Instrumented Cutter With Compliant Connecting Section
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Solution Overview
Problem
Current rotary cutting tools lack effective means to measure forces acting on cutters during underground conduit creation or enlargement, which is crucial for optimizing drilling and milling processes.
Innovation Solution
The tool design incorporates a cutter body with a compliant connecting section that allows for force measurement by strain sensors, enabling the transmission of forces from the outer end portion to the tool body while maintaining elastic deformation within the connecting section's limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid connecting section is used to attach the cutter to the tool body, then the strength and stability of the connection is improved, but the ability to measure forces through strain deformation is lost
Solution Approach 1:
The connecting section is designed with non-uniform cross-sectional area, creating a localized region with smaller cross-section that has higher compliance. This allows the connecting section to exhibit elastic deformation under load while maintaining overall connection strength, enabling force measurement through strain sensors placed on the compliant region.
Solution Approach 2:
The cross-sectional area parameter of the connecting section is varied along its length, creating a gradient from smaller to larger cross-section. This parameter change creates the necessary compliance in the connecting section while maintaining adequate strength, allowing strain measurement without complete rigidity.
2Measurement precision
If the connecting section has smaller cross-section to increase compliance for measurement, then force measurement capability is improved, but the overall strength of the connection may be reduced
Solution Approach 1:
The connecting section is divided into multiple regions with different cross-sectional areas. The smaller cross-section portion provides compliance for measurement, while the larger cross-section portions maintain strength. This segmentation allows both measurement capability and structural integrity to coexist.
Solution Approach 2:
The connecting section may utilize composite material construction or heterogeneous material properties to achieve the desired combination of compliance and strength. Different material phases or structures within the connecting section allow localized deformation for sensing while maintaining overall structural adequacy.
3Stability of the object's composition
If the outer end portion is closely spaced to the cavity wall to constrain movement, then positional stability is improved, but the range of elastic deformation for force measurement is reduced
Solution Approach 1:
The system is designed to operate in a dynamic regime where the outer end portion undergoes controlled elastic deformation within a limited range. The close spacing to the cavity wall provides a restoring force that keeps the deformation within elastic limits while still allowing sufficient strain for measurement purposes.
Solution Approach 2:
The cavity wall spacing is designed to provide just enough constraint to maintain stability while allowing partial movement for measurement. The spacing is not tight enough to completely prevent deformation, but tight enough to ensure elastic behavior and positional stability during operation.
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 design enables precise measurement of forces acting on the cutter, allowing for improved process control and optimization of drilling and milling operations by monitoring strain and force distribution.
Implementation Method 1
the at least one connecting section being of smaller cross-sectional area than both the inner and outer end portions so as to have greater compliance than the inner and outer end portions... When force is applied to the hard face of the cutter, which is on the outer end portion, it causes strain. This strain consists mostly of distortion of the connecting section(s)
Data Source
AI summary
A rotary cutting tool for use in a wellbore has an instrumented cutter fitted into a cavity in the tool body. The instrumented cutter body has an outer end portion exposed at the open end of a cavity and is connected to the tool body through at least one connecting section having a smaller cross-section and greater compliance than the outer end portion. The outer end portion and the connecting section are slightly movable within the cavity but the cavity surrounds at least part of the outer end portion sufficiently closely to limit transverse movement to elastic strain of the compliant connecting portion. One or more sensors, which may be strain gauges, are used to measure force on the outer end portion in a plurality of directions transverse to the cavity and causing elastic strain of the at least one connecting section.