Industrial Robot Wrist Cable Routing Using Nested Pipe and Spiral Flat Cable
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Solution Overview
Problem
Existing industrial robots face challenges in maintaining a compact and lightweight arm structure with integrated reduction gear, as prior solutions either project wire supply apparatuses or limit the rotational range due to tension in filament bodies, leading to potential breakage and reduced operational stability.
Innovation Solution
The use of a pipe member within the arm to house the umbilical-member and a flat cable wound in spiral form around the pipe member, which absorbs tension and reduces interference, allowing for a more compact design and improved stability by avoiding entanglement and twisting during robot operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filament bodies are disposed along the arm or wrist element, then connection between work tool and supply apparatus is achieved, but interference with arm or peripheral equipment occurs and tension in filament bodies results in breakage or damage
Solution Approach 1:
The flat cable is wound around the outer circumference of the hollow cylindrical intermediate shaft, utilizing the space of the intermediate shaft structure. This nesting approach allows the cable to be disposed within the existing structural boundaries of the arm, avoiding external interference while maintaining connection reliability.
Solution Approach 2:
The invention transitions from linear cable routing to a spiral/wound configuration around the intermediate shaft. This dimensional change from straight-line disposition to circumferential winding allows the cable to accommodate arm rotation without tension, as the spiral configuration can expand and contract radially during rotation.
2Reliability
If wire supply apparatus is mounted on arm to achieve compact design, then operational stability improves, but wire supply apparatus projects behind arm reducing compactness
Solution Approach 1:
The wire supply apparatus is integrated into the hollow cylindrical intermediate shaft structure, utilizing the internal space of the existing arm components. This nesting eliminates the need for external mounting that would project behind the arm, maintaining compactness while ensuring operational stability through integrated design.
3Volume of moving object
If reduction gear is incorporated in arm to achieve compact design, then arm becomes more compact, but space for cable disposition is reduced
Solution Approach 1:
The flat cable is wound around the outer circumference of the hollow cylindrical intermediate shaft that contains the reduction gear. This approach utilizes the external surface area of the intermediate shaft rather than requiring internal space, allowing cable disposition without interfering with the compact reduction gear integration.
Solution Approach 2:
The cable routing moves from internal space utilization to external circumferential winding around the intermediate shaft. This dimensional transition allows the cable to be disposed in a different spatial dimension (around the shaft) rather than competing for internal space with the reduction gear components.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An industrial robot having: an arm (17), a wrist element (22) rotatably interconnected to the arm, a work tool (32) mounted on a distal end of the wrist element, and a motor mounted on the wrist element; wherein an umbilical-member (51) connected to the work tool and a flat cable (110) connected to the motor are disposed to run along the wrist element from the arm side to aid work tool or to the motor, characterized in that a pipe member (100) extending in a direction of a rotation axis of the wrist element is provided inside the arm, the umbilical-member (51) connected to the work tool being passed inside the pipe member (100), the flat cable (110) connected to the motor being wound around outside of the pipe member, with the flat cable slacked in a rotating direction of the wrist element.