JP2016112730A - Blow molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow molding method for, making a fusion surface of a parison and a built-in component vertical to a gravity direction of the built-in component, for depositing the built-in component to a predetermined place.SOLUTION: A blow molding mold 20 comprises a slide core 26, and forms a slide core holding part 26a for holding a built-in component attachment part 12 on a tip end of the slide core 26. A built-in component holding bar 41 is inserted into a built-in component holding hole 11, and the built-in component holding bar 41 and the built-in component holding hole 11 are held so that slide friction occurs. The blow molding mold 20 is opened, then a built-in component 10 is held at a position facing a cavity 22, then the blow molding mold 20 is closed, then a parison 8 and the built-in component 10 are held on the slide core 26, then, the built-in component attachment part 12 is held by the slide core holding part 26a sandwiching the parison 8, then, the built-in component holding bar 41 is lowered, then, the built-in component attachment part 12 is pressed against the parison 8 by slide friction, for deposition.SELECTED DRAWING: Figure 2

Description

The present invention relates to a blow molding method for molding a blow molded product having a built-in component made of a thermoplastic synthetic resin.

Conventionally, as a structure of a hollow blow-molded product, for example, a fuel tank for an automobile or the like, a metal one has been used. However, in recent years, the weight of a vehicle is reduced, rust is not generated, and a desired shape is used. For example, a hollow thermoplastic synthetic resin has come to be used because of its easy molding.

In the production of a hollow product made of a thermoplastic synthetic resin, a blow molding method has been often used because of the ease of molding a hollow body. In the blow molding method, a parison of a molten thermoplastic synthetic resin member is formed into a cylindrical shape and extruded from above, and the parison is sandwiched between molds and air is blown into the parison to produce a hollow body.

On the other hand, in the blow molding method, it is sometimes required to provide a blow molded product, for example, a built-in component such as a valve or a baffle plate for suppressing fuel flow noise inside the fuel tank.
Therefore, when providing a built-in component inside the blow molded product, a manufacturing apparatus as shown in FIG. 13 is used (for example, refer to Patent Documents 1 and 2). The built-in component 110 is held in the cavity of the blow molding die 120 by the built-in component holding rod 141, the parison 8 is lowered, and then the built-in component 110 is sandwiched by the slide core 126, and the blow molding die 120 is held. Is closed, and the parison 8 is sandwiched between pinch plates 135 to form a blow molded product.

However, in this case, when the built-in component 110 becomes large, the built-in component 210 is held in the parison 8 when the built-in component 210 held by the built-in component holding rod 241 is molded by the blow mold 220 as shown in FIG. The built-in component 210 is held by the holding rod 241, the built-in component holding rod 241 is slid, the built-in component 210 is inserted, and then the built-in component 210 is sandwiched by the slide core 226.

In this case, since the built-in component 210 is clamped by the slide cores 226 attached to the split molds on both sides of the blow molding die 220, the built-in component 210 can be clamped by the slide cores 226 on both sides. It needs to have a width. Further, since the fusion surface of the built-in component 210 and the parison is parallel to the direction of gravity, the built-in component 210 may be fixed by being displaced from a predetermined position on the inner surface of the parison 8 due to the weight of the built-in component 210.
Further, the built-in component 210 in the portion sandwiched between the slide cores 226 on both sides needs to have strength to support its own weight in the mold during blow molding, facing the sandwiched pressing force.

For this reason, an unnecessary part is included as a function of the built-in component 210, so that the built-in component 210 is enlarged, the weight of the blow molded product to which the built-in component 210 is attached is increased, and the enlarged built-in component 210 is disposed. The space is increased, and the mounting portion for mounting the built-in component 210 in the blow-molded product is restricted.

Japanese Patent Laid-Open No. 9-174670 JP-A-8-72129

  Therefore, the present invention provides a blow molding method for welding a built-in component in a predetermined place by making the fusion surface of the parison and the built-in component perpendicular to the gravity direction of the built-in component in the manufacture of a blow molded product having the built-in component. The task is to do.

