JP2017015537A - Device for detecting liquid level of molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting the liquid level of molten metal with which, even when using a float as a liquid level sensor, it is possible to accurately detect the liquid level height of molten metal, with the float favorably tracking a change in the liquid level height.SOLUTION: The device comprises: a detection piece 61 provided with a float 61a floating on the liquid surface of molten metal 5 and a float shaft 61b extending upward from the float 61a; a guide member 62 having a guide hole 63 into which the float shaft 61b is inserted, for guiding the float shaft 61b by the inner circumferential surface 63a of the guide hole 63, thereby holding the detection piece 61 upright; and a laser displacement meter 67 for measuring the height position of the detection piece 61 and thereby detecting the liquid level height of the molten metal 5. A recess 64 is formed in the inner circumferential surface 63a of the guide hole 63.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a melt level detector for detecting the level of a melt.

  Conventionally, in a die casting apparatus, a fixed amount of molten metal (molten metal) is supplied to an injection sleeve provided in a mold, and then the molten metal filled in the injection sleeve is provided by a plunger tip provided at the tip of a plunger driven by hydraulic pressure. Die-casting is performed by feeding into the mold cavity (see Patent Document 1).

In such a die casting apparatus, for example, when the molten metal stored in the molten metal holding furnace is filled into the injection sleeve using an electromagnetic pump and the molten metal is supplied to the injection sleeve using the electromagnetic pump, the liquid in the molten metal holding furnace is used. Some are configured to control the supply amount of the molten metal constant by detecting the surface height and feeding back to the driving force of the electromagnetic pump.
In this case, in order to control the supply amount of the molten metal uniformly, it is important to accurately detect the liquid level of the molten metal. For example, the detection of the liquid level of the molten metal in the molten metal holding furnace This is done using a surface level sensor.

  In addition, as a liquid level sensor for detecting the liquid level, as disclosed in, for example, Patent Document 2, a float that floats on the liquid level of the molten metal stored in the molten metal holding furnace is connected to the float, A float shaft (vertical bar) extending above the melt holding furnace through a through-hole formed in the upper surface of the melt holding furnace, and measuring the vertical position of the upper end of the float shaft, Those configured to detect surface height are known.

JP 2012-223779 A JP-A 64-75142

As described above, when a float that floats on the surface of the molten metal is used as a liquid level sensor, the float and float axis move up and down as the liquid level of the molten metal changes, and the float axis moves to the molten metal holding furnace. Although it slides in the through hole on the upper surface, when the float shaft slides in the through hole, it may slide while contacting the inner peripheral surface of the through hole.
Thus, when the float shaft slides in contact with the inner peripheral surface of the through hole, the vertical movement of the float shaft is hindered by the sliding resistance between the float shaft and the inner peripheral surface of the through hole. However, there is a possibility that the liquid level of the molten metal cannot be detected accurately without following the change in the liquid level well.

  Therefore, in the present invention, even when a float is used as the liquid level sensor, the float follows the change in the liquid level of the molten metal, and accurately detects the liquid level of the molten metal. It is an object of the present invention to provide a liquid level detection device for molten metal.

The molten metal level detection apparatus that solves the above problems has the following characteristics.
That is, according to the first aspect of the present invention, the melt level detector includes a float that floats on the melt level, a detector that includes a float shaft that extends upward from the float, and the float shaft. A guide member that has a guide hole, guides the float shaft by an inner peripheral surface of the guide hole, holds the detector in a standing posture, and measures the height position of the detector to measure the molten metal. And a recess is formed on the inner peripheral surface of the guide hole.

  According to the present invention, it is possible for the float to follow the change in the liquid level of the molten metal satisfactorily and accurately detect the liquid level of the molten metal.

