JP3537481B2 - Blow molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a blow molding method.
More specifically, the present invention relates to a blow molding method for molding a molded article having a crush portion from a tubular parison. The method of the present invention comprises:
For example, it can be suitably used when forming a duct with a resonator used for an intake duct and an exhaust duct of an engine of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, an intake system of an automobile engine,
2. Description of the Related Art In an exhaust system, a duct with a resonator is used for the purpose of reducing sound of a specific frequency. This is composed of a cylindrical duct body forming a gas passage, and a resonator connected to the duct body and forming a resonance chamber communicated with the gas passage of the duct body.

As a method of manufacturing such a duct with a resonator, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 59-68130, a duct body and a resonator are separately formed and fastened via an elastic member or the like. Generally, a method of connecting the both by a member is used. For example, Japanese Patent Publication No. 4-30900 and Japanese Patent Publication No. 4-25131 disclose that one member of a duct main body and a resonator is prepared in advance, and this is blow-molded to form the other member. A method is disclosed in which both members are integrated by blow-molding the other member while being housed in a mold.

Further, Japanese Patent Application Laid-Open No. 64-4318 discloses a method in which a single blow mold is used to simultaneously blow-mold the duct body and the resonator.

[0005]

However, the conventional method disclosed in Japanese Utility Model Application Laid-Open No. 59-68130, in which the duct body and the resonator are separately formed and then combined by using separate members, is disclosed in Japanese Unexamined Utility Model Publication No. 59-68130. It takes a lot of steps and man-hours to assemble the duct, and it cannot be said that the airtightness at the joint and the reliability of the joint strength are sufficient.

In the conventional method disclosed in Japanese Patent Publication No. 4-30900 or Japanese Patent Publication No. 4-25131, one member is formed in advance, and when the other member is blow-molded, both members are blown. Therefore, two or more molding steps are required, and the cost increases as the number of steps increases. On the other hand, in the conventional method disclosed in Japanese Patent Application Laid-Open No. 64-4318, the molding process itself is one step. A step of removing the burrs generated along the line is required, and a separate operation step is generated correspondingly. Therefore, the productivity is not sufficiently high, and there is a possibility that it is disadvantageous economically.

The present invention has been made in view of the above circumstances, and is capable of forming a blow-molded article having a main hollow portion and a sub-hollow portion communicating with each other, and further simplifies the forming process and reduces the deburring process. It is necessary to solve the problem of providing a blow molding method capable of molding a blow molded product having high reliability such as airtightness and bonding strength at the boundary between the main hollow portion and the sub hollow portion. It is a technical issue.

[0008]

The blow molding method according to the present invention for solving the above-mentioned problems has a slide core in at least one of an upper mold and a lower mold, and the slide core is provided in accordance with a desired product shape. In a blow molding method for molding a tubular parison using a blow mold provided to be able to protrude and retract with respect to a cavity engraved in a mold and a lower mold,
A setting step of setting the tubular parison having a shape that can be accommodated in the cavity without protruding from the side wall of the lower mold, and at the same time, allowing a part of the tubular parison to be present in a cavity space from which the slide core projects; A primary blow step of supplying air at a predetermined pressure inside the tubular parison after clamping the upper mold and the lower mold, and a core for allowing the slide core to advance into the cavity from at least one of the upper mold and the lower mold. a step out, the secondary blow step of the high pressure air than the supplied air is supplied to the interior of the tubular parison allowed to mold the molded article conforming to the outer shape of the cavity during the primary blow process, Ri Tona, The blow mold has the cavity
Having a parison guide that can appear in the
Is a state where the parison guide is projected into the cavity.
And set the parison in contact with the parison guide
Step der Rukoto to is characterized in.

In a preferred embodiment of the method of the present invention, the tubular parison of the present invention comprises, at least once, one material having a higher limit of the blow-up rate and another material having a lower limit of the blow-up rate than the one material. The parison in which the material is switched between the material and the material, and the blow-up rate of the maximum blow-up portion of the portion made of one material before and after blow molding is the maximum blow-up portion of the portion made of another material. It can be mentioned that it is larger than the blow-up rate.

[0010]

According to the blow molding method of the present invention, a tubular parison having a size that can be accommodated in the cavity of the blow mold is first formed. The parison is set in the cavity of the lower mold so that the side surface of the parison does not protrude from the cavity of the lower mold. At this time, the parison is set in the cavity of the lower mold so that at least a part of the parison is present in the cavity space from which the slide core provided so as to be able to move in and out of the mold projects. This allows
Burrs can be prevented from being generated on the outer peripheral side surface excluding both ends of the blow molded product.

