A die lip opening method

Abstract

The application relates to the technical field of die lip opening degree, and discloses a die lip opening degree method, which comprises an intelligent die, the intelligent die comprises a fixed half-haaf module, an aviation socket arranged on the top surface of the fixed half-haaf module, and a horizontal section melt pipe above the fixed half-haaf module. The die lip opening degree method utilizes the special die lip shape of the application to preform a cast sheet required by equal stress of each particle in a transverse drawing process, and the cast sheet is forced to approach a state through long-time manual adjustment. The original logic of the die lip hardware and the software programming required by specification switching is accurately quantified on the basis of theoretical calculation, obstacles for one-key start of the process parameter menu are cleared, the die lip opening degree is ensured by adopting a servo electric cylinder with a positioning accuracy of 0.01 millimeter, the laborious and time-consuming adjustment process of dozens of die lip adjusting bolts in the traditional process is avoided, machine adjustment waste caused by specification replacement is greatly reduced, and the equipment utilization rate is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of mold lip opening technology, specifically a method for adjusting the mold lip opening. Background Technology

[0002] In existing biaxial stretching processes, whether dry or wet, stepwise or synchronous, manual intervention is required to control the cross-section of the casting from the die head during the transverse stretching stage. This control aims to make the cross-section of the casting thicker in the middle and thinner at the edges to counteract the tendency of the transverse stretching process to be thinner in the middle and thicker at the edges.

[0003] On the film-making line, if the thickness is found to be bulging at a certain point before winding, the die head needs to be pushed back to the corresponding position to press down the die lip adjusting bolt; conversely, it needs to be raised. The adjustment amount and position are entirely based on experience.

[0004] Biaxially stretched lithium-ion battery separators, whether dry or wet, suffer from poor thickness, porosity, thermal shrinkage, air permeability, mechanical strength, and appearance consistency, and are recognized as a global problem. The root cause lies in the lack of in-depth research on the internal mechanism of the biaxial stretching process, which is known as the black box theory.

[0005] Current technology uses a fixed die lip opening for a single die head, generally suitable only for a small thickness range. If the thickness range is large, the die head needs to be replaced, requiring the machine to be shut down and cooled to below 50°C before resuming operation. Current technology typically avoids changing the die head, instead using other process parameters to compensate. For example, if the material quantity is insufficient, the melt pump feed rate needs to be increased, while the draw ratio is reduced or the machine speed is slowed or increased. Such practices limit other product properties. Furthermore, the upward compatibility of using a narrow-slit, wide-lip die head to produce thick films is limited. Using a die head with a wider lip opening to produce thin films requires increasing the speed difference before the casting cools to obtain a thinner casting, thus reducing the die lip opening's plastic constraint on the casting. In short, although products of the required specifications can eventually be produced, their performance controllability and stability become very poor, representing a non-tailor-made match. The required adjustment and stabilization time are also lengthened, increasing the cost of setup waste.

[0006] Currently, the manual adjustment of the corresponding adjusting bolts on the die head is based on the shape presented by the X-ray thickness scanner before winding, which determines the bolt position and the lifting or pressing force. The adjustment process relies entirely on the adjuster's personal experience to control the adjustment force and position, without quantitative data. The disadvantage is that it can only be approached infinitely close to the ideal state through continuous overcorrection. Even with automatic die heads using electrically heated bolts, it is still necessary to first manually adjust to roughly the ideal shape before the electrically heated bolts can be automatically adjusted. Because the adjustment range of the heated bolts is very small, it can only achieve fine-tuning, so its effect is not significant. Most manufacturers still mainly use non-automatic die heads.

[0007] Because the original technology needs a long adjustment time to slowly approach the required state after starting, the longer the continuous production time, the smaller the proportion of coarse adjustment loss, and if different thickness specifications of products are frequently replaced on the same line, the proportion of machine adjustment loss is very high, so that the cost cannot be controlled. Gradually forming an industry consensus that only one specification is opened on a line, which is the root cause of many manufacturers opening many lines and causing a large amount of inventory backlog to occupy funds. This mode cannot achieve production according to sales, which brings great financial pressure and market risk to enterprises, and is also the main reason why the diaphragm market always lives in a period of overcapacity.

