Stretching device for PET film production
By preheating and softening the PET film through a heating and stretching mechanism, the problem of film springback in traditional stretching methods is solved, achieving dimensional stability and high-quality production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-21
- Publication Date
- 2026-04-17
AI Technical Summary
In current PET film production, traditional stretching methods result in uneven stress distribution within the film, making it prone to springback and failing to meet high precision and stability requirements, thus affecting product quality.
A heating and stretching mechanism is used to preheat and soften the film through upper and lower heating plates, and then the mechanical stretching force of the winding mechanism is used to stretch it in a specific direction, thus realizing a composite process of heating first and then mechanical stretching.
It significantly reduces film springback, ensures dimensional stability and product quality after stretching, and improves film strength and flatness.
Smart Images
Figure CN224130454U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of film manufacturing technology, specifically relating to a stretching device for PET film production. Background Technology
[0002] PET (polyethylene terephthalate) film has wide applications in packaging, electronics, and optics due to its excellent physicochemical properties. In the production of PET film, the stretching process is one of the key steps. Its purpose is to orient the polymer molecular chains through mechanical force, thereby improving the film's strength, smoothness, and optical properties.
[0003] In existing technologies, PET film stretching is typically achieved using stretching roller sets. The basic principle is to apply stretching force to the film using the speed difference between multiple roller sets. However, this traditional stretching method has significant drawbacks: because the film is only subjected to mechanical force during stretching without heat treatment, uneven stress distribution occurs within the film. After stretching, the film is prone to springback shrinkage due to stress release, severely affecting dimensional stability and product quality. Furthermore, traditional stretching devices have limited stretching effectiveness, failing to meet the requirements of high-precision film products for stretching uniformity and stability, thus limiting the production efficiency and application range of high-performance PET films. Therefore, providing a device that reduces film springback and improves stretching effectiveness has become a pressing technical problem to be solved in this field. Utility Model Content
[0004] The purpose of this invention is to provide a stretching device for PET film production to solve the problems existing in the background art.
[0005] To achieve the above objectives, this utility model provides the following technical solution:
[0006] A stretching device for PET film production includes a frame, an unwinding mechanism, a winding mechanism, and a heating and stretching mechanism. The unwinding mechanism is installed on one side of the frame, the winding mechanism is installed on the other side of the frame, and the heating and stretching mechanism is located between the unwinding mechanism and the winding mechanism. The PET film is drawn out from the unwinding mechanism, heated and stretched by the heating and stretching mechanism, and then recycled by the winding mechanism.
[0007] Preferably, the unwinding mechanism includes an unwinding wheel and two unwinding rollers; the two ends of the unwinding wheel and the unwinding rollers are mounted on the frame by bearings, and the two unwinding rollers are located below the unwinding wheel, so that the PET film enters the heating and stretching mechanism in an S-shaped path, and the unwinding wheel is detachable and replaceable.
[0008] Preferably, the winding mechanism includes a winding wheel, two winding rollers, and a winding motor; the winding motor is connected to the drive shaft of the winding wheel via a belt, and the winding motor drives the winding wheel to rotate, thereby stretching the PET film through the rotation of the winding wheel, so that the PET film is stretched in the heating and stretching mechanism.
[0009] Preferably, the heating and stretching mechanism includes a gantry frame, a movable plate, a drive cylinder, an upper heating plate, and a lower heating plate; the gantry frame is fixed inside the frame, the drive cylinder is fixed to the top of the gantry frame, and its piston rod passes through the gantry frame and is connected to the movable plate; the upper heating plate is fixed to the bottom of the movable plate, the lower heating plate is fixed to the bottom of the gantry frame, and a groove is formed between the upper heating plate and the lower heating plate for the PET film to pass through. After being heated, the PET film is stretched and deformed by the winding mechanism.
[0010] The beneficial effects of this invention are as follows: This device significantly improves the stretching effect of PET film through the synergistic action of the heating and stretching mechanism and the winding mechanism. The upper and lower heating plates preheat the film, causing it to deform slightly under heat, reducing the internal stress of the molecular chains. Then, the mechanical stretching force of the winding mechanism achieves directional stretching. This composite process of "heating and softening first, then mechanical stretching" avoids the film springback problem caused by traditional simple mechanical stretching, ensuring the dimensional stability of the stretched film and preventing shrinkage deformation, thus effectively improving product quality. Attached Figure Description
[0011] Figure 1 This is the front view of this utility model;
[0012] Figure 2 This is a side view of the present invention;
[0013] Figure 3 yes Figure 1 Sectional view at point AA;
[0014] Figure 4 This is a top view of the present invention. Detailed Implementation
[0015] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings and preferred embodiments.
[0016] like Figure 1-4 As shown, a stretching device for PET film production mainly consists of a frame 4, an unwinding mechanism 1, a heating and stretching mechanism 3, and a winding mechanism 2. These mechanisms are integrated and mounted via the frame 4 (see...). Figure 1-4 ).
[0017] The frame 4 serves as the main support and is made of metal (such as aluminum alloy or steel). It has reserved installation space inside to fix the unwinding mechanism 1, the heating and stretching mechanism 3 and the winding mechanism 2, so as to ensure the relative position stability of each component.
