JP2002050464A - Cooling structure of induction heating furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-cooled heat insulation structure of an induction heating furnace in which the temperature of an induction heating coil is made to be kept in a low-temperature as far as possible by installing a water-cooled heat insulation layer between an electromagnetic induction heating furnace and the induction heating coil. SOLUTION: A heat-resistant heat insulating material layer 5 is installed at an outside of a furnace body 2, and the water-cooled heat insulation layer consisting of water-cooled tubes 7 is formed between the heat insulating material layer 5 and the induction heating coil 11, and the water-cooled tubes 7 are made of metal tubes and pipes which are connected with a cooling water inlet 8 and a cooling water outlet 9 of the water-cooled tubes 7 are made of rubber or resin, and an electrically closed circuit is made not to be formed by the metal part of the water-cooled tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure of an electromagnetic induction heating furnace, and more particularly, to a cooling structure of the electromagnetic induction heating furnace which can be advantageously applied to, for example, an induction heating coil having low heat resistance. It is about structure.

[0002]

2. Description of the Related Art Electromagnetic induction heating furnaces have been increasingly used as heating furnaces for relatively small parts because of their rapid heating, miniaturization and automation of equipment, and high temperature control accuracy. .

As is well known, in an induction heating furnace, when a metal such as iron is inserted into a coil connected to an AC power supply, the magnetic flux is converged on the metal, the leakage magnetic flux is extremely reduced, and the coil is separated from the metal. In spite of the fact that the metal is heated from the surface, the furnace body is generally made of a cylindrical high temperature heat-resistant material in order to allow the metal to be heated to pass through the inside of the coil. Further, the induction heating coil is usually arranged in plural numbers in the axial direction of the cylindrical body to facilitate the heating control, and to perform electromagnetic shielding so that the heating only heats the metal in the coil.

[0004]

By the way, the induction heating coil has conventionally been made of a rectangular copper tube, and the inside of the tube has been used as a cooling water passage to prevent power loss due to heating. However, such an induction heating coil has a problem in that coil current is large because current flows unevenly to the furnace side.

Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-283269, an induction heating coil using a conductor obtained by twisting a plurality of insulating coating conductors having a diameter of about 0.1 to 0.3 mm is disclosed in Japanese Patent Laid-Open No. 9-283269. The diameter of the conductive wire is sufficiently smaller than the current penetration depth, thereby eliminating coil loss, preventing induction heating by magnetic flux of another layer, and improving cooling efficiency.

In the induction heating coil disclosed in Japanese Patent Application Laid-Open No. Hei 6-28928, a wire conductor is wound around a spring to reduce a potential drop between the power supply of the induction heating furnace and the heating coil. An induction heating coil in which a spring is arranged on the outside of the inner cylinder, and a wire conductor similar to that described above is wound around the spring to form an outer cylinder, and cooling water flows inside each spring. Has been proposed.

[0007] These heating coils can reduce coil loss as much as possible by using the thin wire covered with insulation, and can provide high performance in terms of cooling efficiency, insulation resistance, and the like. However, it is difficult to achieve an induction heating coil having high performance with a high heat-resistant material. Also, when the outside temperature is high, the cooling capacity is limited, so that the water temperature at the cooling water outlet side rises, and problems such as an increase in coil loss at the cooling water outlet side were also recognized.

The present invention has been made in view of the above problems, and has been made to select a material which is excellent in electrical insulation, watertightness, lowering of the conductor temperature and workability in winding on a coil of the conductor. Provide a water-cooled insulation structure of the induction heating furnace between the electromagnetic induction heating furnace and the induction heating coil, which does not adversely affect the furnace temperature and keeps the temperature of the induction heating coil as low as possible. It is intended to be.

[0009]

According to the present invention, there is provided a cooling structure for an induction heating furnace in which a water-cooled heat insulating layer is provided between a furnace body of an electromagnetic induction heating furnace and an induction heating coil. Things.

When the temperature of the cooling water rises when the water-cooled heat-insulating layer is exposed to high heat, the outer skin temperature of the induction heating coil rises accordingly. Therefore, in the present invention, it is preferable to provide a heat-resistant heat insulating material layer between the furnace body and the water-cooled heat insulating layer. The heat-resistant heat insulating material that can be used is not particularly limited, and for example, ceramic fiber or the like can be used.

[0011] The water-cooled heat-insulating layer is formed by a metal water-cooled pipe arranged at a predetermined interval, and a pipe connected to a cooling water inlet and an outlet of the water-cooled pipe is formed by an electric insulator. It is preferable to suppress the occurrence of power loss due to the induced current by preventing a circuit from being formed. Further, the space between the water cooling tubes can be left as an air gap. The electrically insulating material can be appropriately selected from conventionally used materials such as synthetic rubber and silicone rubber, and the length of the water-cooled tube is made longer than the length of the furnace body. May be arranged in a direction along the axis of the furnace body, and may be folded back at the end of the furnace body for piping.Furthermore, the periphery of the furnace body may be divided into a plurality of sections, and the water cooling pipe may be arranged for each section. it can.

