Iron core material and manufacturing method of them

Abstract

To provide an iron core material in a low cost, and a manufacturing method of them.SOLUTION: By extending a wire of an industrial pure iron, a cross section of them is formed as an element wire of a diameter of about 1 mm of a rectangular shape, a cross-sectionally hexagon shape, or a cross-sectionally octagonal shape. By passing an annealing furnace by making the element wire to be progressed in a straight, an improvement and an extension of a magnetic characteristic are realized. Sequentially, a resin coated treatment doubling as an adhesion with an insulation is adopted, it is arranged and is wound to a capstan having a large diameter that is 1000 or more times of a liner diameter, and an annular parallel element wire binding is adhered so as to be accumulated in a multi-step is formed. Since it has a cross sectional shape of the element wire, an arrangement wiring becomes stable. Since the capstan has a large diameter, the element wiring becomes a coil ring within an elastic range, and when one portion of the binding is cut, it is opened to a plate shape from an annular shape, and it becomes an iron core material. An iron core is obtained by appropriately cut out from the iron core material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a core material used for the core of an electromagnetic device and a method for manufacturing the same.

Background Art

[0002] Electromagnetic steel sheets, which are soft magnetic, are widely used as core materials for electromagnetic devices. The component is an Fe-Si alloy. This material is highly sophisticated through complex and advanced processes, specifically, in terms of material properties, it has a large magnetic permeability, a large saturation magnetization, a small magnetic hysteresis loss, a small conductivity, and in terms of structure, the induction loss is minimized by laminating insulating thin sheets, etc. Therefore, there is little energy loss during use, and it is an essential material for large equipment (transformers and motors) and equipment with a high operating rate. The problem is that compared with ordinary steel sheets, the cost is extremely high, and due to the limited number of suppliers, the product is expensive. Moreover, in small equipment, the shapes are diverse, so the mold costs and the like are also relatively high, and the laminated core of electromagnetic steel sheets has a significant cost problem.

[0003] In small motors for automobiles, etc., for example, in the case of wipers, etc., the operating rate is too low and there are many DC devices, so the cost is prioritized over the performance as a magnetic material. Recently, for the cores of small devices, those obtained by powder compacting in a mold using spherical powder particles of pure iron having a resin coating that functions for insulation and bonding have become widespread. Compared with electromagnetic steel sheets, the magnetic properties are considerably inferior, but since the electrical resistance is extremely large in all directions, the induction loss is suppressed, which is particularly desirable when the frequency is high. The reason for the inferiority is that, as can be understood from the fact that steel balls are weak in adhering to magnets, the magnetic flux tends to be confined within the sphere. Therefore, the core is suitable for cases where the magnetic properties are not a major problem.

[0004] Patent Document 1 discloses a method of forming coated iron powder into a core. According to it, since the coated iron powder is costly, as a cost reduction measure, an auxiliary lubricant is utilized to replace about half of the coated iron powder with inexpensive ordinary iron powder. It can be understood from the description that a certain cost is also incurred in the forming method from the insulated coated powder particles.

[0005] Commercially available bar steel of pure iron can be used as a core material for small electromagnetic devices with an integral core. It is superior to electromagnetic steel sheets and coated iron powder cores in terms of cost. The magnetic properties such as relative permeability and saturation magnetization are not inferior to those of electromagnetic steel sheets, and there is no problem with magnetic hysteresis loss, but the eddy current loss becomes quite large.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In electromagnetic devices, if the core material gives top priority to energy efficiency, high-performance electromagnetic steel sheets are required, but there are problems in terms of cost. On the other hand, there are electromagnetic devices with extremely low operating rates. In such products, cost is prioritized over performance. In a core formed by pressure bonding and molding powder particles of pure iron with insulation and adhesion coatings, the cost is improved to some extent, but the magnetic performance deteriorates significantly. The core dimensions increase due to insufficient magnetic force. In a massive core formed from pure iron bar steel, cost reduction further progresses. The magnetic performance is excellent, but there are still problems with electromagnetic performance. The problem to be solved by the present invention is to provide a novel core material for use in electromagnetic devices, whose electromagnetic properties are at the same level as those of electromagnetic steel sheets and whose manufacturing cost is at the same level as that of a massive core, and a manufacturing method thereof.

