Stuffing Box Bearing Extraction Using Axial Jack Screws
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Solution Overview
Problem
Existing methods for removing bearings or bushings from stuffing boxes in rotary mechanical devices, particularly those with a diameter of 3″ or greater, are difficult due to their force-fit installation, often resulting in damage during removal.
Innovation Solution
The introduction of jack screws axially through the sidewall of the bearing or bushing seal body, combined with double-threaded cylindrical inserts, allows for easy extraction by pushing the body out rather than pulling, facilitating removal without damaging the seal body or stuffing box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearings or bushings are force fit into the stuffing box bore for secure installation, then reliability of sealing is improved, but removal becomes extremely difficult and may cause damage
Solution Approach 1:
The bearing or bushing is divided into two functional parts: the seal body that remains in the stuffing box and the removable extraction features (jack screw holes and pockets) that facilitate removal. This segmentation allows the bearing to be securely installed while providing a mechanism for damage-free removal when needed.
Solution Approach 2:
Jack screws serve as intermediary tools that engage with the bearing through jack screw holes and apply force to the inner flange of the stuffing box. This intermediary mechanism transfers removal force without directly contacting or damaging the bearing seal body itself.
2Ease of operation
If short removal holes are drilled in the top end of seal elements to allow inserting a screw or bolt, then ease of removal is improved, but the rigid element breaks off making it extremely difficult to remove the remaining part
Solution Approach 1:
Instead of pulling the bearing out from the top end through short removal holes (conventional approach), the jack screws push the bearing out from the bottom end. This inversion of the removal direction allows force application at the inner flange without compromising the integrity of the bearing's top portion.
Solution Approach 2:
The jack screw holes and pockets are pre-formed during manufacturing before the bearing is installed in the stuffing box. This preliminary preparation ensures that the removal mechanism is already in place and properly positioned, eliminating the need for field modifications that could damage the bearing.
3Strength
If bearings with one-half inch or greater wall thickness are used in stuffing boxes of about 3″ in diameter, then strength and durability are improved, but removal difficulty increases due to force fit installation
Solution Approach 1:
The bearing structure is segmented to include thin-walled jack screw pockets at the bottom end where removal force is applied, while the main body maintains its thick walls for strength. This segmentation allows the bearing to have both the strength of thick walls and the removability of thin-walled features.
Solution Approach 2:
Different parts of the bearing have different wall thicknesses optimized for their specific functions: the main body has thick walls (≥0.5 inch) for strength and durability, while the jack screw pockets at the bottom end have thinner walls to facilitate easy formation and engagement with jack screws for removal.
Data Source
AI summary
An improved bearing or bushing body with jack screws kit for extraction of a seal body from a stuffing box using the jack screws is provided. The bearing or bushing seal body includes at least one jack screw on each half of a split body. The jack screw passes axially through the sidewall of the body to the inner flange of the stuffing box and turning the jack screw against the inner flange to lift the body from the stuffing box. A single inner threaded or double threaded insert with a reverse outer thread and standard inner thread is inserted into the bottom wall of the body so that the body may be installed flush against the inner flange. By turning the jack screw through the insert and against the flange, the seal body is pushed out rather than pulled.