JPS6251009A - Magnetic core and its production - Google Patents

Abstract

PURPOSE:To prevent the generation of a false gap function and to secure the satisfactory electromagnetic characteristics, by burying a nonmagnetic material on a medium rubbing surface at an approximately entire outer edge of a magnetic material near a gap. CONSTITUTION:Both core halves 6 and 6' are joined together by means of the glass 58, 59 and 57 of low menting points serving as the nonmagnetic adhesive material a filled into a part of a winding groove 53 and an adhering groove 53' and the whole of a groove 56. While the glass 57 of a low melting point is filled into both grooves 56 and 56' adjacent to both sides along the track width direction against the metallic magnetic films 55 and 55' holding a magnetic gap 61 on a magnetic tape rubbing surface of a magnetic recording medium on the upper surface side shown in the diagram. At the same time, the nonmagnetic glass 52 of a high melting point is filled into the grooves 51 and 51. In such a way, both glass 57 and 52 are buried on the magnetic tape rubbing surface with adjacency to the entire outer edges of both films 55 and 55'.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic core and a method for manufacturing the same, and more particularly to an inductive magnetic head that records and reproduces information by sliding a magnetic gap on a magnetic recording medium. The present invention relates to a magnetic core constituting a magnetic path and a method for manufacturing the same.

[Prior Art] Ferrite (a sintered magnetic core material of metal oxide) has been widely used as a magnetic core material for the above-mentioned induction type magnetic head. Since ferrite has a high specific resistance, a ferrite head using ferrite as a core material has less loss in the high frequency range and also has excellent wear resistance.

On the other hand, in recent years, with the development of high-density magnetic recording in video tape recorders and still videos with tape widths of 8 mm and 1 mm, magnetic recording media with high coercive force, for example, magnetic recording media with a coercive force of 10 mm
The need for a magnetic head with a high saturation magnetic flux density that can record on 000e metal tapes and the like is rapidly increasing.

However, since ferrite has a relatively low saturation magnetic flux density,
Ferrite heads have the disadvantage that they cannot perform sufficient saturation recording on high coercivity magnetic recording media.

On the other hand, there are bulk metal magnetic materials such as sendust (Fe-Affl-3i alloy) and amorphous alloys as core materials with high saturation magnetic flux density, but when these metal magnetic materials are used as core materials, Since the resistivity is small, the eddy current loss is large in the high frequency region, and the magnetic permeability is reduced.

Therefore, as shown in FIGS. 17 and 18, a magnetic core structure constructed by combining ferrite and the above-mentioned magnetic metal materials has been adopted.

In the structure shown in FIG. 17, a core half body 1.1' is formed by laminating ferrite chips 10° 10' thin metal magnetic material [12, 12'] with an insulating layer 13.13' made of 5i02 or the like interposed therebetween. A winding groove 14 is formed in one of the core halves 1, and the core halves 1.1' are butted against each other through a magnetic gap 11 and joined together.

In addition, in the structure shown in FIG. 18, core halves 22 and 21' made of metal magnetic material are butted and joined through a magnetic gap 21, and winding grooves 24 made of ferrite are formed in the lower regions of both sides. Reinforcement plates 20 and 20' are attached, and reinforcement plates 23 and 2 made of non-magnetic material are attached to the upper region.
3' is attached.

However, according to these structures, in the manufacturing process, it is necessary to butt the core halves 1.1' one by one in the structure shown in FIG. 17, and in the structure shown in FIG.
", 23, 23' are required to be pasted together, and both have disadvantages in that productivity is poor and variations in characteristics become large.

Therefore, a so-called composite core as shown in FIG. 19 has been proposed in Japanese Patent Application Laid-Open No. 51-8517, etc., as a structure that has a manufacturing process relatively similar to that of conventional ferrite cores, has good productivity, and has a high saturation magnetic flux density. Proposed.

