Sewing Machine Presser Foot Control for Free Motion Quilting Stability
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Solution Overview
Problem
Sewing machines with vertical presser bar movement mechanisms struggle to prevent displacement of workpieces during free motion quilting, leading to inaccuracies in sewing position when operations are stopped, especially with large workpieces, due to user contact or weight-induced shifts.
Innovation Solution
A sewing machine with a vertical movement actuator and control unit that allows switching between two modes: one for maintaining the presser foot in a cloth pressing position during sewing and another for lifting it slightly during free motion quilting, ensuring the presser foot is automatically returned to the pressing position when stopped, preventing workpiece displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the presser foot is maintained in a lifted position during sewing operation stops, then free motion quilting is enabled, but workpiece displacement occurs due to user contact or weight
Solution Approach 1:
The presser foot position is dynamically adjusted based on operational state: lifted during active sewing to enable free motion quilting, and automatically lowered during stops to prevent workpiece displacement. This dynamic switching resolves the contradiction between enabling free motion capability and maintaining workpiece stability.
Solution Approach 2:
The control unit monitors the operational status of the sewing machine and automatically adjusts the presser foot position accordingly. When sewing stops, the system detects this state and triggers automatic lowering of the presser foot, providing feedback-based control that prevents workpiece displacement while maintaining free motion capability during operation.
2Stability of the object's composition
If the sewing needle is lowered to anchor position during stops, then workpiece displacement is prevented, but the needle may bend or create damage holes in large workpieces
Solution Approach 1:
The harmful function of needle anchoring is extracted and replaced with presser foot lowering. Instead of using the needle to anchor the workpiece (which causes bending and damage holes), the system uses the presser foot to press down on the workpiece during stops, eliminating the harmful effects while maintaining position stability.
Solution Approach 2:
The presser foot serves as an intermediary between the control system and the workpiece during stops. Rather than directly anchoring the workpiece with the needle, the presser foot mediates by pressing down on the workpiece surface, providing a safer and more reliable anchoring mechanism that avoids needle damage.
3Stability of the object's composition
If the presser foot is manually lowered upon stopping, then workpiece displacement is prevented, but work efficiency is reduced due to cumbersome operations
Solution Approach 1:
The system performs self-service by automatically lowering the presser foot when sewing stops, eliminating the need for manual user intervention. The control unit autonomously monitors the operational state and executes the presser foot positioning, thereby preventing workpiece displacement while maintaining high work efficiency.
Solution Approach 2:
The manual mechanical operation of lowering the presser foot is replaced with an automated control system. Instead of requiring the user to manually operate the presser foot lever, the control unit uses electrical signals to automatically position the presser foot, substituting mechanical manual operation with automated electro-mechanical control.
4Stability of the object's composition
If the presser foot is kept in cloth pressing position during sewing, then workpiece stability is maintained, but free motion quilting cannot be performed
Solution Approach 1:
The presser foot position is dynamically adjusted based on operational state: lifted during active sewing to enable free motion quilting, and automatically lowered during stops to prevent workpiece displacement. This dynamic switching resolves the contradiction between enabling free motion capability and maintaining workpiece stability.
Solution Approach 2:
The control unit is pre-programmed with the logic to automatically lower the presser foot when sewing stops. This preliminary programming ensures that the presser foot is already in the correct position (lowered) before the next sewing operation begins, eliminating the need for manual intervention and maintaining both stability and free motion capability.
Data Source
AI summary
A sewing machine comprising: vertical movement actuator that vertically moves the presser bar having a presser foot; a control unit, that controls the vertical movement actuator to selectively execute a first mode or a second mode; a mode switch unit capable of selectively switching between the first mode and the second mode; and the control unit, when switched to the first mode, controls the vertical movement actuator so as to retain the presser foot at a cloth pressing position irrespective of an operational status of a sewing process; and when switched to the second mode, controls the vertical movement actuator so as to retain the presser foot in a slightly lifted position while a sewing operation is ongoing, whereas when the sewing operation is stopped, the presser foot is moved and retained in the cloth pressing position.