New Blue Silver Steel Tape Measure Galvanized

New Blue Silver Steel Tape Measure Galvanized

There are three main factors that affect the measurement accuracy of steel tape: temperature, tension of tape and the error caused by the gravity of tape when it is hung in mid air. The error correction method caused by these three factors is as follows:

1. Temperature

Premise: the steel tape from china factory has no error at 20 ¡æ.

Calculation formula: error due to temperature = actual measured value × Expansion coefficient of tape × (service temperature -20 ¡æ)

For example, the expansion coefficient of a steel tape is 0.0000115, and the correction at 36m at 10 ¡æ is 36000mm × zero point zero zero zero zero one one five × (10-20)=-4.14mm

2. Tension of tape

Premise: the ruler belt does not need tension correction under standard tension. When the tape exceeds or falls below the standard tension, it will stretch.

Calculation formula: error due to tension = (actual measured tension – standard tension) × Measured distance ÷ (telescopic elastic force) × Cross-sectional area of steel tape from china factory)

For example, the standard tension is 50N, and the correction at 36m under 100N tension: (100-50) × 36000mm÷(205800 × 2.52)=3.47mm

3. Error caused by the weight of the tape when the steel tape from china factory is hung in the air for measurement

Calculation formula: error caused by the gravity of the tape = -{(unit weight of the tape × Measured distance) × Measured distance}÷ (24 × Measured tension)

For example, 100N, 36m-{£¨0.000194 × 36000mm£© × 36000mm}÷£¨24 × Measured tension) =-7.32mm

The correction parameters of steel tapes of different specifications are different.

The indicated value error of the steel tape measure is affected by the standard device of the respective laboratory, environmental conditions and many other factors. The following to use comparative measurement, measurement standard is the standard steel tape measure as an example, explain the problems should be noted when the calibration of the steel tape measure value error.

1. Standard steel tape measure and the installation of the steel tape measure and zeroing

Standard steel tape measure and the steel tape measure should be installed in parallel, and kept in the same plane. After the standard steel tape measure and the inspected steel tape measure apply the prescribed tension force respectively, use the zeroing mechanism to align the zero value line pattern center of the inspected tape measure with the zero value line pattern center of the standard steel tape measure.

2.Reading

JJG4-2015 “steel tape measure inspection procedures” clearly stipulates that when inspecting Ⅰ steel tape measure and depth measuring steel tape measure, the deviation value of the inspected point should be read by the reading microscope of 0.01mm, and the standard steel tape measure plus the correction value is used. The regulations “test Ⅱ grade steel tape measure and subsequent test steel tape measure, standard steel tape measure does not add correction value, the deviation value of the inspected points with visual estimation read.” This sentence, by the drafters of the regulations Ma Yiqing, Liu Jiali published in the “China Metrology” magazine in 2016, 7 “JJG4-2015 “steel tape measure calibration procedures” interpretation” article, should be understood as “Ⅱ steel tape measure subsequent calibration can use the standard steel tape measure nominal value of direct measurement, II Level II steel tape measure for the first time, the standard steel tape measure should be used with the correction value.”
In order to avoid the value of the error of the positive and negative sign is wrong, the use of the definition of the value of the error is “the difference between the reference value of the measuring instrument and the corresponding input quantity”