PP thick plate extrusion production line

Abstract

The invention discloses a PP thick plate extrusion production line, and particularly relates to the technical field of thick plate production equipment.The PP thick plate extrusion production line comprises an extruder, a forming die, a three-roller calender, a cooling transmission frame, a traction machine and a cutting device which are sequentially arranged in the material conveying direction, and the three-roller calender comprises a rack, an upper roller, a middle roller and a lower roller, and the upper roller, the middle roller and the lower roller are installed on the rack. By arranging the cooling mechanism with the two-way spiral flow channel, a cooling medium spirally flows in the first flow guide grooves and the second flow guide grooves in opposite directions, and efficient heat exchange is performed between the adjacent first flow guide grooves and second flow guide grooves, so that the axial temperature difference of the surface of the roller body is remarkably reduced, uniform cooling is realized, and the service life of the roller body is prolonged. Deformation defects such as warping or rippled edges caused by non-uniform cooling of the PP thick plate are effectively prevented, and the production efficiency and the product consistency are improved.

Description

Technical Field

[0001] This invention relates to the field of equipment technology for thick plate and sheet production, and more specifically, to a PP thick plate extrusion production line. Background Technology

[0002] A PP thick sheet extrusion production line is an automated industrial equipment specifically designed to continuously process polypropylene (PP) plastic granules into sheets of a specific thickness. Through a series of processes including heating, plasticizing, extrusion, shaping, cooling, and cutting, it produces PP sheets widely used in packaging, construction, automotive, and other fields.

[0003] In current PP thick sheet extrusion production lines, after the PP thick sheet is calendered by the first two rollers of a three-roll calender, it needs to be rapidly cooled and shaped by the rear roller to prevent subsequent shrinkage and deformation. However, the rear roller of the existing three-roll calender adopts a spiral single-channel water channel structure, which results in uneven distribution of cooling water along the roller axis. The cooling speed is fast in the area near the inlet, while the cooling speed is slow in the outlet area far from the inlet. This causes a significant axial temperature difference on the roller surface. This uneven cooling causes inconsistent shrinkage behavior in different areas of the PP thick sheet during the shaping process. This results in the faster-cooling areas shaping prematurely, while the slower-cooling areas still maintain a certain degree of thermoplastic flow. Ultimately, this leads to deformation defects such as warping or wavy edges in the sheet, reducing overall production efficiency and product consistency.

[0004] This invention provides a PP thick plate extrusion production line, which aims to solve the problem that in the existing PP thick plate extrusion production line, the rear roller of the three-roll calender adopts a spiral single-channel water channel structure, which leads to uneven distribution of cooling water along the roller axis, resulting in deformation defects such as warping or wavy edges in the plate. Summary of the Invention

[0005] The purpose of this invention is to provide a PP thick plate extrusion production line to solve the problem mentioned in the background art that in the existing PP thick plate extrusion production line, the rear roller of the three-roll calender adopts a spiral single-channel water channel structure, which leads to uneven distribution of cooling water along the roller axis, resulting in deformation defects such as warping or wavy edges in the plate.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a PP thick plate extrusion production line, comprising an extruder, a forming die, a three-roll calender, a cooling transfer frame, a traction machine, and a cutting device arranged sequentially along the material conveying direction. The three-roll calender includes a frame and an upper roll, a middle roll, and a lower roll mounted on the frame. The lower roll is a cooling roll, which has a cooling mechanism inside for causing the cooling medium to flow spirally in opposite directions, and a throttling mechanism for dynamically adjusting the flow rate of the cooling medium flowing into the cooling mechanism according to the axial temperature distribution of the lower roll.

[0007] Preferably, the cooling mechanism includes a partition layer coaxially disposed within the roller body of the lower roller, and a plurality of spiral guide vanes are arranged circumferentially between the partition layer and the inner wall of the roller body. A plurality of first guide grooves and a plurality of second guide grooves are formed between the plurality of spiral guide vanes. The spiral directions of the first guide grooves and the second guide grooves are the same, but the flow directions of the cooling medium are opposite.

