Plate production line

Abstract

The utility model relates to a plate production line. The plate production line comprises an extruder, a mold and a calender which are arranged in the machining direction, the extruder comprises a machine barrel and two screws, the two screws are meshed with each other and rotationally arranged in the machine barrel with the respective central axes as rotating shafts, the diameter of each screw is gradually reduced from the feeding end to the discharging end, and the diameter of each screw is larger than that of the machine barrel. And the included angle between the rotating shafts of the two screw rods is 10 minutes to 1 degree 20 minutes. The production line is improved according to the characteristics of PET materials, the plasticizing effect of the PET materials is improved, the quality of PET plates is guaranteed, the productivity of the production line is improved, and energy consumption is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of plate manufacturing, and in particular relates to a plate production line. Background Art

[0002] PVC sheets, currently widely used in the market, have numerous shortcomings. First, PVC materials are environmentally unfriendly and can release harmful substances during production and use, impacting indoor air quality. Second, PVC sheets have relatively low wear and heat resistance, making them prone to fading and deformation after long-term use. Furthermore, the recycling rate of PVC sheets is low, leading to resource waste and environmental pollution. Therefore, the search for more environmentally friendly and durable alternative materials has become a pressing need for industry development.

[0003] Polyester (PET) is an emerging alternative material with superior performance. Firstly, PET excels in environmental protection, with extremely low emissions and harmful substances released during production, meeting the requirements of modern green buildings. Secondly, PET's wear and pressure resistance surpasses that of traditional PVC, resulting in a longer service life. PET also exhibits excellent heat resistance. Furthermore, PET's high recyclability reduces the environmental impact of production, aligning with the concept of sustainable development.

[0004] Despite the numerous advantages of PET, there are currently no high-capacity production lines suitable for PET sheet. This is primarily due to the fact that the equipment and processes of existing high-capacity production lines are primarily designed for other types of materials. Due to the unique physical properties of PET, when using existing high-capacity production lines for production, the mixing, extrusion, and molding processes may not meet the plasticization requirements of PET, resulting in unstable product quality and low output. Furthermore, existing sheet production lines use co-rotating parallel twin-screw extruders, which require high-speed operation but have low production capacity and high power consumption. This makes high-capacity production of PET sheet impossible, limiting its promotion and application. Utility Model Content

[0005] In response to at least one shortcoming in the related art, the present invention provides a plate production line, which is improved according to the characteristics of PET materials, thereby improving the plasticizing effect of PET materials, ensuring the quality of PET plates, increasing the production capacity of the production line and reducing energy consumption.

[0006] The utility model provides a plate production line, comprising an extruder, a die and a calender arranged along a processing direction. The extruder comprises a barrel and two screws. The two screws are meshed with each other and are rotatably arranged in the barrel with their respective central axes as rotation axes. The diameter of each screw gradually decreases from the feed end to the discharge end, and the angle between the rotation axes of the two screws is 10' to 1°20'.

[0007] In some embodiments, the aspect ratio of each screw is 25:1 to 35:1, where the aspect ratio is the ratio of the length of the screw to the average of the diameter at the feed end and the diameter at the discharge end.

[0008] In some embodiments, the length of each screw is 3-7 m.

[0009] In some embodiments, the calendering machine includes a frame and multiple groups of calendering rollers arranged on the frame, the calendering rollers located above the slab conveying path are upper calendering rollers, and the calendering rollers located below the slab conveying path are lower calendering rollers. Each group of calendering rollers includes an upper calendering roller and a lower calendering roller correspondingly arranged above and below, or only includes one lower calendering roller. A conveying device is provided between at least two adjacent groups of calendering rollers; the conveying device includes multiple rollers and a conveyor belt wrapped around the multiple rollers, the surface of the conveyor belt located above the multiple rollers is the conveying surface, the upper end surfaces of the multiple rollers are flush to keep the conveying surface flat, and the plane where the conveying surface is located is tangent to the roller surfaces of the two lower calendering rollers on both sides of the conveyor belt.

[0010] In some embodiments, the conveying device also includes a roller mounting member provided on the frame, the roller mounting member is formed with a mounting groove, and each roller is respectively formed with a mounting shaft at both ends, the mounting shaft is provided in the mounting groove and supported by the bottom of the mounting groove to mount the roller on the frame.

[0011] In some embodiments, a bolt hole connected to the bottom of the mounting groove is opened in the roller mounting member, and an adjustment bolt is installed in the bolt hole in a threaded manner. The end of the adjustment bolt extends into the mounting groove from the bottom of the mounting groove and supports the roller.

[0012] In some embodiments, the conveying device further includes a first drive motor and a drive roller mounted on the frame, the conveyor belt surrounds a plurality of rollers and the drive roller, and the first drive motor is connected to the drive roller.

[0013] In some embodiments, at least one calendering roller group among the multiple calendering roller groups includes only one lower calendering roller, and a first baking device is provided above the calendering roller group including only one lower calendering roller.

[0014] In some of the embodiments, a displacement sensor for measuring the lifting distance of the upper calender roller is arranged corresponding to each upper calender roller, a second driving motor for controlling the lifting of the upper calender roller is arranged on the frame, and the displacement sensor is electrically connected with the second driving motor.