[0008] The current production process only adapts to the situation of continuous expansion of market size and shortage of supply, but the market will always fluctuate large or small due to various factors, resulting in that the diaphragm industry cannot adjust in time according to market changes to reduce operational risk like traditional manufacturing industry.

[0009] The present application discloses the formation reason of the phenomenon of thin in the middle and thick on both sides existing in the horizontal drawing process of the wet two-way stretched diaphragm for lithium ion battery through the research and exploration of the engineering stress of the film material in the horizontal drawing process, and provides a targeted solution to eliminate the phenomenon of low control precision, long time consumption and large waste caused by the original process control method according to the characteristics, and realizes stable output of high consistency products by replacing manual control with engineering and digital control method.

[0010] Therefore, a die lip opening method is provided. SUMMARY

[0011] Technical problems to be solved

[0012] In view of the defects of the prior art, the present application provides a die lip opening method, which has the advantages of breaking the existing diaphragm enterprise survival logic, realizing low-cost and fast switching of varieties, greatly reducing machine adjustment waste generated by machine adjustment time, realizing production according to sales, effectively reducing the capital occupation caused by inventory, etc., and solves the problem that only by continuously overcorrecting to approach the ideal state, even if the automatic die head with electric heating screw is used, it must be manually adjusted to approach the ideal shape first, and then automatically adjusted by the electric heating screw, because the adjustment range of the heating screw is very small, only fine adjustment can be realized, so the effect is not good.

[0013] Technical scheme

[0014] To achieve the above object, the present application provides the following technical scheme:

[0015] A die lip opening method, comprising an intelligent die head, the intelligent die head comprising a fixed half module and an aviation socket arranged on the top surface of the fixed half module;

[0016] And a horizontal section melt pipe arranged above the fixed half die module;

[0017] A vertical melt pipe is arranged vertically between the horizontal section melt pipe and the fixed half die module, and an adjustable half die module is arranged below the front end of the fixed half die module;

[0018] A group of heating bolts are uniformly arranged in the middle of the inclined surface at the top end of the adjustable half die module, and servo electric cylinders are symmetrically arranged on the left and right sides of the group of heating bolts;

[0019] The die lip opening method using the above intelligent die lip includes the following steps:

[0020] Step one: first analyze the existing product state;

[0021] Step two: design an intelligent die lip to achieve a new die lip structure according to the analysis data;

[0022] Step three: quantify the correlation between various process parameters and deduce the parameter relationship of the die lip gap;

[0023] Step four: design a die lip opening calculation method according to the parameter relationship in step three, modify the adjustable parameters on the touch screen, and automatically calculate the die lip opening with PLC and display the data on the touch screen to realize one-key start of the process parameter menu and complete the die lip opening.

[0024] Preferably, the top end of the vertical melt pipe is connected with the front end of the horizontal section melt pipe through a communication member, and the bottom end of the vertical melt pipe is connected with the inside of the fixed half die module.

[0025] Preferably, the contact position of the servo electric cylinder and the adjustable half die module is provided with a heat insulation pad.

[0026] Preferably, the heat insulation pad is a high-strength heat insulation material, which is a carbon fiber reinforced carbon aerogel composite material.

[0027] Industrial phenolic resin is used as a carbon precursor, high-boiling alcohol is used as a pore-forming agent, and a high-pressure curing environment is used to promote the uniform growth of the aerogel network structure and the generation of large particle combination area and hierarchical pore structure.

[0028] Phenolic fibers with good matching with the aerogel matrix during carbonization are selected as reinforcing bodies, and through fiber / matrix interface regulation, the synergistic shrinkage of the matrix and the fibers during carbonization and the strong chemical interface bonding of the fiber / matrix are realized.

[0029] Preferably, the output part of the servo electric cylinder is linked with nitrogenized austenitic stainless steel material, and the cylinder body connecting bolt is also made of low-thermal-conductivity stainless steel material and is provided with a carbon fiber reinforced carbon aerogel composite material pad.

[0030] Preferably, the step one of the analysis of the existing product state is embodied as:

[0031] a. analysis of the thickness state of the cast sheet after transverse stretching under the initial lip state;

[0032] b. then determine the reasonable state of the lip shape after adjustment by the lip adjustment bolt;

[0033] c. further determine the actually required cross-sectional shape of the cast sheet.

