JP2017004695A - Induction heating coil and heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating coil and a heating method that can perform both of heating efficiency and uniform heating and secure soldering quality with a short tact.SOLUTION: In an induction heating coil 100 for generating high frequency by electromagnetic induction, arranging soldering material 103 at a connection portion between an end portion of a first metal pipe 102 having a large outer diameter and an end portion 101 of a second metal pipe 102 having a smaller outer diameter than the first metal pipe in a heating target portion 100a, and performing soldering by high frequency heating, two or more turns 105a, 105b are formed in the opposite directions on both the sides of the first and second metal tubes in mutually opposite directions, and a transfer portion 106 for connecting the respective turns can be arranged to be nearer to the second metal pipe than the first metal pipe.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to an induction heating coil and a heating method for brazing a metal pipe at high frequency in a heat exchanger used in an air conditioner such as an air conditioner.

In recent years, CO ₂ reduction is strongly demanded from the viewpoint of global environmental protection, and energy saving is a major issue even in air conditioners that account for about 25% of the energy consumption of ordinary households. In particular, the heat exchanger is one of the important components of the air conditioner, and the demand for high performance is very high.

  Generally, a heat exchanger for an air conditioner includes a large number of plate fins made of aluminum or iron and the like arranged in parallel to each other, and these plate fins are penetrated in the thickness direction, and a plurality of heat transfer tubes are passed through the through holes. The one with is known. In order to manufacture such a heat exchanger, first, plate fins and heat transfer tubes are assembled in a predetermined arrangement to form a heat exchanger core. Thereafter, a U-shaped and a plurality of other joint pipes communicating with the heat transfer tubes are joined to the opening end portions of the heat transfer tubes protruding from the end portions of the heat exchanger core, and the refrigerant circulating around each heat transfer tube It is necessary to form a route.

  Conventionally, a gas brazing method using a flame burner has been used as a method for joining metal pipes as described above. In the case of such gas brazing, the metal tube is heated by radiant heat in a flame atmosphere. For this reason, the heating region is wide and a temperature distribution of several hundred degrees is generated, and local and constant temperature control of the joint portion of the metal tube becomes difficult. Therefore, for example, defects such as damage to the metal tube due to excessive heating or insufficient wrapping of the brazing material due to insufficient heating occur.

  In order to solve this problem, high-frequency brazing technology has been developed to improve the brazing quality by heating the joint portion of the metal tube to an equal temperature by induction heating technology (see, for example, Patent Document 1). ).

  A specific brazing process is shown below.

  7A to 7E are explanatory views showing respective steps of a conventional method for joining metal tubes by induction heating.

  First, as shown in FIG. 7A, a tube expansion portion 301 is formed at the opening end of the heat transfer tube 302.

  Next, as shown in FIG. 7B, a ring-shaped brazing material 303 and a joint pipe 304 are arranged in the expanded pipe portion 301 formed at the open end of the heat transfer tube 302.

  Next, as shown in FIG. 7C, an induction heating coil 305 (solenoid type) in which a copper pipe is wound in the same direction is placed close to the work holding space 305a so that the connection portion between the heat transfer pipe 302 and the joint pipe 304 is located. Deploy.

  Next, as shown in FIG. 7DD, by applying an electric current to the induction heating coil 305, the heat transfer tube 302 and the joint tube 304 are heated, and the ring-shaped brazing material 303 is melted to form a fillet. The brazing material 303 wraps around the gap between the heat pipe 302 and the joint pipe 304.

  Next, as shown in FIG. 7E, by stopping the application of current and removing the induction heating coil 305, the brazing material 303 is cooled, and the heat transfer tube 302 and the joint tube 304 can be joined.

  However, with recent demands for cost reduction of heat exchangers, the members used for metal tubes are being changed from copper to aluminum. In the case of brazing aluminum compared to copper, the difference in melting point between the base material and the brazing material is as small as about 1/5. In order to ensure the brazing quality, the difference in melting point between the base material and the brazing material. It is necessary to set a temperature profile that falls within the range, sense the brazing temperature using a non-contact thermometer such as a radiation thermometer, and follow the set temperature profile (temperature feedback control). When temperature feedback control is performed with a solenoid type coil wound in the same direction as in Patent Document 1, the current command value to the output power source pulsates in order to follow the temperature profile. Directional electromagnetic force is generated, the brazing material moves from a predetermined position (hopping phenomenon), and the brazing material becomes insufficiently melted.