[0015] In some of the embodiments, a cooling bracket, a traction machine and a cutting device are arranged at the rear end of the calender, and a second baking device is further arranged at the front end of the traction machine.

[0016] Compared with the prior art, the plate production line has the advantages and positive effects that:

[0017] (1) The plate production line provided by at least one embodiment of the plate production line improves the screw structure in the extruder according to the characteristics of the PET material, can provide suitable shear force for PET material plasticization, improves the plasticization effect and plasticization efficiency, and can reduce the energy consumption of the extrusion process;

[0018] (2) The plate production line provided by at least one embodiment of the plate production line is provided with a conveying device between adjacent calender roller groups, the conveying device adopts the form of a conveying belt to convey the plate blank, and the inclination of the conveying belt is adjustable, which can effectively avoid the deformation of the surface of the plate blank and ensure the flatness of the final PET plate;

[0019] (3) The plate production line provided by at least one embodiment of the plate production line is provided with baking devices in the calender and in front of the traction machine according to the change of the material performance in the PET plate production process, can heat the plate blank according to actual needs, and avoids the problem of plate cracking due to the brittleness of the plate blank in the calendering and cutting process; BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, and the schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1a It is a side view of the plate production line provided by the embodiment of the present application;

[0022] Figure 1b It is a top view of the plate production line provided by the embodiment of the present application;

[0023] Figure 2 It is a structural schematic view of the extruder in the embodiment of the present application;

[0024] Figure 3 It is a structural schematic view of the double screw in the embodiment of the present application;

[0025] Figure 4aThis is a schematic diagram of the distribution of various sections along the axial direction of the screw in the embodiment of the present application;

[0026] Figure 4b for Figure 4a Cross-sectional view of the middle AA site;

[0027] Figure 4c for Figure 4a Cross-sectional view of the mid-BB area;

[0028] Figure 5a This is a structural diagram 1 of a calender in an embodiment of the present application;

[0029] Figure 5b The structure of the calender in the embodiment of this application is shown in FIG. Figure 2 ;

[0030] Figure 5c A side view of a calender in an embodiment of the present application;

[0031] Figure 6 for Figure 5c A partial enlarged view of the middle part C;

[0032] Figure 7 This is a structural diagram 1 of the conveying device in an embodiment of the present application;

[0033] Figure 8 This is a schematic diagram of the structure of the transmission device in the embodiment of the present application. Figure 2 ;

[0034] Figure 9a This is a schematic diagram of the structure of the conveying device after the conveyor belt is removed in an embodiment of the present application, so as to fully illustrate the structure of the roller mounting member;

[0035] Figure 9b for Figure 9a A partial enlarged view of the middle portion D, wherein the roller mounting portion is partially cut away to show the internal bolt holes;

[0036] Figure 10 This is a schematic diagram of one side of the calender equipped with a displacement sensor in an embodiment of the present application.

[0037] In the picture:

[0038] 1. Loading machine;

[0039] 2, extruder; 21, barrel; 211, barrel jacket; 22, screw; 221, preheating section; 2211, feeding section; 2212, first temperature increasing section; 2213, second temperature increasing section; 222, first mixing section; 223, first venting section; 224, compression section; 225, second mixing section; 226, plasticizing section; 2261, backflow section; 2262, material blocking section; 2263, backflow tank; 227, second venting section; 228, discharging section; 2281, first discharging section; 2282, second discharging section; 229, first transition section; 2210, second transition section; 23, stirring assembly; 231, toothed protrusion; 24, venting device; 25, heating collar;

[0040] 3, mold;

[0041] 4, calender; 41, frame; 42, calender roll set; 421, upper calender roll; 422, lower calender roll; 43, conveying device; 431, idler roll; 4311, mounting shaft; 432, conveying belt; 433, idler roll mounting; 4331, mounting groove; 4332, bolt hole; 434, adjusting bolt; 435, first driving motor; 436, driving roll; 437, guide roll; 44, first baking device; 45, elevator; 46, connecting rod; 47, displacement sensor; 48, second driving motor;

[0042] 5, cooling bracket;

[0043] 6, second baking device;

[0044] 7, haul-off machine;

[0045] 8, cutting device;

[0046] 9, ground travel track. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments will be described clearly and completely below with reference to the 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 of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0048] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean that it refers to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. Those skilled in the art understand explicitly and implicitly that the embodiments described in the present application can be combined with other embodiments without conflict.

[0049] In the description of this utility model, it should be understood that the terms "upper," "lower," "front," "back," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features referred to.

[0050] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0051] This application provides a sheet production line, which is particularly suitable for producing PET sheets, but it is understandable that other types of sheets can also be produced according to actual conditions. Figure 1a and Figure 1b As shown, in some embodiments, the plate production line includes a loader 1, an extruder 2, a mold 3, a calender 4, a cooling bracket 5, a traction machine 7, a cutting device 8, etc. along the processing direction.