The induction heating coil used in the present invention is not particularly limited. For example, the induction heating coil includes a conductive wire and a cooling water channel formed in a conduit, and the conductive wire has a diameter larger than a current penetration depth determined by a frequency. It consists of twisted or knitted multiple strands of small insulated conductive wire,
The cooling water channel uses a hollow portion in which a spring in which a metal wire such as a copper wire is spirally wound is arranged in a conduit, and the conduit can be formed of a flexible and electrically insulating material. The conductive wire may be spirally wound around the spring as a winding core.

Further, a fiber reinforced and flexible tape is wrapped around the conduit so as to enhance the pressure resistance against the water pressure in the conduit, so that the material forming the conduit has a heat-shrinkable resin having electrical insulation properties. Can be used to improve workability in forming a conduit.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cooling structure of an induction heating furnace according to the present invention will be described below with reference to the accompanying drawings.

The electromagnetic induction heating furnace 1 used in the present embodiment shown in FIG. 1 has a cylindrical furnace body 2 made of a refractory material such as alumina and is inserted into an insulator 3 around the outer periphery of the furnace body 2. The heating wire 4 for heat insulation is helically arranged with electrical insulation between them, and a ceramic tape 10 '(FIG. 2) is wrapped around the heating wire 4; The heat-resistant material layer 5 was formed, and a heat-resistant tape heat-insulating layer 6 (FIG. 2) made of ceramic fiber or the like was wound around the layer 5 to form a furnace body.

Water cooling tubes 7 were arranged at equal intervals around the furnace body to form a water cooling heat insulating layer, and a ceramic tape 10 was wound around the outside thereof to form a water cooling heat insulating layer. The space between the adjacent water cooling tubes 7 was left as an air gap. Next, an induction heating coil 11 was provided outside the water-cooled heat insulating layer. Reference numeral 12 shown by a two-dot chain line in FIG. 1 is a billet as a heated object. Table 1 below illustrates the thickness of each member used in the present embodiment.

[0017]

[Table 1]

The water cooling tube 7 of the present embodiment shown in FIG. 2 has a furnace body divided into four parts in the circumferential direction, and has four water cooling tubes 7-1 to 7-4 (7-2).
7-3 are not shown) in each section. In addition,
The water cooling tube is generally denoted by reference numeral 7.

As shown in FIG. 2, each of the water cooling pipes 7-1 to 7-4 has a zigzag shape which is folded back and forth twice, and ends of a cooling water inlet 8 and a cooling water outlet 9 are bent at both ends of the coil. And a rubber hose for cooling water supply / drainage (both not shown) to supply / drain the cooling water.

The cooling structure of the present embodiment described above
It is formed by a water-cooled heat-insulating layer in which 16 water-cooling tubes 7 are conveniently arranged around the furnace body (the distance between the water-cooling tubes 7 in the present embodiment is about 16 mm). Table 2 shows the specifications of the water cooling structure.
In this embodiment, as shown in Table 2, the water cooling pipe 7
Two cases, book and 16 were performed.

[0021]

[Table 2]

The effect of the water-cooled heat-insulating layer formed as described above is shown in Table 3 when the billet 12 is at a temperature of 1250 ° C.

[0023]

[Table 3]

From the results shown in Table 3, when the water-cooled heat-insulating layer was provided, the temperature at the inside of the water-cooled heat-insulating layer was less than that when the water-cooled heat insulating layer was not provided.
It can be seen that the position in the furnace body 2 where the temperature is lowered by at least 00 ° C. and becomes 1000 ° C. is almost the same.

Therefore, it was found that the water-cooled heat-insulating layer of the present embodiment can reduce the temperature of the induction heating coil 11 to 300 ° C. or less without affecting the temperature of the billet 12. Therefore, a resin or the like for obtaining an induction heating coil 11 having a bundle of thin electric wires to reduce coil loss and having high watertightness, cooling efficiency, insulation resistance, and excellent workability of forming the coil. The range of choice of organic materials was greatly expanded.

Next, the details of the induction heating furnace coil 11 used in the present embodiment will be described with reference to FIGS.
That is, the induction heating coil 11 (hereinafter simply referred to as a coil)
An inner winding coil 11-1 and an outer winding coil 11-2 are formed double by spirally winding (not shown) a conductive tube 15 outside the furnace body 2.

