Longitudinal stretching equipment for wide lithium battery diaphragm

Abstract

The longitudinal stretching equipment comprises a machine frame, a preheating unit, a stretching unit and a shaping unit, the preheating unit, the stretching unit and the shaping unit are arranged on the machine frame from back to front, the preheating unit comprises a plurality of preheating roller sets rotationally arranged on the machine frame, and each preheating roller set comprises a preheating roller, a preheating pressing roller and a scraper assembly; the multiple preheating rollers are arranged in an up-down staggered mode, a first circumferential face covered by a diaphragm and a second circumferential face not covered by the diaphragm are formed on each preheating roller, each preheating pressing roller is synchronously and rotationally connected with the corresponding preheating roller and tightly pressed on the first circumferential face of the corresponding preheating roller, and each scraper assembly is opposite to the second circumferential face of the corresponding preheating roller. Each first scraper assembly comprises a first scraper and an oil suction assembly, and the oil suction assembly is communicated with a negative pressure source so as to transfer an oil-water mixture scraped by the first scraper into a collection chamber; the diaphragm is prevented from slipping in the stretching process, the stretching precision is improved, and the thickness uniformity of the diaphragm is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery separator production equipment, in particular to a longitudinal stretching equipment for lithium battery separator. BACKGROUND

[0002] Lithium ion battery separator mainly plays the role of isolating positive and negative electrodes, preventing short circuit and allowing lithium ion conduction in lithium ion battery, and the quality of lithium ion battery separator directly affects the application performance of lithium ion battery. Lithium battery separator has dry and wet process production technology, and the principle of wet preparation of lithium battery separator is mainly: taking paraffin oil as a pore forming agent, mixing the powder with paraffin oil, heating and melting into a uniform system, and then reducing the temperature to cause phase separation. Paraffin oil is a short-chain hydrocarbon with carbon atom number of 8-12. The preparation process of the separator includes the steps of extruding a casting sheet, longitudinal stretching, transverse stretching, extraction, drying and transverse stretching heat setting. Finally, a micro-porous separator is prepared. The role of extraction and drying is to extract the pore forming agent from the pores of the separator, present micro-pores that can allow lithium ions to pass through, replace the pore forming agent with a solvent, and the drying process is to accelerate the volatilization of the extraction agent and replace the extraction agent with air.

[0003] That is, in the steps before extraction, paraffin oil always exists in the separator, so in the traditional lithium battery separator processing process, the surface of the separator is always infiltrated with paraffin oil during longitudinal stretching and transverse stretching, especially during the longitudinal stretching process. After the separator is just cleaned (the cleaning process temperature is lower than 40℃), the surface has both oil and water, which causes the separator to slip on the surface of the stretching roller during stretching, the stretching roller cannot stretch the separator at the preset stretching ratio, and the paraffin oil in the separator cannot be smoothly separated from the polymer material, so that the thickness of the stretched separator is not uniform, and the stretching precision is low. SUMMARY

[0004] In order to solve the technical problem of slippage of the above-mentioned wet-process produced separator during stretching, the purpose of the present application is to provide a longitudinal stretching equipment for wide lithium battery separator, which can remove part of the liquid on the surface of the lithium battery separator before longitudinal stretching, avoid the film slipping during stretching, and improve the uniformity of the thickness of the separator.

[0005] To achieve the above object, the technical scheme adopted by the present application is as follows: A longitudinal stretching equipment for wide lithium battery diaphragm, comprising: a rack, a preheating unit, a stretching unit and a setting unit arranged in sequence from back to front on the rack, the preheating unit comprises a plurality of preheating roller groups arranged on the rack, each preheating roller group comprises a preheating roller, a preheating pressure roller and a scraper assembly, a plurality of preheating rollers are arranged staggered up and down, and the projections of a plurality of preheating rollers on a horizontal plane do not overlap each other, so that the diaphragm passes through a plurality of preheating rollers in an "S" shape from back to front, and the temperature of each preheating roller gradually increases from back to front; a first peripheral surface covered by the diaphragm and a second peripheral surface not covered by the diaphragm are formed on each preheating roller, each preheating pressure roller is synchronously connected with each preheating roller and is pressed on the first peripheral surface of each preheating roller, and each scraper assembly is opposite to the second peripheral surface of each preheating roller, in the rotating direction of each preheating roller, the diaphragm contacts the roller surface of the preheating roller before each scraper assembly; the scraper assembly is divided into a first scraper assembly located above the preheating roller and a second scraper assembly located below the preheating roller, each first scraper assembly comprises a first scraper and an oil absorption assembly arranged upstream of the first scraper in the rotating direction of the preheating roller, the oil absorption assembly has a suction port in communication with a negative pressure source and adjacent to the blade part of the first scraper, so as to transfer the oil-water mixture scraped by the first scraper into a collection chamber; the stretching unit comprises a stretching roller group arranged on the rack, each stretching roller group comprises a stretching roller and a stretching pressure roller, a plurality of stretching rollers are arranged staggered up and down, so that the diaphragm passes through a plurality of stretching rollers in an "S" shape from back to front, and the roller speed of a plurality of stretching rollers gradually increases from back to front.

