The Czech marmalade manufacturing company began to test new recipes due to the desire to expand sales and the brand's recognition. The company encountered a problem, as they found that existing machines do not meet the cleanliness standards and are economically inadequate since they are completely non-automated. Two solutions were available: the purchase of a unique machine capable of cooking various types of marmalade in a short time and as independently as possible, or the retrieve of existing machines, as they do not have adequate space for the new one. Depending on the desire to expand production and the European funding, they decided to order a unique automated machine.
An automatic cooking machine for marmalade, which is a unique Slovenian product made of stainless steel and was constructed with the ENOOP hardware installation company, consists of a boiler, valves and pumps for heating and cooling, valves for dosing of necessary materials, valves and pumps for washing, homogenizer for mixing and passing the product and a set of temperature, pressure and position sensors. We built the device as almost completely automated, because it is capable of introducing the necessary substances into the boiler itself, mixing it, cooking it and then emptying it onto the filling line. The entire interaction between the user and the machine takes place through the Siemens touch screen, which enables the user to learn faster and easier to see over the work.
In the project we used quite a few electrical elements, which are essential for the operation of the machine. The programmable logic controller, which is powered by a rectifier, is the core of the project, because on the basis of information obtained from the temperature, pressure and position sensors, it forms the output signals that open and close the valves, they change the speed of the rotation of the motors and inform the operator of the state of the device. For controlled rotation of mixers, pumps and homogenizers, we included frequency converters which are protected by bimetallic motor protection against short circuits and overloads. The valves were controlled using relay logic. The vacuum pump is controlled and protected by means of motor protection and contactor.
During the coordination of project, details between the client and machine designers, we came to the conclusion that complete automation due to spatial distress and lack of funds is not feasible. The user must enter the quantity of the substances entered, the temperature and the cooking time, the method and the rate of mixing, etc. We found a number of shortcomings in testing the device. The sensor calibration of the end position of the lid is very demanding and takes a lot of time. The forks that measure the presence of water in the pipes in front of the pump are not properly designed, as the marmalade is residues on them. In case of too viscous marmalade, mixing should not be stopped, as the PLC can reactivate the frequency converter when the mixer is switched on again.
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