Means for Solving the Problems

[0008] The first aspect of the present invention is a material for an electromagnetic core, characterized in that it is formed from an industrial pure iron wire rod, has a cross-sectional shape of either square, hexagonal, or octagonal, and is formed into a plate shape by arranging, laminating, and adhering straight annealed iron wires with an adhesive insulating film in parallel.

[0009] The second invention is a material for an electromagnetic core, characterized in that it is formed from an industrial pure iron wire rod, has a cross-sectional shape of either square, hexagonal, or octagonal, and is formed into an annular shape by winding straight annealed iron wires with an adhesive insulating film around a frame of a predetermined shape and overlapping parallel alignment, lamination, and adhesion.

[0010] The third invention is a method for forming the electromagnetic core material specified in the first invention. The method involves drawing an industrial pure iron wire rod through a wire drawing machine into an iron wire with a wire diameter of 0.5 mm or more and 2.0 mm or less and a cross-sectional shape of either square, hexagonal, or octagonal. Then, the iron wire is passed straight through an annealing furnace for annealing, straightening, and magnetic modification. After passing through, a resin coating that combines insulation and adhesion is applied, and it is aligned and wound around a capstan with a diameter 1000 times or more the wire diameter and having a groove-shaped guide held on its side. It is laminated to a predetermined thickness to form an annular pure iron ring in which the iron wires are fixed to each other. Then, a part of the pure iron ring is cut and automatically deformed into a plate shape by elasticity.

[0011] Here, industrial pure iron means that the mass concentration of C is 0.02% or less and the purity of Fe is 99.0% or more. The wire diameter is defined as the length between opposite sides that are parallel. In the case of an irregular shape, the longer side is used.

Advantages of the Invention

[0012] The advantages of the present invention are as follows. In terms of performance, since the material is pure iron, the metal structure is in an annealed state, and the magnetic flux direction is the wire axis direction of the iron wire, the magnetic performance is comparable to that of an electromagnetic steel sheet in terms of saturation magnetic flux and relative permeability, and the magnetic hysteresis loss is not a problem. It is superior to iron powder magnetic materials. The insulating film restricts the induced current in both the X and Y directions perpendicular to the magnetic flux, and the eddy current loss is not inferior to that of an electromagnetic steel sheet.

[0013] Regarding the cost aspect, the pure iron wire material is at the same level as ordinary steel wire and is lower in cost than strip for electromagnetic steel sheets and iron powder. Special processes are not required for melting pure iron. When melting ordinary low-carbon steel, vacuum degassing is applied, but it is only necessary to decarburize to 0.02% C or less, and a low-vacuum treatment can suffice. Alloys and deoxidizers are not required. Even during secondary processing, since it is a soft iron wire, pretreatment, lubrication, etc. can also be simple. In some cases, they may not be necessary. Because it is soft, a predetermined diameter can be obtained by a single wire drawing process. The process is simpler than that for electromagnetic steel sheets and also simpler for powders. The processing from the core material to the core is also simple.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

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Figure 7

Embodiments for Carrying Out the Invention

[0015] The novel plate-shaped core material 1 of the present invention will be described according to FIG. 1. The material is industrial pure iron, and the purity of Fe is 99.0% or more. Similar to wood, a desired shape is cut out from the core material 1 and used for the electromagnetic core. The material 1 for the iron core has a structure in which a large number of pure iron wires 2 with a small diameter and straight are aligned and adhered in parallel in the width direction and the thickness direction. The pure iron wire 2 has a resin film 3 having functions of insulation and adhesion. The strength in the coil axis direction is that of pure iron itself, but it has appropriate strength in the width direction and the thickness direction, and cutting along the coil axis is easy and accurate. When cutting out, the magnetic flux direction is made to coincide with the coil axis direction. As a result, the excellent magnetic properties of pure iron can be utilized as they are. Moreover, since it is subdivided by an insulating film in the direction orthogonal to the coil axis, the induced power loss can be sufficiently suppressed.

