Abstract: A sand core pattern (11) for producing a one-piece cast wheel (10) having a radially inner shell (12), a radially outer blade support (13), and a plurality of angled blades (14) extending in a spaced, annular array (22). The pattern includes a plurality of similar segments (15), each having an inner end portion (18) defining a portion of the profile of the shell, and an outer end portion (21) defining the profile of the blade. The segments are supported in annular array about a mandrel (25) and are circumscribed by a split ring (26) defining the pattern for the outer blade support portion of the wheel (10). The inner portions of the segments are defined by angled side surfaces (16,17) which, in alternate ones of the segments in the annular array, converge and diverge toward the center of the array.

Abstract: A flexible pattern for forming casting molds can be withdrawn from the mold, without need of partitioning and reassembling, and includes a pattern member made by coupling a plurality of outer plates, having a configuration corresponding to a desired predesigned casting, by means of joint members, which are freely removable, and an airtight bag installed in the inner periphery of the pattern member. The pattern member and the airtight bag are united in a single body.