A method of polishing a metal diaphragm of a diaphragm compressor

Abstract

The present disclosure relates to a polishing method for a diaphragm compressor metal diaphragm, comprising the following steps: S1, mounting the metal diaphragm above a polishing base with a lower polishing disc; S2, applying polishing paste on the surface of the metal diaphragm or the polishing cloth; mounting an upper polishing disc wrapped with polishing cloth and provided with a cooling water channel above the metal diaphragm; S3, pressing the upper polishing disc and the lower polishing disc and polishing the metal diaphragm; the polishing paste is Al2O3 particles and / or SiO2 particles with a particle size of 0.1-20 microns, preferably 1-10 microns. After the polishing treatment, the surface roughness of the metal diaphragm is reduced, the surface residual stress is reduced, the diaphragm does not curl, and the fatigue resistance of the diaphragm is improved.

Description

Technical Field

[0001] This disclosure relates to the field of hydrogen energy, and more specifically, to a method for polishing a metal diaphragm sheet of a diaphragm compressor. Background Technology

[0002] A diaphragm compressor is a reciprocating compressor that compresses and transports gases by the reciprocating motion of a metal diaphragm within a cylinder. Due to its structure, diaphragm compressors are widely used for compressing various high-purity gases, rare and precious gases, toxic and harmful gases, and corrosive gases. Their main application areas include: energy, petrochemicals, electronics, materials science, and defense.

[0003] A metal diaphragm compressor compresses gas by deforming a diaphragm in the oil chamber through piston compression, thereby changing the volume of the gas chamber. The diaphragm is the most critical and easily damaged component in the compressor's operation. The main forms of diaphragm damage are twisting deformation, collapse, wear cracks, and mechanical fatigue. Under the pressure difference between liquid and gas, the metal diaphragm is subjected to alternating loads, resulting in flexural deformation and fatigue failure. Many factors affect diaphragm lifespan, such as the mechanical properties of the diaphragm material; poor surface smoothness; stress concentration caused by surface residues and impurities; and the fact that a thin diaphragm is prone to breakage, while an excessively thick diaphragm reduces its flexural deformation capacity.

[0004] The article "Xu Zhongyi. Analysis of Diaphragm Cracking Failure in Diaphragm Compressors. Refining & Chemical Industry, 2013(5):3" points out that fatigue streaks were found in the large-area propagation zone of the diaphragm crack fracture surface, and no corrosion products were found in the fracture propagation zone. Furthermore, no branching phenomenon was observed in the crack propagation in the metallographic structure, indicating that stress corrosion was not involved in the crack propagation process, and mechanical fatigue was the main cause of failure. The pits on the diaphragm surface are the main crack initiation sites. The fatigue performance of the diaphragm mainly depends on the surface roughness; the lower the surface roughness, the better the fatigue resistance of the diaphragm.

[0005] Although patent CN201715036U provides a method for modifying the surface of a metal diaphragm by coating an oxide layer on the diaphragm surface to improve its fatigue resistance, the surface roughness of the diaphragm is not reduced. Therefore, in the long run, this method cannot improve the fatigue performance of the material.

[0006] Therefore, problems such as reducing the surface roughness of metal diaphragms and improving their fatigue resistance urgently need to be solved. Summary of the Invention

[0007] The purpose of this disclosure is to provide a polishing method for a metal diaphragm of a diaphragm compressor. After polishing, the surface roughness of the metal diaphragm is reduced, the surface residual stress is reduced, the diaphragm does not curl, and the fatigue resistance of the diaphragm is improved.

[0008] To achieve the above objectives, this disclosure provides a polishing method for a metal diaphragm sheet of a diaphragm compressor, the polishing method comprising the following steps: S1. The metal diaphragm is installed on top of a polishing base with a lower polishing disc; S2. Apply polishing paste evenly to the surface of the metal diaphragm or the polishing cloth; install the upper polishing disc, which is wrapped with polishing cloth and has a cold water channel, above the metal diaphragm; S3. Press the upper and lower polishing discs together to polish the metal diaphragm; The polishing paste is selected from Al2O3 particles and / or SiO2 particles, and the particle size of the polishing paste is 0.1-20μm, preferably 1-10μm.

