JPH05229015A - Manufacture of fuel tank - Google Patents

Abstract

PURPOSE:To secure bond strength and airtightness in a bonding part by enabling opening-peripheral parts of depressed moldings of upper and lower parts constituting a fuel tank to be bonded to each other in a high temperature state. CONSTITUTION:A high temperature state melted resin sheet 22 is extruded conforming to a mold size to be put fixedly on a projected metal mold 46. Suction holes 34 provided to an inner wall 32 of a depressed mold 30 capable of being mated with the projected mold 46 are evacuated with a vacuum device 40, and a heated film 42 of the same quality as the resin sheet 22 is stuck fast to the inner wall 32 of the depressed metal mold 30. The projected mold 46 is mated with the depressed mold 30. They are thermally compressed and thereafter the molds are opened. The depressed mold 30 wherein high temperature state depressed moldings manufactured thus are held is mated with another mold wherein high temperature state depressed moldings manufactured in the same way are held, and they are thermally compressed. Since a bond part of the depressed moldings is welded in a high temperature state, their bond strength is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a hollow fuel tank.

[0002]

2. Description of the Related Art Hollow containers such as resin fuel tanks are generally manufactured by blow molding.

This blow molding method, as shown in FIG.
The tubular parison 52 is extruded from the extruder 50 through the blow molding die 54, and the parison 52 is extruded continuously or intermittently from the die 54.
After sandwiching between the two concave molds 56, closing the concave mold 56 and sealing the upper and lower sides thereof, air is blown into the parison 52 from the blow pin 58 to expand the parison 52, and the parison 52 is closely attached to the inner wall 56A of the concave mold 56. Then, a hollow fuel tank is manufactured.

However, when a large fuel tank is manufactured by this blow molding method, the wall thickness of the upper part tends to be smaller than that of the lower part due to the weight of the parison 52 in a fluid state, and the wall thickness cannot be made uniform. It was Further, in the complicated shape, when the parison 52 is expanded, the expansion rate of the parison 52 varies depending on the part of the product, so that the wall thickness cannot be made uniform. Further, since it is difficult to insert the assist plug into the parison 52 and perform stamping molding (post-processing of the inner surface of the parison), the wall thickness cannot be reduced and the weight cannot be reduced. Further, in order to manufacture the fuel tank, the parison 52 that is longer than the length of the fuel tank is required, and the amount of burrs generated in the gap of the concave die 56 increases, resulting in poor productivity.

In order to solve these problems, a resin material in a high heat state is sandwiched between a pair of metal molds having a concave shape and a convex shape, and the pressure is applied to form a concave shaped article forming the upper and lower portions of a fuel tank. A method for manufacturing a fuel tank as a hollow body is also proposed by manufacturing the respective fuel tanks, cooling them, and then joining the opening peripheral edge portions of the upper and lower concave molded products (Actually published Sho 60-62).
325, JP-B-63-93220, and JP-B-63-93221).

However, in the case where the peripheral edge portions of the upper and lower concave-shaped molded articles which have been once cooled are joined, no matter what means is taken, there remains a problem in the joining strength and airtightness.

Therefore, in order to ensure the reliability of the joint, the concave molds are heat-molded and still in a high temperature state, and the concave molds are matched with each other. Then, a method of manufacturing a fuel tank as a hollow body by joining the opening peripheral portions of the upper and lower concave shaped products at a high temperature state can be considered.

[0008] However, when a hot-pressed molded product is opened in a high temperature state, the molded product is slightly cooled when the mold is opened, so that the molded product contracts in the convex mold and the molded product is held in the concave mold. May not be retained. Further, even when the molded product can be held in the concave mold, when matching the concave mold holding the molded product forming the upper part and the concave mold holding the molded product forming the lower part, Since the molded product that constitutes the upper part has a low shape-retaining force due to high temperature, there is a risk of falling
It was difficult to join the opening peripheral edge portions of the upper and lower concave shaped products at high temperature.

