Discussion on combined die for pressing molybdenum crucible
Molybdenum is a kind of high temperature resistant material. It is widely used in modern industry, but its price is high. In order to reduce the cost, powder metallurgy production method is widely used to manufacture molybdenum products. Molybdenum crucible is one of them. This paper describes the design of pressing combination die for molybdenum crucible.
Features of parts and die design
It is characterized by that the part is composed of two parts: the wall shell and the lower cone, and the ratio of height to thickness of the wall cylinder is close to 8. It is not easy to ensure the uniform density of the medium pressure billet by manual pressing, and it is easy to produce cracks. After several process adjustments in production, the following ideal design scheme of manual combined die was found.
The mold design principle is as follows:
The lower cone part of the molybdenum crucible is formed by the lower die punch, the base and the core rod. In order to facilitate the demoulding of the lower cone part of the molybdenum crucible from the base, the base is composed of three vertically divided parts; the female die, the upper die punch and the core rod forming the wall cylinder part of the molybdenum crucible.
The powder loading is divided into two times. After the powder is evenly scraped with a special scraper, the core rod is installed for the second powder loading. Due to the friction between powders and the friction between powder and mold, pressure loss will occur during pressing. In order to improve the density of the lower cone part of the compact and make the density of the compact uniform, two-way pressing is adopted. After the first pressing, remove the mold pad for the second pressing. At this time, since the base is composed of three pieces, it is easy to take the blank out of the base by hand.
