Page 24 - RHP IT

MACHINE BUILDING

The sensor inside

the conveyor belt

CONVEYORS

WHEN HABASIT, A LEADING PROVIDER OF CONVEYOR AND POWER TRANSMISSION SYSTEMS,
HATCHED AN AMBITIOUS PLAN TO CREATE AN EMBEDDED WIRELESS FORCE-SENSING LINK
IN ONE OF ITS CURVED PLASTIC MODULAR BELT CONVEYOR SYSTEMS, IT WORKED WITH
SIGNAL CONDITIONING SPECIALIST MANTRACOURT TO ACHIEVE ELEGANCE.
legant engineering is all around us. The face ID
in your phone, the keyless go in your car, the
smart speaker in your home; these devices make
Eour lives perceptibly easier. What’s not always
easy are the novel design challenges engineers must
overcome to realise these products.foods with total
traceability.
In 2018, Andrew Richardson was working as a project
manager in the plastics R&D department at Habasit, a
leading global manufacturer of conveyor and power
transmission systems, based in Reinach, Switzerland. A
large customer in the food and beverage industry had
recently come to Habasit with a query; it wanted to
measure tension in the spiral conveyor belt system on its
bread production line.
After the bread came out of the oven, it made its way
through the rising spiral conveyors to allow it to cool
before being packaged. Reminiscent of the holding pattern
sometimes used by passenger aircraft on the approach to
an airport, the spiral conveyors are a common sight in
many food production environments. They offer a space
saving way of increasing production throughput and are
also used to move products up and down between
different levels in the plant, sometimes reaching a height
of two storeys.
However, because the belt in a spiral conveyor needs
to follow a curved path, as well as a straight path, one of load-cell that clips onto the surface of the belt and antenna. The components had to be durable enough to
the biggest challenges these types of conveyors face is measures the force between the modular links. However, withstand extreme temperature changes and the wireless
tension. High levels of tension in the belt can cause it to this approach has its limitations. “The downside with this transmission had to reliably relay data through the
buckle and/or break. In the food industry in particular, this method is that it only takes place periodically as part of complex plant environment.”
problem is exacerbated by food particles from the likes of the scheduled maintenance visits and means stopping the Habasit reached out to partner with a specialist to
bread and pastries becoming lodged in the gaps between conveyor,” explains Richardson. “Secondly, the load cell support the development of the link, but initially struggled.
the plastic links. Between cleaning cycles, this leads to an that measures tension only works on some parts of the “The relationship with the first company we engaged with
increase in friction, which leads to higher belt tension. conveyor system and can’t fit through tight spaces, so you quickly fell through due to a lack of responsiveness,” says
“In the industry today, it’s common for engineers to only really get a limited picture of belt tension in the Richardson. “We then reached out to Mantracourt and hit
measure the condition of motors and pumps,” explains system.” it off immediately. This was before the pandemic, so our
Richardson. “However, it’s less common to measure the The team at Habasit came up with an ambitious plan team flew out to the UK and spent the day with the team
force inside the conveyor belt itself. It’s a very challenging to create a sensor that would fit inside a metal link that at Mantracourt, to really give them a feel for our needs.”
environment, with ovens and chillers working in close was the same shape and size as one of the existing plastic Exeter-based Mantracourt Electronics designs and
proximity to make everything from frozen pizza to cooked modular links in the belt. This special link would manufactures signal conditioning equipment and sensor
chicken.” continuously transmit data wirelessly back to a base systems, specialising in miniature high-performance
Using sensors in this environment is not easy. The station. “We knew it was not an easy design engineering electronics and wireless telemetry systems.
traditional approach involves a maintenance engineer challenge,” says Richardson. “All of the electronics had to “The link is made up of four areas,” explains Tom Lilly,
visiting the site to carry out repairs and upgrades. During fit inside the small envelope occupied by the link, application engineer at Mantracourt. “At the most basic
these visits, the engineer will also check tension using a including the sensor, the circuit board, the battery and the level, a strain gauge sensor connected to the internal

24 INDUSTRIAL TECHNOLOGY • June 2021