Kyshtym Copper Electrolytic Plant implemented a method for determining the spiral elongation of wire rod
The new test allows us to make a conclusion on the copper purity, its chemical composition. The process takes four hours. First, wire rod with a diameter of 8 mm is drawn into a 2-millimeter wire on a drawing machine. It is fired in a thermostat at a temperature of 200°С for two hours. Under a certain load, the wire is tightly twisted into a spiral, then, again with the help of the load, the spiral is pulled out in a suspended state. Then the value of its elongation is determined on the deltamer. Copper with a high content of impurities elongates poorly. The higher the spiral elongation value, the cleaner the cathodes from which the wire rod is made. In the ideal case, this value should exceed 400 points, where each point is equal to a millimeter.
In the technical conditions, according to which KMEZ produces wire rod, the definition of the spiral elongation of the finished product is not provided. But such a requirement is included in most European standards. Since our wire rod is exported, a few years ago we started checking it for elongation, ordering the test in other organizations once or twice a year. In order to carry out such measurements on regular basis and on its own, KMEZ purchased foreign equipment: a German drawing machine, a thermostat from France and a Czech deltamer.
First, at KMEZ arrived the thermostat and the deltamer. They were installed in the Central Plant Laboratory at the Copper Rod Continuous Casting Division. The Central Plant Laboratory specialists mastered the new equipment without waiting for arrival of the drawing machine. The samples for test were prepared by the employees of the Technical Control department on an old, well-worn machine.
Due to the coronavirus pandemic, it took a little longer for the machine to arrive from Germany to the plant. Finally, it was assembled and installed in the Copper Rod Continuous Casting Division. Installers from the Russian representative office of a foreign company explained to Kyshtym specialists of the Quality Control Department how to handle the new equipment.
The machine functioning principle was clear: a wire rod sample 8 mm thick is alternately inserted into 13 drawing dies (metal parts with holes of different diameters) and pulled through them, each time noticeably «losing weight», gradually turning into a two-millimeter wire. And in order to insert the sample into the hole of the drawing die, it must be sharpened on one side.
We noticed that the dies holder, where each dies is fixed, is too far from the “jaws”, which must grab the pointed end, wind the wire rod onto the drum and drag the rest of the “thick” part of the copper segment through the drawing die – says the head of the Quality Control Department Lyudmila Chugunov.
Controller of the Quality Control Department Andrey Zuikov found a way out of the situation. He suggested replacing the dies holder, making it longer, and even sketched a drawing – in fact, he made an improvement proposal, which took on real shape in Design and Construction department. Based on the drawings developed in the department, the structure was manufactured at Remservice LLC.
With the new holder, the distance between the dies and the clamps has been noticeably reduced, – says Andrey Zuikov. – Now it has become much more comfortable to work on the machine and we manage to prepare the sample several times faster.
With the efforts of the Russian Foil factory staff and Remservice LLC, the drawing machine began to work as it was desired. Now QCD inspectors prepare 4 samples per day for further testing in the Central Plant Laboratory. The test results inspire optimism: the spiral elongation value has never dropped below the prescribed 400 points. Moreover, KMEZ and the Uralelectromed plant, which is part of the UMMC holding, periodically exchanged samples and tested each other products in their laboratories. Such an exchange demonstrated the objectivity, accuracy of estimate and confirmed the high quality of wire rod produced at each of the plants.
