JPH065567B2 - Method of manufacturing core for magnetic head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetic head core, and more particularly to a method for advantageously manufacturing a magnetic head core having a narrow track width in a magnetic head core made of a ferrite material. It is about.

(Prior Art and Problems Thereof) Conventionally, as a method of manufacturing a core for a magnetic head having a narrow track width, a method of forming a track by laser processing has been known. It is disclosed in Japanese Patent Publication No. 53-80212. For example, Japanese Patent Laid-Open No. 57-212617 discloses a method of forming a center rail several times thicker than the track width, leaving the track portion, and removing unnecessary portions on both sides by laser processing. By this manufacturing method, the magnetic head core as shown in FIG. 3 is obtained.

However, in these methods, in addition to the inconvenience of having to process each core, the track portion is protected in the groove 20 that defines the width of the track 8 formed by laser processing. Since it is extremely difficult to industrially carry out the step of burying the glass, the glass is actually used without filling the groove 20 with the glass, and the reliability as a magnetic head core is poor. There was a drawback.

Further, as another example, on a gap line of a so-called gap bar, which includes a long C-shaped core and an I-shaped or C-shaped core,
Grooves (holes) reaching the coil winding groove are continuously formed by multi-row laser processing so as to leave the track width,
After burying glass in the groove, there is a method of cutting into individual magnetic head cores (core chips).

However, in this method, since the laser processing is performed directly on the flat surface of the gap bar, it is not possible to efficiently remove the workpiece outside the groove (hole) for defining the track width, The processing takes time, which causes problems such as cracks in the track portion and sticking of the melt. In addition, the temperature distribution in each part of the wall surface of the groove (hole) becomes non-uniform, and the wall surface of the groove (hole) is undulated, resulting in a decrease in dimensional accuracy of the track width. It was difficult to carry out industrially as a manufacturing method of.

(Object of the Invention) The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a magnetic head core having a narrow track width and high reliability at low cost. It is to provide a method that can be manufactured.

(Structure of the Invention) In order to achieve such an object, the method of manufacturing a magnetic head core according to the present invention is characterized in that a gap bar in which an annular magnetic path having a magnetic gap of a predetermined gap is formed is used. When the core chip is cut out to manufacture the desired magnetic head core, the gap width of the gap bar is sufficiently wider than the track width of the magnetic head core in the direction in which the magnetic gap extends. After providing at least a pair of first grooves extending in a direction traversing the magnetic gap at intervals, further extending in a direction close to each other from the pair of first grooves at a magnetic gap forming portion of the gap bar. By forming the second groove so that a track portion having a predetermined width remains in the middle portion, the groove is sandwiched between the pair of first grooves. The magnetic gap exists only in the track portion in the cap bar portion.

In manufacturing such a magnetic head core of the present invention, (a) the magnetic gap extends on the magnetic gap forming surface of a gap bar having a magnetic gap of a predetermined gap and in which an annular magnetic path is formed. In a direction at a distance sufficiently wider than the track width of the magnetic head core, at least a pair of first grooves extending in a direction crossing the magnetic gap, and (b) at a magnetic gap forming portion of the gap bar, Forming a second groove so that a track portion having a predetermined width remains in an intermediate portion in a direction in which the pair of first grooves are close to each other; and (c) in the first groove and in the second groove. By embedding a non-magnetic material such as glass in the groove of
A method including a step of forming a core bar and a step of (d) cutting out the core bar to a predetermined core width including the track and forming a core chip is suitably adopted.

By the way, in the present invention, various conventionally known magnetic materials, preferably ferrite materials, are used as the material of the magnetic head core, and the core is filled in the first groove and the second groove. As a non-magnetic material,
Glass will be preferably used.

In addition, a so-called drilling method such as ultrasonic machining or electric discharge machining is appropriately adopted for machining the second groove according to the present invention. In order to define the track width that determines the recording width on the magnetic recording medium, and to process the vicinity of the magnetic gap part where signals come in and out to form the second groove, the processing The method is required to have high dimensional accuracy and low processing strain. Therefore, laser processing is preferably used for processing the second groove. However, laser processing is a method of melting and evaporating a work piece by heat of laser light, which may cause processing strain or cracks due to heat on the work surface, or the melt may stick to the work surface. Therefore, more preferably, a laser-induced etching method is employed, in which the work piece is removed by a chemical reaction. It should be understood that the laser processing referred to in the present invention is used as a general term including this laser induced etching.

