JPH06277820A - Method and device for controlling molten metal quantity in casting equipment and sensor for detecting molten metal - Google Patents

Abstract

PURPOSE:To rationalize die casting and to improve product quality as for casting equipment by detecting in no time delay and in high precision the molten metal surface under high pressure. CONSTITUTION:It is the molten metal quantity control device of a casting equipment, which a molten metal 14 is poured in a die 9 so as to be die-cast under high pressure. A sensor for molten metal surface detection 10, which is provided with an electrode 1 of small diameter bar of heat resistant electric conductor and a refractory 5 encircled around a tip of electrode, is inserted into the hole 15 opened to the molten metal surface detecting position of a cavity 11 in a die 9, facing each tip part of the electrode 1 and refractory 5 on the cavity 11 and is fixed in the hole with electrically insulated so as to receive the internal pressure of cavity as the electrode 1 and refractory 5 are integrated. This electrode 1 of the molten metal detection sensor 10 and die 9 are short circuited through the molten metal 14 to detect a molten metal surface of the molten metal 14, further, the device consists of a control means 16 to control variation of molten metal supply quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of the amount of molten metal in a casting facility such as a die casting device, a molten metal forging device, a die casting device, etc., for controlling the amount of molten metal to be increased or decreased according to the level of the molten metal in the cavity. The present invention relates to a method, a molten metal amount control apparatus suitable for carrying out the method, and a molten metal detection sensor used directly for carrying out the method.

[0002]

2. Description of the Related Art A molten metal detecting sensor (hereinafter referred to as a sensor) used for detecting a molten metal surface in a cavity 11 of a conventional casting facility such as a die casting machine is shown in an enlarged scale in FIG.
This sensor is formed by a thermocouple. The body 17 made of a metal having a good thermal conductivity has a thermocouple mounting hole 18
Is bored from the rear side, and thermocouple wires 19 and 19 made of, for example, an alumel wire or a chromel wire having a wire diameter of 0.2 mm are welded to the bottom of the hole 18. A thick portion 20 between the welded portion and the front end face of the main body 17
Is usually 0.4 mm to 0.8 mm, and the diameter of the thermocouple mounting hole 18 is generally about 8 mm. The sensor having such a structure has no problem in use when the pressure inside the cavity 11 is as low as 50 to 75 Kgf / cm ² : 5 to 7.5 MPa.

[0003]

When the pressure inside the cavity 11 increases, the pressure of 200 to 300 Kgf / cm ² (2
Up to 0 to 30 MPa), the diameter of the thermocouple mounting hole 18 should be φ
By reducing the pressure to about 4 mm, a pressure resistant structure can be obtained, and there is no problem in detecting the molten metal surface, but the pressure inside the cavity 11 is much higher as in the die casting device,
In the case of reaching 0 to 1300 Kgf / cm ² (70 to 130 MPa), it is no longer possible to reduce the thermocouple mounting hole 18, and it is necessary to thicken the thick portion 20 to, for example, about 2 mm. When the thick portion 20 is thickened in this way, in this method in which the arrival of the molten metal surface is indirectly detected by the temperature change, the time difference (delay time) between the time of reaching the molten metal surface and the time of detecting the temperature becomes large, and the detection performance is improved. It is not suitable for practical use due to the decrease.

As a result of an experiment conducted by the present inventor on the above problem of detection performance, the following results were found.
That is, two sensors (thermocouples) having a thick portion 20 of 0.8 mm and 2.1 mm are attached at predetermined positions of the mold, and the elapsed time required for each sensor to detect a temperature of 110 ° C. from the start of casting. As a result of measurement, 0.03 sec, 0.
At 18 seconds, it is clear that the latter high-voltage sensor is very inferior in terms of detection performance.

The present invention has been made in order to solve such a problem, and an object of the present invention is to detect a molten metal surface under a high pressure with high accuracy without time delay. By doing so, it is aimed to rationalize the molding process in casting equipment and improve the quality of products.

[0006]

The present invention has the following constitution in order to achieve the above object. That is, the present invention is a method for controlling the amount of molten metal in a casting facility in which a molten metal such as an aluminum alloy is poured into a mold and molded under high pressure. The molten metal surface is detected by using the electrical displacement phenomenon caused by direct contact between the electrode and the molten metal, with the tip facing the molten metal surface detection position of the cavity, and the molten metal supply amount based on this detected molten metal surface. Is controlled to increase or decrease.

The present invention is also an apparatus for controlling the amount of molten metal in a casting facility for injecting a molten metal such as an aluminum alloy into a mold and molding it under high pressure. The electrode is composed of a thin rod of heat-resistant conductor and its tip. With a refractory surrounding the part,
The mold is inserted into one hole or two adjacent holes that are opened at the molten metal surface detection position of the cavity, and each tip surface of the electrode and refractory faces the cavity, and the electrode and refractory are integrated. In order to be able to receive the internal pressure of the cavity, the molten metal detection sensor is electrically insulated and fixed in the hole, and the electrode and mold of the molten metal detection sensor,
Alternatively, it includes a control means for detecting the molten metal surface by short-circuiting the electrodes of two adjacent molten metal detection sensors via the molten metal, and controlling the increase / decrease of the molten metal supply amount.