[0016] FIG. 2 shows the cross-sectional shape of the straight iron wire which is a component of the iron core material. As appropriate shapes, A is square, B is octagonal, and C is hexagonal. The reason is that the wires are aligned with their flat side surfaces in contact with each other without being twisted, and can be accurately laminated, and a smooth surface can be obtained even when separated. In the case of a circular cross-section, it is difficult to achieve accuracy due to the tendency to twist. If the corners of the iron wire are rounded, the manufacturing problems are also alleviated. The wire diameter is preferably 0.5 mm or more and 2.0 mm or less. The smaller it is, the more advantageous it is for the induction loss, but the man-hours increase. The electromagnetic steel sheet is often 1.0 mm or less, but in the present invention, since there is no width like the steel sheet, even if the thickness (wire diameter) increases somewhat, it will not be disadvantageous, so the upper limit is set to the above value.

[0017] FIG. 3 shows a method of assembling the iron wire which is the base wire into a plate shape. The base wire itself only requires drawing a pure iron wire rod and does not require any particular explanation. The base wire 31 having the above-described shape and wire diameter is made to travel straight through a pinch roller 32 and passed through an annealing furnace 33 at about 900 ° C. to be sufficiently softened and to improve the magnetic properties. The magnetic properties of iron in the work-hardened state are deteriorated. A coating device 34 is provided at a partially cooled site, and a resin coating that serves both as insulation and adhesion is applied to the strand 31. The strand 31 is aligned and wound while being pulled by a capstan 35 having a grooved outer periphery 36, and is laminated to form an annular stranded wire 37 that does not come apart due to rapid curing of the adhesive. When it accumulates to a predetermined thickness, it stops and the annular stranded wire 37 is cut in a direction parallel to the annular axis by a cutting machine 38, and it opens from an annular shape to a flat shape by elasticity to complete a plate-shaped core material 39. To use it for a core, a predetermined size piece 40 is appropriately cut out from the plate-shaped core material.

[0018] Here, the first thing to note is that, first, in order to straighten the strand 31 with kinks or twists, a horizontal tension state is always maintained between the pinch roll 32 and the capstan 35. Due to annealing under tension, elongation appears, the wire kinks are eliminated, and straightness is ensured. Second, since the line length is large relative to the wire diameter, catenary bending occurs due to its own weight. Appropriate guides for maintaining horizontal are provided on the furnace floor of the annealing furnace 33.

[0019] Third, if plastic bending occurs in the strand wound around the capstan 35, it will not become a straight flat plate during cutting and straightening. As a countermeasure, the capstan diameter must be 1000 times or more the wire diameter. The basis is as follows. Elastic limit stress (=yield stress) of pure iron wire ≒200 - 250 MPa (1) Bending stress = longitudinal elastic modulus × wire diameter / bending diameter (=capstan diameter) ≤ yield stress (2) From the above formula (2), the capstan diameter is, Capstan diameter ≥ longitudinal elastic modulus × wire diameter / yield stress (3) ≥20,000 (kgf / mm2) / 20 (kgf / mm2) × wire diameter (4) ≥1000 × wire diameter (5)

[0020] Figure 4 shows the manufacturing process of a core material in which straight iron wires with an adhesive insulating film are assembled in a square ring by overlapping alignment, lamination, and joining in parallel. A wire 41 having the above-mentioned wire diameter is made to travel straight through pinch rollers 42 and passed through an annealing furnace 43 at about 900° C., where it is sufficiently softened and its magnetic properties are modified. The wires 41 are then coated with a resin coating that serves both insulation and adhesion in a subsequent painting device 44. The wires 41 are aligned and wound around a core lower frame 45 of a prescribed shape (usually square) with a grooved outer periphery 46 while being pulled, and are then stacked, forming a rectangular bundle of wires 47 that will not come apart due to the rapid hardening of the adhesive, which is then accumulated to a prescribed thickness to become core material 48. The dimensions of the lower frame are the inner dimensions of the planned transformer core. As a transformer core, it has a near-net shape. When the material for the toroidal core is cut, it does not open up into a flat plate because the corners are subjected to plastic bending.

[0021] Figure 5 shows the assembly of a "sun"-shaped transformer core cut out from plate-shaped core material 39. It consists of a main core 52 into which an electromagnetic coil 51 is fitted, and sub-cores 53 and 54 that form a magnetic circuit. The magnetic circuit is aligned with the axial direction of the iron wire that forms the magnetic material.