Here, the at least one pair of first grooves formed in the gap bar according to the present invention is used for scattering the work piece out of the second groove when laser processing the second groove as described above. It plays a role as a route. Therefore, due to the presence of such a first groove, the processing speed of the second groove can be improved, and at the same time, the effect of preventing the occurrence of cracks in the track portion and the fixation of the melt can be achieved. is there. Further, when laser-induced etching is applied, this first groove serves as a discharge path for the reaction product of the work piece and the atmosphere, and facilitates the diffusion of the reactant to the work point. It also plays a role of increasing the processing speed.

It is obvious that the magnetic gap portion other than the gap portion of the track portion is not allowed to remain on the sliding contact surface of the magnetic head core. Therefore, the above-mentioned second groove defines the track width. Not only does it play a role in removing unnecessary gaps. Therefore, in consideration of these points, the second groove is formed so that the width thereof is 10 times or more the predetermined magnetic gap length (gap) so as to avoid adverse effects such as noise due to the pseudo gap effect. Is desirable.

(Specific Description of Configuration) Hereinafter, in order to more specifically clarify the present invention, a specific configuration of the present invention will be described in detail with reference to the drawings.

First, in the present invention, an annular magnetic path is formed by the presence of a hole for coil winding, and a gap bar is formed in which a magnetic gap having a predetermined gap is provided in a direction crossing the magnetic path. Various conventionally known magnetic materials can be used as the material that provides the core block used, but in general, Mn-Zn ferrite and Ni-Zn are generally used.
Ferrite materials such as ferrite will be used properly according to the application. Then, generally, those made of the same material are advantageously used. Regarding the fine structure of each ferrite member, each ferrite material may be a polycrystalline material, a single crystal material, or a composite material including a polycrystalline portion and a single crystal portion. It is also possible to use a combination of ferrite members having different texture structures.

Then, one specific method of manufacturing the intended magnetic head core according to the present invention using such a ferrite material is schematically shown in FIG.

That is, the pair of core blocks 1 in the shape of a long square bar,
A groove 1a for coil winding is formed on one side of 1 ', and the core blocks 1, 1'are butted and joined to each other, whereby a predetermined gap (length) is provided at the butted portion.
The magnetic gap 2 is formed, and the gap bar 4 having an annular magnetic path is obtained by forming the coil winding hole 3 based on the existence of the groove 1a.

Here, even in the operation of joining the pair of core blocks 1, 1 ′, the operation of forming the magnetic gap 2, the operation of forming the groove 1 a for the coil winding, etc., a known method is appropriately adopted. Thus, for example, in the joining of the core blocks 1 and 1 ′, in addition to joining by glass, joining by solid phase reaction or the like is adopted. In any case, since the gap bar 4 is manufactured according to a known method, a detailed description will be omitted here,
If necessary, Japanese Patent Application No. 58-246 filed by the applicant of the present application
261, Japanese Patent Application No. 58-246262, Japanese Patent Application No. 61-
See 131196, etc.

Next, with respect to such a gap bar 4, a plurality of pairs of grooves 6 and 6'extending in a direction crossing the magnetic gap 2 and substantially parallel to each other are formed with a width sufficiently wider than the track width of the target magnetic head core. After sequentially forming a predetermined interval in the extending direction of the magnetic gap 2 so as to leave the convex portion 5,
At the magnetic gap forming portion of the convex portion 5, a track 8 having a predetermined width is left and the magnetic gap length 10
The second groove 7 having a width more than double is formed by laser processing, more preferably laser induced etching.

Then, a glass 9 as a predetermined non-magnetic material is placed on the gap bar 4 provided with the pair of first grooves 6 and 6'and the second groove 7 and heated, By being melted, the first groove 6,
6'and the second groove 7 are filled so that the core bar 1
0 is formed. In this core bar 10,
After machining the air bearing surface grooves 17 along the first grooves 6 and 6 ′, the width of the center rail 12 is regulated at the same time, and then the yoke 15 and the tapered portion 16 are formed, and then the air bearing surface 14 and the core 18 are predetermined. Then, the target magnetic head core 18 is formed by cutting out so as to have the width.

