Method for early diagnosis of load cell "sub-health"(I)

[Abstract] This article introduces a principle and method of early and accurate diagnosis of the "sub-health" condition of load cells.

[Keywords] early; diagnosis; "sub-health"; load cell; method

I. Introduction

With the continuous deepening of enterprise technological transformation, electronic weighing instruments have been used more and more widely in process flow, process control, and settlement and measurement. The resistance strain type load cell (hereinafter referred to as the sensor) is a kind of metal elastic body as the force

-Measuring instruments with electric conversion function, and sensors are the core components of electronic weighing instruments. Due to the inherent characteristics of the sensor itself

And in a complex and harsh environment, its failures are characterized by diversity and complexity, and the failure rate is also higher. Present

Replacing the sensor in the field judgment will not only affect the normal production rhythm, but even cause the wind, the furnace, the defective product and the failure to calculate

The amount, etc., seriously affect the economic benefits of the enterprise. Maintenance personnel hope that there is a way to advance the sensor failure

Get reminded.

After years of exploration, there is a way to accurately diagnose whether the load cell is bad or not (abbreviated as

"Sub-health") to improve the initiative of maintenance and achieve the purpose of "zero failure" maintenance.

2. Principles and phenomena

The load cell involves disciplines such as mechanics, electricity, and chemistry. The cause of the fault is complicated and it is difficult to judge. Formation in failure

It is indeed not easy to diagnose in advance that the load cell is in a "sub-healthy" condition.

The faults of the load cell can be divided into three categories according to the principle: A, caused by elastic body; B, caused by electric shock and circuit; C, caused by the pasting process. But no matter what kind of failures will be reflected through the unbalanced output.

The size of the zero point output of the load cell is a reflection of the quality of the production process and the quality of the design, and it is also a potential failure

One of the most obvious manifestations.

The zero point output of the load cell is too large, which poses a potential danger to the reliability of the sensor. The change of zero point will also make

The stability of the sensor is not guaranteed. It is found that the zero point is too large during use, which must be caused by a malfunction. The long-term stability of the zero point of the load cell is a prerequisite technical index in the reliability and stability of the sensor. These are the conclusive understandings of the failure of the load cell during many years of work. On this basis, after exploration, it is found that the empty scale output and no-load output signal changes of the load cell. Using monitoring, tracking, and analysis methods, it is possible to grasp the pulse of the “health” of the load cell, from the “change amount”. "Early and accurate diagnosis of the "health" condition of the sensor. At the same time, it also explains the output of the empty scale. The change of the output of the empty scale is a concentrated reflection of two important technical indicators of the load cell zero point and linearity.

The load cell is in the "sub-healthy" condition. The two most common and most sensitive phenomena are the two most common and sensitive characteristics: one is that the weighing indicator often changes zero during use, but it can automatically return to zero without affecting the weighing. The second is that when the standard weight is loaded during the use period, there is often a slight over-tolerance, but it can be restored to normal by adjusting the potentiometer. One of these phenomena indicates that there are "sub-healthy" sensors in the scale. How to find and diagnose?