Preparation method for intercepting test piece for testing mechanical performance on mining impactor piston

Abstract

The invention discloses a preparation method for cutting a test piece for testing mechanical performance on a mining impactor piston, and belongs to the technical field of mechanical cutting machining, and the preparation method comprises the following three steps: separating the piston, dividing the piston into a small-diameter pipe joint and a large-diameter pipe joint, and cutting a disc A and a disc B; forming and processing the test piece, cutting the test piece from the end surfaces of the disc A and the disc B at equal thickness, reserving the outer wall of the pipe joint for hardness detection, and testing the rest part for other performances; the surface roughness of the test piece is precisely polished and deburred to ensure that the maximum roughness Ra of the to-be-detected surface and the maximum roughness Ra of the non-detected surface are 1.6 microns and 3.2 microns. A test piece is directly cut out from a finished piston, so that the mechanical performance of each part of the piston, especially the performance difference between a small-diameter pipe joint and a large-diameter pipe joint, is accurately reflected. Compared with the prior art, representative test piece data is provided, the manufacturing quality of the piston can be comprehensively evaluated, and the reliability and stability of the mining impactor in a high-load and high-frequency vibration working environment are ensured.

Description

Technical Field

[0001] The present invention belongs to a technical improvement scheme in the field of mechanical cutting processing technology. Specifically, the present invention relates to a method for preparing a test piece for testing mechanical properties cut from a mining impactor piston workpiece, especially a method for preparing a test piece for testing mechanical properties cut from a finished piston. Background Art

[0002] Mining hammer is a special equipment for rock drilling, which is widely used in tunnel excavation, mining and other fields. One of the core components of mining hammer is piston, which transmits impact kinetic energy to the tool through reciprocating motion, so as to achieve the purpose of rock crushing. During normal operation, the built-in piston of mining hammer reciprocates nearly a thousand times per minute, that is, it vibrates nearly a thousand times. Since the built-in piston of mining hammer is a component that directly transmits impact kinetic energy, and transmits impact kinetic energy under high-frequency vibration conditions, given that the working environment of mining hammer is very harsh, the piston should be configured with not only good structural design, but also suitable materials and heat treatment processes, otherwise the mining hammer cannot be used reliably. There are many brands of mining hammers on the market today, but the manufacturing quality is good or bad. Under the same geological conditions, high-quality mining hammers can dig nearly thousands of meters, while high-quality mining hammers can only dig tens of meters. The reason is that the mechanical properties of the pistons of each matching are quite different. In order to ensure the stability and reliability of mining hammers under long-term high-load work, the material and manufacturing process of the piston are particularly critical. At present, most manufacturers of mining impactors attach importance to the quality control of pistons and ensure their quality through strict mechanical property testing. Prior art CN117418851A discloses an impact-rotation combined tunneling excavator, which focuses on improving the integrity of the tunnel rock wall and improving the excavation efficiency. The impact-rotation device involved in this technology can crush rocks through high-frequency impact rotation. However, in the prior art, the method for testing the mechanical properties of the piston of the mining impactor mostly adopts the method of preparing test pieces by sampling from the molten raw material. Although this method can perform basic mechanical property evaluation, it has the following obvious defects and shortcomings: The existing technology usually uses molten raw material sampling, which can only reflect the quality of the raw materials, but cannot fully display the mechanical properties of various parts of the finished piston. Since the working environment of the piston is extremely complex, especially under high-frequency vibration and impact conditions, the mechanical properties of various parts of the piston vary greatly. Therefore, relying solely on raw material specimens cannot accurately reflect the overall performance of the finished piston.

[0003] The mechanical property data obtained by the conventional sampling method in the prior art are often one-sided and cannot fully reflect the performance of the piston in actual work. In particular, when the piston needs to withstand the impact force of different parts, the material properties of each part may differ greatly. Therefore, only the test piece data of the molten raw material cannot quantitatively show the difference in mechanical properties of each part.

[0004] The piston of a mining impactor is generally composed of pipe sections of different diameters, and the materials and processes of each part are different. The existing technology cannot perform separate performance tests on different parts of the piston, which easily leads to substandard performance of some parts during the actual working process of the piston, thus affecting the overall working effect of the impactor.

