Dongguan Jingcheng Industry Co., Ltd.
Address: No. 14, Minying Road, Jinxia Industrial Zone, Jinxia Management District, Chang'an Town, Dongguan City
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Edit: Administrator Browse: Time: 2019-09-30
The tensile test of the spring thimble is mainly used to determine the tensile performance of the spring thimble. Usually, a tensile tester, a universal spring thimble tester is used to perform the tensile test. The tensile test is suitable for rubber, various molecular compounds, plastic profiles, pipes, sheets, sheets, films, wires and cables, waterproof spring pins, metal wires, etc.
Tensile properties of polymer:
When used as a spring thimble , a high molecular polymer is required to have δ mechanical properties that cannot go around the bucket. It can be said that for most applications of polymer polymers, mechanical properties are more important than other physical properties.
Figure 1-Spring Thimble
Macromolecules have a wider range of mechanical properties that can change gender in the known spring thimbles. This is because polymers are composed of long-chain molecules, and molecular motion has clearly revealed relaxation and special properties. For example, the polymer spring thimble has a relatively high elongation, and the usual PE elongation at break is 90% ~ 950% (the linear elongation is low and the density of polyyiene LLDPE is higher). Through a special manufacturing process, the elongation of some spring thimbles can be above 1000%, and the break elongation of ordinary polymer spring thimbles is usually between 50% and 100%. Generally speaking, the spring thimble has high tensile properties such as heat shrinkable film and stretched film.
Low carbon steel tensile test:
Prepare the test piece: Use a ruling machine to scribe a circle in the original gauge range (or punch a small punch with a small steel), and divide the gauge length into 10 cells of equal length. Use a vernier caliper to measure the diameter of each of the two perpendicular sides at the two ends and the middle of the original gauge length of the test piece. Take the arithmetic average value as the diameter of the section at that point, and then use the minimum value of the three sections to calculate The size A of the simplest surface of the original section of the test piece or the surface of the object. (Take three significant digits).
Figure 2-Spring thimble connector
Adjust the test machine. According to the tensile strength σb of the low-carbon steel and the size of the simplest surface of the original cross-section or the surface of the object, the zui large load of the test piece is estimated, equipped with a corresponding pendulum, and a suitable force measuring disc is selected. Start the test machine and raise the workbench by about 10mm to eliminate the influence of the weight of the workbench system. Adjust the active pointer to zero, move the driven pointer closer to the active pointer, and adjust the automatic drawing device.
Clamping the test piece: first clamp the test piece in the upper chuck, then move the lower chuck to the appropriate clamping position, and then clamp the lower end of the test piece.
Inspection and commissioning. Please experimentally guide the instructor to check the above steps to complete the material situation. Start the test machine, add a small amount of load in advance (the stress corresponding to the load cannot exceed the proportional limit of the spring ejector pin), and then unload to zero to check whether the test machine works normally.
Conduct the test: Start the test machine, load slowly and uniformly, and carefully observe the rotation of the force measurement pointer and the material situation drawn by the drawing device. Pay attention to hunting the buckling load value and record it to calculate the stress value σS at the buckling point. Pay attention to the slippage phenomenon during the buckling stage. After the buckling phase, the loading speed can be faster. When the maximum value is about to be reached, pay attention to observe the "neck" phenomenon. Stop the specimen immediately after it breaks, and record the maximum load value.
Figure 3-Spring thimble
Remove the test piece and recording paper:
Use a vernier caliper to measure the gauge distance after the break, and use a vernier caliper to measure the small diameter d1 at the necking point.
Tensile test of cast iron:
Preparation of test pieces: Except for the use of score lines or small punch points, the rest are all the same as low carbon steel. Adjust the testing machine and automatic drawing device, install the test piece, and check the above work (the same steps as in the low carbon steel tensile test).
Perform the experiment: start the test machine and load slowly and evenly until the test piece is pulled off. Turn off the testing machine, record the zui large load value at the time of breaking, and remove the test piece and recording paper.