The breaking force test is a crucial part in evaluating the quality and performance of round steel chain. It is an indispensable item in the factory inspection process for mining chains, lifting chains, and bucket elevator conveyor chains, and it is also one of the conventional means to test the performance of chain products.
I. Test Purposes
1. Quality Inspection
To determine the maximum tensile force that the round steel chain can withstand, so as to verify whether the chain meets the design requirements and relevant standards.
2. Safety Assessment
To provide data support for the safety factor of the round steel chain in practical applications. In many high-risk industrial application scenarios, such as mining equipment and lifting equipment, understanding the breaking force of the chain helps to determine the appropriate safe working load and ensures the safety of personnel and equipment during operations.
II. Test Equipment
1. Tensile Testing Machine
This is the core equipment for conducting the breaking force test of round steel chains. It can apply tensile force at a stable speed and accurately measure the magnitude of the tensile force. The range of the tensile testing machine needs to be selected according to the specifications and expected breaking force of the chain. Generally, it is required that the maximum tensile capacity of the machine should exceed a certain proportion (for example, 150% - 200%) of the expected breaking force of the chain to ensure that the chain can be fully tested until it breaks.
The tensile testing machine is usually equipped with a high-precision force sensor, which can accurately record the tensile force values and has data recording and analysis functions, facilitating the subsequent viewing and processing of test data.
2. Fixtures
Fixtures are used to fix both ends of the chain. The design of the fixtures should ensure that they can firmly clamp the chain and prevent the chain from slipping out during the test process. For different sizes and types of chains, specially designed fixtures may be required. For example, for round link chains, the fixtures usually have a structure with special-shaped slots that can closely fit the chain links and ensure that the tensile force is evenly distributed on the chain.
III. Preparation of Test Samples
1. Sampling Method
For chains produced in batches, test samples need to be selected according to certain sampling standards. Generally, a random sampling method is adopted, and it is necessary to ensure that the number of sampled samples meets the requirements of relevant standards. For example, in some standards, it is stipulated that for each batch of round steel chains, the sampling proportion shall not be lower than a certain percentage (such as 5% - 10%), and the minimum number of sampled samples shall not be less than the specified number of pieces (such as 3 - 5 pieces).
2. Sample Pretreatment
Before conducting the breaking force test, it is necessary to inspect the sample chains to ensure that there are no obvious defects, such as cracks or deformations. At the same time, the basic information of the chains, such as size, model, and production batch, should be recorded for subsequent analysis and traceability of the test results.
IV. Test Process
1. Installation of Samples
Install the prepared round steel chain samples on the fixtures of the tensile testing machine. Pay attention to ensuring that the installation direction of the chain is correct and that the chain is in a naturally straightened state in the fixtures, avoiding twisting or bending. After clamping the chain, it is necessary to check again whether the fixtures are firm to ensure that the tensile force can be evenly applied to the chain.
2. Setting of Test Parameters
Set appropriate tensile speeds on the tensile testing machine according to the type and test requirements of the chain. Generally, the tensile speed should not be too fast to avoid affecting the accuracy of the test results. For example, for the breaking force test of mining round link chains, the tensile speed is usually set between 10 - 30 mm/min. Meanwhile, the frequency of data acquisition should also be set so that the change process of the breaking force can be accurately recorded.
3. Start of the Test
Start the tensile testing machine and begin to apply tensile force. During the test process, the force sensor of the tensile testing machine will record the magnitude of the tensile force in real time and transmit the data to the computer control system for storage and display. Observe the deformation of the chain under the action of the tensile force. When the chain breaks, the tensile testing machine will automatically stop applying the tensile force and record the maximum tensile force value at this time, which is the breaking force of the chain.
V. Analysis of Test Results
1. Judgment of Breaking Force Values
Compare the measured breaking force value obtained from the test with the design breaking force standard of the chain. If the measured breaking force is greater than or equal to the standard breaking force, it indicates that the strength of the round steel chain meets the requirements; if the measured breaking force is lower than the standard breaking force, further analysis of the reasons is needed, which may be due to problems with the quality of raw materials, defects in the manufacturing process, or improper operation during the test process.
2. Fracture Analysis
Observe and analyze the fracture surface of the round steel chain after it breaks. Different fracture causes will present different characteristics on the fracture surface. For example, if the fracture is caused by material fatigue, fatigue striations may appear on the fracture surface; if the fracture is caused by poor welding quality, pores, slag inclusions and other defects may appear near the weld. Through fracture analysis, a basis can be provided for improving the manufacturing process or quality control measures of the chain.
IPv6 network supported