Method for improving wear resistance of rivet head of automobile hinge riveting machine

Abstract

The present application belongs to the technical field of laser beam processing, and relates to a method for improving the wear resistance of a rivet head of an automobile hinge riveter, which comprises the following steps: preparing a composite coating alloy powder, adding diamond particles as a main reinforcing component to significantly improve the wear resistance of the coating, and obtaining the composite coating alloy powder by ball milling; pre-treating the surface of a rivet head mandrel insert; laser melting deposition to prepare a wear-resistant layer reinforced by diamond particles; and post-treatment of the wear-resistant coating and polishing treatment of the coating surface. The present application applies a high-energy-density laser beam to heat and melt the coating alloy of the working surface of the rivet head mandrel insert of the riveter and rapidly solidifies to form a metallurgical bond with the base body, thereby forming a high-hardness wear-resistant coating on the working surface of the mandrel insert. The coating has higher hardness and wear resistance, can effectively resist friction and impact, maintains excellent performance in a severe working environment, greatly improves the working time of the rivet head of the riveter, prolongs the service life of the rivet head, and reduces the replacement and repair frequency of the rivet head.

Description

Technical Field

[0001] This invention belongs to the field of laser beam processing technology, specifically relating to a method for improving the wear resistance of rivet heads in automotive hinge riveting machines. Background Technology

[0002] As a core component connecting car doors, hoods, and other parts to the vehicle body, automotive hinges directly impact vehicle safety and reliability due to their connection strength and lifespan. Currently, automotive hinges commonly employ a riveting process to achieve precise connections between rivets and metal sheets. This process involves placing the rivet in a predetermined riveting position, rotating the rivet head at high speed and applying pressure, gradually pressing the rivet into the connector. Through rotation and pressure, the rivet head undergoes plastic deformation, forming a strong connection. Compared to welding or bolting, riveting avoids the risk of thermal deformation, reduces assembly stress, and meets the high-precision connection requirements of lightweight automotive manufacturing. However, the riveting process for automotive hinges is characterized by high frequency and high load.

[0003] Taking car door hinges as an example, a single production line needs to complete tens of thousands of riveting operations daily, and the rivet head must withstand instantaneous impact loads as high as 500-800 MPa. Therefore, in practical applications, especially under high-intensity and high-frequency operating environments, rivet heads face serious wear problems. First, under high-frequency use, the rivet head is subjected to high pressure and friction for extended periods, causing rapid surface wear. This wear not only affects riveting quality but also shortens the rivet head's lifespan. Second, due to severe wear, the rivet head's short lifespan necessitates frequent replacement, increasing production costs and production line downtime, thus impacting production efficiency. Worn rivet heads can lead to decreased riveting quality, unsatisfactory rivet fixing effects, and affect product consistency and reliability.

[0004] Rivet heads are typically made of materials such as carbon tool steel, high-speed steel, cemented carbide, and tungsten alloys. Carbon tool steel has poor wear resistance and impact resistance, making it prone to wear or breakage under high-intensity conditions. High-speed steel, including M2 and M35, is expensive and prone to brittle fracture under extreme conditions. Commonly used cemented carbide grades include YG6 and YG8. Traditional rivet head materials, such as ordinary steel or cemented carbide, perform poorly in high-intensity working environments and cannot meet the high wear resistance requirements of modern manufacturing. Tungsten alloys are alloy materials made with tungsten as the base material and the addition of appropriate amounts of cobalt, nickel, and other elements. They possess extremely high hardness, excellent wear resistance, and good toughness, maintaining good stability under high stress conditions. Commonly used tungsten alloys include W90Cu10. However, tungsten alloys are expensive and difficult to process.

