JP2023150086A - Film thickness estimation device and film molding apparatus - Google Patents

Abstract

To provide a technique for determining the thickness of a film.SOLUTION: A film thickness estimation device is used for a film molding apparatus. The film molding apparatus 10 includes a first measuring instrument 50 that measures a frost line position of a film 12 conveyed from a die 14 in a flow direction. The film thickness estimation device includes a film thickness estimation part that estimates the thickness of the film 12 on the basis of the frost line position measured by the first measuring instrument 50.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a film thickness estimation device and a film forming device.

Patent Document 1 discloses a film forming apparatus that forms a film. This film forming apparatus keeps the film thickness within a target range by adjusting the lip width of the die, the wind speed and temperature of the cooling device, etc.

Japanese Patent Application Publication No. 2020-163768

In order to keep the film thickness within the target range, it is important to understand the film thickness. The film thickness of a film is usually ascertained by successively measuring the film thickness using a measuring device while changing the measurement position in the transverse direction of the film, as described in Patent Document 1. The inventors of the present invention have discovered a new idea for determining the thickness of a film using a different method.

One of the purposes of the present disclosure is to provide a technique for determining the thickness of a film.

An aspect of the present disclosure is a film thickness estimating device used in a film forming apparatus, which includes a first measuring device that measures a frost line position of a film sent from a die in a machine direction; a film thickness estimating section that estimates the film thickness of the film based on the frost line position.

According to the present disclosure, the thickness of the film can be determined.

FIG. 1 is a configuration diagram schematically showing a film forming apparatus according to an embodiment. It is a block diagram showing the function of the film forming device of an embodiment. FIG. 3 is an explanatory diagram regarding film thickness measurement points on the film. FIG. 3 is an explanatory diagram regarding film thickness measurement points on the film and predicted locations of frost lines. FIG. 3 is an explanatory diagram regarding relationship estimation processing. FIG. 2 is an explanatory diagram regarding the frost line passing portion on the film and the arrival time.

Embodiments will be described below. Identical components are given the same reference numerals and redundant explanations will be omitted. In each drawing, constituent elements are omitted, enlarged, or reduced as appropriate for convenience of explanation. The drawings should be viewed according to the direction of the symbols.

Please refer to FIG. The film forming apparatus 10 of this embodiment is an inflation forming apparatus. This film forming apparatus 10 includes a die 14 that forms a resin film 12 by discharging molten resin extruded from an extruder (not shown) through a die lip 28, and a die 14 that forms a resin film 12 on the most downstream side of the flow path of the film 12. A winder 16 for winding the winder is provided. In addition, the film forming apparatus 10 includes a take-off machine 20 that takes up the film 12 taken out from the die 14 and folds it into a flat shape, and a pair of take-off machines that guide the film 12 in the process of being taken up by the take-off machine 20. A stabilizer plate 22 is provided. In addition, the film forming apparatus 10 includes a cooling device 24 that cools the film 12, and a control device 26 that controls each component of the film forming apparatus 10. The control device 26 also functions as a film thickness estimation device 48 for estimating the film thickness distribution of the film 12.

The die 14 of this embodiment is a round die used in the inflation method, and molten resin is ejected from a ring-shaped die lip 28. The die 14 blows air out of the air outlet 30 inside the film 12 to form an expanded tube-shaped film 12 (also referred to as a bubble).

The die 14 is capable of adjusting the lip width (interval) of the die lip 28 at a plurality of circumferential positions. It can also be said that the die 14 can adjust the lip width distribution in the circumferential direction of the die lip 28. In order to achieve this, the die 14 can, for example, make a part of the die lip 28 a deformable flexible part and use a drive source to deform the flexible part, so that the lip can be formed at a plurality of circumferential positions. The width may be adjustable. This driving source is a linear actuator, heat bolt, or the like.

The die 14 can adjust the film thickness distribution of the film 12 in the circumferential direction by adjusting the lip width distribution of the die lip 28 in the circumferential direction. For example, by reducing the lip width at a certain circumferential position, the thickness of the film 12 taken out from there can be partially reduced. On the other hand, by increasing the lip width at a certain circumferential position, the thickness of the film 12 taken out from there can be partially increased. In this way, the die 14 constitutes a film thickness adjustment section 32 that can adjust the film thickness distribution in the circumferential direction of the film 12.

Please refer to FIGS. 1 and 2. Each block shown in FIG. 2 can be realized in terms of hardware by electronic components such as a CPU (Central Processing Unit) of a computer, circuits, mechanical devices, etc., and can be realized in terms of software by a computer program or the like. Here, we depict the functional blocks realized by these collaborations. Those skilled in the art will understand that these functional blocks can be realized in various ways by combining hardware and software.