[0052] The material is mixed by the feeder 1 and then enters the extruder 2 for processing. The extruder 2 used in the embodiment of the present application is a twin-screw extruder. The material is transported forward in the extruder 2 by the rotation of the screw. During the forward movement of the material, the material is heated, sheared and compressed by the screw so that the material is fully mixed, melted and plasticized, providing the prerequisite for the subsequent forming of the plate.

[0053] Different materials present different characteristics in the process of processing, for example, PET material has higher hardness and intensity, makes it more brittle and rigidity is large, and glass transition temperature is higher, needs higher processing temperature, but good environmental protection.When adopting existing forcing machine to extrude at PET material, plasticizing process is difficult to control, and the problem of plasticizing is not enough or over-plasticizing occurs easily, and current fluctuation is large, and product quality is unstable and production capacity is low.For the problems referred to above, the application first starts with forcing machine 2 and improves production line, improves the plasticizing effect of PET material, is conducive to improving the quality of follow-up sheet material forming.

[0054] like Figure 2 and Figure 3 As shown, the extruder 2 includes a barrel 21 and two screws 22 arranged in the barrel 21. The two screws 22 are meshed with each other and are rotatably arranged in the barrel 21 with their respective central axes as rotation axes. The diameter of each screw 22 gradually decreases from the feeding end to the discharging end, and the angle α between the rotation axes of the two screws 22 is 10′ to 1°20′. Figure 3 The structure diagram of the twin screw is shown in FIG. 2. In order to more clearly illustrate the degree of inclination of the screw 22, Figure 3 The threads on the screw 22 are not shown. Figure 3 As shown, the two screws 22 have a very small taper close to that of a flat screw (i.e., a cylindrical screw of equal outer diameter). This taper is very small relative to the length of the screws 22. The angle between the central axes of the two screws 22 is α, and the value of α ranges from 10′ to 1°20′. The final value of α can be determined based on the composition of the material and processing conditions. For example, α can also be 30′, 35′, 40′, 1°, 1°10′, etc. Optionally, α is 10′ to 1°.

[0055] In some embodiments, the two screws 22 have the same size, the average of the maximum and minimum outer diameters of each screw 22 is the median diameter, and the ratio of the length to the median diameter of each screw 22 is 25:1 to 35:1.

[0056] In some embodiments, the length of each screw 22 is 3 to 7 meters.

[0057] In the above embodiment, the taper and length of the screw 22 are limited. Compared to conventional tapered screws, the screw 22 has a longer length and a smaller taper. This optimizes the combination of the shear force provided by the screw 22 and the duration of its action on the PET material, thereby more effectively plasticizing the PET material, improving the plasticizing effect, and achieving the desired processing state. For example, the length-to-median-diameter ratio of each screw 22 can be 26:1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, etc., and the length can be 3.5 m, 4 m, 4.5 m, 5 m, 5.5 m, 6 m, 6.5 m, etc. Based on the screw length and the length-to-median-diameter ratio, the outer diameter (maximum outer diameter) of the screw 22 at the feed end and the outer diameter (minimum outer diameter) of the screw 22 at the discharge end can be determined, thereby determining the overall dimensions of the screw 22.

[0058] The double screw used in the above extruder 2 is a new screw structure between flat double screw and tapered double screw. The taper of the existing tapered double screw is large, the diameter of the screw changes greatly from the feeding end to the discharging end, for example, the maximum diameter is about twice the minimum diameter, the length is small, and the length-diameter ratio is between 22:1 and 28:1. The space inside the screw is getting smaller and the pressure on the material is getting larger during the forward pushing of the material, the plasticizing capacity is good, but when processing PET material, it is easy to appear over-plasticization or paste phenomenon if not controlled well, and the pressure needs to be controlled during production, and if not controlled well, it will fluctuate, resulting in poor stability. The outer diameter of the existing flat double screw is equal, and there is no taper, and the plasticizing capacity is slightly worse than that of the tapered double screw, so the length of the screw needs to be increased to improve the plasticizing effect. The length-diameter ratio of the existing parallel double screw is generally more than 30:1, and some may reach 38:1 or even more than 40:1. Since the flat double screw does not have a taper, there is no pressure during the forward pushing of the material, and there is no fluctuation, so the production process is relatively easy to control and has good stability, but when processing PET material, it will lead to insufficient plasticization, and the PET material cannot reach a good plasticized state. The double screw designed in this application is designed based on the above two existing screw structures. By retaining and reducing the appropriate taper of the tapered double screw, the disadvantage of easy over-plasticization of the tapered double screw is avoided, and the appropriate pressure is retained. The advantage of easy plasticization of the tapered double screw is controlled within a proper range. Correspondingly, due to the reduction of the taper, the plasticizing capacity is relatively weakened, and the length of the screw is appropriately increased to achieve the required plasticizing degree. Compared with the existing tapered screw, the taper is smaller and the length is longer, which can provide suitable shear force for PET material plasticization, so that the PET material can be more fully plasticized, and at the same time, the phenomenon of over-plasticization does not occur, and the production process is easier to control and has good stability. The advantages of tapered double screw and flat double screw are combined.

