JP2000289093A - Hollow plastic molded article and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the length projected from the outer surface of a hollow main body part of a projected joining part without lowering the joining force of a product. SOLUTION: A hollow plastic molded article 10 consists of a hollow main body part 11 having a required hollow shape molded from two opposed plastic sheets 10a, 10a by a sheet blow molding method and a projected joining parts 12 of two plastic sheets formed to the outer surface of the hollow main body part in a projected state and the projected joining parts are formed so that the leading ends 13 thereof are set to a state having a shape inclined or curved toward the surface of the hollow main body part on one side of the joining parts or a wavy shape bent toward the surface of the hollow main body part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a hollow synthetic resin molded product and a method for producing the same.

[0002]

2. Description of the Related Art As a method of manufacturing a hollow synthetic resin molded article,
A sheet blow molding method is known, and is also used for manufacturing a hollow synthetic resin molded product 50 used for an automobile duct as shown in FIG. 9 and FIG. 10 which is a cross sectional view thereof. In this sheet blow molding method, as shown in FIGS. 11 and 12, two opposed thermoplastic synthetic resin sheets 50a, 50a, which have been softened by heating, are formed into a molding cavity surface 6.
1 and 71, the synthetic resin sheet 50a is sandwiched between divided molds 60 and 70 having parting surfaces 62 and 72.
This is a method of manufacturing the hollow synthetic resin molded product 50 by blowing a gas (not shown) between 50a.

In this example, the molding cavity surface 6
In order to make the synthetic resin sheets 50a, 50a more closely adhere to the first and the first 71, a vacuum device (not shown) is used to separate the inside of the split mold 6a.
3, 73, the synthetic resin sheets 50a, 50a are sucked in vacuum. Reference numerals 64 and 74 denote vacuum suction holes communicating with the split mold interiors 63 and 73, reference numerals 65 and 75 denote pipes connected to a vacuum device, and reference numeral 80 denotes a sheet clamp for holding the synthetic resin sheets 50a and 50a.

In the sheet blow molding method, a protruding joint portion 52 is formed on the outer surface of a hollow main body 51 shaped and fixed in the shape of the molding cavity surfaces 61 and 71 by sandwiching the parting surfaces 62 and 72. Is done. Note that the synthetic resin sheet outside the protruding joint portion 52 is cut by a trimming process. Since the parting surfaces 62 and 72 have a substantially planar shape as shown in an enlarged view in FIG. 13, the projecting joint portion 52 has a substantially straight cross section as shown in FIGS.

However, it is preferable that the protruding joint portion 52 does not protrude as much as possible from the hollow main body portion 51 in view of a space in which the molded hollow synthetic resin molded product 50 is arranged. However, if the protruding length of the protruding joint portion 52 becomes too short, there is a problem that the joining force is reduced and the joint is opened. For this reason, conventionally, the protruding length of the protruding joint portion 52 cannot be shortened by a certain amount or more.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to shorten the length of a projecting joint from the outer surface of a hollow main body without lowering the joining force of a product. An object of the present invention is to provide a hollow synthetic resin molded product and a method for producing the same.

[0007]

That is, a first aspect of the present invention is a hollow main body formed and fixed in a required hollow shape from two opposing synthetic resin sheets by a sheet blow molding method. A hollow synthetic resin molded product comprising a projecting joint portion of the two synthetic resin sheets protrudingly formed on the outer surface of the main body portion, wherein the protruding joining portion has its tip directed toward the surface of the hollow main body portion on one side of the joining portion. The present invention relates to a hollow synthetic resin molded product characterized by being formed in an inclined or curved shape.

According to a second aspect of the present invention, there is provided a hollow main body formed and fixed in a required hollow shape from two opposing synthetic resin sheets by a sheet blow molding method, and a projection formed on an outer surface of the hollow main body. A hollow synthetic resin molded product comprising a projecting joint of the two synthetic resin sheets formed, wherein the projecting joint is bent in a wave shape from a base to a tip thereof, and the bent shape is an outer surface of the hollow main body. The hollow synthetic resin molded article is characterized by being substantially continuous continuously along the line.

