CN112393588A

CN112393588A - Induction smelting cold crucible with full suspension and strong stirring capacity

Info

Publication number: CN112393588A
Application number: CN202011152944.2A
Authority: CN
Inventors: 李佳; 李庚�
Original assignee: Baoji Huayu Dingzun Material Technology Co Ltd
Current assignee: Baoji Huayu Dingzun Material Technology Co Ltd
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2021-02-23

Abstract

The invention discloses a cold crucible with full suspension and strong stirring capacity for induction melting, which comprises a crucible, a main induction coil, a bottom induction coil, a main magnetic field disturbance cylinder and a bottom magnetic field disturbance cylinder, wherein the main induction coil is arranged on the outer side surface of the crucible, and a radial suspension force is applied to a molten pool through the main induction coil to separate the molten pool from the side surface of the crucible. The bottom induction coil is arranged at the bottom of the crucible, and the bottom induction coil or the spiral conical induction coil exerts upward suspension force on the bottom of the molten pool through the bottom induction coil, so that the bottom of the molten pool is also separated from the inner bottom surface of the crucible, thereby realizing full suspension of the molten pool, improving the smelting temperature, improving the uniformity of alloy components and preventing the formation of solidified shells. In addition, a spiral small conical or cylindrical induction coil is arranged at the bottom of the crucible, acting force is applied to the cast molten metal, the molten metal is always in the middle position, and casting is accurate.

Description

Induction smelting cold crucible with full suspension and strong stirring capacity

Technical Field

The invention relates to a cold crucible for induction melting with full suspension and strong stirring capacity, in particular to a cold crucible for improving the suspension effect by using an electromagnetic field in the suspension melting process, and belongs to the technical field of melting.

Background

Cold crucible vacuum induction melting (vacuum electromagnetic suspension melting) is one of the most advanced melting technologies, similar to vacuum intermediate frequency induction melting, and is a melting process completed by heating metal with an electromagnetic field in a vacuum or inert gas environment, and belongs to a melting technology without gas pollution. Compared with vacuum medium-frequency induction melting, cold crucible vacuum induction melting utilizes electromagnetic suspension force to enable a metal melting pool to be in a suspension state in a crucible, and pollution of crucible materials to liquid metal is avoided. Therefore, the suspension smelting technique is particularly suitable for smelting active metals, refractory metals and alloys thereof. This melting technique uses a split cold crucible and is therefore referred to as cold crucible technique. The purpose of the crucible sectioning is to enable an electromagnetic field to enter the interior of the metal crucible.

In the cold crucible vacuum induction melting technology, the suspension force generated by an electromagnetic field points to the axis of a crucible, and under the action of the suspension force, the surface around a molten pool is subjected to pressure, so that the molten pool is bound into a column shape and is not contacted with the inner surface of the side wall of the crucible. The molten pool is subjected to gravity in addition to the levitation force, and the pressure increases toward the lower portion of the molten pool, so that the molten pool takes on a shape that is fine at the top and coarse at the bottom. At the bottom of the molten pool, the liquid can not be completely separated from the bottom surface of the crucible, and the liquid is subjected to the strong cooling action of the bottom surface of the crucible, so that the temperature at the bottom of the molten pool is low, and a skull is often formed, as shown in figure 1. When the inner bottom surface of the crucible 01 is a curved surface or a sloped surface, the bottom of the molten pool 03 can be partially separated from the inner bottom surface of the crucible 01 as shown in fig. 2. However, in the center region of the inner bottom surface, the bottom of the molten pool 03 still cannot be completely separated from the inner bottom surface of the crucible 1.

The phenomenon that the temperature at the bottom of the molten pool is lower and the solidified shell is formed can bring the following adverse effects to the smelting effect:

1. the heat of the molten pool is mostly taken away by the cooling water of the crucible, so that the energy consumption of the smelting is increased, and the smelting time is prolonged; 2. the yield is reduced; 3. in the melting of the alloy, the occurrence of skull makes it difficult to achieve uniformity of the alloy composition and causes deviation of the product composition from the design composition, which is the most serious influence caused by the occurrence of skull, resulting in a reduction in yield.

The prior patent CN101948958 discloses a method and equipment for refining nonferrous metal by vacuum electromagnetic suspension distillation, wherein a suspension coil and a stabilizing coil are arranged on the outer side of a crucible, so that the materials are heated and stirred in a suspension state. However, the arrangement of the induction coil cannot provide an upward suspension force for the material, and the bottom of the material is in contact with the bottom of the crucible, so that the temperature of the bottom of the material is reduced, a skull is easily formed, and the uniformity of the alloy is seriously affected.

