A production process of an automobile transmission shaft

Abstract

The application relates to the field of automobile accessory processing, in particular to a production process of an automobile transmission shaft. The automobile transmission shaft is prepared by the following method: 1) raw materials are pretreated to obtain a bar material; 2) the bar material is preheated to 200-250 DEG C, graphite lubricating film forming agent is sprayed, and then the bar material is heated to 850 DEG C plus or minus 20 DEG C, so that a lubricating layer is formed on the surface of the bar material, and a processing material is obtained; 3) the processing material is subjected to forming processing, and after the transmission shaft structure is formed, surface treatment is carried out, so that the automobile transmission shaft is obtained; the graphite lubricating film forming agent is composed of graphite and a synergistic dispersing solution in a weight ratio of 1: (4.5-5.5); the synergistic dispersing solution comprises 30-50 g / L graphene-rare earth metal oxide composite powder, 50-80 g / L active modified silicon oil and 3-8 g / L active modified cellulose, and water is added to constant volume.

Description

Technical Field

[0001] This application relates to the field of automotive parts processing, and more specifically, it relates to a manufacturing process for automotive drive shafts. Background Technology

[0002] As a key load-bearing component of the automotive transmission system, the automotive driveshaft plays a crucial role in transmitting power and compensating for axial and radial displacements. Its structural integrity, dimensional accuracy, and surface quality directly determine the vehicle's transmission efficiency, driving stability, and service life. With the continuous development of the automotive industry, higher demands are being placed on the quality and production efficiency of automotive driveshafts. Currently, the production of automotive driveshafts has reached a certain technological foundation, but there are still areas for improvement. In the field of automotive parts processing, the production technology of automotive driveshafts has been continuously explored and improved to meet the growing needs of the automotive industry. Currently, the production of automotive driveshafts mostly adopts hot forging forming technology. The conventional process flow is usually as follows: raw materials are pre-treated by cutting, rust removal, and grinding to obtain qualified bar stock. The bar stock is then heated to the forging temperature. To reduce the frictional resistance between the billet and the die, improve the plastic flow properties of the metal, and facilitate subsequent forming processing and post-forging demolding, a lubricant needs to be sprayed onto the surface of the bar stock before forging. The most widely used lubricant in the industry is graphite emulsion. These graphite emulsion lubricants typically use graphite as the core lubricating component, simply compounded with water, or with only a small amount of common film-forming aids. Their core function is to form a lubricating film on the surface of the billet, isolating the billet from direct contact with the die, reducing frictional losses during forging, and facilitating smooth metal forming. However, traditional graphite emulsion lubricants and corresponding forging processes suffer from numerous intractable technical defects. During spraying, the graphite particles are prone to agglomeration and have poor dispersibility, resulting in poor film uniformity on the billet surface, often leading to uneven film thickness, missing film, and coating agglomeration. Furthermore, under the long-term high-temperature forging environment of automotive drive shafts, the lubricating film formed by traditional graphite emulsions has insufficient heat resistance and weak adhesion to the billet surface, making it prone to softening, ablation, and peeling, leading to lubrication failure. The shedding of the lubricating film layer can cause serious surface defects on the workpiece surface, such as scratches, folds, and cracks. It can also lead to uneven metal flow, resulting in poor dimensional accuracy and out-of-tolerance form and position of forgings, significantly reducing the final product quality of automotive drive shafts and even causing workpiece scrap. In addition, to compensate for the above defects, traditional processes often require increasing the coating amount of graphite emulsion, which not only increases the cost of raw materials but also easily leads to secondary problems such as peeling and flaking due to excessive coating thickness, further affecting production stability. Summary of the Invention

[0003] The purpose of this application is to overcome the above-mentioned technical problems and provide a manufacturing process for automotive drive shafts.

[0004] A manufacturing process for an automotive driveshaft, comprising the following steps: 1) Pre-process the raw materials to obtain bar stock; 2) Preheat the bar stock to 200-250℃, spray with graphite lubricating film-forming agent, and then heat to 850℃±20℃ to form a lubricating layer on the surface of the bar stock to obtain the processed material; 3) The material is processed into a drive shaft structure, and then surface treated to obtain the automotive drive shaft; The graphite lubricating film-forming agent is composed of graphite and a synergistic dispersion in a weight ratio of 1:(4.5-5.5); The synergistic dispersion comprises: 30-50 g / L graphene-rare earth metal oxide composite powder, 50-80 g / L active modified silicone oil, 3-8 g / L active modified cellulose, and water to a fixed volume.

