JPS6362993B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electromagnetic core, and in particular, the present invention relates to an electromagnetic core with a silicon content.
The present invention relates to a method for manufacturing an electromagnetic core having a laminated structure (hereinafter referred to as a "laminated core") made of 4.5 to 7.5% silicon iron.

Laminated cores are generally used in transformers and motors, and are also used in relatively special products such as dot printers. Conventionally, laminated iron cores have been manufactured by a method in which 3% silicon iron is made into thin plates and laminated in large numbers with insulating layers interposed therebetween. However, if high-silicon iron with a silicon content of 4.5% or more is used, especially 6.5% silicon iron, the electrical resistance is about twice as high as that of 3% silicon iron, which reduces eddy current. As a result, heat generation is reduced, which reduces power consumption, magnetostriction is extremely low, so transformer beats are reduced, magnetic permeability is maximized, and holding force is minimized, among other excellent effects. It will be done. However, silicon iron containing 4.5% or more silicon has extremely brittle mechanical properties and is extremely difficult to process, such as cutting, rolling, and forging.
For this reason, attempts have been made to reduce the thickness of 6.5% silicon iron, but this has not been achieved.

Therefore, the object of the present invention is to
It is an object of the present invention to provide a manufacturing method that can easily and inexpensively manufacture an electromagnetic core having a laminated structure made of % silicon iron.

Generally speaking, the present invention has a silicon content of 4.5 to 4.5.
Forming 7.5% silicon iron slurry into a sheet shape,
An insulating layer is formed on the surface of the sheet using insulating slurry, the sheets are laminated in multiple layers, the laminated body is cut in the cross-sectional direction to form an iron core of a predetermined shape, and then the formed iron core is sintered. This method produces a laminated core made of 4.5 to 7.5% silicon iron.
Here, the reason why the silicon content is limited to 4.5 to 7.5% is as follows. That is, as the silicon content increases, the electrical resistance increases and the AC characteristics improve. However, as the silicon content increases, the material becomes brittle. Silicon content up to 4.5% can be processed by hot working, but above this it is difficult to make thin sheets. On the other hand, as the silicon content increases further, the magnetostriction decreases, becoming almost zero at 6.5% Si, and then increasing again. If magnetostriction becomes too large, beats will occur when applied to an iron core. Furthermore, as the silicon content increases, the saturation magnetic flux density decreases, so it is necessary to increase the size of the iron core. Considering such magnetostriction and saturation magnetic flux density, the upper limit of silicon content is set at 7.5%. (References: RMBOZORTH,
“FERROMAGNETISM”, D.VAN
NOSTRAND COMPANY, INC., USA,
1963, P.76, 77, 80, 81, and RCHALL,
“JOURNAL OF APPLIED PHYSICS”
(Vol. 30, No. 6, 1959, P. 816-819) Note that the core can be formed into different shapes depending on how the sheets are laminated.

Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings.

The method for manufacturing a laminated electromagnetic core according to the present invention generally includes the following three steps: (1) Forming a silicon iron sheet having an insulating layer on the surface (2) Laminating the sheets and forming the core (3) Forming Consists of sintered iron core.

In the first step (1), first, a silicon iron slurry having a silicon content of 4.5 to 7.5% is prepared.
As an example, the final composition of -400 mesh carbonyl iron powder and -350 mesh Fe-17%Si alloy powder is
After weighing to give 6.5% silicon iron, 3 g of binder (e.g. polyvinyl butyral), 4 g of plasticizer (e.g. dibutyl phthalate), 7 g of methanol, 2 g of butanol, and 10 g of methyl ethyl ketone were added to 100 g of these powders in a ball mill. After mixing for 72 hours, 6.5% silicon iron slurry can be prepared. Then, as shown in FIG. 1A, a slurry 10 (particularly indicated by dots) is poured onto a tape-shaped molded carrier 11 using a doctor blade 12, and a sheet of approximately 0.4 mm thick ( green sheet) 13. Next, an insulating layer is formed on the silicon iron sheet 13 using an insulating slurry. Insulating slurry is prepared, for example, by the following method. First, each powder of magnesia, silica, alumina, and barium oxide was added at 50% by weight:
Mix at a ratio of 40:5:5 and add this mixed powder to 1200
℃ for 1 hour and then ground by ball milling for 24 hours. Add a binder (polyvinyl butyral) to 100g of the powder thus obtained.
9g of plasticizer (dibutyl phthalate), 11g of dispersant (NOF OP-85R), 80g of methyl ethyl ketone, 50g of methyl alcohol, and 15g of butyl alcohol were added and ball-milled for about 72 hours to form insulation slurry. can get. Then, as shown in FIG. 1B, this insulating slurry 14 is poured onto the previously formed silicon iron sheet 13 using the same doctor blade method to form an insulating layer 15 with a thickness of approximately 1 mm. . In this way, a sheet 16 having an insulating layer 15 formed on a 6.5% silicon-iron sheet 13 is obtained as shown in FIG. 1C.

