Robot Wrist Backlash Reduction via Guide Member Alignment
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Solution Overview
Problem
The assembly of a wrist unit in industrial robots is time-consuming and prone to high backlash between gearwheels, leading to disturbances and potential wobbling, especially when the axes are not linearly aligned, requiring complex disassembly for maintenance.
Innovation Solution
A method for assembling the wrist unit involves using guide members to ensure compatibility between interface surfaces, allowing the gearwheel to rotate and mesh with the pinion, reducing backlash by enabling a pendular movement that aligns the gearwheel with the pinion without screws until a secure fastening is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high tolerance is set for the distance between gearwheels to eliminate squeezing risk, then assembly is easier, but backlash becomes unacceptably great
Solution Approach 1:
The guide member is provided on the interface surface before assembly begins, pre-establishing the correct alignment path for the gearwheel axes. This preliminary positioning action ensures that when parts are joined, the axes are automatically aligned linearly, eliminating backlash without requiring tight tolerance control during assembly.
Solution Approach 2:
The guide member acts as an intermediary element between the interface surfaces of the two parts. It mediates the alignment process by providing a physical reference that guides the gearwheel into correct position, thereby resolving the conflict between easy assembly and precise backlash control.
2Manufacturing precision
If tight tolerance is set for the distance between gearwheels to reduce backlash, then gearmesh precision is improved, but assembly becomes time-consuming and complex
Solution Approach 1:
The guide member serves as a mediator that translates the complex requirement of tight backlash tolerance into a simple alignment task. By providing a physical guide, it enables workers to achieve precise gearmesh without requiring skilled adjustment or repeated measurements, thus maintaining high productivity.
Solution Approach 2:
The guide member enables the assembly process to be self-aligning. When the parts are brought together along the guide member, the correct position is automatically achieved without requiring external adjustment or complex measurement procedures, thereby reducing assembly time while ensuring precision.
3Manufacturing precision
If guide members are used to align gearwheel axes, then backlash is reduced, but device complexity increases
Solution Approach 1:
The guide member is provided locally only on the interface surface where alignment is needed, rather than throughout the entire wrist unit. This localized approach provides the necessary alignment function while minimizing the overall structural complexity of the device.
4Manufacturing precision
If complex wrist unit structure is used to achieve precise gearmesh, then backlash is reduced, but ease of maintenance deteriorates
Solution Approach 1:
The wrist unit is divided into separate parts with interface surfaces, allowing the guide member to be integrated into one part while maintaining the ability to disassemble and reassemble the unit for maintenance. The guide member's integration into the interface surface ensures precise gearmesh can be quickly restored during maintenance without requiring complex adjustments.
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 method simplifies the assembly process, reduces backlash, and ensures precise alignment of the gearwheel and pinion, minimizing tolerance errors and preventing wobbling during manipulator movements.
Implementation Method 1
the centre of the gearwheel is enabled to perform a pendular movement about the guide member and thus trends to swing about the guide member by its own weight or by applied pressure
Implementation Method 2
providing at least one of said interface surfaces with a guide member, about which the first part is rotatable in parallel relation to said second symmetry axis
Data Source
Figure 1~2
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AI summary
A method for the assembly of a first part (1) to a second part (2) of a manipulator, wherein the first part has a first interface surface (8) and the end of the second part has a second interface surface (9), which first and second interface surfaces (8, 9) after the assembly forms an interface (3) between said first part and said second part, wherein at least one of said interface surfaces (8, 9) is provided with a guide member (34) about which the other part is rotatable, joining said first part (1) and said second part (2) such that said first interface surface (8) and said second interface surface (9) are positioned to be compatible to each other, rotating said first part (1) about said guide member (34) until a gearwheel (25) of the first part (1) fully meshes a pinion (15) of the second part (2) and fastening the first part (1) firmly to said second part (2) by means for fastening (10).