Current patent ZL201020696611.1 provides a cold crucible of induction melting technique with high suspension ability, and the bottom inner wall and the horizontal direction of its crucible body are equipped with even or inhomogeneous inclination, and the bottom of the crucible body is split completely, and the gap between the split runs through crucible body bottom thickness to this improves bottom zone's in the crucible heat effect and suspension power, prevents to contact and the low formation skull of temperature at the bottom of molten bath bottom and the crucible. However, the electromagnetic fields generated by the induction coils positioned on the side wall and the bottom of the crucible interfere with each other, so that the electromagnetic field inside the crucible body is not uniform, the heating and stirring of the furnace charge are not uniform, and the uniformity of the alloy is affected. In addition, when the molten metal flows out from the lower pouring opening, the acting force of the induction coil is lost, the molten metal cannot uniformly flow out along a certain track, great randomness is achieved, the molten metal cannot accurately enter the inlet of the casting mold, and waste is caused.

In addition, although the conventional suspension smelting technique has electromagnetic stirring, the electromagnetic stirring capability is weak, and the bath composition cannot be sufficiently homogenized. Therefore, the induction melting cold crucible which can be fully suspended, uniformly heated and stirred, is high-temperature resistant and is anti-pollution has very important significance.

Disclosure of Invention

Aiming at the prior art, the invention aims to provide the cold crucible for the full-suspension induction melting, which enables an alloy melting pool to realize full suspension, uniform heating, uniform stirring and accurate casting and has a simple overall structure.

The purpose of the invention is realized by the following technical scheme.

The utility model provides a cold crucible of induction melting with full suspension, strong stirring ability, includes induction coil, vacuum furnace body, vacuum unit, inductive power supply, and cold crucible is located the vacuum furnace body, and the oscillating current of inductive power supply output is carried in the induction coil, induction coil includes main induction coil and bottom induction coil and inside is provided with coil cooling water route, and cold crucible includes crucible, main induction coil, bottom induction coil, a main magnetic field disturbance section of thick bamboo, end magnetic field disturbance section of thick bamboo, the crucible includes the lamella of being separated into by the slit, the inside lamella cooling water route that is provided with of lamella, the slit pierces through the bottom of crucible, the interior bottom surface of crucible is conical surface, curved surface or plane, the lateral surface of crucible is provided with annular one, induction coil includes main induction coil and end induction coil, main induction coil is spiral pipeline and cover and establishes the main magnetic field disturbance section of thick bamboo outside, the bottom induction coil is a planar spiral pipeline and is arranged at the lower end of a bottom magnetic field disturbance barrel, the main magnetic field disturbance barrel comprises a first driving ring, a first shielding strip is arranged at the lower end of the first driving ring, a first convex ring is arranged on the inner side surface of the first driving ring, the first convex ring is rotatably arranged in a first annular groove to sleeve the main magnetic field disturbance barrel outside a crucible, a gear is arranged on the outer side surface of the first driving ring, and a driving device drives the gear to rotate so as to drive the main magnetic field disturbance barrel to rotate outside the crucible; a bottom magnetic field disturbance section of thick bamboo includes drive ring two, a bottom magnetic field disturbance section of thick bamboo is provided with to center and plane radiation and hides blend stop two, two medial surfaces of drive ring are provided with bulge loop two, the lateral surface of crucible is provided with annular two, bulge loop two rotate set up in annular two with will bottom magnetic field disturbance section of thick bamboo cover is established in the crucible outside, the lateral surface of drive ring one is provided with the gear, and drive arrangement drives gear revolve with the drive bottom magnetic field disturbance section of thick bamboo rotates in the outside of crucible.

Furthermore, the bottom of the crucible comprises an inclined surface, the inclined surface is a conical surface, and the slit completely penetrates through the inclined surface.

Furthermore, the shielding strip II is arranged along the inclined plane at the bottom of the crucible and used for shielding the slit on the inclined plane, and the bottom induction coil comprises a large conical induction coil sleeved outside the inclined plane.

Furthermore, the bottom end of the inclined plane is provided with a cylindrical surface, the slit completely penetrates through the inclined plane and the cylindrical surface at the bottom of the crucible, and the bottom induction coil further comprises a spiral small conical induction coil/small cylindrical induction coil sleeved outside the cylindrical surface.

