KR101301908B1 - Induction heating coil enabling to open and close for heating steel sheet - Google Patents

Abstract

The present invention relates to an open / close type induction heating coil for heating a steel plate, which is surrounded by a part of a pass line of a steel plate and installed to be able to reciprocate laterally with respect to the traveling direction of the pass line. 1 The first door part mounted on one end of the nose piece and having a protruding end, and the second door part mounted on one end of the second nose piece and having a concave groove into which the protruding end is inserted. Including a pair of elastic conductors and actuators installed laterally from one end of the konip and connected to the first door part or the second door part to open and close the door, in consideration of the high frequency energizing skin current and the auxiliary elastic contact, the door The robustness of the partial contacts is maintained and the effect of maximizing the reliability of the system is achieved.

Description

Induction heating coil enabling to open and close for heating steel sheet}

The present invention relates to an open / close type induction heating coil for steel plate heating, and more particularly, by designing the structure of the induction heating coil in consideration of high frequency skin current characteristics and stable physical coupling force, thereby maintaining the robustness of the door contact and improving the reliability of the system. It relates to an open and close type induction heating coil for steel sheet heating that can be maximized.

There are various kinds of induction heating coils for steel plate heating, among which the open / close type induction heating coils are used in the steel sheet alloy plating line for alloying through induction heating after hot dip galvanizing. Necessary when the line to make simple galvanized steel sheet by passing through the hot dip galvanizing bath and air cooling and the line to make galvanium alloying of the surface layer by rapid heating of the steel sheet by induction heating are changed in one process line. Do.

1 is a schematic illustration of a portion of a conventional continuous hot dip galvanizing alloying plant.

As shown in FIG. 1, a continuous hot dip galvanizing alloying facility is provided above the plating bath 10 for galvanizing the steel sheet 1. On the plating bath 10, an air knife 20, at least one large power high frequency induction heating furnace 30, a cooling duct 40, and a mist cooling device 50 are arranged, and the plating bath 10 is disposed. The galvanized steel sheet 1 passed through is subjected to an alloying heat treatment process to allow the alloying of the plated phase to proceed.

Specifically, the molten zinc is adhered to the surface of the steel sheet 1 which has passed the plating bath 10 within 1 to 2 seconds, and the zinc plating amount is adjusted to a predetermined thickness by the air knife 20. Subsequently, the galvanized steel sheet 1 passing through the air knife 20 passes through at least one large power high frequency induction heating furnace 30, which is illustrated in FIG. 1 by way of two high frequency induction heating furnaces 31. 32) is shown.

For example, in the first high frequency induction heating furnace 31, the steel sheet 1 is heated to 460 ~ 520 ℃ so that the surface coating component of the steel sheet 1 is diffused into the inner layer to form a galvanium alloy layer. In addition, the steel sheet 1 passes through the second high frequency induction heating furnace 32, and maintains the surface temperature of the steel plate 1 heated primarily to 560 ~ 600 ℃ to give a holding time for diffusion. As a result, the galvanized steel sheet 1 is galvanium alloyed by a plurality of high frequency induction furnaces 31 and 32. Next, the steel plate 1 passes through the cooling duct 40 which cools the steel plate 1 using air, and the mist cooling apparatus 50 which cools the steel plate 1 using air and water. Thereby, the steel plate 1 is cooled to about 280 degrees C or less.

Since the galvanized steel sheet 1 having a thickness of about 0.6 to 2 mm should be induction heated rapidly, the plate-type induction heating coils 100 used in the first and second high frequency induction heating furnaces 31 and 32 (100). ) Is applied a large current of 50 ~ 80 kHz, 6000 ~ 12000 A from the high frequency power supply (33).

