JP2003236888A - Molding method for hollow resin product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of molding even a thin hollow resin product, easily, rationally and inexpensively. <P>SOLUTION: By using a mold 30 equipped with a slide mold 61 slidable in a direction crossing the mold opening/closing direction between a movable mold 32 and a fixed mold 52, a pair of split members 11, 21 provided with engaging holes 15 and engaging claws 25 at the respective connecting parts and constituting the hollow resin product by allowing the connecting parts to be abutted are injected and molded at a position mutually shifted between the movable mold 32 and the slide mold 61. Afterward, the movable mold 32 and the slide mold 61 are separated in the state keeping one split body 11 in the movable mold 32 and the other split body 21 in the slide mold 61, and the slide mold 61 is made to slide to align the engaging holes 15 and the engaging claws 25 of both split members 11, 21. Then, the space between the movable mold 32 and the slide mold 61 is closed to engage the engaging hole 15 with the engaging claw 25. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for molding a hollow resin product.

[0002]

2. Description of the Related Art Conventionally, as a method for molding a hollow resin product,
The blow molding method is often used. This blow molding method
In the method of extruding resin into a tubular parison from the extruder, sandwiching the parison with a mold before cooling, blowing compressed air into the parison to inflate it into the inner shape of the mold, and then cooling to obtain a hollow resin product. is there.

[0003]

However, in the blow molding method, the cooling time is long, which causes the molding cycle to be longer than that of the injection molding. Also,
To inflate a tubular parison with a mold,
The portion sandwiched between the molds forms a hard burr, which is formed on the outer surface of the product, and there is the inconvenience of removing the burr by post-processing. Moreover, since burrs are formed on the outer surface of the product with a three-dimensional shape, it is difficult to remove burrs automatically by machining, and deburring work must be performed manually, which makes the work complicated and increases costs. linked.

In recent years, DSI (die slide injection) molding has been proposed as a molding method for hollow resin products. In this DSI molding, as shown in FIG. 9, an injection molding die 70 including a slide die 75 between a movable die 71 and a fixed die 73 is used. Then, first, between the movable die 71 and the slide die 75, the two divided bodies P1 and P2 each having a shape obtained by dividing the hollow resin product are injection-molded by shifting the positions in a state of facing each other (temporary injection). Next, with one divided body P1 held by the movable die 71 and the other divided body P2 held by the slide die 75, the movable die 7 is held.
1 and the slide die 75 are opened, and in that state, the slide die 7
5 is slid upward so as to intersect with the mold opening / closing direction to align the positions of both of the divided bodies P1 and P2, and as shown in FIG. 10, the movable die 71 and the slide die 75 are closed so that the divided bodies P1 and P2 are mutually separated. The joining portions S1 and S2 of are joined together. At that time, a space S3 for joining resin is formed between the joining end faces of the two divided bodies P1 and P2, which is a combination of grooves formed on both joining end faces by the injection molding. In that state, the resin is injected into the bonding resin space S3 (two-hour injection)
Then, the joint portions S1 and S2 are welded with a resin to obtain a desired hollow resin product. 9 and 10, reference numeral 81 is a movable plate, 83 is a fixed plate, 85 is an injection machine, and 87 is a sprue bush.

However, in the above-mentioned DSI molding, since it is necessary to form a groove for the space for the bonding resin in the joint end surface of both divided bodies, both the divided bodies have a thickness capable of forming a groove in the joint end surface. Limited. Therefore, when DSI molding is used for molding a hollow resin product, it is not suitable for a thin hollow resin product such as an air conditioning duct of an automobile.

The present invention has been made in view of the above points, and provides a method for molding a thin hollow resin product in a simple, rational, and inexpensive manner.

[0007]

SUMMARY OF THE INVENTION The present invention uses a mold provided with a slide mold which is slidable between a movable mold and a fixed mold in a direction intersecting with a mold opening / closing direction, and has a fitting means at a joint portion thereof. A pair of divided bodies that form a hollow resin product by abutting the joint portions are injection-molded at positions displaced from each other between the movable die and the slide die, and then one of the divided bodies is attached to the movable die and the other. Between the movable die and the slide die after opening the space between the movable die and the slide die while holding the divided die in the slide die and then sliding the slide die to align the fitting means of both the divided bodies. The present invention relates to a method for molding a hollow resin product, characterized by:

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view of a hollow resin product obtained by an embodiment of the molding method of the present invention, FIG. 2 is a vertical sectional view of a mold used in the embodiment of the present invention at a central position, and FIG. FIG. 4 is a vertical cross-sectional view taken at a position passing through the mold fitting means molding portion, FIG. 4 is an enlarged cross-sectional view of an essential part near one of the divided body molding cavities in FIG. 3, and FIG. FIG. 6 is an enlarged cross-sectional view of an essential part, FIG. 6 is a vertical cross-sectional view of the mold in the mold open state, FIG. 7 is a vertical cross-sectional view of the mold in the slide state, and FIG. It is a longitudinal cross-sectional view which expands and shows.

