Sewing Machine Bobbin Case Changer Frame Mounting
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Solution Overview
Problem
Conventional bobbin case changing devices in sewing machines experience reliability issues due to slight relative movements or temperature fluctuations, leading to impaired functionality and unsatisfactory performance.
Innovation Solution
The bobbin case changing device is securely attached to the upper part of the sewing machine frame, ensuring that all components, including the rotary hook and gripping means, are affected uniformly by thermal expansions or contractions, maintaining alignment and enhancing reliability. Additionally, a pivotable gripping mechanism and a rotatably arranged magazine with multiple receptacles facilitate fast and compact bobbin case changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bobbin case changing device is attached to a separate part of the sewing machine frame, then the device can be independently positioned, but relative movements and temperature fluctuations cause misalignment and reliability issues
Solution Approach 1:
The patent merges the bobbin case changing device with the rotary hook assembly by attaching both to the same upper part of the sewing machine frame. This integration ensures that thermal expansions and contractions affect both components uniformly, maintaining their relative alignment and eliminating misalignment issues that would occur with separate attachments.
Solution Approach 2:
The patent creates an equipotential relationship between the bobbin case changing device and the rotary hook by mounting them on the same structural reference point. This ensures that both components experience identical thermal and mechanical conditions, eliminating differential movement and maintaining consistent alignment during operation.
2Device complexity
If conventional bobbin case changing devices are used with separate attachments, then device complexity is reduced, but alignment maintenance becomes difficult and reliability decreases
Solution Approach 1:
The patent combines the bobbin case changing device and rotary hook into a unified mounting system, reducing the overall number of attachment points and simplifying the structural configuration. This merged approach eliminates the complexity of coordinating multiple independent attachments while improving reliability through unified thermal and mechanical reference.
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 ensures consistent functional reliability without the need for realignment, reduces unproductive idle times during bobbin changes, and allows for compact and efficient bobbin case changing devices, even in retrofitting scenarios.
Implementation Method 1
thermally induced expansions or contractions of the machine frame affect all components of the changer and the rotary hook in the same way, so that the distances between these components do not change, or at most change only negligibly
Data Source
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AI summary
The invention relates to a sewing machine for stitching back stitches, provided with a needle bar for receiving a needle guiding an upper thread, and comprising a rotary shuttle (5) in which a bobbin case (4) comprising a bobbin guiding a lower thread can be accommodated, said sewing machine also comprises a bobbin case changing device (8) enabling a bobbin case (4) to be removed from a housing (9) and to be introduced into the rotary shuttle (5). The aim of the invention is to improve the functional reliability of said type of sewing machine with a bobbin case changing device, such that the bobbin case changing device (8) is secured to an upper part of the machine frame (2) of the sewing machine.