Link Actuating Device Bearing Play Filling and Pre-load
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Solution Overview
Problem
Existing link actuating devices with parallel mechanisms face challenges in achieving high rigidity, large weight capacity, and compact size due to low rigidity and interference issues, along with difficulties in bearing play filling-up and pre-load adjustment, which affect their operational efficiency and maintenance.
Innovation Solution
The link actuating device incorporates multiple sets of link mechanisms with a bearing structure composed of two bearings, featuring a play filling-up mechanism to regulate axial movement, a spacer for pre-load adjustment, and a locking portion for positioning, enhancing rigidity and reducing size, while preventing component interference through optimized geometrical configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a parallel link mechanism is used to achieve quick and accurate operation in three-dimensional space, then positioning accuracy is improved, but the operation angle of each link becomes small, requiring large link lengths to increase the operation range, which increases the device size
Solution Approach 1:
The link mechanism is divided into multiple links (first link, second link, third link, fourth link) connected by rotation pairs, allowing each link to contribute to the overall operation range. This segmentation enables a compact configuration where the operation range is achieved through coordinated movement of multiple shorter links rather than requiring a single large link.
Solution Approach 2:
The mechanism utilizes multi-dimensional movement through the coordinated rotation of multiple links in different planes. The first and second links rotate about different axes, and the third and fourth links provide additional rotational degrees of freedom, effectively expanding the operation range in three-dimensional space without increasing link lengths.
2Adaptability or versatility
If the link length is increased to expand the operation range of the traveling plate, then the operation range is improved, but the rigidity of the mechanism decreases, limiting the weight capacity of the traveling plate
Solution Approach 1:
The mechanism is segmented into multiple rigid links of appropriate lengths, where each link maintains high rigidity. The overall operation range is achieved through the coordinated movement of these rigid segments rather than using a single long, flexible link, thereby preserving rigidity while expanding operational capability.
Solution Approach 2:
Multiple rigid links are combined through rotation pairs to form a unified mechanism that achieves large operation range. The merging of these rigid components through precise rotational joints maintains the overall rigidity of the system while enabling extensive movement capabilities.
3Reliability
If snap rings are used to prevent detachment of bearings in rotation pair portions, then bearing retention is improved, but axial gaps between snap rings and grooves cause movement and rattling of the link mechanism
Solution Approach 1:
A play filling-up member is introduced as an intermediary component between the bearing and the snap ring. This member fills the axial gap and eliminates the movement that causes rattling, while the snap ring continues to provide reliable bearing retention. The play filling-up member acts as a mediator that resolves the conflict between retention and rattling prevention.
4Stability of the object's composition
If press-fit is used to fill radial gaps in bearing structures, then gap filling is improved, but the mechanism becomes difficult to dismantle after assembly
Solution Approach 1:
The play filling-up member serves as an intermediary that provides gap filling without requiring press-fit assembly. This member can be easily installed and removed, providing the stability of filled gaps while maintaining ease of dismantling and reassembly.
Solution Approach 2:
The assembly method transitions from a static press-fit configuration to a dynamic, easily adjustable configuration. The play filling-up member can be installed and removed as needed, providing the benefits of gap filling while maintaining flexibility for maintenance and repair operations.
5Reliability
If crimping is used as a detachment prevention means for bearings, then bearing retention is improved, but dismantling is impossible and maintenance performance deteriorates
Solution Approach 1:
The bearing retention system transitions from a permanent crimping configuration to a dynamic, reversible system using snap rings and play filling-up members. This allows the bearings to be securely retained during operation while enabling easy removal and reinstallation for maintenance and repair.
Solution Approach 2:
The bearing retention system is segmented into separate functional components: the snap ring for detachment prevention and the play filling-up member for gap filling. This segmentation allows each component to be independently installed, adjusted, and removed, providing reliable retention while maintaining ease of maintenance.
Data Source
AI summary
In a bearing detachment prevention structure provided in a rotation pair portion of a link mechanism, play filling-up and pre-load adjustment for the bearing are realized with ease. As a means for therefor, there is provided a link actuating device having three or more sets of link mechanisms in each of which end link members are rotatably connected to input and output members respectively arranged on the input and output sides, the respective end link members on the input and output sides being rotatably connected to intermediate link members to form four rotation pair portions, the input and output sides being geometrically the same with respect to a cross section in a central portion of each link mechanism, in which each rotation pair portion of the link mechanisms has a bearing structure consisting of two bearings, with a play filling-up means for regulating axial movement of the two bearings being provided in the rotation pair portions. Further, by appropriately determining the configuration of each component forming the link mechanisms, interference between the components during operation of the link mechanisms is prevented. As a means therefor, a beveled portion is formed on the link side peripheral end edge portion of each input member, whereby interference between the end link member and the outer peripheral surface of the rotation pair portion of each intermediate link member is prevented.