JP2914599B2 - Work coil for high frequency power supply - Google Patents

Abstract

PURPOSE:To improve attaching/detaching performance, reduce leakage flux, and improve heating efficiency, by providing a work coil which generates high- frequency current in a magnetic alloy heater by induction with a coil mat which is curved in a circumferential direction. CONSTITUTION:This work coil 10 for high-frequency power supply, which is used for fusion of a plastic pipe or the like, contains a coil mat 12 of roughly C-shape. The coil mat 12 is provided with a core 14 made of heat resistant resin such as polycarbonate, a loop which consists of an inducting body 16 is formed on its external surface, and a ferritic layer 22 and a casing 24 made of aluminum or the like are formed at its outside. In connecting pipes 38, 38 with each other, the respective pipes 38 are inserted in the socket of a joint 30 formed with a magnetic alloy heater 36 on its internal circumferential surface side, and the inducing body 16 is energized through terminals 30a, 30b by a high-frequency power supply 34, so that the heater 36 is inductively-heated to fusion-connect both the coupler and the pipes 30, 38 with each other at their connected surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work coil for a high-frequency power supply, and more particularly to a work coil for a high-frequency power supply used, for example, for welding plastic pipes using high-frequency induction heating.

[0002]

2. Description of the Related Art An example of a work coil for a high-frequency power supply for fusing and joining plastic pipes by utilizing high-frequency induction heating is disclosed in International Publication WO92 / 15182. This work coil has a joint sandwiched between two coil mats.

[0003]

The conventional work coil has a problem that it is difficult to manufacture the work coil because it is necessary to form two coil mats. In addition, since the entire device is large and has a structure in which the joint is sandwiched between two coil mats, there is a problem that the detachability from the joint is poor.

[0004] Therefore, a main object of the present invention is to provide a work coil for a high-frequency power supply, which can be easily manufactured and can be improved in detachability.

[0005]

A first invention is a work coil for a high-frequency power supply for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin. A work coil for a high-frequency power supply, including one coil mat including a wound conductor, the coil mat being wound in a circumferential direction.

A second invention is a high-frequency power supply work coil for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, wherein the conductor coil is wound around a predetermined loop. And a ferrite layer formed on the outside of the coil mat. The third invention is
A high-frequency power supply work coil for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, wherein the coil mat includes a conductor forming first and second portions having different diameters. A work coil for a high-frequency power supply.

A fourth invention is a high-frequency power supply work coil for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, the work coil having a first portion extending in a circumferential direction and an axial direction. A work coil for a high-frequency power supply, comprising: a coil mat including a conductor that forms a loop with a second portion extending to the first portion, wherein the first portion and the second portion are formed in the same cylindrical plane.

[0008]

According to the first aspect of the invention, since only one coil mat needs to be formed, it can be easily manufactured. Further, if the coil mat is formed in a C shape or a U shape, it can be easily attached and detached around the joint. According to the second aspect, since the ferrite layer is formed outside the coil mat, the magnetic flux can be guided into the ferrite layer. Therefore, the leakage magnetic flux can be reduced.

According to the third aspect of the invention, by selecting and using one of the first portion and the second portion having different diameters, the present invention can be applied to two types of joints having different diameters. 4th
According to the invention, since the first portion extending in the circumferential direction and the second portion extending in the axial direction of the loop formed by the conductor are formed in the same cylindrical surface, the size can be reduced.

[0010]

According to the first aspect of the invention, it can be easily manufactured,
Moreover, the detachability can be improved. According to the second aspect, since the leakage magnetic flux can be reduced, the heating efficiency can be improved. According to the third invention, since it can be applied to two types of joints having different diameters,
Workability can be improved.

According to the fourth aspect, since the size can be reduced, the cost can be reduced and the workability can be improved. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0012]

1 and 2, a high-frequency power supply work coil 10 of this embodiment includes one coil mat 12 (FIG. 2) having a substantially C shape. The coil mat 12 is made of, for example, a core 1 made of a heat-resistant resin such as polycarbonate.
4, a loop 18 or 20 is formed on the outer surface of the core 14 by the conductor 16, for example, as shown in FIG. 3 or FIG. 4. A ferrite layer 22 is formed outside the coil mat 12 (conductor 16),
Outside the ferrite layer 22, a casing 24 made of aluminum or the like is formed so as to cover the coil mat 12 and the ferrite layer 22. Ferrite layer 22
May be formed by sintering, attaching a ferrite tile, or the like, or may be formed as a synthetic resin layer mixed with ferrite powder. The casing 24 is divided into a first portion 24a and a second portion 24b so that the opening 26 (FIG. 1) of the coil mat 12 can be enlarged.
4a and the second portion 24b are connected via a hinge 28. However, when the opening 26 is wider than the outer diameter of the joint 30 (FIG. 2), it is not always necessary to divide the casing 24.

