Multi-functional sensing methods and apparatus therefor

A method of detecting the distance between a nozzle assembly for a machining process and a workpiece to be machined, comprising:

• supplying a gas to create a pressure within a shield means surrounding a nozzle assembly, said shield means being open at one end to permit a piercing force from said nozzle assembly to exit said shield means;
• detecting an increase in pressure caused within said shield means as said open end of said shield means approaches a workpiece to be machined;
• monitoring said increase in pressure within said shield means;
• and
• detecting when said pressure reaches a pressure which corresponds to a predetermined gap distance between said nozzle assembly and said workpiece for a machining process.

An apparatus for sensing a pierce-through condition of a material made by a piercing force, comprising:

• a shield means for surrounding a source of a piercing force;
• a means for supplying a gas to create a pressure within said shield means;
• and
• a sensing means for detecting a decrease in pressure caused within said shield means by said pierce-through condition created by said piercing force, said sensing means being disposed between and in fluid communication with said means for supplying gas and said shield means.