Digital Micrometer with Linear and Rotational Stage Motion System The rivet is held horizontally, on a rotational stage, which rides on a linear stage. The part can be passed through a digital micrometer. The measurement data and stage positions can be combined to form a 2D profile, from which diameter and length measurements can be obtained. 

Pros o o o o



Accurate measurements of lengths and diameters Part can be rotated around axis, so that roundness and concentricity can be determined Simple system architecture Relatively low cost

Cons o

Cannot measure undercut, without additional components

2D Laser Profile Scanner with Linear and Rotational Stage Motion System A 2D laser profile scanner is mounted on a vertical linear stage. This obtains a profile of the rivet, which is held in a rotational stage. The rivet can also be rotated 90 degrees with respect to the laser, so the profile of the end of the rivet may be obtained. 

Pros o



Can measure every critical dimension with high accuracy

Cons o o o

Increased system cost Added system complexity due to third axis of motion Longer cycle time per part

Vision Camera and Rotational Stage A vision camera is used to take a picture of the rivet profile, from which measurements are obtained via an image analysis software. The rivet is mounted to a rotational stage, so that images can be taken from several angles, for determination of roundness and concentricity. 

Pros o o o



Simple system architecture Can accurately determine many measurements Quick cycle time

Cons o o o

Increased system cost Cannot measure undercut, without additional components Sensitive to surrounding lighting conditions, may require adjustment by technicians

Coordinate Measurement Machine (CMM) Packaged machine and software, capable of highly accurate measurements in 3D space. 

Pros o o

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Highly accurate measurement Can measure every critical dimension

Cons o o

Expensive solution Increased cycle time

Undercut Measurement Options Several potential methods for measurement of the undercut region are proposed. These may be required in conjunction with the digital micrometer or vision camera design proposals. Additional profile sensor normal to flat end of rivet 2D laser scanner mounted normal to flat ‘indented circle’ end of rivet. The sensor beam would pass through the center of the rivet, capturing the profile of the undercut, round, and indented circle. The rivet could be rotated during the scan, so that the entire undercut area would be measured. Depending on the depth of field of the sensor, separate passes may be required for measurement of the undercut and the indented circle. 

Pros o o

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Simplified component layout & complexity Capable of measuring entire profile of undercut area & indented circle

Cons o o

Prohibitively expensive May require adjustment to center scanner with respect to part

Tubular shaft attached to limit switch A hollow tubular shaft, with ID closely matched to rivet sleeve OD, is mounted concentrically with the rivet. As the linear stage moves the rivet, the stem end enters the ID of the tube. When the tube makes contact with material in the undercut area, a limit switch is triggered. The data processing system can then calculate a minimum undercut angle. 

Pros o o

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Relatively simple architecture Low cost components

Cons o o o o o

Only can measure depth at a fixed radius Extra material and imperfections may trigger an incorrect measurement Requires very precise alignment of multiple components Tube must be changed for different size rivets, creating more alignment issues Cannot measure undercut edge round, or check presence of indented circle

Stylus attached to limit switch Similar to the previous option, but uses one or multiple styli to take position readings. The part could be rotated between readings, allowing multiple values to be calculated. 

Pros o o o o



Cons

Simple architecture Eliminates some alignment issues, as opposed to using hollow tube Does not require changing parts for different rivet types Low cost

o o o

Can only measure depth at specific points Requires precise positioning with respect to axis of rivet Cannot measure undercut edge round, or check presence of indented circle

Stylus attached to position encoder, on linear stage A single stylus rides on a small displacement linear stage, with motion perpendicular to the rivet axis. The part is advanced linearly until the stylus makes contact with the undercut. The stylus is then moved side to side, obtaining a trace of the undercut profile. 

Pros o o o



Can obtain detailed profiles of undercut round and undercut angle Eliminates many alignment issues Does not require changing parts for different rivet types

Cons o o o o

Complex system Complex data analysis required Potentially expensive Cannot check presence of indented circle