It is side surface sectional drawing which shows the die-casting apparatus provided with the liquid level detection apparatus of the molten metal. It is side surface sectional drawing which shows the liquid level detection apparatus of a molten metal. It is an expanded view which shows the internal peripheral surface of the guide member in the liquid level detection apparatus of a molten metal. It is an expanded view which shows the 2nd Example of the internal peripheral surface of a guide member. It is an expanded view which shows the 3rd Example of the internal peripheral surface of a guide member. It is side surface sectional drawing which shows a mode that the float shaft contacted the inner peripheral surface of the guide hole in the state in which the shaft center of the float shaft and the shaft center of the guide hole were parallel. It is side surface sectional drawing which shows the contact state of a float shaft and the internal peripheral surface of a guide hole when the inclination | tilt angle with respect to the guide hole of a float shaft becomes the maximum. It is side surface sectional drawing which shows the liquid level inspection apparatus of the molten metal which comprises the guide member in which the recessed part is not formed in the internal peripheral surface of a guide hole. In a melt level inspection apparatus having a guide member in which a recess is not formed on the inner peripheral surface of a guide hole, the float shaft is aligned with the guide hole in a state where the axis of the float shaft is parallel to the axis of the guide hole. It is side surface sectional drawing which shows a mode that it contacted the inner peripheral surface. The inner circumference of the float shaft and the guide hole when the inclination angle of the float shaft with respect to the guide hole is maximized in a molten metal liquid level inspection apparatus having a guide member in which the concave portion is not formed on the inner peripheral surface of the guide hole. It is side surface sectional drawing which shows a contact state with a surface. It is side surface sectional drawing which shows the test apparatus for measuring the change of the raising force of the detector by the inclination angle of a furnace cover. It is a figure which shows the relationship between the inclination angle of a furnace cover, and the raising force of a detector.

  Next, modes for carrying out the present invention will be described with reference to the accompanying drawings.

A die casting apparatus 1 shown in FIG. 1 is an embodiment of a die casting apparatus including a molten metal holding furnace provided with a molten metal level detecting device according to the present invention.
The die casting apparatus 1 includes a mold 10 in which a cavity 11 is formed, a substantially cylindrical injection sleeve 20 attached to the mold 10, an injection chip 30 that is slidably inserted into the injection sleeve 20, and a molten metal. The molten metal holding furnace 50 which stores 5 inside and the electromagnetic pump 40 for supplying the molten metal 5 in the molten metal holding furnace 50 to the injection sleeve 20 are provided.

The molten metal holding furnace 50 includes a liquid level detection device 60 for detecting the liquid level height of the molten metal 5 to be stored. Further, the molten metal holding furnace 50 has its upper opening closed by a furnace lid 51 and stores the molten metal 5 in a state of being cut off from the atmosphere.
The molten metal 5 stored in the molten metal holding furnace 50 is a molten metal such as aluminum. The molten metal holding furnace 50 and the furnace lid 51 are made of a refractory material.

One end of the electromagnetic pump 40 is inserted into the molten metal 5 in the molten metal holding furnace 50, and pumps the molten metal 5 by electromagnetic force in conjunction with injection control.
Hot water pipes 41 and 42 are connected to the other end of the electromagnetic pump 40, and the melt 5 pumped up by the electromagnetic pump 40 is supplied to the inside of the injection sleeve 2 through the hot water pipes 41 and 42. ing.
The hot water supply pipes 41 and 42 are connected to each other, and the hot water supply pipe 41 is disposed above the hot water supply pipe 42. And the upper end part of the hot water supply pipe 41 is connected to the other end part of the electromagnetic pump 40, and the lower end part of the hot water supply pipe 42 is disposed so as to face the hot water outlet 6 of the injection sleeve 20.

The hot water supply pipes 41 and 42 are connected to the injection sleeve 20 via the relay pipe 43. Specifically, the relay pipe 43 has a bellows structure bellows 43a which is a vibration absorbing portion and a heat insulating member 43b connected to the lower side of the bellows 43a, and a lower end portion of the heat insulating member 43b is the injection sleeve 20. The upper end of the bellows 43a supports the connecting portion between the upper hot water supply pipe 41 and the lower hot water supply pipe 42, thereby connecting the hot water supply pipes 41 and 42 to the injection sleeve 20.
In this way, by connecting the hot water supply pipes 41 and 42 to the injection sleeve 20 via the relay pipe 43, the hot water supply pipes 41 and 42 and the injection sleeve 20 are not brought into contact with the hot water supply port 21 at the lower end portion of the hot water supply pipe 42. And the displacement and vibration of the injection sleeve 20 are absorbed by the bellows 43a, and the displacement and vibration can be prevented from being transmitted to the hot water supply pipes 41 and 42.

