Manufacturing method of metal threaded lead screw with high strength and corrosion resistance

Abstract

The invention relates to the technical field of metal screw rod manufacturing, in particular to a manufacturing method of a metal threaded screw rod with high strength and corrosion resistance, which comprises the following steps: by taking a stainless steel bar as a raw material, firstly carrying out solution treatment on the bar; and then straightening, outer circle rough turning, aging treatment, center hole grinding and trimming, outer circle semi-finish turning, outer circle finish turning, thread rough turning, thread semi-finish turning and thread finish turning treatment are conducted, and a finished lead screw is obtained. The strength and corrosion resistance of the lead screw can be further improved through solution treatment, aging treatment and multiple times of heat treatment, residual stress in the machining process is eliminated, and the precision of the lead screw can be effectively improved through multiple times of size detection.

Description

Technical Field

[0001] This invention relates to the field of metal screw manufacturing technology, and in particular to a method for manufacturing a metal threaded screw with high strength and corrosion resistance. Background Technology

[0002] With the development of society, human beings are gradually accelerating their pace towards the deep sea and open ocean. Correspondingly, marine equipment is also showing a trend of development towards deeper and more distant waters. Screws (especially high-precision ball screws) are widely used in marine engineering, mainly due to their high precision, high load-bearing capacity, smooth movement and long service life. Stainless steel is widely used in screw manufacturing due to its good corrosion resistance, creep resistance and excellent ductility. However, in recent years, with the improvement of my country's comprehensive national strength, the requirements for the strength, corrosion resistance, wear resistance and ductility of stainless steel screws in the field of marine engineering have become increasingly higher.

[0003] Traditional methods for manufacturing stainless steel threaded rods often result in hydrogen embrittlement and thermal deformation during processing, leading to reduced strength, corrosion resistance, and precision, which limits their use in structural components. Therefore, it is necessary to provide a method for manufacturing metal threaded rods with high strength and corrosion resistance, which is of positive significance for improving my country's marine engineering. Summary of the Invention

[0004] The main objective of this invention is to provide a method for manufacturing a metal threaded rod with high strength and corrosion resistance, thereby improving the strength and corrosion resistance of stainless steel threaded rods.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for manufacturing a metal threaded screw with high strength and corrosion resistance includes the following steps: providing stainless steel bar raw material, wherein the chemical composition of the stainless steel bar raw material is as follows (by mass percentage): C≤0.03%, Cr: 17.0-19.0%, Ni: 14.0-15.0%, Mo: 2.25-3%, Mn≤2%, Si≤1%, P≤0.045%, S≤0.03%, Nb: 0.1-0.2%; W≤1-2%, Y: 0.01-0.02%, with the balance being Fe and unavoidable impurities;

[0007] A: Solution treatment: The stainless steel bar raw material is subjected to solution treatment to obtain solution-treated bars;

[0008] B: Straightening: Straightening the solid solution rod at room temperature;

[0009] C: Rough turning of the outer diameter: Mount the straightened bar on the lathe and ensure that the workpiece is firmly installed. Perform rough turning of the outer diameter and straighten it. After machining, measure the roundness, straightness and roughness of the bar. If the measurement results exceed the threshold, repeat C.

[0010] D: Aging treatment: After rough turning of the outer diameter, the bar is subjected to aging treatment at a temperature of 600-850℃ and a holding time of 4-10h.

[0011] E: Center hole finishing: The center hole of the aged bar is finished to obtain a drilled bar. The diameter of the drilled bar is 101-105% of the diameter of the bar in step D, and the positional deviation is ≤0.3mm.

[0012] F: Semi-finish turning of the outer diameter: The bar material after the center hole has been treated is semi-finish turned to obtain the bar material blank;

[0013] G: Finish turning of the outer diameter: The outer diameter of the bar billet is finished by finishing turning. After the machining is completed, the roundness, straightness and roughness of the bar are measured. If the measurement results exceed the threshold, G is repeated.

[0014] H: Rough threading: Rough threading is performed on the bar stock after the outer diameter has been finished, followed by stress-relieving heat treatment and dimensional inspection. If the dimensions are out of tolerance, straightening is performed at room temperature and step H is repeated.

[0015] I: Semi-finish thread cutting: Perform semi-finish thread cutting on the bar stock after rough threading and heat treatment, and then check the dimensions. If the dimensions are out of control, straighten the bar stock at room temperature and repeat step I.

[0016] J: Finish threading: The semi-finish threaded bar is subjected to finish threading. The finish threading process involves multiple grinding operations at a grinding speed of 4-8 μm / s. After the processing is completed, heat treatment is performed to obtain the finished screw.

