SANDWICH PANEL, METHOD OF FORMING CORE MATERIAL FOR SANDWICH PANEL, AND METHOD OF FORMING SANDWICH PANEL

• US 20110250384A1
• Filed: 10/31/2009
• Published: 10/13/2011
• Est. Priority Date: 10/31/2008
• Status: Active Grant

• Current Assignee: Kyoraku Co.,Ltd.
• Original Assignee: Kyoraku Co.,Ltd.
• Inventors: Nagai, Sumio, Sumi, Takehiko, Tanji, Tadatoshi
• Granted Patent: US 9,283,895 B2
• Time in Patent Office: Days
• US Class Current: 428/118
• CPC Class Codes: B29C 44/569 Shaping and joining components with different densities or hardness
• CPC Class Codes: B29C 70/086 and with one or more layers of pure plastics material, e.g. foam layers applying a non-preformed coating, e.g. a gel-coat, B29C37/0025; with foam blocks B29C70/86
• CPC Class Codes: B32B 2250/40 Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
• CPC Class Codes: B32B 2305/022 Foam
• CPC Class Codes: B32B 2307/542 Shear strength
• CPC Class Codes: B32B 2307/546 Flexural strength; Flexion stiffness
• CPC Class Codes: B32B 2605/003 Interior finishings
• CPC Class Codes: B32B 2605/08 Cars
• CPC Class Codes: B32B 27/065 of foam
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 3/12 characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• CPC Class Codes: B32B 3/266 characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
• CPC Class Codes: B32B 3/28 characterised by a layer comprising a deformed thin sheet , i.e. the layer having its entire thickness deformed out of the plane, e.g. corrugated, crumpled B32B29/08 takes precedence
• CPC Class Codes: B32B 3/30 characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs apertured layer B32B3/266; layer with cavities or internal voids B32B3/26
• CPC Class Codes: B32B 37/04 characterised by the partial melting of at least one layer
• CPC Class Codes: B32B 38/06 Embossing
• CPC Class Codes: B32B 5/18 characterised by features of a layer of foamed material
• CPC Class Codes: B60R 13/01 Liners for load platforms or load compartments
• CPC Class Codes: B60R 13/0268 Rear parcel liners used as luggage covering means B60R5/044
• CPC Class Codes: B60R 13/0815 Acoustic or thermal insulation of passenger compartments wall or roof liners integrating the insulating function B60R13/02; insulating floor mats or carpets B60N3/04
• CPC Class Codes: B60R 5/044 : luggage covering means, e.g. parcel shelves
• CPC Class Codes: E04C 2/296 : composed of insulating material and non-metallic or unspecified sheet-material E04C2/288 takes precedence
• CPC Class Codes: Y10T 428/24165 : Hexagonally shaped cavities
• CPC Class Codes: Y10T 428/24306 : Diamond or hexagonal
• CPC Class Codes: Y10T 428/24331 : including nonapertured component

Abstract

An object of the present invention is to provide a sandwich panel which is capable of securing its flexural or its shear rigidity as a whole and securing a compression rigidity of a core material itself, while at the same time of readily reducing the weight of the sandwich panel.

According to an aspect of the invention, there is provided a sandwich panel comprising two resin skin sheets, and a resin core material sandwiched between the two resin skin sheets and planarly adhered to each of the two resin skin sheets, said core material consists of an foamed resin with a predetermined expanding ratio and has a plurality of recesses each of which forms an opening formed on at least one surface thereof and extends inwardly to define an inner space closed by the corresponding skin sheet, the number of said recesses and the total area of the openings are determined in such a manner that the planer adhesion of at least one surface of the resin core material to the corresponding skin sheet is maintained, while at the same time solid portions of the foamed resin of the resin core material excluding said inner space formed by the plurality of recesses function to support a compressive load in the thickness direction of the resin core material, under the predetermined void volume allocated to said plurality of recesses in relation with said predetermined expanding ratio.

Claims

1. A sandwich panel comprising two resin skin sheets, and a resin core material sandwiched between the two resin skin sheets and planarly adhered to each of the two resin skin sheets,

said core material consists of an foamed resin with a predetermined expanding ratio and has a plurality of recesses each of which forms an opening formed on at least one surface thereof and extends inwardly to define an inner space closed by the corresponding skin sheet,

the number of said recesses and the total area of the openings are determined in such a manner that the planer adhesion of at least one surface of the resin core material to the corresponding skin sheet is maintained, while at the same time solid portions of the foamed resin of the resin core material excluding said inner space formed by the plurality of recesses function to support a compressive load in the thickness direction of the resin core material, under the predetermined void volume allocated to said plurality of recesses in relation with said predetermined expanding ratio.