After the lower mold and the upper mold are clamped, primary blow molding is performed at a relatively low pressure to entirely bulge the parison. This causes the parison to begin to swell gradually within the cavity. While the parison is expanding, the slide core is projected from at least one of the upper mold and the lower mold into the cavity. As a result, the parison at the position where the slide core protrudes is crushed by the slide core and the cavity surface facing the tip of the slide core. After that, if the secondary blow molding is performed at a high pressure, the parison in the portion not crushed by the slide core is blown up in the cavity. As a result, the portion blown up by direct blow-in of the air is defined as a main hollow portion, the portion crushed by the slide core is defined as a rib, and the portion blown up as a partial partition wall from the main hollow portion is defined as an auxiliary portion. It can be a blow molded product having a hollow portion. This blow molded product is released from the mold after cooling.

As described above, according to the blow molding method of the present invention, the rib which is the boundary between the main hollow portion and the sub hollow portion can be formed by the crushing portion using the slide core.
The strength is high, and the bonding strength at the ribs is high. Further, the main hollow portion and the sub hollow portion of the blow molded product can be simultaneously and integrally formed. Further, the blow mold has a parison guide portion that can come and go in the cavity, and in the step of setting the parison, the parison is brought into contact with the parison guide portion with the parison guide portion protruding into the cavity. Set it
Therefore , the parison can be quickly and reliably set in the cavity.

Further, in order to stably form a blow-molded product having a large blow-up rate in only a certain part and a parison blow-up in a narrow part, as described in the molding method of the present invention, After closing the mold and closing the pinch-off portion, it is effective means to perform a two-stage blow of a low-pressure primary blow and a high-pressure secondary blow. That is, since the partitioning partitioning the inside of the parison starts to be formed in a state where the parison is gradually expanding due to the primary blow, the parison can be blown up without difficulty even in a narrow cavity portion. Because it can withstand.

According to the method of the present invention, the parison of the blow-molded article is composed of a plurality of types of materials having different blow-up limits, and a part of the parison composed of one material having a high blow-up limit is replaced with another parison. This is a particularly suitable molding method for molding a blow molded article requiring a larger blow-up rate than the portion described in (1).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. ( Reference Example) This reference example is for manufacturing a duct with a resonator for an automobile. FIG. 1 is a cross-sectional view of a duct manufactured according to this reference example, and FIG. 2 is a cross-sectional view taken along line AA of FIG. B- of FIG.
FIG. 3 shows a cross-sectional view taken along line B.

A duct with a resonator according to a reference example has a tubular duct body 1 having a gas passage 1a therein, and a gas passage 1 of the duct body 1 formed integrally with the duct body 1.
box-shaped resonator 2 having a resonance chamber 2a communicating with a
And a pair of plate-shaped ribs 3 connecting the duct body 1 and the resonator 2. The duct body 1 is formed by blow molding of a method that does not generate burrs on the outer peripheral side surface except for both ends, and includes a first soft end portion 11 connected to a carburetor, an air cleaner, and the like, and a resonator 2.
Is formed integrally with a hard central portion 12 and a second soft end portion 13 connected to an intake manifold, an air flow meter, or the like of the engine. The first,
Both the second soft ends 11 and 13 are formed of a soft material such as a thermoplastic elastomer, specifically, TPO. The hard central portion 12 is made of a material having a high swale ratio and a high blow-up ratio with respect to the soft material,
It is formed of P (polypropylene) natural material.

The resonator 2 is made of the same material as the hard central portion 12 of the duct main body 1. The resonator 2 is integrated with the duct main body 1 via a neck 21 made of the same material as the hard central portion 12. Have been. A communication hole 21a is formed in the neck 21 for communicating the gas passage 1a of the duct body 1 with the resonance chamber 2a of the resonator 2. The cross-sectional shape of the resonator 2 is substantially trapezoidal as shown in FIG.

The rib 3 is also formed integrally with the duct body 1 and the resonator 2 using the same material as that of the hard central portion 12 of the duct body 1. The ribs 3 are formed by pressing and chewing on the surface of a blow molding die (slide core) as described later, and have a thickness of about 5 to 30 mm. A method of manufacturing the duct with the resonator having the above configuration will be described with reference to FIGS.

