JPH047691B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides a method for arranging a parison between split molds and then clamping the molds, and then using a blowing nozzle arranged in a direction intersecting the parting line of the split molds. The present invention relates to a blow molding method in which compressed gas is blown into the parison to form the parison into a shape that follows a cavity in a split mold.

Conventional technology In conventional blow molding methods of this type, compressed gas is blown into the parison by protruding a blowing nozzle into the cavity and sticking it into the parison, and by sucking and fixing the outer surface of the parison with an intake nozzle. There is a method in which a blowing nozzle placed at the axial center of the suction nozzle is inserted into the parison.

Problems to be Solved by the Invention The former method above is the most commonly used method, but when the blowing nozzle breaks through the parison, the parison deforms and escapes, making it difficult to penetrate the parison properly. This caused molding defects.

The latter is a technique known from Japanese Patent Publication No. 38-11831, and while this method solves the above-mentioned problems of the former, it also has the following problems.

In other words, in order to bring the tip of the intake nozzle closer to the parison, the intake nozzle was fixed in a state protruding into the cavity, so when the blow ratio is large, the expanding parison moves to the rear side of the intake nozzle. The part that abuts the tip of the intake nozzle is extremely thin and a hole is formed in this part, allowing compressed gas to enter between the parison and the cavity, resulting in molding defects.

Furthermore, if a large-diameter parison is used and both sides of the parison are sandwiched between split molds, the parison becomes flat and moves away from the cavity surface on which the suction nozzle is protruded, so the suction nozzle must protrude into the cavity by that amount. Not only that, but the above problem is further exacerbated.

Means and Effects for Solving the Problems The present invention has been made in view of the above, and includes a blowing nozzle which has a suction part around the blowing part and is provided so as to be retractable from the cavity.
The parison in the split mold is protruded into the cavity and clamped at the tip of the parison, which is sucked by the suction force of the suction section, and then the blowing nozzle is retracted until the tip of the nozzle is located within the cavity surface. After that, compressed gas is blown into the parison from the blowing part to perform blow molding. The tip of the blow nozzle does not protrude into the cavity during filling.

Example Embodiments of the present invention will be described based on the drawings.

In the figure, 1 and 2 are divided molds, 3 is a parison extruded between the two divided molds 1 and 2, and 4 is a blowing nozzle that blows compressed gas into the parison 3 after mold clamping. The nozzle 4 is placed in one of the split molds 2,
It is arranged in a direction perpendicular to the parting line, and its tip is slidably fitted in and out of the cavity 2a. 5 is a cylinder device for sliding the blow nozzle 4.

The above-mentioned blowing nozzle 4 is constructed as shown in FIGS. 2 and 3, and has a blowing part 6 at the axial center and a suction part 7 around this, each having a blowing pipe 8. , connected to the suction tube 9. The blow pipe 8 and the suction pipe 9 are led out through the split mold 2 and connected to a compressed gas supply device and a suction device (not shown).

Examples of steps of the method of the present invention using the above-mentioned apparatus will be described below.

(a) Parison arrangement (Figure 4) Parison 3 is suspended between the two split molds 1 and 2 in the open state.

(b) Mold clamping (Fig. 5) The two split molds 1 and 2 are clamped, and at the same time, the blowing nozzle 4 is protruded and its tip is brought into contact with the outer surface of the parison 3.

(c) Moving the parison (Fig. 6) After the mold clamping is completed, the parison 3 is sucked from the suction part 7 of the blowing nozzle 4 and placed at the tip of the blowing nozzle 4.
adsorbs. In this state, the blow nozzle 4 is moved back to a position where its tip coincides with the cavity surface, and the parison 3 is moved accordingly.

(d) Blowing (Figures 7 and 8) When compressed gas is blown from the blowing part 6 with the parison 3 adsorbed to the tip of the blow nozzle 4, this compressed gas presses the parison 3. It breaks through and is blown into Parison 3, causing it to expand.

(e) Mold release After expansion molding in the split molds 1 and 2, the mold is kept cool for a certain period of time, then the suction and blowing at the blow nozzle 4 is stopped, the pressure inside the parison is released, and the mold is opened. . In the above process, a molded product is formed from the parison along the cavities of the split molds 1 and 2, but as another example of the process, the blowing nozzle 4 may be made to protrude before the molds are clamped.

In addition, as another embodiment of the blowing nozzle 4, the blowing part 6 can be protruded from the suction part 7 as a needle, and the blowing part 6 can be protruded from the suction part 7, and the parison can be drawn by the blowing part 6. You may try to break through it.

Further, the tip of the blowing nozzle 4 is set back to a position flush with the cavity or recessed from the cavity surface. In particular, if the blow nozzle 4 is retracted to a position slightly recessed from the cavity surface, the area around the blow hole of the molded product will bulge, so when closing the blow hole after blow molding, this bulge will The portion can be easily closed by melting and moving the portion with a heating element or the like.

Effects of the Invention According to the present invention, gas is blown while the tip of the blowing nozzle 4 is always adsorbed on the outer surface of the parison 3 in the cavity. It is possible to reliably perform the embedding without the parison 3 escaping.

In addition, a blowing nozzle 4 having a suction part 7 at the tip
is made to protrude into the cavity, and the parison 3 is adsorbed to the tip by the adsorption force of the suction part 7, so that the parison 3 can be adsorbed to the suction part of the blowing nozzle 4 even with a small amount of suction air. Moreover, by retracting the blow nozzle 4 in this state until its tip is located within the cavity surface, the suction capacity of the suction device can be reduced, and the suction of the parison 3 and the cavity can be reduced. It is possible to move to the surface in a short time and efficiently.

Furthermore, since the tip of the blowing nozzle 4 does not protrude beyond the cavity 2a when blowing gas, the parison 3 can be uniformly expanded and molded without being hindered by the blowing nozzle 4.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a cross-sectional view showing the mold in an open state, FIG. 2 is a cross-sectional view showing the main parts of the gas blowing device, and FIG.
The cross-sectional view and FIGS. 4 to 8 are explanatory diagrams showing the blow molding process. 1 and 2 are split molds, 3 is a parison, 4 is a blowing nozzle, 6 is a blowing part, and 7 is a suction part.

Claims (1)

[Claims] 1 Blow molding in which a parison is placed between the split molds 1 and 2, the mold is clamped, and then compressed gas is blown into the parison from a blowing nozzle placed in a direction intersecting the parting line in the split mold. In this method, a blowing nozzle 4 having a suction part 7 around a blowing part 6 and provided so as to be able to move in and out of the cavity is made to protrude into the cavity, and a mold-clamped divided part is attached to the tip of the blowing nozzle 4, which has a suction part 7 around the blowing part 6 and is provided so as to be able to move in and out of the cavity. The parison 3 located between the molds 1 and 2 is sucked by the suction force of the suction part 7, and then the blowing nozzle 4 is retreated until its tip is located within the cavity surface, and then the blowing part 6
A blow molding method characterized in that blow molding is performed by blowing compressed gas into the parison 3.