A biaxial stretching apparatus for a film
By connecting the central slider with the side slider and controlling it with a servo motor, the problem of unevenness caused by clamp synchronization error in existing film stretching equipment is solved, realizing uniform force on the film during biaxial stretching, and improving product quality and equipment adaptability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 扬州博恒新能源材料科技有限公司
- Filing Date
- 2024-04-17
- Publication Date
- 2026-07-31
AI Technical Summary
In existing film stretching equipment, the movement of the clamps relies on a linear motor, which leads to synchronization errors, affects the uniformity of stretching, and causes wrinkles and uneven thickness in the film, reducing product quality and production efficiency.
The design employs a central slider connected to side sliders, and the movement of the clamps is precisely controlled by slider servo motors and shift servo motors to ensure that the film is subjected to uniform force in both longitudinal and transverse directions. The adjustable side guide rail spacing is used to accommodate films of different widths, and the stretching process is optimized by combining a preheating box and an infrared thermometer.
This method achieves uniform stress on the film during biaxial stretching, avoiding wrinkles and uneven thickness, improving stretching quality and equipment flexibility, and reducing production costs.
Smart Images
Figure CN118219543B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of thin film processing technology, specifically to a biaxial stretching device for thin films. Background Technology
[0002] Film, namely polyethylene terephthalate film, is an important polymer material that is widely used in packaging, electronics, insulation materials, decorative materials and other fields due to its excellent physical properties, chemical stability and processing performance.
[0003] Biaxial stretching is a crucial process in film production. Stretching not only allows PET films to reach a predetermined thickness but also improves their physical and mechanical properties, such as tensile strength, impact resistance, and crease resistance. It also enhances optical properties, such as increasing transparency and reducing haze. Furthermore, biaxial stretching makes the molecular chains of the film more regularly arranged, thereby improving its thermal and dimensional stability.
[0004] Existing stretching equipment uses clamps to hold the film and move it along a surrounding guide track. These clamps move within the stretching zone and then return to the entry zone. However, the movement of the clamps in this device relies on linear motors, requiring numerous linear motors to individually control the movement of the clamps, increasing the complexity and cost of the equipment. Since the clamps on both sides need to move completely synchronously, any mechanical or control error in the linear motors will cause asynchronous movement of the clamps, thus affecting the uniformity of the plastic film stretching. Asynchronous movement of the clamps can lead to defects such as wrinkles and uneven thickness in the plastic film during stretching, reducing product quality. The linear motor motion control method limits the production efficiency and stability of the stretching equipment, affecting the continuous operation of the production line and the improvement of capacity.
[0005] Therefore, it is necessary to provide a biaxial stretching apparatus for thin films to solve the problems mentioned in the background art. Summary of the Invention
[0006] To achieve the above objectives, the present invention provides the following technical solution: a biaxial stretching device for films, comprising a support, wherein multiple crossbars are distributed on the support, the middle part of the crossbars is fixed to a central guide rail, multiple central sliders are slidably connected in the central guide rail, and side guide rails are symmetrically provided on both sides of the central guide rail, wherein multiple side sliders are slidably connected in the side guide rails.
[0007] Each of the side sliders is equipped with clamps;
[0008] Each of the central sliders is fixed with connecting rods on both sides, and each of the connecting rods on both sides of the central slider is connected to the side sliders on both sides.
[0009] Each of the central sliders is equipped with a slider servo motor.
[0010] Furthermore, as a preferred embodiment, the rear end of the support is provided with a winding device.
[0011] Furthermore, as a preferred embodiment, a preheating box is provided above the front end of the bracket, and the preheating box contains a downward-facing heating tube and an infrared thermometer.
[0012] Furthermore, as a preferred embodiment, the side guide rail includes a preheating section, a stretching section, and a toughening section, wherein the preheating section is hinged to the stretching section, and the stretching section is hinged to the toughening section.
[0013] The preheating section and the toughening section are each connected to at least two horizontal bars below them.
[0014] Furthermore, as a preferred embodiment, the stretching section is a telescopic guide rail.
[0015] Furthermore, preferably, the crossbar has a groove, and the back of the side guide rail is slidably connected to the crossbar.
[0016] Furthermore, as a preferred embodiment, both the center guide rail and the side guide rail are double-layered guide rails, and the two ends of the upper and lower layers are connected together by U-shaped guide rails.
