JP5734707B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating device used for a work for removing a distortion of a welded part and other heating work in a process of manufacturing a metal structure such as a ship.

Steel structures such as ships have many parts that can be assembled by welding steel sheets, but the welded parts are distorted, so usually the welded parts are heated and cooled after the welding and assembly are finished. The work which removes distortion is performed.
This distortion occurs when the welded portion shrinks and deforms due to welding heat, but can be removed by shrinking and correcting the opposite side of the steel plate. Further, distortion caused by dimensional deviation or slack due to the structure can be removed by heating the steel sheet and then shrinking it to adjust the dimensions.

  In a conventional strain relief operation, a method is employed in which an operator holds a gas torch in his hand and heats it while moving along the welded portion. However, since the method by gas heating is surface heating, temperature unevenness is likely to occur, and since a high degree of skill is required for the work, in recent years when the shortage of skilled workers has become noticeable, the adoption has decreased. Heating by an induction heating device is performed.

  As a conventional high-frequency induction heating device, for example, the applicant of the present application first discloses a strain relief heating device that can raise the temperature of an object to be heated in a short time and can automate the heating operation. As suggested.

  The strain relief heating device includes an amplifying transformer and an induction heating coil mounted on a traveling carriage, the traveling carriage is provided with drive wheels and auxiliary wheels driven by a motor, and can travel along a guide rail during heating work. It is.

  In Patent Document 2, a high-frequency current from a power source is amplified by an amplifying transformer and energized in a heating coil disposed close to the surface of the steel material, and heat generation due to an induced current occurs in the steel material. A heating device configured to remove distortion caused by deformation of the steel material by heating the deformed portion facing the heating coil and the vicinity thereof, and the heating device mounted so as to be movable on the steel material are mounted. In a steel material strain relief device having a traveling carriage, the carriage body supporting the traveling wheels of the traveling carriage can be moved up and down independently of the carriage body and can move the surface of the steel material independently from the power supply. An amplifying transformer that amplifies the current and supplies the heating coil, a supporting member that supports the heating coil, and a heating coil gap that holds the gap between the heating coil and the surface of the steel material in a predetermined gap via the supporting member. The heating coil gap adjusting mechanism is interposed between the support member and the carriage main body and biased in a direction to bring the support member into contact with the surface of the steel material, and exerts a magnetic action on the traveling wheel. The wheel is always in contact with the surface of the steel plate by the magnetic force due to the pressing action from the back of the spring by the wheel through the cart body and the pressing action of the internal support member to the steel plate surface through the guide roller by the spring. However, a steel material strain relief device is described that is configured to roll while traveling the traveling carriage so that the height position of the support member from the steel surface is constant via the carriage body.

  Furthermore, Patent Document 3 filed by the applicant of the present application discloses an amplifying transformer that amplifies and outputs an input high-frequency current to a traveling carriage that can be driven by wheels, and an alternating magnetic field generated by the high-frequency current supplied from the amplifying transformer. In an induction heating device that heats a surface to be heated of a plate metal by inducing an eddy current in the plate metal by an alternating magnetic field generated by the heating coil, the heating coil itself is insulated Discloses an induction heating apparatus configured to contact a surface to be heated.

Japanese Patent Laid-Open No. 11-170081 Japanese Patent No. 4015481 JP 2009-242823 A

  In the strain relief heating apparatus described in Patent Document 1 described above, there is a predetermined gap between the induction heating coil and the steel plate that is the object to be heated, and thus there is a problem that the heating efficiency is poor depending on the distance of the gap. . In addition, if there is a deformation such as undulation on the surface of the steel sheet that is the object to be heated, there is a problem in that the amount of heat input to the target steel sheet surface varies.

  In the strain relief device described in Patent Document 2, a guide roller provided on a support member that supports a heating coil is pressed against the surface of the steel plate using a spring, whereby the heating coil and the steel plate are deformed by deformation of the steel plate. However, it cannot cope with irregularities and undulations with dimensions smaller than the pitch of the guide roller. Therefore, if the diameter of the guide roller is made too small, the travel of the traveling carriage will be hindered, so there is a limit to reducing the diameter of the guide roller. In particular, in the case of thin plate heating, the surface to be heated expands and deforms at the moment of heating, and becomes a concave or convex state in a narrow region, making constant heating difficult.

  The induction heating device described in the above-mentioned Patent Document 3 is configured such that the heating coil itself is in an insulating state, for example, in contact with the surface to be heated via an insulating coating or an insulating sheet, so that various unevenness of the object to be heated is obtained. Since the distance between the heating coil and the object to be heated is also kept constant, the insulation coating and the insulating sheet are inevitably worn away. If worn, the heating coil directly contacts the object to be heated and short-circuits. Because of the danger, it is necessary to check the wear state, rework the insulation coating, and replace the insulation sheet.