The magnetic field generated from the induction heating coil 100 through the application of a high frequency alternating current is rapidly heating the surface of the steel sheet 1 by a heating method inducing heat generation to the metal surface in the heating coil. In particular, the high-power high-frequency induction heating furnace 30 used in the hot-dip galvanized alloying facility has a very high current density and a current carrying density per unit width of the induction heating coil 100. Since the steel sheet 1 is heated up to 600 ° C. and close to the nonmagnetic temperature of iron, the current of the induction heating coil 100 is required to be several times higher than the heating conditions at room temperature (at least 6000 A). . Moreover, deterioration accidents due to large currents are frequently occurring at the contacts in the door part 120 of the induction heating coil 100. Since high frequency current of 50 kHz or higher is applied, local surface heat generation is also very high due to current deflection due to extreme skin effect.

On the other hand, in the field in which the induction heating coil 100 is installed, the heat deformation of the structure is caused by the rising heat generated in the high temperature plating tank 10 and the hot air gas burner (not shown) that is heated under the induction heating coil 100. Sag deepens. Even if some deflection or deformation of the structure, the contacts in the door portion 120 must be secured to maintain the survivability.

Moreover, in the conventional process, mainly fixed coils are mainly used due to the influence of high current, high voltage, and high frequency applied to the induction heating coil 100, but induction heating is performed when replacing the lower plating bath 10 or producing a simple galvanized steel sheet. Since the trolley (not shown) in which the coil 100 is installed may be retracted on a rail, for this purpose, the induction heating coil 100 may be used for spatial coupling of the steel sheet 1 continuously supplied to the induction heating coil 100. There is a need for a structure having a door portion 120 to allow one side central portion to be opened and closed. That is, the induction heating coil 100 used in the high frequency induction heating furnace 30 should have an open / close structure in which the door part 120 is opened and closed so that the steel plate 1 under tension is inserted and exited.

When the door part 120 is configured to automatically operate for frequent opening and closing, a mechanical actuator (not shown) is required. A general low frequency switch or a general knife type switch can handle heating and current contact densities in high frequency induction. It may not be able to deteriorate and burn out. Therefore, an actuator employing a pneumatic cylinder is used, and the characteristics of pneumatic pressure are widely adopted because the applied air pressure is continuously pushed during operation by acting as a spring.

Figure 2 is a plan view schematically showing an example of the door portion applied to the opening and closing type induction heating coil for steel sheet heating according to the prior art.

The example shown in (a) of FIG. 2 is a general contact point method, in which the pressure of the actuator acting behind the induction heating coil is dispersed on a wide surface A, so that the contact pressure per unit area falls, so that an equivalent electrical contact resistance is obtained. There is a growing characteristic. In addition, at high frequencies, due to the skin effect, current i flows along the outer skin. When looking at the contact microscopically, since the electrical contact that meets face-to-face is irregular and is inward, the surface movement distance of the current is increased, the heat generation is increased rapidly. In particular, when foreign matter remains on the contact surface, there is a problem that can be very dangerous do not push or escape naturally during opening and closing.

In FIG. 2B, a contact point method having a rounded surface is shown. If the contact surface is subjected to ultra precision processing, high-quality current i may flow in the form of a line contact B. FIG. Since the force being pushed from one pneumatic cylinder is concentrated only at the contact point, the contact pressure per unit area may be high, resulting in low electrical contact resistance. However, ultra-precision machining is practically difficult and ideal line contact is not made continuously. In addition, the high-purity copper plate has good ductility, so if the pushing force of the pneumatic cylinder is transmitted from the V-shaped groove to the left and right directions, the contact made with oxygen-free copper cannot guarantee continuous viability. Instead, it is a relatively free structure from metallic materials such as zinc powder.

The example shown in (c) of Figure 2 is a contact point type having a rhombus, and the tapered surface is increased in the pressing force to be fitted from the side shows a stable conduction performance in the initial installation. However, if heat, deformation, or torsional force is applied during use, the tapered and joined areas are opened outward and do not retract inward due to the characteristics of the high-purity copper plate. Once the spreading occurs, due to the epidermal effect caused by the high frequency, the current (i) is squeezed inward from the epidermis in the zigzag direction, so that the amount of heat generated is increased three times. In addition, when the deformation progresses due to heat generation or mechanical stress, heat is conducted to the cooling water pipe, which does not cool well and takes overheating pattern. Since the contact surfaces C and D are also wide, the pushing force is distributed to the pneumatic cylinder, so that the contact pressure per unit area decreases and the electrical contact resistance becomes larger. If any foreign substance is caught, it forms a point contact, so there is a disadvantage that it may occur until contact welding. Therefore, it is a very dangerous structure when contaminated with dust.

