JP3470580B2 - Method and apparatus for molding 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 an apparatus for molding a hollow container, and in particular, as represented by a fuel tank of an automobile, a part of the hollow container is locally recessed inward and the recess is formed. Relates to a method and an apparatus for forming a hollow container having a structure in which a portion corresponding to a bottom wall portion of the container is fused and integrated with an inner wall surface of the container itself facing the container to form a web by a blow molding method.

[0002]

2. Description of the Related Art In a vehicle fuel tank 1 made of resin as shown in FIG . 4, it is generally molded by a blow molding method. At the same time, the bottom wall surfaces of the recess 3 are fused and integrated with each other, and the partition-shaped web 4 is formed in that portion. The web 4 is provided to prevent deformation of the fuel tank 1 due to an increase in internal pressure and interference with other parts.

As shown in FIG. 5 , the fuel tank 1 having the web 4 is formed by air-blowing the parison P while pressing and restraining the parison P with the mold 101.

[0004]

In the conventional molding method as described above, when the mold 101 is clamped, the convex portion 1 is formed at that point.
02 and 102 are abutted against each other to form the web 4. On the other hand, as is clear from FIG. 5A , the parison P is still in the process of expanding at the time of completion of the mold clamping, and the web 4 which is substantially completely restrained by the convex portions 102, 102. Other parison P
Will be stretched further. Therefore, a portion of the parison P that is close to the web 4, that is, a portion corresponding to the vertical wall portion of each depression 3 is locally greatly stretched, and as a result, the wall thickness t of that portion is extremely thinned and the local portion is locally thinned. It is easy to cause problems such as mechanical strength reduction. This is based on the fact that the portion to be the web 4 is completely restrained by the convex portion 102 from an early stage.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a molding method and a molding apparatus which solve the above-mentioned problem of localized thinning.

[0006]

According to a first aspect of the present invention, a part of the hollow container is locally recessed inward, and an inner wall surface of a portion corresponding to the bottom wall of the recess faces it. A method for molding a hollow container having a structure in which a web is formed by fusion-bonding with the inner wall surface of the container itself by a blow molding method, which is a part of a mold for blow molding that controls molding of the depression. Guide all or part to the groove provided in the mold
Divide into a slide core that is supported and can appear and disappear in the depth direction of the recess, and part of the parison wraps around the groove side.
Until circumferential length necessary for forming the recesses in Mukoto is secured proceeded expansion of the parison being maintained at the retreat limit position or incomplete forward position of the slide core, the recess
Once the perimeter of the parison required for molding the parison is secured , the slide core is advanced to the advance limit position corresponding to the regular product shape position before the expansion of the parison is completed, and the bottom wall of the recess is The web is formed by fusing a corresponding portion to the inner wall surface of the parison facing the corresponding portion.

According to the second aspect of the invention, portions of the hollow container facing each other are locally recessed inward, and portions corresponding to bottom walls of the recesses are inner wall surfaces. A method for molding a hollow container having a structure in which a web is fused and integrated to form a blow molding method, wherein all or a part of a mold for blow molding which controls molding of at least one depression Part of the mold
Is guided and supported in the northern groove divides the slide core retractable in the depth direction of the recess that, the part of the parison
By wrapping around to the groove side, the peripheral length required for forming the depression is
Until it is secured , the expansion of the parison proceeds while holding the slide core in the retracted limit position or the incompletely advanced position to secure the peripheral length of the parison necessary for forming the recess.
Been if by the slide core is advanced to a forward limit position corresponding to a product shape normal position before the expansion of the parison is completed, the web are fused together portions corresponding to the bottom wall of each recess It is characterized by molding.

The invention described in claim 3 is a molding apparatus used in the molding method according to claim 1 or 2, wherein
Forming part of the recess by wrapping around part of the groove toward the groove
While until circumference is secured necessary to hold the retraction limit position or incomplete forward position of the slide core, wherein
If the perimeter of the parison necessary for forming the recess is secured, it is equipped with an actuator that advances the slide core to the advance limit position corresponding to the regular product shape position before the expansion of the parison is completed. There is.

Therefore, in the invention described in claims 1 to 3, the portion of the die that controls the web formation is movable as a slide core, and the slide core reaches the regular final product shape position. The timing of doing this is likely to be much later than the expansion timing of the parison. Therefore, in the expansion process of the parison, a part of it wraps around the slide core and a part of the recess is preformed, and after the sufficient peripheral length is secured, the inner wall surface of the bottom wall of the recess is separated by the slide core. The web is formed by fusing to the inner wall surface of the parison or the other bottom wall portion. As a result, a part of the parison does not become locally thin due to the shortage of the peripheral length in the vicinity of the web as in the conventional case.

