JPH0262704A - Method for grinding curved face of core block - Google Patents

Abstract

PURPOSE:To attain the grinding to a prescribed curved face accurately at all times by butting a joined side face at both ends of a projected core block onto a reference face of a working jig, fixing the side face tentatively and applying curved face grinding to a tip face of the core block while the working jig is rocked around one point on a prolonged line of the reference face. CONSTITUTION:Joined side faces 26, 26 at both ends of a projected core block 12 are pressed onto reference faces 21, 21 of a loading arm 22 and the core block 12 and the loading arm 22 are bonded tentatively in this state. After the tentative bonding, the working jig 23 is moved to bring the tip face of the core blocks 11, 12 into contact onto a grinder 24, the working jig 23 is rocked around a rotary shaft 25 and moved laterally to apply curved face grinding to the tip face of the core blocks 11, 12. When the grinding is finished, an adhesives is molten to remove the working jig 23, the core blocks 11, 12 are sliced to form a core chip. Thus, the tip face of a couple of core blocks is ground accurately onto the curved face taking the magnetic gap as its apex.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a curved surface polishing method for accurately polishing the tip end surface of a core block into a curved surface having a magnetic gap as its apex.

[Conventional technology]

A magnetic head used in a VTR device or the like has a structure shown in FIGS. 5 and 6, for example.
1) is a core chip made of a ferromagnetic material such as single-crystal ferrite, in which a pair of cores (2) and (3) are joined together with glass (4) and (6). The tip surface of the core chip (1) is formed into a curved surface, and the top end portion has a core (2) (
A magnetic gap (g) is formed by interposing a non-magnetic thin film (5) such as Sing, which serves as a gap spacer, between the bonding surfaces of 3). In addition, the winding locking grooves (7) and (8) formed on the outer narrow side surfaces of the cores (2) and (3), and the winding insertion hole (9) provided by the integral joining of the core (3). Using
A coil is formed by winding a predetermined number of wire rods (10) around the cores (2) and (3).

A plurality of core chips (1) constituting the magnetic head are manufactured in batches from a pair of core blocks (11) (12). That is, as shown in FIG. 7, a V-groove (13) is formed on the inner side surface of one core block (11), and a winding locking groove (14) is formed on the outer side surface. There are also winding locking grooves (15) on the outer and inner side surfaces of the other core block (12).
Both core blocks (1
1) At the inner edge of (12), track (T) (T)
Multiple track grooves leaving... (17) (17)
... is formed at a fixed pitch. And both core blocks (
11) Track groove of (12) (17) (17)
...and ■Glass (18) in the groove (13) (18)
... (19) is molded, and then the bonding surfaces of both core blocks (11) and (12) are polished to a mirror finish, and non-conforming materials such as Si islands, which will serve as gap spacers, are formed on the entire bonding surface of the core block (11). A magnetic material f[1 (20) is deposited by sputtering. After this, core block (11) (
12) are butted together and integrated by heating and welding. After integrally bonding, the tip surfaces of the core blocks (11) (12) are polished into curved surfaces, and finally the core blocks (11) (12) are separated along a direction inclined by an azimuth angle with respect to the width direction of the core blocks (11) (12). (11) A plurality of core chips (1) are manufactured by slicing (12) into predetermined thicknesses.

The curved surface polishing of the tip surfaces of the core blocks (11) and (12) is performed using a processing jig (23) integrally formed with a mounting arm (22) having a reference surface (21), as shown in FIG. Core block (11) integrally connected to (21) (
12), and then move the processing jig (23) and grind the end surfaces of the core blocks (11) and (12) with the grindstone (
24), and the processing jig (23) is brought into contact with the rotating shaft (25).
The tip surfaces of the core blocks (11) and (12) are polished by swinging the core blocks at the center and moving them laterally.

The rotation axis (25) of the processing jig (23) is set on an extension line of the magnetic gap between the core blocks (11) and (12) attached to the reference surface (21).

[Problem to be solved by the invention]

In the above polishing method, a processing jig (23
) Core block (11) affixed to the reference surface (21) of
Due to the variation in the thickness of the magnetic gap (2), the dimension (2,) from the reference surface (21) to the magnetic gap (g) changes, and the gap line may shift from the center of rotation of the processing jig (23). If polishing is performed with such misalignment, the curved surfaces of the core blocks (11) and (12) will not be formed with the magnetic gap (g) as the apex, and the specified magnetic properties will not be obtained. There was a problem.

The present invention aims to provide a method for polishing a curved surface that is not affected by variations in the thickness of the core block and can always accurately form a predetermined curved surface.

