Machine capability verification and diagnostics (CAP/DIA) system, method and computer program product
First Claim
1. A method for calibrating a machine having a base, a movable element, which is movable relative to the base in reference to an axis, and a control system for numerically controlling movement of the movable element in reference to the axis along a predetermined distance, the method comprising:
- identifying a plurality (N+1) of predetermined spaced-apart positions (i) along the predetermined distance, each of the positions (i) being associated with a desired position (DPr,i), the desired position (DPr,i) being representative of a desired location of the movable element in the predetermined distance;
moving the movable element to each of the predetermined positions (i) in a first direction and calculating an error (Er,i) between the desired position (DPr,i) and an actual position (APr,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i);
translating the structure to each of the predetermined positions (i) in a second direction opposite the first direction and calculating an error (Er+1,i) between the desired position (DPr+1,i) and an actual position (APr+1,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i);
repeating the above two steps a predetermined number (R/2) of times;
identifying at least two sources of assignable cause error; and
quantifying the assignable cause error that is attributable to the at least two sources using at least one of the error (Er,i) and the error (Er+1,i).
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Accused Products
Abstract
A method for verifying the accuracy of a CNC machine or a CMM. The methodology segregates the measured error into an assignable cause portion and a common cause (or random error) portion. The methodology may be employed to affect the calibration of the machine tool to factor out the mean value of the assignable cause portion. Inherent in this methodology is the ability to diagnose mechanical problems with the CNC machine or CMM that affects the repeatability and accuracy of such machine tools; identify degradation in the performance of such machine tools that is indicative of mechanical failure; and improve the accuracy and repeatability of such machine tools in certain situations.
14 Citations
27 Claims
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1. A method for calibrating a machine having a base, a movable element, which is movable relative to the base in reference to an axis, and a control system for numerically controlling movement of the movable element in reference to the axis along a predetermined distance, the method comprising:
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identifying a plurality (N+1) of predetermined spaced-apart positions (i) along the predetermined distance, each of the positions (i) being associated with a desired position (DPr,i), the desired position (DPr,i) being representative of a desired location of the movable element in the predetermined distance;
moving the movable element to each of the predetermined positions (i) in a first direction and calculating an error (Er,i) between the desired position (DPr,i) and an actual position (APr,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i);
translating the structure to each of the predetermined positions (i) in a second direction opposite the first direction and calculating an error (Er+1,i) between the desired position (DPr+1,i) and an actual position (APr+1,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i);
repeating the above two steps a predetermined number (R/2) of times;
identifying at least two sources of assignable cause error; and
quantifying the assignable cause error that is attributable to the at least two sources using at least one of the error (Er,i) and the error (Er+1,i). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for calibrating a machine having a base, a movable element that is movable relative to the base in reference to an axis, and a control system for numerically controlling movement of the movable element along the axis, the apparatus comprising:
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means for calculating an error (Er,i) between a desired position (DPr,i) and an actual position (APr,i) of the movable element relative to the base and in reference to the axis at each of a plurality of predetermined positions (i) when the movable element is moved relative to the base in a first direction;
means for calculating an error (Er,i) between a desired position (DPr,i) and an actual position (APr,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i); and
means for quantifying an assignable cause error that is attributable to at least two sources, the quantifying means employing at least one of the error (Er,i) and the error (Er+1,i) to quantify the assignable cause error attributable to each of the at least two sources.
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17. A method for calibrating a machine having a base, a movable element, which is movable relative to the base in reference to an axis, and a control system for numerically controlling movement of the movable element in reference to the axis along a predetermined distance, the method comprising:
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identifying a plurality (N+1) of predetermined spaced-apart positions (i) along the predetermined distance, each of the positions (i) being associated with a desired position (DPr,i), the desired position (DPr,i) being representative of a desired location of the movable element in the predetermined distance;
moving the movable element to each of the predetermined positions (i) in a first direction and calculating an error (Er,i) between the desired position (DPr,i) and an actual position (APr,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i);
translating the structure to each of the predetermined positions (i) in a second direction opposite the first direction and calculating error (Er+1,i) between the desired position (DPr+1,i) and an actual position (APr+1,i) of the movable element relative to the base and in reference to the axis at each of the predetermined positions (i);
repeating the above two steps a predetermined number (R/2) of times; and
determining an average cumulative positioning error per unit length (m) based upon an average of the differentials (Er,i) and (Er+1,i) at each of the predetermined positions (i) and an amount by which the movable element is moved relative to the base. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification