Spot-joining apparatus and methods

A method of driving a fastener or performing a clinching or friction stir spot welding operation, the method comprising:

• bringing the fastener or a punch into contact with a workpiece;
• causing the fastener or punch to rotate under action of a first transmission, the first transmission transferring rotary motion of a motor to the fastener or punch when engaged;
• and
• driving the fastener or punch into the workpiece under action of a second transmission, the second transmission translating rotary motion of said motor into linear motion of the fastener or punch when engaged,
• wherein the degree of engagement of at least one of the first and second transmissions is selectively adjusted by a transmission control apparatus.

A method of driving a fastener or performing a clinching or friction stir spot welding operation, the method comprising:

• bringing the fastener or a punch into contact with a workpiece;
• selectively rotating at least a portion of an upsetting die counterposed with the fastener or punch;
• and
• driving the fastener or punch into the workpiece.

A spot-joining apparatus comprising:

• a motor;
• a punch for driving a fastener or performing a clinching or friction stir spot welding operation;
• a multifunctional transmission configured to perform a first function, which is to transfer rotary motion of the motor to the punch, and a second function, which is to convert rotary motion of the motor to linear motion of the punch;
• and
• a transmission control apparatus arranged to selectively adjust the degree to which the multifunctional transmission performs at least one of the first and second functions.