[0005] By adopting the above technical solution, the raw materials are first pretreated to obtain rods. The rods are then preheated to 200-250℃ and coated with a graphite lubricating film-forming agent. They are then heated to 850℃±20℃ to form a stable lubricating layer on the rod surface. Finally, the drive shaft is produced through molding and surface treatment. The 200-250℃ preheating ensures the rod surface reaches a suitable spraying temperature, preventing poor spreading and uneven film formation due to excessively low temperatures, and preventing premature decomposition, localized coking, or film defects due to excessively high temperatures. It also removes residual moisture and slight oil contamination from the rod surface, improving the interface quality between the lubricating layer and the substrate. Further heating the coated rods to 850℃±20℃ allows for rapid evaporation of moisture in the lubricating film-forming agent and moderate curing and cross-linking of organic components, promoting rapid and dense film formation. This temperature is close to the subsequent molding temperature range, allowing the lubricating layer to form a structurally stable and strongly adhesive continuous film at high temperatures, ensuring continuous lubrication throughout the molding process.

[0006] In graphite lubricant film-forming agents, graphite, as the main lubricating component, provides excellent high-temperature friction reduction and anti-galling properties, reducing the friction coefficient between the blank and the mold during molding, and minimizing metal adhesion and scratches. The graphene-rare earth metal oxide composite powder in the synergistic dispersion features a regular layered structure, excellent high-temperature stability, and strong interfacial bonding activity. It can utilize the high load-bearing and high friction-reducing properties of graphene to enhance lubrication load-bearing capacity, and leverage the high-temperature stability and interfacial modification effects of rare earth metal oxides to strengthen the bonding strength between the lubricating layer and the metal matrix, significantly improving the high-temperature wear resistance and anti-detachment performance of the lubricating layer. This composite powder and graphite form a highly efficient synergistic effect. Graphite provides basic high-temperature lubrication and friction reduction, while the composite powder further forms a high-strength, highly dense, and highly adhesive composite lubricating structure on the graphite lubrication framework. This compensates for the shortcomings of single graphite lubricating layers, such as easy detachment at high temperatures, insufficient load-bearing capacity, and limited wear resistance, ensuring that the lubricating layer maintains a complete and continuous lubrication effect even under the harsh conditions of high-temperature forging.

[0007] The active modified silicone oil consists of water-based modified hydroxypropyl silicone oil and hydrophilic double-ended epoxy polyether silicone oil. The two work synergistically to improve the overall wettability, leveling properties, and high-temperature film-forming performance of the film-forming agent. The water-based modified hydroxypropyl silicone oil promotes rapid spreading and uniform wetting of the graphite lubricating film-forming agent on the surface of the preheated rod, improving the flexibility and crack resistance of the coating after film formation. The hydrophilic double-ended epoxy polyether silicone oil stabilizes the system dispersion and moderately cross-links and cures during subsequent heating, enhancing the interfacial bonding between the lubricating layer and the metal substrate, and improving the high-temperature shear resistance and anti-detachment properties of the lubricating layer. The active modified cellulose consists of sulfonated modified cellulose nanocrystals and / or TEMPO oxidized nanocellulose. Its surface is rich in active groups, which can improve the dispersion uniformity of graphene-rare earth metal oxide composite powder and graphite in the aqueous system, inhibit powder agglomeration and sedimentation, and ensure long-term storage stability and non-stratification of the film-forming agent. Its nanoscale rod-like structure can also form a network support framework in the lubricating layer, improving the toughness, density, and structural stability of the lubricating layer.

[0008] The above three components achieve significant synergistic effects. The active modified cellulose and active modified silicone oil together construct a stable dispersion system, ensuring uniform dispersion of the graphene-rare earth metal oxide composite powder in the dispersion liquid and long-term system stability. This effectively promotes uniform dispersion of graphite particles and prevents agglomeration. The graphene-rare earth metal oxide composite powder, in turn, enhances the high-temperature stability and interfacial bonding of the lubricating layer. Under the promoting effects of the active modified silicone oil and active modified cellulose, the formed lubricating layer has a smooth surface, uniform film thickness, strong adhesion, and excellent high-temperature shear resistance. This significantly reduces problems such as lubricating layer detachment and localized film defects during high-temperature forging, effectively avoiding defects such as surface scratches, folds, cracks, poor dimensional accuracy, and out-of-form tolerances on the workpiece. This further improves the forming quality, dimensional accuracy, surface quality, comprehensive mechanical properties, and production qualification rate of the drive shaft, while reducing production costs, making it more suitable for large-scale precision forming production of automotive drive shafts.

[0009] Preferably, the forming process in step 3) includes: extruding the rod part, upsetting the big end, forging to the size and shape specified in the drawing, and cooling to obtain a semi-finished product.