According to a third aspect of the present invention, a synthetic resin sheet comprising a foam layer and a solid layer is used, and two synthetic resin sheets are arranged so that the solid layers face each other. The hollow synthetic resin molded product according to claim 1 or 2, wherein

According to a fourth aspect of the present invention, two opposed synthetic resin sheets that have been softened by heating are sandwiched by a split mold having a parting surface around a molding cavity surface, and gas is blown between the synthetic resin sheets. By sheet blow molding method,
A method for manufacturing a hollow synthetic resin molded product comprising a hollow main body shaped and fixed to the molded cavity surface shape and a projecting joint formed on the outer surface of the hollow main body sandwiched by the parting surface, A hollow synthetic resin molded product characterized in that the parting surface is formed into a wavy curved surface along the inner and outer directions of the mold, and the projecting joint formed by the parting surface is formed into a wavy shape from the base to the tip thereof. Pertaining to the method of manufacturing.

According to a fifth aspect of the present invention, sheet blow molding is performed by using a synthetic resin sheet having two layers, a foam layer and a solid layer, and arranging the two synthetic resin sheets so that the solid layers face each other. A method for producing a hollow synthetic resin molded product according to claim 4.

According to a sixth aspect of the present invention, after the sheet blow molding, the molded product is released from the mold, and the protruding joint is cut along the outer periphery of the hollow main body at the bent top or bottom away from the base. Item 4 relates to a method for producing a hollow synthetic resin molded product according to item 4 or 5.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a hollow synthetic resin molded product according to a first embodiment of the present invention, FIG. 2 is a sectional view showing a hollow synthetic resin molded product according to a second embodiment, and FIG. FIG. 4 is a sectional view showing a hollow synthetic resin molded product.
FIG. 5 is a cross-sectional view showing a split mold for sheet blow molding of a hollow synthetic resin molded product according to an embodiment, FIG. 5 is an enlarged cross-sectional view of a main part near a parting surface of the split mold according to the first embodiment, and FIG. FIG. 7 is an enlarged cross-sectional view of a main part of a split mold according to an example, FIG. 7 is an enlarged cross-sectional view of a main part of a split mold according to a third embodiment, and FIG. 8 is a cross-sectional view showing a sheet blow molding process according to the first embodiment.

FIG. 1 shows a hollow synthetic resin molded product 10 according to a first embodiment of the present invention. The hollow synthetic resin molded article 10 of this embodiment has two synthetic resin sheets 10.
a, a duct formed from sheet 10a by a sheet blow molding method, comprising a hollow main body 11 and a projecting joint 12; In this embodiment, a single-layer non-foamed polyethylene sheet is used as the synthetic resin sheet.

The hollow main body 11 is formed and fixed in shape by opposing two synthetic resin sheets 10a, 10a along forming cavity surfaces 21, 31 of sheet blow molding split dies 20, 30, which will be described later. And has a hollow shape with a substantially square cross section. Further, the projecting joint 1
2 is the molding cavity surfaces 21 and 31 of the split molds 20 and 30
Are formed by the two synthetic resin sheets 10a, 10a sandwiched between parting surfaces 22, 32 provided around the periphery of the hollow main body 11, and have a structure protruding from the outer surface of the hollow main body 11.

The protruding joint 12 is moved from the base 14 or 14 of the protruding joint 12 so that its tip 13 is closer to the surface of the hollow body 11 on one side (the upper side in this embodiment) of the protruding joint 12. It has a shape that is linearly inclined from an appropriate position between the tip and the tip 13. In addition, the projecting joint portion 12 may have not only a shape inclined to approach the surface side of the hollow main body 11 as described above, but also a shape curved in an arc shape so as to approach the surface side of the hollow main body 11. When the projecting joint 12 has such a shape, the hollow body 1
The shortest protruding length L from one surface is shorter than that of a conventional protruding joint having a substantially linear cross section. Further, the length between the distal end 13 and the base 14 of the projecting joint 12 measured along the projecting joint 12 can be equal to or longer than that of a conventional projecting joint having a substantially linear cross section. Therefore, the bonding area between the synthetic resin sheets does not become narrower or becomes wider, so that the joining force does not decrease.