  Therefore, the present invention maintains the heating temperature condition while traveling and moving with high power efficiency by keeping the distance between the heating coil and the object to be heated in a non-contact and constant manner even for various irregularities and undulations of the object to be heated. An object of the present invention is to provide an induction heating apparatus that can perform the above-described process.

In order to solve the above-mentioned problems, an induction heating apparatus according to the present invention has an amplifying transformer that amplifies and outputs an input high-frequency current to a traveling carriage that can be driven by wheels, and an alternating current using the high-frequency current supplied from the amplification transformer. A heating coil that generates a magnetic field, and an induction heating device that heats a surface to be heated of the plate metal by inducing an eddy current in the plate metal by an alternating magnetic field generated by the heating coil. The heating coil is formed in a plate shape at the lower end of a movable frame that has two opposite sides across the center line in the width direction of the traveling carriage, and supports the heating coil so as to be movable up and down with respect to the traveling carriage. to maintain a constant small distance spaced state from the metal, at least one rotatable ball, the U-shaped heat co even on the width direction of the center line of the traveling carriage Characterized in that provided on Le opposing two sides of the center line.

  The induction heating efficiency is inversely proportional to the square of the distance between the heating coil and the heated surface, and the induction heating efficiency becomes extremely small as the gap increases. The plate-like metal is uneven due to thermal expansion caused by heating. There are also deformations and swells even before heating. Therefore, in the present invention, the vertical position of the heating coil is held at the distance between the heating coil and the ball so that the distance between the heating coil and the surface to be heated is kept at a constant minute distance even during continuous running. Therefore, heating is stable and induction heating efficiency can be increased. It is a requirement that at least one ball is provided, but two or three balls may be provided close to each other.

  The rotatable ball is preferably made of a nonmagnetic material, a heat resistant material, and a wear resistant material. In order to withstand the fact that an alternating magnetic field is generated by applying a high-frequency current to the heating coil, the plate-like metal that is the object to be heated is heated, and the ball is worn out by contact with the plate-like metal. Non-magnetic material, heat resistance, wear resistance.

  Further, by supplying a lubricating liquid to a ball receiver that rotatably supports the ball, the ball can be smoothly rotated and friction can be reduced.

  According to the present invention, at least one rotation for holding the heating coil at a certain small distance from the metal plate at the lower end of the movable frame that supports the heating coil so as to be movable up and down with respect to the traveling carriage. By providing a free ball and holding the vertical position of the heating coil at the distance between the heating coil and the ball, the distance between the heating coil and the surface to be heated can be held at a constant minute distance even during continuous running. Therefore, the heating is stable and the induction heating efficiency can be increased.

The induction heating apparatus which concerns on embodiment of this invention is shown, (a) is a side view, (b) is a rear view. The structure around the heating coil in the induction heating apparatus which concerns on embodiment of this invention is shown, (a) is a side view, (b) is a front view, (c) is a bottom view.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a traveling carriage 1 that constitutes the induction heating device according to the embodiment of the present invention can travel by drive wheels 2 and auxiliary wheels 3. The drive wheel 2 can be driven by a drive motor 4. The traveling carriage 1 can be moved by holding the handle 5 by hand and pushing and pulling it in the front-rear direction. A clutch mechanism (not shown) is mounted between the drive wheel 2 and the drive motor 4.

  A movable frame 8 is attached to the support 6 fixed to the traveling carriage 1 so as to be movable up and down by a lifting metal fitting 7 using a spring, a damper or the like. The movable frame 8 has an amplification transformer 9 and a U-shape. A heating coil 10 is mounted. A ball 11 is provided at the lower end of the movable frame 8 to hold the height between the heating coil 10 and the metal plate to be heated at a fixed minute distance.

  The details around the heating coil 10 will be described with reference to FIG. A fixing plate 12 fixed to the bottom of the movable frame 8 is fixed with a fixing metal 14 for fixing the heating coil 10 and a current-carrying conductor 13 for supplying a high-frequency current to the heating coil 10. A mounting bracket 15 is attached by screws 16. Ferrite cores 17 are provided on both sides of the heating coil 10 for concentrating the alternating magnetic field induced by the heating coil 10 on the material to be heated to improve induction heating efficiency.

  A cylindrical ball receiver 18 in which the ball 11 is rotatably accommodated is fixed to the lower end of the mounting bracket 15, and an adjustment screw 19 for adjusting the downward projecting length of the ball 11 is provided. In the present embodiment, the protrusion length of the ball 11 from the lower surface of the heating coil 10 can be adjusted within a range of 2 to 7 mm according to the height of the unevenness of the plate-like metal that is the material to be heated. It is not limited to the protruding length.

