Abstract: In a method for joining at least two plate-shaped workpieces by a fastening tool and a device for operating the fastening tool, the fastening tool comprises a punch for exerting a punch force to perform a joining operation and a clamp for exerting a clamping force upon the workpieces at the joining area. During the joining operation the punch exerts a high punch force to perform the joining operation and the clamp exerts substantially no clamping force to allow for free material deformation in the joining area. After the joining operation both the punch and the clamp exert high forces at the same time to reduce any material deformations of the workpieces and to provide for compression of the workpieces in the joining area. Preferably the invention is used in a riveting tool for setting self-piercing rivets; as an alternative it may be used in a clinching tool.

Abstract: In a method for joining at least two plate-shaped workpieces by a fastening tool and a device for operating the fastening tool, the fastening tool comprises a punch for exerting a punch force to perform a joining operation and a clamp for exerting a clamping force upon the workpieces at the joining area. During the joining operation the punch exerts a high punch force to perform the joining operation and the clamp exerts substantially no clamping force to allow for free material deformation in the joining area. After the joining operation both the punch and the clamp exert high forces at the same time to reduce any material deformations of the workpieces and to provide for compression of the workpieces in the joining area. Preferably the invention is used in a riveting tool for setting self-piercing rivets; as an alternative it may be used in a clinching tool.

Abstract: In a method for joining at least two plate-shaped workpieces by a fastening tool and a device for operating the fastening tool, the fastening tool comprises a punch for exerting a punch force to perform a joining operation and a clamp for exerting a clamping force upon the workpieces at the joining area. During the joining operation the punch exerts a high punch force to perform the joining operation and the clamp exerts substantially no clamping force to allow for free material deformation in the joining area. After the joining operation both the punch and the clamp exert high forces at the same time to reduce any material deformations of the workpieces and to provide for compression of the workpieces in the joining area. Preferably the invention is used in a riveting tool for setting self-piercing rivets; as an alternative it may be used in a clinching tool.

Abstract: A drive system for a fastening tool, in particular a riveting tool, includes a punch for a fastening operation and a clamp axially moveable relative to the punch for clamping the workpieces during the fastening operation. The punch is actuated by a drive so as to be displaced axially. During such operation the drive force exerted upon the punch is transmitted to the clamp by force transmitting means comprising an air pressure chamber of variable volume.

Abstract: A hydraulic drive mechanism to actuate a tool for joining at least two work-pieces of ductile material such as by self-piercing riveting or clinching. The drive mechanism comprises a punch drive for actuating a punch and a clamp drive for actuating a clamp which clamps the workpieces against an up-setting die during the joining operation. Both drives comprise piston cylinder assemblies. The piston cylinder assembly of the clamp drive is carried by the piston rod of the punch drive. The pressure chamber of the clamp drive communicates with one of the work chambers of the punch drive such that pressure within the work chamber of the punch drive is transmitted to the pressure chamber of the clamp drive in order to generate the clamping force. As a result thereof only a pair of fluid connections are required for operating both drives.