The present invention of claim 1 for solving the above-mentioned problem is a blow molding method for molding a blow molded product in which a built-in component is attached.
The blow molding method includes a die core for extruding a parison, a blow molding die for molding the outer wall of the blow molded product, a parison clamping device for clamping the lower end of the parison, and a built-in component holding device for holding a built-in component before blow molding Use
The blow mold has a split mold formed by dividing it into two parts at the parting line, and a cavity that forms a blow-molded product is formed on the open / close surface, and the slide core can be moved forward and backward on the inner surface of the cavity. The slide core holding part that holds the built-in part mounting part formed on the outer surface of the built-in part is formed at the tip of the slide core, the built-in part is held by the slide core holding part, and the blow molded product is formed in the cavity. Molding the outer wall,
A parison clamping device for clamping the lower end of the parison is provided below the blow mold,
The built-in component holding device has a built-in component holding bar that holds the built-in component and is slidable in the vertical direction. The built-in component holding bar is inserted into the built-in component holding hole formed in the built-in component, and the built-in component The holding rod is inserted so that sliding friction occurs in the built-in component holding hole,
Open the blow mold, slide the built-in component holding rod from the lower end of the parison, position the built-in component in the parison, hold the built-in component in a position facing the cavity, and close the blow mold The internal component is positioned inside the parison, the parison is brought into contact with the slide core, and the internal component mounting portion is held by the slide core holding portion with the parison interposed therebetween, and then the internal component holding rod is lowered downward, The built-in component mounting part is pressed against the parison held by the slide core by sliding friction and welded.
In this blow molding method, the blow molding die is closed and the upper and lower portions of the parison are sandwiched between the upper and lower ends of the blow molding die, and then a gas is blown into the parison to mold a blow molded product.

In the present invention of claim 1, the blow molding method includes a die core for extruding the parison, a blow molding die for molding the outer wall of the blow molded product, a parison clamping device for clamping the lower end of the parison, and built-in before blow molding. A built-in component holding device that holds the components is used. For this reason, the parison extruded by the die core is held at the lower end of the parison before blow molding, the lower end of the parison is widened, and the built-in component is inserted into the parison by the built-in component holding device, and the built-in component is held inside. A blow molded product can be obtained.

The blow mold has a mold that is divided into two parts at the parting line. A cavity that forms a blow-molded product is formed on the open / close surface, and a slide core is formed on the inner surface of the cavity so that the slide core can be moved forward and backward. Provide. For this reason, a blow molded product having the built-in component in a predetermined position in the cavity can be formed by holding the built-in component in the parison with the slide core.

The slide core holding part that holds the built-in part mounting part formed at the tip of the built-in part is formed at the tip of the slide core, the built-in part is held by the slide core holding part, and the outer wall of the blow molded product is formed by the cavity. To do. For this reason, since the built-in component mounting portion of the built-in component can be held by the slide core holding portion, the weight of the built-in component is received by the slide core holding portion in the direction perpendicular to the gravity, and the built-in component is fused at a predetermined position. There is no need to sandwich the built-in component from both sides with a slide core, and it is not necessary to increase the rigidity of the built-in component, thereby reducing the size.

A parison clamping device that clamps the lower end of the parison is provided below the blow molding die. For this reason, it is possible to open the lower end of the parison and insert the built-in part into the lower end of the parison. When pre-blowing and inflating the parison and inserting the built-in part into the parison, the built-in part contacts the inner wall of the parison. Can be prevented.

The built-in component holding device has a built-in component holding bar that holds the built-in component and is slidable in the vertical direction, and the built-in component holding bar is inserted into a built-in component holding hole formed in the built-in component. For this reason, the built-in component holding rod is inserted into the built-in component holding hole, the built-in component is held and inserted into the parison, and the built-in component holding rod is detachably slid from the built-in component holding hole, and the built-in component The holding bar can be pulled out.

The built-in component holding rod is inserted so that sliding friction occurs in the built-in component holding hole. For this reason, when the built-in component holding rod is removed from the built-in component holding hole, the built-in component can be pulled downward by sliding friction, and the built-in component mounting part can be pressed against the parison held by the slide core holding part. The built-in component mounting portion can be firmly pressed against the parison.

Open the blow mold, slide the built-in component holding rod from the lower end of the parison, position the built-in component in the parison, hold the built-in component in a position facing the cavity, and close the blow mold Then, the built-in component is positioned inside the parison, and the parison is brought into contact with the slide core. For this reason, a built-in component can be reliably attached to the predetermined position inside a parison.