  The generation mechanism of this hopping phenomenon will be described with reference to FIGS. As shown in FIG. 8B, when the temperature feedback control is not performed and the peak value C of the alternating current is always a constant value and the period D is always constant, as shown in FIG. 8A, the circulating portion 305a of the induction heating coil, 305b always generates a magnetic flux A in the same direction, and the brazing material 303 always generates an equal electromagnetic force B in the opposite direction and cancels it. For this reason, it becomes possible for the brazing material 303 to remain in a predetermined position with respect to the induction heating coil. On the other hand, as shown in FIG. 9B, when the temperature feedback control is performed, when the peak value C of the alternating current changes and the period D becomes indefinite, as shown in FIG. When the magnetic flux A in the same direction is generated in the surrounding portions 305a and 305b, the electromagnetic force B applied to the brazing material 303 changes with time and becomes non-uniform. For this reason, when the upward force becomes large, the brazing material 303 is lifted from a predetermined position with respect to the induction heating coil.

  As an induction heating coil when performing temperature feedback control, as shown in FIGS. 10A and 10B, an induction heating coil in which a copper tube is bent into a U shape or C shape in a plan view or an inverted U shape or an inverted C shape in a side view. 405 (horse-shoe coil) is placed in close proximity so that the connection portion between the heat transfer tube 402 and the joint tube 404 is positioned in the heating target portion 405a of the U-shaped or C-shaped work holding space in plan view. Generation of uniform electromagnetic force can be prevented. Although the structure of the coil shows one turn that is bent once and again, it may be two or more turns that are bent over three or more times (see, for example, Patent Document 2). In this case, as shown in FIG. 10D, when the temperature feedback control is performed, the peak value C of the alternating current changes and the period D becomes indefinite, but as shown in FIG. 10C, the heating of the induction heating coil 405 is performed. Since the same magnetic flux A in the opposite direction is generated on both sides around the target portion 405a and the equal electromagnetic force B in the opposite direction is always generated and offset in the brazing material 403, the brazing material 403 is in a predetermined position. Residual and hopping phenomenon can be prevented.

Japanese Patent No. 2923916 JP-A-10-216930

  However, since the conventional horseshoe coil structure is bent into a U shape or a C shape, the generated magnetic flux density is smaller than that of a completely wound solenoid type coil structure. Even when two or more turns are used to increase the magnetic flux density, there are upper and lower transfer portions where current flows in opposite directions in the horizontal direction with respect to the metal tube, so that the magnetic flux generated at each transfer portion is offset. , Heating efficiency deteriorates. Further, the distribution of magnetic flux becomes non-uniform, and in the case of aluminum brazing where the difference in melting point between the base material and the brazing material is very small, it is difficult to ensure the quality of brazing by uniform heating.

  The present invention solves the above-mentioned conventional problems, and the melting point difference between the base material and the brazing material is very small like brazing of aluminum, and even when temperature feedback control is performed, heating efficiency and uniform heating are achieved. It is an object to provide an induction heating coil and a heating method capable of satisfying both of the above.

In order to achieve the above object, according to the induction heating coil according to one aspect of the present invention, a high frequency is generated by electromagnetic induction, and the end of the first metal tube having a large outer diameter is formed on the heating target portion. In the induction heating coil that brazes by placing a brazing material at the connection portion with the end of the second metal tube having a smaller outer diameter than the first metal tube, and heating at high frequency,
On both sides of each of the first and second metal tubes, two or more turns are formed in opposite directions, and a connecting portion that connects the turns is a second metal rather than the first metal tube. Can be placed on the tube side.

