JPH0948070A - Method for setting of initial forming condition in inflation film forming, and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply set initial forming conditions complying to a film to be formed. SOLUTION: Data on the density of a raw material and the amount of extruded raw material measured based on the arbitrary number of rotation of a screw 15 pertaining to the raw material, is obtained and a characteristic graph of the number of rotations of the screw and the amount of extruded raw material is prepared and stored in a first storage part 20. Further, the characteristic graph of the frequency of a blower 17 for a grade classification obtained based on an arbitrary thickness and a production grade is prepared and stored in a second storage part 21. At the time of the initial forming of an inflation film, data on the production grade, forming thickness and folding width is entered by an input part 22. In addition, a first calculation part 24 decides the production grade and the forming thickness, and seeks a logical take-in speed based on the grade classification, and the logical frequency of the blower 17 based on the characteristic graph. A second calculation part 24 seeks the logical extrusion amount of a raw material based on the logical transaction rate, width, thickness and density. Besides, the second calculation part 24 decides the logical number of rotations of a screw based on the characteristic graph.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for setting initial molding conditions in inflation film molding.

[0002]

2. Description of the Related Art There are a wide variety of products molded by inflation molding, including raw materials used, product thickness, product width,
An operator determines the initial molding conditions based on experience, taking into consideration various conditions such as product accuracy, various physical properties, and openability. Generally, a method of recording the molding condition for each product and setting each condition so as to reproduce it at the next molding is generally used. In the present applicant, when the molding thickness is determined irrespective of the folding width, it is empirically determined that the product of the thickness (μ) and the take-up speed (m / min) is about 800 to 1000. A predetermined molded product is obtained by initializing the speed, calculating the extrusion amount when the take-up speed is set, and molding.

[0003]

SUMMARY OF THE INVENTION The present invention introduces a new factor, that is, product type classification with thickness and production grade as parameters, based on the above-mentioned empirical rule, and obtains the basic data only once. If it is stored, it is possible to set the initial molding conditions and the apparatus for inflation film molding that can automatically calculate and set the initial molding conditions of various products by inputting desired parameters for each product. It is intended to be offered to the market.

[0004]

In order to solve the above-mentioned problems, a specific invention is to melt a synthetic resin, which is a raw material, by a screw rotating in a heating cylinder and push a tube rough film extruded from a molding die into a pinch roller. In the inflation film molding method, the density of the raw material is stored at least in advance, the extrusion rate of the raw material with respect to any rotation speed of the screw is measured, and a characteristic graph of the screw rotation speed and the extrusion material is created. Create a characteristic graph of the frequency of the external cooling device for the product category obtained from the arbitrary thickness and production grade during the inflation film test molding,
This is memorized, and after that, at the time of the initial formation of the inflation film, the production grade, thickness, and folding width are input as set values, and the product classification is determined based on the set production grade and thickness, and this determination is made. The theoretical take-off speed of the inflation film is calculated as the quotient of the product category divided by the thickness, and the theoretical frequency of the external cooling device of the inflation film is calculated from the stored characteristic graph corresponding to the determined product category. Initial molding in inflation film molding, characterized in that the theoretical raw material extrusion rate is obtained from the take-up speed, width, thickness, and density, and the theoretical screw rotational speed is obtained from the stored characteristic graph corresponding to the theoretical raw material extrusion rate obtained. This is a condition setting method.

