Press-Fit Joint Arrangement With Shape Lock for Backlash-Free Assembly
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Solution Overview
Problem
Existing joint arrangements in industrial robots require specialized machinery for press fitting, which is impractical for field installation, leads to increased spare parts and does not allow for easy disconnection or replacement, and introduces backlash and safety concerns.
Innovation Solution
A joint arrangement combining a press fit and a shape lock that allows for field attachment and detachment, eliminating backlash and ensuring safety by reducing the press fit force requirement and providing a secondary locking mechanism to prevent slippage, enabling simple connection and disconnection without specialized tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a press fit machine is used to provide high press fit force, then safety against slippage is ensured, but field installation becomes impractical and device complexity increases
Solution Approach 1:
The connection mechanism is segmented into two independent components: a press fit component for eliminating backlash and a shape lock component for preventing slippage. This segmentation allows each component to be optimized independently, with the shape lock providing safety without requiring high press fit forces that would need specialized machinery.
Solution Approach 2:
The shape lock acts as a pre-prepared safety mechanism that is already in place to prevent slippage. This beforehand cushioning ensures that even if the press fit fails or is insufficient, the shape lock provides a backup safety mechanism, eliminating the need for excessively high press fit forces during assembly.
2Reliability
If a press fit machine is used to control press fit force, then sufficient safety margin is provided, but manufacturing precision requirements increase and production costs rise
Solution Approach 1:
The safety mechanism is divided into two segments: the press fit provides primary connection with reduced force requirements, while the shape lock provides secondary safety. This segmentation eliminates the need for precise press fit force control, as the shape lock ensures safety even if press fit force varies within a wider tolerance range.
Solution Approach 2:
The shape lock structure allows for simpler, less precise manufacturing of the press fit components. By providing a backup shape lock mechanism, the system can tolerate lower precision in the press fit components, effectively allowing less expensive manufacturing processes to be used.
3Ease of operation
If a shape lock is used to provide safety against slippage, then field installation is simplified, but backlash is introduced and manufacturing complexity increases
Solution Approach 1:
The invention merges two previously separate connection mechanisms (press fit and shape lock) into a single integrated system. The press fit and shape lock work together, with the press fit eliminating backlash through close tolerance fitting and the shape lock providing safety against slippage. This combination achieves both goals simultaneously.
4Reliability
If keyway or spline joints are used to provide shape lock, then safety against slippage is ensured, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent employs a simplified shape lock structure that is less complex than traditional keyway or spline joints. This simplified structure achieves the necessary safety function with fewer manufacturing steps and lower complexity, effectively replacing expensive complex components with a simpler alternative that maintains safety functionality.
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 joint arrangement facilitates field attachable and detachable connections, reduces spare parts, ensures reliable and safe operation, and provides a compact design by allowing lower press fit force settings and eliminating the need for complex machinery, while maintaining operational safety and reducing production costs.
Implementation Method 1
When the pinion is connected to the drive member by means of a press fit, such as a cylindrical press fit, safety against slippage between the drive member and the pinion can be provided by setting a press fit force high enough. Moreover, the press fit eliminates backlash between the drive member and the pinion
Implementation Method 2
In case the pinion is connected to the drive member by means of a shape lock, safety against slippage between the drive member and the pinion is provided. Examples of shape locks are keyways and splines
Data Source
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AI summary
A joint arrangement (20) comprising a drive member (22) rotatable about a rotation axis (26), the drive member (22) comprising a drive member press fit surface (42) and a drive member shape lock structure (46); an attachment portion (54) having an attachment thread (56); and a driven member (24) comprising a driven member press fit surface (44), a driven member shape lock structure (48) and a through hole (50); wherein the joint arrangement (20) is configured such that the driven member (24) can be rigidly connected to the drive member (22) by means of a press fit between the drive member press fit surface (42) and the driven member press fit surface (44) by threadingly engaging the attachment thread (56) with an attachment member (28) passing through the through hole (50); and wherein the joint arrangement (20) is configured such that a shape lock is provided between the drive member shape lock structure (46) and the driven member shape lock structure (48) when the driven member (24) is connected to the drive member (22).