Pipe scriber "test method" - Huaqiang Electronic Network

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Kaixin micro test

I. Overview

Longitudinal retraction rate is an important indicator of the performance of plastic pipe products. It reflects the stability of plastic pipe products in the longitudinal plasticity of the pipe under thermal influence. Its measurement is of great significance to improve the ability of the product to withstand changes in temperature, sunlight and other heat sources, and to increase the life of the product. However, due to the diversity of methods for determining the longitudinal retraction rate, we often affect the accuracy of the detection due to improper operation or inadvertent attention.

There are two test methods for determining the longitudinal shrinkage of thermoplastic pipes, one in liquid (Method A) and the other in air (Method B). The sample of the specified length is placed in a heating medium at a given temperature for a certain period of time, and the distance between the sample lines before and after heating is measured. The longitudinal retraction rate of the tube is expressed as a percentage change from the length of the original length. .

The scriber is to draw two circumferential markings on the sample with a distance of 100mm so that one of the markings is at least 10mm from either end. It complies with the national standard GB/T6671-2001 "Determination of the longitudinal shrinkage rate of thermoplastic pipes". It is suitable for samples with a diameter of less than or equal to 400mm, and samples larger than 400mm can be used for slicing tests.

Second, technical parameters

1. Straight line distance: 100mm (loose screws can be adjusted at will)

2, scribing pen: arbitrary (but pencil, marker, paint pen, etc.)

3. Sample diameter: 0-400mm

4, the external dimensions: 550 × 420 × 250mm

5, weight: 15KG

Third, the test method

1. Place the scriber in a suitable test location and adjust the anchor screw so that the scriber is in an equilibrium position without shaking.

2. The sample is taken to make the length of the sample 200±20 mm, and then the sample is placed in the center of the four rotating wheels of the scribe.

3. Place the marking pen (but pencil, marker pen, paint pen, etc.) on the fixing frame above the scriber, adjust the position of the marking pen so that the two pens are in the same shape, and adjust the position of the marking pen tip. The distance between the two tips is 100mm (guarantee the distance between the two markings is 100mm).

4. Gently turn the handwheel. At this time, the sample rotates with the rotating wheel. After the sample rotates one turn, the marking pen draws two parallel circumferential markings on the sample. If the marking is unclear, adjust the height of the marker. Then, turn the handwheel back to the starting position one turn in the opposite direction. At this time, it can be ensured that the marked line drawn after adjustment is coincident with the adjustment.

5. Remove the sample and refer to GB/T6671-2001 "Determination of Longitudinal Retraction Rate of Thermoplastic Plastic Pipes" in Test Method Method A or B for retraction rate test.

Fourth, the test results processing

Longitudinal retraction rate T=_L0-L_/L0×100

Note: We draw two circumferential markings of 100mm apart from each sample and make it a line at least 10mm away from either end of the specimen. After the line is drawn, we should measure it again and use the measurement result as the original gauge length. Set the oven to the required 150 ° C. When the oven reaches the specified temperature, we place the prepared sample. Measure again and use the measurement result as the original gauge length. Set the oven to the required 150 ° C. When the oven reaches the specified temperature, we place the prepared sample. It should be noted here that when we put the sample, the oven should be re-raised to the set temperature within 15 minutes. Therefore, we should not put too much sample into the sample, it should be within the range that the oven can withstand, and the action should be slightly faster, so that the temperature inside the oven is not too low. There are two methods for placing the sample here: the first suspension sample, the test is suspended in the oven, the suspension point should be at the farthest end of the line, and the sample should not touch the bottom and wall of the oven. For the second flat sample, the sample should be placed on a flat plate with a layer of talc and placed in an oven. Here we hang the two sets of samples in an oven for heating, and the other two are placed in an oven for heating. The oven was turned off and the time was started when the oven temperature rose back to 150 °C. It is required to be placed for 60 minutes as required. After 60 minutes, we took the sample out of the oven, placed the two sets of suspended samples flat on a smooth wooden countertop, and placed one on a smooth granite countertop. The other two groups are also placed separately. Wait for the sample to cool completely to (23 ± 2) °C, we will measure the maximum or minimum distance between the lines, here we should make multiple measurements, select li to make it the largest value relative to the original gauge length, and then Calculation.