Pipe Bursting Head Using Cable Fatigue Loading
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Solution Overview
Problem
Current pipe bursting systems face challenges with slow bursting rates and equipment limitations when dealing with large pipes and obstructions, requiring large and costly equipment, and often result in unacceptably slow processes or the need for further excavation.
Innovation Solution
The system combines a hydraulic cable puller with a small impactor to create a reciprocating fatigue cycle stress load on the pipe, varying the stress above and below the static load imposed by the cable, using the stored energy in the cable and impactor to efficiently rupture the pipe through low-cycle fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large and costly equipment is used to handle large pipes and obstructions, then bursting capacity is improved, but equipment complexity and cost increase
Solution Approach 1:
The system dynamically combines a static cable puller with a dynamic impactor that delivers reciprocating blows. The impactor activates only when additional force is needed to overcome obstructions or large pipe sections, transforming the system from purely static to a hybrid static-dynamic system that adapts to resistance conditions.
Solution Approach 2:
The invention merges two different force application methods: the continuous static pulling force from the cable puller and the intermittent dynamic impact force from the impactor. This combination allows the system to handle both normal bursting conditions and difficult obstructions with a single integrated apparatus.
2Device complexity
If static cable pulling is used for pipe bursting, then equipment size is reduced, but bursting rate becomes slow when encountering obstructions
Solution Approach 1:
The impactor operates periodically, delivering reciprocating blows at controlled intervals rather than continuously. This periodic action allows the system to maintain low equipment size while providing bursts of high force when needed, preventing the cable from becoming stuck and maintaining productivity during obstruction encounters.
Solution Approach 2:
The system changes the force application parameter from purely static to a combination of static plus dynamic impact. The impactor modifies the force profile by adding high-magnitude, short-duration impulses that dramatically increase the bursting rate when encountering obstructions, while the overall equipment size remains compact.
3Force
If high cable tension is maintained to increase bursting force, then power requirements increase, but equipment size must be larger
Solution Approach 1:
Instead of maintaining high cable tension continuously, the system applies excessive force only partially through the impactor when needed. The impactor delivers brief, high-intensity blows that temporarily exceed the normal cable tension, providing the necessary bursting force for obstructions without requiring the cable puller to be sized for maximum continuous force.
Solution Approach 2:
The cable puller preliminarily establishes a baseline tension and positioning, preparing the system for bursting. The impactor then provides the additional force needed for difficult sections. This preliminary action by the cable puller allows the use of a smaller, lower-power device while still achieving high bursting forces when combined with the impactor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for faster pipe bursting with smaller, lighter equipment, reducing power requirements and enabling efficient handling in tight spaces without the need for extensive excavation, while maintaining high bursting capacity and efficiency even in difficult conditions.
Implementation Method 1
The force of the impactor, together with the released energy stored in the cable combine to produce a reciprocating fatigue cycle stress load on the pipe being replaced
Implementation Method 2
using the stored energy in the cable and impactor to efficiently rupture the pipe through low-cycle fatigue
Implementation Method 3
The cable is pulled, either intermittently or continuously, with enough force to cause the bursting head to burst the pipe
Implementation Method 4
When the bursting head is moved axially, the outer surface imparts force to the pipe, including a radially outward component, thereby producing a hoop stress in the pipe
Implementation Method 5
the outer surface imparts force to the pipe, including a radially outward component, thereby producing a hoop stress in the pipe
Data Source
AI summary
A pipe bursting system and method, and components thereof, are described wherein a bursting head assembly pulled by a cable employs a relatively small pneumatic impactor (hammer) and a relatively large cable tension to impose a cyclical stress on the pipe being burst to cause fatigue failure of the pipe, resulting in lower size and power requirements, and higher efficiency for a given set of job requirements.