[0005] To address this, existing technologies have proposed various methods to improve the wear resistance and service life of rivet heads. For example, high-chromium cast iron, ceramic materials, and superhard materials are used as the base material for rivet heads. While these materials offer high hardness and wear resistance, they also face the risk of high brittleness in practical applications, making them prone to fracture under high stress conditions. Furthermore, their high cost and difficulty in processing hinder large-scale applications. In addition, surface heat treatment or surface coating technologies (such as physical vapor deposition (PVD) and chemical vapor deposition (CVD)) have been proposed to form a hard coating (such as TiN or CrN) on the rivet head surface to improve surface hardness and wear resistance. However, this method suffers from the problem that a single coating is prone to peeling or wear under high-intensity use, affecting wear resistance, and it is difficult to simultaneously meet the requirements of high hardness and high toughness. Research has shown that heat treatment processes such as quenching and tempering can enhance the hardness and toughness of the rivet head base material. However, traditional heat treatment processes suffer from the difficulty of precisely controlling temperature and time, easily leading to unstable rivet head performance. Moreover, heat treatment can easily cause material deformation, affecting the accuracy and service life of the rivet head.

[0006] In summary, while existing technologies have improved rivet head performance to some extent, they still suffer from numerous shortcomings, such as poor coating adhesion, complex processes, high costs, high material brittleness, and processing difficulties. Currently, automobile manufacturing is upgrading towards intelligent and high-speed production, and traditional material improvement methods still face significant bottlenecks in terms of cost, process compatibility, and balanced wear resistance, making it difficult to meet the demands of actual industrial production. Therefore, developing a more efficient and cost-effective method to improve rivet head wear resistance is essential and of great significance for improving the manufacturing quality of automotive hinges and the overall efficiency of production lines. Summary of the Invention

[0007] The purpose of this invention is to provide a method for improving the wear resistance of rivet heads in automotive hinge riveting machines. This method involves applying a high-energy-density laser beam to the working surface of the mandrel insert of the riveting machine head to prepare a high-hardness, high-wear-resistant composite coating based on diamond microparticle reinforcement. This forms a wear-resistant coating on the working surface of the mandrel insert, thereby solving the problem of significantly improving the wear resistance of the rivet head and extending its service life.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for improving the wear resistance of the riveting head of an automotive hinge riveting machine involves using a laser beam to prepare a composite coating based on diamond microparticles and having metallurgical bonding on the working surface of the mandrel insert 2 of the riveting head, comprising the following steps:

[0010] A. Preparation of composite coated alloy powder:

[0011] The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles and tungsten powder. Its composition by mass percentage (Wt / %) is: nickel 24-26, cobalt 32-36, diamond 0.5-1, and tungsten as the balance. First, weigh out the nickel powder, cobalt powder, diamond microparticles and tungsten powder, mix them evenly, and then ball mill for 12 hours to obtain the composite coating alloy powder. Among them, the particle size of the diamond microparticles is no larger than 100 nm.

[0012] B. Surface treatment of the mandrel insert 2 of the rivet head:

[0013] The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove oxide layer and impurities. The end face of the insert is ultrasonically cleaned with acetone solution with a purity of 99% or higher at an ultrasonic frequency of 50kHz for 10 minutes to ensure that the surface is clean.

[0014] C. Laser melting deposition to prepare a wear-resistant layer reinforced with diamond microparticles;

[0015] The composite coating alloy powder obtained in step A is added to the powder feeding bin, and a high-energy-density laser beam is used to melt the composite coating alloy powder to obtain a wear-resistant coating 3 with a thickness of 400-800μm on the end face of the high-speed steel. The laser melting deposition process parameters are: laser power 1.5-3kw, scanning speed 180-240mm / min, powder feeding speed 30-35g / min, and protective gas flow rate 15-18L / min, forming a wear-resistant coating 3 with metallurgical bonding on the working surface of the mandrel insert 2 of the rivet head.

[0016] D. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface, improve the smoothness and performance of the coating, and meet the design requirements.

[0017] Furthermore, in step A, the purity of the tungsten, nickel, and cobalt used is greater than 99.9%, and the particle size of the powder is 75-80 μm.

[0018] Further, in step A, the composite coating alloy composition by mass percentage (Wt / %) is: nickel 26, cobalt 32, diamond 0.5, and tungsten as the balance.

[0019] Further, in step A, the composite coating alloy composition by mass percentage (Wt / %) is: nickel 26, cobalt 33, diamond 0.8, and tungsten as the balance.

