JP2004154815A - Filter apparatus for molten metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the exchange of a filter medium while securing required filtering performance in a filter apparatus for molten metal. <P>SOLUTION: The filter apparatus 10 mountable in an immersed way from the upper direction to the liquid face of a holding tank 12 is provided with a cylindrical body 14, and the lower end of the cylindrical body 14 is fitted with a cup-shaped filter medium 28 freely attachably and detachably. An annular piston 34 is inserted into the internal cavity of the cylindrical body 14 freely slidably vertically, a piston rod 36 is inserted via the central opening 34A of the annular piston 34, and a stopper pin 39 is fixed to the lower end of the piston rod 36. A valve plate 38 is fixed to the piston rod 36. On elevation of the piston 34, the valve plate 38 is separated from the piston 34, and molten metal is introduced into a cavity S1 at the lower face of the piston via the central opening 34A. On lowering of the piston 34, the valve plate 38 closes the central opening 34A, and the molten metal is pressure-fed via the cavity S1 and the filter medium 28. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a filter device for molten metal such as aluminum, which can be used for collecting inclusions in molten metal in a holding tank in an aluminum casting device.
[0002]
[Prior art]
In the casting of metal such as aluminum, inclusions such as impurities and oxides in the molten metal cause defects in the cast product, and a filter device is used for removing the inclusion in advance. Conventionally, as a filter device, a filter medium made of sintered ceramics or the like is provided, and the filter device is disposed at an inlet portion of a holding tank that holds the molten metal in the mold, and is placed in the molten metal when the molten metal is introduced into the holding tank. Existing inclusions are collected by a filter medium, and then the molten metal is introduced into the mold from a holding tank (Patent Document 1).
[0003]
[Patent Document 1]
JP-A-6-57342 [Problems to be solved by the invention]
In the prior art described in Patent Literature 1, a filter device is disposed at an inlet of a molten metal into a holding tank, and inclusions in the molten metal are collected by a filter medium. Thus, the melt can only undergo a filtering action once when it passes through the filter media, i.e. when it is introduced into the holding tank. Therefore, inclusions in the molten metal can be removed when the molten metal is introduced into the holding tank, but inclusions generated in the molten metal after being temporarily stored in the holding tank can be directly used for casting in the mold. , Causing defects in castings as products. On the other hand, if the filter medium can be provided immediately before the mold, it is ideal from the viewpoint of eliminating inclusions in the cast product, but it is structurally difficult, and the filter is provided in a holding tank provided for storing molten metal before the mold. Equipment had to be provided.
[0004]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a filter device that facilitates replacement of a filter medium while ensuring necessary filtration performance and has less restrictions on a mounting target.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a filter medium immersed in the liquid surface of the molten metal in the tank, and means for forming a circulating flow of the molten metal in the tank via the filter medium. A filter device for molten metal is provided.
[0006]
To explain the operation and effect of the first aspect of the invention, the molten metal in the tank is circulated through the filter medium, and the molten metal in the tank can be repeatedly passed through the filter medium. Therefore, the inclusions generated in the molten metal after being stored in the molten metal tank can be collected afterwards by passing through the filter medium, so that more ideal casting can be performed. Can be reduced.
[0007]
According to the invention described in claim 2, a body whose one end is located outside the molten metal tank and whose other end extends toward the liquid surface of the molten metal in the molten metal tank, and the main body is detachably attached to the molten metal tank from outside. A means for freely attaching, a filter medium fixed to the main body and collecting inclusions in the molten metal, and a means provided on the main body and forming a circulating flow of the molten metal in the molten metal tank through the filter medium. The present invention provides a filter device for molten metal, comprising:
[0008]
The operation and effect of the second aspect of the present invention will be described. The circulation of the molten metal in the tank is performed through the filter medium attached to the main body, and the interposition of the molten metal in the molten metal in the tank as in the first aspect of the invention. Objects can be collected on the filter medium. Then, by removing the main body, the filter medium can be easily replaced regardless of whether the furnace is a closed type or an open type. Further, since the main body is detachable from the outside of the furnace, the main body can be easily attached / detached, and thus the filter medium can be easily replaced.
