JPH06277770A - Press die made of ceramics - Google Patents

Abstract

PURPOSE:To make the wear little even in a press forming of the hard inorganic powder, to prolong the life of a die, to prevent the generation of the corrosion on a contact part even in a press forming of the corrosive chemical powder, to eliminate the residual subject left inside the die and to eliminate the fear of the contamination of an article. CONSTITUTION:At least, an internal surface of a metal sleeve 1, pressing surfaces of an upper punch 3 and a lower punch 5 of the metal and sliding surfaces with the sleeve are formed of the ceramics, a ceramic sleeve 2 is joined on the internal surface of the metal sleeve 2 with the shrink fit, and ceramics heads 7, 8 are joined on the pressing surfaces of the upper punch 3 and the lower punch 5 made of the metal with the shrink fit, and the surface of the sliding surface is ground, at least, to Ra 0.4mum roughness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a press die sleeve and upper and lower punch main parts made of ceramics.
The present invention relates to a ceramic press die having excellent wear resistance and corrosion resistance.

[0002]

2. Description of the Related Art Press dies used for compressing ceramic materials, ceramic materials, etc. and performing forming, drawing, bending, etc., are the inner surface of the die (sleeve) and the inner surface of the die of the upper and lower punches. The sliding parts and the main parts such as the press surfaces of the upper and lower punches are subject to large wear and tear due to wear and corrosion.For example, when pressing ceramic powder, these parts are worn by hard ceramic powder. There is a problem of doing. Also, when a chemical powder such as a bactericide is press-molded, there is a problem that the above-mentioned portion is corroded by the chemical.

Therefore, in order to solve these problems, various measures have been studied so far. For example, the sliding parts of the sleeve, the upper and lower punches, and the press surface are covered with high wear resistance. As described in Japanese Utility Model Laid-Open No. 61-190321, the upper and lower punches and the main body of the sleeve and the like are made of a metal material such as cast iron, and the sleeve and the upper and lower punches are made. A method has been proposed in which the main parts such as the sliding part and the pressing surface are formed of an inorganic material containing alumina as a main component.

[0004]

However, even in the case where the above-mentioned sleeves, the sliding portions of the upper and lower punches, and the main portions such as the pressing surface are covered with high hardness special steel,
There are problems such as wear of the molded product over time, contamination of the molded product, loss of the molded powder due to expansion of the gap between sliding parts, product size variation, and corrosion resistance. Further, in the method of Japanese Utility Model Laid-Open No. 61-190321, since the material used is alumina and has a quadrangular cross section, it has low toughness, is easily worn or chipped at the sliding portion, and has low strength, so it is damaged by the press pressure. However, there is a problem that the stress is concentrated on the corners and cracks are easily generated.

As a result of earnest research in view of the above-mentioned conventional problems, the present inventor has made the sleeve a cylindrical cross-sectional shape, and at the same time, Si is formed in the sleeve and the upper and lower punches.
₃ N ₄ , sialon, PSZ, SiC, Al ₂ O ₃ (alumina), preferably Si ₃ N ₄ , sialon, PSZ
The inventors have found that a press die having excellent performance can be obtained by forming a ceramic layer that is a combination of one or two of the above, and has reached the present invention. Furthermore, the present inventor has found that even if the cross-sectional shape of the sleeve is square, the same performance can be obtained with alumina by forming the sleeve in one piece instead of integrally forming the sleeve.

[0006]

That is, according to the present invention, there is provided a press die comprising a sleeve and an upper punch and a lower punch that slide on the inner surface of the sleeve to compress the contents. The inner surface of the metal sleeve, the pressing surfaces of the metal upper punch and the lower punch, and the sliding surface of the metal upper punch and the metal lower punch with the sleeve are made of ceramics, and the inner surface of the metal sleeve is ceramic. The sleeves are fastened with an interference fit, and the ceramic heads are fastened with the press faces of the metal upper and lower punches with an interference fit, and the surface roughness of the sliding surface is ground to at least Ra 0.4 μm. A ceramic press die, which is characterized in that it is provided.

In the present invention, it is preferable that the sleeve has a cylindrical cross-sectional shape. However, even if the sleeve has a quadrangular shape, the same performance can be obtained by forming the sleeve in four sides instead of integrally forming the sleeve. .

[0008]

In the press die of the present invention, the inner surface of the sleeve and the sliding portions of the upper and lower punches on the inner surface of the sleeve, and the metal bases on the pressing surfaces of the upper and lower punches are tightened. By forming the ceramic layer by machining, the ceramic layer can be firmly and stably fastened, and the manufacturing cost can be reduced. If the sleeve to be fastened to the inside of the die has a cylindrical or quadrangular cross-sectional shape, the four sides are divided into two parts, and even if a ceramic layer is formed on the inner surface of the sleeve, it is as if it were a conventional square sleeve. The stress is not concentrated on the corners of the sleeve, and cracks do not occur.