[0020] Further, in step A, the composite coating alloy composition by mass percentage (Wt / %) is: nickel 25, cobalt 34, diamond 1, and tungsten as the balance.

[0021] Further, in step A, the composite coating alloy composition by mass percentage (Wt / %) is: nickel 25, cobalt 35, diamond 0.5, and tungsten as the balance.

[0022] Further, in step A, the composite coating alloy composition by mass percentage (Wt / %) is: nickel 24, cobalt 36, diamond 0.8, and tungsten as the balance.

[0023] Further, in step A, the composite coating alloy composition by mass percentage (Wt / %) is: nickel 24, cobalt 36, diamond 1, and tungsten as the balance.

[0024] Further, in step A, the ball milling process is as follows: select three types of zirconia grinding balls with diameters of 12 mm, 6 mm and 1 mm respectively, with a weight ratio of 1:1:1 and a ball-to-material ratio of 4:1. Put the powder and balls into the ball milling jar, fill it with argon gas for protection and ball milling. The ball milling speed is 250 r / min. After each ball milling for 10 minutes, stop for 10 minutes to dissipate heat. The ball milling is carried out for 12 hours.

[0025] Further, in step C, the energy density of the laser beam is in the range of 1-10 kW / cm².

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This invention applies a high-energy-density laser beam to heat and melt the coating alloy on the working surface of the mandrel insert of an automotive hinge riveting machine, allowing it to rapidly solidify and form a metallurgical bond with the substrate. This results in a high-hardness, wear-resistant coating on the working surface of the mandrel insert. In existing technologies, the coating hardness is 58-62 HR. Compared to traditional materials, the coating of this invention exhibits higher hardness and wear resistance, effectively resisting friction and impact, and maintaining excellent performance in harsh working environments. Existing technologies typically experience severe wear after approximately 15,000 riveting cycles. This invention significantly increases the working time of the riveting machine head, extends its service life, and reduces the frequency of replacement and maintenance. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the riveting process.

[0030] Figure 2 A schematic diagram of the wear-resistant coating structure prepared by laser melting deposition in this invention;

[0031] Figure 3 This is a scan image of the wear surface of a riveting machine head without wear-resistant coating after 15,000 riveting cycles;

[0032] Figure 4 This is a scan image of the wear-resistant coating prepared by laser melting deposition after 15,000 riveting cycles by a riveting machine head.

[0033] In the diagram, 1. mandrel; 2. mandrel insert; 3. wear-resistant coating; 4. rivet; 5. workpiece. Detailed Implementation

[0034] The present invention will be further described below with reference to embodiments:

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0036] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Figure 1 This is the basic principle of the riveting process. During the riveting process, the mandrel 1 applies axial pressure while rotating, and the tail of the rivet 4 is plastically deformed by the mandrel insert 2, tightly fitting into the workpiece 5, thereby achieving a stable connection of the workpiece 5.

[0038] like Figures 1-2 As shown, the mandrel 1 is the main body of the entire riveting machine head, transmitting rotational motion and pressure. The mandrel insert 2 is located at the bottom of the mandrel 1 and is in direct contact with the rivet 4, used to guide the plastic deformation of the tail of the rivet 4. A wear-resistant coating 3 is prepared on the surface of the mandrel insert 2 by laser melting deposition. The wear-resistant coating 3 has a thickness of 400-800μm, which is used to enhance wear resistance, significantly improve the working time of the riveting machine head, extend the service life of the riveting head, and reduce the frequency of rivet head replacement and maintenance.

[0039] This invention provides a method for improving the wear resistance of riveting machine heads. A high-energy-density laser beam is applied to the working surface of the mandrel insert 2 of the riveting machine head to melt a specific composite coating material, thereby preparing a high-hardness, high-wear-resistant composite alloy material based on diamond microparticle reinforcement. A wear-resistant coating 3 with metallurgical bonding is formed on the working surface of the mandrel insert 2, which significantly improves the wear resistance of the riveting head and extends its service life.