In this structure, each core half 3.3' is constructed by forming a metal magnetic film 32, 32' made of sendust or the like on one surface of a ferrite chip 30, 30'. The surfaces on which the metal magnetic films 32 and 32'' are formed are abutted against each other with a magnetic gap 31 interposed therebetween and are bonded.

However, in this structure, metal magnetic films 32, 32' and ferrite chips 30, 30 are formed on the sliding surface of the magnetic tape at the top in the figure.
Since there is a boundary 33, 33' between the magnetic holes 33 and 33', which is parallel to the magnetic gap 31, there is a drawback that it acts as a pseudo gap and has a negative effect on the electromagnetic conversion characteristics of the head.

Therefore, the structure shown in Fig. 20 was developed in JP-A-53-118.
No. 809, Japanese Patent Publication No. 57. -84324, JP-A-58-
This method has been proposed in, for example, No. 17522 and Japanese Unexamined Patent Publication No. 58-220232.

In this structure, each core half 4.4' has a nonmagnetic plate 45, 45' adhered to the upper surface of the magnetic tape sliding side of the ferrite chip 40.40', and a metal magnetic film 42 on one surface of each core half. .42' is formed, and the surfaces of the core halves 4, 4' on which metal magnetic films 42 and 42' are formed are abutted against each other via a magnetic gap 41 and fixed.

[Problems to be Solved by the Invention] In the structure shown in FIG. 20, the non-magnetic plate 45 on the magnetic tape sliding surface
, 45' and the metal magnetic film 42, the boundary 43 between 42'
, 43' do not act as a pseudo gap, so there is no problem due to the pseudo gap effect. However, the adhesive strength of the adhesive surfaces 46, 46' between the ferrite chips 40, 40' and the non-magnetic plates 45, 45'' is a problem, and the non-magnetic plates 45, 45' may peel or chip during processing. The drawback was that reliability and productivity were poor.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a magnetic path of an inductive magnetic head that records and reproduces information by sliding a magnetic gap on a magnetic recording medium. In a magnetic core configured such that a portion near the gap and a portion other than the gap are formed of different magnetic materials, a non-magnetic material is embedded in the medium sliding surface in contact with almost the entire outer edge of the magnetic material near the gap.

Further, in the method for manufacturing a magnetic core of the present invention, after forming a first groove having a width equal to or larger than a track width in a substantially linear shape in a block made of a first magnetic material, a non-magnetic material is buried in the groove. a step of processing the block into a core half block having a core half shape in cross section after cutting the block along a cut surface intersecting the groove; and attaching a second magnetic material to the cut surface of the core half block. a step of forming a second groove for determining the track width between the buried portion of the non-magnetic material on the attachment surface; and a step of connecting the core half blocks to each other through a magnetic gap material after forming the second groove. The second groove is filled with a non-magnetic adhesive and joined to obtain a core block.

[Function] According to the structure of the present invention described above, almost the entire outer edge of the magnetic material near the magnetic gap on the sliding surface of the magnetic recording medium is in contact with the non-magnetic material, and there is no boundary between different magnetic materials. Since the non-magnetic material is embedded in the sliding surface, there is little risk of peeling or chipping during the manufacturing process.

Further, according to the above manufacturing method of the present invention, a magnetic core having the structure of the present invention can be manufactured, in which case a non-magnetic material is used.

Since the non-magnetic adhesive is buried as described above, peeling and chipping are less likely to occur as described above.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing the structure of a magnetic core according to a first embodiment of the present invention.

As shown in the figure, the magnetic core of this embodiment has a code of 6.6'.
It is constructed by abutting and joining two core halves shown through a magnetic gap 61, and a winding groove 53 for winding a coil winding (not shown) is provided on the upper part of the abutting surface of one core half 6. is formed, and an adhesive groove 53' is formed at the lower end.

The core half 6.6' is made of low-melting glass 58, 59, 57 made of a non-magnetic adhesive filled in a part of the winding groove 53, a part of the adhesive groove 53', and all of the groove 56 to be described later. It is joined by

In addition, each of the core halves 6 and 6' has a ferrite chip 6.
Sendust (Fe-A
It is constructed by forming a metal magnetic film 55.55'' of high saturation magnetic flux density made of a material such as FFL-3T alloy.

