Hexagon nut and preparation method thereof

Abstract

The invention provides a hexagon nut and a preparation method thereof, and relates to the technical field of nuts. The hexagonal nut comprises the following chemical components in percentage by mass: less than or equal to 0.03% of C; si is less than or equal to 0.01%; mn: 0.75 to 1.0%; p is less than or equal to 0.03%; s is less than or equal to 0.01%; 24 to 26 percent of Cr; 3 to 4 percent of Mo; 4.5 to 6.5 percent of Ni; 0.20% to 0.30% of N; 0.08% to 0.20% of W; 0.5 to 1.0 percent of Cu; and the balance of Fe and inevitable impurities. The hexagon nut prepared through the method has excellent mechanical performance, and the requirements of customers and the market are met.

Description

Technical Field

[0001] The present invention relates to the technical field of nuts, and particularly to a hexagonal nut and a preparation method thereof. Background Art

[0002] When manufacturing hexagonal nuts, generally, round bars are forged into shape after heating to strengthen their mechanical properties. Subsequently, heat treatment is carried out, sandblasting is used to remove the surface oxide scale, and then machining is performed to complete the product. The manufacturing cost is high, the cycle is long, and the labor input is large. Summary of the Invention

[0003] Based on the technical problems existing in the background art, the present invention provides a hexagonal nut and a preparation method thereof.

[0004] A hexagonal nut provided by the present invention includes the following chemical components by mass percentage: C≤0.03%; Si≤0.01%; Mn: 0.75 - 1.0%; P≤0.03%; S≤0.01%; Cr: 24 - 26%; Mo: 3 - 4%; Ni: 4.5 - 6.5%; N: 0.20 - 0.30%; W: 0.08 - 0.20%; Cu: 0.5 - 1.0%; the balance being Fe and unavoidable impurities.

[0005] A preparation method of a hexagonal nut provided by the present invention includes the following steps:

[0006] S1. Cutting a hexagonal bar raw material to obtain a nut blank;

[0007] S2. Subjecting the nut blank to extrusion treatment to obtain an extruded nut;

[0008] S3. Chamfering the inner hole and tapping the extruded nut to obtain the product.

[0009] Preferably, in S1, the hexagonal bar raw material includes the following chemical components by mass percentage: C≤0.03%; Si≤0.01%; Mn: 0.75 - 1.0%; P≤0.03%; S≤0.01%; Cr: 24 - 26%; Mo: 3 - 4%; Ni: 4.5 - 6.5%; N: 0.20 - 0.30%; W: 0.08 - 0.20%; Cu: 0.5 - 1.0%; the balance being Fe and unavoidable impurities.

[0010] Controlling the chemical components of the hexagonal bar raw material within a certain range is helpful for subsequent processing and ensuring its mechanical properties.

[0011] Preferably, in S1, an extrusion allowance is reserved for the nut blank, and the extrusion allowance is 0.6 mm.

[0012] Preferably, in the above-mentioned S2, the extrusion process includes assembling the extrusion die on the press, and then placing the nut blank in the cavity of the press die for extrusion.

[0013] More preferably, the extrusion punch of the press die needs to be subjected to PVD strengthening treatment and lubrication protection throughout the process.

[0014] More preferably, the specific PVD strengthening treatment includes: after the extrusion punch is cleaned by argon ion, the vacuum degree is adjusted to 0.1 - 6 Pa, the sample bias voltage is -40 - -175 V, nitrogen is introduced, the air pressure is 2.2 - 5 Pa, the sample temperature is controlled at 400 - 485 °C, the target current is 70 - 115 A, and deposition is carried out for 1 - 7 h to obtain the product.

[0015] More preferably, the target is a Cr target, a Ti target or an AlCr target.

[0016] More preferably, the lubrication specifically includes: applying lubricating oil on the surface of the extrusion punch with a brush.

[0017] More preferably, the extrusion pressure of the press is 10 - 15 MPa.

[0018] Preferably, in the above-mentioned S3, the chamfer is a 1.8×60° chamfer.

