Product category:
Vision and scanning systems
News Release from: Cognex UK | Subject: Vision sensors
Edited by the Manufacturingtalk Editorial
Team on 23 August 2005
Vision sensors check tyres for defects
Industrial vision sensors now inspect the tyres on the manufacturing line and measure any distortion with complete reliability, to remove defective tyres before more value is added.
Cognex, the major global supplier of vision systems, sensors and bar code readers, presents an example of an application of industrial vision carried out at Continental located in Sarreguemines, France, for checking the quality of its tyre manufacture Tyres are key components for vehicle safety and driving comfort
This article was originally published on Manufacturingtalk on 20 Mar 2001 at 8.00am (UK)
Related stories
Vision sensors can be linked by Ethernet
Vision sensor breakthrough makes it simple to install multiple-camera inspection stations, and implement factory wide vision area networks.
Vision sensor offers faster frame rates
An ultra-high performance vision sensor that offers fast frame rates and accelerated vision tool performance.
Over time, their technology has become extremely sophisticated and their manufacture requires great precision, as the slightest distortion in fitting makes them unsuitable for use.
The Cognex vision sensors inspect the tyres on the manufacturing line and measure any distortion with complete reliability.
Vision inspection is a key part of the strategy put in place by the Sarreguemines factory.
Further reading
Vision sensor offers an even higher resolution
A new high resolution model of vision sensors offers the highest ever resolution as well as a complete range of powerful vision tools.
Buying a vision sensor: 10 questions to ask
With so many vision sensors available today, it can be a daunting task to figure out which one is right for your particular application. This guide will help you to ask the right questions.
Vision-guided robotic system for truck parts
At its Stamping Plant in Twinsburg, Ohio, DaimlerChrysler called on Cognex, Nachi Robotic Systems and Shafi to develop a vision-guided robotic system
Detecting and removing defective parts at the manufacturing stage in which they appear is a crucial competitive action.
The Continental factory is a production unit for tyres for private vehicles.
With a production of 28,000 tyres per day (almost 9 million per year), the factory produces an annual turnover of EUR 265 million.
Today the site has a staff of 1200 (three-quarters of them in production), over a floor area of 100,000m2.
As in all of the Continental Group's production centres, the products made on this site are subject to very strict manufacturing and inspection regulations.
Tyres play an important role in the safety and comfort of vehicles.
Because of this, the manufacture of a tyre has become complex.
The final inspection is particularly exhaustive in order to avoid defective products which cannot be delivered to the company's customers.
In a highly competitive environment, a final inspection of the parts before delivery (always essential in the procedure for ensuring quality) is no longer sufficient.
And all the more so since the management of the factory set up a manufacturing line inspection policy whose purpose is to detect manufacturing faults as far up the line as possible from the final inspection.
This strategy has the two-fold purpose of improving the efficiency of quality control and to generate appreciable savings from the fact that the defective assemblies are detected very early in the production process and removed before they are subject to other processes.
In this way, the application described below meets these considerations.
It is located at the assembly point of the tyres right before the firing stage and involves quality inspection of tread band fitting onto the tyre carcass.
In simple terms, a tyre is made up of two parts: the carcass and the tread band, which have to be precisely assembled before they are 'welded' together by vulcanisation.
In practice, the carcass itself is made up of several components (textile ply, sidewalls, sidebands, tread, bead wires etc.).
The process is as follows: a machine brings the tyre plies and tread bands and puts this assembly onto the carcass, making up an assembly of two cylinders, one on top of the other.
Once this has been made into a ring, it is inflated and shaped, then the assembly, which is called a 'green tyre', turns and is pressed by rollers to aid the binding.
It is at this moment that the inspection is carried out by a Cognex In-Sight 5100 vision sensor installed facing the roller and which is then able to see the whole of the tread band as it rolls.
At this stage, the tyre still does not have any tread, but the tread band does have one or more grooves.
It is very precisely the centre point of the middle groove which serves as a reference point and on which the camera will analyse any possible movement for detecting an 'offset' where the ring will be badly positioned when fitted, before or after the scheduled assembly point, or a "snaking" where the components will have 'moved' during assembly.
In both these cases, the tyre is considered defective and must be removed.
We must remember that tyre treads are the result of sophisticated research and the positioning of the various sub-assemblies is critical for the performance of the tyre.
An 'offset' produces a problem of uniformity for the tyre and consequently a lateral pull on the vehicle.
A 'snaking' makes the tyre out of balance and consequently causes vibrations on the vehicle.
An increase in mass is required to balance the tyre when it is fitted to the vehicle.
If the tyre passes the inspection, it continues with its manufacturing process (spraying, then vulcanisation).
If the tyre does not pass the inspection, the machine stops and an operator must remove the defective component before re-starting the machine to process a new assembly.
In this production stage, the operation for making a tyre requires less than one minute.
It is imperative for Continental's engineers, who have installed this inspection solution, that the time taken by the vision system to acquire and analyse the images does not have any impact on the time cycle of the process.
The second important fact was to find a precise and reliable measurement solution, as the tolerances permitted for determining whether a tyre conforms or not are very low.
The aim was to intercept the faulty tyres and to do this reliably, i e, to ensure the removal of all defective products without exception, and only the faulty products.
In their search for an ideal solution, Continental's engineers had thought about using an industrial vision system.
They approached the Solutech company (a Cognex System Integrator) to ask them to demonstrate the Cognex vision sensor systems.
It was the great simplicity of use of the Cognex In-Sight vision sensors which immediately attracted Continental's engineers.
They were very enthusiastic about the power of the vision functionalities available on this equipment, as well as the ease and speed of configuration.
"We made a good choice with Cognex, because we have been able to develop our applications ourselves, and to have them assessed according to our requirements," stated Luc Vaucelle, project manager at the Continental factory.
"The In-Sight 5100 sensors which we have chosen have a full range of tools available".
"The environment is very intuitive, it can be configured by a few clicks of the mouse and there is no need for a PC, which simplifies the connections and reduces maintenance".
"These sensors can take measurements very reliably, which is essential for our application." Another advantage of the Cognex vision systems, which is greatly appreciated by Continental's engineers, is their rugged industrial design.
In continual service for several months, the system has carried out precise measurements without deviation.
The application runs without any special lighting system, in artificial ambient light, and the sensors are remarkably unaffected by surrounding disturbances".
""The In-Sight sensors are very robust".
"If the electricity is cut for one reason or another, the system operates normally when the power is returned without us having to do anything".
"We appreciate that very much," said Vaucelle".
""The performance and the efficiency of the Cognex tools have allowed us to acquire complete control of our vision applications".
"We are very satisfied with this autonomy".
"We are now starting to update other applications, again with Cognex products". Request a free brochure from Cognex UK ...
"Cognex has now become the preferred supplier for industrial vision solutions for Continental at Sarreguemines.".
• Cognex UK: contact details and other news
• Email this article to a colleague
• Register for the free Manufacturingtalk email newsletter
• Manufacturingtalk Home Page
Search the Pro-Talk network of sites
