Induction heating vacuum melting and pouring all-in-one machine

Abstract

An induction heating vacuum melting and pouring all-in-one machine comprises an induction heating furnace body, the induction heating furnace body comprises a crucible, an induction heating hearth, an induction heating coil, a supporting body and a furnace shell which are sequentially arranged from inside to outside, and the induction heating furnace body further comprises two rotating shafts and a furnace mouth. The induction heating hearth and the crucible are coaxially arranged on the two opposite sides of the outer wall of the furnace shell, and the furnace nozzle sequentially penetrates through the furnace shell, the induction heating hearth and the crucible from outside to inside and is communicated with the middle of a cavity of the crucible; the vacuum refining and flue gas purification system comprises an exhaust pipe, a vacuum pump and a flue gas purifier which are connected in sequence, and a gas cylinder and a gas inlet pipe which are connected in sequence, the pouring system comprises a dumping platform, a gantry moving platform, a horizontal moving trolley and a steel rail. According to the vacuum smelting and pouring all-in-one machine, smelting and pouring are completed at a time, the intermediate link of a pouring ladle is omitted, energy consumption is reduced, production efficiency is improved, and a foundation is laid for intelligent production from smelting to pouring.

Description

Technical Field

[0001] The invention belongs to the technical field of induction heating, and in particular relates to an induction heating vacuum melting and pouring integrated machine. Background Art

[0002] Induction heating has the characteristics of fast heating speed, high thermal efficiency, and no pollution. It is widely used in daily life and industrial fields, such as the electromagnetic cookers used in daily life, and induction heating heat treatment, welding heating, forging heating, metal smelting, etc. in the industrial field. Although induction heating has higher thermal efficiency than resistance heating, the thermal efficiency is only around 50% to 75%, and there is still considerable room for improvement. Most of the induction heating melting furnaces in the existing technology heat in air, which easily causes high gas and impurity content in the molten metal, directly affecting the mechanical properties of the product and causing serious pollution to the environment. The vacuum melting furnaces in the existing technology use vacuum melting and vacuum pouring, which makes the vacuum melting furnace large in size and low in production efficiency, making it unsuitable for mass production. The induction heating melting furnaces in the existing technology can only perform a pouring action, that is, pouring the molten metal into a ladle and then pouring it into the casting mold. The production efficiency is low and impurities are easily introduced into the casting mold, affecting the quality of the casting. Summary of the Invention

[0003] The purpose of the present invention is to provide an induction heating vacuum melting and pouring all-in-one machine, that is, an all-in-one machine for vacuum melting and atmospheric pouring, which eliminates the intermediate link of pouring with a pouring ladle, thereby achieving the goals of improving dual efficiency (thermal efficiency and production efficiency), improving quality and efficiency, being green and environmentally friendly, and automatically controlling mechanical movement.

[0004] To achieve the above-mentioned object, the technical solution adopted by the present invention is: an induction heating vacuum melting and pouring integrated machine, comprising an induction heating furnace body, the induction heating furnace body comprising a crucible, an induction heating furnace chamber, an induction heating coil, a support body and a furnace shell arranged in sequence from the inside to the outside, the induction heating furnace body also comprising a rotating shaft and a furnace nozzle, the rotating shafts being provided with two and coaxially arranged on opposite sides of the outer wall of the furnace shell, the furnace nozzle passing through the furnace shell, the induction heating furnace chamber and the crucible in sequence from the outside to the inside, and communicating with the middle part of the crucible cavity; Also includes: A vacuum refining and flue gas purification system, comprising an exhaust pipe, a vacuum pump, and a flue gas purifier connected in sequence, as well as a gas cylinder and an air inlet pipe connected in sequence, wherein the exhaust pipe and the air inlet pipe are both connected to the crucible, and the gas cylinder is filled with an inert gas; The pouring system includes a dumping platform, a gantry moving platform, a horizontal moving trolley and steel rails. The steel rails are fixed to the ground, and the horizontal moving trolley runs on the steel rails. Two gantry moving platforms are provided, and a horizontal sliding is provided on the horizontal moving trolley, and the sliding direction is perpendicular to the steel rails. A lifting mechanism is provided on the gantry moving platform for driving the connected dumping platform to rise and fall vertically. The induction heating furnace body is connected to the rotary drive assembly on the dumping platform through a rotating shaft.

[0005] Furthermore, the crucible is a composite crucible, comprising an outer layer of ferritic stainless steel crucible and an inorganic non-metallic lining bonded to the inner wall thereof.

[0006] Furthermore, the crucible is made of amorphous refractory knotted material.

[0007] Furthermore, the induction heating furnace includes a refractory fiber preform and a refractory material part preset in the refractory fiber preform, and the compressive strength of the refractory material part is greater than 3 MPa.

[0008] Furthermore, the induction heating furnace has a density of less than 1000 Kg·m -3 It is cast from unshaped refractory knotted materials.

[0009] Furthermore, the induction heating coil is made of aluminum or aluminum alloy strip with a rectangular cross-section and an aluminum oxide film on the surface. The induction heating coil includes a side coil wrapped around the side of the induction heating furnace and a bottom coil located at the bottom of the induction heating furnace. The two coils are connected in series, and the height of the side coil is less than the height of the crucible.

[0010] Furthermore, the furnace shell includes a furnace mouth annular cover plate, a furnace shell bottom plate and a cylindrical surface connector connecting the furnace mouth annular cover plate and the furnace shell bottom plate. The furnace mouth annular cover plate is metal, and the furnace shell bottom plate and the cylindrical surface connector are fiberglass.