[0022] Figure 6 shows a transformer core assembled from ring-shaped core materials. Core material 61 assembled using the method in Figure 4 is first divided into two. An electromagnetic coil 64 is fitted into lower core 62, and then upper core 63 is connected to return it to its original shape. A "M" shaped transformer is completed. Two "M" shapes are combined to create a "Sun" shaped transformer. 65 is the dividing line.

[0023] The two core materials of the present invention are easy to use for transformers, but difficult to use for electric motors because their shapes are not linear. However, partial application is possible. Fig. 7 shows a structure in which the annular iron core material assembled in the method of Fig. 4 is applied to the outer periphery 71 of the stator of an electric motor. The magnetic pole 72 is appropriately integrated using a conventional material. This will not be difficult for a person skilled in the art. EXAMPLES

[0024] The economic manufacturing method of pure iron is not particularly difficult. When melting low-carbon steel, vacuum degassing treatment is applied. It does not require the strictness as for special steel. Just by bubbling under low vacuum, the decarburization reaction ( C + O =CO↑) proceeds, and a C content of 0.02% or less can be obtained. Deoxidation and desulfurization are not required. The steel slab obtained by inexpensive billet continuous casting is hot-rolled into a wire rod with a diameter of 5.5 mm. Since it is pure iron, the wire rod can be easily processed into a bare wire with a diameter of 1 mm or less by a single wire drawing. In the finishing pass, it is made into an octagon with rounded corners, close to a square with a piece length of 1.5 mm, by using a shaped die or rolling. For annealing, simply heating to about 900 °C coarsens the crystal grains and modifies the magnetic properties. The resin coating treatment may be done once. It is desirable that the resin material becomes in a semi-cured state during straightening. When the capstan diameter is 2 m, a plate-shaped core material with a length of about 6 m can be obtained.

Industrial Applicability

[0025] The present invention can be easily substituted for low-cost core materials whose demand is growing.

Explanation of Symbols

[0026] 1; Plate-shaped core material 2; Bare wire cross-section 2A; Square cross-section 2B; Octagonal cross-section 2C; Hexagonal cross-section 31; Bare wire 32; Pinch roll 33; Annealing furnace 34; Coating device 35 Capstan 36; Grooved outer periphery 37; Annular stranded wire 38; Cutting machine 39; Plate-shaped core material 40; Predetermined size piece 41; Bare wire 42; Pinch roll 43; Annealing furnace 44; Coating device 45: Core lower frame 46; Outer peripheral groove 47; Angular stranded wire 48; Core material 51; Electromagnetic coil 52; Main core 53, 54; Sub-core 61; Core material 62; Lower core 63; Upper core 64; Electromagnetic coil 65; Dividing line 71; Stator outer peripheral part 72; Magnetic pole

Claims

1. A material for an electromagnetic core, characterized in that it is formed into a plate shape by aligning, laminating, and adhering straight annealed iron wires having an adhesive insulating film, with an industrial pure iron wire rod as the material and a cross-sectional shape of either square, hexagonal, or octagonal, in parallel.

2. A material for an electromagnetic core, characterized in that it is formed into an annular shape by winding straight annealed iron wires having an adhesive insulating film, with an industrial pure iron wire rod as the material and a cross-sectional shape of either square, hexagonal, or octagonal, around a frame of a predetermined shape, and overlapping parallel alignment, lamination, and adhesion.

3. A method for forming the material for an electromagnetic core specified in Claim 1, wherein an industrial pure iron wire rod is drawn by a wire drawing machine into an iron wire having a wire diameter of 0.5 mm or more and 2.0 mm or less and a cross-sectional shape of either square, hexagonal, or octagonal, and then the iron wire is advanced straight through an annealing furnace to achieve annealing, straightening, and magnetic modification. After passing through, a resin coating that combines insulation and adhesion is applied, and it is wound around a capstan with a diameter 1000 times or more the wire diameter while being aligned and held by a groove-shaped guide on the side, laminated to a predetermined thickness, and an annular pure iron ring in which the iron wires are fixed to each other is formed. Then, a part of the pure iron ring is cut and automatically deformed into a plate shape by elasticity. A method for manufacturing a material for an iron core.

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