[0017] Furthermore, as a preferred embodiment, a connecting plate is fixed in the center guide rail corresponding to the middle position of the preheating section and the toughening section, a gear is rotatably provided on the connecting plate, and a rack with opposite directions is slidably provided in front and behind the connecting plate, the rack meshes with the gear, the end of the rack away from the gear is fixed in the connecting column, and the connecting columns on both sides are fixed to the corresponding preheating section or toughening section respectively.
[0018] A shifting servo motor is fixed to the back of the central guide rail on the gear, and the output shaft of the shifting servo motor is connected to the gear.
[0019] Furthermore, as a preferred embodiment, the side slider is rotatably provided with a rotating base, the clamp is fixed to the rotating base, and the connecting rod slidably passes through the rotating base.
[0020] Furthermore, as a preferred embodiment, a guide rack is fixed on one side of the central guide rail corresponding to the bottom surface of the central slider, and a slider gear is rotatably provided on the bottom of each central slider. The slider gear meshes with the guide rack, and the output shaft of the slider servo motor is connected to the slider gear.
[0021] Compared with the prior art, the beneficial effects of the present invention are:
[0022] In this invention, bidirectional stretching of the film is achieved by precisely controlling the moving speed and position of the central slider and the side sliders. Compared with unidirectional stretching, this stretching method can better ensure that the film is subjected to uniform force in both longitudinal and transverse directions, effectively avoiding problems such as film deformation or damage caused by uneven stretching, thereby improving the stretching quality of the film.
[0023] In this invention, since the longitudinal movement speed of the central slider and the side sliders connected to it by the connecting rods on both sides is the same, it can ensure that the lateral tension applied to the film by the clamps on both sides is completely symmetrical, ensuring that the film is subjected to uniform lateral stretching force, and avoiding the phenomenon of wrinkles and uneven thickness of the film caused by lateral tension misalignment due to precision error.
[0024] This invention also features adjustable side guide rail spacing. By operating the shift servo motor, the spacing between the preheating or toughening sections can be easily changed, thus adapting to the stretching requirements of films of different widths. This design not only improves the flexibility of the equipment but also reduces production costs, allowing the same equipment to process films of different specifications. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of a biaxial stretching device for thin films;
[0026] Figure 2 A schematic diagram of the projection surface structure of the center guide rail and the side guide rails;
[0027] Figure 3 A schematic diagram of the side structure at the end of the center guide rail or side guide rail;
[0028] Figure 4 A schematic diagram of the structure of a gear and rack;
[0029] Figure 5 This is a schematic diagram of the cross-sectional structure of the center guide rail and the side guide rails;
[0030] Figure 6 A schematic diagram of the cross-sectional structure of the central guide rail;
[0031] In the diagram: 1. Support; 2. Crossbar; 3. Center guide rail; 31. Guide rail rack; 4. Center slider; 41. Connecting rod; 42. Slider servo motor; 43. Slider gear; 5. Side guide rail; 51. Preheating section; 52. Stretching section; 53. Toughening section; 6. Side slider; 61. Rotary seat; 7. Clamp; 8. Preheating box; 9. Winding device; 10. Connecting disc; 11. Gear; 12. Rack; 13. Shift servo motor; 14. Connecting column. Detailed Implementation
[0032] Please see Figure 1In this embodiment of the invention, a biaxial stretching device for a film includes a support 1, on which multiple crossbars 2 are distributed. The middle part of the crossbars 2 is fixed to a central guide rail 3. Multiple central sliders 4 are slidably connected in the central guide rail 3. Side guide rails 5 are symmetrically provided on both sides of the central guide rail 3. Multiple side sliders 6 are slidably connected in the side guide rails 5.
[0033] Each of the side sliders 6 is provided with clamps 7;
[0034] Each of the central sliders 4 has a connecting rod 41 fixed on both sides, and each of the connecting rods 41 on both sides of the central slider 4 is connected to the side sliders 6 on both sides.
[0035] Each of the central sliders 4 is equipped with a slider servo motor 42.
[0036] In other words, the central slider 4 can be driven by the slider servo motor 42 to move actively along the central guide rail 3, and the side sliders 6 on both sides can be driven to move synchronously along their respective side guide rails 5 through the connecting rod 41;
[0037] When the clamps 7 on both sides symmetrically clamp the film, a longitudinal tension can be applied to the film by increasing the longitudinal movement speed of the central slider 4, and a lateral tension can be applied to the film by increasing the lateral distance between the two side guide rails 5.
