Discussion on Testing Methods of Large Scale Weighing Apparatus

Abstract This paper starts from the perspective of large-scale weighing instruments, and analyzes in detail the several detection methods used in the current large-scale weighing instruments, including the standard weight method, standard weight substitution method, integrated detection method, superposition method, and These aspects of the calculation method are compared with the differences in the scope of use, cost of use, and effect of use. It is hoped that this will provide some guidance for the follow-up of large-scale weighing instruments.

Key words large-scale weighing instrument; detection; method; comparison

In combination with current measurement standards and specifications, there are mainly two types of detection technology methods involved in the inspection of large-scale scales: one is a standard detection method that can be widely applied, and the other is that the application value needs to be further examined. And the method of investigation. The specific application problems of the above two types of detection methods are analyzed and discussed. At the same time, a comprehensive comparison of the application of the relevant large-scale weighing instruments is conducted to guide the development of practical work.

1. Standard test methods that can be widely used

In China's current measurement standards and specifications, the standard test methods that can be widely used include two types. One is the standard weight method, the second is the standard weight replacement method, and the third is the integrated detection method. In the process of acting on a large scale, the corresponding detection method can be summarized as follows:

1 standard weight method

The standard weight method mainly refers to the use of weights to detect the total metering performance of a large scale instrument being tested. In the standard weight method detection process, the error of the used weight should be strictly controlled within the standard value range (ie, lower than the maximum permissible error of the corresponding weighing value of the large scale instrument being tested*1/3). However, it should be noted that, from the point of view of a large-scale instrument that has been certified, the accuracy of the weighing corresponding to the maximum scale of the scale must be used as the standard for the first verification. Subsequent verifications can be flexibly selected based on actual needs. In other words, for large-scale scales, the standard weights required for early detection may be as much as tens of tons, or even hundreds of tons, and the standard weights available at the municipal metrological testing institutes are completely unable to meet this requirement. Requirements, so the application of this method is less.

2 standard weight substitution method

The standard weight substitution method mainly means that other loads may be used when the maximum scale value of a large-scale instrument to be tested is higher than 1 ton and the currently prepared standard code method is not sufficient to complete the measurement work of a large scale. Replace standard weights to complete subsequent inspections of large scales. However, in the process of testing using the standard weight substitution method, the following preconditions are required: First, the standard scale has a weight of at least 1 ton in the inspection of the large scale instrument; Second, at least 50% of the weight of the large scale instrument is tested. The maximum weighing capacity can be detected by the standard weight (above the above prerequisites, the larger value meets the requirements and the alternative method can be used for detection). At the same time, if the repeatability error of a large scale is less than 0.2e, the alternative measure can be reduced to 20% of the maximum scale; if the repeatability error of a large scale is less than 0.3e, the alternative measure can be reduced. Up to 35% of the maximum standard.

3 Integrated detection method

In the current weighing instruments testing standards "Discontinuous Accumulative Automatic Weighing Apparatus" and "Gravity Automatic Loading Weighing Apparatus" and other related specifications, it is established that the detection of large-scale weighing instruments can be completed by applying an integrated detection method. The main value of the integrated detection method lies in the fact that the true value of the quality of the weighed articles is detected by using the self-owned device of the large-scaled weighed instrument, so as to realize the scientific detection of the dynamic weighing accuracy index of the large-scale instrument being tested. However, in the process of actual work, in order to ensure the quality and accuracy of large-scale weighing instruments, it is also necessary to perform testing under certain preconditions: First, the static weighing accuracy corresponding to the large-scale instrument being tested satisfies The software and hardware conditions support the smooth development of inspection operations. Second, the method can only be used for automatic weighing instruments.

2. The test value of the application value to be further examined and examined

In view of the limitations of current standard methods in the work of large-scale weighing instruments, the relevant personnel proposed several non-standard detection methods. These methods have certain feasibility and may be able to solve the limitations of traditional detection methods. Mainly involves the following types, one is the overlay detection method, and the other is the calculation method. In the process of acting on a large scale, the corresponding detection method can be summarized as follows:

1 superposition detection method

Superposition detection is currently widely used in the detection of load cells, but it has not been widely used in large scales. Then, the accuracy requirement in the weighing sensor detection is obviously higher than that of a large scale. From this perspective, the application of overlay detection method is technically feasible. But the main problem is: From the point of view of detection method and detection step, how to realize the performance test under the condition of different weighing values ​​for large-scale weighing instruments under the superposition detection method is worthy of deep thinking.

2 calculation method

The main basis for the inspection of large-scale scales under the calculation method is that there is a certain correlation between output signals and load equivalents, bridge voltages, load cell sensitivity, the number of load cells, and the maximum capacity of the load cell. In actual work, firstly, the output signal value needs to be detected under the no-load state of a large scale, and then the standard weight is applied according to the maximum scale value of the 10%* checkweigher, the output signal value under this state is detected, and the same standard is continuously applied. Weight, the signal output value is detected and compared linearly. From this point of view, the calculation method is a comprehensive control detection method. According to the calculation parameters of the carrier provided by the manufacturer, through the calculation of the deformation of the carrier, it is checked whether the parameters provided by the manufacturer are accurate and its advantages. It is to be able to obtain the value data of the calculation error and the bearing capacity at the same time.

3. Comparison and analysis of several detection methods

This article focuses on the description and analysis of the detection methods that can be applied to the detection of large-scale scales, including the standard weight method, standard weight substitution method, integrated detection method, superposition method, and calculation method. In order to make the operator in the actual work more flexible and accurate in selecting the corresponding detection method, the comparison is made from the following three aspects: use scope, use cost, and use effect:

1 comparison of use scope

For the standard weight method, it is mainly applicable to the detection of large-scale weighing instruments with a small measuring range; for the standard weight substitution method, it is mainly applicable to the detection of large-scale instruments with a large measuring range; for integrated detection methods It is mainly applicable to the detection of large-scale automatic weighing instruments; for the superposition method, it is mainly applicable to the detection of large scales with large measuring ranges; for calculation methods, it is mainly applicable to large-scale large-scale instruments. Special weighing instrument detection work.

2 use cost comparison

For the standard weight method, the use cost is higher; for the standard weight replacement method, the use cost is medium; for the integrated detection method, the use cost is medium; for the overlay method, the use cost is higher. Low; for the calculation method, its use cost is lower.

3 use of the effect of contrast

For the standard weight method, its role in large-scale weighing instrument detection has the advantage of reliable value transfer; for the standard weight substitution method, its role in large-scale weighing instrument detection has the advantages of reliable value transfer, but the detection time-consuming Long, there may be the problem of error superposition; for the integrated detection method, it acts on the detection of large-scale weighing instruments with a certain degree of specificity, and for large-scale automatic weighing instruments, the detection time is less and the precision is high; for the superposition method In terms of its role in the detection of large-scale scales, it has the advantages of reliable transmission of measured values ​​and less time-consuming detection. For the calculation method, it can be applied to the measurement of large-scale scales to meet the metrological performance of special scales, with less time and data.

4 Conclusion

Under the background of the increasing number of large-scale scales, for the detection of large-scale scales, the staff of various industries and fields have proposed and summed up some detection methods that can meet the detection requirements. This paper attempts to comprehensively summarize and research several detection methods applicable to the current large-scale weighing instruments, hoping to attract the attention and attention of the peers.

references

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Author: Even Hongwen Source: Technology and Enterprise 2014 20