A device and method for evaluating the wear resistance of relatively low hardness metal materials

Abstract

The present invention relates to the field of surface properties of metal materials, and is a device and method for evaluating the wear resistance of metal materials with lower hardness. Different from the existing ideas, this method uses a softer medium to rub a harder material for a long time to obtain the difference in wear resistance of different materials. It can more objectively evaluate the wear resistance of metal materials with lower hardness under the same conditions, and the test results are more consistent with the actual operation results. Specifically, the sample to be tested is fixed in a sample slot, and no other wear media such as liquids and abrasives are required. The rubber wheel and the sample form a friction pair. When the test is carried out, the rotating rubber wheel performs relative sliding friction motion on the sample, and at the same time, a certain positive pressure of 70N-100N is applied to the rubber wheel using a lever device and a weight to increase friction. After the rubber wheel rotates a total of 10000r, the absolute weight loss is measured using an analytical balance with an accuracy of 1 / 10000g to obtain the wear resistance parameters of the metal material. The method is simple to operate and easy to implement, and the results are consistent with the actual situation.

Description

Technical Field

[0001] The present invention relates to the field of surface properties of metal materials, and in particular to a device and a method for using the device to evaluate the wear resistance of metal materials with relatively low hardness. Background Art

[0002] While existing wear resistance testing and evaluation methods vary, they are all designed for high-hardness and high-wear-resistance wear-resistant steels, tool steels, and surface-modified metals. Traditional methods, such as dry grinding with hard materials and wet grinding with hard abrasives, typically employ reciprocating friction between the test material and a relatively hard medium, such as bearing balls or quartz sand. These methods are not suitable for evaluating the wear resistance of materials such as structural or container steel. In recent years, technological advancements and increased production efficiency have placed higher demands on the performance of structural steel in many applications, making the wear resistance of structural components a key performance indicator. However, when testing structural steel using existing wear resistance testing standards and methods, the hardness of these steels is generally ≤ HV300, while the hardness of the wear medium used in wear tests is much greater than this value. This results in indistinguishable test results for materials of varying hardness, making it impossible to compare their wear resistance. This makes it difficult to provide valuable guidance on material selection in engineering applications where wear resistance is critical. Under the above-mentioned premise, after extensive research on existing wear test devices and evaluation methods, the wear resistance test method suitable for low-hardness metal materials in the patent of this invention was proposed.

[0003] The purpose of the present invention is to more accurately and objectively evaluate the wear resistance of metal materials with lower hardness and their weld metals so as to correctly select materials according to different usage requirements. Summary of the Invention

[0004] The purpose of the present invention is to address the above problems and provide a device and method for evaluating the wear resistance of relatively low hardness metal materials.

[0005] The object of the present invention is achieved as follows: A device for evaluating the wear resistance of relatively low-hardness metal materials, comprising a test cavity (1), a rubber wheel (2), a sample groove (3), an L-shaped lever (6), a cam (7), a weight (8), an electric motor (9), a first coupling (10), a test platform (11), a reducer (12), an LED display control panel (13), a photoelectric counter (14), a second coupling (15) and an end cover (16) of the cavity, wherein the short arm end (4A), the long arm end (4B) of the L-shaped lever (6), the lever shaft (5) and the weight (8) form a clamping device, which transmits the weight of the weight to the sample and the rubber wheel to generate friction. The motor (9) drives the rubber wheel (2) to rotate after being decelerated by the reducer (12). The speed of the motor (9) can be adjusted (low speed and high speed) through the control panel (13). The sensor of the photoelectric counter (14) is placed on the side of the reducer output shaft to monitor the rotation of the shaft. Each time the shaft rotates once, the counter increases by 1. The LED on the control panel can display the total number of rotations. The above components constitute the power and control system of the device.

