Method for improving the ridging of invar strip

Abstract

An INVAR strip rib improving method, comprising: S1: obtaining a strip initial state, including a strip thickness, a strip width, and a strip initial flatness state, the initial flatness state including straightness, edge wave height, and center wave height of the strip; S2: adjusting initial flattening process parameters according to the initial state of the strip, the flattening process parameters including convexity of a flattening roller, furnace temperature, tension, and holding time; S3: placing the strip after S2 adjustment into a heat treatment furnace, monitoring a transverse pressure difference of the strip, measuring a pressure distribution in real time at an outlet of the heat treatment furnace and calculating a real-time transverse pressure difference ΔP of the strip; and S4: dynamically adjusting the flattening process parameters in the process according to the transverse pressure difference of the strip, so as to make the transverse pressure difference of the strip satisfy a target threshold value.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal material processing, in particular to an INVAR strip raising improvement method. BACKGROUND

[0002] OLED display technology has become an important development direction in the display field due to its excellent display performance, such as high contrast, fast response time and wide viewing angle. In the manufacturing process of an OLED display screen, a high-precision metal mask plays a crucial role. With the development of OLED display technology towards higher resolution and larger size, higher precision and quality of the high-precision metal mask are required.

[0003] The high-precision metal mask is made of INVAR alloy strip. Invar alloy is a kind of iron-nickel alloy with extremely low thermal expansion coefficient, and is widely used in high-precision manufacturing field due to its dimensional stability at high temperature. However, the surface of the Invar alloy strip is prone to raising phenomenon during the production process. The surface raising phenomenon of the Invar alloy strip is that irregular protrusions or corrugations appear on the surface of the strip, which seriously affects the surface flatness of the strip.

[0004] Further, the surface raising phenomenon of the INVAR alloy strip will cause the opening size precision of the high-precision metal mask to decrease, thereby affecting the pixel pattern precision of the OLED display screen. Therefore, an INVAR strip raising improvement method is needed. SUMMARY

[0005] The application aims to provide an INVAR strip raising improvement method for improving the surface flatness of the strip and eliminating irregular protrusions or corrugations on the surface of the strip.

[0006] An INVAR strip raising improvement method, comprising: S1: obtaining an initial state of the strip, including the thickness of the strip, the width of the strip, and an initial plate shape state, the initial plate shape state including the straightness of the strip, the edge wave height, and the middle wave height; S2: adjusting the initial flattening process parameters according to the initial state of the strip, the flattening process parameters including the crown of the flattening roller, the furnace temperature, the tension, and the holding time; S3: placing the strip adjusted in S2 into a heat treatment furnace, monitoring the transverse pressure difference of the strip, and measuring the pressure distribution in real time at the outlet of the heat treatment furnace and calculating the transverse pressure difference ΔP of the strip in real time; and S4: dynamically adjusting the flattening process parameters in the process according to the transverse pressure difference of the strip, so that the transverse pressure difference of the strip meets the target threshold.

[0007] S2: adjusting the initial flattening process parameters according to the initial state of the strip, the flattening process parameters including the crown of the flattening roller, the furnace temperature, the tension, and the holding time;

[0008] S3: placing the strip adjusted in S2 into a heat treatment furnace, monitoring the transverse pressure difference of the strip, and measuring the pressure distribution in real time at the outlet of the heat treatment furnace and calculating the transverse pressure difference ΔP of the strip in real time; and S4: dynamically adjusting the flattening process parameters in the process according to the transverse pressure difference of the strip, so that the transverse pressure difference of the strip meets the target threshold.

[0009] S4: dynamically adjusting the flattening process parameters in the process according to the transverse pressure difference of the strip, so that the transverse pressure difference of the strip meets the target threshold.

[0010] Further, the step S1 comprises normalizing the strip thickness, strip width, and the initial strip flatness, H|=(H-20) / 40, W|=(W-150) / 450, S|=S / 0.05, E|=E / 150, Z|=Z / 200, wherein H is the strip thickness, W is the strip width, S is the straightness, E is the edge wave height, and Z is the center wave height.

[0011] Further, the step S2 comprises calculating the initial flattening process parameters according to the strip thickness, strip width, and the initial strip flatness normalization parameters, including wherein the convexity of the flattening roller C=(0.05+0.25W|)×(1+0.4W|-0.6Z|)×(0.8+0.2H|), the tension F=(40+5H|)×(1-0.3Z|-0.1S|)×(0.9+0.1W|), and the holding time t=(20+40H|)×(1+0.2Z|+0.15S|)×(1-0.05W|).

