The tensile testing of heavy plate poses various challenges to the steel industry. With test specimens weighing up to 10kg operators can have difficulty trying to ac-curately place and align the specimen in the grips of the testing machine. Zwick recently provided one of its customers with a completely automatic solution which also allows testing 24 hours per day.
The operator simply places the test specimen in one of 133 positions in a heavy duty magazine, and a “portal” robotic handing system then takes over the process. With its multi-axis gripping head it removes the first specimen from the magazine and places it into a measurement and alignment unit. This ensures that the speci-men is correctly aligned in the testing machine. The cross-section measurement unit is fully automatic and uses precision high resolution digital sensors to measure the width and thickness.
The sample is then removed from the cross section measuring unit and placed in the hydraulic grips of the tensile testing machine. The grips are closed automatically to a fixed pressure defined in the software or as a function of the measured cross-sectional area of the test specimen. This ensures the optimum gripping parameters are determined for each individual tensile test.
The testing machine is a hydraulic 4-column construction with a capacity of 2000 kN and is fitted with Zwick’s digital macro extensometer used by many steel producers worldwide. This automatic device measures the elongation to failure as well as proof stress (offset yield). At the end of the test the extensometer is detached from the specimen, the robot grips one end of the test specimen and the hydraulic grip is opened. This is repeated for the other half of the specimen and the grips are then returned to their starting position for the next test. For additional investigations, the specimen remains can be sorted into different locations depending on the result of the tensile test.
As with most Zwick products the entire test is under the control of testXpert II® soft-ware. All control parameters for the test can be entered manually or imported auto-matically via on-line databases. At the end of the test, the results can be printed on a test report, exported to an external database or Microsoft Office program, and/or stored in a special data file with all control parameters used for the test.
The major benefit of this system is that it provides a much safer working environ-ment and avoids repetitive processes for operators enabling them to be deployed on much more important tasks. Because of improved testing efficiency the system generates tests results faster, with significantly higher integrity, and is quickly amor-tized.
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