JPH0230267Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field> This invention supplies cold air from inside the die to the inside of a bubble made of a synthetic resin tube extruded from the die of an extrusion molding machine in inflation film molding. It relates to a device that forcibly cools bubbles extruded from the inside that are still in a molten state from the inside.

<Prior art> In this type of inflation film forming, bubbles that are still in a molten state immediately after being extruded from a die are expanded by the air sealed inside in the cooling and solidification process, and are formed into the desired shape. It is molded to the film width dimension. In addition, in order to make a thick film uniform in tensile strength all around and to obtain a high-quality film, we cool the bubble from the outside as well as from the inside. As with external cooling, this uses cold air for internal cooling, and in the process of blowing this cold air into the bubble from the die and circulating it, it expands and cools the bubble, and then discharges it to the outside of the bubble through the die. There is.

<Problems to be solved by this invention> In a conventional example of a bubble internal cooling device using this type of cold air, as shown in FIG. The cold air from the air supply pipe D of the die C is sequentially supplied into each ring A via the vertical short pipes E to G, and the slit-like The cold air is blown out from the cold air blowing lip H to the inner surface of the bubble, but since the inside of the upper and lower rings A are communicated with each other through the vertical short pipes E, F, and G, the cold air is blown from the upper ring A to the inner surface of the bubble. The supplied air volume is reduced compared to the one in the lower tier, and it seems to be insufficient.If the area of each lip H is constant, the velocity of the cold air blown from these will be weaker in the upper tier, and the cold air from the lip H of the ring A in each tier will be lower. The speed becomes non-uniform, and the bubble cooling effect of the cold air cannot be made constant even at all height positions, which causes the bubble to vibrate vertically or horizontally.

In order to improve this drawback, a conventional technique in which the cross-sectional area of the vertical short pipes E, F, and G in each stage is made larger toward the lower stage is described in Japanese Patent Publication No. 56-7854. It is difficult to set up and manufacture, and the structure is complicated, so there is still room for improvement.

Further, the cold air blown from the lip H of each ring A passes through a cylindrical air guide path with a short axial length between each ring A, and then passes through the inner wall of the central pipe K and the ring A forming the central exhaust passage J. As the air is sucked into the annular suction passage L formed between them and rises, the pressure inside this air guide passage becomes a negative pressure state lower than atmospheric pressure, and some of the bubbles that are being internally cooled by the cold air However, at the position of this air guide path, that is, the position between the upper and lower rings A, there is a risk that it will be sucked into the internal cooling device and come into close contact with the internal cooling device, which may prevent smooth internal cooling of the bubble, which is the stage before blowing into a bubble of the desired diameter. If this is not possible, the bubble will vibrate left and right or up and down, and when the bubble is wound up, uneven thickness will likely occur in the bubble, and in the worst case, it will break, reducing the efficiency of film forming.

These matters can be pointed out as problems.

This invention improves the problems of the prior art,
The main objective is to provide a device that uniformly internally cools bubbles without vibration.

<Means for solving the problem> This invention is a bubble internal cooling device devised to solve the above-mentioned main purpose. An apparatus for cooling the inside of a bubble from the inside, comprising: an inner tube whose upper end opens into the bubble and whose lower end communicates with the central exhaust suction path of the die to form a central air exhaust passage; an inner intermediate tube whose lower end communicates with the cold air outlet of this die and forms a cylindrical cold air supply path around the inner tube; and an inner intermediate tube whose upper end opens into a bubble and whose lower end is closed and which connects the air rising passage. An outer intermediate pipe formed around the outer intermediate pipe is arranged concentrically, and a pair of adjacent identical cold air discharge chambers are arranged above and below in the circumferential direction and spaced apart in the axial direction on the outer peripheral surface of the outer intermediate pipe. A circumferential direction which is formed by a ring-shaped material having an outer diameter and communicates with the cold air discharge chamber between an outwardly extending lip of the upper ring-shaped material and an inwardly extending lip of the lower ring-shaped material. A slit-shaped cold air outlet groove is formed, and a large number of short pipes communicating between each cold air outlet chamber and the cold air supply path are arranged radially across the air ascending passage in the radial direction. Between the chambers, a cylindrical body with a large number of small holes is stretched flush with the tip surface of the cold air blowing groove, and the cylindrical body, the shape material and the outer circumferential surface of the outer intermediate pipe arranged at a distance from each other form a cylindrical body with a large number of small holes. , an air return chamber isolated from the cold air discharge chamber is formed, and a large number of communication holes are formed in the outer intermediate pipe located between each air return chamber and the air ascending passage, and the peripheral surface of the cylinder and the tip surface of the cold air blowing groove are formed. This is a bubble internal cooling device for inflation film molding, characterized in that a cylindrical bubble guide surface is formed.

