JP3078356B2 - Powder pressing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder pressing method for pressing a powder of ceramics or the like to obtain a compact.

[0002]

2. Description of the Related Art Generally, a method of manufacturing a ceramic product is as follows.
It comprises the steps of mixing the raw material powders, forming them into a predetermined shape, and then firing. In the molding step, a powder pressure molding method is generally used because mass production is possible at low cost. .

[0003] An apparatus for performing such powder pressure molding is, for example, as shown in FIGS.
In addition, the space formed by the lower punches 12 and 13 is filled with the raw material powder 15 from the feeder 14 and pressed by the upper punch 11. As shown in FIG. 2, an operation time chart of the powder press molding apparatus, the upper punch 11 moves up and down in a sine curve, and after pressing the raw material powder at the bottom dead center, the upper punch 11 Dice 10 as it goes up
As a result, the compact 16 comes out on the upper surface of the die 10 and is taken out by the movement of the feeder 14.

[0004]

However, in the conventional powder pressing method, it is difficult to uniformly fill the raw material powder 15, and the upper punch 11 is pressed at only one point at the bottom dead center. For this reason, the pressure cannot be transmitted to the details of the molded body 16, so that there is a problem that only a relatively simple shape can be molded. For example, as shown in FIG. 4, if a molded body 16 having a small thickness and a complicated shape is to be obtained, the density is not uniform, and cracks are likely to occur at the corners of the molded body 16. I couldn't. Therefore, in order to obtain a product having such a complicated shape, it is necessary to perform a cutting process or take a special molding method, and in any case, mass production could not be performed at low cost.

[0005]

Accordingly, the present invention provides a stopping time of 2 to 10 seconds between the time of filling the raw material powder in the powder pressing step and the time of removing the formed body after pressing. It is provided. In this way, by stopping at the time of filling the raw material, the filling of the raw material can be made uniform, and by stopping after pressing, the transmission of pressure can be made uniform, and the friction between the compact and the die at the time of taking out can be improved. And the occurrence of cracks can be prevented.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

As shown in FIG. 3, the apparatus used in the molding method of the present invention comprises a die 10, an upper punch 11 and a lower punch 1.
After the raw material powder 15 is filled into the die 10 from the feeder 14 and then pressed by the upper punch 11, a molded body 16 is obtained.

The operation of each part will be described with reference to the time chart of FIG. First, as a filling step, the feeder 14 moves to the position shown in FIG.
Raw material powder 1 is placed in the space formed by
Fill 4 Then, a first stop time is provided in this state (part A in FIG. 1). By stopping in a state in which the raw material powder 15 is filled, the filling of the raw material powder 15 can be made uniform. Thereafter, the feeder 14 returns to the original position, and the upper punch 11 descends, so that the raw material powder 15 is pressed.

After the upper punch 11 has passed through the bottom dead center, the upper punch 11 is raised and the die 10 is lowered as shown in FIG. A second stop time is provided between the time when the upper punch 11 passes through the bottom dead center and the time when the molded body 16 is removed from the die 10 (part B in FIG. 1). By stopping at this point, the pressure transmission to the compact 16 is transmitted to the details, and the raw material is completely crushed.
The friction between the die 6 and the die 10 can be reduced, and the occurrence of cracks in the molded body 16 during removal can be prevented. Thereafter, when the upper punch 11 is further raised and the die 10 is completely lowered, the molded body 16 is extruded by the movement of the feeder 14, and the raw material powder 15 is filled.

Note that all the operations of the molding apparatus are stopped during the above-mentioned stop time. By incorporating a timer or the like into the molding apparatus, the molding apparatus can be freely stopped for a predetermined time. Furthermore, since the effect is not particularly high even if the stop time is set to 10 seconds or more, the stop time is preferably 10 seconds or less in order to perform molding efficiently. On the other hand, if the stop time is shorter than 2 seconds, the above effect is not obtained. Therefore, the stop time is preferably 2 seconds or more.

As described above, according to the present invention, the raw material powder 1
1 (part A in FIG. 1) and after pressing
By providing a stop time until the material 6 is taken out (part B in FIG. 1), the filling of the raw material powder 15 can be made uniform, the pressure transmission to the compact 16 can be made uniform, and the compact 16 can be taken out. Cracks can be prevented by reducing friction at the time. Therefore, as shown in FIG. 4, it is possible to mold even a molded body 16 having a complicated shape such as a thin cylindrical body having a small thickness.

Further, in the above embodiment, an example is described in which a forming apparatus including one upper punch 11 and two lower punches 12 and 13 is used in FIG. The shape can be freely changed according to the shape of the desired molded body. Further, in the above embodiment, the lower punch is fixed and the upper punch is used for pressurizing. However, it is also possible to press the upper and lower punches or only the lower punch. Further, it goes without saying that the present invention can be applied not only to pressure molding of ceramics but also to pressure molding of various powders.

Experimental Example Here, a ceramic molded body 16 having the shape shown in FIG.
In order to obtain, a molding was performed by the molding method of the present invention shown in FIG. 1 and the conventional molding method (comparative example) shown in FIG. The size of the ceramic molded body 16 is 8 mm in length H and 60 mm in diameter φ.
Alumina ceramics having a thickness of 1 mm and a thickness t of 1 mm and an Al ₂ O ₃ content of 94% was used as the raw material powder 15. In the molding methods of the present invention and the comparative example, the molding cycle was set to 4 times / minute. The two stop times in the molding method of the present invention were all 5 seconds.

A plurality of moldings were performed by the respective molding methods, and the weight of the obtained molded body 16 was measured. The results were as shown in FIG. 5 (the present invention) and FIG. 6 (comparative example). Originally, the weight of the molded body 16 had to fall within the range of 16000 ± 25 mg, but in the comparative example shown in FIG. 6, it hardly fell within this range, and the dispersion was extremely large. Moreover, cracks occurred in all of the obtained molded bodies 16. In contrast, in the embodiment of the present invention shown in FIG.
It was found that all the weights of the compacts were within the required range, and that no cracks occurred in all the compacts 16, so that stable compaction could be performed.

[0015]

As described above, according to the present invention, when filling the raw material powder in the powder pressing step and before taking out the pressed body after pressing by the upper and lower punches, 2 to 10 respectively.
By providing a stop time of 2 seconds, uniform filling of the raw material, uniform pressure transmission to the compact, and reduction of friction between the compact and the die prevent cracks when removing the compact. Therefore, even a molded article having a complicated shape can be molded stably. Therefore, it is possible to mass-produce a ceramic product having a complicated shape with high quality and at low cost by powder pressure molding.

[Brief description of the drawings]

FIG. 1 is a time chart showing the operation of each part in the powder press molding method of the present invention.

FIG. 2 is a time chart showing the operation of each part in a conventional powder pressing method.

FIGS. 3A and 3B are cross-sectional views each showing a powder pressure molding apparatus.

FIGS. 4A, 4B, and 4C are cross-sectional views each showing a ceramic molded body having a complicated shape.

FIG. 5 is a graph showing a change in weight of a compact according to the powder pressing method of the present invention.

FIG. 6 is a graph showing a change in weight of a compact according to a conventional powder pressing method.

[Explanation of symbols]

 10 Die 11 Upper punch 12, 13 Lower punch 14 Feeder 15 Raw material powder 16 Molded body

Claims (1)

(57) [Claims] In a molding method in which a raw material powder is filled in a die and pressurized with upper and lower punches, two to one to one are used during filling of the raw material powder and before the molded body is taken out after pressing.
A powder pressure molding method characterized by providing a molding apparatus stop time of 0 second.