[0006] In the above technical scheme, preferably, the roller temperature of each preheating roller is 80-100℃, and the rotating speed of each preheating roller is 10-30m / min.

[0007] In the above technical scheme, preferably, the rack comprises a pair of wall plates, the first scraper assembly further comprises an angle adjusting member for adjusting the inclination angle of the oil absorption assembly and an adjusting module capable of adjusting the position and inclination angle of the blade of the first scraper in the axial and radial directions, the oil absorption assembly is rotatably connected to the pair of wall plates and is in transmission connection with the angle adjusting member; the adjusting module comprises a first adjusting member for attaching the blade of the first scraper to the corresponding preheating roller and a second adjusting member for adjusting the angle between the blade and the roller surface of the preheating roller.

[0008] In the technical scheme, preferably, each of the scraper assemblies has a blade and a blade seat fixedly mounting the blade, the surface of the preheating roller has a chrome plating layer, the gap between the blade and the preheating roller is less than or equal to 50 microns and forms a non-force mutual abutment, and the gap between the blade and the preheating roller in each of the preheating roller groups gradually decreases from back to front.

[0009] In the technical scheme, preferably, the blade is made of polytetrafluoroethylene or polyamide or polyurethane material, and the thickness of the blade is 2-3 mm.

[0010] In the technical scheme, preferably, the blade seat of the second scraper assembly can move along the radial direction of the corresponding preheating roller and rotate around the axis of the blade seat.

[0011] In the technical scheme, preferably, the suction flow of the oil suction assembly is 10000-20000 m 3 / h.

[0012] In the technical scheme, preferably, each of the preheating rollers coaxially sleeves a driving gear, each of the preheating rollers coaxially sleeves a driven gear, and the driven gear meshes with the driving gear to drive.

[0013] In the technical scheme, preferably, the longitudinal stretching device further comprises a swing mechanism arranged at the rear side of the preheating unit, the swing mechanism comprises a swing roller floatingly arranged on the frame and a swing cylinder drivingly connected between the frame and the swing roller, and the swing cylinder is used to drive the swing roller to swing back and forth in the front-rear direction.

[0014] In the technical scheme, preferably, the lower part of the frame further comprises at least one oil receiving disc, and the at least one oil receiving disc is arranged below the preheating unit.

[0015] The preheating unit of the present application preheats the lithium battery separator before the stretching unit, so that the paraffin oil attached to the separator and the surface of the separator remains fluid at 80-100℃, and at the same time, the oil of the lithium battery separator is pressed out by the pressing roller rotating synchronously with the preheating roller, so as to avoid the battery separator from being stretched during the conveying process. In the present application, the separator first contacts the preheating roller, and the liquid on the surface of the separator is transferred to the surface of the preheating roller. The linear speed of the preheating roller is kept at a relatively low speed of 10-30 m / min, so that the paraffin oil transferred to the surface of the preheating roller is heated for a short time, and then removed by the scraper assembly. Part of the liquid removed by the scraper assembly is collected and transferred by the oil suction assembly, and part of the liquid is collected by the oil receiving disc, so as to avoid being dropped on the surface of the separator again. Since the temperature of each preheating roller gradually increases from back to front, the paraffin oil in the separator is heated and continuously precipitated. After passing through multiple preheating rollers, the oil on the surface of the separator is gradually removed. After passing through the preheating unit, 40% of the oil on the surface of the separator can be removed. In this way, the mixture of oil and water attached to the battery separator entering the stretching unit can be reduced, the separator can be prevented from slipping during the stretching process, the flat conveying of the separator can be ensured, and thus the precision of the stretching and the uniformity of the thickness of the separator can be improved. Since the amount of oil on the surface of the separator is reduced during the preheating process, the oil precipitated during the stretching process can be smoothly transferred to the surface of the separator. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A perspective structural schematic diagram of a longitudinal stretching device provided for an embodiment of the present application is shown in FIG. 1.

[0017] Figure 2 A partial enlarged schematic diagram of A in FIG. 1 is shown in FIG. 2. Figure 1

[0018] A partial enlarged schematic diagram of B in FIG. 1 is shown in FIG. 3. Figure 3 Figure 1 A partial enlarged schematic diagram of C in FIG. 1 is shown in FIG. 4.

[0019] Figure 4 Figure 1 A top view of the longitudinal stretching device in FIG. 1 is shown in FIG. 5.

[0020] Figure 5 A sectional view along line D-D in FIG. 1 is shown in FIG. 6. Figure 1

[0021] A sectional view along line E-E in FIG. 1 is shown in FIG. 7. Figure 6 Figure 5 A structural schematic diagram of the preheating unit in FIG. 1 on the wallboard is shown in FIG. 8.

[0022] Figure 7 Figure 6 A structural schematic diagram of the stretching unit and the setting unit in FIG. 1 on the wallboard is shown in FIG. 9.

[0023] Figure 8 A structural schematic diagram of the stretching unit and the setting unit in FIG. 1 on the wallboard is shown in FIG. 9. Figure 6 ​​​​​

[0024] Figure 9 for Figure 7 A three-dimensional structural diagram of the oil-absorbing component and the corresponding scraper component on the wall panel;

[0025] Figure 10 for Figure 9 Front view of the oil absorption assembly and scraper assembly;

[0026] Figure 11 For along Figure 10 A sectional view cut along the EE line;

[0027] Figure 12 This is a schematic diagram of the second scraper assembly.

