Flat film thickness online automatic adjusting die head and adjusting method thereof
By independently controlling the local temperature through heating tubes to regulate melt flow, the problem of insufficient precision in mechanical die lip adjustment is solved, achieving high-precision thickness adjustment and improving equipment reliability, making it suitable for high-end flat film products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-27
- Publication Date
- 2026-03-31
AI Technical Summary
In the existing technology, the adjustment accuracy of mechanical die lip adjustment mechanism is limited, making it difficult to achieve slight thickness correction. Furthermore, frequent mechanical displacement leads to a reduction in equipment lifespan and cannot meet the requirements of high-end flat film products for thickness uniformity.
The heating tube is used to independently control the local temperature. The thickness of the flat film is adjusted by changing the viscosity and fluidity of the melt. The thermal expansion and rheological properties of the heating tube are used to achieve continuous, stepless, and minute thickness adjustment. The temperature control thermocouple is combined with real-time monitoring and adjustment of the heating tube temperature.
It achieves high-precision thickness adjustment, improves product thickness consistency and equipment reliability, reduces mechanical stress and wear risks, adapts to changes in production conditions, and enhances the appearance flatness and mechanical properties of high-end flat film products.
Smart Images
Figure CN121756495A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of plastic film preparation technology, specifically to an online automatic adjustment die head for flat film thickness and its adjustment method. Background Technology
[0002] Flat film (cast film) products are widely used. In certain special cases, the uniformity of film thickness is particularly important, as it directly affects the tensile strength and other related indicators of the product. For example, when drawing film into bulk bags, the uniformity of film thickness affects both the surface smoothness of the bulk bag and its packing strength. To improve film thickness uniformity, Chinese Patent Publication No. CN13568178A discloses a flat film die head with an automatic die lip adjustment device and a method for adjusting the die lip. This device uses a fine-tuning screw to adjust the die lip opening. In this automatic die lip adjustment device, the rotation angle of the fine-tuning screw is limited by the shape of the screw head. If it is a hexagonal screw, then the fine-tuning screw rotates in multiples of 60° each time; otherwise, the rotation mechanism cannot properly fix the fine-tuning screw. Therefore, the adjustment amount of the die lip opening each time is a multiple of one-sixth of the screw pitch. For applications requiring high film thickness uniformity, this adjustment mechanism cannot adequately meet the requirements. Summary of the Invention
[0003] To address the technical problems in the background art, this invention discloses an online automatic adjustment die head for flat film thickness and its adjustment method.
[0004] This invention provides an online automatic adjustment die head for flat film thickness, including a front die body and a rear die body, which are fixedly connected by a clamping screw; a flow channel for melt is formed between the front die body and the rear die body; a front lip and a rear lip are respectively provided at the lower ends of the front die body and the rear die body, and a lip slit is formed between the front lip and the rear lip that communicates with the flow channel and whose spacing is consistent with the set thickness of the flat film; a plurality of heating tubes are evenly spaced and inserted into the front die body and / or the rear die body along the width direction of the flat film. By adjusting the temperature of the heating tube in the corresponding area, the fluidity of the melt in that area is changed, thereby adjusting the thickness of the flat film flowing out from the corresponding area of the lip seam.
[0005] Furthermore, the heating element is configured to: when the thickness of the flat film flowing out of the corresponding area of the lip seam is detected to be greater than the target thickness, reduce the set temperature of the heating element corresponding to that area; when the thickness is detected to be less than the target thickness, increase the set temperature of the heating element corresponding to that area.
[0006] Furthermore, the heating tubes are arranged in two rows symmetrically relative to the lip seam, and are simultaneously installed in the front mold body and the rear mold body; The arrangement of each row of heating tubes is parallel to the lip seam.
[0007] Furthermore, the heating element is an electric heating element.
[0008] Furthermore, the heating elements are located between two adjacent clamping bolts.
[0009] Furthermore, adjusting bolts are provided on the front mold body; The adjusting bolt is threaded to the front lip to drive the front lip to deform, moving it closer to or away from the rear lip.
[0010] Furthermore, a groove is provided on the upper side of the front lip, with the upper area of the groove serving as the upper arm and the lower area serving as the lower arm; The adjusting bolt passes downward through the upper arm and is threaded into the lower arm.