Moreover, in order to achieve the said objective, according to the heating method concerning another aspect of this invention, a high frequency is generated by electromagnetic induction and the edge part of the 1st metal tube with a large outer diameter dimension is made into a heating object part. And a heating method using an induction heating coil in which brazing material is disposed at a connection portion between the first metal tube and the end of the second metal tube having a smaller outer diameter than the first metal tube, and brazing by high frequency heating In
Two or more turns of the induction heating coil are arranged in opposite directions on both sides of the first and second metal tubes, and a connecting portion connecting the respective turns is more than the first metal tube. Arranged on the second metal tube side,
Thereafter, an electric current is supplied to the induction heating coil, and the connecting portion between the end of the first metal tube and the end of the second metal tube is heated at a high frequency to braze with the brazing material.

  As described above, the induction heating coil and the heating method according to the above aspect of the present invention have a very small melting point difference between the base material and the brazing material, such as brazing of aluminum, and even when temperature feedback control is performed. It is possible to achieve both efficiency and uniform heating, and it is possible to provide a small coil capable of ensuring brazing quality with a short tact time.

The block diagram in the state which has arrange | positioned the induction heating coil concerning 1st Embodiment of this invention in the heating target object. Configuration view of induction heating coil viewed from the side Configuration view of induction heating coil from above Configuration view of induction heating coil from the front Explanatory drawing which shows the process of the joining method of the metal tube by the induction heating coil concerning 1st Embodiment of this invention. Explanatory drawing which shows the process of the joining method of the metal tube by the induction heating coil concerning 1st Embodiment of this invention. Explanatory drawing which shows each process of the joining method of the metal pipe by the induction heating coil concerning 1st Embodiment of this invention. Explanatory drawing which shows each process of the joining method of the metal pipe by the induction heating coil concerning 1st Embodiment of this invention. Explanatory drawing which shows each process of the joining method of the metal pipe by the induction heating coil concerning 1st Embodiment of this invention. The schematic diagram when performing temperature feedback control with the induction heating coil concerning 1st Embodiment of this invention Current waveform diagram when temperature feedback control is performed by the induction heating coil according to the first embodiment of the present invention. The figure which shows the setting parameter of the induction heating coil concerning 1st Embodiment of this invention. The figure which shows the setting parameter of the induction heating coil concerning 1st Embodiment of this invention. The figure which shows the setting parameter of the induction heating coil concerning 1st Embodiment of this invention. The graph of the simulation result by the setting parameter of the induction heating coil concerning 1st Embodiment of this invention The graph of the simulation result by the setting parameter of the induction heating coil concerning 1st Embodiment of this invention The block diagram of the induction heating coil concerning 2nd Embodiment of this invention. The block diagram of the induction heating coil concerning 2nd Embodiment of this invention. The block diagram of the induction heating coil concerning 2nd Embodiment of this invention. The block diagram of the induction heating coil concerning 2nd Embodiment of this invention. Explanatory drawing which shows the process of the joining method of the metal pipe by the conventional induction heating Explanatory drawing which shows the process of the joining method of the metal pipe by the conventional induction heating Explanatory drawing which shows the process of the joining method of the metal pipe by the conventional induction heating Explanatory drawing which shows the process of the joining method of the metal pipe by the conventional induction heating Explanatory drawing which shows the process of the joining method of the metal pipe by the conventional induction heating Schematic diagram when temperature feedback control is not performed with a conventional induction heating coil Current waveform diagram when temperature feedback control is not performed with a conventional induction heating coil Schematic diagram when performing temperature feedback control with a conventional induction heating coil Current waveform diagram when performing temperature feedback control with a conventional induction heating coil Schematic diagram when performing temperature feedback control with a conventional induction heating coil (horse-shoe coil) Schematic diagram when performing temperature feedback control with a conventional induction heating coil (horse-shoe coil) Schematic diagram when performing temperature feedback control with a conventional induction heating coil (horse-shoe coil) Current waveform diagram when performing temperature feedback control with a conventional induction heating coil (horse-shoe coil)

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the same element, the same code | symbol is attached | subjected and description may be abbreviate | omitted.

(First embodiment)
FIG. 1A is a diagram showing a configuration of an induction heating apparatus used in the heating method according to the first embodiment of the present invention, that is, an induction heating coil 100 for brazing two metal tubes 102 and 104. Moreover, FIG. 1B is the block diagram which looked at the induction heating coil 100 from the side surface. FIG. 1C is a configuration diagram of the induction heating coil 100 as viewed from above. FIG. 1D is a configuration diagram of the induction heating coil 100 as viewed from the front. 2A to 2E are explanatory views showing each step of the method for joining two metal tubes 102 and 104 according to the first embodiment of the present invention.

