A method for improving the production control of the degree of bending of a steering gear nut steel

Abstract

The application discloses a production control method for improving the bending degree of steering gear nut steel, wherein 1) the heating temperature is optimized, the heating furnace step beam is advanced at 110s / step in the production process, the uniform heating of the steering gear nut steel blank in the heating furnace is ensured, and the temperature fluctuation of a single thermocouple is less than or equal to 15 DEG C; 2) the open rolling temperature is controlled to be 980 DEG C-1020 DEG C, and the speed of the first rolling mill is reduced to 0.48 m / s; 3) the 3# and 4# water tanks are used and the water tank booster pumps are closed during rolling, the pressure of the 3# and 4# water tanks is kept at 6.5 Bar, and the 5# / 6# / 7# water tanks are all offline; and 4) the heat preservation cover is abandoned on the cooling bed, the length of the double-length on the cooling bed is set to be 82m-90m, and the cooling bed moves once in 22s with 1 tooth and 1 motion. Through the control of the rolling temperature and the cooling temperature and the sawing temperature after rolling, the flatness of the nut steel is effectively improved, the straightening process is omitted, the production cost is reduced, and the delivery speed is improved.

Description

Technical Field

[0001] This invention relates to the field of steering gear nuts, and more particularly to a production control method for improving the bending degree of steering gear nuts. Background Technology

[0002] Steering gear nuts are important components in automotive transmissions, with a large market demand. The steel used for these nuts has high requirements for surface quality, fatigue performance, and straightness. The steel used for steering gear nuts has a high content of alloys such as Cr, Mo, and Mn, requiring high-temperature rolling. After rolling, uneven cooling rates during the cooling bed and sawing processes often result in bending, necessitating repeated straightening to ensure straightness. Further processing, including flaw detection and packaging, not only increases processing costs but also adds approximately 15 days to the delivery time.

[0003] Therefore, it is necessary to develop new production control methods to improve flatness, reduce production costs, and increase delivery speed. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings and defects of existing technologies, this invention provides a production control method for improving the curvature of steering gear nut steel. By controlling the rolling temperature, cooling temperature, and post-rolling sawing temperature, the straightness of the nut steel is effectively improved, eliminating the straightening process, reducing production costs, and increasing delivery speed.

[0005] Technical solution: The present invention provides a production control method for improving the bending degree of steel used in steering gear nuts, characterized by comprising the following steps:

[0006] 1) Optimize heating temperature. During the production process, the walking beam of the heating furnace advances at 110s / step to ensure that the steel billet for the steering gear nut is heated evenly in the heating furnace, and the temperature fluctuation of a single thermocouple is ≤15℃.

[0007] 2) The initial rolling temperature is controlled at 980℃-1020℃, and the speed of the four primary rolling mills is reduced to 0.48m / s;

[0008] 3) Use water tanks #3 and #4 during rolling and turn off the water tank booster pumps. Maintain the pressure of water tanks #3 and #4 at 6.5 Bar. All water tanks #5, #6, and #7 should be taken offline.

[0009] 4) The insulation cover of the cooling bed is abandoned. The length of the upper cooling bed is set at 82m-90m. The cooling bed moves once per tooth and moves once every 22 seconds to control the movement rhythm and ensure that the rolled material is cooled slowly on the cooling bed.

[0010] 5) When the time for supporting the steel on the cooling bed is less than 1 minute and the sawing temperature is less than 150℃, the steel should be sawed. After it comes off the line, it should be placed in a slow cooling pit for slow cooling for more than 24 hours.

[0011] The steering gear lead screw steel comprises the following components in the indicated mass percentages: C: 0.48%-0.67%, Mn: 0.66%-0.82%, Si: 0.28%-0.46%, Mo: 0.14%-0.22%, Cr: 0.95%-1.12%, Ni≤0.15%, Cu≤0.20%, P+S<0.10%, and Fe balance.

[0012] In step 2), the rolling temperature is controlled at 1000℃.

[0013] The steering gear nut steel is a round steel with a diameter of Φ30mm-60mm.

