JPS625034Y2 - - Google Patents

Description

[Detailed description of the invention] The invention is based on the structure of an induction heating coil, specifically, connecting an input terminal connected to an output terminal on the heating power source side and a heating conductor portion facing the heated surface of the heated material with a predetermined gap. The present invention relates to the structure of a lead portion of an induction heating coil which is required to have an extremely long lead portion.

For example, when quenching, tempering, or annealing the inner surface of a long tube several meters long by induction heating, the wound heating conductor is moved from one end of the inner surface of the long tube to the other. In this case, the length of the lead connecting the heating conductor and the input terminal of the heating coil connected to the output terminal on the heating power source side must be at least the length of the tube material. This will be explained using the heating coil shown in FIG. 1a.

In FIG. 1a, reference numeral 1 denotes an input terminal of a heating coil 10' which is fastened to an output terminal on the power supply side with a bolt (not shown) through a bolt hole 11, for example, with an insulating material 5 in between. It consists of a side input terminal 1b. One end of the wound heating conductor portion 2 is a horizontal lead portion 31a projecting at right angles from the input terminal 1a on the one side, and a length L hanging from the tip of the horizontal lead portion 31a is a long vertical direction. The other end of the heating conductor 2 is electrically connected via the lead portion 32'a, and the other end of the heating conductor 2 protrudes at right angles from the input terminal 1b on the other side with the insulating material 5 interposed between the lead portions 31a and 32'a on the one side. A horizontal lead portion 31b and a vertical lead portion 32' having a long length L hanging from the tip of the horizontal lead portion 31b.
They are electrically connected via b. Both lead portions 31 and 32' are configured to suppress self-heating by cooling fluid flowing through the pipes 4a and 4b, such as copper pipes fixed to their respective side surfaces. It should be noted that the heating conductor portion 2 is of course provided with a cooling fluid supply/discharge structure for absorbing self-generated heat, but it is not shown because it is not relevant to the present invention. FIG. 1b shows a case in which the heating coil 10' having the above-mentioned structure is used to heat the inner surface of a long tube, for example, the axial direction of which is perpendicular, for hardening. First, as shown in the figure, the heating coil 10' is arranged so that the heating conductor portion 2 is located on the lower end surface of the long tube W, which is vertical. In this state, the vertical lead portion 32' is inserted almost all the way along the axis of the long tube W. After turning on a power source (not shown), by moving the long tube W downward or moving the heating coil 10' upward at a predetermined feed speed, the heating conductor portion 2 is sequentially displaced upward according to the arrow. The inner surface of the long tube W is moved and heated, and the heated inner surface is sequentially rapidly cooled and quenched by cooling fluid injected from a cooling fluid injection ring (not shown) that moves below the heating conductor section 2. In this way, when the heating conductor portion 2 is displaced upwardly and comes out of the upper end surface of the long tube W, the internal hardening over the entire length of the long tube W is completed.

By the way, when examining the inner hardened layer of the long tube W that has been hardened, the hardening depth is thicker in the direction of the heating start end face (lower end face) and gradually becomes thinner towards the end face direction of heating end face (upper end face). It turns out that it is thinnest at the end face.

The above example uses internal hardening of a long pipe W, but
This problem occurs when only heating is applied for tempering, as the depth of the tempering layer becomes thicker or thinner.

Therefore, the above phenomenon is caused by the fact that when the vertical lead portion 32' of the heating coil is fully inserted into the long tube W, the heating effect is large, and the less the heating coil is inserted, the smaller the heating effect is. I can say that.

The present inventor analyzed the above problem as follows.

That is, each of the vertical lead parts 32'a and 32'b separated by the insulating material 5 generates magnetic flux φ in opposite directions at a certain moment, as shown in FIG. 1c, but the magnetic flux φ is Inside the tube, the magnetic flux is trapped and flows to the tube body, creating a load state, which increases the circuit impedance, increasing the magnetic flux generated from the heating conductor section 2, and outside the tube, it diffuses infinitely into the air, creating a no-load state. As a result of lowering the circuit impedance, the magnetic flux generated from the heating conductor portion 2 is reduced.
Therefore, when the vertical lead section 32' is inserted into the pipe at its maximum, the heating effect of the heating conductor part 2 is maximized, and when it is not inserted into the pipe, the heating effect by the heating conductor part 2 is minimized.

