JP3067450B2 - Manufacturing method of resin 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 for manufacturing a resin container, and more particularly to a method for manufacturing a resin container capable of molding a resin container to a uniform thickness and improving the joining strength and airtightness of a joint. About.

[0002]

2. Description of the Related Art A container made of resin is generally manufactured by a blow molding method. In the blow molding method, a tubular parison (molten resin) extruded from an extruder
Is sandwiched between two molds, and air is blown into the parison from the blow nozzle with the molds closed. As a result, the parison comes into close contact with the inner wall surface of the mold, and a resin container having a predetermined shape is formed.

When a large-sized resin container is manufactured by the blow molding method, the thickness of the upper portion tends to be smaller than that of the lower portion due to the weight of the parison in a flowing state, and the thickness cannot be made uniform. As one of the technologies to make the thickness of the resin container uniform, sandwich the high-temperature resin material between concave and convex molds, mold it into a predetermined shape, cool it, and join the peripheral edge of the molded product (Japanese Patent Laid-Open No. 59-209)
No. 531) joins the parts once cooled,
It is difficult to perform welding sufficiently, and there remains a problem in terms of bonding strength and airtightness.

Therefore, as a technique for improving the reliability of the joint, a compression molded high temperature resin molded product is left in one mold while the other high temperature resin molded product is placed on the other mold. There has been proposed a method of inverting a mold, performing mold matching, and joining a peripheral portion of a molded product at a high temperature.

[0005]

However, as described above, in the case of the method of performing mold matching by inverting the other mold, equipment for rapidly inverting a huge mold is required when the size of the resin container is increased. And the manufacturing cost increases. Also,
The production cycle time is prolonged by the time to reverse the mold, and the production efficiency is deteriorated. Because the time that the sheet-like molten resin extruded from the extruder is in contact with the mold is long,
There are problems such as a decrease in the temperature of the sheet-like molten resin and narrowing of the range of molding conditions.

SUMMARY OF THE INVENTION The present invention is directed to a resin container capable of molding a resin container to a uniform thickness and improving the joining strength and airtightness of a joint without inverting a mold. It is intended to provide a manufacturing method.

[0007]

According to the present invention, there is provided a method for manufacturing a resin container, comprising: separating a molten resin extruded from an extruder into two sheets of molten resin;
The separated sheet-shaped molten resins are fixed to each other by clamping a first mold positioned between the sheet-shaped molten resins and a second mold positioned outside each of the sheet-shaped molten resins. Compression-molded into the shape of, then the first mold is retracted to the outside of the second mold by opening the mold of the second mold,
Thereafter, the second mold is clamped again and the peripheral portions of the formed sheet-like molten resins are welded to each other.

[0008]

In the method for manufacturing a resin container configured as described above, the sheet-shaped molten resin is compression-molded by the first mold and the second mold, so that the resin container has a uniform thickness. Becomes possible. Since the molding of the sheet-like molten resin and the joining of the peripheral portion after the molding are performed with the same mold, the temperature drop due to the contact of the peripheral portion with the mold can be suppressed to a small level. Therefore, the peripheral portion can be joined at a high temperature, and the welding of the peripheral portion is reliably performed, so that the joining strength and the airtightness of the peripheral portion are improved.

The joining of the molded sheet-like molten resin is performed by matching the first mold and the second mold in the same manner as at the time of molding, so that there is no need to invert the mold as in the conventional case. In addition, the reversing equipment becomes unnecessary, and the time for reversing becomes unnecessary, thereby improving the production efficiency.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the method for manufacturing a resin container according to the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an embodiment of the present invention, and particularly show a case where the present invention is applied to a resin fuel tank. First, a manufacturing apparatus for carrying out the present invention will be described. In FIG. 1, reference numeral 1 denotes an extruder (blow head on the extruder side). From the extruder 1, a cylindrical molten resin 10 is extruded.

A sheet developing block 2 is disposed immediately below the extruder 1. The upper surface of the sheet developing block 2 is formed in an arc shape. Seat development block 2
A cutter (knife) 3 is attached to the top of the upper surface of the. The cutter 3 cuts the molten resin 10 extruded from the extruder 1 and cuts the two sheets of molten resin 11, 12.
It has the function of separating into

The separated sheet-like molten resins 11 and 12
The first mold 5 is located between them. First mold 5
Has protrusions 5a and 5b that protrude in the left-right direction, respectively. On the upper surface side of the first mold 5, a peripheral molding portion 5c protruding upward is formed. On the lower surface side of the first mold 5, a peripheral molding portion 5d protruding downward is also formed.

Each of the separated sheet-like molten resins 11 and 12
The second molds 6 and 7 are respectively located outside.
The second mold 6 and the second mold 7 are arranged so as to face each other with the first mold 5 interposed therebetween. On the other hand, the second mold 6 has a concave portion 6a that can be fitted with the convex portion 5a of the first mold 5. The other second mold 7 has the first mold 5
A concave portion 7a that can be fitted with the convex portion 5b is formed.

The second dies 6 and 7 can be moved forward and backward with respect to the first dies 5 by driving means (not shown).
The first mold 5 can be moved up and down with respect to the sheet developing block 2 by elevating means (not shown). When molding the sheet-like molten resins 11 and 12, the second mold 6,
Numerals 7 move toward the first mold 5 respectively.

At the time of joining the peripheral edges 11a and 12a of the sheet-like molten resins 11 and 12 formed into a predetermined shape, the first mold 5 escapes from between the second molds 6 and 7 to the outside. It has become. When the first mold 5 is retracted, the second molds 6 and 7 approach each other, and the peripheral portions 11a and 12a of the molten resin are welded by mold clamping.