In order to solve the above-mentioned problems, the related invention relates to an inflation film molding in which a synthetic resin as a raw material is melted by a screw rotating in a heating cylinder and a tube rough film extruded from a molding die is drawn by a pinch roller. In the apparatus, a) a first storage unit that measures a density of a raw material and an extrusion rate of the raw material with respect to an arbitrary rotation rate of the screw, creates a characteristic graph of the screw rotation rate and the extrusion rate, and stores the graph. b) A second storage unit that creates and stores a characteristic graph of the external cooling device for the product category obtained from the arbitrary thickness and production blade during the test forming of this inflation film. c) At the initial formation of the inflation film of the raw material. Input section for inputting production grade, thickness, and folding width as set values d) Enter The product category is determined based on the production grade and the thickness entered in the force section, and the theoretical take-up speed of the inflation film is calculated as the quotient obtained by dividing the determined product category by the thickness, and corresponding to the determined product category. A first calculation unit for obtaining the theoretical frequency of the external cooling device from the specific graph stored in the second storage unit e) The theoretical take-up speed obtained by the first calculation unit and the width input by the input unit , The theoretical raw material extrusion rate is calculated from the thickness and the density stored in the first storage section, and the theoretical screw rotation is calculated from the characteristic graph stored in the first storage section in accordance with the calculated theoretical raw material extrusion rate. Second to determine the number
The arithmetic unit of a) to e) is provided as a setting device for initial molding conditions in inflation film molding.

In order to solve the above problems, it is preferable in view of the quality of the molded product that the production grade in this method is a value in the range of 100% ± 100%.
Incidentally, the characteristic graph of the product classification and the theoretical frequency of the external cooling device, the characteristic graph of the screw rotation speed and the extrusion rate,
It is created for each type of raw material.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION This aspect is a typical embodiment of the invention described in claim 2. In FIG. 1, A is an inflation molding apparatus, and an extruder 10 in this molding apparatus A is connected to an annular die 11 which is a type of molding die for discharging molten resin into a cylindrical shape. A bubble cooling air ring 13 is provided in the vicinity of the annular discharge port 12 of the die 11. The air ring 13 is connected to the secondary side of the blower 17 of the external cooling device. A pair of pinch rollers 16 are provided above the guide plate 14 for stabilizing and folding the blown-up film having a desired diameter. Further, a synthetic resin as a raw material is melted by a screw 15 rotating in a heating cylinder of the extruder 10, and a tube rough film F extruded from an annular discharge port 12 of the die 11 is transferred to the pair of pinch rollers 1
Pick up at 6. Such an inflation molding apparatus A
Is provided with an initial molding condition setting device B. That is, the density of the raw material and the screw 1 relating to this raw material
5, the extrusion amount with respect to an arbitrary rotation number is measured, a characteristic graph of the screw rotation number and the extrusion amount is created, and the first storage unit 20 for storing the characteristic graph and an arbitrary thickness and production at the time of test molding of this inflation film are produced. A second storage unit 21 that creates a characteristic graph of the frequency of the blower 17 of the external cooling device with respect to the product classification obtained from the grade and stores the graph.
And are provided.

Further, an input section 22 for inputting a production grade, a thickness, and a folding width as set values at the time of initially forming an inflation film of a raw material, and a product type classification is determined based on the production grade and the thickness inputted by the input section 22. Then, the theoretical take-up speed of the inflation film F is obtained as the quotient obtained by dividing the determined product type division by the thickness, and the external cooling is performed from the characteristic graph stored in the second storage unit 21 corresponding to the determined product type division. First computing unit 23 for obtaining the theoretical frequency of the blower 17 with an inverter of the device
Then, the theoretical raw material extrusion rate was obtained from the take-up speed obtained by the first calculation section 23, the width and thickness input by the input section 22, and the density stored in the first storage section 20, and this was obtained. A second calculation unit 24 is provided for determining the theoretical screw rotation speed from the relevant data stored in the first storage unit 20 in correspondence with the theoretical raw material extrusion rate.

The operation of this mode will be described below as a typical embodiment of the method invention according to claims 1 and 3. The synthetic resin, which is a raw material, is melted by the screw 15 rotating in the heating cylinder, and the tubular film F extruded from the die 11 is taken by the pair of pinch rollers 16 to continuously form an inflation film before the first film is formed. In the storage unit 20, the density of the raw material and the extrusion amount of the raw material with respect to an arbitrary rotation speed of the screw 15 are measured, and a characteristic graph of the screw rotation speed and the extrusion quantity is created and stored. The second storage unit 2
In step 1, a characteristic graph of the frequency of the blower with an inverter 17 of the external cooling device with respect to the product category obtained from the arbitrary thickness and the production grade during the test molding of the inflation film F is created and stored.