[0010]

According to the invention described in claims 1 and 2, a part of the hollow container is locally recessed inward, and an inner wall surface of a portion corresponding to a bottom wall portion of the recess faces it. A hollow container having a structure in which it is fused and integrated with the inner wall surface of the container itself to form a web, or parts of the hollow container that face each other are locally recessed inward, and the bottom wall of each recess is In forming a hollow container having a structure in which a portion corresponding to a portion is fused and integrated with each other on inner wall surfaces to form a web by a blow molding method, it controls molding of the depression in the blow molding die. All or part of the part ,
It is guided and supported in the grooves provided on the mold to divide the slide core retractable in the depth direction of the recess thereof, the parison one
Necessary for forming the recess by wrapping around the groove side
Until the peripheral length is secured , the expansion of the parison is advanced while the slide core is held at the retracted limit position or the incompletely advanced position, and the circumference of the parison necessary for forming the recess is increased.
If the length is secured , the slide core is advanced to the advance limit position corresponding to the regular product shape position before the expansion of the parison is completed, and the inner wall surface of the portion corresponding to the bottom wall portion of the recess is opposed to it. Since the web is formed by fusing with the inner wall of the parison or the bottom wall of the recess on the other side, the recess is formed only when the parison is fully extended in the mold, that is, at the end of forming. Will be done. Therefore, unlike the conventional case, the required thickness is secured without locally thinning the vicinity of the web, and it is possible to improve the strength and quality of the hollow container as a molded product.

According to the third aspect of the invention, the molding apparatus used in the molding method according to the first or second aspect is provided with an actuator for moving the slide core forward and backward. Therefore, in addition to the same effect as the invention according to claim 1 or 2, the advance / retreat operation timing of the slide core by the actuator can be easily adjusted, thereby further optimizing the operation timing of the slide core. There is an effect that can be done.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a more preferred first embodiment of the invention described in claims 1 to 3 .
4 shows an example of a mold for blow molding for molding an automobile fuel tank (hereinafter referred to as a molded product) 1 which is the hollow container shown in FIG.

As shown in FIG. 1, a mold 5 composed of an upper mold 6 and a lower mold 7 is capable of performing a mold clamping mold opening operation in a direction of approaching and separating from each other. While the tube-shaped parison P is clamped by 7 and the mold is clamped, air is blown into the parison P to expand the parison P.
The molded product 1 having a predetermined shape is molded by being brought into close contact with a and 7a.

Of the inner wall surfaces 6a, 7a of the upper and lower molds 6, 7, the parts that control the molding of the web 4 of the molded product 1 are preliminarily divided as slide cores 8 and are guided and supported by the groove portions 9, respectively. The structure is such that it can move back and forth with respect to 6, 7. An air cylinder 10 or a hydraulic cylinder is provided as an actuator on the outside of the upper and lower molds 6 and 7, and the piston rod 1 of each air cylinder 10 is provided.
The slide core 8 is connected to the slide core 1, and each slide core 8 moves back and forth according to the expansion and contraction operation of these air cylinders 10.

FIG. 1A shows a state in which the mold clamping operation of the mold 5 is completed as the air blow progresses, and each slide core 8 is retracted by the contraction operation of the air cylinder 10 before the mold clamping operation is started. Therefore, each slide core 8 is held at the retracted limit position, that is, the position retracted from the normal final product shape position even when the mold clamping is completed as shown in FIG.

Even after the mold clamping is completed, the air blowing into the parison P is still continued, and the parison P is gradually brought into close contact with the inner wall surfaces 6a and 7a of the mold 5 as shown in FIG. Expands. At this time, since each slide core 8 is still held in the retracted limit position and does not particularly restrain the parison P, the parison P expands so as to be uniformly thinned as a whole, while the parison P By wrapping around the tip of each slide core 8 and wrapping around the groove 9 side, the circumferential length required for forming each recess 3 is secured.

[0017] Then, if the expansion of the parison P, as shown in FIG reaches the molding end progresses, i.e., the
Part of the parison P is attached to the tip of each slide core 8 as shown in
As it wraps around the groove 9 side, each recess 3
When the peripheral length required for molding is secured, each air cylinder 10 is operated to move the slide core 8 forward.
As a result, the parts of the parison P that are wound around the slide cores 8 are expanded so as to be expanded to form the recesses 3 having a predetermined depth, and the recesses 3 correspond to the bottom wall portions of the recesses 3. The inner wall surface 3a of the portion to be melted is fused and integrated with each other to form the web 4,
Finally, the molded article 1 as shown in FIG. 7 is molded after waiting for the completion of the air blow shown in FIG.