The magnetic head core 18 thus obtained is compared with the conventional magnetic head core 21 shown in FIG.
Glass 9 for protecting the track portion is buried in both side surfaces of the track 8, and the reliability of the mechanical strength and the like of the track 8 can be remarkably improved as compared with the conventional magnetic head core. .

Although the magnetic head core according to the present invention and an example of manufacturing the core have been described above, the present invention should not be construed as being limited to the specific examples given above, and does not depart from the gist of the present invention. It goes without saying that various changes, modifications, improvements, etc. can be added based on the knowledge of those skilled in the art, and it should be understood that the present invention includes those of such embodiments. .

For example, although the manufacturing method of the core for the monolithic type RDD head has been described above as an example, the present invention is not limited to this, and the core for the composite type RDD or VTR head as shown in FIG. It can also be advantageously applied to the manufacture of magnetic head cores having other structures such as.

Further, the various features of the present invention described in detail above can be easily understood from the following examples.

(Embodiment) First, a magnetic disk device (RDD) shown in FIG.
Of the core for the monolithic type RDD head used for
The desired core was manufactured according to the manufacturing process according to the present invention. Therefore, the gap bar 4 made of Mn-Zn ferrite polycrystalline material is machined with a diamond cutter in a direction orthogonal to the magnetic gap 2 so that the width of the uncut convex portion 5 becomes 0.5 mm. A plurality of pairs of parallel first grooves 6 and 6'having a diameter of 3.5 mm were formed at intervals of 3.5 mm. The depth of the grooves 6 and 6'was 0.2 mm deeper than the bottom of the gap 2, the so-called bottom of the depth.

Then, in the gap portion 2 of the uncut uncut convex portion 5, the second groove 7 is formed so that the width of the track 8 is 20 μm and the width of the groove 7 is 50 μm on both sides of the gap portion 2 and the total is 0.1 mm.
It was formed by laser processing under the conditions shown in the table below. In addition,
The depth of the groove 7 was 0.1 mm deeper than the lowermost end of the depth part.

After that, the filling glass 9 is placed on the gap bar 4, placed in an electric furnace and heated to melt the glass 9 to define the width of the track 8 (second groove) 7 And the first grooves 6, 6 ′ were filled. At the time of melting the glass 9, the atmosphere in the furnace was controlled to be substantially the same as the equilibrium oxygen partial pressure of ferrite so that the magnetic characteristics of the ferrite would not be deteriorated by the reaction between oxygen and ferrite in the furnace. Thus, the gap surface of the gap bar 4 filled with glass, in other words, the surface on which the glass 9 was placed was polished to a predetermined depth length to obtain the core bar 10.

In this core bar 10, along the first grooves 6, 6 '
After forming the air bearing surface grooves 17 at intervals of 0.4 mm, the tapered portion 16 having a predetermined angle is further processed, and then the yoke 15 is 0.4 mm.
Formed with a width of. After that, the width of the air bearing surface 14 is 0.75 mm,
Cut out so that the width of the core 18 is 3.4 mm and
4 and the center rail 12 were chamfered to obtain a monolithic RDD head core 18.

The magnetic head core 18 thus obtained is different from the magnetic head core 21 shown in FIG. 3 in that the track portion 8 is reinforced by the glass 9 from both sides, so that the track portion has high mechanical strength and is reliable. It was a magnetic core for magnetic head. Further, by forming the pair of first grooves 6 and 6'before forming the second groove 7 that defines the width of the track 8, the work piece can be efficiently eliminated. As compared with the conventional method of forming a hole in the gap bar by laser processing, the processing time can be shortened to half, and the flatness of the side surface of the track portion 8 can be remarkably improved to improve the track width dimensional accuracy. It could be kept within ± 2 μm. Furthermore, almost no cracks or adhesion of the molten material could be found on the track portion 8.

As described above, the present invention is not limited to the method for manufacturing the core for the monolithic RDD head.
For example, it can be applied to a manufacturing process of a core for a composite type RDD head used in a magnetic disk device shown in FIG. Is a (100) plane, and the sliding contact surface with the recording medium is a (110) plane. The gap bar 4 is made of single crystal Mn-Zn ferrite, and is machined by a diamond cutter in a direction orthogonal to the gap 2. A plurality of parallel first grooves 6, 6 having a width of 0.2 mm are formed with a gap of 220 μm so that the width of the uncut portion 5 becomes 220 μm. The depth of the grooves 6, 6 ... Is set to be 0.1 mm deeper than the bottom of the gap 2, that is, the lowermost end of the so-called depth portion.

