JPH04346406A - Manufacture of square-shaped magnetic core and jig used therein - Google Patents

Abstract

PURPOSE:To efficiently obtain a square-shaped magnetic core at low cost without deterioration of characteristics by a method wherein a magnetic ribbon is cylindrically wound, a heat treatment is conducted, resin is impregnated, and after it has been hardened, it is formed into an almost square shape by applying pressure from the circumferential surface. CONSTITUTION:First, a magnetic ribbon is cylindrically wound, and a cylindrical magnetic core main body, having a hollow part 11, is obtained. Then, a heat-treatment is conducted in an electric furnace, and one-pack type epoxy resin is impregnated. Then, the inside reinforcement part 13 of a jig 12 is inserted and fitted to the hollow part 11 of the magnetic core main body 1. Subsequently, a pair of pressing plates are arranged on the upper and the lower positions of the magnetic core main body 1, and the magnetic core main body 1 is pressed by applying stress in such a manner that the main body 1 is pinched by the pressing plates from the upper and the lower side. The magnetic core main body 1 is formed into a square shape in the space of square-shaped cross section surrounded by the inner surface of the pressing plates and the inner surface of a side reinforcement part 16. As a result, a square-shaped magnetic core can be obtained efficiently at low cost without deterioration of characteristics.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a rectangular magnetic core,
In particular, it relates to techniques that are effective when applied to the forming process of square magnetic cores.

0002

2. Description of the Related Art In magnetic cores used as cores of transformers, smooth chokes, etc., it is known that the core body is shaped into a square or rectangular shape for convenience in winding or mounting a coil.

[0003] Such a rectangular magnetic core is produced by first winding a magnetic ribbon around a core made of metal such as iron and having a rectangular cross section, and then heat-treating the magnetic ribbon while being wound around the core. There is.

[0004] After the heat treatment, the core is removed and
Instead, a self-lubricating resin with good mold releasability (for example, nylon resin, fluororesin), etc., is inserted into the hollow part of the magnetic core body, and the resin is impregnated and hardened.

[0005] This resin impregnation is performed in order to maintain the magnetic core in a constant rectangular shape. The reason why the nylon resin member is inserted into the hollow part of the magnetic core body at this time is to prevent the resin from deforming when it hardens.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned prior art, since the magnetic ribbon is wound in a rectangular shape, the winding efficiency is lower than that in cylindrical winding, and stress is concentrated at the corners during winding. There was a possibility that characteristic deterioration would occur. In particular, since the ribbon layers at the corners are pressed against each other with strong force, eddy currents flow between the ribbon layers, which tends to increase high-frequency iron loss.

[0007] Furthermore, since the heat treatment is performed with the winding core made of iron or the like attached, there is a problem that the overall heat capacity is large and the heating efficiency is poor.

[0008]Furthermore, in the prior art, the work steps such as removing the winding core and inserting the nylon resin member are complicated, making it difficult to efficiently manufacture the rectangular magnetic core.

In addition, when forming a gap in the magnetic core body, the magnetic path is cut with the nylon resin member inserted into the hollow part, so the nylon resin member cannot be reused and there are many consumable parts, resulting in high costs. It became.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a technique for obtaining a rectangular magnetic core with good formability at low cost and efficiently without deterioration of characteristics. It is in.

[0011]

[Means for Solving the Problems] The present invention includes a step of winding a magnetic ribbon into a cylindrical shape to obtain a magnetic core body, a step of subjecting the magnetic core body to heat treatment, and a step of impregnating and curing the magnetic core body with a resin. The gist of the present invention is a method of manufacturing a rectangular magnetic core, which includes a step of pressing the circumferential surface of the magnetic core body from at least two directions to shape the axial cross section of the magnetic core body into a substantially rectangular shape.

[0012] At this time, the angular forming step can be performed before or after the resin impregnation step.

In addition to the above, the present invention also provides a middle part that is inserted into the hollow part of the cylindrical magnetic core body, and a pair of side parts that are positioned outside the side surfaces of the magnetic core body when the magnetic core body is attached. The gist of the present invention is a jig consisting of a contact portion and a pair of pressing plates that press the magnetic core body from two directions perpendicular to the side contact portion.

[0014]

According to the present invention, a magnetic ribbon is first wound into a cylindrical shape, subjected to heat treatment, and then formed into a rectangular shape. In this way, since there is no need to wind the film in a square shape during winding, the winding efficiency is good and stress concentration at the corners can be prevented.

