JPH0533316Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an injection blow molding mold for forming blow molded products such as bellows boots used as parts of automobile steering wheels.

[Prior Art] Traditionally, injection blow molding molds have been designed to prevent air leakage from the parison during blow molding, and
To ensure internal pressure, core rods are used during injection molding to cool and solidify the front and rear ends of the parison. Then, the parison is used to perform blow molding to produce a hollow molded product.

[Problems to be solved by the invention] However, in the conventional injection blow molding described above, when the cycle time is short or the sprue diameter is large, the parison in the sprue part is not completely cooled and solidified. As shown in FIG. 5, during blow molding, the internal pressure of the parison P in the blow molds 22a and 22b increases, so that the parison P in the sprue part that has not been completely cooled is pushed out, and a through hole 21 is formed. Then, the air inside the parison P leaks from the through hole 21, and the internal pressure of the parison P decreases below a predetermined value. There was a problem with this.

The purpose of this invention is to solve the above problems, and to prevent air leakage from a part of the parison formed by the sprue, to maintain the internal pressure of the parison, and to prevent material from flowing out. The purpose is to provide a model.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an injection blow molding mold for molding a parison formed by an injection mold using a blow mold, A configuration in which a pressing part for crushing a part of the parison formed by the sprue part is provided in a housing part of the blow mold that accommodates a part of the parison formed by the sprue part of the mold. is adopted.

[Function] By adopting the above configuration, the parison molded by the injection mold is placed in the blow mold, and when the blow mold is closed, the parison is attached to the sprue part of the injection mold. The parison thus formed is crushed by the pressing part of the blow mold, and then air pressure is applied inside the parison, and the parison maintains a predetermined internal pressure without causing air leakage or material outflow. Blow molding is performed smoothly and a molded product is manufactured.

[Example] An example embodying the present invention will be described below with reference to FIGS. 1 and 2.

First, the injection mold for molding the parison will be explained.

As shown in Figure 2, two injection molds 1a, 1b
A core rod 2 having a symmetrical shape with respect to the mold cracking surface (PL surface) is removably installed inside the mold. A cavity 3 is formed by the injection molds 1a, 1b and the core rod 2, and a parison P of a predetermined shape is molded within the cavity 3.

At the tip of the cavity 3 (left side in Figure 2),
A sprue portion 4 is provided through which resin is injected. At the tip of the cavity 3 and the outer periphery of the sprue section 4,
Cooling inserts 5a and 5b are provided so that the tip of the cavity 3 and a portion of the parison P in the sprue portion 4 can be cooled after injection molding. In addition, at the rear end of cavity 3 (right side in Figure 2),
Cooling inserts 6a and 6b are provided to cool the rear end of the parison P after injection molding. In addition, approximately in the center of the core rod 2,
An air blowing port 7 opened at the outer periphery is provided to blow air into the parison P during blow molding, which will be described later.

Next, a blow mold for forming a blow molded product using the parison P formed by the injection mold will be described.

As shown in FIG. 1, two blow molds 8a, 8
The PL surface formed by b is provided with a hole 9 into which the core rod 2 of the injection mold is inserted and removed. Moreover, the sprue portion 4 of the injection molds 1a and 1b
Protrusions 10a, 10b as pressing portions are provided approximately at the center of the holes 9a as accommodating portions of the blow molds 8a, 8b that accommodate a part of the parison P formed by the blow molds 8a, 8b.
is provided, and a part of the parison P is placed in a blow mold 8.
It is designed so that it can be crushed when the molds a and 8b are closed. The diameter of the hole 9a is about 7 mm, and the height of the projections 10a, 10b is about 2 mm.

The functions and effects of the injection blow molding mold using the injection mold and blow mold configured as described above will be explained.

First, the formation of parison P by injection molding using injection molds 1a and 1b will be described.

As shown in FIG. 2, the injection molds 1a and 1b are closed, and the core rod 2 is inserted between the two injection molds 1a and 1b. At this time, a cavity 3 is formed by both injection molds 1a and 1b and the core rod 2. In this state, melted resin such as urethane resin is applied to the sprue portion 4.
eject from. Then, the resin reaches the rear end of the cavity 3 from the sprue portion 4 through the tip of the cavity 3.

After the resin injection is completed, the cooling inserts 5a, 5b
Cooling water is injected into 6a and 6b to cool the parison P formed in the cavity 3. Thereafter, both injection molds 1a and 1b are opened. In this way, the parison P is molded so as to adhere to the outer periphery of the core rod 2.

Next, blow molding using the blow molds 8a and 8b will be explained.