[0028] The components are as follows: 100. Longitudinal stretching equipment; 10. Frame; 11. Wall panel; 12. Oil receiving tray; 13. Stainless steel mesh frame; 14. Support frame; 20. Preheating unit; 2. Preheating roller group; 21. Preheating roller; 22. Preheating pressure roller; 23. First scraper assembly; 231. First blade; 232. Adjustment module; 2321. First adjusting component; 2322. Second adjusting component; 233. First blade holder; 24. First adjusting component; 25. Oil suction assembly; 251. Suction port; 252. Angle adjusting component; 253. Air box; 26. First drive motor; 27. Drive gear; 28. Driven gear; 29. ​​Second scraper assembly; 291. Second blade; 292. 1. Second cutter holder; 2. Feed cylinder; 3. Tensioning unit; 3. Tensioning roller group; 3. Tensioning roller; 3. Tensioning pressure roller; 3. Second adjusting component; 3. Second drive motor; 3. Drive gear; 3. Driven gear; 4. Shaping unit; 4. Shaping roller group; 4. Shaping roller; 4. Shaping pressure roller; 4. Third adjusting component; 4. Third drive motor; 4. Drive gear; 4. Driven gear; 7. Rear drive shaft of heavy vehicle; 50. Swinging mechanism; 51. Swinging roller; 52. Swinging cylinder; 53. Swing arm; 60. Film threading traction mechanism; 61. Moving chain; 62. Chain motor; 63. Chain tensioning assembly; 70. Waste film rewinder. Detailed Implementation

[0029] To describe the technical content, structural features, achieved objectives and effects of the application in detail, the technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. In the following description, for the purpose of explanation, many specific details are set forth to provide a detailed description of various exemplary embodiments or implementations of the invention. However, various exemplary embodiments may also be implemented without these specific details or in the case of one or more equivalent arrangements. In addition, various exemplary embodiments may be different, but not necessarily exclusive. For example, without departing from the inventive concept, the specific shapes, structures and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment.

[0030] Hereinafter, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "plurality" is two or more.

[0031] The "front", "rear", "left", "right", "upper", and "lower" described in the present application are in accordance with the front, rear, left, right, upper, and lower shown in the attached Figure 1 The direction of the lithium battery separator passing through the membrane is as shown by the hollow arrow in Figure 6 and the rotation directions of each roller are as shown by the solid arrows.

[0032] In the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or integrated; it can be directly connected or indirectly connected through an intermediate medium.

[0033] The embodiments of the present application provide a longitudinal stretching device for a wide-width lithium battery separator, which is used to longitudinally stretch the separator that has been subjected to primary cleaning, stretch the separator in its length direction, so that the molecular chains of the polymer in the separator are arranged in an orderly manner in the longitudinal direction, and shape the separator so that the orderly arranged macromolecular structure is fixed, thereby improving the performance of the separator.

[0034] As Figure 1As shown in the figure, the longitudinal stretching device 100 includes a frame 10, and a preheating unit 20, a stretching unit 30 and a shaping unit 40 arranged on the frame 10. The preheating unit 20, the stretching unit 30 and the shaping unit 40 are arranged on the frame 10 in sequence from back to front. The frame 10 includes a pair of wallboards 11 arranged opposite to each other left and right, and the pair of wallboards 11 are used to support the preheating unit 20, the stretching unit 30 and the shaping unit 40. The frame 10 further includes an oil tray 12 located below the preheating unit 20, the stretching unit 30 and the shaping unit 40. The oil tray 12 is used to receive the liquid dripping from the preheating unit 20, the stretching unit 30 and the shaping unit 40. The upper end of the oil tray 12 is also covered with a stainless steel grid frame 13 to facilitate the maintenance and repair of the longitudinal stretching device 100 by the staff.

[0035] As Figure 6 , 7 shown, in an embodiment of the present application, the preheating unit 20 includes six preheating roller groups 2 arranged on the frame 10. The six preheating roller groups 2 are arranged in sequence from back to front. Each preheating roller group 2 includes a preheating roller 21 rotatably arranged between a pair of wallboards 11, a preheating pressure roller 22 for pressing the diaphragm against the preheating roller 21, and a scraper assembly for scraping the liquid on the preheating roller 21. In other embodiments, according to different production requirements, the number of preheating roller groups may also be 2, 4, 8, 10, etc.

[0036] [[ID=IO]]In the previous cleaning process, due to the low temperature (below 40°C), the paraffin oil on the surface and inside of the diaphragm is in a solid or semi-solid state and is not easy to remove. The diaphragm cannot be directly stretched at too low a temperature. Therefore, the diaphragm needs to be preheated. In the present application, the surface temperature of the preheating roller 21 in the preheating unit is controlled at 80°C - 100°C, preferably 90°C - 100°C. At this temperature, the paraffin oil in the diaphragm can be kept in a molten state, and at the same time, the stretching temperature of the diaphragm is satisfied. At this temperature, part of the paraffin oil in the diaphragm precipitates and then transfers to the preheating roller and is removed. The linear speed of the preheating roller is kept at a relatively low rotation speed of 10 - 30 m / min, preferably 20 m / min.