The control device 26 includes a communication section 56 that executes communication processing with other components of the film forming apparatus 10 (die 14, cooling device 24, etc.) according to a predetermined communication protocol, and an input section that receives input operations by the user. 58, and a display section 60 that displays various information. In addition, the control device 26 includes a data processing section 62 that executes data processing using data acquired from other components of the film forming apparatus 10 and the input section 58, and a data processing section 62 that stores data used in the data processing section 62. and a storage unit 64 for storing information. The data processing unit 62 includes an operation control unit 70 that controls the operations of the die 14, the cooling device 24, etc., a film thickness estimation unit 72 that estimates the film thickness distribution of the film 12, and a correlation between the frost line position and the film thickness. and a relationship estimation unit 74 that estimates correlation information indicating . Details of the film thickness estimating section 72 and the relationship estimating section 74 will be described later.

The operation control unit 70 controls the operation of the film thickness adjustment unit 32 based on the film thickness distribution estimated by the film thickness estimation unit 72. The operation control unit 70 controls the operation of the film thickness adjustment unit 32 by transmitting a control command for manipulating the amount of operation that can be adjusted by the film thickness adjustment unit 32. The manipulated variable here refers to the lip width in the case of the die 14, and refers to the air volume and air temperature in the case of the cooling device 24, which will be described later. The film thickness adjustment unit 32 adjusts the film thickness by adjusting the manipulated variable (rip width in this case) according to the control command transmitted from the operation control unit 70.

The operation control unit 70 controls the film thickness adjustment unit 32 so that the film thickness distribution estimated by the film thickness estimation unit 72 falls within a preset target range. For example, consider a case where the film thickness at a specific circumferential position on the film 12 exceeds the target range (that is, it is excessively thick). In this case, the operation control unit 70 transmits a control command to the die 14 to reduce the lip width at the circumferential position of the die lip 28 corresponding to a specific circumferential position on the film 12, thereby Keep the film thickness at the position within the target range. Consider a case where the film thickness at a specific circumferential position on the film 12 is less than the target range (that is, it is too thin). In this case, the operation control unit 70 transmits a control command to the die 14 to increase the lip width at the circumferential position of the die lip 28 corresponding to a specific circumferential position on the film 12, thereby Keep the film thickness at the position within the target range. That is, the operation control unit 70 performs feedback control to control the film thickness adjustment unit 32 so that the film thickness distribution estimated by the film thickness estimation unit 72 falls within the target range.

Here, in the process of forming the film 12, frost lines FL are generated. The frost line FL generally refers to a boundary between the melted portion 12a and the solidified portion 12b that is generated when the melted portion 12a of the film 12 solidifies during the cooling process. The frost line FL in this specification refers to the generally known boundary between the melted portion 12a and the solidified portion 12b of the film 12, but is not limited thereto. The position of this frost line FL in the flow direction Da is referred to as a frost line position. The flow direction Da here refers to the direction in which the entire film moves when the film 12 is formed by the film forming apparatus 10 (so-called machine direction). When using the inflation method, the frost line position can be specified, for example, as the height from the upper end surface of the die 14 to the frost line FL in the film flow direction Da.

There is a correlation between this frost line position and the thickness of the film 12. This correlation is such that as the frost line position becomes higher, the film thickness becomes thicker, and as the frost line position becomes lower, the film thickness becomes thinner (see also FIG. 5, which will be described later). In other words, this correlation is such that the farther the frost line position is from the die 14, the thicker the film is, and the closer the frost line position is to the die 14, the thinner the film thickness is. This is because under constant cooling conditions, the thicker the film, the longer it takes to solidify, and the further the solidification position of the film 12 is from the die 14, the more the frost line position changes from the die 14. This is due to the distance (higher) from the This correlation varies depending on the material of the film 12, the blow ratio, and other molding conditions such as temperature and atmospheric pressure in the environment in which the film molding apparatus 10 is used.

One feature of the film thickness estimating device 48 of this embodiment is that it estimates the correlation between the frost line position and the film thickness by measuring the frost line position and the film thickness. Thereby, by understanding the frost line position, it is also possible to understand the film thickness of the film 12 according to the correlation. In addition, the film thickness estimating device 48 of this embodiment is characterized in that it estimates the film thickness distribution using the correlation between the frost line position and the film thickness and the measured value of the frost line position distribution. be. It can be said that the film thickness estimating device 48 is characterized in that it estimates the film thickness using this correlation and the measured value of the frost line position. The details will be explained below.

The film forming apparatus 10 includes a first measuring device 50 that measures the frost line position distribution of the film 12 sent from the die 14 in the flow direction Da. The frost line position distribution refers to the distribution of frost line positions in the circumferential direction of the film 12.