Next, in the gap portion 2 of the uncut residual convex portion 5, the second groove 7 is formed as described above so that the width of the track 8 is 13 μm and the width of the groove 7 is 50 μm on both sides of the gap portion 2. It was formed by laser processing under the same conditions.

Thereafter, the glass 9 is embedded in the same manner as described above, the tapered portion 15 is processed, and the core bar 10 is obtained by polishing to a predetermined depth length.
After being cut along the first grooves 6, 6 ... to have a thickness of .mu.m, both side surfaces of the core were polished by 20 .mu.m to obtain a core 19 for a composite type RDD head.

Unlike the conventional composite type RDD head core 22 shown in FIG. 4, the magnetic head core 19 thus obtained could effectively reduce the exposed area ratio of the glass on the sliding contact surface 11. The wear resistance could be significantly reduced. In addition, reproduction output, overwrite characteristics, crosstalk, etc., are the same as those of the conventional head core
Properties equal to or better than 2 were obtained.

Further, if the manufacturing method of the present invention shown in FIG. 2 is applied,
It is also possible to manufacture a VTR magnetic head core, in which case the groove 7 for defining the track width is processed once (twice including the machining of the first groove) and the glass embedding operation is performed once. In addition, in comparison with the number of processing steps, the number of processing, and the number of times of glass embedding in the manufacturing process of the magnetic head core 23 (FIG. 5) by conventional machining such as a diamond cutter, there is no track alignment step. It is significantly reduced.

(Effects of the Invention) As is clear from the above description, according to the method of manufacturing a magnetic head core according to the present invention, it is possible to inexpensively manufacture a magnetic head core having a narrow track width and high reliability. It has become possible, and there is a great industrial significance of the present invention.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing one manufacturing process of a magnetic head core according to the present invention, and FIG. 2 is an explanatory diagram showing one example of a manufacturing process of different magnetic head cores according to the present invention. Further, FIG. 3, FIG. 4 and FIG. 5 are perspective views each showing an example of a conventional magnetic head core. 1, 1 ': core block, 2: magnetic gap, 3: coil winding hole, 4: gap bar, 5: uncut convex portion, 6, 6': first groove, 7: second groove, 8: track 9: Glass, 10: Core bar 11: Sliding contact surface, 12: Center rail 18, 19, 2, 22, 23: Magnetic head core 13: Gimbal mounting groove 14: Air bearing surface, 15: Yoke 16: Tapered portion, 17: Air bearing surface groove, 20: Track width defining groove

Claims (7)

[Claims] 1. A core chip is cut out from a gap bar in which an annular magnetic path is formed by the presence of a hole for coil winding and a magnetic gap having a predetermined gap is provided in a direction traversing the magnetic path. When manufacturing the magnetic head core, the magnetic gap is formed with a gap sufficiently wider than the track width of the magnetic head core in the direction in which the magnetic gap extends, with respect to the surface of the gap bar on which the magnetic gap is formed. After providing at least a pair of first grooves extending in a direction traversing the, further, at the magnetic gap forming portion of the gap bar, second grooves extending in a direction close to each other from the pair of first grooves, respectively, By forming the track portion having a predetermined width in the middle portion, only the track portion is formed in the gap bar portion sandwiched by the pair of first grooves. A method of manufacturing a core for a magnetic head, characterized in that a magnetic gap exists. 2. The method of manufacturing a core for a magnetic head according to claim 1, wherein the material of the gap bar is ferrite. 3. A method of manufacturing a magnetic head core according to claim 1, wherein the second groove is formed by laser processing. 4. The method for manufacturing a magnetic head core according to claim 1, wherein the second groove is formed by ultrasonic machining. 5. The method for manufacturing a magnetic head core according to claim 1, wherein the second groove is formed by electric discharge machining. 6. The first to fifth aspects of the present invention, wherein the width of the second groove is 10 times or more the gap of the magnetic gap.
Item 8. A method for manufacturing a magnetic head core according to any one of items. 7. A non-magnetic material such as glass is filled in each of the first groove and the second groove prior to the cutting of the core chip.
Item 7. A method of manufacturing a magnetic head core according to any one of Items 6 to 6.