[0034] Preferably, the parameter relationship of the lip slit width in the step three is: lip slit width: b = BRδa (1 + β / c) / l;

[0035] b is the lip slit width, B is the finished product width, R is the longitudinal stretching ratio, δ is the film thickness, α is the film true volume ratio, β is the oil / powder ratio, c is the oil / powder relative density, and l is the lip slit length.

[0036] Compared with the prior art, the present application provides a die lip opening method, which has the following beneficial effects:

[0037] 1. The die lip opening method uses the unique die lip shape of the present application to preform the cast sheet required for equal stress of each particle in the transverse stretching process, without the need for artificial adjustment for a long time to approach the state (which still cannot eliminate the generation of defective products near the center line). On the basis of theoretical calculation, the original logic of the die lip hardware and the software programming required for specification switching is accurately quantified, which removes the obstacles for the menu-based one-key start of process parameters.

[0038] 2. The die lip opening method uses a servo cylinder with a positioning accuracy of 0.01 mm to ensure the lip opening, which eliminates the laborious and time-consuming adjustment process of dozens of lip adjustment bolts in traditional processes, greatly reduces the large amount of machine adjustment waste generated by changing specifications, and greatly improves the equipment utilization rate. DETAILED DESCRIPTION

[0039] Figure 1 Stress analysis diagram for the phenomenon of thin in the middle and thick on both sides of the diaphragm during transverse stretching of the diaphragm of the present application;

[0040] Figure 2 Stereoscopic diagram of the intelligent die structure of the present application;

[0041] Figure 3 Diagram of the relationship between the die opening adjustment and related process parameters of the present application;

[0042] Figure 4 Diagram of the transverse thickness distribution of the X-ray thickness detector of the present application;

[0043] Figure 5 Fig. 9 is a schematic diagram of the cumulative effect of the intermediate thinning in the present application;

[0044] Figure 6 Fig. 10 is a schematic diagram of the interlayer state during low-tension winding in the present application;

[0045] Figure 7 Fig. 11 is a schematic diagram of the influence of factors other than the die lip in the present application;

[0046] Figure 8 Fig. 12 is a schematic diagram of the thickness of the cast sheet after transverse stretching in the initial die lip state in the present application;

[0047] Figure 9 Fig. 13 is a schematic diagram of the fact that the conventional die lip can only approach but cannot match the ideal cross section in the present application;

[0048] Figure 10 Fig. 14 is a schematic diagram of the linear gradient relationship between the thickness from the center axis to the rail clamp in the present application.

[0049] In the figure: horizontal melt pipe 1, vertical melt pipe 2, fixed half-block 3, aviation socket 4, adjustable half-block 5, heat insulation pad 6, heating screw 7, servo cylinder 8. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings 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. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0051] Please refer to Figures 1-10 ;

[0052] A die lip opening method, comprising an intelligent die, the intelligent die comprising a fixed half-block 3 and an aviation socket 4 arranged on the top surface of the fixed half-block 3;

[0053] and a horizontal melt pipe 1 arranged above the fixed half-block 3;

[0054] A vertical melt pipe 2 is vertically arranged between the horizontal melt pipe 1 and the fixed half-block 3, and an adjustable half-block 5 is arranged below the front end of the fixed half-block 3, the top end of the vertical melt pipe 2 is connected with the front end of the horizontal melt pipe 1 through a communication member, and the bottom end of the vertical melt pipe 2 is connected with the inside of the fixed half-block 3;

[0055] A group of heating screws 7 are uniformly arranged at the middle position of the inclined surface of the top end of the adjustable half-block 5, and servo cylinders 8 are symmetrically arranged on the left and right sides of the group of heating screws 7.

[0056] The servo cylinder 8 is provided with a heat insulation pad 6 at the contact position with the adjustable half-haaf module 5;

[0057] The heat insulation pad 6 is a high-strength heat insulation material, which is a carbon fiber reinforced carbon aerogel composite material:

[0058] Industrial phenolic resin is used as a carbon precursor, high-boiling alcohol is used as a pore-forming agent, and a high-pressure curing environment is used to promote the uniform growth of the aerogel network structure and the generation of large particle combination area and hierarchical pore structure;

[0059] Phenolic fibers with good matching with the aerogel matrix during carbonization are selected as reinforcing bodies, and through fiber / matrix interface regulation, the synergistic shrinkage of the matrix and the fibers during carbonization and the strong chemical interface combination of the fiber / matrix are realized;

[0060] The output part of the servo cylinder 8 is linked with a nitrogenized austenitic stainless steel material, and the cylinder connecting bolts are also made of a low-thermal-conductivity stainless steel material and a carbon fiber reinforced carbon aerogel composite material pad.

