conche vs concher

conche

noun
  • Synonym of concher (“machine used to refine the flavour and texture of chocolate”) 

concher

noun
  • A machine (rather like a rotating pestle and mortar) used to refine the flavour and texture of chocolate by warming and grinding. 

  • A person who operates such a machine. 

How often have the words conche and concher occurred in a corpus of books? (source: Google Ngram Viewer )