JPH06278199A - Molding method and device for hollow container - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a direct blow molding method and a molding apparatus for a hollow container, capable of blowing a fluid by using a large-diameter hollow needle, and having high production efficiency. [Structure] A parison of a molten polymer is sandwiched between a pair of split molds, a hollow needle is pierced into the parison whose both ends are sealed, and a fluid is blown into the parison to expand it into a hollow body, and at the same time expand by circulating the fluid. In the method of forming a hollow container in which an exhaust port is formed in the hollow body to cool the hollow body, a relatively small diameter hollow needle and a relatively large diameter hollow needle are arranged in a split mold, and both ends are A small-diameter hollow needle is stabbed into the sealed parison to blow the fluid, and then a large-diameter hollow needle is stabbed to blow the fluid at a large flow rate while the internal pressure is applied to the parison.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for molding a hollow container, and more particularly, to a hollow container which is capable of efficiently expanding a parison and cooling a blow-molded container and is excellent in production efficiency. The present invention relates to a molding method and a molding device.

[0002]

2. Description of the Related Art It has been a conventional practice to mold a thermoplastic synthetic resin hollow container by direct blow molding. In this molding method, a parison made of a molten polymer is sandwiched in a split mold, a hollow needle is pierced into the parison, and a fluid is blown into the parison through the hollow needle to expand and cool the parison. It is formed into a shape and a size. In the above molding method, in order to penetrate the parison with a hollow needle for inserting a fluid into the parison, since the parison sandwiched in the split mold is soft at a relatively high temperature, it is difficult to pierce the parison with a thick needle. , Had to use a hollow needle with a fine tip and a sharp tip.

[0003]

However, when a thin needle is used as the hollow needle for injecting fluid into the parison in this manner, the amount of fluid that can flow into the parison per unit time is small and molding is difficult. There was a problem that it took time. Moreover, it is difficult to expand the parison with this small amount of fluid, and it is difficult to cool the expanded hollow body. Even if it is possible to mold a container with a small volume, it is possible to form a large volume container. The container could not be molded.

On the other hand, in direct blow molding,
An unnecessary part called the flash part, which is cut off after molding, is formed above the part that should be the mouth part of the molding container, a hollow needle is pierced into this unnecessary part from the direction perpendicular to the axial direction of the parison, and the exhaust port is also installed. By providing it, it becomes possible to leave the trace on the molding container. However, when the hollow needle is pierced into this portion to blow the fluid, it is preferable that the fluid easily flows in the direction of the body of the container, that is, downward in the parison axial direction.
However, in the case of a thin needle, the fluid injection port can be provided only at the tip of the needle due to processing, so the fluid can be injected only in the direction perpendicular to the axial direction of the parison, and the fluid can be efficiently injected into the parison. Since it cannot be circulated and the cooling fluid cannot be blown in at a large flow rate, there is a problem that it takes a lot of time to cool the container.

Therefore, an object of the present invention is to provide a direct blow molding method and a molding apparatus for a hollow container, in which a fluid can be blown using a large diameter hollow needle.
Another object of the present invention is to provide a method and apparatus for molding a hollow container with high production efficiency.

[0006]

According to the present invention, a parison of a molten polymer is sandwiched between a pair of split molds, a hollow needle is pierced into the parison whose both ends are sealed, and a fluid is blown into the parison to form a hollow body of the parison. In the method of forming a hollow container, in which the hollow body is cooled by expanding the air into the hollow body and then forming the exhaust port in the hollow body by the circulation of the fluid and then cooling the hollow body, The hollow needle and the hollow needle are placed in a split mold, and a small diameter hollow needle is stabbed into the parison that is sealed in the split mold and sealed at both ends to inject fluid, and then the parison has a large diameter with internal pressure applied. There is provided a method for molding a hollow container, which comprises piercing a hollow needle and blowing a large amount of fluid.

Further, according to the present invention, a pair of split molds provided with a hollow container and a cavity for forming a flash part inside the mold, and a pinch-off part of a parison and capable of opening and closing; a flash part of the split mold. A relatively small-diameter hollow needle and a relatively large-diameter hollow needle provided in a portion corresponding to
A pressurizing fluid supply mechanism for supplying a pressurizing fluid to each of the hollow needles that advances each of the hollow needles from the standby position to the operating position of piercing the parison and retracts the hollow needles from the operating position to the standby position; An exhaust port forming mechanism for forming an exhaust port in the parison at the end of expansion of the parison provided in a portion corresponding to the flash section; a small-diameter hollow needle is first advanced to inject the fluid first, and then the timing is set. And a control mechanism for controlling the operation of the large-diameter hollow needle and the small-diameter hollow needle so that the large-diameter hollow needle is moved forward to blow the fluid therein. .

