JP2760369B2 - Method and apparatus for forming hollow container - Google Patents

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 method for molding a hollow container which is capable of efficiently performing expansion of a parison and cooling of a blow molded container and having excellent production efficiency. The present invention relates to a molding method and a molding apparatus.

[0002]

2. Description of the Related Art It has been conventionally practiced to form a hollow container of a thermoplastic synthetic resin 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 size. In the above molding method, in order to penetrate the parison with a hollow needle for putting a fluid inside the parison, it is difficult to pierce the parison with a thick needle because the parison held in the split mold is relatively high temperature and soft. A hollow needle having a thin and sharp tip must be used.

[0003]

However, when a thin needle is used as the hollow needle for injecting a fluid into the parison, the amount of fluid that can flow into the parison per unit time is small, and the molding is difficult. There was a problem that it took time. In addition, with this small amount of fluid, it is possible to expand the parison at best, and it is difficult to cool the expanded hollow body. Even if a small-capacity container can be formed, a large-capacity container can be formed. The container could not be molded.

On the other hand, in direct blow molding,
An unnecessary part called a flash part, which is cut off after molding, is formed at the upper part of the part to be the mouth part of the molded 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 By providing, it is possible to leave no trace on the molded container. However, in the case where a fluid is blown by piercing a hollow needle into this portion, it is preferable that the fluid be made to flow easily in the direction of the container body, that is, below 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 that 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. Therefore, there is a problem that it takes a lot of time to cool the container because a large amount of cooling fluid cannot be blown.

Accordingly, it is an object of the present invention to provide a method and apparatus for direct blow molding of a hollow container in which fluid can be blown in using a large-diameter hollow needle.
Another object of the present invention is to provide a method and an apparatus for molding a hollow container with good 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 a parison having both ends sealed, and a fluid is blown into the parison hollow body. In the method of forming a hollow container in which the hollow body is cooled by cooling the hollow body by forming an exhaust port in the hollow body following the expansion by the circulation of the fluid, a relatively small diameter hollow needle and a relatively large diameter are used. The hollow needle is arranged in a split mold, a small diameter hollow needle is inserted into a parison that is confined in the split mold, and both ends are sealed, and fluid is blown into the parison. A method for forming a hollow container is provided, wherein a fluid is blown at a large flow rate by piercing a hollow needle.

According to the present invention, there is also provided a pair of split dies which are provided with a cavity for forming a hollow container and a flash portion inside the die, and a pinch-off portion of a parison and are provided so as to be openable and closable; A relatively small-diameter hollow needle and a relatively large-diameter hollow needle provided in a portion corresponding to
A pressurized fluid supply mechanism for supplying pressurized fluid to each of the hollow needles that advances each of the hollow needles from a standby position to an operating position for piercing the parison and retracts 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 the expansion of the parison provided in a portion corresponding to the flash portion; a small-diameter hollow needle is first advanced to blow fluid first, and then the timing is adjusted. A control mechanism for controlling the operation of the large-diameter and small-diameter hollow needles such that the large-diameter hollow needle is shifted to advance and blow fluid. .

[0008]

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

That is, since the parison wall is relatively high temperature and soft, a large-diameter hollow needle cannot penetrate directly into the parison wall. However, first, a small-diameter hollow needle is pierced to blow a fluid into the parison to reduce the internal pressure. When applied, the parison becomes elastic, so that after a short time has passed after piercing the small-diameter hollow needle, it becomes possible to pierce the large-diameter hollow needle. As described above, in the present invention, it becomes possible to use a large-diameter needle, so that a large volume of fluid can be blown into the parison. Becomes possible,
It is possible to improve the molding cycle.
In addition, since a large volume of fluid can be blown, a large bottle can be formed.

