Measuring method and equipment for the automatic control of the forwards and backwards movement of the grinding wheel of a surface grinder

A measuring apparatus for the automatic control of the forwards and backwards movement of the grinding wheel of a surface grinder relative to a horizontal table mounted on a frame for movement under the grinding wheel to permit the latter to scan a field and to machine workpieces placed on the table inside this field until these workpieces reach a nominal size, said apparatus comprising;

• a measuring head mounted on the frame of the grinder to feel the upper surface of at least one of the workpieces during different successive passes of these workpieces under the grinding wheel and to produce each time a measuring signal which substantially represents their actual size;
• a reference block of a thickness less than the nominal size of the workpieces, said reference block being placeable on the table along with the workpieces in a position inside the field scanned by the grinding wheel so that the measuring head feels the reference block during each of said successive passes and also produces each time a reference signal;
• and,
• an electronic measuring circuit which is connected to the measuring head and which comprises first storage means to store the reference value between two moments when the reference block is felt by the measuring head, and calculating means to calculate at least for each of said passes the difference between the value of said measuring signal and the stored value of said reference signal and to produce a resulting signal which corresponds to the actual size of said workpieces and which can be used for the control of the forwards and backwards movements of the grinding wheel.