On the upper part of the casing 24, there are formed terminals 30a and 30b each connected to the end of the conductor 16, and a handle 32 is provided between the terminals. And
A high frequency power supply 34 (FIG. 2) is connected to terminals 30a and 30b. At the time of joining, as shown in FIG. 2, a joint 30 provided with a magnetic alloy heater 36 near its inner peripheral surface is prepared, a pipe 38 to be joined is inserted into a socket of the joint 30, and a work is attached to the joint 30. Put the coil 10 on. Then, the switch of the high-frequency power supply 34 is turned on to energize the conductor 16, thereby applying a high-frequency current to the heater 36. Then, the heater 36 rapidly generates heat in the skin portion where the current is concentrated by the skin effect. When the temperature of the heater 36 rises to reach the Curie temperature, the magnetic permeability of the heater 36 is greatly reduced, and almost no skin current flows, and the heater 36
Greatly reduces heat generation. Heater 3 by heat radiation etc.
When the temperature of 6 decreases, the heater 36 generates heat again by the skin current. In this way, since the heater 36 is maintained at the predetermined Curie temperature, the bonding surface is heated to or near the predetermined Curie temperature, that is, the optimum fusion temperature,
It is fused.

The present inventors applied the work coil 10 to a magnetic alloy heater 40 (φ60) as shown in FIGS. 5 and 6 and measured the temperature change of each part a to e to thereby obtain the work coil 10. The practicality was verified. FIG. 7 is a graph in which the abscissa represents the energization time and the ordinate represents the measured temperatures of the respective portions a to e. From this graph, it was confirmed that even when the opening 26 was provided, the entire magnetic alloy heater 40 could be heated substantially uniformly.

According to this embodiment, since the open portion 26 is provided in the coil mat 12, the work coil 10 can be easily attached and detached and the workability can be improved. Also,
Since the ferrite layer 22 is formed outside the coil mat 12, magnetic flux can be guided into the ferrite layer 22. Therefore, the leakage flux can be reduced,
Thereby, efficiency can be improved and radiation noise can be reduced.

When the loop 18 (FIG. 3) is formed, there is a possibility that the magnetic flux is canceled out at the center of the loop 18. Therefore, the center A (FIG. 2) of the work coil 10 has a higher relative permeability than the others. It is also possible to use a high ferrite and concentrate the magnetic flux on that portion to prevent the cancellation of the magnetic flux. By the way, the relative magnetic permeability of the central part A is 25.
The relative magnetic permeability of the other parts was about 250.

Further, a stopper 42 as shown in FIG. 8 or a stopper 44 as shown in FIG. 9 may be formed so that the work coil 10 can be reliably positioned on the pipe 38 to be joined. Further, as shown in FIG. 10, for example, the lower end of the work coil 10 is folded outward, and the loop 18 (FIG. 3) or the loop 20 (FIG. 4)
By disposing a portion extending in the axial direction, disturbance of the magnetic field may be prevented.

The shape of the work coil 10 is not limited to the C shape as in the above-described embodiment, but may be formed into a U shape as shown in FIG. 11 or FIG. Work coil 4 of another embodiment shown in FIG.
Reference numeral 8 denotes a body formed with a loop 18 (FIG. 3) or 20 (FIG. 4) in a main body 50 made of a soft material such as ferrite rubber, and is used by being bent to an arbitrary curvature.

In each of the above embodiments, the conductor 16
Although the case where the loop 18 (FIG. 3) or 20 (FIG. 4) is formed is shown in FIG. 14, when the present invention is applied to a joint 52 having a socket only on one side as shown in FIG. Instead of 20, a loop 54 or 56 as shown in FIG. 15 or FIG. 16 may be formed. Also in this case, by using ferrite having a higher relative magnetic permeability than the others in the intermediate portion B (FIG. 14) between the work portion and the discarded winding portion, the cancellation of the magnetic flux can be prevented. Note that the loop 56 has a discarded winding part C (FIG. 16).
Is doubly wound.

A work coil 58 according to another embodiment shown in FIGS. 17 and 18 is intended to be applied to two types of single-receiving joints having different diameters, and a first portion 60 and a second portion 62 having different diameters. And a coil mat 64 having the following. The coil mat 64 includes a core 66, and a loop 18 or 20 as shown in FIG. 3 or FIG. 4 is formed on the outer surface of the core 66 by the conductor 16. The ferrite layer 22 is formed outside the coil mat 64 in the same manner as in the above-described embodiment (FIG. 2), and the casing 24 is formed outside the ferrite layer 22.

