CN117507332A - Method for monitoring position of condensation line of film blowing bubble - Google Patents
Method for monitoring position of condensation line of film blowing bubble Download PDFInfo
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- CN117507332A CN117507332A CN202311530148.1A CN202311530148A CN117507332A CN 117507332 A CN117507332 A CN 117507332A CN 202311530148 A CN202311530148 A CN 202311530148A CN 117507332 A CN117507332 A CN 117507332A
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- Prior art keywords
- bubble
- cross bar
- horizontal cross
- condensation line
- condensation
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- 238000009833 condensation Methods 0.000 title claims abstract description 54
- 230000005494 condensation Effects 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000010096 film blowing Methods 0.000 title claims abstract description 10
- 238000012544 monitoring process Methods 0.000 title claims abstract description 9
- 238000001931 thermography Methods 0.000 claims abstract description 8
- 239000012528 membrane Substances 0.000 claims description 4
- 238000001125 extrusion Methods 0.000 description 11
- 238000001816 cooling Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000007664 blowing Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 239000002985 plastic film Substances 0.000 description 3
- 229920006255 plastic film Polymers 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- PCTMTFRHKVHKIS-BMFZQQSSSA-N (1s,3r,4e,6e,8e,10e,12e,14e,16e,18s,19r,20r,21s,25r,27r,30r,31r,33s,35r,37s,38r)-3-[(2r,3s,4s,5s,6r)-4-amino-3,5-dihydroxy-6-methyloxan-2-yl]oxy-19,25,27,30,31,33,35,37-octahydroxy-18,20,21-trimethyl-23-oxo-22,39-dioxabicyclo[33.3.1]nonatriaconta-4,6,8,10 Chemical compound C1C=C2C[C@@H](OS(O)(=O)=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@H]([C@H](C)CCCC(C)C)[C@@]1(C)CC2.O[C@H]1[C@@H](N)[C@H](O)[C@@H](C)O[C@H]1O[C@H]1/C=C/C=C/C=C/C=C/C=C/C=C/C=C/[C@H](C)[C@@H](O)[C@@H](C)[C@H](C)OC(=O)C[C@H](O)C[C@H](O)CC[C@@H](O)[C@H](O)C[C@H](O)C[C@](O)(C[C@H](O)[C@H]2C(O)=O)O[C@H]2C1 PCTMTFRHKVHKIS-BMFZQQSSSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012768 molten material Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/28—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of blown tubular films, e.g. by inflation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
- B29C2037/90—Measuring, controlling or regulating
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Radiation Pyrometers (AREA)
Abstract
A method for monitoring the position of a condensation line of a film blowing bubble comprises the following steps: (1) Carrying out thermal imaging photographing on the lower part of the film bubble by using an infrared thermal imager to obtain an infrared thermal imaging picture of the lower part of the film bubble and temperature values of pixel points in the picture; (2) Estimating the vertical range of the bubble condensation line according to the picture; (3) Dividing the estimated vertical range into a plurality of horizontal cross bar areas from bottom to top, wherein the vertical sizes of the horizontal cross bar areas are the same; (4) Calculating the average temperature value of all pixel points of each horizontal cross bar area; (5) Calculating the difference value of the average temperature values of every two upper and lower adjacent horizontal cross bar areas; (6) And finding out two upper and lower adjacent horizontal cross bar areas with the largest difference, and determining the bubble position corresponding to the horizontal boundary line of the two horizontal cross bar areas as a bubble condensation line. The invention can accurately determine the vertical position of the condensation line.
Description
Technical Field
The invention belongs to the technical field of plastic film processing, and particularly relates to a method for monitoring the position of a condensation line of a film blowing bubble.
