JP2005294319A - Mold for compression molding, compression molded product and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintered material having a high dimensional accuracy in an entire sintered material in the sintered material which has a U shape and in which a groove is formed. <P>SOLUTION: A compression molded product has the U shape in which two first and second pole legs are extended in a substantially perpendicular direction from both ends of a rod-like molded product body, and the groove is formed from the first end of one end toward the vicinity of the second end of the other end along the longitudinal direction of the molded product body on the opposed surface of the opposite direction to the pole let forming surface in the molded product body. The width of the intermediate part disposed between the pole legs of the molded product body is smaller than the other part, and a tapered part is formed in which the width of the molded product body is continuously reduced from the first end direction toward the intermediate part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a compression molded body and a manufacturing method thereof, and more specifically, a compression molded body whose size and shape are controlled so as to increase the dimensional accuracy of a sintered body obtained by firing, and a manufacturing method thereof, and The present invention relates to a compression mold for producing the compression molded body, and a sintered body with high dimensional accuracy obtained by firing the compression molded body.

  Ferrite cores (ferrite sintered bodies) used as magnetic cores for coils and transformers, for example, are filled with a powder of ferrite powder, which is a powder material, and compressed and pressed (pressed). It is manufactured by forming and firing this compression molded body.

  Examples of the ferrite core include a split type core such as a UU type core, an EE type core, and an EI type core. Among such split cores, for example, a coil or a transformer using a UU core is formed by combining two U cores and inserting them into a bobbin having a winding. Thus, when two U-shaped cores are inserted into a bobbin to form a coil or a transformer, it is necessary to fix each core with a fixing jig such as a clip. In the core of the mold, a fixing groove for fixing is formed.

  In a U-shaped core having a fixing groove, the groove is formed by using, for example, a molding die having a groove-forming convex portion as an upper mold for compression when compression molding. However, when the groove is formed in the compression molded body by such a method, the molding density of the part where the groove is formed becomes higher than the molding density of the other part, resulting in a density difference in the molded body. End up. Then, due to this density difference, there is a problem that a difference in shrinkage ratio occurs during firing, the dimensional accuracy of the sintered body after firing is reduced, and a dimensional defect occurs.

  In order to solve the above-mentioned problem, for example, in Patent Document 1, when manufacturing a U-shaped compression molded body having a groove portion, a molded body main body is obtained by setting a protruding portion in advance in a frame mold of a molding die. A method of forming a recess in the middle part of the above is disclosed. In this document, the difference in shrinkage rate during firing is reduced by adjusting the molding width of the portion where the molding density is increased by forming the groove.

  However, the invention described in this document adjusts the molding width only for the portion inserted into the bobbin among the portions where the molding density increases due to the formation of the groove, and other portions that are not inserted into the bobbin. For, the width of the molding is not adjusted. Therefore, the ferrite sintered body obtained by the invention described in this document remains low in dimensional accuracy other than the portion inserted into the bobbin, as in the conventional case.

  On the other hand, in recent years, automation of the process of inserting a ferrite core into a bobbin is progressing for the purpose of improving production efficiency. In order to insert the ferrite core into the bobbin by an automatic machine, it is required that the dimensional accuracy of the entire core is high, that is, that the dimensional accuracy other than the portion inserted into the bobbin is high. However, in the invention described in Patent Document 1, although the dimensional accuracy is controlled for the portion inserted into the bobbin, the dimensional accuracy other than the portion inserted into the bobbin remains low, so the above requirement is satisfied. I couldn't. Therefore, in order to ensure dimensional accuracy in such a sintered body, a total inspection of the sintered body is performed separately. For products that are out of specification as a result of the inspection, the dimensions are included in the standard. In addition, it is necessary to perform additional processing such as grinding, which is a cause of an increase in manufacturing cost.

No. 7-39510

  The present invention is made in view of such a situation, and in a sintered body having a U-shape and having a fixing groove formed therein, the sintered body having high dimensional accuracy over the entire sintered body. The purpose is to provide. The present invention also provides a compression molded body that becomes a sintered body having high dimensional accuracy by firing, a method for manufacturing the same, and a mold for compression molding for manufacturing such a compression molded body. Also aimed.

  The present inventors have a U-shape in which two column bases extend from both ends of a rod-shaped molded body main body in a substantially right angle direction, and are opposed surfaces in the opposite direction to the column base forming surface of the molded body main body. In addition, in the compression molded body in which the groove is formed, a recess is formed so that the width of the intermediate portion located between the column bases in the molded body is smaller than that of the other portion, and in the intermediate portion On the other hand, it has been found that the above object can be achieved by forming a tapered portion in which the width of the molded body is continuously reduced, and the present invention has been completed.

