A high-hardness mandrel machining process

Abstract

The application relates to the technical field of manufacturing processes, and provides a high-hardness mandrel machining process, which comprises the following steps: S1, first straightening of a blank, so that the straightness is less than or equal to 0.2; S2, rough turning of the blank, so that the blank reaches the design drawing standard; S3, quenching and tempering heat treatment of the rough-turned blank to HRC 38-42; S4, second straightening of the blank, so that the straightness is less than or equal to 0.2; S5, grinding of the blank, so that the blank is ground into a mandrel, the double-edge allowance of the outer circle of the mandrel is 0.35-0.45; S6, third straightening of the blank, so that the straightness is less than or equal to 0.2; S7, rough and fine knurling of key A on the mandrel, so that the mandrel reaches the design drawing standard; S8, laser quenching of the outer surface of the key A, so that the tooth surface hardness of the key A is HRC 45-50, the quenching depth is 0.6-1 mm, and the tooth surface deformation is controlled to be less than or equal to 0.1 in the length direction of the tooth surface; S9, laser quenching of the outer circular surface of the mandrel, so that the surface hardness of the mandrel is HRC 50-55, and the quenching depth is 1.2-1.5 mm; and S10, cooling treatment of the mandrel.

Description

Technical Field

[0001] This invention relates to the field of manufacturing technology, specifically to a high-hardness mandrel machining process. Background Technology

[0002] Mandrels have applications in many fields, such as automotive parts, office automation parts, home appliance parts, and power tool parts. A mandrel is a mechanical part that supports rotating parts and rotates with them to transmit motion, torque, or bending moment. It is generally a round metal rod, and different sections can have different diameters. The rotating parts in a machine are mounted on the mandrel.

[0003] As a transmission component, the mandrel needs to possess a certain degree of hardness to prevent breakage. Existing mandrels typically undergo hard chrome plating to improve surface hardness and wear resistance. However, hard chrome plating has the following drawbacks: 1. High cost, and requires multiple processing steps after plating. 2. Limited hardness effect; the hard chrome plating layer is thin, typically only about 0.05-0.15 mm. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a high-hardness mandrel processing technology that can greatly improve the surface hardness and wear resistance of the mandrel, while keeping the cost low.

[0005] This invention provides a high-hardness mandrel machining process, comprising the following steps:

[0006] S1. Perform the first straightening of the blank to ensure its straightness is ≤0.2;

[0007] S2. Roughly turn the blank to meet the design drawing standards;

[0008] S3. The blank after rough turning is subjected to quenching and tempering heat treatment to HRC38-42;

[0009] S4. Perform a second straightening on the blank to make its straightness ≤ 0.2;

[0010] S5. Grind the blank to form a mandrel, with a margin of 0.35-0.45 on both sides of the outer diameter of the mandrel;

[0011] S6. Perform a third straightening on the blank to make its straightness ≤ 0.2;

[0012] S7. Apply rough and fine knurling A to the mandrel to meet the design drawing standards;

[0013] S8. Laser harden the outer surface of spline A so that the hardness of the tooth surface of spline A is HRC45-50, the hardening depth is 0.6-1mm, and the tooth surface deformation is controlled within 0.1mm in the length direction of the tooth surface.

[0014] S9. Laser harden the outer circular surface of the mandrel to make the surface hardness of the mandrel HRC50-55 and the hardening depth 1.2-1.5mm.

[0015] S10, Cooling treatment of the mandrel.

[0016] Furthermore, before the blank is straightened for the second time, the blank is subjected to ultrasonic testing to select blanks without cracks and qualified blanks to enter the next process.

[0017] Furthermore, after the blank is straightened a second time, a 50mm long test piece is cut from each end of the blank, and the test pieces are subjected to metallographic analysis. The hardness data, model data and specification data of the test pieces are then archived.

[0018] Furthermore, it also includes S11, precision machining of the outer circle of the mandrel, so that its upper deviation is 0mm and its lower deviation is 0.063mm.

[0019] Furthermore, it also includes S12, performing deburring and blunting treatments on the surface of the mandrel.

[0020] Furthermore, it also includes S13, performing a fourth straightening of the blank to ensure its straightness is ≤0.2 and its runout is ≤

[0021] Furthermore, after step S5, the outer circle of the mandrel is not allowed to be damaged.

[0022] Beneficial Effects: This invention provides a high-hardness mandrel machining process. Before grinding the blank into a mandrel, a margin of 0.35-0.45mm is left on both sides of the outer diameter of the mandrel. Then, the spline A surface and the mandrel surface are subjected to laser hardening treatment successively. After surface laser hardening, the surface layer requires approximately 40J / mm² of energy, resulting in a significant increase in hardness. The surface layer has refined grains, improving the wear resistance of the mandrel. The high surface hardness, coupled with the reduced hardness in the transition zone, gives the mandrel bearing load-bearing surface high wear resistance and impact resistance, increasing its service life by approximately double. Furthermore, laser hardening is more cost-effective than electroplating hard chrome. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0025] like Figure 1 As shown, the present invention provides a high-hardness mandrel machining process, including the following steps:

[0026] S1. Cut the blank according to its dimensions and straighten it for the first time to make its straightness ≤0.2.

[0027] S2. Roughly machine the blank to meet the design drawing standards.

[0028] S3. Perform quenching and tempering heat treatment on the rough-turned blank to HRC38-42.

