An inductive coil and a method of manufacturing the same

Abstract

The present application relates to a kind of induction coil and manufacturing method, induction coil includes copper coil, screw, bolt, multiple long strip epoxy glass plate, epoxy glass cover plate, brown corundum casting material, foam ceramic layer, graphite hard felt, graphite heating element, long strip epoxy glass plate is fixed with copper coil using screw and bolt;Epoxy glass cover plate is set in the outside of multiple long strip epoxy glass plate;The part of the outside of coil not covered by long strip epoxy glass plate is coated with ceramic paint, brown corundum casting material is provided in the outside of ceramic paint;Foam ceramic layer is covered on the inner side surface of brown corundum casting material;Graphite hard felt is covered on the inner surface of foam ceramic layer, and graphite heating element is provided on the inner surface of graphite hard felt.

Description

TECHNICAL FIELD

[0001] The present application relates to an induction coil and a manufacturing method thereof, in particular to a heating induction coil suitable for use in high-temperature environments. BACKGROUND

[0002] In high-temperature equipment such as heating furnaces and vacuum furnaces, a medium-frequency induction coil heating device is usually used. Since the temperature in the furnace is relatively high, there are high requirements for the insulation and high-temperature resistance of the coil, especially for heating furnaces with a temperature of 3000°C or above, the long-term stability and safety of the induction coil need to be ensured. In the existing insulation treatment of medium-frequency induction coils, a layer of insulating paint is brushed on the surface, or a glass tape is wound on the surface of the coil, and the coil is fixed with a stainless steel and insulating porcelain seat, or a layer of casting material is sprayed on the surface. The medium-frequency induction coil cannot be operated stably for a long time, and the insulation of the coil is often damaged after a few months or even shorter, resulting in serious safety hazards and accidents such as water leakage and electric leakage. SUMMARY

[0003] In order to solve the above problems, the present application provides an induction coil, which comprises a copper coil, screws, bolts, a plurality of long strip-shaped epoxy glass plates, an epoxy glass cover plate, brown corundum casting material, a foam ceramic layer, a graphite hard felt, and a graphite heating body. A plurality of screws are welded on the outer periphery of each turn of the copper coil, and the positions of the screws on each turn are the same, so that the screws of the coil are aligned along the length direction of the coil. A plurality of long strip-shaped epoxy glass plates are provided, and a plurality of countersunk holes are formed in the long strip-shaped epoxy glass plates. Each row of screws is located in the countersunk hole along the length direction of the coil, and the bolts are screwed with the screws to fix the long strip-shaped epoxy glass plates and the copper coil. An epoxy glass cover plate is arranged outside the long strip-shaped epoxy glass plates. The part of the coil which is not covered by the long strip-shaped epoxy glass plates is coated with ceramic paint, and the brown corundum casting material is arranged outside the ceramic paint. The foam ceramic layer is arranged on the inner side surface of the brown corundum casting material. The graphite hard felt is arranged on the inner surface of the foam ceramic layer, and the graphite heating body is arranged on the inner surface of the graphite hard felt.

[0004] Preferably, a structural adhesive is filled between the countersunk hole and the bolt.

[0005] Preferably, the thickness of the brown corundum casting material on the outer layer of the coil is 10 mm, and the thickness of the brown corundum casting material on the inner layer of the coil is 20 mm.

[0006] Preferably, the copper coil is a plurality of groups.

[0007] Preferably, the graphite hard felt and the graphite heating body are spliced together, and notches and protrusions are arranged between the segments to match each other.

[0008] Preferably, the thickness D of the graphite hard felt is 0.1*T-120, wherein T is the design requirement of high temperature resistance, ranging from 1400 to 4000℃, and the unit of the thickness of the graphite hard felt is millimeter.

[0009] Preferably, the graphite heating body is a hollow cylinder with a thickness greater than 20mm.

[0010] The application also provides a manufacturing method of the induction coil, comprising the following steps:

[0011] S1: preparing a copper coil;

[0012] S2: welding a plurality of screws on the outer periphery of each turn of the coil, the positions of the screws on the outer periphery of each turn of the coil being the same, so that the screws of the coil are aligned along the length direction of the coil;

[0013] S3: preparing a plurality of long strip-shaped epoxy glass plates, a plurality of countersunk holes being formed in the long strip-shaped epoxy glass plates along the length direction, the pitch of the plurality of countersunk holes being consistent with the pitch of the screws arranged along the length direction of the coil;

[0014] S4: mounting the long strip-shaped epoxy glass plates on the outer part of the coil: the screws on the outer part of the coil pass through the countersunk holes of the long strip-shaped epoxy glass plates, and nuts are mounted on the screws, so as to fix the coil and the long strip-shaped epoxy glass plates;

