JP2017194233A - Cold Crucible Melting Furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold crucible melting furnace enabling a state in which an induction current [eddy current] circulating around a tubular cooling water passage in each of the segments to be prevented*restricted, a loss of fed electrical power caused by the induction heating at a crucible to be reduced and a melting efficiency to be increased.SOLUTION: A barrel part 10 of a crucible 1 is constituted in such a way that several segments 2 having a tubular water-cooled passage C1 extending in a height direction formed therein are arranged in a peripheral direction through vertical slits 3 closed by insulation materials 4. As segments 2, at least one wall part of an outer peripheral wall part 22B and two side walls 22C, 22D is formed with a releasing part 24 connected from outsides of the segments 2 to the water-cooled passage C1, and the releasing part 24 is closed with a water-tight material 25 with a higher electric resistivity than that of an inner peripheral wall part 22A to make a cold crucible melting furnace X.SELECTED DRAWING: Figure 2

Description

  The present invention dissolves refractory metals and active metals, does not mix non-metals, achieves high purity, and can dissolve metals with uniform components and temperature in a molten metal pool in a water-cooled copper crucible. Related to a cold-crucible melting furnace.

  Conventionally, a cold crucible melting furnace has been used as a melting furnace for metals having a high melting point such as titanium. The crucible of a cold crucible melting furnace includes a cylindrical body portion having a plurality of segments that are partially arc-shaped in plan view and arranged adjacent to each other through slits in the circumferential direction, and a bottom portion. The insulating material which has property is arrange | positioned. With such a configuration, adjacent segments are electrically insulated from each other, and the magnetic flux generated by the induction heating coil disposed on the outer periphery of the body portion can be efficiently introduced into the crucible, and the molten metal can enter through the slit. Is preventing.

  Each segment is formed with a water cooling passage that constitutes a part of the cooling means. As an example of a water-cooled passage, an inner pipe is arranged in a segment with a predetermined clearance between the inner peripheral surface of the hole inside a hole with a circular cross section formed along the standing direction of the segment. Then, the gap between the inner peripheral surface of the hole and the outer peripheral surface of the inner pipe is used as a path of the rising water flow to be ejected along the rising direction of the segment, and the rising water flow is 180 near the upper end portion in the vicinity of the upper end portion of the closed hole. There can be mentioned a double-structured passage where the inner space of the inner pipe is used as the path of the descending water flow (for example, Patent Document 1 below).

  When melting the metal to be melted contained in the crucible of such a cold crucible melting furnace, the metal to be melted is induction-heated by an induction heating coil, and the crucible is cooled by passing cooling water through the cooling water channel. As a result, since the metal to be melted accommodated in the crucible is extracted at the outer peripheral side, the melted metal is cooled and solidified skull is formed on this outer peripheral side, and only the inside is melted. For this reason, the molten metal in which the metal to be melted is not brought into contact with the crucible by the skull, and even if the molten metal is brought into contact with the crucible by shaking, the crucible is sufficiently cooled and does not react and does not cause contamination.

JP 2002-277169 A

  By the way, in the conventional structure, 30% to 50% of the input electric power contributes to melting, while about several tens of% of the input electric power is lost by the induction heating coil (coil loss) or by the induction heating of the crucible. become. In particular, the loss due to induction heating of the crucible is about 30% of the input power. As shown in FIGS. 6 and 7, this is because the induction heating coil H is arranged on the outer periphery of the crucible 1 in which the plurality of segments 2 are connected in the circumferential direction via the slits 3. When a high-frequency current is applied, an induced current (an eddy current whose current direction is indicated by an arrow in FIG. 7) that circulates in the tubular cooling water channel C1 is generated in each segment 2, and this is the main cause. The greater the loss of input power, the lower the dissolved power and the very poor efficiency, so there is room for improvement. In FIG. 6, a member denoted by reference numeral 4 is an insulating material having fire resistance arranged in the vertical slit 3 without any gap.

  Therefore, a configuration in which the mutual inductance between the crucible and the induction heating coil is reduced by setting the thickness in the circumferential direction and the radial direction of the segment to be thin is also conceivable. However, as the thickness in the circumferential direction and the radial direction of the segment is reduced, the strength of the segment is reduced, and there is a possibility that the segment is deformed by the heat during the melting process. In addition, if the thickness in the circumferential direction and the radial direction of the segment is set thin, the size (opening shape) of the cooling water channel formed in the segment must be set small. As the size (opening shape) of the cooling water channel is reduced, the cooling capacity of the cooling means using the cooling water channel is reduced, which may lead to deformation and melting of the crucible itself.

