These SR-Schindler treated products are then conveyed back to the Hess packaging line. The value adding line is designed to grind products with working widths of up to 1200 mm and thicknesses ranging from 40 – 180 mm. Handling equipment such as layer pushers, drum turning devices etc, can handle even small stones 100 x 100 mm without any problems.
The complete SR-Schindler plant consists of a drum turning device before the calibrating machine for turning the paving layers, respectively tiles from the first to the second layer side, a SR-Schindler calibrating machine with 2 stations for milling the base mix side, a drum turning device for turning the products to the first layer side, a high performance 6-station grinding machine, the bypass chamfering machine in angular execution, a drying track and a shot blasting machine. After shot blasting, the layers can be visually inspected and taken offline. A layer with 2nd choice products (the layer gets marked with small plastic block by the operator) can be taken out of the line with the Hess cuber and stacked separately. After the visual control a layer pusher transports the 1st choice stone layers on a belt conveyor, where they get picked up by the Hess cuber and transferred to the Hess packaging line.
Calibrating, grinding and chamfering machines can operate in wet mode. Each station on the calibrating machine, consisting of 15 diamond milling segments, can mill between 1,5 to 2 mm off each product layer.
The first 3 stations of the grinding machine are equipped with diamond milling segments to achieve smoothening. The other 3 stations are equipped with Steckfix fast exchange grinding segments. All treatment tools can be frequency controlled as required.
The conveyor of the grinding machine is made of grey iron steel with high-precision ground manganese steel plates and multilayer armoured Siegling belts resulting in a constant and smooth motion of products on the conveyor. The tunnel segment construction with tool spindles double mounted in pillar guides, adjusts to the required performance and allow all usual grinding levels of hard and soft stones, small and big grain in the first layer whilst keeping tooling and energy consumption costs to a minimum.
All SR-Schindler processing machines are adjustable to the individual product type via the control panels or by the B&B operating and monitoring systems where the individual products parameters are inputted. Passage speed, treatment speed, pressure, height adjustment, as well as the number of working stations in operation can be set for every single product in consideration of its age, the hardness of the aggregates, the individual mixture and the expected appearance.
The chamfering machine, executed as bypass with angular devices, consists of two treatment bridges each with a chamfer milling station on the left and the right side. That way the treatment of all 4 sides in continuous flow is achieved. After chamfering the products get visually controlled and 2nd choice products, also marked with small plastic blocks, get separated by an angular device with V-belt conveyor for manual offloading.
A high performance drying track with special fans makes sure that the products are dry for subsequent processes i.e. shot blasting.
Products not requiring chamfering, bypasses the chamfering line and is transported (via layer pushers) to the drying track and subsequent shot blasting machine.
The shot blasting machine is equipped with 2 high capacity turbines, 18,5 kW each. A perforated rubbered transport belt transports the tiles and stones (products) through the machine. At a working width of 1200 mm tiles and stones up to a height of 400 mm can be treated. The turbines projects steel abrasives at high speed on the products to clear the surplus cement and to expose the aggregates. After treatment the abrasive material (shot) is recycled back into the dedusting zone where the bucket elevator induces gravity separation. Here the reusable abrasive material and cement dust are separated. The “cleaned” abrasive material then returns back to the machine.
Due to the Australian Standards on noise regulations, the calibrating, grinding , chamfering machine, drying track and shot blasting machines are fully encapsulated with sound proof panels. The complete plant consists of 19 safety zones with separate main switches each termed as form 4 switchboards. All wires in the 16 switchboards and in the terminal boxes are labelled with single conductor labelling. All switchboards as well as the Hess control system are placed in a separate, air-conditioned control room. All safety components are equipped with call back contacts to the PLC, where defective components can be immediately identified. 3 Safety Control PLCs communicate with each other via Ethernet. All safety doors (24 items) have a Fortress lock switch. Drives with centrifugal mass are equipped with standstill monitors.
To save energy costs, all drives with a power beyond 22 kW are equipped with a network of energy recovery converters.
Special features of control system
By means of product data tracing, every product carries its article number and processing date throughout the complete value adding line. This data is handed over to the shift register and signal exchange (Hess plant), which gets printed on the individual product pack.
With entering the article number the recipe management can be loaded automatically. Therefore several formats can be treated in the line at the time. If there is no automatic change possible, the product will be stopped in front of the relevant area and necessary modifications are displayed via visualisation. Once these modifications are done, the quit button is to be pressed and the line continues operation automatically. Via a complex height measurement the calibrating and grinding machines are self-adjusting to the new height and a higher or lower layer can pass the machines without operation stop. The individual electric controls are connected with the firm network via Ethernet. Therefore production data can be seen on every computer and in the internet. The Internet is also used for remote maintenance of the line. For fast response there are more than 5000 error messages. Every movement in the line is controlled chronologically. All manuals and maintenance plans are integrated in the visualisation. During maintenance only the plans relevant for the area under maintenance get opened and thus no time-consuming search is necessary. For easy orientation the complete visualisation is in 3D format. For every parameter change in the line three levels with upper and lower limits were defined in the visualisation. That way also the machine operator is able to make small changes.
With its high level of safety and advanced technical control features, the SR-Schindler value adding line can be customized for Australian companies.