A nozzle 8 for jetting air is provided below the second molds 6 and 7. Peripheral edge 11 of molten resin
a and 12a are welded at the time of welding,
Air is fed from the nozzle 8 to the inside of the nozzle 7.

Next, a method for manufacturing a resin container and its operation will be described. As shown in FIG. 1, a cylindrical molten resin 10 extruded from an extruder 1 is cut by a cutter 3 provided on the top of a sheet developing block 2. The molten resin 10 cut by the cutter 3 is separated into right and left by contact with the sheet developing block 2.

The sheet-like molten resin 11 separated into right and left,
12 moves downward by its own weight. In this state, the first mold 5 is stationary at a predetermined position, and the second molds 6 and 7
Is away from the first mold 5. One sheet-like molten resin 11 descends toward the space between the first mold 5 and the second mold 6, and the other sheet-like molten resin 12 It descends toward the space between the second mold 7.

When the sheet-like molten resins 11 and 12 drop by a predetermined amount, the second dies 6 and 7 start moving toward the first dies 5, and as shown in FIG. Molds 6 and 7
Of the mold is performed. Thereby, each sheet-like molten resin 11 and 12 is compression-molded by the first mold 5 and the second molds 6 and 7 to be formed into a predetermined shape.

When the sheet-like molten resins 11 and 12 are formed into a predetermined shape, as shown in FIG.
7 moves in a direction away from the first mold 5,
The molds 6 and 7 are opened.

When each of the sheet-like molten resins 11 and 12 moves, the first mold 5 is lowered by an elevating means (not shown), and the first mold 5 is retracted outside the second molds 6 and 7. Let me do. FIG. 4 shows a state in which the first mold 5 has escaped from the second molds 6 and 7.

When the retraction of the first mold 5 is confirmed, the second
The molds 6 and 7 of the second mold 6 and 7 move in the approaching direction again, and the second molds 6 and 7 are clamped as shown in FIG. When the mold clamping of the second molds 6 and 7 is completed, the peripheral edges 11a and 12a of the sheet-like molten resins 11 and 12 are welded.

This welding is performed in the second molds 6 and 7 which are the same as the molding.
Is used, the temperature drop of the peripheral portions 11a and 12a due to the contact with the second molds 6 and 7 is small, and the peripheral portion 11a
a and 12a can be joined in a high temperature state. Therefore,
The peripheral portion 11a and the peripheral portion 12a are sufficiently welded, and the joining strength and airtightness (liquid tightness) of the peripheral portions 11a and 12a, which are joint portions, are increased.

When the peripheral portions 11a and 12a are welded, air is sent through the nozzle 8 into the clamped second molds 6 and 7. As a result, the sheet-like molten resins 11 and 12 come into close contact with the concave portions 6a and 7a of the second molds 6 and 7, and the sheet-like molten resins 11 and 12 are cooled by heat exchange with the molds.

When the molded sheet-like molten resins 11 and 12 are cooled and solidified, the second molds 6 and 7 are opened, and a molded resin fuel tank is taken out. When the removal of the fuel tank is completed, the first mold 5 is moved up by the elevating means (not shown) and returned to the state shown in FIG.

[0027]

According to the present invention, the following effects can be obtained.

(1) Since the sheet-like molten resin separated into two pieces is compression-molded by the first mold and the second mold, the thickness of the resin container is made uniform as compared with the blow molding. And the quality of the resin container can be improved.

(2) Since the same mold is used for joining the peripheral portion of the sheet-like molten resin after molding, the temperature of the peripheral portion decreases due to the contact of the peripheral portion with the mold at the time of joining. Can be kept small, and the peripheral portion can be welded at a high temperature. Therefore, the peripheral portion can be reliably welded, and the joining strength and airtightness of the peripheral portion can be increased.

(3) Since the joining of the peripheral portions of the molding of the sheet-like molten resin is performed by the same die, it is not necessary to invert the mold at the time of joining the peripheral portions as in the related art. Therefore, a mold reversing facility is not required, and the production efficiency can be improved by reducing the time for reversing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a molding apparatus to which a method for manufacturing a resin container according to the present invention is applied.

FIG. 2 is a cross-sectional view showing a molding state of a sheet-like molten resin in the apparatus of FIG.

3 is a cross-sectional view showing a moving state of a second mold after completion of molding of a sheet-like molten resin in the apparatus of FIG.

FIG. 4 is a sectional view showing a retracted state of a first mold in the apparatus of FIG. 1;

5 is a cross-sectional view showing a welding operation state of a peripheral portion of a sheet-like molten resin in the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 5 1st metal mold 6 2nd metal mold 7 2nd metal mold 10 Molten resin 11 Sheet-shaped molten resin 12 Sheet-shaped molten resin 11a Peripheral part 12a Peripheral part

Claims (1)

(57) [Claims] 1. A molten resin extruded from an extruder is separated into two sheet-shaped molten resins, and each of the separated sheet-shaped molten resins is placed between first and second sheet-shaped molten resins.
The compression molding into a predetermined shape by clamping the mold and the second mold located outside each of the sheet-like molten resin,
Thereafter, the first mold is retracted to the outside of the second mold by opening the mold of the second mold, and thereafter, the second mold is clamped again to form the respective sheet-shaped melts. A method for manufacturing a resin container, comprising welding peripheral portions of resin.