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FEATURE MACHINE CONTROL


Unlocking THE poTEnTial oF conVEYoRS


Choosing the right conveyor control


device can not only maximise the potential of the conveyor systems, but can help


reduce energy bills. Steve Hughes, managing director of REO UK, explains how


V


ibratory conveyors are available in two types: either those with mechanical drives, or electromagnetic conveyors.


Both distribute energy to the conveyor bed through frame-mounted drives and spring arm assemblies, creating a forward vibratory motion, which causes the product to hop along the conveyor. Mechanical drives – also known as motor


driven conveyors – typically use Variable Speed Drives (VSDs) or even Direct-On-Line (DOL), as the control method. VSDs allow speed control through increased vibration, but the vibration frequency is limited; whereas DOL control applies the full voltage and, in this case, the vibration amplitude and frequency is limited by the mechanical design of the conveyor. However,


this may be problematic as in a food processing factory, for example, too intense a vibration can cause flavourings to be shaken off the product. Electromagnetic feeders use the cyclic


energisation of electromagnets, which causes the metal trough to vibrate using magnetic force impulses. This allows for lower amplitude and more flexibility with regards to the vibrating frequency, expanding the range of products they can convey. Another benefit is that these have fewer moving parts. Vibratory conveyors are used in everything from


industrial assembly automation to food processing and packaging. Although they are generally more expensive to buy than belt conveyors, they are much easier to maintain and clean because they have smooth stainless-steel troughs instead of


user-friendly hmi has 7in touch screen


A new and easier to use Human-Machine Interface (HMI) has been added to Schaffner’s Active Harmonic Filter (AHF) solution: the Ecosine Active Sync. This is a modular product that actively mitigates the harmonics sent back to an electrical


network, reducing or suppressing disturbances by taking the harmonic current generated by non-linear loads and converting it. This is suitable for applications where harmonics levels are continually changing, such as when producing high quality products like semiconductor wafers. Ecosine delivers a solution for three- or four-wire systems, mitigating harmonics between the


phases and neutral wire. It needs to be programmed to fine-tune it to a specific application but, up until now, the traditional way of doing this has been by connecting a computer or laptop with a special cable plus associated software. At the same time, direct machine-face interaction was only possible through a 2in (5cm) monochrome display that required the user to press physical buttons to switch through the various parameters and enter values. The new HMI unit uses a large 7in (18cm) capacitive colour touch-screen. Using simple screen


swipe functions, this modern user interface makes it more straightforward to access and view all the necessary parameters – while reading and entering values where required. The HMI makes it possible to change and monitor all filter parameters and measured values of the three-phase network. It can plot up to six traces in an oscilloscope style view, and ensures all measurements are saved automatically to the built-in memory (for subsequent downloading to a USB drive if needed). With the Ecosine Active Sync used widely in


such challenging and demanding sectors as the automotive and robotics industries – as well as in large data centers and semiconductor manufacturing – simplifying the AHF’s operation and modernising how users interact with it were key factors behind Schaffner developing the new HMI.


schaffner 4 desiGn solutions MARCH 2023 8 www.schaffner.com


belts, pulleys and gears. This allows them to be used in food environments where high levels of hygiene must be maintained. Other benefits include sizing, grading, spreading, aligning, elevating and de-watering. For example, when conveying leafy greens in a food processing plant, the vibrations can shake off excess water and soil.


taking control


A control device is needed to unlock the full potential of electromagnetic conveyors, with different versions depending on the application of the conveyor. These range from simple controls that use triac or thyristors in the phase control to provide a variable voltage for the magnet, up to frequency converters that generate any drive frequency and amplitude. The precise control provided by frequency


converters means that vibratory feeders can be set at the required frequencies to convey a wider range of products. It also allows them to be used for many critical applications, like high-speed weighing and counting. There is, however, another benefit: lower


energy consumption. During a survey by Make UK, 42% of manufacturers said that their electricity bills had doubled between September 2021 and September 2022; and 52% of companies expect their electricity costs to further increase by over 100% over the next year. To help, modern control systems are much more energy efficient. As the electromagnetic feeder induces a voltage in the magnet, this can be stored and utilised. Some devices, such as REO’s MFS368


range of controllers, use an Active Front End, ensuring the input current is in phase with the applied voltage and is not distorted. This allows the product to be conveyed at up to 80% less energy than conventional control systems. Energy costs are a concern for everyone and


food inflation is a function of the raw material, the processing time and energy consumed. When conveyors can be controlled accurately and the feeders used more efficiently, throughput can be optimised.


reo t: 01588 673411 www.reo.co.uk


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