Sewing Machine Upper Feed Dog Arc Radius Control
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Solution Overview
Problem
Existing sewing machines require expensive and complex control systems to independently drive upper feed feeders at different speeds to set the arc radius of a feed arc for sewing material, which is inefficient and costly.
Innovation Solution
The arc radius is set by adjusting the slip difference between the two upper feed feeders, allowing for stepless adjustment of the radius through mechanical means, using a stepper motor for precise positioning and toothed belts for efficient transmission, with an adjustable stop for varying material thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the two upper feed feeders are driven independently at different speeds to set the arc radius, then the arc radius can be precisely controlled, but the control system becomes expensive and complex
Solution Approach 1:
The invention changes the control parameter from independent speed control of two feeders to slip difference control. By controlling the slip difference between the two upper feed feeders through mechanical adjustment of one feeder rod's position, the arc radius is precisely controlled without requiring complex independent speed control systems.
Solution Approach 2:
The invention extracts the complex control requirement by realizing that only the slip difference between feeders needs to be controlled, not the absolute speeds of both feeders. This allows one feeder to be mechanically adjusted relative to the other, removing the need for complex synchronized speed control.
2Adaptability or versatility
If independent drive of upper feeders is used to set arc radius, then feed arc specification is achieved, but operational costs and control outlay increase
Solution Approach 1:
The invention replaces the electronic control system with a mechanical adjustment system. One upper feeder rod can be mechanically displaced relative to the other, creating the required slip difference through pure mechanical means, thereby eliminating complex electronic control and synchronization systems.
3Manufacturing precision
If mechanical adjustment of upper feeders is implemented, then stepless presetting of arc radius is achieved, but device structure becomes more complex
Solution Approach 1:
The invention segments the feeder system into two independent upper feed feeder rods that can be adjusted relative to each other. This segmentation allows one rod to be mechanically displaced to create the required slip difference, enabling stepless presetting of arc radius through simple mechanical positioning rather than complex integrated 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 solution enables precise control of the arc radius and efficient material transport, allowing for predictable gathering values and adaptation to different sewing material thicknesses, reducing operational complexity and costs.
Implementation Method 1
A spring preload according to claim 7 makes it possible for the displaceable upper feeder to deviate upwards even in a lowered feeder position when the sewing material is thicker.
Data Source
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AI summary
A sewing machine (1) for sewing two pieces of material together has at least one lower feed dog (12, 13) and two upper feed dogs (15, 16) for feeding the material. At least one (16) of the two upper feed dogs (15, 16) is movable relative to the lower feed dog (12, 13) such that a change between at least two feed dog positions is possible, in which the two upper feed dogs (15, 16) are displaced relative to each other with respect to their distance from the lower feed dog (12, 13). This results in a sewing machine in which the arc radius of a feed arc for the material can be predetermined without the two upper feed dogs having to be driven independently of each other.