[0009] Optionally, the material of the metal diaphragm is selected from one of GH4169, 316L, 00Cr15Ni5, Hastelloy, or nickel-based alloys.

[0010] Optionally, in step S1, the metal diaphragm and the lower polishing disc are installed by magnetic or electrostatic adsorption.

[0011] Optionally, the upper polishing disc and the lower polishing disc are each made of stainless steel.

[0012] Optionally, the size of the upper polishing disk is 0.5-1.5 times that of the lower polishing disk.

[0013] Optionally, the polishing cloth has a thickness of 2-6mm and is made of synthetic natural fibers or abrasion-resistant wool fibers.

[0014] Optionally, step S3 further includes: during the polishing process, opening the cold water channel of the upper polishing disc to rinse the upper polishing disc and the lower polishing disc.

[0015] Optionally, the temperature of the cooling water is less than 10°C.

[0016] Optionally, in step S3, the polishing time is 15-60 min, the pressure applied by the upper polishing disc to the metal diaphragm is 20-100 kPa, and the amount of polishing paste used is 5-10 g.

[0017] Optionally, the surface roughness of the polished metal film is less than 0.1 μm, and the warpage is 0.01%-0.05%.

[0018] The above technical solution results in a metal diaphragm with low warpage, low surface roughness, reduced surface residual stress, no diaphragm curling, and improved fatigue resistance.

[0019] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a distribution diagram of the polished objects.

[0021] Figure 2 This is a strain contour plot after the diaphragm has been polished. Detailed Implementation

[0022] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0023] In this disclosure, unless otherwise stated, directional terms such as "up" and "down" generally refer to the top or bottom of an image.

[0024] This disclosure provides a polishing method for a metal diaphragm of a diaphragm compressor, the polishing method comprising the following steps: S1. The metal diaphragm is installed on top of a polishing base with a lower polishing disc; S2. Apply polishing compound to the surface of the metal diaphragm or the polishing cloth; install the upper polishing disc, which is wrapped with polishing cloth and has a cold water channel, above the metal diaphragm. S3. Press the upper and lower polishing discs together to polish the metal diaphragm; The polishing paste is selected from Al2O3 particles and / or SiO2 particles, and the particle size of the polishing paste is 0.1-20μm, preferably 1-10μm.

[0025] In this disclosure, Al2O3 particles and / or SiO2 particles are used as polishing paste during the polishing process of metal films to better reduce the roughness of the metal films. Al2O3 particles or SiO2 particles can be used alone, or a mixture of Al2O3 and SiO2 particles can be used. The particle size of the polishing paste should be gradually reduced from large to small, according to the surface roughness requirements of the metal film. In one specific embodiment of this disclosure, the polishing paste is evenly applied to the surface of the metal film or the polishing cloth. Preferably, the polishing paste is evenly applied to the surface of the polishing cloth.

[0026] In one specific embodiment of this disclosure, the material of the metal diaphragm can be selected from GH4169, 316L, and 00Cr.15 Ni5, Hastelloy, or a nickel-based alloy, preferably, the metal diaphragm is made of GH4169.

[0027] In one specific embodiment of this disclosure, in step S1, the metal diaphragm and the lower polishing disc can be installed using magnetic or electrostatic adsorption. These two adsorption methods employed in this disclosure can minimize the gap between the polishing disc and the diaphragm, thereby ensuring that no other impurities enter between the metal diaphragm and the lower polishing disc during the polishing process, and thus maximizing the flatness of the metal diaphragm surface.

[0028] In one specific embodiment of this disclosure, the upper and lower polishing discs can be made of GCr15. The GCr15 used in this disclosure has a Vickers hardness of 510-530 HRV. GCr15 steel is a representative high-carbon chromium bearing steel. The most significant advantage of using GCr15 bearing steel is its low temperature sensitivity; it remains essentially undeformed with temperature changes, ensuring that the surface flatness of the upper and lower polishing discs is unaffected by temperature during the polishing process. Furthermore, GCr15 steel has good wear resistance and high hardness, guaranteeing long-term use.

[0029] In one specific embodiment of this disclosure, the size of the upper polishing disk is 0.5-1.5 times that of the lower polishing disk.