Further, the large conical induction coil and the small conical induction coil/the small cylindrical induction coil are arranged in series or are arranged independently.

Furthermore, the number and the positions of the shielding strips I and the shielding strips II are in one-to-one correspondence with the slits.

Furthermore, the number of the shielding strips I and the number of the shielding strips II are larger than or smaller than that of the slits, so that the shielding strips I and the shielding strips II are arranged with the slits in a staggered mode.

Furthermore, the bottom induction coil and the main induction coil adopt the same induction power supply.

Further, the frequency of the induction power supply adopted by the bottom induction coil is less than or equal to 0.1 time of the frequency of the induction power supply adopted by the main induction coil.

Furthermore, the bottom induction coil and the main induction coil are made of red copper.

The invention has the advantages that:

1. the cold crucible comprises a crucible, a main induction coil, a bottom induction coil, a main magnetic field disturbance cylinder and a bottom magnetic field disturbance cylinder, wherein the main induction coil is arranged on the outer side surface of the crucible, a radial suspension force is applied to a molten pool through the main induction coil to enable the molten pool to be separated from the side surface of the crucible, meanwhile, for the crucible with a plane inner bottom surface, a plane spiral bottom induction coil is arranged at the bottom of the crucible, an upward suspension force is applied to the bottom of the molten pool through the bottom induction coil to enable the bottom of the molten pool to be separated from the inner bottom surface of the crucible, so that the full suspension of the molten pool is realized, firstly, the bottom of the molten pool is prevented from contacting with the inner bottom surface of the crucible to form a skull, the uniformity is; secondly, prevent the pollution of crucible to the molten bath, in addition, can also prevent that cold crucible from taking away the heat to reduce the energy consumption.

2. For the crucible with the inner bottom surface being a conical surface or a curved surface, a spiral large conical induction coil is arranged outside the conical surface at the bottom of the crucible, upward suspension force is applied to the bottom of a molten pool through the upward component force of the large conical induction coil, so that the bottom of the molten pool is also separated from the inner bottom surface of the crucible, thereby realizing the full suspension of the molten pool,

3. a main magnetic field disturbance cylinder is arranged on the outer side surface of a crucible, and a slit on the crucible is intermittently shielded by rotating the main magnetic field disturbance cylinder, so that the magnetic flux passing through the slit is intermittently changed, the suspension force or acting force exerted on a molten pool is intermittently changed, and the molten pool is stirred.

4. The bottom of the crucible is provided with a bottom magnetic field disturbance cylinder, and the slit at the bottom of the crucible is intermittently shielded by rotating the bottom magnetic field disturbance cylinder, so that the magnetic flux passing through the slit at the bottom is intermittently changed, the suspension force or the acting force exerted on the bottom of the molten pool is intermittently changed, and the stirring of the molten pool is enhanced.

5. The bottom of the crucible is provided with a cylindrical surface, a spiral small conical induction coil is arranged outside the cylindrical surface, and radial component force and upward component force are applied to a molten pool through the small conical induction coil, so that on one hand, upward suspension force to the molten pool is increased during smelting, and on the other hand, radial force is applied to a metal flow during casting, so that the metal flow is always in the central position, and the metal liquid is prevented from being scattered.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic diagram of electromagnetic levitation force of an existing flat-bottom cold crucible induction coil on a molten pool.

FIG. 2 is a schematic diagram of the electromagnetic levitation force of the existing cone bottom cold crucible induction coil to the molten pool.

FIG. 3 is a structural view of the cold crucible vacuum induction melting apparatus.

FIG. 4 is a perspective view of a flat bottom cold crucible.

FIG. 5 is an exploded view of a flat bottom cold crucible.

FIG. 6 is a schematic view of a flat bottom crucible.

FIG. 7 is a schematic view of a main magnetic field perturbing cylinder.

FIG. 8 is a schematic view of a flat-bottomed magnetic field perturbing cylinder.

FIG. 9 is a perspective view of a cold crucible with a conical bottom.

FIG. 10 is an exploded view of a cold crucible with a conical bottom.

FIG. 11 is a schematic view of a tapered bottom crucible.

FIG. 12 is a schematic view of a cone bottom magnetic field perturbation cylinder.

Fig. 13 is a schematic view of a cone bottom induction coil.

