 12 from the lowermost edge of the hot water supply port 12 (d ≦ h
The molten metal level detection sensor 40 is provided at an upper position by 1 ≦ 2dd (the diameter of the plunger tip 18). This arrangement position is a position where no pressure is generated in the molten metal in the injection sleeve 18 during injection.

As shown in FIG. 3, the molten metal level detecting sensor 40 is composed of an electrode rod 41 and an insulator 42, and is supplied into the injection sleeve 13 to increase the molten metal level. The sensor detects the arrival of the molten metal by utilizing an electrical short circuit generated when the rod 41 and the injection sleeve 13 are simultaneously contacted.

The electrode rod 41 is inserted into the sleeve-shaped insulator 42 by press-fitting so that the tip end thereof is exposed from the inner peripheral surface of the injection sleeve 13 and can contact the molten metal supplied to the injection sleeve 13. As well as being electrically insulated from the injection sleeve 13 by the insulator 42.

The head of the electrode rod 41, that is, the portion projecting outward from the outer peripheral surface of the injection sleeve 13 is threaded.
The wiring B is fixed by a and 44b.

A wire A extends from the injection sleeve 13, and these wires A and B are connected to a short-circuit detection circuit 46. The short-circuit detection circuit 46 is connected to the control means 34.

As a material of such an electrode rod 41, a material which is electrically good and is not easily eroded by a molten metal, as well as a material which is resistant to thermal shock, is used.
For example, materials such as hot die steel, conductive ceramics, and boride Samet are suitable. Further, as a material of the insulator 42, a ceramic material such as silicon nitride, sialon, or silicon carbide that is electrically insulative, hardly eroded by the molten metal, and resistant to thermal shock is used.

The control means 34 comprises an I / O 35, a timer 36 as a measuring means for measuring a time t1 from the initial level L0 of the molten metal to the detection of the arrival of the molten metal by the molten metal level detecting sensor 40, and a timer 36 A memory 37 storing the time t1 measured at 36 and the temperature data T of the molten metal at the time of casting a good product,
And a CPU 38 as an arithmetic and control unit for controlling the operation of. The CPU 38 calculates the time t2 from the reference level L1 to the required hot water supply amount based on the time t1 from the initial level L0 of the molten metal to the time when the molten metal level detection sensor 40 detects the arrival of the molten metal at the reference level L1. Then, after the elapse of the time t2, the operation of the water heater 23 is stopped. The quality of the molten metal is determined from the temperature data Tx detected by the temperature sensor 48 and the temperature data T stored in the memory 37.

Next, a description will be given of a hot water supply amount control method performed by the hot water supply amount control device configured as described above.
First, according to a hot water supply command, the operation of the hot water supply device 23 is started,
The molten metal in the constant temperature furnace 22 is supplied to the hot water supply port 12 through the nozzle 21.
From the injection sleeve 13. At this time, the timer 36 is operated from the time when the operation of the hot water supply device 23 is started (that is, the initial level L0 of the molten metal). Injection sleeve 1
When the level of the molten metal rising inside 3 reaches the reference level L1 and comes into contact with the electrode rod 41, the electrode rod 41 and the injection sleeve 13 are electrically short-circuited. The CPU 38 to which the detection signal due to the short circuit is given measures the time t1 from the level L0 to the level L1 by the timer 36,
The time t1 is stored in the memory.

Next, the CPU 38 determines the required hot water supply level L2 (height H = h1 + h2) based on the time t1.
) Is calculated. The amount of molten metal from the initial level L0 to the reference level L1 is (V0 + V
1), the time t2 required for the molten metal amount V2 from the reference level L1 to the required hot water supply level L2 can be obtained from t2 = [V2 / (V0 + V1)] t1.

Here, V0... The internal volume of the nozzle 21 above the initial level L0 of the molten metal V1... The reference level L from the upper end surface of the plunger tip 18 at the lower limit (h0 above the initial level L0).
The internal volume of the injection sleeve 13 up to 1 can be obtained by calculation or experiment.