16. The sandwich panel according to claim 1, wherein the relationship between the mean density (x) of said thermoplastic resin core material and the effective density (y) thereof meets a following equation and the expanding ratio of said thermoplastic resin core material is less than, or equal to 10-fold.

0.05x≦

y≦

0.85x

17. The sandwich panel according to claim 1, wherein said predetermined expanding ratio of the foams formed inside said thermoplastic resin core material is limited so as to secure the ratio of close-celled foams in accordance with an heat insulating characteristics required for said sandwich panel, while a distribution of said plurality of recesses on said at least one surface of said thermoplastic resin core material is determined in accordance with the rigidity required for said sandwich panel.

2. A sandwich panel comprising two resin skin sheets, and a resin core material sandwiched between the two resin skin sheets and planarly adhered to each of the two resin skin sheets,

said core material consists of an foamed resin with a predetermined expanding ratio and has a plurality of recesses on at least one surface thereof each of which extends inwardly to define an inner space closed by the corresponding skin sheet,

each of said plurality of recesses is defined by an annular rib forming an opening on at least one surface, the number and the annular shapes of said annular ribs are determined in such a manner that the planer adhesion of at least one surface of the resin core material to the corresponding skin sheet is maintained, while at the same time said annular ribs function to support a compressive load in the thickness direction of the resin core material, under the predetermined void volume allocated to said plurality of recesses in relation with said predetermined expanding ratio.

3. The sandwich panel according to claim 2, wherein said resin core material comprises a pair of thermoplastic resin plates, each of which includes a plurality of recesses each of which inwardly tapers in a converging manner and is constituted by said annular rib protruding at its inner surface side, each of said plurality of recesses includes an abutting portion at the most converged portion, whereby said core material is formed by welding the abutting portion of each of the plurality of recesses of one of the pair of the resin plates and that of the corresponding recess of the other of the pair of the resin plates, the surface of each of said pair of the thermoplastic resin plates is joined to the corresponding skin sheet.

4. The sandwich panel according to claim 3, wherein each of said plurality of recesses includes a bottom, said abutting portion includes a plane abutting portion, and said core material is formed by welding the plane abutting portion of each of said plurality of recesses of one of said pair of resin plates to that of the corresponding recesses of the other of said pair of resin plates in a back to back configuration.

5. The sandwich panel according to claim 6, wherein said abutting portion is formed by a peripheral portion of an opening formed on each of the surfaces opposed to each other of the pair of resin plates, said core material including perforated holes is formed by welding the abutting portion of each of said plurality of recesses of one of said pair of resin plates to that of the corresponding recess of the other of said pair of resin plates in a back to back configuration.

6. The sandwich panel according to claim 4, wherein each of said plurality of recesses is shaped to be a truncated pyramid which includes a regular hexagon opening on an outer surface of said thermoplastic core material.

7. The sandwich panel according to claim 6, wherein said plurality of recesses are disposed to be in a honeycomb pattern on said outer surface of the thermoplastic core material.

18. The sandwich panel according to claim 2, wherein said annular shape of said annular rib includes a size and a shape of said opening formed by said annular rib, or a thickness thereof.

19. The sandwich panel according to claim 18, wherein the number of said annular ribs is determined based on a total peripheral length and a total area of said opening formed by each of said annular ribs.

8. A method of forming a thermoplastic resin core material for a sandwich panel sandwiched between two resin skin material sheets comprising steps of:

positioning foamed thermoplastic resin material in a molten state between a pair of split molds so as to protrude around an annular pinch-off portion formed a peripheral edge portion of each of said pair of split molds,

clamping said pair of split molds to form a sealed space inside said pair of split molds, and

forming the thermoplastic resin material by means of protrusions provided on an inside of said pinch-off portion of a cavity of at least one of said pair of split molds by pressurizing and/or sucking the foamed thermoplastic resin material in a molten state inside said sealed space so as not to rupture foams formed in the foamed thermoplastic resin material,

whereby recesses are formed on at least one surface of the thermoplastic resin material inside the sealed space which surface is opposed to said cavity.

9. The method of forming the thermoplastic resin core material according to claim 8, wherein said foamed molten thermoplastic resin material is a cylindrically extruded parison.