[0009]

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention makes it possible to join the peripheral edge portions of the openings of the upper and lower concave shaped articles constituting the fuel tank at a high temperature, and the joining strength at the joining portion. Another object of the present invention is to provide a method for manufacturing a fuel tank that ensures airtightness.

[0010]

In the method of manufacturing a fuel tank according to the first aspect of the present invention, a fixed concave metal mold having a concave opening at an upper side and a rotary concave metal mold are connected to the fixed concave metal mold so that they can be matched with each other. And a rotary concave metal mold, wherein a molten resin sheet in a high temperature state is extruded and placed on the rotary concave metal mold corresponding to the dimensions of the fixed concave metal mold and the rotary concave metal mold. A second step of sandwiching the outer end of the resin sheet in the high temperature state with a clip provided on the outer peripheral edge of the mold, rotating the rotary concave mold to align it with the fixed concave mold, and heat compression; Is characterized by having.

According to a second aspect of the present invention, there is provided a method of manufacturing a fuel tank, which comprises a first step of extruding and placing a molten high-temperature resin sheet on a convex mold in accordance with a size of the mold, and a mold matching with the convex mold. By the suction holes provided on the inner wall of the possible concave mold,
A second step of bringing a heated film of the same quality as the resin sheet into close contact with the inner wall of the concave mold, the convex mold and the concave mold being combined with each other and thermally compressed, and then the mold is opened. Process, the concave mold holding the high temperature concave shaped article, and another concave metal holding the high temperature concave shaped article separately manufactured by the first to third steps Type and
And a fourth step in which the molds are matched and heat-compressed.

[0012]

In the method of manufacturing the fuel tank according to claim 1,
In the first step, a molten high-temperature resin sheet is put into each of a concave fixed concave mold having an upper opening and a concave rotary concave mold connected to the fixed concave mold and having an upper opening. Extrude and place according to the die size. Next, in the second step, the outer end of the high temperature resin sheet is clamped by the clip provided on the outer peripheral edge of the rotary concave die, and the rotary concave die connected to the fixed concave die is rotated. The fixed concave mold. As a result, the opening peripheral edge portions of the upper and lower concave shaped articles are joined at high temperature, so that the joining strength and airtightness of the joining portion are secured. In addition, since the outer end of the high temperature resin sheet is clamped by the clip, the molded product does not drop at the time of mold matching. In addition, after the first step, a convex mold corresponding to the concave shape is pressed against the fixed concave mold and / or the rotary concave mold to perform stamping molding to process the inner surface,
It is also possible to make the wall thickness uniform and thin. Further, after the mold matching, the blow pin is inserted, and the molded product is brought into close contact with the inner wall of the mold by air pressure while the molded product is cooled, whereby the dimensional accuracy of the product is further improved.

Further, in the fuel tank manufacturing method according to the second aspect, in the first step, the molten high-temperature resin sheet is extruded and placed on the convex mold according to the size of the mold.
Here, a vacuum device is connected to the suction hole provided on the inner wall of the concave mold that can be matched with the convex mold, and by driving this vacuum device, the suction hole is evacuated. can do. Therefore, in the second step, a vacuum film is formed in the suction holes to bring a heated film of the same quality as the resin sheet into close contact with the inner wall of the concave mold.
Next, in a third step, the convex mold and the concave mold are matched with each other and heat-compressed, and then the mold is opened to mold a concave molded article in a high temperature state. At this time, since the film is of the same quality as the resin sheet, the film melted by the high temperature resin sheet and the molded product are welded. Here, since the film is adsorbed to the concave mold, the molded product is held in the concave mold, does not cling to the convex mold when the mold is opened, and also drops when moving the concave mold. There is no.

Next, in the fourth step, a concave die holding the concave molded article in the high temperature state and the first to third steps.
Another concave mold holding a high temperature concave molded product separately manufactured by the process is matched with the mold and thermally compressed. As a result, the joint portion is welded at a high temperature, so that the joint strength is improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, in the method of manufacturing a fuel tank according to the first embodiment, a rotary concave die 10 for molding a concave molded product on the upper part of the fuel tank, and an upper part of the fuel tank. The fixed concave metal mold 12 for molding the concave molded product is used. Arms 14 and 16 are provided on the facing side portions of the rotary concave mold 10 and the fixed concave mold 12, respectively, and are rotatably connected by a connecting pin 18. This connecting pin 1
The mounting position of 8 is the fixed concave mold 1 when the rotary concave mold 10 rotates clockwise about the connecting pin 18 (see FIG. 3).
2 and the rotary concave die 10 are in a position where they can be matched with each other.