  The present invention has been made paying attention to such points, and its main purpose is to prevent and suppress the occurrence of induced current (eddy current) that circulates in the tubular cooling water channel in each segment. An object of the present invention is to provide a cold crucible melting furnace capable of reducing the loss of input power due to induction heating of the crucible and increasing the melting efficiency.

  That is, the present invention relates to a cold crucible melting furnace capable of melting a metal to be melted in a crucible by induction heating with an induction heating coil disposed on the outer periphery of a body portion of the crucible.

  In the cold crucible melting furnace according to the present invention, as the body portion, a plurality of segments in which tubular water-cooling passages extending in the height direction are formed are radially extended along the radial direction of the body portion. And applying what is arranged in a state of being arranged in the circumferential direction through a vertical slit closed with a predetermined insulating material, the segment is an inner peripheral wall part forming a region radially inward from the water cooling passage, and a water cooling passage An outer peripheral wall portion that forms a radially outer region, and two side wall portions that form a region between the inner peripheral wall portion and the outer peripheral wall portion and face each other across the water cooling passage in the circumferential direction, and At least one wall portion of the outer peripheral wall portion or the two side wall portions is formed with an open portion communicating with the water cooling passage from the outside of the segment, and the open portion is closed with a watertight material having a higher electrical resistivity than the inner peripheral wall portion. To be It is characterized.

  According to such a cold crucible melting furnace according to the present invention, the segments divided and formed in the circumferential direction are arranged on the outer periphery of a crucible that is an aggregate joined together through a vertical slit closed with an insulating material. The induction heating coil is energized, an induction magnetic field is introduced into the crucible through the vertical slit, penetrates into the metal to be melted, can be heated by induction, and communicates with the water cooling passage from the outside of the segment. Since the open part formed so as to be blocked by a watertight material having a higher electrical resistivity than the inner peripheral wall part that forms a radially inner region of the peripheral wall part than the water-cooled path, the water-cooled path is changed to the open part. Prevents the leakage of cooling medium such as cooling water and ensures a good water cooling function, and eddy currents that circulate in the water cooling passages flow in each segment. It is possible to significantly prevention and inhibition. As a result, the loss of input power due to induction heating of the crucible can be greatly reduced, and the melting efficiency is improved.

  As described above, in the present invention, an open portion communicating with the water cooling passage from the outside of the segment is formed on at least one wall portion of the outer peripheral wall portion or the two side wall portions, and this open portion is more electrically connected than the inner peripheral wall portion. It is characterized in that it is blocked by a watertight material having a high resistivity, and the part forming the open part may be only the outer peripheral wall part, only one side wall part, or only both side wall parts. Moreover, you may form an opening part in an outer peripheral wall part and a both-sides wall part, respectively. The shape and number of the open portions can be appropriately selected and changed, and the open portions can be appropriately closed by applying a watertight material according to the shape of the open portions.

  In particular, in the cold crucible melting furnace according to the present invention, the radial thickness of the inner peripheral wall portion and the outer peripheral wall portion of the segment and the circumferential thickness of each side wall portion are determined by the penetration depth of the magnetic field created by the induction heating coil. If the thickness is set to be less than the penetration depth of electromagnetic induction, the eddy current generated in the segment can be reduced, the loss of input power due to induction heating of the crucible can be further reduced, and the melting efficiency can be reduced. A further rise can be achieved.

  Thus, in the present invention, among the segments constituting the crucible body, at least one wall portion of the peripheral wall portion or the two side wall portions is formed so as to communicate with the water cooling passage from the outside of the segment. Since the open portion is closed by a watertight material having a higher electrical resistivity than the inner peripheral wall portion, each segment is divided by the open portion and the watertight material around the tubular water-cooled passage, and each segment is tubular. Cold-crucible melting that does not generate induction current (eddy current) that circulates in the cooling water passage or is difficult to generate, reduces loss of input power due to induction heating of the crucible, and increases melting efficiency A furnace can be provided.

