JPS60177412A - Production of magnetic head - Google Patents

Abstract

PURPOSE:To produce two types of heads from the same core basic material and to stabilize the characteristic of a magnetic head, by fixing the track pitch of a groove cutting blade and changing the thickness of the blade to perform cutting. CONSTITUTION:The thickness D of a groove cutting blade 22 is changed, and an edge part is cut with a blade 22' having thickness D'. The blade 22' is first moved by an indexes 1ch1' to cut the edge parts of basic materials 14 and 15. Thus a track groove 20' is produced together with a track Tch1' for the 1st channel. In the same way, the blade 22' is moved by an index 1ch2' to obtain a track Tch2' for the channel. Thus both channels Tch1' and Tch2' are obtained from the same materials 14 and 15. This eliminates the variance of characteristics and stabilizes the characteristics of a magnetic head.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method of manufacturing a magnetic head, and in particular to a method of manufacturing a magnetic head used in VTRs and the like, in which sets of magnetic heads with different track widths are used. be.

A specific example of a magnetic head used in the prior art, such as a home VTR, is shown in FIG. 1 and will be described below. In the figure, (1) is a first core block (2) made of ferrite and a second core block (3) whose opposing sides are joined with glass (5) via a non-magnetic thin film (4). A magnetic gap g with a predetermined track width d is formed on the top end surface of the head core (1). (6) is the second core block (
3) Winding windows cut and formed on the joint surface near the magnetic gap (g), (7) and (8) are both outer side surfaces of the first and second core blocks (2) and (3). The winding engagement groove (9) formed in the winding window (6) and the winding engagement groove (7)
)(8) to create the first and second core blocks (2).
)(3) is a winding wire wound with a predetermined number of turns. still,(
10) is a glass reservoir formed on the inner side surface of the second core block (3) in order to reinforce the joint between the first and second core blocks (2) and (3).

For example, in the two-way helical scan system adopted in home VTRs, the magnetic heads for the first and second channels, which have different track widths, are held by a holding jig (11) (11), as shown in Figure 2. ) through rotating drum (12)
The drum (12) is rotated to run diagonally to the magnetic tape (13) with a track width d having a magnetic gap g to the magnetic tape (1, β). video recording or magnetic tape (
13) is being played back and deleted.

A specific example of the method for manufacturing the head core (1) shown in FIG. 1 will be described with reference to steps 3131 (a) to (e) and FIG. 4. First and second core block base materials (14) (15) each having a rectangular parallelepiped shape with predetermined dimensions shown in FIG. 3(a).
(hereinafter referred to as core base material) is obtained, as shown in Fig. 3(b).
As shown in the figure, winding engagement grooves (16) (17) are formed along the longitudinal direction on the outer side surfaces of both core base materials (14) (15).
Cutting. Furthermore, cutting grooves (1B) (19), which will later become a winding window and a glass reservoir, are cut along the longitudinal direction on the inner side surface of the second core base material (15), which will become the joint surface. Next, as shown in FIG. 3(C), the first and second
A plurality of track grooves (20) (20) -- 111 are formed in the inner edge portion of the core base material (14) (15), leaving a predetermined track width l, as will be described later. This is the fourth
As shown in the figure, a plurality of first and second core base materials (14)
(15) is tilted at a predetermined angle and placed on the jig (21), and the grooving blade (22) is rotated and advanced in the direction of the dotted line arrow shown in the figure, thereby forming the eleventh second core base material. (14) Cut the edge part of (15). For each cutting process, the groove cutting blade (22) is moved to the first. By moving the second core base material (14) (15) at a predetermined pitch along the longitudinal direction, as shown in FIG.
c) Multiple track grooves (20) (20) as shown in
−・・− is formed. After the track groove processing described above, the track grooves (20) (20) - are filled with low melting point glass or the like as an adhesive to form the first and second core base materials (14).
(15) is glass-molded, and the glass-molded eleventh and second core base materials (14) and (15) are polished into a predetermined shape to mirror-finish their inner side surfaces. Thereafter, a non-magnetic thin film such as 5i02 is deposited and formed on the magnetic gear forming surface of the first and second core base materials (14) and (15), and as shown in FIG. , second core base material (
14) Butt the inner sides of (15) together and heat and weld to integrate. Furthermore, as shown in FIG. 3(e), the top end surfaces of the integrated first and second core base materials (14) and (15) are subjected to a curved polishing process.

Then, as shown by the dashed lines (m) (m)- in FIG. 1st and 2nd above
The core base material (14) (15) is sliced with a cutting blade to a predetermined thickness to obtain the helad core (1) shown in FIG. Thereafter, using the winding window (6) and winding engagement grooves (7) and (8) formed in the head core (1), the first and second core blocks (2) and (3) are turned in a predetermined direction. number of windings (
A magnetic head is obtained through the step of winding 9).

