A biaxial stretching process for a high orientation flexible label base film

Abstract

The application relates to a bidirectional stretching process of a high-orientation-degree flexible label base film applied to the technical field of related stretching forming, through the setting of a real-time monitoring unit in a longitudinal stretching device, the state of a stretching roller can be monitored in real time, the centrifugal or deformation condition of the stretching roller caused by excessive wear can be found in time, so that the phenomenon of shaft jumping is not prone to occurring during stretching, the uniformity of stretching is effectively ensured, and in cooperation with a shaft supporting unit, when the wear or centrifugal condition occurs, the shaft can be supported at multiple points, the shaft center of the stretching roller is gradually coincided with the shaft center of a bearing seat, the stretching roller is temporarily restored to normal, so that the stretching roller can continue to work without shutdown, the stretching process is not prone to interruption, the stretching efficiency is ensured, and the end of the shaft supporting unit can be self-adapted to the irregular outer wall of the worn bearing, so that the stability during shaft supporting is higher, and the influence of wear on the stretching quality of the film is greatly reduced.

Description

Technical Field

[0001] This invention relates to a biaxial stretching process, and more particularly to a biaxial stretching process for a highly oriented flexible label base film applied in the field of stretching and forming technology. Background Technology

[0002] Biaxial stretching is a process in which a thick film or cast sheet is stretched longitudinally and transversely at a temperature below the melting point of the film material and above the glass transition temperature. Then, it is subjected to appropriate cooling or heat setting treatment or special processing (such as corona treatment, coating, etc.) under tension. Biaxial stretching is generally divided into two types: one is simultaneous stretching in both longitudinal and transverse directions, such as the biaxial stretching device for films disclosed in the specification with announcement number CN115302750A; the other is a two-step stretching process, where longitudinal stretching is performed first and then transverse stretching is performed, such as the biaxial stretching BOPP film preparation method disclosed in the specification with announcement number CN116353038B.

[0003] In the two-step separate stretching process, longitudinal stretching mainly relies on multiple stretching rollers to stretch the film. During long-term use, due to the combined effects of the rollers' own weight and the film tension, the bearings and bearing seats of the stretching rollers are prone to eccentric wear, and the wear points are mostly concentrated at the bottom, causing the stretching rollers to become eccentric. When stretching the film, this will cause fluctuations in film tension, resulting in periodic changes in the longitudinal thickness of the film, leading to uneven thickness and uneven tensile stress. In severe cases, even film breakage may occur.

[0004] When wear occurs, the resulting change in film thickness is very slight and difficult to detect because the wear is relatively minor. The abnormality is often only discovered during quality inspection after the batch of films has been stretched, resulting in the rework or scrapping of the entire batch of films, which seriously affects the overall film production efficiency and wastes resources. Summary of the Invention

[0005] The technical problem that this invention aims to solve in response to the above-mentioned prior art is that wear on the stretching roller is difficult to detect, resulting in the rework or scrapping of batches of film, which seriously affects the overall film production efficiency and wastes resources.

[0006] To address the above problems, this invention provides a biaxial stretching process for a highly oriented flexible label base film, comprising the following steps:

[0007] S1. First, install a real-time monitoring unit and multiple support shaft units on the bearing housing of the stretching roller in the longitudinal stretching equipment.

[0008] S2. The polymer resin is melt-extruded through an extruder to obtain a base film, and the base film is then wound up.

[0009] S31. The wound base film is unwound into the longitudinal stretching equipment by the guide roller, and the longitudinal stretching of the base film is achieved by the cooperation of multiple stretching rollers.

[0010] S32. During the longitudinal stretching process, the real-time monitoring unit monitors the status of the stretching roller in real time. When the wear between the bearing housing and the bearing is too large, the support unit supports the bearing and the stretching roller connected to it to temporarily restore the status of the stretching roller to normal. This allows the stretching roller to continue working without stopping the machine, and it is not easy to interrupt the stretching process.

[0011] S4. Then, the longitudinally stretched base film is guided into the transverse stretching equipment through the guide roller for transverse stretching. Finally, it is heat-set, cooled and wound up to complete the stretching of the base film.