[0030] In this disclosure, the size of the upper polishing disc is adjustable, and its size can be 0.5-1.5 times that of the lower polishing disc. The size of the polishing cloth is equal to the circumference of the upper polishing disc, completely covering the upper polishing disc.

[0031] In one specific embodiment of this disclosure, the thickness of the polishing cloth can be 2-6 mm, and the material can be synthetic natural fiber or wear-resistant wool fiber.

[0032] In this disclosure, the polishing cloth can be made of synthetic natural fibers or abrasion-resistant wool fibers; the friction between the fabric fibers of the polishing cloth and the diaphragm can make the polishing surface more lubricated, and the fiber fabric can embed the particles in the polishing paste while preventing the particles from dissipating due to centrifugal force. In addition, some of the moisture absorbed by the polishing cloth ensures the cooling and lubrication of the diaphragm surface, which can ensure that the polishing process can be carried out more smoothly.

[0033] In one specific embodiment of this disclosure, step S3 may further include: opening the cold water channel of the upper polishing disc during the polishing process to rinse the upper polishing disc and the lower polishing disc. In this disclosure, the temperature of the cold water used during the rinsing process is less than 10°C.

[0034] During the polishing process of the metal diaphragm, the cold water channel needs to be kept open to rinse the upper and lower polishing discs. Rinsing can cool down the upper and lower polishing discs. In addition, the polishing cloth used in this disclosure will absorb some water during the rinsing process. The water absorbed by the polishing cloth can cool down the metal diaphragm during the polishing process and keep the temperature of the metal diaphragm below 20°C.

[0035] According to this disclosure, in step S3, the polishing time is 15-60 min, the pressure applied by the upper polishing disc to the metal diaphragm is 20-100 kPa, and the amount of polishing paste used is 5-10 g.

[0036] According to this disclosure, the surface roughness of the polished metal film is less than 0.1 μm, and the warpage is 0.01%-0.05%.

[0037] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0038] Example Example 1 A metal diaphragm made of GH4169 with a surface roughness of 5μm was mounted on a polishing base with a lower polishing disc. 10g of Al2O3 particles with a particle size of 2μm were coated onto a 3mm thick synthetic natural fiber polishing cloth. An upper polishing disc, which wraps the polishing cloth and has cooling water channels, was mounted on top of the GH4169 diaphragm. The upper polishing disc was 1.5 times the size of the lower polishing disc. The upper and lower polishing discs were pressed together, and the GH4169 diaphragm was polished for 45 minutes under a pressure of 50kPa. The temperature of the cold water during the polishing process was 5℃. After polishing, the surface roughness of the GH4169 film is 0.05 μm and the warpage is 0.02%.

[0039] Example 2 A metal diaphragm made of GH4169 with a surface roughness of 4μm was mounted on a polishing base with a lower polishing disc. 10g of SiO2 particles with a particle size of 1μm were coated on the surface of the GH4169 diaphragm. An upper polishing disc wrapped with polishing cloth and equipped with cooling water channels was mounted on top of the GH4169 diaphragm. The upper polishing disc was 1.5 times the size of the lower polishing disc. The upper and lower polishing discs were pressed together and the GH4169 diaphragm was polished for 45 minutes under a pressure of 60Pa. The temperature of the cold water during the polishing process was 5℃. After polishing, the surface roughness of the GH4169 film is 0.04 μm and the warpage is 0.01%.

[0040] Example 3 A metal diaphragm made of GH4169 with a surface roughness of 5μm was mounted on a polishing base with a lower polishing disc. 10g of Al2O3 particles and SiO2 particles with a particle size of 1μm were coated on a polishing cloth made of synthetic natural fiber with a thickness of 5mm. An upper polishing disc wrapped with the polishing cloth and equipped with cooling water channels was mounted on top of the GH4169 diaphragm. The upper polishing disc was 1.5 times the size of the lower polishing disc. The upper and lower polishing discs were pressed together and the GH4169 diaphragm was polished for 60min under a pressure of 100kPa. The temperature of the cold water during the polishing process was 1℃. After polishing, the surface roughness of the GH4169 film was 0.01 μm, and the warpage was 0.01%. Example 4 The polishing method used is the same as in Example 1, except that a 316L metal diaphragm with a surface roughness of 5μm is mounted on a polishing base with a lower polishing disc. 10g of polishing paste with a particle size of 2μm is applied to a 3mm thick synthetic natural fiber cloth. An upper polishing disc, which wraps the polishing cloth and has cooling water channels, is mounted on top of the 316L diaphragm. The upper polishing disc is 0.1 times the size of the lower polishing disc. The upper and lower polishing discs are pressed together, and the 316L diaphragm is polished for 45 minutes under a pressure of 50kPa. The temperature of the cold water during the polishing process is 5°C. The surface roughness of the 316L film after polishing is 0.08 μm and the warpage is 0.1%.