The CPU 38 includes a molten metal level detection sensor 40
The operation of the hot water supply device 23 is stopped after a lapse of time t2 after the arrival of the molten metal at the reference level L1 is detected. As a result, the operation of the hot water supply device 23 is stopped when the molten metal reaches the required hot water supply level L2, that is, the supply of the molten metal is stopped. Thereafter, as the plunger tip 18 rises, the molten metal (V1 + V2) supplied into the injection sleeve 13 is injected into the cavity 2 of the mold 1. After the injection, the plunger tip 18
Returns to the original position, and one injection operation ends.

In this way, even in the next injection operation, the molten metal level detection sensor 4 starts from the initial molten metal level L0.
A time t2 until the molten metal reaches the required hot water supply level L2 is calculated based on a time t1 until 0 is detected when the molten metal reaches the reference level L1, and the operation of the hot water supply device 23 is performed after the elapse of the time t2. By being stopped, the molten metal is always supplied to the required hot water supply level L2.

At this time, the time t 1 ′ in a state where there is no clogging in the nozzle 21 is stored in the memory 37 in advance, and the measured time t 1 is compared with the time t 1 ′ stored in the memory 37. It is possible to determine whether or not clogging has occurred in 21.

The CPU 38 includes a hot water supply level detector 4
The temperature data Tx detected by the temperature sensor 48 provided separately from 0 is compared with the temperature data T stored in the memory 37, and the quality of the molten metal is determined based on whether or not the difference is within an allowable range. If the difference is out of the allowable range, a message to the effect that a defect has occurred is given to the operator.

In the above first embodiment, the injection operation is performed 50 times at a hot water supply speed of 3 kgf / sec.
When the response time of the molten metal level detection sensor 40 was measured, the result was 3.5 msec on average and 3.9 msec at maximum. On the other hand, under the same injection operation conditions, when a conventional temperature sensor was attached to the injection sleeve 13 at a position corresponding to the reference level L1 in place of the molten metal level detection sensor 40 and the injection operation was performed, the response time was 45 msec on average.
Thus, when the injection sleeve 13 and the electrode rod 41 were electrically short-circuited, it was clear that the responsiveness was greatly improved.

Next, another embodiment of the present invention will be described with reference to FIG.

In the embodiment of the present invention, molten metal detecting means is provided on the divided surface of the injection sleeve, and when the molten metal detecting means detects that the molten metal has reached the reference level L1, the same hot water supply as in the first embodiment described above. This is to control the amount.

FIG. 4 is a diagram showing a cross section of the injection sleeve 13 in FIG. 2 at a position corresponding to the reference level L1. FIG. 5 is a view taken along line VV of FIG. The injection sleeve 13 is vertically split into two at the split surface of the mold into sleeves 13a and 13b.
Is a division plane. Reference numeral 52 denotes the entirety of the sensor as the molten metal detecting means disposed toward the division surface 50. As in the first embodiment, the molten metal detection sensor 52 combines the electrode rod 53 and the insulator 54 to form the molten metal into the electrode rod 5.
3 is a sensor of a type that detects by an electric short circuit between the electrode rod 53 and the injection sleeve 13 when it comes into contact with the injection sleeve 3.

In this case, the runner 55 for guiding the molten metal in the injection sleeve 13 is deflected from the rising direction of the molten metal so that the molten metal can come into contact with the tip of the electrode rod 53. Is formed. The end of the runner 55 communicates with a concave portion 56 formed in an insulating stopper 57 disposed so as to face the electrode rod 53.
The front end of the electrode rod 53 can face 6. The end surface of the insulating stopper 57 is connected to the split surface 5 of the injection sleeve 13.
It is arranged on the same plane as 0.

On the other hand, a compression coil spring 58 is accommodated as an elastic member in the insulating sleeve 54 as an insulator, and the compression coil spring 58 comes into contact with the shoulder of the electrode rod 53 to contact the electrode rod 53. Is urged in the direction of pushing the whole.