The hollow synthetic resin molded product 10 shown in FIG.
As shown in A, the projecting joint 12A is bent in a wavy shape from its base 14A to its tip 13A, and the bent shape is substantially uniformly continuous along the outer surface of the hollow main body 11A, that is, along the longitudinal direction of the duct. May be. In this case, the joining strength of the protruding joining portion 12A is further increased. further,
As in the hollow synthetic resin molded product 10B shown in FIG. 3, the projecting joint portion 12B is bent into a larger wave shape from the base portion 14B to the distal end 13B, and the bent shape is substantially uniform along the outer surface of the hollow main body portion 11B. May be continuous.

Next, a method of manufacturing the hollow synthetic resin molded product 10 will be described. FIG. 4 shows split molds 20 and 30 for sheet blow molding for manufacturing the hollow synthetic resin molded product 10. The split dies 20 and 30 have a molding cavity surface 2 for molding the hollow body 11.
1, 31 are provided, and the molding cavity surface 21,
Parting surfaces 22 and 32 for forming the projecting joints 12 are provided around the periphery of the part 31.

In this embodiment, in order to make the synthetic resin sheets 10a, 10a more closely adhere to the molding cavity surfaces 21, 31, the synthetic resin sheets 10a, 10a, 10a, 10a are separated from the split mold insides 23, 33 by a vacuum device (not shown). It has a structure for vacuum suction of 10a. Reference numerals 24 and 34 are vacuum suction holes communicating with the split mold insides 23 and 33, and reference numerals 25 and 35 are pipes connected to a vacuum device.

The parting surfaces 22 and 32 extend along the inner and outer directions of the mold (in this embodiment, the cavity surfaces 21 and 32).
It is a wave-shaped bent surface (from 31 toward the outer surfaces 26, 36). As shown in an enlarged view in FIG. 5, in this embodiment, of the split dies 20 and 30, the parting surface 22 of the upper split die 20 is a single concave bent surface, and Is a single convex curved surface corresponding to the concave shape of the parting surface 22 of the upper split mold 20.

The shape of the parting surface is not limited to that described above. For example, as shown in FIG.
A parting surface 22A is a plurality of concave curved surfaces, and parting surface 32A of lower split mold 30A is formed.
However, a plurality of convex bending surfaces corresponding to the concave shape of the parting surface 22A of the upper split mold 20A may be used. Also, as shown in FIG. 7, the parting surface 22B of the upper split mold 20B is a bent surface where the convex shape and the concave shape are continuous, and the parting surface 32 of the lower split mold 30B is formed.
B may be a continuous curved surface having a concave shape and a convex shape corresponding to the shape of the parting surface 22B of the upper split mold 20B.

When manufacturing the hollow synthetic resin molded article 10 using the split dies 20, 30, first, as shown in FIG.
The two synthetic resin sheets 10a, 10a, which have been softened by heating according to a known sheet blow molding method, are held by a sheet clamp 40 or the like so that the two synthetic resin sheets 10a, 10a face each other, and the split mold 20, Place between 30.
Then, the split dies 20 and 30 are clamped, and a gas such as air is blown between the synthetic resin sheets 10a and 10a in the mold from a blowing nozzle (not shown), thereby forming the synthetic resin sheet as shown in FIG. 10a, 10a are formed into the shape of the molding cavity surfaces 21, 31. In this embodiment,
As described above, the vacuum device is provided. By blowing gas from the blowing nozzle and operating the vacuum device, the synthetic resin sheets 10a, 10a are more closely adhered to the molding cavity surfaces 21, 31 of the split dies 20, 30. Can be done.

