Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/16—Making multilayered or multicoloured articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/16—Making multilayered or multicoloured articles
  • B29C2045/1682—Making multilayered or multicoloured articles preventing defects
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2269/00—Use of PC, i.e. polycarbonates or derivatives thereof as reinforcement
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
  • B29K2995/0026—Transparent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
  • B29K2995/0029—Translucent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2011/00—Optical elements, e.g. lenses, prisms
  • B29L2011/0075—Light guides, optical cables

Definitions

• the present invention relates to the technical field of molding, preferably by injection, plastic parts of large thickness.
• the invention relates to a method of manufacturing a plastic shell which comprises two large opposite faces and has a larger dimension, measured along a large face, greater than or equal to 10 times the largest thickness of the shell measured between the large faces and greater than or equal to 100 mm, the manufacturing method comprising at least the following steps:
• first portion of shell comprising at least part of one of the large faces of the shell and, opposite the large face, an overmoulding surface at least partially grooved and / or toothed with grooves and / or teeth having a width or thickness less than or equal to 5 mm and spaced from each other by not less than 5 mm,
• the method according to the invention makes it possible to manufacture without deformation or unacceptable shrinkage for the appearance and optical performance of large parts. According to the invention, it is more generally to manufacture hulls of large sizes whose largest dimension is greater than or equal to 100 mm and the largest thickness is greater than or equal to 5 mm. Such parts may also have a height H measured transversely to the thickness E between two opposite faces of the shell, greater than or equal to 30 mm. Such dimensions of parts pose technical problems in particular as regards their appearance and their optical performance unrelated to the technical problems related to the manufacture of small parts, such as generally less than 50 mm. The invention therefore allows the manufacture of large parts where the prior art did not allow it.
• the latter may be formed by overmolding on the first shell portion of more than one other shell portion.
• the method comprises a molding step, on a so-called overmolding surface of reception, of an intermediate shell portion which comprises an overmolding surface at least partially grooved and / or toothed with grooves and / or teeth which have a width or thickness less than or equal to 5 mm and which are spaced from each other by a pitch less than or equal to 5 mm.
• the last portion of shell will be overmolded on an intermediate shell portion.
• the last portion of the shell is overmolded directly on the overmolding surface of the first shell portion.
• one of the large faces has a generally concave shape and the other large face has a generally convex shape.
• This feature takes advantage of the possibilities offered by the process according to the invention to produce hulls of complex shapes that have no defect in appearance or shape, insofar as the method according to the invention makes it possible to control the phenomena of withdrawal.
• the grooves and / or the teeth of each overmoulding surface all have substantially the same width and the same depth and are spaced at the same pitch.
• the local thickness of any portion of a shell portion is less than or equal to 5 mm, preferably less than 3.5 mm.
• the The local thickness is between 1 mm and 5 mm and more preferably between 1.5 mm and 3.5 mm, the local thickness being measured at a distance greater than 1 mm from the edges of the shell portion.
• local thickness it is to be understood the smallest of the distances between two opposite faces, separated continuously by plastic, of a portion of a shell portion.
• the local thickness is less than or equal to one third of the total thickness of the shell.
• the difference between the smallest thickness of the shell and the largest thickness of the shell is less than half the greatest thickness, said thicknesses being measured between the large faces of the shell. the hull and at a distance a distance from the edges of the hull greater than 2 mm.
• the molding and overmolding steps are performed by injection molding the plastic material.
• the injected plastic material is chosen from the following plastics:
• ABS Acrylonitrile butadiene styrene
• the invention also relates to a portion of a plastic shell which comprises two large opposite faces and has a larger dimension, measured along a large face, greater than or equal to 10 times the greatest thickness of the shell measured between the large faces, shell portion characterized in that it comprises one of the large faces of the shell and, opposite the large face, an overmoulding surface at least partially grooved and / or toothed with grooves and / or teeth which have a width or thickness less than or equal to 5 mm and which are spaced from each other by one step, measured parallel to the large face, less than or equal to 5 mm.
• the invention also relates to a shell comprising two large opposite faces and having a larger dimension, measured along a large face, greater than or equal to 10 times the greatest thickness of the shell measured between the large faces and greater than or equal to 100 mm, characterized in that it comprises a first shell portion according to the invention and a last portion of shell which is overmoulded and which includes the other large face of the hull.
• one of the large faces of the shell has a generally concave shape and the other large face of the shell has a generally convex shape.
• the shell comprises at least one overmolded intermediate shell portion and located between the first shell portion and the last shell portion.
• the shell obtained by means of the manufacturing method according to the invention can be used for various applications. So this shell can be opaque and not let the light.
• the shell may also be intended to form a light guide or part of a lighting optics.
• the width of the grooves, the thickness of the teeth and the spacing pitch of the grooves are less than 3.5 mm.
• the width of the grooves, the thickness of the teeth and the spacing pitch of the grooves are between 1 mm and 5 mm.
• the width of the grooves, the thickness of the teeth and the spacing pitch of the grooves are between 1.5 mm and 3.5 mm. Such dimensions allow to adopt short cycle times without risk of defects such as shrinkage.
• the shell has at least one translucent and / or transparent zone.
• the shell comprises at least one opaque portion and at least one transparent or translucent portion.