<Embodiment> A typical embodiment of this invention will be explained based on FIGS. 1 to 3.

1 to 3, 10 is a bubble internal cooling device, and the inner tube 11 of this cooling device 10 is
The upper end thereof opens into the bubble W, and the lower end thereof communicates with the air exhaust port 13 of the die 12 of the extrusion molding machine, thereby forming a central air exhaust passage 14. The upper end of the inner intermediate tube 15 that shares an axis with the inner tube 11 is closed by a ring-shaped end plate 16, and the lower end thereof communicates with the cold air outlet 17 of the die 12. A cylindrical cold air supply path 18 is formed around the inner tube 11.

Air rising passage 19 is arranged around this inner intermediate pipe 15.
The outer intermediate tube 20 forming the inner tube 1 has the axis line
1. This outer intermediate 2 is shared with the inner intermediate tube 15 and is located inside the bubble W on the upper surface of the die 12.
0, the inner intermediate tube 15 and the inner tube 11 are arranged concentrically, and the upper end of the outer intermediate tube 20 is connected to the bubble W.
It opens inward, and its lower end is closed by a ring-shaped end plate 21.

The upper ends of the inner tube 11 and the inner intermediate tube 15 are fixed to the ring-shaped end plate 16, and the ring-shaped end plate 1
A mixing prevention ring body 16a that prevents mixing of the air blown out from the air ascending passage 19 and the air flowing into the central air exhaust passage 14 is provided on the upper surface of the central air exhaust passage 14 to protrude upward.

On the outer peripheral surface of the outer intermediate pipe 20, annular cold air discharge chambers are formed in the circumferential direction at intervals in the axial direction by a pair of adjacent ring-shaped shapes 22 and 23 having the same outer diameter dimension located above and below. 24 is formed in a layered manner, and includes an outwardly extending lip 22a of the upper ring-shaped member 22 and a lower ring-shaped member 23.
A circumferential slit-shaped cold air blowing groove 25 communicating with the cold air blowing chamber 24 is formed between the inwardly extending lips 22b. A short pipe 26 communicating between each of these cold air discharge chambers 24 and the cold air supply path 18
are arranged radially across the air ascending passage 19 in large numbers, and direct the cold air supplied to the cold air supply path 18 to each cold air discharge chamber 2 through a group of short pipes 26.
A path is formed in which the air is sequentially supplied into the bubble W and is blown out from the circumferential slit-shaped cold air blowing groove 25 toward the inner surface of the bubble W.

A cylindrical body 28 having a large number of small holes 27 is provided between the vertically adjacent cold air blowing chambers 24 and the cold air blowing grooves 2.
5, an air return chamber 29 which is stretched flush with the tip surface and is isolated from the upper and lower cold air discharge chambers 24 by this cylinder 28, the shapes 23, 22 spaced apart from each other, and the outer peripheral surface of the outer intermediate tube 20; is formed.

That is, the cold air discharge chamber 23 and the air return chamber 29, which are partitioned by the shapes 22 and 23, are formed and arranged alternately in the axial direction around the outer intermediate pipe 20.
A large number of communication holes 30 are bored in the outer intermediate pipe 20 located between each air return chamber 29 and the air rising passage 19, and air flowing into the cold air blowing chamber 22 from the small hole 27 of the cylinder body 28 is passed through the communication holes 30. Air rising passage 19
A path is formed in which the bubbles are sucked into the bubble W, rise along this passage 19, and blow out into the bubble W from its upper end.

A cylindrical bubble guide surface is formed by the circumferential surface of the cylindrical body 28 and the tip end surface of the cold air blowing groove 25.

Note that a cylindrical body 31 is provided between the lowest air return chamber 29 and the die 12, and the inner intermediate pipe 15
A planar ring-shaped space 32 is formed around the . This space 32 is divided into two inner and outer chambers 32a and 32b by a cylindrical perforated plate 33 through which cold air can freely pass.
5 are connected to the cold air supply path 18 through two sets of upper and lower communication holes 34, and the outer blowing chamber 32b near the cylindrical body 31 has an upwardly facing hole that opens near the molten resin discharge port 35 of the die 12. Blowout annular port 32c
is formed, and a portion of the cold air immediately after being blown out from the cold air outlet 17 of the die 12 flows through the communication hole 34, the inner pressure adjustment chamber 32a, the perforated plate 33, and the outer blowing chamber 32b.
A passage is formed in which the air passes through in a zigzag pattern in this order and blows out from the annular blowout port 32c.