Further, since the press die of the present invention is less likely to be worn during press forming of a hard inorganic powder such as a ceramic material, the life of the die is extended and residual substances remain in the die. There is no risk of contamination of the molded product. Further, it is possible to prevent galling of the die due to sliding of the sleeve and the punch, which enables smooth operation.
In addition, the conventional metal material requires a surface roughness Ra of 0.1 μm or less to prevent slipping and galling.
Although there still occurred a problem, in the present invention, R
Even if it is roughened to 0.4 μm, no galling occurs and it slides smoothly. If the surface roughness Ra of the sliding surface exceeds 0.4 μm, the ceramics rub against each other, resulting in severe wear and chipping in severe cases. In the case of ceramics, even if the surface roughness of the sliding surface is rough, smooth sliding is affected by the fact that ceramics have a smaller friction coefficient than metal.

The above-mentioned interference fit means, for example, when a sleeve is fixed on a metal shaft, there is an interference between the outer diameter of the shaft and the inner diameter of the sleeve.
This is a processing method also called shrinkage fitting. An interference fit is a method of fastening members to each other utilizing heat shrinkage, which includes shrink fit and cooling fit.

The type of ceramics used in the present invention is not particularly limited, but silicon nitride (Si ₃ N ₄ ), sialon, partially stabilized zirconia (PSZ), SiC, alumina (Al ₂ O _3). ) And the like having excellent abrasion resistance and corrosion resistance are preferable, and one or a combination of Si ₃ N ₄ , sialon and PSZ is more preferable. In addition, especially as a sleeve, S
i ₃ N ₄ , sialon and PSZ are preferred.

In the present invention, it is preferable to chamfer the ceramic corners on the upper and lower surfaces of the punch. This chamfering process can prevent chipping of ceramics,
Desirably, it is C0.1-0.2.

[0013]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples. (Embodiment 1) FIG. 1 is a schematic sectional view showing an embodiment of a ceramic press die of the present invention. 50 mm inner diameter of die
m alloy tool steel SKD material sleeve 1 has an inner surface with a thickness of 1
Fit a partially stabilized zirconia sleeve 2 of 5 mm with a fitting tolerance of H7 (+30 μm, 0) / r6 (+62 μm, +
43 μm) and tightened by an interference fit process. Further, in the concave portion 4 of the pressing surface of the upper punch 3 made of the alloy tool steel SKD material and the concave portion 6 of the pressing surface of the lower punch 5 made of the alloy tool steel SKD material, the head portion φ50 mm and the interference fit portion φ40.
mm, partially stabilized zirconia heads 7, 8 convex portions 9,
10 to fit tolerance H7 (+25 μm, 0), p6 (+
42 μm, +26 μm) and tightened by interference fit.

Next, using a ceramic press die having the above-mentioned structure, various powders were used as forming raw materials, and pressure was applied by upper and lower punches at a pressure of 1200 kg / cm ² to produce a molded product. Table 1 shows the usage of the ceramic mold in that case.

(Comparative Example 1) As in Example 1 except that the ceramic member was not fastened to the inner surface of the sleeve made of alloy tool steel SKD material, the sliding portion with the inner surface of the sleeve of the upper and lower punches, and the pressing surface. Using a press die having the same structure, alumina powder and chlorine-based germicide powder were used as molding raw materials in Example 1.
Pressure molding was performed under the same pressure conditions as above. The results are shown in Table 1.

[0016]

[Table 1]

(Embodiment 2) Table 2 shows the results of investigating the occurrence of galling by changing the surface roughness Ra of the sliding portion in the ceramic press die.

[0018]

[Table 2]

[0019]

As described above, according to the ceramic press mold of the present invention, wear of the hard inorganic powder is less likely to occur during press molding, the mold life is extended, and the corrosive chemical powder Even during press molding, the contact portion does not corrode, no residual substance remains in the mold, and there is no risk of contamination of the molded product. Further, there is an advantage that it is possible to prevent galling of the die due to the sliding movement of the sleeve and the upper and lower punches, which enables smooth operation. Also, if the sleeve has a cylindrical cross-section, or if it has a quadrangular shape and the four sides are divided, the ceramic layer formed on the inner surface of the sleeve is stressed at the corners of the sleeve like a conventional rectangular sleeve. Are not concentrated and cracks do not occur.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a ceramic press die of the present invention.

[Explanation of symbols]

 1 Sleeve made of alloy tool steel SKD material 2 Sleeve made of ceramics (PSZ) 3 Upper punch made of alloy tool steel SKD material 4 Recess of press surface 5 Lower punch made of alloy tool steel SKD material 6 Recess of press surface 7, 8 Partial stability Zirconia oxide head 9,10 Convex part

Claims (1)

[Claims] 1. A press die comprising a sleeve and an upper punch and a lower punch that slide on the inner surface of the sleeve to compress the contents, wherein at least the inner surface of the metal sleeve, the metal upper punch and the lower punch. The pressing surface of the punch and the sliding surface of the metal upper punch and the metal lower punch with the sleeve are made of ceramics, and the ceramic sleeve is fastened to the inner surface of the metal sleeve by an interference fit. A ceramic press die, characterized in that a ceramic head is fastened to the press surfaces of the upper punch and the lower punch by interference fit, and the sliding surface is ground to a roughness of at least Ra 0.4 μm. Type.