Method for preventing tin bronze bush centrifugal casting from producing penetrable pores

Abstract

The invention relates to a method for preventing a tin bronze bush centrifugal casting from producing penetrable pores. The method is characterized by reducing the steaming of crystallization water on the inner surface of a casting mold and free water by adopting a mold roasting temperature higher than that given in the manual; adopting a water base spraying paint prepared from a superfine composite refractory aggregate with a steaming quantity lower than or equal to 16mL / g as a casting mold paint; adopting a pouring system combining a uniform distribution type long pour pipe and a pull plug tank bag; and on the basis of the specifications of the manual, appropriately reducing the pouring temperature. For a large tin bronze bush centrifugal casting, casting parameters and centrifugal casting technological parameters are more complicated, and the parameters have mutually restraint relations. The method has the biggest difference from the prior art that the casting mold parameters, the casting parameters, the technological parameters, and the like are counted as a whole, and the matching relations among various parameters are more emphasized, which can greatly reduce the occurrence probability of the penetrable pores, lighten the influence degree of the penetrable pores and improve the product quality.

Description

technical field [0001] The invention relates to the direction of centrifugal casting of copper alloys in the field of casting technology, in particular to a method for preventing penetrating pores from being produced in centrifugal castings of tin bronze bushings. Background technique [0002] For tin bronze bushing castings, when the length / thickness > 25, the use of sand casting will cause feeding difficulties due to insufficient feeding channels, and centrifugal casting is often used. Among copper alloys, centrifugal casting of large and medium-sized tin bronze bushes is more difficult. For tin bronze bushes, the larger the value of length / outer diameter, the easier it is to produce penetrating pores. In the prior art, it is often used to drill a large number of vent holes on the mold wall to facilitate the discharge of gas on the inner surface of the mold during the casting process. Although this method has certain effects, the disadvantage is that it increases the co...

AI Technical Summary

Problems solved by technology

In the prior art, it is often used to drill a large number of vent holes on the mold wall to facilitate the discharge of gas on the inner surface of the mold during the casting process. Although this method has certain effects, the disadvantage is that it increases the cost of casting. On the other hand, it increases the difficulty of operation. If the sand filling of the vent hole is not good or missed (especially for the slender mold), the alloy liquid will drill into the vent hole during the pouring process, which will affect the quality of the casting. Demoulding causes great difficulty

Some manufacturers have also adopted the form of outer jacket + graphite inner sleeve to prevent the generation of penetrating trumpet-shaped pores, but the graphite type has high manufacturing costs and short service life, and is only suitable for medium and small tin bronze bushings , cannot be used for large tin bronze bushing castings

According to the mold drying process given in the manual ("Special Casting Handbook" compilation group Special Casting Handbook [M]. Beijing: Mechanical Industry Press, 1978. the same below), the drying temperature is 200 ° C ~ 300 ° C, The working temperature of the casting mold is 40℃~90℃, the pouring temperature is 1100℃~1150℃ (ZCuSn10Zn2), 1050℃~1100℃ (ZCuSn10P1), etc. For tin bronze bushings with relatively large length / outer diameter, it is easy to cause wear and tear. Permeable stomata