JPS60201926A - Method and apparatus for molding inflation film - Google Patents

Abstract

PURPOSE:To manufacture a homogeneous film extending over the whole circumference by forming a heat-insulating zone between the position of a stream slightly upper than a frost line and size approximately corresponding to the diameter of a bubble and passing the film through the heat-insulating zone in the manufacture of a synthetic-resin flat tube. CONSTITUTION:A tubular bubble is extruded from an annular discharae port for a die 10, and the bubble is expanded to a larger diameter in succession by cold air from a blow-off port 20 for an air-cooling device 18 and each bubble guide cylinder 19a-19c section, and folded and wound flatly by a pair of folding guide plates 13. The length of several tension member 15 is determined so that the lower edge of a heat-insulating zone 14 is positioned at the position of the stream side slightly upper than a frost line L in the bubble 12 at that time, the heat-insulating zone 14 is wound in the circumferential direction of the bubble 12, and connected by a fastener so that the inner diameter of the surrounding heat-insulating zone 14 coincides with the diameter of the bubble, and vibrations are prevented by a holding plate 23. Accordingly, temperature strain is eliminated, a homogeneous film extending over the whole circumference is obtained, and creases are not also generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a method and apparatus for producing flat tubes for synthetic shelves by an inflation method.

[Prior art]

Conventional methods for manufacturing flat tubes using this type of inflation method generally involve installing an air cooling device (nearing) equipped with an annular outlet in one or two stages on the outside of the bubble discharged from the annular opening of the die. is special public service 1977-1
5225 and JP-A-54-150473, which are also outside the puzzle.

On the other hand, models with multi-stage cold air outlets, such as the one known by Konera, have been widely used in recent years due to their good ability to cool bubbles. Thermal distortion of the puzzle may cause internal distortion, or small wrinkles may occur in the film when folded into a 1M flat shape due to bubble photography, or distortion may occur during storage after being folded flat.

In particular, when the blowing ratio of the bubble is increased, it becomes noticeable around this time, so the blowing ratio is said to be limited to about 4 times at most, and the ones on the market are usually up to about 2 times.
be.

As a result of extensive research, the inventor found that while expanding the puzzle to the desired diameter, rapid cooling is required to improve productivity and to prevent the bubbles from relaxing. It was found that better results could be obtained by delaying the cooling rate.

〔the purpose〕

This method invention insulates a predetermined zone of bubbles from the outside air from the 70th line upstream of the bubble expanded to a predetermined size, thereby delaying the rapid cooling of the bubbles, preventing uneven cooling of single bubbles, and This is a method for producing films with less wall thickness, small wrinkles, and other distortions, and is a method for forming raw material into a film using an inflation method.

Also, in device inventions, simple devices are used.

This method is intended to enable the above-mentioned method invention to be carried out, to stably support bubbles, and to enable one device to be used for changing molding dimensions. It is molded into a film.

[Consolidation]

In this invention, the buzzle, which has been inflated to a predetermined diameter, is placed slightly upstream of the frost line so that the puzzle diameter is 0.
This is a blown film forming method characterized by forming the film by passing it through a heat-retaining zone having a width of 5 to 1.5 times and shielded from outside air.

Further, another invention has a length sufficient to wrap at least once around the entire outer circumference of a bubble expanded to a predetermined diameter,
In the flow direction of the bubbles, a retaining band having a width equivalent to the diameter of the buckwheat pull is attached to the machine frame of the film forming apparatus or a part of the immovable part fixed thereto by a locking means that prevents the bubbles from moving in the flow direction. A blown film forming apparatus is characterized in that it is connected to a blown film forming apparatus.

The present invention will now be described based on representative embodiments of the device invention.

In the figure, 10 is a die, 11 is an annular resin discharge port, and 12 is a bubble discharged from this.

After expansion molding to a predetermined diameter, it is folded flat by a pair of folding guide plates 16, and then rolled into a winding device (
(not shown).

Reference numeral 14 denotes a heat-retaining band, which is usually made of a thick woven fabric made of vegetable fibers, and its length is long enough to wrap around the bubble 12 after expansion. The 70 convergence, that is, the dimension l of the puzzle in the running direction is about 0.5 to 1.5 times the diameter of the puzzle 12, preferably 0.5 to 1.0 times. The heat-retaining belt 14 has good heat retention and heat resistance, and is made of natural plants such as 1g of cotton cloth, if! : Not limited to
It may be mineral fiber, a blend of these or a mixed product, and it does not necessarily have to be paper cloth (even non-woven fabric or knitted fabric), which fall within the scope of the heat-retaining belt 14 of the present invention.

