Product category:
Electric Linear Actuators
News Release from: Hoerbiger-Origa | Subject: OSP-E belt drive actuator
Edited by the Engineeringtalk Editorial
Team on 25 October 2004
Sweet solution to a sticky situation
A high speed reciprocating cutter based on a Hoerbiger-Origa servo actuator has completed 2.5 years of trouble-free operation on Trebor Bassett's nougat production line.
A high speed reciprocating cutter based on a Hoerbiger-Origa servo actuator has completed 2.5 years of trouble-free operation on Trebor Bassett's nougat production line, having replaced a first-generation system that worked at half the present speed Nougat is notoriously difficult to cut due to its density and stickiness and it is not that long since it was cut by hand
This article was originally published on Engineeringtalk on 28 Jul 2005 at 8.00am (UK)
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A high speed reciprocating cutter based on a Hoerbiger-Origa servo actuator has completed 2.5 years of trouble-free operation on Trebor Bassett's nougat production line.
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Trebor Bassett's original attempt at automating the process was a major step forward in reducing production costs.
Significantly the consistent accuracy of the equipment addressed the issue of product give away, which erodes into the confectionary industry's already tight margins.
This system cut 50 to 70 bars of nougat per minute from a continuous ribbon extruded from a special mixing machine.
These were separated from one another and transferred to a wrapping station.
Although it was a significant improvement on the original cutting methods it gradually began to need more and more maintenance.
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Hoerbiger-Origa's pneumatic solution is clean and precise and costs one third of the equivalent stepper motor solution.
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When head office asked the production engineers to double production speed they decided that a whole new system would also address the now-regularly recurring breakdowns.
The engineers, Steve Barker and Gerry McDonough, decided to call in linear systems expert Nigel Smith from Hoerbiger-Origa and brief him to deliver a turnkey solution.
"The design principles of the existing system were fine, it just simply could not cope with the duty to which it was subjected", recalls Smith.
"The obvious thing to do was to beef up the system with higher capacity components and to improve its structural strength".
The mass to be moved weighed in at 25kg and the cutting length was 220mm.
An enclosed belt driven actuator was the obvious choice for the drive mechanism and due to the high dynamics of the application, Smith recommended the heavy-duty version of Hoerbiger-Origa's OSP-E belt drive actuator.
He decided to support the load on a pair of guide rails, each fitted with roller cassettes so that there was no extraneous frictional load.
He also used an over-long cylinder and mounted linear decelerators at both ends to eliminate any potential for shock loading during operation.
"In some respects the solution adopted the old Victorian principle of over-engineering", explains Smith.
"In this case the only downside to over-engineering was a slight increase in cost, but this would be quickly recouped by increased productivity, we were planning on doubling the cutting speed to 100-plus cycles per minute and also to design out the hidden expense of equipment failure and downtime".
There was however one area where this principle could not be applied.
Calculations suggested that the servomotor used to drive the actuator would run hot and some test runs proved this to be the case.
Smith considered several options including water cooling and forced draft ventilation but in the end went for another simple solution of using a Control Techniques' 115UMB motor because its compact size left plenty of room for air cooling.
This led to the choice of CT's Unidrive with UD70 motion controller and CT/Origa LiPos linear positioning software which allowed continuous reciprocating moves with all the position, stroke, acceleration/deceleration ramps, speed and dwell times to be stored in the standard software.
Simple inputs provided by relays and switches controlled cycling until stopped by the operator or by any of the safety interlocks built into the system.
The final component in the drive chain was an Alpha LP90 5:1 gearbox fitted between motor and actuator.
Smith had used this product before and was confident of its abilities for this project.
With the design finalised in principle Smith tested his system under the most realistic situations obtainable.
It was here that he realised just why the previous system had proved unreliable.
Starch dust was present everywhere and it wasn't long before it had worked its way into the various components.
Rather than tackling the problem with bellows seals or forced air drafts, which would have increased both costs and the space envelope of the system, Smith's solution was again the essence of simplicity, by fitting standard mountings from the OSP range, the actuator assembly could be inverted so that the dust could not settle on sealing surfaces, eliminating the chance of any migration to the internals of the actuator.
"This worked a treat and was the sort of simple engineering solution that the Victorians thrived on".
"It's very easy to be seduced towards high tech solutions for everything, but often we can learn from the experiences of past masters too". Request a free brochure from Hoerbiger-Origa ...
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