JPH0129138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air ring for forming a blown film, which is applied to an extruder for forming a cylindrical thin film from a thermoplastic resin.

[Conventional technology]

An object of the present invention is to form a cylindrical thin film from a thermoplastic resin such as polyethylene, polystyrene, polypropylene, polyamide, etc., and it is not easy to appropriately and effectively cool each part of the film.

[Purpose of the invention]

The present invention uses low density polyethylene (L-
The present invention aims to provide an air ring that can effectively and appropriately cool LDPE (LDPE) or the like during inflation molding to obtain a highly transparent cylindrical thin film.

For this purpose, according to the present invention, main and sub-slit forming bodies that can change the flow direction and amount of cooling air are provided in the vicinity of the slits from which cooling air is blown out before and after the frost line in the cylindrical thin film. An air ring equipped with the above is provided, thereby making it possible to increase the molding speed of the cylindrical thin film and increase the production amount.

[Structure of the invention]

The present invention is an air ring for inflation film molding, which cools the cylindrical thin film by blowing air out from a horizontal annular slit through which the cylindrical thin film extruded from a die passes. a hollow annular air ring body communicating with the air supply pipe; an annular main cooling slit connected to the air ring body and provided on the side of the cylindrical thin film immediately after exiting the die; a main cooling slit forming body provided at the outlet of the air ring for changing the gap at the outlet; and an annular slit forming body connected to the air ring body and opening toward the cylindrical thin film side at a location away from the die. It is equipped with a sub-cooling slit and a sub-cooling slit forming body provided at the outlet of the slit to change the gap between the slits, and by adjusting each slit forming body. The cooling air can be moved through the cooling retention area of the cylindrical thin film by changing the blowing direction and air volume of the cooling air. It consists of a casing and a movable casing, and the movable casing is rotatably supported by the fixed casing around the central axis of the air ring body, and the main cooling slit forming body is arranged along the traveling direction of the cylindrical thin film. It consists of a plurality of passage forming bodies movably arranged side by side, and a passage is formed with a gap between them, and the end of each of these passages is provided with a protrusion of a different shape. The cooling air is formed into a plurality of branch slits with different blowing directions, and by adjusting the interval between the passage forming bodies, the blowing direction and air volume of the cooling air from each branch slit can be changed. The slit forming body has a plurality of arc-shaped wind direction plates that are supported so as to be movable in the radial direction, arranged in the circumferential direction, and a ring in which the adjacent ends are overlapped, and a rotatable cover. The cover ring is supported by a slide rod that engages with an inclined cam groove in a cam plate provided on the annular body, and by rotating the cover ring, each wind direction plate is moved in the inner and outer directions through the cam groove and the slide rod. It is now possible to move it to

〔Example〕

Next, the present invention will be explained in detail based on the embodiments shown in FIGS. 1 to 7.

1 is a die, and an extruder 2 is connected to the lower end of the die.
The molten thermoplastic resin supplied from the thermoplastic resin is extruded upward from an annular lip 1a provided on the upper surface of the thermoplastic resin to form a cylindrical thin film bubble 3.

The die 1 is supported by a rotor 4 located below the die 1 so as to be rotatable around a vertical axis.

An annular air ring 6 is supported on the upper surface of an L-shaped support arm 5 protruding from the periphery of the upper surface of the die 1 .

As shown in FIG. 3, the air ring main body 7, which has a hollow annular passage 7a opening inward, has three casings: an annular movable lower casing 8 having an upward opening; It consists of an annular and fixed side casing 9 having an annular shape, and an upper casing 10 that covers the upper surface of the air ring body 7 on the inner side.

A ball bearing 11 is interposed between the upper end surface of the outer ring wall 8a of the lower casing 8 and the bottom wall 9a of the side casing 9, and the gap between the two is hermetically closed by a seal ring 12. has been done.

An annular wall 10a that projects outward is connected to the lower edge of the outer periphery of the upper casing 10.
The upper surface and the lower surface of the annular wall 9b hanging down from the inner end of the side casing 9 are slidably abutted, and the gap between them is hermetically closed by a seal ring 13.

An annular opening 14 facing inward is formed between the lower surface of the upper casing 10 and the upper end of the inner ring wall 8b of the lower casing 8. The annular wall 10a
A large number of holes 15 facing upward and downward are provided between the inner ring wall 8b and the inner ring wall 8b.
A rectifying ring 15 (see FIG. 7), which has holes a along the circumference, is inserted.

The upper casing 10 and the lower casing 8 are
They are connected with bolts 16.

The lower surface of the bottom plate of the lower casing 8 near the inner circumference is
It rides on the support arm 5 and is fixed with bolts 17.

