Quenching water mark control method for roller hearth quenching furnace

Abstract

The invention belongs to the technical field of aluminum processing and production, and particularly discloses a quenching water mark control method for a roller hearth quenching furnace. The device is used for solving the problem that water marks of discharged plates of an existing roller hearth quenching furnace cannot be controlled within extremely high requirements. According to the method, trimming, pre-stretching and solid solution quenching treatment are sequentially carried out on the plate. During edge cutting treatment, the edge cutting amount is 15-50 mm; during the pre-stretching treatment, the stretching rate is 0.5-1.0%; and during solid solution quenching treatment, the height of an inlet water jet is controlled to be 300 mm or above, the angle of the inlet water jet is 35-50 degrees, the comprehensive flow of a nozzle of the inlet water jet is 5-10 L / s, the ratio of the upper water flow to the lower water flow in quenching is 0.65-0.85, and the plate transfer speed is 100-500 mm / s. The method is simple, easy to operate, high in stability and good in repeatability, the quenching uniformity and apparent quality of the plate can be improved, and then the economic benefits and social benefits of enterprises are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum processing production, and in particular relates to a method for controlling quenching water marks in a roller bottom quenching furnace. Background Art

[0002] Aircraft aluminum alloy stretched sheets have strict requirements on the surface quality of the final product. Quenching water marks will affect the surface quality of the product. If the water marks are too heavy, the stretched sheet will be scrapped. Not only that, the water marks will also affect the uniformity of quenching, resulting in uneven conductivity and hardenability of the stretched sheet, which will also cause the stretched sheet to be scrapped in severe cases. Therefore, controlling water marks is extremely critical in the production of aircraft aluminum alloy stretched sheets.

[0003] The roller-bottom quenching furnace is a commonly used water quenching equipment. During the water quenching process, the inlet water jet of the roller-bottom quenching furnace first contacts the surface of the stretched plate, which has the greatest impact on the surface quality of the stretched plate. If the inlet water jet is not set properly, it will not only produce water marks on the surface of the stretched plate, but also cause the water quenching uniformity to deteriorate, resulting in the deterioration of the apparent quality and internal quality of the finished product, and in severe cases directly lead to product scrapping.

[0004] At present, the water marks on the plates coming out of the roller bottom quenching furnace cannot be controlled within extremely high requirements. Therefore, a complete set of standard production processes must be adopted to ensure the surface quality of the plates after quenching and to ensure that all material indicators meet the requirements of downstream customers for the product. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling quenching water marks in a roller hearth quenching furnace, which effectively solves the problem that the water marks of plates discharged from the roller hearth quenching furnace cannot be controlled within extremely high requirements.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for controlling quenching water marks in a roller bottom quenching furnace is provided, wherein the plate is subjected to trimming, pre-stretching and solution quenching treatment in sequence. When trimming, the trimming amount is 15-50 mm; when pre-stretching, the stretching rate is 0.5-1.0%; when solution quenching, the inlet water jet height is controlled to be above 300 mm, the inlet water jet angle is 35°-50°, the inlet water jet nozzle comprehensive flow rate is 5-10 L / s, the quenching upper and lower water flow rate ratio is 0.65-0.85, and the plate transfer speed is 100-500 mm / s.

[0008] Furthermore, as the thickness of the plate increases, the height of the inlet water jet also increases accordingly. When the angle remains unchanged, the difference between the height of the inlet water jet and the thickness of the plate is a fixed value, that is, Hh=L(1), where H is the height of the inlet water jet, h is the thickness of the plate, and l is the distance constant.

[0009] Furthermore, when the inlet water jet height reaches the upper limit, the water jet angle is adjusted to ensure the spray distance of the water jet, cosα=(Hh) / L(2), where L is the distance constant and α is the inlet water jet angle.

[0010] Furthermore, the height and angle of the inlet water jet are adjusted as follows: before the height of the inlet water jet reaches an upper limit, the angle of the inlet water jet is kept unchanged, and the height of the inlet water jet is adjusted according to formula (1); after the height of the inlet water jet reaches an upper limit, the height of the inlet water jet is kept unchanged, and the angle of the inlet water jet is adjusted according to formula (2).

[0011] Furthermore, the distance between adjacent nozzles is no more than 100 mm, the nozzles are not blocked or cracked, and the pipelines are not cracked.

[0012] Furthermore, the quenching water is deionized water, the pH of the quenching water is 6-8, and the conductivity of the quenching water is 50-200 μS / cm. When the conductivity of the quenching water is insufficient, the conductivity value is increased by adding sodium hydroxide.