The molten metal 5 pumped up by the electromagnetic pump 40 is supplied to the injection sleeve 20 from the lower end portion of the hot water supply pipe 42 through the hot water supply port 21.
In this case, the connection portion of the relay pipe 43 with the injection sleeve 20 and the connection portion with the hot water supply pipes 41 and 42 are sealed, and the hot water supply port 21 is entirely covered by the relay pipe 43, so that the hot water supply pipe 41 is provided. The molten metal 5 supplied into the injection sleeve 2 through the hot water supply port 21 from 42 does not come into contact with the atmosphere.

  The injection tip 30 inserted through the injection sleeve 20 is controlled so as to advance and retreat in the axial direction in the injection sleeve 20 by an actuator (not shown) composed of an air cylinder, a hydraulic cylinder or the like.

The cavity 11 of the mold 1 is communicated with the injection sleeve 20, and when the molten metal 5 supplied into the injection sleeve 20 is pushed out by the injection tip 30, the extruded molten metal 5 is injected into the cavity 11. Become.
The mold 10 communicates with the cavity 11 and is provided with a suction port 12 for sucking air in the cavity 11. A shut valve 13 is provided in a path connecting the cavity 11 and the suction port 12. . The suction port 12 is connected to a decompression unit, and the inside of the cavity 11 can be decompressed by the decompression unit.

  In the die casting apparatus 1 configured as described above, the molten metal supplied from the molten metal holding furnace 50 to the inside of the injection sleeve 20 via the hot water supply pipes 41 and 42 by the electromagnetic pump 40 in a state where the pressure in the cavity 11 is reduced by the pressure reducing means. 5 is extruded to the mold 10 side by the injection chip 30 and injected into the cavity 11 to perform die casting.

Next, the liquid level detection device 60 of the molten metal 5 provided in the molten metal holding furnace 50 will be described.
As shown in FIGS. 1 and 2, the liquid level detection device 60 is formed at a float 61a floating on the liquid level of the molten metal 5, a float shaft 61b extending upward from the float 61a, and an upper end portion of the float shaft 61b. The detector 61 having the detection surface 61c and the guide hole 63 through which the float shaft 61b is inserted are guided, and the detector 61 is held in an upright position by guiding the float shaft 61b with the inner peripheral surface of the guide hole 63. And a laser displacement meter 67 which is a detecting means for detecting the height of the liquid surface of the molten metal 5 by measuring the height position of the detection surface 61c of the detector 61.

The float 61a of the detector 61 has a maximum diameter part in the middle of the top and bottom, and is formed in a truncated cone shape whose diameter is reduced from the maximum diameter part downward from the maximum diameter part. The upper part is formed in a truncated cone shape that decreases in diameter as it goes upward from the maximum diameter part. The vertical dimension of the frustoconical part located at the lower part of the float 61a is formed larger than the vertical dimension of the frustoconical part located at the upper part.
The float 61a is made of, for example, a ceramic material, and a weight member 66 is embedded therein. The weight member 66 is embedded in a truncated cone-shaped portion located at the lower part of the float 61a, and is made of a member having a specific gravity higher than that of the ceramic material constituting the float 61a.

The float shaft 61b of the detector 61 is a rod-shaped member made of, for example, an austenitic stainless material, and is arranged along the vertical direction. The lower end portion of the float shaft 61 b is connected to the float 61 a, and the upper end portion extends to the upper outside of the molten metal holding furnace 50.
The detection surface 61c of the detector 61 is an upper surface of a disk-shaped portion that is formed at the upper end of the float shaft 61b and has a diameter larger than the shaft diameter of the float shaft 61b. The disk-shaped part on which the detection surface 61c is formed is also made of, for example, an austenitic stainless material.

