JPH0631804A - System for regulating deviation of film thickness in inflation molding - Google Patents

Abstract

PURPOSE:To provide a system for regulating the deviation of film thickness which can regulate simply the deviation of film thickness in the process of inflation molding. CONSTITUTION:In the inflation molding of a cylindrical melt extruded from an inflation die to make a film, more than one blowhole is installed around the cylindrical melt. A blowing pass 4 is connected individually to each blowhole, and a blower 5 is attached to the blowing pass 4. An air-capacity regulator 6 which regulates the volume of air passing through each blowing pass 4 is also installed to regulate individually the volume of air ejected from each blowhole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an inflation molding apparatus for forming a film by melting, stretching and cooling a thermoplastic resin raw material in a series of steps.

[0002]

2. Description of the Related Art Inflation molding is suitable for film formation because it can melt, stretch and cool a thermoplastic resin material in a series of steps. In order to carry out this inflation molding, as shown in FIG.
Heating cylinder part that heats and melts thermoplastic material (21)
And a screw (2) for kneading the thermoplastic raw material in the heating cylinder part (21) and extruding the melt from the tip of the cylinder part.
2) and an extruder (20) consisting of a driving unit (23) for kneading and extruding this screw, and an inflation device for shaping the extruded melt connected to the downstream of the heating cylinder unit (21) into a tubular shape. A die (30), an air ring (41) connected to a blower means (40) for injecting air blown from the blower means around the tubular melt extruded from the inflation die (30), and the die. An inflation molding device (10) is generally used, which is provided above the and includes a pinch roller portion (60) for drawing a film molding (film tube) (50) stretched by jet air.

[0003]

In such inflation molding, since the tubular melt is required to be stretched into a film molding having a uniform thickness, the inflation die (30) usually has As shown in FIG. 6, a die gap (31) for extruding a cylindrical melt (see FIG. 3)
The uneven thickness adjusting bolt (32) for adjusting the uneven thickness is provided, and the uneven thickness is adjusted by adjusting the gap (31) with this bolt. However, this uneven thickness adjustment bolt (3
The clearance adjustment by 2) requires skill and is extremely difficult and complicated work.

An object of the present invention is to provide an uneven thickness adjusting system capable of easily adjusting uneven thickness in an inflation process.

[0005]

Thus, according to the invention of "Claim 1" of the present application, "inflation die"
(30) a plurality of blower openings (4a) that are individually opened around the cylindrical melt extruded from (30), and a blower flow path (4) that is individually connected to each blower opening (4a), and A blower means (5) for blowing air to the air flow passage (4), and an air flow rate adjusting means (6) capable of adjusting the amount of air flow flowing through each air flow passage (6). ) ”Is provided.

The inflation die (30) provided in the uneven thickness adjusting system (1) of the present invention and the film take-up means (60) for taking up the film molded article (50) after the inflation molding are known in the field of inflation molding. The thing is used as it is. Inflation Dice Above (30)
The one having the uneven thickness adjusting bolt (32) for adjusting the die gap (31) is preferably used as the above.

In the system (1) of the present invention, a plurality of blower ports (4a) are opened around the die gap (31) of the inflation die (30). In this case, it is preferable to arrange an air ring (3) provided with a plurality of blower openings (4a) around the inflation die (30). This air ring
It is preferable from the point of view of the operation for adjusting the uneven thickness that the plurality of air outlets (4a) opened in (3) are evenly provided on the circumference of the ring. Each of the above air blow ports (4a) has its own air flow path.
(4) is connected. A blower means (5) for generating air is provided in each of the air flow passages (4). As the blower means (5), those known in the art can be used as they are.

In the system of the present invention, the air blower means (2) is provided with air flow rate adjuster means (6) capable of arbitrarily adjusting the air blown amount flowing in each air blow passage. The air flow rate adjusting means (6) may be configured to change the flow path resistance by using a damper or the like, and the blower means (5) described above may be directly controlled, for example, via an inverter (6) or the like. Then, the amount of generated air may be adjusted. The latter is preferable because it is simple in structure and can be dealt with quickly.

As the uneven thickness adjusting system (1) of the present invention, as shown as the invention according to "Claim 2" of the present application, the temperature of air blowing is adjusted in each air flow passage (4) of the air blowing means (2). There may be mentioned a configuration including a temperature adjusting means (7) capable of controlling the temperature. An ordinary heater or the like can be used as the temperature adjusting means (7). In this case, as the heat source, a heat storage method using late-night power, a method using a chiller, a high-generator, or the like can be appropriately selected in the sense of suppressing running costs. It is preferable that the temperature adjusting means (7) is further provided with a temperature sensor so that the temperature of the heater can be controlled based on an output signal from the sensor. Examples of the sensor include a thermocouple.

[0010]

According to the invention of "Claim 1" of the present application, the tubular melt extruded from the inflation die (30) is extruded with its wall thickness slightly adjusted, and is extruded into a plurality of pieces arranged around it. It is expanded into a film by the air blown all at once from the blower port (4a), but from the blower port provided in the portion where the thickness of the extruded tubular melt is relatively thick at this time. Is injected with a large amount of air, and the expansion degree of each is adjusted by injecting with a small amount of air from the blower port arranged in a relatively thin portion, and as a result, The film molded product (50) having a substantially uniform thickness can be obtained.

According to the invention of "Claim 2" of the present application,
With respect to the cylindrical melt extruded from the inflation die (30), from each blow port (4a) arranged around it,
Since it is possible to blow out air with the air volume and temperature adjusted, the expansion degree from the melt to the film body can be adjusted over a wide range due to the synergistic effect of the temperature and air volume, and it can respond quickly to changes in the wall thickness of the cylindrical melt Then, the expansion degree can be adjusted appropriately.