[0037] The plurality of preheating rollers 21 are arranged in an up-down staggered manner, so that the lithium battery separator passes through the plurality of preheating rollers 21 in an "S" shape from back to front, and the preheating pressure rollers 22 and the scraper assemblies are arranged opposite to each other in the radial direction of the preheating rollers 21. Each preheating roller 21 has a first peripheral surface covered by the lithium battery separator and a second peripheral surface not covered by the separator. Each preheating pressure roller 22 is synchronously connected with each preheating roller 21 for rotation and is pressed against the first peripheral surface of each preheating roller 21, and each scraper assembly is opposite to the second peripheral surface of each preheating roller. In the rotation direction of each preheating roller 21, the preheating pressure roller 22 is always located upstream of the first scraper assembly 23, so that the separator contacts the roller surface of the preheating roller before contacting each scraper assembly, thereby transferring the liquid on the surface of the separator to the surface of the preheating roller. The linear speed of the preheating roller is kept at a relatively low speed of 20 m / min, so that the paraffin oil transferred to the surface of the preheating roller can be heated for a short time, and then removed by the scraper assembly. After the separator passes through the plurality of preheating rollers, the oil and water on the surface of the separator are continuously transferred to the preheating roller and removed, so that only about 50% of the oil remains on the surface of the separator after the separator passes through the preheating unit, and the subsequent stretching process is not affected. The rotation speed of the preheating roller affects the removal rate of the oil on the surface of the final separator. The faster the rotation speed of the preheating roller, the more oil is removed. The slower the rotation speed, the less oil is removed, and the more oil remains on the surface of the separator.

[0038] In an embodiment of the present application, the temperatures of the plurality of preheating rollers gradually increase from back to front. For example, the temperature of a preheating roller is greater than that of an adjacent preheating roller located on the rear side. For example, the temperatures of the plurality of preheating rollers from back to front are 85℃, 87℃, 90℃, 95℃, 97℃, and 100℃, respectively. Alternatively, the temperatures of the first and second preheating rollers are the same, the temperatures of the third and fourth preheating rollers are the same, and the temperatures of the fifth and sixth preheating rollers are the same. For example, the temperatures of the first and second preheating rollers are 90℃, the temperatures of the third and fourth preheating rollers are 95℃, and the temperatures of the fifth and sixth preheating rollers are 100℃. The gradual increase in the temperature of each preheating roller from back to front causes the paraffin oil in the separator to be heated and continuously precipitated, and the oil on the surface of the separator is gradually removed after passing through the plurality of preheating rollers. Due to the reduction in the amount of oil on the surface of the separator during the preheating process, the oil precipitated during the stretching process can be smoothly transferred to the surface of the separator.

[0039] Each preheating pressure roller 22 is pressed against the lithium battery separator and synchronously rotates with the preheating roller 21, for pressing the moving lithium battery separator against the corresponding preheating roller 21 to remove the oil adhered to the separator. Each scraper assembly is away from the separator and scrapes the oil on the surface of the preheating roller 21, which does not affect the work of the preheating pressure roller 22 and the movement of the separator, and can scrape the liquid on the preheating roller 21, avoiding that too much liquid on the preheating roller 21 affects the movement and stretching of the separator.

[0040] The scraper assembly is divided into a first scraper assembly 23 located above the preheating roller 21 and a second scraper assembly 29 located below the preheating roller 21. Each first scraper assembly 23 located above the preheating roller has a first scraper and an oil suction assembly 25 located upstream of the first scraper in the rotation direction of the preheating roller. The oil suction assembly 25 has a suction port in communication with a negative pressure source and adjacent to the first scraper blade to transfer the oil-water mixture scraped by the first scraper from the second surface of the preheating roller into a collection chamber to avoid dropping on the surface of the diaphragm again. In an embodiment, the suction flow rate of the oil suction assembly is 10000-20000 m 3 / h. Preferably, the suction flow rate of the oil suction assembly is 15000 m 3 / h. When the lithium battery diaphragm is continuously conveyed forward, the first scraper scrapes the excess oil and water on the surface of the preheating roller and collects and transfers them to the collection chamber through the suction assembly 25 to avoid dropping on the surface of the lithium battery diaphragm to form pollution.

[0041] The second scraper assembly 29 located below the preheating roller has a second scraper which scrapes the second surface of the preheating roller 21 and the scraped oil and water flow downward and are collected by the oil pan 12.

[0042] Please continue to see Figure 7 , the preheating pressure roller 22 is floatingly arranged between a pair of wall plates 11, and the preheating unit 20 further includes six first adjusting members 24 which are drivingly connected between the corresponding preheating pressure roller 22 and the wall plate 11 and are used to adjust the distance between the surface of the preheating pressure roller 22 and the surface of the corresponding preheating roller 21. The first adjusting member 24 controls the preheating pressure roller 22 to move away from the preheating roller 21 when the diaphragm is being threaded, and controls the preheating pressure roller 22 to move close to the preheating roller 21 after the threading is completed to press the diaphragm on the preheating roller 21, thereby avoiding the diaphragm from being deviated and wrinkled during the conveying process and being able to scrape the oil and moisture on the surface of the diaphragm.

