Sewing Machine Thread Feeder Segmentation for Bobbin Capacity
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Solution Overview
Problem
Sewing machines of the lockstitch type have a limited storage capacity for the lower thread bobbin, requiring frequent changes, which is time-consuming and inconvenient, due to the restricted stroke length of the thread tensioning and take-up lever.
Innovation Solution
The use of a thread feeder and a control element to manage the upper thread loop length independently of the thread tensioning and take-up lever's stroke length, allowing for a longer thread loop that increases the diameter of the lower bobbin, enabling up to 50% more thread storage without modifying the mechanical structure of the sewing machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the stroke length of the thread tensioning and take-up lever is increased to produce a larger upper thread loop, then the storage capacity of the lower bobbin can be increased, but the mechanical structure becomes more complex and the external dimensions of the sewing machine must be increased
Solution Approach 1:
The thread feeding function is segmented into two independent components: the thread tensioning and take-up lever (which maintains its original short stroke length) and a separate thread feeder mechanism (which provides the additional thread length). This segmentation allows the upper thread loop to be extended without requiring the tensioning lever to have a longer stroke, thereby avoiding the need to modify the basic mechanical structure and external dimensions of the sewing machine.
2Quantity of substance
If the stroke length of the thread tensioning and take-up lever is increased to produce a larger upper thread loop, then the storage capacity of the lower bobbin can be increased, but the maximum speed and acceleration of the lever increase, placing greater stresses on mechanical drive parts
Solution Approach 1:
The thread feeding function is segmented into two independent components: the thread tensioning and take-up lever (which maintains its original short stroke length and thus low speed and acceleration) and a separate thread feeder mechanism (which handles the additional thread length requirement). This segmentation allows the lower bobbin storage capacity to be increased without increasing the stroke length of the tensioning lever, thereby avoiding greater stresses on the mechanical drive parts.
3Quantity of substance
If the stroke length of the thread tensioning and take-up lever is increased to produce a larger upper thread loop, then the storage capacity of the lower bobbin can be increased, but the external dimensions of the sewing machine must be increased
Solution Approach 1:
The thread feeding function is segmented into two independent components: the thread tensioning and take-up lever (which maintains its original short stroke length) and a separate thread feeder mechanism (which provides the additional thread length). This segmentation allows the upper thread loop to be extended without requiring the tensioning lever to have a longer stroke, thereby avoiding the need to increase the external dimensions of the sewing machine.
Data Source
AI summary
A sewing machine including a needle that is supplied with an upper thread. A a reciprocating movement carries the upper thread through a sewing material and forms a loop beneath the sewing material. A shuttle houses a bobbin for lower thread and a shuttle arm catches the loop of the upper thread and carries the upper thread around the lower bobbin, so that a stitch is executed on the sewing material. A thread feeder feeds the upper thread to the needle and a control element on each stitch causes the thread feeder at the beginning of a stitch to advance a predetermined length of upper thread, including an excess thread, and at the end of the stitch to correct the length of the upper thread by recovering the excess upper thread, or advancing the further upper thread required.