WO2006122801A1 - Process and mould for moulding structured sheets - Google Patents

Process and mould for moulding structured sheets Download PDF

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Publication number
WO2006122801A1
WO2006122801A1 PCT/EP2006/004712 EP2006004712W WO2006122801A1 WO 2006122801 A1 WO2006122801 A1 WO 2006122801A1 EP 2006004712 W EP2006004712 W EP 2006004712W WO 2006122801 A1 WO2006122801 A1 WO 2006122801A1
Authority
WO
WIPO (PCT)
Prior art keywords
mould
projecting
dimensional structure
process according
negative
Prior art date
Application number
PCT/EP2006/004712
Other languages
French (fr)
Inventor
Giorgio Venere
Adriano Odino
Original Assignee
Renolit Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Renolit Ag filed Critical Renolit Ag
Priority to KR1020077029542A priority Critical patent/KR101051215B1/en
Priority to AT06753703T priority patent/ATE474702T1/en
Priority to PL06753703T priority patent/PL1899132T3/en
Priority to DE602006015645T priority patent/DE602006015645D1/en
Priority to CN2006800175404A priority patent/CN101180169B/en
Priority to EP06753703A priority patent/EP1899132B8/en
Priority to US11/914,134 priority patent/US7794642B2/en
Publication of WO2006122801A1 publication Critical patent/WO2006122801A1/en

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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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/32—Component parts, details or accessories; Auxiliary operations
    • B29C43/36—Moulds for making articles of definite length, i.e. discrete 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/021—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/021—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface
    • B29C2043/026—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface having functional projections, e.g. fasteners
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/32—Component parts, details or accessories; Auxiliary operations
    • B29C43/34—Feeding the material to the mould or the compression means
    • B29C2043/3444—Feeding the material to the mould or the compression means using pressurising feeding means located in the mould, e.g. plungers or pistons
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/32—Component parts, details or accessories; Auxiliary operations
    • B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
    • B29C43/361—Moulds for making articles of definite length, i.e. discrete articles with pressing members independently movable of the parts for opening or closing the mould, e.g. movable pistons
    • B29C2043/3613—Moulds for making articles of definite length, i.e. discrete articles with pressing members independently movable of the parts for opening or closing the mould, e.g. movable pistons applying pressure locally
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/32—Component parts, details or accessories; Auxiliary operations
    • B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
    • B29C43/361—Moulds for making articles of definite length, i.e. discrete articles with pressing members independently movable of the parts for opening or closing the mould, e.g. movable pistons
    • B29C2043/3615—Forming elements, e.g. mandrels or rams or stampers or pistons or plungers or punching devices
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/32—Component parts, details or accessories; Auxiliary operations
    • B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
    • B29C2043/3665—Moulds for making articles of definite length, i.e. discrete articles cores or inserts, e.g. pins, mandrels, sliders
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/32—Component parts, details or accessories; Auxiliary operations
    • B29C43/58—Measuring, controlling or regulating
    • B29C2043/5875—Measuring, controlling or regulating the material feed to the moulds or mould parts, e.g. controlling feed flow, velocity, weight, doses
    • B29C2043/5883—Measuring, controlling or regulating the material feed to the moulds or mould parts, e.g. controlling feed flow, velocity, weight, doses ensuring cavity filling, e.g. providing overflow means
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/18—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/25—Solid
    • B29K2105/253—Preform
    • B29K2105/256—Sheets, plates, blanks or films
    • 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
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • B29L2031/3005—Body finishings
    • 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
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • B29L2031/3005—Body finishings
    • B29L2031/3041—Trim panels