[0010] By adopting the above technical solution, the metal flows more smoothly along the mold cavity and the deformation resistance is reduced during multiple plastic deformation processes such as extrusion of the rod and upsetting of the head, effectively reducing forming load and mold wear. Simultaneously, the lubricating layer is less prone to damage, peeling, or missing film during continuous high-temperature forging, avoiding defects such as adhesion, tearing, folding, and cracking caused by direct contact between the billet and the mold. This results in more uniform extrusion forming of the drive shaft rod and fuller, more regular upsetting of the head. The shape and dimensions of the forging are more easily and precisely controlled to meet drawing requirements, significantly improving the dimensional accuracy, form and position accuracy, and surface finish of the semi-finished product, and reducing subsequent machining allowances and scrap rates. Following cooling and subsequent surface treatment, the final automotive drive shaft exhibits high dimensional consistency, good surface quality, and stable comprehensive mechanical properties, further improving product qualification rate and production efficiency, making it more suitable for precision, efficient, and large-scale forming production of automotive drive shafts.

[0011] Preferably, the surface treatment in step 3) includes: sequentially performing shot blasting, flaw detection, forging inspection, machining, milling of ball bearings, cleaning and rust prevention, packaging, and testing on the semi-finished product to obtain the automotive drive shaft.

[0012] By adopting the above technical solution, the raw materials are first inspected, stored, cut, chamfered, and shot blasted to obtain bar stock. The bar stock is preheated to 200-250℃, and a graphite lubricating film-forming agent composed of graphite and synergistic dispersion in a weight ratio of 1:(4.5-5.5) is sprayed on. Then, it is heated to 850℃±20℃ to form a lubricating layer to obtain processed material. The processed material is then extruded into rods, upsetting the big end, forged into the dimensions and shape specified in the drawings, and cooled to obtain semi-finished products. Finally, the semi-finished products are sequentially shot blasted, flawed, forged, and inspected, machined, milled into ball bearings, cleaned and rust-proofed, packaged, and inspected to obtain the automotive drive shaft. Shot blasting can remove a small amount of oxide scale to obtain a uniform and dense surface strengthening layer, improving the fatigue strength of the drive shaft surface; the final inspection results of flaw detection and forging inspection are more stable and reliable, reducing the rate of missed inspection of defective products and improving the safety and reliability of finished products; it reduces the difficulty of cutting processes in turning and milling ball bearing processes, reduces machining allowance and tool wear, and improves machining consistency and finished product qualification rate; the final automotive drive shaft has guaranteed surface quality, dimensional accuracy, mechanical properties and rust prevention performance, and the product has stable comprehensive performance, long service life, and meets the requirements of high precision and high reliability.

[0013] Preferably, the pretreatment in step 1) includes: raw material inspection, warehousing, cutting, chamfering, shot blasting, and obtaining bar stock.

[0014] By adopting the above technical solutions, raw material inspection and warehousing can control the material, specifications, and mechanical properties of raw materials from the source, eliminating unqualified raw materials and providing a basic guarantee for the stable performance of subsequent molding and processing and drive shaft finished products. Blanking and chamfering can remove burrs and sharp edges from the ends of the bar stock, avoiding stress concentration, local damage to the lubricating layer, or molding cracks caused by sharp edges of the bar stock ends during subsequent preheating, spraying, and molding processes. At the same time, it facilitates the transfer and positioning of the bar stock between processes, improving process stability. Shot blasting can effectively remove oxide scale, rust, and impurities from the surface of the bar stock, making the surface of the bar stock clean and moderately rough. This significantly improves the wetting, spreading, and adhesion of the subsequent graphite lubricating film-forming agent on the surface of the bar stock, providing good interface conditions for uniform film formation and firm adhesion of the lubricating layer, further reducing problems such as lubricating layer peeling and film defects, thus laying a high-quality billet foundation for subsequent forming processes such as extrusion, upsetting, and forging.

[0015] Preferably, the chemical composition of the raw material is: 0.50-0.58% C, 0.15-0.30% Si, 0.65-0.85% Mn, Cr-M-MO composite ≤0.45%, 0.015-0.042% Al, Cu ≤0.25%, Sn ≤0.030%, Sb ≤0.01%, Ti ≤0.03%, P ≤0.025%, with the balance being Fe and other unavoidable impurities.

[0016] By adopting the above technical solutions, the material, specifications, and mechanical properties of raw materials are controlled from the source, and unqualified raw materials are eliminated, providing a basic guarantee for the stable performance of subsequent molding and processing and drive shaft finished products. The blanking and chamfering treatment can avoid the sharp edges of the bar stock from causing stress concentration, local damage to the lubricating layer, or molding cracks during subsequent preheating, spraying, and molding processes. At the same time, it facilitates the transfer and positioning of the bar stock between processes, improving process stability. Shot blasting treatment can make the surface of the bar stock clean and moderately rough, significantly improving the wetting, spreading, and adhesion of the subsequent graphite lubricating film-forming agent on the surface of the bar stock, providing good interface conditions for the uniform film formation and firm adhesion of the lubricating layer, further reducing problems such as lubricating layer peeling and film defects, thus laying a high-quality blank foundation for subsequent extrusion, upsetting, forging and other molding processes.