[0014] The steering gear screw nut steel is made by heating a 320mm×480mm cross-section billet smelted in an electric furnace to 1240℃, rolling it into a 180mm×180mm×11000mm billet, and then heating and rolling it into steering gear screw nut steel with a diameter of Φ30mm-60mm.

[0015] The steel used for the steering gear nut is rolled using an online heating furnace, high-pressure water descaling, 23 alternating horizontal and vertical short stress line rolling mills, 4 three-roll KOCKS rolling mills, 5 flying shears, and 7 online controlled cooling water tanks. An insulation cover is installed above the cooling bed.

[0016] In step 1), when optimizing the heating temperature, the preheating temperature is controlled to be ≤800℃.

[0017] In step 1), when optimizing the heating temperature, the heating temperature of the first heating stage is controlled to be ≤950℃, and the heating temperature of the second heating stage is controlled to be 1020℃-1100℃.

[0018] In step 1), when optimizing the heating temperature, the heating temperature of the first stage of heat equalization is controlled at 1080℃-1140℃, and the heating temperature of the second stage of heat equalization is controlled at 1080℃-1120℃.

[0019] In step 3), the rolling process is carried out at a temperature of 910℃-950℃ to prevent the precipitation of proeutectoid ferrite and to ensure that the rolling is performed in the single-phase region.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention improves the straightness of round steel by low-temperature rolling + controlled rolling and cooling, solving the problem of bending of steel for Φ30mm-60mm steering gear nut; by controlling the rolling temperature, cooling temperature, and post-rolling sawing temperature, the straightness of the steel for the nut is effectively improved, eliminating the straightening process, reducing production costs, and increasing delivery speed.

[0021] Testing revealed that over 99.00% of the steel used for steering gear nuts had a straightness within 0.25%. This invention can save 225 yuan per ton in straightening costs. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0023] The steering gear nut steel of the present invention comprises the following components in the following mass percentages: C: 0.48%-0.67%, Mn: 0.66%-0.82%, Si: 0.28%-0.46%, Mo: 0.14%-0.22%, Cr: 0.95%-1.12%, Ni≤0.15%, Cu≤0.20%, P+S<0.10%, and Fe balance.

[0024] The steering gear nut steel of this invention is produced by heating 320mm×480mm cross-section billets smelted in an electric furnace to 1240℃ for roughing and rolling into 180mm×180mm×11000mm billets, and then heating and rolling them into steering gear nut steel with a diameter of Φ30mm-60mm. During rolling, an online heating furnace, high-pressure water descaling, 23 alternating horizontal and vertical short stress line rolling mills, 4 three-roll KOCKS rolling mills, 5 flying shears, and 7 online controlled cooling water tanks are configured, with an insulation cover equipment above the cooling bed.

[0025] The production control method for improving the bending degree of steering gear nut steel of the present invention includes the following steps:

[0026] 1) Optimize heating temperature. During production, the walking beam of the heating furnace advances at a rate of 110 seconds per step to ensure uniform heating of the steel billet used for the steering gear nut in the heating furnace, with individual thermocouple temperature fluctuations ≤15℃. When optimizing the heating temperature, control the preheating section temperature ≤800℃; control the first heating stage temperature ≤950℃; control the second heating stage temperature at 1020℃-1100℃; control the first soaking stage temperature at 1080℃-1140℃; and control the second soaking stage temperature at 1080℃-1120℃.

[0027]

[0028] 2) The initial rolling temperature is controlled at 980℃-1020℃, and the speed of the four primary rolling mills is reduced to 0.48m / s; so that the intermediate billet can form a hard shell through deformation.

[0029] 3) Use water tanks #3 and #4 during rolling and turn off the water tank booster pump. Maintain the pressure of water tanks #3 and #4 at 6.5 Bar. Perform weak water penetration before controlled rolling to ensure that the inlet sizing temperature is between 910℃ and 950℃ to avoid the precipitation of proeutectoid ferrite. Rolling is carried out in the single-phase region. All water tanks #5, #6, and #7 are taken offline.

[0030] 4) The insulation cover of the cooling bed is abandoned. The length of the upper cooling bed is set at 82m-90m. The cooling bed moves once per tooth and moves once every 22 seconds to control the movement rhythm and ensure that the rolled material is cooled slowly on the cooling bed.

