Device and method for avoiding an interruption in the welding process during friction stir welding, in particular breakage of the friction pin

1. A device for avoiding an interruption of the welding process during friction stir welding, with the following features:

a) at least three elongated sensors ( 8 ), oriented at an angle of 120 degrees to one another, on the longitudinal sides of a wedge-shaped tool dome ( 7 ), the tool dome ( 7 ) guiding a welding pin ( 19 ) by means of a tool receiving cone ( 28 ) and a welding shoe ( 11 ), and the elongated sensors ( 8 ) being designed for determining force, pressure and travel,

b) a cone constriction in the lower region of the tool receiving cone ( 28 ), which serves for receiving a sensor ( 22 ) for detecting an axial force, a torque and a bending moment at the welding pin ( 19 ),

c) a piezo vertical adjustment for the welding pin ( 19 ),

d) an arrangement of a laser measuring sensor ( 10 ) in the region of the welding shoe ( 11 ), which passes over a round hole ( 27 ) in the passing-through region of the pin tip ( 12 ), an airborne sound sensor ( 3 ) being arranged opposite the laser measuring sensor ( 10 ), and a welding shoe temperature sensor being provided,

e) a sensor signal amplifier ( 23 ), with a rotor antenna for receiving, amplifying and passing on all of the measured values detected, these measured values being passed on to a machine controller by a static antenna ( 16 ),

f) an inductive power supply system for supplying the measuring system from a moving secondary winding ( 24 ) and a fixed primary winding ( 25 ).

2. The device as claimed in claim 1 , wherein a structure-borne sound sensor ( 29 ), which is directed with its directional effect into the region between the welding pin 19 and the welding shoe 11 , is installed in the region of the upper end of the union nut ( 9 ).

3. The device as claimed in claim 1 , wherein an eddy current sensor 31 is used for measuring extremely small distances, this sensor being arranged transversely to the welding direction.

4. The device as claimed in claim 1 , wherein a temperature sensor is provided for detecting the temperature of the welding shoe 11 .

5. A method for avoiding an interruption of the welding process during friction stir welding, in particular breakage of the friction pin, with the following features:

a) a device compromising a system of elongated sensors ( 8 ) for determining force, pressure and travel of a rotating tool dome ( 7 ), guiding a welding pin ( 19 ), is supported by a cone constriction in the lower region of a tool receiving cone ( 28 ), which serves for detecting an axial force, a torque and a bending moment at a welding pin ( 19 ), sensors for detecting bending and a temperature of the welding pin ( 19 ) provide information about the state of the welding pin ( 19 ) before any damage to the welding pin occurs,

wherein at least three of the elongated sensors ( 8 ) are oriented at an angle of 120 degrees to one another, on the longitudinal sides of a wedge-shaped tool dome ( 7 ), the tool dome ( 7 ) guiding a welding pin ( 19 ) by means of a tool receiving cone ( 28 ) and a welding shoe ( 11 ), and the elongated sensors ( 8 ) being designed for determining force, pressure and travel, and

wherein the device further comprises a cone constriction in the lower region of the tool receiving cone ( 28 ), which serves for receiving a sensor ( 22 ) for detecting an axial force, a torque and a bending moment at the welding pin ( 19 ).

6. The device as claimed in claim 1 , wherein the interruption of the welding process to be avoided is breakage of the friction pin.