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Senior Design:Validation of Design
December 15, 2008
What’s a Seal?
A mechanical device used to prevent leakage from pumped fluids along a drive shaft.
Mechanical seals increase efficiency and reliability of pumps.
John Crane• Designs and manufactures seals for the
oil & gas, chemical, pharmaceutical, pulp & paper and mining sectors.
• These seals can range from 20lbs to 1000lbs.
Purpose
• As industrial equipment becomes increasingly large, so do the mechanical seals that John Crane maintains
• John Crane needs a work station that can accommodate these large seals and aid in the lifting, assembly, disassembly, testing, and cleaning of them
Needs/WantsNeeds:• A workbench to withstand the maximum weight of a mechanical seal (approximately
1000 lbs.)• Be able to translate parts coaxially for assembly and disassembly
Wants:• Be able to rotate and translate seals as to aid in the ease of assembly• To lift the mechanical seal from a crate onto a workbench
From here, the needs and wants were broken down into a detailed list of metrics that was approved by our sponsor
Concept A Concept B
Concept C
Preliminary Concepts
Concept Selection• Many concepts created for each subsystems
• Combined to make three overall concept
• Ranked against design metrics
• Concept A received highest score
Final Metric Scores
0
500
1000
1500
2000
2500
3000
Concept A Concept B Concept C
Project DesignBack View
Front View
Horizontal Seal
Vertical Seal
Project Design
How it Works
Support Frame
• Support the weight and moment of the mechanical seal
• The top bar supports the pulleys and winch that attach via wire to the slider bar
• The large plates have holes so that the structure can be bolted to the floor
Slider Bar and Trolley System
• Pulley system provides the vertical movement of the slider
• Rotating fixture attaches to center of slider
• Trolleys (not shown) fit inside column of frame
Rotating Fixture (RF)
• Attaches to slider bar using two bearings
• Utilizes motor, speed reducer and set of worm gears
• Rotates at approximately 1 RPM
Tracks and Carriages• The tracks will be attached to
rotating fixture
• Allows for both large translations and fine translations
• Connects to V-Clamp and IDS via a universal connection
• Each carriage is rated for 400 lbs
V-Clamps
• As thread base is turned, clamp converges to center point
• 6 points of contact provide for moment resistance
• Multiple sets may be used during removal from crate
Inside Diameter System (IDS)
• Eight identical slider cranks
• Sliders utilize an acme thread to translate along the seal’s axis
• Rubber coated feet grip the seal and hold the seal while articulated
Scope Reduction
• After the completion of the detailed design, the scope was reevaluated
• Manufacturing reduced to clamping mechanisms only
Adjusted Needs/Wants for Clamping Mechanisms
Needs:• IDS cannot damage inner diameter of sleeves• V-Clamps must support the weight of a seal if the bench fails and the seal is dropped
Wants:• Create a clamping machine to hold seals from outer diameter• Create a clamping machine to hold seals from inner diameter• A way to keep seals stationary to resist torque for the disassembly
Deliverables
• Built and tested V-Clamps and IDS
• A complete design package
• Operations manual
V-Clamps
V-Clamps (continued)
IDS
IDS (continued)
Testing – V-ClampSize Test
Purpose: Verify that the V-Clamp can accommodate seals from 8” to 20”
Method: Place an 8” and 20” seal in clamp
Result: Pass
Testing – V-ClampSupport Test
Purpose: Verify that the clamp can support 400 lb
Method: Place increasingly heavy steel slugs in the V-Clamp
Result: Pass
Testing – V-ClampSupport Test (continued)
Seal = 118 lb
Seal + Matt = 280 lb
Seal + Matt + Bill = 440 lb
Testing – V-ClampImpact Test
Purpose: Verify that the V-Clamp will not drop seal, even if the carriage is left unsecured
Method: Place a steel slug in the V-Clamp; drop weight; measure slug displacement
Results: Maximum displacement was 1/2 inches
Testing – IDSSize Test
Purpose: Verify the seal diameter range that the IDS accommodates
Method: Use calipers to measure fully open and fully closed seal
Results: The size range is 5 1/8” to 6 3/8”
Testing – IDSHorizontal Support Test
Purpose: Verify that the IDS can support 30 lb held horizontally
Method: Place a steel slug on the IDS
Results: Pass
Testing – IDSVertical Support Test
Purpose: Verify that the IDS can support 30 lb held vertically
Method: Place a steel slug on the IDS
Results: Pass
Cost Analysis
Prototypes
V-Clamp material: $1,271IDS material: $1,522
Welding: $520Total: $3,413
Complete Workstation(Estimated)
Frame: $6,090RF: $2,150
Carriages: $4,930V-Clamp: $1,670
IDS: $1,540Assembly: $4,000
Total: $20,380
Project Schedule
Plan Forward
V-Clamp• Can be used as is on workbench• Replace thread with a twin lead thread
IDS• Can be used as is on workbench• Make links shorter• Add tracks to improved torque
resistance
Workstation• Deliver drawing package (us)• Build workstation (John Crane)• Integrate built V-Clamp and IDS
into workstation• Use to repair large seals
Questions?