Index Plug Project
A multi-step project to help retrofit an old forming jig tool.
The Challenge
An index plug for an oval-shaped cutout. A simple 90-degree twist would lock the dome to the form die tool. These oval-shaped ones were the easier index plugs to design.
The challenge: Create a shop-aid tool to help index a dome with an existing cutout into an old tool.
A 5-axis laser cutter rendered an old form die obsolete. The laser cutter was used to cut out several large cutouts in several dome-shaped reservoir parts. Some cutouts were slot shaped and some were circular. Previously, these cutouts had been made by hand-routing, using guides built into the old forming tool.
However, while the laser cutter tool care of the large cutouts, there were several other operations (hole punches, pullouts) that still needed to be done on the old tool. These operations still had to be located properly relative to the large cutouts.
The Solution/Process
A CATIA mockup of an Index Plug fit into a dome.
The solution: 3D-printed Index Plugs to locate the laser-cut holes relative to the old form-die jig tool.
The first step was to take measurements of the dome cutouts as well as the cutout guides on the old tools with calipers. Next, rings of various sizes and configurations were 3D-printed on Stratasys Fortus-900 printers to test out form and fit. Adjustments of several thousandths of an inch could be made between iterations, until rings fit perfectly into each cutout. These rings would guide the measurements needed for the final tool.
Various sizes and shapes for test rings.
Designing Index Plugs for the oval-shaped cutouts was easy: they could simply be fit into the cutout, then turned 90-degrees to lock the claws against the inside of the dome.
However, designing an Index Plug that would fit into a circular cutout was more challenging. It would need to be able to expand its claws once it was fit through the cutout. The solution to this problem was to design something that opened up like an umbrella.
An oval-shaped Index Plug in the "locked" position. The claws could be inserted through the oval cutout in the "open" position, then turned 90-degrees. A spring on the handle would help lock the claws against the inside of the dome, which would position the dome within the old form-die tool and keep it from moving while other operations were done to it.
An "umbrella" style Index Plug could be inserted into a circular hole, and then with some twists and pulls of the handle the claws would expand and lock against the inside of the dome.
This Index Plug was designed for a form-die that had less "steps" in its cutout guide.
Since these were relatively complex assemblies, some assembly instructions were needed. Eleven details were fastened together using a variety of dowel pins and expanding pins.
Assembly instructions for a circular Index Plug.
Like most projects for this business unit, polycarbonate was chosen as the printing material due to its strength and durability, and because it is less susceptible to damage from solvents such as acetone.
A finished Index Plug complete with assembly pins, screws, and springs.