[0011] Furthermore, the gantry moving platform includes a gantry and a gantry base fixed at the lower part of the gantry, the gantry base is used to be slidably connected to the horizontal moving trolley and connected to the horizontal moving slide on the horizontal moving trolley; the lifting mechanism arranged on the gantry is a screw mechanism, the nut of the screw mechanism is fixed on the gantry, the upper end of the screw of the screw mechanism is rotatably connected to the screw upper base, and the screw drives the screw upper base to rise and fall vertically; the tipping platform is fixed on the screw upper base.

[0012] Furthermore, it also includes a cooling and charge preheating system, which includes a fan, an air inlet, an air cooling channel, an air outlet, a hot air pipe and a charge preheating box. The fan is arranged at the bottom of the induction heating furnace body and connected to the bottom of the induction heating furnace body. The air cooling channel is located between the induction heating coil in the induction heating furnace body and the insulation layer on the inner wall of the furnace shell. The air inlet side of the air cooling channel is connected to the fan through the air inlet at the bottom of the furnace body, and the air outlet side of the air cooling channel is connected to the hot air pipe through the air outlet on the furnace shell. The hot air pipe is connected to the charge preheating box outside the furnace body, and the material to be processed is placed in the charge preheating box.

[0013] Furthermore, a partition is provided in the charge preheating box, a plurality of vent holes are processed on the partition, and the air inlet is provided between the partition and the bottom plate of the charge preheating box.

[0014] The beneficial effects of the present invention are: 1. The present invention uses a vacuum melting and pouring integrated machine to complete melting and pouring in one go, eliminating the intermediate link of the pouring ladle, which not only reduces energy consumption but also improves production efficiency, laying the foundation for realizing intelligent production from melting to pouring.

[0015] 2. The present invention improves the quality of molten metal and solves the pollution problem in the smelting process by adopting vacuum refining and flue gas purification system without increasing the equipment cost much.

[0016] 3. By using rectangular cross-section, surface-oxidized aluminum alloy strips to make induction heating coils and combining them with cooling and charge preheating systems, compared with copper tubes and water cooling, not only is the cost significantly reduced, but waste heat is also effectively utilized, thereby further reducing energy consumption per unit output.

[0017] 4. The present invention improves the induction heating thermal efficiency of non-ferromagnetic metals and reduces energy consumption per unit output by adopting a composite crucible composed of a ferrite stainless steel crucible and an inorganic non-metallic lining. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the induction heating furnace body of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the induction heating coil of the present invention; Figure 3 This is a schematic structural diagram of a composite crucible comprising a ferritic stainless steel crucible and an inorganic non-metallic material lining according to the present invention; Figure 4 This is a schematic structural diagram of an induction heating furnace body using a composite crucible according to the present invention; Figure 5 This is a schematic diagram of the induction heating furnace structure of the amorphous refractory knotted material crucible and the fiber workpiece furnace of the present invention; Figure 6 Schematic diagram of an induction heating furnace body comprising an amorphous refractory agglomerated crucible and a low-density refractory agglomerated furnace according to the present invention; Figure 7 It is a schematic structural diagram of the cooling and charge preheating system of the present invention in the furnace body; Figure 8 It is a structural schematic diagram of the preheating box of the present invention; Figure 9 This is a schematic structural diagram of the vacuum refining and flue gas purification system of the present invention on the furnace body; Figure 10 It is a structural schematic diagram of the melting and pouring integrated machine of the present invention; Figure 11 It is a schematic diagram of the induction heating furnace body and the pouring and pouring platform of the present invention assembled together; Figure 12 Schematic diagram of the motion trajectory of the furnace mouth during the pouring and pouring process in the case of a fixed pouring and pouring platform base of the present invention; Figure 13 It is a structural schematic diagram of a single gantry mobile platform of the present invention; Figure 14 It is a schematic diagram of the induction heating furnace body, the pouring and pouring platform and the gantry moving platform assembled together according to the present invention; Figure 15 A schematic diagram of the horizontal movable trolley and rails of the present invention being assembled together; Markings in the figure: 1, induction heating furnace body, 11, crucible, 12, induction heating furnace, 13, induction heating coil, 14, furnace shell, 15, support body, 16, furnace nozzle, 17, furnace cover; 111. Ferritic stainless steel crucible, 112. Inorganic non-metallic material lining, 121. Refractory material parts, 131. Side coil, 132. Bottom coil, 141. Furnace mouth annular cover, 142. Cylindrical connector, 143. Furnace shell bottom plate, 144. Rotating shaft; 21. Fan, 22. Air inlet, 23. Air cooling channel, 24. Insulation layer, 25. Air outlet, 26. Hot air duct, 27. Charge preheating box, 271. Partition, 272. Air inlet; 31. Furnace nozzle cover, 32. Exhaust pipe, 33. Vacuum pump, 34. Flue gas purifier, 35. Inlet pipe, 36. Gas cylinder; 41. Dumping platform, 42. Gantry moving platform, 43. Horizontal moving trolley, 44. Rails; 411. Bearing, 412. Bearing seat, 413. First coupling, 414. First reducer, 415. First control motor, 416. Platform base; 421. Gantry, 422. Upper base of lead screw, 423. Lead screw, 424. Nut, 425. Lower base of lead screw, 426. Second coupling, 427. Second reducer, 428. Second control motor, 429. Gantry base, 4291. Slideway; 431. Trolley frame, 432. Guide rail, 433. Horizontal moving slide, 434. Trolley wheels, 435. Trolley drive assembly. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but they are not intended to limit the invention in any way.

[0020] An induction heating vacuum melting and pouring integrated machine includes an induction heating furnace body 1, a cooling and charge preheating system, a vacuum refining and fume purification system, and a pouring system, which are described in detail below.

[0021] 1. Induction heating furnace like Figure 1 As shown, the induction heating furnace body 1 includes a crucible 11, an induction heating furnace chamber 12, an induction heating coil 13, a furnace shell 14, a support body 15, a furnace nozzle 16 and a furnace cover 17.