[0010]

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 showing an example of the apparatus for manufacturing a hollow molded container according to the present invention, a pair of split molds 1a and 1b that can be opened and closed are each provided with a pinch-off portion 3 that seals a parison 2.
a, 3b, a cavity 4 forming a hollow container, and a cavity 5 forming a flash portion. In the present invention, the flush portion is a portion provided above the mouth of the hollow container to be formed, for piercing a hollow needle for blowing fluid, or for providing an exhaust port and the like. Since the flush portion is cut off after blow molding, it is possible to leave no trace of the manufacturing process such as a hole through which a hollow needle is inserted in the container. In a portion of the cavity 5 corresponding to the flash portion, a relatively small-diameter hollow needle 6 and a large-diameter hollow needle 7 thereunder are located in a standby state. Further, an exhaust port forming mechanism 8 for forming an exhaust port in the parison at the end of the parison expansion and a knockout pin 9 for taking out the formed hollow container from the mold to a predetermined position are provided.

The small-diameter hollow needle 6 and the large-diameter hollow needle 7 can be advanced or retracted from a standby position shown in FIG. 1 to an operation position pierced by the parison shown in FIG. This operation can be performed simultaneously 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 a fluid supplied from a source of pressurized fluid (not shown) through the pressurized fluid supply mechanism 10 is used for the movement operation of the pressurized fluid supply mechanism or supplied into the parison. Are provided respectively.

The movement of the 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 cylinders 13a and 13b provided in the driving devices 12a and 12b, and can move back and forth inside thereof. ing. Cylinder 1
Supply ports 14 and 15 for supplying a pressurized fluid are provided on the sides of 3a and 13b, respectively. Of these supply ports, 14a and 14b are connected to the cylinders 13a and 1b.
3b leads to the front side. In addition, supply ports 15a and 15b
Flows to the rear side of the cylinder, and the fluid supplied from this supply port flows inside the hollow needle or flows so as to push forward from behind the hollow needle.

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 backward, the hollow needles 6 and 7 are located rearward. In FIG. 4, the supply of the fluid is stopped from the supply port 14a, and the fluid is supplied from the supply port 15a instead. Thereby, the small-diameter hollow needle 6 moves forward (parison side) and pierces the parison, and the fluid flowing through the inside of the hollow needle is blown into the parison. On the other hand, the large-diameter hollow needle 7 does not move yet because the fluid is supplied from the supply port 14b as in the state of FIG. In FIG. 5, the supply of the 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 starts blowing the fluid into the parison. In FIG. 6, the supply port 14a
And during or after the supply of fluid from 15a,
The fluid is supplied from the supply port 15b, and the fluid is blown into the parison through the large-diameter hollow needle 7, thereby cooling the container.

FIGS. 7 and 8 for explaining a pressurized fluid supply mechanism and a control mechanism for small diameter and large diameter hollow needles.
The small-diameter hollow needle and the large-diameter hollow needle are first inserted into the parison by inserting the small-diameter hollow needle into the parison to apply fluid to the parison. The operation of the hollow needle and the large-diameter hollow needle and the blowing of the fluid can be controlled by using a cam as shown in FIG. 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 diagram on the left side is a diagram when (A) and (B) are viewed from the side. In the cams 16a and 16b rotating in the direction of the arrow in the figure, the small-diameter hollow needle and the large-diameter hollow needle do not move from the 0 ° point, which is the completion point of mold closing, to the point A in the figure. Is reached, the small-diameter hollow needle is pierced into the parison, and fluid is blown into the parison only from the small-diameter hollow needle between points A and C to apply an internal pressure. When the point C is reached, the large-diameter hollow needle is pierced into the parison, and between point C and point D, fluid is blown into the parison from the large-diameter hollow needle to cool the inside of the bottle.