Further, on the magnetic tape sliding surface of the magnetic recording medium shown on the upper side of the figure, there are grooves 56, 5 adjacent to both sides along the track width direction with respect to the metal magnetic film 55° 55' portion sandwiching the magnetic gap 61.
6'' is formed, and the track width is determined by this groove 56.56''. And this groove 56.56"
As described above, the low melting point glass 57 is filled and buried therein. In addition, grooves 51 and 51 are adjacent to the metal magnetic film 55 and 55' on both sides along the magnetic tape sliding direction in the left-right direction in the figure, and have a width slightly larger than the track width and are magnetic except for the magnetic film portion. The grooves 51 and 51 are formed across the entire sliding surface of the tape in the sliding direction, and a high melting point glass 52 made of a non-magnetic material is filled and buried therein. In this way, the low melting point glass 57. High melting point glass 52 is embedded.

According to this structure, the abutting surface portion of the core halves 6.6' is made of a metal magnetic film 55.55' with a high saturation magnetic flux density, and the remaining part is made of a ferrite chip 60.60'' with a high specific resistance. As a result, it is possible to achieve a high saturation magnetic flux density and high specific resistance as a whole, and it is possible to perform saturation recording on a magnetic recording medium with a high coercive force, and to reduce loss in a high frequency region.

Also, on the sliding surface of the magnetic tape, metal magnetic films 55, 55
' Outer edges 63 , 63 ' parallel to the magnetic gap 61
The entire outer edge including the non-magnetic high melting point glass 52 and low melting point glass 56 are in contact with each other, and there is no boundary with the ferrite portion of the ferrite chip 60, 60', so no pseudo gap effect occurs.

Furthermore, since the high melting point glass 52 and low melting point glass 57 exposed on the magnetic tape sliding surface are buried in the magnetic tape sliding surface, peeling or chipping of these non-magnetic material parts during the manufacturing process is prevented. few.

Next, the method for manufacturing the core of this embodiment having the above structure was carried out in a second manner.
This will be explained with reference to FIGS. 8(a) and 8(b).

First, a rectangular ferrite block 5 as shown in FIG. 2 is formed from ferrite, and linear grooves 51 are formed in parallel at predetermined intervals on its upper surface. The width of this sowing groove 51 is equal to or larger than the track width of the finished magnetic core, and the depth is at least larger than the gap depth of the finished product.

Next, as shown in FIG.
is filled with high melting point glass (working temperature 600°C or higher) 52. Thereafter, as shown by the broken line in the same figure, the ferrite block 5 is cut with a cut surface having an appropriate azimuth angle θ or perpendicular to the groove 51 to a thickness corresponding to the width of the ferrite chip 60 and 60'. disconnect.

Next, as shown by reference numerals 50 and 50' in FIGS. 4(a) and 4(b), two core half blocks obtained by the above cutting are prepared, and the core half blocks 50 are wound around the above cut surface of one of the core half blocks 50. Line groove 5
3 is formed along the rear end of the high melting point glass 52, and an adhesive groove 53' is formed along the edge on the opposite side to the high melting point glass 52.

Next, as shown in FIGS. 5(a) and 5(b), the above-mentioned magnetic metal 1g 155, 55' is applied to the entire surface of the cut surface of the core half blocks 50, 50' by a method such as sputtering.
Formed by adhering metal magnetic material.

Next, as shown in FIGS. 6(a) and 6(b), each high melting point glass is buried at the corner of the metal magnetic film 55° 55' forming surface of the core half blocks 50, 50'' and the high melting point glass 52 buried surface. A groove 56.56'' is formed between the parts. This groove 56.5
As mentioned above, the interval Tw of 6'' is the track width of the finished product.

Next, after polishing the metal magnetic film surfaces of the core half blocks 50 and 50'', a nonmagnetic layer such as 5i02.Aj! to form.