[0012] Further, the furnace temperature comprises a preheating zone, a soaking zone, and a slow cooling zone, and adjusting the furnace temperature corresponds to adjusting the temperature of the soaking zone.

[0013] Further, in the step S3, the transverse pressure difference of the strip is monitored, including measuring the contact pressure of each point in the transverse width direction of the strip at the outlet of the heat treatment furnace, calculating the transverse pressure difference ΔP of the strip, |ΔP| = |(Pc -Pa)| / Wc, wherein Pc is the center point pressure of the strip, Pa is the average pressure of the strip, and Wc is the transverse width of the strip.

[0014] Further, the step S4 comprises S41: obtaining the transverse pressure difference |ΔP| of the strip;

[0015] S42: adjusting the flattening process parameters according to the transverse pressure difference |ΔP| of the strip and the target threshold P0, so that the flatness ΔP is less than the target threshold P0.

[0016] Further, in the step S42, when a0≤|ΔP|<a1, the flattening roller convexity amplitude C1 is adjusted, if ΔP does not change, the tension amplitude F1 is adjusted, if ΔP does not change, the flattening roller convexity amplitude C2 is adjusted, and the tension amplitude F2 is adjusted simultaneously;

[0017] When a1≤|ΔP|, the flattening roller convexity amplitude C2 is adjusted, and the tension amplitude F2 is adjusted simultaneously, if ΔP does not change, the holding time amplitude t1 is adjusted.

[0018] Further: C1<C2, F1<F2.

[0019] Further, comprising, heat treatment furnace, temperature control assembly, flattening roller, conveying assembly, contact pressure sensor array, the heat treatment furnace has an entrance, an exit, the temperature control assembly, flattening roller, conveying assembly are arranged in the heat treatment furnace, the contact pressure sensor array is arranged at the exit of the heat treatment furnace.

[0020] Further, the flattening roller is a crescent-shaped flattening roller, which has a convexity adjusting mechanism to adjust the convexity or concavity of the surface of the flattening roller.

[0021] The present application has at least the following advantages or benefits: improving the surface flatness of the strip, and eliminating irregular protrusions or ripples on the surface of the strip. DETAILED DESCRIPTION

[0022] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below with specific implementation in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application.

[0023] In the description of the present application, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is the orientation or position relationship when the product of the present application is usually placed, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, the terms "horizontal", "vertical" and the like do not mean that the components must be absolutely horizontal or vertical, but can be slightly inclined. For example, "horizontal" only means that it is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0025] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection" and "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] The embodiments of the present application provide an INVAR strip rib improvement method, comprising,

[0027] S1: obtaining the initial state of the strip, including the thickness of the strip, the width of the strip, and the initial plate shape state, the initial plate shape state including the straightness of the strip, the edge wave height, and the center wave height;

[0028] S2: adjusting the initial flattening process parameters according to the initial state of the strip, wherein the initial flattening process parameters include the convexity of the flattening roller, the furnace temperature, the tension, and the holding time;

[0029] S3: monitoring the transverse pressure difference of the strip, wherein the pressure distribution is measured in real time at the outlet of the heat treatment furnace and the real-time transverse pressure difference ΔP of the strip is calculated.

[0030] S4: dynamically adjusting the supporting flattening process parameters according to the transverse pressure difference ΔP of the strip to make the transverse pressure difference of the strip meet the target threshold.

[0031] In step S1, the thickness of the strip is tested by Mahr film thickness tester, the width of the strip and the initial plate shape state of the strip are tested offline by a three-coordinate device, and the sample is tested after the strip process, and the equipment accuracy is: XY: (3.5+L / 150) um; Z: 4mm+1um.

[0032] The straightness of the strip can be used to indicate the bending degree of the strip in the longitudinal direction, the edge wave height refers to the maximum height of the wave on the two edges of the strip, and the center wave height refers to the maximum height of the ribs in the center area of the strip. The center area of the strip refers to the area of 45%-50% of the width of the strip, and the areas on both sides of the center area are the two edges of the strip.