[0012] In the biaxial stretching process of the above-mentioned high-orientation flexible label base film, by setting up a real-time monitoring unit in the longitudinal stretching equipment, the status of the stretching roller can be monitored in real time, and the situation of centrifugal or deformed stretching roller caused by excessive wear can be detected in time. This makes it less likely for the axial runout to occur during stretching, thereby effectively ensuring the uniformity of stretching.

[0013] As a further improvement of this application, the real-time monitoring unit includes a longitudinally symmetrical fixed measuring rod and a moving measuring rod, both of which are located on the side of the bearing housing facing the center of the stretching roller. An upper laser and a lower laser are respectively provided at the ends of the fixed measuring rod and the moving measuring rod that are close to each other, and the emitting ends of the upper laser and the lower laser are perpendicular to the central axis of the stretching roller, and the distance between the two and the surface of the stretching roller is the same.

[0014] As a further improvement of this application, the bearing housing includes a lower base and an upper base that are fixedly connected by bolts, with the upper base located above the lower base. The fixed measuring rod is fixedly connected to the upper base, and an arc-shaped slide rail is installed on the outer end of the lower base. The moving measuring rod is slidably connected to the arc-shaped slide rail, and the lower laser is connected to the moving measuring rod via an electric slide rail.

[0015] As a further improvement of this application, the midpoint of the arc-shaped slide rail is located on the vertical centerline of the lower base, and the central angle of the arc-shaped slide rail is not less than 120°.

[0016] As a further improvement of this application, the semi-circular inner wall of the lower base is chiseled with multiple grooves, and multiple support shaft units are respectively installed inside the multiple grooves. The support shaft unit includes a support shaft column that is completely matched with the inner wall of the groove, an electric push rod that is fixedly connected between the bottom of the groove and the support shaft column, and an inner laser that is fixedly installed at the end of the support shaft column away from the bearing seat axis. The detection end of the inner laser is perpendicular to the inner wall of the groove that is directly opposite the bearing seat axis.

[0017] As a further improvement of this application, the distribution density of multiple grooves gradually increases along the direction from both sides to the middle, the end face of the support column facing the bearing housing axis is arc-shaped, and the arc is consistent with the arc of the inner wall of the bearing housing. The support column is a rigid structure, and the material of the support column is consistent with that of the bearing housing.

[0018] As another improvement of this application, along the direction close to the axis of the bearing seat, the support column includes an electromagnetic base plate, a bearing column and an outer adaptation bladder that are fixedly connected to each other. The bearing column has a transverse cavity and multiple vertical holes inside. The multiple vertical holes are all located above the transverse cavity and communicate with each other. Each of the multiple vertical holes is provided with a support rod. The outer adaptation bladder is fixedly connected with multiple isolation sleeves that correspond to the multiple vertical holes respectively. The support rods move through the vertical holes and extend into the isolation sleeves, and the uprights are in contact with the inner wall of the outer adaptation bladder.

[0019] As a further improvement to this application, the support rod includes a vertical rod extending into the outer adaptation bladder and a compression spring fixedly connected between the vertical rod and the inner wall of the transverse cavity. The outer adaptation bladder is saturated with magnetorheological fluid, and the transverse cavity and multiple vertical holes are also filled with magnetorheological fluid, and the surface of the magnetorheological fluid does not contact the vertical rod.

[0020] In summary, by setting up a real-time monitoring unit within the longitudinal stretching equipment, the status of the stretching roller can be monitored in real time, and centrifugal or deformed stretching rollers caused by excessive wear can be detected in a timely manner. This makes it less likely for shaft runout to occur during stretching, thereby effectively ensuring the uniformity of stretching. In addition, in conjunction with the shaft support unit, multi-point support can be provided to support the shaft when wear or centrifugal conditions occur, so that the axis of the stretching roller gradually coincides with the axis of the bearing seat, temporarily restoring it to normal. This allows the stretching roller to continue working without stopping the machine, making the stretching process less likely to be interrupted and ensuring stretching efficiency. Furthermore, the end of the shaft support unit can adapt to the irregular outer wall of the bearing that has been worn, thereby making the shaft support more stable and significantly reducing the impact of wear on the film stretching quality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the main process of the first embodiment of this application;

[0022] Figure 2 This is a front view of the stretching roller according to the first embodiment of this application;

[0023] Figure 3 This is a schematic diagram of the real-time monitoring unit according to the first embodiment of this application;

[0024] Figure 4 This is a schematic diagram of the end face of the bearing housing according to the first embodiment of this application;

[0025] Figure 5This is a schematic diagram of a bearing housing with multiple support shaft units provided in the first embodiment of this application.

