Static impulse wave deformation hardening method for bimetallic sliding bearing

Abstract

The invention discloses a static pulse wave deformation hardening method for a bimetallic sliding bearing, which comprises the following steps: (1) placing a rod-type roller on the upper surface of a bimetallic material, enabling an impact head of a static pulse generator to directly face the rod-type roller, and arranging a waveguide between the impact head and the rod-type roller; (2) the static pulse generator drives an impact head to generate mechanical impact, and the impact head impacts the waveguide statically pressed on the surface of the bimetallic material with preset energy; and (3) the impact force is directionally transmitted to a to-be-treated area on the upper surface of the bimetallic material through the rod type roller, then plane mechanical deformation impact waves are excited on a contact interface, after the impact waves act on the surface of the bimetallic material, multidirectional alternating stress is generated through induction of mechanical impact energy, and the surface of the bimetallic material is subjected to surface treatment. And an upper plating layer of the bimetallic material is forced to generate plastic deformation, so that submicron grain refinement and dislocation density improvement are realized, and the hardness of the bimetallic material is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material surface hardening, and in particular relates to a static pulse wave deformation hardening method for a bimetallic sliding bearing. Background Art

[0002] Sliding bearings, as core components supporting rotating shafts in mechanical equipment, directly determine their load-bearing capacity, operating efficiency, and service life. As industrial technology advances toward high speeds, heavy loads, and high precision, sliding bearings made from single metals suffer from low load capacity and poor wear resistance, making them difficult to meet the demands of extreme operating conditions. In recent years, bimetallic materials such as steel-copper and steel-aluminum have become the mainstream materials for sliding bearings due to their superior overall performance. Bimetallic sliding bearings typically feature a steel substrate as the load-bearing layer and a copper alloy coating as the wear-resistant layer. Their inner surface directly contacts the shaft and must withstand high friction and alternating loads. Data shows that coating the metal substrate significantly improves its friction and wear performance. Copper-based alloy coatings, due to their self-lubricating properties, play an indispensable role in sliding bearings, pumps, and motors. Lead bronze, in particular, is widely used in systems operating under boundary lubrication or dry friction conditions because it contains lead, an effective solid lubricant. The following are existing methods for preparing these metal materials.

[0003] A method for preparing a bimetallic material by sintering copper alloy powder on a steel strip specifically comprises the following steps: copper alloy powder (Cu, 10% Pb, 10% Sn) is evenly distributed on the surface of a copper-plated low-carbon steel substrate to form a copper alloy coating with a thickness of 10 μm, which is then sintered to form a 1 mm thick copper plating layer. First, the copper alloy powder is preheated to a temperature close to the Curie point of the steel substrate. Subsequently, the substrate coated with the alloy powder is placed in an electric furnace, where the alloy powder is subjected to a first sintering treatment. Next, the sintered material is rolled at a compression rate of 4% and subjected to a second sintering treatment under the same conditions as the first sintering. One of the disadvantages of the bimetallic material obtained by this method is that the lead-containing copper alloy layer exhibits lower strength under friction, especially when subjected to periodic high specific pressure.

[0004] A thermomechanical processing method for a copper alloy comprises the following steps: first, heating the copper alloy to a temperature range of 850-980°C and maintaining the temperature for 0.5-2 hours to ensure uniform temperature, followed by a hardening treatment; then, aging the copper alloy within a temperature range of 350-650°C for 2-8 hours; then, subjecting the copper alloy to severe plastic deformation via a continuous equal channel angular pressing process within a temperature range of 350-450°C, with a true deformation not exceeding 2%; and finally, rolling the copper alloy at room temperature to a compression of not less than 20%. Through the above processing, a submicrocrystalline or nanocrystalline structure is formed in the copper alloy, particularly when the average grain / subgrain size is less than 300nm, which can significantly improve the physical and mechanical properties of the copper alloy, thereby obtaining a semi-finished product with excellent performance.

