Method and apparatus for forming centrifugal fan housings

Claim 1

In an apparatus for fabricating a centrifugal fan housing from a pair of side plates and an elongated band having walls defining two longitudinally extending grooves, one adjacent each of two opposite side edges thereof, each of said two grooves being adapted to receive a portion of the periphery of one of said side plates, which apparatus includes a frame, a separate means for each of said side plates mounted on said frame for clinching the groove-defining walls of said band to the periphery of a side plate while urging the side plate into the groove, said separate means each including a pair of clinch rolls adapted to engage the groove-defining walls along one edge of said band and to clinch said walls to the peripheral portion of a side plate located in the groove while feeding the band in a predetermined direction, one of said clinch rolls being stationary in that it is mounted for rotation about a fixed axis and the other of said clinch rolls being mounted for rotation about an axis parallel to the axis of rotation of said one roll but being movable toward and away from said one roll, means for moving said movable clinch roll in the direction of said stationary clinch roll to effect pressure engagement between said clinch rolls and the groovedefining walls of said band and for moving said movable clinch roll away from said stationary clinch roll to provide sufficient space therebetween to facilitate insertion between said clinch rolls of a groove-defining portion of the band, means coupled to one or the other of said clinch rolls to effect driving rotation thereof, a pair of pressure rolls mounted adjacent said clinch rolls adapted to receive therebetween and to contact opposite surfaces of a housing side wall disposed in the groove of the portion of the band being clinched by said clinch rolls and for exerting forces on said side wall to urge the peripheral edges thereof into said groove and to guide said side plate for turning movement as the band is progressively crimped to the side plate, said pressure rolls being mounted for rotation about parallel axes lying in a plane transverse to the plane defined by the axes of said clinch rolls, the improvement which comprises A. means mounting that pressure roll which is in closest proximity to said stationary clinch roll in a stationary manner also for rotation about an axis which is fixed during the use of said apparatus, B. means mounting the other of said pressure rolls so as to render it movable toward and away from said stationary pressure roll, C. and means for moving said movable pressure roll in the direction of said statiOnary pressure roll to a position wherein said pressure rolls are in pressure engagement with opposite surfaces of said side plate and for moving said movable pressure roll away from said stationary pressure roll to a position in which there is sufficient space between said pressure rolls to permit unobstructed insertion of a side plate between said rolls.