[0008]

As described above, when a hollow container is formed by direct blow molding, if a large diameter hollow needle can be used as a hollow needle for blowing fluid, a large volume of fluid can be blown and cooling can be performed efficiently. It can be performed well, and molding of a large capacity container is also possible. Also, with a large-diameter hollow needle, the position of the fluid injection opening can be freely changed, and the parison can be efficiently expanded.
In the present invention, by using a large-diameter hollow needle in combination with a small-diameter hollow needle, it becomes possible to use a large-diameter needle that could not be used conventionally.

That is, since the parison wall is soft at a relatively high temperature, a large diameter hollow needle cannot be directly penetrated into the parison wall, but first a small diameter hollow needle is pierced to blow a fluid into the parison to increase the internal pressure. When applied, the parison becomes elastic, so that it is possible to puncture a large-diameter hollow needle after a short time after puncturing a small-diameter hollow needle. As described above, in the present invention, since it becomes possible to use a large-diameter needle, a large volume of fluid can be blown into the parison, and not only expansion of the parison but also sufficient cooling can be performed. Is possible,
It is possible to improve the molding cycle.
Moreover, since a large volume of fluid can be blown in, it is possible to mold a large bottle.

[0010]

The present invention will be described in detail with reference to the accompanying drawings. 1 and 2 showing an example of an apparatus for manufacturing a hollow molded container according to the present invention, a pair of openable and closable split molds 1a and 1b are pinch-off portions 3 for sealing a parison 2, respectively.
a, 3b, a cavity 4 forming a hollow container, and a cavity 5 forming a flash portion are formed. In the present invention, the flush section is a section provided above the mouth of the hollow container to be molded, for piercing a hollow needle for injecting a fluid, and for providing an exhaust port and the like. Since the flash portion is cut off after the blow molding, it is possible to leave no traces in the manufacturing process such as holes pierced by hollow needles in the container. A hollow needle 6 having a relatively small diameter and a hollow needle 7 having a large diameter below the hollow needle 6 are positioned in a standby state in a portion of the cavity 5 corresponding to the flash portion. Further, an exhaust port forming mechanism 8 for forming an exhaust port in the parison at the end of the expansion of the parison and a knockout pin 9 for taking out the molded hollow container from the mold to a predetermined position are respectively provided.

The small-diameter hollow needle 6 and the large-diameter hollow needle 7 can be advanced or retracted between the standby position shown in FIG. 1 and the operating position shown in FIG. This operation can be performed simultaneously by using the pressurized fluid supply mechanism 10 for supplying the pressurized fluid into the parison through the small diameter hollow needle 6 and the large diameter hollow needle 7. A control device 11 for controlling whether the fluid supplied from the pressurized fluid source (not shown) through the pressurized fluid supply mechanism 10 is used for the moving operation of the pressurized fluid supply mechanism or is supplied into the parison. Are provided respectively.

The movement of small and large diameter hollow needles is shown in FIGS.
Shown in. 3 to 6, the small-diameter hollow needle 6 and the large-diameter hollow needle 7 are housed in the cylinders 13a and 13b provided in the drive devices 12a and 12b, and can move back and forth inside thereof. ing. Cylinder 1
3a and 13b are provided with supply ports 14 and 15 for supplying pressurized fluid, respectively, of these supply ports 14a and 14b.
It leads to the front side of 3b. Also, supply ports 15a and 15b
Communicates with the rear side of the cylinder, and the fluid supplied from this supply port flows inside the hollow needle or pushes from behind the hollow needle toward the front.

In FIG. 3, since the fluid flows from the supply ports 14a and 14b to the front side of the cylinder and pushes the hollow needles 6 and 7 rearward, the hollow needles 6 and 7 are positioned rearward. In FIG. 4, the supply of the fluid from the supply port 14a is stopped, and the fluid is supplied from the supply port 15a instead. As a result, the small-diameter hollow needle 6 moves forward (toward the parison) and pierces the parison, and the fluid flowing through the hollow needle is blown into the parison. On the other hand, the large-diameter hollow needle 7 still does not move because the fluid is supplied from the supply port 14b as in the state of FIG. In FIG. 5, the supply of fluid from 14b is stopped even in the large-diameter hollow needle 7,
Instead, since the fluid is supplied from the supply port 15b, the large-diameter hollow needle 7 also starts moving forward and begins to inject the fluid into the parison. In FIG. 6, the supply port 14a
And during the supply of the fluid from 15a, or after the supply is completed,
Fluid is supplied from the supply port 15b and blown into the parison through the large-diameter hollow needle 7 to cool the container.