[0040] The present invention provides a method for improving the wear resistance of rivet heads in automotive hinge riveting machines, comprising the following steps:

[0041] The first step is to prepare the composite coating alloy powder. The composite coating alloy powder of the present invention is composed of nickel powder, cobalt powder, diamond microparticles and tungsten powder to enhance the overall strength and wear resistance of the coating. Its composition by mass percentage (Wt / %) is: nickel (Ni): 24-26, cobalt (Co): 32-36, diamond 0.5-1, tungsten (W): balance.

[0042] The tungsten, nickel, and cobalt used in this invention all have a purity greater than 99.9%, and the powder particle size is 75-80 μm. This invention incorporates a certain amount of diamond microparticles as the main reinforcing component. Diamond possesses extremely high hardness and wear resistance, which can significantly improve the wear resistance of the coating. This ensures rigidity and wear resistance during the riveting process, thereby preventing rapid wear and failure of the rivet head end face. The diamond microparticles have a particle size no greater than 100 nm.

[0043] This invention uses ball milling to mix powders to obtain a uniformly composed basic alloy powder. Specifically, the above four powders are accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm are selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls are placed in a ball milling jar, and ball milling is carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling, the mixture is stopped for 10 minutes to dissipate heat. The ball milling is carried out for 12 hours to obtain the composite coated alloy powder.

[0044] The second step is pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0045] The third step is laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. Specifically, a high-energy-density laser beam device is used, with the laser beam energy density typically in the range of 1-10 kW / cm², which can effectively melt and deposit the composite coating material. The composite coating alloy powder is added to the powder feeding chamber, and the composite coating alloy powder is melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 400-800 μm on the high-speed steel end face. The optimized laser melting deposition process parameters are: laser power 1.5-3 kW, scanning speed 180-240 mm / min, powder feeding speed 30-35 g / min, and protective gas flow rate 15-18 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0046] The fourth step is the post-treatment of the wear-resistant coating 3. A 5000-grit polishing wheel is used to polish the surface of the wear-resistant coating 3 for 5 minutes at a speed of 1500 rpm to remove any possible defects or uneven areas on the surface, improve the smoothness and performance of the coating, and meet the design requirements.

[0047] Example 1:

[0048] A method for improving the wear resistance of rivet heads in automotive hinge riveting machines includes the following steps:

[0049] 1. Preparation of composite coating alloy powder. The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles, and tungsten powder, with the following composition by mass percentage (Wt / %): Nickel (Ni): 26, Cobalt (Co): 32, Diamond 0.5, Tungsten (W): Balance. The purity of the tungsten, nickel, and cobalt used is greater than 99.9%, the particle size of the powder is 75-80 μm, and the particle size of the diamond microparticles is no greater than 100 nm.

[0050] The four powders were accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm were selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls were placed in a ball milling jar, and ball milling was carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling session, the mixture was stopped for 10 minutes to allow for heat dissipation. The composite coated alloy powder was obtained after 12 hours of ball milling.

[0051] 2. Pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0052] 3. Laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. A high-energy-density laser beam device was used, with an energy density of 1 kW / cm². Composite coating alloy powder was added to the powder feeding chamber, and the composite coating alloy powder was melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 400 μm on the end face of the high-speed steel. The optimized laser melting deposition process parameters were: laser power 1.5 kW, scanning speed 180 mm / min, powder feeding speed 30 g / min, and protective gas flow rate 15 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0053] 4. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface and improve the smoothness and performance of the coating.

[0054] Example 2:

[0055] A method for improving the wear resistance of rivet heads in automotive hinge riveting machines includes the following steps:

[0056] 1. Preparation of composite coating alloy powder. The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles, and tungsten powder, with the following composition by mass percentage (Wt / %): Nickel (Ni): 26, Cobalt (Co): 33, Diamond 0.8, Tungsten (W): Balance. The purity of the tungsten, nickel, and cobalt used is greater than 99.9%, the particle size of the powder is 75-80 μm, and the particle size of the diamond microparticles is no greater than 100 nm.

