High-frequency induction heating device and induction heating coil for drying metal containers

Abstract

The present invention provides a high-frequency induction heating device and induction heating coil for drying metal containers, which can shorten the heating time. [Solution] The high-frequency induction heating device 1 for drying metal containers comprises induction heating coils 4 and 5 that heat a plurality of metal containers 2 placed on a pallet 3 from above and below. The upper induction heating coil 4 has two heating conductors 4a and 4b that heat the top surface 2a of the metal containers and two heating conductors 4c and 4d that heat both sides 2b and 2c of the metal containers, arranged parallel to the direction of arrangement of the metal containers 2. The lower induction heating coil 5 has a heating conductor 5a below the pallet 3 that heats the bottom surface 2d of the metal containers. The induction heating coil 4 for drying metal containers has a first heating conductor 4a and a second heating conductor 4b that heat the top surface of the metal containers and are arranged parallel to the direction of arrangement of the metal containers, and a third heating conductor 4c and a fourth heating conductor 4d that heat both sides of the metal containers and are arranged parallel to the direction of arrangement of the metal containers 2.

Description

Technical Field

[0004] , , ,

[0001] The present invention relates to a high-frequency induction heating device used for drying a metal container and an induction heating coil used in the device.

Background Art

[0002] It is well known to use a high-frequency induction heating device to dry a heated object (metal article) with water adhering thereto (see, for example, Patent Documents 1 to 3).

[0003] Patent Document 1 describes, "An induction heating device comprising: a conveying unit having an inlet and an outlet and a passage for conveying a metal piece between them; a heating coil wound along the longitudinal direction of the conveying unit; and a high-frequency power source for supplying a high-frequency current to the heating coil, wherein when the metal piece is conveyed in the passage by the action of gravity, the metal piece is induction-heated by the high-frequency magnetic field generated by the heating coil to evaporate and dry the water adhering to its surface." (Claim 1).

[0004] Patent Document 2 states, "(Example 1) As shown in Figures 1 and 2, the heating coil unit 1 has an electrically insulating material forming a groove-shaped space 2 with a substantially U-shaped cross-section for housing the object to be heated, and coil storage sections 3 are provided on the outer sides of both sides of this substantially U-shaped groove-shaped space 2, and a coil 4 is wound around it starting from a coil binding section 4a. A high-frequency current is supplied to the coil 4 from a commercial power supply 6 via an inverter device 5. The object to be heated 7 is placed on a conveying conveyor 8 in a magnetic metal tube and passes through the groove-shaped space." (Paragraph

[0014] ), "(Example 4) As shown in Figure 6, the heating coil The knit 1c is formed by arranging the coil 4 in the coil housing 3, and the exposed coil portion of the coil 4 other than the coil housing 3 is covered with an electrical insulating waterproof member 15. The other configurations are the same as in the above embodiment 1." (Paragraph

[0039] ) "To explain the operation of the above configuration, the purpose of heating the object to be heated 7 is to heat it after washing it with water and dry out the moisture, and in this case even if evaporated droplets are scattered on the exposed portion of the coil 4, they can be protected by the electrical insulating waterproof member 15, and the durability of the coil 4 can be improved." (Paragraph

[0031] )

[0005] Patent Document 3 describes "a method for drying a bottomed metal can, characterized by facing the opening of the bottomed metal can downwards and passing it through or holding it within a high-frequency induction heating device" (Claim 1), "the method for drying a bottomed metal can according to Claim 1, wherein the high-frequency induction heating device induces an electric current in the circumferential direction of the bottomed metal can" (Claim 2), and "the method for drying a bottomed metal can according to Claim 1 or 2, wherein the high-frequency induction heating device comprises a conveying means for continuously conveying the bottomed metal can, and a heating coil section comprising a pair of parallel coil sections extending along the conveying direction on both sides of the conveying path of the bottomed metal can, and a pair of connecting coil sections connecting the two parallel coil sections" (Claim 3). Furthermore, it states that "according to the present invention, by instantaneously heating the bottomed metal can itself with a high-frequency induction heating device, most of the moisture adhering to the surface of the bottomed metal can is easily turned into water droplets and discharged from the opening, and together with the evaporation of the moisture, the bottomed metal can can be dried in a short time."

[0006] In the induction heating apparatus described in Patent Documents 1 and 2, induction heating coils are provided above and below the object to be heated (such as a metal piece) to dry the object to be heated if moisture has adhered to it, but it is not shown that the upper and lower induction heating coils are controlled separately. On the other hand, high-frequency induction heating apparatuses that control the upper and lower induction heating coils separately are also known (see Patent Document 4).