That is, the compression molded body of the present invention is
Having a U-shape in which the first column base and the second column base extend in a substantially right angle direction from both ends of the rod-shaped molded body,
On the opposite surface of the molded body main body in the direction opposite to the column base forming surface, the length of the molded body main body extends from the first end that is one end to the vicinity of the second end that is the other end. A compression molded body in which grooves are formed along the direction,
The width of the intermediate part located between the column bases in the molded body is smaller than that of the other part, and from the first end direction toward the intermediate part, the width of the molded body A taper portion having a continuously decreasing width is formed.

  The compression molded body of the present invention is formed with a tapered portion in which the width of the intermediate portion of the molded body is smaller than that of other portions and the width of the molded body is continuously reduced. There is a feature in the point. By making the compression molded body into such a shape, it becomes possible to prevent the occurrence of dimensional defects due to the difference in shrinkage during firing, and thus it is possible to obtain a sintered body with high dimensional accuracy. Become.

In the compression molded body according to the present invention, preferably,
Tapered portions are formed on both sides in the width direction of the molded body.

In the compression molded body according to the present invention, preferably,
The tapered portion is also formed on a first column base extending from the first end portion.

  The tapered portion formed on the first column base may be formed on at least a part of the first column base, but may be formed over the entire first column base, for example. Moreover, it is preferable that the taper part formed in the said 1st column base is formed continuously with the taper part formed in the said molded object main body.

In the compression molded body according to the present invention, preferably,
The first column base extending from the first end is a rectangular column base having a quadrangular cross section.
The second column base extending from the second end is a columnar leg having a circular cross section.

In the compression molded body according to the present invention, preferably,
The depth (D) of the groove is formed with a dimension of 25% or more of the width (W) of the molded body in the depth direction of the groove, and
The width (G) of the groove is formed to be 25% or more of the width (C) of the portion where the second column base is formed in the molded body.

In the compression molded body according to the present invention, preferably,
The longitudinal direction along the groove length of the molded body of the groove (L _G) is formed by more than 50% of the length with respect to the distance (L1) between said first and second ends Has been.

  The compression molded body of the present invention is not particularly limited, and examples thereof include a ceramic molded body and a ferrite molded body.

The method for producing the compression molded product of the present invention comprises:
A method for producing any one of the above compression-molded bodies,
Filling powder material into a powder filling recess which is a powder material filling portion; and
A step of pressing a molding convex mold into the powder filling concave section filled with the powder material, and compressing and molding the powder material by applying a compressive force.

The sintered body of the present invention can be obtained by firing any one of the above compression-molded bodies.
In the compression molded body of the present invention, the width of the intermediate part of the molded body is smaller than that of other parts in order to prevent the occurrence of dimensional defects due to the difference in shrinkage during firing. And the taper part which the width | variety of a molded object main body becomes small continuously is formed. Therefore, since the sintered body of the present invention is a sintered body obtained by firing such a compression molded body, it becomes possible to have high dimensional accuracy over the entire sintered body.

  In the present invention, the sintered body is preferably a ferrite sintered body. This ferrite sintered body can be used, for example, as a ferrite core for coils and transformers.

The mold for compression molding of the present invention is
A mold for compression molding for producing any one of the above compression molded bodies,
A molding concave mold having a powder filling recess for filling the powder material;
A molding convex mold that is pressed into the molding concave mold filled with a powder material and applies a compressive force to the powder material;
The concave portion for powder filling has an intermediate portion forming projection that will form the intermediate portion of the molded body, and a tapered portion forming protrusion that will form the tapered portion.

  According to the present invention, in the U-shaped compression molded body having a groove portion, the concave portion is formed such that the width of the intermediate portion located between the column bases in the molded body is smaller than that of the other portion, and By forming a tapered part that continuously reduces the width of the molded body toward the intermediate part, it is possible to prevent the occurrence of dimensional defects due to the difference in shrinkage during firing, and sintering. It becomes possible to obtain a sintered body with high dimensional accuracy over the entire body.

