In the use of steel tape, the main reasons for the error are the following

Release time:

2021-11-12

In the use of standard steel tape, the main reasons for the error are the following: 1. Error of temperature change Generally, the thermal expansion coefficient of steel tape measure is α = 1.25x 10-5, and the temperature difference per meter per degree changes only by one eighty thousand. However, the same steel tape measure will still produce large length changes in an environment with large temperature difference, affecting the measurement results. The error of temperature change is taken into account in the ruler formula.

In the use of standard steel tape, the main reasons for the error are the following:

1. Error of temperature change

Generally, the thermal expansion coefficient of steel tape measure is α = 1.25x 10-5, and the temperature difference per meter per degree changes only by one eighty thousand. However, the same steel tape measure will still produce large length changes in an environment with large temperature difference, affecting the measurement results. The error of temperature change is taken into account in the ruler formula.

3. Tension error

The size of the pulling force will affect the length of the steel ruler. If the spring is not used to measure the pulling force during measurement, errors will occur. The elastic modulus of steel E = 2X106 KG/CM2. According to Hooke's law, a length of 30 meters will produce a length error of ± 1.8mm when the tension error is ± 5kg.

3. The error of the steel ruler is not horizontal

When measuring the horizontal distance, the steel tape should be kept level as much as possible, otherwise the error of distance growth will occur. For a length of 30 meters, an error of about 2.6mm will occur when the height difference between the two ends of the ruler reaches 0.4 meters, with a relative error of 1/11200.

Sovereign terms

A measuring device includes a measuring tool having an end hook and a magnetic tool embedded in the end hook.

1. Direct reading method

During measurement, the zero scale of the steel tape shall be aligned with the measurement starting point, and an appropriate pulling force shall be applied (the pulling force of the pulling force shall be subject to the identification pulling force of the steel tape or the calibrated pulling force on the ruler, and shall be measured by a spring scale), and the scale on the ruler corresponding to the measurement ending point shall be directly read.

2. Indirect reading method In some parts where steel tape cannot be directly used, steel ruler or straight-angle ruler can be used to align the zero scale with the measuring point, and the ruler body is consistent with the measuring direction; Use a steel tape to measure the distance to a certain scale on the steel ruler or straight-angle ruler, and use the reading method to measure the remaining length.

3. Several Errors in Steel Tape Measurement

The more accurate steel tape must be verified after leaving the factory and after a period of use, and the temperature, pulling force and ruler length at the time of verification must be indicated. The length marked on the ruler is the nominal length, and the difference between the nominal length and the actual length is called the ruler length correction Δl. When the ruler is subjected to different pulling forces, the ruler length will change. In order to avoid this change, it is required to use steel tape according to the tension marked on the ruler.

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