The guide member 62 is a substantially cylindrical member having a guide hole 63 penetrating in the axial direction, and is made of, for example, an austenitic stainless material. The guide member 62 is fitted in a through hole 51 a formed in the furnace lid 51 of the molten metal holding furnace 50.
The guide member 62 is fitted in the through hole 51a in a posture in which the axial center is directed in the vertical direction (direction orthogonal to the plate surface of the furnace lid 51), and the length dimension L in the axial direction of the guide member 62 is The thickness is larger than the thickness dimension D of the furnace lid 51. The upper end of the guide member 62 is flush with the upper surface of the furnace lid 51, and the lower end portion of the guide member 62 projects downward from the lower surface of the furnace lid 51.

An inner diameter Φ2 of the guide hole 63 of the guide member 62 is formed larger than an outer diameter Φ1 of the float shaft 61b, and the float shaft 61b is slidably inserted into the guide hole 63.
A recess 64 is formed in the inner peripheral surface 63 a of the guide hole 63. The recess 64 is formed in an annular shape along the circumferential direction of the inner peripheral surface 63 a, and the inner diameter Φ3 of the recess 64 is formed larger than the inner diameter Φ2 of the guide hole 63.

As shown in FIG. 3, a plurality of recesses 64 are intermittently formed along the axial direction of the guide hole 63. On the inner peripheral surface 63 a of the guide hole 63, the recesses 64 are not formed. The portions where 64 is formed appear alternately along the axial direction.
In the present embodiment, there are three portions on the inner peripheral surface 63a where the concave portions 64 are not formed.

The concave portion 64 formed in the inner peripheral surface 63a shown in FIG. 3 is formed in an annular shape, but it is not necessarily formed in an annular shape, and the portion of the inner peripheral surface 63a where the concave portion 64 is not formed is What is necessary is just to form so that it may appear intermittently in the several location in the axial center direction of the guide hole 63 in all the phases of the circumferential direction of an internal peripheral surface.
For example, as shown in FIG. 4, in the developed view of the inner peripheral surface 63a, the portion of the inner peripheral surface 63a where the concave portion 64 is not formed is formed in a rectangular shape and arranged in a staggered manner in the circumferential direction and the axial direction. As described above, the concave portion 64 may be formed.
Further, as shown in FIG. 5, in the developed view of the inner peripheral surface 63a, the portion of the inner peripheral surface 63a where the concave portion 64 is not formed is formed in a circular shape and arranged in a staggered manner in the circumferential direction and the axial direction. As described above, the concave portion 64 may be formed.

Since the inner diameter Φ3 of the concave portion 64 formed in the inner peripheral surface 63a is formed larger than the inner diameter Φ2 of the guide hole 63, the float shaft 61b inserted through the guide hole 63 has the concave portion 64 in the inner peripheral surface 63a. It is possible to contact only the portion that is not formed, and does not contact the portion of the inner peripheral surface 63a where the concave portion 64 is formed (that is, the inner peripheral surface 64a of the concave portion 64).
Therefore, in the guide hole 63 in which the concave portion 64 is formed, the area of the inner peripheral surface 63a with which the float shaft 61b that slides in the guide hole 63 can contact is smaller than when the concave portion 64 is not formed in the guide hole 63. It is running low.

  Since the inner diameter Φ2 of the guide hole 63 is formed larger than the outer diameter Φ1 of the float shaft 61b, a predetermined clearance is formed between the inner peripheral surface 63a of the guide hole 63 and the outer peripheral surface of the float shaft 61b. In other words, the float shaft 61b can move within the clearance range in a direction orthogonal to the axial direction of the guide hole 63. The float shaft 61b can be tilted with respect to the axial direction of the guide hole 63 within the clearance.

As shown in FIG. 6, when the float shaft 61b contacts the inner peripheral surface 63a of the guide hole 63 in a state where the axis of the float shaft 61b and the shaft center of the guide hole 63 are parallel, the float shaft 61b The entire inner peripheral surface 63a is in contact with the portion where the concave portion 64 is not formed from the upper end side to the lower end side in the axial direction.
On the other hand, as shown in FIG. 7, when the axis of the float shaft 61 b is inclined to the maximum with respect to the axial direction of the guide hole 63 within the clearance, that is, the float shaft 61 b inserted through the guide hole 63. When the inclination angle θ with respect to the guide hole 63 becomes maximum, the float shaft 61b is located at the uppermost portion and the lowermost portion of the inner peripheral surface 63a where the concave portion 64 is not formed. It will be in contact only with the part.

