Fully automatic x-ray inspection for tire manufacturers--part 2.Automatic x-ray inspection automates decisions that, in the past, were made by operators, and offers repeatable, dependable analysis of tires according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. specific pre-set parameters. Last month's Process Machinery column (Rubber World, May 2005) introduced tire x-ray inspection and examined analog versus digital methods, isocon tubes and cameras, high resolution digital detectors and 270[degrees] panoramic x-ray tubes. The second part of this article will highlight automatic image analysis, including its many benefits and future prospects. Automatic image analysis Computer processing capability has finally developed to a point where the large data files required for automatic image analysis can be processed, stored and passed between computers with relative ease. A typical automatic tire x-ray inspection imaging system (figure 4) includes the LDA (Local Delivery Agent) Software in a mail server that delivers mail to a local recipient. See messaging system. , an analog-to-digital converter, the image acquire PC, an Ethernet switch A device that connects clients and servers to each other in an Ethernet network. See switched Ethernet. , an image analysis PC and a programmable logic controller See PLC. (hardware) Programmable Logic Controller - (PLC) A device used to automate monitoring and control of industrial plant. Can be used stand-alone or in conjunction with a SCADA or other system. . Both computers make use of dual Xeon >=2.4 Ghz processors, 1 gigabit DDR (Double Data Rate) Refers to an SDRAM memory chip that increases performance by doubling the effective data rate of the frontside bus. For more details, see SDRAM. DDR - Double Data Rate Random Access Memory memory, 1,000 BaseT ethernet integrated motherboards and hard drives. [FIGURE 4 OMITTED] Inspection flow The tire image is acquired to the image acquire PC memory for automatic analysis. The image is also displayed on a monitor for real-time viewing. The full image acquired by the image acquire PC is then transferred to the image analysis PC memory. Inspection on the image analysis PC is initiated once the memory transfer is complete. The automatic image analysis software analyzes the image and transfers the results back to the image acquire PC. The image acquire PC then transfers these results to the PLC. Real-time/post image acquisition review of tire A rotated image is displayed line by line on a monitor as data become available. Measurement/zoom/archiving capabilities can be initiated on an acquired image once full tire rotation Tire rotation or rotating tires is the practice of moving automobile tires from one wheel to another to ensure even tire wear. Tire wear is uneven for any number of reasons. Even tire wear is desirable to maintain consistent performance in the vehicle. is complete. Achieving automatic image analysis Inspections use gradient analysis Gradient analysis is an empirical analytical method used in plant community ecology to relate the abundances of various species in a plant community to various environmental gradients. to process inspections. The analysis uses tolerances of average tire specifications to sort through tire anomalies. Example: Cord analysis Set up a region of interest (ROI (Return On Investment) The monetary benefits derived from having spent money on developing or revising a system. In the IT world, there are more ways to compute ROI than Carter has liver pills (and for those of you who never heard of that expression, it means a lot). ) for the area (figure 5) to inspect in the left body ply (sidewall side·wall n. 1. A wall that forms the side of something. 2. A side surface of an automobile tire, between the edge of the tread and the wheel rim. Noun 1. area). We will call this the left body ply inspection. This area will start just inside the left turn up and span horizontally to just inside the first step of the tread belt. This area will span x number of pixels horizontally. [FIGURE 5 OMITTED] First, set up the number of vertical columns (area intervals) that will be used across the ROI horizontally. Then set up the % of maximum gradient. This will find the beginning and ending edge of each individual cord in that column. Next, set up tolerance percentages for minimum/maximum cord width and minimum/maximum cord spacing width (figure 6). The algorithm will first go through each column and find the average cord width and average spacing between each cord. The next step is to go back through each column and compare each cord and each spacing against the average cord and spacing, making sure that each falls within the tolerance programmed around the average cord width and spacing width. Each cord/space that does not fall within the tolerance is then flagged as a defect. Cord analysis is complete. The result of the algorithm will be displayed as shown in figure 7. [FIGURES 6&7 OMITTED] Other anomalies that can be detected with automatic image analysis include, in the body cord In fencing, a body cord serves as the connection between a fencer and the reel. There are two types: one for epee, and another for foil/saber. Description Epee body cords consist of two sets of three prongs each connected by a wire. area, open ply splice, open cord/broken cord, narrow body ply cord, crossed cord/doubled cord and wild wire; in the chafer chafer Any of several species of scarab beetle (most in the subfamily Melolonthinae). Adult leaf chafers (genus Macrodactylus) eat foliage; the female deposits her eggs in the soil, and the larvae live underground for years, feeding on plant roots. , misplaced mis·place tr.v. mis·placed, mis·plac·ing, mis·plac·es 1. a. To put into a wrong place: misplace punctuation in a sentence. b. chafer high and open chafer splice; in the belt, bad belt alignment, foreign material, minor dog ear (step-off), dog ear breaker splice, open body splice, open breaker splice and overlap breaker splice; and in the turn up, dog ear (step-off). Benefits No impact to cycle time The addition of automatic x-ray image analysis to the x-ray inspection system has virtually no impact on cycle time. The next tire can load and start scanning while the current tire is being reviewed. An inspected tire is held until a pass/fail decision is received. Potential cost savings Cost savings will be realized not only from one operator overseeing multiple lines, but also from scrap reduction due to process correction based on data feedback. Data feedback to production One of the major benefits of NDT NDT Newfoundland Daylight Time equipment is the resulting process feedback. Automatic image analysis provides relevant information in order to adjust the production process to maintain a high level of quality, reduce the scrap rate and minimize the cost of production per piece. Automatic image analysis should not be seen as only pass/fail decisions on individual tires, but in addition as a system analysis that can help improve and optimize the production process. Repeatability with accountability Pass/fail decisions made by operators are subjective decisions based on only the 256 gray shades that can be discerned by the operator. Pass/fail decisions made by computers are objective decisions based on pre-set specifications using all data gathered by the system. Less time is required for computer calculated decisions, and the results are consistent and repeatable. Process random tire sizes By incorporating a bar code reader See bar code scanner. into the x-ray inspection system, tires do not need to be sorted, but can be randomly sent through for inspection. Documenting quality related information such as x-ray images or test results Due to the increasing trend of shifting product liability and the associated risk to the sub-suppliers of the automotive industry The automotive industry is the industry involved in the design, development, manufacture, marketing, and sale of motor vehicles. In 2006, more than 69 million motor vehicles, including cars and commercial vehicles were produced worldwide. , archiving and tracing functionality become more and more important. The future of automatic x-ray inspection. The future of automatic x-ray inspection will be driven by customer input. Software development will focus on ways to get more information from the same image by altering and enhancing the data for better presentation. Customer input is critical to ensure development is focused on what manufacturers need most. Inspection cycle time is currently limited by the time it takes to mechanically manipulate the tire. Creative, faster methods of manipulation are being investigated. By networking multiple ADR ADR - Astra Digital Radio systems, product quality and specifications can be compared on multiple manufacturing lines. This could be used for different production lines at the same production facility or at different production facilities across town or around the world. This technology has been proven successful and is being used in the manufacture of alloy wheels. |
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