Page 20 - MetalForming March 2012

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MetalForming/March 2012
www.metalformingmagazine.com
VIBRO/DYNAMICS
vibration and shock isolation systems
Machine Control
Products
Elastomer Isolators for presses, machine tools, diecasters, injection molders, generators, etc.
Wedge Style Elastomer Isolators for plastic molders, diecasters,
presses, machine tools, etc.
Services
Vibration measurement & analysis. Leveling & alignment assessment. Installation advisory services.
is not as specialized as that found with servo feeds. The process of locating and installing equivalent-functioning straightener drives generally occurs more quickly and at less cost than that for servo feeds. In addition, little special- ized programming is required to apply the drives, and many vendors offer suitable replacement products.
Lead time to obtain replacement drives and motors for straighteners and reels generally is measured in days not weeks. In most cases, merely gathering the specifications for your equipment suffices—no need to obtain quotes from multiple vendors unless you’ll be relying on them to install the equipment.
Eddy-Current Drive Controls
Again, the risk with eddy-current drives is moderate to low, and depends on how long a stamper can afford to have a par- ticular press down. These devices allow presses to operate with variable stroking speed, through the use of a specialized motor and eddy-current magnetic-clutch arrangement between the motor output shaft and the pulleys of the belts that turn the flywheel. An additional consideration when determining risk: In a bind, a skilled technician can set up the press to run at one preset stroking speed, by using a DC power supply and a little creativity. (This assumes that the control is what fails, not the eddy-current clutch itself.)
Lead time to secure replacement eddy-current drive con- trols generally is measured in days, and they’re relatively low- cost parts. While obsolescence can be an issue, in most cases the drive controls (or equivalent replacement con- trols from other manufacturers) are readily available. In some cases, repair shops can repair old controls, although the modest purchase price of new controls may make repair a sound solution only when the stamper needs a very quick fix.
A caveat: While rebuilding eddy-current clutch-motor assemblies, may be possible, stampers can expect to wait longer than a few days for parts. Risk can escalate from low to moderate, or even to high, if the machine has a very high utilization rate and there’s no backup press available.
Ensure your supplier(s) can support the speed controls being used. If not, investigate the part numbers of acceptable replacements. Additionally, for presses with very high uptime requirements, it may make sense—considering the pricetag for replacement controls—to keep a speed controller in stock on the shelf.
Another option stampers should consider is converting to AC variable-speed drives, should the motor/clutch fail. Eddy current drives were the standard for presses for many decades, but have been steadily replaced with AC variable speed drives in the last decade. We see a lot of presses being outfitted with these drives, as there are several suppliers and, moving forward, prices and lead times for repair parts will continue to drop.
Note: Converting from eddy-current to AC variable-speed drives will require some millwright support, since the motor mount on top the press must be moved. However, performing this task fits well within the skill set of a good mechanic. MF
Coil Spring Isolators for heavy blanking press isolation, high-speed press inertia force isolation and precision machine and turbine isolated foundations.
2443 Braga Drive, Broadview, IL USA 60155-3941
Tel. 708-345-2050 Toll-free 888-523-2121 Fax: 708-345-2225
www.isolators.com
email: mrktg@vibrodynamics.com
FS Viscous Damped Spring Mounts and Elastomer Isolation Elements for forging hammers and presses.
Modular Isolation Systems.
Custom Design per specification.