[0008] Preferably, the two ends of the roller are respectively provided with sealing plates, the sealing plates are sealed to the end of the separator layer and the inner wall of the roller, and the sealing plates are provided with a plurality of diversion holes communicating with a plurality of the first guide grooves.

[0009] Preferably, the roller body is provided with partitions at both ends, the partitions dividing the end space into a first diversion cavity near the sealing plate and a second diversion cavity near the end cover plate of the roller body, and a plurality of diversion rods communicating with a plurality of second guide grooves are provided between the partitions and the sealing plate.

[0010] Preferably, the lower roller is provided with roller shafts at both ends, and each roller shaft is provided with a first flow channel communicating with the first flow distribution cavity and a second flow channel communicating with the second flow distribution cavity. The first flow channel and the second flow channel are used for the inflow and outflow of cooling medium, respectively, and the inflow and outflow functions of the corresponding flow channels on the two roller shafts are opposite.

[0011] Preferably, the throttling mechanism includes a first drive groove and a second drive groove formed inside the roller shaft, a first throttling groove is formed between the first flow channel and the first drive groove, and a second throttling groove is formed between the second flow channel and the second drive groove.

[0012] Preferably, the first drive groove is provided with a first electromagnet and a first magnetic component that is magnetically repelled by the first electromagnet. A first throttling plate that is slidably connected to the side of the first magnetic component away from the first electromagnet is fixedly connected. The first electromagnet generates a magnetic field under control to drive the first magnetic component to move the first throttling plate, thereby adjusting the flow cross-sectional area of ​​the first flow channel.

[0013] Preferably, the second drive groove is provided with a second electromagnet and a second magnetic component that repels the magnetism of the second electromagnet. A second throttling plate that is slidably connected to the side of the second magnetic component away from the second electromagnet is fixedly connected. The second electromagnet generates a magnetic field under control to drive the second magnetic component to move the second throttling plate, thereby adjusting the flow cross-sectional area of ​​the second flow channel.

[0014] Preferably, a first elastic element is connected between the first magnetic element and the inner wall of the first driving groove, and a second elastic element is connected between the second magnetic element and the inner wall of the second driving groove.

[0015] Preferably, the system further includes multiple temperature sensors, which are evenly distributed along the axial direction of the roller on the inner wall of the separator layer. The temperature sensors, the first electromagnet, and the second electromagnet are all electrically connected to the controller and are used to control the operation of the first electromagnet and the second electromagnet according to the signals from the temperature sensors.

[0016] The technical effects and advantages of this invention are as follows: 1. The present invention, by setting a cooling mechanism with a bidirectional spiral flow channel, enables the cooling medium to flow in opposite directions in the first and second guide channels, and to carry out efficient heat exchange between adjacent first and second guide channels, thereby significantly reducing the axial temperature difference on the roller surface, achieving uniform cooling, effectively preventing deformation defects such as warping or wavy edges caused by uneven cooling of PP thick plates, and improving production efficiency and product consistency.

[0017] 2. This invention, through the setting of a throttling mechanism, utilizes temperature sensors uniformly distributed inside the separator layer to detect the axial temperature of the roller in real time. The controller dynamically adjusts the current of the first and second electromagnets based on the temperature difference signal, driving the first and second magnetic components to slide the first and second throttling plates. This precisely controls the cooling medium flow rate of the first and second flow channels, achieving dynamic flow distribution of the bidirectional spiral flow channel. This ensures that the roller surface temperature remains axially uniform even under external operating conditions, effectively preventing warping or wavy edges of PP thick plates caused by local temperature deviations, and significantly improving the long-term dimensional stability and internal flatness of the plate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the three-roll calender of the present invention.

[0020] Figure 3 This is a schematic diagram of the lower roller structure of the present invention.

[0021] Figure 4 This is a schematic diagram of the roller body and roller shaft structure of the present invention.

[0022] Figure 5 This is a schematic diagram of the structure of the first and second guide channels of the present invention.

