Monitoring machine tool conditions by measuring a force component and a vibration component at a fundamental natural frequency
First Claim
1. A method for monitoring, during machining of a workpiece, the wear condition of a cutting tool having a cutting portion in a structure that is held by substantially more massive means, comprisingmeasuring the component of the dynamic force exerted between the tool and the workpiece approximately in the direction normal to the primary cutting edge of the tool and to the main cutting velocity at approximately the fundamental natural frequency of the held structure in the same normal direction,measuring the component of vibration in the tool approximately in the same normal direction at approximtely the same frequency,computing the value of a predetermined wear indicative function of the ratio of the measured force component to the measured vibration component, andproviding a predetermined type of response to the computed value of the function comprising at least one of the following operations,(a) adjusting cutting conditions to control the rate of wear,(b) adjusting the position of the tool relative to the workpiece to compensate for recession in the cutting portion of the tool,(c) replacing the tool when the wear on a cutting portion exceeds a selected limit.
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Accused Products
Abstract
Methods and apparatus for monitoring, during machining of a workpiece (30,30'"'"'), the wear condition of a cutting tool (31,31'"'"') having its cutting portion in a structure (32,32'"'"') that is held by substantially more massive means (33,33'"'"').
A dynamometer (35,35'"'"') and filter (36) measure the component of the dynamic force exerted between the tool (31,31'"'"') and the workpiece (30,30'"'"') approximately in the direction (A,A'"'"') normal to the primary cutting edge (34,34'"'"') of the tool (31,31'"'"') and to the main cutting velocity (V,V'"'"') at approximately the fundamental natural frequency of the held structure (32,32'"'"') in the same normal direction (A,A'"'"'). An accelerometer (37,37'"'"'), filter (38), and integrators (39) measure the component of vibration in the tool (31,31'"'"') approximately in the same normal direction (A,A'"'"') at approximately the same frequency. Data processing equipment (41,42,43) computes the value of a wear indicative function of the ratio of the measured force component to the measured vibration component, and provides a display, adjustment, or other selected type of response (44) thereto.
The computed value of the function typically indicates the amount of wear (FW) on the flank of the primary and secondary cutting edges (34,34'"'"') of the tool (31,31'"'"') during turning, milling, or drilling.
74 Citations
23 Claims
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1. A method for monitoring, during machining of a workpiece, the wear condition of a cutting tool having a cutting portion in a structure that is held by substantially more massive means, comprising
measuring the component of the dynamic force exerted between the tool and the workpiece approximately in the direction normal to the primary cutting edge of the tool and to the main cutting velocity at approximately the fundamental natural frequency of the held structure in the same normal direction, measuring the component of vibration in the tool approximately in the same normal direction at approximtely the same frequency, computing the value of a predetermined wear indicative function of the ratio of the measured force component to the measured vibration component, and providing a predetermined type of response to the computed value of the function comprising at least one of the following operations, (a) adjusting cutting conditions to control the rate of wear, (b) adjusting the position of the tool relative to the workpiece to compensate for recession in the cutting portion of the tool, (c) replacing the tool when the wear on a cutting portion exceeds a selected limit.
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10. Apparatus for monitoring, during machining of a workpiece, the wear condition of a cutting tool having a cutting portion in a structure that is held by substantially more massive means, comprising
means for measuring the component of the dynamic force exerted between the tool and the workpiece approximately in the direction normal to the primary cutting edge of the tool and to the main cutting velocity at approximately the fundamental natural frequency of the held structure in the same normal direction, means for measuring the component of vibration in the tool approximtely in the same normal direction at approximately the same frequency, means for computing the value of a predetermined wear indicative function of the ratio of the measured force component to the measured vibration component, and means for providing a predetermined type of response to the computed value of the function comprising means for providing at least one of the following operations, (a) adjusting cutting conditions to control the rate of wear, (b) adjusting the position of the tool relative to the workpiece to compensate for recession in the cutting portion of the tool, (c) replacing the tool when the wear on a cutting portion exceeds a selected limit.
Specification