Screw Assembly Device With Axial Locking Lugs
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Solution Overview
Problem
Existing assembly methods for shedding machine blades, such as those using screws or rivets, face issues with reliability due to vibrations and accelerations, and are not suitable for high-temperature and oil-bath environments, while existing hexagonal head screw devices are not compact and prone to bending stresses.
Innovation Solution
A screw assembly device with a threaded rod and a head forming a non-flat angle, featuring a locking ring and elastically deformable lugs that allow radial compactness and secure locking without significant radial protrusion, allowing for reliable assembly without a riveting press and maintaining mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a screw assembly device with a hexagonal head and radial lugs is used, then the screw can be driven by a key, but the device has large radial size and the lugs undergo significant bending stresses
Solution Approach 1:
The patent transitions from radial lug arrangement to axial lug arrangement. The lugs are positioned along the axial direction of the screw rather than radially, changing the dimensional orientation of the locking mechanism. This eliminates bending stresses on the lugs during tightening while maintaining compact radial dimensions.
Solution Approach 2:
Instead of having lugs extend radially outward from the washer as in conventional designs, the patent inverts the arrangement by positioning lugs axially along the screw shaft. This inversion eliminates the bending moment problem while maintaining the locking function.
2Ease of repair
If screws are used to assemble component parts, then dismantling is possible without deterioration, but the screws are likely to gradually unlock during use due to vibrations and accelerations
Solution Approach 1:
The patent implements a self-locking mechanism where the lugs engage with notches on the screw shaft. Once assembled, the lugs automatically lock the screw in position without requiring additional locking elements or threadlockers. The spring-loaded lugs maintain constant contact pressure to prevent loosening under vibration while allowing controlled dismantling when needed.
3Reliability
If threadlock is used to prevent screw loosening, then assembly stability under vibration is improved, but the threadlocker deteriorates over time in oil bath and high temperature environments
Solution Approach 1:
The patent replaces chemical threadlocking methods with a purely mechanical self-locking mechanism. The spring-loaded lugs engage with notches to prevent screw rotation, eliminating the need for threadlockers that deteriorate in harsh environments. This mechanical solution provides reliable vibration resistance without the degradation issues of chemical compounds.
4Reliability
If a locking ring with lugs is added to the screw assembly, then anti-loosening capability is improved, but the radial size of the device increases
Solution Approach 1:
The patent merges the locking ring and lugs into an integrated unit that combines both functions in a single compact component. The locking ring provides the structural base while the lugs extend axially rather than radially, achieving anti-loosening capability without significant radial dimension increase.
Solution Approach 2:
By positioning the lugs in the axial direction rather than radially, the patent achieves locking functionality without increasing radial size. The dimensional reorientation allows the locking mechanism to occupy axial space instead of radial space, maintaining compact overall dimensions.
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 solution provides a reliable and compact assembly method that withstands vibrations and high temperatures, ensuring secure locking without the need for rivets or specific installation tools, while maintaining the thickness and mechanical properties of the blades.
Implementation Method 1
a second part of which faces the second edge of the pair of edges, in a radial direction with respect to a central axis of the screw, this second part of the lug being capable of approaching or moving away from the second edge, thanks to an elastic deformation of the lug
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The device (40) has a screw (50) equipped with a threaded rod (52). A head (54) comprises a pair of two adjacent side edges (5443-5446), where the head is provided with a hollow mark (56) for receiving a drive tool. A blocking ring (60) has an annular part (62) supported against a face of the head directed towards the rod and tabs (64, 66). A part of the tabs is placed against one of the side edges along a radial direction with respect to a central axis (X50) of the screw, where the part is connected to or separated from the edges by elastic deformation of the tab.