초록 ▼

The present invention relates to a method of manufacturing a body made of composite material such as a shell of a helmet. Said body constitutes a multilayer structure where each layer is formed by superposed strata comprising portions of fabrics preimpregnated with thermoplastic resin in which at le

The present invention relates to a method of manufacturing a body made of composite material such as a shell of a helmet. Said body constitutes a multilayer structure where each layer is formed by superposed strata comprising portions of fabrics preimpregnated with thermoplastic resin in which at least some of said layers are formed by woven or non-woven LFRTP-type preimpregnated fabrics. The outer layer is formed by strata of portions of “veil” type or “felt” type fabrics, with non-woven and non-oriented fibers of lengths comprised between 5 and 20 mm. In the method, the multilayer structure arranged in a mold is subjected to the action exerted by a bag that is inflated due to pressure occupying the cavity of the mold.

대표청구항 ▼

1. A method of manufacturing a body made of composite material with thermoplastic matrix provided with an inner cavity with an outward opening, said cavity comprising at least one concave curved wall and the outward opening having a smaller dimension than a maximum width of the inner cavity between

1. A method of manufacturing a body made of composite material with thermoplastic matrix provided with an inner cavity with an outward opening, said cavity comprising at least one concave curved wall and the outward opening having a smaller dimension than a maximum width of the inner cavity between two opposite walls, said method comprising: a first step of cutting fabrics preimpregnated with thermoplastic resin into portions according to a pattern of the body to be manufactured, wherein at least some of said preimpregnated fabrics are LFRTP-type fabrics, reinforced with long woven or non-woven fibers;a second step of placing the portions of preimpregnated fabrics in a mold provided with an inlet in a closed position, divided into at least two facing half-molds forming a closure of which configures a female type cavity reproducing a negative geometry of the body, arranging the portions of preimpregnated fabrics superposed on one another in multiple layers forming a multilayer structure, firstly positioning the portions that will constitute an outer layer of the body to be manufactured on the walls of the cavity of the mold and lastly the portions that will constitute an inner layer, the outer layer being formed by at least one stratum of portions of veil type or felt type fabrics, containing non-woven and non-oriented fibers of lengths comprised between 5 and 20 mm;a third step of placing a head provided with a bag configured as a male component with respect to the mold, closing the inlet of the mold, the bag being located inside the cavity of the mold;a fourth step of applying pressure inside the bag causing the bag to inflate and expand to such a volume causing contact and pressure of the surface of the bag against the portions of fabrics arranged on the walls of the cavity of the mold and a thrust thereof against the walls of the mold;a fifth step, simultaneous to the fourth step, of applying heat on the half-molds starting from a room temperature to an operating temperature value such the heat causes melting of the thermoplastic resin present in the fabrics and flow of the thermoplastic resin to reproduce a geometry of the mold;a sixth step of cooling the half-molds to a temperature to allow extracting the solidified molded body from the mold without becoming deformed;a seventh step of depressurizing the bag until the bag no longer contacts the walls of the cavity of the mold;an eighth step of withdrawing the head from the inlet of the mold whereby the bag is extracted from inside the cavity of the mold;a ninth step of opening the mold by separating the at least two half-molds from one another; anda tenth step of extracting the molded body; andwherein the fibers of the preimpregnated fabrics of the outer layer are hybrid fibers resulting from the combination of polypropylene fibers with glass fibers; andwherein the outer layer has a surface density comprised between 20 and 100 g/m2. 2. The method according to claim 1, characterized in that prior to placing the portions of fabrics of the second step a gel coat is applied on the walls of the cavity of the mold, the gel coat applied being compatible with the thermoplastic resin of the preimpregnated fabrics. 3. The method according to claim 1, characterized in that prior to or as the placement of the portions of fabrics of the second step takes place a tack enhancing product, compatible with the thermoplastic resin of the preimpregnated fabrics, is applied on the walls of the cavity of the mold and on the portions of fabrics placed to improve support of the portions of fabrics on the mold and of some portions on others. 