Sewing Machine Needle Feed Compensation for Wide Stitches
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Solution Overview
Problem
Conventional sewing machines with a horizontally disposed lower bobbin struggle to achieve wider stitches due to the curved path of the needle, resulting in an aesthetic issue and distortion of patterns, especially in decorative sewing and alphabetic characters, as the fabric feeding mechanism does not accurately compensate for the varying stitch length caused by the needle's arcuate movement.
Innovation Solution
Implementing a control algorithm for the stepping motor that adjusts the longitudinal feed of the fabric to compensate for the error in stitch length, allowing the needle to move along a curved path while maintaining accurate stitch width, enabling wider stitches up to 9 mm without restructurizing the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the needle moves along a curved path to accommodate the horizontally disposed lower bobbin, then the gripper can effectively capture the thread loop, but the stitch width is limited and patterns become distorted
Solution Approach 1:
The patent changes the control parameters of the feeding mechanism based on the needle's position and stitch width requirements. By dynamically adjusting the feed amount according to the curved needle path and desired stitch width, the system enables wider stitches while maintaining pattern accuracy without changing the fundamental mechanical structure.
2Device complexity
If the fabric feeding mechanism uses a fixed mechanism, then the structure is simple, but it cannot compensate for the varying stitch length caused by the needle's arcuate movement
Solution Approach 1:
The patent transforms the fixed feeding mechanism into a dynamic one that automatically adjusts the feed amount based on real-time needle position and stitch width requirements. This dynamic adjustment compensates for the varying stitch length caused by the curved needle path, maintaining precision without complex mechanical reconfiguration.
Solution Approach 2:
The system incorporates feedback control where the needle position and stitch width information are used to automatically adjust the fabric feeding amount. This closed-loop control ensures accurate stitch length compensation while keeping the mechanical structure relatively simple.
3Adaptability or versatility
If the stitch width is increased to enhance decorative sewing capability, then the versatility is improved, but the fabric feed error increases causing pattern distortion
Solution Approach 1:
The patent dynamically adjusts the feeding parameters based on the desired stitch width and needle position. By changing the feed amount as a variable parameter rather than using a fixed value, the system maintains pattern accuracy even when creating wide decorative stitches, thereby enhancing versatility without sacrificing precision.
Data Source
AI summary
A method and device applicable to a sewing machine which has a needle and a gripper with a horizontally positioned lower bobbin for executing a seam with stitches in a sewing material being sewn, for compensating a deficiency in a longitudinal shift of the needle during a stitch being caused by an arcuate movement of the needle when it shifts sideways in a stitch, wherein the method includes the material being advanced by a feeder a length yn in the longitudinal direction of the seam on the basis of the seam setting, and wherein the sewing machine has a control including an algorithm causing the feed motor to set the feeder, so that at each stitch which includes sideways shifts of the needle it advances the sewing material a correction length en in the longitudinal direction of the seam, thereby compensating a corresponding deficiency in the needle's longitudinal shift relative to the material during the stitch being caused by the needle's arcuate sideways movement.