Sewing Machine Dual Feed Mechanism Basting Stitch Control
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Solution Overview
Problem
Conventional sewing machines require longer time to form a basting stitch due to the need for multiple cycles of the feed dog and needle bar releasing mechanism, which increases the overall sewing time compared to forming a single lock stitch.
Innovation Solution
The sewing machine incorporates a dual feed mechanism and control system that allows the sewing object to be moved synchronously with the drive shaft rotation, enabling the formation of a basting stitch without the need for a needle bar releasing mechanism, by using a first feed mechanism with a unit feed amount less than the basting stitch length and a second feed mechanism with a unit feed amount greater than or equal to the basting stitch length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the needle bar releasing mechanism is used to temporarily halt the up-down movement of the needle bar and the feed dog is operated for a plurality of cycles, then a basting stitch longer than the feed amount in a single cycle can be formed, but the time required for forming one basting stitch becomes longer than the time required for forming one lock stitch
Solution Approach 1:
The feed mechanism is divided into two independent parts: a first feed mechanism (feed dog) and a second feed mechanism (upper feed device). This segmentation allows each mechanism to operate independently with different feed amounts, enabling the formation of long basting stitches without requiring multiple cycles of the needle bar releasing mechanism. The control device coordinates both mechanisms to achieve the desired stitch length efficiently.
2Length of moving object
If the needle bar releasing mechanism is used to temporarily halt the up-down movement of the needle bar, then a basting stitch longer than the feed amount in a single cycle can be formed, but the device complexity increases
Solution Approach 1:
The invention extracts and eliminates the needle bar releasing mechanism from the system by introducing a dual feed mechanism approach. Instead of using a complex releasing mechanism to control needle bar movement, the patent uses a control device to coordinate two feed mechanisms, simplifying the overall device structure while maintaining the ability to form long basting stitches.
Solution Approach 2:
The control device is designed to universally control both the first feed mechanism and the second feed mechanism, as well as the needle bar up-down movement. This multi-functional control approach eliminates the need for separate dedicated mechanisms for each function, reducing device complexity while achieving the desired basting stitch length.
3Length of moving object
If the feed dog is operated for a plurality of cycles to form one basting stitch, then the basting stitch length can exceed the single cycle feed amount, but the productivity decreases
Solution Approach 1:
The control device performs preliminary coordination between the first and second feed mechanisms before forming each basting stitch. By pre-planning the synchronized operation of both mechanisms, the system can form long basting stitches in a single drive shaft rotation without requiring multiple cycles, thereby maintaining high sewing speed and productivity.
Solution Approach 2:
The dual feed mechanism allows continuous and synchronized feeding of the sewing object throughout the drive shaft rotation. The first feed mechanism and second feed mechanism operate continuously in coordination, eliminating idle time and ensuring that the sewing object is continuously moved at the desired feed amount, thus maintaining high productivity while forming long basting stitches.
Data Source
AI summary
A sewing machine includes a bed, a sewing machine motor, a drive shaft, a needle bar moved up and down by the rotation of the drive shaft, a first feed mechanism can move the sewing object by making contact from below, a maximum value of the unit feed amount for the first feed mechanism being less than a specified length that is the length of a basting stitch, a second feed mechanism can move the sewing object by making contact from above, a maximum value of the unit feed amount for the second feed mechanism being not less than the specified length, and a control device controls the first feed mechanism such that the first feed mechanism does not move the sewing object and controls the second feed mechanism such that the second feed mechanism moves the sewing object with the specified length being defined as the unit feed amount.