[0059] In an embodiment of the present application, the double screw is designed based on the existing 92 tapered double screw. The maximum diameter of the existing 92 tapered double screw is 188 mm, and the minimum diameter is 92 mm. The average value of the maximum diameter and the minimum diameter of the existing tapered double screw is (188+92) / 2=140. Optionally, 190 mm and 145 mm are taken as the maximum diameter and the minimum diameter of the screw in an embodiment of the present application, and the ratio of the length and the diameter is 33:1. Therefore, the length of the screw is (190+145) / 2*33=5527.5 mm. Therefore, the length is taken as 5527 mm, and the double screw of this form is named as 168 light tapered flat double screw.

[0060] Furthermore, the existing PET material extrusion molding process is limited by the screw structure. Both screws rotate in the same direction and must run at high speeds, resulting in high energy consumption and low production capacity. Based on improvements to the screw structure, the extruder 2 can employ a counter-rotating design, where the two screws 22 rotate in opposite directions. That is, the two screws 22 rotate in opposite directions, with one screw 22 rotating clockwise and the other counterclockwise. Compared to existing co-rotating designs, this design allows for lower speeds, for example, 10 to 40 rpm, resulting in lower energy consumption and higher production capacity.

[0061] In some embodiments, as Figure 4a As shown, each screw 22 includes, along the processing direction, a preheating section 221, a first mixing section 222, a first exhaust section 223, a compression section 224, a second mixing section 225, a plasticizing section 226, a second exhaust section 227, and a discharge section 228. The material is initially in a solid, granular, or powdery state when added to the extruder 2. Heating coils 25 are provided on the barrel 21 of the extruder 2, corresponding to each section of the screw 22, to control the temperature within each section of the barrel 21. In this embodiment, based on improvements to the screw structure, the functional sections of the screw from the feed end to the discharge end have been rearranged, providing two mixing sections and two exhaust sections. This ensures more thorough mixing and exhaust of the PET material before entering the plasticizing section.

[0062] The functions of each section of the screw 22 are achieved through the design of the screw ridges on the screw 22 and the temperature control of the barrel 21. It can be understood that the focus of this application is on the adjustment of the distribution of each functional section on the screw after the improvement of the screw structure, rather than on how to specifically achieve the functions of each section. In order to achieve the corresponding functions of each section, those skilled in the art can refer to the existing technology to achieve it. Anything not described in this application should not be considered as insufficient disclosure of this application.

[0063] The barrel 21 continuously heats and raises the temperature of the material in the preheating section 221. The preheating section 221 of the screw 22 continuously turns the material so that the material can be heated evenly to ensure the preheating effect. The first mixing section 222 and the second mixing section 225 are used to mix and crush the material so that the dispersed phase size of the material is smaller and the distribution is more uniform. During the rotation of the screw 22, the material is subjected to shear forces between the screw 22 and the barrel 21 and between different flow layers inside the material to achieve mixing. During the material processing process, the air, water vapor and low molecular volatiles entrained in the material will be discharged. If they are not discharged in time, defects such as bubbles and cavities will be formed in the product, resulting in a decline in product quality. Figure 2As shown, the barrel 21 is provided with exhaust devices 24 at positions corresponding to the first exhaust section 223 and the second exhaust section 227. The exhaust device 24 is connected to the interior of the barrel 21 and is used to discharge the waste gas generated during the extrusion molding process of the material. The screw 22 adopts a large pitch in the first exhaust section 223 and the second exhaust section 227 to make the material loose, increase the contact area between the material and the air, and facilitate exhaust. The compression section 224 compresses the material to increase the density of the material. The screw 22 has a smaller pitch and a shallower thread depth in the compression section 224, which reduces the space occupied by the material and realizes the compression function. After preheating and compression, the material enters the plasticizing section 226 for further heating and shearing, so that the material is completely melted, forming a uniform viscous flow state, and achieving the plasticizing effect. The plasticized material is smoothly conveyed forward through the discharge section 228, output from the extruder 2 and enters the mold 3.

[0064] In some embodiments, as Figure 4a and Figure 4b As shown, the first mixing section 222 and the second mixing section 225 have multiple groups of stirring assemblies 23 spaced axially on the outer surface of the screw 22. Each group of stirring assemblies 23 includes multiple tooth-like protrusions 231 distributed along the circumference of the screw 22. The spacing between adjacent stirring assemblies 23 is 20 to 35 mm, and the length of each tooth-like protrusion 231 in the axial direction of the screw 22 is 20 to 35 mm. The distribution and size of the stirring assemblies 23 in the first mixing section 222 and the second mixing section 225 are the same, and the length of the second mixing section 225 is greater than that of the first mixing section 222. In this embodiment, the design of the stirring assemblies 23 in the mixing section of the screw 22 disrupts the flow of the material and increases the lateral mixing of the material. The two-stage mixing before plasticization ensures that the material is more thoroughly mixed, preparing for plasticization.

[0065] It is understandable that, except for the first mixing section 222 and the second mixing section 225 , the outer surfaces of the other sections of the screw 22 are provided with helical threads, and the corresponding functions are achieved by designing the pitch, lead, screw ridges, etc. of the helical threads.