[0057] The four powders were accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm were selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls were placed in a ball milling jar, and ball milling was carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling session, the mixture was stopped for 10 minutes to allow for heat dissipation. The composite coated alloy powder was obtained after 12 hours of ball milling.

[0058] 2. Pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0059] 3. Laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. A high-energy-density laser beam device was used, with an energy density of 2 kW / cm². Composite coating alloy powder was added to the powder feeding chamber, and the composite coating alloy powder was melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 500 μm on the high-speed steel end face. The optimized laser melting deposition process parameters were: laser power 1.8 kW, scanning speed 200 mm / min, powder feeding speed 31 g / min, and protective gas flow rate 15 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0060] 4. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface and improve the smoothness and performance of the coating.

[0061] Example 3:

[0062] A method for improving the wear resistance of rivet heads in automotive hinge riveting machines includes the following steps:

[0063] 1. Preparation of composite coating alloy powder. The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles, and tungsten powder, with the following composition by mass percentage (Wt / %): Nickel (Ni): 25, Cobalt (Co): 34, Diamond 1, Tungsten (W): Balance. The purity of the tungsten, nickel, and cobalt used is greater than 99.9%, the particle size of the powder is 75-80 μm, and the particle size of the diamond microparticles is no greater than 100 nm.

[0064] The four powders were accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm were selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls were placed in a ball milling jar, and ball milling was carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling session, the mixture was stopped for 10 minutes to allow for heat dissipation. The composite coated alloy powder was obtained after 12 hours of ball milling.

[0065] 2. Pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0066] 3. Laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. A high-energy-density laser beam device was used, with an energy density of 5 kW / cm². Composite coating alloy powder was added to the powder feeding chamber, and the composite coating alloy powder was melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 600 μm on the end face of the high-speed steel. The optimized laser melting deposition process parameters were: laser power 2 kW, scanning speed 200 mm / min, powder feeding speed 32 g / min, and protective gas flow rate 16 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0067] 4. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface and improve the smoothness and performance of the coating.

[0068] Example 4:

[0069] A method for improving the wear resistance of rivet heads in automotive hinge riveting machines includes the following steps:

[0070] 1. Preparation of composite coating alloy powder. The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles, and tungsten powder, with the following composition by mass percentage (Wt / %): Nickel (Ni): 25, Cobalt (Co): 35, Diamond 0.5, Tungsten (W): Balance. The purity of the tungsten, nickel, and cobalt used is greater than 99.9%, the particle size of the powder is 75-80 μm, and the particle size of the diamond microparticles is no greater than 100 nm.

[0071] The four powders were accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm were selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls were placed in a ball milling jar, and ball milling was carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling session, the mixture was stopped for 10 minutes to allow for heat dissipation. The composite coated alloy powder was obtained after 12 hours of ball milling.

[0072] 2. Pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0073] 3. Laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. A high-energy-density laser beam device was used, with the laser beam energy density in the range of 6 kW / cm². Composite coating alloy powder was added to the powder feeding chamber, and the composite coating alloy powder was melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 600 μm on the end face of the high-speed steel. The optimized laser melting deposition process parameters were: laser power 2.4 kW, scanning speed 220 mm / min, powder feeding speed 33 g / min, and protective gas flow rate 17 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0074] 4. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface and improve the smoothness and performance of the coating.

[0075] Example 5:

[0076] A method for improving the wear resistance of rivet heads in automotive hinge riveting machines includes the following steps:

[0077] 1. Preparation of composite coating alloy powder. The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles, and tungsten powder, with the following composition by mass percentage (Wt / %): Nickel (Ni): 24, Cobalt (Co): 36, Diamond 0.8, Tungsten (W): Balance. The purity of the tungsten, nickel, and cobalt used is greater than 99.9%, the particle size of the powder is 75-80 μm, and the particle size of the diamond microparticles is no greater than 100 nm.

[0078] The four powders were accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm were selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls were placed in a ball milling jar, and ball milling was carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling session, the mixture was stopped for 10 minutes to allow for heat dissipation. The composite coated alloy powder was obtained after 12 hours of ball milling.

