Product category:
Adhesives and adhesive bonding equipment
News Release from: Hoerbiger-Origa | Subject: Proportional pressure control valve
Edited by the Manufacturingtalk Editorial
Team on 20 June 2005
Piezo-electric devices direct glue
application
Piezo-electric technology is ensuring quality in ultra high speed envelope manufacture by adjusting the amount of glue laid onto the seams and flap, relative to materials porosity.
Piezo-electric technology is ensuring quality in ultra high speed envelope manufacture by adjusting the amount of glue laid onto the seams and flaps in line with the porosity of the paper Envelopes are typically manufactured at 1200 per minute, i e, in less than 0.05s each, and the amount of glue used is critical
This article was originally published on Manufacturingtalk on 19 Apr 2004 at 8.00am (UK)
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Too little and the envelope will fail; too much and it may look unsightly or fail to open fully, while wastage of an expensive material soon mounts up.
But frequent batch changes are a characteristic of the industry, with each batch likely to use a different paper stock than its predecessor.
So when Universal Adhesive Systems of Daventry, UK, were refining the ITW Dynatec Cold glue application system, a high performance switching arrangement was identified as key to success.
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Technical manager Andy Hart reviewed existing solutions using an E-P (electric to pneumatic) converter, and decided he needed innovation to advance the state of the art if he was to succeed.
Hart called in Terry McFegan, who after some consideration suggested the use of Hoerbiger-Origa's piezo-based intelligent proportional pressure control valve, Airfit Tecno.
As the glue is a cold formulation, it is preferable to use a fixed orifice dispense head, and so varying the laying quantity is achieved through adjusting the pressure.
A 12:1 ratio piston pump running at 2.5 bar supplies adhesive to a pressure regulator at 30 bar.
This high pressure is then transmitted to the Dynacold Application heads where it is then applied to the envelopes.
The parameters for production of the envelope are then fed into the 2008/4 Electronic Pattern Controller, which is situated on the envelope machine.
Therefore as a batch change occurs the controller signals the Airfit Tecno to adjust the pressure by a specified percentage of the maximum level to suit the new envelope size.
The glue pressure is ultimately variable between batch runs but constant throughout each run, therefore the glue laydown is constant.
Airfit Tecno was chosen because it has several advantages over other solutions.
Its combination of piezoelectric technology and precision miniature component engineering completely redefines user expectations for speed and precision of air pressure control.
Smaller than a computer's mouse, Tecno can handle a flow rate of up to 380 litres/min, more than enough for Universal, while providing pilot, main pressure regulator valve and electronic controls in a single package.
At its heart, instead of conventional solenoid technology, is a piezo chip which functions as a continuously operating 3/2 way pilot control valve.
By applying a variable signal of less than 0.25W to a cantilevered piezo element between inlet and outlet, the control airflow may be varied.
The output pressure control signal is then amplified via a diaphragm mechanism to control the main pressure regulating valve.
Tecno is supplied with an extruded and anodised aluminium body.
This provides increased rigidity and robustness, eliminates the need for surface coatings and is aesthetically attractive.
Control air consumption is less than 0.6 Nl/min, ensuring quiet operation, a significant advantage over solenoid-operated.
"Tecno has a reaction time of less than 7ms, effectively instantaneous response and enables the output control to be cycled at speeds in excess of 40Hz," says McFegan.
"And it does not compromise speed for precision, as the output accuracy is also maintained to within 0.2%".
"Responsiveness to highly dynamic situations make Tecno the perfect choice for applications, like Universal's, in which precise pressure profiles are required." The Tecno's small size, low power consumption and excellent responsive properties made this valve the best choice for this application.
"The fact that Tecno does not need an additional power supply actually proved to be crucial to the final design," Hart recalls.
Universal also have plans to use the Tecno on its hot melt piston pump units. Request a free brochure from Hoerbiger-Origa ...
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