JP2008047758A - Ferrite core and its coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ferrite core which is excellent in a shock resistance and a low cost performance. <P>SOLUTION: A ferrite core 1 is a substantially annular body having a central portion in which a cable through-hole 11 is formed, and its outer face 12 is coated with a soft resin α except for an inside face 124. An example of the soft resin contain a polyvinyl chloride, polyethylene, urethane rubber, rubber latex, silicon or acrylic-based. A film thickness is equal to or more than 0.5 mm, and a hardness is equal to or less than HDD 70. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an annular ferrite core used for suppressing noise radiated from a cable and a coating method thereof.

  When a high-frequency current flows through a cable of an electric / electronic device such as a personal computer or a digital home appliance, it radiates to the surroundings as electromagnetic noise, so a ferrite core is attached to the cable to suppress this noise. . In other words, the impedance of the cable increases with the magnetization of the ferrite core and the propagation of the noise current is suppressed, while the magnetic flux generated along with the noise current is captured and the magnetic energy is converted into thermal energy in the ferrite core. To suppress noise as a whole.

  Such a ferrite core is manufactured by mixing and sintering iron oxide and a small amount of metal oxide, and since iron oxide is the main raw material, it is inherently weak against impact and the surface may be easily chipped. There is a drawback of cracking. In order to eliminate this drawback, it has been performed to accommodate the falite core in a case or to coat the outer surface of the falite core with a resin (for example, Patent Documents 1 and 2).

JP 2004-158328 A JP 2004-039855 A

  However, it has been pointed out that the method of housing the ferrite core in the case requires a separate case and a work for incorporating the ferrite core into the case, which increases the cost. On the other hand, for the method of coating the outer surface of the falite core with a resin, it is common to employ a dipping method or the like, and the resin is easily clogged in the hole during dipping, and the work of removing this is troublesome. However, there is a disadvantage that the cost becomes high.

  The present invention has been created under the above-described background, and an object of the present invention is to provide a ferrite core excellent in impact resistance and low cost and a coating method thereof.

  The ferrite core according to the present invention is an annular ferrite core used for suppressing noise radiated from a cable, and the outer surface thereof is covered with a soft resin except at least the inner surface. It is said.

  Examples of the soft resin are polyvinyl chloride, polyethylene, urethane, rubber, rubber latex, silicon or acrylic. The film thickness is preferably 0.5 mm or more, and the hardness is preferably HDD70 or less.

  The method of coating a ferrite core according to the present invention is a method of coating the ferrite core with a soft resin, and passes a plurality of ferrite cores up and down by passing through a straight hanging tool through the cable insertion hole of the ferrite core. In this state, the outer surface of the ferrite core is covered with a soft resin by an immersion method, and then the ferrite core is removed from the hanging tool.

  Spacers are placed between the ferrite cores so that the ferrite cores are not in contact with each other while being held by a hanging tool, or a hanging material coated with a material that is easy to peel off a soft resin is used. It is desirable.

  In the case of the ferrite core according to the first, second or third aspect of the present invention, the portion of the outer surface that is susceptible to impact is coated with a soft resin, so that the surface is not easily chipped or cracked, Excellent in terms of sex. In connection with this, since it is not necessary to accommodate in a case, cost reduction can be achieved. Also, since the inner surface is not covered with a soft resin, unlike the conventional case, the cable insertion hole is not clogged with the soft resin during dipping and the covering operation is simplified. This also makes it possible to reduce costs.

  In the case of the ferrite core coating method according to claim 4 or 5 of the present invention, the ferrite core is coated with a soft resin by a dipping method using a suspending tool. As a result, the cost of the ferrite core can be reduced.

  In the case of the ferrite core coating method according to claim 6 of the present invention, since the hanging tool is coated with a material that allows easy peeling of the soft resin, the hanging tool is used repeatedly without being disposable. Even in this case, the soft resin adhering to the hanging tool can be easily peeled off and cleaned. In this respect, the covering operation is simplified, and the cost can be further reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a ferrite core, and FIG. 2 is a perspective view of another ferrite core.

  The ferrite core listed here as an example is used to suppress noise radiated from power cables or signal cables for electrical and electronic equipment such as personal computers and digital home appliances. Zn, Ni, or Mn-based metal oxides are mixed and sintered.