The present invention also provides a molten metal detection sensor for detecting a molten metal surface, which is attached to a casting facility for injecting a molten metal such as an aluminum alloy into a mold and molding under high pressure. An electrode composed of a small diameter rod, and a refractory which is provided around the tip of the electrode so that the tip surface is flush with the electrode,
A slender rod body as a whole, including a cylinder main body that is integrally coupled to the rear part of the refractory and is fitted to the rear part of the electrode via an electrical insulator, and the cylinder main body is a tip end part of each of the electrode and the refractory. It is characterized in that it is formed on a pressure receiving carrier for collectively receiving the surface pressure acting on.

[0009]

According to the present invention, since the detection system in which the electrodes directly contact the molten metal and conductively detects the molten metal surface is used, there is no time lag and the detection accuracy is extremely high. Furthermore, the electrode and the refractory around it can be made as thin as possible, and a pressure resistant structure can be easily obtained. Since it can be carried on the side, the amount of molten metal can be stably controlled over a long period by using a sensor having a high pressure resistance as a whole.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view schematically showing a main part of a die casting apparatus, which is an example of a casting facility according to an embodiment of the present invention. (A) shows a state immediately before pouring molten metal, and (B) shows a molten pouring operating state. Shown respectively. The mold 9 comprises an outer mold 9A and an inner mold 9B, and a cavity 11 is provided in a mating surface portion of both molds 9A and 9B. The cavity 11 has a plunger chamber 1 containing a plunger 12 for pouring molten metal.
3 are connected. The molten aluminum alloy 14 fed into the plunger chamber 13 is fed into the cavity 11 by the pushing operation of the plunger 12, and is molded under high temperature and high pressure. The configuration and the operation mode described above are well known contents in the die casting apparatus.

The outer mold 9A of the mold 9 is provided with a sensor mounting hole 15, which is provided so as to penetrate from the outer surface to the wall of the cavity 11 and to form the cavity 11.
Is formed in a two-step hole having a smaller diameter than the other portions, and the opening position is matched with the molten metal surface detection position at a predetermined intermediate level. For this sensor mounting hole 15,
The sensor 10 is hermetically fitted and inserted from the outside, and is fixed in a pressure resistant manner.

The sensor 10 is for detecting the surface of the molten metal 14 in the cavity 11 and has a structure shown in FIG.
Is illustrated in a sectional view. As shown in the figure, the sensor 10 includes an electrode 1, a cylinder body 2 forming an outer casing, a ring-shaped electrical insulator 3, and a stepped pillar-shaped refractory 5 as element members, and a stepped elongated bar as a whole. Composed in the body. Tube body 2
Is made of a metal having heat resistance and pressure resistance, for example, stainless steel. A large diameter stepped hole is provided at the tip, and the large diameter part of the refractory material 5 is press-fitted into this hole to form a cylinder. Body 2
And refractory 5 are integrally connected. The refractory 5 has a small-diameter hole penetrating the central axis of the column.

The electrode 1 is made of a long and slender heat-resistant conductor, for example, a tungsten rod whose front and rear portions are narrower than the middle portion, and is inserted concentrically in the cylinder body 2 and the refractory 5 is The tip end portion is fitted in the hole so as to be flush with the tip end portion of the refractory material 5, while the rear portion is pulled out from the cylinder main body 2 and a conductor is connected to the rear end portion. The electrode 1 is inserted into the cylinder body 2 by inserting the receiving washers 4 and the electric insulators 3 into the front and rear portions on both sides of the intermediate portion, and is fitted into the holes of the refractory material 5. In this state, the set screw 6 is screwed into the screw hole provided at the rear portion of the cylinder body 2, whereby the electrode 1, the cylinder body 2 and the refractory 5 are integrally assembled to form the sensor 10. In the case of molten aluminum as the electric insulator 3, a refractory material having a low affinity with and strong, for example, silicon nitride or boron nitride is a preferable example.

As shown in FIG. 2, the sensor 10 having the above-described structure is fitted in the sensor mounting hole 15 in an airtight manner, and then, with the spacing piece 7 interposed, the outer screw 9A is pressed by the holding screw 8. Fixed to. In the sensor 10 thus fixed, the tip surfaces of the electrode 1 and the refractory material 5 are flush with the wall of the cavity 11, and the tip surface portions of the electrode 1 and the refractory material 5 acting from the cavity 11 side are high. The force due to the fluid pressure can be collectively received by the cylinder body 2 as a pressure-bearing carrier, and the pressure-resistant structure can be formed by making the electrode 1 thin so that the refractory 5 can be formed. It is possible to form a heat resistant structure by including.

