Projectile Weaving Loom Dynamic Weft Gripping Mechanism
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Solution Overview
Problem
Projectile weaving looms have a longer weft insertion cycle due to static weft thread gripping and releasing operations, limiting their operating frequency and being replaced by rapier and air/water looms, except for large height or special yarn weaving, where they offer performance advantages.
Innovation Solution
A system for gripping and releasing the weft thread on a running projectile using movable elements within the projectile, actuated by fixed slides along the guide track, allowing dynamic weft thread management, eliminating static operations and reducing cycle duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static weft thread gripping and releasing operations are performed on a stationary projectile, then the weft thread can be securely joined and released, but the weft insertion cycle duration increases significantly
Solution Approach 1:
The patent transforms the static gripping system into a dynamic one by introducing a movable gripping element that can open and close while the projectile is in motion. The gripping element is actuated by a cam mechanism that converts the rotational motion of the projectile into linear motion of the gripping element, allowing it to close on the weft thread during projectile rotation and open after launch, thereby enabling secure gripping without requiring the projectile to be stationary.
Solution Approach 2:
The patent implements preliminary action by pre-positioning the gripping element in an open state before the projectile is launched. The cam mechanism is designed so that the gripping element automatically closes at the appropriate moment during projectile rotation, before the projectile leaves the launching device. This preliminary positioning and automatic actuation eliminates the need for separate stationary gripping operations, reducing cycle time while maintaining gripping reliability.
2Productivity
If the maximum operating frequency is increased to match rapier looms, then productivity improves, but the complex weft thread management operations cannot be performed securely
Solution Approach 1:
The patent replaces the complex multi-step mechanical system of stationary gripping and releasing with a streamlined cam-actuated system that performs both functions during projectile rotation. The cam mechanism provides precise timing and control of the gripping element's motion, substituting the need for separate stationary operations with a single integrated mechanical system that operates during projectile motion, thereby increasing operating frequency while maintaining reliability.
3Force
If a clamping lever with spring is used to retain the weft thread, then the weft thread is held firmly in position, but the system requires stationary operations and cannot operate at high speeds
Solution Approach 1:
The patent replaces the static spring-based clamping lever with a dynamic cam-actuated gripping element that operates during projectile rotation. The cam mechanism provides controlled force application timing, allowing the gripping element to close firmly on the weft thread during rotation and open after launch. This dynamic system maintains sufficient clamping force during the brief contact period while enabling high-speed operation, unlike the stationary spring system.
Solution Approach 2:
The patent implements periodic action by synchronizing the gripping element's closing and opening motions with the rotational period of the projectile. The cam mechanism is designed so that the gripping element closes on the weft thread during a specific phase of projectile rotation, holds it firmly during launch, and opens after the projectile has been launched. This periodic operation allows high-speed cycling while maintaining firm clamping force during the critical retention phase.
Data Source
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AI summary
Improved system for gripping/releasing the weft threads in a projectile weaving loom, wherein each of the projectiles (P) comprises, housed therein, a gripping lever (1) and a releasing lever (3) pivoted to the body of the projectile (P) and movable between a weft thread gripping position, a weft thread clamping position and a weft thread releasing position. The rotation movement of the gripping lever (1) and of the releasing lever (3), against the action of thrust means (M), is caused by the contact between a portion (lps, 8) of said gripping and releasing levers (1, 3) and respective fixed slides (S1, S2) arranged along a portion of the projectile guide track (P), before the inlet and after the outlet of the shed.