The first measuring device 50 includes at least one camera 52 that images the film 12, and a measurement processing section 54 that measures the frost line position distribution by processing the image output by the camera 52. The camera 52 is, for example, a visible light camera, a thermal camera, or the like. The measurement processing unit 54 measures the frost line positions at a plurality of circumferential positions by image processing the image output by the camera 52, and uses it as a measurement result of the frost line position distribution. The method of measuring the frost line position by image processing is not particularly limited, and may be realized using various methods including known methods. The measurement processing unit 54 may measure the frost line position by, for example, three-dimensional image processing, two-dimensional image processing, etc. using images output by the plurality of cameras 52. In addition, a mirror is placed within the field of view of the camera 52, and the frost line position is determined by image processing using the image output from a single camera 52 and the image inside the mirror within that image as a pseudo image. may be measured. By image processing using such images, frost line positions at a plurality of circumferential positions, that is, frost line position distribution can be easily measured simultaneously.

The first measuring device 50 simultaneously measures the frost line position distribution in a measurement target range in a predetermined circumferential direction at each first measurement period. This measurement target range is, for example, the entire circumference of the film 12. The first measuring device 50 sequentially transmits the measurement results of the frost line position distribution to the control device 26.

The storage unit 64 includes a correlation storage unit 66 that stores correlation information indicating the correlation between the frost line position and the film thickness. The correlation information is, for example, a relational expression, a table, etc. that uses the frost line position as input and the film thickness as output.

The data processing unit 62 includes a film thickness estimating unit 72 that estimates the film thickness distribution in the circumferential direction of the film 12 based on the frost line position distribution measured by the first measuring device 50. The process of estimating this film thickness distribution is called a film thickness estimation process. The film thickness estimation section 72 performs film thickness estimation processing based on this frost line position distribution and the correlation information stored in the correlation storage section 66. In this film thickness estimation process, the film thickness at a certain circumferential position is calculated by inputting the measured value of the frost line position measured at a certain circumferential position into a relational expression etc. as correlation information. Perform film thickness calculation processing. In this film thickness estimation process, by performing a film thickness calculation process for each measured value of the frost line position at a plurality of circumferential positions simultaneously measured by the first measuring device 50, the film thickness at each circumferential position is calculated. A certain film thickness distribution is calculated and this is used as the estimation result.

The above film thickness estimation process may be executed periodically when the film 12 is formed by the film forming apparatus 10, or may be executed when predetermined execution conditions are satisfied. The execution condition here is, for example, that a predetermined command is input through the input unit 58.

The effects of the above film thickness estimating device 48 will be explained.

The film thickness estimating device 48 includes a film thickness estimating section 72 that estimates the film thickness based on the frost line position measured by the first measuring device 50. Therefore, the film thickness of the film 12 can be determined using the film thickness estimation result by the film thickness estimating section 72.

The thickness variation of the film 12 mainly occurs in the melted portion 12a of the film 12 located upstream of the frost line FL of the film 12. The frost line FL is located at a position closer to the film thickness variation location of the film 12 than the film thickness measurement position by a second measuring device 80, which will be described later. By estimating the film thickness based on the frost line position specified using such a frost line FL, the variation in film thickness of the film 12 can be reduced more easily than when using the film thickness measurement value by the second measuring device 80, which will be described later. can be identified early.

If the thickness of the film 12 is sequentially measured while changing the measurement position like a second measuring device 80 described later, the period for repeatedly identifying the film thickness distribution will become long. Therefore, if the film thickness fluctuates between measuring the film thickness at a certain circumferential position and the next measurement, a reflection delay occurs in which there is a delay until the fluctuation is reflected in the measured value.

In this regard, according to the present embodiment, the film thickness estimation section 72 specifies the film thickness distribution using the frost line position distribution of the film 12 measured simultaneously by the first measuring device 50. Therefore, compared to the case where the thickness of the film 12 is sequentially measured while changing the measurement position, the period for repeatedly specifying the film thickness distribution can be shortened. Therefore, when the film thickness changes after estimating the film thickness at a certain circumferential position, a delay in reflection until the influence of the change is reflected in the estimated value can be suppressed. Furthermore, it is possible to suppress a decrease in the accuracy of specifying the film thickness due to the delay in reflection.

The operation control unit 70 controls the film thickness adjustment unit 32 so that the estimated value of the highly accurate film thickness distribution that suppresses the influence of such reflection delay falls within the target range. Therefore, the actual film thickness distribution of the film 12 can be adjusted with high precision by controlling the film thickness adjustment section 32.

The film thickness estimating unit 72 estimates the film thickness of the film 12 based on the correlation information stored in the storage unit 64 and the frost line position measured by the first measuring device 50. Therefore, by storing the correlation information in the storage unit 64 in advance, the film thickness can be easily estimated from the frost line position.

According to this embodiment, the frost line position distribution is simultaneously measured by image processing using the image by the first measuring device 50, and the film thickness distribution is estimated based on the frost line position distribution. Therefore, compared to the case where the film thickness distribution is determined by sequentially measuring the film thickness of the film 12 like the second measuring device 80 described later, the film thickness distribution can be determined earlier.