Thereafter, as shown in FIG. 7, the core half block 50 is
, 50' are butted together with the metal magnetic film forming surface through the magnetic gap 61, and a low melting point glass (working temperature 600°C or less) 57 is placed on the top of each groove 561, winding groove 53, and adhesive groove 53'.
, 58.59 and core half block 50.50"
Glue.

FIG. 8(a) is a plan view of the surface of the thus obtained core block 100 corresponding to the magnetic tape rolling surface.
The finished product shown in the figure is obtained.

In addition, in the above process, if the azimuth angle is not set when cutting as shown in FIG. 3, the core block 100 will be cut as shown in FIG.
). In this case, the core block is cut to form an azimuth angle as shown by the broken line in the same figure.

The magnetic core shown in FIG. 1 can be manufactured as described above, and in this case, the high melting point glass 52 exposed on the sliding surface of the magnetic tape. Since the low melting point glass 56 itself is buried by filling with an adhesive, there is little chance of peeling or chipping as described above.

1L11 In the first embodiment described above, there is some problem in the adhesion strength of the metal magnetic film 55,55' formed in the steps shown in FIGS. 5(a) and (b), and as a result, for example, as shown in FIG. 6(a). , (b) when forming the grooves 56 and 56', peeling of the metal magnetic film may occur. Further, in the structure of the first embodiment, the metal magnetic material is exposed at the butt bonding portion except in the vicinity of the magnetic gap, but the metal magnetic material has poor wettability with glass, so that adhesive strength cannot be obtained.

A second embodiment of the present invention that solves these problems will be described with reference to FIGS. 9 to 16 (a) and (b). In addition, in these figures, FIGS. 1 to 8(a) of the first embodiment
, The same reference numerals are given to the same or corresponding parts as in (b), and a detailed explanation of the same parts will be omitted.

FIG. 9 is a perspective view showing the structure of the magnetic core of this embodiment. As shown in the figure, the magnetic core of this embodiment differs from the first embodiment in the metal magnetic material portion.

That is, the metal magnetic material is located between the parts of the magnetic tape sliding surface sandwiching the magnetic gap 61 as shown by 70, 70', and 71;
It is provided only in the portion of the core half 6 facing the winding groove 53. The metal magnetic materials 70 and 70' provided across the magnetic gap 51 are not formed in a film shape but in a bulk shape with a substantially semicircular cross section, and are embedded in the magnetic tape sliding surface. Further, the metal magnetic material 71 facing the winding groove 53 is formed in a film shape. The structure of other parts is the same as that of the first embodiment.

Next, the manufacturing method of this example will be explained below.

First, as shown in Figure 1O and Figure 11, Figure 2 mentioned earlier,
Similarly to the process shown in FIG.
After filling and embedding the high melting point glass 52 in the groove 51, the ferrite block 5 is cut to form the structure shown in FIGS. 12(a) and 12(a).
The core half blocks 50, 50' shown in b) are obtained.

Next, as shown in both figures, one core half block 50 has a winding groove 53. An adhesive groove 53' is formed. In this embodiment, in addition to this, grooves 74 and 74'' having approximately semicircular cross sections are formed in the high melting point glass embedded portions of the cut surfaces of both core half blocks 50 and 50'', respectively. These grooves 74 and 74' are for embedding metal magnetic materials 70 and 70' sandwiching the magnetic gap 61 mentioned above.

Next, a metal magnetic material such as sendust is deposited on the entire cut surface side of the core half blocks 50, 50' (excluding the adhesive groove 53') by sputtering or the like. This deposition is continued until the entire structure 74, 74'' is filled with the metallic magnetic material.

Thereafter, the cut surface of the core half block 50.50'' is polished, and the metal magnetic material 70°70' in the grooves 74 and 74' and the winding groove are polished as shown in FIG. The metal magnetic material is removed from the cut surface, leaving 53 portions of the metal magnetic material 71.

