阅读说明：本技术 吹膜成型装置 (Blown film forming device ) 是由 藤原一优 石原佐知 于 2020-03-23 设计创作，主要内容包括：本发明提供一种能够确定凝固线高度的周向分布的吹膜成型装置。吹膜成型装置具备将透明或半透明的树脂呈管状挤出的模具及确定部(52),所述确定部(52)根据从凝固线的高度以上的位置拍摄所挤出的管状树脂的凝固线的2个图像或从凝固线的高度以下的位置拍摄所挤出的管状树脂的凝固线的2个图像来确定凝固线高度的周向分布。(The invention provides a blown film forming device capable of determining circumferential distribution of solidification line height. The blown film forming apparatus is provided with a die for extruding a transparent or translucent resin in a tubular shape, and a specifying unit (52), wherein the specifying unit (52) specifies the circumferential distribution of the height of the solidification line by taking 2 images of the solidification line of the extruded tubular resin from a position above the height of the solidification line or 2 images of the solidification line of the extruded tubular resin from a position below the height of the solidification line.)

1. A blown film forming apparatus is characterized by comprising:

a die for extruding a transparent or translucent resin in a tubular shape; and

the specifying unit specifies a circumferential distribution of the solidification line heights by capturing 2 images of the solidification line of the extruded tubular resin from a position above the solidification line height or capturing 2 images of the solidification line of the extruded tubular resin from a position below the solidification line height.

2. The blown film forming apparatus according to claim 1,

the specifying unit specifies a circumferential distribution of the height of the solidification line from the 2 images by discriminating a solidification line on a near side and a solidification line on a far side of the tubular resin of at least 1 of the 2 images from the 2 images.

3. The blown film forming apparatus according to claim 2,

the 2 images are images taken from different heights,

the specifying unit discriminates between a solidification line on the near side and a solidification line on the far side of the tubular resin in the 2 images based on a difference in the shape of the solidification line detected from the 2 images.

4. A blown film forming apparatus is characterized by comprising:

a die for extruding a transparent or translucent resin in a tubular shape; and

the specifying unit specifies a circumferential distribution of the height of the solidification line from an image of the solidification line of the extruded tubular resin taken from above or below the height of the solidification line.

5. The blown film forming apparatus according to claim 4,

the specifying unit specifies circumferential distributions of the solidification line heights by using, as solidification lines on the back side and the near side of the tubular resin, portions of the solidification lines located on the upper side and the lower side in the image when the image is taken from above the height of the solidification lines, and specifies circumferential distributions of the solidification line heights by using, as solidification lines on the near side and the far side of the tubular resin, portions of the solidification lines located on the upper side and the lower side in the image when the image is taken from below the height of the solidification lines.

6. A blown film forming apparatus is characterized by comprising:

a die for extruding a transparent or translucent resin in a tubular shape; and

the specifying unit specifies a circumferential distribution of the height of the solidification line by taking 2 images of the solidification line of the extruded tubular resin from circumferentially different positions.

Technical Field

The present application claims priority based on japanese patent application No. 2019-068588, applied 3/29/2019. The entire contents of this Japanese application are incorporated by reference into this specification.

The invention relates to a film blowing forming device.

Background

There is known a blown film molding in which a molten resin is extruded from a die into a tubular shape, and air is blown into the inside of the tubular shape to expand the resin and form a thin film. Conventionally, there has been proposed a technique for controlling the thickness of the resin within a target range by adjusting the lip width, the volume of cooling air, and the air temperature.

Patent document 1: japanese patent laid-open publication No. 2017-177348

If the height of the solidification line (frost line) becomes uneven in the circumferential direction, the quality of the film is degraded, for example, the film is loosened. Therefore, in the blown film forming, it is important to control the height of the solidification line so that the height of the solidification line becomes uniform in the circumferential direction by adjusting the lip width, the air volume of the cooling air, the circumferential distribution of the air temperature, or the like. For this reason, as a precondition, it is necessary to determine the circumferential distribution of the solidification line heights. Currently, the user determines the circumferential distribution of the coagulation line heights with the naked eye. If the circumferential distribution of the solidification line heights can be automatically determined, the burden on the user can be reduced, and the solidification line heights can be automatically controlled according to the result.