When the split dies 20, 30 are clamped, the parting surfaces 22,
At 32, the two thermoplastic synthetic resin sheets 10a, 10a are sandwiched and fused to form the projecting joint 12 bent in a wave shape. In this embodiment, the parting surfaces 22, 32
However, since it is a curved surface having a single wave (concavo-convex) shape as shown in an enlarged view in FIG. 5, the projecting joint portion 12 has a single wave shape as shown in FIG. 1 (including a broken line portion). .

Incidentally, instead of the split molds 20 and 30,
If the split dies 20A and 30A in which the parting surfaces 22A and 32A shown in FIG. 6 are a plurality of corrugated bent surfaces are used, the projected joint portion 12A to be formed is also shown in FIG. 2 (including the broken line portion). It becomes a plurality of wave shapes like this. Also, the parting surface 22B of the upper split type 20B as shown in FIG.
Is a curved surface in which the convex shape and the concave shape are continuous, and the parting surface 32B of the lower split mold 30B is a continuous shape of the concave shape and the convex shape corresponding to the shape of the parting surface 22B of the upper split mold 20B. Split type 20B having a curved surface,
If 30B is used, the parting surfaces 22B and 32B
Since the bent surface has a large wavy shape, the formed projecting joint portion 12B also has a large wavy shape as shown in FIG. 3 (including the broken line portion).

Thereafter, the molded product is cooled and removed from the mold, and the protruding joint is cut to an appropriate length. In this embodiment, the bent tops 15 and 15B separated from the bases 14 and 14B of the above-mentioned corrugated projecting joints 12 and 12B or the bent bottom 15A separated from the base 14A of the projecting joint 12A.
Since the cutting is performed along the outer periphery of the hollow main bodies 11, 11A and 11B, the cutting position can be easily specified, and the problem that the cutting position differs depending on the product does not occur.

As the synthetic resin sheet 10a, not only a single layer made of non-foamed solid resin but also a single layer of foamed resin may be used if possible. Further, a multi-layered structure, for example, a two-layered structure of a foamed layer made of foamed polyethylene or the like and a solid layer made of non-foamed polyethylene or the like may be used. In this case, in the hollow synthetic resin molded articles 10, 10A, 10B for the duct and the method of manufacturing the same, the inside u opposed to the solid layer and the outside s are foamed layers. This makes it possible to easily manufacture a sheet blow-molded article having excellent heat insulating properties, and is particularly suitable for a duct in which dew condensation easily occurs. Further, since the foamed layer also has excellent sound absorbing properties, there is an advantage that the sound absorbing properties of the duct are improved.

The material, thickness, size, etc. of the synthetic resin sheet and the shape, size, etc. of the hollow synthetic resin molded product are not limited to those shown and described, but may be any suitable ones.
Further, the present invention is not limited to the illustrated duct, but can be applied to various hollow synthetic resin molded products.

[0028]

As shown and described above, according to the hollow synthetic resin molded product and the method of manufacturing the same according to the present invention, the projecting joint portion is formed by being bent into an inclined or curved shape or a wavy shape. Since the length of the projecting joint projecting from the outer surface of the hollow body can be shortened while increasing the joining area of the two synthetic resin sheets, the space for arranging the hollow synthetic resin molded product without reducing the joining force of the product. Etc. can be reduced. In addition, since the protruding joint can be cut along the outer periphery of the hollow body at the bent top or bent bottom away from the base, the cut point can be easily specified, and the cut point differs depending on the product and the product part. There is no. Further, since the protruding joint has the shape as described above, even if an interfering object hits the protruding joint, it can bend with elasticity and absorb the interference.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a hollow synthetic resin molded product according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a hollow synthetic resin molded product according to a second embodiment.

FIG. 3 is a sectional view showing a hollow synthetic resin molded product according to a third embodiment.

