Rotary Dobby Coupling for Stable Heddle Frame Motion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dobby designs are inadequate for weaving applications with significant dynamic frame forces and substantial warp thread tension, leading to unexpected shifting of heddle frames.
Innovation Solution
A rotary dobby with a frame, main shaft, outfeed lever shaft, and sub-assemblies of blades and connecting rods, featuring a coupling device that allows synchronized movement and selective locking of eccentrics to distribute forces over two blades, ensuring optimized vertical alternating movement of heddle frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If restraint and immobilization means are used to hold the eccentric in angular position, then the dobby can maintain position during weaving, but the means are inadequate under significant dynamic forces and warp thread tension
Solution Approach 1:
The patent combines two separate blade assemblies (first blade with first connecting rod, and second blade with second connecting rod) that both act on the same heddle frame through a common eccentric. This merging of force application paths distributes the dynamic forces across two synchronized blades rather than one, preventing the restraint means from needing to withstand excessive unilateral forces that would cause failure.
2Device complexity
If a single blade drives the heddle frame, then the structure is simpler, but the dynamic forces cannot be adequately distributed
Solution Approach 1:
The patent segments the force application system into two distinct blade assemblies (first blade and second blade) that operate in parallel on the same heddle frame. Each blade has its own connecting rod and actuating mechanism, but both converge on the common eccentric. This segmentation allows the total force to be distributed across multiple independent pathways, improving reliability without requiring an overly complex single-blade design.
3Stability of the object's composition
If the eccentric is locked to the main shaft, then synchronized movement is achieved, but the ability to selectively release for pattern change is lost
Solution Approach 1:
The coupling device incorporates a ratchet mechanism that allows the eccentric to be selectively locked to the main shaft for synchronized operation during normal weaving, but can be released when needed for pattern changes. This dynamic locking mechanism transitions between fixed (locked) and mobile (released) states, providing both stability during operation and adaptability for reconfiguration without requiring a completely rigid or completely free system.
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 effectively distributes and synchronizes the forces exerted by heddle frames, preventing unexpected shifting and ensuring stable operation even under high tension conditions.
Implementation Method 1
an eccentric mounted around the main shaft and comprising a first zone configured to cooperate with a first zone of the first connecting rod by constituting a first articulation, a second zone configured to cooperate with a guide ring carried by the main shaft by constituting a second articulation
Implementation Method 2
a coupling device, capable of selectively locking the main shaft and the eccentric in rotation in a coupled configuration of the coupling device, and of allowing the eccentric to rotate freely relative to the main shaft in a decoupled configuration of the coupling device
Implementation Method 3
The first hinge includes a first bearing interposed radially to the first axis, between the eccentric and the first connecting rod
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a rotary dobby for a loom comprising a frame, a main shaft, an output lever shaft, a subassembly (200') formed of a first blade (202) and at least one second blade (204), mounted adjacently. The subassembly includes a first output lever (42) and a first actuating rod (52) belonging to the first blade (202), a second output lever (44) and a second actuating rod (54) belonging to the second blade (204), an eccentric (56), mounted around the main shaft, comprising a first zone (56A) configured to cooperate with the first rod (52), a second zone (56B) configured to cooperate with a guide ring (59) and a third zone (56C) configured to cooperate with the second rod (54), and a coupling device (210).