From the above analysis results, the long vertical lead part 3
It is said that leakage magnetic flux of 2' is the cause, and it is concluded that a countermeasure to this problem is to use a coaxial lead that does not generate leakage magnetic flux. However, problems also arise when using coaxial leads. This will be explained below.

As is well known, the lead portion of the induction heating coil must be cooled to absorb heat generated by itself. For example, as shown in FIG.
One side 32''a of the vertical lead portion 32'' is, for example, a round bar-shaped conductor, and the other side 32''b is a tubular conductor having a predetermined inner diameter, which is arranged coaxially with the round bar-shaped conductor, and both end surfaces of the tubular conductor are arranged coaxially. It is closed with an insulating material 51, and cooling fluid is supplied near the upper and lower ends of the tube side.
The structure in which the exhaust ports 6, 6 are provided is the simplest. Therefore, since the self-cooling cooling fluid flows through the annular cavity 8', the vertical leads 32'', 32''a and 32''b, are simultaneously cooled.

In this case, tap water is generally used as the cooling fluid for self-cooling. Unlike pure water, tap water contains a considerable amount of impurities and therefore has low insulation resistance. Therefore, as described above, when currents of opposite polarity flow through the conductor 32''a on one side and the conductor 32''b on the other side of the vertical lead portion 32'', a short circuit current occurs.If the flow path is short and small, a short circuit occurs. Although the current is not noticeable, in the case of the 10" heating coil where the length of the flow path is several meters, the low insulation resistance causes the short circuit current to be extremely large, resulting in a very large power loss. This causes a problem in that the electric power to be supplied to the heating conductor portion 2 is greatly reduced, making it impossible to obtain the desired heating effect. Of course, if pure water or air, nitrogen, or other gas is used as the cooling fluid, there is no risk of the above problem occurring, but pure water is expensive and uneconomical, and gases not only have little cooling effect but also It's expensive.

The present invention has been made with the purpose of solving the problem when the lead portion connecting the power supply side output terminal and the heating conductor is required to be extremely long when heating a heated material by the above-mentioned induction heating. If the surface to be heated is the inner surface of the long pipe, uniform heating can be achieved over the entire length of the long pipe, and power loss can be prevented not only in the above-mentioned long pipe but also in all long leads including this at a low cost. The present invention provides an induction heating coil that can be heated while using water.

The present invention will be explained according to an embodiment shown in FIG.

Induction heating coil 1 according to the present invention shown in FIG.
0, those with the same reference numerals as in FIG. 1 are the same members. That is, 31a and 31b are conductors on one side and the other side of the horizontal lead portion 31, respectively, 2 is a heating conductor portion, and 5 is an insulating material. In the present invention, the vertical lead portion 32 is different from that in FIG. 1a as well as in FIG. 2. That is, the conductor 32a on one side of the vertical lead portion 32 is a tubular member having a hollow portion indicated by 8a, and is connected to the connecting portion 311.
It is connected to the one side conductor 31a of the horizontal lead part 31 through a, and to one end of the heating conductor part 2 through the connecting part 21a. Vertical lead section 32
The other side conductor 32b is a double tube material consisting of an inner tube 321b having an inner diameter slightly larger than the outer diameter of the one side conductor 32a and an outer tube 322b having an inner diameter slightly larger than the outer diameter of the inner tube 321b. Both end surfaces of the annular gap 8b formed by the inner tube 321b and the outer tube 322b are closed surfaces as shown as 323b. The other side conductor 32b made of the double pipe material is connected to the one side conductor 31b of the horizontal lead portion 31 via, for example, a brim-shaped connection portion 311b.
It is also connected to the other end of the heating conductor section 2 via the connection section 21b. The other side conductor 32b is an insulating material 7 provided so as to surround the outer periphery of the one side conductor 32a.
is arranged coaxially with the one-side conductor 32a using a predetermined gap maintaining member. Cooling fluid supply/discharge ports 9a and 9a are provided on the upper and lower end faces of the one side conductor 32a in the axial direction, so that the cooling fluid can flow through the hollow portion 8a, and the axially upper end face of the other side conductor 32b is provided with cooling fluid supply/discharge ports 9a and 9a. - Cooling fluid supply/discharge ports 9b and 9b are provided on the outer wall near the lower end so that the cooling fluid can flow into the annular gap 8b.

