Replacing a mechanical conveyor with an ABB machinery drive based electronic control system doubled throughput from 40 to an average of 80 packs per minute.

A plant specialising in the growing of tomatoes was considering replacing its mechanical tomato handling conveyor system, which used inefficient chains and sprockets.  The customer was looking for a solution that would allow it to pack tomatoes more quickly and accurately while allowing quality inspection of the fruit.

Co-ordinating conveyor speeds

The speed of the conveyer must be co-ordinated with the speed and timing of the wrapper to ensure that the tomatoes are delivered to the flow-wrapper at exactly the right time.  The company was experiencing difficulties with the mechanically interfaced conveyors as their co-ordinating series of chains and sprockets are subject to wear and stretch. This caused maintenance problems, as timing adjustments had to be made mechanically, leading to production interruptions and reduced output.

Improves speed and accuracy

The replacement conveyor system designed by D&D Engineering (Hull) Ltd used ABB servo motors and ABB machinery drives to control the speed of the tomato handling conveyors, matching the speed of the packing machine and ensuring that the tomatoes are packed quickly and accurately. An ABB micro drive runs rollers on the conveyors, allowing the tomatoes to be turned automatically and inspected for quality.

The two feeder conveyors are each driven by an ABB machinery drive in master-slave configuration, with the master receiving an encoder signal from the wrapper. This ensures that the drive knows where the wrapper is in its cycle and can control the speed of the conveyor precisely to ensure the tomatoes arrive at the wrapper at the correct time. If the speed of the wrapper changes, the drive can alter the speed of the conveyor accordingly to maintain the correct timing.

Doubling the packing rate

The mechanical system was achieving a top rate of around 60 packs per minute, but with stoppages, this averaged around 40 packs per minute. The ABB machinery drive based electronic control system increase throughput to an average of 70 to 80 packs per minute.

Added benefits

Accurate co-ordination of tomato handling conveyor with the wrapping machine allowed faster packing of tomatoes while simplifying visual inspections.  In addition to the improved throughput, the electronic drive’s programmed product menus allow different products to be run on the conveyor with quick changeovers.  It was also easier to build than the previous mechanical interfaced system which used a series of chains and sprockets to achieve the necessary co-ordination.  Overall, the operation and maintenance costs were also reduced.

The ABB machinery drives can be used with both synchronous and induction motors and their modular design and flexible software make them suitable for use in a range of machinery applications, including those of the food and beverage industry, material handling and packaging.

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