[0017] Chemical composition of raw materials: 0.50-0.58% C, 0.15-0.30% Si, 0.65-0.85% Mn, Cr-M-MO complex ≤0.45%, 0.015-0.042% Al, Cu ≤0.25%, Sn ≤0.030%, Sb ≤0.01%, Ti ≤0.03%, P ≤0.025%, balance being Fe and other unavoidable impurities.

[0018] By adopting the above technical solutions, the material, specifications, and mechanical properties of raw materials are controlled from the source, and unqualified raw materials are eliminated, providing a basic guarantee for the stable performance of subsequent molding and processing and the finished drive shaft. The blanking and chamfering process can remove burrs and sharp edges from the ends of the bar stock, avoiding stress concentration, local damage to the lubricating layer, or molding cracks caused by sharp edges of the bar stock ends during subsequent preheating, spraying, and molding processes. At the same time, it facilitates the transfer and positioning of the bar stock between processes, improving process stability. Shot blasting can effectively remove oxide scale, rust, and impurities from the surface of the bar stock, making the surface of the bar stock clean and moderately rough. This significantly improves the wetting, spreading, and adhesion of the graphite lubricating film-forming agent on the surface of the bar stock, providing good interface conditions for the uniform film formation and firm adhesion of the lubricating layer, further reducing problems such as lubricating layer peeling and film defects, thus laying a high-quality blank foundation for subsequent forming processes such as extrusion, upsetting, and forging.

[0019] Preferably, the effective coating amount of the graphite lubricating film-forming agent is 20-50 g / m².

[0020] By adopting the above technical solution, within a coating amount range of 20-50 g / m², it is possible to ensure that the lubricating layer forms a continuous, complete, and moderately thick lubricating film on the surface of the rod, meeting the lubrication requirements of subsequent heating at 850℃±20℃ and high-temperature molding processes. This also avoids problems such as excessively thick lubricating layers, uneven drying, localized accumulation, and easy film peeling caused by excessive coating amount, while reducing raw material waste and costs. Thanks to the efficient synergistic effect between graphene-rare earth metal oxide composite powder, active modified silicone oil, active modified cellulose, and graphite, excellent lubrication and film formation effects can be achieved at this lower coating amount, resulting in higher lubrication efficiency per unit area, stronger high-temperature adhesion, and more prominent friction reduction and anti-galling effects. Combined with preheating spraying and high-temperature film formation processes, the lubricating layer can be further ensured to be uniform and dense with excellent adhesion, effectively avoiding defects such as workpiece scratches, folds, cracks, and dimensional deviations. While reducing coating amount and saving production costs, it further improves the molding quality, dimensional accuracy, and finished product qualification rate of the drive shaft, making it more suitable for large-scale, low-cost, and high-quality production of automotive drive shafts.

[0021] Preferably, the active modified silicone oil is composed of water-based modified hydroxypropyl silicone oil and hydrophilic double-ended epoxy polyether silicone oil.

[0022] By adopting the above technical solutions, water-based modified hydroxypropyl silicone oil can promote the rapid spreading and uniform wetting of graphite lubricating film-forming agent on the surface of preheated rod stock, improving the coating's flexibility and crack resistance; hydrophilic double-ended epoxy polyether silicone oil can stabilize the system dispersion and moderately cross-link and cure during heating, enhancing the interfacial bonding force between the lubricating layer and the metal substrate, as well as its high-temperature shear resistance and anti-detachment performance; the combined use of the two can enable the active modified silicone oil to possess excellent wettability, dispersion stability, and high-temperature film strength, ensuring uniform dispersion of graphene-rare earth metal oxide composite powder and graphite, and system stability, resulting in a denser lubricating film, stronger adhesion, and more durable high-temperature lubrication, further reducing workpiece surface defects and improving the forming accuracy and finished product qualification rate of the drive shaft.

[0023] Preferably, the active modified cellulose is sulfonated modified cellulose nanocrystals and / or TEMPO oxidized cellulose nanocrystals.