Furthermore, since the material is wound in a cylindrical shape, there is no risk of deformation even if the core is removed after winding, and heat treatment can be performed with the core removed. Therefore, the heat capacity is small, and thermal efficiency in heat treatment can be maintained favorably.

Furthermore, since the molding is performed by pressing the magnetic core body from the outside using the jig described above, moldability is good and a constant shape can always be maintained.

[0017] In the present invention, the magnetic ribbon includes:
Fe-M-Si-B system, Fe-M-B system or Fe-
An example is an M-Si based amorphous magnetic alloy. Here, M=Nb, Ta, Ca, Mo, W, Zr, Cr, M
Examples include metals consisting of one or a combination of two or more of n, Ni, Cu, C, Al, P, and the like.

Further, in the present invention, the magnetic ribbon described above is heat-treated to contain 1 to 100% (vol%) of microcrystals of 1 μm or less.
A material precipitated within this range may be used as a magnetic ribbon.

[0019]

Embodiment FIG. 5 shows a part of the manufacturing process of the magnetic core body 1 of this embodiment.

In this embodiment, the magnetic ribbon 2 is wound from a reel 3 onto a winding core 7 via a tension detection roller 4. Here, the tension detection roller 4 rotates the reel 3 and lets out the magnetic ribbon 2 when the tension applied to the roller 4 exceeds a certain level.

Further, a cutting blade 5 is arranged from above and below on the supply path of the magnetic ribbon 2, and when the outer diameter reaches a desired value by winding the ribbon 2 around the winding core 7, the magnetic ribbon 2 is cut off. It has a mechanism for cutting the ribbon 2.

The ends of the magnetic ribbon 2 wound around the winding core 7 in the process shown in FIG. A cylindrical magnetic core body 1 having a portion 11 is obtained.

Next, the magnetic core body 1 is subjected to heat treatment in an electric furnace (not shown). The heat treatment temperature at this time is
It is in the range of 380°C to 450°C. The processing atmosphere is preferably an inert atmosphere such as nitrogen.

The jig 12 used in this embodiment will now be explained. The jig 12 is made of a metal material such as iron, and its surface is coated with fluororesin. The center part of the jig 12 has a rectangular center part 1.
3, and the front and back surfaces of this middle support part 13 each have a groove 14 formed linearly in one direction. In the figure, the front end of the middle support part 13 has an arm part 15 extending to both sides, and side support parts 16 are provided at both ends of the arm part 15. .

The side abutting portions 16 are provided with their inner surfaces facing the middle abutment portions 13, and on the upper and lower end surfaces of the side abutting portions 16 are rectangular pressing plates 17 as shown in FIG. Parts of the inner surfaces are brought into contact with each other. The inner surface of this pressing plate 17 is also coated with fluororesin.

The procedure for forming the magnetic core body 1 using the jig 12 will be explained with reference to FIGS. 2 to 4.

First, as shown in FIG. 2, the magnetic core body 1 is mounted on the jig 12 so that the middle part 13 of the jig 12 is inserted into the hollow part 11 of the magnetic core body 1. At this time, the magnetic core body 1 has undergone the aforementioned heat treatment and is impregnated with a one-component epoxy resin for molding.

Next, as shown in FIG. 3, a pair of pressing plates 1
7 are placed above and below the magnetic core body 1, and are pressed by applying stress so as to sandwich the magnetic core body 1 from the top and bottom directions. As a result, the magnetic core body 1 expands in the jig 12 in a direction perpendicular to the pressing direction of the pressing plate 17, that is, in the direction of the inner surface of the both side abutting portions 16, and finally the inner surface of the pressing plate 17 and the side abutting portion The magnetic core main body 1 is formed into a rectangular shape within a space having a rectangular cross section surrounded by the inner surfaces of the magnetic core body 16. Then, as the resin impregnated into the magnetic core body 1 is cured, the rectangular shape is maintained. At this time, in the jig 12, the contact surface between the pressing plate 17 and the magnetic core body 1 is coated with fluororesin, so that the magnetic core body 1 and the jig 12 are prevented from being bonded together by the resin.

