SCARA Robot Rotation Regulator Stress Distribution
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Solution Overview
Problem
Existing SCARA robot stopper devices experience breakage due to locally applied shear stress when attempting to regulate the rotation of the arm, leading to potential bolt failure.
Innovation Solution
A SCARA robot design that incorporates a casing with hole portions and a beam, featuring a contact part, fixing part, and connecting part with a resisting member to distribute force and reduce shear stress, utilizing an elastic part and convex portions to stabilize and distribute the force applied to the rotation regulating members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stopper device is used to mechanically regulate rotation of the arm, then the rotation can be stopped at a predetermined position, but shear stress is locally applied to the fixing part causing bolt breakage
Solution Approach 1:
The rotation regulating member is divided into three functional parts: contact part (regulates rotation by contacting the arm), fixing part (secured to the base), and connecting part (links the other two). This segmentation allows the contact part to bear the rotational regulation load while the fixing part provides secure anchorage, distributing stress away from critical fixing points and preventing bolt breakage.
Solution Approach 2:
The connecting part acts as an intermediary element between the contact part and the fixing part. It transmits forces and moments from the contact part to the fixing part in a distributed manner, preventing concentrated shear stress at the fixing location and thereby preventing bolt failure.
2Strength
If the connecting part is inserted into the hole portion apart from the inner wall, then shear stress is reduced, but the structure becomes more complex
Solution Approach 1:
The connecting part is inserted into a hole portion formed in the casing wall, creating a nested structure where the connecting part fits within the casing. This nesting provides structural support and guidance while maintaining the offset from the inner wall, reducing shear stress without requiring additional external components or complex assembly procedures.
3Strength
If a resisting member is provided between the contact part and the casing, then shear stress energy is relaxed, but the device complexity increases
Solution Approach 1:
The resisting member is positioned to receive shear stress that would otherwise be transmitted directly to the connecting part and fixing part. By intentionally providing this resisting member, the harmful shear stress is converted into a controlled interaction between the resisting member and the connecting part, dissipating energy and protecting the critical fixing structure from failure.
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 design effectively suppresses breakage of the rotation regulating members by distributing the force applied, reducing shear stress and bending moments, thereby enhancing the mechanical regulation of the arm's rotation and reducing the likelihood of component failure.
Implementation Method 1
the resisting member is provided in at least one of the part between the contact part and the casing and the part between the connecting part and the hole portion, and thus, energy of the shear stress is relaxed by the resisting member
Implementation Method 2
An elastic part may be provided in a location of the base with which the contact part is in contact
Data Source
AI summary
A SCARA robot according to an aspect of the invention includes a first arm rotatable with respect to a base, a second arm rotatable with respect to the first arm, a first rotation regulating member regulating a rotation of the first arm, and a second rotation regulating member regulating a rotation of the second arm. The first arm includes a beam provided inside a casing, at least one of the first rotation regulating member and the second rotation regulating member includes a contact part, a fixing part, and a connecting part.