A longitudinal stretching device and method with adjustable stretching gap

Abstract

The application discloses a longitudinal stretching device with adjustable stretching gap and a stretching method, and belongs to the field of film stretching. The longitudinal stretching device with adjustable stretching gap comprises a main body frame, a moving frame, an elevator assembly and a stretching roller group from bottom to top, the elevator assembly comprises a mounting seat, an elevator, a shaft coupling, a connecting rod, a speed reducer, a motor and a linear guide rail, the moving frame moves linearly along the linear guide rail through the elevator. The moving frame is connected to the main body frame through the linear guide rail and the elevator, the moving frame is driven to move along the linear guide rail through the elevator, the left and right moving frames can move synchronously, and the linear guide rail is obliquely arranged on the main body frame and the moving frame, so that the moving frame can move in the up-down and left-right directions.

Description

Technical Field

[0001] This invention relates to the field of film stretching, and more specifically to a longitudinal stretching device and stretching method with adjustable stretching gap. Background Technology

[0002] Longitudinal stretching machines, as core equipment in the film manufacturing process, have been widely used and continuously developed in the plastics processing field in recent years. By precisely controlling process parameters such as stretching speed, temperature, and stretching ratio, they achieve significant improvements in film performance. During longitudinal stretching, the film is heated by preheating rollers, then stretched longitudinally by stretching rollers, and finally cooled and shaped on cooling rollers. Longitudinal stretching machines have a small footprint, high speed control precision, adjustable stretching roller spacing, and can allow for independent speed adjustment of each roller or synchronous control of the entire machine, making the stretching process controllable.

[0003] For example, patent CN112026153A discloses a film longitudinal stretching machine, including a frame with a preheating station, a stretching station, and a shaping station arranged sequentially on the frame. Each station has several work roller assemblies, and the stretching roller assembly is rotatably connected to the frame. A lifting mechanism drives the stretching rollers to move up and down. One of the stretching rollers can adjust the wrap angle between the film and the stretching roller. The frame also has a holding assembly for adhering the film. The structure described in this patent is complex, inconvenient for installation and maintenance, and the instability of the frame structure can easily cause vibration of the roller assembly during operation.

[0004] In existing longitudinal stretching machines, the stretching roller assembly is typically driven by installing a geared motor and universal coupling on each roller, or by connecting the roller assembly to a gearbox via a high-power motor. However, this structure is space-consuming, complex, and difficult to maintain and repair. Furthermore, the position of the stretching roller assembly in a film longitudinal stretching machine is fixed and cannot be adjusted. This prevents the machine from being adjusted according to differences in film materials during operation, limiting its flexibility.

[0005] In summary, the large structural volume of the longitudinal stretching machine during film stretching makes maintenance or operation inconvenient and prone to damage. Furthermore, the fixed positions of the rollers in the stretching machine cannot be adjusted according to production needs, which remains a problem that urgently needs to be solved. Summary of the Invention

[0006] To address the above problems, this invention provides a longitudinal stretching device and stretching method with adjustable stretching gap. By setting a movable frame, the roller group is configured as a movable roller group to meet the production process requirements of different films and facilitates installation and maintenance.

[0007] The present invention provides a longitudinal stretching device with adjustable stretching gap, which comprises, from bottom to top, a main frame, a movable frame, a lifting assembly and a stretching roller group. The movable frame is mounted on the main frame via a lifting assembly, and the stretching roller assembly is mounted on both the main frame and the movable frame. The lifting assembly includes a mounting base, a lifting platform, a coupling, a connecting rod, a reducer, a motor, and a linear guide rail; The stretching roller assembly includes a fixed roller assembly and a movable roller assembly. The fixed roller assembly is mounted on the main frame, and the movable roller assembly is mounted on the movable frame. The mounting base is installed on the main frame, the lifting platform is installed on the mounting base, and the lifting platform is connected to the movable frame, driving the movable frame to move up and down; The linear guide rail connects the main frame and the movable frame. The movable frame moves in a straight line along the linear guide rail, driven by the elevator. The linear guide rail is installed at an angle.

[0008] Furthermore, the angle between the side of the linear guide rail closest to the main frame and the horizontal is 60-65°.

