JPH0573573B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a device for forming a strip such as a film forming machine or a sheet forming machine. The present invention relates to a molding device for increasing the quality of the product.

(Prior Art) Conventionally, when a molten film 4 is cast from a T-die onto a cooling roll 11 to form a film or a sheet (hereinafter simply referred to as a film), generally in order to improve the adhesion between the film and the roll, etc. ,
A method has been used in which an air knife 100 or an air chamber 101 having a structure as shown in FIGS. 2 and 3 is used to press the molten film against a cooling roll using air pressure.

The air knife 100 has a cross section as shown in FIG.
The air guided by the film is rectified, flowed out uniformly in the width direction from the lip 8 at the tip, and collided with the film 4 surface. The collided air is separated into the upper and lower parts of the collision surface and flows out in the directions of arrows A and B, and the film is suppressed by the total pressure of the air flow at the collision point. In addition, when using the air chamber 101, its structure has a cross section as shown in FIG. The film 4 is held down by the static pressure inside. The blown air is divided into upper and lower parts and discharged in the directions of arrows A and B through the gap between the chamber and the roll, similar to the case of an air knife.

(Problem to be solved by the invention) By the way, the method using air pressure is a useful method because it can be applied regardless of the type of resin.
If you try to increase the molding speed to increase the production efficiency of the molding machine, you will have to increase the presser foot pressure to prevent air from getting caught between the film and the roll. As the amount of air leakage increases, vibrations of the molten film,
Molding is forced to deteriorate due to cooling of the die, etc.
Molding could not be performed above a certain speed. Also, by reducing the blowing angle θ with an air knife, the upward blowing air can be reduced, but the film holding pressure will also decrease, so the blowing angle is normally set to θ=
It is said to be about 60°, and the air knife has an air volume of
Performance changes greatly due to subtle differences in spray angle and position, making operational adjustments difficult.

The present invention is an attempt to solve the problem that conventional devices of this type cannot increase the molding speed, and if the molding speed is increased, the molding deteriorates.

(Means for Solving the Problems) Therefore, the present invention provides a film that is extruded from a die and runs in close contact with a cooling roll, a pressure chamber that is open to the sheet surface, and into which air is blown from a blower. A chamber is connected to the lower part of the pressure chamber via a partition wall, is open to the film and sheet surface, and is connected to an exhaust pipe via a pressure adjustment valve, and is wound around the cooling roll. The blowing angle of the pressure chamber opening with respect to the film and sheet surface, which blows the air jet as a downward flow toward the film and sheet surface, is set to an acute angle that is much smaller than 60°, and the downward flow is directed to the lower part of the film and sheet. It is designed to be blown into the chamber, and is used as a means to solve problems.

(Function) The blowing angle of the pressure chamber opening with respect to the film and sheet surface, which blows a downward flow of air onto the film and sheet surface wound around the cooling roll, is set to an acute angle that is much smaller than 60°! Since a chamber whose internal pressure can be adjusted is arranged below the chamber, the air jet ejected in the form of a sheet flows along the film surface in the film running direction, and then flows into the chamber. The pressure within the chamber is maintained at a desired high pressure by appropriate means, and the pressure within the chamber strongly presses the film against the chill roll surface.

Excess air within the chamber flows downward along the film surface and is actively exhausted from the chamber by appropriate means. As a result, the airflow along the film surface does not flow upstream in the film running direction.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Fig. 1 shows an example of the present invention, and 1 is a flow rate adjustment valve provided in the middle of a main pipe. It is connected to a blower (not shown), and its tip extends into a pressure chamber 6 of a film pressing device to be described later. 4 is a film in which the resin melted from the T-die 10 is cast onto the cooling roll surface to become a molten film, which is then cooled. The above is the same or equivalent to the conventional example shown in FIGS. 2 and 3, and the difference from the conventional example of the present invention lies in the film pressing device.

The film pressing device is formed into a box shape as a whole,
Its side cross section is approximately Y-shaped. That is, in FIG. 1, the chamber having a Y-shaped side cross section is separated into two upper and lower chambers, with the upper chamber forming the pressure chamber 6 and the lower chamber forming the chamber 5a.
The pressure chamber 6 has a cross-sectional shape similar to that of the conventional air knife shown in FIG.
The angle is much smaller than the normal blowout angle of 60° with respect to the surface, and the downward flow is directed to the lower chamber 5.
It is formed so as to be blown into a. The tip of the main pipe connected to the above-mentioned blower extends from the rear wall of the pressure chamber 6 into the interior thereof, and a chamber internal pressure regulating valve 9 is provided on the rear wall of the chamber 5a.
An exhaust pipe connected to the outside of the aircraft is communicated through the exhaust pipe.

A film pressing device having the above configuration is placed close to the four sides of the film along the cooling roll 11,
When the film is formed, air supplied from the blower is guided to the pressure chamber 6 through the flow rate adjustment valve 1. In the pressure chamber 6, after the flow is rectified and becomes almost uniform in the width direction, the flow is made at an acute angle to the film surface 4.
The air is blown downward from the air outlet 7 that opens toward the chamber 5a, and enters the chamber 5a. Since the air that rushes into the chamber flows downward, the air flow that tries to blow up from inside the chamber toward the T-die 10 side is blocked, and at the same time, the pressure is recovered in the pressure recovery section 8a and the internal pressure inside the chamber 5a is reduced. is set to a desired constant pressure, strong air pressure is applied to the film surface, and the film 4 is brought into close contact with the cooling roll 11. Excess air in the chamber 5a is discharged through the lower gap of the film pressing device and the chamber internal pressure regulating valve 9.

(Effects of the Invention) As described above in detail, in the present invention, the air jet is blown in a downward flow onto the film or sheet surface wound around a cooling roll, and the blowing angle of the opening of the pressure chamber with respect to the film or sheet surface is adjusted. ,60°
Because the angle is much smaller than the acute angle, the air jet ejected in the form of a sheet flows along the film surface in the film running direction without any turning points (points of collision of the air jet with the film surface), and the air jet flows inside the chamber. flows into. Therefore, a part of the air jet blown out from the pressure chamber does not blow up toward the die, so it is possible to prevent the molten film from vibrating or from deteriorating the forming due to cooling of the die, etc. It is something to play.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a film pressing section of a film forming machine showing an embodiment of the present invention, FIG. 2 is a side sectional view of a film pressing section when a conventional air knife is applied, and FIG. FIG. 3 is a side sectional view of a film pressing section when an air chamber is applied. Explanation of the main parts of the diagram, 1...Flow rate adjustment valve,
4... Film, 5a... Chamber, 6... Pressure chamber, 7... Air outlet, 9... Chamber internal pressure adjustment valve, 11... Cooling roll.

Claims (1)

[Claims] 1. A film extruded from a die and running in close contact with a cooling roll, a pressure chamber that opens to the sheet surface and into which air is blown from a blower, and is connected to the lower part of the pressure chamber via a partition wall, a chamber that is open to the film and seat surface and communicated with an exhaust pipe via a pressure regulating valve;
The blowing angle of the pressure chamber opening with respect to the film and sheet surface, which blows a downward flow of air onto the film and sheet surface wound on the cooling roll, is an acute angle that is much smaller than 60°, A film or sheet forming apparatus characterized in that the downward flow is blown into the lower chamber.