In the reference example, a blow molding machine having an upper mold 5 and a lower mold 6 and a pouring head 7 and the like are used. A cavity corresponding to the product shape is formed in the blow mold including the upper mold 5 and the lower mold 6, and a main cavity 81 corresponding to the shape of the duct main body 1 and a sub cavity 82 corresponding to the shape of the resonator 2 are respectively formed. Have been. The upper die 5 is provided with a slide core 51 at a position corresponding to the rib 3 so as to be able to protrude and retract into the cavity. The tip of the slide core 51 has the same shape as the planar shape of the rib 3, and has a notch 51 a for forming the neck 21 at a position corresponding to the neck 21 (see FIG. 8). The lower die 6 is also provided with a convex portion 61 having the same tip shape as the planar shape of the rib 3 facing the slide core 51 at a position corresponding to the rib 3. A notch 61a for forming the neck 21 is provided at a corresponding position (see FIG. 8).

At the time of molding, first, a parison P1 made of a soft material having a small blow-up limit corresponding to the first soft end portion 11 is poured out from the pouring head 7 of the blow molding machine. 2 and neck 21
A parison P2 made of a hard material having a large blow-up limit value corresponding to the second soft end portion 13 was poured out, and a parison P3 made of a soft material having a small blow-up limit value corresponding to the second soft end portion 13 was poured out (see FIG. 4). . In addition, Parison P
The sizes of the diameters 1 to P3 are controlled so that the side surfaces of the parisons P1 to P3 do not protrude from the cavity of the blow molding die. In other words, the parison P2 has the main cavity 8 of the blow mold so that the parisons P1 and P3 have a cross-sectional shape that can be stored in the main cavity 81 of the blow mold.
The size of the diameter is controlled so as to have a sectional shape that can be accommodated in the first and second cavities 82. Also, Parison P
The diameter of 2 is a parison P if necessary depending on the product shape.
1 or larger than P3. In order to make the diameter of the parison P2 larger than the parisons P1 and P3, there is a means for selecting a material whose swell ratio is larger than that of the parisons P1 and P3 as the material for the parison P2.

Generally, a parison having a large swell ratio is:
This is a parison with a large diameter that occurs immediately after being discharged from the discharge nozzle port. Therefore, parison P
If 2 is made of a material having a swell ratio larger than that of the parisons P1 and P3, only the diameter of the parison P2 can be increased naturally compared to the parisons P1 and P3 simply by pouring while switching the material constituting the parison. .

As shown in FIGS. 5 and 6, the parison P thus formed protrudes mainly into the main cavity 81 of the lower die 6, and the side surfaces of the parisons P1 to P3 protrude out of the cavity of the lower die 6. Set not to do. At this time, the parison P2 is arranged on the convex portion 61 of the lower die 6 so that the parison P2 is located over both the main cavity 81 and the sub cavity 82 of the lower die 6. Note that both ends of the parisons P1 to P3 are connected to the main cavities 81 of the lower mold 6.
Protrudes in the length direction.

After the upper die 5 with the slide core 51 immersed in the die was clamped to the lower die 6, air blowing (primary blowing) was started from a blow pin provided in the die. The air pressure at this time is low (4.9-19.6 × 1
0 ⁴ Pa), the parisons P1 to P3 were gradually expanded as a whole. At this time, the parison P2 corresponding to the hard central portion 12 is made of a material having a higher swelling ratio and a higher blow-up rate than the parisons P1 and P3 corresponding to the soft ends 11 and 13. The parison P2 has a larger diameter than the parisons P1 and P3 and is poured out, and at the same time, a part of the parison P2 swells greatly. As a result, the parisons P1 and P3 have the main cavity 8
1, the parison P2 also expands to a predetermined size in the main cavity 81 and the sub cavity 82.

After the start of the primary blow molding at a low pressure (after 0.1 to 5.0 seconds have elapsed from the air blowing), the slide core 51 is projected from the upper die 5 into the cavity, and
The parison P2 was held between the first mold 1 and the convex portion 61 of the lower mold 6 (see FIG. 7). Then, a secondary blow at a high pressure (34.3 × 1
0 ⁴ Pa), and molded into a predetermined cavity shape to obtain a blow molded product.

After cooling the above blow-molded product in a blow-molding mold, it was released from the mold, and the bags at both ends were cut to obtain a product shape. three
The blow molding method considered example, the blow molding in a state where the side surface of the parison P1~P3 was set parison so as not to protrude into the mold out from the blow mold cavity,
Burrs do not occur on the outer peripheral side surfaces of the duct main body 1 and the resonator 2 and the like which are products, so that a deburring step after blow molding can be omitted.