A resin sheet 2 extruded into a sheet shape by an extruder 20 is provided around the entire circumference of the side surface of the rotary concave die 10.
A clip 24 for fixing the outer end of 2 to the side of the rotary concave die 10
Is provided. The clip 24 is biased toward the side of the rotary concave die 10 by a torsion coil spring (not shown). As a result, the outer edge of the resin sheet 22 is pressed (see FIG. 2). In addition,
The extruder 20 is guided by a guide rail (not shown), and has a fixed concave mold 12 and a rotary concave mold 10 that open upward.
The molten high-temperature resin sheet is extruded and placed according to the size of the mold.

Here, the procedure of the method for manufacturing the fuel tank will be described. As shown in FIG. 1, first, the fixed concave mold 12 and the rotary concave mold 10 are extruded by an extruder 20.
The molten high-temperature resin sheet 22 is extruded, extruded according to the size of each mold, and placed at a predetermined position. In this way, since the resin sheet 22 is placed in the horizontal state, it is possible to prevent the thickness of the resin sheet 22 from becoming uneven due to its own weight. Also, since the minimum required resin sheet 22 is sufficient,
Productivity is improved and cost is reduced.

Next, as shown in FIG. 2, the rotary concave die 10
The outer end of the resin sheet 22 placed on the is clamped by the clip 24. On the other hand, the resin sheet 22 placed on the fixed concave die 12 is pressed by the assist plug 26 and brought into close contact with the inner wall of the fixed concave die 12. As a result, the resin sheet 22 is drawn while being drawn along the shape of the mold. The drawing operation by the assist plug 26 is performed depending on the complexity of the shape, and can be omitted, and the resin sheet 22 placed on the rotary concave die 10 is pressed by the assist plug 26. May be. Further, since the surface of the assist plug 26 is Teflon coated and has a simple shape, and the inner wall of the fixed concave die 12 is roughly processed, the molded product does not cling to the assist plug 26.

Next, as shown in FIG. 3, the rotary concave die 10 is rotated clockwise with the connecting pin 18 as the center of rotation to align the rotary concave die 10 and the fixed concave die 12. At this time, the resin sheet 22 placed on the rotary concave die 10 is in a high temperature state, but since the outer end of the resin sheet 22 is held by the clip 24, the resin sheet 22 is not separated from the rotary concave die 10. Moreover, since the joint portion of the fuel tank is joined at a high temperature, the joint strength and airtightness are improved.

As shown in FIG. 4, finally, the blow pin 28 is inserted into the molded product formed of the resin sheet 22, and blown with air to expand the rotary recessed mold 10 and the fixed concave mold 12. The hollow fuel tank is completed by bringing it into close contact with the inner wall of the container, cooling it, and then opening the mold.
The blow molding performed last is used for manufacturing a molded product with high dimensional accuracy and is not always necessary.

Next, a method of manufacturing the fuel tank of the second embodiment will be described. As shown in FIG. 5, the method for manufacturing a fuel tank according to the second embodiment is used when the shape of the fuel tank is relatively complicated, and a concave mold 30 for molding a concave molded product on the upper portion of the fuel tank. Adsorption holes 34 are formed in the inner wall 32 at predetermined intervals. The suction holes 34 are in communication with an air passage 36 formed inside the concave die 30.
One end of this air passage 36 is connected to a vacuum device 40 by a flexible pipe 38. by this,
By operating the vacuum device 40, the inside of the suction holes 34 can be vacuumed.

A film holding device 44 for holding the outer periphery of the film 42 of the same quality as the resin sheet 22 is disposed below the concave die 30. This film holding device 4
4 is raised toward the concave mold 30 by a push-up machine (not shown) and presses the film 42 against the outer peripheral edge of the concave mold 30.

