JPH06143323A - Continuous injection molding method for ferrite sheet - Google Patents

Abstract

PURPOSE:To obtain various sorts having different lengths by an injection molding method by injecting ferrite powder mixture resin in a mold having a side opening, feeding cooled and solidified sheetlike molded form out of the mold except its end side, then injecting the resin in a molding space, and integrating with a molded form immediately before repeatedly. CONSTITUTION:A side opening 3 is formed at a mold 1 having a molding space 2 for molding a sheetlike molded form. At the time of first injection molding, the space 2 is closed with a top 4, and ferrite powder mixture resin is injection molded. After the resin is cooled and cured, the top 4 is removed, a molded form S1 in the space 2 is fed at a specific pitch (a) from the opening 3 to an external space, and stopped in a state that an end side of the form S1 remains in the opening 3. Then, ferrite powder mixture resin is injected in the space 2 closed by the end side of the form S1, cured, and integrated with the form S1 immediately before simultaneously upon forming of next molded form S2. Then, this procedure is repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for correcting a magnetic field of a deflection yoke mounted on a cathode ray tube of a television receiver, a CRT display or the like, or a radio wave absorber for preventing radio wave leakage from a microwave oven or other electronic equipment. The present invention relates to a method for producing a ferrite sheet used as, more specifically, a continuous injection molding method for a ferrite sheet.

[0002]

2. Description of the Related Art A magnetic field is corrected by attaching a chip-shaped ferrite sheet piece made of synthetic resin or rubber mixed with ferrite powder to the inner surface of a deflection yoke mounted on a cathode ray tube of a television receiver or a CRT display. Techniques or techniques of using a radio wave absorber to prevent radio wave leakage from a microwave oven or other electronic equipment are known.

Both the chip-shaped ferrite sheet piece used for magnetic field correction and the radio wave absorber used for the purpose of preventing radio wave leakage from electronic equipment are molded from a resin containing ferrite powder. Both are sheet-like. For example, as shown in FIG. 11A, a chip-shaped ferrite sheet piece used for magnetic field correction of the deflection yoke has a predetermined size in which a double-sided adhesive sheet T including an adhesive layer B and a release paper R is laminated on the back surface, as shown in FIG. The large-sized ferrite sheet body F is provided with breaking grooves V vertically and horizontally, and a large number of chip-shaped ferrite sheet pieces Ft are supplied in parallel. On the other hand, a radio wave absorber used for the purpose of preventing radio wave leakage is, as shown in FIG. 11B, a strip for breaking in a longitudinal direction on a large-sized ferrite sheet body F having a double-sided adhesive sheet T laminated on the back surface. A plurality of grooves V are arranged side by side in the width direction, and a large number of rod-shaped electromagnetic wave absorbers Fr are supplied in a state of being arranged side by side. Although the illustrated ones are laminated with the double-sided adhesive sheets T, there is also a type in which the double-sided adhesive sheets are not laminated depending on the usage mode.

The double-sided adhesive sheet mentioned here refers to the laminate of the pressure-sensitive adhesive layer B and the release paper R as described above, and the surface where the pressure-sensitive adhesive layer is exposed is attached to the lower surface of the ferrite sheet. After that, the release paper R is peeled off to expose the adhesive layer, so that the other surface can be attached to an object such as a winding of the deflection yoke. As a result, both sides of the adhesive layer B are adhesive surfaces. Refers to what is used as.

In the large-sized sheet body, a double-sided adhesive sheet is laminated on the back surface of a molded ferrite sheet, and then a Thomson blade is cut into this laminated body to form a breaking groove V. It is made by. by the way,
Known calendering methods, extrusion molding methods, and injection molding methods are known as molding methods for ferrite sheets. Although the calendar molding method and extrusion molding method are suitable for mass production,
Not suitable for high-mix low-volume production. In addition, there is a problem that it is difficult to increase the molding accuracy by extrusion molding.
On the other hand, although the injection molding method has the advantages of excellent molding accuracy and suitability for small-quantity production, on the other hand, there are problems peculiar to the injection molding method. That is, in the injection molding method, the size of the obtained molded product is necessarily regulated by the size of the molding space inside the molding die. Need to be replaced with a dedicated mold each time, which causes a problem of high mold cost. Also, in order to obtain a long molded product, it is necessary to use a large molding die, but the size of the mold is naturally limited, and as a result, the injection molding method is used for a long molded product. There is a problem that is not suitable for getting. The present invention has been made in view of the present situation, and an object thereof is to solve the above-mentioned problems that are inevitable in injection molding. That is, it is an object of the present invention to provide a continuous injection molding method of a ferrite sheet, which is an injection molding method and is capable of handling a wide variety of products having different length dimensions by one unit and capable of manufacturing a long ferrite sheet.