[Means to solve the problem]

This invention involves forming one core block longer than the other core block, joining and integrating both core blocks so that both ends of the long core block protrude from both ends of the other core block, and then The joint sides of both ends of the protruding core block are temporarily fixed against the reference surface of the processing jig, and while the processing jig is swung around a point on the extension line of the reference surface, the tip surface of the core block is curved. It is designed to be polished.

[Effect]

With the above method, the joint surfaces of the pair of core blocks, that is, the position where the magnetic gap is formed, always coincides with the reference plane of the processing jig. Moreover, since the processing jig is oscillated around a point on the extension line of the reference plane to polish the tip surface of the core block into a curved surface, the tip surface of the core block becomes an ideal curved surface with the magnetic gap at the top.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. Incidentally, the same reference numerals are given to the same constituent members as in the prior art, and the explanation thereof will be omitted.

In this invention, first, one of a pair of core blocks (11) and (12) forming a core chip is formed long. For example, as shown in Figure 3, winding locking grooves (
15) and a core block (12) forming a groove (16).
) is formed longer than the other core block (11).
. Then, after each core block (11) (12) is subjected to predetermined processing, both core blocks (11) (
12) are joined and integrated so that both ends of the long core block (12) protrude from both sides of the other core block (11).

On the other hand, as shown in FIGS. 1 and 2, the processing jig (23) has a mounting arm (22) formed in a gate shape, with the lower surfaces of both ends serving as reference surfaces (21). The portal-shaped mounting arm (22) has a recess (2) large enough to completely accommodate the short core block (11) even if the dimensions vary.
2a) is formed. In addition, this processing jig (23) has a rotating shaft (25) installed on the extension line of the reference plane (21),
It is configured to swing around the rotating shaft (25).

When polishing the tip surfaces of the core blocks (11) (12), the core blocks (11) (12) and the processing jig (23) are cleaned, and the short core blocks (11) are placed in the processing jig (23). The core block (12) is housed in the mounting arm (22) and protrudes from the elongated core block (12).
Attach the joint sides (26) (26) at both ends of the arm (2).
2), and in this state, the core block (12) and the mounting arm (22) are temporarily fixed, for example, temporarily bonded. After temporary bonding, move the processing jig (23) so that the tip surfaces of the core blocks (11) (12) come into contact with the grindstone (24), and rotate the processing jig (23) around the rotation axis (25). Swing and move laterally,
The tip surfaces of the core blocks (11) and (12) are polished to a curved surface.

When polishing is complete, melt the adhesive and attach the core block (1
1) Remove (12) from the processing jig (23).

When the polishing is completed, the core block (
11) Slice (12) to form core chips.

〔Effect of the invention〕

According to this invention, even if there are variations in the thickness of the core blocks, the magnetic gap between the pair of core blocks attached to the processing jig always matches the reference surface of the processing jig, and the processing jig is Since the core blocks swing around a point on the extended line, the tip surfaces of the pair of core blocks are precisely polished into curved surfaces with the magnetic gap at the top. Therefore, the quality of core chips obtained from core blocks polished by the method of this invention is improved.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of the method of the present invention, Fig. 2 is a longitudinal sectional front view of a processing jig, Fig. 3 is a perspective view showing the state of connection of the core block used in the invention, and Fig. 4. FIG. 2 is a perspective view showing the core block after polishing. Fig. 5 is a perspective view showing an example of a magnetic head, Fig. 6 is a partially cutaway front view of the magnetic head, Fig. 7 is a perspective view showing the manufacturing process of a core chip used in the magnetic head, and Fig. 8 is a conventional FIG. 9 is a side view showing the conventional polishing method. (11) (12)-core block, (g)...
Magnetic gap, (21)--Reference plane, (22)--Equipped arm, (23)--Processing jig, (24)
-Whetstone, (25)--rotating shaft, (26)-
・Joining sides of both ends of core block. Patent applicant Kansai NEC Co., Ltd. 7th generation
Shogo Ebara 1$1
Figure-・1-・Concave 1? Fig. 2 1γ /2 Fig. Fig. Fig. Fig. 2

Claims (1)

[Claims] (1) Form one core block longer than the other core block, join and integrate both core blocks so that both ends of the long core block protrude from both ends of the other core block, and then The joined sides of both ends of the core block are temporarily fixed against the reference surface of the processing jig, and while the processing jig is swung around a point on the extension line of the reference surface, the tip surface of the core block is polished into a curved surface. A method for polishing a curved surface of a core block.