[0009]
According to the invention as set forth in claim 3, it extends toward the liquid surface of the molten metal filled in the tank, and has a main body having an internal cavity, and is fixed to the main body so as to be immersed in the liquid surface of the molten metal, A filter member for collecting inclusions in the molten metal; and a means provided in the internal cavity of the main body and forming a circulating flow of the molten metal in the molten metal tank through the internal cavity and the filter material. The molten metal filter device described above is provided.
[0010]
The operation and effect of the third aspect of the present invention will be described. The metal melt is circulated in the tank through a filter medium mounted in the internal cavity of the main body. Inclusions in the molten metal can be collected on the filter medium. And since a main body is formed so that it may have an internal cavity, and a metal melt is circulated through the inside, a filter apparatus can be comprised compactly.
[0011]
According to the invention described in claim 4, in the invention described in any one of claims 1 to 3, the circulating flow forming means is connected to a reciprocating motion source and a reciprocating motion source, and reciprocates with respect to the main body. Therefore, it is characterized by comprising an alternate type of pressure feeding / suctioning means for performing the feeding of the molten metal through the filter medium during the forward movement and sucking the molten metal toward the front of the filtering medium during the return movement. A filter device for molten metal is provided.
[0012]
Explaining the operation and effect of the invention of claim 4, extrusion and suction are alternately performed by reciprocating motion, so that circulation of the molten metal through the filter medium can be induced. The extrusion pressure can be increased by the reciprocating mechanism, which makes the filter medium finer and is suitable for removing fine inclusions.
[0013]
According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the alternating pressure feeding / suctioning means is connected to an annular piston slidable in a cavity of the main body, and one end is connected to a reciprocating drive source. The other end is composed of a piston rod freely inserted through the center opening of the annular piston, and a valve plate fixed to the piston rod, and the valve plate is integrally moved with the piston when the piston goes forward. And pressing the molten metal toward the filter medium to separate the piston away from the piston when the piston goes home and permit the molten metal to be sucked in from the center opening of the annular piston. .
[0014]
The operation and effect of the invention of claim 5 will be described. The circulation of the molten metal can be reliably performed regardless of the simple mechanism including the annular piston, the valve plate and the piston.
[0015]
According to the invention described in claim 6, in the invention described in any one of claims 1 to 3, the circulating flow forming means includes a wing, and the space, the filter medium, and the hollow portion formed by a rotational motion of the wing. And forming a circulating flow of the molten metal between the two.
[0016]
The operation and effect of the invention according to claim 6 will be described. The rotation of the blades always causes a one-way flow of the molten metal through the filter medium, and causes the circulation of the molten metal through the filter medium at a large flow rate. It is suitable for efficient filtration of inclusions having a low pressure but a large particle size.
[0017]
According to the invention described in claim 7, in the invention described in any one of claims 1 to 6, the filter medium has a cup shape with one end closed, and the open end side of the filter medium is connected to the end of the main body. A filter device for molten metal is provided, which is provided with a detachably fixing means.
[0018]
The function and effect of the invention of claim 7 are as follows. By forming the filter medium into a cup shape, the filter medium can be easily attached to and detached from the main body, and the molten metal flows from the inside to the outside of the cup. The area can be obtained, and the filtration efficiency can be increased. In addition, since the inclusions are held inside the cup shape, the inclusions held inside the cup do not spill when the filter device is removed from the tank for replacement of the filter medium, and the tank is contaminated. There is no.
[0019]
According to an eighth aspect of the present invention, in the sixth aspect of the present invention, in the invention of any one of the first to fifth aspects, the fixing means separates and holds the filter medium with respect to the main body. And a filter device for molten metal.