In order to solve such a problem, the present invention adopts the following configuration. That is, a molding space for molding a sheet-shaped molded product is formed, and a mold is used in which a side opening that opens toward the external space is formed at a side end in the longitudinal direction or the width direction of the molding space. The ferrite powder-containing resin is injected into the mold, and then the sheet-shaped molded product, which has been cooled and hardened, is left intermittently outside the mold through the side opening with the terminal side left in the molding space or the side opening. The latest sheet-shaped molded product that is molded by being injected into the molding space by injecting the ferrite powder-containing resin into the molding space that has been closed by the end of the sheet-shaped molded product after being sent out for a predetermined pitch, It was decided to make a continuous ferrite sheet by integrating it with the end portion of the sheet-shaped molded product formed immediately before, and thereafter repeating the above-mentioned treatment steps.

Since the side opening remains open during the first injection, it is necessary to provide means for closing the side opening.

It is also possible to place the mold horizontally and wind the sheet-shaped molded product fed out from the mold horizontally, but from the viewpoint of preventing the slack of the sheet-shaped molded product,
It is preferable that the side opening is formed at an upper position of the mold, and the sheet-shaped molded product sequentially fed from the mold is wound up.

Further, by forming the side wall shape on the side opposite to the side in which the side opening is opened in the molding space into a sawtooth shape, a molded product manufactured by the latest injection and a molded product manufactured by the last injection. Increase the contact area with objects,
It is preferable to complete the bonding and integration of both moldings.

When polyvinyl chloride, acrylic synthetic resin or rubber resin is used as the binder of the ferrite powder-containing resin, the bonding between the molded product produced immediately before and the latest molded product becomes more complete.

The molding die may be an integral type which does not open the mold, but from the viewpoint of facilitating the taking out of the molded product, a mold-openable mold composed of a fixed mold and a movable mold is used. Is preferred.

[0012]

In the continuous injection molding method for such a ferrite sheet, the terminal end side of the molded product produced immediately before is left in the mold to be used as a means for closing the side opening of the mold, By intermittently feeding out the produced sheet-shaped molded product by a predetermined pitch, the latest molded product produced in the mold is integrated with the end of the molded product immediately before remaining in the mold to form a sheet-shaped product. This is for molding a continuous body of objects.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to illustrated embodiments. FIG. 1 shows a main part of an apparatus for carrying out the manufacturing method of the present invention. In the figure, 1 is a molding die (hereinafter, simply referred to as die 1
In the drawing, N is an injection nozzle, and S in the drawing is a sheet-shaped molded product sent out from the mold 1. The injection nozzle N may be provided at any of the side surface, the upper surface, and the lower surface of the mold 1. The injection nozzle N is omitted in the drawings used in the following description.

2A and 2B are perspective views of the mold 1, wherein FIG. 2A shows a mold clamped state and FIG. 2B shows a mold opened state.
The mold 1 is composed of a movable mold 1a and a fixed mold 1b, and has a molding space 2 for molding a sheet-shaped molded product therein, and the molding space 2 has a longitudinal side end toward the external space. An open side opening 3 is formed. In the illustrated example, the side opening 3 is provided on one side in the longitudinal direction of the molding space 2,
It is also possible to provide it on one side in the width direction. FIG. 3A is a horizontal sectional view, and FIG. 3B is a vertical sectional view. Side opening 3
Has a width and a height that match the width W and the height H of the molding space 2 so that the molded product in the molding space 2 can be taken out through the side opening 3. As the mold 1, as shown in FIG. 4, it is also possible to use an integrated mold 1A that does not open the mold.

FIG. 5 is a process drawing of the continuous injection molding method of the ferrite sheet of the present invention using the mold 1.
Since the side opening 3 is open during the first injection, it is necessary to close it. In this embodiment, a method of forming the molding space 2 as a closed space by screwing the top 4 is adopted (see FIG. 5A). Other means may be used as means for closing the side opening 3.

