ALL-VERTICAL SHAFT MACHINING
Chang’an Automobile decided to handle the comprehensive turning, drilling and grinding work required for this critical engine part with a multi-stage production line that performs all of the machining processes vertically, a process that offers many benefits.
EMAG Salach Maschinenfabrik GmbH (Salach, Germany) has designed a large number of machining centers that operate according to the vertical principle.
The video cannot be shown at the moment. Please try again later.
During the machining process, the tool is located adjacent to the vertically positioned workpiece to ensure that chips and shavings are removed when the workpiece is turned or ground, guaranteeing stable and reliable machining.
To meet the requirements for Chang’an Automobile (Group) Co. Ltd. (Chongquing, China), EMAG had to take the technology a step further by using vertical machining to handle all aspects of soft and hard machining a camshaft within a multi-stage production line.
“We really did enter new territory with this all-in-one solution,” explains Dr. Guido Hegner, the managing director at EMAG in Salach. “It goes without saying that we have a lot of experience with horizontal grinding and drilling processes. The accompanying step of deep-drilling a shaft in the vertical direction is in itself unusual, since the bit must drill 320 mm into the component. Our goal from the very beginning was to apply the principle of vertical machining to the entire line to exploit the benefits it provides.”
The camshaft production line began in Chongqing at the production headquarters of Chang’an. The design features two almost identical production lines, installed parallel to each other for the intake and exhaust camshaft. Interlinked shaft machining is initiated with two VTC 250 DUO turning centers.
While one VTC 250 DUO mills the shaft and machines its ends, the other carries out deep drilling, drills radial oil holes and mills a marking surface.
Two VTC 315 DS grinding centers then perform all necessary grinding steps, where the first center grinds the shaft bearings and the second executes out-of-round grinding on the cams.
What really sets these machines apart, however, is that they integrate two grinding disks that contact the camshaft on both sides and run in different directions. Feed forces are counteracted by the opposing arrangement of the grinding disks.
This design is beneficial in more than one way. First, the rigid bracing facilitates extreme grinding feed rates for a camshaft. The time saved here is then complemented by the two disks, which further reduce machining time.
The technology is also the key to enabling the distinct automation efficiency of the entire line for all turning and grinding processes. Integrated pick-up conveyors for the turning centers remove the components from a shuttle and place them on a different shuttle. Transport then continues.
Inside the grinding centers are robots that secure transfer of the workpieces from shuttle to shuttle. “Coolant is also supplied throughout the entire plant in a very efficient manner,” adds Hegener. “The fact that the two lines for the intake and exhaust camshaft are close to each other and are almost identical in design made it possible to combine the cooling supply for their machining centers. Only two systems are used to clean the coolant.”
One system supplies coolant to the turning centers of both production lines, while the other cools all grinding centers – an effective solution that also decreases investment costs.
The downstream production sequence for machining the camshaft also includes a series of systems which safeguard component quality by crack testing and measuring as well as finish components so that they can be installed by washing them and applying a protective coating.
Two turning centers, two grinding machines, a deburring and finishing process, an additional machine for mounting gear wheels and quality assurance measures – no camshaft takes more than 69 seconds to complete each of these steps during production.
How can such short cycle times be maintained?
“Several factors come into play. The synchronous support grinder, for example, has two grinding disks to expedite rotary grinding. The same applies to the 4-axis turning assembly. Downtime is also minimized, since parts are loaded and unloaded simultaneously,” explains Hegener.
Chang’an profits from an efficient solution that ensures very high component quality. The all-vertical machining helps safeguard process reliability as well.
EMAG LLC, 38800 Grand River Avenue, Farmington Hills, MI 48335, 248-875-0313, Fax: 248-477-7784, www.emag.com.