Inconel Tubing Pre-Pullout

The goal of the project is to provide the Boeing Company with a more ergonomic and consistent way to provide tubing material grinding prior to pullout. The purpose of the pullout is to join tubing in the most efficient and strongest way possible. This project aims to reduce the time and effort for the Boeing operators to obtain a successful pullout.

Problem Explanation
The Boeing Company's Tube, Duct, and Reservoir Center (TDRC) has asked the University of Idaho for assistance in creating a solution in their tubing pullout process. A tubing pullout is an alternate way to join two tubes in a duct system. This process is faster and stronger than other methods available. Currently, the cutting of the tubing is done by either a water jet or a laser cutter. Both of this methods create areas of weaker material around the hole that needs to be removed before the pullout can be done. This material is removed by grinding, using a soft stone, and is done by using a handheld grinder. The method requires the operator to hold both the tube and the tool. The completion of grinding is decided by the individual operator which creates inconsistency with time and pullout success. Not removing enough material will cause the pullout to tear and removing too much is a waste of time. The Inconel Tubing Pre-Pullout team aims to create a viable and easy to implement solution for Boeing's TDRC.



Engineering Requirements
1. Reduce the time of the grinding process to less than 20 minutes

2. Solution will be justified with a business case

3. Operator will have 1 point of contact or less with tool or part

4. Discover an accurate way to measure ground surface

5. Provide amount of material to be removed based on type of material (TBD using tests)

6. Solution must accommodate 15" duct section

Project Learning
Activities and information the team gained from the project learning phase of this project.

Initial Client Interview
The team took a trip to Boeing's TDRC in Auburn, Washington at the beginning of the project to have a face to face meeting with the client and witness the pullout grinding process first hand. Some of the things we learned from the trip were:
 * Every operator likes to hold the part and grinder a different way
 * Whether the pulling die is hot or cold depends on the material
 * Inconel and Steel require a cold pull
 * Aluminum and Titanium require a hot pull
 * The water jet is preferred to the laser when cutting the pullout holes
 * There is use of both Inconel 718 and 625
 * Pullout takes less time to manufacture than a fish-mouth joint and has a higher strength after weld
 * Boeing is primarily concerned with operator's wrist position and use during grinding
 * Boeing would like to help avoid stress and overuse injuries
 * In addition to grinding, some larger pullouts also require polishing

The Design
We decided on two different ideas that would be complementary to each other. The first is a visual inspection of the ground surface and the second is an arm to fix the grinder to the table with a force feedback system with a digital display.

Initial Idea
The initial sketch for the grinder fixture has the grinder at an angle but it will be fixed vertically with the grinder tip pointing down. We have also removed the camera microscope in favor of the handheld visual inspection tool. The grinder for the system is the Bosch DG355LCE.

First Model Iteration
The grinder sub-assembly is essentially two pieces, an arm that telescopes up and down and the fixture that will hold the grinder in place. The arm will be made from heavy duty pipe with a flange on the bottom to fix the arm to the workbench. The upper part of the arm will be smaller so that it can fit inside the base. This will allow for the ability to telescope the arm. Telescoping the arm will allow the operator to move the grinder tip into the best position for the duct size being ground. The grinder fixture, the piece that will actually hold the grinder, will be made from aluminum. It will have a similar design to the V-blocks used to hold cylinders for machining. This will allow different kinds of grinders to be used in the same fixture. The fixture will be tightened into place using wingnuts. The sensors for the force feedback system will be placed somewhere on the arm to measure moment or torque, which can be calculated into force applied at the stone tip. For more information about the force feedback system, refer to that section.

Force Feedback Subsystem
A method to provide the operator an instant feedback on the force being applied to the stone grinder tip.

The Team
For any questions or errors on this page contact Matt Dieckmann at diec5358@vandals.uidaho.edu.