After the built-in component mounting portion is held by the slide core holding portion across the parison, the built-in component holding rod is lowered downward, and the built-in component mounting portion is pressed and welded to the parison held by the slide core by sliding friction. For this reason, the weight of the built-in component is held perpendicularly to the direction of gravity by the slide core holding unit, and the built-in component is welded to a predetermined position, and is held by the slide core holding unit when the built-in component holding member is lowered downward. The built-in component mounting portion can be strongly pressed against the parison by sliding friction, and the built-in component mounting portion can be strongly pressed against the parison and welded to the parison in a molten state.

The blow mold is closed, and the upper and lower parts of the parison are sandwiched between the upper and lower ends of the blow mold, and then gas is blown into the parison to blow the upper and lower parts of the parison to form a blow molded product. It can be closed with a molding die, and blow molding can be performed while the built-in component is held at a predetermined position in the cavity, and a blow molded product in which the built-in component is arranged at a predetermined position can be obtained.

The present invention of claim 2 is a blow molding method in which the built-in component holding rod or the built-in component holding hole has a cross-section formed in an uneven shape, and the built-in component is held so that sliding friction occurs on the built-in component holding rod. .

According to the second aspect of the present invention, the cross section of the built-in component holding rod or the built-in component holding hole is formed in a concavo-convex shape, and the built-in component is held so that sliding friction occurs on the built-in component holding rod. For this reason, the built-in component holding rod can surely generate sliding friction with the built-in component holding hole by the uneven shape of the cross-section of the built-in component holding rod or the built-in component holding hole.

The present invention of claim 3 is a blow molding method in which a plurality of built-in component holding rods are inserted into the built-in components, and each built-in component holding rod is inserted into a plurality of built-in component holding holes.

In the present invention of claim 3, since the plurality of built-in component holding bars are inserted into the built-in component, the built-in component can be stably held.
Since each built-in component holding rod is inserted into a plurality of built-in component holding holes, each built-in component holding rod has a large sliding friction when pulled out from a plurality of built-in component holding holes, so that the built-in component firmly The mounting portion can be pressed against the parison.

In the present invention, a slide core holding portion that holds a built-in component mounting portion formed at the tip of a built-in component is formed at the tip of the slide core, the built-in component mounting portion is held by the slide core holding portion, and blown in a cavity. In order to mold the outer wall of the molded product, the weight of the built-in component can be held by the slide core holder perpendicular to the direction of gravity, and the built-in component can be welded in place, and the built-in component needs to be clamped by the slide core The built-in components can be reduced in size.

To hold the built-in component mounting part with the slide core holding part across the parison, then lower the built-in part holding bar downward, and press and weld the built-in part mounting part to the parison held by the slide core by sliding friction The built-in component mounting portion can be strongly pressed by sliding friction on the parison held by the slide core holding portion, and the built-in component mounting portion can be strongly welded to the parison.