[0043] As shown in Figure 1 , 2 , each preheating roller 21 is drivingly connected with a first driving motor 26 and rotates around the axis thereof under the driving of the first driving motor 26. Each preheating roller 21 coaxially sleeves a driving gear 27 which rotates synchronously with the preheating roller 21. Each preheating pressure roller 22 coaxially sleeves a driven gear 28 which engages with the driving gear 27 when the driven gear 28 is pressed on the driving gear 27 of the corresponding preheating roller 21. When the driving gear 27 rotates, the driven gear 28 drives the preheating pressure roller 22 to rotate around the axis, so that the linear speed of the preheating pressure roller 22 is consistent with that of the corresponding preheating roller 21. The preheating pressure roller is made of rubber material and can play a role in traction and flattening of the diaphragm.

[0044] Please continue to see Figure 6and Figure 7 The diaphragm bypasses above the upper preheating roller 21 and below the lower preheating roller 21 in the moving path of the preheating unit 20. The preheating pressure roller 22 arranged for the upper preheating roller 21 is located above the corresponding preheating roller 21, and the preheating pressure roller 22 arranged for the lower preheating roller 21 is located below the corresponding preheating roller 21.

[0045] As Figures 9-12 shown, the oil absorption component 25 and the corresponding first blade assembly 23 are installed adjacent to each other on the wall panel 11. The first blade assembly 23 includes a first blade 2*31*, a first blade holder 233 for installing the first blade 231, and an adjustment module 232传动连接 with the first blade holder 233. The first blade 231 is made of polytetrafluoroethylene or polyamide or polyurethane material, preferably a material with a certain hardness, and the surface of the preheating roller is plated with a chromium layer, making it equally not easily scratched.

[0046] The second blade assembly 29 includes a feed cylinder 293 fixedly arranged on the frame 10, a second blade holder 292 rotatably connected to the piston rod of the feed cylinder, and a second blade 291 fixed on the second blade holder 292. The angle of the second blade 291 can be adjusted by rotating the second blade holder 292, and at the same time, the second blade holder 292 can also move up and down relative to the preheating roller.

[0047] In one embodiment, the first blade 231 abuts against the preheating roller 21 without force, the gap between the blade and the roller surface is 30 - 50 microns, and the blade thickness is 2 - 3 mm. On the one hand, this can prevent the blade from damaging the surface of the preheating roller, and on the other hand, it can remove the liquid on the surface of the preheating roller. To achieve an ideal oil removal effect, from the back to the front, the gap between the blade and the preheating roller in each preheating roller group gradually decreases.

[0048] See Figure 11 、 12 , in one embodiment, the blades of each blade assembly are at an acute angle to the rotation direction of each preheating roller. The blades are inclined along the rotation direction, which can reduce friction and leave the scraped liquid behind the rotation direction, keeping the roller surface in front of the blade assembly clean.

[0049] It should be noted that there is an unclear expression "传动连接" in the original text which is translated as "传动连接" for now. It may need to be further clarified and accurately translated according to the specific technical term.The adjusting module 232 of the first doctor blade assembly includes a first adjusting piece 2321 for approaching the first blade 231 to the corresponding preheating roller 21 and a second adjusting piece 2322 for adjusting the angle between the first blade 231 and the preheating roller 21; in the embodiment, the first adjusting piece 2321 is a pneumatic cylinder, which pushes the first blade holder 233 to approach and move away from the preheating roller 21, and the second adjusting piece 2322 is a manual rotary speed reducer, which is in transmission connection with the first blade holder 233 through a worm and gear structure. The adjusting module 232 is used for quickly adjusting the distance and angle between the first blade 231 and the surface of the corresponding preheating roller 21, thereby improving the working efficiency. The oil suction assembly 25 includes a suction port 251 for generating suction negative pressure and an angle adjusting piece 252 for adjusting the angle of the suction port 251, and the angle adjusting piece 252 is also a manual rotary speed reducer. The angle adjusting piece 252 is installed on the outer side of the wall plate 11 and is in transmission connection with a bellows 253 having the suction port 251 through a worm and gear structure. The angle adjusting piece 252 can adjust the angle between the suction port 251 and the surface of the corresponding preheating roller 21, so that the suction port 251 faces the joint between the corresponding doctor blade assembly 23 and the preheating roller 21, thereby improving the suction efficiency.

[0050] As shown in Figure 6 、 8 , the stretching unit 30 is arranged on the front side of the preheating unit 20 and includes eight stretching roller groups 3 arranged in sequence from back to front, each stretching roller group 3 including a stretching roller 31 rotatably arranged between a pair of wall plates 11 and a stretching pressure roller 32 for pressing the diaphragm on the stretching roller 31; the eight stretching rollers 31 of the stretching unit 30 are alternately arranged up and down from back to front. The diameter of the stretching roller 31 is smaller than the diameter of the preheating roller 21, and the diameter of the preheating roller 21 is greater than twice the diameter of the stretching roller 31. The diaphragm is sequentially wound around the plurality of stretching rollers 31 in an "S" shape from back to front, and the stretching pressure roller 32 is arranged adjacent to the moving path of the diaphragm for pressing the diaphragm on the corresponding stretching roller 31. The rotation speeds of the eight stretching rollers 31 of the stretching unit 30 are different, and the rotation speeds of the eight stretching rollers 31 gradually increase from back to front, so that the diaphragm is stretched in the longitudinal direction through the speed difference between adjacent two rollers.

