Sewing Machine Gripper Bobbin Braking and Ejection Mechanism
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Solution Overview
Problem
Existing lockstitch sewing machine loopers are complex and fail to effectively prevent bobbin advancement when sewing speed is reduced or the machine is stopped, with braking and ejection functions not being adequately separated.
Innovation Solution
A simplified design where the braking of the bobbin is achieved through a dedicated brake spring and the ejection is facilitated by a separate ejection spring, with a locking lever mechanism that separates these functions, allowing for optimal braking force and easy bobbin removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single spring mechanism is used for both braking and ejection, then the device complexity is reduced, but the braking reliability deteriorates because the spring force cannot be optimized for both functions simultaneously
Solution Approach 1:
The single spring mechanism is segmented into two separate spring mechanisms: a first spring (brake spring) dedicated to braking the spool and a second spring (ejection spring) dedicated to ejecting the spool. This segmentation allows each spring to be independently optimized for its specific function, with the brake spring providing reliable braking force and the ejection spring providing sufficient ejection force, thereby resolving the contradiction between device complexity and braking reliability.
2Reliability
If the brake spring force is increased to prevent bobbin advancement, then the braking reliability is improved, but the ejection capability deteriorates because the same spring cannot provide sufficient force for both braking and ejection
Solution Approach 1:
The spring mechanism is segmented into a first spring for braking and a second spring for ejection. The first spring can be designed with higher force characteristics to ensure reliable braking, while the second spring is designed with appropriate force for easy ejection. This segmentation eliminates the compromise that would be necessary with a single spring, allowing both braking reliability and ease of ejection to be optimized independently.
3Reliability
If a complex locking device is used to separate braking and ejection functions, then the functional separation is achieved, but the device complexity increases
Solution Approach 1:
Instead of using a complex locking device, the patent segments the spring mechanisms themselves into functionally independent components. The first spring is positioned and configured to act solely on the spool for braking, while the second spring is positioned to act solely on the spool for ejection. This functional segmentation through separate spring mechanisms achieves reliable function separation without requiring additional complex locking devices or mechanisms.
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 design ensures the bobbin is securely braked against unwanted movement at reduced sewing speeds and allows for easy bobbin exchange, enhancing operational simplicity and efficiency.
Implementation Method 1
a brake spring (36) which acts on the spool (26) in a braking manner
Implementation Method 2
an ejection spring (34) which is arranged between the bottom (33) of the bobbin case (21) and the bearing plate (32) and which serves to push out the spool (26) from the bobbin case (21)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The gripper (8) has a bobbin case (21) moveably arranged around a vertical axis (9) in a gripper-body (24) and comprising a base (33) and a bearing pin (25) concentric to the axis. A spool supporting device (31a) is movably arranged on the bearing pin in a direction of the axis for retaining a gripper thread bobbin (26). An extended spring (34) e.g. conical spring, is arranged between the base and the spool supporting device. A brake spring (36) e.g. flat disk spring, is operated between the spool supporting device and the gripper thread bobbin.