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CN-121973025-A - Online polishing and curling integrated device and process for magnesium alloy plate and strip

CN121973025ACN 121973025 ACN121973025 ACN 121973025ACN-121973025-A

Abstract

The invention discloses an on-line polishing and curling integrated device and process for a magnesium alloy plate strip. The device is positioned between the final rolling mill and the crimping machine and comprises a polishing groove body, a grading polishing roller set arranged above the groove body, a tension control system and a constant tension crimping mechanism. And a special weak acid polishing solution is supplied to the polishing area through a spraying system, so that mechanical-chemical cooperative polishing is realized under the spraying wetting condition, and the problem caused by the immersion of the roller body is avoided. The tension system is controlled in a grading closed loop mode according to the plate thickness, and the curling mechanism is linked to keep the tension constant. The process includes online co-polishing and optional electropolishing. According to the invention, polishing and crimping aiming at magnesium alloy characteristics are integrated on line, the problems of magnesium chip generation and difficulty in continuous production caused by off-line grinding are solved, the magnesium chip generation amount is less than 0.002kg/m 2 , the surface roughness Ra reaches 0.15-0.8 mu m, the production efficiency is improved by more than 40%, and the method is suitable for continuous production of 1600-180mm wide plates and strips.

Inventors

  • CHEN WEI
  • JIA JUNCHENG
  • FANG LIANG
  • WEI QINGYUAN
  • LIU YANLI
  • HE JIXIN

Assignees

  • 瓯锟科技(北京)有限公司

Dates

Publication Date
20260505
Application Date
20260126

Claims (10)

