Rubber presents a challenge for optical-based measurement sensors. By nature, the black surface is difficult to capture reliable data from and accurately measure. This challenge is often intensified by the complex shapes into which rubber derivatives are extruded or molded.

As a solution to this challenge, 3D laser sensor manufacturers have optimised the design of their sensors to successfully implement scanning and quality control functions for both in-process and final product inspection applications in rubber and tyre manufacturing.

3D laser scanning

Rubber material comes in two forms on the production line, either as fresh and uncured from an extruder or a calender, or as a finished product (e.g., vulcanised tyres). Non-contact 3D laser scanning offers the most practical solution for inspection of both of these rubber material types.

Here’s why:

1. The soft, gummy nature of the rubber makes contact-type measurement ineffective. This measurement approach is also too slow to keep up with the high-speeds of continuous web material production.

2. 2D sensors require complex lighting to see black-on-black contrast. In some applications the lighting is placed underneath the material (e.g., when measuring the width of a strip), and hot sticking rubber can contaminate the lights. In addition, 2D can’t produce measurements related to object geometry (i.e., 3D shape), which means they are unable to measure critical features such as object flatness, surface angles, or part volumes, and are limited to contrast-based inspection. This makes 2D sensors a poor solution for scanning complex shape-based features on dark surfaces, or for operation in low lighting conditions.

          3. In comparison, 3D laser sensors are contrast invariants and generate high-resolution scans regardless of the material or lighting conditions. They also capture the complete 3D geometry of the scan target, including critical depth measurements on surface features such as grooves in a tyre tread. 3D laser sensors are also able to achieve the high speeds required for continuous web material scanning.

Laser profile sensors provide an ideal solution to both in-process and final rubber and tyre measurement and quality control applications. Built-in measurement tools for strip positions, including multiple groove location and depth measurement monitoring with automated alignment enable engineers to configure setup parameters––without requiring any measurement software development.

In addition, the ability to store multiple geometry configurations in the sensor makes changes between different recipes quick and simple, which is critical in minimising downtime for operations that make model changes multiple times per shift.

Application examples

1. In-Process Inspection

Extrusion Profiling with High-Resolution Gocator® 2440 Laser Profiler

Extruding rubber in a specific shape makes up the tread portion of a tyre. Measurement of the extrusion profile is carried out in-process, correcting the extrusion parameters in real-time to maintain the required shape. Key measurement parameters include thickness, width, and profile. Another required sensor capability is monitoring the position of surface features, such as ridges, center lines, and edges.

Profiling these tread extrusions is done by using 3D laser sensors to scan across the extrusion, generating a profile to which built-in measurement tools and pass/fail decision-making logic can be applied.

In this example, two Gocator 2440 laser line profilers are used to measure the rubber web’s extrusion groove pattern, geometry, and location with an X resolution down to 13 microns. Gocator 2440 sensors are able to inspect multiple grooves in a single setup, and groove measurements are unaffected by changes in surface angle relative to the sensor.

Most importantly, Gocator 2440 sensors generate critical 3D height data for robust shape measurement. 2D solutions are limited to contrast-based inspection.

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3. Final tyre inspection

Tyre Sidewall Inspection with High-Speed Gocator 2530 Laser Profiler

Traditional methods for measuring tyre sidewalls for defects such as bulges and dents suffer from too many false rejects (i.e., classifying a good tyre as defective). Due to measurement system limitations, many manufacturers have no choice but to “oversensitise” their sidewall bulge and dent measurement systems, resulting in costly manual inspection requirements for all rejected tyres.

In fact, some measurement systems cannot even distinguish between bulges or dents. However, with state-of-the art laser measurement precision and advanced built-in software analysis, false positive rates can be substantially reduced and, in many cases, eliminated altogether.

Using a Gocator 2530 laser profiler the engineer is able to generate full surface point cloud geometry data in order to detect small defects (down to 28 microns X resolution) anywhere on the sidewall surface. The sensor also delivers complete scan, measurement, and control at 4 kHz, allowing engineers to meet stringent cycle time requirements––with no need for industrial PCs or external controllers.

In this configuration, two profile sensors are typically used, one for each sidewall (top and bottom buddy system). A third sensor is often used to monitor radial runout of the tread.

