JPH06182866A - Blow pin for molding hollow part - Google Patents

Abstract

PURPOSE:To uniformly cool a parison by injecting fluid in a suitable direction and to smoothly discharge the fluid of high pressure in the parison from an injection port to an exterior. CONSTITUTION:A sharp inserting part 23 is formed at an end of a blowing tube 7. An injection port 26 having an area of a sectional area or more of a channel 24 is formed at the vicinity of an end of the tube 7. The tube 7 is longitudinally driven by an air cylinder unit, and inserted into a parison 4 mounted in a mold 1 for molding a hollow part. Fluid is guided and diffused by an inclined and extended bent short passage 25, and injected from the port 26 into the parison 4 to form a hollow product. Then, the fluid in the parison 4 is discharged via the port 26 to reduce a pressure therein. Thus, clogging of the port 26 by adherence of gas, resin, etc., scarcely occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding blow pin for jetting a fluid into a parison in blow molding.

[0002]

2. Description of the Related Art Heretofore, in blow molding, a blow pin has been used which is inserted into a parison mounted on a blow molding die and injects fluid such as air into the parison.

As this type of blow pin, for example, as described in Japanese Patent Laid-Open No. 1-320133, the injection port is opened and closed at an injection port opened at the tip of a tubular blow tube. A configuration supporting a cap body is known. The cap body is elastically supported by a spring body so as to be able to advance and retreat, and has a conical shape with a sharp tip at the tip side, and is pierced into the parison when the blow pin advances. In addition, the rear end side of the cap body,
When the fluid is not jetted, it has a conical shape that is sharpened toward the blow pipe side, and when the fluid is jetted, it is fitted into the jet port of the blow pipe by the urging force of the spring body to close the jet port. By advancing by the pressure of the fluid, the injection port of the blow tube is opened, the fluid is radially dispersed in the parison, and the parison is uniformly cooled.

Further, as described in, for example, Japanese Utility Model Laid-Open No. 4-104430, a blow tube having a sharp tip in a bullet shape is used and a fluid is jetted to a side wall portion near the tip of the blow tube. A configuration is known in which a plurality of small-hole-shaped injection ports are formed.

[0005]

By the way, a fluid is ejected from the ejection port of the blow pin to fill the fluid in the parison, and the hollow product is molded and cooled. A pressure higher than the atmospheric pressure, such as -10 kg / cm ² , is applied. Therefore, after injecting the fluid from the blow pin injection port, it is desirable to discharge the fluid inside the hollow product to the outside from the blow pin injection port and smoothly reduce the pressure inside the hollow product to normal pressure. .

However, for example, Japanese Patent Laid-Open No. 1-3201
The blow pin of Japanese Unexamined Patent Publication No. 33-33 has a problem that the internal fluid cannot be discharged from the blow pin jet port after molding the hollow product because the blow port jet port is closed by the cap body when the fluid is not jetted. There is.

Further, for example, in the blow pin of Japanese Utility Model Laid-Open No. 4-104430, since small hole-shaped injection ports are formed at a plurality of locations on the side wall near the tip of the blow pipe, the diameter of each injection port is different. Get smaller. Therefore, when the fluid is discharged from these injection ports to the outside, there is a problem that gas, tars, etc. inside the parison adhere to each injection port, and these injection ports are likely to be blocked after long-term use. is doing.

The present invention has been made in view of the above circumstances, and a blow molding blow pin capable of ejecting a fluid in an appropriate direction to uniformly cool a parison and smoothly discharging the fluid to the outside. The purpose is to provide.

[0009]

The blow pin for blow molding of the present invention is driven back and forth along the axial direction by a driving means, and is inserted into a parison attached to a blow mold to be inserted into the parison. In a blow molding blow pin for injecting a fluid, this blow molding blow pin has a sharp insertion portion formed at an axial tip end thereof, and a flow passage through which a fluid flows is formed at an inner portion thereof. An injection port communicating with the outside is opened in a predetermined direction intersecting the axial direction of the blow pin, and the area of the injection port is equal to or larger than the cross-sectional area of the flow passage in the direction orthogonal to the axial direction of the blow pin. It is formed, and the fluid in the parison is ejected while the fluid is ejected into the parison through this ejection port.

[0010]

The blow pin for blow molding according to the present invention is driven by the driving means and inserted into the parison mounted in the blow mold. Then, the fluid is ejected in a predetermined direction from the ejection port inserted in the parison. This fluid is injected in a predetermined direction intersecting the axial direction of the blow molding blow pin, and the parison is cooled while maintaining a constant temperature distribution as a whole to form a hollow product. After the hollow product is formed, the fluid injected into the parison is discharged to the outside through the injection port. Since the area of this injection port is formed to be larger than the cross-sectional area of the flow passage in the direction orthogonal to the axial direction of the blow pin, when discharging the fluid in the parison, gas, tar, etc. in the parison will be discharged to the injection port. Even if it adheres, the injection port is difficult to close.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of one embodiment of the blow molding blow pin of the present invention will be described below with reference to the drawings.