[0033] In step S1, the thickness of the strip, the width of the strip, and the initial plate shape state of the strip are further normalized, H|=(H-20) / 40, W|=(W-150) / 450, S|=S / 0.05, E|=E / 150, Z|=Z / 200, wherein H is the thickness of the strip, W is the width of the strip, S is the straightness, E is the edge wave height, and Z is the center wave height.

[0034] In step S2, the initial flattening process parameters include the convexity of the flattening roller, the furnace temperature, the tension, and the holding time.

[0035] The convexity of the flattening roller can actively exert a transverse pressure distribution on the INVAR strip to compensate for the expected deformation of the strip; the convexity of the flattening roller is adjusted according to the width (W) and the plate shape state of the INVAR strip.

[0036] According to the width of the strip, the convexity C of the initial flattening roller is set as follows:

[0037] The width of the strip (150mm-300mm), the convexity C of the initial flattening roller is set to 0.05mm-0.15 mm;

[0038] Strip width (300mm-450mm): the convexity C of the initial flattening roller is set in the range of 0.10mm-0.20mm;

[0039] Strip width (450mm-600mm): the convexity C of the initial flattening roller is set in the range of 0.15mm-0.30mm.

[0040] The setting rule of the convexity C of the initial flattening roller is that when the shape of the INVAR strip has a tendency of edge wave, i.e., the wave height of the edges of the INVAR strip is large, the convexity C is increased; when the shape of the INVAR strip has a tendency of center wave, i.e., the height of the ridges in the central region of the INVAR strip is large, the convexity C is decreased, or even set to be slightly concave; when the thickness of the INVAR strip is thin, the lower limit of the selection range is selected, and when the thickness of the INVAR strip is thick, the upper limit of the selection range is selected.

[0041] Adjusting the furnace temperature can realize stress relaxation of the Invar alloy and eliminate internal stress.

[0042] The furnace temperature includes the temperatures of the preheating zone, the soaking zone and the slow cooling zone, and the temperature value ranges and the functions of the zones are as follows:

[0043] The temperature value range of the preheating zone is 200℃-250℃, and the zone preheats the metal strip entering the interior of the heat treatment furnace to avoid thermal shock of the strip.

[0044] The temperature value range of the soaking zone is 300℃-400℃, and the soaking zone is the core zone of the furnace temperature, and the temperature precision requirement is ±5℃.

[0045] The temperature value range of the slow cooling zone is 250℃-300℃, and the zone is the exit zone of the heat treatment furnace, and can control the cooling rate of the strip to reduce thermal stress.

[0046] Adjusting the furnace temperature corresponds to adjusting the temperature of the soaking zone, and the adjustment rule of the furnace temperature is that when the thickness of the INVAR strip is thin, the lower limit of the temperature range is selected (to avoid overheating), and when the thickness is allowed, the upper limit of the temperature range is selected to pursue higher stress elimination effect.

[0047] The tension setting can maintain stable operation of the strip, but too high tension can induce or aggravate the center wave ridges.

[0048] The tension value range is 5N / mm 2 -50N / mm 2 , and the adjustment rule of the tension is that the thickness of the INVAR strip is a decisive factor, the lower limit is selected when the initial center wave height is large, the tension in the heat treatment furnace is slightly increased when the initial edge wave height is small and the center region has no ridges, and the absolute value of the tension is slightly increased when the width (W) is increased.

[0049] The heat treatment furnace further comprises a floating roller containing a counterweight, and the tension applied to the INVAR strip can be changed by adjusting the up-and-down position of the counterweight in the floating roller.

[0050] The tension adjustment method is to first measure the actual tension of the INVAR strip in real time by using a sensor, compare the measured actual tension with the tension set value to obtain a tension deviation, and then accurately adjust the up-and-down position of the counterweight in the floating roller according to the tension deviation by the controller of the heat treatment furnace, so as to change the tension applied to the INVAR strip.

[0051] The holding time can ensure that the strip reaches sufficient stress relaxation time at the temperature of the soaking zone, and the value range of the holding time is 200s-2000s. The adjustment rule of the holding time is that the thickness of the INVAR strip is the main factor, and the time can be slightly shorter when the temperature (T) is higher; and the time is taken as the upper limit when the stress is required to be completely eliminated.

[0052] Step S2 comprises calculating and adjusting the initial flattening process parameters according to the thickness of the strip, the width of the strip, and the initial strip flatness state normalization parameter,

[0053] The convexity C of the flattening roller is (0.05+0.25W|)×(1+0.4W|-0.6Z|)×(0.8+0.2H|),

[0054] The tension F is (40+5H|)×(1-0.3Z|-0.1S|)×(0.9+0.1W|),

[0055] The holding time t is (20+40H|)×(1+0.2Z|+0.15S|)×(1-0.05W|).

