JP4154479B2 - Magnetic head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head, and more particularly, to a magnetic head including a wear-resistant film that can reduce the spacing loss of the magnetic head and can reduce the thermal load on the magnetic head during film formation.
[0002]
[Prior art]
FIG. 1 shows the configuration of a magnetic head that is used in sliding contact with a magnetic recording medium (hereinafter referred to as a recording medium). The magnetic head A includes a shield case 2 made of metal. The shield case 2 has a sliding contact surface 2a on which a recording medium slides, and an opening 2b is formed on the sliding contact surface 2a. A magnetic core 5 having a magnetic gap G is accommodated in the shield case 2, the upper surface of the magnetic core 5 forms a sliding contact surface 2a by an opening 2b, and the magnetic gap G is positioned in the opening 2b. An excitation coil 6 and a detection coil 7 are wound around the magnetic core 5, and these coils 6 and 7 are molded together with the magnetic core 5 by a resin member 9 in the shield case 2.
[0003]
The slidable contact surface 2a is covered with the wear-resistant layer 10 over the entire surface so as not to be worn or rusted when the magnetic core 5 or the like is slidably contacted with the recording medium.
In this case, the wear-resistant layer 10 slides so that the recording medium can smoothly come into sliding contact with the surface of the wear-resistant layer 10 as well as having high adhesion strength to the slide-contact surface and excellent wear resistance. It is required to be made of a material having good properties. Such materials include ceramic materials such as alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N ₄ ), titania (TiO ₂ ), partially stabilized zirconia (PSZ), Chromium oxide (Cr ₂ O ₃ ) or a mixture thereof or a compound thereof is used for the wear resistant layer 10.
[0004]
The wear-resistant layer 10 made of these ceramic materials is formed by, for example, thermal spraying, ion sputtering, ion plating, or CVD, and the thickness is usually 100 μm or more by thermal spraying, and 0 by other film deposition methods. .1 to 5 μm.
[0005]
[Problems to be solved by the invention]
From the viewpoint of wear resistance, thermal spraying is preferable. However, in the case of thermal spraying, a surface roughness defect of the wear-resistant layer 10 due to the pre-roughening treatment or the like occurs, and polishing treatment is required after film formation. There are many problems such that it is necessary to raise the temperature of the contact surface 2a to a temperature of about 200 ° C. and the film formation on the resin member 9 is impossible. Further, in order to reduce the spacing loss of the magnetic head A and improve the characteristics of the magnetic head, the wear-resistant layer 10 is preferably thin and spraying is not suitable. Therefore, the abrasion resistant layer 10 is formed by an ion sputtering method, an ion plating method or a CVD method among the methods described above. However, the wear-resistant layer 10 formed by these film forming methods has a drawback that when the thickness exceeds 5 μm, the internal stress becomes large, causing cracks and peeling, which is not sufficient from the viewpoint of wear resistance. In addition, when these film forming methods are employed, although depending on the film forming conditions, in order to increase the peel strength (adhesion strength) between the wear-resistant layer 10 and the sliding contact surface 2a to a practical level, It is necessary to raise the temperature of the sliding contact surface 2a to a temperature of at least 400 ° C. during film formation.
[0006]
However, when the magnetic head A is heated to increase the temperature of the sliding contact surface 2a, the insulation of the coil wire that is the material of the coils 6 and 7 is melted and short-circuited, and the coils 6 and 7 function as a coil. There is a problem in that the characteristics of the magnetic head A are lost due to disappearance or distortion of the resin member 9 due to internal stress, resulting in a deviation in the alignment of the magnetic core 5.
[0007]
On the other hand, as a means for solving the coating trouble such as peeling described above, Japanese Patent Application Laid-Open No. 2002-50004 discloses an abrasion resistant layer having a segment pattern. There is a problem that the manufacturing cost of the magnetic head is increased.
The present invention solves the above-described problems, can reduce the spacing loss of the magnetic head, and is an inexpensive magnetic head having a wear-resistant film that can reduce the thermal load on the magnetic head during film formation. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a shield casing having a sliding contact surface in sliding contact with a magnetic recording medium, and a magnetic member housed in the shield casing and part of the surface forming the sliding contact surface. There is provided a magnetic head comprising a core and a wear-resistant film that covers the entire surface of the sliding contact surface and is formed of fine particles of a ceramic material, and the magnetic core is made of permalloy .
[0009]
The wear-resistant layer has a thickness of Ru 1~100μm der. Then, the wear layer is Ru consists of alumina ceramics or zirconia ceramics.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The magnetic head of the present invention will be described below with reference to the drawings.
FIG. 1 shows a magnetic head B according to the first embodiment of the present invention.
The magnetic head B includes a hollow shield case 2 made of permalloy. The entire lower surface of the shield case 2 is opened, and the upper surface of the shield case 2 is a slidable contact surface 2a on which the recording medium is slidably contacted. The slidable contact surface 2a has an opening 2b, a radius of curvature of 12 mm, a width W shown in FIG. 1 of 11 mm, and a depth in a direction perpendicular to the drawing of 8 mm.
