Polymeric stiffened sheet-like component and process for producing the same

Patent metadata

Field	Value
Publication number	US-11608154-B2
Application number	US-202016839355-A
Country	US
Kind code	B2
Filing date	Apr 3, 2020
Priority date	Apr 3, 2019
Publication date	Mar 21, 2023
Grant date	Mar 21, 2023

Abstract

A process for producing a polymeric stiffened sheet-like component, for example a panel, for aircraft construction. Production includes integration of hollow stiffening profiles, for example closed omega stringers, onto a sheet-like component, for example an external skin, where the stringers and external skin are produced from thermoplastic composite material. The stringers are integrated onto the external skin by establishing contact between the stringers and the external skin and melting thermoplastic composite material with exposure to heat and pressure at the areas of contact between external skin and stringers. Melting of the other sections of the stringers is avoided with a pressurized cooling fluid with a temperature significantly below the melting point of thermoplastic composite material, the fluid flowing through the airtight enclosed space in the stringers. Use of closed airtight thermoplastic omega stringers allows integration of the stringers onto the external skin in absence of any flexible tube within the stringers.

First claim

The invention claimed is:

1. A process for producing a stiffened sheet-like component based on polymer for use in aircraft construction, the stiffened sheet-like component comprising a sheet-like component based on polymer and, secured thereon, stiffening profiles based on polymer, the process comprising at least steps of:
a) providing hollow stiffening profiles which comprise thermoplastic composite material, of a sheet-like component which comprises thermoplastic composite material, of a mold and of a gastight container;
b) arranging the hollow stiffening profiles and of the sheet-like component on a surface of the mold with establishment of contact, over a substantial area, between a hollow stiffening profile wall of the hollow stiffening profiles and the sheet-like component;
c) heating the arrangement obtained in step b), in the gastight container by pressurized heating fluid, a temperature of which is above a melting point of thermoplastic composite material, and/or in the pressurized gastight container by heating equipment which is configured within the mold and which heats at least the mold surface to a temperature above the melting point of thermoplastic composite material, with cooling of the hollow stiffening profiles by a pressurized cooling fluid which flows through an enclosed space of the hollow stiffening profiles and a temperature of which is below the melting point of thermoplastic composite material;
d) cooling of the arrangement to ambient temperature with coherent bonding of the hollow stiffening profile walls to the sheet-like component.

2. The process according to claim 1 , wherein the hollow stiffening profiles are closed omega stringers which comprise an omega stringer with stringer top section, stringer webs and stringer feet, and comprise a covering layer bonded, coherently bonded, to the stringer feet, or comprise a covering layer forming the stringer feet, where the covering layer or the stringer feet form(s) the hollow stiffening profile wall provided for contact with the sheet-like component over a substantial area.

3. The process according to claim 1 , wherein step a) comprises one, a plurality or all of steps of:
a1) providing hollow stiffening profiles and/or of a sheet-like component, where these comprise a thermoplastic composite material which comprises:
one or more thermoplastic polymers as matrix material, where these are selected from the group consisting of high-temperature-thermoplastic polymers, engineering plastics, semicrystalline engineering plastics, and polyaryletherketones; and
a reinforcement material, comprising synthetic fibers, or synthetic fibers that are carbon fibers, where the reinforcement material is embedded into the matrix material; and/or
a2) providing a mold that can be a male mold with cavities to receive the hollow stiffening profiles; and/or
a3) providing a mold that can be a male mold with cavities to receive the hollow stiffening profiles and with a hollow-stiffening-profile-cooling unit which is configured adjacent to the cavities in the mold; and/or
a4) providing a male mold with a convexly shaped surface region for lay-up of the sheet-like component; and/or
a5) providing a female mold with a concavely shaped surface region for lay-up of the sheet-like component; and/or
a6) providing a mold that can be a female mold with heating equipment for heating the arrangement laid-up on the mold and made of sheet-like component and of hollow stiffening profiles; and/or
a7) providing an autoclave or pressure autoclave as gastight container.