[0022] The furnace shell 14 comprises an annular cover plate 141 for the furnace opening, a furnace shell bottom plate 143, and a cylindrical connector 142 connecting the annular cover plate 141 and the furnace shell bottom plate 143. The annular cover plate 141 is made of metal, while the furnace shell bottom plate 143 and the cylindrical connector 142 are made of fiberglass reinforced plastic. The annular cover plate 141, the cylindrical connector 142, and the furnace shell bottom plate 143 are integrally connected by bolts. A rotating shaft 144 is provided on each opposing side of the cylindrical connector 142. The two rotating shafts 144 are coaxially arranged and are used to tilt the induction heating furnace body 1 by rotating them during pouring.

[0023] An induction heating furnace 12 is disposed within the furnace shell, the crucible 11 is disposed within the induction heating furnace 12, and the induction heating coil 13 is disposed outside the induction heating furnace 12. The support body is interposed between the induction heating furnace 12 or the induction heating coil 13 and the furnace shell 14, and is used to transmit the force exerted on the induction heating furnace 12 or the induction heating coil 13 to the furnace shell 14. The nozzle 16 passes through the furnace shell 14, the induction heating furnace 12, and the crucible 11 in sequence from the outside to the inside, and is connected to the middle of the crucible 11 cavity for liquid pouring. That is, after smelting is completed, the liquid metal in the crucible 11 is directly poured into the casting mold through the nozzle 16.

[0024] like Figure 2As shown, the induction heating coil 13 includes a side coil 131 and a bottom coil 132 . The side coil 131 is a cylindrical spiral coil, and the bottom coil 132 is a planar spiral coil. These two coils are connected in series.

[0025] In terms of the arrangement of the induction heating coils 13, the prior art arranges them on the cylindrical surface of the entire height of the crucible, while the induction heating coils 13 of the present invention are concentratedly arranged at the lower part of the height of the crucible 11, that is, the height of the side coils 131 is less than the height of the crucible 11, and a bottom coil 132 is also arranged at the bottom of the crucible 11. Figure 1 As shown. The advantage of this arrangement is that it reduces the volume of the magnetic field, thereby increasing the magnetic field strength, which is beneficial to improving electrical efficiency (the ratio of eddy current heating to the sum of coil heating and eddy current heating). In addition, the present invention adopts vacuum melting. In principle, the charge is only added once to a furnace. That is, the charge is added before the furnace is opened, the furnace cover is closed, and heating begins after vacuuming. This requires the volume of the crucible to be large, generally not less than twice the volume of the liquid, that is, the height of the crucible is not less than twice the height of the liquid. In this way, when the charge begins to melt, the induction heating coil above the liquid level is no longer meaningful. Therefore, the height of the induction heating coil 13 is roughly consistent with the height of the liquid after the charge is completely melted. The volume of the liquid is determined by the capacity of the induction heating furnace. For different materials, due to the huge difference in the density of the liquid, the volume also varies greatly.

[0026] There is also a magnetic field outside the induction heating coil 13, which may also cause eddy currents in the materials in the magnetic field, which will also consume electrical energy. In order to reduce this part of the loss, the present invention uses non-magnetic insulating material glass fiber reinforced plastic as the furnace shell material. As a composite material, glass fiber reinforced plastic has high strength (300~500MPa, the strength of low-carbon structural steel is 200~300MPa), low density (1500~2100Kg·m -3 ), high specific strength, non-magnetic properties, and excellent insulation properties, and it does not generate eddy currents in changing magnetic fields. Therefore, the present invention uses fiberglass as the material for the furnace shell bottom plate 143 and cylindrical connector 142, solving the problem of furnace shell heating caused by magnetic leakage. Furthermore, it is lightweight and has excellent thermal insulation. Since the furnace shell top does not have the induction heating coil 13, it can be made of metal.

[0027] The nozzle 16 is located in the middle of the crucible 11 for pouring the molten metal. That is, after smelting is completed, the molten metal in the crucible 11 is poured directly into the mold through the nozzle 16. Existing induction heating melting furnaces often have the nozzle located at the furnace mouth, which has the disadvantage of easily discharging impurities on the surface of the molten metal when pouring out. Positioning the nozzle 16 in the middle and lower part of the crucible 11 prevents impurities on the surface of the molten metal from mixing into the molten metal during pouring, thus reducing the impurity content in the casting and improving the casting quality. Furthermore, the nozzle can be tilted at a smaller angle during pouring, which also reduces the stress on the furnace body.

[0028] Furthermore, the support body is a screw, which is made of a non-magnetic, insulating and heat-resistant glass fiber reinforced plastic round rod or a polytetrafluoroethylene round rod, and an internal thread is processed on the furnace shell 14 to support the induction heating furnace 12 or the induction heating coil 13 with the screw.

[0029] Further, if Figure 3 As shown, the crucible 11 is a composite crucible composed of a ferritic stainless steel crucible 111 and an inorganic non-metallic lining 112. The chemical composition of the ferritic stainless steel is (mass fraction): Cr: 13%~30%, Al: 0~5%, Mo: 0~2%, C: <0.1%, and the rest is Fe. The higher the operating temperature, the higher the amount of alloying elements added. The material of the inorganic non-metallic lining 112 includes but is not limited to amorphous refractory knotted materials, graphite mixtures, etc., which are beaten and sintered. Figure 3 As shown, the ferritic stainless steel crucible 112 and the furnace mouth annular cover plate 141 are cast in one step, so that the ferritic stainless steel crucible 112 and the furnace shell 14 together form a "concave" shaped structure, and the support of the support body 15 makes it have good strength and rigidity. Figure 4 shown.

