Blog 5

 Going into the winter break, the team had set a foundation for the Test fixture design and the components that needed to go in it. For December 11-February 3rd  the tasks that were set can be found below.

Milestone 3: Bearing Selection (11/24/2023-1/24/2024)

·       Conduct supplier relations to explore options within the budget 

·       Compare bearing options within budget from 3rd party suppliers 

·       Compare and select lubricating oil for bearings

·       Purchase bearings and oil from the selected vendor

·       Design-bearing housing 

·       Purchase a seal for the bearing housing 

 

Create Prototype (1/25/2024-2/17/2024)

·       Machine Bearing housing and attach bearings to both ends of the test fixture 

·       Machine the shaft's nominal diameter

 

As Shown above, Milestone 3 was completed during December and January. The project's primary focus during that time was the bearing selection. During that process, the team conducted supplier relations to find the best bearing selection that fit within the allocated budget Sulzer gave. Shown in Figure 1 is the bearing the team decided to select for the capstone project along with the technical specifications.  




Figure 1: Deep Groove ball bearing

 However, once the team found a vendor with the correct bearing, the team faced an obstacle that changed the timeline for the project. After researching deep groove ball bearings that had a rated speed of 8000 RPMS, the team found that the bore diameter of the bearings did not fit the current shaft's diameter constraints. The initial shaft diameter is 3.5 inches, and the bore diameter of the selected bearing is 3.346 inches. The team has decided to machine down the shaft's diameter to 3.347 inches. This adjustment in the nominal shaft diameter is made to ensure that the bearing fits securely on the shaft while maintaining a specific clearance of 18 microns between the bearing and the shaft. This will help ensure the bearing will have a tight fit on the shaft, while also staying in tolerance. Figure 2 shows the updated engineering drawing of the shaft that the machinist will use.



Figure 2: Engineering Drawing of the shaft

 

Additionally, the team designed a bearing housing that fit the deep groove ball bearing specifications. As shown in Figure 3 and Figure 4, a top and bottom drawing of the bearing housing was designed.



Figure 3: Bottom of bearing housing



Figure 4: Top of bearing housing

The team’s design was a modified design of a current bearing housing from SKF. Table 1 shows the design matrix of the parameters the team is using to machine the bearing housing.

Dimensions of Bearing Seat and Outside Dimensions

Da

Diameter of Bearing Seat

5.906 [in]

Ca

Width of Bearing Seat

1.102 [in]

Db

Bore Diameter

3.425 [in]

A

Overall Width

3.346 [in]

A1

Foot width

 

A3

Inside width between seal grooves

 

A4

Width of Seal Groove

0.354 [in]

A5

Distance to seal groove

0.511 [in]

A6

Width of bore diameter

0.629 [in]

Dc

Diameter of seal groove

3.937 [in]

Table 1: Technical specifications of Bearing housing

 

 

  The last task completed before going into February was the seal selection. The team selected a seal, as shown in Figure 5, that is tailored to accommodate the shaft diameter and is designed to withstand a rotational speed of 8000 RPMs. Since the dimensions of this seal fit within the team's design, a direct purchase was made from the SKF vendor.



Figure 5: HMSA10 V seal

 we will assess suitable lubricating oils to guarantee optimal bearing performance and lifespan. Following a comprehensive evaluation, the team will procure the chosen bearings and lubricant from the selected vendor. With the completion of Milestone 3, the periods between February 4th- February 17th outline the machining process and constructing an overspeed trip indicator. The engineering drawings for the shaft and bearing housing have been approved by the engineering team at Sulzer, and the components are now ready for the machining process. The team has brainstormed the idea of using optical tape with a laser for a trip indicator. However, the team needs to test this to ensure the plunger that extends out of the overspeed trip housing has enough force to break the tape. The team plans on going to Sulzer in the next two weeks to test this on a smaller overseed trip assembly. The team hopes to complete Milestone 4 by the end of February, giving so bandwidth into the early month of March. After reviewing the team's current schedule, this will provide the team with time to assemble the components and test. One of the major challenges the team sees in the next two weeks is the lead time. After consulting with the Machinist and the engineering team at Sulzer, it was expressed to the team that the team's Capstone project is not their number one priority. The expected lead time given to the team is 4 weeks. Since this is the only source to machine the team's components, the team has to adhere to the machinist's schedule. Another challenge the team sees is constructing a trip indicator. The possibility of using a laser as a trip indicator. If the plunger does not have enough force to break the optical tape, the possibility of using that as a trip indicator will not work. As a result, the team does have a backup plan. The team has designed an adjustable trip lever that can be secured at different mounting points along the shaft. Once the plunger extrudes and comes into contact with the trip lever, the test fixture will shut off, indicating that the overspeed trip did work.  

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