[0005] The test pieces of the existing technology are usually only used for a single mechanical property test, such as tensile strength or hardness test, and cannot simultaneously conduct comprehensive performance evaluations in multiple dimensions, including metallographic analysis, carburizing quality inspection, impact performance, etc. The lack of comprehensive performance data may lead to the failure to timely discover potential defects in the piston material, thereby affecting the long-term reliability of the mining impactor. Summary of the invention

[0006] The present invention mainly aims at the limitations of the sampling method in the prior art, the one-sidedness of the test data, the inability to reflect the performance of specific parts, and the inability to conduct multi-dimensional performance evaluation. A preparation method for cutting a test piece for testing mechanical properties from a mining impactor piston is proposed. The method is convenient for sampling, and representative test pieces can be cut from the finished piston to accurately reflect the mechanical properties of various parts of the piston, especially the performance differences between the small-diameter pipe section and the large-diameter pipe section. The test piece is easy to prepare, and the measured data is accurate and representative, so that the quality level of various parts of the finished piston can be quantitatively displayed.

[0007] In order to solve the above problems, the present invention provides a method for preparing a test piece for testing mechanical properties cut from a piston of a mining impactor, wherein the piston is a finished product, which is a coaxial assembly composed of two pipe sections with different diameters, and the test pieces are cut from the piston, specifically comprising the following steps: S1, Separation Piston S1.1: Cut a disc A with a thickness of at least 27 mm axially from the small diameter section of the piston; S1.2: Then cut a disc with a thickness of at least 20 mm axially from the large diameter pipe section of the piston; S1.3: The remaining large diameter pipe section forms a round pipe; S2. Specimen Forming Processing S2.1: A specimen 1 with a size of 12x14mm and a specimen 2 with a size of 15x16mm are cut from the end face of disk A with equal thickness. One side of specimen 2 retains the outer wall of the piston small diameter tube section, and its outer wall is used for hardness testing. A CNC milling machine is used with a carbide tool for high-precision cutting to ensure that the cutting surface is flat and free of burrs to avoid affecting the subsequent test results due to the uneven cutting surface.

[0008] S2.2: A specimen 3 with a size of 25x28mm and a specimen 4 with a size of 30x32mm are cut from the end face of the second disc with equal thickness. The outer wall of the piston large diameter tube section is retained on one side of the specimen 4, and its outer wall is used for hardness testing. The CNC milling machine is also used to ensure accuracy through coolant cutting technology. For the second disc, special attention should be paid to the thermal expansion of the material and the thermal deformation that may occur during the cutting process.

[0009] S2.3: Two rectangular strips are cut longitudinally from the wall of the round tube. One of the strips is a 20x20x200mm blank for preparing a Φ16mm standard tensile specimen, and the other is a 10x10x200mm blank for preparing three standard impact specimens. Use a band saw and precision cutting tools for longitudinal cutting to ensure cutting accuracy and avoid excessive heat accumulation during processing to reduce thermal deformation of the workpiece.

[0010] S3, specimen surface roughness S3.1: After the specimen is processed, it is subjected to surface polishing and deburring. The surface to be tested is polished with a precision polishing machine to achieve the required surface roughness. The non-test surface is subjected to ordinary grinding and deburring.

[0011] S3.2: For the roughness control of the test piece's test and non-test surfaces, use a roughness tester to test the test surface to ensure that the maximum surface roughness Ra of the test surface after processing is 1.6μm; the surface roughness requirement for the non-test surface is a maximum Ra of 3.2μm.

[0012] Preferably, the end surfaces of the first and second discs are respectively used to detect the carburizing quality of the piston surface.

[0013] Preferably, in step S2.1, the remaining disk A after the end surface of disk A is cut into specimens 1 and 2 is used as a hardness test piece for the end surface of the piston small-diameter pipe segment.

[0014] Preferably, in step S2.2, the remaining disk B after the end surface of disk B is cut into specimens 3 and 4 is used as a hardness test piece for the end surface of the piston large-diameter pipe segment.

[0015] Preferably, the two pipe sections of the piston specimen are cut radially or obliquely.