The parison P attached to the outer periphery of the core rod 2 is placed on the PL surface of the blow molds 8a and 8b. Subsequently, the blow molds 8a and 8b are closed. Then, as shown in FIG.
The protrusions 10a and 10b each crush a portion of the parison P formed by the sprue portions 4 of the injection molds 1a and 1b by about 2 mm. At this time, if the amount of crushing is too large, a part of the crushed parison P will enter the PL surface, creating a gap on the PL surface and hindering blow molding. On the other hand, if the amount of crushing is too small, the Air leaks from part of parison P.

Next, in this state, the core rod 2 is moved backward, and air is blown into the core rod 2 from an air inlet 7 (not shown) to perform blow molding. At this time, a part of the parison P formed by the sprue part 4 is crushed by the protrusions 10a and 10b, so the crushed part becomes thinner, improving cooling efficiency and solidifying. . Therefore, a portion of the parison P is sufficiently cooled and solidified to withstand the internal pressure of the parison P, so that air leakage from the parison P is prevented and the internal pressure of the parison P is maintained. Further, a part of the parison P does not leak out.

After blow molding, a molded product is obtained by opening the blow molds 8a and 8b and further retracting the core rod 2.

As described above, according to this embodiment, holes are not formed in a part of the parison P formed by the sprue portions 4 of the injection molds 1a and 1b during blow molding, unlike in the conventional case. The internal pressure is maintained at a predetermined value and no material loss occurs.

The present invention is not limited to the above embodiments, but may be configured as follows.

(1) Projection part 1 as a pressing part in the above embodiment
The shape of 0a and 10b may be any shape as long as it can crush a portion of the parison P by an appropriate amount depending on conditions such as the cycle time of blow molding, and may have a triangular cross-section, a semicircular cross-section, etc. in addition to a square cross-section. It may be in the shape of

(2) Also, the protrusions 10a and 10b as pressing parts
As shown in FIG. 3, both blow molds 8a, 8
Female screw holes 12a, 12b are provided in b, and hollow screws 11a, 11b are provided in the same female screw holes 12a, 12b.
It is also possible to form a hole 9a by screwing it into the hole 9a and having a portion thereof protrude into a portion of the hole 9a. Same hollow screw 1
The diameters of 1a and 11b are made 1 to 2 mm larger than the diameter of the parison P formed by the sprue portion 4, so that a part of the crushed parison P is absorbed by the screw hole and does not flow into the PL surface. good.

In this case, hollow screws 11a, 1 to hole 9a
The amount of protrusion of 1b can be arbitrarily adjusted by screwing in or out the same hollow screws 11a and 11b, so it can be adjusted to variations in the blow molding cycle time, etc. Incidentally, the hollow screws 11a and 11b can be easily screwed in or out by turning a hexagonal hole (not shown) provided in the end face with a hexagonal wrench.

(3) Furthermore, the protrusions 10a and 10 as pressing parts
b, as shown in FIG. 4, both blow molds 8a,
Holes 13a, 13b are provided in 8b, and the same holes 13a,
It can also be formed by inserting pins 14a, 14b having a T-shaped cross section into 13b. A spring 15a is located deep inside the pins 14a and 14b.
15b, and use the blind screw 16 to attach the blow mold 8a,
Fix it to 8b.

In this case, a certain pressing force can be applied to a part of the parison P formed by the sprue section 4 by the forces of the springs 15a and 15b. Note that this device uses springs 15a, 15
b. Since members such as blind screws 16 are used, this method is adopted when sufficient space can be secured within the blow molds 8a and 8b.

(4) The injection blow molding mold of the present invention is suitably used as a mold for molding blow molded products such as rack and pinion boots and pin boots as automobile parts.

[Effects of the invention] The injection blow molding mold of the invention can prevent air leakage from a part of the parison formed by the sprue, maintain the internal pressure of the parison, and prevent material from flowing out. be effective.

[Brief explanation of the drawing]

Figures 1 and 2 are views showing an embodiment of the present invention, and Figure 1 shows a state in which a part of the parison formed by the sprue part of the injection mold is crushed by the pressing part of the blow mold. 2 is a sectional view showing the molding state of a parison in an injection mold, FIGS. 3 and 4 are sectional views of a blow mold showing another example of the present invention,
FIG. 5 is a sectional view showing a conventional blow mold. 1a, 1b...Injection mold, 4...Sprue part, 8
a, 8b...blow mold, 9a...hole as a housing part, 10a, 10b...protrusion part as a pressing part,
11a, 11b... Hollow screws as pressing parts,
14a, 14b...Pin as a pressing part, P...
Parison.

Claims (1)

[Scope of utility model registration request] This is an injection blow molding mold for molding a parison P molded by injection molds 1a, 1b using blow molds 8a, 8b, the injection molds 1a,
A part of the parison P formed by the sprue part 4 is crushed into the accommodation part 9a of the blow mold 8a, 8b which accommodates a part of the parison P formed by the sprue part 4 of 1b. Pressing part 1 for
0a, 10b, 11a, 11b, 14a, 14b
An injection blow molding mold characterized by being provided with.