In the subsequent steps, as shown in FIGS. 14 to 16(a) and (b), the core half block is manufactured in the same way as the steps in FIGS. 6 to 8(a) and (b) of the first embodiment. After forming grooves 56°56' to determine the track width at 50.50', a nonmagnetic layer is formed corresponding to the magnetic gap width, and then a core half block 50 is formed.
50' are butted together through a magnetic gap 61 and bonded with low melting glass 57, 58, 59 to form the core block 10.
0 is obtained, and this is cut to obtain the finished product shown in FIG.

According to this embodiment as described above, the metal magnetic materials 70, 70
' are buried in bulk in the grooves 74 and 74', and the metal magnetic material 71 is provided in the winding groove, so there is little risk that these metal magnetic material parts will peel off during the manufacturing process. Since most of the ferrite portion is exposed at the butt bonding portion of the core half blocks 50, 50', a high bonding strength almost equivalent to that of a conventional ferrite core can be obtained.

In addition to these effects, of course, the same effects as in the first embodiment described above can be obtained for the same reasons as in the first embodiment.

Note that the above 1. In the second embodiment, a metal magnetic film 55.55'' or a metal magnetic material 7 is used on the magnetic tape sliding surface.
Although the entire outer edge of 0.70' is assumed to be in contact with the low melting point glass and the high melting point glass, there may be a contact portion with the ferrite as long as it is a very small portion or a portion that is not parallel to the magnetic gap. .

[Effect 1 As is clear from the above explanation, according to the configuration of the present invention,
Since almost the entire outer edge of the magnetic material near the magnetic gap on the sliding surface of the magnetic recording medium is in contact with the non-magnetic material, a pseudo gap effect does not occur and good electromagnetic conversion characteristics can be obtained. Furthermore, since the non-magnetic material is embedded, defects such as peeling and chipping during the manufacturing process are reduced, so reliability and productivity can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a magnetic core according to a first embodiment of the present invention, FIGS. 2, 3, and 4 (a), (b)
, Fig. 5 (a), (b), Fig. 6 (a), (b)
), FIG. 7 is a perspective view sequentially showing the manufacturing process of the core shown in FIG. 1, and FIG. 8(a). (b) is a plan view and an explanatory view of the core block respectively explaining the final cutting step of the same process, FIG. 9 is a perspective view of the magnetic core according to the second embodiment, FIG. 1θ, and the manufacturing process of FIG. FIGS. 16(a) and 16(b) are respectively plan views illustrating the final cutting process of the same process, and FIGS. 17 to 20 are perspective views showing different structures of conventional magnetic cores. It is a diagram. 5... Ferrite block 6.6'... Core half body 50... Core half block 51.56.56', 74... Groove 52... High melting point glass 53... Winding groove 53'...
・Adhesive grooves 55, 55'...Metal magnetic film 57, 58, 59...Low melting point glass 60, 60'...Ferrite chip 61...Magnetic gap 70, 70', 71...All Magnetic material 100...core block

Claims (1)

[Scope of Claims] 1) A magnetic path of an inductive magnetic head that records and reproduces information by sliding a magnetic gap on a magnetic recording medium is configured, and a portion near the gap and a portion other than the gap are made of different magnetic materials. 1. A magnetic core formed of a magnetic core, characterized in that a non-magnetic material is buried in contact with almost the entire outer edge of the magnetic material in the vicinity of the gap on the medium sliding surface. 2) After forming a first groove having a width equal to or larger than a track width in a substantially straight line in a block made of a first magnetic material, embedding a non-magnetic material in the groove, and cutting the block at a point that intersects with the groove. determining a track width between a step of cutting at a surface to obtain a core half block, a step of attaching a second magnetic material to the cut surface of the core half block, and a non-magnetic material buried portion of the adhesion surface. forming a second groove; after forming the second groove, butting the core half blocks together via a magnetic gap material; filling the second groove with a non-magnetic adhesive;
A method for manufacturing a magnetic core, comprising the step of joining to obtain a core block.