[0031] 5) When the time for supporting the steel on the cooling bed is less than 1 minute and the sawing temperature is less than 150℃, the steel should be sawed. After it comes off the line, it should be placed in a slow cooling pit for slow cooling for more than 24 hours.

[0032] This invention improves the straightness of round steel by low-temperature rolling and controlled rolling and cooling, solving the problem of bending of steel used for steering gear nuts with diameters of Φ30mm-60mm. By controlling the rolling temperature, cooling temperature, and post-rolling sawing temperature, the straightness of the steel used for steering gear nuts is effectively improved, eliminating the straightening process, reducing production costs, and increasing delivery speed.

[0033] Testing revealed that over 99.00% of the steel used for steering gear nuts had a straightness within 0.25%. This invention can save 225 yuan per ton in straightening costs.

Claims

1. A production control method for improving the bending degree of steel used in steering gear nuts, characterized in that: Includes the following steps: 1) Optimize heating temperature. During production, the walking beam of the heating furnace advances at 110 seconds per step to ensure uniform heating of the steel billet for the steering gear nut in the heating furnace, with individual thermocouple temperature fluctuations ≤15℃. When optimizing the heating temperature, control the preheating section heating temperature ≤800℃; control the first heating section heating temperature ≤950℃; control the second heating section heating temperature at 1020℃-1100℃; control the first homogenization heating temperature at 1080℃-1140℃; and control the second homogenization heating temperature at 1080℃-1120℃. 2) The initial rolling temperature is controlled at 980℃-1020℃, and the speed of the four primary rolling mills is reduced to 0.48m / s; 3) Use water tanks #3 and #4 during rolling and turn off the water tank booster pumps. Maintain the pressure of water tanks #3 and #4 at 6.5 Bar. All water tanks #5, #6, and #7 should be taken offline. 4) The insulation cover of the cooling bed is abandoned. The length of the upper cooling bed is set at 82m-90m. The cooling bed moves once per tooth and moves once every 22 seconds to control the movement rhythm and ensure that the rolled material is cooled slowly on the cooling bed. 5) When the time for supporting the steel on the cooling bed is less than 1 minute and the sawing temperature is less than 150℃, the steel should be sawed. After it comes off the line, it should be placed in a slow cooling pit for slow cooling for more than 24 hours.

2. The production control method for improving the bending degree of steering gear nut steel according to claim 1, characterized in that: The steering gear lead screw steel comprises the following components in the indicated mass percentages: C: 0.48%-0.67%, Mn: 0.66%-0.82%, Si: 0.28%-0.46%, Mo: 0.14%-0.22%, Cr: 0.95%-1.12%, Ni≤0.15%, Cu≤0.20%, P+S<0.10%, Fe balance.

3. The production control method for improving the bending degree of steering gear nut steel according to claim 1, characterized in that: In step 2), the rolling temperature is controlled at 1000℃.

4. The production control method for improving the bending degree of steering gear nut steel according to claim 1, characterized in that: The steering gear nut is made of round steel with a diameter of Φ30mm-60mm.

5. The production control method for improving the bending degree of steering gear nut steel according to claim 4, characterized in that: The steering gear screw nut steel is made by heating a 320mm×480mm cross-section billet smelted in an electric furnace to 1240℃, rolling it into a 180mm×180mm×11000mm billet, and then heating and rolling it into steering gear screw nut steel with a diameter of Φ30mm-60mm.

6. The production control method for improving the bending degree of steering gear nut steel according to claim 5, characterized in that: When the steel for the steering gear nut is rolled, an online heating furnace, high-pressure water descaling, 23 alternating horizontal and vertical short stress line rolling mills, 4 three-roll KOCKS rolling mills, 5 flying shears, and 7 online controlled cooling water tanks are provided. The cooling bed is equipped with a heat preservation cover.

7. The production control method for improving the bending degree of steering gear nut steel according to claim 1, characterized in that: During rolling in step 3), the infeed sizing temperature is kept between 910℃ and 950℃ to prevent the precipitation of proeutectoid ferrite, and rolling is carried out in the single-phase region.

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