Method and apparatus for dynamically checking dimensions of mechanical parts

A method for checking dimensions of a mechanical part by means of a checking head (2) including a casing (8), at least a feeler (14) movable with respect to the casing (8) and adapted to contact a surface (6) of the part (4), and transducer means (20) for providing a signal responsive to the position of the feeler (14), the method comprising the steps of:

• controlling a mutual displacement between the checking head (2) and the part (4) so as to obtain a first mutual sliding motion between the feeler (14) and the surface (6) of the part, towards, a portion to be checked, along a predetermined path (52);
• detecting a first passage o the feeler (14) at the portion (56;
• 66, 68) to be checked;
• and
• detecting the signal provided by the transducer means (20) in correspondence with said first passage (58;
• 70),
• characterized by the following further steps:
• controlling a further displacement between the checking head (2) and the part (4) in order to cause a second mutual sliding motion between the feeler (14) and the surface (6) of the part, towards said portion to be checked, along said path, the second mutual sliding motion being performed in the direction opposite to that of the first mutual sliding motion (52);
• detecting, during the second mutual sliding motion, a second passage of the feeler (14) at the portion to be checked (56;
• 66, 68);
• detecting the signal provided by the transducer means (20) in correspondence with said second passage (58;
• 70);
• and
• processing the values of the signal detected during said first and second passage, said processing step (60) including calculating an average between said values, said average being indicative of the value of the dimension to be checked.

A method, for checking dimensions of a mechanical part by means of a checking head (2) including a casing (8), at least a feeler (14) movable with respect to the casing (8) and adapted to contact a surface (6) of the part (4), and transducer means (20) for providing a signal responsive to the position of the feeler (14), the method comprising the steps of:

• controlling a mutual displacement between the checking head (2) and the part (4) so as to obtain a first mutual sliding motion between the feeler (14) and the surface (6) of the part, towards a portion to be checked, along a predetermined path (52);
• detecting a first passage of the feeler (14) at the portion (56;
• 66, 68) to be checked;
• and
• detecting the signal provided by the transducer means (20) in correspondence with said first passage (58;
• 70),
• characterized by the following further steps:
• controlling a further displacement between the checking head (2) and the part (4) in order to cause a second mutual sliding motion between the feeler (14) and the surface (6) of the part, towards said portion to be checked, along said path, the second mutual sliding motion being performed in the direction opposite to that of the first mutual sliding motion (52);
• detecting, during the second mutual sliding motion, a second passage of the feeler (14) at the portion to be checked (56;
• 66, 68);
• detecting the signal provided by the transducer means (20) in correspondence with said second passage (58;
• 70);
• processing the values of the signal detected during said first and second passage for obtaining a final measurement value depending on the dimension to be checked (60);
• and
• wherein the method additionally includes carrying out all of the preceding steps by using a master part in place of a part to be checked, for zero-setting the checking head.

An apparatus for automatically checking linear dimensions of a mechanical part (4), with:

• a checking head (2) including a casing (8), at least a feeler (14) movable with respect to the casing (8) to contact the surface of the part (4) and transducer means (20) for providing a signal responsive to the position of the feeler (14) with respect to the casing (8),
• driving means (36, 38, 40) for obtaining a first mutual displacement between the checking head (2) and the part (4) along a determined path,
• processing and control means (44) connected to the transducer means (20) and the driving means (40) for controlling said mutual displacements and for performing a first detection and processing of the signal of the transducer means (20),
• characterized in that the processing and control means (44) and the driving means (36, 38, 40) and also adapted for:
• controlling a second mutual displacement between the checking head (2) and the part (4) along said path, the second displacement being performed in a direction opposite to that of the first mutual displacement, and wherein substantially the same points of the surface of the part (4) are scanned by said feeler (14) during said first and second mutual displacement along said path,
• performing a second detection and processing of the signal of the transducer means (20), and processing the results of said first and second processing for obtaining a value responsive to the dimension to be checked.

An apparatus for automatically checking linear dimensions of a mechanical part (4), with:

• a checking head (2) including a casing (8), at least a feeler (14) movable with respect to the casing (8) and transducer means (20) for providing a signal responsive to the position of the feeler (14) with respect to the casing (8),
• driving means (36, 38, 40) for obtaining a first mutual displacement between the checking head (2) and the part (4) along a determined path,
• processing and control means (44) connected to the transducer means (20) and the driving means (40) for controlling said mutual displacements and for performing a first detection and processing of the signal of the transducer means (20),
• characterized in that the processing and control means (44) and the driving means (36, 38, 40) are also adapted for:
• controlling a second mutual displacement between the checking head (2) and the part (4) along said path, the second displacement being performed in a direction opposite to that of the first mutual displacement,
• performing a second detection and processing of the signal of the transducer means (20),
• processing the results of said first and second processing for obtaining a value responsive to the dimension to be checked, and wherein the apparatus further comprises support and reference means (22, 24) for the part (4), a support element (26) carrying the checking head (2), the support means (22) and the support element (26) being mutually movable along said path, the driving means (36, 38, 40) cooperating with the support means (22) and the support element (26) for obtaining said mutual displacements between the checking head (2) and the part (4), detecting means (42) for detecting the mutual position between the checking head (2) and the part (4) along said path, the processing and control means (44) being also connected to the detecting means (42) for obtaining a first and a second measurement value in correspondence with a same portion, to be checked, of the part (4).