[0030] Common non-ferrous (non-ferrous) metal materials, such as pure magnesium and its alloys, pure aluminum and its alloys, and pure copper and its alloys, have low melting points but are paramagnetic materials with magnetic permeabilities close to those of air. Under the same magnetic field conditions, their internal magnetic field strength is much lower than that of ferromagnetic iron-based alloys, making them difficult to induction heat or having relatively low thermal efficiency. Therefore, the present invention utilizes a ferritic stainless steel crucible and uses induction heating to heat the metal crucible and melt the non-ferrous metal or other non-magnetic material within the crucible. However, because the molten metal has a strong corrosive effect on the metal crucible, not only does it shorten the crucible's lifespan, but its corrosion products are also easily carried into the molten metal, increasing the inclusion content in the casting. Therefore, an inorganic non-metallic lining 112 is formed by adding a layer of amorphous refractory knotted material or graphite to the inner surface of the metal crucible, creating a composite crucible of metal and non-metal, thereby extending the lifespan of the crucible 11. The pouring temperature for magnesium alloys is between 650°C and 750°C, for aluminum alloys between 620°C and 760°C, and for copper alloys between 900°C and 1200°C. Therefore, the metal crucible must exhibit excellent oxidation resistance and high-temperature strength at high temperatures, necessitating the use of stainless steel. Stainless steel is categorized into ferritic, martensitic, austenitic, and duplex stainless steels. Austenitic stainless steel, commonly known as non-magnetic stainless steel, is not suitable due to its low magnetic permeability. Martensitic stainless steel, which forms austenite upon heating and ferrite upon cooling, is also not suitable due to the repeated structural changes that can cause stress, leading to deformation and cracking. Ferritic stainless steel, however, does not undergo phase transformations, yet has high magnetic permeability (comparable to that of industrial pure iron) and high resistivity, resulting in high magnetoelectric conversion capabilities. This is why ferritic stainless steel is the preferred crucible material. The chemical composition of the ferritic stainless steel for casting crucibles provided by the present invention is (by mass): Cr: 13% to 30%, Al: 0-5%, Mo: 0-2%, C: <0.1%, with the remainder being Fe. The higher the operating temperature, the higher the amount of alloying elements added. This alloy is also widely used in resistor materials, namely Fe-Cr-Al-Mo series resistance alloys. For example, 1Cr13Al4 has a maximum operating temperature of 1100°C when used as a resistor material, while 0Cr27Al7Mo2 has a maximum operating temperature of 1300°C. Of course, for use in crucibles, the Al content can be reduced and the Cr content increased.

[0031] Furthermore, the crucible 11 can also be made of amorphous refractory aggregate and used after sintering. When melting steel, due to its high melting point, a metal crucible cannot be used. Instead, a graphite crucible or a crucible made of amorphous refractory aggregate should be used. Therefore, the two crucibles of the present invention are selected based on the type of alloy being melted.

[0032] The present invention adopts a furnace plus crucible structure, which, on the one hand, facilitates the distinction between metal crucibles and crucibles made of amorphous refractory knotted materials, and on the other hand, is also intended to improve the currently commonly used crucibles made of amorphous refractory knotted materials. This improvement, i.e., the addition of a furnace, will significantly improve the thermal insulation performance, thereby achieving the purpose of energy saving.

[0033] Furthermore, the induction heating furnace 12 is made of refractory fiber preforms, the heat-resistant temperature is higher than 1500 ° C, and the density is 300~450 kg·m -3 A high-strength refractory material part 121 is provided in the refractory fiber preform. The refractory material part 121 has a compressive strength greater than 3 MPa and a heat-resistant temperature higher than 1300°C.

[0034] Furthermore, the induction heating furnace 12 is made of a material with a density of less than 1000 Kg·m -3 It is cast from unshaped refractory knotted materials.

[0035] The maximum refractory temperature of the refractory fiber preform used to make the induction heating furnace 12 can reach 1600℃, and the density is 300~450kg·m -3 (Typical value is 400kg·m -3 ), thermal conductivity is about 0.1W·m -1· ·K -1 , its disadvantage is low strength. To overcome the disadvantage of low strength, the present invention provides a high-strength refractory material part 121 in the refractory fiber preform. The refractory material part 121 has a compressive strength greater than 3MPa and a heat-resistant temperature greater than 1300°C. In most cases, lightweight refractory bricks or ceramic tubes or rods can meet the requirements. Another method for making the induction heating furnace 12 is to use a material with a density less than 1000Kg·m -3 It is cast from unshaped refractory knotted material, and its thermal conductivity is 0.15~0.2 W·m -1· ·K -1 Although its thermal conductivity is 1.5 to 2 times that of refractory fiber, its strength is much higher than that of refractory fiber preforms. In addition, its thermal conductivity is only that of ordinary unshaped refractory knotted materials (about 2 W·m -1· ·K -1 ) of 7.5%~10%.

[0036] When a refractory fiber preform is used to make the induction heating furnace 12, the strength of the induction heating furnace 12 is low, and the number of refractory material parts 121 added to the refractory fiber preform should be increased accordingly, and used in conjunction with the support body 15 to improve its bearing capacity, such as Figure 5 If the density is less than 1000Kg·m -3The amorphous refractory knotted material is used as the induction heating furnace 12. Since it has high strength, there is no need to add refractory material parts 121 in the induction heating furnace 12. The support body 15 is directly connected to the furnace shell 14 to ensure reliable strength. Figure 6 shown.

[0037] The following comparative analysis of the energy-saving effect of the present invention compared with the prior art is conducted through specific examples and heat transfer calculations.

[0038] Example 1: Calculate the inner diameter and height of a crucible. Take an aluminum melting furnace as an example, assuming the capacity is 100 kg and the liquid density is 2300 kg·m 3 , then the volume of the liquid is approximately 0.0435m 3 From the perspective of heat dissipation, it is hoped that the surface area will be smaller under the premise of the same volume, so the diameter and height of the liquid should be equal. Based on this, it can be calculated that the diameter D is equal to the height H, that is, , the crucible height should be greater than 760mm.

