Jacquard Loom Shedding Mechanism Friction Compensation
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Solution Overview
Problem
Existing shedding mechanisms in Jacquard-type looms experience excessive overload and increased costs due to the use of elastic stops to overcome friction forces, which complicates the reversal of mobile hooks' direction near the top dead center, leading to inefficient operation and higher costs.
Innovation Solution
A shedding mechanism where the selection lever's sliding ramp is designed to exert a downward force on the flexible blade, compensating for friction forces, allowing the hooks to reverse direction without excessive load on the drive means and eliminating the need for an elastic stop, with the ramp angled between 5 and 15 degrees and potentially featuring undulations or a curved design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an elastic stop is used to overcome friction forces on mobile hooks, then the hooks can reverse direction near the top dead center, but the mechanism experiences excessive overload and increased costs
Solution Approach 1:
The invention extracts and eliminates the elastic stop component from the mechanism. Instead of using an elastic stop to overcome friction forces, the patent employs a sliding ramp on the selection lever that directly provides the necessary downward force on the flexible blade, thereby removing the source of excessive overload while maintaining hook direction reversal capability
Solution Approach 2:
The sliding ramp acts as an intermediary element between the selection lever and the flexible blade. It transfers the downward force from the selection lever to the flexible blade in a controlled manner, enabling friction compensation without the need for an elastic stop and avoiding excessive overload on the drive means
2Ease of operation
If an elastic stop is used to overcome friction forces on mobile hooks, then the hooks can reverse direction near the top dead center, but the mechanism costs increase
Solution Approach 1:
The invention removes the elastic stop component from the mechanism, thereby eliminating its manufacturing cost. The sliding ramp on the selection lever provides the necessary functional capability without requiring additional elastic stop parts, reducing overall manufacturing complexity and cost
Solution Approach 2:
The sliding ramp on the selection lever performs multiple functions: it guides the flexible blade, provides downward force to overcome friction, and enables hook direction reversal. This multi-functionality eliminates the need for separate elastic stop components, reducing part count and manufacturing cost
3Reliability
If elastic stops are used on all mobile hooks, then friction forces are overcome, but the mechanism becomes more complex and costly
Solution Approach 1:
The invention extracts and eliminates the elastic stop component from the mechanism. Instead of using an elastic stop to overcome friction forces, the patent employs a sliding ramp on the selection lever that directly provides the necessary downward force on the flexible blade, thereby removing the source of excessive overload while maintaining hook direction reversal capability
Solution Approach 2:
The sliding ramp on the selection lever performs multiple functions: it guides the flexible blade, provides downward force to overcome friction, and enables hook direction reversal. This multi-functionality eliminates the need for separate elastic stop components, reducing part count and manufacturing cost
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
This solution enables the shedding mechanism to operate more economically and at higher speeds by reducing friction forces and eliminating the need for costly elastic stops, ensuring smooth operation and efficient hook movement.
Implementation Method 1
the component parallel to the direction of movement of the hook of the resultant of the forces applied to the flexible blade when the latter is in contact with the ramp, in the vicinity of the top dead center of its trajectory and at the start of its downward movement, is directed downwards
Implementation Method 2
the sliding ramp of the selection lever makes it possible to exert on the flexible blade a downward return force which compensates for the friction forces undergone by the flexible blade
Data Source
Figure 1
Figure 2A~2
Figure 3~8
AI summary
The mechanism for forming a shed (7) on a jacquard weaving loom useful in carpet and velvet, comprises movable hooks (13) between a position of upper and lower dead points. The hooks are moved by a knife (14), and are immobilized by a selector device. The hooks comprise a body (20) equipped by a nozzle (202) to give a support on the corresponding knife, and a flexible harness fixed on the body with possibilities of relative clearance and to interact with a retained lever so that a selection lever form a rail for sliding a portion of an elastic harness. The mechanism for forming a shed (7) on a jacquard weaving loom useful in carpet and velvet, comprises movable hooks (13) between a position of upper and lower dead points. The hooks are moved by a knife (14), and are immobilized by a selector device. The hooks comprise a body (20) equipped by a nozzle (202) to give a support on the corresponding knife, and a flexible harness fixed on the body with possibilities of relative clearance and to interact with a retained lever so that a selection lever form a rail for sliding a portion of an elastic harness when the hook reaches a vicinity of upper dead point in which the retained lever belongs to the selector device. A component (FA+ FB + FC) is parallel to a displacement direction of the movable hooks of the resultant efforts (RA, RB, RC) applied on the flexible harness when the harness comes in contact with the rail at the vicinity of upper dead point of its trajectory and at starting point of the its descending displacement. The selection lever is directed downwards. The rail extends according to its average direction which makes an angle of 8-15[deg] with respect to the displacement direction of the hook, and is equipped with undulations. The rail is in a tangential curved form, which makes an angles of 8-12[deg] in relation to the displacement direction of the hook. The average direction of lower and upper rails form a first and a second angle with the displacement direction of the hook respectively. The first angle has a value of 5-12[deg], and the second angle has a value of 7-15[deg]. Independent claims are included for: (1) a weaving loom; and (2) a process of selecting a movable hooks for forming a shed on a jacquard loom.