[0006] A method for using a device for evaluating the wear resistance of relatively low-hardness metal materials: comprising the following steps: Step 1: first, the material is processed into a sample, and after the surface is polished and smooth, the oil, moisture and impurities on the surface are cleaned, and then the sample is dried and weighed on an analytical balance with an accuracy of 0.0001g; Step 2: The sample is placed in the sample slot on the short arm side of the lever in the test chamber, and is fixed and clamped with the side baffle and bolts of the sample slot. The middle part of the friction rubber wheel is a cast steel material with a positioning groove, which is matched with the protruding key on the rotating shaft of the reducer. The rubber wheel and the specimen are fixed together on the rotating shaft and fixed with nuts to prevent axial movement; after installation, the side of the test cavity is closed with end covers, and the rotating rubber wheel and the specimen are subjected to wear tests in the cavity to form a semi-closed cavity; Step 3: During the experiment, the specimen applies positive pressure to the rubber wheel to obtain friction, which is achieved through a lever device, that is, a weight with a nominal weight of 70 or 100N, which is converted to 70N on the specimen side, is hung at the long end of the lever, and the specimen slot is located at the short end of the lever and is subjected to an equivalent pressure of 70 or 100N. To facilitate specimen installation and removal, a cam mechanism is provided to lift the lever to separate the specimen from the rubber wheel, or lower it to contact the wheel. Step 4: After turning on the counter, it begins counting automatically at 180 rpm. After 500 rpm, the rubber wheel overheats and softens, emitting smoke and dust, making it unable to continue rotating normally and causing vibration. Simultaneously, the friction coefficient decreases due to the increased temperature. At this point, the stop button is pressed. The wheel is then allowed to cool naturally for 15 minutes. The wheel is then rubbed for another 500 rpm, then stopped again and cooled for 15 minutes. This process is repeated. Step 5: After a total of 10,000 rpm, the specimen is removed, cleaned, thoroughly dried, and weighed. The absolute weight loss is calculated to the nearest 0.0001 g. Step 6: For specimens less than 6 mm thick, similarly sized specimens can be processed and stacked to a thickness of 6 mm. These specimens are then fixed in the specimen holder for testing. Step 7: When the rubber wheel has a Shore hardness of less than 50 after long-term use, it is no longer suitable for wear testing.

[0007] The present invention provides a quantitative evaluation method for the wear resistance of relatively low-hardness metal materials, such as structural steel. This method can be used to compare the surface wear resistance of candidate materials to determine the most preferred material to minimize lifecycle costs. This method simulates the actual operating conditions of workpieces to the greatest extent possible, is simple to operate, and is easily implemented. The test results are also highly convincing and reliable, making it a method worthy of widespread use. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention will be further described below in conjunction with the accompanying drawings.

[0009] Figure 1 It is a top view of the overall structure of the wear-resistant testing machine.

[0010] Figure 2 This is a front view of the schematic diagram of the wear test principle.

[0011] Among them, 1-rotating cavity, 2.-rubber wheel, 3-sample slot (embedded sample), 4A-short lever arm, 4B-long lever arm, 5-lever shaft, 6-L-shaped lever, 7-cam, 8-weight, 9-motor, 10-coupling 1, 11-test bench, 12-reducer, 13-display and control panel, 14-photoelectric counter, 15-coupling, 16-cavity end cover. DETAILED DESCRIPTION

[0012] During the service life of metal workpieces, friction occurs due to contact with the working medium, which causes wear and tear, resulting in a reduction in the effective cross-sectional thickness and failure. Therefore, the surface wear resistance of metal materials is also an important indicator for evaluating their performance. Currently, there are a variety of experimental devices and methods to evaluate the wear resistance of metal materials, including traditional methods such as dry grinding of hard materials and wet grinding of hard abrasives. This type of method generally uses materials with relatively high hardness, such as bearing steel balls, quartz sand, and other media to rub the test materials, while applying a certain positive pressure to increase the friction force. The limitation of this method is that due to the high hardness of the wear medium, it has a strong grinding force, and has a strong grinding amount for metal materials with low surface hardness (≦HV300). Therefore, under the same test conditions, the grinding loss weight obtained from the test of metal materials with different hardness is almost the same, which leads to the test results of metal materials with different hardness and wear resistance being close, making it impossible to evaluate the wear resistance of metal materials.

