A processing method for laser cladding strengthening of a bearing surface

Abstract

The application provides a processing method for laser cladding strengthening of a cast bearing surface, and the processing method comprises the following steps: S1, processing a channel of the cast bearing and pretreating the processed channel; S2, processing a pre-cladding layer on the pretreated channel surface by laser; S3, checking defects of the pre-cladding layer; and S4, processing a functional cladding layer on the pre-cladding layer that passes the defect checking. The pre-cladding layer processing before the functional cladding layer processing greatly reduces the porosity of the cladding layer on the raceway surface of the cast bearing ring, and the one-time qualification rate of the product is increased from 40-50% to more than 98%, so that the material and processing cost are reduced by more than 50%. The single-channel and multi-layer cladding technology is adopted, the overall deformation of the workpiece is small, and the entire cladding layer has good load capacity, wear resistance and fatigue resistance.

Description

Technical Field

[0001] This invention relates to the field of bearing processing technology, and specifically to a processing method for laser cladding strengthening of the surface of cast bearings. Background Technology

[0002] Rolling bearings, as a crucial component of rotating machinery, are primarily used to support shaft rotation, reduce friction during rotation, and ensure accuracy. Front and rear ring bearings, serving as guide bearings for automated artillery units, are widely used in armored vehicles due to their functions of steering, translation, and load-bearing, enabling automated and unmanned operation during firing. Front and rear ring bearings consist of two parts: a front drive ring and a rear drive ring, each composed of an inner ring, an outer ring, and rolling elements. The rolling elements are standard purchased parts, the outer ring is a simple thin-walled annular component, while the inner ring has a more specialized and complex structure, with a wall thickness generally less than 10mm. During production, this presents numerous challenges, including large welding deformation, low material utilization, high machining workload, and low processing efficiency. To address these issues, Chinese patent application number CN 111644570B, "Method for producing inner rings of front and rear ring bearings," uses cast steel material formed by investment casting as the inner ring material. A layer of high-hardness, wear-resistant nano-alloy powder is laser-clad into the inner ring groove of the bearing through a laser cladding process, thereby improving the service life of the bearing.

[0003] However, this solution has the following drawbacks: Since castings inevitably contain numerous defects such as porosity, shrinkage cavities, looseness, and slag inclusions, these defects, distributed near or shallowly on the surface, are easily burned through under laser irradiation during laser cladding. After burning through, the internal gas expands, the pressure increases, and the molten cladding metal is ejected, causing sudden splashing and forming cladding pinholes. This results in a high porosity in the cladding layer and a very low first-pass yield (only 40-50%). Furthermore, this product involves numerous processing steps, particularly during the cladding process. Before the layer defect detection, the process involves more than a dozen steps, including rough turning of the casting surface, rough turning of the casting groove, laser cladding of the groove, fine turning of the surface cladding layer, fine turning of the inner surface of the inner ring, fine turning of the groove cladding layer, rough grinding of the inner surface of the inner ring, rough grinding of the outer surface of the inner ring, rough grinding of the groove cladding layer, and cladding layer defect detection. Once a defect is detected in the product, it needs to be returned to the first step for rework. The rework process is lengthy and labor-intensive, resulting in huge rework costs. Moreover, the quality of the cladding layer after rework cannot be guaranteed. Summary of the Invention

[0004] In view of this, this application provides a laser cladding strengthening method for the surface of cast bearings, which solves the problem in the prior art where the presence of numerous unavoidable defects such as porosity, shrinkage cavities, looseness, and slag inclusions in the castings leads to low cladding quality, resulting in rework and increased costs. The specific solution is as follows:

[0005] A method for laser cladding strengthening of the surface of a cast bearing, the method comprising the following steps:

[0006] Step S1: The cast bearing is machined with grooves, and the machined grooves are pretreated.

[0007] Step S2: A pre-melting coating is processed on the pre-treated channel surface using a laser;

[0008] Step S3: Inspect the pre-melted cladding for defects;

[0009] Step S4: Process the functional cladding layer on the pre-melted cladding layer that has passed the defect inspection.