[0019] The beneficial effects of the present invention are as follows:

[0020] The preparation method of the hexagon nut provided by the present invention directly processes with a hexagon bar raw material, removing the forging, heat treatment and sandblasting cleaning processes from the process; the cost of this part will be directly saved. In addition, in terms of the manufacturing personnel configuration, three people are required for the forging group, while only one person is required for extrusion, saving two people. The proof load of the hexagon nut provided by the present invention reaches 602.3 kN. The present invention adopts cold extrusion of the inner hole of the hexagon bar to strengthen the inner wall hardness and improve its mechanical properties, meeting the requirements of customers and the market. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the extrusion process proposed by the present invention. Detailed Embodiments

[0022] The technical solutions of the present invention will be described in detail through specific embodiments.

[0023] The materials, reagents, etc. used in the following embodiments and comparative examples can be obtained from commercial channels without special instructions.

[0024] Embodiment 1

[0025] A preparation method of a hexagon nut, comprising the following steps:

[0026] S1. The hexagonal bar raw material includes the following chemical components by mass percentage: C: 0.03%; Si: 0.01%; Mn: 0.8%; P: 0.02%; S: 0.01%; Cr: 24%; Mo: 3%; Ni: 5%; N: 0.20%; W: 0.10%; Cu: 0.8%; the balance is Fe and unavoidable impurities. Cut the hexagonal bar raw material to obtain nut blanks, process them according to the M27 standard, and leave an extrusion allowance of 0.6 mm for the thread bottom hole.

[0027] S2. Place the nut blanks in the cavity of the press die for extrusion treatment to obtain the extruded nuts. The extrusion treatment includes assembling the extrusion die on the press, and then placing the nut blanks in the cavity of the press die for extrusion at a pressure of 12 MPa. The inner diameter of the obtained nuts is φ24.1±0.1. The extrusion punch of the press die needs to be subjected to PVD strengthening treatment, and lubricating oil is applied to the surface of the extrusion punch for full lubrication protection throughout the process. The specific PVD strengthening treatment includes: after argon ion cleaning the extrusion punch, adjusting the vacuum degree to 3 Pa, the sample bias voltage to -80 V, introducing nitrogen with a gas pressure of 3 Pa, controlling the sample temperature at 460 °C, using a Cr target as the target material, a target current of 90 A, and depositing for 4 h to obtain the desired result.

[0028] S3. Chamfer the inner hole of the extruded nuts at 1.8×60° on a lathe and perform tapping on a tapping machine to obtain the finished product.

[0029] Example 2

[0030] A method for preparing a hexagonal nut, comprising the following steps:

[0031] S1. The hexagonal bar raw material includes the following chemical components by mass percentage: C: 0.03%; Si: 0.01%; Mn: 0.75%; P: 0.02%; S: 0.01%; Cr: 25%; Mo: 3%; Ni: 6%; N: 0.20%; W: 0.01%; Cu: 0.8%; the balance is Fe and unavoidable impurities. Cut the hexagonal bar raw material to obtain nut blanks, process them according to the M27 standard, and leave an extrusion allowance of 0.6 mm for the thread bottom hole.

[0032] S2. Place the nut blank in the cavity of the press die for extrusion to obtain the extruded nut. The extrusion process includes assembling the extrusion die on the press, and then placing the nut blank in the cavity of the press die for extrusion at a pressure of 12 MPa. The inner diameter of the obtained nut is φ24.1 ± 0.1. The extrusion punch of the press die needs to be subjected to PVD strengthening treatment, and lubricating oil is applied to the surface of the extrusion punch for full lubrication protection throughout the process. The specific PVD strengthening treatment includes: after the extrusion punch is subjected to argon ion cleaning, the vacuum degree is adjusted to 3 Pa, the sample bias voltage is -80 V, nitrogen is introduced, the gas pressure is 3 Pa, the sample temperature is controlled at 460 °C, the target material is AlCr target, the target current is 90 A, and deposition is carried out for 4 h to obtain the required result.

[0033] S3. Chamfer the inner hole of the extruded nut by 1.8 × 60° on the lathe and perform tapping on the tapping machine to obtain the final product.

