Grinding method for low-hardness bushing parts

Abstract

The application discloses a grinding method for a low-hardness shaft sleeve part, relates to the field of grinding processes of shaft sleeve parts, and aims to prepare a high-hardness wear-resistant layer on the outer surface of the shaft sleeve part, install the shaft sleeve part on a center frame, make the supporting point of the center frame correspond to the high-hardness wear-resistant layer, then perform grinding treatment, and remove the high-hardness wear-resistant layer after the grinding is completed; wherein the high-hardness wear-resistant layer is a metal layer with a hardness greater than HRC55. By arranging the high-hardness wear-resistant layer on the outer surface of the shaft sleeve part, when the shaft sleeve part and the supporting point of the center frame rotate relative to each other, the supporting point of the center frame abuts on the high-hardness wear-resistant layer, the high hardness and wear resistance of the high-hardness wear-resistant layer make it difficult for the supporting point of the center frame to scratch or scratch on the high-hardness wear-resistant layer, and therefore the shaft sleeve part can maintain good rotary accuracy during the whole grinding process; even if the supporting point of the center frame produces a slight scratch on the high-hardness wear-resistant layer, the high-hardness wear-resistant layer can be removed after the grinding is completed, and the product quality of the shaft sleeve part is not affected.

Description

Technical Field

[0001] This invention relates to the field of grinding processes for bushing-type parts, specifically a grinding method for low-hardness bushing-type parts. Background Technology

[0002] When grinding heat-treated bushing-type parts, a center rest is usually used for mounting. The center rest is supported on the outer surface of the part, and the part rotates around the center rest's support point.

[0003] Low-hardness bushing parts refer to bushing parts with a hardness below HRC35, such as housings and long spacers. Due to their low hardness, these parts are prone to scratches on their outer surface during grinding due to the center rest fulcrum. Moreover, as the machining time increases, the scratch depth gradually increases, leading to a decrease in the rotational accuracy of the parts, more pronounced runout, and ultimately an adverse effect on grinding accuracy.

[0004] Existing technologies typically employ a flexible wear-resistant layer or rollers inside the center support fulcrum to reduce scratches on the outer surface of the part. However, regardless of whether a flexible wear-resistant layer or rollers are used, the outer surface of the bushing-like part still needs to be in direct contact with the corresponding flexible wear-resistant layer or rollers, resulting in relative movement. Therefore, the risk of friction and scratches on the outer surface of the bushing-like part remains. Furthermore, if the flexible wear-resistant layer is too soft, it is prone to compression deformation under the weight and centrifugal force of the bushing-like part, causing eccentricity during rotation and affecting the grinding accuracy. If the flexible wear-resistant layer is too hard, the contact and relative movement between the harder wear-resistant layer and the softer part still pose a significant risk of scratches. Similarly, using rollers made of either flexible or rigid materials will result in similar problems as with flexible wear-resistant layers. Summary of the Invention

[0005] The present invention aims to provide a grinding method for low-hardness bushing parts, so as to improve grinding accuracy, reduce the damage of the fulcrum to the outer surface accuracy of the parts, and thus improve the rotational accuracy and grinding quality of the parts.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows: a grinding method for low-hardness bushing parts, wherein a high-hardness wear-resistant layer is prepared on the outer surface of the bushing part, the bushing part is mounted on a center frame so that the fulcrum of the center frame corresponds to the high-hardness wear-resistant layer, and then grinding is performed, and the high-hardness wear-resistant layer is removed after grinding; wherein, the high-hardness wear-resistant layer is a metal layer with a hardness greater than HRC55.

[0007] As a further optimization of the above technical solution, the high-hardness wear-resistant layer is made of metal powder by laser cladding.

[0008] As a further optimization of the above technical solution, the metal powder is cemented carbide powder or tungsten carbide powder.

[0009] As a further optimization of the above technical solution, the thickness of the high-hardness wear-resistant layer is 0.4-0.8mm.

[0010] As a further optimization of the above technical solution, the high-hardness wear-resistant layer is annular and there are multiple high-hardness wear-resistant layers, which are distributed at intervals along the axial direction of the bushing-type parts.

[0011] As a further optimization of the above technical solution, the specific steps include:

[0012] S1: Rough grinding of the outer surface, inner surface and end face of bushing-type parts;

[0013] S2: Aging treatment for bushing-type parts after rough grinding;

[0014] S3: Prepare a high-hardness wear-resistant layer on the outer surface of bushing-type parts;

[0015] S4: Install the bushing-type parts on the center frame, and keep the support points of the center frame corresponding to the high-hardness wear-resistant layer. Then, perform fine grinding on the inner surface and end face of the bushing-type parts.

[0016] S5: Remove the high-hardness wear-resistant layer;

[0017] S6: Fine grinding of the outer surface of bushing-type parts.