[0009] Furthermore, the linear guide rail is divided into a guide rail and a slider.

[0010] Furthermore, the main frame is a rectangular frame structure, and the main frame includes support plates on the left and right sides and fixing rods.

[0011] Furthermore, the fixing rod spans between the support plates on the left and right sides, and both ends of the fixing rod are fixed to the support plates on the left and right sides of the main frame by bolts. The support plates on the left and right sides are arranged in parallel and symmetrically.

[0012] Furthermore, height adjustment bolts are symmetrically installed at the four bottom corners and inside and outside of the main frame.

[0013] Furthermore, the height adjusting bolt is used to adjust the height of the main frame. The height adjusting bolt has a coarse thread structure and is equipped with a nut base, which is mounted on the ground plate.

[0014] Furthermore, the movable frame is divided into left and right sides, and the support plates on the left and right sides of the main frame are symmetrically provided with grooves adapted to the size of the movable frame. The movable frame is symmetrically nested on the support plates on the left and right sides of the main frame.

[0015] Furthermore, the movable frame is divided into an upper roller assembly and a lower lifting assembly.

[0016] Furthermore, a mounting plate protrudes from one side of the lifting part, and the mounting plate is fixed to the slider by bolts.

[0017] Furthermore, the two side support plates of the main frame are symmetrically fitted with support plates protruding from the outer wall of the support plates to support and install the guide rail.

[0018] Furthermore, the bottom of the lifting section is also equipped with a limit device to prevent the moving frame and the main frame from colliding or contacting.

[0019] Furthermore, the limiting device is installed on the lifting part, and its direction is opposite to that of the slider.

[0020] Furthermore, the limiting device is a fixing bolt or a fixing plate.

[0021] Furthermore, the main frame and the roller assembly of the movable frame are provided with circular holes that are adapted to the diameter of the roller drive shaft. The area above the circular holes is an open structure, forming a "semi-enclosed" groove for mounting the rollers.

[0022] Furthermore, the movable roller assembly is installed through the circular hole of the movable frame via bearings and bushings, and the fixed roller assembly is installed through the circular hole of the main frame via bearings and bushings. The outer ring of the drive shaft bearing of the roller in the movable roller assembly and the fixed roller assembly is tightly fitted with the wall of the circular hole, and the inner ring is stably connected to the roller drive shaft.

[0023] Furthermore, the rollers in the moving roller group and the fixed roller group are arranged parallel to each other and alternately up and down.

[0024] Furthermore, oil receiving trays are symmetrically installed at the drive shafts at both ends of the rollers of the moving roller group and the fixed roller group. The oil receiving trays are fixedly installed on the bearing seats at both ends of the rollers of the moving roller group and the fixed roller group by bolts, and are used to collect oil droplets when the rollers of the moving roller group and the fixed roller group are working.

[0025] Furthermore, the mounting base is symmetrically mounted on the support plates on the left and right sides of the main frame, located below the movable frame, and parallel to the bottom edge of the movable frame.

[0026] Furthermore, the mounting direction of the mounting base on the movable frame is opposite to the mounting direction of the guide rail.

[0027] Furthermore, the mounting base is equipped with a lifting mechanism, which is rigidly connected to the mounting base by bolts. The lifting mechanism has an internal worm gear and screw structure, which utilizes the meshing of the worm gear and the transmission principle of the screw and nut to convert the horizontal rotation output force of the motor into vertical lifting thrust.

[0028] Furthermore, the elevator is fixedly connected to the movable frame and is arranged parallel to the linear guide rail.

[0029] Furthermore, the connecting rod spans across the main frame and is connected to the elevator at both ends. The elevator is located at both ends of the main frame and synchronously drives the movable frame to move along the linear guide rail.

[0030] Furthermore, the coupling is installed at both ends of the connecting rod, located on one side of the inner wall of the support plates on the left and right sides.

[0031] Furthermore, the motor is mounted outside the elevator on one side and is electrically connected to the elevator.

[0032] Furthermore, the speed reducer is installed between the motor and the elevator.

[0033] Furthermore, one side of the fixed roller group is the film inlet side, and the side of the movable roller group is the film outlet side.

[0034] Furthermore, the vertical distance between the centers of the rollers in the fixed roller group and the moving roller group is 50-100mm, and the horizontal distance between the centers is 150-300mm.

