Metal Forming Tool Monitoring Based on a 3D Measuring Endoscope Using CAD Assisted Registration

Abstract

In order to provide timely, reliable, and comprehensive data for the maintenance of highly stressed geometries in sheet-bulk metal forming tools, this article features a possible setup by combining a 3D measuring endoscope with a two-stage kinematic. The measurement principle is based on the projection of structured light, allowing time-effective measurements of larger areas. To obtain data of proper quality, several hundred measurements are performed which then have to be registered and finally merged into one single point cloud. Factors such as heavy, unwieldy specimens affecting precise alignment. The rotational axes are therefore possibly misaligned and the kinematics and the hand-eye transformation remain uncalibrated. By the use of computer-aided design (CAD) data, registration can be improved, allowing a detailed examination of local features like gear geometries while reducing the sensitivity to detect shape deviations.

Fringe Projection Profilometry in Production Metrology: A Multi-Scale Comparison in Sheet-Bulk Metal Forming

“…However, it should also be mentioned that, due to the spatial frequency of the specimen, no particular advantage can be expected with respect to the relative phase measurement uncertainty with additional magnification. In general, this implies that, for each spatial frequency, there is an optimal corresponding fringe frequency [ 39 , 64 ] of which there is a necessary corresponding pixel resolution. The applied sphere appears to be particularly smoothly reconstructed by certain sensors at larger measuring volumes, suggesting that the spatial frequency of the sphere is favouring sensors with larger scale ranges and aliasing effects of limited sampling with respect to camera and projector appears undetectable.…”

“…This sensor is optimized for robot-guided inspection in narrow spaces due to its design and flexible positioning [ 38 ]. Within the TCRC 73, in-situ inspections were carried out during the ongoing forming process to quantify the tool condition between consecutive forming cycles and to predict failure [ 39 ]. Such an application is shown in Figure 4 a.…”

“…A distortion correction follows the approach of Conrady and Brown [ 48 ]. For different measurement applications, different sensor head designs have been developed with different working distances [ 39 ]. Gradient index rod-lenses supplied by GrinTech GmbH (Jena, Germany) are applied at 10 and 20 mm working distance (wd).…”

Special Issue “Fiber Optic Sensors and Applications”: An Overview

“…In "Metal Forming Tool Monitoring Based on a 3D Measuring Endoscope Using CAD Assisted Registration" [11], a setup by combining a 3D measuring endoscope with a two-stage kinematic was demonstrated based on the projection of structured light, allowing time-effective measurements of larger areas. By the use of computer-aided design (CAD) data, registration was improved, allowing a detailed examination of local features like gear geometries while reducing the sensitivity to detect shape deviations.…”

Guided, Fusion-Based, Large Depth-of-field 3D Imaging Using a Focal Stack

“…Three dimensional (3D) imaging based on structured light has been widely used in many applications, such as for human–computer interactions, industrial measurements, and regarding cultural relics [1,2,3]. There are numerous structured-light methods which have been discussed thoroughly by Salvi et al [4] and Zhang [5].…”