JP2001009596A - Powder compression molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method, for partially adjusting the molding density with good raw material yielding without splitting a lower punch. SOLUTION: In powder compression molding, a notch part is installed to one part of an upper end face of a cylinder and/or a core rod. A lower punch 3 is inserted in a cylinder 1, and the raw material powder is charged in a spacing, inclusive of the notch part, formed by the cylinder 1 or the core rod 2. After the cylinder 1 is pushed up or the lower punch 3 is lowered so as to charge the powder in the compression part, an upper punch 6 is inserted for performing compression molding so as to adjust partial density difference of a molding material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferrite core,
The present invention relates to a powder compression molding technique for ceramics, carbide tools, and the like.

[0002]

2. Description of the Related Art In the case of powder compression molding of a ferrite core or the like, a raw material powder is filled in a metal mold, and the raw material powder in the metal mold is compressed by an upper punch and a lower punch. For example, when the cross section of only one side 52 is an octagon and the other side 53 is a quadrangle like a square-shaped ferrite core 51 shown in FIG. 5, the raw material may be simply cut and filled by the raw material supply feeder. However, the molding density of the portion 52 having an octagonal cross section becomes higher than that of the other portions, and there is a problem that a difference in shrinkage occurs partially when fired, resulting in a trapezoidal deformation as shown in FIG. As a countermeasure, the lower punch was divided into portions having different densities, the stroke length of the lower punch was changed, and a mold was designed so that the density became uniform. This molding method is shown in FIG. In FIG. 7, the lower punch 71 is replaced with another lower punch 72.
It is set at a higher position to adjust the filling amount of the raw material powder 73 to be filled. In FIG. 7, reference numeral 74 denotes a mandrel, 7
5 indicates a cylinder, and 76 indicates an upper punch.

In Japanese Unexamined Patent Publication No. Hei 6-246724, as shown in FIG. 8, in a method of forming a sun-shaped ferrite core, a cylinder 85 at an upper end surface of two mandrels 81 is used.
The chamfered dimension of the twill portion on the center direction side was made large, and the raw material powder 83 was allowed to escape into the upper punch 82 by the chamfered portion at the time of press molding to adjust the molding density. In FIG. 8, reference numeral 84 denotes a lower punch. The purpose of this is as shown in FIG.
Is formed in a concave shape, and the molding density of the middle leg 93 is adjusted to be lower than that of the outer leg 94. As a result, as shown in FIG. 10, when the cut surface (butting surface) of the E-shaped ferrite core 95 obtained by cutting the sun-shaped ferrite core 91 is ground, the seating is good with respect to the grinding platen. This has the effect that stable processing can be performed.

[0004]

However, this 2
The two prior arts have the following problems.
First, as shown in FIG. 7, in the lower punch dividing method, since the lower punch is complicated, the lower punch is apt to be damaged, it takes a lot of man-hours to attach, and in the molded body, burrs are formed at the joints of the divided punches. There is a disadvantage that minute cracks are easily generated from the joint.

[0005] In the case of JP-A-6-246724, a part of the raw material powder, which is to be used for the compact, is discharged to the outside of the cylinder hole. Further, when the tip surface of the upper punch is concavely curved, when the upper punch is inserted into the cylinder, the curved portion holds the raw material powder, and the raw material powder is not discharged more efficiently than the chamfered portion. was there. Actually, even if this method is applied to the above-mentioned square-shaped ferrite core, there is almost no effect of adjusting the molding density, and after firing, it has been transformed into a trapezoid.

An object of the present invention is to provide a molding method that solves the above-mentioned problems.

[0007]

According to the present invention, in a powder compression molding, a notch is provided in a part of an upper end surface of a cylinder and / or a mandrel, and the raw material powder filled in the notch is compressed. , Followed by compression molding, and adjusting the partial density difference of the molded body.

