JPS6239007A - Annealing of heat insulation treated magnetic core - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved method for annealing an amorphous alloy core, and more particularly, a method for rapidly annealing an amorphous alloy core and magnetically annealing the amorphous alloy core, thereby improving its magnetic properties. on how to tailor the product for a specific product.

Amorphous alloys have been developed that exhibit better magnetic properties than general crystalline alloys. These amorphous alloys can be rolled to form a magnetic core (approximating a toroidal magnetic circuit) and are suitable for use as cores in magnetic devices, such as transformers, inductors, electrodeless fluorescent lamps, etc. . Adaptation of amorphous alloy cores for use in electrodeless fluorescent lamps is shown in US Pat. No. 4,227,120 (Lupolsky et al.). The amorphous metal core is annealed to enhance its magnetic properties. The annealing process generally involves heat treating the core to a temperature sufficient to relieve stress without initiating crystallization and cooling in the presence of a magnetic field. This type of annealing process is described in U.S. Pat. , i, 116,728°4.24
9,969.4,262,233. and 4.298.
No. 409 each specification.

The main problem with common annealing methods is the long period of time required to perform the heating step. This problem is particularly troublesome for relatively large cores.

Rapid heating of the core to annealing temperatures creates hot spots on its exterior, which significantly reduces the magnetic properties of the core, making it unsuitable for use in the above-mentioned products. To alleviate this problem, the temperature of the core must be raised to the annealing temperature by a laborious process involving multiple staged heating steps, which is time consuming and expensive.

The present invention substantially reduces the time required for annealing and significantly improves its magnetic properties. An improved method for magnetic core annealing is provided. Generally, a magnetic core is an amorphous metal ribbon wound to form an outer surface, an inner surface, a top surface, and a bottom surface.

The core is heated to a first temperature, held at this temperature for a preselected period of time, and then cooled to a second temperature. The improvement consists of insulating the inner and outer surfaces of the core before the heating step.

It has been discovered that substantially larger cores can be annealed in an economically reliable manner by thermally treating the inner and outer surfaces of the core prior to the heating step. Heat is transferred from the top and bottom surfaces into the interior of the core along the metal passages, while heat transfer to the inner and outer surfaces of the core is substantially reduced. Since the heating step is a rate determining step, overall processing time and production costs are minimized. The common staged heating steps are eliminated, resulting in a reduced number of process steps and increased reliability of the annealing process. The core is highly uniformly heated, with no substantial temperature fluctuations. If this were present, mechanical deformations, thermal stresses, and hot spots would occur. An advantage is that the magnetic cores produced by the method of the invention exhibit high magnetic properties (i.e., at an induction of 1.40 Tesla and a frequency of 60 Hz, AC iron losses are approximately 0.0.
16~0.25W/Kf, excitation force is about 0.25~0.4
5 VA/Kg, and the coercive force is approximately 1.1-1.5A/
m). Magnetic cores annealed according to the invention are therefore particularly suitable for use in inductors, transformers and electrodeless fluorescent lamps.

The present invention will be better understood, and other advantages will become apparent, upon reference to the following detailed description and accompanying drawings.

FIG. 1 is a plot showing the time-temperature profile of a magnetic core annealed by a conventional annealing method.

FIG. 2 is a plot showing the time-temperature profile of a magnetic core annealed by the annealing method of the present invention.

The amorphous alloys of this invention are produced by quenching molten metal at a rate of about 0.6° C./sec to directly form a glassy material in the form of a thin ribbon or wire. Generally, the thickness of the ribbon is about 20-30 μm, and the width of the ribbon is about 25 μm.
~100 order. The magnetic core is wrapped with an amorphous ribbon,
It has an outer surface, an inner surface, a top surface, and a bottom surface. The inner surface defines a central aperture extending substantially coaxially with the centroia of the core. Additionally, the top and bottom surfaces lie in respective planes substantially perpendicular to respective cylindrical surfaces formed from the inner and outer surfaces thereof, respectively.

The present invention provides an improved method for magnetic core annealing that substantially reduces the period required for annealing and significantly improves the magnetic properties of the core, the improvement being in the heated portion of the annealing process. It consists of insulating the inner and outer surfaces of the core before starting. The heat insulation treatment also has a thermal conductivity of about 0.
03-0.14 W/m'c and linear shrinkage approximately 1-3% (
This consists of selecting an insulator that has a temperature of up to 500℃). It is also within the scope of the present invention to use assembled insulators or those manually manufactured from component parts that meet the above criteria. Once the insulation is selected, it is applied to the interior and exterior surfaces by a method selected from the group consisting of wrapping, painting, casting and dipping.

Wrapping of insulation can be easily accomplished at low cost using common equipment and procedures. Therefore, the preferred method for applying insulation to the core is wrapping. Typically, the insulation has a thickness dimension extending radially outward from the outer surface of the core and radially inward from the inner surface of the core, approximately 25 mm in thickness.
~75m+.

According to the present invention, the magnetism of the core can be increased by annealing. The annealing process generally consists of rapidly heating the core to a first temperature and holding it at this temperature for a preselected period of time. This is sufficient to remove all stress from the material, but less than that required to initiate crystallization.