It is a fuel tank perspective view which is an embodiment of the invention. It is sectional drawing of the process in which the blow molding apparatus of embodiment of this invention manufactures a blow molded product, and it is sectional drawing which shows the state which a parison entered in the blow molding die and the lower end of the parison was opened with the parison expander. is there. Sectional drawing of the process which the blow molding apparatus of embodiment of this invention manufactures a blow molded product, and shows the state which clamped the lower end of a parison by the parison outer clamping plate and the parison holding part of a built-in component airtight guide cylinder It is. It is sectional drawing of the process in which the blow molding apparatus of embodiment of this invention manufactures a blow molded product, The state which performed the pre-blow by pinching the lower end of a parison with the upper end of a parison outer clamping plate and a built-in component airtight guide cylinder. It is sectional drawing shown. Sectional drawing of the process in which the blow molding apparatus of embodiment of this invention manufactures a blow molded product, raises a built-in component holding rod from the lower end of a parison, and shows the state which inserted the built-in component in a parison It is. It is sectional drawing of the process in which the blow molding apparatus of embodiment of this invention manufactures a blow molded product, and a state just before a slide core slides in a cavity and hold | maintains the internal component in a parison with a slide core. It is sectional drawing shown. It is sectional drawing of the process in which the blow molding apparatus of embodiment of this invention manufactures a blow molded product, hold | maintains the built-in component attachment part in a parison with a slide core holding part on both sides of a parison, It is sectional drawing which shows the state extracted from the blow molding die. FIG. 3 is a cross-sectional view of a process for producing a blow molded product by the blow molding apparatus according to the embodiment of the present invention, in which a built-in component mounting portion in a parison is held by a slide core holding portion, and a blow molding die is closed to perform blow molding It is sectional drawing which shows the state which carried out. FIG. 4 is a cross-sectional view of a process for producing a blow molded product by the blow molding apparatus according to the embodiment of the present invention, showing a state in which a built-in component holding member of a built-in component in a parison is held by a slide core with a parison interposed therebetween; It is an expanded sectional view of the part which held the built-in component attachment part in the slide core holding part It is an expanded sectional view of the state where the built-in component holding rod used for the blow molding method of an embodiment of the invention was inserted in the built-in component holding hole of the built-in component. It is an expanded sectional view which shows the state by which the root part of the built-in component holding | maintenance rod used for the blow molding method of embodiment of this invention was inserted in the built-in component holding hole of a built-in component. It is an expanded sectional view which shows the state by which the front-end | tip part of the built-in component holding rod used for the blow molding method of embodiment of this invention was inserted in the built-in component holding hole of a built-in component. It is a perspective view of the apparatus with which the slide core and drive control pin of the conventional blow molding apparatus manufacture a blow molded product. It is sectional drawing of the process of manufacturing the blow molded product of the other conventional blow molding apparatus, and is sectional drawing which shows the state which the parison entered in the blow molding die.

A blow molding method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 12 by taking as an example a blow molding method for manufacturing a fuel tank 1 for automobiles which is a blow molded product. The present invention will be described by taking the fuel tank 1 having the built-in component 10 as an example, but other blow molded products having the built-in component 10 can also be used.

FIG. 1 is a perspective view of a fuel tank 1 manufactured by a blow molding method according to an embodiment of the present invention.
In the embodiment of the present invention, a fuel tank 1 manufactured by a blow molding apparatus has a pump unit mounting hole 4 for taking a fuel pump (not shown) and the like into and out of the fuel tank 1 as shown in FIG. Is formed on the upper surface. A fuel injection hole 5 for injecting fuel from an inlet pipe (not shown) is formed on the side surface or the upper surface of the fuel tank 1.

An outer peripheral rib 2 is formed around the entire circumference of the fuel tank 1, and mounting holes 3 are formed at predetermined locations such as corner portions of the outer peripheral rib 2. The fuel tank 1 is attached to the vehicle body by bolting 3 and the vehicle body.
Furthermore, on the upper surface of the fuel tank 1, there are formed attachment holes 6 at various places for connecting a hose or the like for collecting the internal fuel vapor.

The fuel tank 1 manufactured in the present embodiment is manufactured by a blow molding manufacturing apparatus to be described later. The outer wall of the fuel tank 1 is formed by blow molding, and the outer wall is formed by one layer or multiple layers. In the case of multiple layers, for example, a skin layer, an external body layer, an external adhesive layer, a barrier layer, an internal adhesive layer, and an internal body layer are formed in order from the outside.

Inside the fuel tank 1, for example, a pillar for reinforcing the fuel tank 1, a partition plate for preventing the generation of undulation noise, a fuel pump, A box or the like for mounting a canister or the like is attached as the built-in component 10.
The built-in component 10 can be formed of a fuel-resistant thermoplastic synthetic resin such as polyacetal or high-density polyethylene (HDPE). As a result, the strength of the fuel tank 1 can be improved, and even if the fuel tank 1 is attached to the inside of the fuel tank 1, the rigidity does not decrease due to swelling by the fuel oil or the like. Moreover, if the same kind of material as the outer wall of the fuel tank 1 is used, the built-in component 10 can be firmly welded.

A method for manufacturing a fuel tank 1 having a built-in component 10 by blow molding, which is an embodiment of the present invention, will be described with reference to FIGS. The blow molding device used in the embodiment of the present invention includes a die core 60 for extruding the parison 8, a blow molding die 20 for molding a blow molded product, a parison clamping device 30 for clamping the lower end of the parison 8, and a built-in device. The component 10 includes a built-in component holding device 40 that holds the component 10 in the built-in component hermetic guide cylinder 42 and inserts the component 10 into the parison 8 in the blow molding die 20.