[0020]
The function and effect of the invention of claim 8 will be described. By providing the spacer, the sealing performance between the filter and the main body can be improved, and the main body can be prevented from being damaged when the filter device is taken out.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a filter device 10 according to a first embodiment of the present invention mounted on a holding tank in a die casting system made of metal such as aluminum. Reference numeral 12 denotes a holding tank as the molten metal tank of the present invention, which has an inlet and an outlet (both not shown) for the molten metal, and has a heater (not shown) for maintaining a predetermined temperature of the molten metal on a wall surface. A control device (not shown) for maintaining the liquid level L of the molten metal M in the holding tank 12 at a predetermined level is provided.
[0022]
The filter device 10 of the first embodiment has a so-called throw-in type structure, is immersed from above toward the liquid level M of the molten metal, and is immersed in the molten metal M in the tank 12 through a filter medium as described later. This causes the circulating flow to occur, whereby inclusions in the molten metal in the tank 12 can be collected by the filter medium. The filter device 10 includes a cylindrical main body 14 (the main body of the present invention), and includes means for detachably attaching the upper end of the cylindrical main body 14 to the upper wall surface of the holding tank 12. This means comprises a split ring 16 for holding the upper end of the cylindrical body 14 and a base 18 on the outer peripheral side of the split ring 16. The cylindrical body 14 has a liquid level M through an opening 12 A formed in the upper wall of the tank 12. The base 18 is attached to the upper end of a mounting cylindrical base 22 that stands upright from the upper wall surface of the tank 12 with fasteners such as bolts 24 and nuts 26. Therefore, the filter device 10 can be easily attached to and detached from the tank 12 by fastening or loosening the bolt 24 and the nut 26. On the lower surface of the base 18, a tubular body 27 made of a heat insulating material is inserted into the opening 12 </ b> A while surrounding the tubular main body 14, so that the heat retaining property of the tank 12 can be secured.
[0023]
A cup-shaped filter medium (filter element) 28 having a closed lower end is disposed at the lower end of the cylindrical main body 14. The filter medium 28 has a porous structure composed of a sintered structure of a heat-resistant ceramic material such as silicon carbide, silicon nitride, silicon carbide, and alumina. When the molten metal passes through the filter medium 28, inclusions in the molten metal are formed. Can be blocked. The filter medium 28 is inserted into the lower end of the tubular body 14 via a tubular spacer 30 made of a heat-resistant material (for example, ceramics), and is fixed to the tubular body 14 by a pin 32 of a heat-resistant material (for example, ceramics). . The sealing property between the main body 14 and the filter medium 28 can be improved by interposing the spacer 30, and the spacer 30 protects the cylindrical main body 14 when the filter device 10 is pulled out of the holding furnace for replacing the filter medium 28. Also achieve the function of
[0024]
In the first embodiment, the means for forming the circulating flow of the molten metal through the filter medium 28 is of a reciprocating type, and includes an annular piston 34 made of carbon or the like, and a cylindrical piston rod made of high ceramics or the like. 36, and a valve plate 38 made of carbon or the like fixed to the cylindrical piston rod 36. The annular piston 34 is arranged so as to be slidable in the axial direction (vertical direction in FIG. 1) along the cavity in the cylindrical main body 14 while maintaining a close contact with the cylindrical main body 14. The hollow inside the cylindrical body 14 is partitioned into a lower portion S1 of the piston 34 and an upper portion S2 of the piston 34 by the annular piston 34. The lower end of the piston rod 36 is inserted through the center opening 34A of the annular piston 34, and a stopper pin 39 (see FIG. 2) made of high ceramics or the like is inserted and fixed to the piston rod 36 in the diameter direction below the center opening 34A. You. The length of the stopper pin 39 is slightly larger than the diameter of the center opening 34A of the piston 34, and can prevent the piston 34 from falling off. In the state of FIG. 1 in which the piston 34 contacts the stopper pin 39, there is a gap between the piston 34 and the valve plate 38, and the molten metal can flow through this gap. A plurality of circular communication openings 40 are formed on the peripheral surface of the cylindrical body 14 above the valve plate 38 at circumferential intervals, and the communication openings 40 are formed in the cylindrical body of the molten metal in the tank. 14 to be introduced into the internal cavity. The shape of the communication opening 40 is not limited to a circular shape, and may have any shape such as a long hole shape or a rectangular shape as long as it has a flow path area that allows a desired amount of molten metal to flow.