[0039] Since the height of the induction heating coil 13 is roughly the same as the height of the completely melted charge, the furnace mouth annular cover plate 141 of the furnace shell 14 is made of steel plate, and its distance from the induction heating coil 13 is more than 380 mm, and it is not easy to be heated by the magnetic field.

[0040] The existing medium frequency melting furnaces often use bakelite sticks to reinforce the induction heating coil, and then use amorphous refractory knotted materials directly inside the coil as a crucible, or use induction coil slurry (clay) to paste the inner and outer surfaces of the coil first, and then use amorphous refractory knotted materials inside to make a crucible after solidification. One of the disadvantages of this method is that the thermal conductivity of the refractory material used is relatively high, at 2W·m -1 ·k -1 The thermal conductivity of the preform made of refractory fiber is very small, about 0.1W·m -1 ·k -1 About 1 / 20 of the former. If the thickness of the two is the same and the temperature difference between the inside and the outside is also the same, the heat dissipation power of the prefabricated parts made of refractory fibers is only 1 / 20=5% of that of the refractory castables, which has a significant energy-saving effect.

[0041] In existing technology, induction heating coils are wound using copper square tubes. Because copper easily oxidizes at high temperatures, water cooling is necessary. This results in significant heat loss, a key contributor to the low thermal efficiency of induction heating. The heat removed by the cooling water comes from two sources: heat dissipated by the crucible and Joule heating generated by the current flowing through the copper tube itself. The following example calculates and analyzes the power dissipated by the crucible.

[0042] Example 2 Analysis of the existing technology: Assume that the thickness of the crucible plus the induction heating furnace is 150mm, the temperature inside the furnace is 1500℃, and the copper tube coil is cooled by water. The outer wall temperature of the furnace is about 100℃, and the temperature difference between the inside and outside is 1400℃. The furnace and crucible are all made of knotted materials, and the average thermal conductivity is 2W·m -1 ·k -1 , the heat dissipation power per unit area is: 2÷0.15×1400=18666.7w·m -2 =18.7kw·m -2 According to Example 1, the inner diameter of the crucible is designed. The heat dissipation area is calculated by taking the furnace plus the crucible middle diameter, which is 380+150=530mm. The heat dissipation area is 3.14×0.53×0.76+2×3.14×0.53 2 / 4≈1.71m 2 , with a heat dissipation power of 32 kW. For melting high-carbon steel, the heat required to melt 1 kg of high-carbon steel and heat it to 1500°C is 653 × 1400 (heat absorbed in the solid state) + 272,000 (latent heat of fusion) + 816 × 100 (heat absorbed in the liquid state) = 1,267,800 J = 0.352 kWh. Based on the dimensions in Example 1, 100 / 2.3 × 7 = 300 kg can be melted at a time, absorbing 105.5 kWh of heat. Assuming a melting time of 1 hour, the total heat dissipation is 32 kWh, representing 30.3% of the absorbed heat.

[0043] Example 3 Analysis of the present invention with a furnace containing refractory fiber preforms and a crucible containing refractory materials: 50 mm refractory fiber preforms (with an average thermal conductivity of 0.1 W·m -1 ·k -1 ) as the furnace and add a 100mm amorphous refractory crucible. Other conditions are the same as in Example 2. The heat dissipation power is 1400÷(0.05 / 0.1+0.1 / 2)=2545.5 W·m -2 ≈2.55 kw·m -2 , only 13.6% of Example 2, the total heat loss is 4.35kwh, and the heat loss is 4.1% of the heat absorption, with significant energy saving effect.

[0044] Example 4 Analysis of low-density refractory knotted material as furnace + unshaped refractory knotted material as crucible: Assume that the furnace thickness is 50mm and the density of the furnace is less than 1000Kg·m -3 It is cast from unshaped refractory knotted material, and its thermal conductivity is 0.15W·m -1 ·k -1 The crucible is 100 mm thick and uses amorphous refractory knotting material. Other conditions are the same as in Example 2. The heat dissipation power is 1400÷(0.05 / 0.15+0.1 / 2)=3652.2 W·m -2≈3.65 kw·m -2 , only 19.5% of Example 2, the total heat loss is 6.24kwh, and the heat loss is 5.9% of the heat absorption, with significant energy saving effect.

[0045] Example 5: For traditional materials with a density higher than 1000 kg·m -3 Analysis of furnace hearth + metal crucible made of amorphous refractory knotted material: Assume that the furnace hearth thickness is 60mm and the furnace hearth density is higher than 1000Kg·m -3 The density of the unshaped refractory knotted material is about 2000Kg·m -3 , the thermal conductivity is about 2 W·m -1·k-1 The furnace is filled with a metal crucible. If the crucible temperature is 700°C and the copper coil is cooled with water, the outer wall temperature of the furnace is about 100°C, and the temperature difference between the inside and outside is 600°C. The furnace is made of knotted material, and the average thermal conductivity is 2W·m -1 ·k -1 , the heat dissipation power per unit area is: 2÷0.06×600=20000w·m -2 =20kw·m -2 According to Example 1, the inner diameter of the crucible is designed. The crucible thickness is 20mm. The middle diameter of the furnace is 420+60=480mm to calculate the heat dissipation area. The heat dissipation area is 3.14×0.48×0.76+2×3.14×0.48 2 / 4≈1.51m 2 If aluminum alloy is melted, the heat required to melt 1 kg of aluminum alloy and heat it to 700°C is 1119000 J = 0.31 kWh. Based on the dimensions in Example 1, 100 kg can be melted at a time, and the heat absorbed is 31 kWh. Assuming the melting time is 1 hour, the heat lost is 30.2 kWh, which is 97.4% of the heat absorbed.