[0016] Preferably, the standard tensile test piece is a three-section coaxial assembly, the coaxial assembly has equal diameters at the top and bottom and a middle section that is contracted.

[0017] Preferably, specimen one is used for metallographic analysis of the piston material, specimen two is used to detect the carburizing quality of the outer wall of the small diameter tube section of the piston, specimen three is used for composition analysis of the piston material, specimen four is used to detect the carburizing quality of the outer wall of the large diameter tube section of the piston, specimen one is used for tensile performance testing of the piston material, and specimen two is used for impact performance testing of the piston material.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: By cutting test pieces from different parts of the finished piston, the present invention can accurately and comprehensively reflect the mechanical properties of each part, especially can show the performance differences of different pipe sections caused by material and process differences, which solves the limitation of the prior art that the performance of each part of the piston cannot be fully displayed by sampling only the molten raw materials.

[0019] The present invention adopts test pieces cut into different sizes and shapes, and can simultaneously carry out metallographic analysis, carburizing quality inspection, tensile properties, impact properties and other multi-dimensional comprehensive performance evaluations, which makes up for the deficiency of traditional technology that only relies on a single mechanical property test, and helps to comprehensively evaluate the quality and reliability of piston materials.

[0020] The present invention ensures the representativeness of the test piece by directly cutting the test piece from the finished piston. The test data can more accurately reflect the performance of the finished piston in actual work, has strong representativeness, and the data is more accurate, which effectively avoids the one-sidedness and inaccuracy of the data caused by improper sampling methods in traditional methods.

[0021] The preparation method provided by the present invention is simple and easy, and can directly cut a test piece from a piston. The processing process is relatively simple, and no complicated pre-treatment operation is required, thereby having high production efficiency and low cost.

[0022] By accurately evaluating the performance of different parts of the piston, the present invention can discover potential defects or substandard parts early, which helps to improve the overall quality and long-term reliability of the mining impactor, especially in harsh working environments with high loads and high-frequency vibrations, ensuring the stable operation and long service life of the mining impactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the finished piston of the present invention to be divided into three sections.

[0024] Figure 2 Schematic diagram of the structure for splitting the specimen from disk A.

[0025] Figure 3 Schematic diagram of the structure for splitting the specimen from disk B.

[0026] Figure 4 Schematic diagram of the structure for splitting the specimen from a circular tube.

[0027] In the figure: 1-A disk, 1.1-specimen 1, 1.2-specimen 2, 2-B disk, 2.1-specimen 3, 2.2-specimen 4, 3-round tube, 3.1-standard tensile specimen, 3.2-standard impact specimen. DETAILED DESCRIPTION

[0028] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments.

[0029] A method for preparing a test piece for testing mechanical properties from a piston of a mining impactor, wherein the piston is a matching part of the mining impactor, and is a sample randomly selected from a finished product. In this embodiment, the piston diameter is Φ4100mm. Figure 1 As shown, the piston is a coaxial assembly consisting of two pipe sections of different diameters. The test chamber is a special part used to test mechanical properties. In order to objectively and accurately reflect the actual quality level of each part of the piston, all test pieces are cut from the piston. The specific cutting steps are as follows: S1, Separation Piston S1.1: If Figure 1 As shown, firstly, a disc A 1 with a thickness of at least 27 mm is axially cut from the small diameter pipe section of the piston; S1.2: Then, cut a section of the B disc 2 with a thickness of at least 20 mm axially from the large diameter pipe section of the piston; S1.3: The remaining large diameter pipe section of the piston forms a round pipe 3; S2. Specimen Forming Processing S2.1: If Figure 2 As shown, a piece of specimen 1.1 with a size of 12x14mm and a piece of specimen 1.2 with a size of 15x16mm are cut from the end face of disk A 1 with equal thickness, and specimen 1.2 is required to retain the outer wall of the piston small diameter tube section on one side. The outer wall is used for hardness testing. A CNC milling machine is used with a cemented carbide tool for high-precision cutting to ensure that the cutting surface is flat and free of burrs, so as to avoid affecting the subsequent test results due to the uneven cutting surface. The remaining disk A 1 is used as a hardness test piece for the end face of the piston small diameter tube section.