[0025]
The upper end of the piston rod 36 is fixed to the lower end of the connecting shaft 41 by a pin 42, and the upper end of the connecting shaft 41 is connected to the piston rod 44-1 of the air cylinder 44. A substrate 45 (made of stainless steel plate) on which the air cylinder 44 is fixed is fixed to an upper end flange 46-1 of a heat insulating material holder 46 fixed to the upper surface of the base 18 at the upper end of the cylindrical main body 14 with an eye bolt 49. You. The heat insulating material holder 46 has a cylindrical heat insulating material 50 on its inner periphery, and the connecting shaft 41 from the piston rod 44-1 of the air cylinder 44 extends concentrically through the hollow portion at the center of the heat insulating material 50. I have.
[0026]
The air cylinder 44 includes therein a piston and lower and upper chambers (not shown) of the piston. One end of each of the pneumatic pipes 47 and 48 is connected to the lower and upper chambers, and the other end of each of the pneumatic pipes 47 and 48. Is connected to an electromagnetic switching valve 51, and the electromagnetic switching valve 51 further includes an air pressure pipe 52 connected to a compressor (not shown). The electromagnetic switching valve 51 can be switched between a first position for guiding the air pressure from the compressor to the pipe 47 and a second position for guiding the air pressure from the compressor to the pipe 48 by a control device (not shown). In the first position, the air pressure is introduced into the chamber below the air cylinder 44 from the pipe 47, so that the piston rod 44-1 and the cylindrical piston rod 36 connected thereto rise as shown by the arrow a in FIG. (Return in the present invention). Conversely, at the second position, air pressure is introduced into the chamber above the air cylinder 44 from the pipe 48, so that the piston rod 44-1 and the cylindrical piston rod 36 connected thereto are as shown by the arrow b in FIG. (Going forward in the present invention).
[0027]
Next, the operation of the filter device of the present invention described above will be described. When the cylindrical piston rod 36 rises as shown by the arrow a because the electromagnetic switching valve 51 is at the first position, the lower end of the cylindrical piston rod 36 The stopper pin 39 is separated from the lower surface of the piston 34 at the beginning of the rising stroke, but comes into contact with the lower surface of the piston 34 when the rising stroke advances enough to fill the gap, and thereafter, the cylindrical piston rod 36 The piston 34 is raised as it rises as described above (return stroke of the piston 34 in the present invention is performed). The lower surface side portion S1 of the piston 34 in the internal cavity of the hollow body 14 is communicated with the molten metal M via the filter medium 28 having a large flow resistance, while the upper surface side portion S2 of the piston 34 in the internal cavity of the hollow body 14 is The molten metal M is communicated through the communication opening 40 having almost no flow path resistance. Therefore, the pressure of the hollow portion S1 is reduced with respect to the pressure of the hollow portion S2 due to the rise (return) of the piston 34 in the direction of the arrow a, and the molten metal M passes through the communication opening 40 as shown by the arrow c in FIG. Through the central opening 34A of the piston 34, as shown by the arrow c '.