[0023] Figure 6 This is a cross-sectional view of the internal structure of the roller body of the present invention.

[0024] Figure 7 For the present invention Figure 6 Enlarged view of the structure of part A.

[0025] Figure 8This is a schematic diagram of the sealing plate and partition structure of the present invention.

[0026] The attached figures are labeled as follows: 1. Extruder; 11. Forming die; 12. Three-roll calender; 121. Frame; 122. Upper roll; 123. Middle roll; 124. Lower roll; 125. Roller body; 126. Roller shaft; 127. Cover plate; 13. Cooling transfer frame; 14. Traction machine; 15. Cutting device; 2. Cooling mechanism; 21. Separating layer; 22. Sealing plate; 23. Partition plate; 24. First diversion chamber; 25. Second diversion chamber; 26. Spiral guide vane; 27. First guide groove; 28. 29. Second guide channel; 210. Diverting hole; 211. Diverting rod; 212. First flow channel; 213. Second flow channel; 31. Throttling mechanism; 32. First drive channel; 33. Second drive channel; 34. First throttling channel; 35. Second throttling channel; 36. First magnetic component; 37. First throttling plate; 38. First elastic component; 39. Second electromagnet; 310. Second magnetic component; 311. Second throttling plate; 312. Second elastic component; 313. Temperature sensor. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1 In existing PP thick sheet extrusion production lines, the rear roller of the three-roll calender uses a spiral single-channel water channel structure. This results in uneven distribution of cooling water along the roller axis. The cooling rate is faster near the inlet and slower at the outlet, creating a significant axial temperature difference on the roller surface. This uneven cooling causes inconsistent shrinkage behavior in different areas of the PP thick sheet during the shaping process. Faster-cooling areas shape prematurely, while slower-cooling areas retain some thermoplastic flow. Ultimately, this leads to deformation defects such as warping or wavy edges, reducing overall production efficiency and product consistency. refer to Figures 1 to 8 An embodiment of the present invention provides a PP thick plate extrusion production line, comprising an extruder 1, a forming die 11, a three-roll calender 12, a cooling transfer frame 13, a traction machine 14, and a cutting device 15 arranged sequentially along the material conveying direction, wherein: Extruder 1 is used to heat and pressurize PP raw materials to plasticize them into a uniform melt.

[0029] The forming mold 11 is used to uniformly extrude the melt to form a slab.

[0030] The three-roll calender 12 is used to calender and shape slabs to ensure a smooth and clean surface and to perform initial cooling.

[0031] The cooling transfer rack 13 is used to further cool and support the sheet material, allowing it to fully set.

[0032] The traction machine 14 is used to provide stable tension, pulling the sheet metal through the production line at a uniform speed.

[0033] The cutting device 15 is used to make transverse and longitudinal cuts according to a set length.

[0034] refer to Figure 2 The three-roll calender 12 includes a frame 121 and an upper roller 122, a middle roller 123 and a lower roller 124 mounted on the frame 121. The shaft ends of the upper roller 122, the middle roller 123 and the lower roller 124 are respectively connected to independently controlled drive devices and distance adjustment devices.

[0035] The upper roller 122 and the middle roller 123 are heating rollers, each with an independent heating chamber or heating pipe inside, for introducing a heat-conducting medium or setting an electric heating element to maintain the roller surface at a preset forming temperature.

[0036] refer to Figure 2 and Figure 3 The lower roller 124 is a cooling roller, which has a cooling mechanism 2 with a bidirectional spiral flow channel inside. The lower roller 124 includes a roller body 125, a roller shaft 126 and a cover plate 127. The roller body 125 is a cylindrical hollow structure, and its two ends are closed by the cover plate 127. There are two roller shafts 126, which are fixedly connected to the outer center of the two cover plates 127 respectively, to support the rotation of the roller body 125 and to serve as the inlet and outlet channels of the cooling medium.