As a method of determining the circumferential distribution of the height of the solidification lines, it is conceivable to take an image of the solidification lines in the horizontal direction from the same height as the solidification lines, detect the solidification lines from the taken image by image analysis, and determine the circumferential distribution of the height from the detected solidification lines. Fig. 1 shows an image of the coagulation line F taken from the same height level as the coagulation line F. When the resin is transparent or translucent, not only the coagulation line F of the near side portion but also the coagulation line F of the far side portion of the tubular resin are captured in the captured image, but these cannot be distinguished from the image. That is, in fig. 1, it is not possible to distinguish which of the coagulation line F located on the upper side and the coagulation line F located on the lower side is the coagulation line of the near side portion and which is the coagulation line of the far side portion. As a result, the circumferential distribution of the height of the solidification line cannot be determined. Therefore, determining the circumferential distribution of the solidification line heights is not so simple.

Disclosure of Invention

The present invention has been made in view of such circumstances, and an exemplary object of one embodiment thereof is to provide a blown film forming apparatus capable of determining circumferential distribution of the height of a solidification line.

In order to solve the above problem, a blown film forming apparatus according to an embodiment of the present invention includes a die for extruding a transparent or translucent resin in a tubular shape, and a determination unit for determining a circumferential distribution of the height of a solidification line by taking 2 images of the solidification line of the extruded tubular resin from a position above the height of the solidification line or 2 images of the solidification line of the extruded tubular resin from a position below the height of the solidification line.

Another embodiment of the present invention is also a blown film forming apparatus. The apparatus includes a die for extruding a transparent or translucent resin in a tubular shape, and a determination unit for determining a circumferential distribution of the height of a solidification line by imaging an image of the solidification line of the extruded tubular resin from a position above or below the height of the solidification line.

Still another embodiment of the present invention is a blown film forming apparatus. The apparatus includes a die for extruding a transparent or translucent resin in a tubular shape, and a determination section for determining a circumferential distribution of the height of a solidification line by taking 2 images of the solidification line of the extruded tubular resin from circumferentially different positions.

In addition, any combination of the above-described constituent elements or any combination obtained by mutually replacing the constituent elements and expressions of the present invention among methods, apparatuses, systems and the like is also effective as an aspect of the present invention.

Effects of the invention

According to the present invention, the circumferential distribution of the height of the solidification line can be determined.

Drawings

Fig. 1 is a view showing an image of a solidification line taken from the same height level as the solidification line.

Fig. 2 is a diagram showing a basic configuration of a blown film forming apparatus according to embodiment 1.

Fig. 3 is a block diagram schematically showing the function and configuration of the control device of fig. 1.

Fig. 4(a) and 4(b) illustrate a method of discriminating between the near side portion of the bubble and the far side portion of the bubble by the determination unit in fig. 3.

Fig. 5(a) and 5(b) illustrate a method of discriminating between the near side portion of the bubble and the far side portion of the bubble by the determination unit in fig. 3.

Fig. 6 is a diagram showing a basic configuration of a blown film forming apparatus according to a modification.

Fig. 7 is a diagram showing a basic configuration of a blown film forming apparatus according to embodiment 2.

Fig. 8 is a diagram showing a basic configuration of a blown film forming apparatus according to embodiment 3.

In fig. 9, fig. 9(a) and 9(b) are diagrams illustrating a method of determining the circumferential distribution of the height of the solidification line by the determination unit.

In the figure: 1-blown film forming device, 7-control device, 10-die, 26-1 st camera device, 27-2 nd camera device, 52-determination part.

Detailed Description

The present invention will be described below in accordance with preferred embodiments with reference to the accompanying drawings. The same or equivalent constituent elements, components, and processes shown in the respective drawings are denoted by the same reference numerals, and overlapping descriptions are appropriately omitted. The embodiments are not intended to limit the invention but to exemplify the invention, and all the features or combinations thereof described in the embodiments are not necessarily essential to the invention.

(embodiment 1)

Fig. 2 shows a basic configuration of a blown film forming apparatus 1 according to embodiment 1. The blown film forming apparatus 1 includes a mold 2, a cooling device 3, a pair of stabilizing plates 4, a tractor 5, a thickness acquiring unit 6, a 1 st image pickup device 26, a 2 nd image pickup device 27, and a control device 7.

The molten transparent or translucent resin supplied from an extruder (not shown) is extruded from an annular discharge port 2a formed in the die 2. At this time, air is blown out from air blowing ports 2b formed in the central portion of the die 2 toward the inside of the extruded resin, thereby forming a thin resin film (hereinafter, also referred to as "bubble") that is expanded into a tubular shape.

The cooling device 3 is disposed above the mold 2. The cooling device 3 blows cooling air into the tube bulb to cool the tube bulb.