The float shaft 61b is inclined with respect to the guide hole 63, and the float shaft 61b contacts only the uppermost portion of the inner peripheral surface 63a where the concave portion 64 is not formed and the lowermost portion. In this case, if the clearance between the guide hole 63 and the float shaft 61b is large and the inclination angle θ of the float shaft 61b with respect to the guide hole 63 becomes too large, galling occurs between the float shaft 61b and the guide hole 63, and the float shaft 61b may not be able to slide smoothly in the guide hole 63.
Accordingly, the concave portion 64 of the inner peripheral surface 63a is formed from the outermost diameter Φ1 of the float shaft 61b, the inner diameter Φ2 of the guide hole 63, and the portion located at the uppermost end of the portion of the inner peripheral surface 63a where the concave portion 64 is not formed. When the inclination angle θ of the float shaft 61b with respect to the guide hole 63 is maximized, the dimension Lt up to the position positioned at the lowermost portion of the portions that are not formed is galled between the float shaft 61b and the guide hole 63. It is preferable to set the dimensions so that they do not occur.

In the detector 61 configured as described above, when the detector 61 is in an upright posture and the float 61 a is floated on the liquid surface of the molten metal 5, for example, a truncated cone-shaped portion located below the float 61 a sinks into the molten metal 5. The frustoconical portion located at the upper part of the float 61 a is configured to protrude above the liquid surface of the molten metal 5.
In addition, since the detector 61 in the standing posture in which the float 61a floats on the liquid level guide member 62 of the molten metal 5 has a high center of gravity and cannot be completely self-supported, in the liquid level detection device 60, the float shaft 61b. Is inserted into the guide hole 63, and the float shaft 61b is guided by the inner peripheral surface 63a of the guide hole 63, so that the standing posture of the detector 61 is maintained. That is, the guide member 62 having the inner peripheral surface 63a of the guide hole 63 is a guide member disposed on the outer peripheral portion of the float shaft 61b, and the inner peripheral surface 63a of the guide member 62 becomes the guide surface of the float shaft 61b. Yes.

  Here, the standing posture of the detector 61 is a posture in which the float 61a is positioned at the lower end portion of the detector 61 and the axis of the float shaft 61b is in the vertical direction. However, the float shaft 61b is not necessarily in a completely vertical posture, and includes a case where the float shaft 61b is tilted with respect to the guide hole 63a within a clearance range with respect to the guide hole 63a.

The laser displacement meter 67 is disposed above the detector 61, irradiates the detection surface 61c with laser light, and receives the reflected light reflected by the detection surface 61c, thereby detecting the height position of the detection surface 61c. And the liquid level height of the molten metal 5 is detected based on the measured height position of the detection surface 61c.
Further, in the die casting apparatus 1, the liquid level height of the molten metal 5 detected by the laser displacement meter 67 is fed back to the electromagnetic pump 40 so that the pumping amount of the molten metal 5 by the electromagnetic pump 40 is controlled.

When the liquid level height of the molten metal 5 is detected by the laser displacement meter 67, the detector 61 moves up and down as the liquid level of the molten metal 5 changes, but when the detector 61 moves up and down, the float axis When 61b comes into contact with the inner peripheral surface 63a of the guide hole 63, the inner peripheral surface 63a is formed with the concave portion 64, even if it is in general contact from the upper end side to the lower end side in the axial direction. The area of the inner peripheral surface 63a where the shaft 61b actually contacts does not have the concave portion 64 is reduced, and the sliding resistance generated between the float shaft 61b and the guide hole 63 is small.
Therefore, the vertical movement of the float shaft 61 b is not hindered, and the detector 61 can follow the change in the liquid level height of the molten metal 5 well. Detection can be performed accurately.