[0037] refer to Figures 5 to 8 The cooling mechanism 2 includes: The separator layer 21 is disposed along the axial direction of the roller body 125 at the center position inside the roller body 125, dividing the space inside the roller radially.

[0038] Two sealing plates 22 are fixed to both ends of the separator layer 21 and are sealed to the inner wall of the roller body 125.

[0039] Two partitions 23 are respectively disposed between the sealing plate 22 and the corresponding end cover plate 127, dividing the end space into a first diversion cavity 24 near the sealing plate 22 and a second diversion cavity 25 near the cover plate 127.

[0040] Several spiral guide vanes 26 are evenly distributed in the annular space between the inner wall of the roller body 125 and the outer wall of the separator layer 21, and their two ends are fixedly connected to two sealing plates 22 respectively. The first guide groove 27 and the second guide groove 28 are alternately formed between adjacent spiral guide vanes 26, and the number of the two is the same.

[0041] refer to Figure 5 and Figure 8 Both sealing plates 22 are provided with diversion holes 29 in the same number and corresponding positions as the first guide channel 27, so that the two ends of the first guide channel 27 can be connected to the first diversion cavity 24 on the corresponding side through the diversion holes 29.

[0042] refer to Figure 6 Between the two partitions 23 and the corresponding sealing plate 22, there are diversion rods 210 of the same number and position as the second guide channel 28, which are used to connect the two ends of the second guide channel 28 to the second diversion cavity 25 on the corresponding side through the diversion rods 210. The diversion rods 210 are hollow tubular structures, and their two ends are sealed by sealing elements.

[0043] refer to Figure 6 The two rollers 126 are respectively provided with a first flow channel 211 and a second flow channel 212, wherein the first flow channel 211 is connected to the first flow divider 24 and the second flow channel 212 is connected to the second flow divider 25.

[0044] The first flow channel 211 and the second flow channel 212 on the same roller 126 are used as inflow and outflow channels for the cooling medium, and the two flow directions are opposite. At the same time, the corresponding flow channels on the left and right rollers 126 have opposite inflow and outflow functions. For example, if the first flow channel 211 of the left roller 126 is used as the cooling medium inlet, then its second flow channel 212 is used as the cooling medium outlet. Correspondingly, the first flow channel 211 of the right roller 126 is used as the cooling medium outlet, and its second flow channel 212 is used as the cooling medium inlet. The roller 126 is connected to the external cooling circulation pipeline through a rotary joint (existing technology, not described in detail).

[0045] In actual production, the pretreated PP raw material is first fed into the extruder 1 stably and continuously through an external feeder. The PP raw material is heated and conveyed by a screw conveyor through the extruder 1, so that the PP raw material is gradually melted, compressed and homogenized to form a uniform and fluid melt.

[0046] After being filtered, the melt is forced into the forming mold 11 to form a continuous slab with the required width and initial thickness.

[0047] The extruded slab is immediately introduced into a three-roll calender 12, where the upper roll 122, middle roll 123 and lower roll 124 of the three-roll calender 12 are used to press, scrape, and initially cool and shape the slab to form a precise surface finish and thickness.

[0048] After being calendered, the sheet material enters the cooling transfer rack 13 for further uniform cooling, so that the sheet material is completely cured and deformation is prevented.

[0049] The fully cooled sheet is clamped by the traction machine 14 and pulled out at a uniform speed, and finally cut by the cutting device 15 according to the set length.

[0050] After the PP sheet is heated and calendered by the upper roller 122 and the middle roller 123, it enters the lower roller 124 for preliminary cooling and shaping. The cooling mechanism 2 of the lower roller 124 works as follows: First cooling circuit: The cooling medium enters the first diversion cavity 24 on one side (such as the left side) of the roller 126 through the first flow channel 211, and is evenly distributed to each first guide groove 27 through the diversion hole 29. The medium flows along the spiral path of the first guide groove 27 through the entire length of the roller body 125. After reaching the other side (right side), it flows into the first diversion cavity 24 on the right side through the diversion hole 29, and finally flows out from the first flow channel 211 of the right roller 126.

