JPS59167821A - Core assembly of magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To realize a titled high-quality assembly by providing plural recessed parts to an end face of a holding member at the side which is in contact with a core to reduce a residual stress at bonding. CONSTITUTION:A core block body A is formed by arranging a ferrite bar 20 and a ceramic bar 22 formed with the recessed parts 20a, 22a-22c on which a low-melting point glass bar 25 and a high-melting point glass bar 26 are held to both end faces of an I-shaped ferrite bar 21. The block body A is held by a jig and heated in a furnace, then the bars 20, 21 and the bar 22 are bonded. A core assembly B is formed by slicing after the bonding, the wear resistance is excellent for the upper bonding part of a holding core 22' and a core 21' because the part is formed with a high-melting point glass and is hard, and the lower bonding part is formed with the low-melting point glass and has sufficient bonding strength, and then the core assembly without residual stress of the bonding face and without distortion is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a core assembly for a magnetic head, and an object of the present invention is to reduce residual stress generated when a holding core and a magnetic core are bonded together with an adhesive when manufacturing the core assembly. The objective is to provide a stable core assembly.

Conventionally, a so-called tunnel type magnetic head for a floppy disk has a gap 2 formed by a pair of recording/reproducing cores 1, 1 and the recording/reproducing cores 1, 1, as shown in FIG. be done. Reference numeral 3 denotes a holding core made of a non-magnetic material such as ceramic, which is attached to the end face of one of the recording and reproducing cores 1; 4, 4 is an erasing core arranged on one side of the holding core 3; A holding member 5 made of a non-magnetic material is fixed to one end surface of the cores 4, 4.

6, 6 is an erasing core arranged on the other side of the holding core 3, and one end face of the erasing core 6.6 is made of a non-magnetic material such as ceramic, like the erasing cores 4, 4. A holding member T consisting of the above is fixed. Note that 8 and 8 are sliders made of ceramic or the like.

In the magnetic head configured as described above, each core, holding core (holding member), and slider are fixed to each other by lath bonding or the like.

In addition, recording/reproducing core 1, holding core 3, erasing cores 4, 6
and the holding members 5, 1 are bonded with resin or glass in the same manner as described above.

At this time, recording, reproducing cores 1, 1 and erasing cores 4.6
is made of iron, manganese, and zinc ferrite, and when each adhesive layer 9, 10.11 is formed of resin, the adhesive strength of the resin is weaker than that of glass, and the dimensions are not stable over time. Sex isn't enough either. Therefore, the reliability of adhesion is lacking.

Furthermore, when the resin hardens in the engineering type recording/reproducing core 1, stress is left behind, deteriorating the magnetic conversion characteristics of the core. Further, when the adhesive layers 9, 10, 11 are formed of glass, they are formed by, for example, a glass flow method or a coating method. However, in the glass flow method, it is necessary to flow molten glass into a gap of several millimeters that forms the adhesive layer, and the magnetic core must therefore be kept at high temperature for a long time. The reaction between the recording and reproducing core 1 and the glass forming the adhesive layer 9 is promoted, and a reaction layer (not shown) is formed on a part of the core 1, which not only adversely affects the magnetic properties.
Furnace equipment is large-scale and productivity is poor. The one-shot method has drawbacks such as difficulty in controlling the thickness of the adhesive layer and the need for separate coating equipment.

The present invention provides a solution to the above-mentioned drawbacks,
This will be explained in detail below with reference to FIGS. 2 and 3.

FIG. 2 is a perspective view showing the core block body, and FIG. 3 is a perspective view showing the core assembly, in which 20 is a substantially U-shaped ferrite par made of a magnetic material such as iron, manganese, or zinc ferrite; 21 is an engineering type ferrite par made of magnetic materials such as iron, manganese, and zinc ferrite, and 22 is a ceramic spar made of non-magnetic materials such as barium titanate and calcium titanate. Concave portions 22a and 22b in which a plurality of glass pars 25 and 26, which will be described later, are held on opposing end surfaces;
22C is formed. 23 is a spacer for forming a gap 24 between the ceramic spar 22 made of mica or the like and the ferrite spar 21, and 2T is a gap plate for forming a gap 28 between the 7-elite bars 20, 21. Note that 20a is a recessed portion in which a high-melting-point glass par 26 formed at the upper part of the end face of the ferrite par 20 facing the ferrite par 21 is held. 25,'2
6 is 7 elite par 20 and 21 and ceramic spar 22
The glass par 26 has a higher melting point (TI<T2) than the glass par 25 between the melting point T1 of the glass par 25 and the melting point T2 of the glass par 26.