4. The process according to claim 1 , wherein step b) comprises one, a plurality or all of steps of:
b1) arranging the hollow stiffening profiles in the cavities of the mold and lay-up of the sheet-like component on the surface of the mold; and/or
b2) arranging the sheet-like component on the surface of the mold and positioning of the hollow stiffening profiles on a surface of the sheet-like component; and/or
b3) establishing contact between a surface of the covering layer of the closed omega stringers and the surface of the sheet-like component.

5. The process according to claim 1 ,
wherein step c) comprises one, a plurality or all of steps of:
c1) using air or of an inert gas as heating fluid and/or as cooling fluid; and/or
c2) using a heating fluid and/or of a heated mold with a temperature that is at least about 10° C. above the melting point of thermoplastic composite material, and/or of a cooling fluid with a temperature that is at least about 50° C. below the melting point of thermoplastic composite material; and/or
c3) using a heating fluid and/or of a heated mold with a temperature of about 5° C. to about 120° C., or about 10° C. to about 100° C., or about 10° C. to about 80° C., or about 10° C. to about 60° C. above the melting point of thermoplastic composite material, and a cooling fluid with a temperature of about 50° C. to about 250° C., or about 60° C. to about 180° C., or about 70° C. to about 160° C., or about 90° C. to about 140° C. below the melting point of thermoplastic composite material; and/or
c4) using a heating fluid and/or of a heated mold in combination with a cooling fluid, a temperature of which is selected such that the sheet-like component and the hollow stiffening profile wall, only a side of the hollow stiffening profile wall that adjoins the sheet-like component, are heated above the melting point of thermoplastic composite material, and other sections of the hollow stiffening profiles remain at a temperature below the melting point of thermoplastic composite material; and/or
c5) using a heating fluid and/or of a heated mold in combination with a cooling fluid, a temperature of which is selected such that the hollow stiffening profile wall and the sheet-like component can be coherently bonded to one another and/or other sections of the hollow stiffening profiles remain dimensionally stable and/or the hollow stiffening profiles remain airtight.

6. The process according to claim 1 , wherein step c) comprises:
c7) generating a pressure p A in a range of about 2 to 40 bar, or about 8 to 12 bar, by generating pressure within the gastight container and/or by an external pressure-generation system; and/or
c8) generating a superatmospheric pressure in the hollow stiffening profiles, where the hollow stiffening profile wall of the hollow stiffening profile or the covering layer of the closed omega stringers complies precisely with the desired surface shape of the aircraft component; and/or
c9) generating a superatmospheric pressure in a gap optionally present between the cavities and the hollow stiffening profiles laid-up into the cavities.

7. The process according to claim 1 , wherein cooling of the hollow stiffening profiles in step c) comprises one, a plurality or all of steps of:
c10) introducing heating fluid from the gastight container into a fluid line A configured in the male mold and equipped with a fluid cooling unit A for cooling of the heating fluid, and introducing the resultant cooling fluid into the enclosed space in the hollow stiffening profiles;
c11) conducting heating fluid out of the gastight container into an external fluid line B equipped with a fluid cooling unit B for cooling of the heating fluid, and introducing the resultant cooling fluid into the gastight container and then into the enclosed space in the hollow stiffening profiles;
c12) producing pressurized cooling fluid outside of the gastight container in a separate pressure-generation system and/or by a pump, and introducing the cooling fluid through a fluid line C into the gastight container and then into the enclosed space in the hollow stiffening profiles; and/or
c13) using a cooled insulated flexible or inflexible tube for introduction of the pr

Assignees

• Airbus Operations Gmbh

Inventors

• Jörn Paul
• Hinz Remo

Classifications

• B64C1/061

  Frames · CPC title

• B64C1/064

  Stringers; Longerons · CPC title

• B29C33/0038

  with sealing means or the like (seals on envelopes used in tyre retreading B29D30/542; for injection moulding footwear B29D35/0045) · CPC title

• B29C66/73921

  characterised by the materials of both parts being thermoplastics · CPC title

• B29C2035/1616

  using liquids · CPC title