[0051] Second cooling circuit: Simultaneously, the cooling medium enters the second diversion chamber 25 on the other side (e.g., the right side) from the second flow channel 212 of the roller 126. It is evenly distributed to each second guide groove 28 by the diversion rod 210. The medium flows along the spiral path of the second guide groove 28, but its flow direction is opposite to that of the adjacent first guide groove 27. After the medium reaches the left side, it flows into the second diversion chamber 25 on the left side through the diversion rod 210 and finally flows out from the second flow channel 212 of the left roller 126.

[0052] The cooling media in the first and second cooling circuits flow in opposite spiral directions within the roller body 125. Since the first guide groove 27 and the second guide groove 28 are closely adjacent and the media flow in opposite directions, the higher temperature medium (about to flow out of the roller body 125) and the lower temperature medium (just entering the roller body 125) will undergo efficient heat exchange, making the temperature of the cooling media at each point along the axial direction of the roller body 125 tend to be consistent, thereby significantly reducing the axial temperature difference of the roller surface, and finally achieving a uniform temperature distribution on the entire working surface of the roller body 125, so as to uniformly and stably cool the passing PP blank.

[0053] In summary, by setting up the cooling mechanism 2 with bidirectional spiral flow channels, the cooling medium flows spirally in opposite directions in the first guide groove 27 and the second guide groove 28, and performs efficient heat exchange between adjacent first guide grooves 27 and second guide grooves 28. This significantly reduces the axial temperature difference on the surface of the roller 125, achieves uniform cooling, effectively prevents deformation defects such as warping or wavy edges caused by uneven cooling of PP thick plates, and improves production efficiency and product consistency.

[0054] Example 2 In actual production, although the temperature uniformity of the lower roller 124 is improved by the bidirectional spiral flow channel, fluctuations in external operating conditions (such as changes in raw material temperature, differences in ambient temperature, and heat accumulation during long-term operation of the equipment) can still cause dynamic temperature deviations. The cooling medium with a fixed flow rate is still difficult to cope with real-time changes, which may cause the local temperature of the roller 125 to deviate from the set value, resulting in axial temperature differences that affect the quality and the long-term dimensional stability and internal flatness of the sheet. Therefore, this embodiment improves the device described in the above embodiment.

[0055] refer to Figure 6 and Figure 7 It also includes a throttling mechanism 3, which includes a first drive groove 31 located inside the roller 126 corresponding to the position of the first flow channel 211 and a second drive groove 32 located corresponding to the position of the second flow channel 212. A first throttling groove 33 is provided between the first drive groove 31 and the corresponding first flow channel 211, and a second throttling groove 34 is provided between the second drive groove 32 and the corresponding second flow channel 212.

[0056] refer to Figure 7 A first electromagnet 35 is fixedly embedded at one end of the first drive groove 31 away from the first flow channel 211. A first magnetic element 36 that is magnetically repelled by the first electromagnet 35 when energized is slidably connected inside the first drive groove 31. A first throttling plate 37 that is slidably connected inside the first throttling groove 33 is fixedly connected to the side of the first magnetic element 36 away from the first electromagnet 35. A first elastic element 38 is connected between the side of the first magnetic element 36 away from the first electromagnet 35 and the first drive groove 31 for resetting the first magnetic element 36.

[0057] A second electromagnet 39 is fixedly embedded at one end of the second drive groove 32 away from the second flow channel 212. A second magnetic element 310 that is magnetically repelled by the second electromagnet 39 when energized is slidably connected inside the second drive groove 32. A second throttling plate 311 that is slidably connected inside the second throttling groove 34 is fixedly connected to the side of the second magnetic element 310 away from the second electromagnet 39. A second elastic element 312 is connected between the side of the second magnetic element 310 away from the second electromagnet 39 and the second drive groove 32 for resetting the second magnetic element 310.

[0058] refer to Figure 6 It also includes a temperature detection unit, which includes multiple temperature sensors 313 arranged axially and uniformly on the inner side of the separator layer 21, for real-time acquisition of temperature signals at different positions along the axial direction of the roller body 125.

