Conveyor belts with textile plies for coalmining - Part 6: Testing
1Key Takeaways
This standard applies to the inspection of textile conveyor belts according to DIN 22109-1, DIN 22109-2 and DIN 22109-4.
2Expert Interpretation
This article provides an in-depth interpretation of the DIN 22109-6:2016-03 conveyor belt testing standard, covering test requirements, method specifications, and safety certification processes. It also provides detailed analysis of the testing standards for key conveyor belt indicators such as breaking strength, abrasion resistance, and flame retardancy, providing professional guidance for conveyor belt quality control in the coal mining industry.
DIN 22109-6 Standard Overview and Technical Background
DIN 22109-6:2016-03 is a test standard for textile conveyor belts used in coal mines, published by the German Institute for Standardization. As a key component of the DIN 22109 series of standards, it specifically specifies test methods and requirements for conveyor belts. Published in March 2016, this standard replaces the 2003 version and reflects the latest developments in conveyor belt testing technology.
The standard covers all textile conveyor belt products specified in DIN 22109-1 (single-core underground conveyor belts), DIN 22109-2 (double-core underground conveyor belts), and DIN 22109-4 (double-core aboveground conveyor belts). The standard was developed based on the coal mining industry's stringent requirements for conveyor belt safety and reliability. In underground coal mining environments, conveyor belts must exhibit excellent flame retardancy, abrasion resistance, and mechanical strength.
Core Test Items and Technical Specifications
DIN 22109-6 specifies a comprehensive test system for conveyor belts, including three categories: physical and mechanical performance testing, safety performance testing, and durability testing.
4.1 Test Sample Requirements
The standard has strict regulations on the sampling quantity and distribution of test samples. According to the total length of the conveyor belt, the number of test samples increases gradually:
| Total length of conveyor belt | Number of test samples | Sample specification requirements |
|---|---|---|
| ≤500 meters | 1 piece | Each sample is a conveyor belt section with full length width and a length ≥700mm, and sampling must be evenly distributed in the entire batch |
| 500-1000 meters | 2 pieces | |
| 1000-2000 meters | 3 pieces | |
| 2000-3500 meters | 4 specimens | |
| 3500-5000 meters | 5 specimens | |
| 5000-7000 meters | 6 specimens | |
| ＞10000 meters | Add 1 specimen every 5000 meters |
4.2 General Test Principles and Data Processing
The standard requires three specimens for each test, and two specimens for the separation force test. Strict statistical methods are used for test data processing: When calculating the average value, if a single value deviates from the average value by more than 10%, it will be discarded and three new specimens will be resampled from adjacent areas. The final average value is calculated from the remaining values and the newly added values.
Testing time requirement: Wait at least 48 hours after the conveyor belt is manufactured before testing to ensure that the material properties are stable.
Detailed explanation of key performance test methods
4.6 Elongation and breaking force test under static load
According to DIN EN ISO 283, the deformation characteristics and breaking strength of the conveyor belt under static tension conditions are tested. During the test, a CRE or CRT type tensile testing machine is used to precisely control the loading rate and environmental conditions.
4.7 Breaking force test after removal of specific tensile members
For single-layer textile conveyor belts, the standard specifies a special test procedure: First, remove the upper and lower covering rubber within a 150mm length of the middle of the specimen, and then use an electric planer to remove the tensile member material along both longitudinal sides.
| Conveyor belt type | Planing thickness requirement | Precision control |
|---|---|---|
| ≤1000/1 type | 1.0mm | ±0.1mm |
| ＞1000/1 type | 1.2mm | ±0.1mm |
4.11.5 Oxygen index test
The oxygen index of the conveyor belt is measured in accordance with DIN 22117, which is a key indicator for measuring the flame retardancy of the material. Conveyor belts used in coal mines, especially underground conveyor belts, are required to have a high oxygen index value to ensure safety in underground operations.
Conveyor belt connection test requirements
4.9.1 Removable connection test
Includes breaking force test (DIN EN ISO 1120) and running time test (DIN 22110-2). The running time test evaluates the performance of the connection under long-term operating conditions through durability testing.
4.9.2 Non-detachable connection test
For non-detachable connection methods such as finger connections, the specimen width must be at least 3 times the finger width and symmetrically distributed. During the test, a tensile testing machine with an accuracy level of 1 is used, the loading speed is (100±10)mm/min, the maximum breaking force is recorded, and the strength value per unit connection width is calculated.
Covering Rubber Performance Test
4.11.1 Hardness Test
Use a Shore durometer in accordance with DIN ISO 7619-1 to measure the indentation hardness of the covering rubber and evaluate the material's compressive and wear resistance.
4.11.2 Tear Strength and Elongation Test
According to DIN 53504, cut S2 type standard specimens from the covering rubber and perform tensile testing. The tear strength is measured to an accuracy of 0.1N/mm², and the tear elongation is measured to an accuracy of 10%. Covering rubber with a thickness of less than 1.5mm is not subject to this test.
4.11.3 Abrasion Resistance Test
Use a rotating drum device in accordance with DIN ISO 4649:2014 Method A to measure the material's abrasion resistance. The results are rounded to integers. Abrasion resistance is an important indicator for evaluating the service life of conveyor belts.
Safety Performance Test Requirements
4.11.6 Safety Technical Tests
Depending on the application environment, electrical and fire safety tests are conducted in accordance with DIN EN 12882 (general applications) and DIN EN 14973 (underground applications). These tests include key safety indicators such as surface resistance and flame retardancy.
Differentiating Tests for Underground and Aboveground Conveyor Belts
The standard clearly distinguishes between test requirements for underground conveyor belts (DIN 22109-1/DIN 22109-2) and aboveground conveyor belts (DIN 22109-4), reflecting the specific performance requirements for conveyor belts in different application environments.
Test Certificates and Quality Assurance
Chapter 5 Test Certificate Requirements
All test results must be included in a test certificate in accordance with DIN EN 10204. Appendix A and B provide sample certificate formats. The certificate type and validity period are contractually agreed upon between the manufacturer and supplier to ensure the integrity of the quality traceability system.
The test certificate must include the following key information: conveyor belt identification, specifications, test results, oxygen index value, surface resistivity, etc. For underground conveyor belts, safety certification-related information is also required.
Standard Implementation Recommendations and Best Practices
Testing Laboratory Construction Requirements
Implementation of the DIN 22109-6 standard requires the establishment of a test laboratory that meets the requirements and is equipped with high-precision testing equipment, including tensile testing machines, hardness testers, abrasion testing machines, and oxygen index meters. The laboratory environment must maintain controlled temperature and humidity to ensure the accuracy and comparability of test results.
Establishing a Quality Control System
Manufacturers are advised to establish a comprehensive quality control system, including raw material inspection, production process control, and finished product testing. Particular attention should be paid to the representativeness of test samples and statistical analysis of test data to ensure consistent product quality.
Technical personnel training requirements
Test operators need to undergo professional training and be familiar with standard requirements, test methods and equipment operation. Regularly participate in proficiency verification and comparison tests to ensure the continuous improvement of testing technology level.
Standard Updates and Technological Development
With the development of conveyor belt technology and the application of new materials, it is recommended to pay close attention to standard updates and technological development trends. Timely adopt new test methods and technical means to improve product quality and technical level.
The implementation of DIN 22109-6:2016-03 standard is of great significance to improving the product quality and use safety of conveyor belts used in coal mines. By strictly implementing the standard requirements, the reliable operation of conveyor belts under harsh working conditions can be ensured, providing strong protection for safe production in coal mines.