[0013] Furthermore, the inlet water jet includes an upper water jet and a lower water jet, and the upper water jet and the lower water jet are separated on the upper and lower sides of the plate. When the thickness of the plate is not more than 10mm, the comprehensive water flow rate of the upper water jet nozzle is 5.5L / s, and the comprehensive water flow rate of the lower water jet nozzle is 7.9L / s; when the thickness of the plate is 10-20mm, the comprehensive water flow rate of the upper water jet nozzle is 6.5L / s, and the comprehensive water flow rate of the lower water jet nozzle is 9.5L / s; when the thickness of the plate is 20-50mm, the comprehensive water flow rate of the upper water jet nozzle is 7.0L / s, and the comprehensive water flow rate of the lower water jet nozzle is 10.0L / s; when the thickness of the plate is 50-250mm, the comprehensive water flow rate of the upper water jet nozzle is 7.5L / s, and the comprehensive water flow rate of the lower water jet nozzle is 10.0L / s.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are:

[0015] The method of the present invention is simple, easy to operate, highly stable and has good repeatability. Firstly, the shape of the plate is controlled by controlling the trimming and pre-stretching, so that the plate is cooled evenly during quenching, avoiding the occurrence of uneven water pressure; secondly, the surface quality of the plate after quenching is ensured by adjusting the angle, height and flow rate of the inlet water knife and other processes, effectively solving the problem of water marks on the surface of the plate, improving the quenching uniformity and appearance quality of the plate, and thus improving the economic and social benefits of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the water jet at the entrance of the roller hearth quenching furnace. The solid arrow in the figure indicates the direction of plate movement.

[0017] List of reference numerals: upper water jet - 1; lower water jet - 2; plate - 3. DETAILED DESCRIPTION

[0018] A method for controlling quenching water marks in a roller bottom quenching furnace, wherein the plate is subjected to trimming, pre-stretching and solution quenching treatment in sequence. (1) During trimming, the trimming amount is 15-50 mm, thereby releasing a wave of internal stress. (2) During pre-stretching, the stretching rate is 0.5-1.0%, and the internal stress is continuously released after stretching, and the plate shape before quenching is guaranteed. (3) During solution quenching, the inlet water jet height is controlled to be above 300 mm, the inlet water jet angle is 35°-50°, the inlet water jet nozzle comprehensive flow rate is 5-10 L / s, the quenching upper and lower water flow ratio is 0.65-0.85, and the plate transfer speed is 100-500 mm / s.

[0019] like Figure 1 As shown, the inlet water jet includes an upper water jet 1 and a lower water jet 2, which are located on the upper and lower sides of the plate 3. The inlet water jet is the first part to contact the surface of the plate 3 during solution quenching treatment, but the water flow is relatively small, and both the upper water jet 1 and the lower water jet 2 have only one row of nozzles, which mainly prevent the water in the quenching zone from splashing outside the quenching zone. The inlet water jet height refers to the distance between the upper water jet 1 and the feeding roller (i.e., the height from the bottom of the plate), and the inlet water jet angle refers to the angle between the spray direction of the upper water jet 1 or the lower water jet 2 and the vertical direction of the moving direction of the plate 3.

[0020] The applicant has found through research that the water flow rate of the inlet water jet should not be too large while meeting the above requirements. For thin plates with a thickness of less than 6.35 mm, the water flow rate of the inlet water jet should be small enough to prevent the inlet water jet from producing a quenching effect and affecting the plate shape. When the plate thickness is not more than 10 mm, the comprehensive water flow rate of the upper water jet nozzle is 5.5 L / s, and the comprehensive water flow rate of the lower water jet nozzle is 7.9 L / s; when the plate thickness is 10-20 mm, the comprehensive water flow rate of the upper water jet nozzle is 6.5 L / s, and the comprehensive water flow rate of the lower water jet nozzle is 9.5 L / s; when the plate thickness is 20-50 mm, the comprehensive water flow rate of the upper water jet nozzle is 7.0 L / s, and the comprehensive water flow rate of the lower water jet nozzle is 10.0 L / s; when the plate thickness is 50-250 mm, the comprehensive water flow rate of the upper water jet nozzle is 7.5 L / s, and the comprehensive water flow rate of the lower water jet nozzle is 10.0 L / s.