[0059] Multiple temperature sensors 313, a first electromagnet 35, and a second electromagnet 39 are all electrically connected to the controller. The controller receives signals from the temperature sensors 313 and, based on a set temperature threshold and temperature difference algorithm, outputs adjustable current to the corresponding first electromagnet 35 and second electromagnet 39.

[0060] During actual production, as the PP sheet and the lower roller 124 continuously exchange heat, multiple temperature sensors 313 detect the temperature distributed along the axial direction inside the roller body 125 in real time and transmit the data to the controller.

[0061] When a temperature deviation is detected in roller 125, such as the temperature on the left side being higher than that on the right side and the temperature difference exceeding a set threshold, the controller determines that the liquid inlet flow rate on the right side needs to be reduced while the liquid inlet flow rate on the left side needs to be increased to achieve thermal balance on both sides.

[0062] The controller simultaneously outputs a certain amount of current (the magnitude of the current is positively correlated with the temperature difference) to the second electromagnets 39 on the two rollers 126. The current causes the second electromagnets 39 to generate a magnetic field, which pushes the second magnetic component 310 with the same polarity to move towards the second flow channel 212, overcoming the resistance of the second elastic component 312, and driving the second throttling plate 311 to slide along the second throttling groove 34 towards the second flow channel 212, thereby reducing the effective flow cross-sectional area of ​​the two second flow channels 212.

[0063] Since the second flow channel 212 is the channel through which the cooling medium enters the second cooling circuit (inlet on the right and outlet on the left), the reduction in cross-sectional area will reduce the flow rate of the medium in this circuit, resulting in a relative decrease in the cooling capacity of the right side. At the same time, since the total system pressure is constant, after the flow rate of the second cooling circuit is reduced, the controller can allocate more medium to the first cooling circuit (the first flow channel 211 on the left serves as the inlet), thereby enhancing the cooling on the left side.

[0064] If the temperature on the right side of roller 125 is higher than that on the left side, the controller will activate the two first electromagnets 35 to push the first throttling plate 37 to reduce the flow area of ​​the first flow channel 211. The adjustment principle is the same as above, but the action circuit is reversed.

[0065] During the throttling adjustment process, the temperature sensor 313 continuously feeds back the temperature change, and the controller dynamically adjusts the current of the electromagnet according to the real-time temperature difference, thereby finely adjusting the opening of the first throttling plate 37 and the second throttling plate 311, so that the axial temperature of the roller 125 is always maintained within the set range.

[0066] In summary, by setting the throttling mechanism 3, the temperature sensors 313 evenly distributed inside the partition layer 21 are used to detect the axial temperature of the roller 125 in real time. The controller dynamically adjusts the current of the first electromagnet 35 and the second electromagnet 39 according to the temperature difference signal, driving the first magnetic component 36 and the second magnetic component 310 to drive the first throttling plate 37 and the second throttling plate 311 to slide. This accurately controls the cooling medium flow rate of the first flow channel 211 and the second flow channel 212, realizing dynamic flow distribution of the bidirectional spiral flow channel. This ensures that the surface temperature of the roller 125 remains axially uniform even under external working conditions, effectively preventing warping or wavy edges of the PP thick plate caused by local temperature deviation, and significantly improving the long-term dimensional stability and internal flatness of the plate.

[0067] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PP thick plate extrusion production line, comprising an extruder (1), a forming die (11), a three-roller calender (12), a cooling transmission rack (13), a traction machine (14) and a cutting device (15) arranged in sequence along the material conveying direction, the three-roller calender (12) comprising a rack (121) and an upper roller (122), a middle roller (123) and a lower roller (124) installed on the rack (121), characterized in that, The lower roller (124) is a cooling roller, which is internally provided with a cooling mechanism (2) for spirally flowing cooling medium in opposite directions, and a throttling mechanism (3) for dynamically adjusting the flow of cooling medium flowing into the cooling mechanism (2) according to the axial temperature distribution of the lower roller (124).