[0007] Patent Document 4 states that "Conventionally, a high-frequency induction heating device of this type is known, having the configuration shown in Figure 2. In Figure 2, reference numeral 10 indicates a high-frequency power supply, and the high-frequency power supply 10 is connected to a heating coil 14 located above the object to be heated 16 via a resonant capacitor 12. Similarly, a high-frequency power supply 20 is connected to a heating coil 24 located below the object to be heated 16 via a resonant capacitor 22. ...In this way, a conventional high-frequency induction heating device consists of two independent sets of high-frequency power supplies 10, 20, resonant capacitors 12, 22 and heating coils 14, 24 located above and below the object to be heated 16, and each heating coil 14, 24 is connected to a high frequency By passing a high-frequency current, an alternating magnetic field is generated, and the object to be heated 16 placed within this alternating magnetic field is heated by eddy current losses due to electromagnetic induction. In the case of an object to be heated 16 that is asymmetrical in its upper and lower sections, the initial temperatures at which heating begins may differ. However, even in this case, conventional high-frequency induction heating devices can independently adjust the power input to the upper and lower heating coils 14 and 24 according to the shape and temperature distribution of the object to be heated 16. This type of surface heating, over a certain period of time according to the heat capacity of the object to be heated 16, results in a uniform temperature throughout the object due to heat transfer." (Page 1, right column, line 3 to Page 2, left column, line 12)

[0008] Furthermore, induction heating coils with specific structures are known for uniformly heating the object to be heated or for extending the lifespan of the induction heating coil (see Patent Documents 5 and 6).

[0009] Patent Document 5 describes "an induction heating coil for induction heating a planar portion of an object to be heated, characterized in that it has a plurality of parallel conductor portions, each facing the planar portion and through which current flows in the same direction" (Claim 1). It also states, "As described above, when an induction heating coil or a pancake-type induction heating coil is used to induction heat and rapidly cool a planar portion of an object to be heated, there is a risk that the hardness distribution may be uneven depending on the position of the planar portion" (Paragraph

[0004] ). "In view of the above circumstances, the present invention aims to provide an induction heating coil that can uniformly heat a planar portion of an object to be heated" (Paragraph

[0006] ).

[0010] Patent Document 6 describes a high-frequency heating coil body for heating one or more sides of a long workpiece that moves relative to a predetermined direction, comprising a plurality of heating conductors arranged opposite to the heating target region of the side, wherein the plurality of heating conductors are characterized in that the direction of the current is the same direction. (Claim 1) It also states that "the main object of the present invention is to provide a high-frequency heating coil body that can achieve a long lifespan without reducing production efficiency and while allowing for appropriate hardening depth." (Paragraph

[0010] ) [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2009-109070 [Patent Document 2] Japanese Patent Publication No. 2003-272824 [Patent Document 3] Japanese Patent Application Publication No. 9-129191 [Patent Document 4] Japanese Patent Application Publication No. 3-141578 [Patent Document 5] Japanese Patent Publication No. 2000-12205 [Patent Document 6] Japanese Patent Publication No. 2001-329313 [Overview of the project] [Problems that the invention aims to solve]

[0012] The high-frequency induction heating devices described in Patent Documents 1 and 2, used for drying metal articles with moisture adhering to them, are not designed for drying metal containers, and the upper and lower induction heating coils cannot be adjusted independently, resulting in the problem of difficulty in controlling the heating temperature. The high-frequency induction heating device described in Patent Document 3, used for drying metal cans with moisture adhering to them, has the problem of difficulty in controlling the heating temperature because the induction heating coil only heats the sides of the metal can.

[0013] The high-frequency induction heating apparatus described in Publication 4 is used for heating objects that are asymmetrical in their upper and lower dimensions, and its application to drying metal containers or heating multiple objects is not indicated. The induction heating coils described in Patent Documents 5 and 6 are for high-frequency induction hardening and are not shown to be for drying the workpiece.

[0014] In view of the above prior art, the object of the present invention is to provide a high-frequency induction heating apparatus and induction heating coil for drying multiple metal containers that can appropriately control the heating temperature and shorten the heating time. [Means for solving the problem]