[0008] The present invention also relates to a method in which a lower punch is inserted into a cylinder, a space formed by the cylinder and the lower punch is filled with raw material powder, an upper punch is inserted into the cylinder, compressed, and In the powder compression molding method for molding powder, a notch is provided at a part of the upper end surface of the cylinder, and the raw material powder filled in the notch is compressed by pushing up the cylinder or lowering the lower punch. The powder compression molding method is characterized in that the upper punch is inserted into the portion, the upper punch is inserted into the portion, and compression molding is performed to adjust a partial density difference of the compact.

Further, according to the present invention, a mandrel and a lower punch are inserted into a cylinder, a raw material powder is filled in a space formed by the cylinder, the mandrel and the lower punch, and an upper punch is inserted into the cylinder and compressed. In the powder compression molding method for molding the raw material powder, a cutout portion is provided in a part of the upper end surface of the cylinder and / or the mandrel, and the raw material powder filled in the cutout portion is provided with the tube and the mandrel. A powder compression molding method characterized in that, after filling in a compression portion by pushing up or lowering the lower punch, the upper punch is inserted, compression molded, and a partial density difference of a compact is adjusted.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention are described in
In contrast to JP-A-246724, it is not necessary to discharge the unnecessary portion of the raw material powder but to refill the necessary portion with the raw material powder. The present invention is a powder compression molding method, at the time of pressure molding, the raw material supply feeder recedes,
Before the upper punch is inserted into the cylinder, a press mechanism that pushes up only the cylinder and the mandrel, or lowers only the lower punch,
A molding method characterized by adjusting a partial density difference of a compact by filling a raw material powder into an arbitrary portion by using a cutout portion on an upper end surface of a cylinder or a mandrel.

An embodiment of the present invention will be described using the above-mentioned square-shaped ferrite core as a shape example. 1 and 2 are cross-sectional views showing a molding process according to one embodiment of the present invention. In this embodiment, a mandrel 2 and a lower punch 3 are inserted into a cylinder 1, and a space formed by the cylinder 1, the mandrel 2 and the lower punch 3 is filled with raw material powder 4. This raw material powder 4
Is filled by supplying the raw material powder 4 to the space by sliding the raw material supply feeder on the upper surface of the cylinder 1 and scraping it off. In the related art, a chamfer 5 is formed on the upper end surfaces of the cylinder 1 and the mandrel 2 at the portion where the molding density is low, and the raw material powder 4 is also filled in the chamfer 5.

Next, as shown in FIG. 2, by pushing up the cylinder 1 and the mandrel 2 or lowering the lower punch 3, the raw material powder 4 filled in the chamfer 5 is filled in the compression section.
This makes it possible to adjust the molding density by increasing the amount of the raw material powder 4 in the portion where the molding density was conventionally low. Then, the upper punch 6 is inserted, and the raw material powder 4 is compression-molded together with the lower punch 3 to form a compact.

In the above-described embodiment, the chamfer is described as an example of the notch on the upper end surface of the cylinder 1 or the mandrel 2. However, the present invention is not limited to this. For example, a notch is provided in a mortar shape, or the cylinder has a U-shape. A notch of a mold may be provided, and the raw material powder 12 may be pushed out by the driving device 11 as shown in FIG. In this example, the purpose is to correct the molding density difference, but the present invention is not limited to this. The difference in molding density can be arbitrarily adjusted. In addition, the shape of the molded body is not limited to a square shape or a sun shape. The present invention can be widely used not only for molding ferrite cores but also for fields requiring powder compression molding techniques such as ceramics and carbide tools. Further, the present invention can be used even in a structure without a mandrel, that is, in the case of molding from an upper punch, a lower punch and a cylinder.