When a fixed mold and a movable mold (not shown) are clamped, the electrode rod 53 is pushed into the insulating sleeve 54 against the elastic force of the compression coil spring 58. A screw is formed at the tail end of the electrode rod 53, and a lock nut 59 and a positioning nut 60 are screwed into the screw. The lock nut 59 and the positioning nut 60 constitute a means for adjusting the movement stroke S of the electrode rod 53 projecting from the sleeve dividing surface 50 by the elastic force of the compression coil spring 57 when the mold is opened.

In FIG. 4, reference numeral 61 denotes a screw for fixing the insulating sleeve 54 so that it does not rotate and does not come off because the direction of the runner 55 is fixed. Shows a screw that keeps it from turning and coming off. In the hot water supply amount control method using the molten metal level detection sensor 52 having the above-described configuration, the basic operations such as the calculation of the required molten metal amount are the same as those in the first embodiment described above. First, the timer 36 is operated from the initial level L0 of the molten metal, and when the level of the molten metal rising in the injection sleeve 13 reaches the reference level L1, the molten metal is guided by the runner 55 and contacts the electrode rod 53. .

Since the runner 55 is narrow and is deflected with respect to the rising direction of the molten metal, the runner 55 is narrowed by the runner 55 so that the surface of the molten metal does not undulate on the runner 55. Accurate level detection by the electrode rod 53 can be performed without receiving the signal. In addition, hot water supply speed is 1kgf
/ Sec, 50 injection operations were performed, and the response time of the molten metal level detection sensor 52 was measured to be 3.8 on average.
msec, at most 4.1 msec. this is,
Although it is slightly inferior to the average of the first embodiment of 3.5 msec, it is clear that the responsiveness is significantly improved in addition to the effect of the ripples. When an electrical short-circuit occurs, the CPU 38 to which the detection signal due to the short-circuit is given measures the time t1 from when the molten metal reaches the level L0 to L1 by the timer 36,
The time t1 is stored in the memory.

Next, the CPU 38 determines the required hot water supply level L2 (height H = h1 + h2) based on the time t1.
) Is calculated, and after the elapse of the time t2, the operation of the hot water supply device 23 is stopped, and the molten metal is always supplied to the required hot water supply level L2.

FIG. 6 shows that the electrode rod 5 is opened when the mold 1 is opened.
FIG. 3 is a view showing a state in which the protrusion 3 projects from a sleeve dividing surface 50 by the elastic force of a compression coil spring 58. In this case, in FIG. 4, a small metal piece 70 solidified in the runner 55 and adhered to the tip of the electrode rod 53 is removed by an impact when the positioning nut 60 abuts on the end face of the insulating sleeve 54. The detection accuracy of 53 can be prevented from lowering.

In order to prevent solidification of the molten metal in the runner 55, a means such as embedding a cartridge heater in the insulating sleeves 54 and 57 may be employed as a solidification preventing means.

Further, the molten metal detecting means according to the second embodiment is not limited to a sensor utilizing the electrical conduction of the electrode rod 53, but may use other molten metal detecting means, for example, a temperature sensor, a thermocouple or the like. Is also good.

Next, in the first and second embodiments described above, the inner diameter of the injection sleeve 13 is 80 mm.
Table 1 shows the results of a hot water supply test performed using the casting metal alloy AC4CH as the type of molten metal.

[0051]

[Table 1] In this case, hot water was supplied 50 times for each of the hot water supply speeds of 1 kgf / sec and 3 kgf / sec. The required amount of hot water is set at 3 kgf, the actual amount of hot water is measured, and the error is expressed as the accuracy of hot water supply.

In both the first and second embodiments, it can be seen that the accuracy of hot water supply is improved as compared with the one using a conventional temperature sensor. Comparing the first embodiment and the second embodiment, it is proved that the second embodiment can improve the accuracy of hot water supply and prevent the influence of ripples in the injection sleeve 13. Can be

[0053]

As is apparent from the above description, according to the present invention, the responsiveness and accuracy of the molten metal level detection in the injection sleeve can be improved, and accurate hot water supply control can be achieved.

Further, according to the molten metal level detecting device of the present invention, the responsiveness is improved, the molten metal level can be detected quickly and accurately, and the detection accuracy of the undulation on the molten metal level surface rising the injection sleeve is improved. It is possible to achieve an improvement in accuracy without any influence.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of a vertical injection device of a die casting machine to which the present invention is applied.