[0024] By employing the above technical solutions, the surfaces of sulfonated modified cellulose nanocrystals and / or TEMPO oxidized cellulose nanocrystals are rich in active groups, which can improve the dispersion uniformity of graphene-rare earth metal oxide composite powder and graphite in aqueous systems, inhibit powder agglomeration and sedimentation, and ensure long-term storage stability and non-stratification of the film-forming agent; its nanoscale rod-like structure can form a network support framework in the lubricating layer, improving the toughness, density and structural stability of the lubricating layer; and it can be combined with active groups formulated from water-based modified hydroxypropyl silicone oil and hydrophilic double-ended epoxy polyether silicone oil. Modified silicone oil synergistically enhances coating leveling and film uniformity, ensuring the lubricating layer remains continuous, intact, and exhibits strong adhesion at high temperatures of 850℃±20℃, resisting cracking and peeling. In subsequent molding processes, the lubricating layer stably reduces friction and prevents seizing, avoiding surface defects and improving the molding quality, dimensional accuracy, and yield of the drive shaft. This allows the graphite lubricating film-forming agent to achieve excellent lubrication and film-forming effects even with a low coating amount of 20-50g / m², reducing production costs and making it more suitable for large-scale precision molding production of automotive drive shafts.

[0025] Preferably, the graphene-rare earth metal oxide composite powder is composed of graphene, zirconium oxide, borides, and rare earth metal oxides in a weight ratio of 2:(1-2):(0.9-2.5):(0.1-0.5).

[0026] By employing the above technical solution, graphene, zirconium oxide, borides, and rare earth metal oxides are precisely compounded in a weight ratio of 2:(1-2):(0.9-2.5):(0.1-0.5) to form a graphene-rare earth metal oxide composite powder, which maximizes the synergistic effect of each component. Graphene constructs a "flexible skeleton" for the lubrication layer. Under high-temperature and high-pressure molding and processing conditions, its sheets are oriented along the friction direction, providing interlayer sliding lubrication, improving the load-bearing and shear resistance of the lubrication layer, and also providing a stable substrate for the dispersion of inorganic nano-ceramic powder. Zirconia, borides, and rare earth metal oxide nanoparticles form "micro-bearings," converting sliding friction into rolling friction and reducing frictional resistance. Zirconia enhances the stability of the "micro-bearings," while borides improve the hardness and high-temperature stability of the nanoparticles, adapting to high-temperature film formation and molding processes, avoiding wear and failure of the "nano-balls." Furthermore, the high-melting-point ceramic phase forms a dense ceramic alloy transition layer with the rod metal matrix at high temperatures, and the rare earth metal oxides promote in-situ reactions, enhancing the high-temperature adhesion and ablation resistance of the coating. This composite powder forms a highly efficient synergistic lubrication system with graphite, overcoming the shortcomings of single graphite lubrication layers, such as easy detachment at high temperatures, insufficient load-bearing capacity, and limited wear resistance. This results in a synergistic improvement in the lubrication layer's friction reduction, shear resistance, and high-temperature stability. Under the dispersing and stabilizing effects of active modified cellulose and the wetting and high-temperature film-forming effects of active modified silicone oil, the composite powder is uniformly dispersed in an aqueous system, synergistically forming a continuous, dense, and strongly adherent lubrication layer with graphite. Combined with effective coating amount, preheating, and high-temperature film-forming processes, it is compatible with the entire process, reducing surface defects on the workpiece during molding, improving the molding accuracy, surface quality, and overall mechanical properties of the drive shaft, extending mold life, reducing production costs, and meeting the needs of large-scale, precision production of automotive drive shafts.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. Preheating the bar stock at 200-250℃ allows the bar stock surface to reach a suitable spraying temperature, preventing poor spreadability and uneven film formation caused by excessively low temperature, or premature decomposition, local coking, or local film defects caused by excessively high temperature; it also removes residual moisture and slight oil stains from the bar stock surface, improves the bonding interface quality between the lubricating layer and the substrate, and creates conditions for subsequent uniform film formation. 2. Heating the sprayed rod to 850℃±20℃ allows the moisture in the lubricating film-forming agent to evaporate quickly and the organic components to be moderately cured and cross-linked, promoting rapid and dense film formation of the coating; allowing the lubricating layer to form a continuous film with stable structure and strong adhesion at high temperature, avoiding cracking, peeling or local detachment of the lubricating layer due to sudden temperature changes or friction and shearing during the molding process, ensuring continuous lubrication throughout the molding process; 3. The graphite lubricating film-forming agent is formulated by compounding graphite and synergistic dispersion at a weight ratio of 1:(4.5-5.5). The graphene-rare earth metal oxide composite powder in the synergistic dispersion has the characteristics of regular layer structure, excellent high-temperature stability, and strong interfacial bonding activity. This composite powder and graphite form a highly efficient synergistic effect. Graphite provides basic high-temperature lubrication and friction reduction, while the composite powder further forms a high-strength, high-density, and high-adhesion composite lubrication structure on the graphite lubrication skeleton, making up for the defects of single graphite lubrication layer, such as easy detachment at high temperatures, insufficient load-bearing capacity, and limited wear resistance. With the promoting effect of active modified silicone oil to improve the wettability and leveling of the film-forming agent, and active modified cellulose to improve the suspension stability of the system, the lubrication layer maintains a complete and continuous lubrication effect under the harsh conditions of high-temperature forging, reducing defects such as surface scratches, folds, cracks, poor dimensional accuracy, and out-of-form deviations of the workpiece, thereby improving the finished product quality and production qualification rate of the drive shaft. 4. The effective coating amount of graphite lubricating film-forming agent is 20-50 g / m². Within this coating amount range, lubrication requirements can be met while avoiding problems caused by excessive coating amount, reducing raw material waste and costs. Combined with the above synergistic and promoting effects, the forming quality, dimensional accuracy, and finished product qualification rate of the drive shaft are further improved. Attached Figure Description