[0021] The quenching water sprayed by the upper and lower water jets needs to overlap on a line of the plate to ensure uniform deformation of the upper and lower surfaces of the plate, to ensure more uniform cooling of each position of the plate, and to avoid water marks caused by excessive temperature difference between the upper and lower surfaces of the plate. At the same time, adjust the height and angle of the inlet water jet to ensure that the quenching water sprayed by the upper and lower water jets is sprayed on the same point of the plate.

[0022] The applicant has found that (1) the relationship between the height of the inlet water jet and the thickness of the plate: as the thickness of the plate increases, the height of the inlet water jet should increase accordingly. When the angle remains unchanged, the difference between the height of the inlet water jet and the thickness of the plate is a fixed value, that is, Hh = L(I), where H is the height of the inlet water jet; h is the thickness of the plate; and L is a distance constant, generally 300 mm. This ensures that the water sprayed from the nozzle spreads more evenly and can be sprayed evenly on the surface of the plate. At the same time, it is necessary to avoid the situation where there is no water in some parts of the plate surface when the quenching water is sprayed on the plate surface.

[0023] (2) The relationship between the inlet water jet angle and the inlet water jet height: Generally speaking, the inlet water jet cannot be raised indefinitely. Therefore, when the inlet water jet reaches the upper limit of its height, it is difficult to ensure the height of the inlet water jet and the thickness difference of the plate. In this case, if you want to ensure the spray distance of the inlet water jet, you can adjust the angle of the inlet water jet. cosα=(Hh) / L(II), where L is the distance constant, generally 300mm, and α is the inlet water jet angle. It is recommended that the inlet water jet angle be 35°-50°, which meets the requirements of fluid mechanics and allows the water that contacts the surface of the plate to be sprayed away faster by the water behind.

[0024] (3) The height and angle of the inlet water jet are adjusted as follows: before the height of the inlet water jet reaches the upper limit, keep the angle of the inlet water jet unchanged (45° is recommended) and adjust the height of the inlet water jet according to formula (I); after the height of the inlet water jet reaches the upper limit, keep the height of the inlet water jet unchanged and adjust the angle of the inlet water jet according to formula (II). Assuming that the upper limit of the inlet water jet height is 500mm and the distance constant is 300mm, when producing 250mm thick plates, if the inlet water jet height is adjusted, the inlet water jet height needs to be adjusted to 550mm. If the upper limit of the inlet water jet height is exceeded, the inlet water jet angle needs to be adjusted. Enter formula (I) and formula (II) into the electrical program. You only need to enter the plate thickness before the quenching roller furnace enters the furnace to automatically control the height and angle of the inlet water jet.

[0025] (4) Transfer speed refers to the speed at which the plate moves through the inlet water jet and the quenching zone. A fast transfer speed can reduce the contact time between the plate and the inlet water jet flow, increase hardenability, and prevent water marks caused by uneven water absorption on the plate; if the transfer speed is too slow, it will affect the quenching effect of the quenching zone and make the material shape worse. Therefore, the transfer speed should be increased while ensuring the hardenability and related properties of the aluminum plate.

[0026] (5) The distance between adjacent nozzles should be small enough, preferably no more than 100 mm, to ensure that the surface of the board is evenly watered.

[0027] The nozzle should not be blocked or cracked, and the pipe should not be cracked. When the nozzle is blocked, the water pressure at the nozzle position will increase significantly, and the water flow will not be dispersed. Excessive water pressure will cause white streaks. The same is true for pipe cracks. A large amount of water is generated at the cracked position, which will spray onto the board and cause long water marks.

[0028] Methods for checking nozzles and pipes: ① Open the nozzle manually to spray water, and set the water flow rate to the minimum water flow rate that can spray water. At this time, check whether the nozzle is blocked and whether the pipe is cracked. ② Observe the water pressure of the pipe: When the water flow rate is large (such as 360L / s), if there is no pipe crack, its water pressure should be the largest (such as 2.0bar). If the pipe cracks, the water pressure in the pipe will decrease due to the loss of water. When the degree of cracking is large, the water pressure will drop seriously (such as 1.7bar), so as to judge whether the pipe is cracked and the size of the crack.

[0029] Methods to prevent pipe cracking: Water supply pipes may crack at corners due to long-term high pressure. The general solution is welding, but without more advanced welding methods, such as argon arc welding, it is generally difficult to weld evenly, and cracking will occur repeatedly due to poor welding quality (such as different strengths at different welding positions). However, due to the influence of the size of the quenching zone, high-level welding work is generally not possible. In order to solve the problem of repeated cracking, the applicant has found that reinforcing the cracked position while welding the pipeline can improve the crack resistance of the pipeline. For example, bend an iron sheet 90° (according to actual conditions), and then weld the iron sheet to the cracked position. The cracked position is reinforced by a circle of welding and increasing the strength of the iron sheet.

