JP2554982B2 - Molten metal sensor mechanism of cold chamber type die casting machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold chamber type die casting machine, and more particularly to a molten metal sensor mechanism for a die casting machine for obtaining a cast product having no cavities.

[0002]

2. Description of the Related Art In a conventional cold chamber type die casting machine, normally, the molten metal in a melting furnace is pumped up by a ladle, and then the molten metal is supplied to a plunger sleeve at a filling rate of about 40% to advance an injection plunger at a low speed. In the low-speed injection process, the hydraulic valve is switched so that the injection plunger has a high injection speed by a preset limit switch signal, assuming the time when the tip reaches the gate of the mold. The cavity was filled with the molten metal in an extremely short time.

Further, in the case of hot water supply by a molten metal feeding device such as an electromagnetic pump, the amount of hot water supplied is set by controlling the operating time of the electromagnetic pump with a timer, for example, so that there is a problem that the amount of hot water supply varies greatly. However, since the molten metal can be supplied without contact with the air, a good quality cast product free of oxides was obtained. However, the plunger sleeve is supplying hot water with a filling rate of around 40%, and a low-speed injection process is required to advance the injection plunger at a low injection speed until the tip of the hot water reaches the gate. Met.
When the injection plunger is moving forward at a low speed, the surface of the molten metal in the plunger sleeve is so large that air is entrained, and it is impossible to manufacture a cast product without cavities.

Therefore, a quantitative filling detection device, that is, a molten metal sensor mechanism disclosed in Japanese Utility Model Publication No. 44-22330 has been proposed and researched for its practical use. On the other hand, although sensitive heat sensor method are known by, and Japanese Utility Model 56-14923 discloses due this kind placed energization of the electrode and the molten metal as capacitors over, in the die-casting mold cavity of the water-soluble release agent It has been impossible to always keep the electrode rod clean in a very bad environment because fine powder, metal fine powder due to splash of molten metal and oxide thereof and the like adhere to the electrode of the sensor.

[0005]

By using a sealed molten metal feeder such as an electromagnetic pump instead of the ladle hot water feeder, it is possible to obtain a high quality cast product which is less in contact with air and is free of oxides. Since the plunger sleeve and the cavity communicating with the plunger sleeve are sealed, the internal pressure of the plunger sleeve rises as the hot water is supplied, and when the pressure exceeds the pressure of the electromagnetic pump, hot water cannot be supplied. In addition, the amount of hot water supplied is controlled by a timer for the operating time of the electromagnetic pump, and the internal pressure of the cavity changes, so that there is a problem that the variation in the amount of hot water supply becomes even greater.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a molten metal sensor for a cold chamber type die casting machine which can be kept clean against an extremely bad environment in the cavity of the die casting mold. It provides a mechanism.

[0007]

[MEANS FOR SOLVING THE PROBLEMS] A molten metal feeding device such as an electromagnetic pump fills molten metal into a plunger sleeve connected to a cavity formed by a fixed mold and a movable mold through a gate portion, and the molten metal feeding device Melts into the gate
Injection plunger device after detecting that hot water is filled
When the molten metal is injected into the cavity by means of the molten metal sensor mechanism of the cold chamber type die casting machine, which detects that the gate portion located above the uppermost part of the inner surface of the plunger sleeve is filled with the molten metal. The holes are attached to the mold and communicate with holes having small and large diameters.
A sleeve that forms a conical surface hole that gradually decreases in diameter toward the gate part at the end opening to the gate part, and is slidably fitted in a small diameter hole of the sleeve and loosely inserted in a large diameter hole. <br /> The conical hole of the sleeve has a minute gap and forms a orifice that allows gas to pass therethrough and does not pass molten metal; a push-out bar of a wedge mechanism that moves the spool forward and backward; An elastic member that presses the extrusion bar, and a gas supply unit that includes a pressure switch that supplies gas to the orifice and detects a back pressure of the orifice when the orifice is blocked by molten metal and issues a control signal. Sensor mechanism for cold chamber type die casting machine consisting of.

[0008]

[Action] Prior to hot water, the melt in the melt feeder while removing a rise in pressure in the cavity communicates with a vacuum source or the atmosphere by opening the vacuum valve mechanism plunger Sri - When the hot water in the blanking, The molten metal opens the orifice of the sensor mechanism provided at the gate and releases a slight pressure gas, and when the molten metal reaches the orifice and blocks the orifice by the molten metal itself, the release of gas is hindered and the back pressure of the orifice rises. To do. When the back pressure of this orifice rises, the pressure switch operates to send a signal, which controls the molten metal feeding device and advances the injection plunger at a high speed to close the hot water supply port, thus controlling the quantitative amount of hot water supply with high accuracy. it can. Therefore, it is not necessary to adjust the limit switch for switching from low-speed injection to high-speed injection, and operability can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings showing embodiments. FIG. 1 is a cross-sectional view showing both fixed and movable dies, a plunger sleeve and the like. The fixed die 11 is fixed to a fixed die plate 12 and the movable die 13 is a movable die plate (not shown). An electromagnetic pump 15 is connected to the melting furnace 16 via hot water supply pipes 30 and 31 in the plunger sleeve 14 fixed to the fixed die plate 12 and attached to the fixed die plate 12. A plunger 18 for injecting the molten metal 17 into the cavity 20 is slidably provided at the rear end (right end in the figure) of the plunger sleeve 14, and an injection cylinder (not shown) is controlled by a hydraulic device. The plan <br/> Jasuri - tip of the probe 14 (the left end in the drawing) is gate - is connected to the cavity 20 through the door portion 19.

