JP5522672B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating device.

As one of the induction heating devices, there is an induction heating roller device. FIG. 5 shows an example of the structure of such an induction heating roller device. The roller 1 is rotatably supported by a bearing 3 with respect to a machine base 2 and is driven to rotate by a motor (not shown). Reference numeral 4 denotes a jacket chamber formed in the thick portion of the roller 1, in which a gas-liquid two-phase heat medium is enclosed.

  In this example, an induction heating mechanism 7 comprising six induction coils 5 wound around an iron core 6 is disposed inside the hollow of the roller 1, and each induction coil 5 is substantially in the axial direction of the roller 1. They are arranged from end to end. Reference numeral 8 denotes a magnetic disk interposed between the induction coils 5, and 9 denotes a support rod for supporting the induction heat generating mechanism 7, which is supported inside a journal 11 connected to the roller 1 via a bearing 10. Reference numeral 5a denotes a lead wire of the induction coil 5, which is led out through the support rod 9 and connected to an external AC power source.

  In the induction heating roller device configured as described above, when an alternating current is passed through each induction coil 5, an alternating magnetic flux is generated. The alternating magnetic flux generates an induced current in the roller 1, and the roller 1 generates Joule heat by the induced current. Then, the belt-shaped workpiece to be conveyed in contact with the surface of the roller 1 with the heat is heat-treated. In this case, it is necessary to uniformly heat the object to be processed, but the heat generation due to the amount of magnetic flux by the induction coil increases in the central portion in the longitudinal direction of one induction coil, and the distribution of the mountain shape decreases toward the end. Become.

Therefore, if a large number of induction coils are arranged, each induction coil is connected in parallel to a single-phase AC power source, and the direction of the magnetic flux generated by each induction coil is the same, a mountain with a large amount of heat generated by each induction coil. The space | interval of the top part of can be shortened. Thereby, the temperature in the longitudinal direction of the roller 1 is made uniform, and in addition, the temperature is made more uniform by the movement of the latent heat of the gas-liquid two-phase heat medium sealed in the jacket chamber 4.

  By the way, in the case of using an induction coil, particularly an induction heat roller device using a plurality of induction coils or a plurality of induction heat roller devices, as a power source to be applied to the induction coil, it is generally supplied from a convenient power company. It is desired to use a phase AC power source. However, in a three-phase AC power source, as is well known, there is a phase difference of 120 degrees in the power supply voltage of each of the three-phase phases Eu, Ev, and Ew. The generation time is greatly different, and the uniformity as in the case of using the above-described single-phase AC power source cannot be obtained.

Therefore, it is conceivable to reduce this phase difference. For that purpose, six induction coils are used, divided into three, one of which is connected to the delta and connected to the power supply of each of the three-phase Eu, Ev, Ew (delta connection), and the remaining one Are connected to the star and connected to the power sources of the three-phase phases Eu, Ev, Ew (star connection). Then, when the star-connected induction coils and the delta-connected induction coils are alternately arranged, a voltage having a phase difference of 30 degrees can be applied to each induction coil.

However, even though the induction coil that is star-connected and the induction coil that is delta-connected are alternately arranged, in the induction heating device as described above, the direction of the magnetic flux generated by the six induction coils at the same time is the same. There is a need to. FIG. 6 shows wirings in which the directions of magnetic fluxes generated by six induction coils at the same time are the same, a to f are six induction coils, and a to f are horizontal arrangement orders. ing. The induction coil a has one end (hereinafter referred to as the left end in FIG. 5) connected to the Eu phase power source and the other end (hereinafter referred to as the right end in FIG. 5) to the neutral point N, and the induction coil adjacent to the induction coil a. b has one end connected to the Ew-phase power supply and the other end connected to the Eu-phase power supply, and the end connected to the Eu-phase power supply is reversed with respect to the induction coil a, that is, the polarity is reversed. The direction of the magnetic flux is the same.

Similarly, the induction coil c has one end connected to the Ew phase power source and the other end connected to the neutral point N in the same manner as the induction coil b. The induction coil d has one end connected to the Ev phase power source and the other end connected to the Ew phase power source. The induction coil e has one end connected to the Ev-phase power source in the same manner as the induction coil d, and the other end connected to the neutral point. The induction coil f has one end connected to the Eu-phase power source and the other end connected to the Ev-phase power source. ing. When the six induction coils are arranged in this order from a to f, the direction of the magnetic flux generated by the six induction coils at the same time is made the same and applied to adjacent induction coils as shown by the vector in FIG. The phase difference of the applied voltage can be set to 30 degrees.