The typical fragmentary sectional view of the cold crucible melting furnace which concerns on one Embodiment of this invention. The figure which shows typically the principal part of the cold crucible melting furnace which concerns on the same embodiment partially in cross section. The plane sectional view which omits some principal parts of the cold crucible melting furnace concerning the embodiment, and shows typically. The plane sectional view which omits some segments in the embodiment and shows typically. The figure which shows the modification of the segment applicable with the cold crucible melting furnace which concerns on the embodiment corresponding to FIG. The figure which shows the conventional cold crucible melting furnace corresponding to FIG. The figure which shows the segment applied with the conventional cold crucible melting furnace corresponding to FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the cold crucible melting furnace X according to the present embodiment includes a crucible 1 that is a furnace body that accommodates a metal W to be melted, and an induction heating coil H that is disposed on the outer periphery of a body portion 10 of the crucible 1. And a frame K arranged at the lower end of the crucible 1 to support the crucible 1 and a cooling means C for cooling the crucible 1, and the metal W to be melted is induction-heated by the induction heating coil H in the water-cooled crucible 1. It can be dissolved in a semi-floating state. The cold crucible melting furnace X of the present embodiment is installed in an airtight container (not shown) and can perform the melting process of the metal W to be melted in a reduced pressure atmosphere (including a vacuum atmosphere).

  The crucible 1 is configured by connecting a plurality of conductive segments 2 (hereinafter “segment 2”) in the circumferential direction via vertical slits 3. As shown in FIG. 1, the segment 2 includes a bottom 21 formed so as to constitute a bottom wall of the crucible 1, a peripheral wall 22 constituting a side wall of the crucible 1, and a crucible 1 from a lower end of the peripheral wall 22. And a mounting portion 23 that is fastened to the flange portion K2 of the gantry K with a bolt B and a nut N.

  The body portion 10 of the crucible 1 is shown in FIG. 2 (the figure shows the body portion 10 and a part thereof is shown as a cross-sectional view for convenience of explanation). The vertical slits 3 that are constituted by the peripheral wall portions 22 of the plurality of segments 2 arranged in the circumferential direction and extend radially along the radial direction are closed with a predetermined insulating material 4. In FIG. 2, the bottom portion 21 and the attachment portion 23 of the segment 2 are omitted. In the cold crucible melting furnace X according to the present embodiment, a crucible 1 is formed by a plurality of segments 2 to open the upper part and accommodate the metal W to be melted.

  Each segment 2 is excellent in electrical conductivity and thermal conductivity, resistant to thermal shock, has necessary mechanical strength, and high heat necessary for forming the skull Wa (see FIG. 1) by cooling by the cooling means C. A material having conductivity, for example, copper or a metal material such as chromium copper, beryllium copper, zirconium copper, chromium zirconium copper, tellurium copper or the like is used. In addition, materials such as stainless steel, nickel-base alloy hastelloy, and Inconel can be used as long as the melting point of the molten metal is relatively low and does not cause a reaction with the crucible.

  A water-cooled passage C1 extending in the height direction is formed inside the peripheral wall portion 22 of each segment 2. The water cooling passage C1 constitutes the cooling means C. As shown in FIG. 1 and the like, the water-cooled passage C1 in the present embodiment has a hollow portion C2 having a substantially circular cross section continuously formed in a region extending from the lower end of the peripheral wall portion 22 to a position slightly below the upper end. In the hollow portion C2, a double structure is constituted by a cylindrical inner pipe C3 arranged in a standing posture with a gap of a predetermined dimension from the inner peripheral surface of the hollow portion C2. In FIG. 1, the inner pipe C3 is schematically shown by a simple solid line.

  As shown in FIG. 1, the water cooling passage C1 in the segment 2 includes an outward water passage (intra-segment internal water passage C4) using a gap between the inner peripheral surface of the cavity C2 and the outer peripheral surface of the inner pipe C3, and an inner pipe C3. And a condensate channel using the internal space (intra-segment condensate channel C5). The in-segment outbound water channel C4 and the in-segment condensate channel C5 are configured to be continuous with each other at the upper end portion of the segment 2. In FIG. 1, the flow direction of the cooling water flowing through the water cooling passage C1 (intra-segment forward water passage C4, intra-segment condensate passage C5) is schematically indicated by arrows.

