JPH03229406A - Manufacture of deflection yoke core - Google Patents

Abstract

PURPOSE:To avoid the variation of density over a molded unit and maintain the circularity of a core to facilitate manufacture of the deflection yoke core having high deflection characteristics by a method wherein protrusions are provided on the molded unit in the rear parts of its clipping trenches and the molded unit is baked. CONSTITUTION:A molded unit 10 for a deflection yoke core 1 is formed by the compression molding of ferrite powder. The molded unit 10 is formed with a mold in which protrusions corresponding to separation trenches 2 and clipping trenches 5 and 6 and recesses corresponding to protrusions 11 and 12 are provided beforehand. As the molded unit 10 formed as described above has an approximately uniform thickness t0 over the whole unit, a pressure for molding is applied to the whole unit almost uniformly, so that a density can approximately be uniform over the whole unit. Therefore, if the molded unit is baked in that state or in the state after the protrusions 11 and 12 are removed, deformation caused by the baking can be avoided and the core 1 having a high circularity can be obtained. The protrusions 11 and 12 may be removed before or after the baking.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a method for manufacturing a core for a deflection yoke used in cathode ray tubes such as televisions, particularly for a morning glory-shaped deflection yoke that is divided along dividing grooves. The present invention relates to a method for manufacturing a core.

[Conventional technology]

Figure 5 is a partially cutaway front view showing the core for the deflection yoke;
The figure is a bottom view, FIG. 7 is a sectional view taken along line A-A in FIG. 5, FIG. 8 is a plan view of the clip, and FIG. 9 is a front view of the clip.
In the figure, (1) is a morning glory-shaped deflection yoke core made of a sintered body of ferrite powder, and (2) is a core formed on the outer and inner surfaces of the core (1) facing each other to divide the core (1). divided groove, (3).

(4) is a divided core divided by a dividing groove (2), (5),
(6) represents each split core (3) and (4) on both sides of the split groove (2).
), and (7) is a clip.

The above deflection yoke core (1) is divided into two divided cores (3) and (4) by the firing machine dividing groove (2), and after winding, they are combined into one core, and the opposing clip grooves (5 ).

(6) is sandwiched between clips (7) and used as an integrated unit.

The conventional manufacturing method for such a deflection yoke core (1) is to first use a mold in which convex portions corresponding to the dividing grooves (2) and clip grooves (5) and (6) are formed in advance.

Pressure molding ferrite powder to form a molded body having one dividing groove (2) and clip grooves (5) and (6),
The core (1) for a deflection yoke is obtained by firing the molded body at a high temperature of several hundred degrees. After firing, a chisel with a wedge-shaped tip is applied to the dividing groove (2), and an impact is applied from above with a hammer to divide it into two parts.

[Problem to be solved by the invention]

However, in such a conventional manufacturing method of a core for a deflection yoke, the wall thickness t in the clip groove forming portion (8) forming the bottom surface of the clip groove (5) is thinner than the wall thickness t0 in other parts. Because it is a thin-walled part, the density of the thin-walled part of the molded product formed by press molding is high,
As a result, a density difference with the peripheral portion is formed, and the density balance of the entire core (1) is disrupted. If the density of the molded body is unbalanced in the circumferential direction, deformation occurs during firing, which deteriorates the roundness of the core (1) after firing, which affects the deflection characteristics of the CRT. This invention is intended to solve the above problems, and even when forming a molded body with clip grooves, there is no difference in density in the molded body, so that the true shape of the core after firing is It is an object of the present invention to provide a method for manufacturing a core for a deflection yoke that can maintain high circularity and improve deflection characteristics.

[Means to solve the problem]

The method for manufacturing a core for a deflection yoke according to the present invention involves forming a molded body having clip grooves on both sides of a dividing groove by press-molding ferrite powder, and firing this molded body to produce a morning glory-shaped core for a deflection yoke. In this manufacturing method, a molded body having a protrusion is formed on the back side of the clip groove, and the protrusion is removed after molding or firing.

[For production]

In the method for manufacturing a core for a deflection yoke of the present invention, when a molded body for a deflection yoke core is formed by pressure molding of ferrite powder, a protrusion is formed on the back surface of the clip groove so that the entire wall has a substantially uniform thickness. form a molded body.