[0005] A method for static pulse treatment of metal materials through surface plastic deformation (PDD). This method forms a hardened layer on the surface of the metal material by applying a deformation shock wave, thereby generating a series of plastic indentations with a certain size, overlap rate and number of applications on the hardened surface. During the static pulse treatment process, the microstructure of the metal material is refined, thereby effectively enhancing its mechanical properties. The depth of the surface hardened layer of the metal material treated by this method can be controlled within the range of 0.1-0.3mm to 8-10mm, and the hardness can reach 35-45HRC. This process can significantly improve the wear resistance and fatigue resistance of metal materials and extend their service life.

[0006] In the cold state, static pulse processing methods are usually used when performing surface plastic deformation on workpieces repaired by surfacing. In addition, static pulse processing methods are also widely used in surface plastic hardening treatment of surfacing materials under different temperature conditions. Specifically, a steel metal material is first surfacing on a steel metal substrate, and then, under different temperature conditions, static pulse processing is used to apply multi-stage mechanical deformation shock waves to harden the surfacing material. The technical effect of this process is mainly reflected in significantly improving the hardness and strength of the coated metal material by reducing the characteristic size of grains and phase elements. However, at present, the static pulse processing method has not been widely used in the hardening treatment of non-ferrous metal coatings obtained by sintering bimetallic materials. Summary of the Invention

[0007] In view of this, the purpose of the present invention is to improve the hardness of the copper alloy coating in the bimetallic material by reducing the characteristic grain size and phase elements to address the problem that the existing technology cannot achieve good deformation hardening effect when the bimetallic material is subjected to high pressure or high temperature conditions.

[0008] The present invention provides a static pulse wave deformation hardening method for a bimetallic sliding bearing, which is characterized in that it includes the following steps: (1) placing a rod-type roller on the upper surface of a bimetallic material and facing the impact head of a static pulse generator to the rod-type roller, with a waveguide being arranged between the impact head and the rod-type roller; (2) the static pulse generator drives the impact head to generate a mechanical impact, and the impact head strikes the waveguide statically pressed against the surface of the bimetallic material with a preset energy; (3) the impact force is directionally transmitted to the to-be-treated area on the upper surface of the bimetallic material through the rod-type roller, thereby exciting a planar mechanical deformation shock wave at the contact interface, and after the shock wave acts on the surface of the bimetallic material, multi-directional alternating stress is induced by the mechanical impact energy, forcing the upper coating of the bimetallic material to undergo plastic deformation, thereby achieving submicron grain refinement and improvement of dislocation density and enhancing its hardness.

[0009] Preferably, the bimetallic material is a copper alloy plated on a steel substrate.

[0010] Preferably, the waveguide is in close contact with the bimetallic surface by static compression to ensure that the mechanical deformation shock wave energy is delivered to the target area in the range of 50-200J.

[0011] Preferably, the ratio of the impact energy A of the static pulse generator to the footprint area F of the rod roller is in the range of A / F = 1.5-2.5 J / mm 2 .

[0012] Preferably, the copper alloy is a lead-copper alloy.

[0013] Preferably, the blank is heated to 0.85T pl.pb -0.95T pl.pb In the temperature range of , mechanical deformation shock wave is used for static pulse treatment, where T pl.pb The melting point of lead.

[0014] By adopting the above technical solution, the present invention can achieve the following technical effects: The present invention addresses the pain points of existing bimetallic sliding bearing hardening technology, which relies on high-temperature treatment, has high energy consumption and insufficient interface bonding strength. The present invention proposes a static pulse wave deformation hardening method for bimetallic sliding bearings. The impact head is driven by a pulse signal to impact the waveguide, and the generated mechanical deformation shock wave directly acts on the metal surface, and combined with the waveguide to transmit the impact energy in a directionally manner. At room temperature or low temperature, this method can achieve submicron grain refinement and interface gradient nanostructure strengthening of the copper alloy coating. By precisely controlling the unit impact energy density, the hardness and interface bonding strength are significantly improved while avoiding material damage. Compared with traditional processes, the energy efficiency of this method is greatly improved and the energy consumption is significantly reduced. This method abandons complex high-temperature processes and adopts pure mechanical impact to achieve efficient and low-cost mass production. It is particularly suitable for optimizing the wear resistance and fatigue resistance of high-precision sliding bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For those skilled in the art, other relevant drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 Schematic diagram of the implementation principle of the method for hardening the copper alloy in the bimetallic material of the present invention;