  The cold crucible melting furnace X of the present embodiment includes an intra-segment water channel C4 and a segment in a space formed between a columnar portion K1 of a gantry K, which will be described later, and a space K2 of the gantry K and the segment 2. Each condensate channel C5 has a continuous water channel. Specifically, an upstream water discharge channel C6 that is formed below the segment 2 and continues to the intra-segment water discharge channel C4, and a downstream water supply channel C7 that is formed below the segment 2 and continues to the intra-segment condensate channel C5; Is formed. In FIG. 1, the flow direction of the cooling water flowing through the upstream outgoing channel C6 and the downstream condensate channel C7 is schematically indicated by arrows.

  A cooling water supply source (not shown) is connected to the upstream end of the upstream water supply channel C6, and the cooling water supplied from this cooling water supply source is connected to the upstream water supply channel C6, the intra-segment outgoing water channel C4, and the intra-segment condensate water channel. By circulating the C5 and the downstream condensate channel C7 in this order, the entire crucible 1 including the body portion 10 can be cooled to be sufficiently lower than a predetermined temperature (reaction temperature with the metal W to be dissolved). Is possible. By this cooling, it is possible to form the skull Wa on the inner surface of the crucible 1. In addition, the cooling water discharged | emitted from the downstream end of the downstream side condensate channel C7 is collect | recovered by the appropriate collection | recovery part. Various liquids (including gels) other than water and gas may be used as the cooling fluid.

  3 and 4 (FIG. 3 schematically shows a view cut along a horizontal plane at a predetermined height position of the peripheral wall portion 22 of the peripheral wall portion 22 constituting the body portion 10 of the crucible 1 in each segment 2. FIG. 4 schematically shows a view of the segment 2 cut along a horizontal plane at a predetermined height position. In FIGS. 3 and 4, parallel diagonal lines to be attached to the cut surface of the peripheral wall portion 22. 2), the planar shape is defined by partial arc-shaped inner peripheral surface 22a and outer peripheral surface 22b, and side surfaces 22c and 22d that connect both ends of outer peripheral surface 22b and inner peripheral surface 22a, respectively. Is. The angle of the arc of the outer peripheral surface 22b and the inner peripheral surface 22a of the peripheral wall portion 22 is obtained by dividing 360 by the number of segments 2 in the circumferential direction of the body portion 10 of the crucible 1, that is, 360 (one round 360 °). The angle is approximately equal to a value obtained by subtracting the dimension in the circumferential direction of the vertical slit 3 from the obtained value.

  In the present embodiment, a ceramic refractory material such as alumina, zirconia, or yttria is applied as the insulating material 4 that closes the vertical slit 3. In FIG. 1 thru | or FIG. 3, the insulating material 4 which obstruct | occludes the vertical slit 3 is attached | subjected and shown with the predetermined pattern. The insulating material 4 that closes the vertical slit 3 may be any insulating material and fire-resistant material. Non-inductive material such as mortar filled in the vertical slit 3 or insulation with a predetermined film thickness disposed in the vertical slit 3. It is possible to apply a conductive thin film or the like as an insulating material.

  With such a configuration, the adjacent segments 2 in the body portion 10 of the crucible 1 can be electrically insulated, and the magnetic flux generated by the induction heating coil H can be efficiently introduced into the crucible 1, and the vertical slit 3 The intrusion of the molten metal Wb is prevented.

  Here, as shown in FIGS. 3 and 4, the vertically long peripheral wall portion 22 in the segment 2 in the present embodiment includes an inner peripheral wall portion 22A that forms a region radially inward of the water cooling passage C1, and a water cooling passage C1. The outer peripheral wall portion 22B that forms a radially outer region, and the two side wall portions 22C that form a region between the inner peripheral wall portion 22A and the outer peripheral wall portion 22B and face each other across the water cooling passage C1 in the circumferential direction. , 22D can be distinguished. And the cold crucible melting furnace X which concerns on this embodiment forms the open part 24 connected to the water-cooling channel | path C1 from the exterior of the segment 2 only to the outer peripheral wall part 22B among the peripheral wall parts 22, and this open part 24 is used as a peripheral wall. A water-tight material having an electrical resistivity higher than that of the portion 22 other than the open portion 24 (all of the inner peripheral wall portion 22A, all of the side wall portions 22C and 22D, and the outer peripheral wall portion 22B excluding the open portion 24). 25. Specifically, an open portion 24 that communicates with the water cooling passage C1 from the outside of the segment 2 is formed in the central portion in the circumferential direction of the outer peripheral wall portion 22B, and the watertight material 25 is disposed in the open portion 24 without a gap. .