A plurality of vertical supports 20 are fixed to the outside of the side casing 9, and a roller 19 is rotatably supported on the inside of the lower part of each support 20 with a horizontal shaft 18.

The lower surface of the lower casing 8 is rotatably supported by the plurality of rollers 19 .

A chain 21 is wound along the outer peripheral surface of the outer ring wall 8a of the lower casing 8. As a result, only the lower casing 8 can be rotated independently by removing the support arm 5 and meshing a sprocket (not shown) with the chain 21.

As shown in FIG. 2, a pair of air supply pipes 22 oriented in the tangential direction are provided at opposing portions of the outer peripheral surface of the side casing 9.
Cooling air is introduced into the chamber.

This cooling air flows from the air ring main body 7, ascends the above-mentioned rectifying ring body 15, is rectified, passes through the opening 14, and is further formed by two types of slit forming bodies, which will be described in detail later. The bubbles 3 are blown out from two slits in the lower and upper parts, one for main cooling and one for sub-cooling.

Reference numerals 23, 24, 25, and 26 shown in FIG. A main slit forming body 28 is formed, the inner part of which serves as the main cooling slit 27.

At the upper end of each of the passage forming bodies 23 to 26, outwardly facing horizontal flanges 23a, 24a, 25a, 26a are arranged in series, and the three passage forming bodies 23, 26 below are connected to each other.
A through hole 29 having a diameter larger than the diameter of the lip 1a of the die 1 is bored in the center of each bottom surface 23b, 24b, 25b of the die 1.

A through hole 30 having a slightly larger diameter than the through hole 29 is bored in the center of the bottom surface of the uppermost passage forming body 26 .

Each upper flange 23 of the passage forming bodies 23 to 26
Male threaded portion 23c cut into the outer peripheral surface of b to 26b
~26c, the inner ring wall 8b of the lower casing 8
By screwing into the internal threaded portion 8d cut into the inner circumferential surface of the passage forming bodies 23 to 26, the passage forming bodies 23 to 26 are rotatably overlapped with a gap between them. The above gaps are arranged in order from the bottom to the cooling air passage 3.
1, 32, 33.

At the outer edge of each collar 24a, 25a, 26a,
In order for cooling air to flow in from the opening 14,
Through holes 34, 35, and 36 are formed in the vertical direction, respectively.

Upward annular projections 24d and 25d for adjusting the width of the gap between the passages 32 and 33 are formed on the upper surfaces of the intermediate flanges 24a and 25a near the inner edges.

Next, the three branch slits constituting the main cooling slit 27 will be explained.

The lower end of the outer passage 31 forms a horizontal annular first branching slit 37 .

The lower end of the intermediate passage 32 is connected to an upward annular projection 24 formed on the inner edge of the bottom surface 24b of the passage forming body 24.
d, and a notch 25d provided on the lower inner edge of the bottom surface 25b of the passage forming body 25 and inclined inwardly and upwardly, forming an annular second branching slit 38 facing inwardly and upwardly.

The lower end of the inner passage 33 is connected to an annular projection 25e formed on the inner side of the upper surface of the bottom surface 25b of the passage forming body 25.
The lower edge of the passage forming body 26 forms a third branch slit 39 that faces inward and upward.

The main cooling slit 27 is formed by these branch slits 37, 38, and 39.

An annular protrusion 26e that protrudes upward along the peripheral wall 26d of the passage forming body 26 is formed on the inner edge of the uppermost flange 26a, and is fitted onto the inner end surface of the upper casing 10 so as to face the annular protrusion 26e. Between the annular wall 40a, which projects inwardly from the lower inner edge of the support ring 40, and the annular protrusion 26e,
A passage 41 having an inverted L-shaped cross section and communicating with the opening 14
is formed.

A sub-cooling slit 42 is provided at the upper end of the passage 41.
is formed.

A sub-cooling slit forming body 43 is attached to the upper surface of the support ring 40, which can change the direction of cooling air blown out from the slit 42. This will be explained based on FIGS. 4 to 6.

A plurality of square grooves 44 facing in the radial direction and having a rectangular shape when viewed from above are carved on the upper surface of the support ring 40, and each square groove 44 has an approximately L-shape with an outer end 45a facing upward. The horizontal portion of the slide rod 45 is slidably fitted therein.

On the upper surface of the inner end of the horizontal part of each slide rod 45,
A horizontal wind direction plate 46a having an arc shape and semicircular ends is fixedly attached thereto.

A roller 47 is pivotally attached to the upper end of the outer end 45a of the slide rod 45.

Reference numeral 48 denotes a ring-shaped cam plate, which has a width near its inner circumferential surface that can slidably and rotatably hold the roller 47, and has a predetermined angle with respect to the inner circumferential surface. Intersecting arc-shaped cam grooves 48a are cut.

