Roller preparation method capable of producing high-RPc automobile sheet product

Abstract

The invention discloses a roller preparation method capable of producing a high-RPc automobile plate product, which is a method capable of increasing the RPc value of a roller for producing a high-grade automobile outer plate product in an optimal and most economical manner, after the factors influencing the surface roughness of cold-rolled strip steel are studied, the whole process of roller grinding and texturing is respectively analyzed and studied, and the surface roughness of the cold-rolled strip steel is improved. The control process is deeply analyzed, and the technological process of the microscopic state is researched. After repeated tests, on the premise that existing equipment is determined, the roller capable of meeting the technical requirements of the surface of an automobile outer plate product can be completed, and the use kilometers of the cold-rolled automobile plate surface peak value (RPc) roller can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of roller grinding quality control, and in particular relates to a roller preparation method capable of producing high RPc automobile plate products. Background Art

[0002] At present, with the rapid development of the automobile, home appliance and other industries, the demand for high-quality cold-rolled steel strips is increasing year by year, and users have continuously improved their requirements for the surface quality and performance of steel strips. Chery Automobile, a major customer of automobile outer panels, reported that the products supplied by our company have problems such as rough surface feel and poor freshness after painting. This study is mainly aimed at the complaints of end customers about the rough surface feel and poor freshness after painting of our company's cold-rolled automobile sheet products. We will conduct in-depth research on the relevant technical parameters that affect the surface feel and coating effect of steel strips, analyze and optimize the influencing factors of each cold rolling process, master its control rules, and achieve an increase in the peak number RPc of the surface of cold-rolled automobile sheets.

[0003] The existing patent research is as follows:

[0004] The patent "A method for controlling the grinding of low-roughness roll surfaces" is a grinding method for different low roughnesses, and is only a control method for the roughness Ra;

[0005] The patent "A method for controlling the grinding quality of high-quality cold-rolled rolls" establishes the relationship between roll speed, grinding wheel linear speed, roll diameter, grinding wheel width, grinding pass and other parameters and roll grinding quality through grinding speed ratio and overlap. It is mainly a method for controlling the surface quality of rolls.

[0006] The present invention is a method for improving the RPc value of rollers for producing high-level automobile outer plate products in the best and most economical way. After studying the factors affecting the surface roughness of cold-rolled strip steel, the whole process of roller grinding and texturing is analyzed and studied, and the control process is deeply analyzed to study the process of its microscopic state. After repeated tests, it is determined that under the premise of existing equipment, rollers that meet the surface technical requirements of automobile outer plate products can be completed, and the peak value number (RPc) of the surface of cold-rolled automobile plates can be achieved. Roller usage kilometers.

[0007] According to the above technical background, we visited Chery Automobile, the end user of automobile plates, and investigated the performance of external plate products. At the same time, we collected similar products from other advanced steel mills for benchmarking. We found the gap between products. With the continuous development of industrial technology, end users have more stringent requirements on product performance and surface quality. The client's simpler and low-loss steel plate processing technology, as well as the continuous improvement of market demand for product quality, have forced upstream factories, namely cold-rolled strip production, to continuously innovate technology. We mainly tracked the transfer effect of rollers with different roughness at different kilometres on the cold-rolled finished product production line to study its transfer law; the same roughness and different roughness rollers were used for the acid-rolled F5 frame and the subsequent leveler, and the RPc value of the final product was tracked to study its superposition relationship; the plate surface roughness and RPc value of chrome-plated and non-chrome-plated rollers were tracked at different kilometres on the machine to explore its attenuation law.

[0008] The industry uses methods such as EDM roughening after fine grinding to achieve the roughness performance control of the roll. However, the roll grinding process is subject to the uncertainty of the self-sharpening of the grinding wheel and the micro-graining situation, which cannot stably control the grinding quality of such extremely high requirements, resulting in unstable roughness control after roll roughening and extremely difficult grinding. The roughening process is difficult to control because its principle is to punch irregularly distributed small pits on the roll surface in a microscopic state. All production lines sacrifice a lot of working time for repeated roughening to achieve high RPc values ​​and good roughness retention performance. The above control processes are all characterized by unstable control processes and low success rates, which is also the current status of the industry. The two parameters of roughness (Ra) and peak number (RPc) are analyzed. Since the mechanical properties of the final product must be achieved, the rolling force and elongation of the production line that affect the roughness and peak value cannot be further adjusted. Therefore, in order to achieve the purpose of controlling the roughness and peak value of the strip, the only thing left is to study the rolls that are directly involved in the deformation and surface morphology of the strip, that is, to achieve a strip with a high RPc value surface, to achieve an increase in the RPc value of the roll surface.