For example, the two-head system used in home VTRs requires magnetic heads for the first and second channels with different track widths, so during the manufacturing process of the magnetic heads,
In the track groove machining process shown in FIGS. 3(C) and 4, track grooves are conventionally formed by the method shown below. That is, as shown in FIG. 6, the first and second core base materials (14) are rotated and moved forward in the direction of the arrow shown in the figure by rotating a grooving blade (22) having a predetermined thickness D.
(15) Cut the edge part. That is, the groove cutting blade (22) is inserted into the first and second core base materials (14).
Proximity index Ich along the short direction of (15)
Track pitch P consisting of l and separation index Id
A plurality of track grooves (20) (20)- having a groove width are formed by cutting the track grooves (9). At this time, when the groove cutting blade (22) is moved at the index Ichl to cut the edge portions of the first and second core base materials (14) (15), a trap groove (20) is formed. At the same time, a track Tchl for the first channel having a predetermined trunk width/chi is also formed. Further, when cutting is performed by moving the groove cutting blade (22) at the index Id, a track groove (20) is formed and a dummy track Td having a predetermined track width ld is formed.
is also formed. Therefore, the above indices Ichl, Id
The groove cutting blade (
22) are cut while moving, thereby obtaining a plurality of first channel trunks Tchl and dummy tracks Td alternately on a set of first and second core base materials (14) (15). . Furthermore, in order to obtain the tracks for the second channel, the track pitch P is kept constant, so the trunk width ld of the dummy track Td, that is, the index Id is changed, and the index I ch2 is changed by changing the groove cutting blade (22). , Id", a new set of first and second core base materials (14) (15
), a plurality of second channel trunks Tch2 and dummy tracks Td' are alternately obtained on the first and second core base materials (14) and (15).

By the way, in the above-mentioned conventional track groove processing, since the track pitch and the cup pitch P are constant, the track Tchl for the first channel and the track Td for the dummy are used as a set of the first and second core base materials (14) (15). ), and also a track T ch2 for the second channel and a trunk T for the dummy.
d" to another set of first and second core base materials (14) (1
5), and the magnetic heads for the first and second channels are obtained from these separate first and second core base materials.
When using a combination of magnetic heads for the first and second channels in a two-head household V'l'H, variations in characteristics often occur, and either the magnetic head for the first or second channel One of the first and second core base materials (1
4) (15) was a defective product, and there was a problem that the numbers of magnetic heads for the first and second channels that were finally manufactured were significantly different, making it difficult to produce bearings in cents. Furthermore, there is a problem in that work for machining track grooves for the first channel and for the second channel must be performed separately, which greatly reduces work efficiency.

OBJECTS OF THE INVENTION The present invention was proposed in view of the above-mentioned problems, and it is an object of the present invention to provide a manufacturing method that can obtain a magnetic head with stable characteristics and easily improve workability.

20 Structure of the Invention The present invention involves cutting each edge portion of a first and second core base material made of a magnetic material at a predetermined track pitch using a groove cutting blade of a predetermined thickness to form a track groove leaving only the trunk width. cutting the edge portion to form a trunk groove so as to periodically provide a set of grooves arranging tracks of different widths; In this method, tracks for multiple channels each having a predetermined track width are simultaneously formed on a core base material.

E. Examples First and second examples of the manufacturing method according to the present invention are shown in FIGS. 7 and 8 and will be described below.

For example, the first one used in a two-head home VTR,
During the manufacturing process of the magnetic head for the second channel, in the trunk groove processing process of the present invention, the track pinch P in the conventional method shown in FIG. 6 is kept constant, and the thickness D of the groove cutting blade (22) is changed. do. In other words, in the first embodiment, as shown in FIG. 7, the grooving blade (22") having the changed predetermined thickness Do is rotated and moved forward in the direction of the arrow in the figure, thereby cutting the first and second core matrices. The edges of the materials (14) and (15) are cut. For each cutting process, the groove cutting blade (22") is cut into the first and second grooves.
A plurality of tracks having a groove width D° are formed by moving the core base materials (14) and (15) along the width direction at a track pitch P (constant) consisting of predetermined indexes I chl'' and I ch2'. Groove (20') (20'
) to form −・. At this time, the above index I
When the groove cutting blade (22') is moved at chi' to cut the edge portions of the first and second core base materials (14) (15), a track groove (20°) is formed and a predetermined groove is cut. A trunk Tchl° for the first channel having a track width j2chl'' is formed.Furthermore, when cutting is performed by moving the groove cutting blade (22°) at index Ich2'', a trunk groove (20') is formed. At the same time, a track Tch2' for the second channel having a predetermined track width βch2" is formed. Therefore, the groove cutting blade (22") is moved at a track pitch P consisting of the above-mentioned indexes I chl' and I ch2'. While cutting a single pair of first,
Trunks Tchl' and Tch2° for the first and second channels are simultaneously obtained on the second core base material (14) (15).