[0011] Furthermore, the lower surfaces of the front and back lips are arranged at an angle and form a V-shape; The groove is perpendicular to the lower slope of the front lip; The adjusting bolt is parallel to the lower slope of the front lip.
[0012] This invention also provides a method for adjusting a flat film thickness online automatic adjustment die head, comprising the following steps: S1. Tighten the adjusting bolt to make the lip seam spacing consistent with the set thickness of the flat film; S2. Inject the melt into the flow channel and simultaneously start the heating device to heat the heating tube, thereby heating the melt in the flow channel; S3, The melt flows downward from the lip seam; S4. Real-time monitoring of the thickness distribution of the flat film flowing out from the lip slit in the width direction; S5. Compare the detected thickness value with the set thickness value; When the thickness gauge detects that the thickness of the flat film in a certain area is greater than the set value, the temperature of the heating tube corresponding to this area decreases. When the thickness gauge detects that the thickness of the flat film in a certain area is less than the set value, the temperature of the heating tube corresponding to this area will rise.
[0013] The beneficial effects of this invention are: 1. Mechanical die lip adjustment mechanisms (such as fine-tuning screws) are limited by their mechanical structure (e.g., the rotation angle is fixed at multiples of 60°), and their adjustment range is a fixed fraction of the screw pitch. This results in an inherent lower limit to adjustment accuracy, making it difficult to achieve minute thickness corrections. This invention abandons mechanical displacement adjustment methods. By independently controlling the local heating temperature, it changes the viscosity and flowability of the melt in the corresponding area, thereby fine-tuning the die lip discharge to adjust the flat film thickness. This adjustment method, based on thermal expansion and rheological properties, enables continuous, stepless, and minute thickness adjustment. Its adjustment accuracy is far superior to mechanical methods, effectively addressing production scenarios with extremely high requirements for film thickness uniformity and significantly improving product thickness consistency.
[0014] 2. In mechanical adjustment devices, the die lip often requires frequent mechanical displacement to adjust its thickness. Long-term, repeated stress and micro-movements can easily lead to fatigue of the front lip component, and even deformation or breakage, affecting equipment lifespan and production continuity. In this invention, the front lip itself does not require mechanical displacement adjustment; thickness adjustment is achieved entirely through heat control via the heating element. The front lip maintains a fixed position, ensuring structural stability and fundamentally avoiding mechanical stress and wear caused by frequent adjustments. This significantly reduces the risk of front lip breakage and deformation, improves equipment reliability and service life, and reduces maintenance requirements.
[0015] 3. The temperature control system has a fast response time and can dynamically adjust in real time to detect thickness deviations, adapting to changes in production conditions. It is especially suitable for high-end flat film products that are extremely sensitive to thickness uniformity, improving the product's appearance flatness and mechanical property consistency. Attached Figure Description
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0017] Figure 1 This is the front view of the present invention; Figure 2 This is a top view of the present invention; Figure 3 This is a right-hand view of the present invention, in which a partial cross-section is shown; In the diagram: 1. Front mold body; 2. Rear mold body; 3. Runner; 4. Lip seam; 5. Heating tube; 6. Adjusting bolt; 7. Temperature control thermocouple; 8. Clamping bolt; 11. Front lip; 12. Groove; 13. Upper arm; 14. Lower arm; 21. Rear lip. Detailed Implementation
[0018] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.
[0019] Example 1: like Figure 1-3 As shown, this invention discloses an online automatic adjustment die head for flat film thickness, comprising a front die body 1 and a rear die body 2, which are locked together by clamping bolts 8. A melt flow channel 3 is provided between the front die body 1 and the rear die body 2, and the flow channel 3 is wedge-shaped, wider at the top and narrower at the bottom. A front lip 11 and a rear lip 21 are respectively provided at the lower ends of the front die body 1 and the rear die body 2. The front lip 11 and the rear lip 21 form a lip slit 4 that communicates with the flow channel 3 and whose spacing is consistent with the set thickness of the flat film. The melt in the flow channel 3 flows downward through the lip slit 4, forming a flat film of uniform thickness.
