Application of the Month
Roller Drive and Gap Control
December, 2015 - View all Application Examples
Providing production flexibility in machinery design, to manufacture or process different product sizes for example, is becoming more of a necessity with today’s desire for shorter runs and quicker deliveries. With our consultative approach and some unique capabilities, we were able to help a recent customer achieve the flexibility he needed.
A prospect recently contacted us with interest in our spiral bevel gearboxes with hollow output shaft. His task was to feed material through two counter rotating drums or rollers. The kicker was that different material sizes where required, meaning the center distance between the rollers had to change by several inches, sometimes a couple of times a day. His idea was to insert a connecting shaft with key inside the hollow bore of two boxes. Then when the center distances had to change he would slide one the boxes along the shaft and tighten it back down.
To drive the rollers at the necessary 100-200 RPM he planned on driving the through shafts of the 1:1 bevel boxes with a servo driven speed reducer in 10:1 ratio. This would allow precise speed matching with the rest of the machine.
Our first comment to the customer was that we didn’t believe using an insert shaft with key was the best option for what he wanted to do. Because adjustments had to be made fairly often we were concerned the key would begin to show wear from the sliding action.
Our suggestion was to use a square sided spline shaft, which effectively has six or more “keys”. This shaft design is more commonly used for adjustments of distance and where key load sharing is desired. Expanding universal joint line shafts come to mind as an example where this concept is used. The spline shaft shares the load better than a single keyed shaft, depending on tolerance accuracy. We have several profiles and tolerances available to choose from.
To use the spline shaft we recommended our HWK model of hollow shaft gearbox. This is one of four versions in the Tandler hollow output shaft series. This design, along with hollow bore with keyway, hollow bore with involute spline, and hollow bore with shrink disc, provides more shaft insertion design flexibility than is available from any other bevel box manufacturer.
With only one of the bevel boxes needing to be moved to achieve the desired center distance adjustment the standard hollow bore with keyway, series HW, was actually the best choice for the stationary box. This allowed the capture of the spline insert shaft so it wouldn’t move axially as we slid the second HWK bevel box along it’s length when adjusting the gap.
To capture the spline shaft the end was turned to fit into the hollow bore with keyway and out the other side. With a shoulder on the spline side and a thrust bearing on the other, the spline was held rigidly in place.
A similar profile was added to the free end of the spline shaft to mate with the hollow bore of another of our reducer family, the WattDrive helical bevel with servo input interface, which was to be used as the main driver of this section of the machine.
The result of consulting with the customer in the beginning of the design process, and determining his needs for the entire drive design instead of just the components he expressed interest in, generated several benefits for the customer.
Instead of them going with an initial design idea that could have led to wear issues down the road, we were able to suggest a more reliable design idea. And instead of expending design and drawing creation time we were able to provide complete assembly and individual gearbox drawings and supply the main mecahanical components from a single source.
In the end the customer agreed to the design, added a servo motor and linear slide system supplied by our local motion control distributor, and had a better machine design because of it.
DieQua works with most of its customers in this manner. It’s through our consultative approach that we can be most helpful. While the products we offer are of outstanding quality, it’s the assistance we provide to best utilize them that our customers realize the superior value that is The DieQua Advantage.
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