Central Surface Inspection Station at Daimler Press Shop in Sindelfingen
Daimler AG has introduced a fully automatic ABIS II surface inspection system (fig. 1) as a central audit station at their press shop 2 in Sindelfingen, Germany. The system, which was implemented in November 2008, achieves the highest degree of automation, the greatest flexibility and the highest throughput compared to systems used by other automakers.
The test sequence (see fig. 2) comprises placing a part on the infeed conveyor [1] and transporting it into the inspection cell [2], where its position is determined (single camera mounted above the conveyor), the robot path is adjusted, and the part is examined by the ABIS II surface inspection system; the part is then transported out of the cell by the outfeed conveyor [3]. At the outfeed conveyor (fig. 3+4), a large visualization screen displays the surface inspection results (fig. 5).
The operator unloading the outfeed conveyor can see from the on-screen report if the current part is OK or if it has to be reworked or scrapped. In conventional manual auditing with a whetting stone, inspecting one entire body side frame takes at least 15 minutes – a task that the ABIS II system completes in less than two minutes.
The fully automatic ABIS II surface inspection system is also used for various other tasks at Daimler's press shop in Sindelfingen:
- Imaging the agreed surface limit samples and implementing a central test station based on objective criteria
- Conducting individual tests to objectively assess a part's quality if discussions arise concerning problematic areas on single parts
- Efficiently sorting the individual press lots during automatic operation of the system. Lot sizes can range from 100 to 2000 parts. Sufficient space for loading equipment and fork lift traffic is provided around the system.
- Performing sampling inspection as an integral part of the press shop's quality loop and thus providing quick feedback on the surface quality after a tool change
The concept of the system installed at Daimler AG in Sindelfingen was developed in close cooperation between the planners and plant managers at Daimler and the engineers at Steinbichler Optotechnik.
A special feature of the Daimler system is that it is optionally expandable to allow inspecting parts of the complete bodywork, as well. To do this, the door of the inspection cell is opened and the body shell is positioned in front of the robot. The robot moves the ABIS II sensor to the parts to be inspected. This is done in safe manual mode, an additional operating mode that allows users to inspect surfaces which, once assembled, can no longer be placed on the conveyor belt as single parts. After assembly, parts such as body side frames, fenders and roofs can only be inspected on the complete bodywork.
The reason behind the system's concept is the need to examine and trace the surface quality after each of the process steps Single Part, Assembly and Cathodic Dip Painting. Experience has shown that surface defects rated as requiring rework in single parts sometimes lose relevance in the subsequent processes. The opposite is also known (particularly at eye level): defects that initially were not rated as requiring rework in the single part later become clearly visible after cathodic dip painting.
Fig. 1:
Central surface inspection station at Daimler AG's press shop 2 in Sindelfingen
Fig. 2: Test sequence
1 - Part placement on infeed conveyor
2 - Inspection cell with ABIS II
3 - Outfeed conveyor with display of test result
Fig. 3:
Outfeed side with large visualization screen
Fig. 4:
View of inspection cell from outfeed conveyor
Fig. 5:
On-screen display of test result at
outfeed conveyor