In FIG. 1 and FIG. 2, reference numeral 1 denotes a hollow molding die, which is composed of a cavity mold 2 and a core mold 3 which can be opened and closed. A cavity 5 in which the parison 4 is mounted is formed between the mold 3 and the mold 3. An air cylinder device 6 as a driving means is incorporated in the core die 3, and a blow pipe 7 constituting a blow molding blow pin is supported by the air cylinder device 6 so as to be able to move forward and backward. It is configured to project in and out of the cavity 5.

The air cylinder device 6 has a piston body (not shown) therein, and the piston body is supplied with air pressure from an air source through a pair of flow pipes 11 and 12 and a solenoid valve (not shown). It is designed to be driven back and forth in the forward and backward directions.

Further, a rod portion 14 is provided so as to project from the piston body toward the front side, and a cylindrical bolt 15 is tightened at the tip portion of the rod portion 14 to fix the base end portion of the blow pipe 7. Has been done. In addition, the blow pipe 7 is a core type 3
It is slidably penetrated through the through hole 3a formed in the above, and is driven forward and backward in the forward and backward direction as the piston body advances and retracts.

As shown in FIGS. 1 to 3, the blow tube 7 has a substantially columnar shape, and has an elliptical inclined surface portion 22 cut at a tip portion thereof in a direction inclined with respect to the axial direction.
Is formed, and the tip of the inclined surface portion 22 has a sharp insertion portion 23.
It has become.

Along the axial center of the blow tube 7,
A flow passage 24 that opens to the base end side is formed. The flow passage 24 is bent near the tip of the blow pipe 7,
A short bend 25 in a direction inclined with respect to the longitudinal direction of 24
Through, through an elliptical injection port 26 formed in the inclined surface portion 22. Further, the curved short path 25 is expanded in a tapered shape toward the injection port 26, and the inclined surface portion 22 of the injection port 26 is formed.
The upper area is formed larger than the cross-sectional area of the flow passage 24 cut in the direction orthogonal to the axial direction of the blow pipe 7.

On the other hand, the base end side of the flow passage 24 of the blow pipe 7 is
It is connected to a communication passage (not shown) formed in the rod portion 14 of the piston body, and this communication passage is communicated with the flow pipe 28 connected to the air cylinder device 6 when the piston body is located at the forward limit. A fluid such as air is press-fitted from an air source connected to the flow pipe 28. Also,
An electromagnetic valve or the like (not shown) is connected to the distribution pipe 28 so that the distribution pipe 28 can be opened to the outside air.

Next, the operation of the above-described embodiment at the time of hollow molding will be described.

First, with the parison 4 extruded from a die (not shown) being lowered between the cavity mold 2 and the core mold 3, as shown in FIG.
Then, the parison 4 is mounted in the cavity 5. At this point, the piston body supporting the blow pipe 7 is in the retracted limit, and the blow pipe 7 is housed in the through hole 3a formed in the core mold 3.

Next, when air is press-fitted into the air cylinder device 6 through the flow pipe 11, the blow pipe 7 advances together with the piston body, and the insertion portion provided at the tip of the blow pipe 7
23 pierces the parison 4, and the tip side of the blow tube 7 is inserted into the parison 4.

Then, after the blow pipe 7 is positioned at the forward limit, by the action of a solenoid valve or the like, through the flow pipe 28 or the like,
A fluid such as air is pressed into the flow passage 24 of the blow pipe 7.
This fluid is guided by the bent short path 25 so that it is not directly sprayed on the inner surface opposite the parison 4,
The parison 4 is bent in a predetermined direction toward the longitudinal direction, diffused by the tapered inner surface of the bent short path 25, and discharged from the injection port 26 into the parison 4.

In this way, the parison 4 is uniformly filled with the fluid, the parison 4 expands in the cavity 5 into a predetermined shape, and the parison 4 as a whole is
It is cooled while maintaining a constant temperature distribution.

When the parison 4 is cooled in this way to form a hollow product, the inside of the hollow product is, for example, 7
It is maintained at a pressure higher than atmospheric pressure, such as -10 kg / cm ² . Therefore, when the solenoid valve is operated to open the flow pipe 28 to the outside air, the flow passage of the blow pipe 7 is passed through the flow pipe 28.
24 and the injection port 26 are communicated with the outside air. In this state, the high-pressure fluid inside the hollow product is discharged to the outside from the injection port 26 of the blow pipe 7, and the pressure inside the hollow product is smoothly reduced to the atmospheric pressure of the outside air.

