Method for machining thin plates and elastic joints particularly for monolithic mechanical oscillators

A method for achieving a monolithic folded pendulum from a blank made of a material, the method comprising the following steps:

• LA. Preparing said blank so that:
• LA1. it comprises two opposite flat main faces;
• and
• LA2. there are eight pairs of apertures on said two flat main faces in a direction substantially perpendicular to said two flat main faces, in each of the eight pairs of apertures there being defined an element with a main extension direction and a first side and a second side, opposite to the first side, along said main extension direction, said first side and said second side having a surface substantially perpendicular to said two flat main faces;
• LB. In each of the eight pairs of apertures, working said first side, by milling a portion of the material of said element along said perpendicular direction from one of said two flat main faces to a depth deeper than a design depth;
• LC. In each of the eight pairs of apertures, working said second side, by milling a portion of said element along said perpendicular direction from one of said two flat main faces to said depth (ps) deeper than the design depth,
• wherein the operation of steps LB and LC is adapted to form a worked element between each of the eight pairs of apertures, thus forming eight worked elements, and wherein the following further steps are performed:
• LD. Drilling four holes in a first connecting face of said blank which connects said two flat main faces, the four holes being formed to said depth (ps) respectively parallel to four worked elements of the eight worked elements, so that said four worked elements of the eight worked elements are removed from the blank to said design depth;
• LE. Drilling four further holes in a second connecting face of said blank which connects said two flat main faces, said second connecting face being opposite to said first connecting face, the further four holes being formed to said depth (ps) respectively parallel to the other four worked elements of the eight worked elements, so that said other four worked elements of the eight worked elements are detached from the blank to said design depth, thus obtaining eight corresponding joints;
• LF. At two joints of the eight corresponding joints per flat main face, removing material from said blank which is not adjacent to each of the two joints of the eight corresponding joints, so that each of the two joints of the eight corresponding joints is connected at one end only to a central portion of said blank worked to act as an oscillating mass in the folded pendulum;
• LG. Applying an immobilization system of said eight corresponding joints to at least one of the two flat main faces by immobilizing portions of said blank along said main extension direction with fall between pairs of joints of said eight corresponding joints;
• and
• LH. Working the blank so as to detach said eight corresponding joints and said central portion from the rest of the blank, thus obtaining a free central mass connected, through pendulum arms, to a frame by means of the eight corresponding joints, according to a folded pendulum scheme.