Now, the procedure of the method for manufacturing the fuel tank will be described. As shown in FIG. 2, similarly to the first embodiment, the molten resin sheet 22 in the high temperature state is extruded by the extruder 20 (see FIG. 1) and adjusted to the die size of the convex die 46. Cut and place in place. On the other hand, the film 42 held by the film holding device 44 is heated to an appropriate temperature by a heating device (not shown), and is raised toward the concave mold 30 by a push-up machine, so that the film 42 is placed on the outer peripheral edge of the concave mold 30. Press down. At the same time, as shown in FIG. 6, the vacuum device 40 is driven to bring the inside of the suction holes 34 into a vacuum state to bring the film 42 into close contact with the inner wall 32 of the concave die 30.

Next, as shown in FIG. 7, a concave mold 30 is used.
In the state where the film 42 is closely attached to the inner wall 32, the resin sheet 22 is combined with the convex mold 46 on which the resin sheet 22 is mounted, and the compression molding is performed. At this time, since the film 42 is of the same quality as the resin sheet 22, it is melted by the resin sheet 22 in a high temperature state and welded to the resin sheet 22. As a result, as shown in FIG. 8, the molded resin sheet 22 is welded to the film 42 adsorbed by the concave mold 30, and the convex mold 46 is opened when the mold is opened.
Molded resin sheet 22 without clinging to the
However, it does not flow and fall when moving the concave die 30.

Next, although illustration is omitted, similarly, a concave mold and a concave mold 3 for holding a concave molded product in the lower portion of the fuel tank are formed.
0 and the molds are matched, and the concave and upper molded parts are welded at a high temperature. As a result, even in a hollow fuel tank having a relatively complicated shape, the joining strength of the joining portion is ensured.

[0026]

The method of manufacturing a fuel tank according to the present invention comprises:
Since the peripheral edges of the openings of the upper and lower concave parts forming the fuel tank can be joined at a high temperature, the joining strength and airtightness at the joining portion can be secured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing procedure of a method for manufacturing a fuel tank according to a first embodiment.

FIG. 2 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the first embodiment.

FIG. 3 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the first embodiment.

FIG. 4 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the first embodiment.

FIG. 5 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the second embodiment.

FIG. 6 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the second embodiment.

FIG. 7 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the second embodiment.

FIG. 8 is a cross-sectional view showing the manufacturing procedure of the method for manufacturing the fuel tank according to the second embodiment.

FIG. 9 is a schematic view showing a conventional fuel tank manufacturing method.

[Explanation of symbols]

 10 Rotating Recessed Mold 12 Fixed Recessed Mold 24 Clip 30 Recessed Mold 34 Adsorption Hole 42 Film 46 Convex Mold

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B60K 15/03 B65D 8/00 6540-3E 8/18 Z 6540-3E // B29L 22:00 4F

Claims (2)

[Claims] 1. A molten fixed high-temperature state is formed into a concave fixed concave metal mold having an opening at the top and a rotary rotary concave metal mold which is pivotally connected to the fixed concave metal mold so as to be mold-matchable with each other. A first step of extruding and placing a resin sheet according to the mold dimensions of the fixed concave mold and the rotary concave mold, and the resin sheet in the high temperature state by a clip provided on the outer peripheral edge of the rotary concave mold A second step of sandwiching the outer end of the rotary concave die, rotating the rotary concave die to align with the fixed concave die and thermally compress the same. 2. A first step of extruding and placing a molten high-temperature resin sheet on a convex mold according to the size of the mold, and providing the inner wall of a concave mold that can be matched with the convex mold. The second step of bringing the heated film of the same quality as the resin sheet into close contact with the inner wall of the concave mold by the suction holes, and the convex mold and the concave mold are matched with each other and thermally compressed, and then the mold. A third step of opening, the concave mold holding the high temperature concave shaped article, and the high temperature concave shaped article separately manufactured by the first to third steps were held. And a fourth step of heat-compressing another concave mold by matching the molds with each other.