This cam plate 48 is slidably mounted on the support ring 40.

As shown in FIG. 5, when the slide rod 45 is fitted into each square groove 44 and the roller 47 is fitted into each cam groove 48a, each wind direction plate 46a
Both ends thereof overlap with adjacent wind direction plates 46a to form a ring 46 as a whole.

49 is a cover ring whose downward U-shaped groove is fitted into the cam plate 48 from above, and between the lower surface near the inner peripheral wall and the upper surface of the support ring 40 near the inner peripheral wall. , an annular gap 50 is formed. Each wind direction plate 46 is taken in and out from this gap 50.

Four horizontal handles 51 are protruded from the outer peripheral surface of the cover ring 49, and the handles 51 allow the cam plate 48 to be rotated around a vertical axis via the cover ring 49. ing.

Next, the handling and operation of the air ring for blown film according to the present invention constructed as described above will be explained.

In order to disperse uneven thickness when forming bubble 3,
By rotor 4, via die 1 and arm 5,
Rotate the lower casing 8 of the air ring body 7.

A high-temperature, molten thermoplastic resin is extruded from the lip 1a of the die 1 and formed into a cylindrical thin film, that is, a bubble 3. At the same time, the bubble 3 is pushed upward by the cooling air blown into the inside from the die 1. As it progresses, the diameter is expanded and stretched.

On the other hand, on the outer surface of the bubble 3, the cooling air introduced into the air ring body 7 from the air supply pipe 22 is rectified while ascending the rectifying ring body 15, and after passing through the opening 14, a part of it is , upper passage 4
1, from the sub-cooling slit 42, the bubble 3
When I was about to go, I was blown out.

Most of the cooling air flows through the through holes 34, 35, 36.
descends, enters the passages 31, 32, 33, and enters each branch slit 3 constituting the main cooling slit 27.
By discharging from the lower end of 7, 38, 39,
The part of the bubble 3 closer to the die 1 is cooled.

When cooling the bubble 3, the direction of the cooling air blown out from the lower end of each branch slit 37, 38, 39 is different as shown by arrows a, b, and c.

The mutual spacing between the passage forming bodies 23, 24, 25, 26 can be adjusted by turning the threaded portions 23c, 24c, 25c clockwise or counterclockwise.

To increase the cooling effect at the bottom of the bubble 3, narrow the branch slit 37 and increase the wind pressure. Similarly, to increase the cooling effect at the upper part, narrow the branch slit 38 and increase the wind pressure. .

When the diameter of the die 1 is small, the distance between the main cooling slit 27 and the bubble 3 becomes large, but in this case, the wind pressure of the lower branch slit 37 is also increased to ensure that the air reaches effectively. do.

On the other hand, when the diameter of the die 1 is large, the distance between the main cooling slit 27 and the bubble 3 is small, so if high-speed air is blown directly from the slit 27, the bubble 3 will be dented, which is not favorable for molding. do not have.

In such a state, the wind pressure on the lower branch slit 37 is weakened and the upper branch slit 38 is
All you have to do is increase the wind pressure. Upper branch slit 3
Since the air outlet 8 is directed upward, the high-speed cooling air hits the bubble 3 obliquely and does not deform the bubble 3.

In this way, by appropriately combining the main cooling slits 27 having different angles, the cooling retention area of the bubble 3 can be freely selected.

Size of die 1, type of resin, or bubble 3
The cooling retention area varies depending on the wall thickness, etc., but in the case of a conventional single slit, the cooling retention area of the slit is limited. Therefore, it was necessary to replace the slit with a different inner diameter each time. However, according to the present invention, the slit can be adjusted freely.

The reason why the passage forming bodies 23 to 26 have an inverted truncated cone shape is to correspond to the shape of the bubble 3.

As a result, air passages with approximately constant intervals are formed between the bubble 3 and the passage forming body 26, and when the air blown out from the branch slits 37, 38, and 39 passes through these passages at high speed, a ventilating effect is produced. The generated unstable bubble 3 is sucked in the outer diameter direction,
Bubble 3 remains in a constant shape and does not shake.
Effectively shaped.

Therefore, wrinkles, sagging, uneven thickness, etc. caused by shaking are less likely to occur, and a high-quality product can be obtained.

Particularly when producing in large quantities, a large amount of cooling air is required, but if the wind pressure is increased, the bubbles 3 will deform or shake due to the wind pressure, making molding impossible.

However, according to the present invention, the more air is sent, the more the ventilly effect is enhanced and the stability of the bubble 3 is promoted. The reason why the outlet of the upper branching slit 39 is directed upward is to enhance this Ventury effect.