The pair of stabilizing plates 4 is disposed above the cooling device 3, and guides the bulb to the tractor 5. The tractor 5 is disposed above the stabilizer plate 4. The tractor 5 includes a pair of pinch rollers 38. The pair of pinch rollers 38 is driven and rotated by a motor, not shown, and folds the guided bulb while pulling it up. The winder 20 winds the folded resin film to form a film roll 11.

The thickness acquisition unit 6 is disposed between the cooling device 3 and the stabilizing plate 4. The thickness acquiring section 6 acquires (measures) the thickness of the bulb at each position in the circumferential direction while rotating around the circumference of the bulb. The thickness data acquired by the thickness acquiring unit 6 is sent to the control device 7.

The 1 st and 2 nd imaging devices 26 and 27 are disposed below the height of the solidification line F, and image the solidification line F. The lower side of the height of the solidification line F may be the lower side of the minimum height Min of the solidification line F, or the lower side of the intermediate height ((Max + Min)/2) between the minimum height Min of the solidification line F and the maximum height Max of the solidification line F. The 2 nd imaging device 27 is disposed below the 1 st imaging device 26, preferably directly below the 1 st imaging device 26. The 1 st image pickup device 26 and the 2 nd image pickup device 27 may be any devices as long as they can pick up an image that can specify the solidification line F, and may be a normal camera that can pick up visible light, or may be an infrared camera that can pick up infrared light, that is, can pick up a thermal image.

In the present embodiment, the 1 st image pickup device 26 and the 2 nd image pickup device 27 are arranged obliquely upward (i.e., with the coagulation line F looking upward). The elevation angles of the 1 st image pickup device 26 and the 2 nd image pickup device 27 may be the same angle or different angles, for example, an elevation angle of the 2 nd image pickup device 27 located further downward may be larger than an elevation angle of the 1 st image pickup device 26. Further, as long as the coagulation line F is captured in the image, the 1 st imaging device 26 and the 2 nd imaging device 27 may be oriented in the horizontal direction (that is, the elevation angle may be 0 °). The 1 st image pickup device 26 and the 2 nd image pickup device 27 transmit the picked-up images to the control device 7. Hereinafter, the image captured by the 1 st imaging device 26 will be referred to as a 1 st image, and the image captured by the 2 nd imaging device 27 will be referred to as a 2 nd image.

The control device 7 is a device for controlling the blown film forming device 1 in a unified manner.

Fig. 3 is a block diagram schematically showing the function and configuration of the control device 7. Each block shown here can be realized by an element such as a CPU of a computer or a mechanical device in terms of hardware, and by a computer program or the like in terms of software. Accordingly, those skilled in the art will appreciate that these functional blocks can be implemented in various forms by a combination of hardware and software.

The control device 7 includes: a communication unit 40 that executes communication processing with the thickness acquisition unit 6, the 1 st image pickup device 26, and the 2 nd image pickup device 27 in accordance with various communication protocols; a U/I unit 42 that receives an operation input by a user and displays various screens on the display unit; a data processing unit 46 for executing various data processing based on the data acquired from the communication unit 40 and the U/I unit 42; and a storage unit 48 for storing the data referred to and updated by the data processing unit 46.

The storage section 48 includes an image storage section 64. The image storage unit 64 stores the 1 st image and the 2 nd image transmitted from the 1 st image pickup device 26 and the 2 nd image pickup device 27.

The data processing unit 46 includes a receiving unit 50, a specifying unit 52, and a motion control unit 54.

The receiving unit 50 receives the thickness of the bubble, the 1 st image, and the 2 nd image from the thickness acquiring unit 6, the 1 st imaging device 26, and the 2 nd imaging device 27, respectively. The receiving unit 50 stores the received 1 st and 2 nd images in the image storage unit 64.

The specifying unit 52 specifies the circumferential distribution of the height of the coagulation line from the 1 st image and the 2 nd image stored in the image storage unit 64.

First, the determination unit 52 detects the coagulation line F in each of the 1 st image and the 2 nd image by a known image processing technique. As described above, since the resin is transparent or translucent, the coagulation line F at the near side portion of the bubble and the coagulation line F at the far side portion of the bubble can be detected from the respective images.

Next, the determination section 52 determines the detected coagulation line F as the near side portion of the bubble and the far side portion of the bubble.