[0013] Generally speaking, the higher the surface hardness and strength of a material, the better its wear resistance. Wear resistance is a crucial performance indicator for metal workpieces subjected to abrasive conditions. Good wear resistance extends the workpiece's service life, thereby reducing lifecycle costs and maintenance costs. Under the same operating conditions, higher wear resistance also improves the workpiece's quality. Therefore, wear resistance has always been a key performance indicator of concern to engineers. In addition to hardness and strength, factors influencing wear resistance include the material's crystal structure, operating temperature and humidity, plasticity and toughness, inclusions and metallurgical defects, and surface roughness. Various experimental setups and evaluation methods exist for wear resistance, including weight loss, dimensional change, surface topography, and indentation. The weight loss method is the most widely used and easily implemented, using an analytical balance to measure the weight change of a specimen before and after the test to evaluate the material's wear resistance. This method has the advantages of simple operation, high sensitivity, and intuitive results, but it has high requirements on the cleanliness and dryness of the sample to avoid the influence of oil, water or other impurities on the measurement results.

[0014] The wear test method employed in this invention utilizes the absolute weight loss method, a new evaluation method developed based on numerous abrasive wear test methods. In engineering applications, improvements in mechanical performance and efficiency have led to higher demands for reduced energy consumption. During operation, workpieces experience wear and tear from contact with materials, which not only reduces the lifespan of the machine but also, because the wear process is also an energy-wasting process, increases energy consumption and reduces efficiency. Therefore, the wear resistance of materials has become a key consideration during material selection.

[0015] In the conveying machinery industry, such as ore or coal conveyors, materials are transported over long distances via belts. The belts are driven forward by the rotation of the rollers in contact with them. During this process, friction between the belt and the barrel material causes wear, leading to a continuous decrease in the effective thickness of the barrel wall. When this decreases to a certain level, the barrel wall becomes unusable and fails, marking the end of the entire conveying system's lifespan. Therefore, the wear resistance of the barrel material significantly determines the service life and cost of the equipment. Therefore, wear resistance has become a key performance indicator for material selection, and further research and improvement are needed to objectively evaluate the wear resistance of materials.

[0016] In the early stage, the traditional wet grinding test of abrasive wear was used, that is, the method of grinding the sample in water using quartz sand. The results showed that for metal materials with different hardness, their hardness was HV154, HV198 and HV245 respectively, the weight loss measured by this method was almost the same. Analysis believes that this is because quartz has an extremely high hardness (HV1000 or above), which is much greater than the hardness of the test metal materials. Therefore, for metal materials with hardness far lower than its own hardness, the grinding force is too strong, resulting in no significant difference in the test results. The dry wear test of the material using quartz sand also showed that whether it is wet abrasive wear or dry abrasive wear, the results obtained cannot distinguish the difference in wear resistance between metal materials of different hardness. When using bearing balls with a hardness similar to that of steel to perform reciprocating friction wear tests on metal material surfaces, because the test results of this method are greatly affected by the roughness of the material surface, sometimes the weight loss measured for samples with high surface hardness will be large, which cannot accurately reflect the true wear resistance of the material. Therefore, it is necessary to change the experimental design ideas to apply to the wear resistance evaluation of metal materials.

[0017] To address the problem that existing wear resistance test equipment and evaluation methods are not suitable for metal materials with lower hardness, such as structural steel or stainless steel, and to objectively evaluate the true wear resistance of metal materials, a new wear resistance test device and evaluation method have been designed based on a large number of experiments. Its unique feature is that instead of using a high-hardness wear medium, a hard rubber wheel with a wear medium lower in hardness than the metal material is used to perform a long-term sliding dry friction wear test on the specimen. Although the test cycle is long and the rubber wheel wear is large, the experimental results have real and objective reference value and can accurately reflect the differences in wear resistance between metal materials of different hardness.

