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Changan Automobile’s manufacturing facility in Chongqing, China, has launched two camshaft machining lines—one each for intake and exhaust shaft machining—that perform the operations while the workpieces are held vertically. Speaking of this approach, Dr. Guido Henger, managing director at EMAG Salach Maschinenfabrik GmbH (emag.com), the Germany-based supplier of the equipment, said that while the company, like many, has experience performing grinding and drilling in horizontal orientation, this approach for Changan is challenging but beneficial. As for a challenge: “Deep-drilling a shaft in the vertical direction is in itself unusual, since the bit must drill 320 mm into the component.” Among the benefits: chips and shavings from the grinding and turning operations fall away from the part, thanks to gravity.
The operation commences on two VTC 250 DUO turning centers. One of the machines mills the shaft and machines its end, while the other performs deep drilling, drills radial oil holes, and mills a marking surface. Then there are two VTC 315 DS grinding centers. The first machine grinds the shaft bearings and the second performs the grinding on the cams. Both grinding machines feature two grinding disks that contact the shaft on either side and rotate in opposite directions so that the feed forces are counteracted so that there is rigidity in the setup that permits high feedrates for faster grinding.
Transport of the work-in-process is performed via integrated pick-up conveyors, shuttles, and robots. In the dual-spindle machines, parts are loaded and unloaded simultaneously, reducing throughput time.
Overall, with turning, grinding, deburring, finishing, mounting gear wheels and quality assurance, the cycle time for a camshaft is no more than 69 seconds.