Fig. 4 and 5 are diagrams illustrating a method of determining the near side portion and the far side portion of the bulb by the determination unit 52. Fig. 4(a) and 4(b) show the 1 st image and the 2 nd image, respectively. Similarly, fig. 5(a) and 5(b) show the 1 st image and the 2 nd image, respectively.

In the 1 st image, 2 solidified lines F, i.e., a solidified line F located on the upper side and a solidified line F located on the lower side in the image, are captured. The solidification line F located on the upper side and the solidification line F located on the lower side cannot be distinguished by referring to the 1 st image alone from each other, and the solidification line F located on the near side of the bubble and the solidification line located on the far side of the bubble are distinguished from each other.

Similarly, in the 2 nd image, 2 solidified lines F, i.e., a solidified line F located on the upper side and a solidified line F located on the lower side in the image, are also captured. Referring to only the 2 nd image is a solidification line at which one of the solidification line F located on the upper side and the solidification line F located on the lower side is the solidification line at the near side portion of the bubble and the other is the solidification line at the far side portion of the bubble.

Therefore, the specification unit 52 determines the near side portion of the bubble and the far side portion of the bubble with reference to both the 1 st image and the 2 nd image. The principle of this will be explained below.

When viewed from the imaging devices 26 and 27, the focus is on a certain position in the left-right direction, and here, the focus is on the center position in the left-right direction. When viewed from the imaging devices 26 and 27, a point located at the center in the left-right direction of the solidification line F on the upper side is referred to as a 1 st point P₁The point located at the center in the left-right direction of the lower coagulation line F is referred to as the 2 nd point P₂. Then, the 1 st imaging device 26 and the 1 st focal point P are connected₁And a line connecting the 1 st imaging device 26 and the 2 nd focal point P₂Is referred to as angle 1 α₁. Then, the 2 nd imaging device 27 and the 1 st focal point P are connected₁And a line connecting the 2 nd imaging device 27 and the 2 nd focal point P₂Is referred to as angle 2 α₂. In FIG. 1, point of attack P1 is shown₁2 nd eyepoint P₂Angle 1 α₁And angle 2 α₂。

First, consider a case where the coagulation line F on the near side of the bubble is located on the upper side and the coagulation line F on the far side of the bubble is located on the lower side. Assume that the imaging devices 26 and 27 are connected to the 1 st focal point P₁And 2 nd eyepoint P₂On the line of (1), then the 1 st angle α₁Angle 2 α₂Becomes 0 DEG, the 1 st point of attack P₁And 2 nd eyepoint P₂The image pickup devices 26 and 27 are thereby moved downward to the 1 st angle α₁Angle 2 α₂Becomes larger and the 1 st point of attack P₁And point of attack P of No. 2₂Gradually further away. As can be seen from this, the distance between the coagulation line F at the front portion of the upper bulb and the coagulation line F at the rear portion of the lower bulb becomes wider in the 2 nd image captured by the 2 nd imaging device 27 located further downward.

Next, a case where the coagulation line F on the near side of the bubble is located on the lower side and the coagulation line F on the far side of the bubble is located on the upper side is considered. Assume that the imaging devices 26 and 27 are connected to the 1 st focal point P₁And 2 nd eyepoint P₂On the line of (1), then the 1 st angle α₁Angle 2 α₂Becomes 0 DEG, the 1 st point of attack P₁And 2 nd eyepoint P₂The image pickup devices 26 and 27 are thereby moved upward to the 1 st angle α₁Angle 2 α₂Becomes larger and the 1 st point of attack P₁And point of attack P of No. 2₂Gradually further away. As can be seen from this, the distance between the coagulation line F at the front portion of the upper bulb and the coagulation line F at the rear portion of the lower bulb becomes narrower in the 2 nd image captured by the 2 nd imaging device 27 located further downward.

As described above, if the interval between the solidification line F located on the upper side and the solidification line F located on the lower side of the 2 nd image captured by the 2 nd imaging device 27 located on the lower side is wider than the interval between the solidification line F located on the upper side and the solidification line F located on the lower side of the 1 st image captured by the 1 st imaging device 26 located on the upper side, it is found that the solidification line F located on the upper side is the solidification line on the near side of the bubble, and the solidification line F located on the lower side is the solidification line on the far side of the bubble. On the other hand, if the interval between the coagulation line F located on the upper side and the coagulation line F located on the lower side in the 2 nd image is narrower than the interval between the coagulation line F located on the upper side and the coagulation line F located on the lower side in the 1 st image, it is found that the coagulation line F located on the upper side is the coagulation line on the inner side of the bubble, and the coagulation line F located on the lower side is the coagulation line on the near side of the bubble.