On the other hand, when the guide member that guides the float shaft 61b is a guide member 162 in which a recess is not formed in the inner peripheral surface 163a of the guide hole 163 as shown in FIG. 8, for example, the axis of the float shaft 61b When the float shaft 61b comes into contact with the inner peripheral surface 163a of the guide hole 163 in a state where the shaft center of the guide hole 163 is parallel, the float shaft 61b moves from the upper end side to the lower end side of the inner peripheral surface 163a as shown in FIG. Overall contact. In this case, the float shaft 61b comes into contact in the entire range from the upper end to the lower end of the inner peripheral surface 163a, and the contact area between the float shaft 61b and the inner peripheral surface 163a is that of the inner peripheral surface 63a in which the recess 64 is formed. It becomes larger than the case. Accordingly, when the float shaft 61b comes into overall contact with the inner peripheral surface 163a, the sliding resistance generated between the float shaft 61b and the guide hole 163 increases, and the detector 161 changes in the liquid level of the molten metal 5. There is a risk that it will not be possible to follow this well.
For this reason, in the present embodiment, as described above, the recess 64 is formed in the inner peripheral surface 63a of the guide hole 63, and the contact area between the float shaft 61b and the inner peripheral surface 63a is reduced. By reducing the sliding resistance generated between the shaft 61 b and the guide hole 63, the detector 61 can follow the change in the liquid level height of the molten metal 5 satisfactorily.

  As shown in FIG. 10, in the case of the guide member 162 in which the concave portion is not formed on the inner peripheral surface 163a of the guide hole 163, the shaft of the float shaft 61b is within the clearance between the float shaft 61b and the guide hole 163. When the center is tilted to the maximum with respect to the axial direction of the guide hole 163, the float shaft 61b contacts only the uppermost portion and the lowermost portion of the inner peripheral surface 163a. It becomes.

Further, on the inner peripheral surface 63a of the guide hole 63, at least a portion where the concave portion 64 is not formed, that is, a portion where the float shaft 61b contacts is subjected to nitriding treatment (SP treatment), and the friction coefficient of the inner peripheral surface 63a. The sliding resistance between the float shaft 61b and the inner peripheral surface 63a when the float shaft 61b contacts the inner peripheral surface 63a is reduced.
Similarly, nitriding treatment (SP treatment) is also applied to the outer peripheral surface of the float shaft 61b to reduce the friction coefficient of the outer peripheral surface, and when the float shaft 61b contacts the inner peripheral surface 63a, The sliding resistance between the peripheral surface 63a is reduced.

  Moreover, in the detector 61, since the weight member 66 is embed | buried under the float 61a, the independence at the time of floating on the liquid level of the molten metal 5 compared with the case where the melt weight member 66 is not embed | buried is more. Even when the float shaft 61b is inclined and contacts the inner peripheral surface 63a, the contact strength of the float shaft 61b with respect to the inner peripheral surface 63a is not high, that is, the float shaft 61b makes light contact with the inner peripheral surface 63a. Therefore, the sliding resistance between the float shaft 61b and the inner peripheral surface 63a can be reduced.

Further, the guide member 62 and the float shaft 61b are made of an austenitic stainless material, thereby improving the oxidation resistance and reducing the oxidation due to the heat of the molten metal 5. Thereby, it can suppress that the sliding resistance between the float axis | shaft 61b and the internal peripheral surface 63a becomes large with the increase in the operation time of the die-casting apparatus 1. FIG.
Further, a coating agent having a heat insulating property is applied to the inner peripheral surface 64 a of the recess 64 formed in the inner peripheral surface 63 a of the guide member 62, thereby improving the heat resistance of the guide member 62.

  Further, in the present embodiment, in the inner peripheral surface 63a of the guide member 62, the portion where the concave portion 64 is not formed is formed at three places, but it is formed at two places or at more places than three places. It is also possible to do.

Further, in the liquid level detection device 60, the lower end portion 62 a of the guide member 62 protrudes downward from the lower surface of the furnace lid 51, so that a foreign material such as a refractory material that constitutes the furnace lid 51 falls below the guide hole 63. Can be prevented from entering. Thereby, it is possible to prevent the foreign matter from entering the gap between the guide hole 63 and the float shaft 61b and increasing the sliding resistance between the float shaft 61b and the inner peripheral surface 63a.
The length dimension L of the guide portion 62 is 110 mm or more when the thickness dimension D of the furnace lid 51 is, for example, 102 mm in order to project the lower end portion of the guide member 62 below the lower surface of the furnace lid 51. Can be set to the dimension.