FIGS. 3 to 6 show the correspondence of the movement of the cam shown in FIG. 7; FIG. 3 shows the state from 0 ° (mold closing completed) to point A in FIG. 7, and FIG. 4 shows A in FIG. 5 is a state between point C and point C, FIG. 5 is a state between point C and point B in FIG. 7, and FIG.
Respectively correspond to the state between point B and point 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 during which fluid is blown only from the small diameter hollow needle. W is the time during which the fluid is flowing from both the small and large diameter hollow needles, and Q is the time during which the fluid is blown only by the large diameter hollow needle. 360 ° is a 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 of the fluid (L in FIG. 8) 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 is inserted 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 it is longer than this time, there is no merit because the production cycle becomes longer. Further, the time of fluid injection by the large-diameter hollow needle (Q in FIG. 8) is in the range of 5 to 30 seconds, particularly 10 to 20 seconds. After the large-diameter hollow needle is pierced, the fluid is injected from the small-diameter hollow needle. The time until the blowing stops (W in FIG. 8) is 0.2 to 10 seconds, particularly 0.5
It is preferably in the range of 5 to 5 seconds. If the time is shorter than this time, the fluid supplied from the large-diameter hollow needle may flow back through the small-diameter hollow needle, and if it is longer than this time, the production cycle becomes longer and there is no merit. It is.

The control mechanism for controlling the operation of such small and large diameter hollow needles is not limited to this, but a mechanism shown in FIG. 9 can be used. The state shown in FIG. 9 shows that the cams of the small and large diameter hollow needles are both located at 0 °, and that both the pilot valves 17 are not operated. The role of the timer 18 is to allow the blow of the fluid from the small-diameter hollow needle to be repeated even after the blow of the fluid from the large-diameter hollow needle is started. This prevents the fluid in the parison from flowing back through the small diameter hollow needle. In addition, in FIG. 9, 19 is a master valve,
Reference numeral 20 denotes a flow control valve.

At the time when the expansion of the parison is almost completed, a small-diameter exhaust port for circulating the blown air into the parison is formed by inserting a small-diameter and a large-diameter hollow needle into the flash portion, as shown in FIGS. The fluid can be discharged by piercing the nozzle for forming the discharge port as shown in FIG. 2, but as described in Japanese Patent Publication No. 59-3260, the internal pinch-off portion of the split mold has The outlet can also be formed by a pressure fluid. The hollow molded container from which the compressed fluid has been discharged is removed from the mold to a predetermined position on a conveyor or the like by the knockout pin, and the molding of the hollow container is completed.

As the small-diameter hollow needle used in the present invention, a known hollow needle used for direct blow molding can be used. The diameter of the passage cross section varies depending on the size of the hollow container to be molded. Those having a 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 of 3 to 15 times, particularly 4 to 10 times the passage cross section of the small diameter hollow needle. If it is smaller than this range, it is not possible to supply a sufficient fluid for cooling, and if it is larger than this range, it becomes difficult to easily pierce the parison. Unlike large-diameter hollow needles, unlike small-diameter hollow needles, it is possible to process so that the fluid blowing opening is provided at a position other than the tip of the needle, and to provide a fluid blowing opening at the side of the hollow needle Can be. If the blow opening 19 is provided on the side of the hollow needle 7 as shown in FIG. 5, the fluid blown from the large-diameter hollow needle 7 can be supplied in the direction of the body 20 of the parison 2, that is, in the direction of the vertical axis. As a result, it is possible to efficiently circulate the fluid in the parison body. Further, it is preferable that the large-diameter hollow needle 7 inserted into the flash part 5 of the parison is located closer to the parison body than the small-diameter hollow needle 6. Thus, a large volume of fluid blown from the large-diameter hollow needle can be efficiently circulated through the parison body. In the case of a parison, a large diameter hollow needle can be easily pierced by increasing the parison diameter with a fluid blown from the small diameter hollow needle.

As shown in FIG. 5, the driving devices 12a and 12b for the small and large diameter hollow needles are preferably arranged so as to be movable in parallel. Thereby, the control mechanism and the pressurized fluid supply mechanism can be shared, and the apparatus 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 cross each other when viewed in a projected cross section perpendicular to the container axis direction. That is, since the large-diameter and small-diameter hollow needles are positioned at a fixed angle as shown in FIG. 10, the large-diameter and small-diameter hollow needles can be pierced on the same circumference of the flash part of the parison, which is unnecessary. The flash portion, which is a portion, can be made smaller.