Needless to say, the lower end of the outer intermediate tube 20 is closed by the end plate 21 directly above the ring-shaped space 32.

<Operation> The operation of the present invention configured as described above will be explained below.

When the blower P ₁ communicating with the cold air outlet 17 of the die 12 and the blower P ₂ communicating with the air outlet 13 of the die 12 are started, the cold air is supplied from the cold air outlet 17 of the die 12 by the blower P ₁ according to the present invention. After being supplied to the cold air supply path 18 of the bubble internal cooling device 10, a part of the cold air is supplied to the communication hole 34 near the die 12.
The bubbles pass through the inner pressure adjustment chamber 32a, the porous plate 33, and the outer blowing chamber 32b in order, and are blown out from the blowing annular opening 32c toward the inner surface of the bubble W in a molten state during extrusion molding from the outlet 35 of the die 12. The inner surface of the bubble W is cooled, and the other cold air rises along the circumferential surface of the bubble W and the cylindrical body 31, and as it rises through the cylindrical cold air supply path 18, it passes through the short pipe 26 extending in the radial direction. The cold air is sequentially distributed and supplied to each cold air discharge chamber 24, and then blown from each cold air discharge chamber 24 toward the inner surface of the bubble W through the slit-shaped cold air blowing groove 25 in the circumferential direction, thereby cooling the inner surface of the bubble W and forming bubbles. Rising along.

A part of the air whose temperature has risen slightly by cooling the inner surface of the bubble continues to rise along the bubble while being further cooled, and merges with the cold air blown out from the cold air blowing groove 25 of the next cold air blowing chamber 21. Bubble W
It continues to cool the bubble W by rising upward along the same direction.

Another part of the air whose temperature has risen slightly by cooling the bubble W is guided into the adjacent upper air return chamber 22 through a large number of small holes 27 of the cylinder body 28, and then the air rises. After being sucked into the air passage 19 through the communication hole 30, the air rises in the air rising passage 19, and all the warm air sucked from each air return chamber 22 is blown out from the upper end of the air rising passage 19. , merges with the air rising along the bubble W, and rapidly expands and expands the bubble W immediately after leaving the internal cooling device to a desired diameter. At this time, the mixing prevention ring 16a prevents the air flowing into the exhaust passage 14 and the air blown out from the rising passage 19 from mixing. All the warm air that has expanded and expanded the bubble W in this way flows in and descends from the upper end of the central air exhaust passage 14 formed by the inner tube 11, and is discharged from the air exhaust port 13 of the die 12 to the outside of the die 12. .

This air rising passage 19 and the central air exhaust passage 14
If they are communicated with each other by short pipes provided in the radial direction near their upper ends, the central air exhaust passage 1
A part of the air in the air rising passage 19 is forcibly sucked into the air flow flowing through the air passage 4, thereby making the upward flow of air in the air rising passage 19 more reliable.

<Effects> The internal cooling device 10 of this invention, which is constructed and operates as described above, has the following effects.

The cold air is supplied to each cold air discharge chamber 24 by passing the cold air rising through a cylindrical cold air supply path 18 formed around the inner pipe 11 by the inner intermediate pipe 15 to a plurality of short channels arranged radially in the radial direction. Since the structure is such that the pipes 26 supply the cold air in a distributed manner from the radial direction, even if the short pipes 26 of the same size are used, almost the same amount of cold air can be distributed and supplied to the cold air discharge chambers 24 spaced apart in the axial direction. The structure is simplified, and the same air volume and speed can be blown out from the frit-shaped cold air blowing grooves 25 of each cold air discharge chamber 24 toward the inner surface of the bubble W, without vertical or horizontal vibration. can be cooled uniformly from the inside in a stable state, and uneven thickness can be prevented.