[0051] The diaphragm passes above the upper stretching roller 31 and below the lower stretching roller 31 in the moving path of the stretching unit 30. In order not to affect the transportation of the diaphragm in the stretching unit 30, the stretching pressure roller 32 arranged with the upper stretching roller 31 is above the corresponding stretching roller 31, and the stretching pressure roller 32 arranged with the lower stretching roller 31 is below the corresponding stretching roller 31. Each stretching pressure roller 32 is floatingly arranged between a pair of wall plates 11, and the stretching unit 30 further comprises a plurality of second adjusting members 33, each of which is drivingly connected between the corresponding stretching pressure roller 32 and the wall plate 11, and is used for adjusting the distance between the surface of the stretching pressure roller 32 and the surface of the corresponding stretching roller 31. The working principle of the second adjusting member 33 is consistent with that of the first adjusting member 24, and will not be repeated here. The second adjusting member 33 controls the stretching pressure roller 32 to press the diaphragm on the corresponding stretching roller 31, and plays a role of traction and flattening of the diaphragm in the stretching process.

[0052] As shown in Figure 1 , 3 each stretching roller 31 is drivingly connected with a second driving motor 34, and rotates around its own axis under the driving of the second driving motor 34. Each second driving motor 34 can adjust the rotating speed of the corresponding stretching roller 31, and can change the stretching ratio, thereby improving the stretching efficiency of the stretching unit 30; each stretching roller 31 coaxially sleeves a driving gear 35, and the driving gear 35 rotates with the stretching roller 31; the stretching pressure roller 32 coaxially sleeves a driven gear 36, and when the stretching pressure roller 32 presses the diaphragm on the stretching roller 31 under the control of the second adjusting member 33, the driven gear 36 is engaged with the driving gear 35. When the driving gear 35 rotates, the driven gear 36 drives the stretching pressure roller 32 to rotate, so that the linear speed of the stretching pressure roller 32 is consistent with that of the corresponding stretching roller 31.

[0053] The roller surface temperature of the stretching roller 31 is controlled at 110-130°C, reaching the stretching temperature of the diaphragm. At this time, the paraffin oil in the diaphragm will continue to precipitate as the stretching proceeds. Although the oil in the diaphragm will continue to precipitate during the stretching process, it can ensure that the diaphragm does not slip during the stretching process, and will not affect the uniformity of the thickness of the stretching. Part of the oil on the surface of the diaphragm will drip downward into the oil pan 12 below during the stretching process.

[0054] As shown in Figure 6 , 8As shown, the shaping unit 40 is arranged on the front side of the stretching unit 30 and includes three shaping roller groups 4 arranged in sequence from back to front. Each shaping roller group 4 includes a shaping roller 41 rotatably arranged between a pair of wall panels 11 and a shaping pressure roller 42 for pressing the diaphragm against the shaping roller 41. The three shaping rollers 41 of the shaping unit 40 are arranged alternately up and down from back to front, and the distance between the roller centers of two adjacent shaping rollers 41 in the front-back direction is less than that of the preheating roller 21 and the stretching roller 31. That is, the three shaping rollers 41 are arranged in an inverted "pin" shape, so that the wrap angle of the diaphragm on the shaping roller 41 is greater than that on the preheating roller 21 and the stretching roller 31, increasing the contact area between the diaphragm and the surface of the shaping roller 41 to enable rapid cooling and shaping. The diameter of the shaping roller 41 is the same as that of the preheating roller 21. The diaphragm sequentially bypasses multiple shaping rollers 41 in an "S" shape from back to front. Each shaping pressure roller 42 is arranged adjacent to the moving path of the diaphragm for pressing the diaphragm against the shaping roller 41. The moving path of the diaphragm in the shaping unit 40 bypasses above the shaping roller 41 located on the upper side and below the shaping roller 41 located on the lower side. In order not to affect the conveyance of the diaphragm in the shaping unit, the shaping pressure roller 42 configured for the upper shaping roller 41 is located above the corresponding shaping roller 41, and the shaping pressure roller 42 configured for the lower shaping roller 41 is located below the corresponding shaping roller 41.

[0055] Each shaping pressure roller 42 is floatingly arranged between a pair of wall panels 11. The shaping unit 40 further includes a third adjusting member 43. The third adjusting member 43 is传动连接 (translation error, should be "drivably connected") between the shaping pressure roller 42 and the wall panel 11 for adjusting the distance between the surface of the shaping pressure roller 42 and the surface of the corresponding shaping roller 41. The working principle of the third adjusting member 43 is the same as that of the first adjusting member 24 and will not be elaborated here. The third adjusting member 43 controls the shaping pressure roller 42 to press the diaphragm against the corresponding shaping roller 41, making the diaphragm closely adhere to the surface of the shaping roller 41 for better cooling and shaping. The first adjusting member 24, the second adjusting member 33 and the third adjusting member 43 are all low-friction cylinders. The low-friction cylinders can be adjusted according to the pressure between the pressure roller and the corresponding roller cylinder to ensure the smooth conveyance of the diaphragm.