As shown in FIG. 2, the built-in component 10 attached to the inside of the fuel tank 1 that is a blow-molded product is formed so as to project laterally from the outer surface, and is held by a slide core holding portion 26a of a slide core 26 described later. A plurality of built-in component attachment portions 12 to be welded to the parison 8 are provided.
Further, the built-in component 10 is provided with a built-in component holding hole 11 into which a built-in component holding rod 41 of a built-in component holding device 40 described later is inserted.

As shown in FIG. 10, in the case where the built-in component 10 is large and is formed to be bent in a hollow shape or a plate shape, two built-in component holding holes 11 can be formed on the upper and lower sides. In that case, a built-in component holding hole 11 below the built-in component 10 into which the built-in component holding rod base 41b is inserted is formed large, and an upper built-in component holding hole 11 into which the built-in component holding rod tip 41a is inserted. Is formed small.

Since the two built-in component holding holes 11 are formed at the top and bottom, the built-in component holding bar 41 can stably hold the built-in component 10.
When the built-in component 10 is large, it is preferable to insert and hold a plurality of built-in component holding bars 41 in the built-in component 10. In this case, it is preferable that each built-in component holding rod 41 inserts two built-in component holding holes 11.

As shown in FIG. 11, the lower built-in component holding hole 11 forms a built-in component holding hole protrusion 11a toward the center. When the built-in component holding rod base 41b is inserted into the built-in component holding hole 11, the built-in component holding hole protrusion 11a comes into contact with the built-in component holding rod base 41b, and the built-in component holding rod 41 moves up and down. On the other hand, sliding resistance can occur.
Further, a protruding portion can be formed around the built-in component holding rod base portion 41 b to generate a sliding resistance with the built-in component holding hole 11.

As shown in FIG. 12, the built-in component holding hole 11 is similarly formed in the upper built-in component holding hole 11 toward the center. When the built-in component holding rod tip 41a is inserted into the built-in component holding hole 11, the built-in component holding hole protrusion 11a comes into contact with the built-in component holding rod root 41b, and the built-in component holding rod 41 moves up and down. On the other hand, sliding resistance can occur.

Since sliding resistance is generated by the upper and lower built-in component holding holes 11 respectively, the built-in component mounting portion 12 can be strongly pressed against the parison 8 held by the slide core holding portion 26a.
Further, similarly to the built-in component holding rod base portion 41 b, a protruding portion can be formed around the built-in component holding rod tip 41 a to generate a sliding resistance with the built-in component holding hole 11.

When the die core 60 extrudes the parison 8 and opens the blow molding die 20, the parison 8 is positioned inside the die core 60, and the upper end of the parison 8 is held so that the inside of the parison 8 at the time of pre-blow described later can be obtained. Prevent gas outflow. The upper end of the parison 8 can be hermetically sealed using an upper pinch plate.

Next, the blow mold 20 will be described with reference to FIG.
The blow molding die 20 is divided into two parts by a parting line, and is slid so that it can be opened to the left and right by a blow molding die moving device (not shown). The blow molding die 20 has a cavity 22 that forms the fuel tank 1 therein. Furthermore, slide cores 26 are provided in the cavities 22 of the left and right blow molding dies 20, respectively.

The slide core 26 forms part of the inner surface of the cavity 22 when the blow molding die 20 is closed and the slide core 26 is retracted, and the blow molding die 20 is opened and advanced into the cavity 22. In some cases, a later-described built-in component 10 and a parison 8 are held. A plurality of slide cores 26 are provided on the left and right blow molding dies 20 according to the shape of the built-in component 10.

A slide core holding portion 26a that holds the built-in component mounting portion 12 formed at the tip of the built-in component 10 is formed at the tip of the slide core 26, and the built-in component 10 is held by the slide core holding portion 26a. The slide core holding part 26a is formed in a step shape and can be held so as to support the built-in component attachment part 12. Since the built-in component 10 can be held by the slide core holding portion 26 a, the weight of the built-in component 10 can be received by the slide core holding portion 26 a perpendicular to the gravity of the built-in component 10, and the built-in component 10 can be laterally moved by the slide core 26. Therefore, the built-in component 10 is not displaced by its own weight, and it is not necessary to increase the rigidity for preventing the shift, and the built-in component 10 can be downsized.