After that, at the time of the initial formation of the inflation film, the production grade, the molding thickness, and the folding width are input as set values in the input section 22, the product classification is determined based on the production grade and the thickness, and the determined product is selected. The theoretical take-up speed of the inflation film is obtained as a quotient obtained by dividing the division by the thickness, and the theoretical frequency of the blower 17 with the inverter of the external cooling device of the inflation film is calculated from the stored characteristic graph corresponding to the determined product division. Is calculated by the first arithmetic unit 23. That is, the amount of cold air blown from the air ring 13 to the bubbles is determined according to the product category.

The theoretical raw material extrusion rate is obtained from the obtained theoretical take-off speed, width, thickness, and density by the second computing unit 24, and the theoretical screw rotation is calculated from the stored characteristic graph corresponding to the theoretical feed rate extrusion obtained. The number is determined by the second calculator 24. The determined operating speed of the screw and the frequency of the blower 17 with an inverter of the external cooling device are set in the standard operating condition setting unit 27 as required. At this time, the production grade is a value in the range of 100% ± 100%,
After setting the initial molding conditions in this way, using this set value as a reference value, the extrusion amount was measured by a known method,
The take-up speed of the pinch roller 16 is controlled based on this extrusion amount.

[0012]

【Example】

 Molding conditions Annular die diameter 100 mm Raw material used L-LDPE Its density 0.924 Extruder Screw diameter 50 mm

Example 1 1) When a thickness of 20 (μ), a folding width of 400 (mm) and a production grade of 80% are input, the initial molding conditions are a theoretical take-up speed of 35.0 m / min, a theoretical raw material extrusion rate of 31. 2k
g / H, theory of blower with inverter which is an external cooling device, frequency 37 Hz and theoretical screw rotation speed 69.
When the inflation film was set at 8 rpm and the subsequent continuous molding operation was performed, the molding was stable. 2) When a thickness of 20 (μ), a folding width of 400 (mm) and a production grade of 120% are entered, the initial molding conditions are a theoretical take-up speed of 55.0 m / min and a theoretical raw material extrusion rate of 48.6 k.
g / H, theoretical frequency of the blower with an inverter which is an external cooling device 50 Hz, and theoretical screw speed 108.7
When the inflation film was molded by the continuous molding operation after setting to rpm, the molding was a little unstable, and the uneven thickness accuracy and the folding width accuracy became poor.

Example 2 1) When the thickness is 50 (μ), the folding width is 400 (mm), and the production grade is 90%, the initial molding conditions are the theoretical take-up speed of 16.7 m / min and the theoretical raw material extrusion rate of 36.9 kg.
/ H, theoretical frequency 41Hz and theoretical screw rotation speed 82.6 rpm of the blower with an inverter which is an external cooling device
When the inflation film is molded by the continuous molding operation after that, molding is stable and blocking does not occur. 2) When the thickness is 50 (μ), the folding width is 400 (mm), and the production grade is 110%, the initial molding conditions are a theoretical take-up speed of 20.7 m / min and a theoretical extrusion rate of 45.8 kg /.
H, theoretical frequency of blower with inverter as external cooling device 48Hz and theoretical screw speed 102.5 rpm
When the inflation film was molded by the continuous molding operation after that, the molding was stable, but blocking occurred.

[0015]

According to the first aspect of the invention, the initial molding conditions can be easily set according to the film to be molded. In particular, the theoretical take-up speed can be set easily and the theoretical frequency of the external cooling device can be determined by dividing the product classification determined based on the production grade and the thickness without considering the folding width by the thickness.