[0056] ]As shown in Figure 1 、 4 As shown, each shaping roller 41 is drivably connected to a third driving motor 44 and rotates around its own axis under the drive of the third driving motor 44. A driving gear 45 is coaxially sleeved on each shaping roller 41, and the driving gear 45 rotates with the shaping roller 41. A driven gear 46 is coaxially sleeved on the shaping pressure roller 42. The driven gear 46 approaches the shaping roller 41 under the control of the third adjusting member 43 as the shaping pressure roller 42 moves, and meshes with the driving gear 45. When the driving gear 45 rotates, the driven gear 46 drives the shaping pressure roller 42 to rotate, so that the shaping roller 41 and the shaping pressure roller 42 have the same linear velocity.

[0057] It should be noted that there is an error in the description "传动连接" in the original text, which should be "drivably connected" in English.Six preheating rollers 22, eight stretching rollers 32 and three setting rollers 42 are rubber rollers, and the surfaces of the rollers are elastic. The interiors of the six preheating rollers 21, the eight stretching rollers 31 and the three setting rollers 41 are provided with spiral flow channels to pass through heat-conducting medium, and are connected with a roller temperature control system (not shown in the figure). The roller temperature control system adjusts the roller surface temperature of each roller by controlling the temperature of the heat-conducting medium, and ensures that the error between the roller surface temperature of each roller and the set standard temperature is less than 5°, thereby improving the accuracy of roller temperature control. The roller surface temperature of the preheating rollers 21 is controlled at 80-100°C, and the diaphragm is preheated before entering the stretching unit 30, so as to facilitate the stretching of the diaphragm by the subsequent stretching unit 30. The roller surface temperature of the stretching rollers 31 is controlled at 110-130°C, so as to improve and maintain the temperature of the diaphragm to facilitate stretching. The roller surface temperature of the setting rollers 41 is lower than that of the stretching rollers 31 and the preheating rollers 21, so as to facilitate cooling and setting of the diaphragm.

[0058] The two ends of the six preheating rollers 21 and the three setting rollers 41 are respectively provided with bearing seats, and each preheating roller 21 and setting roller 41 is rotatably arranged on the rack 10 about its own axis, and each bearing seat adopts a Haff structure to facilitate the removal of the roller from the bearing seat, and facilitate the disassembly and maintenance of the roller.

[0059] As shown in Figure 1 , 5 , each driving motor is connected with the corresponding roller through a heavy truck rear drive shaft 7. The heavy truck rear drive shaft 7 has the characteristics of large transmission torque, large concentricity adjustment range and installation position floating range, and telescopic length, which facilitates the installation and replacement of the roller, and is especially suitable for longitudinal stretching equipment of diaphragms with large width. The rack 10 includes a support frame 14 supporting the plurality of driving motors, and the support frame 14 is arranged on the outer side of the wall plate 11. Each heavy truck rear drive shaft 7 is supported between the support frame 14 and the wall plate 11 to drive connect the corresponding driving motor and the roller.

[0060] As shown in Figure 1 , 7As shown, a swing mechanism 50 is further arranged at the rear side of the preheating unit 20, which is located at the entrance of the moving path of the diaphragm in the longitudinal stretching device 100, so that the speed of the device outlet upstream of the diaphragm in the longitudinal stretching device 100 matches the speed of the entrance of the longitudinal stretching device 100, which plays a buffering role to avoid problems such as wrinkling caused by speed mismatch; at the same time, the swing mechanism 50 buffers the diaphragm entering the stretching unit 30 from the preheating unit 20, and ensures the smooth conveying of the diaphragm. The swing mechanism 50 includes a swing roller 51 floatingly arranged between a pair of wall plates 11 and a swing cylinder 52 driving the swing roller 51 to swing forward and backward, the swing roller 51 is drivingly connected between the pair of wall plates 11 through a pair of swing arms 53 arranged opposite to each other, the air rod of the swing cylinder 52 is connected with the swing arms 53, and the cylinder body of the swing cylinder 52 is hinged to the wall plates 11, when the air rod extends or retracts relative to the cylinder body, the swing roller 51 swings forward and backward around the connection between the swing arms 53 and the wall plates 11 with the swing arms 53 as the radius; when the diaphragm is conveyed in line, the swing roller 51 swings backward at the entrance of the longitudinal stretching device 100, realizing the short-time storage of part of the diaphragm; the swing roller 51 swings forward at the entrance of the longitudinal stretching device 100, releasing the stored diaphragm, and buffering the diaphragm entering the longitudinal stretching device 100 through the way of storing and releasing the diaphragm.

