Needle Feed Sewing Machine Belt Speed Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The mismatch between the varying needle feed speed and the constant belt feed speed in sewing machines leads to inconsistent workpiece feeding, affecting the quality of the stitch.
Innovation Solution
A sewing machine configuration that integrates a lower feed mechanism using a conveyor belt driven by a motor, a needle up-and-down movement mechanism, and a control device to synchronize the belt feed with the needle feed, ensuring smooth workpiece movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a lower feed mechanism using a conveyor belt is mounted in needle feed sewing machines, then the belt does not damage the workpiece, the feed speed can be easily varied, and the number of components is small, but the constant belt feed speed mismatches with the varying needle feed speed, resulting in inconsistent workpiece feeding
Solution Approach 1:
The patent applies dynamics by making the conveyor belt speed variable rather than constant. The control device dynamically adjusts the rotational speed of the conveyor belt motor based on the needle bar's swinging speed at different upper shaft angles, allowing the belt feed speed to match the varying needle feed speed throughout the sewing cycle. This resolves the contradiction by enabling the belt to adapt its speed profile to prevent workpiece damage while maintaining feed consistency.
Solution Approach 2:
The patent changes the speed parameter of the conveyor belt from a fixed constant value to a variable value that changes according to the upper shaft angle. The control device modifies the motor rotation speed parameter in real-time based on the needle bar's positional information, ensuring that the belt feed speed corresponds to the needle feed speed at each stage of the sewing cycle. This parameter change enables both gentle workpiece handling and consistent feeding.
2Speed
If the conveyor belt speed is increased to match the maximum needle feed speed, then smooth feeding is achieved at high speeds, but the belt moves too fast during low-speed needle feed phases, causing workpiece instability
Solution Approach 1:
The system dynamically adjusts the conveyor belt speed according to the real-time operating conditions. During high-speed needle feed phases, the belt speed increases to match, enabling smooth feeding. During low-speed phases, the belt speed decreases proportionally, preventing workpiece instability. This dynamic speed adaptation is achieved through the control device that continuously monitors needle bar position and adjusts motor speed accordingly.
Solution Approach 2:
The patent implements feedback control where the control device receives information about the needle bar's swinging speed and position, then uses this feedback to adjust the conveyor belt motor speed. The feedback mechanism ensures that the belt speed always corresponds to the actual needle feed speed, maintaining both smooth high-speed feeding and stable low-speed feeding without workpiece instability.
3Power
If the needle bar swings with variable speed throughout the upper shaft rotation, then the stitching action is effective, but the feed speed varies with each upper shaft angle, creating mismatch with constant belt feed
Solution Approach 1:
The patent changes the speed parameter of the conveyor belt from constant to variable, where the variable speed profile matches the needle bar's swinging speed pattern. The control device adjusts the belt speed parameter at different upper shaft angles to correspond with the stitching power requirements, ensuring both effective stitching and consistent feeding without mismatch.
Solution Approach 2:
The conveyor belt system is designed to perform multiple functions: it provides gentle workpiece handling like traditional belt feed mechanisms while also adapting its speed to match the variable needle feed speed for consistent feeding. The control device enables the single belt mechanism to universally accommodate both the protective function and the speed-matching function that would otherwise require separate mechanisms.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A sewing machine (100) includes a lower feed mechanism (20) that feeds a workpiece from below a throat plate (101) by conveyor belts (21 to 24) driven by lower feed motors (24 and 25), a needle up-and-down movement mechanism (80) that moves up and down, by a sewing machine motor (16), a needle bar (12) holding a stitch needle (11), a needle feed mechanism (50) that swings, by the sewing machine motor (16), the needle bar (12) holding the stitch needle (11) along a feed direction of the workpiece, and a control device (90) that controls the lower feed motors (24 and 25) to feed the conveyor belts (21 to 24) in accordance with a feed amount of the stitch needle (11) along the feed direction of the workpiece, the feed amount being caused by swinging of the needle bar (12).