The above-mentioned sensor 10 and the control means 16 realized by the electric-hydraulic conversion circuit constitute a molten metal amount control device. That is, when the sensor 10 receives a molten metal surface signal that detects and outputs the molten metal surface of the molten metal 14, the electro-hydraulic conversion circuit 1
6 issues, for example, a speed-up command to the plunger 12 to increase the pushing speed of the plunger 12 and
Operates to increase the rate of pouring of melt 14 into the interior.
In this case, the example of FIGS. 1 and 2 is a device that uses one sensor 10, in which a potential difference is applied between the electrode 1 and the mold 9 and the filling amount of the molten metal 14 in the cavity 11 is set. Further, it is possible to detect the molten metal surface position of the molten metal 14 promptly without a time lag by utilizing the fact that the molten metal 14 electrically short-circuits between the electrode 1 and the mold 9.

FIG. 3 is a sectional view of a sensor according to another embodiment of the present invention. In this example, the sensor 10 shown in FIG.
They are used individually and are provided close to each other in the vertical direction at a predetermined position of the mold 9. In the case of this example, a potential difference is applied between the two electrodes 1 of the two sensors 10, and the filling amount of the molten metal 14 in the cavity 11 is increased, so that the molten metal 14 is separated between the electrodes 1.
It is possible to detect the position of the molten metal 14 by utilizing the fact that it is electrically short-circuited.

FIG. 4 is a sectional view of a sensor according to another embodiment of the present invention. This example is different from the monopolar structure in the case of FIGS. 2 and 3 in that it has a bipolar structure by assembling the two electrodes 1, 1 side by side with respect to the cylinder body 2 and the refractory material 5. There is a feature of. Note that the detection operation is the same as in the example of FIG. 3, and is used with a potential difference applied between both electrodes 1.

[0018]

As described above, according to the present invention, it is a method of detecting that the electrode directly contacts the molten metal.
There is no time delay as seen in the conventional use of heat conduction, and therefore, extremely accurate level detection without ambiguity and highly reliable control of the amount of molten metal by the detection are possible. Further, according to the present invention, it is possible to provide a sensor that is small in size and has high withstand voltage performance by forming the electrode into a rod body as thin as possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a main part of a die casting apparatus which is an example of a casting facility according to an embodiment of the present invention,
(A) shows the state immediately before the molten metal injection, and (B) shows the molten metal injection operating state.

FIG. 2 is a molten metal detection sensor 10 according to an embodiment of the present invention.
FIG.

FIG. 3 is a molten metal detection sensor 10 according to another embodiment of the present invention.
FIG.

FIG. 4 is a sectional view of a molten metal detection sensor 10 according to another embodiment of the present invention.

FIG. 5 is a sectional view of a molten metal detection sensor used in a conventional casting facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrode, 2 ... Cylinder main body, 3 ... Electrical insulator, 5 ... Refractory material, 9 ... Mold, 10 ... Molten sensor, 11 ... Cavity, 14 ... Molten, 15 ... Sensor mounting hole, 16 ... Control means .

Front page continuation (72) Fumikazu Otsuki, Inventor Fumikazu Otsuki 1-3-18, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Kobe Steel Works, Kobe Head Office (72) Kiyoshi Tsune 3 Higashi-oike, Kita-ku, Kobe Chome 34-21

Claims (3)

[Claims] 1. In a casting facility for injecting molten metal into a mold and molding under high pressure, an electrode is pierced through the mold in a pressure resistant and electrical insulating manner, and a tip portion is provided at a molten metal surface detection position of a cavity. A casting characterized in that the molten metal surface is detected by utilizing an electric displacement phenomenon caused by direct contact between the electrode and the molten metal, and the molten metal supply amount is controlled based on the detected molten metal surface. Method of controlling molten metal amount in equipment. 2. A casting facility for injecting molten metal into a mold and molding under high pressure, comprising an electrode made of a thin rod of a heat-resistant conductor and a refractory surrounding the tip of the electrode. , Is inserted into one hole or two adjacent holes provided at the molten metal surface detection position of the cavity in the mold so that each tip surface portion of the electrode and the refractory material faces the cavity, and the electrode and the refractory material are A molten metal detection sensor, which is electrically insulated and fixed in the hole, and an electrode and a mold of the molten metal detection sensor, so that they can integrally receive the internal pressure of the cavity,
Or a control means for detecting the molten metal surface by short-circuiting the electrodes of two adjacent molten metal detection sensors via the molten metal, and controlling the increase / decrease of the molten metal supply amount. Molten metal amount control device in equipment. 3. A molten metal detection sensor for detecting a molten metal surface by being attached to a casting facility for injecting molten metal into a mold and molding under high pressure, the electrode comprising a thin rod of a heat-resistant conductor. A refractory which is provided around the tip of the refractory and whose front end surface is flush with the electrode, and a tube which is integrally coupled to the rear of the refractory and is fitted to the rear of the electrode via an electrical insulator. A molten metal, including a main body, which is a slender rod body as a whole, and which is formed as a pressure-bearing carrier for collectively receiving the surface pressure acting on the tip surfaces of the electrodes and refractory material. Sensor for detection.