Further, since the rib 3 connecting the duct body 1 and the resonator 2 is formed by being pressed and crushed by the mold surfaces of the slide core 51 and the convex portion 61, its strength is high, and The bonding strength in No. 3 is highly reliable. In addition, the ribs 3 are formed by crushing.
Can be large. Further, the ribs 3 do not have any missing portions due to poor resin rotation due to crushing. Furthermore, since the duct body 1, the resonator 2, the ribs 3 and the neck 21 are all integrally formed simultaneously by blow molding,
In addition to simplifying the molding process and reducing the number of components, it is possible to prevent poor connection between the duct body 1 and the resonator 2 and prevent foreign matter such as dust and screws from entering the resonator 2. Further, it is possible to prevent the resonator 2 from being tuned out of alignment due to poor connection.

Furthermore, in the duct with the resonator according to the reference example, since both ends of the duct body 1 are formed by the soft ends 11 and 13, the connection work with the mating member becomes easy, and furthermore, the airtightness at the connection portion is improved. The property is also good. Further, since this duct with a resonator is formed by blow molding of a method that does not generate burrs, there is no V-shaped groove due to a parting line on the inner peripheral surface of the duct body 1 and the like except for the crushed portion. . For this reason, it further contributes to improving the airtightness of the connection portion.

Although the slide core 51 is provided only in the upper die 5 in the above reference example, the protrusion 61 of the lower die 6 may be a slide core similarly to the upper die. (First Embodiment) This first embodiment includes, as shown in FIG. 9, which was provided removably parison guide members 9 to the lower mold 6, others the
It is the same as the reference example. The parison guide 9 has a plate-shaped guide plate 91 at the tip.

At the time of blow molding, the parison guide 9 is inserted from the end of the main cavity 81 opposite to the sub-cavity 82 so that the guide plate 91 is located substantially at the center of the main cavity 81, and the lower mold is inserted. 6. And
When the parisons P1 to P3 are set in the cavity of the lower mold 6, the parison P2 is set while being in contact with the guide plate portion 91 of the parison guide portion 9. As a result, the parison P2 is curved toward the sub-cavity 82 while being guided by the guide plate portion 91, so that the parison P2 surely and quickly spans both the main cavity 81 and the sub-cavity 82. Can be set to When the parisons P1 to P3 have been set in the cavity of the lower mold 6, the parison guide 9 is removed, the mold is clamped, and blow molding is performed as in the reference example.

The guide plate 91 of the parison guide 9 may be inclined to make it easier to insert the parison P2. ( Second Embodiment) In the second embodiment, as shown in FIGS. 10 and 11, the parison guide 9 is provided on the lower die 6 so as to be reciprocable in the horizontal direction. This is the same as the first embodiment. That is, the parison guide section 9 can reciprocate in the horizontal direction so as to be able to protrude and retract into the main cavity 81.

At the time of blow molding, the parison guide portion 9 is inserted into the main cavity 81 from the opposite end of the sub cavity 82 of the main cavity 81 so that the guide plate portion 91 is located substantially at the center of the main cavity 81. Protrude. Thus, when the parisons P1 to P3 are set in the cavity of the lower mold 6, the parison P2 is set in the same manner as in the first embodiment.
Can be reliably and quickly set while contacting the portion with the guide plate portion 91 of the parison guide portion 9. Since the parison P2 is curved toward the sub cavity 82 while being guided by the guide plate portion 91, the parison P2 can be reliably set so as to extend over both the main cavity 81 and the sub cavity 82. When the parisons P1 to P3 have been set in the cavity of the lower mold 6, the lower mold 6 and the upper mold 5 are clamped, and the parison guide 9 is immediately or immediately immersed in the lower mold 6. While low pressure blow molding. As a result, the first
As compared with the embodiment, the parison P2 can be more reliably expanded in both the main cavity 81 and the sub cavity 82.

( Third Embodiment) In the third embodiment, as shown in FIG. 12, a plate-shaped parison guide 9 is provided on the lower mold 6 so as to be able to reciprocate in a substantially vertical direction. In other respects, the second embodiment is the same as the second embodiment, and has the same operation and effect as the second embodiment. In order to make it easier to insert the parison P2, the sliding direction of the parison guide 9 may be inclined.