[0061] As shown in the drawings, Figure 6 The longitudinal stretching device further includes a membrane passing traction mechanism 60, the membrane passing traction mechanism 60 includes a moving chain 61 circulating from rear to front, a chain motor 62 driving the moving chain 61 to move, and a chain tensioning assembly 63 adjusting the tension of the moving chain 61, one side edge of the diaphragm is connected with the moving chain, and the diaphragm is passed between the rollers by the driving of the moving chain 61; the chain tensioning assembly 63 is used to ensure the tightness of the moving chain 61. The longitudinal stretching device 100 further has a waste membrane winding machine 70 at the outlet, which is used to wind the unqualified diaphragm generated when starting, and cut off the connection with the waste membrane winding machine 70 after the diaphragm is qualified, and guide to the next device.

[0062] The longitudinal stretching device of the present application removes the liquid on the diaphragm in time, ensures the smooth conveying of the diaphragm, avoids the slipping of the diaphragm in the stretching process, accurately controls the temperature and speed of each roller, ensures the stretching precision, and ensures the functional requirements of the wide lithium battery diaphragm in the longitudinal stretching.

[0063] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited to the above examples, the above examples and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the spirit and scope of the present application, and the scope of protection of the present application is defined by the appended claims, the specification and their equivalents.

Claims

1. A longitudinal stretching apparatus for wide-format lithium battery separator, comprising: The frame, the preheating unit, the stretching unit and the setting unit are arranged on the frame from back to front, characterized in that the preheating unit comprises a plurality of preheating roller groups arranged on the frame, each of the preheating roller groups comprises a preheating roller, a preheating pressure roller and a scraper assembly, a plurality of the preheating rollers are arranged staggeredly, and the projections of the preheating rollers on a horizontal plane do not overlap with each other, so that the diaphragm passes through the preheating rollers from back to front in an "S" shape, and the temperature of each preheating roller gradually increases from back to front; each preheating roller has a first peripheral surface covered by the diaphragm and a second peripheral surface not covered by the diaphragm, each preheating pressure roller is synchronously connected with each preheating roller and is pressed on the first peripheral surface of each preheating roller, and each scraper assembly is opposite to the second peripheral surface of each preheating roller, and in the rotating direction of each preheating roller, the diaphragm contacts the roller surface of each preheating roller earlier than each scraper assembly; the scraper assembly is divided into a first scraper assembly above the preheating roller and a second scraper assembly below the preheating roller, each first scraper assembly comprises a first scraper and an oil suction assembly arranged upstream of the first scraper in the rotating direction of the preheating roller, the oil suction assembly has a suction port in communication with a negative pressure source and adjacent to the blade of the first scraper, so as to transfer the oil-water mixture scraped by the first scraper into a collection chamber; the stretching unit comprises a stretching roller group arranged on the frame, each stretching roller group comprises a stretching roller and a stretching pressure roller, and a plurality of the stretching rollers are arranged staggeredly, so that the diaphragm passes through the stretching rollers from back to front in an "S" shape, and the roller speed of each stretching roller gradually increases from back to front.

2. The longitudinal stretching apparatus according to claim 1, characterized in that: The roller temperature of each preheating roller is 80-100℃, and the rotating speed of each preheating roller is 10-30m / min.

3. The longitudinal stretching apparatus according to claim 1, characterized in that: The frame comprises a pair of wall plates, the first scraper assembly further comprises an angle adjusting member for adjusting the inclination angle of the oil suction assembly and an adjusting module capable of adjusting the position and inclination angle of the blade of the first scraper in the axial and radial directions, the oil suction assembly is rotatably connected to the pair of wall plates and is in transmission connection with the angle adjusting member, and the adjusting module comprises a first adjusting member for attaching the blade of the first scraper to the corresponding preheating roller and a second adjusting member for adjusting the angle between the blade and the roller surface of the preheating roller.

4. The longitudinal stretching apparatus according to claim 1, characterized in that: Each scraper assembly has a blade and a blade seat for fixing the blade, the surface of the preheating roller has a chromium plating layer, the gap between the blade and the preheating roller is less than or equal to 50 microns, and the blade and the preheating roller abut each other without force, and the gap between the blade and the preheating roller in each preheating roller group gradually decreases from back to front.

5. The machine according to claim 4, characterized in that: The blade is made of polytetrafluoroethylene, polyamide or polyurethane material, and the thickness of the blade is 2-3mm.

6. The machine according to claim 4, characterized in that: The blade seat of the second scraper assembly can move in the radial direction of the corresponding preheating roller and rotate around its own axis.

7. The machine according to claim 1, characterized in that: The suction flow of the oil absorption assembly is 10000-20000m 3 / h.

8. The longitudinal stretching apparatus according to claim 1, characterized in that: Each of the preheating rollers is coaxially sleeved with a driving gear, each of the preheating compression rollers is coaxially sleeved with a driven gear, and the driven gears are in meshing transmission with the driving gears.

9. The machine according to claim 1, characterized in that: The longitudinal stretching device further comprises a swing mechanism arranged at the rear side of the preheating unit, the swing mechanism comprises a swing roller floatingly arranged on the frame and a swing cylinder in transmission connection between the frame and the swing roller, and the swing cylinder is used to drive the swing roller to swing back and forth in the front-rear direction.

10. The longitudinal stretching apparatus according to claim 1, characterized in that: The lower part of the frame is further provided with at least one oil receiving tray, and the at least one oil receiving tray is arranged below the preheating unit.

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