[0026] Figure 6 This is a schematic diagram of the structure of the pivot unit according to the first embodiment of this application;

[0027] Figure 7 This is a schematic diagram illustrating the process from wear to the recovery of eccentricity by the support shaft according to the first embodiment of this application;

[0028] Figure 8 This is a schematic diagram of multiple support shaft units providing multi-point support according to the first embodiment of this application;

[0029] Figure 9 This is a cross-sectional schematic diagram of the support column according to the second embodiment of this application;

[0030] Figure 10 This is a schematic diagram of the bearing outer wall with adaptive wear of the support column according to the second embodiment of this application.

[0031] Explanation of the labels in the diagram:

[0032] 1 Bearing housing, 11 Lower base, 12 Upper base, 2 Fixed measuring rod, 201 Upper laser, 3 Moving measuring rod, 301 Lower laser, 302 Arc slide rail, 4 Supporting shaft unit, 41 Supporting shaft column, 42 Electric push rod, 401 Groove, 402 Inner laser, 411 Electromagnetic base plate, 412 Bearing column, 413 External adaptation bag, 51 Compression spring, 52 Vertical rod, 501 Horizontal groove, 502 Vertical hole. Detailed Implementation

[0033] The two embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0034] First implementation method:

[0035] Figure 1 The biaxial stretching process for a highly oriented flexible label base film is shown, including the following steps:

[0036] S1. First, install a real-time monitoring unit and multiple support shaft units 4 on the bearing housing of the stretching roller in the longitudinal stretching equipment.

[0037] S2. The polymer resin is melt-extruded through an extruder to obtain a base film, and the base film is then wound up.

[0038] S31. The wound base film is unwound into the longitudinal stretching equipment by the guide roller, and the longitudinal stretching of the base film is achieved by the cooperation of multiple stretching rollers.

[0039] S32. During the longitudinal stretching process, the real-time monitoring unit monitors the status of the stretching roller in real time. When the wear between the bearing housing and the bearing is too large, the support shaft unit 4 supports the bearing and the stretching roller connected to it to temporarily restore the status of the stretching roller to normal. This allows the stretching roller to continue working without stopping the machine, and it is not easy to interrupt the stretching process.

[0040] S4. Then, the longitudinally stretched base film is guided into the transverse stretching equipment through the guide roller for transverse stretching. Finally, it is heat-set, cooled and wound up to complete the stretching of the base film.

[0041] In the biaxial stretching process of the above-mentioned high-orientation flexible label base film, by setting up a real-time monitoring unit in the longitudinal stretching equipment, the status of the stretching roller can be monitored in real time, and the situation of centrifugal or deformed stretching roller caused by excessive wear can be detected in time. This makes it less likely for the axial runout to occur during stretching, thereby effectively ensuring the uniformity of stretching.

[0042] like Figure 2-3 In the figure, a represents the stretching roller and b represents the bearing. The real-time monitoring unit includes a longitudinally symmetrical fixed measuring rod 2 and a moving measuring rod 3, both of which are located on the side of the bearing seat 1 facing the center of the stretching roller. The fixed measuring rod 2 and the moving measuring rod 3 are respectively provided with an upper laser 201 and a lower laser 301 at their respective ends close to each other. The emitting ends of the upper laser 201 and the lower laser 301 are perpendicular to the central axis of the stretching roller, and the distance between them and the surface of the stretching roller is the same.

