Abstract: Fiber optic laser apparatus for spot welding, brazing, or soldering comprises an optical fiber for transmitting a laser beam to a workpiece, and a tool disposed at an output end of the optical fiber for mechanically engaging and applying pressure to the workpiece. The output end of the optical fiber is supported within a longitudinal bore of the tool with the tip of the fiber closely adjacent to an opening in a workpiece-engaging end of the tool. The diverging laser beam from the end of the optical fiber projects a spot onto the workpiece through the opening with sufficient power to cause melting without the necessity for a lens system for focusing of the laser beam.

Abstract: Gradual wear or breakage of a machine tool which occurs over a period of time is detected by sensing high frequency vibrations produced at the cutting tool/workpiece interface during a machining process. The high frequency vibrations are converted to a unipolar vibration signal which is processed to produce a tracking signal which tracks the minimum value of the vibration signal. The vibration signal is related to the effective cutting energy and it decreases due to gradual tool wear or breakage. The tracking minimum signal is compared to a predetermined threshold level to detect excessive wear or breakage of the tool, and an alarm is provided.