Dec 1, 2014 in Industrial Surveying by
  • The use of Leica Laser tracker to provide sub millimeter dimensional verification on heavy engineering project
  • The use of Leica Laser tracker to provide sub millimeter dimensional verification on heavy engineering project

Hi. I Thought I would write a bit about an industrial surveying project – we are working on the construction of a Stacker Recaimer for a new coal mine in the Northwest province.

We are providing all the dimensional verification and ensuring that all the bearing housings are machined in their correct position and orientations.  The machine is some 40M long and 10 -12M wide. Accuracy requirements are 0.2mm absolute and pairs of bearings housings to within 0.05mm relative. To achieve these, we utilise a Leica laser tracker and Polyworks IMinspect software.

A further complexity is that individual components are not set level prior to construction so the coordinate system for each component has a different orientation in space. This eliminates the use of digital levels to confirm the individual shafts horizontal alignment and the use of total stations to ensure shafts are parallel or perpendicular as required.

Few onsite machining and milling services have bearing cutting shafts that are 8 m long and in this case it was therefore required to machine the left and right bearings for axis on the machine with separate cutting shafts.

We measure the bearing holes/flanges in the steel structure as initially installed. We then align the pairs of shafts in the machine axis until each shaft is centred in its correct position and the pairs of shafts are aligned along the common axis. We combine the dynamic measuring capabilities of the Laser tracker and digital dial gauges to achieve the survey accuracies required.

The great thing about Polyworks is the simplicity with which we can transform the gravity defined survey coordinate system into the machine coordinate system and can activate different coordinate systems for different machine components.  The transformation can be done through a combination of common points or alternatively by the definition of a plane, axis and point on the component.

A major part of the industrial surveying was the setting of the main slew bearing for precision milling. Each half of the bearing is 9 meters in diameter and weighs in at 69 tons.  For the milling accuracies to be met we, centred the bearing on the mill and set it parallel to milling surface to within 0.05mm. First we set a machine coordinate system to align with the 4 alignment jacks set at 90 degrees around bearing and then provided alignment values for each jack in both horizontal and vertical planes.