[0010] Preferably, the cladding process for both the pre-cladding layer and the functional cladding layer uses a rectangular wide-spot laser to perform single-layer, single-pass cladding.

[0011] Preferably, the outer dimensions of the rectangular light spot are larger than the cross-sectional dimensions of the channel to be clad.

[0012] Preferably, the powder feeding rate of the pre-melted cladding layer is lower than that of the functional cladding layer.

[0013] The cladding thickness of the pre-cladding layer is lower than that of the functional cladding layer.

[0014] Preferably, in the pre-coating layer, the linear energy density of laser cladding is 20–30 W·s / mm. 3 ;

[0015] In the functional cladding layer, the linear energy density of laser cladding is 15–25 W·s / mm. 3 .

[0016] Preferably, in step S1, the processing depth h of the channel is less than the cladding layer thickness t;

[0017] The cladding layer thickness t includes the pre-cladding layer thickness t0 and the functional cladding layer thickness t1.

[0018] Preferably, the functional cladding layer thickness t1 includes the retained thickness t2 of the functional cladding layer and the processed thickness t3 of the functional cladding layer.

[0019] Preferably, the thickness t0 of the pre-melted cladding layer is 0.3–0.8 mm;

[0020] The remaining thickness t2 of the functional cladding layer is 0.5–0.6 mm;

[0021] The processing thickness t3 of the functional cladding layer is 0.5 to 0.7 mm.

[0022] Preferably, in step S3, the defect inspection includes: inspection of surface defects of the pre-melted cladding and remelting.

[0023] Preferably, the defect inspection includes surface discontinuity defect inspection.

[0024] Compared with the prior art, the beneficial effects of this application are as follows:

[0025] This application achieves the elimination of defects on the surface or near-surface of the bearing casting material to be clad by laser pre-melting cladding before the functional cladding layer, or exposes the defects on the surface of the pre-melting cladding layer; and through defect inspection, the defective areas are ground and remelted, so as to ensure that the subsequent functional cladding layer can obtain continuous and defect-free product quality.

[0026] In this application, both the pre-cladding layer and the functional cladding layer are clad using wide-spot laser cladding technology. The profile size of the wide spot is larger than the cross-sectional size of the channel, which avoids the problem of high product defect rate caused by the need for multiple overlapping cladding steps with small circular spots used in the prior art. This results in a smoother surface of the functional cladding layer, smaller processing allowance, and higher processing efficiency.

[0027] This application employs low powder content, low thickness, and high linear energy density for cladding during the pre-melting cladding stage, further eliminating defects such as porosity, shrinkage cavities, looseness, and inclusions in castings, and further reducing the impact on the quality of the functional cladding layer.

[0028] This application employs a large amount of powder, a large thickness, and a low linear energy density in the functional cladding layer processing stage, which can avoid large deformation of the workpiece while ensuring the cladding quality.

[0029] This application employs single-pass, multi-layer cladding technology in both the pre-cladding layer and the functional cladding layer processing stages, resulting in low linear energy density of each laser cladding layer, small overall workpiece deformation, and giving the entire cladding layer good load-bearing capacity, wear resistance, and fatigue resistance. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0031] In the attached diagram:

[0032] Figure 1 This is a schematic diagram of the structure of the laser cladding layer of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure for machining the channel of the present invention;

[0034] Figure 3This is a schematic diagram of the structure after the cladding of the present invention is completed.

[0035] Among them, 1-channel, 2-pre-melting cladding, 3-functional cladding, 4-cladding, 5-cast bearing ring base. Detailed Implementation

[0036] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0037] According to the appendix Figure 1-3 The method shown is a laser cladding strengthening process for the surface of a cast bearing, the process comprising the following steps:

[0038] A method for laser cladding strengthening of the surface of a cast bearing, the method comprising:

[0039] Step S1: The cast bearing is machined with grooves, and the machined grooves are pretreated.

[0040] Step S2: A pre-melting coating is processed on the pre-treated channel surface using a laser;

[0041] Step S3: Inspect the pre-melted cladding for defects;

[0042] Step S4: Process the functional cladding layer on the pre-melted cladding layer that has passed the defect inspection.