FIG. 2 is a cross-sectional view showing a main part of the vertical injection device of FIG.

FIG. 3 is a sectional view showing a configuration of a molten metal level detection sensor.

FIG. 4 is a sectional view showing a configuration of a molten metal level detection sensor according to another embodiment.

FIG. 5 is a diagram showing a relationship between a runner and an injection sleeve.

FIG. 6 is a diagram showing the operation of the electrode bar when the mold is opened.

[Explanation of symbols]

 Reference Signs List 1 mold 2 cavity 11 vertical injection device 12 hot water supply port 13 injection sleeve 14 injection cylinder device 18 plunger tip 21 nozzle 22 constant temperature furnace 23 hot water supply device 40 molten metal level detection sensor 41 electrode rod (electrode body) 42 insulator 46 short circuit Detection circuit 50 Injection sleeve division surface 52 Molten metal detection sensor 53 Electrode rod 54 Insulator 55 Runner 57 Insulation stopper

Claims (6)

[Claims] 1. A hot water supply amount control method for controlling a hot water supply amount supplied from a hot water supply device into an injection sleeve of a vertical injection device, comprising: contacting a molten metal of a reference level at a predetermined height position from an initial level in the injection sleeve. An electrical short circuit between the electrode body attached to the injection sleeve and the injection sleeve via an insulator as much as possible detects the arrival of the molten metal to the reference level and allows the molten metal to move from the initial level. The time required to reach the reference level is measured, and the required amount of hot water and the time required for the molten metal to reach the required level after the molten metal reaches the reference level are calculated based on the measured time. A method for controlling the amount of hot water supply, wherein the operation of the hot water supply device is stopped after a lapse of the set time. 2. A hot water supply amount control method for controlling a hot water supply amount supplied by a hot water supply device into an injection sleeve of a vertical injection device divided by a mating surface of a fixed die and a movable die, wherein the initial level in the injection sleeve is controlled. A runner for guiding the molten metal to the molten metal detecting means for detecting the molten metal of the reference level at a predetermined height position is formed on the divided surface of the injection sleeve, and the arrival of the molten metal to the reference level is detected by the molten metal detecting means. At the same time, a time required for the molten metal to reach the reference level from the initial level is measured, and a required amount of hot water based on the measured time and a time required for the molten metal to reach the required hot water supply amount after the molten metal reaches the reference level. And calculating the time and stopping the operation of the water heater after the calculated time has elapsed. 3. The molten metal detecting means includes an electrode body attached to the injection sleeve via an insulator so as to be able to contact the molten metal at the reference level. 3. The hot water supply amount control method according to claim 2, wherein the arrival of the molten metal to a reference level is detected by detecting an electrical short circuit when the molten metal comes into contact with a body. 4. An insulator mounted on an injection sleeve of a vertical injection device, and an electrode body supported by the insulator at a position capable of contacting a molten metal at a predetermined level in the injection sleeve, A molten metal level detecting device, wherein the arrival of the molten metal to the predetermined level is detected by detecting an electrical short circuit when the molten metal simultaneously contacts the injection sleeve and the electrode rod. 5. The injection sleeve comprises an injection sleeve divided by a mating surface of a fixed mold and a movable mold, and a runner for guiding a molten metal at a predetermined level in the injection sleeve is formed on the division surface. The molten metal level detecting device according to claim 4, wherein the electrode body is supported by the electrode body so as to be able to contact the molten metal in the runner. 6. The electrode body comprises an electrode rod arranged so that the tip faces the runner. The tip of the electrode rod faces the insulating sleeve when the mold is closed on the other divided surface. Provided with an insulating stopper that abuts, urges the electrode rod in a direction protruding from the dividing surface by the elastic force of the elastic member housed in the insulating sleeve, and regulates the amount of movement of the electrode rod when the mold is opened so as to be adjustable. 6. The molten metal level detecting device according to claim 5, wherein a means for removing the small metal pieces solidified in the runner is added from the electrode rod.