[0061] The die lip opening degree method using the above intelligent die includes the following steps:

[0062] Step one: first, analyze the existing product state;

[0063] The analysis of the existing product state specifically embodies:

[0064] a. Analyze the thickness state of the cast sheet after transverse stretching under the initial die lip state;

[0065] b. Then determine the reasonable state of the die lip shape after adjustment by the die lip adjustment bolt;

[0066] c. Further determine the actual required cast sheet cross-sectional shape;

[0067] Step two: design an intelligent die according to the analysis data to achieve a new die lip structure;

[0068] Step three: quantify the correlation between various process parameters, and derive the parameter relationship of the die lip gap width as b = BRδa(1 + β / c) / l;

[0069] b is the die lip gap width, B is the finished product width, R is the longitudinal stretching ratio, δ is the film thickness, α is the film true volume ratio, β is the oil / powder ratio, c is the oil / powder relative density, and l is the die lip gap length;

[0070] Step four: according to the parameter relationship of step three, the die lip opening calculation method is designed, the adjustable parameters can be modified on the touch screen, the PLC automatically calculates the die lip opening and displays the data on the touch screen, and the process parameter menu is realized to achieve one-key start, and the die lip opening is completed.

[0071] From Figure 1 It can be seen from the above that the edge particles are more than the particles along the x-axis direction of the center line, the transverse stretching force and the reaction force are equal in size and opposite in direction and perpendicular to the center line, if the angle between the edge line and the center axis is θ, l=Lcosθ, the relationship between the stress σ along the center axis and the stress σ' along the track chain is a=bcosθ, since the action force and the reaction force are equal in size and opposite in direction, that is, F=F',:

[0072] Because σ'>σ, the stress along the center axis is greater than the stress along the track chain, so the stretching process appears to be thin in the middle and thick on both sides;

[0073] If you want to avoid this phenomenon, you should try to make σ=σ';

[0074] The film thickness along the center line is d, and the film thickness along the track chain is D, because F=F', σ=F' / d*l, σ'=F / D*L, if you want σ=σ', D*L=d*l (area is equal), because l=Lcosθ, so D=dcosθ.

[0075] The existing die lip is a straight narrow slit, and in engineering, the phenomenon of thin in the middle and thick on both sides after the transverse stretching is needed to be artificially adjusted by lifting or pressing the die bolt to achieve uniform transverse thickness, but this is only a qualitative method based on engineering experience, which is obviously not accurate enough for high-end films, because the film lip is manufactured and processed as a straight mouth, the adjustment mechanism of the bolt is the micro-elastic deformation of the lip, and the lip shape adjusted according to the principle of thick in the middle and thin on both sides is closer to a straight line on both sides, and closer to an arc curve in the middle. The demand for replacing the linear curve with an arc curve can only be approximate, so it is difficult to obtain the ideal shape no matter how the film surface is adjusted;

[0076] With the increase of the total winding length, the number of layers also increases, and the trend of herringbone and wrinkling in the winding direction near the thickness peak value also becomes more obvious, if the flattening roller is not used and the tension is increased, dead folds and diagonal lines will be formed;

[0077] Another method is to adjust the winding tension to the minimum, called micro-tension or even zero tension, through the interlayer gap to eliminate the cumulative error caused by the thickness of the transverse particles due to the inconsistent roll diameter, and the softness of the film roll covers the defects caused by the accumulation of thickness deviation. This covering is only temporary. PE materials are more prone to creep than paper, PET, PP, etc. in dry and normal temperature conditions, and the density of the thick area is large and the density of the thin area is small. With the extension of time and the influence of environmental temperature, the thin area will shrink inward and the thick area will not have space to shrink. The outer diameter of the thick area will be larger than that of the thin area. When the film is used, the film will be long and loose in the thick area. If it is at the edge, it will be collapsed and curved. If it is not at the edge, it will form a loose groove. If a large tension is used and a flattening roller is used to eliminate wrinkles, it will make the longitudinal thermal shrinkage and normal temperature shrinkage more serious. The appearance of the film roll is very poor after more than 1000 meters. The film placed on the roll has two peaks on both sides of the adjacent center line, forming two deep grooves. This is because the longitudinal length of the area is longer than the adjacent position due to the large roll diameter. If it is coated, it will appear coating leakage. If it is slit, it will have serious edge hanging or bending.