A parison clamping device 30 that clamps the lower end of the parison 8 is provided below the blow molding die 20, and the parison clamping device 30 is inserted into the lower end of the parison 8 that comes out from the lower portion of the blow molding die 20. An expander 31 and a parison outer clamping plate 32 that clamps the outer surface of the lower end of the parison are provided.

A plurality of parison expanders 31 are attached so that the lower end of the parison 8 can be expanded. In the present embodiment, four pieces are attached so as to correspond to four corners of a built-in component hermetic guide cylinder 42 described later.
As shown in FIG. 2, a pre-blow outlet 34 is formed at the tip of the parison expander 31 so that a gas such as air can be ejected into the parison 8.

Next, the built-in component holding device 40 will be described with reference to FIGS. The built-in component holding device 40 includes a cylindrical built-in component hermetic guide tube 42, a built-in component holding bellows 44 having the built-in component 10 attached to the built-in component hermetic guide tube 42, and a built-in component hermetic guide tube 42. A built-in component lower guide plate capable of closing the built-in component holding rod 41 and the built-in component holding bellows portion 44 that can move the built-in component 10 in the parison 8 and can move the built-in component 10 vertically. 43.

The built-in component holding bellows portion 44 is formed in a hollow bellows cylinder shape, houses the built-in component 10 inside the hollow, and holds it so as to be movable in the vertical direction. The cross-sectional shape of the built-in component holding bellows portion 44 can be any of a circular shape, an elliptical shape, and a polygonal shape so that the built-in component 10 can be accommodated.

The built-in component holding bellows portion 44 has a built-in component hermetic guide tube 42 in which the lower end of the parison 8 abuts on the upper part and holds the lower end of the parison by the parison outer holding plate 32 of the parison holding device 30. It is formed in the bellows shape which can be expanded-contracted to the up-down direction between 42 and the part to which the built-in component lower guide plate 43 is attached.

For this reason, when the built-in component 10 is attached to the built-in component holding rod 41 and the built-in component holding rod 41 is slid and inserted into the parison 8, the built-in component holding bellows portion 44 can also contract, The sliding distance of the bar 41 can be shortened. Therefore, it is not necessary to reduce the space required for sliding the built-in component holding rod 41 and to provide a special pit for storing the built-in component holding rod 41 below the built-in component holding device 40.

The built-in component holding rod 41 can hold the built-in component 10 so that the built-in component 10 can move up and down, and when the lower end of the parison 8 is sandwiched between the built-in component hermetic guide tube 42, the built-in component airtight guide tube 42 can be made airtight. . When the built-in component 10 to be held is large, a plurality of built-in component holding bars 41 can be provided.

The built-in component holding rod 41 is shown in FIG. 10, and as described above, the built-in component holding rod tip portion 41a is formed thin, and the built-in component holding rod base portion 41b is formed thicker than the built-in component holding rod tip portion 41a. May be. The built-in component holding rod base portion 41 b and the built-in component holding rod tip portion 41 a are formed such that sliding friction occurs between the built-in component holding hole 11 and the built-in component holding hole 11. In order to cause sliding friction, even if a protrusion or groove is formed on the outer periphery of the built-in component holding rod base 41b and the built-in component holding rod tip 41a, the protrusion or notch is formed on the inner periphery of the built-in component holding hole 11. May be formed.

The built-in component 10 only needs to be held inside the built-in component holding bellows portion 44, and a wide range of built-in components 10 can be used. Furthermore, by changing the standby position before insertion of the built-in component 10 to the built-in component holding bellows 44, it is easy to change the specifications of the built-in component 10.

Next, the manufacturing method of the fuel tank 1 for motor vehicles which is a blow molded product using the blow molding apparatus of embodiment of this invention is demonstrated based on FIGS.
A die core 60 is provided on the upper part of the blow mold 20. A parison clamping device 30 is attached to the lower part of the blow molding die 20 as shown in FIGS.
As shown in FIG. 2, in blow molding, first, the blow molding die 20 is opened to open a space constituting the cavity 22, and the parison 8 is extruded from the die core 60 therein. Then, the lower end of the parison 8 reaches below the mold lower part 24 of the blow molding mold 20.

