Grab Bucket Excavator Flexible Pipe Axial Traction
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Solution Overview
Problem
Existing grab bucket excavators face issues due to flexible pipes having high radial resistance to fluid pressure but low axial resistance to traction, which affects their performance in deep perforations.
Innovation Solution
The design incorporates flexible pipes with an inner polymeric tube, an outer polymeric protective tube, six metallic wire reinforcement layers wound at specific angles, and additional intermediate and consolidation layers to enhance both radial resistance to fluid pressure and axial resistance to traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If flexible pipes with high radial resistance to fluid pressure are used, then radial resistance to fluid pressure is improved, but axial resistance to traction deteriorates
Solution Approach 1:
The flexible pipe employs a composite structure combining polymeric tubes with multiple metallic wire reinforcement layers wound at specific angles. The inner polymeric tube provides radial resistance to fluid pressure, while the outer polymeric protective tube provides axial resistance to traction. The metallic wire reinforcement layers bridging between tubes enhance both radial and axial mechanical properties, resolving the contradiction between radial pressure resistance and axial traction resistance.
Solution Approach 2:
Different sections of the flexible pipe have different structural characteristics optimized for specific functions. The inner tube structure is optimized for fluid pressure containment, while the outer tube and reinforcement layers are configured to provide axial strength. This local differentiation of structural quality allows the pipe to simultaneously achieve high radial resistance and high axial resistance.
2Length of moving object
If the flexible pipe has long length subjected to high axial traction force in deep perforations, then the working depth is improved, but the axial resistance to traction deteriorates
Solution Approach 1:
The composite construction with metallic wire reinforcement layers embedded in polymeric tubes provides high specific strength (strength-to-weight ratio). This allows the flexible pipe to maintain adequate axial resistance to traction even when extended to great lengths for deep perforation work, overcoming the limitation of conventional flexible pipes that become too weak when lengthened.
Data Source
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AI summary
An excavator has a grab bucket (7) provided with two shovels (8); a lifting device (10) for lowering and lifting the grab bucket (7); and a hydraulic drive device (9) provided with at least one actuator cylinder, which is designed to move the shovels (8) between an open position and a closed position, and is operated by a fluid under pressure supplied along at least one flexible pipe (14), which has at least six reinforcement layers (20) interposed between an inner tube (18) and an outer tube (19), and is provided with a plurality of intermediate layers (21), each of which is interposed between two adjacent reinforcement layers (20) so as to ensure the adhesion between the reinforcement layers (20).