[0046] Example 6 Analysis of fiber furnace + metal crucible: If a 60mm refractory fiber preform (average thermal conductivity of 0.1W·m -1 ·k -1 ) as the furnace, and other conditions are the same as in Example 5, then the heat dissipation power is 0.1÷0.06×600=1000w·m -2 =1kw·m -2 The heat dissipated is 1.5kwh, which is 4.8% of the absorbed heat. Compared with Example 5, the energy-saving effect is significant.

[0047] The above analysis shows that furnace-use refractory fiber preforms offer significant energy savings, but they also have a disadvantage: low strength. To overcome this disadvantage, the present invention incorporates a higher-strength refractory material member 121 within the refractory fiber preform, which, together with the support member 15, enhances its load-bearing capacity (the refractory fiber preform is essentially free of stress).

[0048] The induction heating furnace body 1 of the present invention is equipped with a furnace cover 17, which is made of refractory fiber prefabricated parts and also has excellent heat insulation and energy saving effects. Therefore, the heat loss from the crucible 11 is very small, which has a significant energy saving effect. The thermal efficiency of induction heating is affected not only by the heat dissipation factors analyzed above, but also by the heat generated by the induction heating coil 13 itself.

[0049] Furthermore, the induction heating coil 13 of the present invention is wound with aluminum or aluminum alloy strip having a rectangular cross-section and an aluminum oxide film on the surface. When DC current is applied, the resistivity of aluminum is approximately 1.5 times that of copper. Perhaps for this reason, high-power induction heating coils are currently commonly wound with copper tubes. However, due to the skin effect of current distribution when AC current passes through a conductor, the resistivity of aluminum is less than 1.5 times that of copper under AC current. This is because the current penetration depth (the depth corresponding to the current dropping to 36.8% of the surface current) is different from the current penetration depth. (ρ is resistivity) is proportional to (f is the frequency) and is inversely proportional. Hollow tubes (whether round or square) take up a lot of space, making coil winding difficult. Thin strips made of aluminum alloy (to reduce the increase in resistance caused by the skin effect) have extremely high insulation properties after surface oxidation. Stacking them together to form coils offers greater flexibility and economy. The dense oxide layer on the surface of aluminum alloy prevents further oxidation at high temperatures (e.g., below 400°C), thus eliminating the need for water cooling. Of course, as the temperature increases, the resistivity also increases (approximately 40% for a 100°C increase in resistivity). This increase in resistance can be compensated by increasing the cross-sectional area. If the crucible's outer wall temperature increases from 100°C to 400°C, according to Example 2, the internal and external temperature difference decreases from 1400°C to 1100°C, then the heat dissipation power is 1100 ÷ (0.05 / 0.1 + 0.1 / 2) = 2000 W·m -2 =2kW·m -2 , and 2.5455 kw·m -2 This means that increasing thermal efficiency by raising the surface temperature is not very effective and may even reduce it. This is because increasing the temperature increases the coil resistance, which in turn increases the energy consumed by the coil resistance. Therefore, it is best to keep the coil temperature as low as possible. Coil cooling is accomplished by the cooling and charge preheating systems.

[0050] 2. Cooling and charge preheating system like Figure 7 、 8 As shown, the cooling and charge preheating system includes a fan 21, an air inlet 22, an air cooling channel 23, an insulation layer 24, an air outlet 25, a hot air pipe 26, and a charge preheating box 27. The fan 21 is located below the furnace shell bottom plate 143, the air inlet 22 is located on the furnace shell bottom plate 143 (to allow ventilation from top to bottom of the furnace shell bottom plate 143), the insulation layer 24 is located close to the inner wall of the cylindrical connector 142 of the furnace shell 14, the air cooling channel 23 refers to the gap between the insulation layer 24 and the induction heating coil 13, and the air outlet 25 is located on the upper part of the cylindrical connector 142 of the furnace shell 14. Figure 8 As shown, an air inlet 272 is provided on one side of the charge preheating box 27, and the two ends of the hot air pipe 26 connect the air outlet 25 and the air inlet 272. A partition 271 is provided within the charge preheating box 27, which is machined with multiple ventilation holes. The air inlet 272 is located between the partition 271 and the bottom plate of the charge preheating box 27. The fan 21 draws room temperature air through the air inlet 22 into the air cooling channel 23 to cool the induction heating coil 13. The hot air then flows through the air outlet 25 and the hot air pipe 26 to the air inlet 272 and enters the charge preheating box 27, heating the material placed on the partition 271 in the charge preheating box 27, thereby utilizing waste heat and achieving energy conservation and emission reduction effects.

[0051] Furthermore, the portion above the induction heating coil 13 is not provided with an air cooling channel 23 and is filled with thermal insulation material.

[0052] Furthermore, the fan is a variable frequency fan.

[0053] This invention uses air cooling to cool the induction heating coils. A fan draws room-temperature air through an air inlet located on the bottom of the furnace shell into an air cooling channel. The air is then discharged through an air outlet located on the upper side of the furnace shell, cooling the furnace and induction heating coils. The resulting hot air provides heat energy for the charge preheating system, thereby improving thermal efficiency. Compared with the existing water-cooling method, this method reduces equipment costs (no water cooling system is required) and actual operating costs (the power required by the fan is lower than that required by the water pump in the water circulation system).

[0054] 3. Vacuum refining and flue gas purification system like Figure 9As shown, the vacuum refining and flue gas purification system primarily includes a furnace nozzle cover 31, an exhaust pipe 32, a vacuum pump 33, a flue gas purifier 34, an air intake pipe 35, and a gas cylinder 36. Both the exhaust pipe 32 and the air intake pipe 35 pass through the furnace cover 17 and communicate with the crucible 11. The air inlet of the vacuum pump 33 is connected to the exhaust pipe 32 via a flexible hose, while the air outlet of the vacuum pump 33 is connected to the air inlet of the flue gas purifier 34. Inert gas stored in the gas cylinder 36 is passed into the crucible 11 via the air intake pipe 35. The furnace nozzle cover 31 is used to cover the furnace nozzle 16, creating a seal and ensuring a vacuum environment within the furnace.