[0020] Within the front mold body 1 and / or the rear mold body 2, several heating tubes 5 are evenly spaced along the width of the flat film to heat the melt within the flow channel 3. The heating tubes 5 are located in the gap area between two adjacent clamping bolts 8. This arrangement avoids spatial interference between the heating tubes 5 and the clamping bolts 8, allowing each heating tube 5 to independently and precisely correspond to its local mold area. This layout ensures independent temperature control; when a deviation in film thickness occurs in a certain area, the temperature of the corresponding heating tube 5 can be adjusted individually without interference from adjacent bolt structures or heat conduction, thus achieving more precise compensation control of the film thickness.
[0021] To improve the temperature stability of the melt within the flow channel 3, the following design is implemented: Heating tubes 5 are arranged in two symmetrical rows relative to the lip 4, and are simultaneously located within the front mold body 1 and the rear mold body 2. The arrangement direction of each row of heating tubes 5 is parallel to the lip 4. This symmetrical structure allows the temperature field of the melt to be controlled synchronously and evenly as it flows through both sides of the lip 4, thereby enabling more precise adjustment of the local flowability of the melt. Compared to heating only on one side, bidirectional symmetrical heating can adjust thickness deviations more quickly and uniformly, avoiding response lag or uneven temperature gradients caused by unilateral temperature control.
[0022] In this embodiment, the heating tubes 5 are parallel electric heating elements: each electric heating tube is electrically connected to a controller that controls its on / off state; in this embodiment, the controller is a series automatic switch, which automatically turns on and off and automatically controls the off time, so that the temperature of each heating tube 5 can be independently adjusted and controlled. In other embodiments, the controller can also be a relay or contactor. This configuration has the following advantages: 1. The electric heating tubes directly convert electrical energy into heat energy, which can achieve rapid and precise temperature regulation. When a film thickness deviation is detected in a certain area, the system can immediately adjust the power of the corresponding electric heating tube, quickly change the local melt flow, thereby achieving real-time adjustment of the thickness deviation and improving the adjustment efficiency. 2. The electric heating tubes are small in size and have a regular shape (usually cylindrical), which is convenient for uniform and dense arrangement along the width direction of the flat film, and is easy to embed inside the front mold body 1 and the rear mold body 2. This design does not occupy extra space, maintains the compactness of the overall structure of the mold head, and meets the needs of independent temperature control in multiple areas. 3. Each electric heating tube can be connected to an independent temperature control circuit to realize the individual setting and adjustment of the temperature of each heating area. This zoned independent temperature control method allows for differentiated temperature adjustment based on thickness deviations at different transverse positions of the film, significantly improving the precision of thickness uniformity adjustment. 4. The electric heating element is directly inserted into the mold body, allowing heat to be rapidly conducted through the metal mold body to the melt within the flow channel 3, reducing thermal hysteresis. This facilitates more sensitive melt viscosity adjustment, thereby enabling more accurate control of the melt flow rate and thickness at the lip slit 4 exit.
[0023] By adjusting the temperature of the heating tube 5 in the corresponding area, the flowability of the melt flowing through that area is changed, thereby adjusting the thickness of the flat film flowing out from the corresponding area of the lip slit 4. Specifically, the thickness of the flat film is measured online using a thickness gauge, and each heating tube 5 is equipped with a temperature-controlled thermocouple 7. The temperature-controlled thermocouple 7 not only measures the temperature of the heating tube 5 but also maintains the heating tube 5 within a set temperature range, ensuring that the flat film with the required thickness can be produced normally. The temperature set by the temperature-controlled thermocouple 7 is also consistent with that of the heating tube 5. The temperature-controlled thermocouple 7 is also simultaneously connected to the thickness gauge signal. When the thickness of the flat film flowing out of the area corresponding to the lip seam 4 is detected to be greater than the target thickness, the temperature control thermocouple 7 automatically lowers the temperature value and controls the automatic switch, extending the automatic switch off time and shortening the automatic switch closing time to reduce the set temperature of the heating tube 5 corresponding to that area, increase the viscosity of the melt in that area, reduce the fluidity of the melt in that area, and thus reduce the thickness of the flat film flowing out of that area; when the thickness is detected to be less than the target thickness, the temperature control thermocouple 7 automatically raises its temperature value and controls the automatic switch, shortening the automatic switch off time and extending the automatic switch closing time to raise the set temperature of the heating tube 5 corresponding to that area, reduce the viscosity of the melt in that area, increase the fluidity of the melt in that area, and thus increase the thickness of the flat film flowing out of that area.