[0015] S5: after the copper coil is fixed, the copper coil is put into a sand blasting chamber for sand blasting treatment of the inner and outer surfaces of the copper coil;

[0016] S6: coating an insulation ceramic paint with high temperature resistance of 600℃ on the surface of the copper coil: the thickness of a single coating is between 0.1-0.2mm, and the ceramic paint is coated again after drying, and the coating is repeated for 3 times;

[0017] S7: putting the copper coil into an oven and baking at 200℃ for 4 hours;

[0018] S8: after the baking is completed, a wooden mold is made according to the size of the induction coil and the thickness of the castable to be cast, and the coil is placed in the mold;

[0019] S9: injecting brown corundum castable into the mold and vibrating the castable with a vibrating rod;

[0020] S10: after the brown corundum castable is cast, the castable is naturally cooled and dried at a temperature of 20-30℃ for 5 days, and then the mold is removed;

[0021] S11: injecting structural adhesive into the countersunk holes of the long strip-shaped epoxy glass plates to fill the gap between the nuts and the countersunk holes;

[0022] S12: covering and fixing the long strip-shaped epoxy glass plates with another epoxy glass cover plate outside the long strip-shaped epoxy glass plates;

[0023] S13: sequentially sticking a foam ceramic layer, a graphite hard felt and a graphite heating body on the inner surface of the brown corundum castable, and the foam ceramic layer, the graphite hard felt and the graphite heating body form a cylinder.

[0024] Preferably, the step S13 is performed between steps S10 and S11.

[0025] Preferably, in the step S1, the copper coil is multiple groups.

[0026] The present application has the following technical effects: (1) the long strip-shaped epoxy glass plate is used to fix the coil, and the coil is not easy to be damaged, and there is no conductive material around, so that the risk of electric leakage is eliminated; (2) the graphite hard felt and the high-temperature-resistant foam ceramic layer are used to play the role of heat insulation and heat preservation, and both of the two materials are light and high-temperature-resistant, so that the heat storage is small and the thermal conductivity is low, thereby the equipment is quickly heated. If oxidation or damage occurs during use, the brown corundum castable is provided to play an additional high-temperature-resistant role, and the brown corundum castable itself is also electrically insulated, thereby avoiding the danger of electric leakage; (3) the wooden mold is used to avoid that metal chips or rust are mixed into the castable during casting, so as to reduce the temperature resistance of the castable and avoid heating when the coil is powered on. Finally, the service life of the induction coil is greatly increased, and major safety hazards and accidents such as water leakage and electric leakage are avoided. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural diagram of the induction coil of the present application;

[0028] Figure 2 is Figure 1 A-A sectional view in

[0029] Figure 3 is Figure 1 a partial enlarged view. DETAILED DESCRIPTION

[0030] Referring to Figures 1-3 , the induction coil of the present application comprises a copper coil 1, a brass screw 2, a bolt 3, a plurality of long strip-shaped epoxy glass plates 4, an epoxy glass cover plate 5, a brown corundum castable 6, a foam ceramic layer 7, a graphite hard felt 8 and a graphite heating body 9.

[0031] A plurality of brass screws 2 are welded on the outer periphery of each turn of the copper coil, the positions of the brass screws on the outer periphery of each turn of the copper coil are the same, so that the brass screws of the coil are aligned along the length direction of the coil; a plurality of countersunk holes are formed in the long strip-shaped epoxy glass plate 4, and each row of brass screws is located in the countersunk hole along the length direction of the coil; the bolt 3 is screwed with the brass screw 2, so as to fix the plurality of long strip-shaped epoxy glass plates with the copper coil.

[0032] The epoxy glass cover plate 5 is further arranged outside the plurality of long strip-shaped epoxy glass plates.

[0033] In the prior art, the copper coil is fixed by an insulating porcelain seat, a stainless steel angle steel or a U-shaped structure stainless steel, which is not firm and safe. The coil is fixed by an electrically insulating long strip epoxy glass plate in the present application, which is not easy to be damaged and has no conductive material around, so that the risk of electric leakage is eliminated.

[0034] The part of the coil not covered by the long strip epoxy glass plate is coated with an insulating ceramic paint (not shown), and the outside of the insulating ceramic paint is provided with brown corundum castable 6.

[0035] The main functions of the brown corundum castable are as follows: 1) insulation; the dry brown corundum castable is insulating, which further insulates and protects the copper coil; 2) high temperature resistance; when the heat preservation layer inside the brown corundum castable is damaged, the high temperature radiation to the high temperature castable will not be damaged; and 3) non-magnetic; the brown corundum castable closely adheres to the copper induction coil and will not heat itself due to magnetic conduction.

[0036] Structural glue 10 is also filled between the countersunk hole and the bolt to fill the gap between the bolt and the countersunk hole.