  Further, according to the present invention, since a sintered body with high dimensional accuracy can be obtained over the entire sintered body in this way, for example, when inserting a ferrite sintered body formed of ferrite into a bobbin, As described above, in order to ensure dimensional accuracy, it is possible to insert into a bobbin using an automatic machine without separately inspecting the total number of sintered bodies or performing additional processing, thereby reducing manufacturing costs. Can be achieved.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
1A is a front view of a ferrite molded body according to an embodiment of the present invention, FIG. 1B is a top view, FIG. 1C is a bottom view, and FIG. 1D is FIG. Id-Id line sectional view of
2A is a front view of a ferrite sintered body according to an embodiment of the present invention, FIG. 2B is a top view, FIG. 2C is a bottom view, and FIG. 2D is FIG. IId-IId line sectional view of
3A is a top view of a ferrite molded body according to an embodiment of the present invention, FIGS. 3B and 3C are top views of a conventional ferrite molded body,
4A is a top view of a ferrite sintered body according to an embodiment of the present invention, FIG. 4B and FIG. 4C are top views of a conventional ferrite sintered body,
FIG. 5 is a top view of a coil according to an embodiment of the present invention,
6A is a cross-sectional view of a compression mold according to an embodiment of the present invention, FIG. 6B is a cross-sectional view taken along the line VIb-VIb of FIG. 6A, and FIG. Top view of concave,
FIG. 7 is a graph showing the relationship between the density of the molded body and the shrinkage ratio of the sintered body by firing.

Ferrite molded body 1
As shown in FIG. 1 (A) to FIG. 1 (D), a ferrite molded body 1 according to an embodiment of the present invention is U-shaped, a rod-shaped molded body 2, a prism 3, and a cylinder 4. And have. The prism 3 extends from the first end 6a which is one end of the molded body 2 and the column 4 extends from the second end 6b which is the other end in a substantially perpendicular direction. The dimension of the ferrite molded body 1 is not particularly limited and may be an appropriate dimension according to the use. Usually, the length (L1) of the molded body 2 is 15 to 100 mm, and the length of the column base (L2) is 5 to 5. 60 mm, thickness (C) is about 5 to 30 mm.

  As shown in FIG. 1C, the prism 3 extending from the first end 6a has a quadrangular cross-sectional shape, and the cylinder 4 extending from the second end 6b has a circular shape. It has a cross-sectional shape.

  Moreover, in the ferrite molded body 1 of this embodiment, as shown to FIG. 1 (A) and FIG. 1 (B), it is opposite to the column base formation surface 6c in which the prism 3 and the cylinder 4 of the molded body 2 are formed. A groove portion 5 is formed in the direction facing surface 6d from the first end portion 6a toward the vicinity of the second end portion 6b along the longitudinal direction of the molded body 2. The groove 5 is used for fixing with a fixing jig such as a clip when the ferrite molded body 1 is fired and used as a ferrite core and inserted into a bobbin.

  In the ferrite molded body 1 of the present embodiment, as shown in FIGS. 1B to 1D, the width of the intermediate part 2 c located between the column bases in the molded body 2 is larger than that of other parts. Recesses 2b are formed on both sides so as to be smaller. The depth Δx of each recess 2b is not particularly limited, and may be appropriately selected according to the depth (D) and width (G) of the groove 5, the density at the time of molding, etc. 0.1 to 0.5 mm.

  Further, in the ferrite molded body 1, a taper portion 2a is formed in the molded body 2 from the first end 6a toward the concave portion 2b formed in the intermediate portion 2c. Since the cross-sectional shape of the prism 3 is rectangular, the tapered portion 3a is also formed in the prism 3 in order to smoothly connect the tapered portion 2a and the rectangular prism 3.

  As shown in FIGS. 1B and 1D, the tapered portion 2a formed in the molded body 2 is formed on the entire surface from the first end 6a to the recess 2b. The tapered portion 2a is formed so that the width of the molded body 2 is continuously reduced.

  The formation length (T) of the tapered portion 2a formed on the molded body 2 is not particularly limited, and depends on the depth (D) and width (G) of the groove portion 5, the density at the time of molding, and the like. Can be selected as appropriate. The formation length (T) of the tapered portion 2a is preferably longer than the width (M) in the short direction of the prism 3 and about 1 to 5 mm longer than the width (M) of the prism 3 in the short direction. In particular, it is preferable to make the length about 2 mm longer.

  As shown in FIG. 1 (D), the tapered portion 3a formed on the prism 3 is formed from the direction of the tip of the prism 3 toward the tapered portion 2a formed on the molded body 2; The tapered portion 3a is formed not from the tip portion of the prism 3 but starting from a portion on the way from the tip portion toward the tapered portion 2a. Further, the tapered portion 3a of the prism 3 is formed from the tip of the prism 3 toward the tapered portion 2a.

  The feature of the present invention is that, in the compression molded body, a concave portion is formed so that the width of the intermediate portion of the molded body is smaller than that of the other portion, and the first end portion direction is directed toward the intermediate portion. In addition, a taper portion in which the width of the molded body is continuously reduced is formed. By using such a compression molded body, it becomes possible to reduce the dimensional defect of the sintered body due to the difference in shrinkage during firing, and the sintered body has high dimensional accuracy over the entire sintered body. Can be obtained.