  The open part 24 and the watertight member 25 are set to a height dimension facing at least the induction heating coil H disposed on the outer periphery of the body part 10 of the peripheral wall part 22. Examples of the electrically insulating and watertight material include rubber, synthetic resin, ceramic, nonmagnetic stainless steel, and the like, and the watertight material 25 is formed from a material appropriately selected from these materials. In this embodiment, the peripheral wall part 22 which comprises the trunk | drum 10 of the crucible 1 among the segments 2 has all the inner peripheral wall parts 22A, all the side wall parts 22C and 22D, and the open part 24 among the outer peripheral wall parts 22B. The part to be removed is integrally formed from the same material. Therefore, it can be understood that the peripheral wall portion 22 is a portion in which only a predetermined portion is divided by the opening portion 24 in the direction of circling the water cooling passage C. In FIG. 1 to FIG. 4, the watertight material 25 is shown with a predetermined pattern different from that of the insulating material 4 described above.

In the present embodiment, the penetration depth of the magnetic field created by the induction heating coil H (the thickness in the radial direction of the inner peripheral wall portion 22A and the outer peripheral wall portion 22B and the thickness in the circumferential direction of the side wall portions 22C and 22D ( The thickness is set to less than the penetration depth of electromagnetic induction. The eddy current that can be generated in the segment 2 by the induction heating coil H is a current that is induced by the magnetic field generated by the induction heating coil H and flows inside the segment 2. The penetration depth δ of the magnetic field created by the induction heating coil H is the material constituting the segment 2 (all of the inner peripheral wall portion 22A, all of the side wall portions 22C, 22D, and the outer peripheral wall portion 22B, excluding the open portion 24). Resistivity ρ of the material constituting the portion), the frequency of the current applied to the induction heating coil H (frequency of the induction heating coil H) f, and the material constituting the segment 2 (all of the inner peripheral wall portion 22A, both side wall portions) In relation to the magnetic permeability μ of all of 22C and 22D and the material of the outer peripheral wall portion 22B excluding the open portion 24), based on the relationship, What is necessary is just to set the radial thickness of 22 A of inner peripheral wall parts and 22 A of outer peripheral wall parts, and the thickness of the circumferential direction of both side wall parts 22C and 22D to an appropriate value.
δ = √ {2 · ρ / (ω · μ)} where ω = 2πf Equation 1

  As shown in FIG. 1, the gantry K has a cylindrical columnar portion K1 whose axial center coincides with the axial center of the crucible 1, and a state in which the pedestal K protrudes radially outward from the upper end of the columnar portion K1. And a collar portion K2 provided on the head. The crucible 1 is fixed to the gantry K using bolts B and nuts N in a state where the crucible 1 (attachment portion 23 of the segment 2) is placed on the upper surface of the flange portion K2. In this fixed state, spaces that communicate with the water cooling passage C1 of the segment 2 are formed between the inner space of the columnar portion K1 and the flange portion K2 and the bottom portion 21 of the segment 2, and the space of the segment 2 is formed in these spaces. A horizontal posture pipe C8 and a standing posture pipe C9 which are continuous with and communicated with each other at the lower end of the inner pipe C3 disposed in the portion C2 are disposed.

  The induction heating coil H is arranged in a spiral shape so as to surround the body portion 10 at a position away from the outer peripheral surface 22b of the body portion 10, and is connected to a power supply device (not shown) that can output AC power of an arbitrary frequency. ing. In an energized state in which AC power is supplied from the power supply device to the induction heating coil H, an alternating magnetic field is generated around the coil H, and this alternating magnetic field is infiltrated into the melted metal W accommodated in the crucible 1 to perform induction heating. To do.

  Examples of the metal W to be melted include metals having a large thermal conductivity such as gold, silver, aluminum, and alloys of these metals in addition to pure copper and copper alloys, such as iron, cobalt, titanium, nickel, and zirconium. , Hafnium, chromium, niobium, tantalum, molybdenum, uranium, rare earth metals, thorium, and alloys thereof.