[0030] (6) Requirements for quenching water: ① The pH of quenching water is 6-8, and it is recommended to test it once every 1-2 weeks. ② The conductivity of quenching water is 50-200μS / cm, and it is recommended to test it once every 1-2 weeks. ③ In combination with the actual situation of the enterprise, try to reduce the content of calcium ions and chloride ions in the quenching water. Excessive content of calcium ions and chloride ions can easily cause corrosion or color difference to aluminum alloys. It is recommended to test it once every 1-2 months. ④ The replacement cycle of quenching water is generally 1-2 years. It is necessary to ensure that the water body is clear and free of excessive turbidity. It should be replaced according to the water marks on the surface of the plate. If the water marks on the surface of the plate cannot be eliminated, the water can be changed in advance. ⑤ It is recommended to use deionized water for quenching, but the conductivity of the new deionized water is too low (less than 20μS / cm). When the conductivity is too low, the quenching effect is not ideal. Therefore, additives are added to achieve the purpose of quickly increasing the conductivity of quenching water. Sodium hydroxide is recommended as an additive, and sodium chloride is not recommended. Because sodium chloride will increase the chloride ion content in the quenching water, and chloride ions will form HCl under acidic conditions, which is easy to cause corrosion. However, the hydroxide ions obtained from sodium hydroxide can neutralize the HCl in the quenching water, which can not only improve the conductivity but also prevent the quenching water from being weakly acidic.

[0031] The present invention firstly controls the plate shape by controlling the trimming and pre-stretching, so that the plate is cooled evenly during quenching to avoid uneven water pressure; secondly, the surface quality of the plate after quenching is ensured by adjusting the angle, height, water pressure and flow rate of the inlet water jet, effectively solving the problem of water marks on the surface of the plate, and improving the quenching uniformity and surface quality of the plate. The present invention will be further described in detail in combination with the embodiments and comparative examples.

[0032] Example 1: Aluminum alloy is treated by using the roller bottom quenching furnace quenching water mark control method provided by the present invention.

[0033] (1) Trimming: The trimming amount is 25 mm. After trimming, keep it for later use.

[0034] (2) Pre-stretching: The trimmed sheet is stretched with a stretching rate of 0.8%. The size of the obtained aluminum alloy sheet is: 50 mm thick * 1200 mm wide * 13000 mm long.

[0035] (3) Solution quenching treatment: The inlet water jet height is 350 mm, the inlet water jet angle is 45°, the comprehensive water flow rate of the upper water jet nozzle is 7.0 L / s, the comprehensive water flow rate of the lower water jet nozzle is 10.0 L / s, the transfer speed is 200 mm / s, and there is no water mark after quenching.

[0036] Comparative Example 1: The difference from Example 1 is that the inlet water jet height of Comparative Example 1 is 200 mm, and there are water marks after quenching.

[0037] It can be seen from Example 1 and Comparative Example 1 that when the inlet water jet angle remains unchanged and the difference between the height of the inlet water jet and the thickness of the plate is a distance constant (300 mm), it is beneficial to ensure that the water sprayed from the nozzle is diffused more evenly, so that there is no water mark on the plate after quenching.

[0038] Example 2: Aluminum alloy is treated by using the roller bottom quenching furnace quenching water mark control method provided by the present invention.

[0039] (1) Trimming: The trimming amount is 15 mm. After trimming, keep it for later use.

[0040] (2) Pre-stretching: The trimmed sheet is stretched at a rate of 0.5% to obtain an aluminum alloy sheet with dimensions of 200 mm thick, 1200 mm wide, and 10,000 mm long.

[0041] (3) Solution quenching treatment: The inlet water jet height is 500 mm (upper limit), the inlet water jet angle is 45°, the comprehensive water flow rate of the upper water jet nozzle is 7.5 L / s, the comprehensive water flow rate of the lower water jet nozzle is 10.0 L / s, the transfer speed is 100 mm / s, and there is no water mark after quenching.

[0042] Comparative Example 2: The difference from Example 2 is that the inlet water jet angle of Comparative Example 2 is 35°, and there are water marks after quenching.

[0043] It can be seen from Example 2 and Comparative Example 2 that after the height of the inlet water jet reaches the upper limit (500 mm), keeping the height of the inlet water jet unchanged and adjusting the angle of the inlet water jet according to formula (II) is conducive to achieving water mark-free plate after quenching.