Opening and closing type induction heating coil for heating the steel sheet according to the prior art has a variety of problems in addition to the above, if the change in the electrical contact resistance of the door part is rapidly increased as described above causes excessive heat generation and the contact melts and emits. This may be caused by a decrease in the pneumatic pressure of the actuator, deterioration of the packing due to lack of heat resistance temperature of the packing material of the actuator, a horizontal defect in the mechanical left and right doors, a difference in expansion coefficient due to a decrease in cooling capacity, and thermal deformation.

In addition, due to the insulation breakdown of the door part or the induction heating coil, arcs are generated in the hinge part at the rear of the door part, and the actuator is designed to be located too close to the induction heating coil, thereby causing high heat in the actuator under the influence of the high frequency magnetic field. There is also a problem that occurs.

In addition, when the induction heating coil is opened and closed, the warpage of the body copper plate frequently occurs, because the induction heating coil made of high-purity copper plate is not restored after the stress caused by the frictional force between the floor and the ceiling during the horizontal opening and closing. Since the coolant line is attached to the copper plate through high temperature oxygen welding, the metal structure may be annealed to become even softer and may not have some elasticity. In addition, the lack of mechanical directional restraint force of the actuator and the hinge that pushes the induction heating coil and the door part may cause a warpage phenomenon.

Accordingly, the present invention, by designing the structure of the induction heating coil in consideration of the high-frequency skin current characteristics and a stable physical coupling force, to provide an open and close type induction heating coil for heating the steel plate to maintain the toughness of the door contact and to maximize the reliability of the system. Its purpose is to.

The opening and closing type induction heating coil for heating a steel sheet according to the present invention includes a first nose body and a second nose body which surround a part of a pass line of the steel plate and are reciprocated laterally with respect to the traveling direction of the pass line. A first door portion mounted on one end of the nose body and having a protruding end, and a second door part mounted on one end of the second nose body and having a concave groove into which the protruding end is inserted, and on both sides of the protruding end. A pair of elastic conductors to be installed, and at least one end of at least one of the koja body is installed laterally with respect to the longitudinal direction of the koja body connected to the first door portion or the second door portion to open and close Contains an actuator.

According to the present invention as described above, by considering both the high-frequency conduction skin current and the auxiliary elastic contact, the current flows at the outside of the door as much as possible, but the contact is made to be a narrow surface contact and there is no torsional deformation and at the same time, the elastic By placing additional conductors to ensure the survivability and duplicity of the contacts, the robustness of the contacts is maintained and the effect of maximizing the reliability of the system is achieved.

1 is a schematic illustration of a portion of a conventional continuous hot dip galvanizing alloying plant.
2 is a plan view schematically showing examples of a door part applied to an open / close induction heating coil for heating a steel sheet according to the prior art.
Figure 3 is an enlarged perspective view of the main portion of the open-type induction heating coil for heating the steel sheet according to the present invention.
FIG. 4 is a plan view illustrating the first door part and the second door part shown in FIG. 3.
5 is a front view showing a connection relationship between the door portion and the actuator of the open-type induction heating coil for heating the steel sheet according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unclear.

Referring to FIG. 1 again before explaining the main part of the open / close induction heating coil for steel sheet heating according to the present invention, the continuous hot-dip galvanizing alloying equipment is supported at least by the support (not shown) at intervals vertically at least Including a pair of induction heating coil 100, that is, at least one large power high frequency induction heating furnace 30, the induction heating coils 100 to the steel sheet 1 extracted upward from the plating bath 10 Heating by passing through).

