Abstract: An apparatus for rounding off edges of openings in a work piece, such as internal openings or cut outs in steel plates. The apparatus includes a belt grinding machine having a continuous grinding belt running over several belt guiding rollers which are provided on a support frame. Two of the rollers are provided on a cradle, that is pivotally supported in the support frame. The grinding belt is, between the rollers on the cradle, disposed for rectilinear working of the work piece, and a device is arranged for operating the cradle in a pendulum like movement about the pivotal support during a grinding operation.

Abstract: An edge grinding device for rounding off edges of members which are passed through the grinding device. The device includes a main frame for supporting the structural member, and a grinding aggregate which is pivotably mounted on the frame about an axis running substantially parallel to the directional motion of the member, the grinding aggregate having a grinding element which has a convex grinding surface, wherein the grinding aggregate pivots the convex grinding surface about the edge which is to be round while the member is moving through the device.