Next, the plurality of parison expanders 31 enter the inner surface of the lower end of the parison 8 and come into contact therewith. And the parison expander 31 opens in the direction away from the center of the parison 8 as shown by the arrow in FIG.
At that time, the built-in component holding device 40 holding the built-in component 10 is positioned below the lower end of the parison 8.

Next, as shown in FIG. 3, the upper end of the parison 8 is held by the die core 60, and the upper portion of the parison 8 is held in an airtight state.
Then, the upper end of the built-in component hermetic guide cylinder 42 is inserted into the lower end of the parison 8. The parison expander 31 comes into contact with the built-in component airtight guide cylinder 42. The outer surface of the lower end of the parison 8 is pressed by the parison outer clamping plate 32 and moves toward the built-in component airtight guide cylinder 42.

The lower end of the parison 8 is clamped by the parison outer clamping plate 32 and the built-in component airtight guide cylinder 42. At this time, the parison expander 31 is integrated with the built-in component airtight guide cylinder 42 and sandwiches the inner surface of the lower end of the parison 8. The lower end of the built-in component holding bellows portion 44 is closed by the built-in component lower guide plate 43, and the lower end of the parison 8 is airtight.

Next, as shown in FIG. 4, pre-blow is performed. Pre-blowing can be performed by inflating the parison 8 by blowing gas into the parison 8 from the tip of the parison expander 31. As shown in FIG. 4, a pre-blow outlet 34 is formed at the tip of the parison expander 31. Gas can be blown into the parison 8 from the pre-blow outlet 34. In the present embodiment, air is used as the gas blown into the parison 8.

At this time, in the upper part of the parison 8, the parison 8 is blocked by the die core 60 as described above. In the lower part of the parison 8, the parison 8 is blocked by the built-in component airtight guide cylinder 42, the parison expander 31, and the built-in component holding bellows 44 as described above to prevent air from escaping. Further, in the lower part of the built-in component holding bellows portion 44, the built-in component lower guide plate 43 is blocked to prevent air from escaping.

Next, as shown in FIG. 5, the built-in component holding rod 41 holding the built-in component 10 from the built-in component airtight guide cylinder 42 is slid upward in the parison 8 inflated by pre-blow, so that the blow mold 20 The built-in component 10 is positioned at the position of the cavity 22. At this time, since the parison 8 is swollen by pre-blow, the built-in component 10 does not come into contact with the inner wall of the parison 8.

Further, when the built-in component 10 is slid by sliding the built-in component holding rod 41 to hold the built-in component 10 at a position facing the cavity 22 of the blow molding die 20, the built-in component holding bellows portion 44 is compressed, The air in the built-in component airtight guide cylinder 42 can be sent into the parison 8 and pre-blowed for the second time. For this reason, the parison 8 can be further inflated. The parison 8 is expanded by this two-stage pre-blow, and the built-in component 10 can be inserted into the parison 8 more reliably without contacting the parison 8.

Then, as shown in FIG. 6, the blow molding die 20 is slightly closed and a plurality of slide cores 26 provided on the blow molding die 20 are slid. At this time, the plurality of slide cores 26 are provided at positions corresponding to the built-in component mounting portion 12, and the slide core holding portion 26 a slides to a position where the built-in component mounting portion 12 is held. The parison 8 comes into contact with the surface of the slide core 26 of the blow molding die 20.

Next, as shown in FIG. 7, the built-in component holding bar 41 is lowered. Then, the built-in component mounting portion 12 of the built-in component 10 abuts on the parison 8 that abuts on the slide core holding portion 26 a of the slide core 26. Further, when the built-in component holding rod 41 is slid downward, the built-in component holding rod base portion 41 b and the built-in component holding rod tip 41 a slide friction between the built-in component holding hole 11. Therefore, as shown in FIG. 9, the built-in component mounting portion 12 is pressed against the parison 8 on the slide core holding portion 26a. Therefore, the built-in component mounting portion 12 can be strongly pressed against the parison 8 due to the pressing force due to sliding friction.

Then, since the inner surface of the parison 8 is still in a molten state, the built-in component mounting portion 12 of the built-in component 10 and the parison 8 can be fused. At this time, since the built-in component 10 is held by the slide core holding portion 26 a, the built-in component 10 can be reliably attached to a predetermined position on the inner surface of the outer wall of the fuel tank 1.