[0079] 2. Pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0080] 3. Laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. A high-energy-density laser beam device was used, with an energy density of 8 kW / cm². Composite coating alloy powder was added to the powder feeding chamber, and the composite coating alloy powder was melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 700 μm on the high-speed steel end face. The optimized laser melting deposition process parameters were: laser power 2.8 kW, scanning speed 220 mm / min, powder feeding speed 34 g / min, and protective gas flow rate 17 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0081] 4. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface and improve the smoothness and performance of the coating.

[0082] Example 6:

[0083] A method for improving the wear resistance of rivet heads in automotive hinge riveting machines includes the following steps:

[0084] 1. Preparation of composite coating alloy powder. The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond microparticles, and tungsten powder, with the following composition by mass percentage (Wt / %): Nickel (Ni): 24, Cobalt (Co): 36, Diamond 1, Tungsten (W): Balance. The purity of the tungsten, nickel, and cobalt used is greater than 99.9%, the particle size of the powder is 75-80 μm, and the particle size of the diamond microparticles is no greater than 100 nm.

[0085] The four powders were accurately weighed by mass percentage using an electronic balance with an accuracy of 0.0001g. Three types of zirconia grinding balls with diameters of 12mm, 6mm, and 1mm were selected with a weight ratio of 1:1:1 and a ball-to-powder ratio of 4:1. The powder and balls were placed in a ball milling jar, and ball milling was carried out under argon protection at a speed of 250 r / min. After each 10-minute ball milling session, the mixture was stopped for 10 minutes to allow for heat dissipation. The composite coated alloy powder was obtained after 12 hours of ball milling.

[0086] 2. Pretreatment. The mandrel insert 2 of the rivet head is cleaned and surface-treated to remove the oxide layer and impurities. The end face of the insert is ultrasonically cleaned with an acetone solution of 99% or higher purity at a frequency of 50kHz for 10 minutes to ensure a clean surface.

[0087] 3. Laser melting deposition to prepare a diamond microparticle-reinforced wear-resistant layer. A high-energy-density laser beam device was used, with an energy density of 10 kW / cm². Composite coating alloy powder was added to the powder feeding chamber, and the composite coating alloy powder was melted by the laser beam to obtain a wear-resistant coating 3 with a thickness of 800 μm on the end face of the high-speed steel. The optimized laser melting deposition process parameters were: laser power 3 kW, scanning speed 240 mm / min, powder feeding speed 35 g / min, and protective gas flow rate 18 L / min, forming a metallurgically bonded wear-resistant coating 3 on the working surface of the mandrel insert 2 of the rivet head.

[0088] 4. Post-treatment of wear-resistant coating 3: Use a 5000-grit polishing wheel at a speed of 1500 rpm to polish the surface of wear-resistant coating 3 for 5 minutes to remove any possible defects or uneven areas on the surface and improve the smoothness and performance of the coating.

[0089] The technical indicators achieved by the composite coating alloy wear-resistant layer of the riveting machine heads prepared using the coating alloy composition, process steps and parameters of Examples 1-6 are shown in Table 1.

[0090] Table 1

[0091]

[0092] As can be seen from Table 1, the hardness of the composite coating alloy wear-resistant layer of the present invention is 75-85 HRC; the wear resistance of the composite coating alloy is 1.6-1.8 times that of the uncoated substrate.

[0093] Depend on Figure 3 and Figure 4 It can be seen that the riveting head without the wear-resistant coating 3 suffered severe wear after 15,000 riveting cycles and could no longer be used for riveting. The riveting head prepared according to the above-described process steps and composition of this invention, after 15,000 consecutive riveting cycles, still had a smooth surface on the mandrel insert 2 and could continue riveting. Ultimately, it was tested to withstand 27,000-30,000 consecutive riveting cycles before suffering severe wear, representing 1.8-2 times the number of riveting cycles required for the riveting head without the wear-resistant coating 3.

