Reconditioning of gear reducers for screw down drives

The Galbiati Group recently undertook a project to recondition two gear reducers for screw down drives installed in an old plant operating at Mariupol in the Ukraine.

The engineering was entrusted to renowned industry leader Primetals Linz, whilst the machines themselves are the property of end customer Metinvest Engineering LLC, also located in the Ukraine at Dnipropetrovsk.

The reconditioning operation concerns a pair of gear reducers coupled to screw down drives 2X, 100 KW at 670/42 rpm, in an assembly weighing 18 tons overall, which includes the support frame, auxiliaries, brakes, auxiliary geared motors, etc. The gear reducers consist in two symmetrical components of around 9000 kg each.

We were commissioned to carry out a full reconditioning procedure on the two gear reducers for the left and right screw down drives, each equipped with a single motor rated 100 kW, which would then be mounted to a rolling mill stand and resume their function of controlling the gap between the two main mill rolls. Both drives are governed by an electronic system with feedback control, capable of responding in thousands of a second to regulate the gap between the rolls, so that the thickness of the strip can be maintained constant.
Individual components are inspected to determine wear and deformation. Non-destructive tests, are conducted by skilled and experienced technicians, using high-precision instruments and a ZEISS MMZ-G 30 60 25 three dimension measuring machine.

Once completed, a full-speed running test is performed. Temperatures, noise levels, and vibrations are continuously measured and properly recorded.

A “Certification File” is issued for each drive, which contains the materials and inspection certificates as well as all intermediate and final inspection drive report.

The following pictures show the gear reducers during test procedures, and fully assembled in the dedicated area of the Galbiati workshops.