[0034] Example 3

[0035] A method for preparing a hexagonal nut, comprising the following steps:

[0036] S1. The hexagonal bar raw material includes the following chemical components by mass percentage: C: 0.03%; Si: 0.01%; Mn: 0.75%; P: 0.02%; S: 0.01%; Cr: 26%; Mo: 3.5%; Ni: 6.5%; N: 0.20%; W: 0.08%; Cu: 0.7%; the rest are Fe and inevitable impurities. Cut the hexagonal bar raw material to obtain the nut blank, process it according to the M27 standard, and reserve an extrusion allowance of 0.6 mm for the thread bottom hole.

[0037] S2. Place the nut blank in the cavity of the press die for extrusion to obtain the extruded nut. The extrusion process includes assembling the extrusion die on the press, and then placing the nut blank in the cavity of the press die for extrusion at a pressure of 12.5 MPa. The inner diameter of the obtained nut is φ24.1 ± 0.1. The extrusion punch of the press die needs to be subjected to PVD strengthening treatment, and lubricating oil is applied to the surface of the extrusion punch for full lubrication protection throughout the process. The specific PVD strengthening treatment includes: after the extrusion punch is subjected to argon ion cleaning, the vacuum degree is adjusted to 3 Pa, the sample bias voltage is -80 V, nitrogen is introduced, the gas pressure is 3 Pa, the sample temperature is controlled at 470 °C, the target material is AlCr target, the target current is 90 A, and deposition is carried out for 4 h to obtain the required result.

[0038] S3. Chamfer the inner hole of the extruded nut by 1.8 × 60° on the lathe and perform tapping on the tapping machine to obtain the final product.

[0039] Perform performance inspection, holding test on the obtained hexagonal nut, and complete the final dimension inspection. After passing, it is packaged and stored in the warehouse. The test results are shown in Table 1.

[0040] Table 1

[0041] Project Inner Wall Hardness / HV Guaranteed Load / kN Qualified Rate of Dimension Inspection / % Example 1 285 553.4 90 Example 2 290 580.2 95 Example 3 310 602.3 98

[0042] As can be seen from the data in Table 1, the hexagonal nuts prepared by the present invention have high inner wall hardness, guaranteed load, and qualified rate of dimension inspection.

[0043] In summary, the hexagonal nuts prepared by the present invention have excellent mechanical properties and meet the requirements of customers and the market.

[0044] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A hexagonal nut comprising the following chemical components by mass percentage: C≤0.03%; Si≤0.01%; Mn: 0.75-1.0%; P≤0.03%; S≤0.01%; Cr: 24-26%; Mo: 3-4%; Ni: 4.5-6.5%; N: 0.20-0.30%; W: 0.08-0.20%; Cu: 0.5-1.0%; the rest is Fe and unavoidable impurities.

2. A method for preparing the hexagonal nut according to claim 1, characterized in that: The following steps are involved: S1, cutting the hexagonal bar raw material to obtain a nut blank; S2, extruding the nut blank to obtain an extruded nut; S3. Chamfer and tap the inner hole of the extruded nut to obtain the product.

3. The preparation method according to claim 2, characterized in that: In the S1, the hexagonal rod raw material includes the following chemical components in mass percentage: C≤0.03%; Si≤0.01%; Mn: 0.75-1.0%; P≤0.03%; S≤0.01%; Cr: 24-26%; Mo: 3-4%; Ni: 4.5-6.5%; N: 0.20-0.30%; W: 0.08-0.20%; Cu: 0.5-1.0%; the rest is Fe and unavoidable impurities.

4. The preparation method according to claim 2, characterized in that: In the S1, an extrusion margin is reserved for the nut blank, and the extrusion margin is 0.6 mm.

5. The preparation method according to claim 2, characterized in that: In the above-mentioned S2, the extrusion process includes assembling the extrusion die on a press, and then placing the nut blank in the die cavity of the press for extrusion.

6. The preparation method according to claim 5, characterized in that: The extrusion punch of the press die needs to be PVD strengthened and lubricated throughout the process.

7. The preparation method according to claim 5, characterized in that: The extrusion pressure of the press is 10-15 MPa.

8. The preparation method according to claim 2, characterized in that The chamfer is 1.8×60° chamfer.

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