The configuration in which the lower end portion of the guide member 62 protrudes downward from the lower surface of the furnace lid 51 is also applied to the guide member 162 in which the concave portion is not formed on the inner peripheral surface 163a of the guide hole 163 shown in FIG. Can do.
That is, even in the guide member 162 in which the concave portion is not formed on the inner peripheral surface 163a, the lower end portion 162a protrudes downward from the lower surface of the furnace lid 51, and the foreign matter enters the gap between the guide hole 163 and the float shaft 61b. Can be prevented.

Further, in the guide member 62, the position located at the lowest end of the portion of the inner peripheral surface 63a where the concave portion 64 is not formed, that is, the lower end of the portion of the inner peripheral surface 63a that the float shaft 61b contacts is the guide member 62. It is comprised so that it may be located above the lower end of.
Thus, the float shaft 61b in the inner peripheral surface 63a contacts the liquid surface of the molten metal 5 by positioning the lower end of the portion of the inner peripheral surface 63a in contact with the float shaft 61b above the lower end of the guide member 62. The size up to the lower end of the part to be increased. Thereby, the molten metal 5 is suppressed from entering the gap between the guide hole 63 and the float shaft 61b, and it is possible to prevent the sliding resistance between the float shaft 61b and the inner peripheral surface 63a from increasing.

  Next, when the float shaft 61 b slides in the guide hole 63 in the liquid level detection device 60, sliding resistance generated between the float shaft 61 b and the inner peripheral surface 63 a of the guide hole 63, and the furnace lid 51 The relationship between the inclination angle θc, that is, how the magnitude of the sliding resistance generated between the float shaft 61b and the inner peripheral surface 63a changes depending on the inclination angle θc of the furnace lid 51 was tested. So I will explain.

As shown in FIG. 11, in this test, the lifting force required when the detector 61 in a state where the float 61 is floating on the liquid surface of the molten metal 5 is lifted upward is used as the float axis of the detector 61. The sliding resistance generated between 61b and the inner peripheral surface 63a of the guide hole 63 was measured.
Further, the lifting force of the detector 61 was measured by changing the inclination angle θc of the furnace lid 51 with respect to the horizontal direction by interposing a spacer 70 between the molten metal holding furnace 50 and the furnace lid 51. In this case, the inclination angle θc of the furnace lid 51 was confirmed by an inclinometer 71 installed on the upper surface of the furnace lid 51. The inclination angle θc of the furnace lid 51 was changed in the range of 0 ° to 10 °.

The lifting force of the detector 61 was measured with a load cell connected to the detector 61. The molten metal 5 used at the time of measurement was an aluminum alloy (ADC12), and the temperature of the molten metal 5 at the time of measurement was 680 ° C. The detector 61 was lifted from the lower end to the upper end in a predetermined range of lifting stroke S in the vertical direction.
Measurement of the lifting force of the detector 61 is performed when the guide member 62 (the guide portion in which the concave portion 64 is formed on the inner peripheral surface 63a of the guide hole 63) is used for the liquid level detection device 60, and the guide member 162 (guide hole). The case where a guide portion in which a concave portion is not formed on the inner peripheral surface 163a of 163 is used.
The inner diameter Φ2 of the guide hole 63 in the guide member 62 and the inner diameter Φ2 of the guide hole 163 in the guide member 162 are set to the same diameter, and the clearance between the float shaft 61b and the guide hole 63, and the float shaft 61b The clearance with the guide hole 163 has the same dimension.

FIG. 12 shows the measurement results of the pulling force of the detector 61.
When the guide member 162 in which the concave portion is not formed on the inner peripheral surface 163a of the guide hole 163 is used, the lifting force of the detector 61 increases as the inclination angle θc of the furnace lid 51 increases from 0 °. .

