This thesis presents the upgrade of the peripheral system of WaterJet metal cutting, which includes two sand hoppers with abrasive sand and a water filtration system. The purpose of the thesis was to ensure more reliable, transparent, and automated operation of the entire system and to reduce the possibility of stoppages, which cause direct financial loss.
The upgrade involved both hardware and software modifications. Three WAGO controllers were installed, each for its own part of the system – sand hopper 1, sand hopper 2, and the filtration unit. Each unit operates as a slave device, communicating with the main Siemens S7-300 PLC controller (master) via the Profibus network. Standard WAGO modules were used to connect input and output signals (750-610, 750-430, 750-530, and 750-600).
On the software side, the entire system was newly developed in Siemens Step 7, taking into account the specific operation of each unit. For sand hopper 1, logic with two sensors in the lower container was implemented, allowing automatic and reliable switching between readiness, filling, and emptying states. Sand hopper 2, due to a different construction with only one sensor, uses time-based logic. Both units also allow for manual control with signal lights (green, yellow, red) and the possibility of simulating sensor failure.
For the water filtration system, which separates sand from water, a special discharge cycle of seven chambers was developed. This part of the system operates in two automatic modes (with linear and priority-based valve opening), and also in manual mode with a safety limit of four open valves at once, which prevents pump overload.
An important part of the solution is the visualization, created in WinCC flexible, which gives the operator complete control over the system. Displayed are the sand levels in the hoppers, sensor statuses, unit statuses, warnings, and alarms. The system also logs the number of fillings, which is used for statistical purposes and maintenance optimization. With the implemented solutions, greater reliability, reduced downtime, improved safety and system transparency, and better planning of material consumption were achieved. The system upgrade has significantly contributed to the efficiency of the industrial waterjet cutting process.
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