A part of the air that is blown out from each slit-shaped cold air blowing groove 25 toward the bubble W and slightly warmed by the cooling of the bubble W rises along the inner surface of the bubble W and passes through the group of small holes 27 of the cylinder 28 to each air. Since most of the warm air flows into the air return chamber 29, it is possible to flow into the air return chamber 29 without increasing the inflow speed at once. While maintaining the pressure inside the air return chamber 29 at almost atmospheric pressure without making it negative pressure,
A large amount of warm air can be guided to the air rising passage 19 through the communication hole 30, and the bubble W can be prevented from coming into close contact with the circumferential surface of the cylindrical body 28 at the air return chamber 29 position. The bubble W can be supported and internally cooled by the cold air rising along the bubble W while being spaced apart from the outer peripheral surface of the internal cooling device 10.

<Effects of the embodiment> Mixing prevention ring body 16a provided on the end plate 16
As a result, it is possible to reliably prevent the air blowing out from the upper end of the air rising passage 19 from mixing with the air flowing in and falling into the central air exhaust passage 14 from the upper end, and to direct this blowing air along the bubble W without causing an overflow. By appropriately mixing with the rising air, the bubbles W can be blown to a desired diameter all at once.

A portion of the cold air, which still has a high cooling capacity, is blown from the blow-off annular opening 32c formed in the outer blow-off chamber 32b near the cylindrical body 31 to the entire inner peripheral surface of the bubble W immediately after being extruded from the discharge port 35 of the die 12. can be attached,
The bubble W can be internally cooled immediately after extrusion molding, and the air warmed by bubble cooling can be guided upward along the outer circumferential surface of the cylindrical body 31 to stably guide the bubble W to the upper air return chamber 22. , and since low-temperature air is always sequentially supplied to the inside of the cylinder 31, the air flowing around the outer circumferential surface of this part is cooled from the inside while flowing through this section, creating a bubble cooling effect. It can be increased further.

If the cylindrical body 28 is formed by forming a punching plate with a large number of small holes 27 into the cylindrical body, the cylindrical body 28 can be manufactured easily.

In addition, for convenience of assembly, the mold materials 22 and 23 are
It is divided into two parts.

[Brief explanation of the drawing]

The figures relate to this invention; FIG. 1 is a longitudinal cross-sectional view of a typical embodiment of this invention, FIG. 2 is a cross-sectional view of the air discharge chamber, and FIG. 3 is a
A cross-sectional view at the air return chamber position, FIG. 4, is a schematic diagram showing one of the conventional examples. Explanation of main symbols, 10...Bubble internal cooling device, 11...Inner tube, 15...Inner intermediate tube, 20...
...Outer intermediate pipe, 22, 23... Shape material, 24... Air discharge chamber, 25... Slit-shaped air discharge groove, 2
9...Air return chamber.

Claims (1)

[Claims for Utility Model Registration] 1. A device for cooling the inside of a bubble made of a synthetic resin tube extruded from a die of an extrusion molding machine from the inside, the upper end opening into the bubble and the lower end opening into the central exhaust of the die. an inner pipe that communicates with the suction passage to form a central air exhaust passage; and an inner middle whose upper end is closed and whose lower end communicates with the cold air outlet of this die, forming a cylindrical cold air supply passage around the inner tube. A tube and an outer intermediate tube whose upper end opens into a bubble and whose lower end is closed to form an air ascending passage around the inner intermediate tube are arranged concentrically, and an axial space is formed on the outer peripheral surface of the outer intermediate tube. An annular cold air discharge chamber is formed by a pair of adjacent ring-shaped sections having the same outer diameter, and the outer diameter of the annular cold-air discharge chamber is located one above the other in the circumferential direction. A slit-shaped cold air blowing groove in the circumferential direction communicating with the cold air discharge chamber is formed between the inwardly extending lips of the ring-shaped member, and a short pipe communicating between each cold air discharge chamber and the cold air supply path is formed to A large number of cylinders are arranged radially across the ascending passage in the radial direction, and between the upper and lower adjacent cold air blowing chambers, a cylinder body with many small holes is stretched flush with the tip surface of the cold air blowing groove. An air return chamber isolated from the cold air discharge chamber is formed by the molded material and the outer peripheral surface of the outer intermediate pipe, which are arranged at a distance from the cylinder, and an outer air return chamber located between each air return chamber and the air ascending passage. 1. A bubble internal cooling device for inflation film molding, characterized in that a number of communicating holes are formed in an intermediate tube, and a cylindrical bubble guide surface is formed by the circumferential surface of the cylinder and the tip surface of the cold air blowing groove. 2. The bubble internal cooling device for inflation film molding according to claim 1, wherein the cylindrical body is a punch plate having a large number of holes.