[0018] The present invention is an experimental device and method for evaluating metal materials with lower hardness and their wear resistance under atmospheric corrosion conditions. It solves the problem that the existing wear resistance test method is only applicable to evaluating materials such as wear-resistant steel and tool steel with higher hardness, but not applicable to the wear resistance of structural steel materials and weld metal with lower hardness. Its innovation and characteristics are that, unlike the existing idea of ​​using high-hardness grinding media for wear tests, the idea of ​​this experimental design is "using softer media to rub harder materials for a long time to obtain the difference in wear resistance of different materials", so it can more objectively evaluate the wear resistance of metal materials with lower hardness (including weld metal) under the same conditions. The test method was used to evaluate the wear resistance of stainless steel and carbon structural steel. On this basis, it was recommended to users that stainless steel with better wear resistance and longer service life be used and successfully applied in production practice. After a period of actual operation, actual measurements were carried out, and the results showed that the actual operation results were highly consistent with the test evaluation conclusions. This method secures the sample to be tested in a specimen tank. No other abrasive media, such as liquids or abrasive particles, are required. Instead, a rotating rubber wheel is used to create relative sliding friction against the sample. During the test, a certain positive pressure (70N-100N) is applied to the wheel. After the wheel rotates a total of 10,000 revolutions, the absolute weight loss is measured using an analytical balance with an accuracy of 1 / 10,000g to obtain the wear resistance parameters of the metal material.

[0019] This test method is applicable to metal materials with lower hardness (HV ≤ 300) such as stainless steel, ordinary carbon steel, aluminum alloy, and titanium alloy. It can also evaluate the wear resistance of weld metal (melt width greater than 1 cm). The experimental results obtained have relatively accurate reference value. It is not suitable for wear resistance testing of tool steel, abrasive steel, and cemented carbide with higher hardness, as well as metal surfaces treated by spraying hard powder or depositing hard materials. When conducting wear resistance tests on welds, the weld must be machined flush with the base material before testing.

[0020] The device for implementing the present invention includes a test platform (11), an electric motor (9), a speed reducer (12), a coupling (10, 15), a photoelectric counter (14), an LED display and a control panel (13), a sample tank (3), a rubber wheel (2), a rotating cavity (1), a lever device (4, 5, 6) and a weight (8). The design idea of ​​the experimental method is to "use a hard rubber wheel with a lower hardness to rub a metal material with a higher hardness for a long time, and evaluate the wear resistance of different metal materials under the same test conditions." This is to avoid the experimental design defect that the grinding force of metal materials with different hardness is very different when using a wear medium with a higher hardness than the metal material, resulting in similar test results and inability to evaluate metal materials with different wear resistance.

[0021] The short arm end (4A), long arm end (4B), lever shaft (5), and weight (8) of the L-shaped lever (6) in the wear test device form a clamping device, which transfers the weight of the weight to the sample (fixed in the sample groove) and the rubber wheel (2) to generate friction. The motor (9) drives the rubber wheel (2) to rotate after being decelerated by the reducer (12). Its speed can be adjusted (low speed and high speed) through the control panel (13). The sensor of the photoelectric counter (14) is placed on the side of the reducer output shaft to monitor the rotation of the shaft. Each time the shaft rotates, the counter increases by 1, and the LED on the control panel can display the total number of rotations. The above components constitute the power and control system of the device.

[0022] This method is suitable for evaluating the wear resistance of relatively low-hardness metal materials operating in atmospheric corrosion conditions, with ambient temperatures ranging from -20°C to 40°C and relative humidity ranging from 0% to 60%. The friction media in contact with the materials can be metal or non-metallic, such as rubber, coal, or ore. The evaluation metric is absolute weight loss, making it suitable for comparing different materials within the same group under the same test conditions.

[0023] The friction tool used is composed of a steel disc with a chlorobutyl rubber ring molded and vulcanized on its outer surface. The Shore hardness of the rubber ranges from 60 to 80. If the hardness is less than 50, it cannot be used.

[0024] The specific steps of the test method of the present invention are as follows.

[0025] 1. First, process the material into a size of 6×25.5×57.5mm 3 The sample was polished smooth, cleaned of oil, water and other impurities on the surface, dried thoroughly and weighed on an analytical balance with an accuracy of 0.0001g.