10. The method of forming the thermoplastic resin core material according to claim 8, wherein said foamed molten thermoplastic resin material is a parison in a sheet form extruded from a T-die.

11. The method of forming the thermoplastic resin core material according to claim 8, wherein said foamed molten thermoplastic resin material is made to be in a molten state by reheating the foamed thermoplastic resin material which has been formed in advance by extrusion molding.

15. A method of forming a sandwich panel including a thermoplastic resin core material sandwiched between two resin skin material sheets comprising steps of:

positioning the core material formed by the method of forming the thermoplastic resin core material according to claim 8 between the pair of split molds,

positioning two molten sheet parisons made of thermoplastic resin between the pair of split molds so as to sandwich the core material and protrude each of two molten sheet parisons from a corresponding annular pinch-off portion formed on a peripheral edge portion of a cavity of each of the pair of split molds,

clamping the pair of split molds to form a sealed space inside the pair of split molds, and

forming the sheet parisons in the sealed space by means of convex and concave portions provided on the cavity of each of the pair of split molds inside the corresponding annular pinch-off portion by pressurizing air inside the sealed space, or sucking the sealed space through the pair of clamped split molds, while at the same time welding the sheet parison and the core material,

whereby a parting line is formed on peripheral edges of the sheet parisons welded to each other with the core material being arranged inside.

20. The method of forming the thermoplastic resin core material according to claim 9, wherein the thermoplastic resin material is formed into the foamed parison by adding foaming agent in an extruder in an amount required for the predetermined expanding ratio and kneading it while at the same time heating it so as to form foamed resin in a molten state, and extruding said foamed resin at a predetermined extruding velocity.

12. A method of forming a thermoplastic resin core material for a sandwich panel sandwiched between two resin skin material sheets comprising steps of:

positioning two foamed thermoplastic resin sheet parisons in a molten state between a pair of split molds so as to protrude around an annular pinch-off portion formed on a peripheral edge portion of each of said pair of split molds,

forming a sealed space between a cavity of each of said pair of split molds and the corresponding sheet parison by abutting the corresponding sheet parison against said annular pinch-off portion provided on said cavity so as to protrude from said cavity toward the other split mold,

forming each of the sheet parisons by pressing it against a plurality of protrusions provided on an inside of the corresponding pinch-off portion by sucking it through the sealed space, and

welding said two sheet parisons to each other by clamping said pair of split molds,

whereby a sealed space is provided inside the two sheet parisons, while at the same time a plurality of recesses or penetrated holes are provided on a surface of each of the two sheet parisons by forming a parting line on peripheral edges of the two welded sheet parisons.

13. A method of forming a thermoplastic resin core material for a sandwich panel sandwiched between two resin skin material sheets comprising steps of:

positioning foamed thermoplastic resin material in a molten state between a pair of split molds so as to protrude around an annular pinch-off portion formed on a peripheral edge portion of each of said pair of split molds,

forming a sealed space inside said pair of split molds by clamping said pair of split molds, and

forming the thermoplastic resin material by protrusions provided inside the annular pinch-off portion of a cavity of at least one of said pair of split molds by sucking the foamed thermoplastic resin material parison in a molten state inside the sealed space through said pair of clamped split molds,

whereby recesses are formed on at least one surface of the thermoplastic resin material opposed to said cavity inside the sealed space.

14. A method of forming a thermoplastic resin core material for a sandwich panel sandwiched between two resin skin sheets comprising steps of:

positioning foamed thermoplastic resin material in a molten state between a pair of split molds so as to protrude around an annular pinch-off portion formed on a peripheral edge portion of each of said pair of split molds, and

clamping said pair of split molds to form the thermoplastic resin material by protrusions provided on a cavity of at least one of the pair of split molds inside said annular pinch-off portion thereof,

whereby recesses are formed on at lease one surface of the thermoplastic resin material inside a sealed space opposed to said cavity.

21. A sandwich panel comprising an foamed resin core material on each surface of which a resin skin sheet is adhered, characterized in that a plurality of recesses are formed on said foamed resin core material.

22. A method of producing a sandwich panel comprises steps of:

forming a plurality of recesses on an foamed core material by means of a plurality of protrusions protruding from at least one surface of a pair of split molds spaced apart from each other by a predetermined distance, and

sandwiching said foamed resin core material between two resin skin sheets to adhere its area other than that corresponding to said plurality of recesses to the corresponding resin skin sheet.