A vacuum valve mechanism 21 is mounted above the parting lines of the fixed mold 11 and the movable mold 13 and its details will be described later. A gas discharge type sensor mechanism 22 is attached to a portion of the movable die 13 which is in contact with the gate 19 portion . Reference numeral 26 is a gas supply unit connected to the sensor mechanism 22. The supply unit 26 includes a cylinder 23 accumulating oxygen gas (O 2) , a pressure adjusting valve 24 for adjusting the gas pressure discharged from the cylinder 23, and an electromagnetic valve. A pusher 43 for closing the drive source of the pump 15, the hydraulic valve of an injection cylinder (not shown) that is a drive device of the plunger 18, the drive source of the vacuum valve mechanism 21, and the orifice of the sensor mechanism 22 (FIG. 2).
Pressure switch 2 which issues an activation signal to each drive source
It is composed of 5 and 5.

Details of the above-mentioned sensor mechanism 22 will be described with reference to FIG. A small hole 31 and a large hole 31 are formed in the center of a portion of the plunger sleeve 14 which is located above the uppermost portion of the inner surface and is in contact with the gate portion 19 of the movable die 13 (not limited to the movable die 13 side). comprising a diameter of the hole 32, to the right of the large diameter of the hole 32
A sleeve 34 having a conical surface 33 having a gradually decreasing diameter is inserted toward the gate portion 19, and the end of the large diameter hole 32 is connected to a pressure switch 25 (see FIG. 1). A hole 36 is formed in the direction perpendicular to the axis which is in contact with 35. The sleeve 34 is fixed to the movable mold 13 by two screws 37, and a spool 38 is slidably inserted into the small-diameter hole 31 of the sleeve 34 to allow the spool 38 to move. In the figure, a conical surface 39 having the same angle as that of the conical surface 33 is formed at the right end, and both conical surfaces 33 and 39 are minute by about 0.2 mm.
An orifice 40 is formed which has a gap and allows gas to pass but does not pass molten metal.

[0012] The spool - left Le 38 is fixed to the coupling 42 by pressing in a screw 41 which is screwed to one end of the large diameter has become large diameter coupling 42 on the slope, the slope A push-out bar 43 that moves up and down by a cylinder (not shown) is in contact with the. Since the spring 44 is provided between the screw 37 and the other end of the coupling 42, the spool 38 is constantly pressed to the left and its position is regulated by the pushing bar 43. Although the spring 44 is described as a flat spring in the embodiment, it is not limited to a flat spring and may be an elastic body.

For example, the screw 41 and the coupling 42 are removed, and a compression coil spring is used in place of the flat spring 38 in the spool 38.
Is attached to the shank of the sprue, both ends of which are brought into contact with the screw 37 and the head of the spool 38, and the head of the spool 38 is pushed out by the extruding bar 43.
May be contacted with. When the spool 38 is in the state shown in the figure, the orifice 40 is open so that the gas in the passage 35 can be ejected from the orifice 40. However, when the extruding bar 43 is raised, the spool 38 passes through the coupling 42. To the right to close the orifice 40. A seal 50 is attached to the end surface of the sleeve 34 through a screw 37 to prevent leakage of oxygen gas supplied from the passage 35.

The vacuum valve mechanism 21 described above is shown in detail in FIG.
This will be described below. 3 is a partial sectional view of the parting line of the fixed mold 11 as seen from the moving mold 13 side in FIG.
In the figure, the support 51 centered on the parting line
Is attached to the fixed mold 11, and an actuator 5 having two conduits 52 and 53 on the upper surface of the support 51.
4 is fixed, the piston rod 55 of the actuator 54
Has a cover 56 slidably pierced through it and a lid 56 is screwed to the tip thereof. A valve body 60 is slidably inserted into a cylinder 59 formed by a valve main body 58 having a hole 57 in the lower part which is integrated with the lid 56, and a pipe line 61 connected to the cylinder 59 is inserted into the valve body 60. When the fluid flows in and out of 62, it moves up and down or moves forward and backward.

The valve body 60 opens the hole 57 of the valve body 58 when it descends (forwards) and closes the hole 57 when it rises (retracts) . The hole 57 communicates with the bent passage 63 from the cavity 20 and is connected to a vacuum source (not shown) or the atmosphere by a pipe 64. The vacuum valve mechanism is not limited to the illustrated configuration. Although the electromagnetic pump 15 is used as an example of the means for feeding the molten metal 17 in the above description, the melting furnace may be hermetically closed and air pressure may be applied to the upper portion, or a mechanical pump may be used.