[0056] Further, a high-precision, high-temperature-resistant contact pressure sensor array is installed at the outlet of the heat treatment furnace, and the sensors are densely distributed along the transverse direction (width direction) of the strip with a spacing of 10m. In step S3, the normal contact pressure (Pi, N) of each point in the width direction of the strip is continuously measured and recorded when the strip passes through the sensor array;

[0057] The transverse pressure distribution data is integrated along the width direction to obtain an average value Pa;

[0058] The transverse pressure difference ΔP of the strip is defined as |ΔP|=|Pc-Pa| / Wc, where Pc is the center point pressure of the strip, and Pa is the average value of the transverse pressure of the strip. The transverse pressure difference can reflect the non-uniformity of the transverse pressure distribution of the strip. As shown in Table 1, according to the test data, the transverse pressure difference has a linear relationship with the center wave height of the strip, so the transverse pressure difference can be controlled to control the center wave height of the strip and whether there is a rib phenomenon in the center region of the strip.

[0059] Table 1: Experimental data of INVAR strip transverse pressure difference and middle wave height

[0060]

[0061] wherein ΔP is the transverse pressure difference of the strip, and Z is the middle wave height of the strip.

[0062] Step S4 comprises, S41: obtaining the transverse pressure difference |ΔP| of the strip;

[0063] S42: adjusting the flattening process parameters according to the transverse pressure difference |ΔP| of the strip and the target threshold P0, so that the strip shape state ΔP is less than the target threshold P0.

[0064] ΔP≥0 indicates that the middle wave height of the strip is high;

[0065] If 0≤ΔP

[0066] If P0≤ΔP

[0067] If ΔP≥ a1 triggers a second level adjustment;

[0068] First level adjustment: first choice: fine-tune the flattening roller crown (C), adjust in the direction of reducing the crown, adjust the crown width C1 to 0.01mm-0.05mm. Second choice / linkage: fine-tune the heat treatment furnace tension (F), adjust in the direction of reducing, adjust the tension amplitude F1 to 5N / mm 2 -10N / mm 2 , so as to reduce the longitudinal stress that induces the middle wave. After each adjustment is stable for a period of time, observe the change of ΔP after adjustment, if ΔP is improved, maintain; if ΔP is not improved or deteriorated, try another parameter adjustment or enter the second level adjustment. Second level adjustment (ΔP≥20N / mm or first level adjustment is invalid): linkage adjustment 1: significantly reduce the flattening roller crown, adjust the crown width C2 to 0.05mm-0.10mm, and reduce the heat treatment furnace tension (F), adjust the tension amplitude F2 to 10N / mm 2 -20N / mm 2 . Linkage adjustment 2: on the basis of adjustment 1, extend the holding time, adjust the holding time amplitude t1 to 60-200s, to promote the strip to relax more fully. When adjusting the flattening process parameters, closely monitor ΔP and the running state of the strip, especially to prevent strip breakage.

[0069] ΔP<0 indicates that the edge wave height of the strip is high;

[0070] If -P0≤ΔP

[0071] If -a1≤ΔP< -P0, trigger the first level adjustment;

[0072] If ΔP≥-a1, trigger the second level adjustment;

[0073] First level adjustment: First choice: fine-tune the convexity of the flattening roller (C), adjust in the direction of increasing convexity, adjust the convexity width C1 to 0.01mm-0.05mm. Second choice / linkage: fine-tune the tension in the heat treatment furnace (F), adjust in the direction of increasing, adjust the tension amplitude F1 to 5N / mm 2 -10N / mm 2 , to reduce the longitudinal stress that induces the middle wave. After each adjustment is stable for a period of time, observe the change of ΔP after adjustment, if ΔP is improved, maintain, if ΔP is not improved or deteriorated, try another parameter adjustment or enter the second level adjustment. Second level adjustment (ΔP≥-a1 or first level adjustment is invalid): Linkage adjustment 1: significantly increase the convexity of the flattening roller (C), adjust the convexity width C2 to 0.05mm-0.10mm, and increase the tension in the heat treatment furnace (F), adjust the tension amplitude F2 to 10N / mm 2 -20N / mm 2 . Linkage adjustment 2: on the basis of adjustment 1, extend the holding time, adjust the holding time amplitude t1 to 60s-200s, to promote more full stress relaxation of the strip. Closely monitor ΔP and the running state of the strip, especially to prevent strip breakage. Thus, through the above method, the INVAR strip is improved in the phenomenon of ribbing, so that the INVAR strip surface is flat.