[0009] In view of the above analysis, the starting point of the present invention is to analyze and study the whole process of roller grinding and texturing, conduct in-depth analysis of its control process, and study its microscopic process. Roller processing is divided into grinding and texturing processes. The roller grinding process provides a reference surface for subsequent processing of the roller texturing process. The flatter the reference surface, the more obvious the pitting and pitting after texturing. Summary of the invention

[0010] The purpose of the present invention is to provide a roll preparation method for producing high RPc automobile plate products. When producing high-level automobile products, the production method of high RPc roll preparation can be stably completed; it is a roll preparation method for producing automobile covering parts and other products with high forming performance and high quality. The purpose of the present invention is to develop a roll preparation method for outer plate products that meets the user's requirements in combination with the needs of users. With the rapid development of the automobile industry, users have continuously improved their requirements for the surface quality and performance of strip steel. Chery Automobile reported that the outer plate products had problems such as rough surface texture and poor freshness after painting, which affected the image of the outer plate products and the subsequent stable supply.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0012] The present invention discloses a roll preparation method for producing high RPc automobile sheet products, comprising:

[0013] Grinding process: Optimize to make the roller surface as smooth as possible after grinding; Material: Increase the pores of the grinding wheel and reduce the sand particle size to 80#; Control: Use low-roughness surface roller grinding operation method to achieve a roller surface roughness of ≤0.4Ra after grinding, and no wheel tail line defects on the surface;

[0014] Texturing process: The texturing bed molten pool and the roller surface are in sealed contact to form a closed space, which is filled with insulating oil mixed with a certain proportion of high-purity graphite powder. The electrode discharges to the roller surface in it, and the discharged arc is conducted to the roller surface by the bridge formed by the graphite particles, causing local high temperature on the roller surface to melt the roller surface and form the required pits.

[0015] Further, the optimized texturing parameters are shown in the following table:

[0016]

[0017]

[0018] .

[0019] Furthermore, the peak value of the surface of the strip rolled by the optimized rollers increased by 30%, and remained stable up to 100 km with the increase of rolling kilometers, and then began to decay slightly, decaying to 80 at 220 km.

[0020] Furthermore, the optimized rolling rollers can ensure that the rolled products meet customer needs within the rolling cycle.

[0021] Furthermore, after the rollers were chrome-plated, the attenuation of the peak number of the strip surface was significantly improved, attenuating by 37% after 220 km, while after chrome plating, it only attenuated by 5.3% at 220 km, and finally attenuated by only 21% at 800 km.

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

[0023] After optimizing the grinding process and the roller texturing process according to the present invention, a roller preparation method can be provided that satisfies the surface technical parameters of automobile outer panel products in the most economical way. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 The variation law of the RPc value of the roller texture under the condition of unchanged material, texture times and other conditions;

[0026] Figure 2 The variation law of the RPc value of the roller texture under the condition of unchanged material and roughness;

[0027] Figure 3 The influence trend of various parameters of EDM texturing on the roller surface;

[0028] Figure 4 To show the attenuation of the peak value of the strip surface with the kilometer number before optimization and after optimization with the 3.0 roll;

[0029] Figure 5 The attenuation of the plate surface roughness and RPc value of chrome-plated and non-chrome-plated rollers at different kilometres of the machine is compared. DETAILED DESCRIPTION

[0030] (1) Under the condition of unchanged material, roughening times and other conditions, the influence of different roughness on RPc value was tested, and the variation law of roller roughening RPc value was obtained as follows: Figure 1 .

[0031] When the roughness is 1.0, the RPc value can be maximized, ranging from 110-160. Then, as the roughness increases, the RPc value shows a downward trend. However, when the roughness is lower than 2.0, the roughening layer on the roller surface is shallow, the roller surface cannot reach a uniform state, and cannot be put into production.

[0032] (2) Experiments were conducted to determine the effect of different roughening times on the RPc value while keeping the material and roughness unchanged.

[0033] The variation law of the roller roughening RPc value is as follows: Figure 2 shown.

[0034] It is concluded that when other variables remain unchanged, increasing the number of texturing times can significantly improve the RPc value, but after 3 times, the RPc value tends to be stable and can no longer show an upward trend. Since our company only has one texturing bed to handle the texturing task of the rolls of 6 cold rolling production lines, it is impossible to achieve large-scale and multiple texturing. At the same time, according to the influence trend of various parameters of EDM texturing on the roll surface (such as Figure 3) to optimize the texturing parameters.