After the resin impregnated into the magnetic core body 1 is hardened in the jig 12, the pressing plate 17 is removed and a new pressing plate 18 is installed.
, 19, the rotary cutting blade 2 is inserted from above the top surface.
0 is lowered in a rotating state, passes through a small gap between the pressing plates 18 and 19, and a part of the magnetic core body 1 is cut off. After the rotary cutting blade 20 penetrates the magnetic core body 1 and its tip enters the groove 14 of the middle support part 12, the rotary cutting blade 20 moves in the front-rear direction in the figure, thereby causing the magnetic core body 1 to become The road is completely severed. This cut portion becomes a gap in the magnetic core body 1. At this time, according to this embodiment, since the magnetic core body 1 during cutting is completely fixed by the middle support part 12, the side support part 16, and the pressing plates 18, 19, the rotational force of the rotary cutting blade 20 Does not cause misalignment, etc.
It is possible to cut the magnetic core body 1 at an accurate position.

Next, if necessary, the jig is rotated 180 degrees around the axis of the intermediate support part 12, so that the surface opposite to the cutting surface is placed directly below the rotary cutting blade 20, and the The magnetic path is cut in the same process.

As described above, the magnetic path of the magnetic core body 1 is cut at two places, so that the magnetic core body 1 is divided into two parts. The magnetic core body 1 thus divided into two parts is used as a magnetic core for a smoothing choke, a magnetic core for a transformer, etc. by combining the cut surfaces again.

As explained above, in this embodiment, there is no need to perform rectangular winding when winding the magnetic ribbon 2.
The winding efficiency is good, and there is no stress concentration at the corners during winding, so deterioration of characteristics can be prevented.

Furthermore, during heat treatment, heating can be performed with the wound core already removed from the magnetic core body 1, so that the heat capacity is small and efficient heating is possible. Further, in the prior art, it was necessary to insert a nylon resin member or the like into the hollow portion 11 in order to maintain the rectangular state of the magnetic core body during heating, but this is not necessary in this embodiment.

In the above embodiments, the magnetic core body 1 is impregnated with resin and then the jig 12 is attached to form it into a rectangular shape. The same effect as in the above embodiment can be obtained by forming the magnetic core body 1 into a rectangular shape using the magnetic core body 1, and then impregnating the magnetic core body 1 with resin and curing it.

[0035]

According to the present invention, a rectangular magnetic core with good formability can be obtained at low cost and efficiently without deterioration of characteristics.

[Brief explanation of drawings]

[Fig. 1] A perspective view showing a jig of an example.

[Fig. 2] A perspective view showing the state in which the magnetic core body is attached to the jig in the example.

[Fig. 3] A perspective view showing a state in which a magnetic core body is formed into a square shape using a jig in an example.

FIG. 4 is a perspective view showing a state in which a part of the magnetic path is cut to form a gap in the magnetic core body in the embodiment.

[Fig. 5] Explanatory diagram showing a part of the manufacturing process of the magnetic core body of the example

[Fig. 6] A perspective view showing a magnetic core body before molding in an example.

[Explanation of symbols]

1. Magnetic core body 2. Amorphous ribbon 3. Reel 4...Tension detection roller 5. Cutting blade 6. Kapton tape 7. Winding core 11...Hollow part 12...Jig 13. Middle part 14...Groove 15...Arm 16... Side support part 17...pressing plate 18, 19...pressing plate 20... Rotating cutting blade

Claims (5)

[Claims] 1. A step of winding a magnetic ribbon into a cylindrical shape to obtain a magnetic core body, and a step of subjecting the magnetic core body to heat treatment,
A method for manufacturing a rectangular magnetic core, comprising the steps of impregnating and curing the magnetic core body with a resin, and pressing the circumferential surface of the magnetic core body from at least two directions to shape the axial cross section of the magnetic core body into a substantially rectangular shape. 2. The method of manufacturing a square itself according to claim 1, wherein the square forming step is performed before or after the resin impregnation step. 3. A middle part inserted into the hollow part of the cylindrical magnetic core body, a pair of side parts located outside the side surfaces of the magnetic core body with the magnetic core body attached, and the side parts. A jig comprising a pair of pressing plates that press the magnetic core body from two directions perpendicular to the magnetic core body. 4. A step of winding a magnetic ribbon into a cylindrical shape to obtain a magnetic core body, and a step of subjecting the magnetic core body to heat treatment,
a step of impregnating the magnetic core body with a resin and curing it, mounting the magnetic core body on the middle abutting part of the jig, pressing the magnetic core body with the pair of pressing plates, and pressing this magnetic core body with the side abutting part; 4. A method of manufacturing a rectangular magnetic core using a jig according to claim 3, comprising the steps of forming into a rectangular shape formed by an inner surface with a plate, and cutting off at least a portion of the magnetic core body. 5. The method of manufacturing a square magnetic core according to claim 4, wherein the square forming step is performed before or after the resin impregnation step.