Cutting machine and method of measuring clearance

1 . A cutting machine comprising a die, and a cutting punch having a cutting edge, and configured to bring said cutting punch close to said die to have said cutting edge face to a surface of said die thereby cut a work, said cutting punch being provided with a local slope,

wherein said cutting machine is configured, using a light source, to irradiate a light such that the light transmit through the clearance between said cutting punch and said surface of said die and to reflect on said local slope such that the direction of the path of said light is changed so as to yield reflected light to be observed.

2 . The cutting machine as claimed in claim 1 ,

wherein said local slope of said cutting punch is inclined at a predetermined angle so as to expand the cross section of said cutting punch in the direction departing from the light source.

3 . The cutting machine as claimed in claim 2 , wherein said predetermined angle is 45°.

4 . The cutting machine as claimed in claim 1 ,

wherein said cutting punch has a plurality of said local slopes provided thereto so as to form steps.

5 . A method of measuring a clearance using the cutting machine described in claim 1 ,

configured to measure light reflected on said local slope to thereby measure said clearance.

6 . The method of measuring a clearance as claimed in claim 5 ,

configured to measure the beam width of light reflected on said local slope to thereby measure said clearance.