As shown in FIGS. 3 and 4, the conductive tube 15 comprises a core 16, a conductive layer comprising a conductive wire bundle 17 and an outer cover, and the inside of the core 16 is a cooling water passage 18 in the coil.
The winding core 16 is provided with a metal wire 19 (in the present embodiment, a diameter of 0.9).
mm of copper wire) is spirally and densely wound in a spiral shape. A cooling water passage 18 in the coil is secured inside (constituting the center of the conductive tube 15), and the shape of the conductive layer Workability during holding and coil formation is facilitated. Reference numeral 10 'shown in FIG. 3 is a ceramic tape.

The outer skin is covered with a highly insulating heat-shrinkable rubber tube 20 around the conductive layer, and the outside thereof is wrapped with a fiber-reinforced plastic tape 21 to increase the mechanical strength of the heat-shrinkable rubber tube 20 and to provide cooling water. It was made to withstand water pressure. A heat-shrinkable silicone rubber is used for the heat-shrinkable rubber tube 20, and a glass cloth reinforced silicone tape using an unvulcanized silicone rubber is used for the fiber-reinforced plastic tape 21 at 19.6 Pa (2 kgf / kg).
cm ²⁾ Water pressure resistance.

The conductive wire bundle 17 is formed by twisting or knitting a plurality of twisted wires obtained by twisting a plurality of strands of an insulated copper wire coated with urethane resin. The plurality of conductive wire bundles 17 thus obtained are
To form a conductive layer.

Table 1 shows the specifications of the element wire, twist, conductive wire bundle 17 and coil 11 used in the present embodiment. However, the present invention is not limited to the data shown in Table 1. The wires in the conductive wire bundle 17 were twisted or knitted so that the distance between the wires with respect to the axis C was always changed, thereby preventing the current from being biased between the wires.

[0031]

[Table 4]

Notes: 1. “Constitution of conductive layer” in Table 4 is “the number of conductive wire bundles 17 / the number of twisted strands / the number of strands of strands”. 2. A comparison was made between the power loss of the wire of 0.1 mm and the power loss of 0.3 mm shown in Table 1. As a result, there was no difference between the two.
An m-diameter wire was used. 3. FIG. 3 shows a case where the present invention is implemented by using the B coil. In the case where the embodiment is implemented by using the A coil, the same as FIG. 3 except that the number of conductive wire bundles 17 arranged around the winding core 16 is increased to twelve. The configuration was adopted.

As can be understood from FIG. 3 and Table 4, in the conductive layer, the arrangement of the twisted wires can be made denser in the B coil in which the thickness of the conductive wire bundle 17 is reduced.

Next, before describing the coil 11, an outline of the induction heating furnace will be described with reference to FIG. The coil 11 is shown in FIG.
As shown in FIG. 2, the conductive tube 15 is spirally and densely wound around the surface of the furnace body 2 to form an inner winding coil 11-1, and a spiral concave groove formed between the wound conductive tubes 15 is formed. The conductive tube 15 is wound around the strip 23 to form an outer winding coil 11-2 to form a double coil. This not only improves the winding workability of the outer coil 11-1 but also improves the contact point p between the inner coil 11-1 and the outer coil 11-2, as understood from the coil sectional view of FIG. , Q (when the conductive tube 15 is densely wound, a contact s is further added), and the coil itself can hold the position.

As shown in the electric circuit connection system diagram of FIG. 5, the coil 11 of this embodiment
Heating control was facilitated by dividing into three blocks of o.3. The coil 11 of No. 3 has the same structure as that shown in FIG. The reason why the coil 11 of No. 3 is made into a single winding is for practical reasons and has no essential meaning for the present invention. Table 5 shows the specifications of the No. 1 and Mo. 2 coils 11.

[0036]

[Table 5]

Next, the electrical connection method of No. 1 to No. 3 will be described with reference to FIG. The No.1, No.2 and No.2 double coils 11 are divided into two parts at the center of the coil, and the inner half of the first half
11-1 and outer coil 11-2, and outer 11-2 and inner coil
11-1 were connected in series, and those connected in series were connected in parallel. The single coil No. 3 coil (same shape as the inner coil 11-1) was divided into two at the center of the coil and connected in parallel to the power supply.

The coils 11 of No. 1 to No. 3 connected as described above were connected in parallel to the power source E. Like this
The bias of the current between the inner winding coil 11-1 and the outer winding coil 11-2 of No. 1 to No. 3 was eliminated. Reference numeral 24 shown in FIG. 6 denotes a connection piece for internal / external transposition for connecting the inner winding coil 11-1 and the outer winding coil 11-2, and 25 denotes a coil terminal.