4. The method according to claim 1, characterized in that in the third step, the bag is subjected to a negative pressure and in that the bag internally comprises a cage-like part to which the bag is adhered due to the negative pressure to which the bag is subjected in said step. 5. The method according to claim 1, characterized in that the value of the pressure that is applied inside the bag in the fourth step is comprised between 5 and 10 bar. 6. The method according to claim 1, characterized in that simultaneously to applying pressure in the fourth step heating means provided in the mold are activated for applying heat of the fifth step. 7. The method according to claim 1, characterized in that the operating temperature of the fifth step is comprised between 100 and 280° C. 8. The method according to claim 1, characterized in that a time during which the heat of the fifth step is applied is a time necessary for causing the melting of the thermoplastic material of the thermoplastic resin present in the fabrics and the flow of the thermoplastic material to reproduce the geometry of the mold. 9. The method according to claim 1, characterized in that the cooling of the sixth step is performed by forced convection by means of a cooling circuit for cooling the at least two female half-molds configuring the mold. 10. The method according to claim 1, comprising an eleventh step of finish operations for finishing the body. 11. The method according to claim 1, characterized in that the body is a shell of a helmet for use in vehicles, formed by a hollow body, forming the resistant part of the helmet in the event of a collision in accidents. 12. The method according to claim 1, characterized in that the body is a resistant body of sports footwear. 13. The method according to claim 1, characterized in that the length of the fibers in the LFRTP-type preimpregnated fabrics is at least 50 mm. 14. The method according to claim 13, characterized in that LFRTP-type preimpregnated fabrics are hybrid fabrics of synthetic or inorganic fibers combined with thermoplastic fiber or synthetic or inorganic fabrics incorporating the thermoplastic resin in suspension or diluted. 15. The method according to claim 1, characterized in that the thermoplastic resin of the preimpregnated fabrics is polypropylene resin and the fibers of the LFRTP-type fabrics are E-type glass fibers. 16. The method according to claim 1, characterized in that the outer layer has a fiber weight fraction comprised between 20% and 40%. 17. The method according to claim 1, characterized in that the inner layer is formed by at least one stratum of portions of LFRTP-type preimpregnated fabrics. 18. The method according to claim 17, characterized in that the LFRTP-type preimpregnated fabrics of the inner layer are twill type woven fabrics in which the fibers constituting the weft and the fibers constituting the warp of the fabric have the same number of fibers per unit area of fabric. 19. The method according to claim 18, characterized in that the at least one stratum of the inner layer has a surface density comprised between 300 and 2000 g/m2. 20. The method according to claim 15, characterized in that the at least one stratum of the inner layer has a fiber weight fraction comprised between 50 and 70%. 21. The method according to claim 17, characterized in that the inner layer comprises sections with a different number of strata. 22. The method according to claim 1, characterized in that in the second step superposed portions of fabrics preimpregnated with thermoplastic resin constituting a reinforcement layer are placed in specific areas and located between the outer layer and the inner layer, or between strata of the inner layer. 23. The method according to claim 22, characterized in that the portions of fabrics of the reinforcement layer are unidirectional or plain-woven portions of fabrics, where each strata of the reinforcement layer has a surface density comprised between 300 and 2000 g/m2 and a fiber weight fraction comprised between 50 and 70%. 24. The method according to claim 11, characterized in that the multilayer structure comprises sections with different surface density, with a minimum value of 1000 g/m2 and a maximum value of 3500 g/m2, and an average value comprised between 1800and 2400 g/m2. 