[0018] As a further optimization of the above technical solution, in step S1, when rough grinding the bushing-type parts, the allowance is 0.2mm on the outer surface, 0.1mm on the inner surface, and 0.1mm on the end face.

[0019] As a further optimization of the above technical solution, the aging process in step S2 takes 24 hours.

[0020] As a further optimization of the above technical solution, in step S3, the high-hardness wear-resistant layer set on the outer surface of the bushing-type part is semi-finished to make its roundness less than 2um.

[0021] As a further optimization of the above technical solution, in step S5, the mandrel is inserted into the bushing-type part, and the high-hardness wear-resistant layer on the outer surface of the bushing-type part is removed by grinding.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention avoids direct contact between the bushing-like parts and the fulcrum by setting a high-hardness wear-resistant layer on the outer surface of the bushing-like parts. When the bushing-like parts rotate relative to the center support fulcrum, the center support fulcrum abuts against the high-hardness wear-resistant layer. On the one hand, the high hardness and wear resistance of the high-hardness wear-resistant layer itself makes it difficult for the center support fulcrum to cause scratches or damage on it. Therefore, the bushing-like parts can maintain good rotational accuracy throughout the grinding process. On the other hand, even if the center support fulcrum causes minor scratches on the high-hardness wear-resistant layer, the high-hardness wear-resistant layer will be removed after grinding, so it will not affect the product quality of the bushing-like parts.

[0024] This invention effectively avoids scratches on the outer surface of the part by the center support point without changing the overall hardness and structure of the part, thus improving the rotational accuracy of the part. The wear resistance of the coating reduces the loss of accuracy during the processing. The coating thickness and material can be adjusted as needed, making it suitable for grinding bushing parts with low hardness and various sizes, and has good market application prospects.

[0025] In the grinding method of the present invention, only a local coating treatment is performed on the outer surface of the part, without changing the overall hardness of the part. After processing, the coating can be removed without changing the original part structure. Attached Figure Description

[0026] Figure 1 This is a structural schematic diagram of a bushing-type part;

[0027] Figure 2 A schematic diagram of a bushing-type part mounted on a central frame;

[0028] Reference numerals: 1. Bushing type parts, 2. High hardness wear-resistant layer, 3. Center frame, 4. Support point. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of the present invention should be understood as prior art known or should be known by those skilled in the art.

[0030] like Figure 1 , 2 As shown, this invention discloses a grinding method for low-hardness bushing-type parts. A high-hardness wear-resistant layer 2 is prepared on the outer surface of the bushing-type part 1. The bushing-type part 1 is mounted on a center frame 3, so that the fulcrum 4 of the center frame 3 corresponds to the high-hardness wear-resistant layer 2. Then, grinding is performed. After grinding, the high-hardness wear-resistant layer 2 on the outer surface of the bushing-type part 1 is removed. The high-hardness wear-resistant layer 2 is a metal layer with a hardness greater than HRC55.

[0031] Specifically, the high-hardness wear-resistant layer 2 is prepared by laser cladding of metal powder, which can be cemented carbide, tungsten carbide, or other wear-resistant metal powder. The thickness of the high-hardness wear-resistant layer 2 can be adjusted as needed to ensure sufficient wear resistance and support strength. For bushing-type parts 1 with a hardness lower than HRC35, the thickness of the high-hardness wear-resistant layer 2 is 0.4-0.8 mm.

[0032] In addition, the high-hardness wear-resistant layer 2 can also be prepared by other existing technologies, such as brazing, as long as its hardness meets HRC55.

[0033] Different bushing-type parts 1 have different lengths. For longer bushing-type parts 1, they need to be installed in multiple center supports 3 during grinding. The high-hardness wear-resistant layer 2 can be set as a whole wear-resistant layer covering the outer surface of the bushing-type part 1, or multiple layers can be set at intervals. It is only necessary to ensure that the high-hardness wear-resistant layer 2 is set at the corresponding position of each center support 3.

[0034] In this embodiment, the high-hardness wear-resistant layer 2 is annular and there are multiple layers, which are distributed at intervals along the axial direction of the bushing-type part 1. By setting multiple high-hardness wear-resistant layers 2, the outer surface of the bushing-type part 1 can be locally coated, which saves the raw materials required for coating preparation and also reduces the workload of preparing and removing the high-hardness wear-resistant layer 2 to a certain extent.

[0035] The overall grinding process for bushing-type parts 1 is as follows: rough grinding of the outer surface → rough grinding of the inner surface → rough grinding of the end face → aging treatment → laser cladding → semi-finish grinding of the outer surface → finish grinding of the inner surface → finish grinding of the end face → post-treatment of the outer surface → finish grinding of the outer surface. The grinding method of this invention is described below using the grinding process of the housing of bushing-type parts 1 as an example:

[0036] S1: Rough grinding of the outer surface, inner surface and end face of bushing type part 1.