  The induction heating coil 100 arranges a brazing part 90a of the heating object 90 in a heating target part (heating target space or heating target area) 100a, generates high frequency by electromagnetic induction, performs high frequency heating and brazing. Is.

  The heating coil 100 can be disposed on both sides of the heating object 90 and is electrically connected to the surrounding portions 105a and 105b formed in two or more opposite directions with the same opening area, and the surrounding portions 105a and 105b. It is comprised with the transfer part 106 connected so that it may make. The induction heating coil 100 is formed of, for example, a copper pipe, and cooling water 107 flows inside the copper pipe.

  As an example of the heating object 90, an end portion of the heat transfer tube 102 as an example of a first metal tube having a large outer diameter and a joint as an example of a second metal tube having a smaller outer diameter than the first metal tube It is comprised by the edge part of the pipe | tube 104, and the ring-shaped brazing material 103 arrange | positioned at the edge part of the heat exchanger tube 102. FIG. A tube expansion portion 101 is formed at an opening end portion that is an end portion of the heat transfer tube 102. At the time of joining, a ring-shaped brazing material 103 and an end portion on the connection side of the joint pipe 104 are disposed as a brazing portion 90 a in the pipe expanding portion 101.

  Therefore, when arranging and joining the brazing part 90a of the heating object 90 of the two metal tubes 102 and 104 and the brazing material 103 to the heating object part 100a of the induction heating coil 100 of the first embodiment, The arrangement is as follows. That is, as shown in FIG. 1A, a heat transfer tube 102 in which a tube expansion portion 101 is formed at an opening end portion in a heating target portion 100 a of the heating coil 100, and a ring-shaped brazing material 103 and a joint tube 104 on the tube expansion portion 101. Place. At this time, around the heating target portion 100a where the ring-shaped brazing material 103 is arranged, the surrounding portions 105a and 105b of the heating coil 100 are arranged on both sides of the heating target portion 100a, and the respective surrounding portions 105a, The transfer part 106 which connects 105b is comprised so that arrangement | positioning is possible at the coupling pipe 104 side whose outer diameter is smaller than the heat exchanger tube 102. FIG. In this arrangement state, if a current is passed through the heating coil 100, a high frequency can be generated in the heating coil 100 by electromagnetic induction, and the heat transfer tube 102 and the joint tube 104 are connected via the ring-shaped brazing material 103. Thus, high-frequency brazing can be performed.

  Specifically, the joining of the metal tubes 102 and 104 as an example of the heating object 90 using the induction heating coil 100 is performed by the following processes of FIGS. 2A to 2E.

  First, as shown in FIG. 2A, a tube expansion portion 101 is formed at the opening end portion of the heat transfer tube 102.

  Next, as shown in FIG. 2B, a ring-shaped brazing material 103 and a joint pipe 104 are arranged in the expanded pipe portion 101 formed at the open end of the heat transfer tube 102.

  Next, as shown in FIG. 2C, preparation is performed for high-frequency brazing using the induction heating coil 100 between the heat transfer tube 102 and the joint tube 104 via the ring-shaped brazing material 103. That is, with the same opening area of the induction heating coil 100 as the center, the winding portion 90a in which the ring-shaped brazing material 103 between the heat transfer tube 102 and the joint tube 104 is arranged is wound around two turns. 105a and 105b are arranged, and the transfer part 106 which connects each circumference part 105a and 105b can be arrange | positioned to the joint pipe 104 side whose outer diameter is smaller than the heat exchanger tube 102 (proximity arrangement | positioning is possible). For this reason, the space | interval of the transfer part 106 is taken as the dimension of the extent a little larger than the coupling pipe 104. The interval between the transfer portions 106 may be smaller than the diameter of the heat transfer tube 102 because the joint tube 104 may be inserted.

