Product category:
Ultrasonic and Clamp-on liquid flowmeters
News Release from: Barksdale Control Products | Subject: Barksdale UQS 7 at Kuka
Edited by the Processingtalk Editorial
Team on 21 June 2006
Ultrasonic flowmeter monitors robot
welder cooling
Production line spot welding electrode coolant flow on Kuka robot systems is monitored using the Barksdale UQS 7 ultrasonic flowmeter
Kuka robots in Augsburg are known worldwide for robot systems Kuka has a large manufacturing facility with a hundred stand alone systems in an assembly hanger
This article was originally published on Processingtalk on 3 Dec 2004 at 8.00am (UK)
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For high volume vehicle manufacturing operations, welding robots must complete their tasks in a short time: for example 30 seconds is allowed for 40 spot welds.
It is therefore really no wonder that Kuka works constantly on their systems to find extra "split seconds" within the total cycle and to realise any time saving possible.
One factor is to ensure the even closing of the spot welding electrodes, which must meet the point of weld with a given contact force.
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This is achieved by either pneumatic or now most commonly using servo-electronic adjustment.
Another factor is the cooling of the welding electrodes and the ambient cooling on the robots.
The coolant at the welding electrodes and the first part of the "welding head" is absolutely necessary to dissipate the thermal load of the high currents used during welding.
The copper electrodes used do wear during operation, and require to be changed regularly.
"If the heat doesn't dissipate, the wear will be higher", commented Dr Jacob.
Therefore to reduce the heat, between 6 to 8 litres per minute of coolant flows through and around the welding electrodes.
The Barksdale UQS 7 is installed into the cooling system to provide measurement and control of the cooling fluid.
The factors that convinced Kuka to install the UQS7 were the flow range of the ultrasonic sensor, which is capable of flow measurement from 0.04 to 10 litres per minute.
Also the compact construction, fast response time, remote signalling of coolant flow and the ability for customised programming were important features.
Under normal operation the UQS7 signals into the control system for the spot welder and robot.
Using specially developed software, at the start of the robot cycle, when 0.2% of the normal coolant flow is reached, the UQS 7 signals the robot control that "Coolant is present", to allow the robot to move into place and reach the position on the line.
The UQS7 checks the correct flow before the final position.
If it is OK, the robot begins with the spot welding and if not, it would be stopped.
This method of approach results in seconds being saved during the production cycle.
A further major security feature provided by the UQS7 is the detection of any faults developing in the cooling circuit.
It is possible that during production the welding electrodes may become dislodged or attached to a work piece at the welding station.
This is rare, but if the cooling circuit is ruptured it is critical to ensure coolant does not flow into the production environment, and flood the floor - with the inherent dangers this may cause, resulting in a possible production shutdown.
The UQS7 recognizes any absence of liquid or absence of flow, identifies that there is a problem in the cooling process and switches off the supply of coolant within a second, preventing further coolant escape.
The use of magnetic shut off valves enable the short response time of the UQS7 to provide a short turn-off time.
In addition to the UQS7 flow sensor, Barksdale provides the equipment used in the rest of the cooling unit installed in the periphery of the robot system.
In this unit, Barksdale has integrated an accumulator which collects the water from the complete piping system, when maintenance for the cooling system or replacement of the welding electrodes is required.
The accumulator is a special development from Barksdale for which a Patent has been applied; it allows the collection of water, and avoids any air bubbles in the refilling process of the cooling circuit.
Barksdale has worked with Kuka to develop the whole cooling system, assisting the robot manufacturer with the flexible products and an ability to be a system deliverer. Request a free brochure from Barksdale Control Products ...
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