SCARA Linear Motion Mechanism Without Reducers
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Solution Overview
Problem
Existing linear motion mechanisms in horizontal articulated robots, such as those in SCARA robots, face challenges in efficiently adjusting the vertical position and angle of a working shaft due to complex structures and high maintenance costs, particularly when using reducers for speed reduction.
Innovation Solution
A linear motion mechanism with a shaft supported by a spline nut and a ball screw nut, detachably attached via adapters, allows for two-dimensional positioning and simplified speed reduction without the need for reducers, enabling easy maintenance and reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If reducers are used for speed reduction in the linear motion mechanism, then rotational speed can be reduced, but the structure becomes complex and maintenance cost increases
Solution Approach 1:
The patent replaces the traditional mechanical reducer system with a direct-drive configuration where the ball screw nut and spline nut are directly coupled to the motor. This eliminates the need for separate speed reduction mechanisms while achieving the required torque and speed control through the inherent mechanical advantage of the ball screw and spline engagement systems.
Solution Approach 2:
The patent combines multiple functions into integrated components. The ball screw nut and spline nut are positioned to directly engage with the working shaft, merging the speed reduction, torque transmission, and positioning functions into a compact integrated assembly that eliminates separate reducer units.
2Speed
If reducers are used for speed reduction, then rotational speed can be reduced, but maintenance cost becomes high
Solution Approach 1:
The patent extracts and eliminates the reducer component from the system, removing the source of maintenance complexity and cost. The direct-drive configuration with ball screw and spline nuts provides simplified maintenance since these components are more readily serviceable and have fewer wear points than traditional reducer mechanisms.
3Force
If the power transmission member has a larger outer diameter than the attachment flange, then torque transmission is improved, but the attachment structure becomes more complex
Solution Approach 1:
The patent employs a nested arrangement where the power transmission member with its larger outer diameter is positioned within the cavity of the structural member, and the attachment flange provides a mounting interface that accommodates this size difference. The adapter allows the larger power transmission member to be securely mounted through the smaller attachment flange interface.
Solution Approach 2:
The patent introduces an adapter as an intermediary component that bridges the size mismatch between the attachment flange and the power transmission member. This adapter enables secure connection while maintaining the torque transmission capability of the larger power transmission member.
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
The mechanism simplifies structure, reduces manufacturing costs, and enhances maintenance efficiency by allowing easy replacement and adjustment of nuts, while maintaining torque and reducing rotational speed without the use of reducers.
Implementation Method 1
a ball screw nut for moving the working shaft in the axial direction
Implementation Method 2
a spline nut for rotating the working shaft about the axis
Data Source
AI summary
A linear motion mechanism includes: a shaft extending along a prescribed axis; a structural member provided with a cavity through which the shaft extends; and a spline nut and a ball screw nut that support the shaft so as to be rotatable about the axis and so as to be movable in a direction of the axis, respectively, with respect to the structural member. The spline nut and the ball screw nut are detachably attached to the structural member from both sides sandwiching the structural member via attachment flanges provided thereon. At least one of the spline nut and the ball screw nut is fixed to, inside the cavity, a power transmission member having an outer diameter larger than an outer diameter of one of the attachment flanges provided thereon and is attached to the structural member via an adapter having a larger outer diameter than the power transmission member.