[0028]
When the hollow portion S1 is filled with the molten metal, the electromagnetic switching valve 51 is switched to the second position, and the cylindrical piston rod 36 starts descending in the direction of arrow b as shown in FIG. At the start of this lowering movement, the valve plate 38 fixed to the cylindrical piston rod 36 is located upwardly separated from the piston 34 as shown in FIG. As the movement proceeds, the valve plate 38 comes into contact with and seats on the piston 34 as shown in FIG. 3, and thereafter, the piston 34 moves downward integrally with the valve plate 38 (the forward and backward movement of the piston of the present invention). Do a stroke). The central opening 34A is closed by the seating of the valve plate 38 on the piston 34, the flow of molten metal therethrough is stopped, and the subsequent lowering of the piston 34 increases the pressure in the hollow portion S1 on the lower surface side of the piston 34, and as a result, The melt filled in the hollow portion S1 at the time of the previous ascent stroke (during the retrace stroke) of the piston 34 overcomes the flow resistance of the filter medium 28 and is extruded into the holding tank through the filter medium 28 as indicated by an arrow d. When passing through the filter medium 28, inclusions in the molten metal are collected by the filter medium 28. That is, inclusions having a larger particle size than the pores of the filter medium 28 having a porous structure are restrained in front of the filter medium 28, and inclusions having a particle diameter smaller than the pores of the filter medium 28 can enter the filter medium 28, but most of them. Is adsorbed and held on the surface of the void inside the filter medium having a porous maze structure, and the molten metal stored in the holding tank for casting in the mold can be kept clean.
[0029]
The switching between the first position and the second position of the solenoid valve 51 described above is repeated at a predetermined cycle, and the molten metal from the holding tank to the hollow portion S1 in the filter device 10 when the piston 34 is raised (return stroke). (Arrow a) and the recirculation of the molten metal from the hollow portion S1 to the holding tank via the filter device 10 (arrow b) when the piston 34 descends (forward stroke) are alternately caused. As a result, a continuous and circulating flow of the molten metal M in the holding tank 12 can be realized via the cavities S2 and S1 in the cylindrical main body 14 and the filter medium 28. As a result, inclusions generated in the molten metal before the molten metal is filled into the holding tank 12 and before the molten metal is introduced into the casting mold can be filtered by the filter medium 28, and as a result, the molten metal can be reduced with less inclusions. Can be supplied from the holding tank 12 to the mold, which can contribute to the realization of a casting operation with fewer defects.
[0030]
When the filter medium 28 is clogged, the filter device 10 is removed from the holding tank 12 by loosening the bolt 24 and the nut 26, and the filter medium 28 is replaced. During the work, the filter medium 28 is collected by the filter medium 28 because the filter medium 28 has a closed cup shape, and the inclusions held due to the cup shape of the filter medium 21 are held without spilling. Does not pollute.
[0031]
In the first embodiment described above, the circulation of the molten metal is performed by repeating the extrusion of the molten metal at the time of the downward stroke (forward movement) of the piston 34 and the suction of the molten metal at the time of the upward stroke (return) of the piston 34. In the case of this method, since the extrusion pressure can be easily increased, the filter medium 28 can be relatively densely formed and the passage resistance can be increased. Therefore, the lower limit of the particle size of inclusions that can be collected should be set small. There are benefits.
[0032]
FIG. 4 shows a main part of a filter device 110 according to a second embodiment of the present invention. In order to obtain a circulating flow of the molten metal through a filter medium 128, the piston is rotated instead of reciprocating in the first embodiment. The wing 134 is used. That is, the upper end of the cylindrical main body 114 is mounted on the upper wall of the holding tank by the same means as the cylindrical main body 14 (FIG. 1) of the first embodiment, and the lower end of the cylindrical main body 114 is immersed in the molten metal in the mounted state. It is detachable by appropriate means such as bolts and nuts. As shown in FIG. 4, the rotary wing 134 is fixed to the lower end of the rotary shaft 136 in the internal cavity of the cylindrical main body 114. The upper end of the rotary shaft 136 is itself connected to a suitable rotary driving means such as a well-known hydraulic or electric motor (not shown), and the rotary blade 134 is continuously rotated by driving the motor as shown by an arrow f. I'm sullen. By the rotation of the rotary wings 134, the molten metal in the holding tank is sucked into the internal cavity of the cylindrical main body 114 through the opening 140 of the cylindrical main body 114 as shown by the arrow c, and at the same time, passes through the filter medium 128 as shown by the arrow d. Is returned to the holding tank. The inclusions in the molten metal can be continuously collected by the filter medium 128 by such a circulating flow c, d of the melt through the filter medium 128 under the rotational movement of the rotary blade 134.
