Amada 300 Series, Operation Manual

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APPENDIX C: WELD HEAD DYNAMICS
SERIES 300 FAST RESPONSE WELD HEAD SYSTEM
C-2 990-115
The following narrative steps describe the electrode status or action at each stage of the weld cycle.
1 The electrodes are brought into contact with the weld material.
2 The electrode force is increased to the programmed weld force. When the electrode stops moving and
the weld force is established, the net force acting on the electrode is 0 (zero). That is, the weld force
supplied by the linear actuator (or spring) is balanced by the reaction force of the weld material.
3 The resistance welding power supply is turned on.
4 Weld current flows through the electrodes and the weld material.
5 After a short period, the weld material softens or melts.
6 The net force on the electrodes is now no longer 0 (zero). The reaction force provided by the weld
material decreases because the material has softened. Now, the electrodes start to move into the weld
material. This movement, called ‘follow-up,’ compresses the weld material until the reaction force
builds up again and exactly balances the applied weld force.
7 During the follow-up movement, the electrodes move from a dead stop to a certain speed throughout the
follow-up period. Then, they stop when the reaction force builds up again. The time that is most crucial
to weld quality is when the electrodes just start to move. They must accelerate rapidly to maintain force
on the weld material to prevent expulsion.