The high power high frequency induction heating furnace 30, which is composed of induction heating coils 100, a support, and a high frequency power supply 33, is installed on a trolley (not shown) that is horizontally movable along a rail of the structure. During the alloying process, the pass line of the steel sheet 1 is positioned at the center between the induction heating coils 100, and when the alloying process is unnecessary, the bogie is moved laterally with respect to the traveling direction of the pass line. The high power high frequency induction heating furnace 30 can be retracted away from the pass line of the steel sheet 1.

In order to enable the movement of the large power high frequency induction heating furnace 30 without cutting the steel sheet 1, the door part 120 is provided at one end of each induction heating coil 100 so as to be openable and openable. By opening the door part 120 wide and moving the large power high frequency induction heating furnace 30 in the horizontal direction by a trolley, the steel sheet 1 can be taken in and out of the interior between the induction heating coils 100. Will be.

Figure 3 is an enlarged perspective view of the main portion of the open-type induction heating coil for heating the steel sheet according to the present invention, Figure 4 is a plan view showing the first door portion and the second door portion shown in FIG. In addition, Figure 5 is a front view showing a connection relationship between the door portion and the actuator of the open-type induction heating coil for heating the steel sheet according to the present invention.

As shown in these drawings, the steel sheet heating type induction heating coil 300 according to the present invention is surrounded by a part of the pass line of the steel sheet 1 so as to reciprocate sideways with respect to the traveling direction of the pass line. The first nose part 311 and the second nose body 312, which are mounted on one end side of the first nose body 311 and having a protruding end 323, are provided with a first door part 321 and a second nose body (311). As long as it is mounted on one side of the 312 and provided on both sides of the second door part 322 and the protruding end 323 having the concave groove 324 into which the protruding end 323 of the first door part 321 is inserted. At least one of the pair of elastic conductors 330 and the coarse bodies 311 and 312 is installed laterally with respect to the longitudinal direction of the coarse bodies 311 and 312, and the first door part 321 or the first door. The actuator 340 is connected to the two door parts 322 to open and close.

The first nose body 311 and the second nose body 312 are formed symmetrically with each other, and each nose body 311 and 312 is made of a metal plate such as, for example, a copper plate.

A first door part 321 having a protruding end 323 is mounted on one end of the first nose body 311, and a protruding end 323 of the first door part 321 on one end of the second nose body 312. A second door part 322 having a concave groove 324 into which is inserted is mounted. These door parts 321 and 322 are made of high-purity copper, and are assembled and fixed by bolts (not shown) on one end of each Konip 311 and 312, and have a detachable structure that can be separated and replaced with a new one when broken. .

When the protruding end 323 of the first nose body 311 is inserted into the concave groove 324 of the second nose body 312 so that the door parts 321 and 322 are closed, the first nose body 311 and The second nose body 312 forms a large power high frequency induction heating furnace which surrounds the pass line, and the inside of these induction heating coils 300 becomes the passage part of the steel plate 1.

Cooling water pipes 320 are formed in each of the door parts 321 and 322. The door parts 321 and the door parts 321 and 322 are made of a material having high thermal conductivity, and the door parts 321 are formed due to the coolant passing through the coolant pipes 320. Excessive heat generation caused by the 322 is suppressed, thereby preventing the contact point or the door parts 321 and 322 from melting. For simplicity of illustration, a cooling water hose for supplying cooling water to the cooling water pipe 320, a cooling water inlet and an outlet, and the like are omitted in the drawings, and a detailed description thereof will be omitted.

As shown more clearly in the plan view of FIG. 4, the protruding end 323 has a substantially rectangular cross section, and the concave groove 324 has a cross-sectional shape substantially corresponding to that of the protruding end 323. There is a slight gap between the protruding end 323 and the concave groove 324. That is, the lateral outer circumferential surface of the protruding end 323 and the lateral inner circumferential surface of the concave groove 324 are not in contact with each other so that zinc is attached to the contact inner surface. Form a space for the powder to be pushed out.