[0035] Furthermore, the vertical movement limit of the movable frame is 80-90mm, and the horizontal movement limit is 40-50mm.

[0036] Furthermore, each roller in the fixed roller group and the moving roller group is equipped with a drive motor.

[0037] The present invention also provides a method for stretching a film using the longitudinal stretching device with adjustable stretching gap, comprising the following steps: Step 1: Adjust the lifting mechanism via the motor in the adjustable tension gap longitudinal tension device to move the moving frame to a preset position in the adjustable tension gap longitudinal tension device. Step 2: Stretch the film from the inlet side of the adjustable stretching gap longitudinal stretching device into the adjustable stretching gap longitudinal stretching device in an alternating up and down manner, and wrap it around the fixed roller group and the moving roller group in sequence. Step 3: Repeatedly adjust the moving frame until it meets the production requirements. After the adjustment is completed, proceed to the next process stage of the film.

[0038] Furthermore, in step 1, the vertical movement limit of the movable frame is 80-90mm, and the horizontal movement limit is 40-50mm.

[0039] Furthermore, in step 2, the rotational speeds of the rollers in the fixed roller group are 0-250 r / min, 0-250 r / min, and 0-850 r / min sequentially from the side where the film enters; the rotational speeds of the rollers in the moving roller group are 0-1100 r / min, 0-1100 r / min, and 0-1100 r / min sequentially from the side where the film enters.

[0040] Furthermore, the stretching ratio of the film in step 3 is 1-7 times.

[0041] The beneficial effects of this invention are: 1. Conventional longitudinal stretching devices use fixed rollers, and the distance between roller groups is not adjustable, making it impossible to adjust the stretching distance according to different production needs. However, this invention sets a movable frame on the main frame, and connects the movable frame to a lift via a linear guide rail. The lift drives the movable frame to move along the linear guide rail. Both the lift and the linear guide rail are installed on both sides of the main frame, so that the movable frames on the left and right sides can move synchronously, ensuring consistency in the film stretching process. The lifts on both sides are connected by a connecting rod, which also ensures synchronous movement of the lifts on both sides. In addition, the linear guide rail in this invention is installed at an angle on the main frame and the movable frame, so that the movable frame can move in both the up and down and left and right directions at the same time. 2. The present invention also installs height-adjustable bolts at the bottom of the main frame, which facilitates the adjustment of the height of the device at any time. In addition, the present invention also installs a limiting device at the bottom of the moving frame to prevent the moving frame from colliding with the main frame uncontrollably when the elevator is damaged. The present invention realizes the free movement of the roller group through a simple elevator and linear guide rail, and stretches the film by the different rotation speeds between each roller group. The device in the present invention can adapt to films of different materials and different process requirements, with high stretching efficiency and high applicability, and is suitable for the production of stretching processes in various industries. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the longitudinal tensioning device with adjustable tension gap described in this invention. Figure 2 This is a side view of the belt roller assembly of the longitudinal stretching device with adjustable stretching gap described in this invention; Figure 3 This is a side view of the longitudinal stretching device with adjustable stretching gap described in this invention without rollers. Figure 4 This is a schematic diagram of the moving frame of the longitudinal tensioning device with adjustable tension gap described in this invention. Figure 5 This is a side view of the lifting assembly of the adjustable tension gap longitudinal tensioning device described in this invention; Figure 6 This is a schematic diagram of the lifting assembly of the adjustable tension gap longitudinal tensioning device described in this invention; The names of the labels in the diagram are as follows: 1. Main frame; 2. Moving frame; 3. Mounting base; 4. Lifting machine; 5. Coupling; 6. Connecting rod; 7. Reducer; 8. Motor; 9. Linear guide rail; 10. Fixed roller group; 11. Moving roller group; 201. Roller group section; 202. Lifting section. Detailed Implementation

[0043] The invention will be described in detail below with reference to the embodiments: This invention provides a longitudinal stretching device and stretching method with adjustable stretching gap. By setting up stretchable roller groups, its adaptability to various films or process conditions is greatly improved.