[0043] Furthermore, the cladding process for both the pre-cladding layer and the functional cladding layer employs a rectangular wide-spot laser for single-layer, single-pass cladding.

[0044] Furthermore, the outer dimensions of the rectangular light spot are larger than the cross-sectional dimensions of the channel to be clad.

[0045] Furthermore, the powder feeding rate of the pre-melted cladding layer is lower than that of the functional cladding layer.

[0046] The cladding thickness of the pre-cladding layer is lower than that of the functional cladding layer.

[0047] Furthermore, in the pre-melted cladding layer, the linear energy density of laser cladding is 20–30 W·s / mm². 3 ;

[0048] In the functional cladding layer, the linear energy density of laser cladding is 15–25 W·s / mm. 3 .

[0049] It should be noted that the powder quantity mentioned in this application refers to the mass of powder fed into the molten pool per unit time. Low powder quantity means that the process powder feeding quantity is lower than that of the functional cladding layer, and the cladding thickness of the pre-cladding layer is lower than that of the functional cladding layer. In one embodiment of this application, the thickness range of the pre-cladding layer is 0.3-0.8 mm, while the thickness range of the functional cladding layer is 1-1.3 mm.

[0050] Furthermore, in step S1, the processing depth h of the channel is less than the cladding layer thickness t;

[0051] The cladding layer thickness t includes the pre-cladding layer thickness t0 and the functional cladding layer thickness t1.

[0052] Furthermore, the functional cladding layer thickness t1 includes the retained thickness t2 of the functional cladding layer and the processed thickness t3 of the functional cladding layer.

[0053] Furthermore, the thickness t0 of the pre-melted cladding layer is 0.3–0.8 mm;

[0054] The remaining thickness t2 of the functional cladding layer is 0.5–0.6 mm;

[0055] The processing thickness t3 of the functional cladding layer is 0.5 to 0.7 mm.

[0056] Furthermore, in step S3, the defect inspection includes: inspection of surface defects of the pre-melted cladding and remelting.

[0057] Furthermore, the defect inspection includes surface discontinuity defect inspection.

[0058] It should be noted that:

[0059] Laser cladding technology is more suitable for treating bearing inner rings than traditional methods such as welding, spraying, and electroplating because it features strong bonding between the cladding layer and the base material, small thermal deformation of the workpiece, dense and uniform structure of the cladding layer, wide range of cladding materials, material saving, convenient process, and the ability to achieve automated production.

[0060] In this application, the surface defect inspection of the pre-melted cladding can be carried out manually or by a detection device. In one embodiment of this application, the defect inspection is mainly carried out manually.

[0061] In this application, the cross-sectional dimension of the channel refers to the horizontal cross-sectional dimension of the channel. The outline dimension of the rectangular wide spot is set to be larger than the cross-sectional dimension of the channel, so that the laser cladding of a unit cross-section of the channel can be completed in a single pass.

[0062] In this application, the material for laser cladding is any one of iron-based, nickel-based, or copper-based powder alloys.

[0063] The present application will be explained and illustrated in more detail below through the following embodiments.

[0064] Example 1

[0065] The specific processing steps of laser cladding for bearing rings made of ZG32MnMo through precision investment casting are as follows:

[0066] 1) The bearing ring is machined with grooves. The machining depth h is 1.4 mm and the machining width b is 12 mm.

[0067] 2) Use alcohol to clean and degrease the surface of the channel;

[0068] 3) Pre-coating laser processing: A 2*14mm rectangular wide-spot laser is used to perform pre-coating on the cleaned bearing raceway in a single-layer, single-pass cladding process. The thickness t0 of the pre-coating is 0.5mm; the linear energy density of the cladding laser is 20W·s / mm. 3 .

[0069] 4) Pre-melted coating defect inspection: Check whether there are discontinuous defects such as pores and inclusions on the surface of the pre-melted coating; if there are no such defects on the surface of the pre-melted coating, proceed directly to the next processing step; if there are such defects on the surface of the pre-melted coating, use an angle grinder or polishing machine to polish the curved area. The polished area should have a smooth transition, and laser cladding should be performed on the polished area for repair.