FIG. 14 is a sectional view of the crucible wall.

FIG. 15 is a diagram of the electromagnetic levitation force of a flat-bottom induction coil on a molten pool.

FIG. 16 is a schematic diagram of electromagnetic levitation force of the cone bottom induction coil on the molten pool.

FIG. 17 is a first schematic view of the arrangement of a crucible water jacket.

FIG. 18 is a second schematic view of the arrangement of the crucible water jacket.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

As shown in fig. 3, the cold crucible vacuum induction melting apparatus includes a vacuum furnace body 6, a vacuum unit 7, an induction power supply 8, and the like. The split cold crucible is arranged in a vacuum furnace body 6, the oscillating current output by a high-frequency induction power supply 8 is transmitted to an induction coil surrounding the crucible 1, and the generated electromagnetic field heats the metal material in the crucible 1, as shown in figure 2. The purpose of the cold crucible sectioning is to enable an electromagnetic field to penetrate the wall of the metal cold crucible into the interior of the crucible 1. In order to protect the crucible 1 from burning at high temperature, a petal cooling water path 14 is designed in each petal of the crucible 1. In order to achieve a good suspension effect, the inductive power supply 8 should have a relatively high oscillation frequency, for example, 5 to 50 kHz.

According to the first embodiment of the present invention, as shown in fig. 4-8, a cold crucible for induction melting with full suspension and strong stirring capability is provided, which comprises a crucible 1, a main induction coil 2, a bottom induction coil 9, a main magnetic field disturbance cylinder 17 and a bottom magnetic field disturbance cylinder 18. Crucible 1 is the water-cooling copper crucible of flat bottom, and it includes lamella 101 separated into by slit 102, lamella 101 is inside to be provided with lamella cooling water route 14, slit 102 pierces through the bottom of crucible 1. And the upper end and the lower end of the outer side surface of the crucible 1 are respectively provided with a first annular groove 103 and a second annular groove 104. The main induction coil 2 is spiral and is sleeved outside the main magnetic field disturbance cylinder 17, and the bottom induction coil 9 is arranged at the lower end of the bottom magnetic field disturbance cylinder 18. The main induction coil 2 and the bottom induction coil 9 are of pipeline structures, and coil cooling water paths are arranged inside the main induction coil and the bottom induction coil.

In the case where the profile of the crucible bottom is planar, the bottom induction coil is preferably a planar spiral, like a disk as shown in FIG. 5. The main induction coil and the bottom induction coil are both made of copper tubes, and the copper tubes of the planar spiral bottom induction coil are spirally wound from inside to outside to form a mosquito-repellent incense shape. The copper pipes of the main induction coil and the bottom induction coil are internally filled with cooling water, so that the copper pipes are prevented from being burnt by high-frequency current.

At the bottom of the crucible 1, magnetic lines of force generated by the planar spiral bottom induction coil 9 at the bottom end of the crucible 1 are radiated outwards from the center, at the position of the surface of the molten pool 3, the magnetic lines of force are vertical to the axis of the crucible 1, the electromagnetic field generates eddy currents on the surface of the molten pool 3 in the direction surrounding the axis of the crucible, and the force generated by the magnetic lines of force and the eddy currents is vertical to the eddy currents, so the magnetic lines of force and the eddy currents are vertical upwards, as shown in fig. 15.

The power supply supplying the oscillating current to the bottom induction coil 9 may be the same induction power supply 8 as the power supply supplying the current to the main induction coil 2 heating the metal material around the crucible 1. At this time, the electromagnetic fields generated by the two induction coils have the same frequency and phase, and the two electromagnetic fields do not interfere with each other. The bottom induction coil and the main induction coil can be combined in parallel or in series. By changing the ratio of the number of turns of the bottom induction coil to the number of turns of the main induction coil, the energy ratio of the electromagnetic field obtained by the bottom induction coil can be changed. In the case of parallel combination, the currents of the two induction coils can be adjusted separately in order to obtain the best bottom suspension effect.

The power supply (secondary power supply) for supplying current to the bottom induction coil may be a power supply different from the power supply (primary power supply) for supplying current to the primary induction coil. However, the frequency of the secondary power supply output current must differ sufficiently from the frequency of the primary power supply to avoid interference between the primary and secondary power supplies. The frequency of the current of the main power supply is selected in accordance with the smelting operation, so that the frequency of the secondary power supply should be very different from the frequency of the main power supply, preferably more than 10 times lower than the frequency of the main power supply. The frequency of the commercial alternating current is 50Hz, and the commercial alternating current does not generate obvious interference with the frequency of the main power supply higher than 5 kHz. Therefore, the auxiliary power supply can adopt a common industrial alternating current power supply, and the cost for adding the auxiliary power supply can be greatly reduced.

