Reduction of Energy Consumption and of Carbon-Dioxide Emissions with the “Micrometric Plate Mould Recovery”
The international market is increasingly asking companies to develop innovative and sustainable solutions aimed to maximum energy and raw material savings, in strict compliance with the current regulations on environmental protection. In this scope, Bongioanni Macchine/IT developed a plate for the recovery of the wear of the moulds, to be applied on the presses, to avoid the production of roofing tiles with different thickness.
Generally, a number of higher moulds are used on the presses in a 1: 6 ratio compared to the lower moulds, in which the replacement procedure is as follows:
• Replacement of the top moulds and parallelly of the bottom moulds of a drum face of each press;
• This operation is repeated each 2 top moulds replacements (= 4 h after the previous face).
Within 24 h you practically renew the complete drum. This implies a reduced bottom mould quantity (50 for two presses with 3 moulds), but the consequence is the risk to obtain a remarkable weight difference among the produced roofing tiles (for instance, among the roofing tiles made from the moulds of face nr. 1, which have just been replaced, compared with the roofing tiles produced with the moulds of face nr. 6, which are 20 h “old” in their functioning).
An alternative used in other roofing tile factories consists in making one stop a day only, and during this stop all bottom moulds of the drum are replaced. This allows a bigger control linearity of the products’ weight and thickness, exploiting all features of the top mould support plates for gypsum recovery.
These tools are equipped with a strong wedge system, moved by a SEW gear motor, which operates a precise endless screw system. On the opposite side of the gear motor there is an absolute encoder, granting a micrometric movement precision, giving the opportunity to check the vertical position of the top mould at a decimal level. The quote adjustments can be made by the press operating staff, by acting on the press operation panel in both manual and automatic modes, setting the desired correction (expressed in tenths of millimeter). The software will carry out this correction after the stroke range that was set on the operation panel.
This way, it is possible to reduce the weight difference among the products, where ±100–150 g variations (= from 200–300 g for each roofing tile) are usually accepted, reducing this to ±50–60 g (= 100–120 g maximum difference).
Obviously, these results can be achieved working in parallel on constant weight checks by the press operators and in the gypsum department as well, where it is necessary to pay a particular attention to the realization of the bottom mould-tools (conditions of the matrices and of their coupling trays, wear and tear conditions of the moulds, etc.).
Thanks to this system, it is possible to achieve a considerable energy saving during the drying process of the roofing tiles, since the timing will be reduced (the roofing tiles will all have the same thickness), eliminating the waste of raw material (clay).