[0037] S101: Rough grinding of the outer surface;

[0038] S1011: Use rough grinding equipment (such as a universal cylindrical grinder) to perform preliminary grinding on the outer surface of the bushing-type part 1. Adjust the grinding machine parameters according to the material and size of the bushing-type part 1. During the grinding process, control the grinding depth to ensure that an appropriate amount of material is removed with each grinding, until the remaining material on the outer surface reaches 0.2mm. This allowance is set to reserve machining allowance for subsequent semi-finish grinding and finish grinding processes. It ensures that enough material is removed to meet the final dimensional requirements, without increasing the difficulty and time cost of subsequent processing due to excessive allowance.

[0039] S1012: Measure the outer surface dimensions of bushing-type parts 1 after rough grinding. If the dimensional deviation exceeds the allowable range, the cause needs to be analyzed and the grinding machine parameters need to be adjusted appropriately. Grinding should be carried out again until the outer surface dimensions meet the preliminary processing requirements to ensure that a qualified processing foundation is provided for subsequent processes.

[0040] S102: Rough grinding of the inner surface;

[0041] S1021: Use rough grinding equipment (such as a universal grinder) to rough grind the inner surface. During the grinding process, by controlling the feed rate and stroke, the material is gradually removed and a basic shape is formed, so that the inner surface allowance reaches 0.1mm. This allowance is determined based on the accuracy requirements of the subsequent fine grinding process, which ensures that there is enough allowance to correct the size and shape during fine grinding, and that the processing efficiency and accuracy are not affected by excessive allowance.

[0042] S1022: Measure the inner surface dimensions and compare them with the preliminary machining requirements to check if the inner surface dimensions meet the requirements. If they do not meet the requirements, adjust the grinding machine parameters in time to correct them and ensure that the inner surface dimensions are within the tolerance range of the preliminary machining.

[0043] S103: Rough grinding of the end face;

[0044] S1031: Select a suitable end-face grinding tool to perform rough grinding on the end face of the bushing. Adjust the motion trajectory of the grinding machine table and the grinding parameters. During the grinding process, pay attention to maintaining the uniformity of the grinding force to ensure that the end face is flat. Control the grinding amount to ensure that the end face allowance is 0.1mm. This allowance provides space for subsequent fine grinding processes to correct the flatness and perpendicularity of the end face.

[0045] S1032: Check the flatness and perpendicularity of the end face. If they do not meet the requirements, continue to adjust the grinding machine parameters and grind until the flatness and perpendicularity of the end face meet the initial processing requirements.

[0046] S2: Aging treatment for bushing-type parts after rough grinding;

[0047] After rough grinding, the bushing-type part 1 is placed in an aging furnace. The aging temperature and time are set, and the aging treatment lasts for 24 hours to eliminate internal stress. The aging temperature is 120℃. Aging treatment improves the stability of the part. During the aging process, the process is monitored in real time to ensure its stability and achieve the desired effect of eliminating internal stress.

[0048] S3: A high-hardness wear-resistant layer 2 is provided on the outer surface of the bushing-type part 1;

[0049] S301: Install the bushing-type part 1 on the worktable of the laser cladding equipment, and precisely adjust the position of the bushing-type part 1 so that the center support ring on the outer surface of the bushing-type part 1 is aligned with the laser cladding head. Using tungsten steel powder as the wear-resistant metal material, a high-hardness wear-resistant layer 2 with a thickness of 0.5mm is deposited on the center support ring on the outer surface of the bushing-type part 1 through laser cladding technology. The high-hardness wear-resistant layer 2 consists of two layers spaced apart along the axial direction of the bushing-type part 1. The laser power of the laser cladding process is 6kW, the scanning speed is 1m / min, and the powder feed rate is 10g / min. The hardness of the prepared wear-resistant metal layer is tested to be HRC60.

[0050] The hardness of the high-hardness wear-resistant layer 2 was tested and found to be HRC60.

[0051] It should be noted that the position of the central support ring on the outer surface of the bushing part 1 refers to the corresponding position of the fulcrum 4 of the central frame 3 on the bushing part 1 when the bushing part 1 is subsequently installed on the central frame 3.

[0052] S302: A high-precision grinding machine is used to perform semi-finish grinding on the laser-clad area on the outer surface of the bushing part 1. During the grinding process, parameters such as the feed rate of the grinding machine are precisely controlled to achieve a roundness within 2μm. This precision requirement helps to improve the accuracy of the coating and ensure the rotational accuracy of the bushing part 1 during subsequent processing and use.

[0053] S4: Install the bushing-type part 1 on the center frame 3, and keep the support point 4 of the center frame 3 corresponding to the high hardness wear-resistant layer 2. Grind the inner surface and end face of the bushing-type part 1.