  1. 1. The online polishing and crimping integrated device for the magnesium alloy plate strip is arranged between a final rolling mill and a crimping machine of a magnesium alloy rolling production line and is characterized by comprising a polishing groove body (1), a polishing roller set (2), a tension control system (3) and a constant tension crimping mechanism (4); the polishing groove body (1) is of a cuboid open structure, the main body is made of 316L stainless steel, the inner wall is lined with a polytetrafluoroethylene coating with the thickness of 0.5mm, the length of the groove body is 3000mm, the width of the groove body is 1900mm, the depth of the groove body is 500mm, a 30-degree horn mouth guide opening is arranged at an inlet and an outlet of the groove body, the bottom of the groove body is inclined at 1 degree, a magnetic filtering device (11) and a circulating pump are arranged at the bottom of the groove body, a circulating spray pipe (12) for supplying polishing liquid to a contact area between a polishing roller group and a plate belt is arranged at the top of the polishing groove body (1), and a constant-temperature jacket (13) is arranged at the outer side of the groove body; the polishing roller sets (2) are three sets, are equidistantly arranged above the polishing groove body (1) along the advancing direction of a plate belt, the roller surfaces of the polishing roller sets are not immersed below the liquid level of the polishing groove body (1), each set is of an upper-lower pair roller type structure, the lower roller is a fixed roller, the upper roller is a pneumatic pressure regulating roller, the roller length is 1900mm, the first set is a rough polishing roller (21) which adopts 800-mesh white corundum nylon abrasive rollers, the roller diameter is 150mm, the roller surface hardness is Shore 70D, the second set and the third set are fine polishing rollers (22) which adopt wool felt rollers with the density of 800g/m 2 , the roller cores are aluminum alloy and the surface encapsulation thickness is 20mm, and the tension control system (3) comprises a polishing groove body (1) arranged in a feeding mode, the device comprises two groups of active tension rollers (31) and tension sensors (32) at the outlet, wherein the roller diameter of each tension roller (31) is 200mm, the length of each tension roller is 1900mm, the precision of each tension sensor (32) is +/-5N, tension closed-loop control is realized through a PLC, and the constant tension crimping mechanism (4) is linked with the tension control system (3) and the crimping tension value of the constant tension crimping mechanism is consistent with the tension of a plate belt of a polishing section.
  2. 2. The integrated device for online polishing and crimping of the magnesium alloy strip according to claim 1, wherein the polishing solution supplied by the circulating spray pipe (12) is a weak acid system and comprises, by mass, 8% of phosphoric acid, 2% of nitric acid, 3% of ammonium bifluoride, 1% of citric acid, 0.5% of sodium dodecyl benzene sulfonate and the balance of deionized water, wherein the temperature of the polishing solution is controlled at 40+/-2 ℃ and the pH value is controlled at 4.5+/-0.2.
  3. 3. The on-line polishing and curling integrated device for the magnesium alloy plate strip is characterized in that the rolling control of the polishing roller group (2) is that a rough polishing roller is 0.2MPa, a fine polishing roller is 0.1MPa, the linear speed of the polishing roller is synchronous with the advancing speed of the magnesium alloy plate strip by 1:1, and the synchronous speed range is 5-10 m/min.
  4. 4. The on-line polishing and crimping integrated device for the magnesium alloy plate and strip is characterized in that the tension control system (3) sets tension values according to the thickness of the plate and strip in a grading mode, wherein the tension values are 0.5-2 mm of the plate and strip, the tension is controlled to be 500-800N, the tension values are 2-6 mm of the plate and strip, the tension is controlled to be 1000-1500N, and the tension values are 20% -30% of the yield strength of the corresponding magnesium alloy plate and strip.
  5. 5. The online polishing and crimping integrated device for the magnesium alloy plate and strip according to claim 1 is characterized by further comprising an electrolytic polishing section (5), wherein the electrolytic polishing section (5) is arranged between the polishing tank body (1) and the constant-tension crimping mechanism (4) and comprises an electrolytic tank (51), a power supply system (52), an insulating guide roller and an electrolyte circulation system, the electrolytic tank (51) is made of 316L stainless steel lined polytetrafluoroethylene, the size is 4000mm long, 1900mm wide and 300mm deep, a titanium alloy anode plate is arranged in the tank, the length of the anode plate is 1900mm, the distance between the anode plate and the strip is 50mm, the power supply system (52) is a high-frequency switching power supply, the output voltage is 0-30V, the current is 0-500A, the constant-voltage/constant-current mode is provided, the electrolyte is a phosphoric acid-chromic acid system, the electrolyte comprises phosphoric acid 60%, chromic acid 10%, the balance is deionized water, the temperature of the electrolyte is controlled to be 60+/-2 ℃ and the conductivity is 80-100 mS/cm according to mass fraction.
  6. 6. An on-line polishing and curling process for magnesium alloy plate strips based on the device of any one of claims 1 to 5 is characterized by comprising the following steps of S1, guiding the magnesium alloy plate strips subjected to finish rolling to sequentially pass through the three polishing rollers (2) under set tension, S2, continuously supplying polishing liquid with constant temperature and constant components to the surface of the plate strips and the contact area of the polishing rollers (2) and the plate strips through the circulating spray pipe (12), and carrying out mechanical-chemical collaborative polishing under the spray wetting condition, S3, carrying out closed-loop control and stabilization on the plate strip tension through the tension control system (3), and S4, directly entering the constant tension curling mechanism (4) to finish curling under constant tension.
  7. 7. The online polishing and curling process of the magnesium alloy strip according to claim 6 is characterized in that in the step S2, the polishing solution comprises 8% of phosphoric acid, 2% of nitric acid, 3% of ammonium bifluoride, 1% of citric acid, 0.5% of sodium dodecyl benzene sulfonate and the balance of deionized water according to mass fraction, the temperature of the polishing solution is controlled to be 40+/-2 ℃ and the pH value is controlled to be 4.5+/-0.2, the rolling of a rough polishing roller (21) is 0.2MPa, the rolling of a fine polishing roller (22) is 0.1MPa, and the linear speed of the polishing roller and the travelling speed of the strip are synchronous to be 5-10 m/min.
  8. 8. The online polishing and curling process of the magnesium alloy plate strip according to claim 6 is characterized in that in the step S3, tension is controlled in stages according to the thickness of the plate strip, wherein the thickness of the plate strip is 0.5-2 mm, the tension is controlled to be 500-800N, the thickness of the plate strip is 2-6 mm, the tension is controlled to be 1000-1500N, and the tension value is 20% -30% of the yield strength of the corresponding magnesium alloy plate strip.
  9. 9. The online polishing and curling process of the magnesium alloy strip according to claim 6, wherein the online polishing and curling process further comprises the steps of electrolytic polishing and post-treatment after the step S3 and before the step S4, wherein the strip enters an electrolytic polishing section (5) and is subjected to electrolytic treatment for 5-8 seconds at a constant voltage of 12-15V and a current density of 20-30A/dm 2 , and then the strip is subjected to spray washing by deionized water, passivation by chromate passivation liquid and hot air drying in sequence.
  10. 10. The online polishing and curling process of the magnesium alloy strip according to claim 9, wherein the electrolyte used in the electrolytic polishing comprises, by mass, 60% of phosphoric acid, 10% of chromic acid, 5% of glycerin, and the balance of deionized water, and the temperature of the electrolyte is controlled to be 60+/-2 ℃.