[0043] like Figure 4 The bearing housing 1 includes a lower base 11 and an upper base 12 fixedly connected by bolts, with the upper base 12 located above the lower base 11. The fixed measuring rod 2 is fixedly connected to the upper base 12. An arc-shaped slide rail 302 is installed on the outer end of the lower base 11. The midpoint of the arc-shaped slide rail 302 is located on the vertical centerline of the lower base 11, and the central angle of the arc-shaped slide rail 302 is not less than 120°, allowing the moving measuring rod 3 to slide along the arc-shaped slide rail 302 with the lower laser 301, thereby detecting the contact between the lower surface of the stretching roller and the lower laser. Whether the distance between 301 is equal everywhere can be detected, and thus it can be detected whether the stretching roller and bearing seat 1 are eccentric due to excessive wear, which facilitates the normal operation of the support shaft unit 4. The moving measuring rod 3 is slidably connected to the arc-shaped slide rail 302, and the lower laser 301 is connected to the moving measuring rod 3 through the electric slide rail, so that the lower laser 301 can also move along the axial direction of the stretching roller on the moving measuring rod 3, so that it can detect whether multiple points before and after the stretching roller are on the same straight line, thereby effectively judging whether the stretching roller itself has bent and deformed.

[0044] like Figure 5-6In the figure, c represents the distance between the upper surface of the support column 41 and the inner wall of the lower base 11. The semi-circular inner wall of the lower base 11 has multiple grooves 401. Multiple support units 4 are installed inside the multiple grooves 401. The support unit 4 includes a support column 41 that is perfectly matched with the inner wall of the groove 401, an electric push rod 42 that is fixedly connected between the bottom of the groove 401 and the support column 41, and an inner laser 402 that is fixedly installed at the end of the support column 41 away from the axis of the bearing seat 1. The detection end of the inner laser 402 is perpendicular to the inner wall of the groove 401 and faces the axis of the bearing seat 1. It is worth noting that when there is no wear, the ends of the multiple support units 4 are located in the grooves 401 and are not flush with the inner wall of the lower base 11. Moreover, the distance between the upper surface of the multiple support columns 41 and the inner wall of the lower base 11 is the same. This makes it easy to affect the support unit 4 even if the bearing and the bearing seat 1 wear during the normal stretching process of the stretching roller, so that it can be relatively stable when supporting the worn stretching roller in the future.

[0045] Along the direction from both sides to the middle, the distribution density of multiple grooves 401 gradually increases. Since wear is generally concentrated at the bottom, that is, the wear is more severe as you go down, the density of the bottom support shaft unit 4 is increased, which makes the subsequent support shaft effect better. The end face of the support shaft column 41 facing the axis of the bearing seat 1 is arc-shaped, and the arc is consistent with the arc of the inner wall of the bearing seat 1. The support shaft column 41 is a rigid structure, and the material of the support shaft column 41 is consistent with that of the bearing seat 1, so that it can fit as close as possible to the outer wall of the bearing, which makes the subsequent support shaft effect better.

[0046] like Figure 7 When wear is detected, the distance between multiple support shaft units 4 and the inner surface of the lower base 11 (when it is not worn) can be controlled to increase. Figure 8 The multiple support shaft units 4 are aligned with the original outline of the inner wall of the lower base 11. At this time, due to wear, the upper surface of some or all of the support shaft units 4 protrudes from the inner surface of the lower base 11, thus forming multi-point support for the outer wall of the bearing. At this time, the multiple support shaft units 4 are controlled to continue to extend from the bottom to both sides, thereby gradually lifting the bearing with the stretching roller until the distance data detected by the upper laser 201 is consistent with or only slightly deviates from the unworn distance. Then, the shaft centering operation is performed. First, the lower laser 301 is controlled to slide the follow-up measuring rod 3 at the arc-shaped slide rail 302 to detect whether the stretching roller is coaxial with the bearing seat 1. If there are multiple data differences, the extension amplitude of the multiple support shaft units 4 can be adjusted according to the data until they are coaxial, thus completing the shaft support operation. This allows the stretching roller to temporarily return to normal without stopping the machine, and the normal film stretching operation can continue stably without interrupting the continuity of the film stretching process. After this stretching is completed, the abnormally worn bearing and bearing seat 1 can be maintained and repaired.