[0012]

The present invention will be described in detail below with reference to the illustrated embodiments, but the present invention is not limited thereto. Example 1 FIG. 1 is a schematic view of a main part of an inflation molding apparatus equipped with an example of the uneven thickness adjusting system of the present invention. In the figure, an inflation molding device (11) is provided with an extruder (20) including a heating cylinder section (21), a screw (22) and a screw driving section (23), and a downstream section of the heating cylinder section (21). An inflation die (30) for shaping the melt that is connected and extruded into a tubular shape, and an uneven thickness adjusting system (1) for stretching the tubular melt extruded from the die (30) into a film molding (50). The pinch roller portion (60) provided above the die (30) for drawing the film molded product (50) stretched by hot air, and a winding portion (not shown) provided in the subsequent stage of the pinch roller portion (60) It is configured. In addition, (9) is a stabilizing rod.

As shown in FIG. 2, the uneven thickness adjusting system (1) comprises an air ring (3) provided on the outer periphery of the upper edge of the inflation die and a plurality of air rings (3) connected to the air ring (3). It is composed of a blower flow path (4), a blower means (5) provided in each blower flow path (4), and an inverter (6) for controlling the drive of each blower means (5).

As schematically shown in FIG. 3, one end of each of the air flow passages (4) is independently connected to the upper surface of the air ring (3) and has the same circumference of the upper surface of the air ring. Blowers (41) are formed by opening at upper and even positions around the die gap (31). In addition, each air flow path
The other end of (4) is connected to each blower means (5).

The inflation die (30) is similar to the conventional one, and as shown in FIG.
(32), which allows the die gap (31) to be adjusted.

The inflation molding apparatus (1
The operation of 1) will be explained. Pre-inflation dice (30)
The unevenness adjusting bolt (32) is used to adjust the die gap (31) to be substantially uniform. Further, in the uneven thickness adjustment system (1), each blower means (5) is driven so that the same amount of air is blown to each air flow passage (4).

Under the above settings, when the thermoplastic resin melt-kneaded in the heating cylinder portion (21) is extruded as a tubular melt from the inflation die (30) by the screw (22), the die (30 The cylindrical melt is immediately expanded and hardened into a film by the air jetted around (). And the obtained film molded product (50) is a pinch roller part (60)
Is taken over by.

By the way, the expanded film molding (50)
When there is a difference in wall thickness, for example, when the wall thickness on the A side in FIG. 3 is thicker than the wall thickness on the B side, the air blown from the blower port located on the A side is blown out. Increase the amount,
Alternatively, by reducing the amount of air blown from the blower port located on the B side, or by performing both of these, the A side has a higher degree of expansion than the B side, and the difference in wall thickness is adjusted accordingly. Become. The amount of jet air can be adjusted quickly by controlling the drive of each blower means (5) via each inverter (6).

Embodiment 2 FIG. 4 is different from FIG. 4 in that each air flow passage (4) constituting the uneven thickness adjustment system shown in FIG. 2 is provided with a temperature adjusting means (7) capable of adjusting the temperature of the air blow. , Unequal thickness adjustment system with similar configuration (2)
Is. Therefore, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

Each temperature adjusting means (7) is provided with a heater (not shown) provided in the air flow passage (4), a thermocouple (not shown) provided downstream of the heater, and an output signal from the thermocouple. It is composed of a temperature controller (not shown) capable of adjusting the temperature of the air. As a result, air having a desired temperature can be ejected from the blower port.

In the inflation molding apparatus in which the uneven thickness adjusting system (2) having the above-mentioned structure is replaced with the uneven thickness adjusting system (1) of the first embodiment, the air whose temperature is controlled individually from each blower port is used. As a result, the expansion degree can be adjusted over a wide range by the synergistic effect of the difference in the air volume of the jet air and the temperature difference against the uneven thickness of the tubular melt extruded from the inflation die (30). be able to.

[0022]

According to the present invention, it is possible to easily adjust the uneven thickness without requiring skill and to obtain a homogeneous film molded product. In addition, the uneven thickness adjustment can be performed quickly in parallel with the inflation molding operation. Further, adjustment is possible over a wide range of expansion degree.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of an inflation molding apparatus equipped with an example of an uneven thickness adjustment system of the present invention.

FIG. 2 is a schematic view of a main part for explaining the configuration of the uneven thickness adjustment system in FIG.

FIG. 3 is a schematic plan view of an essential part for explaining the relationship between the disposition state of air blow ports and the die gap.

FIG. 4 is a view corresponding to FIG. 2 of another example of the uneven thickness adjustment system of the present invention.

FIG. 5 is a schematic view of a main part of a conventional inflation molding apparatus.

FIG. 6 is an enlarged explanatory view of a main part of FIG.

[Explanation of symbols]

(1) (2) ... Thickness adjustment system (3) ... Air ring (4) ... Blower flow path (5) ... Blower means (6) ... Inverter (7) ... Temperature control means (10) (11) ... Inflation Molding device (21)… Heating cylinder part (22)… Screw (23)… Screw drive part (50)… Film molding (60)… Pinch roller part

Claims (2)

[Claims] 1. A plurality of air outlets that are individually opened around a cylindrical melt extruded from an inflation die, air passages that are individually connected to the respective air outlets, and air is blown to the air passages. The uneven thickness adjusting system for inflation molding, which comprises: a blower unit for controlling the air flow rate; and an air volume adjusting unit for adjusting the air flow rate flowing through each air flow passage. 2. The uneven thickness adjusting system for inflation molding according to claim 1, wherein each of the air flow passages is provided with temperature adjusting means capable of adjusting the temperature of the air blow.