  The ferrite core 1 shown in FIG. 1 is a substantially annular body in which a cable insertion hole 11 is formed in the center portion, and a linear cable (not shown) is used through the cable insertion hole 11. The outer surface 12 of the ferrite core 1 includes an outer surface 121, an upper side surface 122, a lower side surface 123, and an inner side surface 124.

  The most characteristic feature of the ferrite core 1 is that the outer surface 12 thereof is covered with the soft resin α except for the inner surface 124. Since the ferrite core 1 is inherently weak against impact since iron oxide is the main raw material, it is coated with the soft resin α, so the outer surface is not easily chipped or cracked due to contact between the cores, etc. Shards and powder are not scattered around.

  As the soft resin α, a resin or rubber material that has fluidity at room temperature or by heating and solidifies by reaction or cooling is used. This is to provide impact resistance and to reduce the cost by simplifying the coating process.

  Specifically, polyvinyl chloride, polyethylene, urethane, rubber, rubber latex, silicon or acrylic are used as the material, the film thickness is 0.5 mm to 3.0 mm, and the hardness is a durometer as defined in JIS K7215. It is better to use HDA30 to HDD70 depending on the surface hardness.

  The inner side surface 124 of the ferrite core 1 is not covered with the soft resin α, but other than the cable is not in contact, and the outer side surface 121, the upper side surface 122, and the lower side surface 123 are covered with the soft resin α. Therefore, the impact resistance does not decrease as a real problem. However, depending on applications and the like, the portion covered with the soft resin α may be the outer surface 121 and the upper side surface 122 and / or the lower side surface 123 may not be covered. Such a ferrite core 1 is represented as a ferrite core 1 'for convenience. The component parts also display the same.

  On the contrary, since the inner side surface 124 of the ferrite core 1 is not covered with the soft resin α, unlike the conventional case, the cable insertion hole is not clogged with the soft resin in the covering process, and the covering work is easy. This also makes it possible to reduce the cost.

  As described above, the ferrite core 1 has excellent impact resistance as compared with the case where the outer surface 12 is not coated with resin. Also, (1) No need to create a case and incorporate it into the case, (2) No need to use a special material for the soft resin α, (3) Compared to covering all of the outer surface It is possible to reduce the cost because the amount of resin required is small, and (4) the following coating process is simple.

  As described above, the ferrite core 1 according to the present invention is superior in impact resistance, low cost, and noise suppression effect as compared with the conventional one. This is exactly the same even if the basic shape changes.

  The ferrite core 2 shown in FIG. 2 is a rectangular annular body in which a cable insertion hole 21 is formed at the center portion, and a flat cable (not shown) is used through the cable insertion hole 21. The outer surface 22 of the ferrite core 2 is composed of an outer surface 221, an upper surface 222, a lower surface 223 and an inner surface 224, and is covered with a soft resin α except for the inner surface 224. That is, the basic shape is different, and the rest is exactly the same as the ferrite core 1.

  Next, a method for coating the outer surface 12 of the ferrite core 1 with the soft resin α by an immersion method will be described with reference to the drawings. 3A and 3B are diagrams for explaining the method, wherein FIG. 3A is a side view of a hanging tool and the like, and FIG. 3B is a side view showing a state in which a ferrite core is attached to the hanging tool and the like.

  First, the hanging tool 3 and the spacer 4 that are used to coat the outer surface 12 of the ferrite core 1 will be described.

  The hanging tool 3 is a linear holding tool that holds a plurality of ferrite cores 1 side by side, and includes a disc part 31 that is slightly smaller in diameter than the ferrite core 1 and a central part of the upper surface of the disc part 31. And a shaft-like portion 32 having a diameter slightly smaller than the cable insertion hole 11 of the ferrite core 1 and a wire-like hook portion 33 attached to the tip of the shaft-like portion 32. . The spacer 4 is a ring-shaped body having a slightly larger diameter than the cable insertion hole 11 of the ferrite core 1, and is passed through the shaft-shaped portion 32 of the hanging tool 3.

  A method of covering the outer surface 12 of the ferrite core 1 using the hanging tool 3 and the spacer 4 is as follows.

  The spacer 4 is passed through the shaft-like portion 32 of the hanging tool 3 and placed on the disc portion 31. FIG. 3A shows this state. Then, after passing the cable insertion hole 11 of the ferrite core 1 through the shaft-like portion 32 of the suspending tool 3, the spacers 4 and the ferrite core 1 are alternately passed. FIG. 3B shows this state.

