Diaphragm-support disc for a polishing machine and method of operating a polishing machine

A polishing machine for polishing a work piece, said polishing machine comprising:

• a polishing surface or cloth;
• a diaphragm positionable so that the work piece is sandwiched between a radial front face of the diaphragm and the polishing surface or cloth;
• a diaphragm-support disc, the diaphragm being extended across a radial front face of the disc and wrapped around a peripheral edge of the radial front face of the disc;
• a main annular part projecting from the radial front face of the disc, the main annular part being located in a peripheral region of the radial front face of the disc and a predetermined distance from the peripheral edge of the radial front face of the disc;
• and
• a secondary annular part projecting from the radial front face of the disc, the secondary annular part being located on the peripheral edge of the radial front face of the disc,
• wherein during polishing of the workpiece, the main annular part physically contacts the diaphragm so as to press the diaphragm against the work piece and press the work piece onto the polishing surface or cloth by an axial displacement of the disc with respect to the polishing surface or cloth, and
• the secondary annular part does not extend as far from the radial front face of the disc as the main annular part, and the main annular part is located some distance from the secondary annular part.

A method of operating a polishing machine to polish a work piece, the polishing machine of the type including:

• a polishing surface or cloth;
• a diaphragm positionable so that the work piece is sandwiched between a radial front face of the diaphragm and the polishing surface or cloth;
• and
• a diaphragm-support disc, the diaphragm being extended across a radial front face of the disc and wrapped around a peripheral edge of the radial front face of the disc,
• said method comprising the steps of:
• providing a main annular part that projects from the radial front face of the disc in a peripheral region of the radial front face of the disc and a predetermined distance from the peripheral edge of the radial front face of the disc;
• using a fluid to exert pressure on a radial rear face of the diaphragm so as to press the work piece onto the polishing surface or cloth;
• during polishing of the workpiece, using the main annular part to physically contact a radial rear face of the diaphragm so as to press the diaphragm against the workpiece and press a peripheral region of the work piece onto the polishing surface or cloth;
• and
• providing a secondary annular part that projects from the radial front face of the disc on the peripheral edge of the radial front face of the disc,
• wherein the secondary annular part does not extend as far from the radial front face of the disc as the main annular part, and the main annular part is located some distance from the secondary annular part.