[0055] The advantages of vacuum refining are self-evident. The present invention closely combines vacuum refining with atmospheric casting. Compared with the existing vacuum melting and vacuum casting, the equipment cost is significantly reduced, and compared with the atmospheric melting of the existing technology, the equipment cost increases very little because only a mechanical vacuum pump and a flue gas purifier are added. At the same time, the problems of vacuum refining and environmental pollution during the melting process are solved. According to the induction heating furnace structure of the present invention (see Figure 1 To achieve vacuum melting, the furnace nozzle 16 must be sealed with a nozzle cover 31. At the same time, the furnace cover 17 and crucible 11 must be well sealed. The addition of an inert gas system primarily involves flowing inert gas into the crucible 11 before pouring. Only then can the nozzle cover 31 on the furnace nozzle 16 be opened for pouring. During the pouring process, only the molten metal flowing out of the crucible 11 comes into contact with air, while the molten metal inside the furnace remains protected by the inert gas.

[0056] from Figure 9 It can be seen that the rotating shaft 144 provided on the furnace shell 14 plays two roles: first, it supports the entire furnace body and the weight of the molten metal, and second, it utilizes its rotation to pour out the molten metal in the crucible 11, i.e., to perform pouring. The pouring system is described below.

[0057] 4. Casting system like Figure 10 As shown, the pouring system includes a dumping platform 41, a gantry moving platform 42, a horizontal moving trolley 43 and a rail 44. The rail 44 is fixed to the ground, and the horizontal moving trolley 43 moves on the rail 44. The horizontal moving slide mounted on the horizontal moving trolley 43 drives the gantry moving platform 42 to move horizontally in a direction perpendicular to the rail 44. The vertical moving platform mounted on the gantry moving platform 42 drives the dumping platform 41 to move up and down. The rotary drive assembly mounted on the dumping platform 41 drives the induction heating furnace body 1 to dump. Through the coordinated action of the above-mentioned three-dimensional movement and one-dimensional rotation, the outlet of the furnace nozzle 16 reaches the designated casting gate position, thereby completing the pouring.

[0058] Further, if Figure 11As shown, the pouring platform 41 includes a bearing 411 mounted on the rotating shaft 144, a bearing seat 412, a first coupling 413, a first reducer 414, a first control motor 415, and a platform base 416. The bearing seat 412, first reducer 414, and first control motor 415 are mounted on the platform base 416. The first control motor 415 drives the first reducer 414. The output shaft of the first reducer 414 is connected to the rotating shaft 144 through the first coupling 413, thereby achieving rotation of the induction heating furnace body 1 relative to the platform base 416 to complete the pouring operation.

[0059] Furthermore, the bearing is a self-lubricating sliding bearing.

[0060] Furthermore, the first reducer is a worm gear reducer.

[0061] Furthermore, the first control motor is a stepping motor or a servo motor to control the rotation angle of the induction heating furnace body 1 .

[0062] like Figure 12 As shown, if the platform base of the tipping platform 41 is fixed on a fixed base, the furnace nozzle opening is on a π / 2 arc during tipping, and the position of the furnace nozzle opening changes greatly during the tipping process, which does not meet the requirements of pouring. The position of the furnace nozzle opening should remain basically unchanged during pouring, which needs to be ensured by the gantry moving platform 42 and the horizontal moving trolley 43.

[0063] like Figure 13 As shown, the gantry moving platform 42 includes a gantry 421, a lead screw upper base 422, a lead screw 423, a nut 424, a lead screw lower base 425, a second coupling 426, a second reducer 427, a second control motor 428, and a gantry base 429. The bottom of the gantry 421 is fixedly supported on the gantry base 429, the nut 424 is fixed to the middle of the gantry 421, the upper end of the lead screw 423 engaged with the nut 424 is rotatably connected to the lead screw upper base 422, the lower end of the lead screw 423 passes through the lead screw lower base 425 and is rotatably connected to the lead screw lower base 425, the second control motor 428 and the second reducer 427 are fixed to the lower surface of the lead screw lower base 425, and the output shaft of the second reducer 427 is transmission-connected to the lower end of the lead screw 423 via the second coupling 426. The second control motor 428 drives the screw 423 to rotate on the nut 424, driving the screw upper base 422 and the screw lower base 425 to move upward or downward along the inner side of the gantry 421, thereby driving the tipping platform 41 fixed on the screw upper base 422 to move up and down. Specifically, the platform base 416 of the tipping platform 41 is fixed to the screw upper base 422. Therefore, if Figure 14As shown, two gantry moving platforms 42 are provided opposite to each other, and by supporting the two tipping platforms 41 , the induction heating furnace body 1 is supported and the upper and lower positions are adjusted.

[0064] The lower surface of the gantry base 429 is provided with a slide groove 4291, which is perpendicular to the rotating shaft 144 on the furnace shell 14. The gantry movable platform 42 is slidably connected to the horizontal movable trolley 43 through the slide groove 4291 to enable the furnace nozzle 16 to approach or leave the casting mold.

[0065] Furthermore, the second reducer 427 is a worm gear reducer or a planetary reducer.

[0066] Furthermore, the second control motor 428 is a stepper motor or a servo motor so as to accurately control the lifting height.

[0067] Furthermore, the upper and lower ends of the screw 423 can be rotatably connected to the screw upper base 422 and the screw lower base 425 through bearings to avoid driving the screw upper base 422 and the screw lower base 425 to rotate.

