Downstroke Press WKP 5000 S
Downstroke Press Makes Fireproof Insulations
For the production of fireproof sound insulations for subway and railway tubes, Wickert Maschinenbau GmbH in Landau, Germany, has recently added an extraordinarily "fast" downstroke press of the WKP 5000 S type to its range of machinery. The newly installed press is equipped with a 1,200 ¥ 1,200 mm heating platen and a press capacity of 5,000 kN. It processes highly heat-resistant rubber mixtures, with blowing agents added, which later vulcanize.
The gas generated during vulcanization forms a fine foam structure in the elastomer matrix. Pressure inside the micro-size gas bubbles during vulcanization is approx. 90 bar. This is why the insulation plates expand at an explosive rate when leaving the form after the press has opened. To control this effect, Wickert furnished the press with special relief valves: the proportionally controlled fast-relief cartridge block enables sudden press opening. Compressive pre-stretching is applied to the opening cylinder prior to opening. This, together with the layout of the suction valve, enables the press to open relatively fast, i.e. at up to 400 mm/s, over the first 50 mm. Only because the press opens like lightning, the heat-resistant insulation plates can leave the mold undamaged.
The exothermal blowing agent formula for rubber foaming requires that temperature distribution inside the mold is below +1.5°C, and control accuracy is 0.1°C. This precise temperature control is necessary to achieve the desired properties in terms of flame resistance and sound insulation. To comply with the required values of temperatures over the entire surface of the heating platen, a 6-zone temperature control feature was included, which is typical of the presses by Wickert. If a heating element fails, a solid-state relay will detect and display the error on the control display. Monitoring the electric current in a non-contact way, this relay is wear-free. Two light beams guarantee optimum safety for the operators.
Wickert Maschinenbau GmbH
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