Page 18 - CTB N12 - 2015-04

COMPANY NEWS
“State of the Art” Commercial Vehicle Tyre Development at Continental
Since the invention of the automobile, the tyre industr y has been searching for the perfect tyre. However, today, we still do not have an ideal tyre that can do everything. The laws of physics prevent this. Nevertheless modern commercial vehicle tyres are mastering the conflict of aims between low wear, quiet running, good braking in the wet and, on top of that, reducing fuel consumption. Today, customers expect truck and bus tyres to transfer high braking and accelerating forces in all situations on dry and wet surfaces and in both hot and cold conditions at any speed. They should also withstand lateral forces in curves, have good tracking and reduce diesel consumption. At the same time, they should cushion and dampen, roll quietly and be low wearing.
“No high-tech tyre can master all of these requirements equally well. There are too many conflicting criteria for that. However, all of the properties of a true all-round genius must be as balanced as possible,” says Bernd Korte, head of Product Development Continental Commercial Vehicle Tires. The large number of requirements leads to compromises in the tyre design. If his engineers from the Continental development department only improve one criterion, other product properties will suffer due to the physical
relationships.
There are around 70 conflicting aims in tyre development that have to be taken into consideration. One of the most important is the conflict between low rolling resistance and the best wet grip. The designers must, for example, create a relatively soft, flexible rubber compound for the tyre tread to ensure the best possible grip on wet surfaces. A flexible tyre clings better to the asphalt and is the best way of ensuring the transfer of power. However, the natural consequence is that wear increases. Think of the tyre as being like an eraser. The harder you press, the more crumbs you produce. Optimising a rubber compound for wet conditions will also increase fuel consumption due to the greater rolling resistance.
In the Continental development department, chemists, engineers and designers attempt again and again to cheat nature by coming up with innovative materials, tread designs and by fine tuning the tyre structure. Thanks to technological innovations, for example, new rubber compounds, modifications to the tyre design and the use of new materials, Continental has managed to reduce the rolling resistance of their tyres by about one third over the past years and, at the same time, to increase the safety-related properties considerably. The aim
is to reduce the rolling resistance by 10% in each new tyre generation without negatively influencing other criteria.
Several company departments work together on the development of new truck tyres. From the initial idea to the final product, there is normally a long road of research and testing. In the first step, the team lists the properties of the future tyre in a product specification catalogue. The requirements of the haulage industr y, current market trends and legal requirements, like the new EU label for tyres, need to be taken into consideration. The real development work begins once the targets have been set. The engineers have three factors to deal with: the tyre structure, the tyre tread and the tyre compound. The focus is on the consumer in all considerations. “Continental can only be successful if customers can be more successful with Continental tyres,” explains
properties of the modified elements. This is done above all with the finite element method (FEM) in which a tyre is broken down into countless parts on the computer. These individual parts and their behaviour can be watched and calculated separately on the screen. The computer and electronic measuring devices help develop new tyres more quickly for specific aims and speed up the necessar y tests with simulation methods. Simulation replaces practical tests to an extent, which saves valuable time and costs in development. Tyres have now become so highly developed that the development steps have become relatively small.
Without the latest technology, improvements would be difficult to determine because, for example, test series would not be reproducible due to measuring inaccuracies.
Today, modern tyre development means communication above all.
Bernd Korte.
Today, the computer is the main technical tool in tyre development. In 1985, Continental installed a CAD system (Computer Aided Design) for the first time. CAD made it possible to exchange parts of the tyre structure, the rubber compound and the tread in seconds and simulate the
The increased elimination of errors by means of simulation allows so-called “concurrent engineering”. This means that chemists, tread designers and structure specialists work on their respective areas at the same time and in constant consultation with each other. The development of the individual components for the tyre is closely linked at