In the above-described embodiment, an example has been described in which a blow-molded product is formed which has a main hollow portion and a sub-hollow portion, both of which are integrally connected by a rib formed by a crushing portion. However, according to the method of the present invention, by disposing the slide core at the end in the cavity,
On the side of a hollow molded product with a single hollow part, integrally,
Moreover, it is possible to form a blow-molded article having a strong and large crushing portion.

[0034]

As described above in detail, in the blow molding method of the present invention, it is possible to prevent burrs from being generated on the outer peripheral side surface excluding both ends of the blow molded product, and the deburring step after the blow molding is performed. It can be omitted. Further, according to the blow molding method of the present invention, an integral blow comprising a main hollow portion, a sub hollow portion, and a rib which is crushed by the slide core and connects the main hollow portion and the sub hollow portion. A molded article can be formed. Therefore, it is possible to form a blow-molded product having good connectivity at the rib connecting the main hollow portion and the sub-hollow portion while reducing the number of forming steps and the number of parts.

Further, the blow mold is provided with a parison guide portion that can be inserted into and retracted from the cavity, and the parison is set in contact with the parison guide portion with the parison guide portion protruding into the cavity. since the, rapidly parison within cavity, and it is possible to reliably set.

[Brief description of the drawings]

FIG. 1 is a sectional view of a duct with a resonator manufactured according to a reference example.

FIG. 2 relates to the duct with a resonator, and FIG.
FIG. 3 is a sectional view taken along line A.

FIG. 3 relates to the duct with a resonator, and FIG.
FIG. 4 is a cross-sectional view taken along line B.

FIG. 4 is a cross-sectional view of a parison according to a reference example.

FIG. 5 is a perspective view showing a state in which a parison is set in a cavity of a lower die according to the reference example.

FIG. 6 is a cross-sectional view showing a state in which a parison is set in a cavity of a lower mold according to the reference example.

FIG. 7 is a cross-sectional view showing a state after high-pressure blow molding according to the reference example.

FIG. 8 is a partial cross-sectional view of a lower mold projection and an upper mold slide core according to the reference example.

FIG. 9 is a cross-sectional view showing a state in which a parison is set in a cavity of a lower mold according to the first embodiment.

FIG. 10 is a sectional view showing a state in which a parison is set in a cavity of a lower mold according to the second embodiment.

FIG. 11 is a cross-sectional view showing a state after high-pressure blow molding according to the second embodiment.

FIG. 12 is a cross-sectional view showing a state where a parison is set in a cavity of a lower mold according to the third embodiment.

[Explanation of symbols]

1 is a duct body, 1a is a gas passage, 2 is a resonator, 2
a is a resonance chamber, 21a is a communication hole, 3 is a rib, 5 is an upper die, 5
1 is a slide core, 6 is a lower mold, 61 is a projection, 81 is a main cavity, 82 is a sub cavity, 9 is a parison guide,
P1 to 3 are parisons.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-57925 (JP, A) JP-A-2-70419 (JP, A) JP-A-61-70718 (JP, A) JP-A-7-70 217511 (JP, A) JP-A-64-4318 (JP, A) JP-A-63-196709 (JP, U) JP-A-6-32018 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) B29C 49/00-49/80 B60H 1/00-1/34

Claims (2)

(57) [Claims] 1. A slide core is provided in at least one of an upper mold and a lower mold, and the slide core is provided so as to be able to protrude and retract with respect to a cavity formed in the upper mold and the lower mold according to a desired product shape. A blow molding method for forming a tubular parison using a blow mold, wherein the tubular parison having a shape that can be accommodated in the cavity is set without protruding from the side wall of the lower mold, and the tubular parison is simultaneously set. A primary blow step of supplying air at a predetermined pressure inside the tubular parison after clamping the upper mold and the lower mold, and setting a part of the upper part in a cavity space from which the slide core protrudes; A core forming step of causing the slide core to advance into the cavity from at least one of a mold and a lower mold; A secondary blow step allowed to mold the high-pressure air the molded articles tubular parison is supplied to the inside follows the contour of the cavity than the air which is supplied during the degree, Ri Tona, the blow mold the cavity Haunting in
Having a possible parison guide, said setting step
With the ribson guide protruding into the cavity,
A step of setting a ribon in contact with the parison guide section
A blow molding process, characterized in der Rukoto. 2. The tubular parison, wherein the material is switched at least once between one material having a higher blow-up rate limit and another material having a lower blow-up rate limit than the one material. The blow-up rate of the maximum blow-up portion of the portion made of one material before and after blow molding is larger than the blow-up rate of the maximum blow-up portion of the portion made of another material. The blow molding method according to claim 1 .