[0011]
A metal base 3 is accommodated in the lower part of the shield case 2. Base ends of hollow pins 4, 4 are connected to the lower surface of the base 3, and the pins 4, 4 protrude outward from the shield case 2.
A permalloy magnetic core 5 is disposed on the upper surface of the base 3. The magnetic core 5 is composed of two symmetrical members 5a and 5b. The members 5a and 5b are directly connected to each other at the lower end, and a gap having a predetermined width is formed at the upper end. This gap functions as a magnetic gap G, and a Be alloy plate, which is a nonmagnetic material, is interposed.
[0012]
A top surface including a magnetic gap G, which is a part of the surface of the magnetic core 5, is located in the opening 2 b with substantially the same curvature as the top surface of the shield case 2, and a sliding contact surface 2 a on which the recording medium slides. Is configured together with the upper surface of the shield case 2.
The magnetic core 5 is made of permalloy, but may be made of a magnetic material such as sendust or ferrite. However, the magnetic core 5 made of permalloy is preferable because the adhesion strength of the wear resistant film 11 is higher than when Sendust or ferrite is used.
[0013]
An excitation coil 6 and a detection coil 7 are wound around both sides of the magnetic core 5, and the coils 6 and 7 are connected to the outside of the magnetic head through pins 4 and 4. And the holders 8 and 8 made from a zinc alloy are arrange | positioned between the side surfaces of the shield case 2 and the magnetic core 5 in the state which does not contact these coils 6 and 7. FIG. The holders 8, 8 hold the magnetic core 5 in the shield case 2 and position the magnetic core 5 with respect to the shield case 2.
[0014]
The base 3, the pins 4, 4, the magnetic core 5 and the holders 8, 8 arranged as described above are molded and fixed by the resin member 9 made of epoxy resin in the shield case 2. A part of the surface constitutes the sliding contact surface 2a.
The members constituting the slidable contact surface 2a are not limited to the shield case 2, the magnetic core 5, and the resin member 9, and are appropriately set according to the specifications of the magnetic head. For example, in the magnetic head B, the holders 8 and 8 are not positioned on the sliding contact surface 2a, but the holders 8 and 8 together with the magnetic core 5 are in contact with the sliding contact surface 2a as in the magnetic head C shown in FIG. May be located in
[0015]
Examples of the material of the holders 8 and 8 include white, stainless steel, brass, aluminum, and zinc alloy. When the holders 8 and 8 are positioned on the sliding contact surface 2a as in the magnetic head C, other materials are used. Zinc alloy is preferable because the adhesion strength of the wear-resistant film 11 is higher than that of.
The present invention is characterized in that the entire sliding contact surface 2a of the magnetic head B described above is covered with the wear-resistant film 11 formed of fine particles made of a ceramic material. The wear-resistant film 11 formed of the fine particles is a polycrystalline film formed by bonding crystalline particles in a random direction, and each particle does not exhibit a self-shape unique to the material and is incomplete. It has a regular shape and a crystallite size of 0.1 μm or less.
[0016]
Here, the thickness D of the wear-resistant film shown in FIG. 1 is preferably as thin as possible within a film forming range in order to reduce the spacing loss of the magnetic head. Moreover, since the internal stress in a film | membrane will increase and the abrasion-resistant film will peel easily when the thickness of an abrasion-resistant film becomes thick, it is preferable that the thickness D of an abrasion-resistant film is 1-100 micrometers.
In addition, as a ceramic material for forming the wear-resistant film, alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N ₄ ) are considered in consideration of hardness (wear resistance) and lubricity. , Titania (TiO ₂ ), partially stabilized zirconia (PSZ), chromium oxide (Cr ₂ O ₃ ) and the like, and mixtures or compounds thereof, but since higher adhesion strength is obtained, alumina, zirconia and these Alumina-based ceramics or zirconia-based ceramics such as a mixture or compound of these are preferred.
[0017]
The above-described wear-resistant film can be produced by a film forming method (hereinafter referred to as a fine particle film forming method) in which fine particles of a ceramic material are sprayed at a high speed and a thin film is formed by the impact force.
Specifically, this fine particle film forming method is a method in which ceramic fine particles of 2 μm or less that are mechanically pulverized or adjusted to colloidal chemicals are flown at a flow rate of 100 m / min. When transported at a speed of s or more, sprayed onto the sliding contact surface, and collided with the substrate, the high kinetic energy of the fine particles induces local heating and mechanochemical reaction within the contact surface between the particle and the substrate, and the sliding Make a strong bond with the contact surface. In this case, wasteful thermal energy other than entrusting to bonding is hardly generated, and vacuum deposition or a thin film having the same fineness and strength as sputtering can be formed without substantially increasing the surface temperature of the sliding contact surface. Such a film forming method is disclosed in Japanese Patent No. 2963993, Japanese Patent No. 3015869, and the like.
[0018]
Thus, the wear resistant film obtained by the fine particle film forming method has excellent wear resistance because it has very little surface irregularities and good sliding properties, and furthermore, an ion sputtering method is applied to the sliding contact surface at a temperature of 400 ° C. Compared to the case where an abrasion resistant film is formed, it has a denseness and adhesion strength comparable to each other.