  2A to 2C are views showing a ferrite sintered body 10 obtained by firing the ferrite molded body 1 of the present embodiment. Similar to the ferrite molded body 1, the ferrite sintered body 10 is formed of a sintered body 12, a prism 13, and a cylinder 14, and has a groove 15.

  Conventionally, as shown in FIG. 3 (B), the width of the intermediate part of the molded body is the same as the width of the other part, or as shown in FIG. 3 (C), the molded body body Attempts have been made to reduce only the width of the middle part of the slab compared to the other parts. On the other hand, as shown in FIG. 3 (A), the present invention makes the width of the intermediate part 2c of the molded body 2 smaller than that of the other part and is intermediate from the first end direction 6a. A taper portion 2a in which the width of the molded body 2 is continuously reduced toward the portion 2c is characterized.

Hereinafter, the difference between the conventional ferrite molded body and the ferrite molded body of the present invention will be described with reference to FIGS. 3 (A) to 3 (C) and FIGS. 4 (A) to 4 (C).
3 (A) to 3 (C) correspond to the top view of the ferrite molded body shown in FIG. 1 (B), and FIGS. 4 (A) to 4 (C) correspond to FIG. 2 (B). This corresponds to the top view of the ferrite sintered body shown in FIG. In each figure, although the illustration of the groove portion is omitted, each ferrite sintered body and each ferrite molded body have groove portions formed in the sintered body main body, the intermediate portion of the molded body main body, and the prism forming portion. Yes.

  Conventionally, as shown in FIG. 3B, the width of the intermediate portion 2c-1 of the molded body main body 2-1 is substantially the same as the width of other portions. Then, as shown in FIG. 4B, the sintered body produced by firing this compression-molded body has a width C2 of the intermediate portion where the groove is formed and a width C3 of the prismatic portion forming portion. As compared with the width C1 of the columnar portion where no is formed, there is a problem that the size becomes large and a dimensional defect occurs. This problem of dimensional defects tended to be particularly prominent when the depth (D) and width (G) of the groove portions were large.

  The cause of this is considered to be that the molding density of the part where the groove part is formed is higher than the molding density of the part where the groove part is not formed, resulting in a difference in shrinkage during firing. It is done. As shown in FIG. 7, the shrinkage ratio due to firing and the density of the molded body have a certain correlation, and as the density of the molded body increases, the shrinkage ratio tends to decrease. As the density decreases, the shrinkage tends to increase.

  Alternatively, as shown in FIG. 3C, it is also proposed to provide a concave portion having a depth Δx in the intermediate portion 2c-2 of the molded body main body 2-2 so that the width of the intermediate portion is smaller than that of other portions. Has been. This method is expected to prevent the width C2 of the intermediate portion of the sintered body after firing from becoming larger compared to other portions due to the difference in shrinkage ratio during firing. However, in this case, since the width of the intermediate part of the molded body is only made smaller than that of the other parts, the width of the intermediate part of the sintered body as shown in FIG. Although it was possible to make C2 and the width C1 of the columnar forming portion approximately the same size, the width C3 of the prism forming portion was not improved.

  On the other hand, in the present invention, as shown in FIG. 3 (A), a concave portion having a depth Δx is provided in the intermediate portion of the molded body, the width of the intermediate portion is made smaller than the other portions, and The taper part which the width | variety of a molded object main body becomes small continuously from the 1st edge part direction toward an intermediate part is formed. Therefore, as shown in FIG. 4 (A), the sintered body produced by firing the ferrite molded body of the present invention has a width C1 of the columnar forming portion of the sintered body, a width C2 of the intermediate portion, and The width C3 of the prismatic portion can be made substantially uniform, and as a result, a sintered body having high dimensional accuracy over the entire sintered body can be obtained.

  Moreover, in this embodiment, the groove part 5 formed in the molded body main body 2 is, as shown in FIG. 1 (A), from the first end portion 6a toward the vicinity of the second end portion of the molded body body. It is formed along the longitudinal direction. The groove portion 5 has a substantially uniform depth (D) in the intermediate portion located between the column bases in the molded body 2, and in the vicinity of the first end portion 6 a where the prism 3 is formed. The groove portion 5 has a shape that increases the depth. In the present embodiment, the shape of the groove portion 5 is such that the depth is increased in the vicinity of the first end portion 6a in order to facilitate insertion of a fixing clip when the groove portion 5 is incorporated into the bobbin.

