Method for molding fiber-reinforced plastic, and molding device for same

Patent metadata

Field	Value
Publication number	US-10022898-B2
Application number	US-201314407203-A
Country	US
Kind code	B2
Filing date	Jun 11, 2013
Priority date	Jun 12, 2012
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A method for molding fiber-reinforced plastic. A core is formed in a desired shape by accommodating, in a flexible bag, a grain group containing plurality of grains. The core is placed inside a prepreg containing resin and fibers, and the prepreg, in which the core is housed is placed in a molding die and compression molded. When doing so, the grain group contains first and second grains (a,b) that satisfy the equation (1). (1) 1.1≤(Da/Db)≤2.0 In the equation Da is the grain diameter of the grains (a), and Db is the grain diameter of the grain (b). When using a molding die to mold a molded article having a cavity, the above mentioned molding method enables an increase in the internal pressure of the core in order to change the peripheral surface area of the core, without using a pressurized gas and/or pressurized liquid.

First claim

The invention claimed is:

1. A method for molding a molded article of fiber-reinforced plastic having a closed cross-section comprising:
forming a core having a desired shape by accommodating a grain group containing a plurality of high-rigidity grains in a flexible bag;
disposing a prepreg containing a resin and fiber so as to wrap around the core;
disposing the core and the prepreg wrapping around the core between an upper mold and a lower mold of a molding die; and
performing compression molding by closing the molding die;
wherein the method includes:
holding the upper mold and the lower mold by mold interval holding means so as not to cause an interval therebetween to be increased;
pressing a part of outer surface of the core, via the prepreg or not via the prepreg, to increase internal pressure of the core and deform the core by pressing means which comes into the cavity between the upper mold and the lower mold; and
eliminating voids between the core and the prepreg by the pressing and the deformation of the core.

2. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 1 , further comprising
completely restricting an upward movement of the upper mold by moving the mold interval holding means disposed in left and right side portions of the upper mold by a predetermined amount in a direction in which the mold interval holding means approach each other.

3. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 2 , further comprising
forming left and right side surfaces of the upper mold and abutting surfaces of the mold interval holding means as wedge-shaped sliding surfaces.

4. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 1 ,
wherein grain diameters of the grain group accommodated in the flexible bag are not uniform.

5. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 1 ,
wherein a part of the prepreg via which a part of outer surfaces of the core was pressed serves as a formation part of a discharge hole through which the grain group is discharged from the molded article.

6. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 1 ,
wherein the grain group accommodated in the flexible bag includes high-rigidity grains,
the grain group includes a first grain group (a) and a second grain group (b) having different grain diameters, and
the ratio Da/Db of the diameter Da of the first grain group (a) to the diameter Db of the second grain group (b) is equal to or higher than 1.1 and equal to or less than 2.0.

7. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 6 ,
wherein a ratio of the total amount of the second grain group (b) to the total amount of the grain group accommodated in the flexible bag is in a range of 20 to 60 mass %.

8. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 7 , further comprising:
holding the upper mold and the lower mold by mold interval holding means so as not to cause an interval therebetween to be increased;
pressing a part of outer surfaces of the core, via the prepreg or not via the prepreg to increase an internal pressure of the core and deform the core by pressing means which comes into the cavity between the upper mold and the lower mold; and
eliminating voids between the core and the prepreg by the pressing and the deformation of the core.

9. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 8 , further comprising
completely restricting an upward movement of the upper mold by moving the mold interval holding means disposed in left and right side portions of the upper mold by a predetermined amount in a direction in which the mold interval holding means approach each other.

10. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 9 , further comprising
forming left and right side surfaces of the upper mold and abutting surfaces of the mold interval holding means as wedge-shaped sliding surfaces.

11. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 8 , further comprising
pressing the portion of the outer surface of the core by inserting a rod into the cavity of the molding die.

12. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 11 , wherein the rod is a piston rod.

13. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 12 , further comprising
discharging the grain group to outside of the molded article through an insertion position of the rod in the prepreg after the compression molding.

14. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 6 , wherein the flexural modulus of the high-rigidity grain is equal to or higher than 50,000 MPa.

15. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 14 , wherein the high-rigidity grain is ceramic grain.

16. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 1 , wherein the grain group contains the high-rigidity grain and resin grain.

17. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 16 , wherein the flexural modulus of the resin grain is 10 to 3000 MPa.

18. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 17 , wherein the resin grain is polyolefin grain.

19. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 17 , further comprising:
holding the upper mold and the lower mold by mold interval holding means so as not to cause an interval therebetween to be increased;
pressing a part of outer surfaces of the core, via the prepreg or not via the prepreg, to increase an internal pressure of the core and deform the core by pressing means which comes into the cavity between the upper mold and the lower mold; and
eliminating voids between the core and the prepreg by the pressing and the deformation of the core.

20. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 19 , further comprising
completely restricting an upward movement of the upper mold by moving the mold interval holding means disposed in left and right side portions of the upper mold by a predetermined amount in a direction in which the mold interval holding means approach each other.

21. The method for molding a molded article of fiber-reinforced plastic having a closed cross-section according to claim 20 , further comprising
forming left and right side surfaces of the upper mold and abutting surfaces of the mold interval holding means as wedge-shaped sliding surfaces.

22. The method for molding a molded article of fiber-reinforced plastic having a closed cr

Assignees

• Mitsubishi Rayon Co
• Mitsubishi Chem Corp

Inventors

• Takano Tsuneo
• Kazehaya Yuuji
• Nishimura Mitsushi

Classifications

• B29C70/44 Primary

  using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding · CPC title

• B60B5/02

  made of synthetic material · CPC title

• B29L2022/00

  Hollow articles (tubular articles B29L2023/00; pneumatic tyres B29L2030/00) · CPC title

• B29L2031/00

  Other particular articles · CPC title

• B29C70/50

  for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC] · CPC title