Boeing Wing Rib Workstation

The goal of this project is to develop a workstation that will facilitate all assembly of secondary components for a "generic" lower wing rib. Further considerations are laid out below and center around a movable workstation/tool system. The station will have modular options to eliminate redundant rib tools, and dynamic traits that will ease handling and assembly operations.

Background
Boeing is currently in the process of constructing a new airplane, the 777X. With a new design come new challenges. One in particular is the manufacturing and handling of the parts. The ribs in particular cannot be handled in the same way they have been with regards to preparing them for installation. Boeing has given us the task of constructing a tool/workstation that will make the assembly of components on the rib easy and efficient.

Deliverables

 * Concept sketches/CAD models and developed ideas of suitable frames to house the different size ribs.
 * Scale model prototype of a "generic" tool.
 * Proposition of scalability/customizability of the "generic" tool.
 * Suggestion of necessary workstation features and appropriate positioning of those feautures.
 * Features include: tool balancers, lighting, and air hose and power outlets.

Framing Materials
For the framing of the workstation we looked at multiple options. Particularly, we looked at using Bosch Tubing, 304 Stainless Steel, 6061 Aluminum, and Low-Carbon Steel tubing. Ideally the best option so far would be Bosch tubing due to it's capabilities. However, we must take into consideration the cost, material properties, and attachments. For example, Bosch tubing is the best fiscal option. However, various attachments will be required, which will alter the total cost associated with the material. We have compiled quite a bit of information about the different materials, from different sellers.



Having compiled all the material cost information as well as the design itself, we have decided on various materials. For the base framing, we will be using 1018 steel as it has a bigger yield strength and cuts down our cost when compared with other materials. For the framing of the Double-Hex bar, we have combined a few materials. We will be using 1018 steel as well for the general frame but for the slider component we will be using bosch tubing as it is durable but flexible with regards to attachments. Bosch tubing is the best choice for this as it will be holding our attachment pieces. The hoop itself will likely be made from stainless steel or aluminum. As for our prototype, it will mainly be made out of steel.

Lighting Possibilities
Possible lighting options that we have considered are LED lights bars, string lights that could be suspended above the part and fluorescent lights that could be positioned around the workstation. All three options can be easily purchased and are easy to set up. They are reasonably priced, ranging from $50 to $150. The fluorescent lights were in the $100 range, the LED lights were around $60, and the string lights were about $60 to $150 depending on the length of the lights. We are planing on doing some form of lighting array because of the way we are designing our work station. Something similar to the below picture.



Ergonomics
Because the main purpose of this project is to facilitate easy handling and manipulation of large objects, ergonomics are a primary concern and focus. These considerations primarily center around the minor assembly that is to be performed on the wing component held by our tool. First and foremost we need to keep all assembly operations centered within the ergonomic strike or power zone. This region is identified by the vertical extent between the hip and top of the shoulder and approximately one to one and a half forearm lengths horizontally from the hip to shoulder line. The ideal vertical location is abeam to and one forearm length away from the elbow. This allows the technician or mechanic to support their tool or part with the least about of physical strain, using their body weight as the main force.

To quantify this area, anthropometric data tables were used to construct a diagram that shows how to calculate a universal strike zone for any rib size. The diagram uses the 95th percentile shoulder height for males and the 5th percentile elbow height for females to create the absolute bounds for our strike zone range. This means an ideal fit for 90 percent of possible user statures. The result of this analysis showed that the vertical movement that our machine must accommodate to fit this range would be close to the full vertical extent of the largest given rib. The overlap between male and female strike zones may ultimately be removed from this distance. Based on these findings we may have to reevaluate our strike zone goal since our calculations require almost 5 feet of vertical adjustability. Designs that use a variety of rib positioning to accommodate this full range may be a better alternative.



Repetitive injury from tool use is an issue that we will plan to address using a variety of tool counter balance or support devices. Finally safety considerations related to the placement of emergency stop buttons and protection of pinch or catch points related to any mechanical function of our eventual final design will need to be carefully considered.

Tool Balancers
As a part of creating a complete workstation, we wanted to include the use of tool balancers to make the assembler's job easy. A suitable tool balancer would be a zero gravity balancer. They have a large array of models for many weight capacities each range being about 10lbs. The most likely weight ranges would be approximately 5-11lbs or 10-20lbs. Other features include: 360 degree rotation, easy external tension adjusting, safety cable provision, permanent lubrication, compactness and "true balance".

Generic Rib
We constructed a scaled down prototype rib. The purpose behind this prototype rib is to have a physical representation of a scaled down rib to build our workstation around. Particularly, we will be using it to obtain a better understating of how we might hold and manipulate the rib. The rib was developed from a scaled down CAD rib, received from our client. It was modeled in AutoCAD, then brought into SolidWorks to place the bolt hole patterns for our fixture plate. We split the rib into three sections for easier manufacturing and the rib parts were brought into MasterCAM for tollbooth generation. We then CNC milled the rib parts and bonded them together. It includes features from the actual ribs such as variable sized and spaced bathtubs, recessed ends, and an "I" shaped cross section. The prototype rib is similar to the actual ribs used and will ultimately give our workstation a realistic representation of the real assembly process. Our prototype rib is displayed in the figures below.



Overview
The hoop is the most critical part of our design. It sustains the frame which will hold the ribs in place. It is the component that allows for rotation, thereby meeting the ergonomic and manufacturing standards necessary to work on the ribs in an effective manner. In a sense we have built the frame and all other components from the hoop out. While Boeing will have the capabilities to create such a product in a solid state, we have had to rely on a company that has bent metal bars into the proper shape. However, these bars are off somewhat and must also be welded at the ends. If the hoops are not identical and align, then our design will not meet the goals. To fix this we will be using a fixture plate to trim and align then on a rotary table (as can be seen). This will then enable us to satisfy the design requirements.