  According to such a cold crucible melting furnace X according to this embodiment, the molten metal W in a lump or powder form is charged into the crucible 1 and the cooling water is supplied to the water cooling passage C1 of each segment 2, By supplying AC power from the power supply device to the induction heating coil H, an alternating magnetic field is generated around the induction heating coil H, and the magnetic flux passes through the longitudinal slit 3 and passes inside the crucible 1, thereby It penetrates into the molten metal W, and the molten metal W can be induction heated. Thereby, as shown in FIG. 1, the melted metal W is melted from the surface side heated to the melting temperature to become the molten metal Wb and flows down toward the bottom wall of the crucible 1. Then, the molten metal Wb that has reached the bottom wall of the crucible 1 is cooled and solidified by the crucible 1 maintained in an appropriate cooling state by the cooling means C to form a skull Wa that has been cooled and solidified in a dish shape.

  Here, when the thickness of the skull Wa becomes greater than a predetermined value and the heating capability by induction heating exceeds the cooling capability of the crucible 1 by the cooling means C, the molten metal Wb stays on the skull Wa. When the amount of the molten metal Wb staying increases, the molten metal Wb is stirred while exhibiting a dome-shaped outer shape that rises from the peripheral part to the central part due to the interaction between the alternating magnetic field and the induced current and the action of gravity. Will be. Due to such an event, as shown in FIG. 1, the melted metal W includes a skull Wa formed in a deep dish shape along the bottom surface and the inner peripheral surface 22 a of the crucible 1, and the molten metal staying on the skull Wa. The molten metal Wb can be taken out of the crucible 1 by an appropriate method such as tilting the crucible 1. In order to form and maintain a large amount of molten metal Wb on the skull Wa, electric power is supplied to the induction heating coil H so that the molten metal Wb is heated with a heat amount larger than the amount of heat removed from the molten metal Wb of the crucible 1. Need to continue.

  By the way, in the case of the conventional cold crucible melting furnace X, about 30% of the input power is lost due to induction heating of the crucible 1. This is because when an induction heating coil H is energized with a high frequency current, an induction current that circulates in the water-cooled passage C1 in a plan view in each segment 2 (in FIGS. 6 and 7). The main cause is that an eddy current (current direction indicated by an arrow) is generated and a loss occurs. Then, the larger the loss of input power, the lower the melting power and the worse the power input ratio (melting efficiency) to the metal W to be melted in the crucible 1.

  On the other hand, in the cold crucible melting furnace X according to the present embodiment, as the peripheral wall portion 22 that constitutes the body portion 10 of the crucible 1 among the segments 2, the open portion 24 that communicates with the water cooling passage C1 from the outside of the crucible 1 is a peripheral wall portion. A portion 22 (outer peripheral wall portion 22B) is formed, and the open portion 24 is closed by a watertight material 25 having a higher electrical resistivity than the inner peripheral wall portion 22A. According to such a cold crucible melting furnace X according to this embodiment, the open portion 24 formed so as to communicate with the water cooling passage C1 from the outside of the crucible 1 is radially inward of the peripheral wall portion 22 from the water cooling passage C1. Since the water-tight material 25 having a higher electrical resistivity than the inner peripheral wall portion 22A that forms the region is closed, it is possible to prevent or suppress a situation in which an eddy current circulating around the water-cooled passage C1 flows in each segment 2. . As a result, the loss of input power due to induction heating of the crucible 1 can be greatly reduced, and the melting efficiency is improved.

  In particular, in the cold crucible melting furnace X according to the present embodiment, the radial thickness of the inner peripheral wall portion 22A and the outer peripheral wall portion 22B and the circumferential thickness of the side wall portions 22C and 22D are made by the induction heating coil H. Since the thickness is set to be less than the penetration depth of the magnetic field (electromagnetic induction penetration depth), the eddy current generated in the segment 2 can be reduced, and the loss of input power due to induction heating of the crucible 1 can be reduced. Further reduction and further increase in dissolution efficiency can be achieved.

  Further, according to the cold crucible melting furnace X according to the present embodiment, the open portion 24 is closed with the watertight material 25 having a higher electrical resistivity than the inner peripheral wall 22A, thereby cooling water or the like from the water cooling passage C1 to the open portion 24. It is possible to prevent the cooling medium from leaking, to ensure a good water cooling function, to prevent / suppress the situation in which the peripheral wall portion 22 of the segment 2 is abnormally heated, and the cooling means C for the crucible 1 The good cooling performance can be exhibited, and thermal deformation prevention of the crucible 1 can be realized at the same time.