[0038] Since the central slider 4 and the side sliders 6 connected to it by the connecting rod 41 move at the same longitudinal speed, it can ensure that the lateral tension applied to the film by the clamps 7 on both sides is completely symmetrical, ensuring that the film is subjected to uniform lateral stretching force, and avoiding the phenomenon of wrinkles and uneven thickness of the film caused by lateral tension misalignment due to precision error.
[0039] In this embodiment, a winding device 9 is provided at the rear end of the support 1. The stretched film can be wound up by the winding device 9.
[0040] In this embodiment, a preheating box 8 is provided above the front end of the support 1. The preheating box 8 contains a downward-facing heating tube and an infrared thermometer. The infrared thermometer can monitor the temperature of the input film, and the heating tube can heat the film to a predetermined temperature to facilitate stretching.
[0041] Please see Figure 2 In this embodiment, the side guide rail 5 includes a preheating section 51, a stretching section 52, and a toughening section 53, and the preheating section 51 is hinged to the stretching section 52, and the stretching section 52 is hinged to the toughening section 53.
[0042] At least two crossbars 2 are connected below the preheating section 51 and the toughening section 53, respectively.
[0043] In this embodiment, the stretching section 52 is a telescopic guide rail.
[0044] In this embodiment, the crossbar 2 has a sliding groove, and the back of the side guide rail 5 is slidably connected to the crossbar 2.
[0045] In other words, the preheating section 51 and toughening section 53 of the two side guide rails 5 can move laterally in the crossbar 2 and remain parallel, thereby changing the width of the preheating section 51 or the toughening section 53, and thus adjusting the width of the film input and output. Since the stretching section 52 is not connected to the crossbar 2 and is a telescopic guide rail, the stretching section 52 can tilt and transition between the preheating section 51 and the toughening section 53.
[0046] Please see Figure 3 In this embodiment, both the central guide rail 3 and the side guide rail 5 are double-layered guide rails, and the two ends of the upper and lower layers are connected together by U-shaped guide rails. The rear-end central slider 4 and side slider 6 can return to the front end through the corresponding lower guide rail, and the connecting rod 41 remains connected to the corresponding central slider 4 and side slider 6.
[0047] Please see Figure 4 In this embodiment, a connecting disk 10 is fixed in the center guide rail 3 corresponding to the middle position of the preheating section 51 and the toughening section 53, respectively. A gear 11 is rotatably provided on the connecting disk 10, and racks 12 in opposite directions are slidably provided in front and behind the connecting disk 10. The racks 12 mesh with the gears 11, and the end of the rack 12 away from the gears 11 is fixed in the connecting post 14. The connecting posts 14 on both sides are fixed to the corresponding preheating section 51 or toughening section 53, respectively.
[0048] A shift servo motor 13 is fixed to the back of the central guide rail 3 on the gear 11, and the output shaft of the shift servo motor 13 is connected to the gear 11.
[0049] The connecting plate 10 is located between the upper and lower double-layer central guide rails 3, and the connecting column 14 is fixed between the upper and lower double-layer side guide rails 5. That is to say, by driving the gear 11 to rotate through the shift servo motor 13, the two racks 12 can pull the preheating section 51 or toughening section 53 on both sides to change the distance, and the distance from the preheating section 51 or toughening section 53 on both sides to the central guide rail 3 is always the same, ensuring that the film is in the center position and is subjected to uniform force.
[0050] Please see Figure 5 In this embodiment, the side slider 6 is rotatably provided with a rotating base 61, the clamp 7 is fixed to the rotating base 61, and the connecting rod 41 slidably passes through the rotating base 61. When the side slider 6 slides to the stretching section 52, the angle of the side slider 6 tilts, and under the action of the connecting rod 41, the rotating base 61 is driven to rotate, so that the clamp 7 always remains facing the center guide rail 3.
[0051] Please see Figure 6 In this embodiment, a guide rail rack 31 is fixed to one side of the central guide rail 3 corresponding to the bottom surface of the central slider 4. Each central slider 4 has a slider gear 43 rotatably mounted on its bottom. The slider gear 43 meshes with the guide rail rack 31, and the output shaft of the slider servo motor 42 is connected to the slider gear 43. The slider servo motor 42 can drive the central slider 4 to slide within the central guide rail 3, and the rack and pinion connection ensures high movement accuracy of the central slider 4.
[0052] The specific implementation includes the following steps:
[0053] Based on the characteristics of the film to be stretched, use the control panel to set the temperature parameters of the preheating chamber and adjust the temperature of the preheating section to ensure that the film can reach a suitable temperature.