[0041] Example 5 The polishing method used is the same as in Example 1, except that the metal diaphragm, made of Hastelloy with a surface roughness of 5 μm, is mounted on a polishing base with a lower polishing disc. 10 g of polishing paste with a particle size of 2 μm is applied to the polishing cloth, which is made of porous polyurethane foam with a thickness of 3 mm. An upper polishing disc, which wraps the polishing cloth and has cooling water channels, is mounted on top of the Hastelloy. The upper polishing disc is 1.5 times the size of the lower polishing disc. The upper and lower polishing discs are pressed together, and the Hastelloy is polished for 45 minutes under a pressure of 50 kPa. The temperature of the cold water during the polishing process is 5°C. After polishing, the surface roughness of Hastelloy is 3 μm and the warpage is 0.2%.

[0042] Example 6 The polishing method used is the same as in Example 1, except that the metal diaphragm, made of nickel-based alloy with a surface roughness of 5 μm, is mounted on a polishing base with a lower polishing disc. 10 g of polishing paste with a particle size of 2 μm is applied to the polishing cloth, which is made of synthetic natural fiber and is 3 mm thick. An upper polishing disc, which wraps the polishing cloth and has cooling water channels, is mounted on top of the nickel-based alloy. The upper polishing disc is 1.5 times the size of the lower polishing disc. The upper and lower polishing discs are pressed together, and the nickel-based alloy is polished for 45 minutes under a pressure of 50 kPa. The temperature of the cold water during the polishing process is 15°C. The surface roughness of the polished nickel-based alloy is 0.1 μm, and the warpage is 0.2%.

[0043] Example 7 The polishing method used is the same as in Example 1, except that the metal film is made of 00Cr. 15 A Ni5 metal film with a surface roughness of 5μm is mounted on a polishing base with a lower polishing disc. 5g of polishing paste with a particle size of 2μm is applied to a 3mm thick synthetic natural fiber cloth. An upper polishing disc, wrapped with the polishing cloth and equipped with cooling water channels, is then mounted on a 00Cr... 15 Above the Ni5 film, the upper polishing disk is 1.5 times the size of the lower polishing disk; the upper and lower polishing disks are pressed together and polished against 00Cr. 15 The Ni5 film was polished for 5 minutes at a pressure of 1 kPa, with the cold water temperature at 5°C during the polishing process. 00Cr after polishing 15 The surface roughness of the Ni5 film is 5 μm, and the warpage is 0.5%.

[0044] Comparative Example 1 The polishing method used is the same as in Example 1, except that a metal diaphragm made of GH4169 with a surface roughness of 5 μm is mounted on a polishing base with a lower polishing disc. 5 g of Al2O3 particles with a particle size of 30 μm are applied to a polishing cloth made of synthetic natural fiber with a thickness of 3 mm. An upper polishing disc wrapped with the polishing cloth and having a cooling water channel is mounted on top of the diaphragm. The upper polishing disc is 1.5 times the size of the lower polishing disc. The upper and lower polishing discs are pressed together, and the diaphragm is polished for 45 min under a pressure of 50 kPa. The temperature of the cold water during the polishing process is 5 °C. The surface roughness of the polished film is 2 μm, and the warpage is 0.1%.

[0045] Comparative Example 2 The polishing method used is the same as in Example 1, except that the metal diaphragm is made of GH4169 and has a surface roughness of 5μm. It is mounted on a polishing base with a lower polishing disc, and an upper polishing disc wrapped with polishing cloth and having a cooling water channel is mounted on top of the GH4169. The upper polishing disc and the lower polishing disc are pressed together and the GH4169 is polished for 45 minutes under a pressure of 50kPa. The temperature of the cold water during the polishing process is 5℃. After polishing, the surface roughness of GH4169 is 4μm and the warpage is 0.1%.