7 and 8 for explaining the pressurized fluid supply mechanism and the control mechanism for the small diameter and large diameter hollow needles,
Small-diameter hollow needles and large-diameter hollow needles have small-diameter hollow needles inserted into the parison first to inject fluid to apply internal pressure to the parison, and then large-diameter hollow needles to insert fluid, but The operation of the hollow needle and the large-diameter hollow needle and the injection of the fluid can be controlled by using a cam as shown in FIG. 7A shows a cam 16a used for a small diameter hollow needle, and FIG. 7B shows a cam 16b used for a large diameter hollow needle. The drawing on the left side is a view of (A) and (B) as seen from the side. In the cams 16a and 16b that rotate in the directions of the arrows in the figure, the small-diameter hollow needle and the large-diameter hollow needle do not move from the point 0 °, which is the completion point of mold closing, to the point A in the figure, and the point A When it reaches, the small-diameter hollow needle is inserted into the parison, and the fluid is blown into the parison only from the small-diameter hollow needle between the points A and C to apply the internal pressure. When the point C is reached, a large-diameter hollow needle is inserted into the parison, and the fluid is blown into the parison from the large-diameter hollow needle between points C and D to cool the inside of the bottle.

Incidentally, the correspondence of the cam movement shown in FIGS. 3 to 6 in FIG. 7 is as follows: FIG. 3 shows a state between 0 ° (completion of mold closing) and point A in FIG. 7, and FIG. 4 shows A in FIG. 7 is a state between points C and B, FIG. 5 is a state between points C and B in FIG. 7, and FIG.
It corresponds to the state between the points B and D.

In FIG. 8 showing the relationship between the cam and the fluid blowing shown in FIG. 7, O ° is the time when the mold closing is completed, L is the time when the fluid is blown by the small diameter hollow needle,
S is the time in which the fluid is blown from only the small diameter hollow needle. W is the time when the fluid is being flown in from both the small diameter and large diameter hollow needles, and Q is the time when the fluid is being blown only by the large diameter hollow needles. 360 ° is the mold opening start position. During L, the parison expands and is shaped to the desired size and shape. Next, the inside of the hollow container formed during Q is cooled. In the present invention, the blowing time (L in FIG. 8) of the fluid by the small-diameter hollow needle is in the range of 0.5 to 10 seconds, particularly 1 to 4 seconds, and the large-diameter hollow needle after the small-diameter hollow needle is inserted. It is particularly preferable that the time until the needle is inserted (S in FIG. 8) is in the range of 0.2 to 2 seconds, particularly 0.5 to 1 second. If the time is shorter than this time, the internal pressure in the parison is not enough to pierce a large-diameter hollow needle, and if the time is longer than this time, the production cycle is lengthened and there is no merit. Further, the blowing time of the fluid by the large-diameter hollow needle (Q in FIG. 8) is in the range of 5 to 30 seconds, particularly 10 to 20 seconds, and the fluid from the small-diameter hollow needle is inserted after the large-diameter hollow needle is inserted. The time until the blowing stops (W in FIG. 8) is 0.2 to 10 seconds, especially 0.5.
It is preferably in the range of 5 seconds to 5 seconds. If the time is shorter than this time, the fluid supplied from the large-diameter hollow needle may flow backwards through the small-diameter hollow needle, and if the time is longer than this time, the production cycle will be lengthened and there is no merit. Is.

The control mechanism for controlling the operation of such small-diameter and large-diameter hollow needles is not limited to this, but the mechanism shown in FIG. 9 can be used. The state shown in FIG. 9 indicates that the cams of the small diameter hollow needle and the large diameter hollow needle are both positioned at 0 °, and both pilot valves 17 are not operating. The role of the timer 18 is to cause the fluid of the small-diameter hollow needle to be repeatedly blown after the fluid is started to be blown from the large-diameter hollow needle. This prevents the fluid in the parison from flowing back through the small diameter hollow needle. In FIG. 9, 19 is a master valve,
Reference numerals 20 respectively denote flow control valves.