Then, as can be understood from the vector diagram shown in FIG. 7, when increasing the number of induction coils, it is only necessary to arrange the induction coils to be increased in the portions indicated by the dotted lines in FIG. If arranged, a voltage with a phase difference of 30 degrees can be applied to 12 induction coils). It is also possible to add one induction coil. An example in that case is shown in FIG. In the example shown in FIG. 4, the induction coil g connected to the Eu phase power source and the neutral point N is an increase, and this induction coil g is arranged next to the induction coil f.

JP 2002-83675 A

  By the way, the characteristic required for the roller that is the heat generating body of the induction heat generating device is a uniform temperature distribution on the roller surface, but there is an invalid length portion where the workpiece is not applied to both ends of the roller. The temperature may rise or fall because heat is not taken away, and this temperature change adversely affects the heat treatment of the workpiece, so it is necessary to control the current flowing through the induction coils located at both ends of the roller. is there. However, in the configuration in which each induction coil is directly connected to the three-phase AC power source as described above so that a voltage with a phase difference of 30 degrees can be applied, there is a great merit that a multi-phase transformer is not required. There is a problem in that the currents flowing through the induction coils located at both ends of each cannot be individually controlled.

The problem to be solved by the invention is an induction heating device arranged such that each induction coil is directly connected to a three-phase AC power supply and a voltage having a phase difference of 30 degrees can be applied, and the induction coils located at both ends of the arrangement It is in the point which makes it possible to control individually the electric current which flows into.

In order to solve the above problems, the present invention provides an induction coil array in which six induction coils are arranged in a horizontal direction, and voltages having a phase difference of 30 degrees are applied to each induction coil from a three-phase AC power supply in the arrangement order. Is an induction heating device in which x units (x is an integer of 1 or more) are sequentially arranged in the horizontal direction, and one induction coil is added to the forefront of the x unit arrangement. The one induction coil added and the one induction coil located at the last stage of the unit array are connected in parallel and connected to the three-phase AC power source through current control means. And

In the present invention, six induction coils are arranged in a horizontal direction, and an induction coil array formed by applying a voltage having a phase difference of 30 degrees from a three-phase AC power supply to each induction coil in the arrangement order is used as a unit. (Where x is an integer equal to or greater than 1) is an induction heating device that is sequentially arranged in the horizontal direction, and one induction coil is added to the front stage of the x unit arrangement, and the added one induction Since the coil and one induction coil located at the last stage of the unit array are connected in parallel and connected to the three-phase AC power source via the current control means, a multi-phase transformer similar to the conventional one is not required. In addition to having a great merit, the induction coils located at the ends of both sides apply the voltage between the same phase of the three-phase AC power supply, so that the current is individually applied without affecting the induction coil located in the middle part. Can be controlled.

It is a connection diagram of the induction coil which concerns on the Example of this invention. It is a wiring diagram of the induction coil shown in FIG. It is sectional drawing of the induction heating apparatus which concerns on the Example of this invention. It is a connection diagram of the conventional induction coil. It is sectional drawing of an induction heating roller apparatus. It is a connection diagram of the conventional induction coil. It is a voltage vector figure in a star delta connection.

An induction heating apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Each wiring of the three-phase AC wiring system is referred to as an Eu phase power source, an Ev phase power source, and an Ew phase power source. FIG. 1 shows a connection state between a three-phase AC power source and an induction coil, and FIG. 2 shows a wiring state in which the induction coils are arranged in the horizontal direction. In FIGS. 1 and 2, reference numerals 12, 13, and 14 denote thyristors. And current control means such as a saturable reactor, 15 is an induction heating element such as a roller, and a to f and h are induction coils.

Except for the current control means 12, 13, and 14, the six induction coils of the induction coil a to the induction coil f are the same as the connection state with the three-phase AC power source shown in FIG. The induction coil h is connected between the Eu phase power source and the Ev phase power source.

In this embodiment, the induction coil h, induction coil a, induction coil b, induction coil c, induction coil d, induction coil e, induction coil along the width direction of the induction heating element 15 as shown in FIG. They are arranged in a row (may be a plurality of rows) in order with f. Hereinafter, the left end portion of each induction coil in the arrangement state is referred to as one end, and the right end portion is referred to as the other end. One end of the induction coil h located at one end of the induction heating element 15 is connected to the Eu phase power supply via the current control means 13, and the other end is connected to the Ev phase power supply. The induction coil f located at the other end has one end connected to the Eu phase power supply via the current control means 12 and the other end connected to the Ev phase power supply. That is, the induction coil h and the induction coil f are connected to the Eu phase power source and the Ev phase power source in antiparallel. This connection allows individual control without affecting the current flowing through the other induction coils a to e located in the intermediate portion. When the currents flowing through the induction coil h and the induction coil f are the same, the current control means 12 and 13 can be made one.

