Abstract: In the invention, an apparatus is designed for producing spacer frames for insulating glass window structures, made up of lengths of hollow molding joined together by male cornerpieces. Hollows and spaces at the corner joins are sealed or filled by injection of a sealing composition forced in by the use of a female injection head designed to take up a frame corner, and a driver for pushing the frame corner structure into the injection head. There is furthermore a work table for the frame parts in the working position on injection of the compound or sealant, and gripper structures for keeping the hollow molding lengths, forming the corner, in the desired position. At least one of the gripper structures is able to be moved towards the put-in male part of the cornerpiece after the hollow molding part has been gripped.