[0066] In some embodiments, the length of the preheating section 221 accounts for 30% to 40% of the total length of the screw 22, and the pitch of the preheating section 221 is 50 to 65 mm. The preheating section 221 includes, in the processing direction, a feed section 2211, a first temperature rising section 2212, and a second temperature rising section 2213. The length of the feed section 2211 is greater than or equal to the length of the first temperature rising section 2212, and the length of the first temperature rising section 2212 is greater than the length of the second temperature rising section 2213. The number of threads in the feed section 2211, the first temperature rising section 2212, and the second temperature rising section 2213 is equal, and the pitch and flight dimensions decrease in the axial direction of the screw 22. In this embodiment, the long length of the preheating section 221 allows the material to be fully heated before mixing. By dividing the preheating section 221 into three functional sections with successively decreasing pitch and flight dimensions in each section, the material can be more fully heated and better transitioned to the mixing section.

[0067] In some embodiments, the pitch of the compression section 224 is smaller than the pitch of the first exhaust section 223 and larger than the spacing between the agitating assemblies 23 of the first mixing section 222 and the second mixing section 225. The dimension of the screw flight of the compression section 224 in the axial direction of the screw 22 is smaller than the length of the tooth-like protrusions 231 of the first mixing section 222 and the second mixing section 225 in the axial direction of the screw 22. The small pitch and small flight size of the compression section 224 can enhance the extrusion of the material, causing the material to be compressed more tightly.

[0068] In some embodiments, the pitch and flight dimensions of the first venting section 223 and the second venting section 227 are identical, and the pitch and flight dimensions of the first venting section 223 and the second venting section 227 in the axial direction of the screw 22 are both greater than those of the other sections of the screw 22. The length of the second venting section 227 is greater than the length of the first venting section 223 but less than twice the length of the first venting section 223. The large pitch and flight dimensions of the venting section increase the residence time of the material in the venting section and reduce pressure, thereby facilitating the discharge of gas from the material out of the barrel 21. Furthermore, the design of two venting sections, one at the rear end of the first mixing section 222 and the other at the rear end of the plasticizing section 226, helps improve the plasticization of the PET material. The longer length of the second venting section 227 facilitates the full discharge of gas from the plasticized material, further reducing defects such as bubbles in the product.

[0069] In some embodiments, three exhaust devices 24 are provided, wherein one exhaust device 24 is provided at the first exhaust section 223, and two exhaust devices 24 are provided side by side in the processing direction at the second exhaust section 227. The exhaust device 24 can be any device in the prior art that can achieve extruder exhaust, for example, reference can be made to the solution provided in Chinese patent application 202422531684.X.

[0070] In some embodiments, the plasticizing section 226 includes a reflux section 2261 and a material blocking section 2262. Figure 4c As shown, a reflow groove 2263 is formed on at least part of the spiral fins in the reflow section 2261, the lead of the material blocking section 2262 is smaller than the lead of the reflow section 2261, and the length of the reflow section 2261 is greater than the length of the material blocking section 2262 and less than twice the length of the material blocking section 2262. The reflux section 2261 can cause some of the material to reflux in the screw 22. During the reflux process, materials entering the screw 22 at different levels and times can be fully mixed, increasing the residence time of the material in the plasticizing section 226, promoting heat transfer, further promoting the plasticization of the material, and ensuring that the material reaches a good plasticized state. The lead of the reflux section 2261 can be 80 to 100 mm (e.g., 90 mm), and the lead of the stop section 2262 is smaller, which can be 40 to 55 mm (e.g., 50 mm). The axial propulsion speed of the material in the stop section 2262 is relatively slow, and the pressure can be adjusted to prevent excessive reflux of the material. The material flowing out of the reflux section 2261 can be propulsed in an orderly and stable manner in the stop section 2262 in a predetermined direction, making the plasticizing process more stable. In addition, the design of the length of the reflux section 2261 and the stop section 2262 can find a balance between plasticizing efficiency and plasticizing effect, so that the material can be fully processed and the extrusion process can be completed efficiently.

[0071] In some embodiments, a first transition section 229 is further provided between the first mixing section 222 and the first exhaust section 223, and a second transition section 2210 is further provided between the second mixing section 225 and the plasticizing section 226; the pitch of the first transition section 229 is greater than the spacing of the stirring components 23 of the first mixing section 222 and smaller than the pitch of the first exhaust section 223; the pitch of the second transition section 2210 is greater than the spacing of the stirring components 23 of the second mixing section 225 and greater than the pitch of the plasticizing section 226.

[0072] In some embodiments, the discharge section 228 includes a first discharge section 2281 and a second discharge section 2282, which are located at the rear end of the second exhaust section 227 along the processing direction. The pitch of the first discharge section 2281 is greater than the pitch of the second discharge section 2282, the number of threads in the first discharge section 2281 is less than the number of threads in the second discharge section 2282, and the length of the first discharge section 2281 is greater than twice the length of the second discharge section 2282. The design of the first discharge section 2281 and the second discharge section 2282 in the discharge section 228 can efficiently convey materials and establish stable pressure, smoothly conveying the materials forward and avoiding pressure fluctuations that may cause product quality problems.