[0028] Figure 1 This is a dimensional schematic diagram of an automotive driveshaft according to this application. Figure 2 yes Figure 1 A schematic diagram illustrating the technical requirements.

[0029] Figure 3 This is a schematic diagram of the machining and forming process of an automotive drive shaft according to this application. Detailed Implementation

[0030] The following combination Figure 1-3 The present application will be further described in detail with reference to the embodiments.

[0031] Partial ingredient descriptions: The particle size of graphite, graphene, zirconium oxide, borides, and rare earth metal oxides is 100-200 nm. Sulfonated modified cellulose nanocrystals: Tianlu Nanotype TL-005; TEMPO oxidized cellulose nanoparticles: Tianlu Nanomaterials model TL010-2; Waterborne modified hydroxypropyl silicone oil: IOTA2040; Hydrophilic double-ended epoxy polyether silicone oil: IOTA EES22KF; OP-10: CAS No. 9041-29-6; Hydroxyethyl cellulose: CAS No. 9004-62-0.

[0032] Preparation example of graphite lubricating film-forming agent

[0033] Preparation Example 1 A graphite lubricant is obtained by the following method: Based on 1L of synergistic dispersion, weigh 40g / L graphene-rare earth metal oxide composite powder, 60g / L active modified silicone oil, and 5g / L active modified cellulose, mix and disperse them evenly in water, then dilute with water to 1L and stir thoroughly to obtain the synergistic dispersion.

[0034] The graphite lubricating film-forming agent is composed of graphite and a synergistic dispersion in a weight ratio of 1:5; The graphene-rare earth metal oxide composite powder consists of graphene and rare earth metal oxides (composed of lanthanum oxide and niobium oxide in a weight ratio of 1:1) in a weight ratio of 4:1. The active modified cellulose is composed of sulfonated modified cellulose nanocrystals; The active modified silicone oil is composed of water-based modified hydroxypropyl silicone oil and hydrophilic double-ended epoxy polyether silicone oil in a weight ratio of 1:1.

[0035] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that, based on 1L of the synergistic dispersion: 30g / L graphene-rare earth metal oxide composite powder, 80g / L active modified silicone oil, and 3g / L active modified cellulose; the graphite lubricating film-forming agent is composed of graphite and the synergistic dispersion in a weight ratio of 1:5.5.

[0036] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that, based on 1L of the synergistic dispersion: 50g / L graphene-rare earth metal oxide composite powder, 50g / L active modified silicone oil, and 8g / L active modified cellulose; the graphite lubricating film-forming agent is composed of graphite and the synergistic dispersion in a weight ratio of 1:4.5.

[0037] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that the active modified silicone oil is a water-based modified hydroxypropyl silicone oil.

[0038] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 1 is that the active modified silicone oil is composed of hydrophilic double-ended epoxy polyether silicone oil.

[0039] Preparation Example 6 The difference between Preparation Example 6 and Preparation Example 4 is that the active modified cellulose is composed of sulfonated modified cellulose nanocrystals and TEMPO oxidized nanocellulose in a weight ratio of 1:1.

[0040] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 6 is that the graphene-rare earth metal oxide composite powder is composed of graphene, zirconium oxide, borides, and rare earth metal oxides in a weight ratio of 2:2:0.9:0.1.

[0041] Preparation of comparative examples The difference between Comparative Example 1 and Preparation Example 1 is that graphene-rare earth metal oxide composite powder was replaced with an equal amount of graphite.

[0042] The difference between Comparative Example 2 and Example 1 is that the active modified silicone oil was replaced with an equal amount of silane coupling agent 530.

[0043] The difference between Comparative Example 3 and Example 1 is that the active modified cellulose was replaced with an equal amount of hydroxyethyl cellulose.

[0044] The difference between Comparative Example 4 and Example 1 is that the active modified cellulose was replaced with an equal amount of active modified silicone oil.

