The vernier caliper is an instrument commonly used in industry to measure length. It can be directly used to measure workpieces with high precision, such as length, inner diameter, outer diameter and depth of the workpiece.
Presentation of the caliper
As a widely used high-precision measuring tool, the vernier caliper consists of a main scale and a sliding vernier fixed to the main scale. If divided according to the vernier scale value, the caliper is divided into three types: 0.1, 0.05 and 0.02mm.
Vernier caliper reading method
Taking a precision caliper with a scale value of 0.02mm as an example, the reading method can be divided into three steps;
1) Read the whole millimeter according to the nearest scale on the main ruler to the left of the zero line of the auxiliary ruler;
2) According to the zero line of the auxiliary ruler, multiply the number of lines aligned right with the scale of the main ruler by 0.02 to read the decimal;
3) Add the integers and decimals above to get the total size.
0.02mm Vernier Caliper Reading Method
As shown in the picture above, the 0 line of the auxiliary ruler is aligned with the scale in front of the 64mm main ruler, and the 9th line after the 0 line of the auxiliary ruler is aligned with an engraved line on the main rule.
The 9th line after line 0 of the secondary ruler indicates: 0.02×9= 0.18 mm
The size of the part to be measured is therefore: 64+0.18=64.18 mm
How to use the vernier caliper
Gather the measuring prongs and check whether the zero mark of the vernier and the main body of the balance are aligned. If it is aligned, it can be measured; if it is not aligned, the zero error should be recorded: if the zero scale line of the slider is on the right side of the zero scale line of the ruler body, it is called a positive zero error, and if it is on the left side of the zero scale line of the ruler body, it is called a negative zero error (this specification method is consistent with the number axis specification , with the origin on the right being positive and the origin on the left being negative).
When measuring, hold the ruler body with your right hand, move the slider with your thumb, and hold the object to be measured with the outer diameter (or inner diameter) in your left hand, so that the object to be measured is located between the outer measuring prongs When firmly attached to the measuring prongs, you can read, as shown in the figure below:
Application of the caliper
As a commonly used measuring tool, calipers can be specifically used in the following four aspects: 1) Measuring the width of parts
2) Measure the outer diameter of the part
3) Measure the inside diameter of the part
4) Measure the depth of the room
Please see the figure below for specific measurement methods of these four aspects:
Precautions for use
Vernier calipers are relatively accurate measuring tools when using them, you should pay attention to the following points:
1. Before use, clean the measuring surfaces of the two clamping feet, close the two clamping feet, and check whether the 0 line of the auxiliary ruler is aligned with the 0 line of the main ruler. If they are not aligned, measure. the reading must be corrected based on the original error.
2. When measuring the workpiece, the measuring surface of the clamping foot should be parallel or perpendicular to the workpiece surface and should not be inclined. And the force should not be too large to avoid deformation or wear of the clamping feet, which will affect the measurement accuracy. 3. When reading, the line of sight should be perpendicular to the surface of the ruler, otherwise the measurement value will be inaccurate.
4. When measuring the inner diameter, rotate it gently to find the maximum value.
5. After using the caliper, wipe it thoroughly, apply protective oil and place it flat in the closure. To prevent rusting or bending.
The spiral micrometer, also called a micrometer, is a precision measuring tool. The principle, structure and usage of spiral micrometer will be explained below.
What is a spiral micrometer?
The spiral micrometer, also known as a micrometer, spiral micrometer and centimeter, is a more precise tool for measuring length than a caliper. It can measure length with an accuracy of 0.01mm and the measuring range is several centimeters.
The structure of the spiral micrometer
The following is a schematic structural diagram of a spiral micrometer:
Working principle of spiral micrometer
The spiral micrometer is manufactured based on the principle of spiral amplification, that is, when the screw rotates in the nut for one revolution, the screw advances or retreats a distance of steps in the direction of the axis of rotation. Therefore, small distances traveled along the axis can be expressed by readings on the circumference.
The precision thread pitch of the spiral micrometer is 0.5mm. The sliding scale has 50 equal divisions. When the moving scale rotates once, the micrometer screw can move forward or backward 0.5mm. Therefore, rotating each small division is equivalent to measuring. The micro screw advances or retreats by 0.5/50 = 0.01 mm. It can be seen that each small division of the sliding scale represents 0.01mm, so the spiral micrometer can be accurate to 0.01mm. Because it can also read an extra digit, it can read to the nearest thousandth of a millimeter, which is why it is also called a micrometer.
How to use a spiral micrometer
When we often help our customers use spiral micrometers to connect to our data acquisition instruments to obtain effective measurements, we often encourage them to do the following when manufacturing spiral micrometers:
1. Check the zero point before use: slowly turn the fine adjustment knob D′ to contact the measuring rod (F) and the measuring anvil (A) until the ratchet makes a sound. At this time, the zero point is activated. the movable ruler (movable sleeve) The engraved line must be aligned with the reference line (long horizontal line) on the fixed sleeve, otherwise there will be no error.
2. Hold the ruler frame (C) with your left hand, turn the coarse adjustment knob D with your right hand so that the distance between the measuring rod F and the measuring anvil A is slightly larger than the object to be measured, insert the object to be measured, and turn the protection knob D′ to tighten the object to be measured until the ratchet makes a sound, turn the fixing knob G to fix the measuring rod measure and take a reading.
How to Read a Spiral Micrometer
1. Read the fixed scale first
2. Reread the half scale if the half scale line is exposed, record it as 0.5mm; if the half-scale line is not exposed, record it as 0.0 mm;
3. Read the sliding scale again (pay attention to the estimated reading) and record it as n × 0.01 mm;
4. The final reading result is fixed scale + half scale + sliding scale
Since the reading results of the spiral micrometer are accurate to the nearest thousandth of a millimeter, the spiral micrometer is also called a micrometer.
Points to Note About Spiral Micrometers
1. When measuring, be sure to stop using the knob when the micrometer screw is close to the object to be measured, and instead use the fine adjustment knob to avoid excessive pressure. This can not only ensure accurate measurement results, but also protect the. screw micrometer.
2. When reading, pay attention to whether the half-millimeter mark on the fixed scale is exposed.
3. When reading, there is an estimated reading number in the thousandth place, which cannot be thrown away casually. Even if the zero point of the fixed scale is exactly aligned with a certain scale line of the moving scale, the thousandth place must be read. “0”.
4. When the anvil and the micrometer screw are brought together, the zero point of the movable scale does not coincide with the zero point of the fixed scale, and a zero error will occur. This needs to be corrected, i.e. zero error. The value should be removed from the final reading of the length measurement.
Proper use and maintenance of the spiral micrometer
• Check if the zero line is accurate;
• When measuring, the surface of the part to be measured must be wiped clean;
• When the workpiece is large, it should be measured on a V-shaped iron or flat plate;
• Wipe the measuring rod and anvil before measuring;
• A ratchet device is required when twisting the movable sleeve;
• Do not loosen the rear cover to avoid changing the zero line;
• Do not add ordinary engine oil between the fixed sleeve and the movable sleeve;
• After use, wipe it and oil it, put it in a special box and store it in a dry place.
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