The lower edge of the heat-insulating zone 14 is provided with several tension members (usually plant s! male cords) 15 at several places.
Air cooling device 18 provided around the discharge port 110 or cylindrical puzzle guide tubes 19a and 19b provided integrally therewith.
and moored to one of 19C. The heat insulation zone 1
4 should be attached with a velpet-type fastener 17 inside its outer end 16 to prevent it from unraveling after being wrapped around the bubble 12 (see Figure 6).In the example shown, is the outer side of the heat insulation zone 14 in the circumferential direction of the bubble K t
It is supported by a holding member consisting of several bent holding plates 26.

In addition, the bubble guide cylinder has five concentric circles.
The outermost one is taller, and the outermost one 190 is the frost line L of the bubble 12.
It has an inner diameter of about 1.5 to 2 times the maximum diameter of the bubble 12, and the lower part of the outermost guide tube 19c has a large diameter 24 bulging outward. Between each of the bubble guide tubes 19a, 19b, and 19C, the innermost puzzle guide tube 19a, and the outer lip 21 of the air outlet 20 of the air cooling device 18, there are individual bubble guide tubes that are shielded from the outside air except for their upper ends. Independent pressure adjustment chambers 22a, 22
b and 22C are formed.

Also, the tension member 15 is attached to the upper end 4/c1/l of the middle puzzle guide tube 19b among the 6x bubble guide tubes.
It is a retainer.

In the above example, as the device for locking the heat insulation band 14, both the anchoring by the tension member 15 and the holding by the holding member 26 were shown, but it is also possible to use only one device, or the pair of folding guide plates 16 described above may be used. In this invention, even if the heat insulating band 14 is simply engaged with the heat insulating band 14, it is considered as a heat insulating band locking device.

[Embodiment of the method invention and operation of the device] First, a tube-shaped puzzle is extruded from the annular outlet of the die 10, and the blowing air from the outlet 20 of the air cooling device 18 and each puzzle guide tube 19a are extruded.
, 19b and 19C to successively expand the bubble to a larger diameter, and the expanded bubble to a predetermined size is folded flat by a pair of folding guide plates 16 and wound up.

In this case, in the method of this invention, 70 of the bubbles 12
The length of each tension member 15 is determined so that the lower edge of the insulation band 14 is positioned slightly upstream of the line L, and the insulation band 14 is wrapped in the circular shaving direction of the chisel pull 12 to create a surrounding heat insulation. The inner diameter of the band 14 matches the diameter of the puzzle to be formed, and in the example shown in FIG.

As shown in Figures 1 and 2, the holding plate 26 of the locking device is brought into contact with the outside of the heat-insulating belt 14 to prevent the puzzle and the heat-insulating belt 14 from vibrating back and forth and from side to side. .

When the blown film is formed in this manner, the puzzle 12 expands to a predetermined size.

Immediately before reaching the 70th line IK, the wind blown from the outlet 20 flows along the surface of the bubble 12 in a laminar flow, but after that, the bubble 12 flows into the heat insulation zone 14 and mixes with the evaporated outside air. Since the bubble 12 passes through the insulation zone, which is blocked off, the cooling rate is moderated during this section, and the frost line is essentially higher than that without the insulation zone, and the bubble 12 that has passed through the insulation zone afterward is It is cooled by the outside air and folded by the folding guide plate 13.

〔effect〕

In the method of the present invention, as described above, a heat-retaining zone is provided from the position on the upstream side of the frost line L to the dimension equivalent to the aX diameter of the bubble 12 to allow the heat-retaining zone to pass through. The temperature in this direction equalizes while passing through this zone.

Internal residual strain due to temperature distortion is eliminated, and a homogeneous film is created all around the circumference, and this heat insulation zone is exposed to the outside air 2::τ::
F::::Two! 2: There is no occurrence of shielding due to 2". ・Especially when forming the bottom of polystyrene film with a high blowing ratio of 2 to 8 times the bubble, even a small amount of airflow in the workplace will prevent uneven cooling. happened.

Supercooling may also occur due to the blowing air from the air cooling device 18, or the puzzle guide cylinder 19a as shown in the figure.

19b and 19C and the air cooling device 18 are provided concentrically.

The pressure adjustment chamber 20a is closed except for the upper end.

20b and 20C, when the bubble 12 is applied with a small amount of air and molded, the stability of the puzzle 120 above the bubble guide tube is inevitably poor because the amount of air from the air cooling device 18 is small.

Although it is easy to cause vibration, according to the method invention described above.

These drawbacks can be overcome and a blown film can be formed.

Especially when the heat-retaining zone is heat-resistant and heat-retaining, it is wrapped directly around the bubble.

The heat retaining and stabilizing effects of the bubbles are particularly remarkable.