2. The PP slab extrusion line according to claim 1, characterized in that, The cooling mechanism (2) comprises a partition layer (21) coaxially arranged in the roller body (125) of the lower roller (124), a plurality of spiral flow guides (26) are annularly arranged between the partition layer (21) and the inner wall of the roller body (125), a plurality of first flow guide grooves (27) and a plurality of second flow guide grooves (28) are formed between the plurality of spiral flow guides (26), and the spiral directions of the first flow guide grooves (27) and the second flow guide grooves (28) are the same but the cooling medium flow directions are opposite.

3. The PP slab extrusion line according to claim 2, characterized in that, Both ends of the roller body (125) are respectively provided with a blocking plate (22), the blocking plate (22) is sealingly connected with the end portion of the partition layer (21) and the inner wall of the roller body (125), and a plurality of shunt holes (29) are formed in the blocking plate (22) and communicate with the plurality of first flow guide grooves (27).

4. The PP slab extrusion line according to claim 3, characterized in that, Both ends of the roller body (125) are respectively provided with a partition plate (23), the partition plate (23) divides the end space into a first shunt cavity (24) close to the blocking plate (22) and a second shunt cavity (25) close to an end cover plate (127) of the roller body (125), and a plurality of shunt rods (210) are arranged between the partition plate (23) and the blocking plate (22) and communicate with the plurality of second flow guide grooves (28).

5. The PP slab extrusion line according to claim 4, characterized in that, Both ends of the lower roller (124) are provided with roller shafts (126), a first flow channel (211) communicating with the first shunt cavity (24) and a second flow channel (212) communicating with the second shunt cavity (25) are respectively formed in each roller shaft (126), the first flow channel (211) and the second flow channel (212) are respectively used for inflow and outflow of the cooling medium, and the inflow and outflow functions of the flow channels corresponding to the roller shafts (126) at both ends are opposite.

6. The PP slabstock extrusion line according to claim 5, characterized in that The throttling mechanism (3) comprises a first drive groove (31) and a second drive groove (32) formed in the roller shaft (126), a first throttling groove (33) is formed between the first flow channel (211) and the first drive groove (31), and a second throttling groove (34) is formed between the second flow channel (212) and the second drive groove (32).

7. The PP slabstock extrusion line according to claim 6, characterized in that The first drive groove (31) is provided with a first electromagnet (35) and a first magnetic member (36) magnetically repelling the first electromagnet (35), one side of the first magnetic member (36) away from the first electromagnet (35) is fixedly connected with a first throttling plate (37) slidingly connected in the first throttling groove (33), and the first electromagnet (35) is controlled to generate a magnetic field to drive the first magnetic member (36) to move the first throttling plate (37) to adjust the flow area of the first flow channel (211).

8. The PP slabstock extrusion line according to claim 7, characterized in that The second driving slot (32) is provided with a second electromagnet (39) and a second magnetic member (310) magnetically repelling the second electromagnet (39), the side away from the second electromagnet (39) of the second magnetic member (310) is fixedly connected with a second throttling plate (311) slidingly connected in the second throttling slot (34), the second electromagnet (39) is controlled to generate a magnetic field to drive the second magnetic member (310) to move the second throttling plate (311) to adjust the flow area of the second flow channel (212).

9. The PP slabstock extrusion line according to claim 8, characterized in that The first magnetic member (36) and the inner wall of the first driving slot (31) are connected with a first elastic member (38), and the second magnetic member (310) and the inner wall of the second driving slot (32) are connected with a second elastic member (312).

10. The PP slabstock extrusion line according to claim 9, characterized in that A plurality of temperature sensors (313) are uniformly arranged on the inner wall of the separation layer (21) along the axial direction of the roller body (125), and the temperature sensor (313), the first electromagnet (35) and the second electromagnet (39) are electrically connected with the controller, so as to control the action of the first electromagnet (35) and the second electromagnet (39) according to the signal of the temperature sensor (313).

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