[0033]
In the second embodiment described above, since the circulating flow is obtained by the rotation of the rotary wings 134, it is easy to increase the flow rate of the circulating flow, and the filter medium 28 is configured relatively coarsely to prevent the inclusions that can be collected. This is suitable when the lower limit of the particle size is set large and the collection speed is set high.
[0034]
The filter device of the present invention forms a circulating flow that passes through the filter medium at the storage portion of the molten metal, and becomes a final storage tank of the molten metal in the casting mold in the casting system in terms of collecting inclusions in the molten metal toward the casting mold. Particularly suitable for use in holding tanks. However, the present invention is not necessarily limited to use in a holding tank, and can be used in a melting tank, a molten metal heating tank, a molten metal processing tank, and the like which are usually provided in a casting system. It goes without saying that the molten metal bath in the present invention should be construed to include any of these.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a filter device according to a first embodiment of the present invention mounted on an upper wall surface of a holding tank, and shows a piston during a rising motion (return stroke).
FIG. 2 is a sectional view taken generally along the line II-II in FIG.
FIG. 3 shows the lower end of the filter device of FIG. 1, but during the downward movement (forward stroke) of the piston.
FIG. 4 is a longitudinal sectional view of a main part of a filter device according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Filter apparatus 12 ... Holding tank 14 ... Cylindrical main body 28 ... Filter medium 30 ... Spacer 34 ... Annular piston 36 ... Cylindrical piston rod 39 ... Stopper pin 40 ... Communication opening 44 ... Air cylinders 47, 48 ... Pneumatic pipe 51 ... Solenoid switching valve 52 Pneumatic pipes S1, S2 Hollow portion 110 Filter device 114 Cylindrical body 128 Filter material 134 Rotor blade

Claims (8)

A filter device for a molten metal, comprising: a filter medium immersed in a liquid surface of the molten metal in the tank; and means for forming a circulating flow of the molten metal in the tank through the filter medium. A main body having one end located outside the molten metal bath and the other end extending toward the liquid surface of the molten metal in the molten metal bath, means for detachably attaching the main body to the molten metal bath from the outside, and being fixed to the main body. A filter medium for collecting inclusions in the molten metal, and means provided on the main body and forming a circulating flow of the molten metal in the molten metal tank through the filter medium. Filter device. A main body having an internal cavity extending toward the liquid surface of the molten metal filled in the tank, and a filter medium fixed to the main body so as to be immersed in the liquid surface of the molten metal and collecting inclusions in the molten metal And means for forming a circulating flow of the molten metal in the molten metal tank through the internal cavity and the filter medium, the filter device being provided in the internal cavity of the main body. The invention according to any one of claims 1 to 3, wherein the circulating flow forming means is connected to a reciprocating motion source and a reciprocating motion source. A filter device for molten metal, comprising: an alternate type of pressure-feeding / suctioning means for performing pressure feeding of the molten metal, and sucking the molten metal toward the filter medium when returning. In the invention described in claim 4, the alternate type of pressure feeding / suction means has an annular piston slidable in a cavity of the main body, one end connected to a reciprocating drive source, and the other end connected to a center opening of the annular piston. It consists of a freely inserted piston rod and a valve plate fixed to the piston rod.When the piston moves in the forward direction, the valve plate moves in close contact with the piston to move the metal melt toward the filter medium. A filter device for molten metal, wherein the filter device is separated from the piston when the piston moves backward, and allows the molten metal to be sucked through the central opening of the annular piston. The invention according to any one of claims 1 to 3, wherein the circulating flow forming means forms a circulating flow of the molten metal between the space, the filter medium, and the hollow portion by a wing and a rotational motion of the wing. A filter device for molten metal, comprising: The invention according to any one of claims 1 to 6, wherein the filter medium has a cup shape with one end closed, and has means for detachably fixing an open end side of the filter medium to an end of the main body. Features Filter device for molten metal. 8. The filter device for molten metal according to claim 7, wherein the fixing means includes a spacer for keeping the filter medium separated from the main body.

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