Standard Determination Process and Principle of Springback Characteristics of Edge Cutting Tape

　　trimming beltThe rebound test standard adopts the international vulcanized trimming belt rebound test method, referring to the standard trimming belt speed measurement method, from the beginning of the test to the trimming belt viscosity reduced to * * small value and then increased, the vulcanization speed is accelerated. The scorch time of two sizes of rotors was measured, and the test results were expressed by the arithmetic mean. When the test time is less than 20 minutes, measure the test results of the two samples, the measured value is accurate to 0.5min, and take the integer value of the calculation result. The test report shall include the following contents: the type of rotor and cavity; the preheating time; the test temperature; the subject content and the scope of application stipulate the method of measuring the springback of the trimmed edge by the impact method within a small range of impact strain and strain rate. It is suitable for vulcanized trimming belt with hardness within the scope of national standard under test temperature. Refers to the environmental adjustment of the tape sample under the standard and test standard temperature, humidity and time;

The preparation principle of the trimmed sample is: the rebound rate is the ratio of the output energy to the input energy (I. e. the rebound value) when the deformed sample is quickly and fully recovered. For pendulum with gravity restoring force, calculate its rebound amount, R -- rebound value%;H -- rebound height mm; For pendulum with spring or torsion wire generating restoring force, it can be calculated by arithmetic formula 2 of springback characteristics of trimming band. Pay attention to the difference between the impact angle and the rebound angle in the formula; the test instrument used is composed of two parts: one part is a simple pendulum and a single degree of freedom mechanical swing device, and the other part is composed of a sample fixture and a dial indicating the elastic value. These two parts should be fixed on a heavy-duty frame with a sample table, and the mass of the frame should be at least 200 times the impact mass to ensure that the machine does not produce displacement during the impact;

This standard requires that the surface strain energy density of the trimmed band must be kept within the range specified above. Various design instruments that meet the above requirements can be used, that is, these instruments can work within various parameter ranges, and the same rebound value can be obtained after precise correction;

According to the characteristics of the instrument and equipment, it is recommended to follow the following steps during testing:

Checking pendulumtrimming beltThe friction force and air friction force often need to check the flexibility of the product. For vertically suspended products, keep a 45-degree angle so that the product is in a static vertical state, then beat the pendulum to a 45-degree angle, and then swing freely with it. The number of simple pendulum shall not be less than 300 times; When checking the friction of the pointer, connect the follow-up pointer with the product with a wire or wire clamp of no more than 5g, and the number of swings shall not be less than 35 times. In most cases, the trimmed edge tape manufacturer cannot make correction calculation, and if more accurate analysis is needed, it can be adopted. In addition, during the test, it should be ensured that the trimmed tape sample is prepared in accordance with the national standard method.

Cut three samples with a length of 250 mm from one PJ V-ribbed belt, and mark a marking line with a spacing of 100mm at the middle position of the PJ V-ribbed belt. When more than three samples cannot be taken from one PJ V-ribbed belt, samples can be cut from the same batch of PJ V-ribbed belt, but must be indicated in the report. 7.4.2 High temperature resistance test method
Place the sample at 100 ℃ ± 2 ℃ for 96 h ± 1 h and then take it out. After standing at laboratory temperature for more than 2h, bend it along a cylinder with a diameter of 20 mm at a contact angle of at least 90 °.