  Next, as shown in FIG. 2D, by applying an electric current to the induction heating coil 100 in such an arrangement state, the heat transfer tube 102 and the joint tube 104 are heated, and the ring-shaped brazing material 103 is melted. A fillet is formed, and the brazing material 103 wraps around the gap between the heat transfer tube 102 and the joint tube 104 from the expanded portion 101. At this time, temperature feedback control by PID control is performed using a non-contact radiation thermometer so that the temperature measurement spot 108 follows a predetermined temperature profile.

  Next, as shown in FIG. 2E, by stopping the application of current and removing the induction heating coil 100 from the heating object 90, the brazing material 103 is cooled, and the heat transfer tube 102 and the joint tube 104 are joined. be able to.

  At this time, the heat transfer tube 102 is, for example, an aluminum tube (melting point: 660 ° C.) having a diameter of 8 mm and a thickness of 0.8 mm. For example, the joint pipe 104 is an aluminum pipe having a diameter of 7 mm and a thickness of 0.8 mm. As an example, the ring-shaped brazing material 103 is aluminum brazing (melting point 580 ° C.) having a diameter of Φ1 mm. The induction heating coil 100 is formed of a copper pipe having a diameter of 3 mm, and the diameter of each of the circulating portions 105a and 105b is 20 mm.

  In this case, as shown in FIG. 3B, when temperature feedback control is performed, the peak value C of the alternating current changes and the period D becomes indefinite. However, as shown in FIG. 3A, the magnetic flux A in the reverse direction is always generated in each of the circulating portions 105a and 105b of the induction heating coil 100, and the equal electromagnetic force B in the reverse direction is always generated in the brazing material 103 to be offset. The For this reason, the hopping phenomenon is suppressed, and the brazing material 103 can remain at a predetermined position (heating target portion 100a) with respect to the induction heating coil 100.

  At this time, as an example, it is assumed that the output of the induction heating power supply 80 (see FIG. 1C) that supplies current to the induction heating coil 100 is 5 kW and the frequency is 300 kHz. Here, after applying power, set the temperature profile at the temperature measurement spot 108 of the non-contact thermometer so that the brazing part 90a is heated to 600 ° C. in 7 seconds, and perform temperature feedback control by PID control, High-frequency brazing is performed by melting and infiltrating a ring-shaped brazing material.

  Although the hopping phenomenon can be suppressed by the induction heating coil 100 as described above, when aluminum is used as the material of the metal tubes 102 and 104, the temperature range to be controlled during brazing is different from that of other metals. Since it becomes very narrow compared with the case where the material is used, in order to perform brazing without breaking the metal tubes 102 and 104, it is required to control the brazing portion 90a in a very narrow temperature range (about 80 ° C.). It is done. For this reason, it is necessary to devise the shape and arrangement of the induction heating coil 100 in consideration of the structure of the metal tubes 102 and 104. Therefore, the shape and arrangement conditions to be satisfied by the induction heating coil 100 are derived using simulation. Hereinafter, after describing the parameters of the coil structure, the shape and arrangement conditions of the induction heating coil 100 that realizes brazing without causing a hopping phenomenon by simulation will be described.

  First, parameters of the induction heating coil will be described with reference to FIGS. 4A and 4B. 4A, the outer diameters of the circumferential portions 105a and 105b of the induction heating coil 100 in the longitudinal direction of the metal tube are X, the end surface of the ring-shaped brazing material 103 on the heat transfer tube 102 side, and the circumferential portions 105a and 105b of the induction heating coil 100. The distance from the central axis is defined as Z. Moreover, in FIG. 4B, the inclination angle of the transfer part 106 of the surrounding parts 105a and 105b of the induction heating coil 100 is defined as θ.

  The effects of these parameters on the hopping phenomenon and heating characteristics were evaluated by simulation. As a simulation tool, the electromagnetic field / thermal coupled analysis function of JMAG-Designer Ver 13.1.02 g (JSOL Corporation) was used. An analysis model equivalent to the induction heating coil shown in FIG. 1A was created, and the shape of the metal tube and the ring-shaped brazing material was fixed. In addition, for the induction heating coil, parameters having no effect on suppressing the hopping phenomenon were analyzed with fixed values.

