senior design: validation of design

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?