  That is, a plurality of (six in the illustrated example) ferrite cores 1 are vertically arranged and held at intervals with the suspension 3 and the spacers 4. In this state, the soft resin α is coated on the outer surface of the ferrite core 1 by a dipping method. The specific coating method differs slightly depending on the type of the soft resin α.

  For example, when the soft resin α is polyvinyl chloride, the ferrite core 1 or the like is put in a preheating furnace (not shown), preheated to 150 to 300 ° C., and placed in a paste tank (not shown) containing polyvinyl chloride paste. Put in and soak. At this time, the polyvinyl chloride paste in contact with the outer surface 12 of the ferrite core 1 is gelled by the heat amount of the ferrite core 1.

  Thereafter, the ferrite core 1 and the like are taken out from the paste tank, put in a heating furnace (not shown), the entire ferrite core 1 and the like are further heated, and the polyvinyl chloride paste adhered to the outer surface of the ferrite core 1 and the like is completely gelled. Make it. Thereafter, the ferrite core 1 and the like are taken out from the heating furnace, and the ferrite core 1 and the spacer 4 are removed from the hanging tool 3.

  As a result, the outer surface 121, the upper side surface 122, and the lower side surface 123 of the outer surface 12 of the ferrite core 1 are covered with the soft resin α. That is, since the shaft portion 32 of the hanging tool 3 is passed through the cable insertion hole 11 of the ferrite core 1 and is immersed in the polyvinyl chloride paste, the soft resin α Is not coated. On the contrary, since the ferrite cores 1 are prevented from contacting each other by the spacer 4, the upper side surface 122 and the lower side surface 123 of the ferrite core 1 are covered with the soft resin α.

  In order to save raw material costs, improve physical strength, and adjust viscosity, a filler may be added to the polyvinyl chloride paste as necessary. Moreover, in order to improve the adhesiveness between the outer surface 12 of the ferrite core 1 and the soft resin α, it is preferable to perform a primer treatment in advance before immersing the ferrite core 1 or the like in the paste tank.

  The hanging tool 3 and the spacer 4 are used repeatedly. Therefore, it is necessary to clean the soft resin α adhering to the outer surface each time, so that the soft resin can be easily peeled off from the outer surface for easy cleaning, such as Teflon (registered trademark). It is good to coat with. This is particularly effective when the soft resin α is polyene vinyl chloride, and the suspending tool 3 and the spacer 4 can be easily detached from the ferrite core 1.

  When the soft resin α is polyethylene, the powdered polyethylene is coated on the ferrite core 1 in the same manner as described above by a fluid immersion method. That is, the ferrite core 1 and the like are put in a preheating furnace (not shown) and preheated, immersed in a powder mist tank of powder polyester (not shown), and the outer surface of the ferrite core 1 is covered with a soft resin α of polyethylene. The ferrite core 1 and the spacer 4 are removed from the hanging tool 3.

  When the soft resin α is urethane, the ferrite core 1 is coated in the same manner as described above by a two-component urethane reactive liquid dipping method. The ferrite core 1 and the like are immersed in a raw material reaction tank, the outer surface of the ferrite core 1 is covered with a soft urethane resin α, and finally the ferrite core 1 and the spacer 4 are removed from the hanging tool 3.

  Since the two-component urethane is cured by mixing, it is different from the above method in that preheating and heating after immersion are unnecessary or a low temperature is sufficient. However, when there is dripping of the liquid, it is preferable to shorten the curing time by heating or to rotate the ferrite core 1 or the like to make the urethane soft resin α uniform.

  When the soft resin α is rubber latex, the ferrite core 1 is coated in the same manner as described above by a dipping method of a liquid raw material of rubber latex. The ferrite core 1 and the like are immersed in the raw material tank, and the outer surface of the ferrite core 1 is coated with a rubber latex soft resin α. Finally, the ferrite core 1 and the spacer 4 are removed from the hanging tool 3.

  Since the rubber latex is formed by simply drying the rubber latex, it is the same as the above method in that preheating and heating after immersion are not required or may be performed at a low temperature. But when bridge | crosslinking and vulcanization are carried out with a heat | fever, it is good to make it heat to predetermined temperature after taking out from a raw material tank. When there is dripping of the liquid, it is preferable to shorten the drying time by heating or to rotate the ferrite core 1 or the like so that the rubber latex soft resin α is made uniform. Further, by permeating into the latex coagulant solution, a rubber layer is formed in a short time, and the processing time can be shortened and sagging can be prevented.