  Here, as an example, the length of the joint tube 104 is 63 mm, the diameter is 7 mm, and the wall thickness is 1 mm, and the length of the heat transfer tube 102 is 56 mm, the diameter is 7 mm, and the wall thickness is 1 mm. Further, as an example, the pipe expanding portion 101 has a diameter Φ12 mm and the ring-shaped brazing material 103 has a wire diameter Φ1.6 mm and a ring inner diameter Φ6.9 mm. The area to be heated with respect to the object to be heated 90 was set to a range of 15 mm before and after the joined portion (the brazed portion 90a) of the heat transfer tube 102 and the joint tube 104.

  The induction heating coil parameters were fixed as follows. The distance between the induction heating coil and the metal tube was 2.85 mm, the outer diameter of the circumference of the induction heating coil was 20 mm, the pitch was 0.5 mm, and the number of turns was 2.

  In the analysis, the parameter of the relative position of the induction heating coil to the brazing material was varied to suppress the hopping phenomenon and obtain conditions for brazing. In the brazing performed in the experiment, when the time when the minimum temperature of the brazing part of the metal tube reaches the melting point 600 ° C. of the brazing material is less than 2.5 seconds, the heating rate of the heating target part is too high. When the metal tube broke and took more than 3.5 seconds, the rate of temperature increase was too slow and the brazing material was not melted or insufficiently penetrated. For this reason, in this analysis, when the arrival time is 2.5 seconds or more and 3.5 seconds or less and the distance Z between the brazing material in FIG. 4A and the central axis of the circulating portion of the induction heating coil is 0 mm, Assuming that the electromagnetic force is 1, the parameter range when the ratio of the electromagnetic force received by the brazing material when the relative position is changed to 1 or less is the condition derived this time.

  FIG. 5A plots the parameter of the inclination angle θ of the transfer section 106 of the circulating sections 105a and 105b of the induction heating coil 100, and plots each value in the same graph. The time for the lowest temperature of the brazing portion 90a to reach the melting point 600 ° C. of the brazing material 103 is 2.5 seconds or more and 3.5 seconds or less if the inclination angle θ is −30 ° or more and + 25 ° or less. The hopping phenomenon can be suppressed and brazing can be performed. At this time, the ratio of the electromagnetic force received by the brazing material 103 was always 1 or less.

  Further, FIG. 5B shows that the outer diameter in the metal tube longitudinal direction of the surrounding portions 105a and 105b of the induction heating coil 100 is X, and the distance between the ring-shaped brazing material 103 and the central axis of the surrounding portions 105a and 105b of the induction heating coil 100. The parameter of the ratio Z / X where Z is Z is assigned, and each value is plotted on the same graph. The ratio of the electromagnetic force received by the brazing material 103 to 1 or less is that if the ratio Z / X is 5% or less, the hopping phenomenon is suppressed and brazing is possible. The ratio Z / X is 5% or less, in other words, the distance Z between the brazing material 103 arranged in the heating target portion 100a and the central axis of the surrounding portions 105a and 105b is equal to the outer diameter X of the surrounding portions 105a and 105b. In contrast, it means within ± 5%. At this time, the time for the lowest temperature of the brazing portion 90a to reach the melting point 600 ° C. of the brazing material 103 was always 2.5 seconds or more and 3.5 seconds or less.

  In FIG. 4C, the distance between the connecting portion 106 connecting the circulating portions 105a and 105b of the induction heating coil and the joint pipe 104 is always constant, that is, the shortest distance to the joint pipe 104 is constant at any position of the connecting portion 106. Thus, the joint pipe 104 can be heated evenly. At this time, the transfer unit 106 has a semicircular or semi-elliptical shape. In general, when the length of the major axis of the ellipse is A and the length of the minor axis is B, the length LD of the ellipse is

で表される。よって、渡し部１０６と継手管１０４の中心との距離をα、渡し部１０６の水平方向（例えば、ロウ材の加熱対象面、又は、周回部１０５ａ、１０５ｂの中心軸方向と継手管１０４の中心軸方向との両方に直交する方向）に対する傾き角度をθとすると、渡し部１０６の長さＬＷは、

It is represented by Therefore, the distance between the transfer part 106 and the center of the joint pipe 104 is α, and the horizontal direction of the transfer part 106 (for example, the surface to be heated of the brazing material or the center axis direction of the circulating parts 105a and 105b and the center of the joint pipe 104) When the inclination angle with respect to the direction perpendicular to both the axial direction is θ, the length LW of the transfer portion 106 is