[0015] To solve the above problems, the present invention employs the following means. (1) A high-frequency induction heating apparatus for drying metal containers, comprising induction heating coils for heating a plurality of metal containers placed on a pallet from above and below, wherein the upper induction heating coil has two heating conductors for heating the top surface of the metal containers and two heating conductors for heating both sides of the metal containers, each arranged parallel to the direction of arrangement of the metal containers, and the lower induction heating coil has a heating conductor below the pallet for heating the bottom surface of the metal containers. (2) The high-frequency induction heating device according to (1) above, wherein currents in the same direction flow through two heating conductor portions that heat the upper surface of the metal container. (3) The high-frequency induction heating device according to (1) or (2) above, wherein the lower induction heating coil has heating conductor portions arranged in a zigzag pattern. (4) The high-frequency induction heating device according to any one of (1) to (3) above, wherein the upper induction heating coil and the lower induction heating coil can be adjusted independently. (5) An induction heating coil for drying a metal container, including a first heating conductor portion and a second heating conductor portion parallel to each other along the arrangement direction of the metal container that heats the upper surface of the metal container, a third heating conductor portion and a fourth heating conductor portion parallel to each other along the arrangement direction of the metal container that heats both side surfaces of the metal container, a first connection conductor portion that connects the two at the rear end of the first heating conductor portion and the front end of the third heating conductor portion, a second connection conductor portion that connects the two at the rear end of the third heating conductor portion and the front end of the second heating conductor portion, and a third connection conductor portion that connects the two at the rear end of the second heating conductor portion and the front end of the fourth heating conductor portion. Note that, when viewed from the direction of the current flow, the front end is the location where the current flows forward, and the rear end is the location where the current flows backward.

Advantages of the Invention

[0016] By using the high-frequency induction heating device and the induction heating coil of the present invention, when drying a metal container, it is possible to appropriately control the heating temperature and shorten the heating time.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a schematic diagram showing a high-frequency induction heating device and an upper induction heating coil according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the lower induction heating coil 5 as viewed from the A direction in FIG. 1. [Figure 3] FIG. 3 is a plan view showing the positional relationship between the side surface 2c of the metal container 2 and the heating conductor portion 4d as viewed from the B direction in FIG. 1.

Best Mode for Carrying Out the Invention

[0018] A high-frequency induction heating device and an induction heating coil according to an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described with reference to FIGS. 1, 2, and 3.

[0019] As shown in FIGS. 1, 2, and 3, the high-frequency induction heating device 1 for drying the metal container 2 according to this embodiment includes induction heating coils 4 and 5 that heat a plurality of metal containers 2 placed on the pallet 3 from above and below. The upper induction heating coil 4 has two heating conductor parts 4a and 4b that heat the upper surface 2a of the metal container 2 and two heating conductor parts 4c and 4d that heat both side surfaces 2b and 2c of the metal container 2, which are arranged in parallel along the arrangement direction of the metal container 2, respectively. The lower induction heating coil 5 is a high-frequency induction heating device that has a heating conductor part 5a that heats the bottom surface 2d of the metal container 2 under the pallet 3.

[0020] The lower induction heating coil 5 may be a serpentine type (see FIG. 2) arranged in a normal zigzag. In the high-frequency induction heating device of this embodiment, the output of the lower dielectric heating coil 5 is larger than the output of the upper induction heating coil 4.

[0021] It is preferable that the upper induction heating coil 4 and the lower induction heating coil 5 can be adjusted independently. By adjusting independently, it becomes easier to control the target temperature reaching time.

[0022] As shown in Figure 1, the induction heating coil 4 for drying the metal container 2 according to this embodiment is an induction heating coil having a first heating conductor portion 4a and a second heating conductor portion 4b that are parallel to the arrangement direction of the metal container 2 and heat the upper surface 2a of the metal container 2, a third heating conductor portion 4c and a fourth heating conductor portion 4d that are parallel to the arrangement direction of the metal container 2 and heat both sides 2b and 2c of the metal container 2, a substantially U-shaped first connecting conductor portion 4(a) that connects the rear end of the first heating conductor portion 4a and the front end of the third heating conductor portion 4c, a substantially L-shaped second connecting conductor portion 4(b) that connects the rear end of the third heating conductor portion 4c and the front end of the second heating conductor portion 4b, and a substantially L-shaped third connecting conductor portion 4(c) that connects the rear end of the second heating conductor portion 4b and the front end of the fourth heating conductor portion 4d. The front end of the first heating conductor section 4a is connected to the power supply conductor section 4x, and the rear end of the fourth conductor section 4d is connected to the power supply conductor section 4y.