[0070] 5) Laser processing of the functional cladding layer: A 2*14mm rectangular wide spot laser is used to process the functional cladding layer on the surface of the pre-cladding layer in a single-pass, two-layer cladding manner. The thickness t1 of the functional cladding layer is 1.1mm. The linear energy density of the laser used for cladding is 15W·s / mm. 3 .

[0071] 6) The functional cladding layer is machined by turning and grinding.

[0072] After the above processing steps, the first-pass yield of the product reached 98%, and the workpiece deformation was 0.08mm.

[0073] Example 2

[0074] Laser cladding is performed on bearing rings made of ZG32MnMo material and formed by precision investment casting. The cladding process specifically includes the following steps:

[0075] 1) In the machining of the bearing ring groove, the machining depth h is 1.7mm and the machining width b is 12mm.

[0076] 2) Clean and degrease the raceway surface of the bearing ring with alcohol;

[0077] 3) Pre-coating laser processing: A 2*14mm rectangular wide-spot laser is used to process the pre-coating layer on the channel surface in a single-layer, single-pass cladding manner. The thickness t0 of the pre-coating layer is 0.7mm. The linear energy density of the laser used for cladding is 25W·s / mm². 3 .

[0078] 4) Pre-melted coating defect inspection: Check whether there are discontinuous defects such as pores and inclusions on the surface of the pre-melted coating; if there are no such defects on the surface of the pre-melted coating, proceed directly to the next processing step; if there are such defects on the surface of the pre-melted coating, use an angle grinder or polishing machine to polish the defective area. The polished area should have a smooth transition, and laser cladding repair should be performed on the polished area.

[0079] 5) Laser processing of the functional cladding layer: A 2*14mm rectangular wide spot laser is used to process the functional cladding layer on the surface of the pre-cladding layer in a single-pass, two-layer cladding manner; the thickness t1 of the functional cladding layer is 1.2mm; the linear energy density of the laser used for cladding is 20W·s / mm. 3 .

[0080] 6) The functional cladding layer is machined by turning and grinding.

[0081] After the above processing steps, the product's first-pass yield reached 100%, and the workpiece deformation was 0.10mm.

[0082] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for laser cladding strengthening of the surface of a cast bearing, characterized in that, The processing method includes: Step S1: The cast bearing is machined with grooves, and the machined grooves are pretreated. Step S2: A pre-melting coating is processed on the pre-treated channel surface using a laser; Step S3: Inspect the pre-melted cladding for defects; Step S4: Process the functional cladding layer on the pre-melted cladding layer that has passed the defect inspection; During the cladding process of the pre-cladding layer and the functional cladding layer, a rectangular wide-spot laser is used to perform single-layer, single-pass cladding on the pre-cladding layer. The outer dimensions of the rectangular wide spot are larger than the cross-sectional dimensions of the channel to be clad; In the pre-melted cladding layer, the linear energy density of laser cladding is 20~30 W·s / mm. 3 ; In the functional cladding layer, the linear energy density of laser cladding is 15~25 W·s / mm. 3 ; In step S1, the processing depth h of the channel is less than the cladding layer thickness t; The cladding layer thickness t includes the pre-cladding layer thickness t0 and the functional cladding layer thickness t1; The thickness t1 of the functional cladding layer includes the retained thickness t2 of the functional cladding layer and the processed thickness t3 of the functional cladding layer; The thickness t0 of the pre-melted cladding layer is 0.3~0.8 mm; The remaining thickness t2 of the functional cladding layer is 0.5~0.6mm; The processing thickness t3 of the functional cladding layer is 0.5~0.7mm.

2. The processing method for laser cladding strengthening of the surface of a cast bearing according to claim 1, characterized in that, The cladding thickness of the pre-cladding layer is less than the cladding thickness of the functional cladding layer.

3. The processing method for laser cladding strengthening of the surface of a cast bearing according to claim 1, characterized in that, In step S3, the defect inspection includes: inspection of surface defects of the pre-melted cladding and remelting.

4. The processing method for laser cladding strengthening of the surface of a cast bearing according to claim 1, characterized in that, The defect inspection includes the inspection of surface discontinuities.

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