Instead, the shoulders 325 around both sides of the protruding end 323 in the first door part 321 and the extension parts forming both sidewalls of the concave groove 324 in the second door part 322. Substantially abutting 326 makes contact between the first door portion 321 and the second door portion 322 and ultimately between the first nose body 311 and the second nose body 312.

The contact surface of the shoulders 325 is such that its total area (e.g., twice the contact surface area of one shoulder portion) is considerably narrower than that of the front surface of the protruding end 323. The shape or the area of each contact surface of both shoulders 325 need not necessarily be the same, but in order to transmit equivalent pressure, the shape and area are the same.

In addition, the inner edges of the contact surfaces of both extensions 326 are chamfered, so that the actual thickness of the extensions 326 is maintained, but the area of the contact surfaces of the extensions 326 is reduced. Accordingly, it is possible to adjust the contact pressure per unit area of the contact, and also to secure a space in which dust can be deposited or discharged on the contact in advance.

Although the area of these contact surfaces is formed to be considerably narrow, both shoulder portions 325 and both extension portions 326 are almost in line contact by narrowing the contact area further through chamfering. Accordingly, the contact pressure per unit area is high, so that the electrical contact resistance can be lowered. As a result, the amount of heat generated can be greatly reduced by the contact line moved in the outer skin direction of the door part.

In the open / close type induction heating coil 300 for heating the steel sheet according to the present invention, fitting grooves 331 are formed on both sides of the protruding end 323 along the entire length thereof, and the elastic conductor 330 in the fitting groove 331. ) Is installed. The elastic conductor 330 is a kind of leaf spring member made of one or a combination of metal materials such as silver, copper, brass, gold, tin, and the like. Among these materials, it is preferable to configure the elastic conductor 330 with silver because the electrical conductivity is excellent and the current concentrated in the contact can be overcome.

Of course, the fitting groove 331 may be formed in the concave groove 324, but if the fitting groove 331 is formed in the extension portion 326 forming both sidewalls of the concave groove 324, the extension portion 326 ) Is not preferred because the thickness of the c) should be thickened and the effect of increasing the area of the contact surface to reduce the amount of heat generated is not exhibited.

On the other hand, the cross-sectional shape of the fitting groove 331 is formed to be approximately equal to the letter 'c', the width is formed to be narrower than the width of the elastic conductor 330, then pressure is applied to both ends of the width direction of the elastic conductor 330 When inserted into the fitting groove 331 in the applied state, the central portion of the elastic conductor 330 is exposed from the fitting groove 331 toward the outer side of the protruding end 323 protrudes convexly. Preferably, a plurality of hemispherical embossings 332 are arranged in a line along the longitudinal direction at the central portion of the outer surface of the elastic conductor 330 so that the point of contact between the elastic conductor 330 and the sidewall of the concave groove 324 is virtual.

When the cross-sectional shape of the fitting groove 331 has a shape of approximately 'c', fixing grooves 333 may be formed along the entire length of both sides of the fitting groove 331, and these fixing grooves 333 Conductive clamps 334 each having a separate 'C'-shaped cross section may be inserted into and fixed to both ends of the elastic conductor 330 in the width direction.

Since the elastic conductor 330 is provided, the elastic conductor 330 and the concave groove (even if there is a lack of precision or thermal deformation of the contact point E formed by the shoulder portion 325 and the extension portion 326). An additional auxiliary contact (F) between the 324, to ensure the survivability and duality of the contact to be maintained in the induction heating coil (300). In addition, even if there is a mechanical shock or vibration in the doors 321 and 322 during operation, the toughness of the contact is maintained, even if the pressure of the actuator 340 to be described later, the contact is maintained to operate to maintain the induction heating The effect of maximizing the reliability of the coil 300 to the system is to be obtained.