Based on the above principle, the determination unit 52 determines the coagulation line F on the near side of the bubble and the coagulation line F on the far side of the bubble from the difference between the shape indicated by the coagulation line F in the 1 st image and the shape indicated by the coagulation line F in the 2 nd image.

Specifically, as long as the interval in the vertical direction of the portion other than both ends of the 2 nd image is entirely wider than the interval in the vertical direction of the portion other than both ends of the 1 st image as shown in fig. 4(a) and 4(b) for the 2 lines of the coagulation lines F extending substantially in the left and right directions in each image, the determination section 52 determines that the line located on the upper side in each image is the coagulation line F on the near side portion of the bubble and the line located on the lower side is the coagulation line F on the back side portion of the bubble. In other words, if the shape indicated by the in-image coagulation line F in the 1 st image is a ring shape that is flattened in the longitudinal direction than the shape indicated by the in-image coagulation line F in the 2 nd image, the determination unit 52 determines that the line located on the upper side in each image is the coagulation line F on the near side portion of the bubble and the line located on the lower side is the coagulation line F on the far side portion of the bubble.

On the other hand, as for the 2 lines of the coagulation line F extending substantially in the left and right directions in each image, as long as the interval in the up-down direction of the portion other than both ends of the 2 nd image is entirely narrower than the interval in the up-down direction of the portion other than both ends of the 1 st image as shown in fig. 5(a) and 5(b), the determination section 52 determines that the line located on the upper side in each image is the coagulation line F at the back side portion of the bubble and the line located on the lower side is the coagulation line F at the near side portion of the bubble. In other words, if the shape indicated by the in-image coagulation line F in the 2 nd image is a ring shape that is flattened in the longitudinal direction than the shape indicated by the in-image coagulation line F in the 1 st image, the determination unit 52 determines that the line located on the upper side in each image is the coagulation line F on the back side portion of the bubble, and the line located on the lower side is the coagulation line F on the near side portion of the bubble.

Then, the determination unit 52 determines the circumferential distribution of the coagulation line heights by, for example, a known technique based on the determination result and at least one of the 1 st image and the 2 nd image.

The operation control section 54 controls the operation of the blown film forming apparatus 1. For example, the operation controller 54 adjusts the adjustment requirements (for example, the lip width, the volume of cooling air, the air temperature, and the like) so that the thickness of the bubble falls within the allowable range and the solidification line height is relatively uniform in the circumferential direction. For example, if the solidification line height of a portion in the circumferential direction is higher than the surrounding or desired height, the operation controller 54 may increase the volume of the cooling air in the corresponding portion in the circumferential direction to decrease the solidification line height of the portion.

In addition, as a modification, a display control unit, not shown, displays the circumferential distribution of the thickness of the bubble or the circumferential distribution of the height of the solidification line on a screen, and a user determines the operation amount of the expansion theoretical element with reference to the information, and the operation control unit 54 may control the operation of the blown film forming apparatus 1 in accordance with the determination.

The above is the structure of the blown film forming apparatus 1. Next, the operation will be described. This process is repeatedly executed at a predetermined cycle.

The 1 st and 2 nd imaging devices 26 and 27 image the solidification line F of the forming bulb and transmit the imaged image to the control device 7.

The control device 7 detects the coagulation line F in the 1 st image and the 2 nd image, discriminates the front side portion and the back side portion of the bubble of the detected coagulation line F, and determines the circumferential distribution of the coagulation line height based on the discrimination result and at least one of the 1 st image and the 2 nd image. The control device 7 controls the operation of the blown film forming device 1 based on the determined circumferential distribution of the solidification line heights so that the solidification line heights are relatively uniform in the circumferential direction.

According to the present embodiment described above, the circumferential distribution of the coagulation line heights can be automatically determined from the plurality of images of the coagulation line F on the near side and the far side into which the bubble is shot.

As described above, according to embodiment 1, one aspect of the present invention is explained. Next, a modification of embodiment 1 will be described.

(1 st modification of embodiment 1)

In the above-described embodiment, the case where the circumferential distribution of the solidification line heights is determined from the plurality of images taken from below the height of the solidification line F has been described, but the circumferential distribution of the solidification line heights may be determined from the plurality of images taken from above the height of the solidification line F.