A hollow resin product 10 shown in FIG. 1 is made of a synthetic resin tubular body used for an air conditioning duct of an automobile, and the tubular body is divided into two in the longitudinal direction.
1 and 21, and is molded by practicing the present invention using the mold 30 shown in FIGS. 2 and 3. Incidentally, the molding method of the present invention is not limited to a cylindrical product having both ends opened, and a cylindrical product having only one end opened,
It is applied to the molding of a hollow resin product having an appropriate shape such as a hollow cylindrical product with both ends closed, or a hollow box product with the entire circumference closed.

In the divided bodies 11 and 21, the divided portions of the hollow resin product constitute joint portions 12 and 22, and the joint portions 12 and 2 are formed.
Fitting means 13, 23 are provided on the outer surface of 2 at predetermined intervals in the longitudinal direction.
Are formed. In the fitting means 13 and 23 of this example, the outward projecting piece 14 is formed in the joint portion 12 of one of the split bodies 11, and the fitting hole formed in the projecting piece 14 (reference numeral 15 in FIGS. 6 to 8 etc.). And a fitting claw (a portion indicated by reference numeral 25 in FIGS. 6 to 8 and the like) formed in the joint portion 22 of the other divided body 21. As can be seen from FIG. 8, the fitting hole 15 has a size such that the intermediate shaft portion 26 of the fitting claw 25 can be inserted, and more than the maximum portion of the tip locking claw 27 of the fitting claw 25. By making the tip locking claw 27 small, it is forcibly inserted into the fitting hole 15 so that the fitting hole 15 expands and the tip locking claw 27 can be inserted and fitted.

A mold 30 used for molding the hollow resin product 10 is a movable mold 32 attached to a movable plate 31 of an injection molding machine and a fixed mold 52 attached to a fixed plate 51.
And a slide mold 6 between the movable mold 32 and the fixed mold 52.
1 and 1. The movable plate 31 is attached to a base (not shown) of the injection molding machine, and can be moved forward and backward in the horizontal direction by a mold opening / closing device (not shown) so that the movable plate 31 can approach and separate from the fixed plate 51. Further, as shown in FIG. 2, an injector 53 is attached to the fixed platen 51 substantially at the center thereof.

The movable die 32 is provided with a movable plate 31 by an opening / closing device.
Together with this, it moves forward or backward, and as shown in FIG. 6, it can be opened and closed with the slide die 61. In the movable die 32, a divided body forming cavity 34 and a divided body forming convex portion 35 are formed on a surface facing the slide die 61 at a predetermined interval (upper and lower predetermined intervals in this example). The split body molding cavity 34 corresponds to the outer surface of one of the split bodies obtained by splitting the hollow resin product molded by the mold 30 into two. In this example, in the tubular hollow resin product 10 of FIG. It has a substantially concave cross section corresponding to the outer surface of one of the divided bodies 11.

In the divided body molding cavity 34, the portion corresponding to the joint portion 12 of the one divided body 11 is located at the position of the mold matching portion (parting line) 36. Further, the fitting means 13 of one of the divided bodies 11 in the hollow resin product 10, in this example, the outward protruding piece 1
Fitting means forming part 37 for the fitting hole 15 formed in 4
However, as can be better understood from FIG.
And the slide mold 61 are formed between the mold-matching portions 36 and 62 from the divided body molding cavity 34. In the fitting means forming portion 37, a recess 38 is formed in the portion of the movable die 32 corresponding to the fitting hole 15 of the split body 11, and the tip locking claw 27 of the fitting claw 25 at the time of fitting means fitting described later. Are accommodated in the recessed portion 38. Further, a slide member 39 is provided on the mold matching portion 36 of the movable mold 32 outside the fitting means molding portion 37. This slide member 39 is formed by a known slide means (not shown), such as a cylinder device, an inclined pin, etc.
7, the side surface 39a on the side of the fitting means forming portion constitutes the outer side surface 37a of the fitting means forming portion 37 when approaching.

The divided body molding convex portion 35 has a shape corresponding to the inner surface of the other divided body 21, and is shown in FIGS.
As will be better understood from the above, a recess 40 corresponding to the tip locking claw 27 is formed in the portion corresponding to the fitting claw 25. Divided body molding cavity 3 in the movable mold 32
4 and the divided body molding convex portion 35 are spaced apart from each other by the slide member 3
It is determined in consideration of the slide amount of 9 or the like. Further, in the movable die 32, as shown in FIG. 2, a runner 41 and a gate 42 are formed between the divided body forming cavity 34 and the divided body forming convex portion 35.