In the invention described in claim 2, the invention described in claim 1 can be carried out, and the theoretical raw material extrusion rate is obtained from the theoretical take-off speed, width, thickness and density obtained from the product classification as described above, and this theoretical raw material extrusion is carried out. The theoretical screw speed corresponding to the quantity,
It can be appropriately determined from the characteristic graph stored in advance, and as a result, initial molding conditions in inflation film molding can be easily set without requiring skill,
It can contribute to stabilizing the quality of molded products during continuous operation.

According to the invention of claim 3, in addition to the effect of the invention of claim 1, since there is a range of production grades, it is possible to appropriately select the product type classification, and as a result, the theoretical frequency according to the molding is selected. In addition to being able to obtain the theoretical take-up speed, it is possible to obtain the theoretical take-up speed easily and rapidly, and the continuous operation of the inflation film can be carried out to form a molded article having no trouble. From the above examples, it was revealed that by appropriately selecting the production grade and setting the theoretical frequency, the tube film can be cooled with an appropriate amount of air and stably formed. Further, the theoretical take-up speed can be set as described above, and the theoretical take-up speed can be used as an initial condition to smoothly shift to the continuous forming of the inflation film, and the take-up control can be performed without bubble breakage.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of this molding apparatus.

[Explanation of symbols]

 20 1st memory | storage part 21 2nd memory | storage part 22 Input part 23 1st calculating part 24 2nd calculating part 27 Reference | standard operating condition setting part

Claims (3)

[Claims] 1. An inflation film molding method in which a synthetic resin as a raw material is melted by a screw rotating in a heating cylinder, and a tube rough film extruded from a molding die is pulled by a pinch roller, wherein at least the density of the raw material is stored in advance. Then, the extrusion rate of the raw material with respect to an arbitrary number of revolutions of the screw is measured, and a characteristic graph of the number of revolutions of the screw and the degree of extrusion is created, and the characteristic graph is stored. Create a frequency characteristic graph of the external cooling device for the obtained product category,
This is memorized, and thereafter, at the time of the initial formation of the inflation film, the production grade, the thickness, and the folding width are input as set values, and the product type classification is determined based on the set production grade and thickness, and this determination is made. The theoretical take-off speed of the inflation film is calculated as the quotient of the product category divided by the thickness, and the theoretical frequency of the external cooling device of the inflation film is calculated from the stored characteristic graph corresponding to the determined product category. Initial molding in inflation film molding, characterized in that the theoretical raw material extrusion rate is obtained from the take-up speed, width, thickness, and density, and the theoretical screw rotational speed is obtained from the stored characteristic graph corresponding to the theoretical raw material extrusion rate obtained. How to set the conditions. 2. An inflation film molding apparatus in which a synthetic resin as a raw material is melted by a screw rotating in a heating cylinder, and a tube rough film extruded from a molding die is pulled by a pinch roller, wherein a) the density of the raw material, and A first storage unit that measures the extrusion rate of the raw material with respect to an arbitrary rotation rate of the screw, creates a characteristic graph of the screw rotation rate and the extrusion rate and stores the characteristic graph, and b) optional during the test molding of the inflation film. The second storage section that creates and stores the characteristic graph of the external cooling device for the product category obtained from the product thickness and production grade. C) Raw material inflation film Set the production grade, thickness, and folding width during initial molding Input section d) Based on the production grade and thickness entered in this input section Then, the product type classification is determined, and the theoretical take-up speed of the inflation film is obtained as a quotient obtained by dividing the determined product type classification by the thickness, and from the specific graph stored in the second storage unit corresponding to the determined product type classification. A first arithmetic unit for obtaining the theoretical frequency of the external cooling device e) The theoretical take-up speed obtained by the first arithmetic unit, the width and the thickness input by the input unit, and the first storage unit The theoretical raw material extrusion rate is obtained from the density, and the theoretical screw rotational speed is determined from the characteristic graph stored in the first storage unit in accordance with the obtained theoretical raw material extrusion rate.
An arithmetic unit for setting initial molding conditions in inflation film molding, comprising: a) to e). 3. The method for setting initial molding conditions in inflation film molding according to claim 1, wherein the production grade has a value within a range of 100% ± 100%.