At this time, the 1 st imaging device 26 and the 2 nd imaging device 27 are disposed above the height of the solidification line F. The height above the height of the coagulation line F may be above the maximum height Max of the coagulation line F, or may be above the intermediate height ((Max + Min)/2) between the minimum height Min of the coagulation line F and the maximum height Max of the coagulation line F. The 2 nd imaging device 27 is disposed above the 1 st imaging device 26, preferably directly above the 1 st imaging device 26. The 1 st imaging device 26 and the 2 nd imaging device 27 are disposed obliquely downward (i.e., so as to make the solidified line F in a plan view). The depression angles of the 1 st image pickup device 26 and the 2 nd image pickup device 27 may be the same angle or different angles, for example, an angle in which the depression angle of the 2 nd image pickup device 27 located further downward is larger than the depression angle of the 1 st image pickup device 26. Further, as long as the coagulation line F is captured in the image, the 1 st imaging device 26 and the 2 nd imaging device 27 may be oriented in the horizontal direction (that is, the depression angle may be 0 °).

As for the 2 solidification lines F extending substantially to the left and right within the image, the determination section 52 determines that the line located on the upper side within each image is the solidification line F at the back side portion of the bubble and the line located on the lower side is the solidification line F at the near side portion of the bubble, as long as the interval in the vertical direction of the portion other than both ends of the 2 nd image is entirely wider than the interval in the vertical direction of the portion other than both ends of the 1 st image as shown in fig. 4(a) and 4 (b). In other words, if the shape indicated by the in-image coagulation line F in the 1 st image is a ring shape that is flattened in the longitudinal direction than the shape indicated by the in-image coagulation line F in the 2 nd image, the determination unit 52 determines that the line located on the upper side in each image is the coagulation line F on the back side portion of the bubble, and the line located on the lower side is the coagulation line F on the near side portion of the bubble.

On the other hand, as for the 2 lines of the coagulation lines F extending substantially in the left-right direction in the image, as long as the interval in the up-down direction of the portion other than both ends of the 2 nd image is narrower as a whole than the interval in the up-down direction of the portion other than both ends of the 1 st image as shown in fig. 5(a) and 5(b), the determination section 52 determines that the line located on the upper side in each image is the coagulation line F of the near side portion of the bubble and the line located on the lower side is the coagulation line F of the back side portion of the bubble. In other words, if the shape indicated by the in-image coagulation line F in the 2 nd image is a ring shape that is flattened in the longitudinal direction than the shape indicated by the in-image coagulation line F in the 1 st image, the determination unit 52 determines that the line located on the upper side in each image is the coagulation line F on the near side portion of the bubble and the line located on the lower side is the coagulation line F on the far side portion of the bubble.

According to this modification, the same effects as those of the embodiment can be achieved.

(modification 2 of embodiment 1)

In the above-described embodiment, the case where the circumferential distribution of the height of the coagulation line is determined from the plurality of images photographed from below the height of the coagulation line F has been described, and in the above-described modification, the case where the circumferential distribution of the height of the coagulation line is determined from the plurality of images photographed from above the height of the coagulation line F has been described, but if the coagulation line F detected from the image photographed in the horizontal direction from substantially the same height as the coagulation line F is annular, the circumferential distribution of the height of the coagulation line may be determined from the image and the image photographed from below or above the height of the coagulation line F.

Fig. 6 shows a basic configuration of a blown film forming apparatus 1 according to a modification. In the present modification, the 1 st imaging device 26 is disposed so as to be oriented in the horizontal direction at the same height as the solidification line F. Specifically, the 1 st imaging device 26 is disposed such that the optical axis (i.e., the optical axis of the lens (not shown)) Ax thereof is oriented in the horizontal direction and passes between the maximum value Max and the minimum value Min of the coagulation line height.

The determination unit 52 may determine the circumferential distribution of the solidification line heights from the 1 st image and the 2 nd image in the same manner as in the above-described embodiment when the 2 nd imaging device 27 is disposed below the height of the solidification line F as in the above-described embodiment, and may determine the circumferential distribution of the solidification line heights from the 1 st image and the 2 nd image in the same manner as in the above-described modification when the 2 nd imaging device 27 is disposed above the height of the solidification line F as in the above-described modification.

According to this modification, the same effects as those of the embodiment can be achieved.

(embodiment 2)

In embodiment 1, the case where the circumferential distribution of the solidification line height is determined from 2 images taken from below the solidification line F height has been described. In embodiment 2, a case will be described in which the circumferential distribution of the height of the solidification line is determined from 1 image taken from below the height of the solidification line F. The following description focuses on differences from embodiment 1.