When the expansion of the parison is almost completed, in order to form a small-diameter exhaust port for circulating the air blown into the parison, in order to form the small-diameter and large-diameter hollow needles, the flash portion in which the small-diameter and large-diameter hollow needles are inserted, as shown in FIG. Although the fluid can be discharged by inserting a nozzle for forming a discharge port as shown in FIG. 2, as described in Japanese Patent Publication No. 59-3260, the internal pinch-off portion of the split mold is provided with an internal structure. The outlet can also be formed by a pressure fluid. The hollow molded container from which the compressed fluid inside has been discharged is removed from the mold at a predetermined position on the conveyor or the like by the knockout pin, and the molding of the hollow container is completed.

The small-diameter hollow needle used in the present invention may be one known per se used for direct blow molding, and the diameter of the passage cross section thereof varies depending on the size of the hollow container to be molded, but it is generally 0. Those in the range of 0.5 to 5 mm, particularly 1.5 to 3 mm are preferably used.
The passage cross section of the large-diameter hollow needle preferably has an area 3 to 15 times, especially 4 to 10 times the area of the passage cross-section of the small diameter hollow needle. If it is smaller than this range, it is not possible to supply sufficient fluid for cooling, and if it is larger than this range, it becomes difficult to insert the parison easily. Unlike a small-diameter hollow needle, a large-diameter hollow needle can be processed so that the fluid-blowing opening is provided at a position other than the tip of the needle, and a fluid-blowing opening must be provided on the side of the hollow needle. You can As shown in FIG. 5, if the blow-in opening 19 is provided in the side portion of the hollow needle 7, the fluid blown from the large-diameter hollow needle 7 can be supplied in the direction of the body portion 20 of the parison 2, that is, in the vertical axis direction. Therefore, the fluid can be efficiently circulated in the parison body. Furthermore, it is preferable that the large-diameter hollow needle 7 that is inserted into the flash portion 5 of the parison is located closer to the parison body than the small-diameter hollow needle 6. As a result, a large volume of fluid blown from the large diameter hollow needle can efficiently circulate in the parison body. In the case of a parison, the large diameter hollow needle can be easily pierced by increasing the diameter of the parison with the fluid blown from the small diameter hollow needle.

As shown in FIG. 5, the small-diameter and large-diameter hollow needle driving devices 12a and 12b are preferably arranged so as to be movable in parallel. As a result, the control mechanism and the pressurized fluid supply mechanism can be shared, and the device required for moving the hollow needle and supplying the fluid can be simplified. Further, it is preferable that the driving devices for the large-diameter and small-diameter hollow needles are arranged such that the moving directions of the hollow needles intersect with each other when viewed in a projected cross section perpendicular to the container axis direction. That is, by locating the large-diameter and small-diameter hollow needles at a constant angle as shown in FIG. 10, it is possible to pierce the large-diameter and small-diameter hollow needles on the same circumference of the flash part of the parison, which is unnecessary. The flash part, which is the part, can be made smaller.

The parison which can be used in the present invention is
A bottomed parison or a tubular one can be used. At this time, it has been described above that the flash portion is provided above the portion which should be the container mouth portion, but by providing the protruding portion at the portion of the flash portion where the large-diameter hollow needle should be pierced, blow molding At this time, this portion can be thinned, and it is easy to pierce, which is particularly preferable. Further, the molding method of the present invention can be carried out by the conventionally known direct blow molding as long as it has the above-mentioned characteristics.

[0022]

[Example] The molten parison extruded from the extruder was blown in a blow mold (split mold) shown in FIG. 1 at room temperature with a blow pressure of 6 kg / cm ² from a small diameter hollow needle for about 3 seconds. Approximately 1 second after the start of the primary blow, room temperature air with a blow pressure of 8 kg / cm ² is blown from the large-diameter hollow needle for approximately 9 seconds, and then the pressurized air in the container is released in about 0.1 second. Exhausted. The blow molding method using two large and small hollow needles of the present invention has a blow time of about 11 seconds and an exhaust time of about 1.2 compared to the conventional blow molding method using one small diameter hollow needle.
It can be shortened by 9 seconds and the molding cycle is improved by about 60%.

[0023]

In the present invention, by combining with a small diameter hollow needle, it becomes possible to use a large diameter hollow needle, which has been difficult to use for direct blow molding in the past. Can be supplied. As a result, a large-capacity container can be molded, and the container can be efficiently cooled, so that the production cycle can be increased. Further, according to the molding apparatus of the present invention, the movement of the small diameter and large diameter hollow needles and the supply of the fluid can be efficiently controlled, and the production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for molding a hollow molded container of the present invention.