As described above, according to this embodiment, by delaying the forward movement of each slide core 8 relative to the degree of progress of the air blow, it is possible to sufficiently secure the circumferential length required for forming the recess 3. Unlike the conventional case, the wall thickness in the vicinity of the web 4 does not become locally thin.

Here, the projection timing of the slide core 8 is appropriately adjusted according to the depth of the recess 3 and the like,
In some cases, the air blow operation may be performed while advancing the slide core 8 little by little. Also, as shown in FIG. 2, with respect to the inner wall surfaces 6a, 7a of the upper and lower molds 6, 7 which are responsible for the molding of the web 4, only a part of the outer peripheral side thereof is divided to form the slide core 8A. Is obtained. However, in FIG. 2, the air cylinder 10 of FIG. 1 is not shown.

FIG. 3 is a view showing a second embodiment of the invention described in claims 1 to 3, wherein when one of the depressions 3 has a relatively shallow depth, the depth of the upper and lower molds 6A, 7A is reduced. Large depression 3
The slide core 8 is provided only on the side of the lower mold 7A for molding. It goes without saying that the same effects as those of the first embodiment can be obtained in this embodiment as well.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the invention described in claims 1 to 3, and is an operation explanatory diagram of a mold at the time of blow molding.

FIG. 2 is an enlarged view of an essential part showing a modified example of the slide core shown in FIG.

FIG. 3 is a sectional view of a mold showing a second embodiment of the invention described in claims 1 to 3.

FIG. 4 shows a structure of an automobile fuel tank as an example of a hollow container .
Sectional perspective view showing a structure.

FIG. 5 is a sectional view of a mold showing a conventional blow molding method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Automotive fuel tank (molded product = hollow container) 3 ... Recess 3a ... Inner wall surface 4 ... Web 5 ... Molds 6, 6A ... Upper mold 7, 7A ... Lower mold 8, 8A ... Slide core 9 ... Groove 10 ... Air cylinder (actuator) P ... Parison

Claims (3)

(57) [Claims] 1. A part of a hollow container is locally recessed inward, and an inner wall surface of a portion corresponding to a bottom wall portion of the recess is fused and integrated with an inner wall surface of the container itself facing the web. A method of molding a hollow container having a structure that forms a blow molding method, wherein all or part of a portion of the mold for blow molding that controls molding of the recess is formed in a groove provided in the mold. The slide core is guided and supported, and is divided into a slide core that can project and retract in the depth direction of the recess, and a part of the parison wraps around the groove side to form the recess.
Until the perimeter required for molding is secured , the expansion of the parison is advanced while the slide core is held in the retracted limit position or the incompletely advanced position, and the perimeter of the parison required for molding the recess is secured. and the slide core is advanced to a forward limit position corresponding to a product shape normal position before been Do <br/> mule expansion of the parison is completed,
A method for forming a hollow container, characterized in that a portion corresponding to a bottom wall portion of the recess is fused with an inner wall surface of a parison facing the depression to form a web. 2. A hollow container is configured such that portions facing each other are locally recessed inward, and portions corresponding to bottom walls of the recesses are fused and integrated with each other on inner wall surfaces to form a web. A method for molding a hollow container having the structure described above by a blow molding method, in which at least one of the molds for blow molding is provided with the mold in whole or in part .
The slide core is guided and supported in the groove and is divided into slide cores that can project and retract in the depth direction of the recess, and a part of the parison wraps around the groove side to form the recess.
Until the perimeter required for molding is secured , the expansion of the parison is advanced while the slide core is held in the retracted limit position or the incompletely advanced position, and the perimeter of the parison required for molding the recess is secured. and the slide core is advanced to a forward limit position corresponding to a product shape normal position before been Do <br/> mule expansion of the parison is completed,
A method for forming a hollow container, characterized in that a portion corresponding to a bottom wall portion of each recess is fused with each other to form a web. 3. The molding apparatus used in the molding method according to claim 1, wherein a part of the parison wraps around the groove side to form the recess.
Until circumferential length necessary for forming the is secured while retaining the retracted limit position or incomplete forward position of the slide core, the circumferential length of the parison required shaping of the recess is ensured
The hollow container molding apparatus is provided with an actuator that advances the slide core to the advance limit position corresponding to the regular product shape position before the expansion of the parison is completed.