Oval Shield Machine Cutter Head Mechanism
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Solution Overview
Problem
Current shield machines for drilling tunnels with oval cross sections face challenges such as high power consumption, complex structures, increased manufacturing costs, and reduced durability due to the projection of components into the drilling chamber, which leads to mud adherence and reduced supporting stiffness.
Innovation Solution
A shield machine design featuring a circular plate member and pivot arms that rotate around a central axis, with rotary cutter heads mounted on the arms, allowing for orthogonal movement and controlled drilling of oval cross sections, reducing power consumption and improving durability by minimizing mud adherence and enhancing structural support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If components project into the drilling chamber to enable oval cross-section drilling, then the tunnel cross-section shape is improved, but mud adherence increases and power consumption rises
Solution Approach 1:
The disturbing part (cutter head assembly) is extracted from the drilling chamber space and positioned outside it. The cutter head is mounted on a movable arm that can be retracted into a housing when not in use, preventing mud adherence while enabling oval cross-section drilling when deployed.
Solution Approach 2:
A movable arm mechanism serves as an intermediary between the shield machine body and the cutter head. This arm can extend and retract, allowing the cutter head to be positioned outside the drilling chamber during operation and retracted into a housing during non-operation, thus mediating between the need for oval drilling and power consumption reduction.
2Shape
If components project into the drilling chamber to enable oval cross-section drilling, then the tunnel cross-section shape is improved, but the structure becomes more complex
Solution Approach 1:
The movable arm mechanism serves multiple functions: it supports the cutter head during drilling, enables retraction into the housing, and positions the cutter head for different drilling positions. This multi-functionality reduces the need for separate components for each function, thereby reducing overall structural complexity despite enabling oval cross-section drilling.
3Shape
If components project into the drilling chamber to enable oval cross-section drilling, then the tunnel cross-section shape is improved, but manufacturing cost increases
Solution Approach 1:
The cutter head assembly is segmented from the main shield machine body and mounted on a movable arm. This segmentation allows the cutter head to be independently positioned and retracted, enabling oval cross-section drilling while simplifying the manufacturing process by allowing modular construction and assembly.
4Shape
If components project into the drilling chamber to enable oval cross-section drilling, then the tunnel cross-section shape is improved, but supporting stiffness decreases and durability is reduced
Solution Approach 1:
The cutter head is pre-mounted on a movable arm that can be retracted into a housing before drilling operations begin. This preliminary positioning ensures that the cutter head is securely supported by the arm and housing structure, maintaining supporting stiffness and durability while enabling oval cross-section drilling when deployed.
Data Source
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AI summary
A shield machine according to the present invention includes: a body (1) having an oval cross section; a circular plate member (17) mounted on a front end-side portion of a shield machine main body (3); a first rotating mechanism (18) which rotates the circular plate member (17); a pair of pivot arms (19) which are rotatably supported by the circular plate member (17); a pair of second rotating mechanisms (20) which rotate the pair of pivot arms (19); a pair of head supporting members (19a) which are firmly fixed to tip end portions of the pivot arms (19); a pair of rotary cutter heads (4) which are rotatably mounted on the head supporting members (19a) and each of which has a diameter that is half a short diameter of the oval cross section of the body; and a pair of third rotating mechanisms (21) which rotate the rotary cutter heads (4) around third center axes.