Under the condition that the bottom induction coil is not arranged, in the crucible with the horizontal inner bottom surface, the main induction coil generates the suspension force with the direction facing to the axis of the crucible, only the thrust force for moving the edge of the bottom surface of the molten pool 3 to the center is generated, and the thrust force for making the bottom surface of the molten pool upwards separate from the bottom of the crucible is completely avoided, as shown in figure 1. In order to further enhance the floating effect of the bottom of the molten pool 3, the inner bottom surface of the crucible 1 is preferably curved or inclined. When the inner bottom surface of the crucible 1 is a curved surface or an inclined surface, even if the bottom induction coil 9 is not provided, the magnetic lines of force and the eddy current of the main induction coil 2 generate only a levitation force in a direction perpendicular to the axis of the crucible 1 in the crucible 1, and the bottom of the molten pool 3 can be partially separated from the inner bottom surface of the crucible 1 as shown in fig. 2. However, in the center region of the inner bottom surface, the bottom of the molten pool 3 still cannot be completely separated from the inner bottom surface of the crucible 1. In this case, the bottom induction coil 9 is added to obtain the effect of completely suspending the bottom of the molten bath 3, as shown in fig. 15.

Further, while the melting is performed, the alloy liquid in the molten pool 3 cannot be sufficiently stirred, and the texture of the metal or the alloy cannot be sufficiently stirred uniformly. In contrast, the invention is also provided with a main magnetic field disturbance cylinder 17, and the main magnetic field disturbance cylinder 17 is rotatably sleeved on the outer side of the crucible 1. Since the suspension force of the molten pool 3 comes from the electromagnetic field in the crucible 1, the electromagnetic field in the crucible 1 comes from the electromagnetic field generated by the induction coil and enters the crucible 1 through the slit 102 arranged on the side wall of the crucible 1 and parallel to the axis of the crucible 1 to form. The electromagnetic field transmitted through the slit 102 is influenced by the width of the slit, and the wider the slit, the larger the magnetic flux, the stronger the electromagnetic field, and the larger the levitation force acting on the molten pool 3. The slit 102 is shielded discontinuously by rotating the main magnetic field disturbance cylinder 17 on the outer side surface of the crucible 1, the electromagnetic field strength in each direction is changed ceaselessly, the suspension force in each direction changes intermittently, the molten metal in the molten pool 3 vibrates or rocks to a certain degree, and then the alloy or the molten metal in the molten pool 3 is stirred, so that the components of the molten metal or the alloy liquid are more uniform.

Further, the main magnetic field disturbance cylinder 17 is sleeved outside the crucible 1 and comprises a driving ring 1701, and a shielding strip 1703 is arranged at the lower end of the driving ring 1701. Preferably, the first shielding bars 1703 correspond to the slits 102 one by one, so that the molten pool 3 is regularly stirred. The number of the first shielding strips 1703 can also be larger or smaller than the number of the slits 102, so that the first shielding strips 1703 and the slits 102 are arranged in a staggered mode, the stirring strength is further enhanced, and the molten metal is more uniform.

Further, a first convex ring 1702 is arranged on the inner side surface of the driving ring 1701 of the primary magnetic field disturbance cylinder 17, a first annular groove 103 is arranged on the outer side surface of the crucible 1, and the first convex ring 1702 is arranged in the first annular groove 103 and is in sliding fit with the first annular groove 103. The main magnetic field disturbance cylinder 17 is arranged on the outer side surface of the crucible 1 through the convex ring I1702 and the annular ring I103. The outer side surface of the first driving ring 1701 is provided with a gear and other driving structures, the driving device drives the gear and other structures to drive the main magnetic field disturbance cylinder 17 to rotate outside the crucible 1, the first shielding strip 1703 is used for intermittently shielding the slit 102, the magnetic flux passing through the slit 102 is changed, and the suspension force acting on the molten pool 3 is intermittently changed to realize stirring of the molten pool 3.