By employing the above configuration, the one side conductor 32a and the other side conductor 32b in the vertical lead portion 32 are arranged coaxially, so generation of leakage magnetic flux is prevented, and the one side conductor 32a is hollow. The conductor 32b on the other side is self-cooled by the cooling fluid flowing through the annular gap 8b, and each tube wall serving as the cooling fluid flow path is made of a single piece. Since a polar current flows, there is no risk of short-circuit current flowing, so even if clean water containing impurities is used as a cooling fluid, there is no need to worry about low insulation resistance, and the power supplied to the heating conductor section 2 is reduced. There will be no water loss at all.

In the above embodiment, the one side conductor 32a and the other side conductor 32b of the vertical lead portion 32 are coaxially arranged using the insulating material 7 that surrounds the entire outer circumference of the one side conductor, but the present invention is not limited to this. For example, a predetermined gap may be maintained by partially using a ring member made of an insulating material or by using a bridge member.

Further, in the above embodiment, for convenience of explanation, the horizontal lead portion 31 and the vertical lead portion 32 are expressed, but the lead portion 3 has a straight structure without bending as in the embodiment, and has a full length. Alternatively, a predetermined range of the lead portion 3 may be replaced with 32a, 3 in the above embodiment.
It goes without saying that it may be constructed in the same manner as 2b, and that it will have exactly the same effects as the embodiment.

[Brief explanation of the drawing]

Figures 1a and b are a perspective view and a front view showing the heating operation of a conventional induction heating coil in which the lead portion is made longer if necessary, respectively, and Figure 1c is a problem with the conventional induction heating coil. Fig. 2 is a cross-sectional front view of a coaxial lead type induction heating coil with the lead portion lengthened as necessary, and Fig. 3 is a cross-sectional front view of the induction heating coil of the present invention. be. 1...Input terminal, 1a...One side of the input terminal,
1b...Other side of the input terminal, 2...Heating conductor, 3
...Lead portion, 31a, 32a...One side conductor of the lead portion, 31b, 32b...Other side conductor of the lead portion, 321b, 322b...Inner tube and outer tube of the other side conductor of the lead portion, 7... Insulating material, 8
a... Hollow part, 8b... Annular gap, 10... Induction heating coil, W... Heated material.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. The lead portion connecting the input terminal connected to the output terminal on the heating power source side and the heating conductor portion facing the heated surface of the heated material with a predetermined gap therebetween is extremely long. In the required induction heating coil, the entire length or a predetermined range of one side conductor connecting one side of the input terminal constituting the lead part and one end of the heating conductor part is made of a tubular material,
A self-cooling fluid is allowed to flow through the hollow part of the tubular material, and the other side conductor connecting the other side of the input terminal and the other end of the heating conductor section is extended over a range that is approximately the same as the entire length or a predetermined range of the one side conductor. A double pipe material is arranged coaxially with a predetermined gap, and both ends of the annular gap formed by the inner pipe and outer pipe of the double pipe material are closed, and a self-cooling fluid is introduced into the annular space. An induction heating coil characterized by being able to be distributed. 2. The induction heating coil according to claim 1, wherein the tubular material and the double tubular material are coaxially arranged with a predetermined gap separated by an insulating material. 3. The induction heating coil according to claim 1, wherein the material to be heated is a long tube, and the surface to be heated is the inner surface of the tube.