In addition, the high frequency current i applied to the nose and the door part is driven to the skin only by the skin effect, and the contacts E and F are positioned substantially close to the outer surface of the entire door part, so that only the outer part of the door part is located. Current i flows. In particular, the auxiliary contact F is disposed on both sides of the protruding end 323 instead of the front, so that the current i does not flow to the inner center portion of each door part 321 or 322, and the current moving distance is shortened. . Accordingly, the amount of heat generated is minimized, thereby improving the cooling capacity of the door unit.

Next, the actuator 340 is installed laterally with respect to the longitudinal direction of the nose body 311, 312 at one end of the nose body 311, 312, and the first door part 321 or the second door part 322. It is connected to the rear side, that is, the opposite end of the protruding end 323 or the concave groove 324 to allow these door parts (321, 322) to be opened and closed. Since the actuators 340 provided with respect to the first door part 321 or the second door part 322 may be identically and symmetrically disposed, the actuator 340 for the first door part 321 for convenience of description. Only the details will be described.

The actuator 340 is mounted on a box-shaped support bracket 341 installed around the first nose piece 311, and a plurality of connection mediating elements are installed between the actuator 340 and the first door part 321.

Specifically, a hinge member 342 made of an insulating material such as epoxy is installed on the rear surface of the first door part 321, and the first door part 321 and the hinge member 342 are hinge pins (not shown). Connected by The hinge member 342 is operated by the actuator 340 to linearly reciprocate the first door part 321, but in practice, the first door part 321 is rotated based on the other end of the first nose body 311. Since it is, it is necessary for the smooth rotation of the first door portion 321. At this time, the first door part 321 rotates about 1 to 2 degrees.

The hinge member 342 is fixedly connected to the guide member 343. The guide member 343 is a rod-shaped member made of an insulating material such as epoxy, for example, and has a polygonal cross section, and is connected to the actuator 340 through the support bracket 341. Since the hinge member 342 and the guide member 343 are made of an insulating material of a nonmagnetic material such as epoxy, induction heating due to the influence of the magnetic field does not occur. In particular, the guide member 343 has a polygonal cross section such as a quadrangle as shown in FIG. 3, so that the first door parts 321 to the first corrugated body 311 have space constraints of four sides, It can be opened and closed without torsional deformation, and the first door part 321 is stably engaged with the second door part 322 to form a contact point.

In addition, the actuator 340 is installed on the support bracket 341 via a pair of restraining members 345. The restraining member 345 is a plate-shaped member having a predetermined thickness, so that the restraining members 345 are minute to each other so that the guide member 343 can smoothly reciprocate linearly without friction between the restraining members 345. It is positioned as close as possible to the guide member 343 on both sides at intervals. The pair of restraining members 345 may be installed vertically or horizontally.

Since the restraining members 345 are positioned close to the guide member 343 and the guide member 343 has an angular shape, the guide member 343 cannot be rotated between the restraining members 345. . The guide member 343 causes the guide member 343 to reciprocate linearly without rotation or torsion due to the restraining member 345, and ultimately, the first door part 321 to the first corpus 311 can be opened and closed without torsional deformation.

The restraining member 345 and the support bracket 341 are made of a metal such as aluminum, which has a moderate strength and light weight, and generates little heat by the induced magnetic field.

A separate insulating member 346 electrically and thermally insulates between the restraining members 345 and the actuator 340 to generate heat from the actuator 340 by induction heating or conduction, or the actuator 340. The heat transfer can be prevented.

The actuator 340 employs a heat resistant pneumatic cylinder. The cylinder rod of the pneumatic cylinder and the guide member 343 may be screwed together. The characteristic of the pneumatic pressure is that the applied air pressure is pushed during operation due to the permanent spring action. In addition, by attaching a speed controller (not shown) to the pneumatic valve line for driving the pneumatic cylinder to prevent the pneumatic cylinder, that is, the actuator 340 from operating at high speed, each door portion 321, 322 of high purity copper ) Is not to be damaged by mechanical shock.