If the entire heat retention zone is located downstream of the frost line, distortion due to thermal imbalance cannot be removed, and if the length l of the heat retention zone is smaller than the above limit, distortion removal and bubble retention will be incomplete. If l is too large, bubbles that cannot be cooled down sufficiently after passing through this heat-retaining zone will be folded, causing blocking.

In the device invention, in addition to being able to carry out the method invention described above, the heat insulating band 14 has heat resistance and heat retention, so it can sufficiently withstand the heat from the bubble 12 and has a sufficient heat insulating effect, and the band can be wrapped around it. Since the heat insulating band 14 is designed to be able to fit freely to the size of the bubble, and because the heat insulating band 14 is locked to an immovable part by a locking device, it will not move even when the puzzle 12 flows.

In particular, if the insulation band 14 is made of cotton cloth or other material with a fine mesh and a soft surface, the surface of the puzzle 120 will not be damaged, and if the locking device is just a tension member 15, the structure is simple and inexpensive. and can be easily added to existing equipment,
Demonstrates beloved formability. Such moldability can be fully exhibited even when molding polystyrene films.

The velvet-type fastener 17 attached to the inside of the outer end 16 of the heat-insulating band 14 does not change the inner diameter of the heat-insulating band 14 during molding, there is no risk of it coming undone, and the inner diameter can be changed steplessly, making it suitable for various puzzles. Able to handle dimensional shaping.

In addition, when the puzzle is equipped with a curved holding plate 26, the stability of the puzzle becomes even more excellent.

Other dimensions of the inner and outer lips of the outlet of the illustrated lice cooling device 18 and the bubble guide tubes 19a, 19b.

The dimensions of 19C are the diameter of the annular discharge port 11 of 1001114
To give an example, the diameter of the inner protrusion is 1
20 to 160 MM, the diameter of the outer N lip 210 is 150 to 240111N, the diameter of the bubble guide cylinder 19a is 220 to 361:Il, the height is 0.7 to 1 times this diameter, the diameter of the middle puzzle guide rg119b is 420 to 56
0111111. The height is 0.8 to 1 times that height, and the diameter of the outermost bubble guide cylinder 19C is about 700 KN, and its upper end reaches the heat insulation zone, and the lower part is even larger (for example, has a diameter of 950 KN, Each pressure adjustment type 22a, 22
b, the gauge pressure suddenly decreases at 22C, and the inner and outer lips and each puzzle guide cylinder 19a.

The bubbles are sucked by the Venturi effect near the upper edges of 19b and 19c, and the bubbles 12 are supported in other parts by outside air and the pressure of a pressure adjustment chamber that is closed except for the upper end, allowing expansion molding with a high blow ratio. It makes it possible.

It is desirable to use such a device in conjunction with the method and device of the present invention.

[Brief explanation of drawings]

The drawings are related to this invention and show typical embodiments of the device invention, with fang 1 being a partial longitudinal sectional view, spear 2 being a cross-sectional plan view taken along the line 2-2 in Figure 11, and spear 6 being a partial longitudinal sectional view. is a perspective view of a heat insulation zone. Main symbols in the figure 1o090.9. Die, 11... annular discharge port. 12...Puzzle. 16... A pair of folding guide plates, 14...
・・Warmth retention i, 15・・・・Tension menno <-
126...Holding sales. L: Frost line, K: Height of heat insulation zone. Patent Applicant: Bluff Co., Ltd. j
l! Li-r: Walking Z figure

Claims (1)

[Claims] 1) A puzzle expanded to a predetermined diameter is expanded from slightly upstream to downstream of the frost line with a bubble diameter of 0.
A blown film forming method characterized by forming the film by passing it through a heat-retaining zone having a width of 5 to 1.5 times and shielded from outside air. 2) The blown film g according to claim IJJj, wherein the heat-retaining zone is formed by wrapping a heat-resistant and flexible heat-retaining zone directly around the bubble.
shape method. 6) It has a length sufficient to be wrapped at least once around the entire outer circumference of the puzzle expanded to a predetermined diameter. In the flow direction of the puzzle, a heat insulating zone having a hole with a size equivalent to the diameter of the y-bubble is attached to the machine frame of the film forming device or a part of the immovable part fixed thereto by a locking means that prevents the bubble from moving in the flow direction. A blown film forming apparatus characterized by being connected to. 4) The heat-insulating zone is made of a thick fabric formed from one of vegetable M fibers and mineral fibers, and has a dimension of 1 width (length in the bubble transfer direction) of 10 to 50011, preferably 15 to 25 cI11. A blown film forming apparatus according to claim 6, characterized in that: 5) The blown film forming apparatus according to claim 6, characterized in that the heat insulation band locking device comprises one type of John member on the outer peripheral surface of the puzzle.