[0073] This application also improves the calender 4 in the plate production line to make it more suitable for producing PET plates. Figure 5a-5cAs shown, the calender 4 includes a frame 41 and multiple groups of calendering rollers 42 arranged on the frame 41 along the processing direction. The slab formed by the mold 3 enters the calender 4 for calendering. The calendering rollers located above the slab conveying path are upper calendering rollers 421, and the calendering rollers located below the slab conveying path are lower calendering rollers 422. Each group of calendering rollers 42 includes an upper calendering roller 421 and a lower calendering roller 422 correspondingly arranged above and below, or only includes one lower calendering roller 422. A conveying device 43 is provided between at least two adjacent calendering roller groups 42. Figure 6-Figure 8 The conveying device 43 includes a plurality of rollers 431 arranged between two adjacent calendering roller groups 42 and a conveyor belt 432 surrounding the plurality of rollers 431. The surface of the conveyor belt 432 located above the plurality of rollers is the conveying surface. The upper end surfaces of the plurality of rollers 431 are flush so that the conveying surface remains flat. The plane where the conveying surface is located is tangent to the roller surfaces of the two lower calendering rollers 422 on both sides of the conveyor belt.

[0074] In the above embodiment, one or more conveying devices 43 may be provided, depending on the distance between adjacent calendering roller sets 42. For example, if the distance between two adjacent calendering roller sets 42 is large, a conveying device 43 may be provided. If the distance between two adjacent calendering roller sets 42 is small, a conveying device 43 may not be provided. The conveying device 43 takes the form of a conveyor belt 432 wrapped around multiple rollers 431. The upper surface of the conveyor belt 432 supported above the multiple rollers 431 is flat. Due to the high rigidity of the PET slab, the temperature of the calender 4 is high during the calendering process, keeping it in a relatively soft and easily deformable state. While the PET slab is being transported between the calendering roller sets 42, the flat conveyor belt 432 provides flat support for the PET slab, preventing corrugated deformation and ensuring the flatness of the PET sheet.

[0075] The plane of the upper surface of the conveyor belt 432 is tangential to the roller surfaces of the lower calendering rollers 422 in the two adjacent calendering roller groups 42, ensuring that the conveyor belt 432 forms a good connection with the calendering rollers at its ends. The slab discharged from one calendering roller group 42 can be conveyed to the top of the conveyor belt 432 in a flat state, and then conveyed from the top of the conveyor belt 432 to the next calendering roller group 42 in a flat state, thereby ensuring the flatness of the slab. The upper surface of the conveyor belt 432 can be horizontal or inclined, depending on the height of the lower calendering rollers 422 at its front and rear ends. The inclination of the upper surface of the conveyor belt 432 is determined by the arrangement height of the multiple rollers 431.

[0076] In some embodiments, as Figure 9a and Figure 9bAs shown, the conveying device 43 further includes a roller mounting member 433, and both ends of each roller 431 are respectively mounted on the frame 41 via the roller mounting member 433. The roller mounting member 433 is formed with a mounting groove 4331. Both ends of each roller 431 are respectively formed with a mounting shaft 4311, and the mounting shaft 4311 is disposed in the mounting groove 4331 to mount the roller 431 on the frame 41. The roller mounting member 433 can be a sheet-like structure or a block-like structure, and the mounting groove 4331 is formed through the sheet-like structure or the block-like structure. The shape of the mounting groove 4331 can be an upward opening or a hole.

[0077] In some embodiments, as Figure 9a and Figure 9b The roller mounting member 433 has a bolt hole 4332 in communication with the bottom of the mounting slot 4331. An adjustment bolt 434 is threadedly mounted within the bolt hole 4332. The end of the adjustment bolt 434 extends from the bottom of the mounting slot 4331 into the mounting slot 4331 and supports the mounting shaft 4311 of the roller 431. To adjust the height of the roller 431 to adjust the flatness and inclination of the upper surface of the conveyor belt 432, the height of the roller 431 can be adjusted simply by rotating the adjustment bolt 434 to adjust the height at which the end of the adjustment bolt 434 is exposed from the bottom of the mounting slot 4331. This is simple and easy to do.

[0078] In some embodiments, as Figure 5c-Figure 8 As shown, the conveyor 43 also includes a first drive motor 435 and drive rollers 436 mounted on the frame 41. The conveyor belt 432 is wrapped around multiple rollers 431 and drive rollers 436. The output shaft of the first drive motor 435 is connected to the drive rollers 436. The first drive motor 435 rotates the drive rollers 436 to drive the conveyor belt 432. In this embodiment, the first drive motor 435 only needs to drive the rotation of one drive roller 436 to achieve conveyance of the entire conveyor 43, eliminating the need to drive the rotation of each roller 431 separately. This improves drive efficiency and ensures stable slab conveying. The first drive motor 435 can be a servo motor, etc.

