Load Cell Pedestal with Spherical Hinges for Platform Deflection
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Solution Overview
Problem
Existing load cell bases for platform scales and container scales suffer from reduced weighing accuracy due to horizontal forces and torsional moments caused by platform deflection, leading to measurement errors, especially with long load pins or short force transmission bolts.
Innovation Solution
A base with an upper joint featuring a small bearing ball and a convex force absorption surface within the base plate, ensuring the force application point remains unchanged during platform deflection, and a power transmission bolt with a crowned surface that maintains vertical force transmission, even with lateral deflection, thus minimizing bending stresses and measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a long load pin or short force transmission bolt is used, then the device complexity is reduced, but the measurement precision deteriorates due to horizontal forces and torsional moments from platform deflection
Solution Approach 1:
The invention employs a spherical bearing ball at the upper joint and a crowned (spherically curved) force absorption surface at the lower joint. This curvature allows the force transmission bolt to articulate and accommodate platform deflection while maintaining vertical force alignment, eliminating horizontal forces and torsional moments that would otherwise compromise measurement precision.
Solution Approach 2:
The invention changes the geometric parameters of the force transmission path by using a crowned surface with a radius corresponding to the bolt length. This parameter optimization ensures that even with lateral deflection, the force application point remains vertically aligned with the force absorption point, maintaining measurement accuracy without requiring excessively long or short components.
2Measurement precision
If the platform is made rigid to prevent deflection, then the measurement precision improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The invention introduces articulated joints with spherical bearing balls and crowned surfaces as intermediaries between the platform and the load cell. These intermediaries absorb and accommodate platform deflection through controlled articulation, allowing the use of a simpler, more cost-effective platform structure without compromising measurement precision.
3Device complexity
If the force transmission bolt is made short to reduce device height, then the device complexity is reduced, but the measurement precision deteriorates due to increased horizontal deflection
Solution Approach 1:
The crowned (spherically curved) force absorption surface with a radius corresponding to the bolt length enables the short force transmission bolt to articulate effectively. This curvature geometry ensures that even with lateral deflection, the force application point remains vertically aligned with the force absorption point, maintaining measurement accuracy despite the reduced bolt length.
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 achieves high weighing accuracy by maintaining vertical force transmission and preventing horizontal shifting of the force application point, allowing for stress-free and accurate force introduction into the load cell, even under bending or lateral movement of the platform.
Implementation Method 1
the upper joint (3) with a bearing ball (19) with a relatively small ball diameter
Implementation Method 2
with a crowned force absorption surface (10) on the power transmission bolt (1) with a radius corresponding to the bolt length
Data Source
Figure 1~2
AI summary
The invention relates to a pedestal for load cells (5) comprising a force transfer screw (1) and a base plate (2), wherein the force transfer screw (1) is joined to the load cell (5) by means of an upper hinge (3) and to the base plate (2) by means of a lower hinge (4). The invention is characterized in that the upper hinge (3) is made of a bearing sleeve (6) inserted in the load cell (5) having an inner bearing cup (7) in which the force transfer screw (1) is supported at the upper spherical force input surface (8) thereof. The lower hinge (4) is made of a planar hole (9) made in the base plate (2), in which the force transfer screw (1) is supported by the convex force receiving surface (10) thereof. The radius of the convex force transfer surface (10) thereby corresponds approximately to the length of the force transfer screw (1) while the radius of the spherical force input surface (8) is a fraction, and maximally one-fifth, of the radius of the force transfer surface (10).