[0030] S2.2: If Figure 3 As shown, a piece of specimen 3 2.1 with a size of 25x28mm and a piece of specimen 4 2.2 with a size of 30x32mm are cut from the end face of the second circular disc 2 with equal thickness, and the outer wall of the piston large diameter pipe segment is required to be retained on one side of the specimen 4 2.2. The outer wall is used for hardness testing. The CNC milling machine is also used to ensure accuracy through coolant cutting technology. For the second circular disc 2, the cutting process needs to pay special attention to the thermal expansion of the material and the thermal deformation that may occur during the cutting process. The remaining second circular disc 2 is used as a hardness test piece for the end face of the piston large diameter pipe segment.

[0031] S2.3: If Figure 4 As shown, two rectangular strips are cut longitudinally from the tube wall of the round tube 3, one of which is a blank with a size of 20x20x200mm, used to prepare a Φ16mm standard tensile test piece 3.1, and the other is a blank with a size of 10x10x200mm, used to prepare three standard impact test pieces 3.2. A band saw machine and a precision cutting tool are used for longitudinal cutting to ensure cutting accuracy and avoid excessive heat accumulation during processing to reduce thermal deformation of the workpiece.

[0032] S3, specimen surface roughness S3.1: After the specimen is processed, it is subjected to surface polishing and deburring. The surface to be tested is polished with a precision polishing machine to achieve the required surface roughness. The non-test surface is subjected to ordinary grinding and deburring.

[0033] S3.2: Roughness control of the test piece's test and non-test surfaces. Use a roughness tester to test the test surface to ensure that the maximum value of the surface roughness Ra of the test surface after processing is 1.6 μm. In this embodiment, Ra is 1.45 μm. The surface roughness requirement for the non-test surface is that the maximum value of Ra is 3.2 μm. In this embodiment, Ra is 3.0 μm.

[0034] The test pieces made by the above steps have different shapes and positions, and their uses are different. They are introduced as follows: 1. The end faces of the manufactured disc A 1 and disc B 2 are directly used to detect the carburizing quality of the piston surface.

[0035] 2. Specimen 1.1 is used for metallographic analysis of piston material.

[0036] 3. Test piece 1.2 is used to test the carburization quality of the outer wall of the small diameter pipe section of the piston.

[0037] 4. Specimen 2.1 is used for the composition analysis of the piston material.

[0038] 5. Test piece 2.2 is used to test the carburization quality of the outer wall of the large diameter pipe section of the piston.

[0039] 6. Specimen 3.1 is used for testing the tensile properties of piston materials.

[0040] 7. Specimen 3.2 is used to test the impact performance of piston materials.

[0041] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are described in detail below through specific usage methods.

[0042] The specific working process of the present invention is as follows: The working process includes three main stages: separating the piston, the specimen forming process and the specimen surface roughness treatment. The following are the detailed steps and processes of each stage: Separator piston: Figure 1 A schematic diagram of the structure of the piston to be divided into three sections is shown in FIG. 1 , with the cutting positions indicated.

[0043] Step 1: Cut the A-disc 1 from the small diameter tube section of the piston. First, fix the finished piston of the mining impactor on the workbench of the CNC machine tool, and perform precise axial cutting with the CNC tool. During the cutting process, a carbide cutting tool is used to ensure a smooth and high-precision cutting surface to avoid burrs and irregular cutting surfaces. Cutting thickness: Cut a disc 1 of at least 27mm thick from the small diameter tube section of the piston. Use coolant during cutting to reduce friction and temperature effects, extend tool life, and ensure cutting accuracy. Ensure that the cutting thickness and size strictly meet the requirements, and keep the cutting surface smooth for subsequent processing and performance testing.

[0044] Step 2: Cut the second disc 2 from the large diameter tube section of the piston. Use the same CNC cutting technology as step 1 to cut the second disc 2 with a thickness of at least 20 mm from the large diameter tube section of the piston. This step requires precise control of the cutting force and cutting speed during the cutting process to ensure that the size of the second disc after cutting is accurate. Use precision cutting equipment and cooling technology to avoid thermal expansion and deformation of the material during the cutting process, and ensure the flatness of the cutting surface and the accuracy of the size.