[0047] In summary, by setting up a real-time monitoring unit within the longitudinal stretching equipment, the status of the stretching roller can be monitored in real time, and centrifugal or deformed stretching rollers caused by excessive wear can be detected in a timely manner. This makes it less likely for shaft runout to occur during stretching, thereby effectively ensuring the uniformity of stretching. In addition, in conjunction with the function of the shaft support unit 4, multi-point support can be provided to support the shaft when wear or centrifugal conditions occur, so that the axis of the stretching roller gradually coincides with the axis of the bearing housing 1, temporarily restoring it to normal. This allows the stretching roller to continue working without stopping the machine, making it less likely to be interrupted during the stretching process and ensuring stretching efficiency.

[0048] Second implementation method:

[0049] This embodiment further improves the support shaft unit 4 based on the first embodiment, while the rest remains the same as the first embodiment.

[0050] Figure 9 As shown, along the direction close to the axis of bearing housing 1, the support column 41 sequentially includes an electromagnetic base plate 411, a bearing intermediate column 412, and an outer adaptation bladder 413, all fixedly connected to each other. The bearing intermediate column 412 has a transverse cavity 501 and multiple vertical holes 502 inside. The multiple vertical holes 502 are all located above the transverse cavity 501 and communicate with it. Each of the multiple vertical holes 502 has a support rod inside. The outer adaptation bladder 413 has multiple isolation sleeves fixedly connected inside, each corresponding to one of the multiple vertical holes 502. The support rods movably pass through the vertical holes 502 and extend into the isolation sleeves, with the upright 52 contacting the inner wall of the outer adaptation bladder 413. The support rods include extensions... The support rod 52 inside the outer adaptation bladder 413 and the compression spring 51 fixedly connected between the support rod 52 and the inner wall of the transverse cavity 501 are saturated with magnetorheological fluid. The transverse cavity 501 and multiple vertical holes 502 are also filled with magnetorheological fluid, and the surface of the magnetorheological fluid does not contact the support rod 52. When the magnetorheological fluid is in a liquid state, it does not easily affect the compression of the compression spring 51, allowing the support rod to adapt to the outer wall of the bearing and retract inward. When it is in a solid state, it restricts the compression of the compression spring 51. At this time, the support rod can cooperate with the equally solidified outer adaptation bladder 413 to provide stable support for the outer wall of the bearing, so that the support shaft can operate stably.

[0051] During the shaft support operation, the electromagnetic base plate 411 is first de-energized, at which point the magnetorheological fluid is in a liquid state, the outer adaptor 413 becomes soft, and the support rod experiences little or no binding force. Then, the shaft support unit 4 is extended to provide multi-point support to the worn bearing outer wall. The soft outer adaptor 413 and the upright 52, experiencing little or no binding force, can adapt to the irregular shape of the bearing outer wall due to wear during contact. Then, the bearing column 412 is energized to harden the magnetorheological fluid. At this point, if... Figure 10This provides a high degree of support to the outer wall of the bearing, allowing for subsequent shaft center adjustment. Compared to the first implementation method, the multi-point support in this method results in a larger contact area and a higher degree of fit, leading to better stability when the stretching roller continues to perform film stretching after the shaft center is adjusted, and significantly reducing the impact of wear on the film stretching quality.

[0052] In light of current practical needs, the above-described embodiments adopted in this application are not limited to these. Any changes made within the scope of knowledge possessed by those skilled in the art without departing from the concept of this application still fall within the protection scope of this invention.

Claims

1. A biaxial stretching process for a highly oriented flexible label base film, characterized in that: Includes the following steps: S1. First, install a real-time monitoring unit and multiple support shaft units (4) on the bearing seat of the stretching roller in the longitudinal stretching equipment. S2. The polymer resin is melt-extruded through an extruder to obtain a base film, and the base film is then wound up. S31. The wound base film is unwound into the longitudinal stretching equipment by the guide roller, and the longitudinal stretching of the base film is achieved by the cooperation of multiple stretching rollers. S32. During the longitudinal stretching process, the real-time monitoring unit monitors the state of the stretching roller in real time. When the wear between the bearing housing and the bearing is too large, the support shaft unit (4) supports the bearing and the stretching roller connected to it to temporarily restore the state of the stretching roller to normal. Thus, the stretching roller can continue to work without stopping the machine, and it is not easy to interrupt the stretching process. S4. Then, the longitudinally stretched base film is guided into the transverse stretching equipment through the guide roller for transverse stretching. Finally, it is heat-set, cooled and wound up to complete the stretching of the base film.