Next, other features of the film thickness estimating device 48 will be explained. Here, features for estimating correlation information used in film thickness estimation processing will be explained.

Please refer to FIGS. 1 and 3. FIG. 3 is a schematic diagram showing a part of the film 12 developed in a plane. The film forming apparatus 10 includes a second measuring device 80 that sequentially measures the thickness of the film 12 while changing the measurement position Pa in the circumferential direction of the film 12. As the second measuring device 80, for example, a capacitive film thickness meter or the like is used. The second measuring device 80 of this embodiment sequentially measures the thickness of the film 12 while going around the film 12 . The “measurement position Pa” here refers to a position on the film 12 at which the second measuring device 80 attempts to measure the film thickness. Here, the locus Pb of the measurement position Pa of the second measuring device 80 is also shown. Further, here, a state is shown in which one film thickness measurement point Pc on the film 12 and the measurement position Pa are at the same position. The "film thickness measurement point Pc" herein refers to a position on the film 12 where the film thickness is measured by the second measuring device 80.

The second measuring device 80 advances the measurement position Pa of the film 12 in the traveling direction Db as the film 12 advances in the traveling direction Da. Thereby, the film thickness measurement point Pc of the film 12 of the present embodiment fluctuates in a spiral shape that advances in the traveling direction Db toward the upstream side in the flow path of the film 12. The second measuring device 80 sequentially measures the film thickness of the film 12, thereby measuring the film thickness distribution in the measurement target range at every second measurement period (for example, 2 minutes) that is longer than the first measurement period. The second measuring device 80 sequentially transmits measurement results to the control device 26.

The above-mentioned relationship estimation unit 74 (see FIG. 2) calculates the frost line position and film thickness based on the frost line position measured by the first measuring device 50 and the film thickness measured by the second measuring device 80. Correlation information indicating the correlation between the two is estimated. The process of estimating this correlation information is called relationship estimation process. The details of the relationship estimation process will be explained below.

See FIG. 4. The relationship estimating unit 74 performs an association process of associating the film thickness measurement value obtained by the second measuring device 80 with the measured value of the frost line position measured by the first measuring device 50. In this mapping process, the measured value of the frost line position to be correlated with a certain film thickness measurement value is referred to as a target measurement value. In this embodiment, the objective measurement value of the frost line position is a measurement value that satisfies the following two conditions.

The first condition is that the frost line position measurement value is measured at the same circumferential position as the film thickness measurement value. "Same" here includes not only completely the same but also almost the same. The second condition is that the film thickness measurement value is a measurement value of the frost line position measured when the film thickness measurement point Pc at which the film thickness measurement value is measured passes through the predicted existence position Pd of the frost line FL. As the measured value of the frost line position that is an index of the film thickness of the film thickness measurement point Pc, the measured value of the frost line position measured when the film thickness measurement point Pc passes the predicted existence position Pd of the frost line FL, This will be associated with the film thickness measurement value at the film thickness measurement point Pc. The predicted existence position Pd of the frost line FL refers to a position where the frost line FL is predicted to exist. A passage time s0 is assumed at which the film thickness measurement point Pc, whose film thickness was measured at the position Pe by the second measuring device 80 at the measurement time s1, passes through the predicted existence position Pd of the frost line FL. At this time, it can be said that the second condition is a measured value of the frost line position measured at a time immediately before the passing time s0. The relationship estimating unit 74 specifies a target measured value of the frost line position to be associated with the film thickness measured value, which satisfies the second condition, in the following flow.

First, the relationship estimation unit 74 calculates the length ΔL from the measurement position Pa of the second measuring device 80 to the predicted existence position Pd of the frost line FL. The relationship estimation unit 74 calculates a length L1 in the flow direction Da from the die 14 to the measurement position Pa of the second measuring device 80, and a length in the flow direction Da from the die 14 to the predicted existence position Pd of the frost line FL. This length ΔL is calculated based on L0. The length ΔL can be calculated, for example, by subtracting the length L0 from the length L1. For the length L1, for example, a stored value stored in advance in the storage unit 64 is used. The length L0 is, for example, the measurement of the frost line position measured by the first measuring device 50 at the same circumferential position as the film thickness measurement point Pc at the measurement time s1 when the film thickness at the film thickness measurement point Pc was measured. value is used. In addition to this, a fixed value stored in advance in the storage unit 64 may be used as the length L0.

Next, the relationship estimating unit 74 determines, based on the calculated length ΔL and the winding speed v of the film 12, the distance required for the film thickness measurement point Pc on the film 12 to pass through the aforementioned length ΔL. Calculate the required time Δs. The winding speed v [m/sec] here refers to the winding speed by the winder 16. The film 12 flows at a substantially constant winding speed v [m/sec] between the frost line FL and the measurement position Pa by the second measuring device 80. Therefore, the required time Δs can be calculated, for example, by dividing the length ΔL by the winding speed v. For the winding speed v, for example, a set value stored in the storage unit 64 is used.