[0079] In some embodiments, the conveyor 43 further includes two guide rollers 437, which are mounted between the drive roller 436 and the plurality of idler rollers 431. The two guide rollers 437 are located between the two lower calendering rollers 422 in two adjacent calendering roller groups 42. The conveyor belt 432 wraps around the plurality of idler rollers 431 and is guided to the drive roller 436 via opposite sides of the two guide rollers 437. In this embodiment, the drive roller 436 is mounted on the frame 41 near the bottom of the frame 41. The guide rollers 437 are used to adjust the direction of the conveyor belt 432 to prevent interference between the conveyor belt 432 and the calendering rollers.

[0080] In some embodiments, as Figure 5a-5cAs shown, at least one of the multiple calendering roller groups 42 includes only a single lower calendering roller 422. A first baking device 44 is positioned above the calendering roller group 42 that includes only a single lower calendering roller 422 to heat the slab. The first baking device 44 can be a heating device such as an oven or a heat lamp. The length of the first baking device 44 can be comparable to the length of the calendering rollers, thereby covering the entire width of the slab and ensuring uniform heating. Due to the high rigidity of PET, it can become brittle as the temperature decreases during processing. To prevent the PET slab from becoming brittle and developing defects such as cracks during the calendering process, the first baking device 44 is positioned within the calender 4 to allow heating to be applied as needed based on changes in the PET slab's properties during calendering.

[0081] In some embodiments, a lift 45 is installed on the first baking device 44. The lift 45 is mounted on the frame 41. Activating the lift 45 adjusts the distance between the oven and the slab, thereby adjusting the heating effect. Because the first baking device 44 is relatively long, two lifts 45 can be provided at each end of its length. The two lifts 45 are connected by a connecting rod 46 to ensure synchronous movement. The lifts can be implemented using any commonly available structure capable of performing a lifting function.

[0082] In some embodiments, the frame 41 of the calender 4 is installed on the ground running rail 9 to facilitate the adjustment of the position of the calender 4 in the production line.

[0083] In some embodiments, as Figure 10 As shown, a displacement sensor 47 for measuring the lifting distance of the upper calendering roller 421 is provided corresponding to each upper calendering roller 421, and a second drive motor 48 for controlling the lifting of the upper calendering roller 421 is provided on the frame 41. The displacement sensor 47 is connected to the second drive motor 48 and is configured to send a signal to the second drive motor 48 to lift the upper calendering roller 421 to a set position, thereby realizing precise adjustment of the gap between the calendering roller group 42.

[0084] In some embodiments, as Figure 1a and Figure 1b As shown, a cooling bracket 5, a haul-off machine 7, and a cutting device 8 are installed at the rear end of the calender 4. A second baking device 6 is also installed at the front end of the haul-off machine 7. This second baking device 6 is used to heat the PET sheet before cutting. Considering that the PET sheet may become brittle after passing through the cooling bracket 5, heating the PET sheet before cutting is necessary to prevent defects such as cracks during cutting and ensure optimal cutting. The specific configuration of the second baking device 6 can be referred to above as the first baking device 44 and will not be further described here.

[0085] In some embodiments, a film coating assembly (not shown in the figure) can also be provided at the rear end of the calender 4 for film coating treatment of the PET plate blank, and the film coating assembly can be provided with one or more sets of film coating rollers as required. For details, refer to the prior art.

[0086] The plate production line provided by the embodiments of the present application improves the extruder 2 and the calender 4 in combination with the characteristics of PET material. The production capacity of the production line can reach a high capacity of 1600 kg / h or more, and the quality of the obtained PET plate is stable, has few defects, and has a high yield.

[0087] The following provides a method for producing a PET plate using the improved plate production line of the present application, including the following steps:

[0088] The mixture of PET material and auxiliary materials is mixed with calcium powder at a ratio of 1:2-5;

[0089] The mixed material is sent to the extruder 2 for extrusion molding, and the rotation directions of the two screws 22 of the extruder 2 are opposite and the rotation speed is 10-40 r / min;

[0090] The material plasticized by the extruder 2 enters the mold 3 for molding;

[0091] The molded plate blank enters the calender 4 for calendering treatment;

[0092] The plate blank output by the calender 4 is cut to form a PET plate.

[0093] Based on the improved plate production line for producing a PET plate, by increasing the mixing ratio of calcium powder, the state of the material in the extruder 2 can be adjusted, the two screws 22 of the extruder 2 can rotate at a low speed in opposite directions, the plasticizing effect is improved, the energy consumption is reduced, and the yield is improved. Under the premise that the material has a good plasticizing state, the molding and calendering effect of the plate can be improved, and the quality of the finished plate can be ensured.

[0094] Alternatively, the mixing ratio of the mixture of PET material and auxiliary materials to calcium powder can be 1:3-5, and specifically can be 1:4. The auxiliary materials can include, for example, one or a combination of two or more of plasticizers, heat stabilizers, lubricants, and flame retardants, and can be determined as required. The rotation speed of the screw 22 during extrusion molding can be 15 r / min, 18 r / min, 20 r / min, 25 r / min, 28 r / min, 30 r / min, 35 r / min, etc., and can be determined by a person skilled in the art as required.