Preferably, the opening containing the core is first rapidly heated to a peak opening temperature of 100-160° C. above the first temperature of the particular amorphous alloy chosen. As the core approaches its annealing temperature, the open temperature is lowered to match the core temperature (see Figure 2). This method substantially reduces the time required to heat treat the core. The core is then cooled to a second temperature of about 200-25° C. at a cooling rate of about 0.1-b minutes. The first temperature is generally about 325-40
The second temperature is typically at ambient temperature, although it may be 0° C., below the Curie temperature of the particular amorphous alloy chosen. Preferably, at least the heating step, very preferably each of the heating step and the cooling step, is carried out in the presence of a magnetic field. The direction may be either parallel or perpendicular to the longitudinal axis of the core depending on the particular product application. certain alloys,
For example essentially C066Fe4N1BS1 and Fe
76.85Or2B16. Those having a composition consisting of a magnet selected from the group consisting of IS'4.8C0,25 can be annealed in the presence of a magnetic field to substantially improve the magnetic properties as described above.

The method of manufacturing the magnetic core is such that a certain percentage of the total area is air, which is trapped between each layer of the spirally wound ribbon. Therefore, it is also well established that metals are good conductors of heat, while gases are poor conductors of heat. Thermal conductivity values (k) for metal and air are 50.2 Jsm (c) and 0.024 J, respectively.
8m(c)-1 and 0.024J8m(c). Air trapped between the layers of the uninsulated core ribbon thus acts to impede heat flow (H) toward the center along the thickness of the ribbon.

where is the thermal conductivity of the material, A is the cross-sectional area of the material, T2-TI is the temperature difference between two points, and d is the distance between the two points. Due to this poor heat conduction,
Hot spots occur in the outer part of the core, which significantly impairs its magnetic properties, making it unsuitable for use in transformers, inductors, electrodeless fluorescent lamps, etc. Furthermore, thermal conductivity tests conducted at 400°C on uninsulated sample cores show that the thermal conductivity across the width of the ribbon is higher than that of the ribbon during both the heating, process, and cooling processes. It was also found that the thermal conductivity across the area (i-hayashi) was more than 20 times greater. The inner and outer surfaces are insulated before the heating process, leaving the top and bottom surfaces (li, exposed) and (end) substantially larger and more reliable in one direction. It was also found that annealing 1-2 can be achieved by
Ta.

This is because heat is transferred from the top and bottom surfaces into the interior of the core along all internal paths, while the rate of heat transfer to the inner and outer surfaces of the core is substantially reduced. heating]
, the sum is reduced by the speed lp process) -,',1,2: The physical processing time and production cost are reduced. [Generally performed step-by-step addition]: It's time to remove it, that's it! The number of P treatment steps is reduced, and the reliability of annealing treatment is high.

The core is heated highly uniformly without substantial temperature fluctuations (temperature fluctuations would result in mechanical deformations, thermal stresses, and hot spots). Advantageously, the method of the present invention has the advantage that the magnetic core 61 produced by the present invention does not exhibit high magnetic properties (with an induction of 1,40 Tesla and a frequency of 60 [b), the AC iron loss is approximately to 0.16-0,25W,/
'nizo, excitation force 1tt approx. 0.25-0.45VA7%,
coercive cover is approximately 1.1-1.6 A, -% m). Magnetic cores annealed in accordance with the present invention are therefore particularly suitable for use in conductors, transformers, and electrodeless fluorescent lamps.

The following sections are presented for a better understanding of the invention. The specific techniques, conditions, materials and data presented and described for the purpose of illustrating the principles and practice of the invention are illustrative only and should not be construed as limiting the scope of the invention.

Example Metglas with nominal composition Fe 73B 1331-g.

(Registered Trademark) 2605 S-205-2O A ring-shaped magnetic circuit type test sample was prepared by winding the alloy ribbon in a spiral. The average inner diameter and average outer diameter of the masterpiece test specimens were 172 mm and 377 mm, respectively, and the average type 5
'55 hg. High temperature magnetic wire is wrapped 6 times parallel to the longitudinal axis of the core, for annealing purposes) 300Δ
A magnetic field of /m was applied. Some samples were annealed without adiabatic treatment by the Deer method, and annealed with adiabatic treatment by the method of the present invention. g. During the heating and cooling steps, the specimens were heated to their respective annealing temperatures with a magnetic field of 5ooA/m applied.

The samples were cooled to 200°C at an average rate of 1.5°C/min.

The time-temperature profiles for samples annealed by the conventional annealing method and by the method of the present invention are plotted in Figures 1 and 2, respectively. Be sure to place a thermocouple in the center of each core 2.0 to monitor temperature changes during the annealing process. , and placed 1 at 5 defenses from the outside. As shown in FIG. 1, the temperature at the center of each conventionally annealed core is substantially different from the temperature at its outer surface 1. When the core is annealed by the method of the present invention (/'C), the temperature difference between the center 2 and the outer surface 1 becomes smaller as shown in FIG. 2.As a result, the core exhibiting the time-temperature profile shown in FIG. Magnetism significantly improved by L2 can be obtained during annealing 1 to 1 within a significantly shortened period.