Next, the relationship estimation unit 74 determines whether the film thickness measurement point Pc is frost based on the measurement time s1 at which the second measuring device 80 measured the film thickness at the film thickness measurement point Pc and the calculated required time Δs. A passing time s0 when the line FL passes through the predicted existence position Pd is calculated. For example, the relationship estimating unit 74 calculates, as the passing time s0, a time that is back by the required time Δs with respect to the measurement time s1.

Next, the relationship estimation unit 74 specifies a target measurement value to be associated with the film thickness measurement value based on the measurement value of the frost line position measured by the first measuring device 50 immediately before the calculated passing time s0. do. At this time, the relationship estimation unit 74 may specify, for example, the measured value of the frost line position itself measured by the first measuring device 50 immediately before the passing time s0 as the target measured value. In addition, in order to reduce the influence of errors, the relationship estimation unit 74 also uses a representative value (for example, an average value ) may be specified as the target measurement value. This time width is set to be shorter than the second measurement period, for example. As described above, this target measurement value is specified as a measurement value measured at the same circumferential position as the film thickness measurement value.

Thereafter, the relationship estimating unit 74 performs an association process for associating the film thickness measurement value measured by the second measuring device 80 at the film thickness measurement point Pc on the film 12 with the target measurement value at the specified frost line position. I do.

See FIG. 5. The relationship estimating unit 74 performs the above-described association process to obtain a measurement value set that includes a film thickness measurement value and a frost line position measurement value that are associated with each other. FIG. 5 shows a set of measured values plotted on a graph in which the X-axis is the film thickness and the Y-axis is the frost line position. Here, the average value and standard deviation σ are calculated from multiple measurement values measured within a time span including the passing time s0, the average value is plotted, and the range of the average value ± standard deviation σ is shown with an error bar. It is shown by

The relationship estimation unit 74 acquires a plurality of measurement value sets by repeatedly performing the above-described association process. To achieve this, the above-described association process may be performed for each film thickness measurement value at a plurality of circumferential positions sequentially measured by the second measuring device 80. In addition to this, the above-described association process may be performed for each film thickness measurement value at the same circumferential position measured by the second measuring device 80 every second measurement cycle.

The relationship estimation unit 74 calculates an approximate expression as a relational expression indicating the correlation between the frost line position and the film thickness using the plurality of measurement value sets, and uses this as an estimation result of the correlation. Here, an approximation line 82 obtained using a linear approximation equation is shown as this approximation equation. The specific example of this approximation formula is not particularly limited, and various approximation formulas such as a polynomial curve approximation formula may be used. Alternatively, a table such as a look-up table showing the correlation between the frost line position and the film thickness may be generated using a plurality of measurement value sets, and this may be used as the estimation result of the correlation. The relationship estimation unit 74 stores the estimated correlation information in the correlation storage unit 66.

The above relationship estimation process may be executed when predetermined execution conditions are met. This execution condition is, for example, that the film forming apparatus 10 starts forming the film 12 for the first time. In addition to this, it may be executed when an update condition described later is satisfied.

As described above, the film thickness estimating device 48 of this embodiment estimates correlation information based on the frost line position measured by the first measuring device 50 and the film thickness measured by the second measuring device 80. A relationship estimation section 74 is provided. Therefore, even if the correlation information indicating the correlation between the frost line position and the film thickness is not stored in advance, the correlation information can be estimated using the measurement results of the first measuring device 50 and the second measuring device 80.

When a predetermined update condition is satisfied, the relationship estimation unit 74 updates the correlation information stored in the storage unit 64 with the correlation information newly estimated by performing the above-mentioned relationship estimation process. Good too. Thereby, by updating the correlation information when the update conditions are satisfied, it becomes possible to estimate the film thickness distribution using the correlation information that reflects the latest molding conditions.

The update conditions here are, for example, (1) that the molding conditions have been changed, (2) that a predetermined time interval has elapsed since the previous relationship estimation process was performed during molding of the film 12, (3) For example, a command for updating may be input to the input unit 58.

In addition, during the forming of the film 12, it is determined whether the estimated film thickness estimated by the film thickness estimating section 72 is reliable according to predetermined judgment conditions, and if the estimated film thickness is unreliable. The determination may be used as an update condition. To achieve this, for example, the coefficient of determination (R ² ) of the relational equation used in the film thickness estimation process is may be calculated. In this case, the determination condition may be that the calculated coefficient of determination is less than a predetermined reference value, and if the determination condition is met, it may be determined that the estimated value of the film thickness is unreliable. In this case, the film thickness estimation value calculated from the measured value of the frost line position measured when the film thickness measurement point Pc passes the predicted existence position Pd of the frost line FL and the film thickness measurement value measured at the film thickness measurement point Pc. What is necessary is to use a film thickness value set that includes the measured film thickness values.