[0014]

EXAMPLE As a specific example, a ferrite core having a long side (A side) of 26 mm, a short side (perpendicular to A) 18 mm and a thickness of 5 mm as shown in FIG. 5 was formed. FIG. 3 shows a chamfered portion on the upper end surface of the mold cylinder and the mandrel. In FIG. 3, the hatched portion indicates the upper end surface. The chamfer dimension takes into account the molding density difference of this shape,
It was cut into a 3.0 mm width. The reason why the chamfered surfaces on both sides of the mandrel are triangular is in consideration of the required amount and location of the raw material to be filled. Using this mold, Figure 1
After the raw material was supplied by the raw material supply feeder as described above, the press mechanism was used to push up only the cylinder and the mandrel before the upper punch was inserted into the cylinder, to drop the raw material in the chamfered part into the cylindrical hole, and compression-molded. . The molded body was fired, and the dimensional difference between the five A1 and A2 pieces was measured.

Next, as a comparative example, the upper end surfaces of the mold cylinder and the mandrel were not chamfered, but were produced under the same conditions as above, and the dimensional difference of five pieces A1 and A2 was measured. A of the square-shaped ferrite core obtained in the present invention and the comparative example
Table 1 shows the dimensional difference between A1 and A2.

[0016]

[Table 1]

As shown in Table 1, the dimensional difference after firing of the molded article of the example of the present invention was about 10% smaller than that of the comparative example.
%, Indicating that the function of adjusting the molding density worked effectively.

According to the molding method of this embodiment, the molding density could be effectively adjusted without dividing the lower punch of the mold and discharging some of the raw material powder out of the mold cylinder hole.

[0019]

According to the present invention, the lower punch can be divided without being divided, thereby reducing the number of mold breakage and the number of mounting steps, and reducing the occurrence of burrs and cracks in the molded product. It is possible to provide a molding method capable of adjusting the molding density with a good raw material yield.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a molding step according to one embodiment of the present invention.

FIG. 2 is an explanatory view of a molding step according to one embodiment of the present invention.

FIG. 3 is a schematic view of a cylinder and a mandrel according to one embodiment of the present invention.

FIG. 4 is an explanatory view of a molding step of another embodiment according to the present invention.

FIG. 5 is a perspective view of a ferrite core according to the present invention.

FIG. 6 is a perspective view of a deformed ferrite core of a conventional example.

FIG. 7 is an explanatory view of a step of forming a square-shaped ferrite core of a conventional example.

FIG. 8 is an explanatory diagram of a forming process of a conventional day-shaped ferrite core.

FIG. 9 is a schematic view of a conventional day-shaped ferrite core.

FIG. 10 is a schematic view of a conventional E-type ferrite core.

[Explanation of symbols]

 1 cylinder 2 mandrel 3 lower punch 4 ferrite raw material powder 5 chamfer 6 upper punch

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Claims (3)

[Claims] In a powder compression molding, a notch is provided in a part of an upper end surface of a cylinder and / or a mandrel, and after the raw material powder filled in the notch is filled in a compression part, compression molding is performed. A powder compression molding method characterized by adjusting a partial density difference of a compact. 2. Inserting a lower punch into a cylinder, filling a space formed by the cylinder and the lower punch with raw material powder, inserting an upper punch into the cylinder, compressing the raw material powder, and molding the raw material powder. In the powder compression molding method, a notch is provided in a part of the upper end surface of the cylinder, and the raw material powder filled in the notch is filled in the compression section by pushing up the cylinder or lowering the lower punch. After that, the upper punch is inserted, compression-molded, and a partial density difference of the compact is adjusted. 3. Inserting a mandrel and a lower punch into a tube, filling a raw material powder into a space formed by the tube, the mandrel and the lower punch, inserting an upper punch into the tube, compressing, In the powder compression molding method for molding a raw material powder, a notch is provided in a part of the upper end surface of the cylinder and / or the mandrel, and the raw material powder filled in the notch is pushed up the cylinder and the mandrel or A powder compression molding method, characterized in that the lower punch is lowered to fill the compression section, and then the upper punch is inserted, compression molded, and a partial density difference of the compact is adjusted.