The magnetism of these samples, that is, the coercive force (7'nia/m
), A, C, iron loss (Watt/Kq), and excitation force (
To Bordeaux? A/~) to 1.40 tesla induction''6
It was measured by the circumferential f' number of j2 and 60 It:. The magnetic values of specimen 'i6 J: which was subjected to general annealing treatment and specimen which was annealed by the method of the present invention are shown in Tables 1 and 2, respectively.
Shown below.

Table 1 1 Metoglas Inner diameter 172 57260
5 S=2 Outer diameter 383 2 Metoglas Inner diameter 172 56260
5 s -2 outer diameter 380: 55 10 1.8 0.24
0.39370 10! , 8 0.
24 0.36* 200 work] K cooling table ■ Within the scope of the present invention 1 Metoglas Inner diameter I72 53260
5 S-2 outer diameter 375 2 Metoglas inner diameter 172 54260
5 S-2 Outer diameter 375 3 Glass Inner diameter 172 56260
53-2 Outer diameter 378 4 Metoglas Inner diameter 172 55260
5S-2 outer diameter 378 340 6.5 1.4 (1240,
443506, 51, 10, 160, 29 3606, 51, 30, 190, 36 3706, 51, 60, 220, 4J U.S. Cooled to 200°C, then further tested three types of cores without heat insulation treatment. After annealing by rapid heat treatment, their magnetic values were measured at an induction of 1.40 Tesla and a frequency of 60 Hz.

The magnetic properties of the rapidly annealed cores without heat insulation treatment are shown in Table 3.

Table ■ Outside the scope of the present invention J Metoglas Inner diameter 172 5426
05 S-2 Outer diameter 373 2 Metoglas Inner diameter 5426
05S=2 Outer diameter 373 3 Metoglas Inner diameter 172 562
605 s-2 outer diameter 382 3506°5 1.9 0.36 0.4
9360 6.5 2.1 0.37
0.55360 6, 5 2.2
0.32 0.77 Cooled to 200° C. In contrast to the core in Table 2, the core in Table 2 exhibited higher coercive force and higher magnetic loss.

Although the present invention has been described in considerable detail, it is not necessary to adhere to such detailed description, and further changes and modifications will be apparent to those skilled in the art, all of which fall within the scope of the invention as set forth in the claims. include.

[Brief explanation of drawings]

FIG. 1 is a plot showing the time-temperature profile of a magnetic core annealed by a conventional annealing method. FIG. 2 is a plot showing the time-temperature profile of a magnetic core annealed by the annealing method of the present invention. Warm, nose 0c! "Yo" Yo3

Claims (10)

[Claims] (1) The improvement consists of a step of insulating the inner and outer surfaces of the core before the heating process.
A method of annealing a magnetic core comprising heating the magnetic core, which has formed a top and bottom surface, to a first temperature, holding this temperature for a predetermined period of time, and then cooling to a second temperature. (2) The method of annealing a magnetic core according to claim 1, wherein the heat insulation step comprises bonding a heat insulator to the inner and outer surfaces to cover substantially the entire surface thereof. (3) The insulation process (a) forms an insulator having a thermal conductivity of about 0.03 to 0.14 W/m°C and a linear shrinkage of about 1 to 3% up to 500°C; (b) this insulation (c) deposit the insulation in such a way that its thickness extends radially outward from the outer surface of the core and radially inward from the inner surface, and is about 25 to 75 mm; A method of annealing a magnetic core according to claim 2, which comprises: (4) The method of annealing a magnetic core according to claim 3, wherein the step of applying the heat insulator is selected from the group consisting of painting, casting, dipping, and wrapping. (5) Ac iron loss of approximately 0.16 to 0.25 W/kg, excitation force of approximately 0.25 to 0.45 VA/kg, and coercive force of approximately 1.
Induction 1-1.6A/m 1.4 Tesla and frequency 60
A magnetic core for an electromagnetic device, annealed by the method according to claim 1, having annealing at Hz. (6) The method for manufacturing a magnetic core according to claim 3, wherein the step of applying the heat insulator comprises wrapping. (7) Heat the core in an open chamber with a peak open temperature approximately 100 to 160°C higher than the first temperature, and set the peak temperature when the core approaches the first temperature and is within the range of approximately 15 to 45°C. A method of annealing a magnetic core according to claim 1, wherein the magnetic core is lowered to a first temperature. (8) The method of annealing a magnetic core according to claim 1, wherein the heating step is performed in the absence of a magnetic field. (9) The ribbon is essentially Co_6_6Fe_4Ni_1
B_1_4Si_1_5 and Fe_7_6_. ＿８＿
5Cr_2B_1_6_. _1Si_4_. _8C_0
＿． The method of annealing a magnetic core according to claim 1, having a composition selected from the group consisting of _2_5. (10) defining a central aperture whose inner surface extends substantially coaxially with the centroid of the core, and whose top and bottom surfaces lie in a plane substantially perpendicular to each cylindrical surface formed by the outer and inner surfaces, respectively; A method of annealing a magnetic core according to claim 1.