FIG. 4 is a sectional view showing a split mold for sheet blow molding of a hollow synthetic resin molded product according to the first embodiment.

FIG. 5 is an enlarged sectional view of a main part near a parting surface of a split mold according to the first embodiment.

FIG. 6 is an enlarged sectional view of a main part of a split mold according to a second embodiment.

FIG. 7 is an enlarged sectional view of a main part of a split mold according to a third embodiment.

FIG. 8 is a sectional view showing a sheet blow molding process according to the first embodiment.

FIG. 9 is a perspective view of a conventional hollow synthetic resin molded product for a duct.

FIG. 10 is a cross-sectional view of the hollow synthetic resin molded product of FIG. 9;

FIG. 11 is a sectional view showing a conventional split mold.

FIG. 12 is a cross-sectional view showing a conventional molding process.

FIG. 13 is an enlarged sectional view of a main part near a parting surface of a conventional split type.

[Explanation of symbols]

 10, 10A, 10B Hollow synthetic resin molded article 10a Synthetic resin sheet 11, 11A, 11B Hollow main body 12, 12A, 12B Projecting joint 13, 13A, 13B Projecting joint tip 14, 14A, 14B Projecting joint base 15, 15B Bend top 15A Bend bottom 20,30 Split mold 21,31 Mold cavity surface 22,32 Parting surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 9:00 22:00 31:00 F term (Reference) 4F202 AA04 AC03 AG03 AG07 AG20 AG23 AH17 CA15 CA17 CB01 CK83 CP06 4F208 AA04 AC03 AG03 AG07 AG20 AG23 AH17 LB01 LG05 LG06 LN15 MA01 MC01 MG04 MJ21 MW23

Claims (6)

[Claims] 1. A hollow main body formed and fixed to a required hollow shape from two opposing synthetic resin sheets by a sheet blow molding method, and the two synthetic resins protrudingly formed on the outer surface of the hollow main body. A hollow synthetic resin molded product comprising a projecting joint portion of a resin sheet, wherein the projecting joint portion is formed in such a shape that its tip is inclined or curved toward the surface of the hollow main body portion on one side of the joining portion. Hollow synthetic resin molded products. 2. A hollow main body formed and fixed to a required hollow shape by a sheet blow molding method from two opposing synthetic resin sheets, and the two synthetic bodies protrudingly formed on the outer surface of the hollow main body. A hollow synthetic resin molded product comprising a projecting joint of a resin sheet, wherein the projecting joint bends in a wave shape from a base to a tip thereof, and the bent shape is substantially uniformly along the outer surface of the hollow main body. A hollow synthetic resin molded product characterized by being continuous. 3. A synthetic resin sheet comprising two layers, a foamed layer and a solid layer, wherein two synthetic resin sheets are arranged so that the solid layers face each other, and sheet blow molding is performed. 3. The method according to claim 1, wherein
The hollow synthetic resin molded article according to the above. 4. A sheet blow molding method in which two opposed synthetic resin sheets heated and softened are sandwiched by a split mold having a parting surface around a molding cavity surface and a gas is blown between the synthetic resin sheets. A method of manufacturing a hollow synthetic resin molded product comprising a hollow main body shaped and fixed to the shape of the molded cavity surface and a projecting joint formed on the outer surface of the hollow main body sandwiched by the parting surface, A hollow synthetic resin molding, wherein the parting surface is formed into a wavy curved surface along the inner and outer directions of the mold, and a projecting joint formed by the parting surface is formed into a wavy shape from its base to the tip. Product manufacturing method. 5. A synthetic resin sheet comprising two layers, a foam layer and a solid layer, wherein two synthetic resin sheets are arranged so that the solid layers face each other and subjected to sheet blow molding. The method for producing a hollow synthetic resin molded product according to claim 4. 6. The molded product is removed from the molded product after the sheet blow molding, and the protruding joint is cut along the outer periphery of the hollow main body at the bent top or bottom away from the base. Of manufacturing a hollow synthetic resin molded article.