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/Wants Needs: 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
Preliminary Concepts Concept A Concept B Concept C
Concept Selection Many concepts created for each subsystems Combined to make three overall concept Ranked against design metrics Concept A received highest score 3000 2500 2000 1500 1000 500 0 Final Metric Scores Concept A Concept B Concept C
Horizontal Seal Project Design Back View Vertical Seal Front View
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
Needs: Adjusted Needs/Wants for Clamping Mechanisms 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)
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-Clamp Size Test
Purpose: Verify that the clamp can support 400 lb Method: Place increasingly heavy steel slugs in the V- Clamp Result: Pass Testing V-Clamp Support Test
Testing V-Clamp Support Test (continued) Seal = 118 lb Seal + Matt = 280 lb Seal + Matt + Bill = 440 lb
Testing V-Clamp Impact 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
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 IDS Size Test
Purpose: Verify that the IDS can support 30 lb held horizontally Method: Place a steel slug on the IDS Results: Pass Testing IDS Horizontal Support Test
Purpose: Verify that the IDS can support 30 lb held vertically Method: Place a steel slug on the IDS Results: Pass Testing IDS Vertical Support Test
Cost Analysis Prototypes V-Clamp material: $1,271 IDS material: $1,522 Welding: $520 Total: $3,413 Complete Workstation (Estimated) Frame: $6,090 RF: $2,150 Carriages: $4,930 V-Clamp: $1,670 IDS: $1,540 Assembly: $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?