[0054] According to the stretching requirements of the film, the gear can be rotated by operating the shift servo motor, so that the spacing between the preheating section or toughening section on both sides can be changed, thereby adjusting the input and output width of the film and making the width of the preheating section adapt to the width of the film extruded in the extruder.
[0055] Start the slider servo motor to drive the central slider to move on the central guide rail. At the same time, the side sliders on both sides move synchronously on the side guide rails via the connecting rod;
[0056] Once the film is symmetrically clamped by the clamps on both sides, a longitudinal tension is applied to the film by increasing the longitudinal movement speed of the central slider.
[0057] When the film passes through the stretching section, the gap between the clamps on both sides increases, applying a lateral tensile force to the film.
[0058] During this process, since the longitudinal movement speed of the central slider and the side sliders connected to it by the connecting rods on both sides is the same, it can be ensured that the transverse tensile force on the film is completely symmetrical.
[0059] After the film cools in the toughening section, the clamps release the film, and it is smoothly wound up by the winding device. During the winding process, the winding speed and tension are adjusted as needed to ensure the flatness and quality of the film.
[0060] The center slider and side slider at the rear end return to the front end via the corresponding lower guide rails of the center and side guide rails.
[0061] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A biaxial stretching apparatus for films, comprising a support (1), characterized in that, The bracket (1) has multiple horizontal bars (2) distributed on it. The middle part of the horizontal bar (2) is fixed to the central guide rail (3). Multiple central sliders (4) are slidably connected in the central guide rail (3). Side guide rails (5) are symmetrically provided on both sides of the central guide rail (3). Multiple side sliders (6) are slidably connected in the side guide rails (5). Each of the side sliders (6) is provided with a clamp (7); Each of the central sliders (4) has a connecting rod (41) fixed on both sides, and the connecting rod (41) on both sides of each central slider (4) is connected to the side sliders (6) on both sides. Each of the central sliders (4) is equipped with a slider servo motor (42).
2. The biaxial stretching apparatus for thin films according to claim 1, characterized in that, The support (1) is equipped with a winding device (9) at its rear end.
3. The biaxial stretching apparatus for thin films according to claim 1, characterized in that, A preheating box (8) is provided above the front end of the bracket (1), and a downward-facing heating tube and an infrared thermometer are provided inside the preheating box (8).
4. The biaxial stretching apparatus for thin films according to claim 1, characterized in that, The side guide rail (5) includes a preheating section (51), a stretching section (52), and a toughening section (53), wherein the preheating section (51) is hinged to the stretching section (52), and the stretching section (52) is hinged to the toughening section (53). The preheating section (51) and the toughening section (53) are respectively connected by at least two crossbars (2).
5. A biaxial stretching apparatus for thin films according to claim 4, characterized in that, The stretching section (52) is a telescopic guide rail.
6. The biaxial stretching apparatus for thin films according to claim 1, characterized in that, The crossbar (2) has a sliding groove, and the side guide rail (5) is slidably connected to the crossbar (2) on the back.
7. The biaxial stretching apparatus for thin films according to claim 1, characterized in that, The center guide rail (3) and the side guide rail (5) are both double-layered guide rails, and the two ends of the upper and lower layers are connected together by U-shaped guide rails.
8. A biaxial stretching apparatus for thin films according to claim 4, characterized in that, A connecting plate (10) is fixed in the center guide rail (3) corresponding to the middle position of the preheating section (51) and the toughening section (53). A gear (11) is rotatably provided on the connecting plate (10). Reverse racks (12) are slidably provided in front and behind the connecting plate (10). The racks (12) mesh with the gears (11). The end of the rack (12) away from the gears (11) is fixed in the connecting column (14). The connecting columns (14) on both sides are fixed to the corresponding preheating section (51) or toughening section (53). A shift servo motor (13) is fixed to the back of the center guide rail (3) on the gear (11), and the output shaft of the shift servo motor (13) is connected to the gear (11).
9. A biaxial stretching apparatus for thin films according to claim 1, characterized in that, The side slider (6) is rotatably provided with a rotating base (61), the clamp (7) is fixed to the rotating base (61), and the connecting rod (41) slidably passes through the rotating base (61).
10. A biaxial stretching apparatus for thin films according to claim 1, characterized in that, The central guide rail (3) is fixed with a guide rail rack (31) on one side of the bottom side of the central slider (4). Each central slider (4) is rotatably provided with a slider gear (43) at its bottom. The slider gear (43) meshes with the guide rail rack (31). The output shaft of the slider servo motor (42) is connected to the slider gear (43).