FIG. 2 is a diagram showing a state in which a split mold is closed in FIG.

FIG. 3 is a diagram for explaining the movement of the hollow needle.

FIG. 4 is a diagram for explaining the movement of the hollow needle.

FIG. 5 is a diagram for explaining the movement of the hollow needle.

FIG. 6 is a diagram for explaining the movement of the hollow needle.

FIG. 7 is a diagram showing a cam used in a control mechanism.

8 is a diagram showing the relationship between the movement of the cam shown in FIG. 7 and the blowing of fluid.

FIG. 9 is a diagram showing an example of a control mechanism.

FIG. 10 is a diagram for explaining positions of large-diameter and small-diameter hollow needles.

[Explanation of sign]

 1 split type 2 parison 3 pinch-off part 4 cavity 5 flash part 6 small-diameter hollow needle 7 large-diameter hollow needle 8 exhaust port forming mechanism 9 knockout pin 10 pressurized fluid supply mechanism 11 control device 12 drive device 13 cylinder

Claims (11)

[Claims] 1. A parison of a molten polymer is sandwiched between a pair of split molds, a hollow needle is pierced into the parison whose both ends are sealed, and a fluid is blown into the parison to expand the parison into a hollow body and circulate the fluid. In the method of forming a hollow container in which an exhaust port is formed in the hollow body to cool the hollow body following expansion, a relatively small diameter hollow needle and a relatively large diameter hollow needle are arranged in a split mold. , Characterized in that a small diameter hollow needle is stabbed into a parison whose both ends are sealed to blow a fluid, and then a large diameter hollow needle is stabbed to blow a fluid at a large flow rate while the internal pressure is applied to the parison. Molding method for containers. 2. The molding method according to claim 1, wherein the passage cross section of the large-diameter hollow needle is 3 to 15 times the passage cross-sectional area of the small-diameter hollow needle. 3. After piercing a small diameter hollow needle into a parison,
The molding method according to claim 1, wherein a large-diameter hollow needle is pierced after 0.5 to 2 seconds. 4. The molding method according to claim 1, wherein the blowing of the fluid by the large-diameter hollow needle is performed at least in the axial direction of the hollow container in the direction in which the body portion exists. 5. A small-diameter hollow needle is pierced and a fluid is blown to expand a portion of the large-diameter hollow needle to be pierced to a large diameter, and the large-diameter hollow needle is pierced into the expanded portion to blow a fluid. The molding method according to claim 1. 6. A pair of split molds provided inside a mold for forming a hollow container and a flash part, and a parison pinch-off part and provided so as to be openable and closable; a part corresponding to the flash part of the split mold. A relatively small-diameter hollow needle and a relatively large-diameter hollow needle; and a hollow needle for advancing each of the hollow needles from a standby position to an operating position for piercing a parison and retracting the hollow needle from the operating position to the standby position. A pressurized fluid supply mechanism for supplying a pressurized fluid to each of them; and an exhaust port forming mechanism for forming an exhaust port in the parison at the end of expansion of the parison provided in a portion corresponding to the split mold flash section. ; Small and large diameter hollow needles are first advanced to inject the fluid first, and then the large and small diameter hollow needles are advanced by advancing the large diameter hollow needle to inject the fluid. Molding apparatus hollow container, characterized in that it consists of; control mechanism for controlling the operations and. 7. A small-diameter and a large-diameter hollow needle drive device is composed of a fluid cylinder connected to a pressurized fluid supply mechanism, and advancement of the fluid cylinder enables supply of pressurized fluid to each hollow needle. 7. The molding apparatus according to claim 6, which is associated with a pressurized fluid supply mechanism. 8. The molding apparatus according to claim 7, wherein the large-diameter hollow needle has a fluid-blowing opening that is open at least in the axial direction of the hollow container and in the direction in which the body portion is present. 9. The molding apparatus according to claim 7, wherein the drive devices for the large-diameter and small-diameter hollow needles are arranged such that the hollow needles can move in parallel. 10. The molding apparatus according to claim 7, wherein the driving devices for the large-diameter and small-diameter hollow needles are arranged so that the moving directions of the hollow needles intersect with each other when viewed in a projected cross section perpendicular to the container axis direction. . 11. The molding apparatus according to claim 7, wherein the large-diameter hollow needle is arranged so as to be located closer to the pinch-off portion at the position of piercing the parison than the small-diameter hollow needle.