Adjustable Stepping Height in Sewing Machine Walking Foot
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Solution Overview
Problem
Industrial sewing machines require cumbersome and time-consuming adjustments to change the stepping height of the upper walking foot for sewing thicker materials, limiting their efficiency in handling varying material thicknesses.
Innovation Solution
A sewing machine design with a variable length second crank arm assembly and a lead screw or pneumatic cylinder that allows for continuous adjustment of the stepping height of the upper walking foot, enabling easy configuration for sewing thicker materials by varying the distance between pivot axes of the linkage assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the sewing machine uses a fixed crank arm assembly, then the structure is simple and reliable, but the stepping height of the upper walking foot cannot be adjusted for different material thicknesses
Solution Approach 1:
The crank arm assembly is made dynamically adjustable through a variable length mechanism. The second crank arm can be repositioned along the second crank lever to change the effective crank radius, thereby adjusting the stepping height of the upper walking foot. This dynamic adjustment capability allows the machine to adapt to different material thicknesses without requiring complete redesign of the mechanism.
Solution Approach 2:
The invention changes the geometric parameter of the crank arm assembly by allowing the second crank arm to be positioned at different locations along the second crank lever. This parameter change (crank radius) directly controls the stepping height, enabling the machine to handle both thin and thick materials efficiently.
2Ease of operation
If the sewing machine uses a traditional adjustment mechanism with multiple screws and linkages, then the structure is robust, but the adjustment process is time-consuming and requires qualified technicians
Solution Approach 1:
The invention extracts the adjustment function from the complex multi-screw and multi-linkage mechanism and consolidates it into a single adjustable parameter - the position of the second crank arm on the second crank lever. This simplifies the adjustment process significantly, allowing operators to change stepping height by simply repositioning one component rather than manipulating multiple fasteners and linkages.
Solution Approach 2:
The variable length crank arm assembly is designed to be easily adjustable by the operator themselves without requiring qualified technicians. The mechanism allows direct manual adjustment of the crank arm position, enabling operators to perform maintenance and setup tasks independently and quickly.
3Adaptability or versatility
If the sewing machine is configured for thick materials with high stepping height, then it can handle thick materials effectively, but it cannot efficiently sew thinner materials
Solution Approach 1:
The machine maintains dynamic adjustability of the crank arm length, allowing operators to optimize the stepping height for each specific material thickness being processed. This ensures peak productivity for both thin and thick materials by matching the mechanism's geometry to the material requirements, rather than being locked into a fixed configuration.
Data Source
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Figure 3A
AI summary
A sewing machine (10) comprises a crank shaft (14), a first drive shaft (66), a second drive shaft (88), a needle assembly (16), a presser foot (18), and an upper walking foot (20). A first crank arm assembly (60, 62) is connected to the crank shaft (14) to the first drive shaft (66). A first linkage assembly (70) is connected to the first drive shaft (66) to the needle assembly (16). A second crank arm assembly (80) is connected to the first drive shaft (66) to the second drive shaft (88). A second linkage assembly (22) is connected to the second drive shaft (88) to the presser foot (18) and the upper walking foot (20). The second linkage assembly (22) is configured to cause out-of-phase reciprocatory movement of the presser foot (18) and the upper walking foot (20). The second crank arm assembly (80) has a variable length that is selectably adjustable by an operator to yield at least first and second different stepping heights of the upper walking foot (20).