[0017] Furthermore, the solution treatment temperature is 1000-1200℃, and the holding time is 0.5-7h.

[0018] Furthermore, the roundness of step C is ≤1.5mm, the straightness is ≤3mm, and the roughness is Ra≤1μm.

[0019] Furthermore, the roundness of step G is ≤1mm, the straightness is ≤2mm, and the roughness is Ra≤0.5μm.

[0020] Furthermore, the heating temperature for the stress-relieving heat treatment in step H is 1050-1150℃, and the time is 1-4h.

[0021] Furthermore, the heating temperature of the heat treatment in step J is 850-950℃, and the holding time is 1-3h.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention selects stainless steel bars with the following chemical composition by mass percentage: C≤0.03%, Cr: 17.0-19.0%, Ni: 14.0-15.0%, Mo: 2.25-3%, Mn≤2%, Si≤1%, P≤0.045%, S≤0.03%, Nb: 0.1-0.2%; W≤1-2%, Y: 0.01-0.02%, with the balance being Fe and unavoidable impurities. The higher Cr and Ni content effectively improves the corrosion resistance and hydrogen embrittlement resistance of stainless steel, while the small amounts of Nb and Y refine the grains and reduce impurities, and the small amount of W effectively improves the strength and corrosion resistance of the bars.

[0024] 2. This invention can further improve the strength and corrosion resistance of the finished lead screw by using solution treatment, aging treatment and multiple heat treatments, eliminate residual stress during processing, and effectively improve the accuracy of the lead screw through multiple dimensional inspections. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] This invention provides stainless steel bar raw materials with the following chemical composition by mass percentage: C ≤ 0.03%, Cr: 17.0-19.0%, Ni: 14.0-15.0%, Mo: 2.25-3%, Mn ≤ 2%, Si ≤ 1%, P ≤ 0.045%, S ≤ 0.03%, Nb: 0.1-0.2%; W ≤ 1-2%, Y: 0.01-0.02%, with the balance being Fe and unavoidable impurities. The stainless steel bars used in this invention contain high levels of Cr and Ni elements, which can... It can improve the corrosion resistance and hydrogen embrittlement resistance of stainless steel bars. By containing small amounts of Nb and Y elements, it can effectively refine the grains and improve corrosion resistance. At the same time, Y element can effectively reduce the amount of impurities in stainless steel and reduce the number of pitting corrosion sources, thus improving the corrosion resistance of stainless steel bars. A small amount of W can significantly improve the strength and wear resistance of stainless steel bars. Furthermore, due to the high melting point and high specific gravity of W, stainless steel bars can maintain high strength and stability under high temperature conditions and are not prone to creep and deformation.

[0028] Step A: Solution treatment is performed on the stainless steel bar raw material. The heating temperature is 1000-1200℃, and the temperature is held for 0.5-7 hours. Solution treatment can effectively improve the strength and corrosion resistance of the material, and at the same time create favorable conditions for subsequent aging treatment. The supersaturated solid solution obtained by solution treatment will re-precipitate fine and uniformly distributed strengthening phases during the subsequent aging treatment. These strengthening phases help to improve the strength and hardness of the lead screw, while maintaining good plasticity and toughness.

[0029] Step B: Straighten the solution-treated rod at room temperature. Since the rod will have slight bending or deformation after solution treatment, straightening can restore the rod to a straight state. At the same time, straightening helps to eliminate residual stress inside the solution-treated rod. The straightened rod is also easier to perform finishing processes such as grinding, thereby improving the accuracy of subsequent processing.

[0030] Step C: Rough turning of the outer diameter: Mount the straightened bar on the lathe and ensure that the workpiece is firmly installed. Perform rough turning of the outer diameter and straighten it. After machining, measure the roundness, straightness and roughness of the bar. If the measurement results exceed the threshold, repeat step C. The roundness of the bar is ≤1.5mm, the straightness is ≤3mm and the roughness is Ra≤1μm.

[0031] Step D: Aging treatment: The bar stock after rough turning of the outer diameter is subjected to aging treatment. The heating temperature is 600-850℃ and the holding time is 4-10h. Aging treatment can cause atomic diffusion and form a dispersed phase. These dispersed phases can improve the hardness and strength of the lead screw. At the same time, aging treatment can cause elements such as Cr and Mo to aggregate to the grain boundaries and form a metal oxide film with a certain thickness, thereby improving the corrosion resistance of the lead screw.

[0032] Step E: Grinding the center hole: Grinding the center hole of the aged bar to obtain a drilled bar. The diameter of the drilled bar is 101-105% of the diameter of the bar in Step D, and the positional deviation is ≤0.3mm.