Leveraging 3D Laser Scanning and Inspection

Laser-based laser triangulation sensors meet the high speed and high resolution requirements for accurate rubber and tyre measurement. These sensors are used in a variety of in-process and final inspection applications, including extrusion profiling and tyre sidewall inspection.

Adding 3D laser sensors for automated quality control is vital to reducing scrap and rework, and improving final product quality by maintaining consistency throughout the tyre manufacturing process.

Courtesy of LMI Technologies www.lmi3d.com

Hankook Tire revealed the Design Innovation 2020 project, which defines a vision for the future driving and innovation in mobility.

Launched in 2012, the Design Innovation is Hankook’s R&D project held every two years, in collaboration with one of the world’s leading design universities.

Under the theme ‘Urban Reshaping’, professors and students from the Department of Industrial Design at the University of Cincinnati in the U.S. focused on the transformation of cities geared by reconfiguring mobility as part of living spaces rather than stand-alone purpose in the future with augmented automation infrastructure and cutting-edge technologies such as eco-friendly technology, autonomous driving and Artificial Intelligence (AI).

Throughout the project, modular platform of mobility concept named ‘Hankook Platform System (HPS)-Cell’ was proposed with tyre representing the root of mobility. It is applied with ‘Hankook Electric Mobility Technology (H.E.M.)’ which represents Hankook’s passion for future technological breakthroughs. Then a scenario was created which distinguishes mobility as a moving platform and its function as a pod (space), clearly elaborating that tire indeed sits at the center of the mobility.

The tyre of HPS-Cell embodied an airless tyres’ double-layered unit-cell structure to acquire complex rigidity. It is a concept tyre that uses sensor technology to not only identify tire treads and road conditions in real time, but also to respond to wear-out risks and change tread patterns according to the road condition utilizing variable wheels and optimized infrastructure.

The scenario was brought into reality in a concept film and a mock-up. The productions suggest that in 2040 urban population will be able to use this mobility platform combined with pods of various forms to each meet a specific purpose. The modular platform can also be combined with commercial pods such as urban farming to maximize the scalability and efficiency of movement within smart cities of future generation.

The unveiled productions will be exhibited at various global channels and will represent Hankook’s capabilities in design innovation globally.

Jimmy Kwon, Vice President of Hankook Tire Brand Lab said, “Hankook Tire is incorporating new ideas with our cutting-edge technology to explore design concepts for the next generation, as Hankook believes creativity is the first step towards bringing the imagination into the reality. We are more than excited to present this year’s works as they speak for the essence of the future mobility that Hankook envisions.”

TATNEFT has announced the development of a new line of ATV tyres called the KAMA Quadro ATM. The first model has been made in 25x8-12 standard size at its Nizhnekamskshina factory in Russia.

The ATV tyre, which is developed by Kama Scientific and Technical Center, has been specially designed for off-road driving, providing excellent cross-country ability in mud and snow. The tyre’s special rubber composition ensures high reliability and traction performance.

The first batch of tyres will go for pilot testing to TATNEFT subdivisions that operate off-road special vehicles.

The KAMA Quadro ATM range is currently being developed in nine tyre sizes covering 12 to 14 inches diameter, with nine more sizes coming up over the next year. The factory will begin production of 25x10 tyres for the rear axle in addition to the already manufactured  25x8 tyres intended for the front axle.

The KAMA Quadro ATM will meet the needs of the TATNEFT Group’s all-terrain vehicles used in oil fields and will also be used to equip Russian ATV manufacturers and the secondary market. (TT)

Kumho tyres have outperformed 52 rival manufacturers to ace the Auto Bild magazine’s summer tyre test with its ECSTA HS51 high-performance pattern tyre.

The annual test is among the most comprehensive of its type, the results of which are regarded as highly significant by both the European tyre trade and its consumers.

Conducted on both wet and dry surfaces, it left Kumho in a fighting third place overall. However, while the further qualifications caused the two leaders to slide down the order, 33 of the 53 entries were eliminated by the initial braking test. Kumho’s highly competitive and consistent scores in almost every discipline ultimately left it as the sole test winner.