• the shell is intended to form a light guide and the first shell portion comprises an entrance face of the light and the last shell portion comprises an exit face of light or vice versa. It must therefore be understood that the first portion of the shell may comprise an exit face of the light while the last portion of the shell comprises an entrance face of the light.
• FIG. 1 is a schematic perspective of a shell according to the invention.
• FIG. 1 is a front view of the shell shown in Figure 1.
• FIG. 3 is a section along the lines III-III of Figure 2 at a tongue or tooth of the first shell portion.
• FIG. 4 is a section along the line IV-IV of Figure 2 at a groove of the first shell portion.
• FIG. 5 is an exploded perspective view of the shell illustrated in FIG.
• FIG. 6 is a partial longitudinal section of a portion of the shell shown in Figure 1.
• the invention proposes to make a plastic shell preferably injected so that the shell has no structural defect or deformation induced by the removal and / or cooling of the material after injection.
• a shell is a part whose thickness is small relative to its length developed or measured along one of its large faces when the shell is not developable.
• a shell according to the invention and generally designated by the reference C comprises two large opposite faces 2 and 3.
• the shell C has a larger dimension L, measured along a large face, for example the large face 2, greater than or equal to 10 times the largest thickness E of the shell measured between the large faces 2 and 3.
• the largest dimension L corresponds to the developed length of the large face 2.
• the largest dimension L is preferably greater than or equal to 100 mm, while the height H of the shell is preferably greater than or equal to 30 mm.
• the width L of the shell is preferably greater than or equal to 40 mm.
• the hull C can therefore be described as a large piece.
• the difference between the smallest thickness El of the shell C and the greater thickness E2 of the shell C is less than half of the greater thickness E2, said thicknesses being measured between the large faces 2 and 3 of the shell C.
• the large face 2 has a generally concave shape while the large face 3 has a shape general convex.
• the largest thickness E has, for example, a value greater than or equal to 10 mm. However, this thickness is too large to be injected at one time in a manufacturing cycle of less than 200 seconds counted between the start of the injection and the ejection out of the mold of the injected part, while offering satisfactory structural, aesthetic and dimensional characteristics.
• the invention proposes to design the shell C in several parts or portion of shells that can be molded and overmolded on each other so that at each stage of manufacture the thickness the maximum local area of each shell portion is less than 5 mm and preferably less than 3.5 mm, the maximum local thickness corresponding to the smallest of the distances between two opposite faces, separated continuously by plastic, from a part of a hull portion.
• This local thickness therefore corresponds to the maximum thickness of plastic injected at each stage of manufacture.
• the local thickness may be chosen to be less than one-third of the total thickness of the shell while remaining greater than 1 mm in areas at least 1 mm away from the edges of the shell portions.
• the first shell portion C1 comprises opposite the large face 2, an overmolding surface 10 at least partially grooved and / or toothed.
• overmolding surface 10 comprises an alternation of grooves 11 and tongues 12.
• the tongues 12 form, beyond the large face 2, teeth.
• the grooves have a width i less than or equal to 5 mm.
• the width i is, here, measured perpendicularly to the large face 2, the grooves extending parallel to said large face 2.
• the grooves 11 are spaced apart by a pitch P less than or equal to 5 mm.
• the pitch P then corresponds to the thickness of the tongue / tooth 12 defined by two successive grooves 11.
• the distance d separating the bottom of the grooves 11 of the large face 2 is less than or equal to 5 mm.
• the last portion of shell C2 has a shape complementary to that of the first portion of shell to form in combination therewith the shell C as a whole.
• first shell portion Cl and injection molded plastic in a mold designed for this purpose.
• the plastic material used may be, for example, PMMA.
• the last portion of shell C2 is overmolded the last portion of shell C2 by injection of a plastic compatible with that used for the first portion of shell C2.
• it will be used the same plastic material that constitutes the first shell portion Cl.
• the injected plastic material matches the overmolding surface 10 of the first shell portion C1 and forms part of the large face 3 and in this case a part of the other large large face 2.
• the shell C as illustrated figure 1.
• the overmolding surface 10 occupies on the first shell C2 the major part of the surface or face opposite the part of the large face 2.
• first C1 and last C2 portions of shell have similar dimensions.
• first shell portion Cl forms part of the large face 2 which has a length (greater dimension) substantially equal to the length of the large face 2 of the shell C.
• last portion of the shell C2 forms part of the large face 2 which has a length (greater dimension) substantially equal to the length of the large face 3 of the shell C.
• the shell C is intended to form an optical part. Also, the overmolding of the last portion of the shell is made on the first portion of the shell C1 while the latter has a temperature sufficient to prevent the formation of a diopter between the two shell portions C1 and C2.
• first C1 and last C2 shell portions are defined or designed to each form an entire optical face of either input or output of the light.
• first shell C1 here forms the entirety of an input face of the light Fe while the last shell C2 forms the entirety of the output face Fs of the light.
• a shell C according to the invention is not necessarily an optical part and can form a structural part and / or decorative.
• the shell C forms a "C" whose ends of the branches are connected by a bar for facilitating the attachment of the shell on a support.
• a bar for facilitating the attachment of the shell on a support.
• the implementation of such a bar is not strictly necessary and the shell C may not include said bar.
• a shell according to the invention may have any shape other than that of a C.

Applications Claiming Priority (2)

Publications (1)

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Citations (6)

Family Cites Families (5)

• 2014
  • 2014-04-18 FR FR1453570A patent/FR3020006B1/fr active Active
• 2015
  • 2015-04-20 EP EP15731636.5A patent/EP3131737A1/de not_active Withdrawn
  • 2015-04-20 WO PCT/FR2015/051071 patent/WO2015159038A1/fr active Application Filing

Patent Citations (6)

Non-Patent Citations (1)

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