According to the present invention, as described above, the distance between the nose unit (including the door part) and the actuator is separated by a plurality of connection media elements to suppress the heat generated in the actuator by the induced magnetic field to the maximum, and polygons such as squares The guide member having a cross section of the top has the advantage that there is no distortion of the nose when opening and closing the door.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

300: induction heating coil
311: 1st nose Japanese body
312: The second nose Japanese body
321: first door part
322: second door
323: protrusion
324: concave groove
325 shoulder
326 extension
330 elastic conductor
340: Actuator
342: hinge member
343: guide member
345: restraining member

Claims (20)

A first nose body and a second nose body which surrounds a part of the pass line of the steel plate and is installed to reciprocate laterally with respect to the traveling direction of the pass line;
A first door part mounted at one end of the first nose body and having a protruding end,
A second door part mounted on one end of the second nose piece and having a concave groove into which the protruding end is inserted;
A pair of elastic conductors installed on both sides of the protruding end, and
An actuator installed laterally with respect to the longitudinal direction of the konip at one end of at least one of the konips and connected to the first door part or the second door part for opening and closing operation;
Opening and closing type induction heating coil for steel plate heating comprising a. The method of claim 1,
An open / close type induction heating coil for heating a steel plate in which the shoulder part around both sides of the protruding end of the first door part and the extension part forming both sidewalls of the concave groove in the second door part contact each other. The method of claim 2,
The total area of the contact surface of the shoulder portion is narrower than the area of the front surface of the protruding end heating induction heating coil for steel sheet. The method of claim 2,
Opening type induction heating coil for heating the steel sheet is the same shape or area of the shoulder surface of the both shoulders. The method of claim 2,
Opening-type induction heating coil for heating the steel sheet is the inner edge at the contact surface of the both extensions are chamfered. The method of claim 1,
Both sides of the protruding end is formed with a fitting groove along the entire length,
Opening and closing type induction heating coil for heating the steel sheet in which the elastic conductor is installed in the fitting groove. The method of claim 1,
The elastic conductor is a plate spring member for opening and closing type induction heating coil for steel plate heating. The method of claim 1,
The elastic conductor is an open-type induction heating coil for heating the steel sheet is made of one or a combination of silver, copper, brass, gold, tin. The method of claim 1,
Opening and closing type induction heating coil for heating the steel sheet in which a plurality of hemispherical embossing is arranged in the center of the outer surface of the elastic conductor in the longitudinal direction. The method according to claim 6,
Opening and closing type induction heating coil for heating the steel sheet is formed on both sides of the fitting groove along the entire length of the fixing groove. The method of claim 10,
A conductive clamp is inserted into the fixing groove to open and close the steel sheet heating induction heating coil to fix both ends in the width direction of the elastic conductor. The method of claim 1,
The actuator is a pneumatic cylinder open and close type induction heating coil for heating the steel sheet. The method of claim 1,
The actuator is an open-type induction heating coil for heating the steel sheet is mounted to the support brackets installed around the nose piece. The method of claim 13,
Hinge members are rotatably connected to each door part,
A guide member is fixedly connected to the hinge member,
The guide member is an opening and closing type induction heating coil for heating the steel sheet is coupled to the actuator through the support bracket. 15. The method of claim 14,
The hinge member and the guide member is open and close induction heating coil for heating the steel sheet is made of a non-magnetic insulating material. 15. The method of claim 14,
The guide member is an open-type induction heating coil for heating a steel sheet which is a rod-shaped member having a polygonal cross section. 17. The method of claim 16,
The actuator is installed on the support bracket via a pair of restraining members, the restraining members are spaced apart from each other so that the guide member is positioned between the restraining members in close proximity to the heating coil induction heating coil. 18. The method of claim 17,
Opening and closing type induction heating coil for heating the steel plate between the restraining member and the actuator is provided with a separate insulating member. The method of claim 12,
Opening and closing type induction heating coil for heating the steel plate with a speed controller attached to the pneumatic valve line for driving the pneumatic cylinder. The method of claim 1,
Opening and closing type induction heating coil for heating the steel sheet is formed in each door portion cooling water pipe.

Images