The material of the ball 11 is preferably a non-magnetic material, a heat-resistant and wear-resistant material, for example, a ceramic such as alumina, SiC, or SiN.
In the present embodiment, the number of balls 11 is one at the center in the width direction of the traveling carriage 1, but two or three balls 11 are arranged along the center line in the width direction of the traveling carriage 1 to heat the carriage 11. The coil 10 can be prevented from inclining in the front-rear direction of the traveling carriage 1 and coming into contact with the material to be heated.

In FIG. 1, a lifting fixture 20 is attached to the upper portion of the amplification transformer 9 so that the amplification transformer 9, that is, the heating coil 10 can be fixed at a raised position.
A dust removal nozzle 21 is provided in front of the traveling carriage 1.

  The amplification transformer 9 amplifies a high-frequency current generated by a high-frequency power source (not shown) to a predetermined current value, and a heating coil 10 is connected to its output terminal.

  The inside of the heating coil 10 is hollow, and cooling water is passed through the inside to suppress the heating coil 10 from becoming high temperature.

  Note that a high-frequency power source that supplies a high-frequency current to the amplification transformer 9, a cooling water supply device that cools the heating coil 10, and a supply source of air that blows out from the dust removal nozzle 21 may be built in the traveling carriage 1, but the weight is high. In order to avoid becoming heavy, it can be installed on another mobile carriage and connected to the traveling carriage 1 with a cable or a tube.

Next, the operation of the induction heating device of the present embodiment will be described in order.
(1) First, the traveling carriage 1 is transported to a plate-shaped metal place which is a heat treatment scheduled part.
(2) The clutch of a clutch mechanism (not shown) between the drive wheel 2 and the drive motor 4 is disengaged so that the traveling carriage 1 can be freely moved manually.
(3) The supply air valve is opened, air is blown out from the dust removal nozzle 21, and the dust in the vicinity of the heat treatment start portion is blown off.
(4) Check the heat treatment start position, and insert a clutch mechanism between the drive wheel 2 and the drive motor 4.

(5) The lifting fixture 20 is released, the lower end of the ball 11 is brought into contact with the surface to be heated of the plate metal, and the heating coil 10 is adjusted to be in a state of floating for a certain length from the plate metal.
(6) The moving heating process is started by turning on the switch heating of the moving carriage, turning on the traveling by the drive motor 4, and opening the steel sheet cooling water valve.
(7) The movement process of the heat treatment scheduled part is completed.

(8) The traveling heating process is terminated when the switch heating of the traveling carriage 1 is turned off, the traveling by the drive motor 4 is turned off, and the steel sheet cooling water valve is closed.
(9) The supply air valve is closed, and the heating coil 10 is pulled up and fixed by the lifting fixture 20.
(10) The traveling carriage 1 is carried to the next heat treatment scheduled part.
(11) The clutch mechanism between the drive wheel 2 and the drive motor 4 is disconnected. As a result, the traveling carriage 1 can be manually moved freely.

  The present invention is an induction heating apparatus that can maintain the heating temperature condition while keeping the distance between the heating coil and the object to be heated constant even in various irregularities and undulations of the object to be heated and traveling with high power efficiency. In addition to removing distortion after heat treatment of the plate-like metal that is the surface to be heated, it can be used for heating for various purposes such as preheating before welding and heating before bending. In particular, in the heating of a thin plate, the surface to be heated expands and deforms at the moment of heating and becomes a concave or convex state in a narrow region, so that constant heating is difficult, so the effect of the present invention is great.

DESCRIPTION OF SYMBOLS 1 Traveling carriage 2 Drive wheel 3 Auxiliary wheel 4 Drive motor 5 Handle 6 Support tool 7 Lifting metal fitting 8 Movable frame 9 Amplifying transformer 10 Heating coil 11 Ball 12 Fixing plate 13 Current conducting conductor 14 Fixed metal fitting 15 Mounting metal 16 Screw 17 Ferrite core 18 Ball Base 19 Adjusting screw 20 Lifting fixture 21 Dust removal nozzle

Claims (3)

A traveling cart that can be driven by wheels includes an amplification transformer that amplifies and outputs an input high-frequency current, and a heating coil that generates an alternating magnetic field by the high-frequency current supplied from the amplification transformer, and is generated by the heating coil. In an induction heating device that heats the surface to be heated of the plate metal by inducing eddy current in the plate metal by the alternating magnetic field,
The heating coil has a U-shape having two opposite sides sandwiching a center line in the width direction of the traveling carriage,
At least one rotatable ball for holding the heating coil at a certain small distance from the plate metal at the lower end of a movable frame that supports the heating coil so as to be movable up and down with respect to the traveling carriage. Is provided on the center line in the width direction of the traveling carriage and on the center line of two opposite sides of the U-shaped heating coil .   The induction heating device according to claim 1, wherein the rotatable ball is made of a nonmagnetic material, a heat resistant material, and a wear resistant material.   The induction heating apparatus according to claim 1 or 2, further comprising means for supplying a lubricating liquid to a ball receiver that rotatably supports the ball.

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