[0044] Example 1 This embodiment provides a longitudinal stretching device with adjustable stretching gap, which includes, from bottom to top, a main frame 1, a movable frame 2, a lifting assembly, and a stretching roller group. The movable frame 2 is mounted on the main frame 1 via a lifting assembly, and the stretching roller group is mounted on the main frame 1 and the movable frame 2; The lifting assembly includes a mounting base 3, a lifting platform 4, a coupling 5, a connecting rod 6, a reducer 7, a motor 8, and a linear guide rail 9; The stretching roller assembly includes a fixed roller assembly 10 and a movable roller assembly 11. The fixed roller assembly 10 is mounted on the main frame 1, and the movable roller assembly 11 is mounted on the movable frame 2. The mounting base 3 is mounted on the main frame 1, the lifting platform 4 is mounted on the mounting base 3, and the lifting platform 4 is connected to the movable frame 2, driving the movable frame 2 to move up and down; The linear guide rail 9 connects the main frame 1 and the movable frame 2. The movable frame 2 moves in a straight line along the linear guide rail 9 and is driven by the elevator 4. The linear guide rail 9 is installed at an angle.

[0045] In this embodiment, the linear guide rail 9 has an angle of 63° with the horizontal on the side closest to the main frame 1. The inclined linear guide rail 9 can change the direction of force. When the moving frame 2 moves along the linear guide rail 9 under the action of the elevator 4, the force decomposition results in force components in both the direction perpendicular to the guide rail and the horizontal direction. The vertical component helps to stably lift or lower the moving frame 2, while the horizontal component can counteract the lateral tension generated by the material during the stretching process, preventing the stretching roller group from shifting due to lateral force. Secondly, the inclined angle makes the device more space-efficient. Compared with vertically or horizontally installed guide rails, this inclined angle can increase the travel of the moving frame 2 without increasing the device's floor space, thereby expanding the adjustment range of the stretching gap and adapting to the stretching requirements of more types of materials. The linear guide 9 is divided into a guide rail and a slider; The main frame 2 is a rectangular frame structure, and the main frame 1 includes support plates and fixing rods on the left and right sides; The fixing rod spans between the support plates on the left and right sides, and both ends of the fixing rod are fixed to the support plates on the left and right sides of the main frame by bolts. The support plates on the left and right sides are arranged in parallel and symmetrically. Height adjustment bolts are symmetrically installed at the four corners of the bottom of the main frame 1, both inside and outside. By adjusting these bolts, the levelness of the main frame 1 can be precisely adjusted. In the initial stage of installation, the ground may be uneven. The height adjustment bolts can keep the main frame 1 level, providing a good foundation for the subsequent lifting and lowering of the moving frame 2 and the normal operation of the fixed roller group 10 and the moving roller group 11. The symmetrical installation of the height adjustment bolts at the four corners of the bottom provides a more uniform support force. The height adjusting bolt is used to adjust the height of the main frame 1. The height adjusting bolt has a coarse thread structure and is equipped with a nut base, which is installed on the ground plate. The movable frame 2 is divided into left and right sides. The support plates on the left and right sides of the main frame 1 are symmetrically provided with grooves that are adapted to the size of the movable frame 2. The movable frame 2 is symmetrically nested on the support plates on the left and right sides of the main frame 1. The movable frame 2 is divided into an upper roller assembly 201 and a lower lifting assembly 202; A mounting plate protrudes from one side of the lifting part 202, and the mounting plate is fixed to the slider by bolts; The main frame 1 also has symmetrical support plates protruding from the outer wall of the support plates on both sides for supporting and installing the guide rails. The bottom of the lifting part 202 is also equipped with a limiting device to prevent the moving frame 2 from colliding or contacting the main frame 1. The limiting device can effectively prevent the moving frame 2 from colliding with the main frame 1 due to the malfunction of the lifting machine 4 or program error during the lifting process, so as to damage the frame structure, affect the accuracy of the stretching roller group, or affect the stretching effect. The limiting device is installed on the lifting part 202 and is in the opposite direction to the slider. The limiting device is a fixing bolt; Both the main frame 1 and the roller assembly 201 of the movable frame 2 have circular holes adapted to the diameter of the roller drive shaft. The upper part of the circular holes is an open structure, forming a "semi-enclosed" type slot for installing the roller. The "semi-enclosed" type slot is convenient for installing the roller. Compared with the traditional completely closed or complex installation structure, it is simple and greatly improves the installation efficiency. It also reduces the damage that may be caused to the roller and the slot during the installation process. At the same time, when the roller needs to be repaired, cleaned or replaced, the operator can easily access the roller from above. The tight fit between the circular holes and the roller drive shaft can effectively prevent the roller from moving in the horizontal direction and ensure the stability of the roller's position during operation. The movable roller group 11 is installed through the circular hole of the movable frame 2 via bearings and bushings, and the fixed roller group 10 is installed through the circular hole of the main frame 1 via bearings and bushings. The outer ring of the drive shaft bearing of the roller in the movable roller group 11 and the fixed roller group 10 is tightly fitted with the wall of the circular hole, and the inner ring is stably connected to the roller drive shaft. The rollers in the movable roller group 11 and the fixed roller group 10 are parallel and alternately arranged up and down; Oil receiving trays are symmetrically installed at the drive shafts at both ends of the rollers of the movable roller group 11 and the fixed roller group 10. The oil receiving trays are fixedly installed on the bearing seats at both ends of the rollers of the movable roller group 11 and the fixed roller group 10 by bolts, and are used to collect oil droplets when the rollers of the movable roller group 11 and the fixed roller group 10 are working. The mounting base 3 is symmetrically installed on the support plates on the left and right sides of the main frame 1, located below the movable frame 2 and parallel to the bottom edge of the movable frame 2. Since the lifting machine 4 and the linear guide rail 9 are arranged in parallel, precise control can be achieved when adjusting the tension gap. The parallel structure helps to accurately determine the position of the movable frame 2, thereby accurately adjusting the gap between the fixed roller group 10 and the movable roller group 11. At the same time, the fixed connection between the lifting machine 4 and the movable frame 2 can effectively transmit the force generated by the lifting machine 4 to the movable frame 2. During the process of lifting or lowering the movable frame 2, the force can be evenly distributed along the direction of the linear guide rail 9, reducing the generation of lateral force. This helps to protect the various components of the device, reduce the possibility of wear and damage, and also ensure the service life and reliability of the device. The mounting direction of the mounting base 3 on the movable frame 2 is opposite to the mounting direction of the guide rail; The mounting base 3 is equipped with a lifting machine 4, which is rigidly connected to the mounting base 3 by bolts. The lifting machine 4 has a worm gear and screw structure inside, which uses the meshing of worm gear and screw and nut transmission principle to convert the horizontal rotation output force of the motor 8 into vertical lifting thrust. The elevator 4 is fixedly connected to the movable frame 2 and is arranged parallel to the linear guide rail 9; The connecting rod 6 spans across the main frame 1 and is connected to the elevator 4 at both ends. The elevator 4 is located at both ends of the main frame 1 and synchronously drives the moving frame 2 to move along the linear guide rail 9. The coupling 5 is installed at both ends of the connecting rod 6, located on one side of the inner wall of the support plates on the left and right sides; The motor 8 is installed outside the elevator 4 on one side and is electrically connected to the elevator 4; The speed reducer 7 is installed between the motor 8 and the elevator 4.