The slide die 61 is attached to the fixed die 52, and as shown in FIGS. 6 and 7, in the die open state in which the movable die 32 and the slide die 61 are opened, the cylinder device 63 moves the die in the die opening / closing direction. It is slidable in the direction intersecting with each other. In this example, the mold opening / closing direction Q is horizontal and the vertical direction R intersecting with the mold opening / closing direction Q is the slide mold 6
The slide direction is 1. The cylinder device 63
Is the arm 6 fixed to the lower side of the fixed mold 52 in this example.
It is provided above the slide die 61 with the interposition of the No. 4 side.

On the surface of the slide die 61 facing the movable die 32, one of the divided bodies 11 of the hollow resin product 10 is better understood from FIGS.
The divided body forming convex portion 65 corresponding to the inner surface of the divided body 21 and the divided body forming cavity 67 corresponding to the inner surface of the other divided body 21,
The movable mold 32 is formed so as to be vertically separated by a distance equal to the distance between the divided body forming cavity 34 and the divided body forming convex portion 35.

The divided body molding convex portion 65 of the slide die 61 has a fitting hole formed in the die fitting portion (parting line) 62 with the movable die 32 to form the fitting hole 15 of the one divided body 11. Forming pins 66 are provided so as to project.

In the divided body molding cavity 67 of the slide die 61, a portion corresponding to the joint portion 22 of the other divided body 21 is a die matching portion (parting line) 62.
The position is set to. Further, the fitting means 23 of the other divided body 21, in this example, the fitting means forming portion 68 for the fitting claw 25, is slid from the divided body forming cavity 67 of the slide die 61 to the movable die 32 and slides. It is configured between the mold matching portions 36 and 62 of the mold 61. Further, a slide member 69 is provided outside the fitting means molding portion 68 in the mold matching portion 62 of the slide mold 61. The slide member 69 can be moved toward and away from the fitting means molding portion 68 by a known sliding means (not shown), such as a cylinder device or an inclined pin, and when approaching, the side surface on the fitting means forming portion side. 69a constitutes the outer side surface 68a of the fitting means forming portion 68.

A sprue bush 55 is provided at the center of the fixed die 51. Reference numeral 56 is a sprue.

A method of molding the hollow resin product of FIG. 1 using the mold 30 will be described below. First, FIG.
As shown in FIG. 5, the divided body forming cavity 34 of the movable die 32 and the divided body forming convex portion 65 of the slide die 61 are
Further, the slide die 61 is arranged so that the divided body forming convex portion 35 of the movable die 32 and the divided body forming cavity 67 of the slide die 61 are correctly opposed to each other, and in this state, the movable plate is advanced to move the movable die 32 and the slide mold 61 are closed. As a result, a molding space for the two divided bodies 11 and 21 is formed between the movable die 32 and the slide die 61 with a predetermined gap vertically. At that time, the slide members 39 and 69 of the mold matching portions 36 and 62 are
The side surfaces 39a, 69a on the side of the fitting means forming portions, which are located near the fitting means forming portions 37, 68, respectively, form the outer side surfaces 37a, 68a of the fitting means forming portions 37, 68.
Then, the mold is clamped, and the resin is injected from the injection machine 53 into the molding space to mold the two divided bodies 11 and 21. At that time, the fitting hole 1 is provided in the joint portion of the one divided body 11.
The protruding piece 14 having 5 is formed by the fitting means forming portion 37, and the fitting claw 25 is formed by the fitting means forming portion 68 at the joint portion of the other divided body 21. The movable mold 3
The second slide member 39 contacts the protruding piece 14 having the fitting hole 15 to support the protruding piece 14, and the slide member 69 of the slide die 61 contacts the shaft portion 26 of the fitting claw 25. To support the fitting claw 25.

Thereafter, the mold clamping is released, and the movable platen 31 is retracted to open the movable mold 32 and the slide mold 61 as shown in FIG. At that time, one divided body 11 is separated from the slide mold 61 while being held in the divided body molding cavity 34 of the movable mold 32, and the other divided body 21 is separated from the slide mold 6.
It is separated from the movable mold 32 while being held in the first divided body molding cavity 67.