  Here, when the detector 61 is pulled up, buoyancy from the molten metal 5 acts on the float 61 a floating on the liquid surface of the molten metal 5, and the float shaft 61 b inserted through the guide hole 163 has a guide hole. Since the inside of the guide hole 163 can move freely in the horizontal direction, the horizontal position of the float shaft 61b in the guide hole 163 and the inclination angle with respect to the guide hole 163 change from time to time, and the float shaft 61b has a shape as shown in FIG. A state in which the entire contact with the inner peripheral surface 163a of the guide hole 163 and a state in which only the upper end and the lower end of the inner peripheral surface 163a of the guide hole 163 are in point contact as shown in FIG. Become.

When the inclination angle θc of the furnace lid 51 is 0 °, the float shaft 61b is not frequently in contact with the inner peripheral surface 163a of the guide hole 163, and the float shaft 61b and the guide hole 163 are not frequently contacted. Since the sliding resistance between the detector 61 and the detector 61 is not so high, the lifting force of the detector 61 is not so high.
When the inclination angle θc of the furnace lid 51 is increased from 0 °, the frequency at which the float shaft 61b is in contact with the inner peripheral surface 163a increases, and the float shaft 61b and the guide hole are increased. Since the sliding resistance with respect to H.163 increases, the pulling force of the detector 61 also increases as the inclination angle θc of the furnace lid 51 increases.

  On the other hand, even when the guide member 62 in which the concave portion 64 is formed on the inner peripheral surface 63a of the guide hole 63 is used, the lifting force of the detector 61 increases as the inclination angle θc of the furnace lid 51 increases from 0 °. However, the magnitude of the pulling force is significantly smaller than that in the case where the guide member 162 in which the concave portion is not formed on the inner peripheral surface 163a is used.

  This is because the sliding resistance between the float shaft 61b and the guide hole 63 increases as the inclination angle θc of the furnace lid 51 increases even when the guide member 62 having the recess 64 formed on the inner peripheral surface 63a is used. Although it becomes larger, even when the axial center of the guide hole 63 and the axial center of the float shaft 61b are parallel to each other, the portion of the inner peripheral surface 63a that contacts the float shaft 61b is not formed with the recess 64. This is because the contact area between the float shaft 61b and the inner peripheral surface 63a is reduced, and the sliding resistance between the float shaft 61b and the guide hole 163 is not increased.

As shown in FIG. 12, in the lifting force of the detector 61, the maximum stable movable lifting force F that allows the detector 61 to always move following the change in the liquid level of the molten metal 5 is set. The range below the maximum stable movable lifting force F is the stable movable range of the detector 61.
In the case of using the guide member 62 in which the recess 64 is formed on the inner peripheral surface 63a, when the inclination angle θc of the furnace lid 51 is 5 °, the lifting force of the detector 61 is the maximum movable lifting force F. If the inclination angle θc of the furnace lid 51 is 5 ° or less, the detector 61 can follow the change in the liquid level of the molten metal 5 and slide stably. I understand that.
Further, in the actual usage situation of the liquid level detection device 60, the inclination angle θc of the furnace lid 51 with respect to the horizontal direction is 5 ° or less, so the guide member 62 in which the concave portion 64 is formed on the inner peripheral surface 63a is used. Thus, it is possible to accurately detect the liquid level of the molten metal 5 by the laser displacement meter 67 by causing the detector 61 to always follow the change in the liquid level of the molten metal 5 satisfactorily.

DESCRIPTION OF SYMBOLS 1 Die-casting apparatus 10 Mold 11 Cavity 20 Injection sleeve 30 Injection chip 40 Electromagnetic pump 50 Molten metal holding furnace 51 Furnace lid 60 Liquid level detector 61 Detector 61a Float 61b Float shaft 61c Detection surface 62 Guide member 63 Guide hole 63a Inner circumference Surface 64 Concavity 67 Laser displacement meter

Claims (1)

A detector that includes a float that floats on the surface of the molten metal, and a float shaft that extends upward from the float;
A guide member having a guide hole through which the float shaft is inserted, and holding the detector in an upright posture by guiding the float shaft by an inner peripheral surface of the guide hole;
A detecting means for detecting the height of the molten metal by measuring the height position of the detector;
A recess is formed on the inner peripheral surface of the guide hole.
An apparatus for detecting the level of molten metal.

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