[0078] Under the current technical system, these two high points cannot be eliminated. If the cast sheet slips locally during longitudinal stretching or the warm field is uneven during transverse stretching, or due to improper adjustment of the die head, the convex peak in the middle may deviate to one side and show irregular patterns without fixed position. This is the current situation of most existing production lines.

[0079] The thickness of the cast sheet after transverse stretching under the initial die lip state is as follows: Figure 8 From the stress analysis, the stress gradient of the middle and both sides depends on the expansion angle θ of the transverse stretching track,

[0080] The analysis shows that the stress on the film in the middle of the stretching zone and the track clamping opening has a linear relationship, and the die lip is flat. Then, the die lip opening is adjusted by the adjusting screw according to the needs, and the adjusting principle is the micro-elastic deformation of the lip metal component;

[0081] The micro-elastic deformation of the die lip under the action of the screw and the ideal linear gradient exist as Figure 9 The distance of the middle point is relatively small, which is consistent with the results measured by the X-ray thickness gauge. The two thick points are ideally in the middle and symmetrically arranged. If the adjustment force of the die screw is uneven or the transverse stretching warm field is uneven, the X-ray thickness gauge will show a non-symmetrical pattern, which is irregular and makes it difficult to find the corresponding position during adjustment of the die screw. Therefore, the host of this station needs long-term training and the problem of difficult job replacement and heavy dependence on people.

[0082] Since the theta angle of the cross drawing machine is basically fixed after the design and manufacture, the lip of the die can be calculated to have linear gradients in the middle and on both sides, ensuring that the cross section of the cooled and shaped cast strip meets the stress balance in each area on the film surface after being fed into the cross drawing machine, without the need for manual adjustment of the die lip bolts to approach the ideal cross section shape, eliminating the need for overcorrection to achieve the ideal shape.

[0083] The present application retains the automatic heating bolt function of the die to achieve local automatic correction. The thickness specification switching adds two servo cylinders to the two sides of the adjustable die lip half-Hafer to accurately control the die lip opening distance according to the theoretical discharge amount of the product, which can be switched online without stopping the machine and manually adjusting each bolt, making the online specification switching simple, fast and accurate, and realizing true process standardization and packaging, which removes a major obstacle on the road to integration;

[0084] Wet diaphragm product manufacturing is known for its many process parameters, with about 80% of the key process parameters concentrated in the stretching section from batching to stretching. Many of these parameters have strong correlation and complementarity on the production line. Die parameters belong to equipment parameters, and once the scope of some parameters is determined, the scope is relatively fixed. Exceeding this range may not necessarily produce a product, but the controllability and reliability of the product performance will be greatly reduced. Therefore, finding the quantitative relationship between parameters is the key to ensuring stable production and making high-consistency products.

[0085] The die lip opening in the prior art is fixed, and manual intervention is required to adjust the die lip bolts according to the product condition. This intervention is non-digital. The present application quantifies the correlation between various process parameters, as shown in Figure 3 The length l of the die lip opening is relatively fixed. In order to adapt to the switching of different product specifications, the present application arranges the relationship between the related process parameters in the above table as b = BRδa(1 + β / c) / l. The calculation table sets fixed parameters and adjustable parameters. The adjustable parameters can be modified on the touch screen according to different process packages. The PLC automatically calculates the die lip opening and displays the data on the touch screen to make the process parameters menu-driven and one-key start, which is convenient for operation and storage, and also greatly shortens the start-up and adjustment time and produces high-consistency products.

[0086] Analysis of the stress on the membrane in the cross-drawing section shows that the desired shape of the cast strip cross section has a linear gradient relationship D = d x cosθ from the center axis to the track clamp.

[0087] D = h, d = H, that is, h = Hcosθ, and must satisfy the area of the original rectangular cross section is equal to h = H - (H - b) x 2, regardless of the thickness of the product specifications change, as long as the device transverse stretching track opening angle is a fixed value must satisfy h = Hcosθ, the die adjustable half-lip grinding processing of the tilt angle is: α = arctan4 (H - b) / l.