  The depth (D) and the width (G) of the groove 5 formed in the molded body 2 may be appropriately selected according to the application and purpose, but the depth (D) of the groove 5 is the depth of the groove 5. It is preferable that the length is 25% or more of the width (W) of the molded body 2 in the vertical direction, and the width (G) of the groove 5 is the portion of the molded body 2 where the column 4 is formed. The length is preferably 25% or more of the width (C).

  When the depth (D) and the width (G) of the groove portion 5 are increased, the molding density of the portion where the groove portion 5 is formed in the ferrite molded body tends to be higher than the molding density of other portions. . Therefore, when the depth (D) and width (G) of the groove part 5 are enlarged, the effect of this invention is exhibited especially.

The groove length (L _G ), which is the length of the groove 5 along the longitudinal direction of the molded body 2, may be appropriately selected depending on the application and purpose, but the groove length (L _G ) Preferably, it is formed with a length of 50% or more with respect to the distance (L1) between the first end 6a and the second end 6b.

Manufacturing Method of Ferrite Molded Body 1 The ferrite molded body 1 of the present embodiment is manufactured by first preparing a ferrite powder that constitutes the ferrite molded body 1 and then compression molding the ferrite powder.
Hereinafter, the manufacturing method of the ferrite molded object 1 of this embodiment is demonstrated.

  First, a ferrite powder that constitutes the ferrite molded body 1 is prepared. The ferrite powder is obtained by calcining, pulverizing, and granulating a ferrite raw material.

  Although it does not specifically limit as a ferrite raw material, Iron oxide, zinc oxide, manganese oxide, copper oxide, nickel oxide etc. can be used, and various compounds can be added as a subcomponent as needed.

  Next, the ferrite raw material is calcined. Calcining causes thermal decomposition of raw materials, homogenization of ingredients, formation of ferrite, disappearance of ultrafine powder due to sintering and grain growth to an appropriate particle size, and converts the raw material mixture into a form suitable for the subsequent process. Done for. Calcination is performed in an oxidizing atmosphere, usually in air. The calcination temperature is preferably 800 to 1000 ° C., and the calcination time is preferably 1 to 3 hours.

  Next, the calcined material obtained above is pulverized to obtain a pulverized material. The pulverization is performed in order to produce a powder having appropriate sinterability by destroying the aggregation of the calcined material. When the calcined material forms a large lump, wet pulverization is performed using a ball mill or an attritor after coarse pulverization.

  Next, the pulverized material is granulated (granulate) to obtain a powder material (granulated product). Granulation is performed in order to convert the pulverized material into aggregated particles of an appropriate size and convert them into a form suitable for molding. Examples of such a granulation method include a pressure granulation method and a spray drying method. The spray drying method is a method in which a commonly used binder such as polyvinyl alcohol is added to the pulverized material, and then atomized in a spray dryer and dried.

Next, the obtained ferrite powder is compression molded using a compression molding die 20 shown in FIGS. 6A to 6C to obtain a ferrite molded body 1.
The compression molding is performed by filling the powder filling concave portion 26 formed in the molding concave mold 22 with ferrite powder, and compression molding with the molding concave mold 22 and the molding convex mold 24.

  As shown in FIG. 6 (A), the compression molding die 20 of the present embodiment is pressed into the molding concave mold 22 having the powder filling concave portion 26 and the molding concave mold 22 so as to apply a compressive force to the ferrite powder. And a molding convex mold 24 to be added.

  The molding recess 22 has a powder filling recess 26 that is a powder material filling portion, and the powder filling recess 26 is a molding recess formed by a frame mold 28, an intermediate mold 30, and a lower punch 32. . As shown in FIG. 6C, an intermediate portion forming protrusion 38 and a tapered portion forming protrusion 40 are formed on the frame mold 28 forming the powder filling recess 26. The intermediate portion forming protrusion 38 and the tapered portion forming protrusion 40 are forming protrusions for forming the concave portion 2 b and the tapered portions 2 a and 3 a in the ferrite molded body 1. Therefore, by appropriately adjusting the intermediate portion forming protrusion 38 and the tapered portion forming protrusion 40, it is possible to control the width, forming position, and the like of the recessed portion 2b and the tapered portions 2a and 3a of the ferrite molded body 1 to be manufactured. It becomes.

  The molding convex mold 24 has an upper punch 34 having a groove forming projection 36 at the tip. The groove forming protrusion 36 is a protrusion for forming the groove 5 of the ferrite molded body 1. Therefore, the shape of the groove forming protrusion 36 can be appropriately selected according to the shape of the groove 5 to be formed. It is.