Next, when air is pressed into the air cylinder device 6 through the flow pipe 12, the blow pipe 7 moves backward together with the piston body, and the blow pipe 7 is housed in the through hole 3a formed in the core mold 3. It

Further, according to the present embodiment, the injected fluid is guided while being diffused in the proper direction by the bent short path 25, so that the fluid is not concentrated and sprayed on a part of the parison 4. The parison 4 is uniformly filled with the fluid. Therefore, even if so-called lateral blowing is performed, the parison 4 is cooled while maintaining a constant temperature distribution as a whole, so that inconveniences such as sink marks, diaphragm reversal defects, and shrinkage errors are prevented. can do.

Further, since the high-pressure fluid inside the hollow product is discharged to the outside from the injection port 26 of the blow pipe 7, the pressure inside the hollow product can be smoothly reduced to the atmospheric pressure of the outside air, so that the quality of the hollow product is improved. You can At this time, only one injection port 26 of the blow pipe 7 is formed, and since the area of this injection port 26 is formed larger than the cross-sectional area of the flow passage 24 of the blow pipe 7, the injection port 26 is formed on the tip surface of the conventional case. The discharge efficiency does not decrease as compared with the straight tubular blow pin formed with the above, and when the fluid is discharged from the injection port 26 to the outside, the gas, the resin, etc. inside the parison 4 adhere to the injection port 26 and block it. This can be suppressed, and the fluid inside the hollow product can be discharged stably and smoothly over a long period of time.

Further, at the tip of the blow tube 7, there is a sharply inserted portion 23 cut in a direction inclined with respect to the axial direction.
Since it is formed, the parison 4 can be easily pierced and inserted into the parison 4.

In the above embodiment, the injection port 26 is formed on the inclined surface portion 22 formed at the tip of the blow pipe 7. However, as shown in FIG. 4, for example, at the base end side of the inclined surface portion 22. It is also possible to bend the flow passage 24 and form a substantially elliptical injection port 31 on the side wall portion of the blow pipe 7 located on the base end side of the inclined surface portion 22. Further, as shown in FIG. 5, the flow passage 24 may be bent on the opposite side of the inclined surface portion 22 and the substantially oval injection port 32 may be formed on the side wall portion on the opposite side of the inclined surface portion 22.

In this way, the injection port is formed in the side wall portion facing in the direction orthogonal to the axial direction of the blow pipe 7, that is, the insertion direction.
By forming 31 and 32, the blow pipe 7 is moved to the parison 4
It is possible to prevent a part of the parison 4 from adhering to the injection ports 31 and 32 when it is inserted into the.

The fluid jetted from the blow pipe 7 includes, for example, only air, air and cooling water. In addition, after injecting air, it may be cooled by switching to a cooling gas such as CO ₂ , N, or NO ₂ .

[0031]

According to the blow molding blow pin of the present invention, since the fluid injected from the injection port inserted in the parison is injected in a predetermined direction intersecting the axial direction of the blow molding blow pin, the fluid is laterally ejected. Even when blowing is performed, a hollow product can be formed by appropriately dispersing a fluid in the parison and cooling the parison while maintaining a constant temperature distribution as a whole. Therefore, it is possible to prevent inconveniences such as sink marks, defective drawing inversion, and shrinkage errors. Further, after the hollow product is formed, the fluid injected into the parison can be discharged to the outside from the injection port, and the internal pressure can be smoothly reduced. Since the area of this injection port is formed to be larger than the cross-sectional area of the flow passage in the direction orthogonal to the axial direction of the blow pin, when discharging the fluid in the parison, gas, tar, etc. in the parison will be discharged to the injection port. Even if adhered, the injection port is unlikely to be blocked, and the fluid in the parison can be stably discharged for a long time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an entire hollow molding die using a blow molding blow pin of the present invention.

FIG. 2 is a manufacturing process diagram showing the overall hollow molding die.

FIG. 3 (a) is a sectional view showing a blow molding blow pin of the above. (B) It is a side view same as the above.

FIG. 4A is a sectional view showing another embodiment of the blow molding blow pin. (B) It is a side view same as the above.

FIG. 5 (a) is a side view showing still another embodiment of the blow molding blow pin. (B) It is a sectional view same as the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hollow molding die 4 Parison 6 Air cylinder device as driving means 7 Blow pipes 26, 31, 32 injection ports constituting blow molding blow pin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Sano 1 316 Hatada, Maeda, Fuji City, Shizuoka Prefecture Higashiizumi Plast Co., Ltd.

Claims (1)

[Claims] 1. A blow molding blow pin which is driven back and forth in the axial direction by a drive means and is inserted into a parison mounted on a blow molding die to inject a fluid into the parison. The blow pin for use has a sharp insertion portion formed at the axial tip end and a flow passage through which the fluid flows inside is formed, and the injection port communicating the flow passage and the outside is connected to the blow pin shaft. Is opened in a predetermined direction intersecting with the direction, and the area of the injection port is formed to be larger than the cross-sectional area of the flow passage in the direction orthogonal to the axial direction of the blow pin, and the fluid is introduced into the parison through the injection port. A blow molding blow pin for ejecting the fluid and discharging the fluid in the parison.