Next, the operation of the above-described embodiment will be described. When the movable mold 13 moves forward and comes into close contact with the fixed mold 11, the fluid is sent to the pipe lines 52 and 61 of the vacuum valve mechanism 21 by the close contact signal of the two molds 11 and 13, and the valve body 58 and the valve body 60. Is lowered and the cavity 20 is connected to a vacuum source via a passage 63 and a pipe 64, and the cavity 20 is decompressed and at the same time the orifice 40 of the sensor mechanism 22 is depressurized.
Gas flows in to reduce the pressure in the cavity 20 and purge the air. The gas in the cylinder 23 is preferably oxygen gas as the reactive gas.

Then, by driving the electromagnetic pump 15, the molten metal 17 of the melting furnace 16 is pressure-fed into the plunger sleeve 11 via the hot water supply pipes 30 and 31, and the molten metal is supplied to the inside of the plunger sleeve 11 and the gate portion 19. When filled, the orifice 40 allows gas to pass and does not allow molten metal to pass, so that the molten metal 17 does not enter the orifice 40 and the molten metal 1
Since it is sealed by 7, the gas pressure on the inlet side of the orifice 40 rises and the pressure switch 25 operates. This signal stops the electromagnetic pump 15 and causes the sensor mechanism 22 to stop.
The extruding bar 43 of FIG. 1 rises (shown) by the operation of the cylinder (not shown) to close the orifice 40 by the spool 38, and the signal causes the conduit 62 of the vacuum valve mechanism 21 to flow.
The pressure fluid is sent to the valve body 60, and the valve body 60 rises (retracts) to close the hole 57 of the valve body 58 and disconnect the communication between the cavity 20 and the vacuum source.

Further, at the same time as the signal from the pressure switch 25, the hydraulic valve of the injection cylinder (not shown) for driving the plunger 18 is operated to advance the plunger 18 at a high injection speed and inject the molten metal 17 into the cavity 20. At this time, the cavity 20 is filled with high-quality low-pressure oxygen gas without air, so that a high-quality product without cavities can be obtained. When a good quality gas is a reactive gas, the molten metal reacts with the gas to form a compound that solidifies and the gas disappears, so that the cause of the nest can be removed. In the above description, after the fixed and movable molds 11 and 13 are in close contact with each other, the cavity 20
Is connected to a vacuum source, but the cavity 20 may be connected to the atmosphere without being connected to a vacuum source. Even in this case, the air in the cavity 20 is purged by the gas from the orifice 40, so that substantially the same effect can be obtained.

[0019]

According to the present invention, when the surface of the molten metal rises to the position of the orifice, 100% of the internal volume of the plunger sleeve is filled with the molten metal, and then the plunger is rapidly advanced or injected at high speed from the beginning. The casting cycle is shortened to improve the productivity, and the hydraulic control is simplified to reduce the cost. In addition, since the plunger sleeve is filled with molten metal by means of a feeding device such as an electromagnetic pump, it does not oxidize due to contact with air, and less heat is dissipated.
There is also an effect. Furthermore, since the time for communicating the vacuum valve mechanism with the vacuum source to reduce the pressure can be remarkably longer than in the conventional case, it is easy to sufficiently reduce the pressure in the cavity. As described above, since the hot water supply amount control, the injection control start, the vacuum valve mechanism closing control and the like are controlled by the signal from the orifice, there are advantages that the control device is simple, the cost is low and the reliability is high.

[Brief description of drawings]

FIG. 1 is an overall sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a sensor mechanism.

FIG. 3 is a sectional view of a vacuum valve mechanism.

[Explanation of symbols]

11 Fixed Die 12 Fixed Die Plate 13 Moving Die 14 Plunger Sleeve 15 Electromagnetic Pump 19 Gate 20 Cavity 21 Vacuum Valve Mechanism 22 Sensor Mechanism 23 Cylinder 24 Gas Pressure Control Valve 25 Pressure Switch 26 Gas Supply Section 30, 31 Hot Water Supply tube

Claims (1)

(57) [Claims] 1. A molten metal feeding device such as an electromagnetic pump is used to fill molten metal into a plunger sleeve connected to a cavity formed by a fixed mold and a movable mold through a gate part, and the molten metal feeding device gates the gate part. Is filled with molten metal
Cold chamber type die casting that detects that the gate part located above the uppermost part of the inner surface of the plunger sleeve is filled with the molten metal when the molten metal is injected into the cavity by the injection plunger device after detecting that In a molten metal sensor mechanism of a machine, it communicates with a hole having a small diameter and a large diameter that is attached to the movable die, and opens at the gate portion.
A sleeve having a conical surface hole that gradually decreases in diameter toward the gate portion at the end of the sleeve, and a sleeve having a conical surface slidably inserted into a small diameter hole of the sleeve and loosely inserted into a large diameter hole. The hole is a spool that has a minute gap and forms an orifice that allows gas to pass therethrough and does not allow molten metal to pass, an extrusion bar of a wedge mechanism that moves the spool forward and backward, and an elastic member that constantly presses the spool against the extrusion bar. A melt sensor for a cold chamber type die casting machine, comprising: a gas supply part having a pressure switch for supplying a gas to the orifice and detecting a back pressure of the orifice when the orifice is cut off by the melt. mechanism.