Background
The plastic film may be produced by a plastic film blowing apparatus. As shown in fig. 1, the film blowing device comprises an extrusion die head 1, wherein the extrusion die head 1 is provided with a circular ring-shaped extrusion port 10, a cooling air ring 11 is arranged above the extrusion die head 1, the extrusion die head 1 is also provided with an air inlet pipeline 12 and an air outlet pipeline 13 in a matching way, the air inlet pipeline 12 is connected with a blower 14, the air outlet pipeline is connected with an exhaust fan 15, and an inner end 120 of the air inlet pipeline and an inner end 130 of the air outlet pipeline are respectively opened in the central area of the upper surface of the extrusion die head 1. In production, molten plastic materials are extruded from a circular extrusion port 10 of an extrusion die head 1 to form a circular film bubble 8 and move upwards, the film bubble 8 is cooled by cold air blown out from an air outlet of a cooling air ring 11 in the operation process and gradually cooled, when the operation reaches a certain vertical position, the temperature of the film bubble 8 is reduced to a certain temperature point (the solidifying point temperature of the plastic materials fluctuates along with different factors such as proportion and materials), and plastics with various proportions have no standard uniform solidifying point temperature value) to be condensed and crystallized, and the vertical position is called a condensation line (the position is shown by a dotted line RS in fig. 1). In the above process, the air blower 14 is filled with compressed air with a certain pressure into the bubble 8 through the air inlet pipe 12, and the bubble 8 below the condensation line is inflated under the action of the compressed air because the bubble is not yet condensed, so that the diameter of the bubble 8 is gradually increased, and the section of the bubble between the annular extrusion port 10 and the condensation line is called an inflation section (e.g., RM/SN section in fig. 1). After the film bubble 8 passes the condensation line, it is no longer possible to blow up sharply to a large extent due to condensation, and it is seen that the final shaping effect of the film bubble is mainly dependent on the stage of the blowing section before condensation, and therefore the determination of the vertical position of the condensation line is important. The vertical position of the condensation line corresponds to the time of the blowing process, so that the film thickness and the film bubble diameter are directly determined, and the temperature of the cooling air ring air flow, the pressure of the blowing air flow, the extrusion speed of the molten material, the extrusion quantity and other process control parameters are inversely determined. For example, if the condensation line is lower, it means that the bubble is condensed earlier, the cooling speed is faster, and the bubble is not fully inflated, at this time, a regulation and control measure should be taken, for example, the temperature of the cooling air flow blown out by the cooling air ring is increased, so as to prolong the condensation time of the bubble, or other regulation and compensation measures are also taken, which needs to be comprehensively considered according to the production process.
In the prior art, the position of a condensation line of a film bubble is mainly judged by visual inspection and experience of workers and regulated and controlled according to the position, and the judgment process is relatively coarse, so that the condensation speed (i.e. the condensation process) of the film bubble is not controlled finely enough, and the control automation degree is low, namely the position of the condensation line of the film bubble cannot be converted into electronic data. In order to solve the above problems, the applicant has tried to use a technical solution for measuring the diameter of the bubble and thus determining the vertical position of the condensation line, which defines the vertical position of the condensation line according to the following rules: the bubble horizontal width at the condensation line is greater than the bubble horizontal width at each horizontal section below it and equal to the bubble horizontal width at each horizontal section above it. The theoretical basis of the technical scheme is that; after passing the condensation line, the bubble can no longer be inflated, i.e. the diameter no longer changes, due to condensation. However, in practice, the applicant has found that after passing the condensation line, the bubble is no longer able to be inflated due to condensation, but can also undergo elastic stretching under the pressure of the air flow (elastic stretching corresponds to stretching by force, which stretching is recoverable and inflation by condensation is not recoverable), and in addition, during upward operation of the bubble, the bubble can undergo horizontal rocking and is not very standard circular but is an ellipse approximating a circle due to the influence of the air flow inside and outside, and the ellipse varies in its long and short directions with time, which influences the measurement result of the width (diameter) of the bubble. Since the above-mentioned technical solutions, both theoretically and practically, are to be improved, the result of determining the vertical position of the condensation line by means of measuring the bubble diameter is sometimes not accurate enough.
In addition, in chinese patent document CN103171122a, a condensation line stabilizing device is disclosed, which attempts to detect a change in the position of the condensation line using a first sensor and a second sensor, but this technical solution is obviously not mature and concrete, and thus the detection result cannot be accurate.
Disclosure of Invention
The invention aims to overcome the defects and provide a method for monitoring the position of a condensation line of a film blowing bubble, which can accurately determine the vertical position of the condensation line.
The aim can be achieved according to the following scheme: a method for monitoring the position of a condensation line of a film blowing bubble comprises the following steps:
(1) Carrying out thermal imaging photographing on the lower part of the film bubble by using an infrared thermal imager to obtain an infrared thermal imaging picture of the lower part of the film bubble and temperature values of pixel points in the picture;
(2) Estimating the vertical range of the bubble condensation line according to the picture;
(3) Dividing the estimated vertical range into a plurality of horizontal cross bar areas from bottom to top, wherein the vertical sizes of the horizontal cross bar areas are the same, and the actual vertical size of the membrane bubble corresponding to the vertical size of the horizontal cross bar area is 0.5-2 cm;
(4) Calculating the average temperature value of all pixel points of each horizontal cross bar area;
(5) Calculating the difference value of the average temperature values of every two upper and lower adjacent horizontal cross bar areas;
(6) And finding out two upper and lower adjacent horizontal cross bar areas with the largest difference, and determining the bubble position corresponding to the horizontal boundary line of the two horizontal cross bar areas as a bubble condensation line.
Preferably, the actual vertical dimension of the membrane bubble corresponding to the vertical dimension of the horizontal cross bar area is 0.8-1.2 cm.