[0018] The unwinding mechanism 1 is installed on one side of the frame 4 and is used to hold unstretched PET film rolls. Specifically, it includes an unwinding roller 11, with both ends fixed to the frame 4 via bearings, for mounting the PET film rolls and capable of being disassembled and replaced according to different roll specifications. Two unwinding rollers 12 are arranged parallel to each other below the unwinding roller 11, forming an S-shaped transport path. After the PET film is drawn from the unwinding roller 11, it first passes over the upper unwinding roller 12 and then through the lower unwinding roller 12 to increase the contact length between the film and the subsequent heating and stretching mechanism 3, ensuring heating uniformity (see...). Figure 1 , Figure 3 ).
[0019] The winding mechanism 2 is installed on the other side of the frame 4 and is used to recycle the stretched PET film. Specifically, it includes: a winding roller 21: fixed to the frame 4 at both ends by bearings, used to wind the stretched film; two winding rollers 22: similar in structure to the unwinding roller 12, forming an S-shaped transport path to ensure the film enters the winding roller 21 smoothly; and a winding motor 23: connected to the drive shaft of the winding roller 21 via a belt, providing power to drive the winding roller 21 to rotate, thereby applying a stretching force to the film (see...). Figure 1 , Figure 2 ).
[0020] The heating and stretching mechanism 3 is located between the unwinding mechanism 1 and the winding mechanism 2, and is the core component of this device. Its structure and working process are as follows (see...). Figure 1 , Figure 3 , Figure 4 ):
[0021] The gantry frame 31 is fixed in the middle of the frame 4 as a support structure for the heating and stretching mechanism 3. The top is equipped with a drive cylinder 33 and the bottom is fixed with a lower heating plate 35.
[0022] The piston rod of the drive cylinder 33 passes vertically downward through the gantry 31 and is connected to the moving plate 32. The extension and retraction of the cylinder drives the moving plate 32 to move up and down, thereby adjusting the distance between the upper heating plate 34 and the lower heating plate 35 to accommodate PET films of different thicknesses.
[0023] The lower heating plate 35 is fixed to the bottom of the gantry frame 31, and its surface has an upward-protruding groove (or flat surface) for supporting the film.
[0024] The upper heating plate 34 is fixed to the bottom of the movable plate 32 and is correspondingly arranged with the lower heating plate 35, forming a channel for the PET film to pass through. Both the upper heating plate 34 and the lower heating plate 35 have integrated heating elements (such as resistance wires or heating tubes) inside, and the temperature can be adjusted by a temperature control system (usually heated to near the glass transition temperature of the PET film, so that the film is slightly softened but not melted).
[0025] Workflow:
[0026] Heating stage: After the PET film is drawn out from the S-shaped path of the unwinding mechanism 1, it enters the channel between the upper heating plate 34 and the lower heating plate 35. The heating plates uniformly heat the film, activating its molecular chain segments, reducing internal stress, and causing slight plastic deformation.
[0027] Stretching Stage: The winding motor 23 drives the winding wheel 21 to rotate, applying a continuous tensile force to the film through the winding roller 22. The heated and softened film undergoes directional stretching under mechanical force, with the molecular chains aligning along the stretching direction, thereby improving the film's strength and smoothness. Because the heating process reduces internal stress, the stretched film does not shrink significantly after cooling, ensuring dimensional stability.
[0028] It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.
Claims
1. A stretching device for PET film production, characterized by, It includes a frame (4), an unwinding mechanism (1), a winding mechanism (2), and a heating and stretching mechanism (3); the unwinding mechanism (1) is installed on one side of the frame (4), the winding mechanism (2) is installed on the other side of the frame (4), and the heating and stretching mechanism (3) is located between the unwinding mechanism (1) and the winding mechanism (2); the PET film is drawn out from the unwinding mechanism (1), heated and stretched by the heating and stretching mechanism (3), and then recycled by the winding mechanism (2).
2. The stretching device for PET film production according to claim 1, characterized in that, The unwinding mechanism (1) includes an unwinding wheel (11) and two unwinding rollers (12); the two ends of the unwinding wheel (11) and the unwinding rollers (12) are mounted on the frame (4) by bearings, and the two unwinding rollers (12) are located below the unwinding wheel (11), so that the PET film enters the heating and stretching mechanism (3) in an S-shaped path, and the unwinding wheel (11) is detachable and replaceable.
3. The stretching device for PET film production according to claim 1, wherein The winding mechanism (2) includes a winding wheel (21), two winding rollers (22) and a winding motor (23); the winding motor (23) is connected to the drive shaft of the winding wheel (21) via a belt, and the winding motor (23) drives the winding wheel (21) to rotate, thereby stretching the PET film through the rotation of the winding wheel (21), so that the PET film is stretched in the heating and stretching mechanism (3).
4. The stretching device for PET film production according to claim 1, wherein The heating and stretching mechanism (3) includes a gantry frame (31), a moving plate (32), a driving cylinder (33), an upper heating plate (34), and a lower heating plate (35). The gantry frame (31) is fixed inside the frame (4), and the driving cylinder (33) is fixed to the top of the gantry frame (31). Its piston rod passes through the gantry frame (31) and is connected to the moving plate (32). The upper heating plate (34) is fixed at the bottom of the moving plate (32), and the lower heating plate (35) is fixed at the bottom of the gantry frame (31). A groove is formed between the upper heating plate (34) and the lower heating plate (35) for the PET film to pass through. After being heated, the PET film is stretched and deformed by the winding mechanism (2).