In order to further enhance the disturbance of the electromagnetic field and make the molten pool 3 more uniform, the invention is also provided with a bottom magnetic field disturbance cylinder 18, the outer bottom surface of the crucible 1 is a flat bottom, and the bottom magnetic field disturbance cylinder 18 is a flat bottom magnetic field disturbance cylinder. The bottom magnetic field disturbance cylinder 18 comprises a second driving ring 1801, and a second shielding strip 1803 is radially arranged on the center and the plane of the bottom magnetic field disturbance cylinder 18. Preferably, the second shielding strips 1803 correspond to the slits 102 one by one, so that the bottom position of the molten pool 3 is regularly stirred. The number of the second shielding strips 1803 can also be larger or smaller than the number of the slits 102, so that the second shielding strips 1803 and the slits 102 are arranged in a staggered manner, the stirring strength is further enhanced, and the molten metal is more uniform.

Further, a second protruding ring 1802 is arranged on the inner side surface of the second driving ring 1801 of the bottom magnetic field disturbance cylinder 18, a second annular groove 104 is arranged on the outer side surface of the crucible 1, and the second protruding ring 1802 is arranged in the second annular groove 104 and is in sliding fit with the second annular groove 104. The bottom magnetic field disturbance cylinder 18 is mounted on the outer side surface of the crucible 1 through the convex ring II 1802 and the annular groove II 104. And the outer side surface of the second driving ring 1801 is provided with a driving structure such as a gear, and the driving device drives the gear to drive the bottom magnetic field disturbance cylinder 18 to rotate outside the crucible 1, so as to further enhance the stirring effect on the molten pool 3.

Further, the drive ring one 1701, the drive ring two 1801, the gear and other parts are made of non-metallic materials, preferably high temperature resistant non-metallic materials with certain strength, such as zirconia ceramics and the like. The reason is that the drive ring one 1701, the drive ring two 1801 and the gear made of metal form eddy currents in the electromagnetic field, which causes energy loss and even self-heating to burn out.

Further, the first shielding bar 1703 and the second shielding bar 1803 are made of high temperature resistant metal which is sensitive to the electromagnetic field, such as tungsten, molybdenum, niobium, and other refractory metals.

According to the second embodiment of the present invention, as shown in FIGS. 9 to 13, it is different from the first embodiment in that the bottom profile of the crucible 1 in the second embodiment includes a slope 105 including a tapered surface or a curved surface. The slit 102 penetrates completely through the bevel 105 of the bottom of the crucible 1. The bottom induction coil 9 is a conical or curved spiral shape adapted to the inclined surface 105. The bottom magnetic field disturbance cylinder 18 comprises a second driving ring 1801 and a second shielding strip 1803 at the bottom end of the second driving ring, and the second shielding strip 1803 is arranged along the inclined surface 105 at the bottom of the crucible 1 and used for shielding the slit at the bottom of the crucible 1. The bottom magnetic field disturbance cylinder 18 and the crucible 1 are installed in a matching way through a convex ring II 1802 in the driving ring II 1801 and a ring groove II 104 arranged on the outer side surface of the crucible 1.

Further, a cylindrical surface 106 is provided at the bottom end of the inclined surface 105, and the slit 102 penetrates completely through the inclined surface 105 and the cylindrical surface 106 at the bottom of the crucible 1. The cylindrical surface 106 is used for guiding the casting molten metal, so that the molten metal is prevented from flowing randomly to cause accidental sprinkling, and the waste of materials is increased. Meanwhile, the bottom induction coil 9 of the present embodiment includes a spiral large conical induction coil 901 that is externally fitted to the inclined surface 105 of the bottom of the crucible 1 and a spiral small conical induction coil 902 that is externally fitted to the cylindrical surface 105, and the large conical induction coil 901 and the small conical induction coil 902 apply an upward levitation force to the bottom of the molten pool 3, thereby completely separating the molten pool 3 from the inner bottom surface of the crucible. The large conical induction coil 901 and the small conical induction coil 902 are arranged in series, or may be separately arranged. And the small conical induction coil 902 is matched with the cylindrical surface 105, so that when casting, the small conical induction coil 902 generates component force pointing to the center of the cylindrical surface to the molten metal passing through the cylindrical surface 106, on one hand, the molten metal is prevented from contacting the cylindrical surface 106 when casting, on the other hand, the molten metal can flow out linearly and directly enter the inlet of the casting mold, and the molten metal is prevented from flowing and spilling randomly. Preferably, the small tapered induction coil 902 has a larger diameter at the upper end than at the lower end, and the component force on the plane of the small tapered induction coil is gradually increased, so that the molten metal enters the casting mold in a trickle manner. In addition, the spiral small conical induction coil 902 can be replaced by a spiral small cylindrical induction coil, and under the condition, the small cylindrical induction coil applies radial acting force to the flowing molten metal, so that accurate casting is realized.