Therefore, according to the fine particle film forming method described above, it is not necessary to preheat the sliding contact surface to a high temperature state of 400 ° C. or higher as in the case of the sputtering method, the ion plating method and the CVD method. For this reason, the thermal load on the magnetic head is small when the wear-resistant film is formed. Therefore, in the magnetic head with the wear-resistant film, dielectric breakdown due to melting of the insulating coating of the coil or distortion due to internal stress is caused. Therefore, the occurrence of misalignment of the magnetic core 5 based on the above can be prevented, so that the magnetic head can be manufactured with a high yield.
[0019]
Further, the sliding contact surface 2a coated with the wear-resistant film by applying the fine particle film formation method can omit the abrasion-resistant film polishing process after the film formation, thereby simplifying and reducing the manufacturing process of the magnetic head. Therefore, Ra specified in JIS-B0601 is preferably adjusted to 0.3 μm or less before film formation.
1. Evaluation of abrasion resistance A load of 0.98 N in the longitudinal direction and a conveying speed are applied to the sliding contact surface 2a of the magnetic head B in which the wear-resistant film 11 of alumina ceramic having a thickness of 2.5 μm is formed on the sliding contact surface 2a. The relationship between the number of times of sliding contact (number of passes) and the wear depth of the wear-resistant film 11 was examined at 500 m / s, and the results are shown in FIG.
[0020]
Further, as a comparative example, using a magnetic head having the same structure as the magnetic head B except that the wear-resistant film 11 is not provided, the relationship between the number of sliding contacts and the wear depth of the sliding surface is the same as in the case of the magnetic head B. The results are shown in FIG.
As is clear from FIG. 3, the wear depth of the magnetic head B having the wear resistant film 11 was 1 μm or less when the number of passes was 1 million times, whereas the comparative example without the wear resistant film 11 was used. In this case, the wear resistance film 11 exceeds 0.3 mm, and it is found that the wear resistance film 11 is extremely effective in improving the wear resistance of the magnetic head.
[0021]
2. Evaluation of Adhesion Strength A wear-resistant film 11 made of alumina ceramic having a thickness of 2.5 μm is formed on the sliding contact surface 2a. The magnetic core 5 includes a lead core and a sliding contact of a magnetic head B including side cores arranged on both sides of the lead core. FIG. 4A shows the result of observing the slidable contact surface 2a by causing the 1000 yen bill to slidably contact the surface 2a 2.5 million times in the longitudinal direction at a load of 0.98 N and a conveyance speed of 500 m / s.
[0022]
Further, a wear resistant film 11 having a thickness of 2.5 μm is formed on the sliding contact surface 2a on a magnetic head having the same configuration as the magnetic head B except that the magnetic core is made of Sendust and the lead core and side core dimensions are different. A 1000 yen bill was brought into sliding contact under the same conditions as in the case of the magnetic head B, and the sliding contact surface 2a was observed. The result is shown in FIG.
[0023]
As shown in FIG. 4 (a), in the case of the magnetic head B having a permalloy magnetic core, the wear-resistant film 11 was not peeled off, whereas the magnetic head having a sendust magnetic core. In this case, as shown by the white arrow in FIG. 4B, local peeling of the wear-resistant film 11 was observed. This indicates that permalloy is preferable as the material of the magnetic core.
[0024]
In addition, this invention is not limited to the Example mentioned above, A various deformation | transformation is possible. For example, although the magnetic heads B and C are provided with a pair of excitation coils 6 and detection coils 7, it is needless to say that a plurality of pairs may be provided.
[0025]
【The invention's effect】
As described above, the magnetic head of the present invention is covered with a wear-resistant film whose sliding surface is formed of fine particles. This wear-resistant film has good sliding properties, excellent wear resistance, and adhesion. High strength.
The wear-resistant film has a thickness of 1 to 100 μm, can reduce the spacing loss of the magnetic head, and suppresses internal stress in the film and is difficult to peel off.
[0026]
Furthermore, since the wear-resistant film can be formed without heating the sliding contact surface, the thermal load on the magnetic head is small at the time of film formation, and the magnetic head can be manufactured with good yield.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a magnetic head according to an embodiment of the present invention.
FIG. 2 is a sectional view of a magnetic head according to another embodiment of the present invention.
FIG. 3 is a wear characteristic diagram of a magnetic head.
FIG. 4 is an observation result of an abrasion resistant film after an abrasion resistance test.
[Explanation of symbols]
B, C Magnetic head 2 Shield casing 2a Sliding contact surface 2b Opening 5 Magnetic core 6 Excitation coil 7 Detection coil 8 Holder 9 Resin member 10 Wear resistant layer 11 Wear resistant film G Magnetic gap

Claims (1)

A shield casing having a sliding contact surface in sliding contact with the magnetic recording medium; a magnetic core housed in the shield casing and having a part of the surface forming the sliding contact surface; A wear-resistant film formed of fine particles of material,
Wherein the magnetic core Ri consists of permalloy,
The wear-resistant film is made of alumina or zirconia,
The magnetic head according to claim 1, wherein the wear-resistant film has a thickness of 1 to 100 m .

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