[0017] The accompanying drawings are numeraled as follows: 1-impact head; 2-waveguide (a structural component for directional transmission of mechanical deformation shock wave energy); 3-rod roller; 4-coated metal material; 5-surfacing metal material hardened by static pulse mechanical deformation shock wave treatment; 6-steel substrate; A-impact energy; f-impact frequency; P st - waveguide preload static force; S - rod roller feed direction; x - indentation size obtained under given indentation overlap conditions;. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by the first technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by the first technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] Example

[0020] The following are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the following embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

[0021] The present invention provides a static pulse processing mechanical wave deformation hardening process as follows:

[0022] See the instructions attached Figure 1This pulse generator is capable of generating controllable impact energy and frequency, with an energy range of 50-200 J and a frequency range of 7-40 Hz. Its main components include an impact head 1 and a waveguide 2. During the hardening process, the pulse generator drives the impact head 1 to generate a mechanical impact, which strikes the waveguide 2, which is statically pressed against the surface of the bimetallic material, with a preset energy. The impact force is directed to the treated area via a rod-type roller 3, thereby stimulating a planar mechanical deformation shock wave at the contact interface. Upon impacting the bimetallic surface, the mechanical impact energy induces multidirectional alternating stresses, forcing plastic deformation of the copper alloy coating. This results in submicron grain refinement and an increase in dislocation density, significantly enhancing hardness. Key characteristics of this process include the temporal variation of the impact force, its maximum value, the duration of the impact (i.e., the duration of the mechanical deformation shock wave), and the energy of the mechanical deformation shock wave. These characteristics are influenced by the geometry of the impact head 1 and waveguide 2, the material properties, and the impact velocity. The mechanical deformation shock wave consists of a series of pulses, each with a duration equal to the wave period. The shape of the shock pulse (i.e., the change of force over time) is transmitted to the deformation area where the rod roller contacts the hardened material, which will directly affect the efficiency of dynamic loading. Before the hardening treatment, the waveguide 2 is in close contact with the bimetallic surface by static compression to ensure that the mechanical deformation shock wave energy is efficiently transmitted to the target area within the range of 50-200J, maximizing the use of the pulse load to induce plastic deformation of the material, thereby significantly improving the hardening effect. Throughout the process, the shape of the shock pulse is adjusted to the greatest extent to adapt to the ductility of the copper alloy and the strength of the steel matrix as well as the material properties of the loading conditions. This not only improves the hardening efficiency, but also expands the technical capabilities of the processing, allowing a deeper hardened layer to be formed. During the continuous feeding process of the rod roller 3, the plastic imprint is ensured to be covered without gaps by precisely controlling the indentation overlap coefficient and the regular arrangement of the impact trajectory, achieving high consistency of the surface strengthening layer, and effectively avoiding the local softening or cracking problems caused by energy dispersion in traditional processes.

[0023] The plastic mark left by the rod roller is a comprehensive feature of the fluctuating deformation hardening during static pulse machining, which determines the properties of the hardened surface layer. 2 ) ratio, i.e., unit impact energy, reflects the energy consumption during the hardening process and indicates the energy required to obtain the desired properties of the hardened surface layer. Studies have shown that when using static pulse treatment for wave deformation hardening of lead bronze coatings, the recommended unit impact energy range is A / F = 1.5-2.5J / mm 2 When the static pulse treatment mode of the mechanical deformation shock wave provides an A / F ratio of less than 1.5, the characteristic size of the grains is insufficiently ground, and the hardness and strength of the coating increase; when the A / F ratio is greater than 2.5, the coating exhibits plasticity, resulting in a decrease in its strength.