[0029] S4. Perform a second straightening of the blank to ensure its straightness is ≤0.2.

[0030] S5. Grind the blank to form a mandrel. The outer diameter of the mandrel is: The mandrel has a double-sided allowance of 0.35-0.45 on its outer diameter. This double-sided allowance is used for post-quenching machining.

[0031] S6. Perform a third straightening of the blank to ensure its straightness is ≤0.2.

[0032] S7. Apply rough and fine knurling to key A on the mandrel to meet the design drawing standards (test knurling must be performed before further processing).

[0033] S8. Laser harden the outer surface of spline A to achieve a tooth surface hardness of HRC45-50, a hardening depth of 0.6-1mm, and control the tooth surface deformation within 0.1mm along the tooth surface length. Perform a passability check using a standard gauge.

[0034] S9. Laser hardening of the outer cylindrical surface of the mandrel to achieve a surface hardness of HRC50-55 and a hardening depth of 1.2-1.5mm.

[0035] S10. Mandrel Cooling Treatment. Before shipment, inspect the mandrel to ensure its dimensions meet design requirements and its appearance is good (free from rust, dents, burrs, iron filings, etc.). Then, perform detailed finishing, cleaning, oiling, wrapping with oil paper, covering with wire mesh, and packing into a wooden crate to prevent damage.

[0036] Before grinding the blank into a mandrel, this process leaves a margin of 0.35-0.45 on both sides of the outer diameter of the mandrel. Then, the spline A surface and the mandrel surface are laser hardened one after the other.

[0037] The advantages of laser hardening are: 1. Laser surface hardening requires approximately 40 J / mm² of energy for the mandrel surface layer, significantly increasing hardness. 2. After laser surface hardening, the mandrel surface layer has refined grains, improving wear resistance. 3. After laser surface hardening, the surface layer has high hardness, while the transition zone has reduced hardness, resulting in higher wear resistance and impact resistance on the mandrel bearing surface, approximately doubling the mandrel's service life.

[0038] In addition, the laser hardening process used in this procedure is less expensive than traditional electroplating hard chrome.

[0039] In one embodiment, before the second straightening of the blank, the blank is first subjected to ultrasonic testing, and blanks without cracks and qualified are selected to proceed to the next process. Qualified blanks are recorded and archived for future reference.

[0040] In one embodiment, after the blank is straightened for the second time, a 50mm long test piece is cut from each end of the blank, and metallographic analysis is performed on the test pieces. The hardness data, model data, and specification data of the test pieces are archived for easy retrieval later.

[0041] In one embodiment, the method further includes S11, precision machining of the outer circle of the mandrel to make its upper deviation 0mm and lower deviation 0.063mm, so that the dimensions of the mandrel meet the design requirements.

[0042] In one embodiment, the method further includes S12, performing deburring and blunting treatments on the surface of the mandrel to improve the surface smoothness of the mandrel and facilitate installation and use.

[0043] In one embodiment, the method further includes S13, performing a fourth straightening of the blank to ensure that its straightness is ≤0.2 and its runout is ≤

[0044] In one embodiment, the outer circle of the mandrel is not allowed to be damaged after step S5.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0046] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-hardness mandrel machining process, characterized in that: Includes the following steps: S1. Perform the first straightening of the blank to ensure its straightness is ≤0.2; S2. Roughly turn the blank to meet the design drawing standards; S3. The blank after rough turning is subjected to quenching and tempering heat treatment to HRC38-42; S4. Perform a second straightening on the blank to make its straightness ≤ 0.2; S5. Grind the blank to form a mandrel, with a margin of 0.35-0.45 on both sides of the outer diameter of the mandrel; S6. Perform a third straightening on the blank to make its straightness ≤ 0.2; S7. Apply rough and fine knurling A to the mandrel to meet the design drawing standards; S8. Laser harden the outer surface of spline A so that the hardness of the tooth surface of spline A is HRC45-50, the hardening depth is 0.6-1mm, and the tooth surface deformation is controlled within 0.1mm in the length direction of the tooth surface. S9. Laser harden the outer circular surface of the mandrel to make the surface hardness of the mandrel HRC50-55 and the hardening depth 1.2-1.5mm. S10, Cooling treatment of the mandrel.

2. The high-hardness mandrel machining process according to claim 1, characterized in that: Before the blank is straightened for the second time, it is first subjected to ultrasonic testing to select blanks without cracks and qualified blanks to enter the next process.

3. The high-hardness mandrel machining process according to claim 2, characterized in that: After the blank is straightened for the second time, a 50mm long test piece is cut from each end of the blank, and the test piece is subjected to metallographic analysis. The hardness data, model data and specification data of the test piece are archived.

4. The high-hardness mandrel machining process according to claim 1, characterized in that: It also includes S11, precision machining of the outer circle of the mandrel, so that its upper deviation is 0mm and its lower deviation is 0.063mm.

5. The high-hardness mandrel machining process according to claim 1, characterized in that: It also includes S12, which involves deburring and blunting the surface of the mandrel.

6. The high-hardness mandrel machining process according to claim 1, characterized in that: It also includes S13, performing a fourth straightening of the blank to make its straightness ≤0.

2.

7. The high-hardness mandrel machining process according to claim 1, characterized in that: After step S5, the outer circle of the mandrel must not be damaged.

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