[0046] Comparative Example 3 A metal diaphragm made of 316L with a surface roughness of 5μm is installed on a polishing base with a lower polishing disc. An upper polishing disc wrapped with polishing cloth and having a cooling water channel is installed on top of the 316L. The upper polishing disc and the lower polishing disc are pressed together and the 316L is polished for 5 minutes under a pressure of 1kPa. The cold water temperature during the polishing process is 20℃. After polishing, the surface roughness of 316L is 5μm and the warpage is 0.1%.

[0047] Test Example 1 The test method for the surface roughness of metal diaphragms is as follows: the surface roughness is tested using a contact probe surface roughness tester, referring to standards ISO 13565 and ISO 12085.

[0048] Test Example 2 The test method for the warpage of metal diaphragms is as follows: using a three-laser plane coarse measuring instrument, referring to GB / T 25257-2010, warpage = H / L × 100%.

[0049] Test Example 3 The surface residual stress was determined using the EBSD backscatter diffraction strain contour plot method, specifically referring to the method in the literature "A Review of Micro-region Stress and Strain Research of Materials Based on Electron Backscatter Diffraction (EBSD) Technology".

[0050] Typical strain contour plots of the treated diaphragm are shown below. Figure 2 As shown: in the strain contour map, the redder the color, the greater the strain; conversely, the bluer the color, the smaller the strain.

[0051] The results are shown in the table below:

[0052] The results show that the surface roughness and surface warpage of Examples 1-3 are much smaller than those of Comparative Examples 1-2, and the surface roughness and surface warpage of Examples 1-3 are smaller than those of Examples 4-7. This indicates that the method of this disclosure can reduce the surface roughness of the metal diaphragm and reduce stress concentration on the diaphragm surface, resulting in less warpage of the metal diaphragm surface after polishing. Furthermore, data from Example 4 demonstrates that a good polishing effect is achieved when the size of the upper polishing disc is 0.5-1.5 times that of the lower polishing disc. Data from Example 5 shows that the synthetic natural fibers or abrasion-resistant wool fibers selected in this disclosure are more beneficial for polishing the metal diaphragm. Data from Examples 6-7 show that cooling the upper polishing disc, lower polishing disc, and metal diaphragm during the polishing process at the cold water temperature specified in this disclosure, and polishing the metal diaphragm within the pressure range described in this disclosure, yields even better results.

[0053] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0054] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0055] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A polishing method for a metal diaphragm sheet of a diaphragm compressor, characterized in that, The polishing method includes the following steps: S1. The metal diaphragm is installed on top of a polishing base with a lower polishing disc; S2. Apply polishing compound evenly to the surface of the metal diaphragm or polishing cloth; An upper polishing disc, wrapped with polishing cloth and equipped with cooling water channels, is mounted above the metal diaphragm. S3. Press the upper polishing disc and the lower polishing disc together and polish the metal diaphragm; The polishing paste is selected from Al2O3 particles and / or SiO2 particles, and the particle size of the polishing paste is 1-10μm; The polishing cloth has a thickness of 2-6mm and is made of wear-resistant wool fiber; Step S3 further includes: during the polishing process, opening the cooling water channel of the upper polishing disc to rinse the upper polishing disc and the lower polishing disc; The temperature of the cooling water is less than 10℃; In step S3, the polishing time is 15-60 min, and the pressure applied by the upper polishing disc to the metal diaphragm is 20-100 kPa. The metal diaphragm is installed to the lower polishing disc by magnetic or electrostatic adsorption. The metal diaphragm is made of GH4169; the upper polishing disc and the lower polishing disc are each made of GCr15. The surface roughness of the polished metal film is less than 0.1 μm, and the warpage is 0.01%-0.05%.

2. The polishing method according to claim 1, wherein, The size of the upper polishing disc is 0.5-1.5 times that of the lower polishing disc.

3. The polishing method according to claim 1, wherein, The amount of polishing paste used is 5-10g.

Images