[0024] In this embodiment, the lower end faces of the front lip 11 and the rear lip 21 are arranged at an incline, forming a symmetrical V-shape. A groove 12 is provided on the inclined surface of the lower side of the front lip 11. The upper area of the groove 12 is designated as the upper arm 13, and the lower area as the lower arm 14. The adjusting bolt 6 passes downward through the upper arm 13 and is threadedly connected to the lower arm 14 to drive the front lip 11 to deform, moving closer to or away from the rear lip 21. The groove 12 is perpendicular to the lower inclined surface of the front lip 11, and the adjusting bolt 6 is parallel to the lower inclined surface of the front lip 11. The lower end faces of the front lip 11 and the rear lip 21 are arranged at an incline, forming a V-shape. The opening direction of the groove 12 is perpendicular to the lower inclined surface of the front lip 11, while the installation direction of the adjusting bolt 6 is parallel to this inclined surface. This geometric relationship allows the axial force of the adjusting bolt 6 to be directly and efficiently converted into the displacement of the lower arm 14 in the vertical direction, ensuring that the adjusting force is accurately transmitted along the closing and opening directions of the lip seam 4, reducing unnecessary structural deformation or stress dispersion, and improving the sensitivity and repeatability of the adjustment.
[0025] The adjusting bolt 6 in this embodiment is different from the fine-tuning screw disclosed in CN13568178A in the background art; the adjusting bolt 6 is used to adjust the spacing of the lip slit 4 before the melt enters the flow channel 3 after the front mold body 1 and the rear mold body 2 are spliced together, so as to adapt to the processing of flat films of different thicknesses.
[0026] Compared to existing technologies, the advantages of this embodiment are: 1. Mechanical die lip adjustment mechanisms (such as fine-tuning screws) are limited by mechanical structures (such as rotation angles fixed at multiples of 60°), and their adjustment amount is a fixed fraction of the pitch. The adjustment accuracy has an inherent lower limit, making it difficult to achieve minute thickness corrections. This invention abandons the mechanical displacement adjustment method. By independently controlling the local heating temperature, it changes the viscosity and fluidity of the melt in the corresponding area, thereby fine-tuning the discharge amount of the lip slit 4 to adjust the flat film thickness. This adjustment method based on thermal expansion and rheological properties can achieve continuous, stepless, and minute thickness adjustment. The adjustment accuracy is far higher than that of mechanical methods, effectively addressing production scenarios with extremely high requirements for film thickness uniformity and significantly improving product thickness consistency. 2. In mechanical adjustment devices, the die lip often needs frequent mechanical displacement to achieve thickness adjustment. Long-term repeated stress and micro-movement can easily lead to fatigue of the front lip 11 component, or even deformation or breakage, affecting equipment lifespan and production continuity. In this invention, the front lip 11 itself does not require mechanical displacement adjustment; thickness adjustment is achieved entirely through heat control of the heating tube 5. The front lip 11 remains in a fixed position, ensuring structural stability and fundamentally avoiding mechanical stress and wear caused by frequent adjustments. This significantly reduces the risk of breakage and deformation of the front lip 11, improving equipment reliability and lifespan while reducing maintenance requirements. 3. The temperature control system has a fast response time and can dynamically adjust in real time based on detected thickness deviations, adapting to changes in production conditions. It is particularly suitable for high-end flat film products that are extremely sensitive to thickness uniformity, improving product appearance flatness and mechanical property consistency.