[0033] Step F: Semi-finish turning of the outer diameter: The bar stock after the center hole has been machined is semi-finish turned to obtain the bar stock blank;

[0034] Step G: Finish turning the outer diameter: Finish turn the outer diameter of the bar blank. After the machining is completed, measure the roundness, straightness and roughness of the bar. If the measurement results exceed the threshold, repeat step E. The roundness of the bar is ≤1mm, the straightness is ≤2mm and the roughness is Ra≤0.5μm.

[0035] Step H: Rough threading: Rough threading is performed on the bar after the outer diameter has been finished, followed by stress relief heat treatment and dimensional inspection. If the dimensions are out of tolerance, straightening is performed at room temperature and step H is repeated. The heating temperature for stress relief heat treatment is 1050-1150℃ and the time is 1-4h.

[0036] Step I: Semi-finish thread cutting: Perform semi-finish thread cutting on the bar stock after rough threading and heat treatment, and then check the dimensions. If the dimensions are out of control, straighten the bar stock at room temperature and repeat step G.

[0037] Step J: Finish threading: The semi-finish threaded bar is finished by finishing threading. The finishing threading process involves multiple grinding operations at a grinding speed of 4-8 μm / s. After the processing is completed, heat treatment is performed at a heating temperature of 850-950℃ and a holding time of 1-3 hours to obtain the finished screw.

[0038] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for manufacturing a metal threaded screw with high strength and corrosion resistance, characterized in that: The following steps are involved: A stainless steel bar raw material is provided, wherein the chemical composition mass percentage of the stainless steel bar raw material is: C≤0.03%, Cr: 17.0-19.0%, Ni: 14.0-15.0%, Mo: 2.25-3%, Mn≤2%, Si≤1%, P≤0.045%, S≤0.03%, Nb: 0.1-0.2%; W≤1-2%, Y: 0.01-0.02% and the balance is Fe and unavoidable impurities; A: Solution treatment: performing solution treatment on the stainless steel bar raw material to obtain a solution bar; B: Straightening: straightening the solid solution rod at room temperature; C: Rough turning of the outer diameter: Install the straightened bar on the lathe and ensure that the workpiece is firmly installed. Rough turning of the outer diameter is performed and straightened. After the processing is completed, the roundness, straightness and roughness of the bar are measured. If the measurement result exceeds the threshold, repeat C; D: Aging treatment: After the rough turning of the outer circle is completed, the bar is subjected to aging treatment. The aging treatment temperature is 600-850℃ and the insulation time is 4-10h; E: grinding the center hole: grinding the center hole of the aging treated bar to obtain a punched bar, the diameter of which is 101-105% of the diameter of the bar in step D, and the position deviation is ≤0.3mm; F: Semi-finishing outer circle: The bar after the center hole treatment is semi-finishingly turned to obtain the bar blank; G: Finish turning the outer circle: Finish turning the outer circle of the bar blank. After the processing is completed, measure the roundness, straightness and roughness of the bar. If the measurement result exceeds the threshold, repeat G; H: Rough threading: Rough threading is performed on the bars after fine turning of the outer diameter, and stress relief heat treatment is performed and the size is inspected. If the size exceeds the limit, straightening is performed at room temperature and step H is repeated; I: Semi-finishing thread turning: semi-finishing thread turning is performed on the bar after rough thread turning and heat treatment, followed by dimensional inspection. If the size exceeds the limit, straighten it at room temperature and repeat step I; J: Finishing thread: The rod after semi-finishing thread processing is subjected to finish threading, wherein the finish threading is processed by multiple grinding processes at a grinding speed of 4-8 μm / s. After the processing is completed, heat treatment is performed to obtain a finished screw rod.

2. A method for manufacturing a metal threaded screw with high strength and corrosion resistance according to claim 1, characterized in that: The temperature of the solution treatment is 1000-1200° C., and the holding time is 0.5-7 hours.

3. A method for manufacturing a metal threaded screw with high strength and corrosion resistance according to claim 1, characterized in that: The roundness of the C step is ≤1.5mm, the straightness is ≤3mm, and the roughness is Ra≤1μm.

4. A method for manufacturing a metal threaded screw with high strength and corrosion resistance according to claim 1, characterized in that: The roundness of the G step is ≤1 mm, the straightness is ≤2 mm, and the roughness is Ra ≤0.5 μm.

5. The method for manufacturing a metal threaded screw with high strength and corrosion resistance according to claim 1, characterized in that: The heating temperature of the stress relief heat treatment in step H is 1050-1150° C. and the time is 1-4 hours.

6. A method for manufacturing a metal threaded screw with high strength and corrosion resistance according to claim 1, characterized in that: The heating temperature of the heat treatment in step J is 850-950° C., and the insulation time is 1-3 hours.