Next, the ferrite powder-containing resin is injected into the molding space 2 which has become a closed space (see FIG. 5B).
A known resin can be used as the ferrite powder-containing resin,
For example, a known material in which soft ferrite is dispersed and contained in synthetic resin or rubber is used. As the soft ferrite, for example, manganese zinc ferrite, nickel zinc ferrite or magnesium ferrite can be used, and as the synthetic resin, for example, polyvinyl chloride, polyamide, chlorinated polyethylene, polypropylene, polymethylpentene, polyphenylene sulfide, etc. are used. As the rubber, acrylonitrile butadiene rubber, olefin rubber, chloroprene rubber, chlorosulphonated polyethylene rubber, etc. are used. Also, when the final use purpose of the molded product to be manufactured is a radio wave absorber,
Other magnetic powders can be used in place of the ferrite powder, and for example, magnetic materials such as carbon, magnetite, and carbonyl iron can also be used.

When the ferrite powder-containing resin in the molding space 2 has cooled and hardened, the top 4 is removed (see FIG. 5C). Next, the molded product S1 in the molding space 2 is attached to the side opening 3
A predetermined pitch a is sent toward the external space through, and the molded product S1 is stopped with the terminal end side left in the side opening 3 (see FIG. 5D).

Subsequently, the ferrite powder-containing resin is injected into the molding space 2 closed by the end side of the molded product S1 (see FIG. 5 (e)), and the ferrite powder-containing resin is cured in the molding space 2. At the same time as forming the next molded product S2, the molded product S2 and the molded product S1 molded immediately before are combined and integrated (see FIG. 5F). This bonding and integration is performed by bringing the melted ferrite powder-containing resin into contact with the end side of the molded product S1 so that the end side of the molded product S1 is partially melted or softened and fused. Especially as synthetic resin binder, polyvinyl chloride,
When an acrylic synthetic resin or a rubber resin is used, this fusion is performed more completely, and there is no characteristic change at the joint portion, and it is relatively necessary to wind up the sheet-shaped molded product fed from the mold 1. It is possible to obtain a sheet-shaped molded product that does not separate even when a strong tension is applied.

Next, an integrated product of the molded product S1 and the molded product S2 is sent out at a predetermined pitch, and the molding space 2 is again set in the mold 1.
Are formed (see FIG. 5G). The subsequent procedure is a repetition of the procedure described above. In this way, the terminal end side of the molded product S1 produced immediately before is used as a means for closing the side opening 3 of the mold 1, and the ferrite powder-containing resin is injected into the molding space 2 closed by this molded product S1. As a result, the next molded product S2 continuous with the end side of the molded product S1 is produced. Then, the sheet-shaped molded product S thus produced is intermittently sent out at a predetermined pitch.
The delivery of the sheet-shaped molded product S is performed by winding the sheet-shaped molded product S. When the sheet-shaped molded product S is delivered, it is preferable to open the mold 1 to facilitate the separation of the molded product from the mold. However, it is also possible to send out the molded product by using an integrated mold without opening the mold.

In the above description, the mold 1 is installed horizontally, and the case where the sheet-shaped molded product S is wound in the horizontal direction has been described. However, as shown in FIG. 6, the mold 1 is installed vertically. It is also possible to arrange the side opening 3 at the upper position of the mold 1 and wind up the sheet-shaped molded product S sequentially fed from the mold.

7 to 10 show another example of the mold 1. FIG. 7 shows the side wall shape of the side opposite to the side opening 3 in the molding space 2 formed into a sawtooth shape, the molded article manufactured by the injection operation immediately before and the molded article manufactured by the latest injection operation. This is a case where the mutual contact area is increased to strengthen the bond between the two. The side wall shape may be as shown in FIG. Further, as shown in FIGS. 9A and 9B, a side wall shape having a shape bulging toward the molding space 2 may be adopted. In this case, the mutual coupling of the molded products becomes extremely strong, and the molded products are not separated even when a strong tension is applied to the sheet-shaped molded product S delivered from the mold 1. When such a bulged side wall shape is adopted, it is expected that it will be difficult to remove the molded product from the molding space 2. In such a case, a mold that can be opened with a movable mold and a fixed mold is used as the mold,
It is considered that after the mold is opened, the molded product is pushed up by a protruding pin (not shown) arranged on the bottom surface of the fixed mold, and the molded product is removed from the molding space 2.