[0046] The fixed roller group 10 has one side as the film inlet side, and the movable roller group 11 has one side as the film outlet side. The vertical distance between the centers of the rollers in the fixed roller group 10 and the movable roller group 11 is 65mm, and the horizontal distance between the centers is 200mm. The vertical movement limit of the movable frame 2 is 89mm, and the horizontal movement limit is 45mm. Each roller in the fixed roller group 10 and the moving roller group 11 is equipped with a drive motor.

[0047] This embodiment also provides a method for stretching a film using the adjustable stretching gap longitudinal stretching device, comprising the following steps; Step 1: Adjust the lifting machine 4 through the motor 8 in the adjustable tension gap longitudinal tension device, and drive the moving frame 2 to move to the preset position in the adjustable tension gap longitudinal tension device. Step 2: The film is stretched from the inlet side of the adjustable stretching gap longitudinal stretching device into the device in an alternating up-and-down manner, and then wound sequentially around the fixed roller group 10 and the movable roller group 11. The rotational speeds of the rollers in the fixed roller group 10 are 212 r / min, 215 r / min, and 227 r / min from the film entry side; the rotational speeds of the rollers in the movable roller group 11 are 868 r / min, 1000 r / min, and 1060 r / min from the film entry side. Step 3: Repeatedly adjust the moving frame 2 until the production requirements are met. After the adjustment is completed, start the next process stage of the film. The film is stretched by 5 times.