Then, as shown in FIG. 7, in the mold open state, the slide die 61 is slid upward by the operation of the cylinder device 63, and one of the split bodies 11 held by the movable die 32 and the slide die 61. The other divided body 21 held by is correctly opposed. Then, as shown in FIG. 8, the slide member 39 of the movable die 32 is moved away from the protruding piece 14 in which the fitting hole 15 is formed (in this example, the upper slide member 39U is upward, and the lower slide member 3 is).
9L is slid downward) to separate from the protruding piece 14, and the slide member 69 of the slide die 61 is fitted with the fitting claw 2
5 (in this example, the upper slide member 69U is upward and the lower slide member 69L is downward)
Slide it away from the fitting claw 25. While sliding the slide members 39 and 69 or after the slide is completed, the movable platen 31 is moved to the fixed platen 51 side to close the movable mold 32 and the slide mold 61, and the two divided bodies 1
The joint portions of 1 and 21 are butted and the fitting claw 25 is fitted into the fitting hole 15. At the time of the fitting, since the protruding piece 14 having the fitting hole 15 and the fitting claw 25 are not supported by the slide members 39 and 69, respectively, the deformation at the time of fitting is facilitated and the fitting is ensured. It can be performed. In addition, the fitting between the fitting claw 14 and the fitting hole 25 is performed by the split body 11,
It is preferable that the resin of 21 retains some flexibility before being completely cured. By doing so, the fitting hole 25 is easily deformed during the fitting, and the fitting claw 14 can be inserted into the fitting hole 25 more smoothly.

By the fitting of the fitting means, both split bodies 11,
21 are joined together to form the hollow resin product 10 shown in FIG. Then, the movable platen 31 is retracted to open the space between the movable mold 32 and the slide mold 61, and the hollow resin product 10 is released from the mold to obtain a desired product.

Although the fitting hole and the fitting claw are shown as the fitting means in the above description of the embodiment, the present invention is not limited to this.

[0025]

As shown and described above, according to the method for molding a hollow resin product of the present invention, after the divided body is injection-molded, the slide die is slid without closing the die and the die is closed again. Since both divided bodies can be joined and integrated, a hollow resin product can be molded easily, reasonably and inexpensively. Moreover, unlike the conventional DSI molding in which the joining resin is secondarily injected into the groove formed in the joining end face to perform the welding and joining, in the present invention, the fitting means formed in the joining portion of the divided body is fitted. Therefore, even a hollow resin product having a thin joint can be favorably molded, and there is a high degree of freedom regarding the type and shape of the product.

[Brief description of drawings]

FIG. 1 is a perspective view of a hollow resin product obtained by an embodiment of a molding method of the present invention.

FIG. 2 is a vertical cross-sectional view of a mold used in an embodiment of the present invention at a central position.

FIG. 3 is a vertical cross-sectional view of the mold at a position passing through a fitting means molding portion.

FIG. 4 is an enlarged cross-sectional view of an essential part near one of the divided body molding cavities in FIG.

5 is an enlarged cross-sectional view of an essential part near the other split body molding cavity in FIG.

FIG. 6 is a vertical cross-sectional view of the mold in a mold open state.

FIG. 7 is a vertical cross-sectional view of the same mold in a sliding state.

FIG. 8 is an enlarged vertical cross-sectional view showing a part of the mold halfway in the closed state in the sliding state.

FIG. 9 is a vertical cross-sectional view of a mold showing the time of primary injection by conventional DSI molding.

FIG. 10 is a vertical cross-sectional view of a mold showing the time of secondary injection by conventional DSI molding.

[Explanation of symbols]

10 Hollow Resin Product of One Example Obtained by Implementing the Present Invention 11 Divided Ones 12, 22 Joined Parts 13, 23 Fitting Means 14 Projecting Piece 15 Fitting Hole 21 Other Divided 25 25 Fitting Claw 30 Gold Mold 31 Movable Plate 32 Movable Molds 34 and 67 Divided Body Molding Cavities 35 and 65 Divided Body Molding Convex Part 51 Fixed Plate 52 Fixed Mold 61 Sliding Mold

Claims (2)

[Claims] 1. A mold comprising a slide mold which is slidable between a movable mold and a fixed mold in a direction intersecting a mold opening / closing direction, and fitting means is provided at a joint between the molds so that the joints are butted. A pair of split bodies that make up the hollow resin product,
Injection molding is performed at a position displaced from each other between the movable die and the slide die, and then the movable die and the slide die are opened with one divided body held by the movable die and the other divided body held by the slide die. Then, the slide die is slid to align the positions of the fitting means of the two divided bodies, and then the movable die and the slide die are closed to butt the joints of the two divided bodies and fit the fitting means. A method for molding a hollow resin product, which comprises: 2. The method for molding a hollow resin product according to claim 1, wherein the fitting means comprises a fitting hole and a fitting claw.