[0045] Step 3: The remaining large diameter pipe section is formed into a round pipe 3, which is retained as a subsequent test piece, such as a blank for preparing tensile and impact test pieces. The processing and size of the round pipe are also controlled by a CNC device to ensure that it meets the subsequent processing requirements.

[0046] B. Specimen forming and processing: Step 1: Cut specimen 1.1 and specimen 2 1.2 from the end face of disc 1. Use a CNC milling machine to perform equal thickness cutting on the end face of disc 1 to cut specimen 1.1 with a size of 12x14mm and specimen 2 1.2 with a size of 15x16mm. Use carbide tools and fix the discs with precision fixtures to ensure the accuracy of the size and shape of the specimens during processing. Specimen 2 1.2 retains the outer wall of the small diameter pipe section, which is used for subsequent hardness testing. Use a CNC milling machine for high-precision cutting to ensure that the cut surface is flat and burr-free to ensure the accuracy of the hardness test results. Use precision machining technology to ensure that the size and shape of the specimens strictly meet the requirements to avoid affecting the test results due to machining errors.

[0047] Step 2: Cut specimen 3 2.1 and specimen 4 2.2 on the end face of disc 2. On the end face of disc 2, use the same CNC milling machine technology to accurately cut specimen 3 2.1 with a size of 25x28mm and specimen 4 2.2 with a size of 30x32mm. Specimen 4 2.2 retains the outer wall of the large diameter pipe section of the piston for hardness testing. In order to ensure the accuracy of the specimen and the hardness of the outer wall, special attention should be paid to the cooling and cutting speed control during cutting. In order to prevent the material from deforming due to high temperature, coolant cutting technology is used to ensure that the temperature during cutting is controlled within a reasonable range to ensure cutting accuracy.

[0048] Step 3: Cut the blank on the wall of the round tube 3, and cut two rectangular strip blanks longitudinally on the wall of the round tube 3. The size of each blank is 20x20x200mm, which is used to prepare the Φ16mm standard tensile test piece 3.1, and the size of the other is 10x10x200mm, which is used to prepare three standard impact test pieces 3.2. Use a band saw and a precision cutting tool for longitudinal cutting, and use coolant to avoid deformation caused by overheating of the material. Control the heat accumulation generated during the cutting process and reduce the thermal deformation of the workpiece to ensure the accuracy of the blank and the reliability of subsequent tests.

[0049] C. Surface roughness treatment of specimen: The surface roughness of the specimen directly affects the accuracy of mechanical property testing, especially in hardness testing, metallographic analysis and other performance tests. In order to ensure the accuracy of the test results, the surface of the specimen needs to be finely processed.

[0050] Step 1: Polishing and deburring the surface to be tested. After the specimen is processed, the surface to be tested is precisely polished and deburred. Use a precision polishing machine to polish the surface to be tested so that the surface reaches the required roughness standard. The maximum roughness Ra of the surface to be tested is 1.6μm to ensure a smooth surface without scratches to avoid affecting the subsequent mechanical properties test.

[0051] Step 2: Surface roughness treatment of non-test surface: the surface of non-test surface is subjected to ordinary grinding and deburring treatment to ensure that its roughness reaches the maximum value of Ra 3.2μm. For non-test surface, a simple grinding process is used to remove burrs to ensure that its surface is smooth and meets subsequent requirements. Use a roughness tester to test the surface to be tested and the non-test surface to ensure that the surface treatment of each specimen meets the standard.

[0052] Through the above working process, the present invention can accurately and comprehensively intercept representative test pieces from the finished product of the mining impactor piston. By dividing the piston into multiple parts and intercepting test pieces of different sizes and shapes from each part, these test pieces can be used for multi-dimensional performance tests including metallographic analysis, hardness test, component analysis, carburizing quality test, tensile performance test and impact performance test. Through this method, the mechanical properties of various parts of the piston can be comprehensively and accurately evaluated to ensure the reliability of the piston under high-frequency vibration and strong impact conditions. Through the technical solution of the present invention, the limitations of the sampling method, the one-sidedness of the test data and the inability to comprehensively evaluate the performance of the piston in the prior art can be effectively solved, providing more accurate data support for the quality control of the mining impactor piston, ensuring its reliability and long-term service life in a high-load, high-frequency vibration working environment.