[0035] The optimization experiment effect verification is carried out for the above parameters, and the verification results are as follows:

[0036] Table 1 Roller parameter optimization effect verification table

[0037]

[0038]

[0039] According to the above data, the optimization effect of the early roll grinding process is obvious, and the high RPc value requirements cannot be met under the roughness of 3.0. Under the roughness of 2.0, the single texturing coverage effect is poor and cannot meet the surface quality requirements; the three-time texturing process has a long processing cycle and the results are far beyond the product requirements and cannot be put into normal production use. It is only used as a technical reserve to retain the data rules; the surface quality and RPc value of the two-time texturing meet the requirements, and the processing time for each pair of rolls is 4-5 hours, which meets the production rhythm under the current small-batch production. Therefore, 2 times of texturing with a roughness of 2.0 was determined as the final optimization result, and the optimization parameters and the final roll measured data are as follows:

[0040] Table 2 Texturing parameter optimization

[0041]

[0042]

[0043] Example Analysis

[0044] For the cold-rolled finished product production line, the transfer effect of rollers with different roughness under different machine kilometers is experimentally tracked to study its transfer law. Since the continuous annealing production line produces automobile plates with comprehensive specifications and large output, the continuous annealing production line tracking data is selected for analysis here. The data is collected for plans with DC06 steel grade and the same thickness specifications. The results are as follows:

[0045] Table 3 Data collection

[0046]

[0047] superior Figure 5 The following conclusions are drawn from the analysis of the survey results in the above table:

[0048] The changes in roller transfer rates before and after optimization are not much different. If the subsequent production has special requirements for roughness, the strip can be scheduled according to the data in Table 3.

[0049] The peak value of the strip surface after the optimization is increased by about 30%. With the increase of rolling kilometers, it remains stable up to 100km, and then begins to decay slightly, and decays to 80% at 220km. Before the optimization, the peak value of the strip is only stable at 20-40km, and then begins to decay gradually. With the current actual production of automobile plates, each production is about 120-200km. The optimized rollers can achieve rolling products that meet customer needs within the roller cycle.

[0050] The RPc value superposition test was carried out on the pickling F5 and the subsequent leveler. The continuous annealing production line with higher specifications and output was also selected for verification. The DC06 steel grade with the same specifications was selected for single variable test. The test data are as follows:

[0051] Table 4 Experiment on the superposition effect of peak values ​​of previous and next processes

[0052]

[0053] By comparing the peak values ​​of the pickling and annealing processes, no obvious peak superposition phenomenon was found.

[0054] (3) An attenuation comparison test was conducted on the plate surface roughness and RPc value of chrome-plated and non-chrome-plated rollers at different machine mileages. A galvanized production line with a smaller planned specification change was selected as the test production line, and DC06 raw materials of the same specifications as the automobile outer panel were selected for the test.

[0055] like Figure 5 As shown in the figure, after the chrome plating treatment, the attenuation of the peak number of the strip surface of the roller was significantly improved, attenuating by 37% after 220 km, while after chrome plating, it only attenuated by 5.3% at 220 km, and finally attenuated by only 21% at 800 km. Since there was no such plan in the future, the roller was taken off the production line.

[0056] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A roll preparation method for producing high RPc automotive sheet products, characterized in that: include: Grinding process: Optimize to make the roller surface as smooth as possible after grinding; Material: Increase the pores of the grinding wheel and reduce the sand particle size to 80#; Control: Use low-roughness surface roller grinding operation method to achieve a roller surface roughness of ≤0.4Ra after grinding, and no wheel tail line defects on the surface; Texturing process: The texturing bed molten pool and the roller surface are in sealed contact to form a closed space, which is filled with insulating oil mixed with a certain proportion of high-purity graphite powder. The electrode discharges to the roller surface in it, and the discharged arc is conducted to the roller surface by the bridge formed by the graphite particles, causing local high temperature on the roller surface to melt the roller surface and form the required pits.

2. The roll preparation method for producing high RPc automotive sheet products according to claim 1, characterized in that: The optimized texturing parameters are shown in the following table: 。 3. The roll preparation method for producing high RPc automotive sheet products according to claim 2, characterized in that: After optimization, the peak value of the surface of the rolled strip increased by 30%. With the increase of rolling kilometers, it remained stable up to 100 km, and then began to decay slightly, decaying to 80 at 220 km.

4. The roll preparation method for producing high RPc automotive sheet products according to claim 2, characterized in that: The optimized rolls ensure that the rolled products meet customer needs within the roll cycle.

5. The roll preparation method for producing high RPc automotive sheet products according to claim 1, characterized in that: After the rollers were chrome-plated, the attenuation of the peak number of the strip surface was significantly improved, attenuating by 37% after 220 km, while after chrome plating, it only attenuated by 5.3% at 220 km, and finally attenuated by only 21% at 800 km.

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