[0024] To harden and grind structural parts (primarily lead components) to increase hardness, it is recommended to use static pulse treatment with mechanical deformation shock waves while heating the blank to a temperature range of (0.85-0.95)Tpl.pb°C, where Tpl.pb is the melting point of lead (327.46°C). This treatment achieves the best results.

[0025] Example 1

[0026] A 1 mm thick copper-based alloy surface layer (base: Cu; Pb = 9-11%; Sn = 9-11%; Fe ≤ 0.7%; other alloying elements ≤ 0.5%) was sprayed onto a 7 mm thick steel flat sample (chemical composition: C = 0.17-0.24%; Mn = 0.30-0.60%; Si ≤ 0.40%; P ≤ 0.045%; S ≤ 0.045%). The hardness of the sprayed layer is 85-87 HB. After spraying, the copper alloy surface layer is subjected to static pulse mechanical deformation shock wave hardening treatment. The indentation area of the rod roller is 60 mm. 2 The loading energy of the mechanical deformation shock wave is 150J (the unit impact energy is 2.5J / mm 2 ), the impact frequency is 10 Hz, the overlap coefficient of the plastic indentation is 0.4, and the initial preload static force of the waveguide is 20 kN. Therefore, after static pulse hardening treatment, the hardness of the sprayed coating increases to 110 HB.

[0027] Example 2

[0028] A sample similar to that in Example 1 was used. After spraying, the bimetallic material was heated to 0.85-0.95 Tpl.pb°C and the copper alloy layer was hardened in the hot state by static pulse mechanical deformation shock wave treatment. The indentation area of the rod roller was 62.4 mm 2 The loading energy of the mechanical deformation shock wave is 150J (the unit energy of the impact is 2.4J / mm 2 ), the impact frequency is 10 Hz, the overlap coefficient of plastic indentation is 0.4, and the preload static force of the waveguide is 20 kN.

[0029] Therefore, after static pulse hardening treatment, the hardness of the spray coating increases to 125HB.

[0030] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A static pulse wave deformation hardening method for a bimetallic sliding bearing, characterized in that: The method comprises the following steps: (1) placing a rod-type roller on the upper surface of a bimetallic material and directing an impact head of a static pulse generator toward the rod-type roller, with a waveguide provided between the impact head and the rod-type roller; (2) the static pulse generator drives the impact head to generate a mechanical impact, and the impact head strikes the waveguide statically pressed against the surface of the bimetallic material with a preset energy; (3) The impact force is directed to the area to be processed on the upper surface of the bimetallic material through the rod-type roller, thereby exciting a planar mechanical deformation shock wave at the contact interface. After the shock wave acts on the surface of the bimetallic material, it induces multi-directional alternating stress through mechanical impact energy, forcing the upper coating of the bimetallic material to undergo plastic deformation, thereby achieving submicron grain refinement and improvement of dislocation density and enhancing its hardness.

2. The static pulse wave deformation hardening method for metal sliding bearings according to claim 1, characterized in that: The bimetallic material is a copper alloy plated on a steel substrate.

3. The static pulse wave deformation hardening method for metal sliding bearings according to claim 1 or 2, characterized in that: The waveguide is in close contact with the bimetallic surface through static compression to ensure that the mechanical deformation shock wave energy in the range of 50-200J is transmitted to the target area.

4. The static pulse wave deformation hardening method for metal sliding bearings according to claim 1, characterized in that: The ratio of the impact energy A of the static pulse generator to the footprint area F of the rod roller is in the range of A / F = 1.5-2.5 J / mm2.

5. The static pulse wave deformation hardening method for metal sliding bearings according to claim 1, characterized in that: The copper alloy is a lead-copper alloy.

6. The static pulse wave deformation hardening method for metal sliding bearings according to claim 5, characterized in that: When the blank is heated to 0.85T pl.pb -0.95 Tpl.pb In the temperature range of , mechanical deformation shock wave is used for static pulse treatment, where T pl.pb The melting point of lead.

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