In the case where the outer shape of the crucible bottom is a bevel or a curved surface, the bottom induction coil is preferably designed such that a tapered bevel having a shape matching the outer shape of the crucible bottom should be substantially parallel to the inner surface of the crucible bottom, as shown in fig. 9. The bottom induction coil is made of a copper tube, and the conical induction coil is spirally wound from top to bottom and is funnel-shaped. The main function of the induction coil is to convert the oscillating current introduced by the induction power supply into an electromagnetic field bottom. The copper pipe of the induction coil is internally filled with cooling water, so that the copper pipe is prevented from being burnt by high-frequency current.

The direction of the magnetic field lines generated by the conical inductor at the bottom of the crucible is inclined, and the interaction with the eddy current is perpendicular to the conical surface, so that it has a vertical upward component and a horizontal center component, as shown in fig. 16.

In addition, in order to improve the high temperature resistance of the whole crucible and reduce the pollution to a molten pool, the crucible 1 of the invention sequentially comprises a backing layer 1011, a coarse ceramic layer 1012 and an inert layer 1013 from outside to inside, wherein the backing layer 1011 is made of a composition of a refractory material and a colloid, and the high temperature resistance and the wear resistance of the whole crucible are improved. The coarse ceramic layer 1012 is made of coarse ceramic and is used for increasing the overall structural strength of the crucible. The inert layer 1013 is made of a material inert to the molten metal, and prevents the molten metal from being contaminated when the molten metal contacts the inner wall of the crucible.

In the case of using a bottom induction coil, the design of the water path of the crucible needs to be changed as necessary: in the case of using a bottom induction coil, the water jacket 15 may be provided above the crucible 1, as shown in fig. 18. If the water jacket 15 is disposed below the crucible 1, the electromagnetic field generated by the bottom induction coil cannot enter the crucible from below the crucible. In the existing cold crucible, the cooling water in each crucible flap is firstly collected into the water jacket below the crucible through dozens of small copper pipes and then is guided to the circulating water system from the main water path, as shown in fig. 17.

In the specific experimental process, in the first experiment, the existing water-cooled copper crucible is adopted, the power of the induction power supply 8 is 80kW, and the frequency is 20 kHz. The inner diameter of the split water-cooled copper crucible arranged in the vacuum furnace body 6 is 80mm, the total height is 140mm, the lower section of the split water-cooled copper crucible is 40mm in a conical shape, and the bottom surface in the crucible is an inclined surface. The oscillating current output by the ultrasonic power supply is transmitted to a cylindrical induction coil surrounding the crucible, the induction coil has the inner diameter of 110mm and the height of 150mm, and the induction coil has 10 turns, and the electromagnetic field generated by the induction coil heats the metal titanium in the crucible and has the weight of 1 kg.

After the vacuum furnace body 6 is vacuumized and filled with argon, the induction power supply 8 is started to supply power to the induction coil, and titanium is filled into the crucible 1. The titanium was almost completely melted by heating at 100A for 3 minutes. And after the heating is continued for 1 minute, injecting the titanium liquid into the die in a tilting casting mode. After cooling, the crucible was taken out, and it was found that a skull having a thickness of 5mm remained in the crucible.

Experiment two, with the cold crucible provided by the invention, the furnace body, the power supply and the crucible used are the same as those in embodiment 1, preferably, but the induction coil consists of two induction coils connected in series, including a main induction coil surrounding the upper cylindrical section of the crucible 1, the inner diameter is 110mm, the height is 100mm, and 8 turns; the bottom induction coil surrounding the conical section at the lower part of the crucible has 4 turns, the height is 60mm, the inner diameter of the uppermost turn is 110mm, and the inner diameter of the lowermost turn is 40 mm. 1kg of metallic titanium was added to the crucible.