25. An apparatus for carrying out the method defined in claim 1, comprising: the mold provided with an inlet in the closed position, divided into the at least two facing half-molds the closure of which configures the female type cavity reproducing the negative geometry of the body;the head provided with the bag configured as the male component with respect to the mold, the bag being located inside the cavity of the mold when the head is positioned closing the inlet of the mold;the fabrics preimpregnated with thermoplastic resin cut into portions according to the pattern of the body to be manufactured, wherein at least some of said preimpregnated fabrics are LFRTP-type fabrics, reinforced with long woven or non-woven fibers, wherein some of the portions constitute the outer layer of the body to be manufactured on the walls of the cavity of the mold and other of said portions constitute the inner layer, wherein the portions constituting the outer layer include the at least one stratum of portions of veil type or felt type fabrics, containing non-woven and non-oriented fibers of lengths comprised between 5 and 20 mm; and wherein the fibers of the preimpregnated fabrics of the outer layer are hybrid fibers resulting from the combination of polypropylene fibers with glass fibers, such that the outer layer will have the surface density comprised between 20 and 100 g/m2;heating means for heating the mold;cooling means for cooling the mold; andmeans for applying pressure inside the bag. 26. The apparatus according to claim 25, characterized in that the at least two half-molds are movable with respect to one another. 27. The apparatus according to claim 25, characterized in that the at least two half-molds are made of aluminum or steel. 28. The apparatus according to claim 25, characterized in that the bag is made of silicone. 29. The apparatus according to claim 25, characterized in that the head is attached in an articulated manner to the mold in an upper part on a side provided with the inlet. 30. A shell of a helmet for use in vehicles, formed by a hollow body, forming a resistant part of the helmet in an event of a collision in accidents, wherein the hollow body has a multilayer structure comprising an outer layer and an inner layer, wherein the outer layer is formed by at least one stratum of portions of veil type or felt type fabrics preimpregnated with thermoplastic resin, containing non-woven and non-oriented fibers of lengths comprised between 5 and 20 mm, and wherein the inner layer is formed by at least one stratum of portions of LFRTP-type fabrics preimpregnated with thermoplastic resin, reinforced with long woven or non-woven fibers; wherein the fibers of the preimpregnated fabrics of the outer layer are hybrid fibers resulting from a combination of polypropylene fibers with glass fibers; andwherein the outer layer has a surface density comprised between 20 and 100 g/m2. 31. The shell according to claim 30, characterized in that a length of the fibers in the LFRTP-type preimpregnated fabrics is at least 50 mm. 32. The shell according to claim 31, characterized in that the LFRTP preimpregnated fabrics are hybrid fabrics of synthetic or inorganic fiber combined with thermoplastic fiber or synthetic or inorganic fabrics incorporating the thermoplastic resin in suspension or diluted. 33. The shell according to claim 31, characterized in that the thermoplastic resin of the preimpregnated fabrics is polypropylene resin and the fibers of the LFRTP-type fabrics are E-type glass fibers. 34. The shell according to claim 30, characterized in that the outer layer has a fiber weight fraction comprised between 20% and 40%. 35. The shell according to claim 30, characterized in that the LFRTP-type preimpregnated fabrics of the inner layer are twill type woven fabrics in which fibers constituting the weft and fibers constituting the warp of the fabric have the same number of fibers per unit area of fabric. 36. The shell according to claim 35, characterized in that a stratum or strata constituting the inner layer each has a surface density comprised between 300 and 2000 g/m2. 37. The shell according to claim 30, characterized in that a stratum or strata constituting the inner layer each has a fiber weight fraction comprised between 50 and 70%. 38. The shell according to claim 30, characterized in that the inner layer comprises sections with a different number of strata. 39. The shell according to claim 30, characterized in that the multilayer structure of the hollow body comprises superposed portions of fabric preimpregnated with thermoplastic resin constituting a reinforcement layer in specific areas and located between the outer layer and the inner layer, or between the strata of the inner layer. 40. The shell according to claim 39, characterized in that the portions of fabrics of the reinforcement layer are unidirectional or plain-woven portions of fabrics, where each strata of the reinforcement layer has a surface density comprised between 300 and 2000 g/m2 and a fiber weight fraction comprised between 50 and 70%. 41. The shell according to claim 30, characterized in that the multilayer structure of the hollow body comprises sections with different surface densities, with a minimum value of 1000 g/m2 and a maximum value of 3500 g/m2, and an average value comprised between 1800 and 2400 g/m2. 42. The method according to claim 10, wherein the eleventh step of finish operations for finishing the body includes one or more of a cutting, drilling and surface finish operation. 43. The method according to claim 12, wherein the body is the resistant body of a ski boot.