[0068] In this embodiment, the lifting and lowering of the dumping platform 41 is achieved by a screw mechanism. In other embodiments, a gear rack mechanism or a lifting cylinder or other structures can also be used to replace the screw mechanism.

[0069] like Figure 15 As shown, the horizontal movable trolley 43 includes a trolley frame 431, a guide rail 432, a horizontal movable slide 433, a trolley wheel 434 and a trolley drive assembly 435. The guide rail 432 is fixedly arranged on the upper surface of the trolley frame 431 and is symmetrically arranged about the horizontal movable slide 433. The length direction of the guide rail 432 is parallel to the trolley wheel axis and slides with the slide groove 4291. The moving part of the horizontal movable slide 433 is fixedly connected to the gantry base 429, and the moving direction is parallel to the guide rail 432, thereby driving the gantry movable platform 42 to move along the guide rail 432. The trolley drive assembly 435 is arranged on the lower surface of the trolley frame 431 and is located in the middle of the front and rear positions to drive the trolley wheel 434 to rotate, so that the trolley frame 431 moves along the steel rail 44, thereby realizing the two-dimensional movement of the gantry movable platform 42 in the horizontal direction.

[0070] Furthermore, the horizontal movable slide 433 and the trolley driving assembly 435 are both driven by a stepper motor or a servo motor.

[0071] In other embodiments, the cooling and charge preheating system 2 may not be provided, or the charge preheating box 27 may not be provided, and the cooled hot air may be discharged from the furnace into the atmosphere or collected by a special gas collecting device.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Those skilled in the art should understand that the specific implementation methods of the present invention can be modified or replaced with equivalents with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the pending claims.

Claims

1. An induction heating vacuum melting and pouring machine, comprising an induction heating furnace body, which comprises a crucible, an induction heating furnace chamber, an induction heating coil, a support body and a furnace shell arranged in sequence from the inside to the outside, characterized in that: The induction heating furnace body also includes a rotating shaft and a furnace nozzle. The rotating shafts are provided with two and are coaxially arranged on opposite sides of the outer wall of the furnace shell. The furnace nozzle passes through the furnace shell, the induction heating furnace chamber and the crucible from the outside to the inside in sequence and is connected to the middle of the crucible cavity. Also includes: A vacuum refining and flue gas purification system, comprising an exhaust pipe, a vacuum pump, and a flue gas purifier connected in sequence, as well as a gas cylinder and an air inlet pipe connected in sequence, wherein the exhaust pipe and the air inlet pipe are both connected to the crucible, and the gas cylinder is filled with an inert gas; The pouring system includes a dumping platform, a gantry moving platform, a horizontal moving trolley and steel rails. The steel rails are fixed to the ground, and the horizontal moving trolley runs on the steel rails. Two gantry moving platforms are provided, and a horizontal sliding is provided on the horizontal moving trolley, and the sliding direction is perpendicular to the steel rails. A lifting mechanism is provided on the gantry moving platform for driving the connected dumping platform to rise and fall vertically. The induction heating furnace body is connected to the rotary drive assembly on the dumping platform through a rotating shaft.

2. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The crucible is a composite crucible, comprising an outer ferrite stainless steel crucible and an inorganic non-metallic lining adhered to the inner wall of the crucible.

3. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The crucible is made of amorphous refractory knotted material.

4. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The induction heating furnace comprises a refractory fiber preform and a refractory material part preset in the refractory fiber preform, and the compressive strength of the refractory material part is greater than 3 MPa.

5. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The induction heating furnace has a density of less than 1000Kg·m -3 It is cast from unshaped refractory knotted materials.

6. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The induction heating coil is made of aluminum or aluminum alloy strip with a rectangular cross-section and an aluminum oxide film on the surface. The induction heating coil includes a side coil wrapped around the side of the induction heating furnace and a bottom coil located at the bottom of the induction heating furnace. The two coils are connected in series, and the height of the side coil is less than the height of the crucible.

7. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The furnace shell includes a furnace mouth annular cover plate, a furnace shell bottom plate and a cylindrical surface connector connecting the furnace mouth annular cover plate and the furnace shell bottom plate. The furnace mouth annular cover plate is made of metal, and the furnace shell bottom plate and the cylindrical surface connector are made of glass fiber reinforced plastic.

8. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: The gantry moving platform includes a gantry and a gantry base fixed at the lower part of the gantry, the gantry base is used for sliding connection to the horizontal moving trolley and connected to the horizontal moving slide on the horizontal moving trolley; the lifting mechanism provided on the gantry is a screw mechanism, the nut of the screw mechanism is fixed on the gantry, the upper end of the screw of the screw mechanism is rotatably connected to the screw upper base, and the screw drives the screw upper base to rise and fall vertically; the tipping platform is fixed on the screw upper base.

9. The induction heating vacuum melting and pouring machine according to claim 1, characterized in that: It also includes a cooling and charge preheating system, which includes a fan, an air inlet, an air cooling channel, an air outlet, a hot air pipe and a charge preheating box. The fan is arranged at the bottom of the induction heating furnace body and is connected to the bottom of the induction heating furnace body. The air cooling channel is located between the induction heating coil in the induction heating furnace body and the insulation layer on the inner wall of the furnace shell. The air inlet side of the air cooling channel is connected to the fan through the air inlet at the bottom of the furnace body, and the air outlet side of the air cooling channel is connected to the hot air pipe through the air outlet on the furnace shell. The hot air pipe is connected to the charge preheating box outside the furnace body, and the material to be processed is placed in the charge preheating box.

10. The induction heating vacuum melting and pouring machine according to claim 9, characterized in that: A partition is provided in the charge preheating box, a plurality of vent holes are processed on the partition, and the air inlet is provided between the partition and the bottom plate of the charge preheating box.

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