JPH0744465U - Laver Press Mold - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the green compact from cracking during sintering in the furnace in the next step, eliminate the distorted bulge at the end of the green compact that causes cracking. In a rubber press mold including a tubular pressure-molded rubber and lids attached to both ends of the rubber, the inner diameters of both ends of the molded rubber are made smaller than the inner diameter of the body.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rubber press mold for forming a rod-shaped elongated green compact, and more particularly to a rubber press mold suitable for forming a high melting point metal such as tungsten having a relatively small green compact strength.

[0002]

[Prior art]

 Powder metallurgy techniques are commonly applied in the manufacture of refractory metal articles such as tungsten. That is, after pressing the powder into a rod shape, in order to increase the strength of the green compact and facilitate handling, preliminary sintering (pre-sintering) is performed at 1000 to 1500 ° C. in a hydrogen atmosphere, and further electric heating is performed. Main sintering. There are two types of press molding of tungsten powder: a mold press that fills a mold with powder and presses it, and a rubber press that fills and presses a rubber mold with powder. The rubber press has been adopted more and more to achieve this.

As shown in FIG. 4, a rubber press mold which has been generally used conventionally comprises a pressure-molded rubber 1 having a uniform inner diameter and lids 2 attached to both ends thereof. The powder is filled in the inside 3 of a cylindrical molded rubber and pressure-molded for a predetermined time to obtain a green compact. At this time, at the end of the molded rubber 1, the movement of the molded rubber 1 is restricted by the lid 2 as shown in FIG. 5, so that the green compact 4 obtained as shown in FIG. It becomes a connecting shape. When the green compact having the swollen end portion is subjected to sintering in the furnace in the next step, a load of the green compact is applied to the swollen portion, so that the green compact is cracked.

[0004]

[Problems to be solved by the device]

 The problem to be solved is that a bulge can be formed at the end of the green compact, which causes cracking of the green compact during sintering in the next process.

[0005]

[Means for Solving the Problems]

 In the rubber press mold of the present invention, the inner diameter of both ends of the cylindrical pressure-molded rubber is made smaller than the inner diameter of the body portion to eliminate the bulge at the end of the green compact.

[0006]

【Example】

 1 to 3 are sectional views showing an embodiment of the present invention. In these figures, 1 is a pressure-molded rubber, 2 is a lid attached to both ends of the pressure-molded rubber, 3 is the inside of a cylindrical pressure-molded rubber filled with powder, and d is a pressure-molded rubber. The inner diameter of the end of the rubber, D represents the inner diameter of the body of the pressure molding rubber. Here, FIG. 1 shows an example in which a tapered portion 5 is provided on the inner surface of the end portion to reduce the inner diameter of the end portion, and FIG. 2 shows an example in which a stepped portion 6 is provided on the inner surface of the end portion to reduce the inner diameter of the end portion. FIG. 3 is an end view taken along the line AA ′ in FIG.

In the rubber press mold of the present invention, as shown in FIGS. 1 to 3, since the inner diameter of the molding end is smaller than the inner diameter of the body, the movement of the molded rubber is restricted at the end. However, the end portion of the obtained green compact does not bulge from the body portion and cracks do not occur in the subsequent steps. The ratio of the inner diameter d of the end portion of the molded rubber to the inner diameter D of the body portion may be adjusted depending on the type of powder to be molded or the press conditions, and is not particularly limited, but at least the end of the molded rubber The inner diameter d of the part must be smaller than the diameter of the target green compact.

[0008]

[Effect of device]

 As described above, according to the rubber press mold of the present invention, the end portion of the obtained powder compact does not swell in a distorted shape, so that the occurrence of cracks in the next process can be prevented and the molding yield can be improved. Produce an effect.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing another embodiment of the present invention.

FIG. 3 is an end view taken along line A-A ′ in FIG.

FIG. 4 is a cross-sectional view of a rubber press mold that is conventionally generally used.

FIG. 5 is a cross-sectional view of an essential part showing the movement of a molded rubber when pressure molding is performed with a conventional mold.

FIG. 6 is an explanatory view of a main part of a green compact obtained by a conventional mold.

[Explanation of symbols]

 1 Pressure-molded rubber 2 Lid 3 Inside of pressure-molded rubber 5 Tapered part 6 Stepped part

Claims (1)

[Scope of utility model registration request] 1. A rubber press mold comprising a cylindrical pressure-molded rubber and lids attached to both ends of the molded rubber, wherein the inner diameter of both ends of the molded rubber is smaller than the inner diameter of the body portion. A rubber press mold featuring.