Spring solutions for ball valves and bearing pre-load
Saving space yet offering the same force and deflection as ordinary coil/compression springs, wave springs have proven to be real problem solvers in a host of applications. Here we look at a sealing application within a ball valve, and how wave springs can provide bearing pre-load.
When a ball valve manufacturer was looking to replace a series of small diameter helical coil springs in a sealing task, it turned to TFC and the Smalley Crest-to-Crest wave spring.
Smalley wave springs are precise flat wire compression springs that fit into assemblies where other springs cannot. Since the overall lengths and operating heights of wave springs are lower than those of conventional helical springs, they will often reduce the axial and radial cavity sizes by as much as 50%. This saving of space greatly reduces the assembly weight, raw material and machining costs allowing designers to greatly enhance the efficiency of their finished products.
In this case, by utilising the flat wire profile, the customer was able replace twelve single springs and their associated spring carrier with a single component (pictured below). Furthermore, the open profiles of the flat wire spring was far less susceptible to clogging which would prevent the helical springs from function-ing properly and lead to premature valve leak-age and more downtime.
This is one of many applications where the wave spring has proven to be a real problem solver. And there are many others. One of the most common wave spring applications world wide is a bearing pre-load arrangement (as shown above right). Having the proper load will often extend bearing life by lowering operating temperatures, reducing vibration, minimising wear and providing for a quieter smoother performance.
TFC's Smalley product, unlike a die stamped equivalent, is produced by edge winding from a continuous coil of single filament pre-tempered round-edge flat wire and does not require heat treatment after forming. As a consequence of this production method, the spring rate is consistently more accurate and the load provided at the springs' working height is repeatable across all manufactured batches.
TFC's SSB series, in sizes from 16mm to 580mm, is designed for many standard bearing sizes. Further, the ability to coil non-standard sizes without any tooling costs or delivery implications offers users total design flexibility and a size range from 6mm to in excess of 2000mm.
Standard materials include carbon spring steel, 17-7 stainless steel, 302 or 316 stainless steels but, when applications require it, springs can be manufactured using exotic alloys such as Inconel X750 and Elgiloy.
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