Thereafter, with the built-in component mounting portion 12 held by the slide core holding portion 26 a, the built-in component holding rod 41 is lowered and removed from the blow molding die 20. At this time, since the lower end of the parison 8 is held and sealed by the parison outer holding plate 32 of the parison holding device 30 and the built-in component lower guide plate 43 is positioned and sealed at the lower end of the built-in component holding bellows portion 44, Air does not leak from inside the parison 8.

Furthermore, as shown in FIG. 8, the blow molding die 20 is further closed, and the blow molding die 20 is completely closed. Thereby, the upper part and the lower part of the parison 8 can be completely closed by the blow molding die 20.
In the parison 8, the upper abutment surface of the upper mold portion 23 and the lower abutment surface of the lower mold portion 24 of each of the blow molds 20 formed by dividing the parison 8 into two are in contact with each other. The top and bottom of 8 can be closed. Alternatively, a pinch plate as shown in the prior art may be provided between the blow molding die 20 and the parison clamping device 30 to close the upper or lower portion of the parison 8.

Then, the top and bottom of the parison 8 are cut by slide cutters (not shown) provided on the top and bottom of the blow molding die 20. Then, air is blown into the inside of the parison 8 from the air nozzle 27, and the outer surface of the parison 8 is pressed against the inner surface of the cavity 22 of the blow molding die 20 to form the shape of the fuel tank 1.

At this time, the front end surface of the slide core 26 and the inner surface of the cavity 22 of the blow molding die 20 can be on the same plane except for the slide core holding portion 26a. Further, air is blown into the inside of the parison 8 from the air nozzle 27, and the outer surface of the parison 8 is completely pressed against the blow molding die 20, so that the shape of the fuel tank 1 is completely formed. Then, air is circulated inside the parison 8 to complete blow molding. Thereafter, the blow mold 20 is opened and the fuel tank 1 is taken out.

DESCRIPTION OF SYMBOLS 1 Fuel tank 8 Parison 10 Built-in component 11 Built-in component holding hole 12 Built-in component attachment part 20 Blow molding die 22 Cavity 26 Slide core 26a Slide core holding part 30 Parison clamping device 40 Built-in component holding device 41 Built-in component holding rod

Claims (3)

In a blow molding method for molding a blow molded product in which a built-in component is attached,
The blow molding method includes a die core for extruding a parison, a blow mold for molding an outer wall of a blow molded product, a parison clamping device for clamping the lower end of the parison, and a built-in component for holding the built-in component before blow molding Using the holding device,
The blow molding die has a split mold formed by dividing it into two parts by a parting line, a cavity for forming the blow molded product is formed on the opening / closing surface, and the cavity can be moved back and forth on the inner surface of the cavity. A slide core holding portion is formed at the tip of the slide core to hold a built-in component mounting portion formed on the outer surface of the built-in component, and the slide core holding portion holds the built-in component mounting portion. And molding the outer wall of the blow molded product in the cavity,
A parison clamping device for clamping the lower end of the parison is provided below the blow mold,
The built-in component holding device has a built-in component holding bar that holds the built-in component and is slidable in the vertical direction, and the built-in component holding bar is inserted into a built-in component holding hole formed in the built-in component. The built-in component holding rod is inserted so that sliding friction occurs in the built-in component holding hole,
Open the blow molding die, slide the built-in component holding rod from the lower end of the parison, position the built-in component in the parison, and hold the built-in component in a position facing the cavity. The blow molding die is closed, the built-in component is positioned inside the parison, the parison is brought into contact with the slide core, and the built-in component attaching portion is sandwiched between the parison and the slide core holding portion After holding in, the built-in component holding rod is lowered downward, the built-in component mounting portion is pressed against the parison held by the slide core by sliding friction, and welded,
A blow molding method for forming a blow molded product by closing the blow molding die and sandwiching the upper and lower portions of the parison between the upper end and the lower end of the blow molding die and then blowing a gas into the parison. 2. The blow molding method according to claim 1, wherein a cross-section of the built-in component holding rod or the built-in component holding hole is formed in an uneven shape, and the built-in component is held so that sliding friction is generated in the built-in component holding rod. . 3. The blow molding method according to claim 1, wherein a plurality of the built-in component holding rods are inserted into the built-in component, and each of the built-in component holding rods is inserted into the plurality of built-in component holding holes.