[0037] Preferably, the thickness of the outer layer brown corundum castable is 10 mm, and the thickness of the inner layer brown corundum castable is 20 mm.

[0038] The induction coil is composed of two or more groups of copper coils wound in parallel. In order to solve the problem of consistent magnetic field direction of the two or more groups of coils, the two or more groups of coils adopt the principle of same input and same output.

[0039] Since the discharge phenomenon occurs between the two groups of copper coils when the potential difference between the two groups of coils is greater than 300 V in a vacuum furnace, causing the failure of the equipment, the number of coil groups is determined according to the power, the inductive reactance of each coil, and the voltage required by each group of coils.

[0040] The copper coil is a hollow circular tube or square tube, and cooling water can be introduced into the inside for cooling.

[0041] The inner surface of the brown corundum castable 6 is covered with a foam ceramic layer 7, and the inner surface of the foam ceramic layer is covered with a graphite hard felt 8. The carbon content of the graphite hard felt is above 99.99%, the density is 400-500 Kg / m3, and the maximum temperature resistance is above 3000 degrees.

[0042] The inner surface of the graphite hard felt is covered with a graphite heating body 9. When the coil is powered on, an induced current is generated in the graphite heating body, thereby forming high temperature.

[0043] The thickness D (unit: mm) of the graphite hard felt is determined by the following formula: D=0.1*T-120, wherein T is the design requirement of high temperature resistance, and ranges from 1400 to 4000 DEG C.

[0044] The graphite heating body is made of graphite particles, and the density is above 1760 Kg / m3. The graphite heating body can be made into a circular shape or a square shape, and can be made into a required shape according to the shape of the coil. The thickness of the graphite heating body is not less than 20 mm.

[0045] Due to the large size of the cylindrical shape surrounded by the induction coil, the graphite hard felt 8 and the graphite heating body 9 can be spliced by multiple segments, and the segments are provided with protrusions and recesses matched with each other to form a snap buckle or a wedge structure, which is beneficial to splicing and prevents the material from deforming to form a gap at high temperature.

[0046] The graphite hard felt 8 and the high-temperature-resistant foam ceramic layer 7 are adopted in the application to play a heat insulation and heat preservation role. Both of the two materials are light and high-temperature-resistant materials, have low heat storage and low thermal conductivity, so that the equipment can be heated quickly. If oxidation or damage occurs during use, the brown corundum castable is provided to play an additional high-temperature-resistant role, and the brown corundum castable itself is also electrically insulated, so as to avoid the danger of electric leakage. In this way, the service life of the whole coil is greatly prolonged compared with the existing induction coil.

[0047] The application further provides a manufacturing method of the induction coil, which comprises the following steps:

[0048] S1: preparing a copper coil;

[0049] S2: welding a plurality of screws on the outer periphery of each coil turn, and the positions of the screws on the outer periphery of each coil turn are the same, so that the screws of the coil are aligned along the length direction of the coil;

[0050] S3: preparing a plurality of long strip-shaped epoxy glass plates, and a plurality of countersunk holes are formed in the long strip-shaped epoxy glass plates along the length direction, and the pitch of the plurality of countersunk holes is consistent with the pitch of the screws arranged in the length direction of the coil;

[0051] S4: installing the long strip-shaped epoxy glass plates outside the coil: the screws outside the coil pass through the countersunk holes of the long strip-shaped epoxy glass plates, and nuts are installed on the screws, so as to fix the coil and the long strip-shaped epoxy glass plates;

[0052] S5: after the copper coil is fixed, the copper coil is placed into a sand blasting chamber for sand blasting treatment of the inner and outer surfaces of the copper coil to improve the adhesion of the coating layer on the surface of the copper coil;

[0053] S6: coating an insulation ceramic paint with high temperature resistance of 600 DEG C on the surface of the copper coil: the single coating thickness is between 0.1 and 0.2 mm, and the ceramic paint is coated again after drying, and the coating is repeated for 3 times;

[0054] S7: Put the copper coil into the oven and bake at 200℃ for 4 hours;

[0055] S8: After baking, make a wooden mold according to the size of the copper coil and the thickness of the castable to be cast, and place the coil in the mold;

[0056] S9: Inject brown corundum castable into the mold and compact the castable with a vibrating rod;

[0057] S10: After the brown corundum castable is cast, it is naturally cooled and dried at a temperature of 20-30℃ for 5 days, and then the mold is removed;

[0058] S11: Inject structural adhesive into the countersunk hole of the long strip-shaped epoxy glass plate to fill the gap between the nut and the countersunk hole;

[0059] S12: Cover and fix the long strip-shaped epoxy glass plate with another epoxy glass cover plate on the outside;

[0060] S13: Paste the foam ceramic layer, graphite hard felt and graphite heating element on the inner surface of the brown corundum castable in order, and the foam ceramic layer, graphite hard felt and graphite heating element form a cylinder.