[0027] Example 2: This invention also discloses a method for adjusting a flat film thickness online automatic adjustment die head, using a flat film thickness online automatic adjustment die head as described in Example 1, comprising the following steps: S1. Tighten the adjusting bolt 6 to make the spacing of the lip slit 4 consistent with the set thickness of the flat film; S2. Inject the melt into the flow channel 3, and at the same time turn on the power to heat the heating tube 5 to heat the melt in the flow channel 3. S3, The melt flows downward from the lip 4; S4. Real-time monitoring of the thickness distribution of the flat film flowing out from the lip slit 4 in the width direction; S5. Compare the detected thickness value with the set thickness value; When the thickness gauge detects that the thickness of the flat film in a certain area is greater than the set value, the temperature of the heating tube 5 corresponding to this area decreases. When the thickness gauge detects that the thickness of the flat film in a certain area is less than the set value, the temperature of the heating tube 5 corresponding to this area increases.
[0028] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A flat film thickness online automatic adjusting die, comprising a front die body (1) and a rear die body (2), the front die body (1) and the rear die body (2) are fixedly connected by a pressing bolt (8); the front die body (1) and the rear die body (2) have a flow channel (3) for melt therebetween; the lower ends of the front die body (1) and the rear die body (2) are respectively provided with a front lip (11) and a rear lip (21), the front lip (11) and the rear lip (21) have a lip gap (4) in communication with the flow channel (3) and having a spacing consistent with the set thickness of the flat film, characterized in that: a plurality of heating pipes (5) are uniformly and spacedly inserted into the front die body (1) and / or the rear die body (2) along the width direction of the flat film; the flat film thickness of a corresponding region is adjusted by adjusting the temperature of the heating pipe (5) in the region to change the fluidity of the melt in the region. The heating pipe (5) is configured to: when it is detected that the flat film thickness of a certain region of the lip gap (4) is greater than the target thickness, the set temperature of the corresponding heating pipe (5) in the region is lowered; when it is detected that the flat film thickness is less than the target thickness, the set temperature of the corresponding heating pipe (5) in the region is raised. The heating pipes (5) are arranged in two rows symmetrically relative to the lip gap (4) and are arranged in the front die body (1) and the rear die body (2) at the same time.
2. The flat film thickness on-line automatic adjusting die of claim 1, wherein: The arrangement direction of each row of the heating pipes (5) is parallel to the lip gap (4).
3. The flat film thickness on-line automatic adjusting die head according to claim 1 or 2, characterized in that: The heating pipes (5) are respectively located between two adjacent pressing bolts (8). The front die body (1) is provided with an adjusting bolt (6).
4. The flat film thickness on-line automatic adjusting die of claim 1, wherein: The adjusting bolt (6) is threadedly connected with the front lip (11) to drive the front lip (11) to deform, move closer to or away from the rear lip (21).
5. The flat film thickness on-line automatic adjusting die of claim 1, wherein: The upper side of the front lip (11) is provided with a groove (12), the upper side region of the groove (12) is provided as an upper arm (13), and the lower side region is provided as a lower arm (14). The adjusting bolt (6) passes downward through the upper arm (13) and is threadedly connected with the lower arm (14).
6. The flat film thickness on-line automatic adjusting die of claim 5, wherein: The lower end faces of the front lip (11) and the rear lip (21) are arranged obliquely and form a V shape. The groove (12) is perpendicular to the lower side inclined surface of the front lip (11).
7. A flat film thickness on-line automatic regulating die according to claim 6, characterized in that: The adjusting bolt (6) is parallel to the lower side inclined surface of the front lip (11). The flat film thickness online automatic adjusting die of claim 5 comprises the following steps: S1, twist the adjusting bolt (6) so that the spacing of the lip gap (4) is consistent with the set thickness of the flat film; 8. A method of adjusting a flat film thickness on-line automatic adjusting die, characterized in that, S2, inject melt into the flow channel (3) and start the heating device to heat the heating pipes (5) to heat the melt in the flow channel (3); S3, the melt flows out of the lip gap (4) downward; S4, real-time monitor the thickness distribution of the flat film flowing out of the lip gap (4) in the width direction; S5, compare the monitored thickness value with the set thickness value; When the thickness of a certain region of the flat film detected by the thickness gauge is greater than the set value, the temperature of the heating pipe (5) corresponding to the region is lowered; When the thickness of a certain region of the flat film detected by the thickness gauge is less than the set value, the temperature of the heating pipe (5) corresponding to the region is raised.