To explain the method according to the above embodiment more specifically using the numerical example shown below, for example, as shown in the conventional method described above, the trunk pitch P is 0.374 vua and the thickness D of the grooving blade (22) is 0. .160 tm, the track pitch P is kept constant and the blade thickness is changed to set D' = 0.159 M. At this track pitch P = 0.374 tm, the blade thickness D''
= 0.159 tm When cutting with a groove cutting blade (22'), the trunk width Achl' = 25 μs
, Jch2' = 31JJm, if you want to obtain tracks Tchl' and Tch2' for the first and second channels, use the above groove cutting blade with index I chi' = 0.184 tm and index I ch2' = 0.190. (22''), the predetermined track width j!chi' is achieved at a constant track pitch P = 0.374.
= 25μs, the first with Ach2' = 31cf-
, trunks Tchl', Tch2' for the second channel
is obtained.

Also, contrary to the first embodiment, the second embodiment is similar to the sixth embodiment described above.
By keeping the thickness D of the grooving blade (22) constant in the conventional method shown in the figure and changing the trunk pitch P'', the grooving blade (22) with the blade thickness shown in FIG.
The edge portions of the first and second core base materials (14) and (15) are cut by moving the core base material (22) forward in the direction of the arrow shown in the figure while rotating it. For each cutting process, the groove cutting rib (22) is cut into the first and second core base materials (14) (15).
a predetermined index Ichl” along the longitudinal direction of
A plurality of track grooves (20) having a groove width by moving at a track pitch P' consisting of Ich2°
(20) − and the index Ichl”
The predetermined track width j! chl.

A track Tchl' for the first channel is formed, and a track Tch2° for the second channel is formed having a predetermined track width Itch2' at an index Ich2°. Therefore, a single pair of first and second core base materials (1
4) Trunk T for the first and second channels in (15)
chl' and Tch2' are obtained simultaneously.

To explain this second embodiment more specifically using the numerical example shown below, for example, as shown in the above-mentioned conventional method, the track pitch P is 0.374 tm, and the groove cutting blade (22)
If the blade thickness is 0.160 fi, the blade thickness is kept constant and the trunk pitch P is changed to set P' = 0.376 m. At this track pitch P', -0,376m, blade thickness D=0.1
When cut with a 60 m groove cutting blade (22), the track width! chi'=25μs, j! ch2
'=31/jm track T for the first and second channels
If you want to obtain chl', T ch2°, index I
chi” = 0.185 Tsuru, index Ich2”
=0.191 m, the groove cutting blade (22) with blade thickness D = 0.1601 m will create a predetermined trunk width.
'=25 u III % j! ch2°=3L
Track Tch for the first and second channels with um
l'', T ch2° are obtained.

According to the present invention, the thickness of the grooving blade is kept constant and the track pinch is changed, or the trunk pitch is kept constant and the thickness of the grooving blade is changed. Since the edge portion of the second core base material is cut to form a truss groove, magnetic heads for the first and second channels are simultaneously obtained from a single pair of first and second core base materials. Therefore, a magnetic head with stable characteristics can be manufactured. Further, the number of bearings is easily determined by the number of sets of magnetic heads for the first and second channels that are finally manufactured. Furthermore, it is possible to share the work of track groove machining for the first and second channels, and work efficiency is greatly improved.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a specific example of a magnetic head, and Fig. 2 is a perspective view showing a specific example of a magnetic head.
FIG. 3 is a plan view showing a drum equipped with a magnetic head used in a home VTR using a head helical scan system.
a) to (e) are process diagrams showing part of the manufacturing process of the magnetic head, Figure 4 is a cross-sectional view to explain the track groove machining process, and Figure 5 is a diagram showing the core base material being cut into a plurality of helad cores. FIG. 6 is a partial plan view showing the core base material to explain track groove machining by the conventional method, and FIGS. 7 and 8 are the first and second steps of the present invention. It is a partial plan view which shows the core base material for demonstrating track groove processing by the manufacturing method based on an Example. (14) (15) ... 1st. second core base material, (2
2) (22') Grooving blade, (D) (D
' ) ... Thickness of the groove cutting blade, (j!chl )
(j!chi') (#ch2) (/ch2')
...Trunk width, (Tchl) (Tchl') (
Tch2) (Tch2')...Track, (P)
(P'),. track pitch. Figure 1 Figure 40 2 Figure 3

Claims (1)

[Claims] 11) Manufacturing including the step of cutting each edge portion of the first and second core base materials made of magnetic material at a predetermined track pitch with a groove cutting blade of a predetermined thickness, leaving only the track width to form a track groove. The method includes periodically providing a set of grooves arranging tracks of different widths.
A magnetic head characterized in that track grooves are formed by cutting the edge portions, and tracks for multiple channels having a predetermined trunk width are simultaneously formed in a single pair of the first and second core base materials. manufacturing method.