24.07.07
Mechanical strain gauge from Vortok International
Vortok is introducing a very simple and yet effective device for measuring the change in strain during tensioning or cutting of rail. The device works by being clamped to a rail at two points, a set distance apart. The instrument contains a micrometer (with digital readout) which is zeroed before the strain in the rail is changed. After the rail is cut or tensioned, there is a change of length over the set distance between the clamps which can be measured by the micrometer. This gives a direct reading where 0.1mm represents a change of 1° celsius in the rail tension.
Application
If a rail is to be cut it may be of interest to learn what the tension was in the rail before cutting by placing the Vortok device on the rail at the start of the operation, setting the zero and then cutting the rail. A decrease in length of 1mm would represent a stress free temperature prior to cutting of 10° celsius above the current rail temperature.
If a rail is to be pulled up by tensors and welded, placing the Vortok device close to the weld and another close to the anchor point will not only give an in-process check on the strain achieved by the tensors but will also indicate that the stress distribution has been achieved throughout the pulling length. An increase in length of 1mm would represent a stress free temperature after tensioning of 10° celsius above the current rail temperature.
This device should be carried by every welding team and be used as a double check before the welding operation is conducted. In this way errors in calculating the pull up gap can be identified before time and effort is wasted. The unit can be applied in parallel to the other operations at the weld so will not affect the time of the re-tensioning exercise. It will however spot mistakes before possibly costly errors are made and give an extra level of confidence to the team and improve their productivity.
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