The invention has the following advantages and effects:
according to the invention, the vertical position of the condensation line can be determined according to the difference value of the average temperatures of every two upper and lower adjacent horizontal cross bar areas, which is mainly due to two factors: the factor of the first aspect is that the temperature of the bubble is lower and lower during the rising process; the factor of the second aspect is that when the bubble reaches the condensation point, it will release heat for a short period of time, and after passing the condensation point, it will not release heat. Therefore, the difference value of the average temperatures of the upper and lower adjacent horizontal cross bar areas of the condensation line is larger than that of other areas, and the temperature suddenly changes, so that the vertical position of the condensation line is automatically and accurately monitored and determined. Furthermore, the data of the vertical position of the condensation line can be transmitted to a production control center, and the production control center can automatically control other process parameters according to the data of the vertical position of the condensation line, so that automatic control is realized, and the dependence on manual control is reduced.
Drawings
Fig. 1 is a schematic diagram of a bubble production process.
FIG. 2 is a schematic diagram of the result of step (1) according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of the result of step (2) according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of the result of step (3) according to an embodiment of the present invention.
Detailed Description
A method for monitoring the position of a condensation line of a film blowing bubble comprises the following steps:
(1) Carrying out thermal imaging photographing on the lower part of the film bubble by using an infrared thermal imager to obtain an infrared thermal imaging picture of the lower part of the film bubble and temperature values of all pixel points in the picture, as shown in fig. 2 (a photographing range which is a range surrounded by an ABCD in fig. 2);
(2) According to the picture of fig. 2, the vertical range where the bubble condensation line is estimated to be between the EF line and the GH line is shown in fig. 3;
(3) Dividing the estimated vertical range from bottom to top into a plurality of horizontal bar areas 80, wherein the vertical dimensions of each horizontal bar area 80 are the same (which means that the number of pixels in each horizontal bar area is the same), and the actual vertical dimension of the bubble corresponding to the vertical dimension of the horizontal bar area 80 is 1.0 cm, as shown in fig. 4;
(4) Calculating the temperature average value of all pixel points of each horizontal bar area 80;
(5) Calculating the difference of the average temperatures of every two upper and lower adjacent horizontal bar areas 80;
(6) The two adjacent horizontal cross bar areas 80 with the largest difference are found out, and the bubble position corresponding to the horizontal boundary line of the two horizontal cross bar areas is determined as a bubble condensation line.
In the above embodiments, the actual vertical dimension of the bubble corresponding to the vertical dimension of each horizontal rail region 80 may instead be 1.2 cm, or 0.8 cm, or 0.5 cm, or 2 cm, etc.
Because bubble condensation must occur in the lower portion of the bubble, and is unlikely to occur in the upper middle portion of the bubble, only the lower portion of the bubble need be thermally imaged, and the upper middle portion of the bubble need not be thermally imaged. As to how the lower portion of the bubble is defined and distinguished from the middle portion of the bubble, the person skilled in the art can fully define and distinguish from each other empirically, so long as the condensing line is ensured to be located in the photographing range. Similarly, a person skilled in the art can completely estimate the vertical range in which the bubble condensation line is located, and only needs to ensure that the condensation line is located in the estimated vertical range according to experience.
Claims (2)
1. A method for monitoring the position of a condensation line of a film blowing bubble comprises the following steps:
(1) Carrying out thermal imaging photographing on the lower part of the film bubble by using an infrared thermal imager to obtain an infrared thermal imaging picture of the lower part of the film bubble and temperature values of pixel points in the picture;
(2) Estimating the vertical range of the bubble condensation line according to the picture;
(3) Dividing the estimated vertical range into a plurality of horizontal cross bar areas from bottom to top, wherein the vertical sizes of the horizontal cross bar areas are the same, and the actual vertical size of the membrane bubble corresponding to the vertical size of the horizontal cross bar area is 0.5-2 cm;
(4) Calculating the average temperature value of all pixel points of each horizontal cross bar area;
(5) Calculating the difference value of the average temperature values of every two upper and lower adjacent horizontal cross bar areas;
(6) And finding out two upper and lower adjacent horizontal cross bar areas with the largest difference, and determining the bubble position corresponding to the horizontal boundary line of the two horizontal cross bar areas as a bubble condensation line.
2. The blown film bubble condensation line position monitoring method according to claim 1, wherein: the actual vertical size of the membrane bubble corresponding to the vertical size of the horizontal cross bar area is 0.8-1.2 cm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311530148.1A CN117507332A (en) | 2023-11-16 | 2023-11-16 | Method for monitoring position of condensation line of film blowing bubble |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311530148.1A CN117507332A (en) | 2023-11-16 | 2023-11-16 | Method for monitoring position of condensation line of film blowing bubble |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117507332A true CN117507332A (en) | 2024-02-06 |
Family
ID=89760306
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311530148.1A Pending CN117507332A (en) | 2023-11-16 | 2023-11-16 | Method for monitoring position of condensation line of film blowing bubble |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117507332A (en) |
-
2023
- 2023-11-16 CN CN202311530148.1A patent/CN117507332A/en active Pending
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