  In addition, the ferrite core 1 is an electrical product and requires high flame retardancy. Although the flame retardancy of polyvinyl chloride, urethane, and rubber latex itself is high, the flame retardancy may be lowered by the addition of a plastic material or the like. At this time, it is preferable to add a flame retardant separately.

  When the outer surface 12 ′ of the ferrite core 1 ′ is coated with the soft resin α in the same manner as described above, a hanging tool 3 ′ shown in FIG. 4A is used, and a plurality of ferrite cores are provided on the shaft portion 32 ′. The 1 'cable insertion holes 11' are sequentially passed. FIG. 4B shows this state.

  That is, a plurality of (six in the illustrated example) ferrite cores 1 are vertically arranged and held at intervals with the suspension 3. In this state, the soft resin α is coated on the outer surface of the ferrite core 1 by a dipping method. The coating method is exactly the same as described above.

  As a result, the outer surface 121 ′ of the outer surface 12 ′ of the ferrite core 1 ′ is covered with the soft resin α. That is, the inner surface 124 of the ferrite core 1 ′ is immersed in the polyvinyl chloride paste or the like with the shaft portion 32 ′ of the suspending tool 3 ′ passed through the cable insertion hole 11 ′ of the ferrite core 1 ′. 'Is not coated with soft resin α. Further, since the ferrite cores 1 ′ are in contact with each other, the upper surface 122 ′ and the lower surface 123 ′ of the ferrite core 1 ′ are not covered with the soft resin α except for a part thereof.

  The hanging tool and spacer used to coat the outer surface 22 of the ferrite core 2 with the soft resin α are the same as described above, and are different only in the shape.

  When the soft resin α is coated on the outer surface 12 (12 ′) of the ferrite core 1 (1 ′) using the hanging tool 3 (3 ′) or the like in this way, the point that the dipping method is used, the coating once This is very efficient in that the six ferrite cores 1 (1 ′) and the like are coated in the process, and the cost can be reduced in this respect as well.

  In addition, about the ferrite core which concerns on this invention, as long as it is a cyclic | annular thing used in order to suppress the noise radiated | emitted from a cable, it is not limited to the said embodiment about the shape, material, etc. The same applies to the material and covering method of the soft resin that covers the outer surface. For example, the outer surface of the ferrite core may be covered with a heat shrinkable tube except for its inner surface.

It is a figure for demonstrating embodiment of this invention, Comprising: It is a perspective view of a ferrite core. It is a perspective view of another ferrite core. It is a figure for demonstrating the coating method of a philite core, Comprising: (a) is a side view of a hanging tool etc., (b) is a side view which shows the state with which the ferrite core was attached to the hanging tool etc. . It is a figure for demonstrating the coating method of another philite core, Comprising: (a) is a side view of a hanging tool, (b) is a side view which shows the state with which the ferrite core was attached to the hanging tool. .

Explanation of symbols

1, 2 Philite Core 11, 21 Cable insertion hole 12, 22 Outer surface 121, 221 Outer side surface 122, 222 Upper side surface 123, 223 Lower side surface 124, 224 Inner side surface 3 Suspension tool 4 Spacer

Claims (6)

An annular ferrite core used for suppressing noise radiated from a cable, wherein the outer surface is covered with a soft resin except at least the inner surface. 2. The ferrite core according to claim 1, wherein the soft resin is polyvinyl chloride, polyethylene, urethane, rubber, rubber latex, silicon or acrylic. 3. The ferrite core according to claim 2, wherein the thickness of the soft resin is 0.5 mm or more and the hardness is HDD70 or less. In the method of coating a soft resin on the ferrite core according to any one of claims 1 to 3, a plurality of ferrite cores are vertically arranged and held in a cable penetrating hole of the ferrite core through a straight hanging tool, and left as it is. A method for coating a ferrite core, characterized in that the outer surface of the ferrite core is coated with a soft resin by an immersion method, and then the ferrite core is removed from the hanging tool. 5. The ferrite core coating method according to claim 4, wherein a spacer is disposed between the ferrite cores so that the ferrite cores are not in contact with each other while being held by the suspension tool. Method. 5. The method of coating a ferrite core according to claim 4, wherein the hanging tool is coated with a material that allows easy peeling of the soft resin.

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