  When compression molding is performed using the compression molding die 20 of this embodiment, the molding density is controlled by controlling the compression force when the upper punch 34 is pushed in and the compression force of the lower punch 32. Can be adjusted. In the compression molding die 20 of the present embodiment, the lower punch 32 is fixed so that a certain compressive force is applied to the ferrite powder, and in the process of pressing and pressing the upper punch 34 into the powder filling recess 26, The frame die 28 is moved downward to obtain a compressive force from the lower punch 32.

The ferrite molded body 1 of the present embodiment is manufactured through the above steps.
In the present embodiment, the ferrite sintered body 10 can be obtained by firing the ferrite molded body 1 thus obtained.

  The firing conditions for firing the ferrite molded body 1 to produce the ferrite sintered body 10 include, for example, a stable temperature (firing temperature): 1100 to 1250 ° C., a temperature rising rate: 50 to 300 ° C./hr, and a firing time. : About 2 to 8 hours, Firing atmosphere: It can be set as the atmosphere which controlled oxygen concentration.

  A ferrite sintered body 10 obtained by firing the ferrite molded body 1 of the present embodiment includes a sintered body body 12, a prism 13 and a cylinder 14 as shown in FIGS. 2 (A) to 2 (C). It is formed and has a groove 15. Moreover, since the ferrite sintered body 10 is a sintered body obtained by firing the ferrite molded body 1, it is a sintered body having high dimensional accuracy over the entire sintered body.

  Further, as shown in FIG. 5, the ferrite sintered body 10 is used as a core for a coil or a transformer by inserting and combining two ferrite sintered bodies 10 into a bobbin having a winding. . This ferrite sintered body 10 has a prism 13 of one sintered body, a prism 13 of the other sintered body, and a cylinder 14 of one sintered body and a cylinder 14 of the other sintered body opposed to each other. They are combined via a bobbin 17.

  In the prior art, only the sintered body main body 12 and the cylinder 14 which are parts inserted into the bobbin 17 have been reduced in dimensional defects. However, the ferrite sintered body 10 of the present invention is a sintered body. It has high dimensional accuracy throughout. Therefore, according to the present invention, for example, the ferrite sintered body 10 can achieve the dimensional accuracy required when it is inserted into the bobbin by an automatic machine. For this reason, it is not necessary to separately inspect all the sintered bodies and perform additional processing, so that the manufacturing cost can be reduced.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, in the above-described embodiment, the ferrite molded body and the ferrite sintered body composed of ferrite are exemplified as the compression molded body and the sintered body according to the present invention, but the compression molded body and the sintered body according to the present invention are exemplified. However, the present invention is not limited thereto, and any ferrite molded body molded by compression molding and any sintered body obtained by firing the ferrite molded body may be used.

  In the embodiment described above, the molding concave mold 22 constituting the compression molding mold 20 is the molding concave mold 22 formed by the frame mold 28, the pair of middle molds 30, and the lower punch 32. As the concave mold, a mold having an integrated structure can be used. In the above-described embodiment, the lower punch 32 is fixed in the process of pressing and pressing the upper punch 34 into the powder filling recess 26, and the frame mold 28 is moved downward to compress the lower punch 32. Although the structure for obtaining the force is illustrated, the lower punch 32 may have a structure that descends by pushing the upper punch 34, and the upper punch 34 is placed in the recess 16 for powder filling. It is good also as a structure which raises the lower punch 32 while pushing.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

[Preparation of sintered body sample of example]
First, ferrite raw materials were prepared as starting materials, and then these raw materials were blended, calcined, pulverized and granulated to obtain ferrite powders.

The obtained ferrite powder was compression molded using a compression mold shown in FIG. 6 to obtain a ferrite molded body shown in FIG.
In this embodiment, in FIG. 1, the width (C) of the portion of the molded body 2 where the column 4 is formed, the formation length (T) of the tapered portions 2a and 3a, and the depth (Δx) of the recess 2b. Was adjusted so that the width of the sintered ferrite body after firing was 15.0 mm. That is, the ferrite molded body was manufactured so that the width C1 of the columnar forming portion, the width C2 of the intermediate portion, and the width C3 of the prismatic forming portion of the sintered body in FIG. 4A were 15.0 mm.
Next, the obtained ferrite molded body was fired to produce a sintered body sample of an example of the present invention.

[Production of sintered body sample of comparative example]
A ferrite molded body was prepared in the same manner as the sintered body sample of the example of the present invention, except that the shape without the tapered portions 2a and 3a as shown in FIG. The sintered body sample of the comparative example was produced by baking.

