V-belt slipping - material selection?
V-belt slipping - material selection?
(OP)
We have a rotational scanner which uses a v-belt drive (2L size v-belt, 0.25in wide), and we're getting slippage on the drive sheave. The current design is at maximum tension, although we can modify the design to increase the tension on the belt. Before modifying the geometry of the tension system (bearing slides perpendicular to belt on one side between sheaves), I'd like to get some feedback on materials or other solutions.
The drive sheave diameter is 3in and the driven sheave is 9in, and we used the Gates design manual to spec the grooves.
The driven sheave (9in) requires 18 lb-ft to move at 21rpm (max speed).
Both sheaves are sealed anodized aluminum, and the belt (34in long) is rubber with polyester reinforcing cords. We understand we can increase the traction of the drive sheave by separating the pulleys more (as suggested by Gates) but this also isn't an option in the short term, and if we move the drive pulley it has to go on another platform where the belt will need to be 75-80in and I haven't seen 2L belts that length.
Is the anodized aluminum a poor sheave material? Can I improve the traction with another material?
The drive sheave diameter is 3in and the driven sheave is 9in, and we used the Gates design manual to spec the grooves.
The driven sheave (9in) requires 18 lb-ft to move at 21rpm (max speed).
Both sheaves are sealed anodized aluminum, and the belt (34in long) is rubber with polyester reinforcing cords. We understand we can increase the traction of the drive sheave by separating the pulleys more (as suggested by Gates) but this also isn't an option in the short term, and if we move the drive pulley it has to go on another platform where the belt will need to be 75-80in and I haven't seen 2L belts that length.
Is the anodized aluminum a poor sheave material? Can I improve the traction with another material?





RE: V-belt slipping - material selection?
If slippage is important, and you are the manufacturer, it may be time to help your chief designer find a job elsewhere.
Mike Halloran
Pembroke Pines, FL, USA
RE: V-belt slipping - material selection?
As for hard anodized aluminum sheaves, they should work just fine.
RE: V-belt slipping - material selection?
schaplan.
I assume the tensioner presses on the outside of the belt.
What is the wrap angle on the drive pulley?
If the tensioner diameter can be reduced and the adjustment allows, the wrap angle will increase.
Spring loaded tensioners must be on the "slack" side of the belt.
je suis charlie
RE: V-belt slipping - material selection?
Since schaplan called the product a rotational scanner, I assumed that precise, repeatable positioning of the driven element was important, as in most/all scanners, no matter what they scan or how they do it.
I.e., IMHO, they've followed the proper procedures for sizing the drive; they just picked the worst possible drive in the first place.
I could be wrong; it happens.
Mike Halloran
Pembroke Pines, FL, USA
RE: V-belt slipping - material selection?
RE: V-belt slipping - material selection?
I know a scanner can can be many things. In this case, the slippage wasn't an issue for scanning accuracy because we encoded the scan data to the driven sheave rather than using motor position. The slippage is an issue because we're adding z-axis scanning and the rotational and z-axis movement need to work in unison.
It sounds like it will be worthwhile to change the drive to a timing belt. The v-belt was convenient because it allowed the drive to slip if the part on the turntable collided with scanning hardware or foreign objects, but slipping under regular operating conditions wasn't acceptable. Instead we'll add a clutch or set the motor to stall above a design torque load.
RE: V-belt slipping - material selection?
RE: V-belt slipping - material selection?
RE: V-belt slipping - material selection?
RE: V-belt slipping - material selection?
Cogged belts have slots that run perpendicular to the belt’s length. The slots reduce the bending resistance of the belt. Cogged belts can be used with the same pulleys as equivalently rated V-belts. They run cooler, last longer, and have an efficiency that is about 2 percent higher than that of standard V-belts