At the time of joining, one of the first portion 60 and the second portion 62 is selected according to the diameter of the joint to be joined. That is, when applied to the large-diameter joint 68, as shown in FIG. 17, fusion is performed using the first portion 60, and when applied to the small-diameter joint 70, as shown in FIG. The second portion 62 is used for fusion. When applied to the small-diameter joint 70, the adapter 72 is attached to the inner surface of the first portion 60.

According to this embodiment, since one work coil 58 can be applied to two types of single-receiving joints having different diameters, it is not necessary to prepare a work coil for each type of joint, and the workability can be improved. In this embodiment, one C-shaped or U-shaped coil mat as described above may be used, or a structure in which a joint is sandwiched between two coil mats as in the related art may be used.

The idea of reducing the magnetic flux loss by forming the ferrite layer on the outside of the coil mat can be applied to the conventional work coil disclosed in International Publication WO92 / 15182. Further, the present invention can also be applied to a work coil 78 (a ferrite layer is not shown) having two coil mats 74 and 76 as shown in FIG. In the work coil 78,
Since the first portion extending in the circumferential direction and the second portion extending in the axial direction of the loop formed by the conductor 16 are formed in the same cylindrical surface, the portion of the conductor extending in the axial direction is formed in the cylindrical surface. There is an advantage that the size can be reduced as compared with a conventional work coil removed from the inside.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing the embodiment of FIG.

FIG. 3 is an illustrative view showing a loop applied to the embodiment in FIG. 1;

FIG. 4 is an illustrative view showing another loop applied to the embodiment in FIG. 1;

FIG. 5 is an illustrative view showing an experimental method for verifying the practicality of the embodiment in FIG. 1;

FIG. 6 is an illustrative view showing an experimental method for verifying practicality of the embodiment of FIG. 1;

FIG. 7 is a graph showing the experimental results of FIG.

FIG. 8 is a perspective view showing a state where a stopper is provided in the embodiment of FIG. 1;

FIG. 9 is a perspective view showing a state where a stopper is provided in the embodiment of FIG. 1;

FIG. 10 is a perspective view showing a state where a folded portion is provided in the embodiment of FIG. 1;

FIG. 11 is a perspective view showing a state where the whole is formed in a U shape.

FIG. 12 is a perspective view showing a state where a folded portion is formed in the embodiment of FIG. 11;

FIG. 13 is an illustrative view showing a work coil including a main body formed of a soft material;

FIG. 14 is an illustrative view showing a state in which the embodiment of FIG. 1 is applied to a one-sided joint;

FIG. 15 is an illustrative view showing a loop applied in FIG. 14;

FIG. 16 is an illustrative view showing another loop applied in FIG. 14;

FIG. 17 is an illustrative view showing another embodiment of the present invention;

FIG. 18 is an illustrative view showing a state where the embodiment of FIG. 16 is applied to a small-diameter joint;

FIG. 19 is a perspective view showing a work coil having two coil mats.

[Explanation of symbols]

 10, 48, 58 ... Work coil 12 ... Coil mat 14 ... Core 16 ... Conductor 18, 20, 54, 56 ... Loop 22 ... Ferrite layer 24 ... Casing 26 ... Opening part 30, 52, 68, 70 ... Joint 36, 40 ... magnetic alloy heater

──────────────────────────────────────────────────続 き Continuing from the front page (72) Kozo Nishikawa 1-1-1, Hama, Amagasaki-shi, Hyogo Prefecture Inside Kubota Research Institute of Technology (72) Inventor Masayuki Kanda 1-1-1, Hama, Amagasaki-shi, Hyogo Shares (56) References JP-A-63-272535 (JP, A) JP-A-56-119738 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16L 41/00-41/08

Claims (6)

(57) [Claims] 1. A work coil for a high-frequency power supply for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, the work coil including a conductor wound around a predetermined loop. A work coil for a high-frequency power supply, comprising a coil mat, wherein the coil mat is wound in a circumferential direction. 2. The high frequency power supply work coil according to claim 1, wherein said coil mat is formed only in a part in a circumferential direction. 3. A work coil for a high-frequency power supply for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, the coil mat including a conductor wound around a predetermined loop. ,
A work coil for a high-frequency power supply, comprising: a ferrite layer formed outside the coil mat. 4. The work coil for a high-frequency power supply according to claim 3, wherein the relative permeability of a part of the ferrite layer is higher than that of the other part, and a magnetic flux is guided to the part. 5. A work coil for a high-frequency power supply for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, wherein the conductor forms first and second portions having different diameters. Work coil for high frequency power supply, comprising a coil mat including: 6. A high-frequency power supply work coil for generating a high-frequency current by induction in a magnetic alloy heater provided at a joint portion of a synthetic resin, wherein the first portion extends in a circumferential direction and the second portion extends in an axial direction. A high-frequency power supply work coil, comprising: a coil mat including a conductor that forms a loop with a portion, wherein the first portion and the second portion are formed in the same cylindrical surface.