  About the sintered compact sample of the obtained Example and the comparative example, the measurement of the sintered compact dimension, the measurement of saturation magnetic flux density, and the measurement of core loss were performed.

The sintered body dimensions were measured with respect to the sintered body sample of the obtained example with respect to the width C1 of the cylinder forming portion, the width C2 of the intermediate portion, and the width of the prism forming portion of the sintered body shown in FIG. C3 was measured by measuring each. The measurement was performed on 15 sintered body samples.
Similarly, the width C1 of the column forming part, the width C2 of the intermediate part, and the width C3 of the prism forming part of the sintered body main body shown in FIG. The measurement was performed on 15 sintered body samples.
Table 1 shows the measurement results of the sintered body samples of Examples, and Table 2 shows the measurement results of the sintered body samples of Examples and Comparative Examples. In addition, the sintered compact dimension made the sample which enters into the range of ± 5.0 mm from 15.0 mm which is a design value favorable.

  The saturation magnetic flux density (unit: mT) was measured by combining two sintered body samples of the example as shown in FIG. 5 and combining the primary winding and the secondary winding with primary: 100 / secondary: 10 A transformer sample was prepared by winding each time, and a BH curve tracer manufactured by Riken Denshi Co., Ltd. was used and a magnetic field of 1200 A / m was applied at a measurement temperature of 23 ° C. Measurement was performed on five transformer samples, and evaluation was performed by calculating an average value of the measurement results. Moreover, the saturation magnetic flux density was similarly measured about the sintered compact sample of the comparative example. Table 3 shows the measurement results for the sintered body samples of Examples and Comparative Examples.

  The core loss (unit: W / kg) was measured by preparing a sample similar to the transformer sample used in the measurement of the saturation magnetic flux density for the sintered body samples of Examples and Comparative Examples, and BH manufactured by Iwasaki Tsushinki Co., Ltd. -Performed using an analyzer (SY-8217). The measurement conditions were an excitation magnetic flux density of 150 mT, a frequency of 16 kHz, and a measurement temperature of 100 ° C. Measurement was performed on five transformer samples, and evaluation was performed by calculating an average value of the measurement results. Table 3 shows the measurement results for the sintered body samples of Examples and Comparative Examples.

Evaluation 1
Table 1 shows the width C1 of the column forming part, the width C2 of the intermediate part, the width C3 of the prism forming part, and the width of the prism forming part of the sintered body main body shown in FIG. The minimum and maximum widths of C3 are shown. Table 1 also shows the dimensions of the 15 samples that were measured and their maximum, minimum, and average values.

  From Table 1, the width C1 of the column forming part, the width C2 of the intermediate part, and the width C3 of the prism forming part all fall within the range of 15.0 ± 0.3 mm, and the dimensional accuracy is high and good results are obtained. It was. In addition, regarding the width C3 of the prismatic portion forming the tapered portion, both the minimum width C3 (min.) And the maximum width C3 (max) of the width C3 are 15.0 ± 0.3 mm. Further, the difference between the average value of C3 (min.) And the average value of C3 (max) was 0.1 mm, and it was confirmed that high dimensional accuracy was obtained.

  Table 2 shows the width C1 of the columnar forming portion, the width C2 of the intermediate portion, and the prismatic portion forming portion of the sintered body shown in FIG. 4 (A) or FIG. 4 (C) of the sintered body samples of Examples and Comparative Examples. The measurement result of width C3 is shown. Table 2 shows the average value of the measurement results obtained for each of the 15 sintered body samples of the examples and comparative examples.

  From Table 2, the sintered body samples of the examples were all in the range of 15.0 ± 0.3 mm of the width C1 of the column forming part, the width C2 of the intermediate part and the width C3 of the prism forming part. In the sintered body sample of the comparative example, the width C3 of the prismatic portion forming portion was as thick as 15.46 mm, and was outside the range of 15.0 ± 0.3 mm. That is, the sintered body sample of the comparative example was inferior in dimensional accuracy of the width C3 of the prismatic portion.

  Therefore, as a ferrite molded body, a ferrite portion in which the width of the intermediate portion of the molded body is smaller than that of other portions and a tapered portion in which the width of the molded body is continuously reduced is formed. It was confirmed that by using the molded body, a sintered body having high dimensional accuracy over the entire sintered body can be obtained.

Evaluation 2
Table 3 shows the measurement results of the saturation magnetic flux density and the core loss of the sintered body samples of Examples and Comparative Examples. Table 3 shows the average values of the measurement results obtained for each of the five sintered body samples of Examples and Comparative Examples.