Fig. 7 shows a basic configuration of a blown film forming apparatus 1 according to embodiment 2. The blown film forming apparatus 1 includes a mold 2, a cooling device 3, a pair of stabilizing plates 4, a tractor 5, a thickness acquiring unit 6, a 1 st image pickup device 26, and a control device 7. That is, unlike the blown film forming apparatus of embodiment 1, the blown film forming apparatus 1 of the present embodiment does not include the 2 nd imaging device 27.

The control device 7 is configured as shown in the block diagram of fig. 3, similarly to embodiment 1.

First, as in embodiment 1, the determination unit 52 detects the coagulation line F in the image.

However, even if the solidification line heights are distributed to some extent in the circumferential direction in the stable molding state, if an image of the solidification line F is taken from a position below the height of the solidification line F to some extent, it is considered that, of the 2 lines of the solidification line F extending substantially to the left and right in the image, the line located on the upper side in the image is the solidification line F on the near side of the bubble, and the line located on the lower side is the solidification line F on the far side of the bubble (see fig. 4).

Therefore, the determination unit 52 of the present embodiment determines the circumferential distribution of the solidification line heights from the image in which the line located on the upper side in the image is the solidification line F on the near side portion of the bubble and the line located on the lower side is the solidification line F on the far side portion of the bubble.

According to the present embodiment described above, the circumferential distribution of the coagulation line heights can be automatically determined from the images of the coagulation lines F on the near side and the far side into which the bubble is shot.

Further, according to the present embodiment, only 1 image pickup device is required, and therefore, the cost can be relatively suppressed.

Further, according to the present embodiment, since it is not necessary to perform the process of discriminating the solidification line F between the near side portion and the far side portion of the bulb, the processing performance required in the control device 7 can be relatively reduced. Further, the circumferential distribution of the height of the solidification line can be determined in a relatively short time, and the cycle of repeating the determination of the circumferential distribution of the height of the solidification line can be relatively shortened.

As described above, according to embodiment 2, one aspect of the present invention is explained. Next, a modification of embodiment 2 will be described.

(modification of embodiment 2)

In the above embodiment, the case where the circumferential distribution of the solidification line heights is determined from the image taken from below the height of the solidification line F has been described, but the circumferential distribution of the solidification line heights may be determined from the image taken from above the height of the solidification line F.

At this time, the 1 st imaging device 26 is disposed above the height of the solidification line F.

However, even if the solidification line heights have a certain degree of distribution in the circumferential direction in the case of the stabilized molding state, if an image of the solidification line F is taken from a position above the height of the solidification line F to a certain degree, it is considered that, of the 2 lines of the detected solidification lines F extending substantially in the left and right directions in the image, the line located on the upper side in the image is the solidification line F at the back side portion of the bubble, and the line located on the lower side is the solidification line F at the near side portion of the bubble.

Therefore, the determination unit 52 of the present modification determines the circumferential distribution of the solidification line heights from the image, in which the line located on the upper side in the image is the solidification line F on the back side of the bubble and the line located on the lower side is the solidification line F on the near side of the bubble.

According to this modification, the same effects as those of the embodiment can be achieved.

(embodiment 3)

In the above-described embodiment and these modifications, the case where the circumferential distribution of the height of the solidification line is determined based on the image taken from below or above the height of the solidification line F has been described. In embodiment 3, a case will be described in which the circumferential distribution of the height of the coagulation line is determined from 2 images taken in the horizontal direction from substantially the same height as the coagulation line F. The following description focuses on differences from embodiment 1.

Fig. 8 shows a basic configuration of a blown film forming apparatus 1 according to embodiment 3. The blown film forming apparatus 1 includes a mold 2, a cooling device 3, a pair of stabilizing plates 4, a tractor 5, a thickness acquiring unit 6, a 1 st image pickup device 26, a 2 nd image pickup device 27, and a control device 7.

The 1 st and 2 nd imaging devices 26 and 27 are disposed so as to be oriented in the horizontal direction at the same height as the solidification line F. Specifically, the 1 st image pickup device 26 and the 2 nd image pickup device 27 are arranged such that the optical axes Ax (i.e., the optical axes of the lenses (not shown)) are oriented in the horizontal direction and pass between the maximum value Max and the minimum value Min of the coagulation line height. The 2 nd imaging device 27 is disposed at a position different from the 1 st imaging device 26 in the circumferential direction, for example, at a position spaced apart from the 1 st imaging device 26 by an interval of 90 ° in the circumferential direction.