Description

Online polishing and curling integrated device and process for magnesium alloy plate and strip Technical Field The invention relates to the technical field of metal plastic processing surface treatment, in particular to an on-line polishing and curling integrated device and process for a magnesium alloy plate and strip, which are particularly suitable for on-line continuous surface treatment of the magnesium alloy plate and strip with the width of 1600-180mm and the thickness of 0.5-6 mm in a final rolling and curling link of a rolling production line. Background The magnesium alloy has wide application prospect in the field of high-end equipment light weight such as aerospace, new energy automobiles, rail transit and the like due to the excellent characteristics of low density and high specific strength. The large-width magnesium alloy plate strip is a key structural material in the field, and the surface quality of the large-width magnesium alloy plate strip directly determines the technological properties such as subsequent welding, coating and the like and the reliability of a final product. At present, after finishing rolling, the magnesium alloy plate strip commonly adopts an off-line grinding process to remove the defects of surface oxide skin, rolling stripes and the like so as to improve the surface finish. The traditional process has the following outstanding defects of 1) environmental protection and potential safety hazards, namely, a large amount of fine magnesium chips are generated in the grinding process, the magnesium chips are inflammable and explosive, the treatment difficulty is high, the cost is high, and the serious potential safety hazard exists, 2) the quality control is difficult, the grinding quantity is difficult to accurately control, excessive waste of materials or incomplete removal of surface defects are easily caused, 3) the production efficiency is low, the grinding process is independent of a rolling line, the plate strip is required to be transported and uncoiled again, the production continuity is broken, and particularly, the transportation difficulty and the deformation risk of a large-width plate strip are greatly increased, 4) the process connection is poor, the plate strip is required to be curled after grinding by reestablishing tension, and poor plate shape or interlayer scratch are easily caused. To solve the above problems, alternative techniques such as sand blasting and chemical polishing have been explored. However, the abrasive material consumption in the sand blasting process is large, the surface uniformity is poor, the conventional chemical polishing is mostly wire-separating groove type treatment, the wire-separating groove type treatment cannot be integrated with a high-speed continuous rolling production line on line, and the problems of 'hydrogen embrittlement' of magnesium alloy and the like are easily caused by a strong acid system. In addition, the existing online polishing and curling integrated equipment for aluminum alloy and stainless steel is designed based on higher-hardness metal due to polishing media (such as hard steel rollers), technological parameters (such as high rolling and high tension) and polishing liquid systems (such as alkalinity), and if the online polishing and curling integrated equipment is directly applied to magnesium alloy with lower hardness (HB 30-50) and active chemical property, serious scratch, corrosion or stretching deformation of the surface of a plate and strip are necessarily caused. Therefore, the development of the large-width plate strip on-line surface treatment device and the large-width plate strip on-line surface treatment process which can be in seamless connection with a magnesium alloy rolling production line, avoid generating a large amount of magnesium scraps in principle and adapt to the characteristics of magnesium alloy materials becomes a technical bottleneck which cannot be solved for a long time in the industry. Disclosure of Invention Object of the invention The invention aims at overcoming the defects of the prior art and providing an on-line polishing and curling integrated device and process for a magnesium alloy plate strip. The proposal aims at integrating the polishing process and the curling process which are optimized for the magnesium alloy characteristics on line, and directly embedding the polishing process and the curling process into a rolling production line to replace the traditional off-line grinding process, thereby fundamentally solving the difficult problem of magnesium chip treatment and realizing the high-quality, high-efficiency and continuous production of the magnesium alloy plate and strip with large width. (II) technical scheme In order to achieve the above purpose, the invention adopts the following technical scheme: The magnesium alloy strip on-line polishing and crimping integrated device is arranged between a final rolling mill and a crimping machine of a magnesiu