で表される。例えば、継手管１０４の直径Φを７ｍｍ、周回部１０５ａ、１０５ｂと継手管１０４との距離を２．８５ｍｍとしたとき、α＝６．３５ｍｍとなり、
α＝６．３５ｍｍ、θ＝０°のとき、ＬＷ≒１９．９ｍｍ
α＝６．３５ｍｍ、θ＝−３０°のとき、ＬＷ≒２１．５ｍｍ
となる。

It is represented by For example, when the diameter Φ of the joint pipe 104 is 7 mm and the distance between the circulating portions 105a and 105b and the joint pipe 104 is 2.85 mm, α = 6.35 mm.
When α = 6.35 mm and θ = 0 °, LW≈19.9 mm
When α = 6.35 mm and θ = −30 °, LW≈21.5 mm
It becomes.

  According to such a configuration, the induction heating coil 100 acts so as to cancel the axial electromagnetic force generated on the ring-shaped brazing material 103 of the brazing portion 90 a, and the hopping phenomenon does not occur. The effect of preventing quality defects such as unmelted, insufficient filling and insufficient penetration can be obtained. Therefore, the melting point difference between the base material and the brazing material 103 is very small like brazing of aluminum, and even when temperature feedback control is performed, it is possible to achieve both heating efficiency and uniform heating, with a short tact and brazing quality. Can be provided.

(Second Embodiment)
FIG. 6A is a configuration diagram of an induction heating coil 100B for brazing the metal tubes 202 and 204 according to the second embodiment of the present invention. FIG. 6B is a configuration diagram viewed from the side of the induction heating coil 100B. FIG. 6C is a configuration diagram viewed from the back surface of the induction heating coil 100B. FIG. 6D is a configuration diagram viewed from above the induction heating coil 100B. The induction heating coil 100B is formed of a copper pipe as an example, and cooling water 207 flows inside the copper pipe.

  The induction heating coil 100B is greatly different from the first embodiment in that the transfer portion 206 is compared to the end portions of the first and second metal tubes 202 and 204 arranged in the heating target portion 100Ba and the brazing material 203. That is, two or more turns are connected in parallel. Specifically, the transfer unit 206 is branched into a first branch unit 206a and a second branch unit 206b where the transfer unit 206 is connected to each of the circulation units 205a and 205b, and a metal tube end disposed in the heating target unit 100Ba. Two turns of the brazing material 203 are connected in parallel. Here, two turns of parallel connection are illustrated, but a plurality of turns connected in parallel over three turns or more may be used.

  The heating coil 100B can be disposed on both sides of the object to be heated 90, and is electrically connected to the surrounding portions 205a and 205b formed in two or more turns in the opposite direction with the same opening area, and the surrounding portions 205a and 205b. The transfer section 206 is connected to the first branch section 206a and branched to the second branch section 206b.

  Therefore, when the brazing portion 90a of the heating object 90 of the two metal tubes 202 and 204 and the brazing material 203 is arranged and joined to the heating target portion 100Ba of the induction heating coil 100B of the second embodiment, The arrangement is as follows. That is, as shown in FIG. 6A, a heat transfer tube 202 in which a tube expansion portion 201 is formed at the opening end portion in the heating target portion 100Ba of the heating coil 100B, and a ring-shaped brazing material 203 and a joint tube 204 in the tube expansion portion 201. Place. At this time, around the heating target part 100Ba on which the ring-shaped brazing material 203 is arranged, the surrounding parts 205a and 205b of the heating coil 100B are arranged on both sides of the heating target part 100Ba, and the surrounding parts 205a, The transfer part 206 which connects 205b is arrange | positioned at the joint pipe 204 side whose outer diameter is smaller than the heat exchanger tube 202. FIG. In this arrangement state, if a current is passed through the heating coil 100B, a high frequency can be generated in the heating coil 100B by electromagnetic induction, and the heat transfer tube 202 and the joint tube 204 are connected via the ring-shaped brazing material 203. Thus, high-frequency brazing can be performed.

