Method of operating a linear friction welding system with phase change assembly

1. A method of operating a linear friction welding system including (i) a ram configured to vibrate along a welding axis, (ii) a cam follower operably connected to the ram, (iii) an eccentric including an eccentric outer periphery operably engaged with the cam follower, and an inner periphery, (iv) a first power shaft slidingly engaged with the eccentric, (v) a second power shaft eccentrically engaged with the inner periphery, (vi) a first timing component configured to drive both the second power shaft and a phase change assembly drive shaft, (vii) a motor configured to drive the first timing component, and (viii) a phase change assembly driven by the phase change assembly drive shaft, comprising:

positioning the phase change assembly in a first configuration thereby establishing a first phase relationship between the first power shaft and the second power shaft whereat the ram does not vibrate when the first power shaft and the second power shaft rotate;

driving the first timing component with the motor,

driving the first power shaft and the phase change assembly with the first timing component with the phase change assembly in the first configuration;

driving the second power shaft with the phase change assembly while the phase change assembly is in the first configuration;

establishing a scrub pressure between two components to be welded with the phase change assembly in the first configuration while the first timing component is being driven;

establishing a second phase relationship between the first power shaft and the second power shaft by moving the phase change assembly to a second configuration while the first power shaft and the second power shaft are being driven, thereby causing the ram to vibrate along the welding axis while the scrub pressure is applied;

reestablishing the first phase relationship between the first power shaft and the second power shaft by returning the phase change assembly from the second configuration to the first configuration; and

establishing a forge pressure between the two components with the phase change assembly returned to the first configuration.

2. The method of claim 1 , wherein moving the phase change assembly to the second configuration comprises:

lengthening a load segment of a second timing component of the phase change assembly.

3. The method of claim 2 , wherein lengthening the load segment comprises:

moving a carriage rotatably supporting a gear engaged with the second timing component load segment along a phase change axis.

4. The method of claim 3 , wherein moving the carriage comprises:

moving the carriage from a first location associated with the first configuration toward a second location associated with the second configuration with a linear actuator.

5. The method of claim 4 , wherein moving the phase change assembly to the second configuration comprises:

stopping movement of the carriage toward the second location with a first stop.

6. The method of claim 5 , further comprising:

determining a desired ram vibration amplitude; and

setting a position of the first stop based upon the desired ram vibration amplitude.

7. The method of claim 6 , wherein returning the phase change assembly comprises:

moving the carriage toward the first location with the linear actuator; and

stopping movement of the carriage toward the first location with a second stop.

8. The method of claim 7 , wherein positioning the phase change assembly at the first location comprises:

positioning the second stop at a location whereat when the carriage contacts the second stop the ram does not vibrate when the first power shaft and the second power shaft rotate.

9. The method of claim 8 , wherein setting the position of the first stop comprises:

changing the location of the first stop by rotating a first threaded bolt.

10. The method of claim 9 , wherein positioning the second stop comprises:

changing the location of the second stop by rotating a second threaded bolt.