[0045] The difference between Comparative Example 5 and Preparation Example 1 is that the synergistic dispersion was replaced by an equal amount of OP-10 solution with a mass fraction of 5%. Example

[0046] Example 1 A manufacturing process for an automotive driveshaft, comprising the following steps: The chemical composition of the raw materials is as follows: 0.531% C, 0.291% Si, 0.782% Mn, 0.012% S, 0.282% Cr+M+Mo, 0.027% Al, 0.0064% Cu, 0.0021% Sn, 0.0045% Sb, 0.026% Ti, 0.013% P, with the balance being Fe and other unavoidable impurities.

[0047] 1) The pretreatment of raw materials includes: raw material inspection (the raw material uses Baosteel CF53; metallographic structure: uniform pearlite + ferrite, no granular cementite or bainite is allowed, banded structure grade 2, forgings are 100% magnetic particle tested and demagnetized, residual magnetism 2Gs; ball pitch circle PCD: Ø67.8), warehousing, blanking, chamfering, shot blasting to obtain bar stock; 2) Take 10 bars and put them into the preheating device to preheat to 230°C. Then put them into the spraying device to spray graphite lubricating film-forming agent. The effective coating amount is 20g / m². Hold for 5 minutes. Then put them into the sintering furnace and reheat to 850°C. Hold for 30 minutes to form a lubricating layer on the surface of the bars to obtain the processed material. 3) The material is processed into shapes, including: extrusion rods, upsetting heads, and forging to the dimensions and shapes specified in the drawings (the forming process and dimensions are as follows). Figure 1-3As shown), cooling (water temperature 25℃; water circulation and stirring are turned on; water cooling time 5s) yields a semi-finished product; after forming the drive shaft structure, surface treatment is carried out, including: shot blasting, flaw detection, forging inspection, machining, milling ball track, cleaning and rust prevention, packaging, and testing of the semi-finished product in sequence to obtain the automotive drive shaft.

[0048] The shot blasting parameters in steps 1) and 3) above are: steel shot specification θ0.6; shot blasting time 40 minutes; single-tube product weight 1000Kg; current 20A; no oxide scale on the surface after polishing.

[0049] Examples 2-7 The difference between Examples 2-7 and Example 1 is that the source of the graphite lubricating film-forming agent is different, as shown in Table 1. Table 1. Sources of graphite lubricating film-forming agents in Examples 1-7

[0050] Comparative Example Comparative Examples 1-5 The difference between Comparative Examples 1-5 and Example 1 is that the source of the graphite lubricating film-forming agent is different, as shown in Table 2. Table 2. Sources of graphite lubricating film-forming agents in Comparative Examples 1-5

[0051] Performance testing Sample A: Ten semi-finished products obtained from Examples 1-7 and Comparative Examples 1-5, with an effective coating amount of 20 g / m².

[0052] Sample B: The effective coating amount in the original Examples 1-7 and Comparative Examples 1-5 was changed to 50 g / m², resulting in 10 semi-finished products.

[0053] Experiment (1) Smoothness properties Refer to ISO 4287: Surface roughness profile method; test samples A and B and take the average value. When the surface roughness Ra of the semi-finished product is 0.8 to 1.8 μm, the surface is smooth, without burrs or sticking defects, it is recorded as qualified.

[0054] Experiment (2) Stability of Lubricating Layer Samples A and B were tested and the lubrication layer coverage was calculated, and the average value was taken.

[0055] Lubricant layer coverage: The percentage of the workpiece surface after forging where a continuous and uniform graphite lubricant layer is retained out of the total inspected surface area of ​​the workpiece.

[0056] Judgment rules: Coverage area (metallurgical microscope, magnification 60) Color: Continuous, uniform gray-black, dark black Morphology: Covered with a graphite lubricating layer No metallic luster, no exposed substrate Uncovered area (metallurgical microscope, magnification 60) Colors: Bright white, silver white, metallic Morphology: Directly exposed metal substrate No graphite film, no gray-black layer Commonly found in areas where the lubricating layer has peeled off, is missing, or is severely thinned; Calculation formula: Lubricant layer coverage = Total lubricant layer coverage area of ​​semi-finished product / Surface area of ​​semi-finished product × 100%; The higher the lubricant layer coverage, the less lubricant layer detaches, and the better the stability of the lubricant layer.

[0057] Next, observe the surface of sample A at 50x magnification to see if there are any signs of tearing, folding, or cracking. If any of these problems are found, the sample is considered to be unqualified in appearance.