Next, in the second step, the sheets 16 obtained in the previous step are laminated in multiple layers, and the laminated body is cut and formed into a predetermined shape. In this case, sheet 1
Figures 2 and 3 depend on the method of stacking and cutting 6.
It is possible to form the core in different shapes as shown in the figure. First, in the example shown in FIG. 2, about 10 sheets 16 are cut to an appropriate size and stacked together to form a laminate 17 as shown in FIG. A ring-shaped core 18 shown in FIG. 2B is formed. With this method, the core can be formed into various shapes by changing the punching die. Next, in the example in Figure 3, sheet 1
6 is made into a continuous length, and this is spirally wound to form a coiled laminate 19 as shown in FIG. Triangular prism core 2 as shown
1. Specifically, this triangular prism-shaped core is used in a dot wire drive section of a dot printer. In the case of a triangular prism-shaped core, due to its magnetic properties, it is required to be laminated in the radial direction perpendicular to the magnetic flux direction (longitudinal direction) shown by arrow M, and therefore the dimensions of the sheets constituting each layer are different. Become. If these sheets were to be formed one by one and then laminated, it would require as many punching dies as the number of sheets to be laminated, which would require a great deal of effort and cost, but the method shown in Figure 3 makes it very easy to form them. can.

Finally, in the third step, the formed iron core is heated in the air at 200°C for about 2 hours to scatter the binder.
Thereafter, it is sintered in dry hydrogen at 1350°C for 1 hour. This completes the iron core.

Winding is applied to the laminated core manufactured by the above method,
When tested using it in transformers, pulse motors, dot printers, etc., the output torque was almost the same and the heat generation was reduced by more than 20% compared to when using a conventional laminated core made of 3% silicon iron. was gotten.

As described above, according to the present invention, it is possible to manufacture a laminated electromagnetic core made of 4.5 to 7.5% silicon iron with excellent magnetic properties, and it has many advantages such as a relatively simple process and low cost. has.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically illustrating the process of forming a silicon iron sheet having an insulating layer on its surface in the method of the present invention;
FIGS. 2 and 3 are diagrams showing different embodiments of a laminate of silicon-iron sheets with an insulating layer and an iron core formed from the laminate. 10...Silicon iron slurry, 11...Molded carrier, 12...Doctor blade, 13...Silicon iron sheet, 14...Insulating material slurry, 15...
Insulating layer, 16... sheet, 17, 19... laminate, 18, 21... iron core.

Claims (1)

[Scope of Claims] 1. A method for manufacturing an electromagnetic core with a laminated structure made of silicon iron having a silicon content of 4.5 to 7.5%, which comprises carbonyl iron powder and Fe-17%Si alloy powder having a final composition of Weigh silicon iron with a silicon content of 4.5 to 7.5%, and add and mix binders, plasticizers, and organic solvents to these powders to reduce the silicon content.
A process of preparing 4.5-7.5% silicon iron slurry, and adding and mixing a binder, plasticizer, and organic solvent to heat-treated insulation powder of a mixture containing magnesia, silica, alumina, and participating barium to form insulation slurry. a step of pouring the silicon-iron slurry onto the molded carrier using a doctor blade and forming it into a sheet; and a step of pouring the insulating slurry onto the silicon-iron sheet using a doctor blade. sink, form an insulating layer,
A process of forming a silicon iron sheet with an insulating layer formed thereon, a process of laminating the sheets in multiple layers, cutting and forming an iron core from the laminated body into a predetermined shape, and then sintering the formed iron core. A method of manufacturing a sintered laminated electromagnetic core, characterized by a step of performing the same.