JPH0441452Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ring-shaped magnetic head, and more particularly to an assembly structure using a shape memory alloy.

Conventionally, a ring-shaped magnetic head consists of two combinations of a C-shaped core 1 with a winding 2 attached to a holder 3 with resin or the like, and the abutting surfaces surface-ground, as shown in Fig. 1. A gap space 4 made of titanium foil or the like is inserted at one end to form a head gap, and screws 5 are inserted into both holders 3 and tightened.
However, this structure has the disadvantage that it is necessary to apply torque evenly when tightening the screws 5, which requires a lot of man-hours.Also, the head gap may become misaligned or stepped due to temperature changes or external vibrations and shocks. This has the disadvantage of deteriorating the characteristics of the magnetic head.

Shape memory alloys are Ni-Ti alloys, copper alloys, etc. When cooled from high temperatures, the parent phase transforms to martensite at the martensitic transformation point, and conversely, when heated, the matrix transforms to martensite at a reverse transformation point higher than the martensitic transformation point. Reverse metamorphosis from phase to mother phase. When an alloy formed into a shape in the matrix state is plastically deformed in the martensitic phase and then heated above the reverse transformation point, the alloy has an irreversible shape memory effect in which the shape returns to the shape before plastic deformation.

The present invention utilizes the above-mentioned irreversible shape memory effect to prevent the head gap of a ring-shaped magnetic head from shifting, and according to the present invention, a plurality of cores are butted together across the head gap. A ring-shaped magnetic head is obtained, in which the ring-shaped magnetic head is fixed to a pair of assembled holders, and the periphery of the pair of holders is tightened and fixed with a continuous frame-shaped shape memory alloy.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view showing an embodiment of the magnetic head according to the present invention as an intermediate assembly, similar to FIG.

The same parts as in FIG. 1 are given the same reference numerals. The holder 3 has a leg portion 31 (hereinafter referred to as the front leg portion 31 and the opposite leg portion is referred to as the rear leg portion 32) on the side where the head cavity is provided, which is narrower than the closed end portion 33. Both front and rear end portions of both side surfaces of the end portion 33 and both side surfaces of the rear leg portion 32 are cut out corresponding to the plate width and thickness dimensions of the shape memory alloy 6. The shape memory alloy 6 is a frame-shaped body made of a band-shaped plate having a reverse transformation point near 80°C, for example, and is butted against the front leg 31 side and the rear leg 32 of the closed end 33 of the holder 3. The mating direction of the holder 3 is formed in the martensitic state so that they can be fitted together as shown by the solid line in the figure with the required tightening strength in the direction shown in FIG. It is plastically deformed (elongated) only in the parallel direction.

The intermediate assembly is assembled by gluing the C-shaped core 1 with the winding 2 onto the holder 3 and grinding the surface, and then attaching two pieces of this combination to the rear end of the core 1 and the rear leg end of the holder 3. An instant adhesive is applied to the core 1, a gap spacer 4 made of titanium foil, mica, etc. is inserted into the front end of the core 1, and the cores are butted against each other to form a temporary assembly. After fitting the shape memory alloy 6 into both holders 3 as shown by the chain lines in FIG. The memory alloy returns to the square frame shape before plastic deformation as shown by the solid line, and the holders 3 are tightened and fixed to complete the process. The magnetic head is completed by housing an intermediate assembly in a shield case, injecting resin into the case, and polishing the outward facing surface of the head gap and its vicinity to round the surface.

FIG. 3 is a perspective view showing an unfinished state of an intermediate assembly according to another embodiment of the present invention. This is an example in which the shape of the shape memory alloy 6 is changed during plastic working. That is, in order to fit the holders 3 together with the required tightening strength in the same way as explained in FIG. A shape memory alloy 6 that is plastically worked into a circumscribed circle shape that can be placed on the stepped notch of the holder 3 is used. As shown by solid lines in FIG. 3, shape memory alloy 6 is inserted into the front and rear parts of the temporarily assembled holder 3,
The temperature of the holder is increased to a temperature higher than the reverse transformation point and returned to the frame-shaped body (memory shape, indicated by the chain line), thereby tightening and fixing the two holders. Once a shape memory alloy has returned to its memorized shape, its shape does not change at all even if the temperature changes.

As described above, according to the present invention, there is no need to tighten screws and only heating is required, which reduces assembly man-hours, and provides strength to tighten the holders even in the face of temperature changes, external vibrations, and shocks. It is possible to provide a highly reliable magnetic head in which the characteristics can be maintained without deterioration in the magnetic field strength and, therefore, without any change in the head gap.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of an intermediate assembly of a conventional magnetic head, FIG. 2 is a perspective view showing an embodiment of the present invention as an intermediate assembly, and FIG. 3 is another embodiment of the present invention. FIG. 3 is a perspective view showing an example in a state before finishing the intermediate assembly. In the figure, 1... C-shaped core, 2... Winding wire,
3... Holder, 31... Front leg, 32... Rear leg, 33... Closed end, 4... Gap spacer,
5...screw, 6...shape memory alloy.

Claims (1)

[Scope of utility model registration request] A ring type, characterized in that a plurality of cores are butted against each other with a head gap and fixed to a pair of assembly holders, and the pair of holders are tightly secured around the pair of holders with an unbroken frame-shaped shape memory alloy. magnetic head.