As shown in FIG. 4, in the sub-cooling slit forming body 43, the inner diameter of the ring 46 can be changed by rotating the handle 51 by a required angle.

At the position where the ring 46 protrudes most inwardly, the cooling air from the sub-cooling slit 42 hits the lower surface of the ring 46, as shown by arrow d.
The lower position of the bubble 3 on the frost line f is cooled.

Further, when the ring 46 is housed in the cover ring body 49, the cooling air from the sub-cooling slit 42 is blown upward as shown by the arrow e, and the bubble 3 is positioned above the frost line f. can be cooled. That is, by moving the slit molded body 43, the cooling retention area of the bubble 3 can be changed.

In the present invention, a slit forming body for main and sub-cooling that can change the gap between the openings is provided at the opening edge of the slit that blows out cooling air for cooling the bubbles, and the cooling retention area of the bubbles is moved. Change in diameter (blow-up ratio)
Accordingly, the molding speed can be increased by selecting the optimum cooling position over a corresponding range.

In the inflation molding of low-density polyethylene (L-LDPE), in order to increase the transparency of the cylindrical thin film, a very slight adjustment is required in the cooling position near the frost line, but the present invention According to Airing, this is also possible.

In addition, since the slits are provided at the top and bottom, the blowing direction of the cooling air can be adjusted in various ways, improving the air guide effect to eliminate bubble fluctuations, and by increasing the cooling effect during winding. The phenomenon of adhesion between thin films (blocking) is also reduced, and productivity can be increased.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment in which the present invention is applied to an extruder, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view of FIG. 4 is an enlarged vertical sectional view of the slit-forming ring body which is the main part of FIG. 3, and FIG.
6 is a partially cutaway plan view showing an enlarged view of the cam part which is the main part of FIG. 5, and FIG. FIG. 1...Die, 2...Extruder, 3...Bubble, 4
... Rotor, 5 ... Support arm, 6 ... Air ring, 7 ... Air ring body, 8 ... Lower casing, 9 ... Side casing, 10 ... Upper casing, 14 ... Opening, 15 ... Rectifier ring, 19...
...Roller, 22...Air supply pipe, 23, 24, 2
5, 26... Passage forming body, 27... Main cooling slit, 28... Sub-cooling slit forming body, 29,
30, 34, 35, 36...through hole, 31, 3
2, 33... Passage, 37, 38, 39... Branch slit, 42... Sub-cooling slit, 43... Sub-cooling slit forming body, 44... Square groove, 45...
Slide rod, 46...Ring, 46a...Wind direction plate, 47...Roller, 48...Cam plate, 49...
Cover ring body, 51...handle, 52...ring, 55...band plate, 56...throttle device, 57...
horizontal ring.

Claims (1)

[Scope of Claims] 1. Air for inflation film molding that cools a cylindrical thin film by blowing air out of a horizontal annular slit through which the cylindrical thin film extruded from a die passes. The ring includes a hollow annular air ring body communicating with an air supply pipe, and an annular main cooling slit connected to the air ring body and provided on the side of the cylindrical thin film immediately after coming out of the die. , a main cooling slit forming body provided at the outlet of the slit for changing the gap at the outlet; and a main cooling slit forming body provided at the outlet of the slit, and an opening on the cylindrical thin film side at a location connected to the air ring body and away from the die. An annular sub-cooling slit, and a sub-cooling slit forming body provided at the outlet of the slit for changing the gap between the exit parts, and by adjusting each slit forming body. , the cooling air from the slits can be moved through the cooling retention area of the cylindrical thin film by changing the blowing direction and air volume; The main cooling slit forming body is composed of a fixed casing and a movable casing, and the movable casing is supported by the fixed casing so as to be rotatable around the central axis of the air ring main body, and the main cooling slit forming body A passage is formed by a plurality of passage forming bodies arranged side by side so as to be movable along the direction, with gaps between them, and the ends of these passages are provided with protrusions of different shapes. The cooling air is formed into a plurality of branch slits with different blowing directions, and by adjusting the interval between the passage forming bodies, the blowing direction and air volume of the cooling air from each branch slit can be changed. The sub-cooling slit forming body has a plurality of arc-shaped wind direction plates supported so as to be movable in the radial direction, which are arranged in the circumferential direction, and the adjacent ends of which are stacked on top of each other make the ring rotatable. Each wind direction plate is supported by a slide rod engaged with an inclined cam groove in a cam plate provided on a cover annular body, and by rotating the cover annular body, each wind direction plate is moved through the cam groove and the slide rod. An air ring for inflation film molding, characterized in that it can be moved inward and outward.