Tips & News - Jan. 2016

THE REDESIGN IN 3D It became clear we needed a modified clevis, and since none were available, we were going to have to design our own. Our initial planwas tomake some small modifications to a standard clevis. However, it became obvious that was not enough. Mark Hamer, Standards Specialist for Alliant Energy, and I did some brain storming and came up with about a half dozen different designs. We then approached three manufacturers to see if any would help finalize the design and manufacture the modified clevis. One of the people we talked to was our Hubbell territory representative, who put us in touch with Jim Smith, a Hubbell product manager. Smith got back to us quickly and we were delighted that Hubbell was willing to get involved. Jon Wilson, Engineering Manager for New Products, Hubbell Power Systems, explains, “At the end of 2011, we heard that Alliant Energy needed a modified version of one of our existing clevises. The orientation needed to be rotated 90 degrees and it wasn’t going to work exactly like our current clevis did. Also, there needed to be enough room between the side of the clevis and the pole to be able to insert the cotter pin in the end of the upset pin. We got to work on the design.” The evaluation and fitment process was expedited through the use of 3D printing. Hubbell has two 3D printers that are used to make models/prototypes of parts. “We can print something in a day and send it out the next day for review. We also use the printers to make marketing samples and we can create miniature versions of different assemblies and parts. This is useful because it provides a good representation of what we have and our sales people don’t have to carry a 100 pound part around with them,” continues Wilson.

Since the 3D printers can create parts about 12" x 12" x 15", Hubbell was able to send full-size sample clevises, made from acrylic, to Alliant Energy for evaluation. This saved time and money, since expensive dies did not have to be fabricated to make steel prototypes. “The changes weren’t that big and we quickly sent out a sales drawing andmade 3-D print for them. A few rounds of back-and forth and we had a new clevis for production,” explains Wilson. Version One—August 2012: The first version of the new clevis had an offset leg, to prevent the bolt from digging into the pole. But, this design had the mounting slot which ran from the top to the side of the clevis and was a carryover from the previous threaded clevis design. The one drawback of having this type of mounting slot was that a washer was needed, under the head of the bolt, to keep the bolt positioned so it would hold the clevis tight to the face of the pole. Alliant Energy received a shipment of the newly designed clevises in January of 2013 and began installing them in the field. We got feedback from the field and shortly came up with a few ways the new design could be improved. Version Two—May 2014: By 2014, Alliant Energy and Hubbell finalized a second version of the clevis, which addressed two issues discovered during the years’ worth of field experience. In the second version, the small cotter pin was replaced with a very large one, which is much easier for a line mechanic to grasp and manipulate while wearing thick rubber or leather gloves.

FIGURE 4 - Prototype printed on a 3D printer. In just a few days, HPS can print and send prototypes back to the utility for evaluation. This save a great deal of time and money during the design process, since expensive steel dies do not have to be made.

FIGURE 5 - About the size of refrigerators, HPS’ 3D printers can produce sample parts up to 12" x 12" x 15". 3D printers are very handy. You can quickly make sample parts and send them to the field to check fit.

FIGURE 3 - Alliant Energy created a number of designs. Working with engineers at Hubbell Power Systems, number five was chosen for prototyping and, ultimately, production.


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