[0095] Optionally, the temperature of the extruder 2 is 190-280°C. Specifically, the extruder 2 is provided with a barrel sleeve 211 corresponding to each section of the screw 22, and a heating ring 25 is provided on the barrel sleeve 211 for heating the barrel 21, wherein the temperature of the extruder 2 in the preheating section 221 is 210-260°C (for example, 220°C, 230°C, 240°C, 250°C, etc.), the temperature from the first mixing section 222 to the plasticizing section 226 is 230-280°C (for example, 240°C, 250°C, 260°C, 270°C, etc.), the temperature in the second exhaust section 227 and the discharge section 228 is 190-250°C (for example, 200°C, 210°C, 220°C, 230°C, 240°C, etc.), and the temperature decreases from the second exhaust section 227 to the discharge section 228. The extruder 2 sets corresponding temperatures for each functional section of the screw 22 so that each section of the screw 22 can better perform its function at the corresponding temperature, so that the material is fully mixed and plasticized.

[0096] Optionally, when the material extruded by the extruder 2 enters the mold 3 for molding, the temperature of the mold 3 is 220-260°C, for example, it can be 230°C, 240°C, 250°C, etc., and those skilled in the art can adjust it according to the state of the extruded material.

[0097] Optionally, the temperature of the calendering rollers in the calender 4 is 180-250°C, for example, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, etc., and those skilled in the art can adjust it according to the state of the slab after forming.

[0098] According to the characteristics of the PET material during processing, the temperature of the mold 3 and the temperature of the calendering roller 4 are limited to a suitable range, thereby adjusting the temperature according to the state of the PET sheet during production, improving the quality of the finished sheet, reducing the occurrence of defects, and further increasing the production line's capacity.

[0099] Optionally, the calender 4 is provided with a first baking device 44, which heats the slab during the slab calendering process. The temperature of the first baking device 44 is 180-220°C. The temperature of the first baking device 44 can be 190°C, 200°C, 210°C, etc. After the slab is heated by the first baking device 44, the temperature increases, the brittleness decreases, and the risk of fracturing during the calendering process is reduced.

[0100] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0101] The above examples 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 preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, all of them should be covered in the technical solution range of the present application claimed.

Claims

1. A sheet production line comprising an extruder, a die and a calender arranged along a processing direction, characterized in that: The extruder includes a barrel and two screws, the two screws meshing with each other and rotatably arranged in the barrel with their respective central axes as rotation axes, the diameter of each screw gradually decreasing from the feed end to the discharge end, and the angle between the rotation axes of the two screws is 10'~1°20'; The calendering machine includes a frame and multiple groups of calendering rollers arranged on the frame, the calendering rollers located above the slab conveying path are upper calendering rollers, and the calendering rollers located below the slab conveying path are lower calendering rollers. Each group of calendering rollers includes an upper calendering roller and a lower calendering roller correspondingly arranged above and below, or only includes one lower calendering roller. A conveying device is provided between at least two adjacent groups of calendering rollers; the conveying device includes multiple rollers and a conveyor belt surrounding the multiple rollers, the surface of the conveyor belt located above the multiple rollers is the conveying surface, the upper end surfaces of the multiple rollers are flush to keep the conveying surface flat, and the plane where the conveying surface is located is tangent to the roller surfaces of the two lower calendering rollers on both sides of the conveyor belt.

2. The plate production line according to claim 1, characterized in that: The aspect ratio of each screw is 25:1 to 35:1, where the aspect ratio is the ratio of the length of the screw to the average value of the diameter at the feed end and the diameter at the discharge end.

3. The plate production line according to claim 2, characterized in that: The length of each screw is 3 to 7 m.

4. The plate production line according to claim 1, characterized in that: The conveying device also includes a roller mounting member provided on the frame, the roller mounting member is formed with a mounting groove, and each roller is formed with a mounting shaft at both ends, the mounting shaft is provided in the mounting groove and supported by the bottom of the mounting groove to install the roller on the frame.

5. The plate production line according to claim 4, characterized in that: A bolt hole connected to the bottom of the mounting groove is provided in the roller mounting piece, and an adjustment bolt is threadedly installed in the bolt hole. The end of the adjustment bolt extends into the mounting groove from the bottom of the mounting groove and supports the roller.

6. The plate production line according to claim 1, characterized in that: The conveying device further includes a first driving motor and a driving roller mounted on the frame, the conveyor belt surrounds the plurality of rollers and the driving roller, and the first driving motor is connected to the driving roller.

7. The plate production line according to claim 1, characterized in that: Among the multiple calendering roller groups, at least one calendering roller group includes only one lower calendering roller, and a first baking device is provided above the calendering roller group including only one lower calendering roller.

8. The plate production line according to claim 1, characterized in that: A displacement sensor for measuring the lifting distance of the upper calendering roller is provided corresponding to each upper calendering roller. A second drive motor for controlling the lifting of the upper calendering roller is provided on the frame. The displacement sensor is electrically connected to the second drive motor.

9. The plate production line according to claim 1, characterized in that: A cooling bracket, a haul-off machine and a cutting device are provided at the rear end of the calender, and a second baking device is provided at the front end of the haul-off machine.

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