  From Table 3, it was confirmed that the sintered body sample of the example had substantially the same values of the saturation magnetic flux density and the core loss as the sintered body sample of the comparative example, which is a conventional example.

  Therefore, from the above results, according to the present invention, it is possible to obtain a sintered body having high dimensional accuracy over the entire sintered body without deteriorating electromagnetic characteristics such as saturation magnetic flux density and core loss. It could be confirmed.

1A is a front view of a ferrite molded body according to an embodiment of the present invention, FIG. 1B is a top view, FIG. 1C is a bottom view, and FIG. 1D is FIG. It is Id-Id sectional view taken on the line. 2A is a front view of a ferrite sintered body according to an embodiment of the present invention, FIG. 2B is a top view, FIG. 2C is a bottom view, and FIG. 2D is FIG. Is a sectional view taken along line IId-IId of FIG. 3A is a top view of a ferrite molded body according to an embodiment of the present invention, and FIGS. 3B and 3C are top views of a conventional ferrite molded body. 4A is a top view of a ferrite sintered body according to an embodiment of the present invention, and FIGS. 4B and 4C are top views of a conventional ferrite sintered body. FIG. 5 is a top view of a coil according to an embodiment of the present invention. 6A is a cross-sectional view of a compression mold according to an embodiment of the present invention, FIG. 6B is a cross-sectional view taken along the line VIb-VIb of FIG. 6A, and FIG. It is a top view of a concave shape. FIG. 7 is a graph showing the relationship between the density of the molded body and the shrinkage ratio of the sintered body by firing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ferrite molded body 2 ... Molded body main body 2a ... Tapered part 2b ... Recessed part 3 ... Square pillar 3a ... Tapered part 4 ... Column 5 ... Groove part 6a ... First end part 6b ... Second end part 6c ... Column base forming surface 6d ... Opposing surface 10 ... Ferrite sintered body 12 ... Sintered body 13 ... Square column 14 ... Column 15 ... Groove 17 ... Bobbin 18 ... Winding 19 ... Insulating resin 20 ... Mold for compression molding 22 ... Concavity for molding 24 ... For molding Convex mold 26 ... Powder filling recess 28 ... Frame mold 30 ... Middle mold 32 ... Lower punch 34 ... Upper punch 36 ... Groove forming protrusion 38 ... Intermediate forming protrusion 40 ... Taper forming protrusion

Claims (9)

Having a U-shape in which the first column base and the second column base extend in a substantially right angle direction from both ends of the rod-shaped molded body,
On the opposite surface of the molded body main body in the direction opposite to the column base forming surface, the length of the molded body main body extends from the first end that is one end to the vicinity of the second end that is the other end. A compression molded body in which grooves are formed along the direction,
The width of the intermediate part located between the column bases in the molded body is smaller than that of the other part, and from the first end direction toward the intermediate part, the width of the molded body A compression-molded body characterized in that a tapered portion having a continuously decreasing width is formed.   The compression molding body of Claim 1 in which the taper part is formed in the both sides of the width direction of the said molding body main body.   The compression molding body according to claim 1 or 2, wherein the tapered portion is also formed on a first column base extending from the first end portion. The first column base extending from the first end is a rectangular column base having a quadrangular cross section.
The compression molded body according to any one of claims 1 to 3, wherein the second column base extending from the second end portion is a columnar leg having a circular cross-sectional shape. The depth (D) of the groove is formed with a dimension of 25% or more of the width (W) of the molded body in the depth direction of the groove, and
The width (G) of the groove part is formed with a dimension of 25% or more of the width (C) of the part where the second column base in the molded body is formed. Compression molded body. The longitudinal direction along the groove length of the molded body of the groove (L _G) is formed by more than 50% of the length with respect to the distance (L1) between said first and second ends The compression molded body according to any one of claims 1 to 5. A method for producing the compression-molded body according to any one of claims 1 to 6,
Filling powder material into a powder filling recess which is a powder material filling portion; and
A method for producing a compression molded body, comprising: a step of pressing a molding convex mold into the powder filling concave section filled with the powder material, and applying a compression force to the powder material to perform compression molding.   The sintered compact obtained by baking the compression molding body in any one of Claims 1-6. A compression mold for producing the compression molded body according to any one of claims 1 to 6,
A molding concave mold having a powder filling recess for filling the powder material;
A molding convex mold that is pressed into the molding concave mold filled with a powder material and applies a compressive force to the powder material;
A compression molding die in which the powder filling recess has an intermediate portion forming projection that forms an intermediate portion of the molded body, and a tapered portion forming projection that forms the tapered portion.

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