  In addition, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the open part 24 communicating with the water cooling passage C1 from the outside of the crucible 1 is formed only in the outer peripheral wall part 22B of the peripheral wall part 22, and this open part 24 is more electrically resistant than the inner peripheral wall part 22A. Although the aspect which was obstruct | occluded with the watertight material 25 with a high rate was illustrated, as shown to Fig.5 (a), the open part 24 connected to the water cooling channel | path C1 from the exterior of the crucible 1 is made into outer peripheral wall part 22B of the peripheral wall part 22, It is also possible to adopt a configuration in which the opening portions 24 are formed on the side wall portions 22C and 22D, respectively, and the open portions 24 are closed by a watertight material 25 having a higher electrical resistivity than the inner peripheral wall portion 22A.

  Moreover, in this invention, as shown in FIG.5 (b), the open part 24 is formed only in both wall part 22C, 22D, and each open part 24 is a watertight material whose electrical resistivity is higher than inner peripheral wall part 22A. A configuration closed by 25 may be used. The planar shape of the water cooling passage may be a shape other than the circular shape shown in FIGS. 4 and 5A, for example, a rectangular shape shown in FIG. 5B.

  Furthermore, the other wall portions excluding the inner peripheral wall portion of the peripheral wall portion of the segment, that is, the entire portion corresponding to the outer peripheral wall portion and the both side wall portions are set as one continuous open portion, and this open portion is A configuration closed by a watertight material having an electric resistivity higher than that of the peripheral wall portion can also be adopted. In this case, a water cooling passage is secured in a region surrounded by the inner peripheral wall portion and the watertight material.

  In the present invention, the shape and number of the open portions can be appropriately selected and changed, and the open portions can be appropriately closed by applying a watertight material according to the shape of the open portions. For example, two or more open portions are formed in at least one wall portion of the outer peripheral wall portion or both side wall portions (for example, open portions are formed at a plurality of positions spaced apart in the circumferential direction on the outer peripheral wall portion), and each open portion You may employ | adopt the structure which obstruct | occludes with a watertight material.

  Further, the frequency of the high-frequency power may be set so that induction heating is performed with a penetration depth thinner than the radial thickness of the inner peripheral wall portion and the outer peripheral wall portion and the circumferential thickness of each side wall portion. .

  It is also possible to apply a segment that does not have a bottom part that constitutes the bottom wall of the crucible. In this case, a bottom plate that is set to a diameter slightly smaller than the inner diameter of the crucible body part is used. What is necessary is just to arrange | position so that it can move up and down with respect to a trunk | drum.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Crucible 10 ... Body part 2 ... Segment 22A ... Inner peripheral wall part 22B ... Outer peripheral wall part 22C, 22D ... Side wall part 24 ... Opening part 25 ... Watertight material 3 ... Vertical slit 4 ... Insulating material C1 ... Water cooling passage H ... Induction heating Coil X ... Cold Crucible Melting Furnace

Claims (2)

A cold crucible melting furnace capable of inductively heating and melting a metal to be melted in the crucible by an induction heating coil arranged on the outer periphery of the body part of the crucible;
The body portion includes a vertical slit in which a plurality of segments formed in a tubular water-cooled passage extending in a height direction are radially extended along the radial direction of the body portion and closed with a predetermined insulating material. Are arranged in a line in the circumferential direction through
The segment includes an inner peripheral wall portion that forms a radially inner region from the water cooling passage, an outer peripheral wall portion that forms a radially outer region from the water cooling passage, the inner peripheral wall portion, and the outer peripheral wall. Two sidewall portions that form a region between the portions and face each other across the water cooling passage in the circumferential direction, and at least one wall portion of the outer circumferential wall portion or the two sidewall portions, A cold crucible melting furnace characterized in that an open portion communicating with the water cooling passage from the outside of the segment is formed, and the open portion is closed with a watertight material having a higher electrical resistivity than the inner peripheral wall portion. The thickness in the radial direction or the circumferential direction of the inner peripheral wall portion, the outer peripheral wall portion, and the side wall portion is set to a thickness less than a penetration depth of magnetic flux generated in the induction heating coil. The cold crucible melting furnace described in 1.

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