[0053] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features of the invention described herein.

Claims

1. A method for preparing a test piece for testing mechanical properties cut from a mining impactor piston, characterized in that: The piston is a finished product, which is a coaxial assembly consisting of two pipe sections with different diameters. The test pieces are all cut from the piston, which specifically includes the following steps: S1, Separation Piston S1.1: Cut a disc (1) with a thickness of at least 27 mm axially from the small diameter section of the piston; S1.2: Then, cut a disc (2) with a thickness of at least 20 mm axially from the large diameter pipe section of the piston; S1.3: The remaining large diameter pipe segment forms a circular tube (3); S2. Specimen Forming Processing S2.1: A specimen 1 (1.1) with a size of 12 x 14 mm and a specimen 2 (1.2) with a size of 15 x 16 mm are cut from the end surface of the disc A (1) with equal thickness. The outer wall of the piston small diameter pipe section is retained on one side of the specimen 2 (1.2), and the outer wall is used for hardness testing; S2.2: A piece of specimen 3 (2.1) with a size of 25x28 mm and a piece of specimen 4 (2.2) with a size of 30x32 mm are cut from the end surface of disk B (2) with equal thickness. One side of specimen 4 (2.2) retains the outer wall of the piston large diameter pipe section, and the outer wall is used for hardness testing; S2.3: Two rectangular strips are cut longitudinally from the wall of the round tube (3), one of which is a blank with a size of 20x20x200 mm and is used to prepare a Φ16 mm standard tensile test piece (3.1), and the other is a blank with a size of 10x10x200 mm and is used to prepare three standard impact test pieces (3.2); S3, specimen surface roughness S3.1: After the specimen is processed, it is subjected to surface polishing and deburring. The surface to be tested is polished with a precision polishing machine to achieve the required surface roughness. The non-test surface is subjected to ordinary grinding and deburring. S3.2: For the roughness control of the test piece's test and non-test surfaces, use a roughness tester to test the test surface to ensure that the maximum surface roughness Ra of the test surface after processing is 1.6μm; the surface roughness requirement for the non-test surface is a maximum Ra of 3.2μm.

2. The method for preparing a test piece for testing mechanical properties cut from a mining impactor piston according to claim 1, characterized in that: The end surfaces of the first disc (1) and the second disc (2) are respectively used to detect the carburization quality of the piston surface.

3. The method for preparing a test piece for testing mechanical properties cut from a mining impactor piston according to claim 2, characterized in that: In the step S2.1, after the end surface of the first circular disc (1) is cut into the test piece 1 (1.1) and the test piece 2 (1.2), the remaining first circular disc (1) is used as a hardness test piece for the end surface of the piston small diameter pipe segment.

4. The method for preparing a test piece for testing mechanical properties cut from a mining impactor piston according to claim 2, characterized in that: In the step S2.2, the remaining disk B (2) after the end surface of the disk B (2) is cut into the test piece 3 (2.1) and the test piece 4 (2.2) is used as a hardness test piece for the end surface of the piston large diameter pipe segment.

5. The method for preparing a test piece for testing mechanical properties cut from a mining impactor piston according to claim 1, characterized in that: The two pipe sections of the piston test piece are cut in a radial direction or in an oblique direction.

6. The method for preparing a test piece for testing mechanical properties cut from a mining impactor piston according to claim 1, characterized in that: The standard tensile test piece (3.1) is a three-section coaxial assembly, wherein the coaxial assembly has equal diameters at the top and bottom and a constricted middle section.

7. The method for preparing a test piece for testing mechanical properties cut from a mining impactor piston according to claim 1, characterized in that: The test piece 1 (1.1) is used for metallographic analysis of the piston material, the test piece 2 (1.2) is used for detecting the carburizing quality of the outer wall of the small diameter pipe section of the piston, the test piece 3 (2.1) is used for component analysis of the piston material, the test piece 4 (2.2) is used for detecting the carburizing quality of the outer wall of the large diameter pipe section of the piston, the test piece (3.1) is used for tensile property testing of the piston material, and the test piece (3.2) is used for impact property testing of the piston material.

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