  The induction coils a to e located in the middle part of the induction heating element 15 connect the other ends of the induction coil a, the induction coil e, and the induction coil c in common, and one end of the induction coil a and the other end of the induction coil b. And connected to the Eu phase power supply via the current control means 14a. One end of the induction coil b, one end of the induction coil c, and the other end of the induction coil d are connected and connected to the Ew phase power supply via the current control means 14c. One end of the induction coil d and one end of the induction coil e are connected and connected to the Ev phase power supply through the current control means 14b.

By wiring each induction coil in this way, the phase difference between the voltage applied to the induction coil h and the voltage applied to the induction coil a located adjacent thereto can be set to 30 degrees as is apparent from FIG. it can. Further, controlling the current flowing through the induction coil h and the induction coil f does not significantly affect the current flowing through the other induction coils a to e. In addition to controlling the current flowing through the induction coil h and the induction coil f, this can also control the current flowing through the other induction coils a to e. That is, the temperature of the intermediate portion of the induction heating element 15 can be controlled to a predetermined temperature, and the temperatures of the end portions on both sides of the induction heating element 15 can be set higher or lower than the predetermined temperature.

The induction heating element 15 is not limited to the one in which the array of induction coils shown in FIG. 5 is installed in the hollow interior of the roller, but may be a plate shape or a rod shape, and the heat treatment material is accommodated in the inside as shown in FIG. It may be installed on the outer periphery of the roller. In FIG. 3, 16 is a container-shaped roller body, 17 is a rotating shaft connected to a motor or the like, and 18 is a magnetic flux passage cylinder in which thin silicon steel plates such as an involute core are laminated in a cylindrical shape. The roller body 16 has an opening on the opposite side to which the rotating shaft 17 is fixed, and the opening accommodates a heat treatment product therein and is closed with a lid 16a. The row of the induction coils h and a to f shown in FIG. 2 surrounds the outer periphery of the roller body 16, and the magnetic flux passage cylinder 18 surrounds the outer periphery. That is, the magnetic flux generated by the induction coils h and a to f flows through the roller body 16 and the magnetic flux passage cylinder 18, and the roller body 16 generates induction heat.

In the above example, one induction coil is added to six induction coils connected in a star and delta connection to a three-phase AC power source, and the current flowing through the induction coils located at both ends of the induction coil array is converted into the induction coil. The current flowing in the induction coil located in the middle of the row is controlled separately from the current, but the number of the six induction coils is not limited to six, and is an integral multiple of six. Also good. For example, when twelve induction coils are arranged and one induction coil is added, the induction coils may be inserted into all six star and delta connections, that is, all the dotted lines shown in FIG. . In this way, 12 induction coils connected in 6 stars and deltas are arranged in a lateral direction so that voltages having phases different from each other by 30 degrees are sequentially applied . The induction coils a, b, c shown in FIG. , D, e, and f are repeatedly arranged in the horizontal direction .
That is, six induction coils are arranged in a horizontal direction, and an induction coil array formed by applying a voltage having a phase difference of 30 degrees from the three-phase AC power source to each induction coil in the arrangement order is set to an integral multiple of the unit. As shown in FIG. 2, one induction coil connected in parallel with the induction coil f located at the last stage in the unit array may be installed at the foremost stage of the arrangement.

a to f, h Inductive coils Eu, Ev, Ew Three-phase AC power sources 12, 13, 14 Current control means 15 Induction heating element

Claims (4)

Six induction coils are arranged in the horizontal direction, and an induction coil array formed by applying voltages different in phase by 30 degrees from the three-phase AC power source to the induction coils in the arrangement order is used as a unit. Is an induction heating device in which one or more integers are sequentially arranged in the horizontal direction, and one induction coil is added to the front stage of the x unit arrangement, and the added one induction coil and the unit An induction heating device, wherein one induction coil located at the last stage of the array is connected in parallel and connected to the three-phase AC power source through current control means . One induction coil added to the foremost stage of the x unit array and one induction coil located at the last stage of the unit array are connected in parallel via current control means and connected to a three-phase AC power source. induction heating apparatus according to claim 1, characterized by comprising Te. The induction heating device according to claim 1 or 2, wherein the induction coils arranged in the lateral direction are installed in the hollow of the roller . The induction heating device according to claim 1 or 2, wherein the induction coils arranged in the lateral direction are installed on the outer periphery of a roller for accommodating the processed material in the hollow interior.

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