  The joining of the metal tubes 202 and 204 as an example of the heating object 90 using the induction heating coil 100B is performed by connecting the end portions of the metal tubes 202 and 204 having different outer diameters and the brazing material 203 to the heating target portion 100. This is performed in the same manner as in the first embodiment, using the induction heating coil 100B that is arranged and heated at high frequency for brazing.

  At this time, since the current flowing through each transfer portion 206 is branched into the first branch portion 206a and the second branch portion 206b and the generated magnetic field is dispersed, the heating of the joint pipe 204 is also dispersed, and the temperature distribution is reduced. It becomes possible to adjust.

  According to such a configuration, the induction heating coil 100B acts so as to cancel the axial electromagnetic force generated on the ring-shaped brazing material 203 of the brazing portion 90a, and the hopping phenomenon does not occur. Therefore, aluminum is used as the metal tube material, and the melting point difference between the base material and the brazing material 203 is very small as in the case of brazing aluminum, so that both heating efficiency and uniform heating can be achieved even when heating by temperature feedback control is performed. Thus, an effect of preventing quality defects such as unmelting, insufficient filling, and insufficient penetration of the brazing material 203 can be obtained.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably. In addition, combinations of the embodiments, combinations of the examples, or combinations of the embodiments and examples are possible, and combinations of features in different embodiments or examples are also possible.

  The induction heating coil and heating method of the present invention have a very small melting point difference between the base material and the brazing material as in the case of aluminum brazing, and it is possible to achieve both heating efficiency and uniform heating even when performing temperature feedback control. It can also be applied to metal tube heating applications such as brazing or quenching of heat exchangers used in air conditioners such as air conditioners.

DESCRIPTION OF SYMBOLS 80 Induction heating power supply 90 Heating object 90a Brazing part 100 Induction heating coil is 100a Heating object part 101,201 Expanded pipe part 102,202 Heat-transfer pipe 103,203 Brazing material 104,204 Joint pipe 105a, 105b, 205a, 205b Circulation part 106, 206 Transfer section 206a First branch section 206b Second branch section 107, 207 Cooling water 108 Temperature measurement spot

Claims (6)

A high frequency is generated by electromagnetic induction, and a heating target portion is connected to a connection portion between an end portion of the first metal tube having a large outer diameter and an end portion of the second metal tube having a smaller outer diameter than the first metal tube. In an induction heating coil in which brazing material is arranged and brazed by high frequency heating,
On both sides of each of the first and second metal tubes, two or more turns are formed in opposite directions, and a connecting portion that connects the turns is a second metal rather than the first metal tube. An induction heating coil that can be placed on the tube side.   The said transfer part is connected in parallel by two or more turns with respect to the said edge part and the said brazing | wax material of the said 1st and 2nd metal tube which are arrange | positioned at the said heating object part. Induction heating coil.   The induction heating coil according to claim 2, wherein an inclination angle of the transfer portion with respect to a heating target surface of the brazing material is -30 ° or more and + 25 ° or less.   The induction heating according to claim 2 or 3, wherein a distance between the brazing material arranged in the heating target portion and a central axis of the circulating portion is within ± 5% with respect to an outer diameter of the circulating portion. coil. The shortest distance between the transfer portion and the second metal tube is constant, the distance between the transfer portion and the center of the second metal tube is α, and the inclination of the transfer portion with respect to the surface to be heated of the brazing material When the angle is θ, the length LW of the passing portion is

The induction heating coil as described in any one of Claims 1-4 represented by these. A high frequency is generated by electromagnetic induction, and a heating target portion is connected to a connection portion between an end portion of the first metal tube having a large outer diameter and an end portion of the second metal tube having a smaller outer diameter than the first metal tube. In a heating method in which a brazing material is placed and an induction heating coil that brazes by high-frequency heating is used,
Two or more turns of the induction heating coil are arranged in opposite directions on both sides of the first and second metal tubes, and a connecting portion connecting the respective turns is more than the first metal tube. Arranged on the second metal tube side,
Thereafter, an electric current is supplied to the induction heating coil, and the connection portion between the end of the first metal tube and the end of the second metal tube is heated at a high frequency to braze with the brazing material. Method.

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