The coil 11 for an electromagnetic induction heating furnace according to the second embodiment shown in FIG. 6 is obtained by winding the outer coil 11-2 in reverse to the inner coil 11-1. By doing so, the bias of the coil current can be eliminated. In this case, unlike the coil 11 for the electromagnetic induction heating furnace of the first embodiment, the outer winding coil 11-2 is placed on the inner winding coil 11-1. I will get on. Therefore, the effect of stabilizing the coil position as shown in FIG. 3 cannot be obtained, and a process such as hardening the coil 11 with a resin to maintain the position of the coil is required, and the coil diameter is increased. However, the second embodiment has the configuration of the present invention and should not be interpreted as not belonging to the present invention.

The heat-shrinkable rubber tube 20 has the function of improving the workability for water-tight coating of the cooling water and the effect of increasing the volume of the conductive layer shown in the entirety of the conductive tube 15. It works so that a sufficient strength for ensuring the water pressure resistance required for effectively flowing the cooling water can be realized with a smaller thickness.

In each of the embodiments described above, the conductive tube is used.
15 has double winding and reduced coil loss.
The present invention is not limited to this, and may be implemented with another number of turns, for example, a single turn.

[0042]

The water-cooling insulation structure of the induction heating furnace according to the present invention described above eliminates the effect of the water-cooling insulation layer on the temperature inside the furnace by the water-cooling insulation layer formed outside the induction heating furnace, and Since the induction heating coil is cut off from the high temperature, it is possible to greatly improve the selection range of materials for forming the induction heating coil. Therefore, watertightness, cooling efficiency and insulation resistance all have high performance,
In addition, the effect of greatly expanding the selection range of various materials for obtaining an induction heating coil excellent in workability when winding the coil and the effect of preventing unnecessary power consumption (coil loss) can be obtained. .

[Brief description of the drawings]

FIG. 1 is a sectional view of an induction heating furnace according to an embodiment of the present invention.

FIG. 2 is a perspective view of the water cooling pipe shown in FIG.

FIG. 3 is a half cross-sectional view of a main part of an induction heating furnace equipped with an induction heating furnace coil according to an embodiment of the present invention.

FIG. 4 is a partially cutaway perspective view for explaining the structure of the conductive tube shown in FIG. 3;

5 is a diagram illustrating a configuration of an induction heating furnace coil applied to the induction heating furnace of FIG. 3 and a system of an electric circuit when connected to a power supply.

6 is a half sectional view of a main part of an induction heating furnace equipped with an induction heating furnace coil according to a modification of the embodiment shown in FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electromagnetic induction heating furnace 2 furnace body 5 heat-resistant material layer 7 water cooling tube 8 cooling water inlet 9 cooling water outlet 11 induction heating coil

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Takahiro Ao 3-1-1, Tamano, Tamano-shi, Okayama Prefecture Mitsui Engineering & Shipbuilding Co., Ltd. (72) Ryuichi Kasaishi 3-1-1, Tamano-shi, Tamano-shi, Okayama Prefecture Mitsui Engineering & Shipbuilding Co., Ltd. Tamano Works F-term (reference) 3K059 AA10 AB15 AB25 AC09 AD03 AD07 AD34 AD40 CD44 CD48 CD52 CD73 CD74 CD77 CD79 4K063 BA02 BA03 CA06 EA01 FA34 FA39

Claims (7)

[Claims] 1. A cooling structure for an induction heating furnace having a water-cooled heat-insulating layer provided between a furnace body of an electromagnetic induction heating furnace and an induction heating coil. 2. The cooling structure for an induction heating furnace according to claim 1, wherein a heat-resistant heat insulating material layer is provided between said furnace body and said water-cooled heat insulating layer. 3. The water-cooled heat-insulating layer is formed by a metal water-cooled pipe arranged at a predetermined interval, and a pipe connected to a cooling water inlet and an outlet of the water-cooled pipe is formed by an electric insulator. 3. The cooling structure for an induction heating furnace according to claim 1, wherein a closed circuit is not formed. 4. The furnace according to claim 1, wherein a length of said water cooling tube is longer than a length of said furnace body, and is arranged in a direction along an axis of said furnace body. 3. The cooling structure of the induction heating furnace according to 3. 5. The cooling structure for an induction heating furnace according to claim 4, wherein the periphery of said furnace body is divided into a plurality of sections, and said water cooling pipe is arranged for each section. 6. The coil includes a conductive wire and a cooling water channel formed in a conduit, and the conductive wire includes a plurality of strands formed of an insulated conductive wire having a diameter smaller than a current penetration depth determined by a frequency. 5. A cooling water passage formed by twisting or knitting, wherein the cooling water passage comprises a cavity in which a spring is disposed in the conduit, and the conduit is formed of a flexible and electrically insulating material. Or the cooling structure of the induction heating furnace as described in 5. 7. The cooling structure of an induction heating furnace according to claim 6, wherein a fiber reinforced and flexible tape is wrapped around said conduit to enhance pressure resistance against water pressure in said conduit.