JPS641069Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an apparatus for producing thin tube strips or film strips by an inflation method, and particularly relates to an inflation molding machine that discharges material downward.

Conventionally, as an inflation type bubble cooling device that discharges downward, as shown in the figure, a donut-shaped cooling tank 13 is inserted into the center hole 14 of the tank 13.
The cooling water inside is allowed to overflow, and a bubble expanded to approximately match the inner diameter of the center hole 14 is introduced into the center hole 14 for cooling.

In general, the method of inflation processing by discharging bubbles downward is often used for molding materials with low melt tension, such as polypropylene, and the expansion ratio is set at 1.5 to 2 at most, and the processing speed is also slow. As the processing speed is increased, the stability of the bubble deteriorates, especially since the melting force is small, resulting in deterioration of product quality and, in severe cases, the bubble rupture. .

Therefore, the purpose of this invention is that even when molding such materials, the expansion ratio can be improved to nearly 3, and the processing speed can be improved compared to conventional equipment that does not include the equipment of this invention. compared to 50
The aim is to obtain a product with an improvement of 70% and excellent transparency.

This idea allows the cooling water in the tank to overflow into the center hole of a donut-shaped cooling tank, and introduces a bubble that is discharged downward from the die into the overflowing center hole, so that the cooling water comes into contact with the outer circumferential surface of the bubble. In an inflation molding machine, there is an air cooling device with an annular air outlet along the outer circumference of the bubble close to the annular resin discharge hole of the die, and an air cooling device located downstream of the bubble and upstream of the cooling tank. is provided with an air guide device that surrounds the bubble and includes a donut-shaped air guide plate with a variable inner diameter, and the air cooling device and the air guide device are connected by a cylindrical member having a diameter equivalent to that of the bubble. The downward inflation molding machine is characterized in that a pressure chamber is formed by a space surrounded by the air cooling device, the air guiding device, and the cylindrical member.

The invention will now be explained based on the illustrated representative embodiment.

10 is a die fixed to the molding machine, resin is discharged in a cylindrical shape from the annular resin discharge hole 11, and bubbles B expanded by the internal pressure are transferred to the die 1.
0 and is guided to a water-cooled cooling device 12 provided on the same axis.

This water-cooled cooling device 12 stores water in a doughnut-shaped cooling tank 13, causes the water to overflow into a hole 14 in the center, introduces the expanded resin bubble B into the hole 14, and causes the surface of the bubble B to flow. The water overflowing from the tank 13 is brought into contact with the water in a film form and cooled.

In this device, in addition to this device, a bubble B is provided near the annular resin discharge hole 11.
An air cooling device 16 having an annular air outlet 15 along the outer peripheral surface of the bubble B is provided, and a donut-shaped air guide plate 18 surrounding the bubble B and having a variable inner diameter is provided at a position further downstream from the air cooling device 16. An air guiding device (commonly referred to as an iris device) 19 is provided. To be more specific, this air guide device 19 has a structure similar to a light diaphragm device of a camera, and has a donut-shaped plate 18a made of a thin metal plate shaped as shown in FIG. A donut consisting of a large number of plates 18a is formed by supporting the support frames 21 of the plates 18a, 22, and 23, respectively, and engaging the action points 22 with a common ring-shaped actuation member 23, and moving this actuation member 23 in the circumferential direction. The diameter of the inner peripheral edge 17 of the air guide plate 18 of the mold is bubble B,
It is designed so that it can be changed depending on the purpose of processing.

24 is a cylindrical member with a diameter equivalent to that of the bubble connecting the air cooling device 16 and the air guiding device 19;
A pressure chamber 26 is formed by the space surrounded by the air cooling device 16, the air guide device 19, and the cylindrical member 24, and even if the cylindrical member 24 is provided so that the length thereof can be changed, this invention does not apply. The air cooling device 16, the air guiding device 19, and the water-cooling type cooling device 12 are provided in the machine frame either all together or individually so that the distance apart from the die 10 can be adjusted.

When performing inflation molding using this device configured as described above, the bubble B discharged from the annular resin discharge port 11 of the die 10 is similar to the known downward type inflation molding machine. through the center hole 14 and the clamping roller 2 below.
5 and adjust the pressure in bubble B to open the center hole 1.
The bubble B is expanded to a size that almost reaches the inner diameter of the bubble B.

In particular, in this device, the circumferential surface of the bubble B that has just been discharged from the annular resin discharge port 11 is slightly cooled by the air discharged from the air cooling device 16, and this cooling air flows along the circumferential surface of the bubble B. The air then flows as a laminar flow, passes between the ring-shaped air guide plate 18 of the air guide device 19 and the bubble B, and is discharged into the atmosphere.

Therefore, the slightly cooled bubble B moves to the air guide plate 1.
Due to the reduction in external pressure caused by the high-speed air flow passing through the bubbles 8 and bubbles B, the fibers expand all at once, are rapidly cooled by the water-cooled cooling device 12, are flattened by the holding rollers 25, and are wound up.

In this device configured as described above, the surface of the molten bubble is slightly cooled by the cooling air blown out from the annular air outlet 15 of the air cooling device 16, and the air cooling device 16 and the air guide Since the device 19 is connected by a cylindrical member 24 and the pressure chamber 26 is formed, there is no place for the cooling air to be released outside other than the gap between the bubble B and the air guide plate 18, and the cooling air is In addition to sufficiently contacting the bubbles to increase the cooling effect, the speed of the airflow in the pressure chamber 26 formed by being surrounded by these bubbles becomes slower, and the pressure inside the pressure chamber 26 rises more than that of the outside air, stabilizing the bubble B at the center. It has an expansion effect due to the pressure reduction after passing through the air guide plate 18, and as a result, the extrusion speed of the bubble B can be improved by 50 to 70% compared to the one without this air cooling device. Moreover, the expansion ratio can be increased to 2 to 3, the transparency and surface gloss are improved, higher quality products can be produced, and the improved productivity can lower the cost.

In addition, since the diameter of the inner circumferential edge 17 of the air guide plate 18 is variable, it can be adjusted to the optimum size depending on the purpose.

[Brief explanation of the drawing]

The figure shows what is related to this invention,
FIG. 1 is a schematic longitudinal sectional front view of the entire device, FIG. 2 is a plan view of the air guiding device, and FIG. 3 is a partially exploded plan view of FIG. 2. Symbols in the figure, 10...Die, 11...Annular resin discharge hole, 12...Cooling device, 13...Cooling tank,
14... Center hole, 15... Annular air outlet, 16
... Air cooling device, 18 ... Guide plate, 19 ... Air guide device, 24 ... Cylindrical member, 26 ... Pressure chamber, B
……bubble.

Claims (1)

[Scope of Claim for Utility Model Registration] Cooling water in the tank overflows into the center hole of a donut-shaped cooling tank, and a bubble discharged downward from a die is introduced into the center hole of the overflow, thereby discharging the cooling water. In an inflation molding machine that makes contact with the outer circumferential surface of a bubble, an air cooling device has an annular air outlet along the outer circumferential surface of the bubble close to the annular resin discharge hole of the die, and a cooling tank is installed downstream of the bubble. An air guide device is provided at a position upstream of the bubble and includes a doughnut-shaped air guide plate with a variable inner diameter, and the air cooling device and the air guide device are arranged in a cylinder having a diameter equivalent to that of the bubble. A downward inflation molding machine, characterized in that the pressure chamber is formed by a space surrounded by the air cooling device, the air guiding device, and the cylindrical member.