As described above, both end faces of the single-shaped ferrite par 21 have recesses 20a in which glass pars 25 and 26 for forming adhesive layers 25' and 26' are held, respectively.

Ferrite par 2 with 22a, 22b, 22C formed
0 and the ceramic spar 22 are arranged to complete the core block body A. Note that the core block body A is held by a bonding jig (not shown) K.

The core block body held by this bonding jig is heated in a furnace. The heating temperature at this time is set higher than the melting point T2 of the glass par 26. By heating in this way, the glass par 25.25, 26.26
melts and flows into the respective interstices 24 and gaps 28. This inflow glass causes each of the 7 elite bars 20, 21 and the ceramic bar 22 to
is joined to the rel. At this time, the thickness of the bonded glass is set by the spacer 23 and the gap plate 2T.

The core block body A manufactured as described above was cut from the lines I-1 and 11-11 so as to be perpendicular to the glass bonding surface as shown in FIG. 2, and then cut as shown in FIG. 3. The core assembly B is produced by cutting the core assembly B to a predetermined thickness tl across the glass bonding surface.

At this time, the opposing surface of the magnetic head that contacts the magnetic recording medium (not shown) is the cut surface taken from the line 1--2, and therefore the upper joint between the holding core 22' and the core 21' has a high melting point. The lower joint between the holding core 22' and the engineering type recording/reproducing core 21' in FIG. 3 has a low melting point. Since it is made of glass, the bonding strength is sufficient.
There is no residual stress at the joint surfaces, thus forming a strain-free core assembly.

As mentioned above, using a plurality of glasses with different melting points means that the double-sided ferrite par 21 and the ceramic spar 22 have different coefficients of thermal expansion, which prevents stress from remaining on the joint surface after glass bonding. It's for a reason. Therefore,
By selecting the coefficient of thermal expansion of the glass, the melting point temperature of the glass, and the distance to be bonded, the residual stress can be reduced, and a stable magnetic head can be manufactured.

In addition, a plurality of recesses are formed in the holding core (holding member),
Since the adhesive glass is made to flow into the gap from each recess, the length of the glass flow can be shortened.
It also has the advantage that the heating time in the furnace is short and it can be manufactured in a short time.

As mentioned above, the core assembly of the present invention has very little residual stress at the glass bonding surface (also, during manufacturing, because the heating time is short, the bonding between the ferrite and the glass at the glass bonding surface is small). The reaction layer does not cause twisting and can provide a high quality and stable magnetic head core assembly.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional magnetic head, FIG. 2 is a perspective view of a core block body showing an embodiment of the present invention, and FIG. 3 is a perspective view of the core assembly. 20.21...Nerai) bar, 20', 21
'... Self... Core, 22... Ceramic spar, 22'... Holding core (holding member), 20a,
22a, 22b, 22C---concavity, 25.26・
...Glass bar (adhesive), A. Old core block body, B. Core assembly. 121-

Claims (1)

[Claims] (υ A magnetic head consisting of a pair of cores made of magnetic material facing each other with a gap for recording, reproducing, or erasing, and a holding member made of non-magnetic material attached to one of the cores. A core assembly for a magnetic head, characterized in that the core assembly material has four parts for holding a plurality of adhesives on the end face of the holding member on the side in contact with the one core. (2) Recording and reproduction. Alternatively, in a core assembly of a magnetic head comprising a pair of cores made of a magnetic material facing each other with a gap for erasing, and a holding member made of a non-magnetic material attached to the one core, In a method for manufacturing a core assembly of a magnetic head, the end surface of a holding member in contact with the holding member has a plurality of recesses for holding adhesive, the surface of the recess formed in the holding member being in contact with a magnetic recording medium. A core block body with a high melting point adhesive placed in the recess formed above and a low melting point adhesive placed in the recess formed below the surface in contact with the magnetic recording medium is The adhesive is heated above the melting point of the adhesive, each melted adhesive flows into the gap between the one core and the holding member, and then cooled, and the one core and the holding member are joined to form the core. 1. A method of manufacturing a core assembly for a magnetic head, comprising forming a core block body and then cutting the core block body into a predetermined shape to form a core assembly.