[0044] Example 3: Aluminum alloy is treated by using the roller bottom quenching furnace quenching water mark control method provided by the present invention.

[0045] (1) Trimming: The trimming amount is 50 mm. After trimming, keep it for later use.

[0046] (2) Pre-stretching: The trimmed sheet is stretched with a stretching rate of 1.0%. The size of the obtained aluminum alloy sheet is: 220 mm thick * 1200 mm wide * 10000 mm long.

[0047] (3) Solution quenching treatment: The inlet water jet height is 500 mm (upper limit), the inlet water jet angle is 50°, the comprehensive water flow rate of the upper water jet nozzle is 7.5 L / s, the comprehensive water flow rate of the lower water jet nozzle is 10.0 L / s, the transfer speed is 500 mm / s, and there is no water mark after quenching.

[0048] Comparative Example 3: The difference from Example 3 is that the comprehensive water flow rate of the water jet nozzle of Comparative Example 3 is 13 L / s, and there are water marks after quenching.

[0049] It can be seen from Example 3 and Comparative Example 3 that in order to ensure that there is no water mark on the plate after quenching, the importance of nozzle flow rate cannot be ignored.

[0050] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for controlling quenching water marks in a roller hearth quenching furnace, characterized in that: The plate is subjected to trimming, pre-stretching and solution quenching treatments in sequence; When trimming, the trimming amount is 15-50mm; when pre-stretching, the stretching rate is 0.5-1.0%; During solution quenching treatment, the inlet water jet height is controlled to be above 300mm, the inlet water jet angle is 35°-50°, the inlet water jet nozzle comprehensive flow rate is 5-10L / s, the quenching upper and lower water flow ratio is 0.65-0.85, and the plate transfer speed is 100-500mm / s.

2. The method for controlling quenching water marks in a roller hearth quenching furnace according to claim 1, characterized in that: As the thickness of the plate increases, the height of the inlet water jet also increases accordingly. When the angle remains unchanged, the difference between the height of the inlet water jet and the thickness of the plate is a fixed value, that is, Hh=L(1), where H is the height of the inlet water jet, h is the thickness of the plate, and L is the distance constant.

3. The method for controlling quenching water marks in a roller hearth quenching furnace according to claim 2, characterized in that: When the inlet water jet height reaches the upper limit, the water jet angle is adjusted to ensure the jet distance of the water jet, cosα=(Hh) / L(2), where L is the distance constant and α is the inlet water jet angle.

4. The method for controlling quenching water marks in a roller hearth quenching furnace according to claim 3, characterized in that: The height and angle of the inlet water jet are adjusted as follows: before the height of the inlet water jet reaches the upper limit, the angle of the inlet water jet is kept unchanged, and the height of the inlet water jet is adjusted according to formula (1); after the height of the inlet water jet reaches the upper limit, the height of the inlet water jet is kept unchanged, and the angle of the inlet water jet is adjusted according to formula (2).

5. The method for controlling quenching water marks in a roller hearth quenching furnace according to claim 4, characterized in that: The distance between adjacent nozzles is no more than 100mm, the nozzles are not blocked or cracked, and the pipelines are not cracked.

6. The method for controlling quenching water marks in a roller hearth quenching furnace according to claim 5, characterized in that: The quenching water is deionized water, the pH of the quenching water is 6-8, and the conductivity of the quenching water is 50-200 μS / cm. When the conductivity of the quenching water is insufficient, the conductivity value is increased by adding sodium hydroxide.

7. The method for controlling quenching water marks in a roller hearth quenching furnace according to claim 1, characterized in that: The inlet water jet includes an upper water jet and a lower water jet, which are located on the upper and lower sides of the plate. When the plate thickness is not more than 10mm, the comprehensive water flow rate of the upper water jet nozzle is 5.5L / s, and the comprehensive water flow rate of the lower water jet nozzle is 7.9L / s; when the plate thickness is 10-20mm, the comprehensive water flow rate of the upper water jet nozzle is 6.5L / s, and the comprehensive water flow rate of the lower water jet nozzle is 9.5L / s; when the plate thickness is 20-50mm, the comprehensive water flow rate of the upper water jet nozzle is 7.0L / s, and the comprehensive water flow rate of the lower water jet nozzle is 10.0L / s; when the plate thickness is 50-250mm, the comprehensive water flow rate of the upper water jet nozzle is 7.5L / s, and the comprehensive water flow rate of the lower water jet nozzle is 10.0L / s.

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