Although an example has been described so far in which the film thickness adjustment section 32 is the die 14, the specific example is not particularly limited. This film thickness adjustment section 32 may be a cooling device 24 described below. In addition to this, the cooling device 24 and the die 14 may be used as separate film thickness adjustment sections 32.

Please refer to FIG. The cooling device 24 includes an air ring 154 that blows cooling air sent from a blower (not shown) through an air passage 150 toward the film 12 from a ring-shaped outlet 152. The cooling device 24 includes a plurality of valve devices 156 and a plurality of heaters 158 arranged within the ventilation path 150. The plurality of valve devices 156 are arranged in the circumferential direction so as to divide the inside of the ventilation passage 150 of the air ring 154 into an upstream ventilation passage 150a and a downstream ventilation passage 150b. The valve device 156 can flow air from the upstream ventilation passage 150a to the downstream ventilation passage 150b via a portion whose opening degree can be adjusted. By adjusting the opening degree of the valve device 156, the amount of cooling air supplied to the outlet 152 via the valve device 156 can be adjusted. By adjusting the opening degree of each of the plurality of valve devices 156, it is possible to adjust the wind flow distribution in the circumferential direction of the cooling air.

The plurality of heaters 158 are, for example, heating rods, and are arranged in the circumferential direction within the ventilation path 150. The heater 158 can heat the air flowing through the ventilation path 150. By adjusting the heating temperature of the heater 158, the temperature of the cooling air supplied to the outlet 152 via the periphery of the heater 158 can be adjusted. By adjusting the heating temperature of each of the plurality of heaters 158, it is possible to adjust the wind temperature distribution in the circumferential direction of the cooling air.

By adjusting at least one of the air volume distribution and the air temperature distribution of the cooling air by the cooling device 24, the film thickness distribution in the circumferential direction of the film 12 can be adjusted. The melted portion 12a of the film 12 gradually becomes thinner as it is pulled toward the downstream side in the process of progressing in the flow direction. Therefore, the faster the cooling rate of the film 12 is, the faster the melted portion 12a of the film 12 solidifies, resulting in a thicker film, and the slower the cooling rate of the film is, the slower the melted part 12a is, the slower it solidifies, and the thinner the film thickness becomes. For example, by increasing the amount of cooling air at a certain circumferential position, the cooling rate of the film 12 that is hit by the cooling air can be partially increased, and the thickness of the film 12 can be partially increased. The same applies when the temperature of the cooling air at a certain circumferential position is lowered (when the heating temperature of the heater 158 is brought closer to zero). On the other hand, by reducing the amount of cooling air at a certain circumferential position, the cooling speed of the film 12 that is hit by the cooling air is partially slowed down, and the film thickness of the film 12 is partially reduced. can. The same applies when the temperature of the cooling air at a certain circumferential position is increased (when the heating temperature of the heater 158 is increased).

Next, modifications of each of the constituent elements described so far will be described.

The film forming apparatus 10 may not include the second measuring device 80. The film thickness estimation device 48 does not need to include the input section 58, the display section 60, the operation control section 70, the relationship estimation section 74, and the like. The film thickness estimating device 48 may include at least one of a first measuring device 50 and a second measuring device 80.

The first measuring device 50 only needs to be able to measure the frost line position or the frost line position distribution in the circumferential direction of the film 12, and its specific example is not limited to the content of the embodiment. As an example of this, the first measuring device 50 may measure the frost line position using ink applied to the melted portion 12a of the film 12. When ink is applied to the melted portion 12a of the film 12, there is a correlation between the length of the ink in the flow direction Da observed downstream of the frost line FL and the frost line position. This correlation is such that the longer the length of the ink, the lower the frost line position, and the shorter the length of the ink, the higher the frost line position. Therefore, the frost line position may be specified by storing a relational expression, table, etc. showing this correlation, and inputting the length of the ink applied to the film 12 into the relational expression. In this case, the length of the ink may be specified by image processing using an image captured by the camera 52. The length of the ink in the flow direction may be specified by the length of the linearly extending ink in the flow direction itself, or may be specified by the interval between a plurality of dots of ink.

The film thickness estimating unit 72 only needs to be able to estimate the film thickness of the film 12 based on the frost line position measured by the first measuring device 50, and the specific method thereof is not limited to the content of the embodiment. It can be said that the method of estimating the film thickness distribution of the film 12 based on the measured value of the frost line position distribution by the film thickness estimating section 72 is not particularly limited.