[0074] In addition, the present application provides an INVAR strip ribbing improvement device, comprising a heat treatment furnace, a temperature control assembly, a flattening roller, a conveying assembly, and a contact pressure sensor array, the heat treatment furnace has an inlet and an outlet, the temperature control assembly, the flattening roller, and the conveying assembly are arranged in the heat treatment furnace, and the contact pressure sensor array is arranged at the outlet of the heat treatment furnace.

[0075] In the optional embodiments of the present application, the flattening roller is a crescent-shaped flattening roller, which has a convexity adjustment mechanism to adjust the convexity or concavity of the surface of the flattening roller.

[0076] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An INVAR strip ribbing improvement method, characterized in that: including, S1: obtaining the initial state of the strip, including the thickness of the strip, the width of the strip, and the initial plate shape state, the initial plate shape state including the straightness of the strip, the edge wave height, and the middle wave height; S2: adjusting the initial flattening process parameters according to the initial state of the strip, the flattening process parameters including the crown of the flattening roller, the furnace temperature, the tension, and the holding time; S3: placing the strip adjusted in S2 into a heat treatment furnace, monitoring the transverse pressure difference of the strip, measuring the pressure distribution at the outlet of the heat treatment furnace in real time and calculating the real-time transverse pressure difference |ΔP| of the strip; S4: dynamically adjusting the flattening process parameters in the process according to the transverse pressure difference of the strip to make the transverse pressure difference of the strip meet the target threshold value; Step S1 includes normalizing the thickness of the strip, the width of the strip, and the plate shape state of the initial strip, H|=(H-20) / 40, W|=(W-150) / 450, S|=S / 0.05, E|=E / 150, Z|=Z / 200, wherein H is the thickness of the strip, W is the width of the strip, S is the straightness, E is the edge wave height, and Z is the middle wave height; Step S2 includes calculating and adjusting the initial flattening process parameters according to the thickness of the strip, the width of the strip, and the normalized parameters of the initial plate shape state of the strip, including wherein the crown of the flattening roller C=(0.05+0.25W|)×(1+0.4W|-0.6Z|)×(0.8+0.2H|), the tension F=(40+5H|)×(1-0.3Z|-0.1S|)×(0.9+0.1W|), and the holding time t=(20+40H|)×(1+0.2Z|+0.15S|)×(1-0.05W|).

2. The method of improving the ridging of INVAR strip according to claim 1, characterized in that: The furnace temperature includes a preheating zone, a soaking zone, and a slow cooling zone, and adjusting the furnace temperature corresponds to adjusting the temperature of the soaking zone.

3. The method of improving the ridging of INVAR strip according to claim 1, wherein In step S3, the transverse pressure difference of the strip is monitored, including measuring the contact pressure of each point in the transverse width direction of the strip at the outlet of the heat treatment furnace, calculating the transverse pressure difference |ΔP| of the strip, |ΔP| = |(Pc - Pa)| / Wc, Pc is the center point pressure of the strip, Pa is the average pressure of the strip, and Wc is the transverse width of the strip.

4. The method of improving the ridging of INVAR strip according to claim 1, wherein: Step S4 includes, S41: obtaining the transverse pressure difference |ΔP| of the strip; S42: adjusting the flattening process parameters according to the transverse pressure difference |ΔP| of the strip and the target threshold value P0, so that the plate shape state |ΔP| is less than the target threshold value P0.

5. The method of improving the ridging of INVAR strip according to claim 4, wherein: In step S42, when a0≤|ΔP|<a1, adjust the flattening roller crown amplitude C1; if |ΔP| does not change, adjust the tension amplitude F1; If |ΔP| does not change, adjust the flattening roller crown amplitude C2 and the tension amplitude F2 at the same time; When a1≤|ΔP|, adjust the flattening roller crown amplitude C2 and the tension amplitude F2 at the same time, and if |ΔP| does not change, adjust the holding time amplitude t1.

6. The method of improving the ridging of INVAR strip according to claim 5, wherein: C1

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