The specifying unit 52 specifies the circumferential distribution of the height of the coagulation line from 2 images captured from the same height as the coagulation line F and 2 images captured in the horizontal direction from circumferentially different positions.

Fig. 9(a) and 9(b) are diagrams illustrating a method of determining the circumferential distribution of the solidification line heights by the determination unit 52. Fig. 9(a) is a 1 st image captured by the 1 st imaging device 26, and fig. 9(b) is a 2 nd image (captured from the D direction in fig. 9 (a)) captured by the 2 nd imaging device 27 arranged at a position spaced apart by 90 ° in the circumferential direction with respect to the 1 st imaging device 26.

The determination unit 52 determines whether the portion having a different solidification line height from the periphery or a portion distant from the ideal solidification line height in the 1 st image is the solidification line F of the near side portion or the solidification line F of the far side portion with reference to the 2 nd image.

The discrimination processing will be specifically described. In the 1 st image of fig. 9(a), in both side portions in the left-right direction, the coagulation line F in the near side portion of the bubble and the coagulation line F in the far side portion of the bubble both extend substantially horizontally and overlap each other. In the center portion in the left-right direction, one of the solidification line F of the near side portion of the bubble and the solidification line F of the far side portion of the bubble extends substantially horizontally, and the other thereof protrudes upward at a position above the solidification line F.

In the 2 nd image of fig. 9(b), in the central portion and the right portion in the left-right direction, the solidification line F in the near side portion of the bubble and the solidification line F in the far side portion of the bubble both extend substantially horizontally and overlap each other. In the left portion in the left-right direction, the solidification line F is located higher than the central portion or the right portion.

In the central portion in the left-right direction, referring to only the 1 st image in fig. 9(a), it is impossible to distinguish which of the solidification line F located on the upper side (protruding upward) and the solidification line F located on the lower side (extending substantially horizontally) is the solidification line on the near side portion of the bubble and which is the solidification line on the back side portion of the bubble.

Referring to fig. 2 (b) of fig. 9, it is seen that the solidification line F is higher in the left portion in the left-right direction, and the left portion corresponds to the solidification line F above the center portion in fig. 9 (a).

When the 2 nd image in fig. 9(b) is taken from the direction D in fig. 9(a), it can be seen that the upper side of the central portion in the left-right direction of the 1 st image in fig. 9(a) is the coagulation line F at the back side portion of the bubble and the lower side is the coagulation line F at the near side portion of the bubble.

In the discrimination, it is assumed that the horizontal cross section of the bulb is substantially circular.

Then, the specifying unit 52 specifies the circumferential distribution of the solidification line heights based on the discrimination result and the 1 st image.

According to the present embodiment, the same effects as those of embodiment 1 can be achieved.

As described above, according to embodiment 3, one aspect of the present invention is explained.

Next, a modified example will be described.

Although the circumferential distribution of the height of the coagulation line is determined from 1 set of the 1 st and 2 nd images in the 1 st and 3 rd embodiments and the modifications, the circumferential distribution of the height of the coagulation line may be determined from a plurality of sets of the 1 st and 2 nd images taken at different positions in the circumferential direction, for example, from 4 sets of the 1 st and 2 nd images taken at 90 ° intervals in the circumferential direction.

In this case, the coagulation lines F in the near portion and the far portion may be discriminated by the group, and the circumferential distribution of the coagulation line height may be determined from the discrimination results and the plurality of groups of discriminated images.

Further, the 1 st image pickup device 26 and the 2 nd image pickup device 27 may be moved in the circumferential direction to pick up a plurality of sets of the 1 st image and the 2 nd image, or a plurality of sets of the 1 st image pickup device 26 and the 2 nd image pickup device 27 may be set at different positions in the circumferential direction, and for example, 4 sets of the 1 st image pickup device 26 and the 2 nd image pickup device 27 may be provided at intervals of 90 ° in the circumferential direction.

Similarly, in embodiment 2 and its modification, the circumferential distribution of the height of the coagulation line is determined from the 1 st image, but may be determined from a plurality of 1 st images taken at different positions in the circumferential direction, for example, from a plurality of 1 st images taken at intervals of 90 ° in the circumferential direction.

The structure and operation of the blown film forming apparatus according to the embodiment are explained above. Those skilled in the art will appreciate that these embodiments are illustrative, various modifications can be made to the combination of these respective constituent elements, and such modifications are also within the scope of the present invention.