The parison that can be used in the present invention is:
A bottomed parison or a tube can be used. At this time, it is described above that the flash portion is provided on the upper portion of the portion to be the container mouth portion, but the projection portion is provided on the portion of the flash portion where the large-diameter hollow needle is to be pierced, so that blow molding In this case, it is particularly preferable because this portion can be made thinner and it becomes easy to pierce. Further, in the molding method of the present invention, as long as the above-mentioned features are provided, it can be performed by conventionally known direct blow molding.

[0022]

EXAMPLES The molten parison extruded from the extruder in a blow mold shown in FIG. 1 (split), carried out for approximately 3 seconds primary blow the cold air blow pressure 6 Kg / cm ² from the small diameter of the hollow needle After about 1 second from the start of the primary blow, secondary air is blown from the large-diameter hollow needle with air at a blow pressure of 8 kg / cm ² for about 9 seconds, and then pressurized air in the container is blown for 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 1.1 times as compared with the conventional blow molding method using one small diameter hollow needle.
The time was reduced by 9 seconds, and the molding cycle was improved by about 60%.

[0023]

According to the present invention, by combining with a small-diameter hollow needle, it is possible to use a large-diameter hollow needle which has been difficult to use in direct blow molding, and to use a large-capacity fluid. It became possible to supply. As a result, a large-capacity container can be formed, the container can be cooled efficiently, and the production cycle can be increased. Further, according to the molding apparatus of the present invention, the movement of the small 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 the drawings]

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

FIG. 2 is a view showing a state where a split mold is closed in FIG. 1;

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

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

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

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

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

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

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

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

[Description of sign]

 1 split mold 2 parison 3 pinch-off section 4 cavity 5 flash section 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)

(57) [Claims] 1. A parison of a molten polymer is sandwiched between a pair of split molds, a hollow needle is pierced into a parison having both ends sealed, and a fluid is blown into the parison to expand the parison into the 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 following the expansion to cool the hollow body, a relatively small-diameter hollow needle and a relatively large-diameter hollow needle are arranged in a split mold. The hollow is characterized in that a small-diameter hollow needle is stabbed into a parison whose both ends are sealed and a fluid is blown, and then a large-diameter hollow needle is stabbed in a state in which internal pressure is applied to the parison and a fluid is blown at a large flow rate Container molding method. 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 section of the small diameter hollow needle. 3. After piercing a parison with a small diameter hollow needle,
2. 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 exists. 5. A large-diameter hollow needle is stabbed to a large diameter by piercing a small-diameter hollow needle and blowing a fluid, and a large-diameter hollow needle is pierced into the expanded portion to blow fluid. The molding method according to claim 1. 6. A pair of split dies provided with a cavity for forming a hollow container and a flush portion inside the mold and a pinch-off portion of a parison and provided so as to be openable and closable; A hollow needle having a relatively small diameter and a hollow needle having a relatively large diameter provided; a hollow needle for advancing each of the hollow needles from a standby position to an operating position for piercing the parison and retracting from the operating position to the standby position; A pressurized fluid supply mechanism for supplying a pressurized fluid to each of them; 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 part of the split mold; A small-diameter hollow needle is advanced first to perform fluid injection, and then a large-diameter hollow needle is advanced to advance a large-diameter hollow needle at a different timing to perform fluid injection. Molding apparatus hollow container, characterized in that it consists of; control mechanism for controlling the operations and. 7. A driving device for small and large diameter hollow needles comprises 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 of claim 6, wherein the molding apparatus is associated with a pressurized fluid supply mechanism. 8. The molding apparatus according to claim 7, wherein the large-diameter hollow needle has an opening for blowing fluid which is opened at least in the axial direction of the hollow container and in the direction in which the body exists. 9. 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 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 cross 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 located at a position closer to the pinch-off portion at the position where the parison pierces the parison than the small-diameter hollow needle.