[0088] The beneficial effects of the present application are:

[0089] The die lip opening method, using the unique die lip shape of the present application to preform the cast piece required for equal stress of each particle in the transverse drawing process, without the need for artificial adjustment for a long time to force close to the state (the state near the center line still cannot eliminate the production of defective products) On the basis of theoretical calculation, the original logic of the die lip hardware and the software programming required for specification switching is accurately quantified, which clears the obstacles for the process parameter menu one-key start, ensures the die lip opening by using the positioning accuracy of 0.01mm servo cylinder 8, avoids the laborious and time-consuming adjustment process of traditional process through dozens of die lip adjusting bolts, greatly reduces the large amount of machine adjustment waste generated by changing specifications, and greatly improves the utilization rate of the equipment.

[0090] Although embodiments of the present application have been shown and described, it will be understood by those having ordinary skill in the art that various changes, modifications, substitutions and alterations can be made hereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1.A die lip opening method, comprising an intelligent die, the intelligent die comprising a fixed half die module (3) and an aviation socket (4) arranged on the top surface of the fixed half die module (3); and a horizontal section melt pipe (1) arranged above the fixed half die module (3); a vertical melt pipe (2) vertically arranged between the horizontal section melt pipe (1) and the fixed half die module (3); and an adjustable half die module (5) arranged below the front end of the fixed half die module (3); a group of heating bolts (7) uniformly arranged in the middle of the inclined surface of the top end of the adjustable half die module (5); and servo electric cylinders (8) symmetrically arranged on the left and right sides of the group of heating bolts (7); the die lip opening method using the above intelligent die comprises the following steps: Step 1: firstly, analyzing the existing product state; Step 2: designing an intelligent die according to the analysis data to achieve a new die lip structure; Step 3: quantifying the correlation between various process parameters, and deducing the parameter relationship of the die lip gap width; the parameter relationship of the die lip gap width is b=BRδα (1+β / c) / l; b is the die lip gap width, B is the finished product width, R is the longitudinal stretching ratio, δ is the film thickness, α is the film true volume ratio, β is the oil / powder ratio, c is the oil / powder relative density, and l is the die lip gap length; Step 4: designing a die lip opening calculation method according to the parameter relationship of Step 3, and modifying the adjustable parameters on the touch screen, so that the PLC automatically calculates the die lip opening and displays the data on the touch screen, and the process parameter menu is realized to achieve one-key start, and the die lip opening is completed. The top end of the vertical melt pipe (2) is connected with the front end of the horizontal section melt pipe (1) through a communication member, and the bottom end of the vertical melt pipe (2) is connected with the inside of the fixed half die module (3). characterized in that The contact position of the servo electric cylinder (8) and the adjustable half die module (5) is provided with a heat insulation pad (6). The heat insulation pad (6) is a high-strength heat insulation material, which is a carbon fiber reinforced carbon aerogel composite material. Industrial phenolic resin is used as a carbon precursor, high-boiling alcohol is used as a pore-forming agent, and a high-pressure curing environment is used to promote the uniform growth of the aerogel network structure and the generation of large particle combination area and hierarchical pore structure. Phenolic fibers with good matching with the aerogel matrix during carbonization are selected as reinforcing bodies, and through fiber / matrix interface regulation, the synergistic shrinkage of the matrix and the fibers during carbonization and the strong chemical interface bonding of the fiber / matrix are realized. The output part of the servo electric cylinder (8) is linked with a nitrogenized austenitic stainless steel material, and the cylinder connecting bolts are also made of a low-thermal-conductivity stainless steel material and a carbon fiber reinforced carbon aerogel composite material pad. The analysis of the existing product state in Step 1 specifically embodies as follows: a, analyzing the thickness state of the cast sheet after transverse stretching under the initial die lip state; b, then determining the reasonable state of the die lip shape after adjustment by the die lip adjustment bolt; c, further determining the actual required cast sheet cross-sectional shape. ​ ​ ​ 2. A die lip opening method according to claim 1, wherein ​ 3. The die lip opening method of claim 1 wherein, ​ 4. The die lip opening method of claim 3, wherein ​ ​ ​ 5. A die lip opening method according to claim 4, wherein ​ 6. The die lip opening method of claim 1 wherein, ​ ​ ​ ​

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