Dynamic Scale Spring Plate and Ribbon Cable Design
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Solution Overview
Problem
Dynamic scales used for processing postal items have limited throughput due to large letter gaps, restricting the handling of mixed mail sizes, and existing solutions fail to increase throughput without introducing significant errors.
Innovation Solution
The design incorporates a spring plate that extends the weighing pan, reduces impact vibrations, and uses ribbon cables for motor control and signal transmission, along with a cascaded weighing unit configuration and optimized frame and motor placement to enhance throughput and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the throughput of mail items is increased in dynamic scales, then the processing speed improves, but the error rate increases significantly
Solution Approach 1:
The weighing system is divided into multiple independent weighing units (first weighing unit with first weighing pan, second weighing unit with second weighing pan) that operate in parallel. This segmentation allows simultaneous weighing of multiple mail items, increasing throughput while each individual weighing operation maintains its accuracy, thus preventing error rate increase.
Solution Approach 2:
The spring plate is positioned to extend the weighing pan surface before mail items arrive, creating a prepared receiving surface that reduces impact shock. This preliminary preparation of the weighing surface ensures that even at higher speeds, the mail items are gently received, maintaining measurement accuracy while allowing increased throughput.
2Measurement precision
If only one piece of mail can be on the scales during weighing, then measurement precision is maintained, but throughput is limited due to large letter gaps
Solution Approach 1:
The system uses multiple separate weighing units (first and second weighing pans) that can simultaneously weigh different mail items. Each weighing unit independently maintains measurement precision for single items, while the parallel operation of multiple units eliminates the need for large gaps between items, thereby increasing throughput.
Solution Approach 2:
The weighing system transitions from a single-pan sequential arrangement to a multi-pan parallel arrangement in the horizontal dimension. This dimensional change allows multiple weighing operations to occur simultaneously at different positions, breaking the throughput limitation imposed by sequential single-item weighing while each individual weighing maintains its precision.
3Productivity
If the weighing pan is extended to reduce letter gaps, then throughput increases, but impact vibrations increase causing measurement errors
Solution Approach 1:
The spring plate extends the weighing pan surface in advance before mail items arrive, creating a gradual deceleration zone that reduces impact shock. This preliminary extension prepares the weighing surface to gently receive items, allowing the pan to be effectively extended for reduced gaps while preventing impact vibrations that would cause measurement errors.
Solution Approach 2:
The spring plate acts as a cushioning element that is already in place before mail items arrive. It provides a compliant surface that absorbs impact energy, beforehand cushioning the receiving pan against shock loads. This allows the weighing pan to extend further to reduce letter gaps while the spring plate prevents impact vibrations from compromising measurement precision.
4Length of stationary object
If the overall length of the scale module is retained unchanged, then space utilization is optimized, but increasing throughput becomes difficult
Solution Approach 1:
The scale module is segmented into multiple compact weighing units that are arranged in a space-efficient configuration. Each weighing unit (with its pan, load cell, and support structure) is a self-contained segment that can operate independently. This segmentation allows multiple weighing operations to occur simultaneously within the same overall length, increasing throughput without extending the module's physical footprint.
Solution Approach 2:
The system utilizes the vertical dimension by arranging weighing units at different heights (first weighing unit and second weighing unit at different vertical levels). This vertical stacking within the same horizontal footprint allows multiple weighing operations to occur simultaneously without increasing the overall length of the module, thereby increasing throughput while maintaining compact dimensions.
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 configuration allows for increased mail throughput up to 90 pieces per minute for DIN C6 size items without additional errors, improving both speed and accuracy in weighing operations.
Implementation Method 1
each consisting of a weighing beam with a strain gauge applied
Implementation Method 2
The spring plate reduces impact vibrations, and uses ribbon cables for motor control and signal transmission
Data Source
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AI summary
The present invention describes improvements to a dynamic scale for achieving a higher throughput, wherein the design improvements are characterized in that a spring plate is mounted on the running direction of the weighing material of the first shaft of the first conveyor belt and/or the control of the motors and the transmission of the sensor signals are carried out via flat ribbon cable, which is arranged parallel to the conveyor belts and/or that an electronic, in particular digital, evaluation of disturbance vibrations of the signals of the sensors of the load cell is carried out, wherein at least one low-pass filter is used and wherein at least two digital notch filters are used.