Sewing Machine Thread Cutting Mechanism Direct Drive
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Solution Overview
Problem
Conventional thread cutting mechanisms in sewing machines are imprecise due to complex transmission mechanisms involving multiple connecting rods and indirect control via cam mechanisms, leading to errors in thread cutting operations.
Innovation Solution
A direct drive thread cutting mechanism using a stepping motor to drive a swing lever and pushing rod, which in turn drives a thread hooking blade and cutting blade to perform precise back-and-forth movements for thread cutting, eliminating the need for multiple connecting rods and allowing direct control of thread cutting speed and angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thread cutting mechanism uses multiple connecting rods and cam mechanisms for drive, then the structure can achieve thread cutting function, but the structure becomes complicated and transmission precision deteriorates due to size differences and disengagement errors
Solution Approach 1:
The patent removes the cam mechanism and multiple connecting rods from the transmission system, extracting only the essential drive function. The positioning motor directly drives the thread cutting blade assembly through a simplified linkage, eliminating the complex intermediate transmission components that caused precision errors and structural complexity.
Solution Approach 2:
The patent replaces the cam-based mechanical transmission system with a direct motor drive system. The positioning motor's rotational motion is directly converted to the linear reciprocating motion of the thread cutting blade through a simplified push-rod mechanism, eliminating cam profile design and reducing mechanical transmission errors.
2Measurement precision
If a cam mechanism is used between the positioning motor and scissor driver set for indirect drive, then the structure can transmit motion, but the control precision of thread cutting operation deteriorates due to indirect control through cam rotation
Solution Approach 1:
The patent extracts and removes the cam mechanism from the drive system, eliminating the intermediate control layer. The positioning motor now directly controls the thread cutting blade assembly through a simplified push-rod and linkage mechanism, enabling direct and precise control of thread cutting operations without cam profile conversion errors.
3Reliability
If multiple connecting rods are used in the thread cutting mechanism, then the thread cutting function can be achieved, but transmission errors increase due to size differences and disengagement during transmission
Solution Approach 1:
The patent removes the multiple connecting rods from the transmission system, extracting only the essential motion transmission function. A single push-rod directly connects the positioning motor to the thread cutting blade assembly, eliminating the chain of multiple connecting rods that accumulated transmission errors through size variations and disengagement.
Data Source
AI summary
A thread cutting mechanism is mounted on a sewing machine which includes a sewing platform. The thread cutting mechanism includes a driver assembly and a thread cutting assembly. The driver assembly includes a stepping motor, a swing lever pivotally connected to the stepping motor, and a pushing rod connected to the stepping motor and swing lever and driven jointly with the swing lever by the stepping motor to perform a back-and-forth process. The thread cutting mechanism is disposed on the sewing platform, and includes a thread hooking blade connected to and driven by the swing lever to move back-and-forth along a thread hooking path and to hook back a sewing thread, and a thread cutting blade disposed on the thread hooking path and for cutting the sewing thread when the thread hooking blade hooks back the sewing thread.