 Awarding the ECSTA HS51 their coveted ‘Exemplary’ badge, the Auto Bild testers commended it for its precise steering response, secure wet grip, well-balanced handling, short braking distance, low wear rate and affordable price.

Unlike some tyre tests, where the products are supplied by the manufacturers, those for the Auto Bild ones are covertly purchased by the magazine from regular retail outlets. The chosen size was 205/55R16, the direct fitment for the bulk of Volkswagen Golfs and Audi A3s etc., and therefore arguably the one most common within the European car market.

UK purchasers currently have the choice of 35 sizes of ECSTA HS51 for wheels of 15 to 18 inches in diameter. The qualification round of the test was carried out at ATP (Automotive Testing Papenburg) in Germany and the other tests were performed at the IDIADA facility in Spain. 

Thus, our newly developed "Tire Leap AI Analysis" utilises advanced AI-based analysis technology to analyse (for example) electron microscope imagery of tyre rubber compounds in order to achieve high-precision analysis that far exceeds human capabilities, thereby making it possible to derive accurate estimates of rubber properties from structural data found in this imagery.

Specifically, it is a technology that estimates rubber properties precise from combining data on the individual raw materials contained in a rubber compound with data on its internal structure. In the future, we will continue to develop this technology and develop technology to estimate the future rubber properties from electron microscope imagery of unused rubber.

■ Technology to Precisely Estimate Rubber Properties Based on Structures & Materials

Tire Leap AI Analysis utilises an AI-based image analysis system to analyse the internal structures of rubber in images captured by an electron microscope in order to infer information about the properties of the rubber based on its structural data (i.e. the results of image analysis). By combining this structural data with data about the materials that make up rubber compounds, this technology is then able to derive information about the physical properties of rubber with a high degree of precision.

■ Technology to Detect Changes in the Internal Structures of Rubber After Use & Estimate Resulting Changes in Rubber Properties

By comparing images of a tyre that has never been used (i.e. that is brand new) with images of a tyre that has been used (i.e. after wear over time), this AI-based image analysis system can determine where changes have occurred in the internal structures of the tyre’s rubber and then estimate the physical properties of the rubber in the areas that have undergone these changes. The practical application of this technology will facilitate the design of new rubber compounds that are less prone to performance degradation due to wear and tear, thus contributing to the development and advancement of Performance Sustaining Technology.

Dr. Miki Haseyama, Hokkaido University: We have developed a new AI technology that is able to estimate the extent of changes in the structures based on analysis of images of the internal structures of rubber. As compiling data for this kind of machine learning would otherwise be extremely time-consuming, one of the main merits of this new technology is the fact that this AI does not require prior field data from structural changes in rubber for machine learning. Rather, this AI uses deep learning to learn about the properties of new rubber (i.e. prior to undergoing structural changes) and then estimates the extent of changes in the structure by analysing how data from old rubber (i.e. after undergoing structural changes) compares to the data that it has previously learned about new data. This approach to machine learning allows the AI to automatically detect various types of changes in the structures of rubber.

Kiyoshige Muraoka, Senior Executive Officer, Sumitomo Rubber Industries: We have been working jointly with Hokkaido University to further advance the development of AI technology that can understand how the internal structures of tyre rubber change through use. We have already put this new technology to use in the development of our latest “ENASAVE NEXT III” fuel-efficient tyres, which not only achieve the highest possible “AAA-a” rating for fuel efficiency and wet grip performance (under Japan’s tyre labelling system), but also reduce changes in tyre performance that occur over time as a result of use by half. Moving forward, we will continue to advance our Tire Leap AI Analysis technology to find and analyse slight variations in the internal structures of rubber that human senses and knowhow have been unable to detect so that we can then use the resulting knowledge to develop new technologies that further enhance tyre performance and ensure that this high performance lasts longer. In this way, we will accelerate research and development toward producing high-performance tyres that provide greater safety and peace of mind with the aim of contributing to the realisation of a sustainable mobility society for future generations.

References:

Ren Togo, Naoki Saito, Takahiro Ogawa, Miki Haseyama, “Estimating regions of deterioration in electron microscope images of rubber materials via a transfer learning-based anomaly detection model,” IEEE Access, vol. 7, pp. 162395-162404, 2019.