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Functional refractories made of different layered materials have long posed a challenge to manufacturers because of the manual labor involved. Either the different materials must be manually fitted together as finished components, or the molds must be manually filled before the refractories can be pressed into one piece (the technique primarily used with friction presses).
So why make layered refractories? When using elements such as sliding gates or nozzles, only the surface that comes in contact with the smelted steel must be composed of a highly wear-resistant-and therefore costly-material, while the basic structure of the element can be a less expensive material. In some cases, two different materials are used to provide different mechanical or thermal properties.
Recently, a new hydraulic press was developed to facilitate the production of compound sliding gates and nozzles. The machine fills the molds and presses the product in a single working cycle, which makes the process more economical and highly reproducible.
Press OperationThe most common damage that occurs during the lifetime of a compound sliding gate includes bore enlargement, bore edge damage and sliding surface damage (see Figure 1). Taking this into account, a typical sliding gate design might be as shown in Figure 2.
Further AdvancesCompared to a conventional pressing process, the new press increases the total cycle time by approximately 10 seconds due to the second charging process and increases the machine cost by about 12%. However, this is far less than the time and costs required to complete the fitting and/or filling processes manually.
Further advances are being developed for the production of sliding gates and nozzles, as well as for other shapes where the use of at least two different materials is useful. Technologies are also under way that will allow the modification of existing presses for co-pressing operations.
For more information about the new hydraulic press, contact:
LAEIS GmbH at Am Scheerleck 7, 6868 Wecker, Luxembourg
Phone: (352) 27612-0
Fax (352) 27612-109