[0054] S401: Install the laser-clad bushing part 1 on the center frame 3, and keep the support point 4 of the center frame 3 corresponding to the high hardness wear-resistant layer 2. After adjusting the center frame 3 to align, fine grind the inner surface of the bushing part 1 to improve the inner surface accuracy. After fine grinding, measure the inner surface dimensions to ensure that the fine machining requirements are met.

[0055] S402: Perform fine grinding on the end face of bushing type part 1 to improve the end face accuracy. After fine grinding, check the flatness and perpendicularity of the end face to ensure that the fine machining requirements are met.

[0056] S5: Remove the high-hardness wear-resistant layer 2 from the outer surface of bushing-type parts 1;

[0057] The bushing is inserted onto the mandrel, and a universal cylindrical grinder is used to grind the high-hardness wear-resistant layer 2 on the outer surface of the laser-clad bushing until the high-hardness wear-resistant layer 2 is completely removed. During the grinding process, the grinding depth and feed rate are carefully controlled to avoid affecting the outer surface dimensions of the bushing part 1 itself.

[0058] S6: Finely grind the outer surface of bushing-type parts 1.

[0059] A high-precision cylindrical grinding machine is used for the final finishing of the outer surface. During the grinding process, various parameters of the grinding machine are precisely adjusted according to the required accuracy and surface roughness. Simultaneously, the outer surface dimensions and surface quality are monitored in real time to ensure machining accuracy. After finishing, a final measurement is performed to ensure that the outer surface dimensions and surface quality meet the standards.

[0060] The grinding process of this invention ensures uniform contact area and pressure distribution between the fulcrum 4 of the center support 3 and the outer surface of the bushing-type part 1 by precisely controlling the thickness and uniformity of the coating, thereby improving the rotational accuracy of the part. The coating thickness on the outer surface of the bushing-type part 1 after laser cladding can be adjusted as needed to ensure sufficient wear resistance and support strength. In addition, in the grinding process of this invention, the high-hardness wear-resistant layer 2 can also be retained according to subsequent processing or usage requirements.

[0061] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A grinding method for low-hardness bushing parts, wherein the low-hardness bushing parts refer to bushing parts with a hardness lower than HRC35, characterized in that, A high-hardness wear-resistant layer (2) is prepared on the outer surface of the bushing part (1). The bushing part (1) is mounted on the center frame (3) so that the support point (4) of the center frame (3) corresponds to the high-hardness wear-resistant layer (2). Then, grinding is performed. After grinding, the high-hardness wear-resistant layer (2) is removed. The high-hardness wear-resistant layer (2) is a metal layer with a hardness greater than HRC55. The high-hardness wear-resistant layer (2) is made by laser cladding of metal powder. The high-hardness wear-resistant layer (2) is annular and there are multiple high-hardness wear-resistant layers (2). Multiple high-hardness wear-resistant layers (2) are distributed at intervals along the axial direction of the bushing part (1).

2. The grinding method for low-hardness bushing-type parts according to claim 1, characterized in that, The metal powder is hard alloy powder or tungsten carbide powder.

3. The grinding method for low-hardness bushing-type parts according to claim 1, characterized in that, The thickness of the high-hardness wear-resistant layer (2) is 0.4-0.8 mm.

4. The grinding method for low-hardness bushing-type parts according to claim 1, characterized in that, Specifically, the following steps are included: S1: Rough grinding of the outer surface, inner surface and end face of bushing-type parts (1); S2: Aging treatment of bushing parts after rough grinding (1); S3: Prepare a high-hardness wear-resistant layer (2) on the outer surface of the bushing-type part (1); S4: Install the bushing part (1) on the center frame (3) and keep the support point (4) of the center frame (3) corresponding to the high hardness wear-resistant layer (2), and perform fine grinding on the inner surface and end face of the bushing part (1); S5: Remove the high-hardness wear-resistant layer (2); S6: Grind the outer surface of the bushing part (1).

5. A grinding method for low-hardness bushing-type parts according to claim 4, characterized in that, In step S1, when rough grinding the bushing type part (1), the outer surface allowance is 0.2mm, the inner surface allowance is 0.1mm, and the end face allowance is 0.1mm.

6. A grinding method for low-hardness bushing-type parts according to claim 4, characterized in that, In step S2, the time for aging processing is 24 hours.

7. A grinding method for low-hardness bushing-type parts according to claim 4, characterized in that, In step S3, the high-hardness wear-resistant layer (2) set on the outer surface of the bushing-type part (1) is semi-finished to make its roundness less than 2μm.

8. A grinding method for low-hardness bushing parts according to claim 4, characterized in that, In step S5, the mandrel is inserted into the bushing part (1), and the high-hardness wear-resistant layer (2) on the outer surface of the bushing part (1) is removed by grinding.

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