[0048] In this embodiment, the thickness of the film before stretching by the longitudinal stretching device with adjustable stretching gap is 2 mm, and the thickness after stretching is 0.4 mm.

[0049] As can be seen from the above, the adjustable tension gap longitudinal tensioning device of the present invention has a wide range of applications, low cost, and a very high market prospect.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A longitudinal tensioning device with adjustable tension gap, characterized in that, The adjustable tension gap longitudinal tensioning device comprises, from bottom to top, a main frame (1), a movable frame (2), a lifting assembly, and a tensioning roller group; The movable frame (2) is mounted on the main frame (1) via a lifting assembly, and the stretching roller assembly is mounted on the main frame (1) and the movable frame (2); The lifting assembly includes a mounting base (3), a lifting platform (4), a coupling (5), a connecting rod (6), a reducer (7), a motor (8), and a linear guide rail (9); The stretching roller assembly includes a fixed roller assembly (10) and a movable roller assembly (11). The fixed roller assembly (10) is mounted on the main frame (1), and the movable roller assembly (11) is mounted on the movable frame (2). The mounting base (3) is mounted on the main frame (1), the elevator (4) is mounted on the mounting base (3), the elevator (4) is connected to the movable frame (2), and drives the movable frame (2) to move up and down; The linear guide rail (9) connects the main frame (1) and the moving frame (2). The moving frame (2) moves in a straight line along the linear guide rail (9) and is driven by the elevator (4). The linear guide rail (9) is installed at an angle. The angle between the side of the linear guide rail (9) closest to the main frame (1) and the horizontal is 60-65°. The mounting base (3) is symmetrically installed on the support plates on the left and right sides of the main frame (1), located below the movable frame (2), and parallel to the bottom edge of the movable frame (2); The elevator (4) is fixedly connected to the movable frame (2) and is set parallel to the linear guide rail (9); The mounting direction of the mounting base (3) is opposite to the mounting direction of the guide rail on the movable frame (2).

2. The longitudinal tensioning device with adjustable tension gap according to claim 1, characterized in that, The main frame (1) is symmetrically equipped with height adjustment bolts at the four bottom corners and inside and outside.

3. The longitudinal tensioning device with adjustable tension gap according to claim 1, characterized in that, The movable frame (2) is divided into left and right sides. The support plates on the left and right sides of the main frame (1) are symmetrically provided with grooves adapted to the size of the movable frame (2). The movable frame (2) is symmetrically nested on the support plates on the left and right sides of the main frame (1).

4. The longitudinal tensioning device with adjustable tension gap according to claim 1, characterized in that, The movable frame (2) is divided into an upper roller group section (201) and a lower lifting section (202).

5. The longitudinal tensioning device with adjustable tension gap according to claim 4, characterized in that, The bottom of the lifting part (202) is also equipped with a limiting device to prevent the moving frame (2) and the main frame (1) from colliding or contacting.

6. The longitudinal tensioning device with adjustable tension gap according to claim 4, characterized in that, Both the main frame (1) and the roller assembly (201) of the movable frame (2) have circular holes that are adapted to the diameter of the roller drive shaft. The upper part of the circular holes is an open structure, forming a "semi-enclosed" slot for installing the rollers.

7. A method for stretching a thin film using a longitudinal stretching device with adjustable stretching gap as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Adjust the lifting machine (4) through the motor (8) in the adjustable tension gap longitudinal tension device, and drive the moving frame (2) to move to the preset position in the adjustable tension gap longitudinal tension device. Step 2: Stretch the film from the inlet side of the adjustable stretching gap longitudinal stretching device into the adjustable stretching gap longitudinal stretching device in an alternating up and down manner, and wrap it around the fixed roller group (10) and the moving roller group (11) in sequence. Step 3: Repeatedly adjust the moving frame (2) until the production requirements are met. After the adjustment is completed, start the next process stage of the film.

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