Rebar Binding Machine Current Control for Stable Binding Time
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Solution Overview
Problem
Reinforcing bar binding machines face challenges in maintaining consistent binding time and reducing motor load and heat generation due to fluctuations in battery voltage, leading to inefficiencies in the binding process.
Innovation Solution
A binding machine with a control unit that limits motor current based on battery voltage, using a variable current limit threshold value adjusted according to the number of binding operations, to regulate motor performance and maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor operates at high speed immediately after battery charge, then the binding operation time is shortened, but the motor load and heat generation increase
Solution Approach 1:
The patent applies dynamics by making the current limit threshold variable rather than fixed. The control unit dynamically adjusts the current limit threshold based on the number of binding operations performed, allowing the motor to operate at higher speeds initially when the battery is fully charged, then progressively reducing the current limit as operations continue and battery voltage drops. This dynamic adjustment optimizes both productivity and heat management throughout the operation cycle.
Solution Approach 2:
The patent changes the parameter of current limit threshold from a constant value to a variable value that depends on the number of binding operations. By storing multiple current limit threshold values in memory and selecting appropriate values based on operation count, the system adapts motor current limits to match battery voltage characteristics during discharge, thereby controlling heat generation while maintaining productivity.
2Temperature
If the motor operates at low speed to reduce load and heat generation, then the binding operation time increases, but productivity decreases
Solution Approach 1:
The system dynamically adjusts motor speed characteristics by varying the current limit threshold throughout the operation sequence. Early operations benefit from higher current limits enabling faster motor speeds and shorter binding times, while later operations automatically transition to lower current limits that reduce heat generation. This temporal dynamics resolves the contradiction between maintaining high productivity and controlling heat accumulation.
Solution Approach 2:
The control unit pre-stores multiple current limit threshold values in memory before operations begin, preparing a sequence of appropriate current limits corresponding to different operation counts. This preliminary preparation allows the system to immediately apply appropriate current limits as operations progress, without requiring real-time calculations or adjustments during actual binding operations.
3Ease of operation
If a fixed current limit is applied regardless of battery voltage, then the motor operation is simplified, but consistent binding time cannot be maintained across different battery charge levels
Solution Approach 1:
The control unit automatically selects appropriate current limit thresholds based on the number of binding operations performed, without requiring manual intervention or external adjustment. The system self-regulates motor current limits by counting operations and retrieving corresponding threshold values from memory, maintaining consistent binding times across varying battery charge levels while keeping the operation interface simple and automatic.
Solution Approach 2:
The system implements feedback by using the operation count as a basis for adjusting current limits. Each completed binding operation increments the counter, which then feeds back to determine the appropriate current limit threshold for the next operation. This feedback mechanism ensures that motor parameters adapt to battery voltage changes, maintaining reliable and consistent binding times throughout the battery's discharge cycle.
Data Source
Figure 1
Figure 2A~2B
Figure 2C~3A
AI summary
A binding machine including a wire feeding unit configured to feed a wire, a cutting unit configured to cut the wire wound on an object, a binding unit configured to twist the wire wound on the object and cut by the cutting unit, at least one motor configured to drive one or more of the wire transfer unit, the cutting unit and the binding unit, and a control unit configured to limit a current flowing through the motor, in response to a battery voltage of a battery, in a section in which a large amount of current flows through the motor, as compared with a section in which a small amount of current flows through the motor, while the current flows from the battery to the motor.