The molded body formed in this way has a nearly uniform wall thickness throughout, so the pressure during molding is applied almost uniformly to the entire body, eliminating local density differences and making the overall density almost uniform. It has become. This makes the density distribution uniform in the circumferential direction, so when the molded body is fired, there is no deformation during firing and a core with high roundness is obtained. The protrusion formed on the back surface of the clip groove is removed after molding or firing.

The deflection yoke core manufactured in this way is divided along one dividing groove, the divided cores are wound with wire, and then combined into one. Clips are inserted into the clip grooves formed on both sides of the dividing groove, and the core is divided into two parts. Use by sandwiching the core and integrating.

In this case, since the core has a high roundness, excellent deflection characteristics can be obtained when used as a CRT.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

FIG. 1 is a partially cutaway front view showing a molded body in an embodiment of the present invention, FIG. 2 is a sectional view taken along line BB, and FIG. 3 is a sectional view taken along line CC in FIG. The same reference numerals as in FIGS. 5 to 9 indicate the same or corresponding parts. (10) is a molded body, which is formed in almost the same shape as the core (1) in FIGS. 5 to 7, and has dividing grooves (2 ) split cores (3) on both sides of
Clip grooves (5) and (6) are formed in (4).

(11) and (12) are protrusions formed on the back surfaces of the clip grooves (5) and (6), and the clip groove forming portions (8
) has the same thickness as the other parts.

In the method for manufacturing the deflection yoke core (1), first, a molded body (10) is formed by pressure molding of ferrite powder. At this time, the dividing groove (2) and the clip groove (5).

Convex portions corresponding to (6), and protruding portions (11), (
A molded body (10) is formed using a mold in which a concave portion corresponding to 12) is previously formed.

The molded body (10) thus formed has a substantially uniform wall thickness t throughout, so that the pressure during molding is applied substantially uniformly to the entire body, and the density of the whole is substantially uniform.

Therefore, in this state or with the protrusion (11),
When the molded body (10) is fired with (12) removed, no deformation occurs during firing and a core (1) with high roundness is obtained. The protrusions (11) and (12) may be removed before or after the firing, thereby making the fifth
A core (1) shown in the figures through FIG. 7 is obtained.

The deflection yoke core (1) manufactured as described above is divided along the dividing groove (2) in the same manner as the conventional one, and the divided cores (3) and (4) are wound. Clip grooves (5) combined into one and formed on both sides of the dividing groove (2)
The tip of the clip (7) is inserted into (6), and the split cores (3) and (4) are sandwiched between the clip (7) and integrated for use.

In this case, since the core (1) has a high roundness, excellent deflection characteristics can be obtained when used as a CRT.

FIG. 4 is B- of FIG. 1 showing a molded body in another example.
It is a sectional view of B. In this embodiment, the protrusion (11), (
12) is divided into thin pieces, making it easy to remove in the subsequent process.

In addition, in the above description, the protrusions (11) and (12)
The shape of is not limited to that shown in the drawings and can be changed.

〔Effect of the invention〕

As described above, according to the present invention, a molded body having a protrusion on the back side of the clip groove is formed and fired.
Even when a molded body with clip grooves is formed, there is no density difference in the molded body, and therefore the roundness of the core after firing is maintained high, making it possible to manufacture a core for a deflection yoke with high deflection characteristics. can.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing the molded body of the example, Fig. 2 is a sectional view taken along line B-B, and Fig. 3 is a sectional view taken along line C-C in Fig. 1.
FIG. 4 is a sectional view taken along line BB in FIG. 1 showing a molded body of another embodiment, and FIG. 5 is a partially cutaway front view showing a core for a deflection yoke.
Fig. 6 is a bottom view, Fig. 7 is a sectional view taken along line A-A in Fig. 5,
FIG. 8 is a plan view of the clip, and FIG. 9 is a front view thereof. In each figure, the same reference numerals indicate the same or corresponding parts, (1)
is the core for the deflection yoke, (2) is the dividing groove, (3), (4
) is a split core, (5), (6) are clip grooves, (10
) is a molded body, and (11) and (12) are protrusions.

Claims (1)

[Claims] (1) In a method of manufacturing a morning glory-shaped deflection yoke core by forming a molded body having clip grooves on both sides of a dividing groove by press-molding ferrite powder and firing this molded body, the back side of the clip groove 1. A method for manufacturing a core for a deflection yoke, the method comprising: forming a molded body having a protrusion, and removing the protrusion after molding or firing.