[0058] The specific experimental data are as follows; Table 3. Experimental data of Examples 1-7 and Comparative Examples 1-4

[0059] Combining Example 1 and Comparative Examples 1-5 with Table 3, it can be seen that, in terms of smoothness, Sample A (20 g / m²) of Comparative Examples 1-5 all exhibited unqualified characteristics, and the lubrication layer coverage of Sample A in Comparative Examples 1-5 was all below 88%. Furthermore, the difference in lubrication layer coverage between Sample B and Sample A was significant (around 9%). In contrast, Sample A in Example 1 achieved a lubrication layer coverage of 93.7%, and the difference between Sample B and Sample A was smaller (around 5%). Regarding appearance, Comparative Examples 1 and 5 exhibited unqualified characteristics, thus demonstrating that the specific characteristics of this application... The process (200-250℃) involves preheating and heating to 850℃±20℃ to form the lubricating layer. Then, a graphite lubricating film-forming agent is used, with graphite and an enhancing dispersion mixed at a weight ratio of 1:(4.5-5.5). The graphene-rare earth metal oxide composite powder in the enhancing dispersion has a regular layered structure, excellent high-temperature stability, and strong interfacial bonding activity. Combined with the promoting effects of active modified silicone oil and active modified cellulose, the lubricating layer maintains a complete and continuous lubrication effect even under the harsh conditions of high-temperature forging. This reduces defects such as surface scratches, folds, cracks, poor dimensional accuracy, and out-of-form deviations in the workpiece, improving the quality and production qualification rate of the drive shaft.

[0060] Compared with Example 6, Example 7 showed a higher lubrication layer coverage in Sample A, while the difference between the lubrication layer coverage of Sample B and Sample A was smaller (around 1.2%). This indicates that the graphene-rare earth metal oxide composite powder, composed of graphene, zirconium oxide, borides, and rare earth metal oxides, can play a synergistic role, enabling the lubrication layer to maintain a complete and continuous lubrication effect under the harsh conditions of high-temperature forging, and reducing defects such as surface scratches, folds, cracks, poor dimensional accuracy, and out-of-form deviations in the workpiece.

[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A manufacturing process for an automotive driveshaft, characterized in that, It is prepared by the following method: 1) Pre-process the raw materials to obtain bar stock; 2) Preheat the bar stock to 200-250℃, spray with graphite lubricating film-forming agent, and then heat to 850℃±20℃ to form a lubricating layer on the surface of the bar stock to obtain the processed material; 3) The material is processed into a drive shaft structure, and then surface treated to obtain the automotive drive shaft; The graphite lubricating film-forming agent is composed of graphite and a synergistic dispersion in a weight ratio of 1:(4.5-5.5); The synergistic dispersion comprises: 30-50 g / L graphene-rare earth metal oxide composite powder, 50-80 g / L active modified silicone oil, 3-8 g / L active modified cellulose, and water to a fixed volume.

2. The manufacturing process of an automotive driveshaft according to claim 1, characterized in that: The forming process in step 3) includes: extruding the rod, upsetting the big end, forging to the size and shape specified in the drawing, and cooling to obtain a semi-finished product.

3. The manufacturing process for an automotive driveshaft according to claim 2, characterized in that: The surface treatment in step 3) includes: sequentially performing shot blasting, flaw detection, forging inspection, machining, milling of ball bearings, cleaning and rust prevention, packaging, and testing on the semi-finished product to obtain the automotive drive shaft.

4. The manufacturing process of an automotive driveshaft according to claim 1, characterized in that: The pretreatment in step 1) includes: raw material inspection, warehousing, cutting, chamfering, shot blasting, and obtaining bar stock.

5. The manufacturing process for an automotive driveshaft according to claim 4, characterized in that, The chemical composition of the raw materials is as follows: 0.531% C, 0.291% Si, 0.782% Mn, 0.012% S, 0.282% Cr+M+Mo, 0.027% Al, 0.0064% Cu, 0.0021% Sn, 0.0045% Sb, 0.026% Ti, 0.013% P, with the balance being Fe and other unavoidable impurities.

6. The manufacturing process of an automotive driveshaft according to claim 1, characterized in that: The effective coating amount of the graphite lubricating film-forming agent is 20-50 g / m².

7. The manufacturing process for an automotive driveshaft according to claim 1, characterized in that: The active modified silicone oil is composed of water-based modified hydroxypropyl silicone oil and hydrophilic double-ended epoxy polyether silicone oil.

8. The manufacturing process of an automotive driveshaft according to claim 1, characterized in that: The active modified cellulose is sulfonated modified cellulose nanocrystals and / or TEMPO oxidized cellulose nanocrystals.

9. The manufacturing process for an automotive driveshaft according to claim 1, characterized in that: The graphene-rare earth metal oxide composite powder is composed of graphene, zirconium oxide, borides, and rare earth metal oxides in a weight ratio of 2:(1-2):(0.9-2.5):(0.1-0.5).

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