[0023] Figure 2 illustrates the flow of current (→). The current flows from the power supply conductor section 4x to the first heating conductor section 4a, from right to left through the first heating conductor section 4a, from the first heating conductor section 4a to the first connecting conductor section 4(a), from the first connecting conductor section 4(a) to the third heating conductor section 4c, from the third heating conductor section 4c to the second connecting conductor section 4(b), from the second connecting conductor section 4(b) to the second heating conductor section 4b, from right to left through the second heating conductor section 4b, from the second heating conductor section 4b to the third connecting conductor section 4(c), from the third connecting conductor section 4(c) to the fourth heating conductor section 4d, and from the fourth heating conductor section 4d to the power supply conductor section 4y. In other words, as shown in Figure 2, the current flow in the first heating conductor section 4a is from right to left, and the current flow in the second heating conductor section 4b is also from right to left. Therefore, current flows simultaneously in the same direction in both the first heating conductor section 4a and the second heating conductor section 4b that heat the upper surface 2a of the metal container 2. Consequently, the alternating magnetic fluxes generated by these currents do not cancel each other out, and the upper surface 2a of the metal container 2 can be heated uniformly.

[0024] The above-mentioned power supply conductor section 4x is connected to a high-frequency power supply via a lead, and the above-mentioned power supply conductor section 4y is also connected to a high-frequency power supply via a lead (not shown). In the high-frequency induction heating apparatus of this embodiment, the high-frequency is, for example, 1 to 200 kHz. The current can be set appropriately according to the heating temperature.

[0025] Cooling water is circulated inside the upper induction heating coil 4 and the lower induction heating element 5 to provide cooling.

[0026] The material of the metal container 2 is not limited to conductive materials, but aluminum, iron, etc., can be used. To dry the metal container 2 and completely remove all moisture, the target temperature is preferably 100°C or higher. If the metal container 2 is made of metal only, there is no upper limit to the drying temperature. However, if there is plastic inside the metal container, for example, if there is PP film inside an aluminum casing, it is preferable to set the upper limit to around 130°C.

[0027] The number of metal containers 2 placed on the pallet 3 can be multiple, but it is preferable to have as many as possible in order to improve drying efficiency. For example, the number of metal containers 2 placed on the pallet 3 can be 10 to 20. The pallet is preferably made of aluminum, but may also be composited with plastic that can withstand temperatures above 100°C.

[0028] Furthermore, when heating is performed using only induction heating coils that heat from below or only induction heating coils that heat from above, it takes time for all of the multiple installed metal containers to reach 100°C or higher (preferably 102°C or higher). However, when both the upper and lower induction heating coils are used in combination, the time it takes for all the metal containers to reach 100°C or higher (preferably 102°C or higher) can be shortened. Therefore, using both in combination has the effect of shortening the time required to reach the target temperature. [Industrial applicability]

[0029] The high-frequency induction heating device and induction heating coil of the present invention enable rapid drying of metal containers and efficiently remove moisture from metal containers (aluminum housings) used in various applications, thus offering high industrial applicability. [Explanation of Symbols]

[0030] 1. High-frequency induction heating device 2 metal container 2a Top surface of the metal container 2b Side of the metal container 2c Side of metal container 2d Bottom of a metal container 3 Palettes 4. Upper induction heating coil 4a First heating conductor section 4b Second heating conductor section 4c Third heating conductor section 4d Fourth heating conductor section 4(a) First connecting conductor section 4(b) Second connecting conductor section 4(c) Third connecting conductor section 5. Lower induction heating coil 5a Heating conductor section

Claims

1. A high-frequency induction heating apparatus for drying metal containers, comprising induction heating coils for heating a plurality of metal containers placed on a pallet from above and below, wherein the upper induction heating coil has two heating conductors for heating the top surface of the metal containers and two heating conductors for heating both sides of the metal containers, each arranged parallel to the direction of arrangement of the metal containers, and the lower induction heating coil has a heating conductor below the pallet for heating the bottom surface of the metal containers.

2. The high-frequency induction heating apparatus according to claim 1, wherein a current flows in the same direction through the two heating conductors that heat the upper surface of the metal container.

3. The lower induction heating coil has heating conductors arranged in a zigzag pattern, according to claim 1, in the high-frequency induction heating apparatus.

4. The high-frequency induction heating apparatus according to any one of claims 1 to 3, wherein the upper induction heating coil and the lower induction heating coil can each be adjusted independently.

5. An induction heating coil for drying metal containers, comprising: a first heating conductor portion and a second heating conductor portion parallel to the arrangement direction of the metal containers for heating the upper surface of the metal containers; a third heating conductor portion and a fourth heating conductor portion parallel to the arrangement direction of the metal containers for heating both sides of the metal containers; a first connecting conductor portion connecting the rear end of the first heating conductor portion and the front end of the third heating conductor portion; a second connecting conductor portion connecting the rear end of the third heating conductor portion and the front end of the second heating conductor portion; and a third connecting conductor portion connecting the rear end of the second heating conductor portion and the front end of the fourth heating conductor portion.

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