Meat pickling machine - continued
During the pickling process water stored in the tissue of a piece of ham is removed by a salt mixture or brine to create unfavorable living conditions for micro-organisms. At the same time the cooking salt mixture saltpeter is used to activate enzymes and the growth of bacteria. These additives also ensure the delicate texture and the red coloring of the pickled ham. This process has been used as a general rule up until today: Over 90 % of all the processed meat and sausage products are pickled. The technological breakthrough in comparison with old method of stacking and storing and turning goods marked the development of fast or short pickling by the inoculation method. Twenty-two-percent brine is injected with fine needles directly into the muscles and veins of the meat. After being injected the ham is stacked in a closed container held down by weights and stored until the required concentration of salt to give the meat its red color. The first automatic pickling machine, which simplified and accelerated the mechanical injection method was designed and built by Rühle in 1970. Compared with present day technology this machine has only little in common with its predecessor: In the top model of the current series, the IR 56 pickling centre, all processes are carried out automatically. With ever increasing finer injection needles and more and more dynamic drive and control technology, the needle field on every machine model can be compacted and the individual movements accelerated to ensure an ever faster and more uniform distribution of the brine in the tissues: The IR 56 incorporates precision measuring technology, ten adjustment drives, 56 needles and achieves up to 80 injections per minute. The machine is equipped with a box lifting system and is provided with a 350-mm wide bearing surface for convenient operation even at maximum capacity: Up to 5 000 kg ham can be pickled per hour. All functions of the center are operated by a touch display connected up to a Linux-PC. All the working steps from mixing the brine to the injection process and preparation of the circulating brine are continuously monitored and recorded. The measuring technology directly registers the deviations from the desired values and the necessary corrections are made automatically to the greatest extent. The self cleaning facility ensures optimal hygiene and travels all the moving parts into a suitable position to clean the system under high pressure.
Control technology
Basis for the manifold functions of the pickling centre is more especially the highly efficient control electronics in the background. Amongst other things this electronic control system allows highly dynamic pump operation as well as automatic single needle operation. It was this real time control system with CAN interface, which made it first possible to realize the full range of different injection techniques and sequences. The mode of operation selected by the user refers to the machine control system provided through a PC with which it is connected by means of a serial interface.
The PLC is integrated in the conventional bus coupler, which according to IEC 61131-3, can be projected with structured text, list of instructions, function and contract plans as well as the sequence language.
The PLC is fully multi task enabled to make it possible to define the number of partial tasks to different cycle times and priorities. Up to eight extension modules can be connected up directly to the control system. The modular element box offers freely configurable panels apart from the standard-24 V-I/Os in eight and 16 unit blocks. Analog channels are available for all types of current and voltage I/O signals. The PLC is suitable for networking via CAN. The device also permits connection of function models for temperature control, positioning tasks and counters apart from the digital and analog inputs and outputs.
Moreover, these also relieve the control system through own computing power. As far as Rühle is concerned the open concept of the PLC and its extension has proved successful in several machines.