[0094] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method of improving the wear resistance of a rivet head of an automotive hinge swage machine, characterized by, A laser beam is used to prepare a diamond particle-reinforced composite coating with metallurgical bonding on the working surface of a mandrel insert (2) of a riveting head of a riveting machine, including the following steps: A, preparing a composite coating alloy powder: The composite coating alloy powder is composed of nickel powder, cobalt powder, diamond particles and tungsten powder, and the components are Wt / %: nickel 24-26, cobalt 32-36, diamond 0.5-1, and tungsten as the balance; first, the nickel powder, cobalt powder, diamond particles and tungsten powder are mixed uniformly, and then ball milling is performed for 12 hours to obtain the composite coating alloy powder; wherein the particle size of the diamond particles is not greater than 100 nm; the purity of the tungsten, nickel and cobalt used is greater than 99.9%, and the particle size of the powder is 75-80 μm; the ball milling process is as follows: three kinds of zirconia milling beads with diameters of 12 mm, 6 mm and 1 mm are selected, the weight ratio is 1:1:1, the ball-to-material ratio is 4:1, the powder and the balls are placed in a ball milling tank, argon gas is filled for protection, and ball milling is performed at a speed of 250 r / min, 10 min per ball milling, and 10 min of heat dissipation per ball milling, for a total of 12 h; B, treatment of the surface of the mandrel insert (2) of the riveting head: The mandrel insert (2) of the riveting head is cleaned and surface treated to remove the oxide layer and impurities, the insert end face is ultrasonically cleaned with an acetone solution with a purity of more than 99%, the ultrasonic frequency is 50 kHz, and the cleaning time is 10 minutes, to ensure that the surface is clean; C, laser melting deposition, preparation of diamond particle-reinforced wear-resistant layer; The composite coating alloy powder obtained in step A is added to the powder feeding bin, a high-energy density laser beam is used to melt the composite coating alloy powder, and a wear-resistant coating (3) with a thickness of 400-800 μm is obtained on the high-speed steel end face; wherein the laser melting deposition process parameters are: laser power 1.5-3 kW, scanning speed 180-240 mm / min, powder feeding speed 30-35 g / min, and protective gas flow 15-18 L / min, to form a wear-resistant coating (3) with metallurgical bonding on the working surface of the mandrel insert (2) of the riveting head; the energy density of the laser beam is in the range of 1-10 kW / cm²; D, post-treatment of the wear-resistant coating (3), the surface of the wear-resistant coating (3) is polished for 5 minutes at a speed of 1500 revolutions per minute using a 5000-mesh polishing wheel, to remove surface defects and improve the smoothness and performance of the coating, meeting the design requirements.

2. The method for improving the wear resistance of the rivet head of the automobile hinge riveting machine according to claim 1, characterized in that: In step A, the composite coating alloy components are Wt / %: nickel 26, cobalt 32, diamond 0.5, and tungsten as the balance.

3. The method for improving the wear resistance of the rivet head of the automobile hinge riveting machine according to claim 1, characterized in that: In step A, the composite coating alloy components are Wt / %: nickel 26, cobalt 33, diamond 0.8, and tungsten as the balance.

4. The method for improving the wear resistance of the rivet head of the automobile hinge riveting machine according to claim 1, characterized in that: In step A, the composite coating alloy components are Wt / %: nickel 25, cobalt 34, diamond 1, and tungsten as the balance.

5. The method of improving the wear resistance of the rivet head of the automobile hinge riveter according to claim 1, characterized in that: In step A, the composite coating alloy components are Wt / %: nickel 25, cobalt 35, diamond 0.5, and tungsten as the balance.

6. The method of improving the wear resistance of the rivet head of the automobile hinge riveter according to claim 1, characterized in that: In step A, the composite coating alloy components are Wt / %: nickel 24, cobalt 36, diamond 0.8, and tungsten as the balance.

7. The method of improving the wear resistance of the rivet head of the automobile hinge riveter according to claim 1, characterized in that: Step A, the composite coating alloy composition by weight percent Wt / %: nickel is 24, cobalt is 36, diamond is 1, tungsten is the balance.

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