After the furnace body is vacuumized and filled with argon, an induction power supply is started to supply power to the induction coil, and the titanium is completely melted after the furnace body is heated for 2.5 minutes under the current of 100A. And after the heating is continued for 1 minute, injecting the titanium liquid into the die in a tilting casting mode. After cooling, the crucible was removed and found to have no skull on the bottom of the crucible and a 0.5mm thick skull on the titanium melt channel in the crucible wall.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. The utility model provides a cold crucible of induction melting with full suspension, strong stirring ability, includes induction coil, vacuum furnace body (6), vacuum unit (7), inductive power source (8), and cold crucible is located vacuum furnace body (6), and the oscillating current of inductive power source (8) output is carried in induction coil, induction coil includes main induction coil (2) and bottom induction coil (9) and inside is provided with coil cooling water route, its characterized in that: the cold crucible comprises a crucible (1), a main induction coil (2), a bottom induction coil (9), a main magnetic field disturbance cylinder (17) and a bottom magnetic field disturbance cylinder (18), wherein the crucible (1) comprises petals (101) separated by slits (102), a petal cooling water channel (14) is arranged inside the petals (101), the slits (102) penetrate through the bottom of the crucible (1), the inner bottom surface of the crucible (1) is a conical surface, a curved surface or a plane, a first annular groove (103) is arranged on the outer side surface of the crucible (1), the induction coil comprises a main induction coil (2) and a bottom induction coil (9), the main induction coil (2) is a spiral pipeline and is sleeved outside the main magnetic field disturbance cylinder (17), the bottom induction coil (9) is a spiral pipeline and is arranged at the lower end of the bottom magnetic field disturbance cylinder (18), the disturbance cylinder (17) comprises a first driving ring (1701), a first shielding strip (1703) is arranged at the lower end of the first driving ring (1701), a first convex ring (1702) is arranged on the inner side surface of the first driving ring (1701), the first convex ring (1702) is rotatably arranged in the first annular groove (103) to enable the main magnetic field disturbance barrel (17) to be sleeved outside the crucible (1), a gear is arranged on the outer side surface of the first driving ring (1701), and a driving device drives the gear to rotate to drive the main magnetic field disturbance barrel (17) to rotate outside the crucible (1); bottom magnetic field disturbance section of thick bamboo (18) are including drive ring two (1801), bottom magnetic field disturbance section of thick bamboo (18) are provided with to center and plane radiation and shelter from a strip two (1803), drive ring two (1801) medial surface is provided with bulge loop two (1802), the lateral surface of crucible (1) is provided with annular groove two 104, bulge loop two (1802) rotate set up in annular groove two 104 with will bottom magnetic field disturbance section of thick bamboo (18) cover is established in the crucible (1) outside, the lateral surface of drive ring one (1701) is provided with the gear, and drive arrangement drives gear revolve with the drive bottom magnetic field disturbance section of thick bamboo (17) rotate in the outside of crucible (1).

2. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the bottom shape of the crucible (1) comprises an inclined surface (105), the inclined surface (105) is a conical surface, and the slit (102) completely penetrates through the inclined surface (105).

3. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the shielding strip II (1803) is arranged along the inclined plane (105) at the bottom of the crucible (1) and used for shielding the slit (102) on the inclined plane (105), and the bottom induction coil (9) comprises a spiral large conical induction coil (901) sleeved on the inclined plane (105).

4. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the bottom end of the inclined plane (105) is provided with a cylindrical surface (106), the slit (102) completely penetrates through the inclined plane (105) and the cylindrical surface (106) at the bottom of the crucible (1) at the same time, and the bottom induction coil (9) further comprises a spiral small conical induction coil/small cylindrical induction coil (902) which is sleeved on the cylindrical surface (106).

5. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the large conical induction coil (901) and the small conical induction coil/small cylindrical induction coil (902) are arranged in series or are arranged independently.

6. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the number and the positions of the first shielding strips (1703) and the second shielding strips (1803) are arranged in one-to-one correspondence with the slits (102).

7. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the number of the shielding strips I (1703) and the number of the shielding strips II (1803) are larger than or smaller than the number of the slits (102), so that the shielding strips I (1703) and the shielding strips II (1803) and the slits (102) are arranged in a staggered mode.

8. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the bottom induction coil (9) and the main induction coil (2) adopt the same induction power supply (8).

9. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the frequency of an induction power supply adopted by the bottom induction coil (9) is less than or equal to 0.1 time of the frequency of an induction power supply adopted by the main induction coil (2).

10. The cold crucible for induction melting with full suspension and strong stirring capability as claimed in claim 1, wherein: the bottom induction coil (9) and the main induction coil (2) are made of red copper.