Case Studies: Sensors Inspect Sidewalls
With tire specifications becoming tighter, the need for faster, more sophisticated and more accurate quality inspection for tire uniformity and appearance is critical. The sidewall inspection process, for instance, must detect all suspect products while minimizing false rejects and that often means hands-on inspection that costs time and money.
Tire manufacturers are challenging companies like Commercial Time Sharing Inc. (Akron, OH) and its parent company, Akron Special Machinery (Akron), for on-line tire sidewall inspection solutions that can identify and measure deformities such as bulges, dents and depressions as small as one- thousandth of an inch.
To meet such challenges, CTI partnered with sensor manufacturers such as LMI Selcom (Detroit) for noncontact laser-based sensors. “The sensor companies we use often specialize in vertical industries and have the experience needed to assist in the integration process,” notes Ron Symens, president of CTI. “Since LMI Selcom’s Optocator Sensors have been used in the rubber industry for two decades, we feel this knowledge is invaluable to our application and success.”
The Optocator 2201 is a relative distance measurement sensor that identifies tire deformities quickly and accurately within seconds and provides an X/Y plot of bulge, dents, depressions and the location of lettering on the sidewall. It has a sample rate of 16kHz, which Symes says made it the best choice for the Tire Uniformity (TUO) machine.”
Symens feels that the laser sensors have proven to be superior to traditional contact or mechanical followers formerly used for tire applications or even older capacitive sensors that provide outputs that change with each measurement. This is especially true on sidewalls that have letters and embossments.
“LMI Selcom sensors are not affected by surface texture, color, speed or different ambient light conditions that affect competitive units,” Symens says. “We selected the Optocator 2201 because of its performance when measuring through black lettering, lube oil or other obstacles. The small spot size of 200 microns allows CTI to filter out high frequency signals and still detect and measure the low frequency bulge and dents.”
CTI systems for sidewall inspection
CTI is a systems integration and software engineering firm specializing in multiple level manufacturing automation from software programming to factory floor systems design, installation, implementation and training to significantly increase productivity and improve profitability.
In the early 1990s, CTI received a contract to integrate its control technology into TUO’s built by several companies, including Akron Special Machinery. As a result, they developed the Tire Testing and Optimization Control (TTOC) that replaces existing controllers on 4-post tire test machines.
Recently, CTI acquired the exclusive marketing rights from Bridgestone/Firestone (BFS) to market their Tire Sidewall Inspection System (TSIS) that was developed in 1987. BFS was one of the first tire manufacturers to use LMI Selcom’s noncontact Optocator sensors for sidewall inspection in the early 1980s.
CTI’s second generation TTOC-II controller now integrates the TSIS system directly into the TTOC-II. Over the years, CTI has refined the TTOC and TSIS systems to improve cycle times, increase accuracy and reduce downtime. For instance, test cycle time has been reduced to 17.0 seconds for a complete turnkey system.
The Optocator sensors are mounted on opposing sides of an aluminum C-Frame arm. The TTOC-II/TSIS monitors the signals from the Optocators and identifies the type of depression, how wide it is at the base, the dimensions of its slopes and other such geometrics. Four thousand readings are made of each profile, with the tire spinning at 60 revolutions per second. Up to five profiles can be made during a standard uniformity test.
“One manufacturer we work with has competitive systems within the plant as well as a TTOC-II/TSIS system,” Symens relates. “The manufacturer puts all tires rejected by these systems through our system, and has found that two out of every three tires rejected by the competitive systems are not defective. Rejected tires could have cost the manufacturer thousands of dollars plus hundred of man-hours in testing. It verifies the accuracy of our system, which provides a more quality and consistent product.”
To service the TTOC-II/TSIS systems, CTI can access the systems over the Internet. Through this process, CTI can see the system operating anywhere in the world and can immediately pinpoint any problems to prevent and minimize downtime.
“This allows us to go on-line and immediately pinpoint any problems to keep the systems operating,” Symens says.
LMI Technologies USA Inc.
1. Optocator sensors are mounted on opposing sides of an aluminum C-Frame arm. The TTOC-II/TSIS monitors the signals from the sensors and identifies the type of depression, how wide it is at the base, the dimensions of its slopes and other geometrics.
2. Four thousand readings are made of each profile, with the tire spinning at 60 revolutions per second. Up to five profiles can be made during a standard uniformity test.
3. Service on the sidewall inspection system is facilitated by the Internet. Through this process, the system can be seen anywhere in the world and problems can be immediately pinpointed.