[0026] 2. Place the specimen into the specimen slot in the rubber wheel wear tester and clamp it with a fixture. The friction rubber wheel has a diameter of 176mm. The middle part is made of cast steel with a positioning groove. It is fixed to the rotating shaft with the upper key of the rotating shaft and fixed with a nut to prevent movement. The hardness of the rubber wheel is about 70 Shore hardness (about HV18), which is much lower than the hardness of the metal material used for the test. At the same time, due to the large difference in surface hardness, the rubber also has a certain degree of elasticity, which avoids the problem of the friction coefficient being affected by the surface roughness of the metal material, making the experimental results more objective and true, close to the actual situation. After installation, use the end cap to seal the side of the rotating test chamber to form a semi-enclosed rotating chamber.

[0027] 3. During the experiment, the specimen must apply a certain positive pressure to the rubber wheel to generate friction. This is achieved through an L-shaped lever arrangement. A weighted mass is suspended from the long end of the lever, while the specimen slot is located at the short end of the lever. This allows the smaller mass to exert greater pressure on the specimen. Depending on the mass of the mass, the equivalent pressure applied to the specimen is 70-100N. To facilitate specimen installation and removal, a cam mechanism is provided to raise the lever (separating the specimen from the rubber wheel) or lower it (contacting the specimen with the rubber wheel).

[0028] 4. After turning on, the counter starts counting automatically at a speed of 180 rpm. After 500 rpm, the rubber wheel overheats and softens, accompanied by smoke and dust emission, and cannot continue to rotate normally and begins to shake. At the same time, the friction coefficient also decreases due to the increase in temperature. At this time, press the stop button, cool the rubber wheel naturally for 15 minutes, then continue to rub for 500 rpm, stop again, and cool for 15 minutes. Repeat the above process.

[0029] 5. After the total number of revolutions reaches 10,000, remove the sample, clean it, dry it thoroughly, and weigh it. Calculate the absolute weight loss (accurate to 0.0001 g).

[0030] 6. For specimens with a material thickness of less than 6mm, specimens of the same size can be processed and stacked together to make the thickness reach 6mm and then fixed in the specimen slot for testing.

[0031] 7. When the Shore hardness of a rubber wheel is less than 50 after long-term use, the rubber wheel is no longer suitable for wear testing.

[0032] The following provides a clear and complete description of the specific experimental methods and results, using examples. These examples represent only a set of comparative examples of the wear resistance of metal materials and are not intended to be exhaustive. Their purpose is to illustrate the guiding role of this experimental method in evaluating the wear resistance of metal materials for practical engineering applications, as well as the degree of consistency between the results and actual operational results. Other examples obtained by persons of ordinary skill in the art using the same or similar experimental methods without inventive effort are intended to fall within the scope of protection of this invention.

[0033] Belt conveyors are a common type of conveying machinery used in the coal mining industry. Coal is transported long distances by belts, which are driven forward by the rotation of supporting rollers. During this process, significant friction is generated between the belt and the rollers, causing them to continuously wear out during service. When the belts reach a certain wall thickness, they lose strength and fail, necessitating replacement. Therefore, the wear resistance of the roller material determines the lifespan of the conveyor. Traditional belt conveyor rollers are made of Q345B carbon steel, which has a short service life due to its poor corrosion and wear resistance. To extend the belt conveyor's service life to 5,000 hours, 410 stainless steel, which offers excellent corrosion and wear resistance, was selected as the roller material.

[0034] To further verify the correctness of the material selection, comparative wear resistance experiments were conducted using the experimental apparatus and evaluation methods described in this invention. Furthermore, for further comparison with other materials, 301, 304, and 2101 stainless steels were also compared in the same set of experiments. The experimental procedures were strictly followed as described in the Summary of the Invention. The results are shown in Table 1.