The relationship estimation unit 74 does not need to update the correlation information stored in the correlation storage unit 66. In this case, a plurality of pieces of correlation information that individually correspond to a plurality of molding conditions may be stored in the correlation storage unit 66 in advance. In this case, when performing the film thickness estimation process, the film thickness estimation unit 72 may select correlation information corresponding to the actual molding conditions from among the plurality of correlation information.

In the association processing by the relationship estimation unit 74, the specific example of the objective measurement value of the frost line position to be associated with the film thickness measurement value is not limited to the content of the embodiment. For example, when a film thickness measurement value is measured at measurement time s1, a representative value (for example, an average value) of multiple measurement values at the frost line position measured within a predetermined time period including measurement time s1 is calculated. It may also be a target measurement value. In this case, the representative value (here, the average value) of the frost line position as the target measurement value may be associated with the film thickness measurement value measured at the measurement time s1. In addition, the film thickness measurement value is measured multiple times at the same film thickness measurement point Pc, and the representative value of the multiple measurement values of the frost line position measured at the measurement time of each film thickness measurement value (for example, average value) may be used as the target measurement value. In this case, the representative value (here, the average value) of the frost line position as the target measurement value may be associated with the representative value (for example, the average value) of the film thickness measurement values measured a plurality of times. In either case, in the association processing by the relationship estimation unit 74, the measured value of the frost line position measured at the same circumferential position as the film thickness measurement value is used, as explained in the above-mentioned first condition.

In addition to this, the target measurement value of the frost line position to be associated with the film thickness measurement value may be specified as follows.

See FIG. 6. When the frost line position is measured at a certain measurement time s1, the portion of the film 12 that passes through the frost line FL at the circumferential position where the frost line position was measured is referred to as a frost line passing portion Pf. An arrival time s2 at which this frost line passing portion Pf reaches the same flow direction position Pg as the measurement position of the second measuring device 80 is assumed. Hereinafter, based on the arrival time s2 of the frost line passing portion Pf of the film 12 to the position Pg and the measurement time s3 of the film thickness measurement value by the second measuring device 80, the frost line position to be associated with the film thickness measurement value will be determined. Describe a method for identifying target measurement values.

First, when the frost line position is measured at a measurement time s1 at a certain circumferential position, the relationship estimation unit 74 calculates the length ΔL' from the frost line FL at that circumferential position to the position Pg. This length ΔL' is longer than the length L1 in the flow direction Da from the die 14 to the measurement position (position Pg) of the second measuring device 80 to the length from the die 14 to the frost line FL (frost line passing portion Pf). It is calculated by subtracting L0'. As the length L1, a stored value stored in advance in the storage unit 64 is used as described above. For the length L0', the measured value of the frost line position measured by the first measuring device 50 at the measurement time s1 is used with respect to the circumferential position for which the length ΔL' is to be calculated. Next, based on the length ΔL′ calculated for a certain circumferential position and the winding speed v of the film 12, the relationship estimating unit 74 determines the frost line passing portion Pf on the film 12 at that circumferential position. calculates the required time Δs' for passing the above-mentioned length ΔL'. The required time Δs' can be calculated by dividing the length ΔL' by the winding speed v, similar to the above-described required time Δs. Thereafter, the relationship estimation unit 74 calculates a time that is advanced by the required time Δs' with respect to the measurement time s1 as the arrival time s2. This arrival time s2 represents the time at which the frost line passing portion Pf, which passes through the frost line FL at a certain circumferential position at the measurement time s1, reaches the position Pg, and the frost line passing portion Pf, which passes through the frost line FL at a certain circumferential position at the measurement time s1, reaches the position Pg, and the frost line passing portion Pf, which is measured at the circumferential position at the measurement time s1, reaches the position Pg. Treated as corresponding to the measured value of the frost line position.

When the frost line position distribution is measured at a certain measurement time s1, the relationship estimating unit 74 calculates the arrival time corresponding to the measured value of each frost line position in the above-described flow for each circumferential position at which the frost line position is measured. Calculate s2. In addition, the relationship estimation unit 74 generates measurement value information that links the measured value of the frost line position and the corresponding arrival time s2 for each circumferential position where the frost line position is measured. Perform processing. The relationship estimating unit 74 performs linking processing every time the frost line position distribution is measured, and stores a plurality of pieces of measured value information generated regarding the same circumferential position in the storage unit 64, thereby creating a group of measured value information. generate. The measurement value information group is generated for each circumferential position at which the frost line position is measured. The measurement value information group is generated, for example, as time series data in which a plurality of pieces of measurement value information are arranged in order of the measurement time of the frost line position at a certain circumferential position where the frost line position was measured.