As shown in FIG. 10, a ridge 5 elongated in the feeding direction of the molded article is provided on the inner surface of the mold,
This is an example in which the breaking groove is formed on the molded product simultaneously with the molding.

[0023]

According to the continuous injection molding method of a ferrite sheet of the present invention, since a molded product can be continuously manufactured even though it is an injection molding method, a long ferrite sheet can be manufactured. By cutting the ferrite sheet of (1) to a predetermined size by post-processing, it is possible to obtain various types of ferrite sheets having different lengths. Therefore, it becomes possible to manufacture ferrite sheets of various lengths using a common mold without increasing costs. Moreover, since the present invention is injection molding, the dimensional accuracy is excellent.

[Brief description of drawings]

FIG. 1 is a simplified explanatory view showing a main part of an apparatus for carrying out a manufacturing method of the present invention.

FIG. 2 is a perspective view of a mold, in which (a) is a mold clamped state and (b) is a mold opened state.

FIG. 3 is a cross-sectional view of the mold, in which (a) is a cross-sectional view,
(B) is a vertical sectional view

FIG. 4 is a perspective view showing an integrated mold that does not open the mold.

5 (a) to (g) are process diagrams in which a continuous injection molding method of a ferrite sheet of the present invention is carried out.

FIG. 6 is an explanatory view of an embodiment in which the mold is placed vertically and the sheet-shaped molded product is wound upward.

FIG. 7 is a cross-sectional view showing another embodiment of the mold.

FIG. 8 is a cross-sectional view showing another embodiment of the mold.

9 (a) and 9 (b) are cross-sectional views showing another embodiment of the mold.

FIG. 10 is a cross-sectional view showing another embodiment of the mold,
(A) is a horizontal sectional view, (b) is a vertical sectional view

FIG. 11 is a perspective view showing an external shape of a ferrite sheet, (a) shows a magnetic field correcting ferrite sheet of a deflection yoke, and (b) shows a ferrite sheet in which radio wave absorbers are connected.

[Explanation of symbols]

 F Ferrite sheet body Ft Chip-shaped ferrite sheet piece Fr Rod-shaped electromagnetic wave absorber B Adhesive layer R Release paper T Double-sided adhesive sheet V Break groove N Injection nozzle S Sheet-like molded product S1 Molded product S2 Molded product 1 Mold 1a Movable Mold 1b Fixed mold 1A Integrated mold 2 Molding space 3 Side opening 4 Frame 5 Raised strip

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location // H01J 9/236 7161-5E B29K 105: 16 B29L 31:34 4F

Claims (6)

[Claims] 1. A mold in which a molding space for molding a sheet-shaped molded product is formed, and a side opening opening toward the external space is formed at a side end in the longitudinal direction or the width direction of the molding space. , Injecting a ferrite powder-containing resin into the mold, and then cooling and hardening the sheet-shaped molded product to the outside of the mold through the side opening while leaving the terminal side thereof in the molding space or the side opening. The latest sheet-shaped molding in which the ferrite powder-containing resin is injected into the molding space by intermittently sending it out for a predetermined pitch and then injecting the resin containing ferrite powder into the molding space that is closed by the end of the sheet-shaped molded product. Continuous injection molding method of a ferrite sheet, in which the product is integrated with the terminal end of the sheet-shaped molded product formed immediately before, and thereafter, the above-mentioned processing steps are repeated to produce a continuous ferrite sheet. . 2. The continuous injection molding method for a ferrite sheet according to claim 1, wherein means for closing the side opening of the mold is provided, and the side opening is closed when the first injection is performed. 3. The continuous injection molding method for a ferrite sheet according to claim 1, wherein the side opening is formed at an upper position of the mold, and the sheet-shaped molded product sequentially fed from the mold is wound up. 4. The continuous injection molding method for a ferrite sheet according to claim 1, 2 or 3, wherein the side wall shape on the side opposite to the side where the side opening is formed in the molding space is formed in a sawtooth shape. 5. The continuous injection molding method of a ferrite sheet according to claim 1, 2, 3 or 4, wherein polyvinyl chloride, an acrylic synthetic resin or a rubber resin is used as a binder for the ferrite powder-containing resin. 6. The continuous injection molding method for a ferrite sheet according to claim 1, 2, 3, 4 or 5, wherein the molding die comprises a fixed die and a movable die.