[0035] Table 1 Rubber wheel friction and wear test results (test conditions 700000 r·N)

[0036] Material Original weight g Final mass g Weight loss g 410 stainless steel 62.3538 62.3245 0.0293 304 stainless steel 71.7716 71.7434sqj 0.0282 345B carbon steel 62.0316 61.9702 0.0614 2101 stainless steel 67.6409 67.6234 0.0175 301 stainless steel 68.1681 68.1356 0.0325

[0037] The results show that the absolute weight loss of 410 stainless steel is only about 1 / 2 of that of 345B carbon steel. It can be considered that the wear resistance of 410 stainless steel is doubled compared with 345B, that is, the service life is correspondingly doubled, making it an ideal alternative material. After the rollers with 410 stainless steel barrels were equipped with a belt conveyor in a coal mine and operated for 10,000 hours, the pipe wall thickness was sampled and tested. The test results were compared with the test results of 345B materials used in the same period. The barrel was smooth and the thickness reduction was only about 1 / 2 of that of 345B materials. The actual application results of the project were basically consistent with the wear resistance test results, further verifying the practicality, objectivity and accuracy of this test device and method.

[0038] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by any technician in this field within the scope of the present invention are included in the patent scope of the present invention.

Claims

1. A method for using a device for evaluating the wear resistance of relatively low-hardness metal materials, characterized in that: The device comprises a test cavity (1), a rubber wheel (2), a sample groove (3), an L-shaped lever (6), a cam (7), a weight (8), a motor (9), a first coupling (10), a test platform (11), a reducer (12), an LED display control panel (13), a photoelectric counter (14), a second coupling (15) and an end cover (16) of the cavity. The short arm end (4A), the long arm end (4B) of the L-shaped lever (6), the lever shaft (5) and the weight (8) form a clamping device, which transfers the weight of the weight to the sample and the rubber wheel to generate friction. The motor (9) drives the rubber wheel (2) to rotate after being decelerated by the reducer (12). The speed can be adjusted through the LED display control panel (13) to be divided into low speed and high speed. The sensor of the photoelectric counter (14) is placed on one side of the reducer output shaft to monitor the rotation of the shaft. Each time the shaft rotates once, the counter increases by 1. The LED on the LED display control panel can display the total number of rotations. The above components constitute the power and control system of the device. The method of using the device includes the following steps: Step 1: First, process the material into a sample, polish the surface smoothly, clean the oil, moisture and impurities on the surface, dry it, and weigh it on an analytical balance with an accuracy of 0.0001g; Step 2: Place the sample into the sample slot on the short arm side of the lever in the test chamber and secure it with the side baffles and bolts. The middle part of the friction rubber wheel is made of cast steel with a positioning groove. It is fixed to the rotating shaft with a protruding key on the reducer and fixed with a nut to prevent axial movement. After installation, the side of the test chamber is sealed with an end cap. The rotating rubber wheel and the sample are subjected to wear testing in the chamber, forming a semi-enclosed chamber. Step 3: During the experiment, the sample applies positive pressure to the rubber wheel to obtain friction. This is achieved through a lever device. That is, a weight with a nominal weight of 70 or 100N is hung on the long end of the lever, which is converted to 70N on the sample side. The sample slot is located at the short end of the lever and is subjected to an equivalent pressure of 70 or 100N. To facilitate the installation and removal of the sample, a cam device is provided to lift the lever to separate the sample from the rubber wheel or lower it to contact the rubber wheel. Step 4: After turning on, the counter starts counting automatically at a speed of 180 rpm. After 500 rpm, the rubber wheel becomes overheated and softened, accompanied by smoke and dust emission. It cannot continue to rotate normally and starts to shake. At the same time, the friction coefficient decreases due to the temperature increase. At this time, press the stop button and let the rubber wheel cool naturally for 15 minutes. Then continue to rub for 500 rpm, stop again, and cool for 15 minutes. Repeat the above process. Step 5: After the total number of revolutions reaches 10,000, remove the sample, clean it, dry it thoroughly, and weigh it. Calculate the absolute weight loss to the nearest 0.0001 g. Step 6: For samples with a thickness of less than 6mm, samples of the same size can be processed and stacked together to make the thickness up to 6mm and then fixed in the sample slot for testing; Step 7: When the Shore hardness of the rubber wheel is less than 50 after long-term use, the rubber wheel is no longer suitable for wear testing.

Images