Mill n' Mix
Coldcurve Ltd. was approached by Mill ‘n’ Mix regarding the design, supply and installation of a control system for a grain bruising lorry. The system was originally controlled by a series of push buttons, limit switches and solenoids for the control functions, and mechanical balances for the weight function.
The client requested a number of functions to be carried out by the new system that was previously not available with the use of the original manual control system.
The system was required to automatically control and monitor the bruising, weighing and batching system mounted on the back of a lorry and provide easy adjustment and display of parameters, set-points and operations. It was also requested to design a system of control that would be more accurate, user friendly and productive than the previous system.
The decision was taken to supply and install a bespoke Automatic Grain Bruising and Batching Control System. Designed, programmed and built exclusively by Coldcurve Ltd. that caters for all the requirements of the client.
Systems of this type which rely on human input in this way is inevitably going to result in inaccurate counting due to the fact the operator has a number of responsibilities other than keeping count.
The original system of control was very basic and the process of operation resulted in it being time consuming, laborious and unable to perform all the functions requested by the clients of Mill ‘n’ Mix.
This system processed grain and distributed it to a hopper mounted on the rear of the lorry, with the process being stopped once the hopper was full and during emptying and restarted once emptying was complete. Batch functions were carried out manually, with the operator keeping count of the amount of product processed and manually switching the machine off prior to switching the feed to a different product.
Prior to the installation of a new control system, the lorry was due to be partly dismantled and refurbished. This gave Coldcurve Ltd. and Mill ‘n’ Mix the chance to conceive alterations to the mechanical process to improve the overall performance of the machine.
We suggested the addition of a second hopper with a suitable butterfly valve between the two hoppers, the use of loadcells for weighing duties and the use of a touch-screen HMI for display and control (the use of two hoppers enables the machine to continue to operate and process grain as a finished load is being emptied).
A small control panel, housed in a GRP enclosure manufactured and, using Mitsubishi PLC and HMI kit, a programme of control was conceived and written.
As a result of carrying out previous projects using loadcells, the integration and sourcing of suitable loadcells was straightforward and prompt. Upon installation of the control panel and associated components, the entire electrical system was refurbished, replacing all wiring, sensors, solenoids, controls and indicators. Alarms and beacons were integrated into the new system of control to indicate to the operator when a pre-set function/batch has completed.
With all of these measures implemented and accurate, efficient and user –friendly system of control was created, with the productivity of the machine estimated to have been increased by 100%.
It also enables the operator of the machine to carry out other duties such as maintenance and liaising with the client whilst the machine operates.
The use of the loadcell weighing system has considerably improved the accuracy of the system and with Mill ‘n’ Mix charging by the total weight of product processed it has had a positive effect on profit margin.