[0061] This step S13 can also be performed after S10, and then S11 is performed.

[0062] In addition, in step S1, the copper coil can be multiple groups.

[0063] In the prior art, iron molds are usually used, and when casting, iron rust in the mold may penetrate the castable, the induction coil will heat up when powered on, and the mixture of iron rust and castable will form a high-temperature eutectic, reducing the temperature resistance of the castable. The wooden mold used in the present application can overcome the above problems.

[0064] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An induction coil, characterized by: The copper coil (1), screw (2), bolt (3), a plurality of long strip-shaped epoxy glass plates (4), epoxy glass cover plate (5), brown corundum castable (6), foam ceramic layer (7), graphite hard felt (8), graphite heating element (9), Each turn of the copper coil is welded with a plurality of screws (2), and the positions of the screws of each turn are the same, so that the screws of the coil are aligned along the length direction of the coil; a plurality of countersunk holes are formed in the long strip-shaped epoxy glass plate, and each row of screws is located in the countersunk hole along the length direction of the coil, and the bolt is screwed with the screw, so as to fix the plurality of long strip-shaped epoxy glass plates and the copper coil; An epoxy glass cover plate (5) is arranged outside the plurality of long strip-shaped epoxy glass plates; The part of the coil which is not covered by the long strip-shaped epoxy glass plate is coated with ceramic paint, and the outside of the ceramic paint is provided with brown corundum castable; The inner side surface of the brown corundum castable is covered with a foam ceramic layer (7); the inner surface of the foam ceramic layer is covered with a graphite hard felt (8), and the inner surface of the graphite hard felt (8) is provided with a graphite heating element (9).

2. The induction coil of claim 1, wherein, Structural glue (10) is also filled between the countersunk hole and the bolt.

3. The induction coil of claim 2, wherein, The thickness of the brown corundum castable outside the coil is 10mm, and the thickness of the brown corundum castable inside the coil is 20mm.

4. The induction coil of claim 3, wherein, The copper coil is in multiple groups.

5. The induction coil of claim 1, wherein, The graphite hard felt (8) and the graphite heating element (9) are spliced into multiple segments, and recesses and protrusions that cooperate with each other are arranged between the segments.

6. The induction coil of claim 1, wherein, The thickness D of the graphite hard felt is 0.1*T-120, wherein T is the design requirement of high temperature resistance, and the range is 1400-4000℃, and the unit of the thickness of the graphite hard felt is millimeter.

7. The induction coil of claim 6, wherein, The graphite heating element (9) is a hollow cylinder with a thickness greater than 20mm.

8. A method of manufacturing an inductive coil, characterized by, The method comprises the following steps: S1: preparing a copper coil; S2: welding a plurality of screws on the outer periphery of each turn of the coil, and the positions of the screws of each turn are the same, so that the screws of the coil are aligned along the length direction of the coil; S3: preparing a plurality of long strip-shaped epoxy glass plates, and a plurality of countersunk holes are formed in the long strip-shaped epoxy glass plate along the length direction, and the pitch of the plurality of countersunk holes is consistent with the pitch of the screws arranged in the length direction of the coil; S4: installing the long strip-shaped epoxy glass plate outside the coil: the screws outside the coil pass through the countersunk holes of the long strip-shaped epoxy glass plate, and nuts are installed on the screws, so as to fix the coil and the long strip-shaped epoxy glass plate; S5: after the copper coil is fixed, it is put into a sandblasting chamber for iron sand treatment on the inner and outer surfaces of the copper coil; S6: coating the surface of the copper coil with insulation ceramic paint resistant to 600℃ high temperature: the thickness of a single coating is between 0.1-0.2mm, and after the ceramic paint is dried, it is coated again, and the process is repeated 3 times; S7: putting the copper coil into an oven and baking at 200℃ for 4 hours; S8: after baking, a wooden mold is made according to the size of the inductor coil and the thickness of the castable to be made, and the coil is placed in the mold; S9: injecting brown corundum castable into the mold and vibrating the castable with a vibrating rod; S10: after the brown corundum castable is made, it is naturally dried at a temperature of 20-30℃ for 5 days, and then the mold is removed. S11: injecting structural glue into the countersunk hole of the long strip-shaped epoxy glass plate to fill the gap between the nut and the countersunk hole; S12: covering and fixing the long strip-shaped epoxy glass plate with another epoxy glass cover plate outside; S13: sequentially attaching a foam ceramic layer, a graphite hard felt and a graphite heating body to the inner surface of the brown corundum castable, wherein the foam ceramic layer, the graphite hard felt and the graphite heating body form a cylinder.

9. The method of claim 8, wherein, The step S13 is performed between the steps S10 and S11.

10. The method of claim 8, wherein the copper coil is in multiple groups in step S1.

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