When the film thickness is measured at measurement time s3 at a certain circumferential position, the relationship estimating unit 74 refers to a group of measurement value information generated for the same circumferential position as the film thickness measurement position. The relationship estimation unit 74 identifies the measurement value information having the arrival time s2 nearest to the measurement time s3 in the referenced measurement value information group. The relationship estimation unit 74 specifies the measured value of the frost line position linked to the arrival time s2 of the specified measured value information as the target measured value to be associated with the film thickness measured value measured at the measurement time s3. This makes it possible to accurately correlate the film thickness measurement value of the frost line passing portion Pf on the film 12 with the measured value of the frost line position measured when the frost line passing portion Pf passes the frost line FL. can.

As described above, in the association process, the film thickness measurement value and the frost line position measurement value that satisfy predetermined conditions are associated with each other. The film thickness measurement value to be correlated may be a single film thickness measurement value or a representative value of a plurality of film thickness measurement values. Similarly, the frost line position measurement value to be associated may be a single frost line position measurement value, or may be a representative value of a plurality of frost line position measurement values.

Up to this point, the first measuring device 50 has measured the frost line position distribution in the circumferential direction of the film 12, and based on the measured frost line position distribution, the film thickness estimation unit 72 has measured the frost line position distribution in the circumferential direction of the film 12. An example of estimating thickness distribution has been explained. However, the present invention is not limited to this, and the first measuring device 50 measures the frost line position at a specific circumferential position of the film 12, and the film thickness estimating unit 72 specifies the film 12 based on the measured frost line position. The film thickness at the circumferential position may be estimated.

Up to this point, an example has been described in which the present disclosure is applied to a film forming apparatus 10 that uses an inflation method to feed a tubular film 12 from a round die. The present disclosure is not limited thereto, and the contents of the present disclosure may be applied to a film forming apparatus 10 using a T-die method in which a sheet-like film 12 is sent from a T-die.

In order to understand the contents disclosed up to this point as contents common to the inflation method and the T-die method, it is sufficient to understand the contents disclosed up to this point as contents in which the words "circumferential direction" are replaced with "transverse direction". The "transverse direction" here can also be said to be the in-plane direction of the film 12 in a cross section perpendicular to the flow direction Da of the film. This "transverse direction" refers to the circumferential direction of the film 12 described so far when the tube-shaped film used in the inflation method is targeted. Moreover, this "transverse direction" refers to the width direction of the film 12 when the sheet-like film 12 used in the T-die method is targeted. For example, the first measuring device 50 measures the frost line position distribution in the transverse direction of the film 12, and the film thickness estimation unit 72 calculates the film thickness distribution in the transverse direction of the film 12 based on the frost line position distribution. This means that it is possible to estimate. Even when the sheet-like film 12 is targeted, the frost line position at a specific transverse direction position of the film 12 is measured, and based on the measured value of the frost line position, the film 12 at that specific transverse direction position is measured. The film thickness may be estimated.

The above embodiments and modifications are illustrative. These abstracted technical ideas should not be interpreted as being limited to the contents of the embodiments and modified forms. The contents of the embodiments and modified forms may be subject to many design changes such as changes, additions, and deletions of constituent elements. In the embodiments described above, the content that allows such design changes is emphasized by adding the notation "embodiment". However, design changes are allowed even if there is no such notation. The hatching added to the cross section of the drawing does not limit the material of the hatched object. Naturally, the positional relationships mentioned in the embodiments and modifications include those that can be considered to be the same when manufacturing errors and the like are taken into account.

Any combination of the above components is also effective. For example, an embodiment may be combined with any description of another embodiment, or a modified form may be combined with any description of the embodiment and other modified forms. Further, mutual substitution of any of the components and expressions of the present disclosure among methods, devices, systems, etc. is also effective as an aspect of the present disclosure.

DESCRIPTION OF SYMBOLS 10... Film forming device, 12... Film, 14... Die, 48... Film thickness estimation device, 64... Storage part, 72... Film thickness estimation part, 74... Relationship estimation part.

Claims (5)

A film thickness estimation device used in a film forming device,
The film forming apparatus includes a first measuring device that measures the frost line position of the film sent from the die in the machine direction,
The film thickness estimating device includes a film thickness estimating section that estimates the film thickness of the film based on the frost line position measured by the first measuring device. comprising a correlation storage unit that stores correlation information indicating a correlation between the frost line position and the film thickness of the film,
The film thickness estimating unit estimates the film thickness based on the correlation information stored in the correlation storage unit and a frost line position measured by the first measuring device. Film thickness estimation device. The film forming apparatus includes a second measuring device that sequentially measures the thickness of the film while changing the measurement position in the transverse direction of the film,
The film thickness estimating device includes a relationship estimation unit that estimates the correlation information based on the frost line position measured by the first measuring device and the film thickness measured by the second measuring device. 2. The film thickness estimation device according to 2. The film thickness estimation according to claim 3, wherein the relationship estimation unit updates the correlation information stored in the storage unit with the newly estimated correlation information when a predetermined update condition is satisfied. Device. A film forming apparatus comprising the film thickness estimating device according to any one of claims 1 to 4.

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