2. The biaxial stretching process for a highly oriented flexible label base film according to claim 1, characterized in that: The real-time monitoring unit includes a longitudinally symmetrical fixed measuring rod (2) and a moving measuring rod (3), both of which are located on the side of the bearing seat (1) facing the center of the stretching roller. The fixed measuring rod (2) and the moving measuring rod (3) are respectively provided with an upper laser (201) and a lower laser (301) at their respective ends close to each other. The emitting ends of the upper laser (201) and the lower laser (301) are both perpendicular to the central axis of the stretching roller, and the distance between the two and the surface of the stretching roller is the same.

3. The biaxial stretching process for a highly oriented flexible label base film according to claim 2, characterized in that: The bearing housing (1) includes a lower base (11) and an upper base (12) that are fixedly connected by bolts, and the upper base (12) is located above the lower base (11). The fixed measuring rod (2) is fixedly connected to the upper base (12). An arc-shaped slide rail (302) is installed on the outer end of the lower base (11). The moving measuring rod (3) is slidably connected to the arc-shaped slide rail (302). The lower laser (301) is connected to the moving measuring rod (3) through an electric slide rail.

4. The biaxial stretching process for a highly oriented flexible label base film according to claim 3, characterized in that: The midpoint of the arc-shaped slide rail (302) is located on the vertical centerline of the lower base (11), and the central angle of the arc-shaped slide rail (302) is not less than 120°.

5. The biaxial stretching process for a highly oriented flexible label base film according to claim 4, characterized in that: The lower base (11) has a plurality of grooves (401) carved into its semi-circular inner wall. The plurality of support shaft units (4) are respectively installed inside the plurality of grooves (401). The support shaft unit (4) includes a support shaft column (41) that is perfectly matched with the inner wall of the groove (401), an electric push rod (42) fixedly connected between the bottom of the groove (401) and the support shaft column (41), and an inner laser (402) fixedly installed at one end of the support shaft column (41) away from the axis of the bearing seat (1). The detection end of the inner laser (402) is perpendicular to the groove (401) and faces the inner wall of the axis of the bearing seat (1).

6. The biaxial stretching process for a highly oriented flexible label base film according to claim 5, characterized in that: Along the direction from both sides to the middle, the distribution density of the multiple grooves (401) gradually increases. The end face of the support column (41) facing the axis of the bearing seat (1) is arc-shaped, and the arc is consistent with the arc of the inner wall of the bearing seat (1). The support column (41) is a rigid structure, and the material of the support column (41) is consistent with that of the bearing seat (1).

7. The biaxial stretching process for a highly oriented flexible label base film according to claim 5, characterized in that: Along the direction close to the axis of the bearing seat (1), the support column (41) includes an electromagnetic base plate (411), a bearing column (412), and an outer adaptation bladder (413) that are fixedly connected to each other. The bearing column (412) has a transverse cavity (501) and multiple vertical holes (502) inside. The multiple vertical holes (502) are all located above the transverse cavity (501) and communicate with each other. The multiple vertical holes (502) are all provided with support rods inside. The outer adaptation bladder (413) has multiple isolation sleeves that are fixedly connected to the multiple vertical holes (502). The support rods move through the vertical holes (502) and extend into the isolation sleeves. The support rods are in contact with the inner wall of the outer adaptation bladder (413).

8. The biaxial stretching process for a highly oriented flexible label base film according to claim 7, characterized in that: The support rod includes a vertical rod (52) extending into the outer adaptation bladder (413) and a compression spring (51) fixedly connected between the vertical rod (52) and the inner wall of the transverse cavity (501). The outer adaptation bladder (413) is saturated with magnetorheological fluid. The transverse cavity (501) and multiple vertical holes (502) are also filled with magnetorheological fluid, and the liquid level of the magnetorheological fluid is lower than the lower end of the vertical rod (52).

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