Definitions

  • the invention relates to a process and to a mould for moulding structured sheets.
  • structured sheet is understood to mean a part that essentially has two dimensions, and therefore can result from the continuous deformation of a plane part, possessing a thickness substantially smaller (by at least 100 times) than its width and length, but which includes several appendages having a three-dimensional structure. These may for example be fastening ribs or systems, moulded as one part with the sheet.
  • the interior lining of motor vehicles frequently includes such structured sheets, which are made of thermoplastic material.
  • a known means of producing such structured sheets is the moulding of a molten material in a mould.
  • plastics injection moulding process plastic is heated and mixed in a feed screw and stored in an accumulator. When the latter is full, its content is injected into a temperature-conditioned closed mould where the material is cooled. When the latter has reached a sufficiently low temperature to have a suitable mechanical strength, the mould is opened and the part ejected.
  • the injection of molten material requires high pressures and therefore heavy and expensive machines.
  • the object of the invention is to provide a simplified process for producing low-cost structured sheets. Consequently, the invention relates to a process for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure, in which a blank sheet is placed between the two parts of a mould, the surface of which corresponds to the negative of said three-dimensional structure, and the mould is closed in order to compress the blank sheet and force it to flow into the three-dimensional structure.
  • at least one portion of the surface of the mould surrounding said negative possesses a projecting or recessed feature intended respectively to expel or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.
  • projecting three-dimensional structure is understood to mean any appendage or accessory, made of the same material as the sheet, which it is desired to be integral with this sheet. Typically, these are stiffening ribs or, for example, fastening systems. They may also be overthicknesses intended to reduce the moulding pressure.
  • a recessed structure is a recess made in the sheet during moulding, allowing any useful accessory to be subsequently introduced into it.
  • the three-dimensional structure is projecting and the feature of the mould is a protuberance intended to locally reduce the space provided between the two parts of the mould when it is closed, in order to force the material to penetrate into the negative and to form the three-dimensional structure.
  • the structured sheet will therefore be slightly thinner around the structure.
  • the thickness and the area of the protuberance depend on the volume of the three- dimensional structure, their product having to be close to and if possible slightly greater than this volume (the volume of the reservoir therefore corresponding to the volume of material needed to form the structure).
  • the thickness is greater than 1%, preferably 5% and more preferably 10% of the thickness of the sheet.
  • the thickness of the protuberance will ideally be between 0.2 and 0.4 mm, giving locally a sheet thickness of between 1.6 and 1.8 mm.
  • the process according to the invention is suitable for moulding sheets having thicknesess that vary widely, for example between 0.5 and 10 mm.
  • the process is however particularly advantageous for moulding thin sheets, having a thickness of less than 5 mm, preferably less than 4 mm. It is especially suitable for sheets having a total thickness of between 2 and 3 mm.
  • the negatives are provided, in a known manner, with air venting systems.
  • the three- dimensional structure is projecting and the surface of the mould possesses a protuberance that can be retracted when the mould closes, the protuberance locally increasing the area of the blank sheet, thereby providing material for producing the projecting structure.
  • This retractable protuberance may for example be mounted on a spring.
  • the protuberance raises the blank sheet near the negative. This results in an excess area of blank sheet, corresponding to the flanks of the raised region.
  • the spring is compressed and the protuberance retracts into the mould.
  • the excess amount of blank sheet serves to fill the negative, without requiring flow of material over a long distance, the retractable protuberance having been placed in the vicinity of the negative.
  • the height of the protuberance is determined so as to supply, approximately and in slight excess, the amount of material needed to form the three-dimensional structure.
  • the process according to the invention may apply to any material having sufficient fluidity to allow moulding and formation of three-dimensional structures by flow under pressure. If required, this fluidity may be obtained by heating the material.
  • the blank sheet is made of a fluid plastic.
  • the process according to the invention is particularly advantageous when the plastic includes fibres, as in this case it is difficult for the material to flow onto the three- dimensional structures in the known processes.
  • These may be glass fibres or fibres of any inorganic material, but also organic fibres such as cotton or wood fibres.
  • the plastic may be a thermoset or a thermoplastic.
  • Preferably it is a thermoplastic, for example a polyolefin such as polypropylene.
  • the precise choice of the material will depend on the fluidity needed to form the three-dimensional structures properly and also, for example, on the final coating of the sheet, in order to bond properly thereto.
  • the required fluidity may be easily obtained by heating the material to above its softening temperature.
  • the mould is cooled down to a temperature below this softening temperature, so as to demould a part having good mechanical properties. It is recommended to employ any means for preventing inhomogeneous and premature cooling of the blank sheet before the mould is closed, for example by means of radiation or circulation of hot air.
  • the process according to the invention may be used for moulding structured sheets having three-dimensional structures on both its faces.
  • the sheet possesses a three-dimensional structure only on one of its faces.
  • the process according to the invention makes it possible to obtain a smooth face, free of surface flaws. This is especially advantageous when the three-dimensional structures are deep, as in this case the known processes do not allow a smooth sheet "back", free of sink marks, to be obtained.
  • the excellent surface finish of the face not having a three-dimensional structure allows it to be coated with a thin flexible layer, conforming to the surface finish of the sheet, the coating being for example for cosmetic purposes.
  • the coating may for example be fabrics, sheets of plastics, such as flexible PVC, or leather. This coating may be advantageously produced during moulding of the sheet. Consequently, in one method of implementing this version, before the mould is closed, a flexible coating is superposed on that face of the blank sheet intended to remain smooth.
  • the layer of fibres be a fibrous fabric formed from cotton fibres or glass fibres.
  • a mould having a particular internal surface feature, providing a material reservoir function around the negatives of the three- dimensional structures, is used.
  • the invention also relates to a mould for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure, comprising a negative of said three-dimensional structure, at least one portion of the surface of the mould surrounding said negative possessing a feature intended to form a local reservoir able to supply or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.
  • the three- dimensional structure is projecting and the feature of the mould is a protuberance intended to locally reduce the space left between the two parts of the mould when it is closed, in order to force the material to penetrate into the negative and form the three- dimensional structure.
  • the three-dimensional structure to be projecting and the surface of the mould to possess a protuberance that can retract when the mould closes, the protuberance locally increasing the area of the blank sheet, thereby providing material for producing the projecting structure.
  • Figures 1 to 4 are diagrams illustrating various aspects of the process and the mould according to the invention.
  • Figure 5 shows, at 5a, a known moulding process and at 5b a preferred version of the process and of the mould according to the invention.
  • Figure 1 illustrates the negatives (2) of the mould and processes according to the invention, and the protuberance (1) of a preferred version.
  • Figures 2 to 4 may be seen a glass-fibre fabric placed between the blank sheet made of wood-fibre-filled polypropylene and the flexible PVC coating (4), the smooth face (5) containing no three-dimensional structure, and the three-dimensional structures (6) located on the other face.
  • Figure 5 shows the coating (4), the blank sheet (7), the retractable protuberance (10) and the negative (2) of the three-dimensional structure.
  • Figure 5b shows that the retractable protuberance, actuated by the spring (8), causes the appearance of flanks (9) on the blank sheet (7), thereby constituting a supply of material for filling the negative (2).
  • the mould Around the negative (2), the mould has a protuberance (1) with a thickness of 0.5 mm.
  • the blank sheet was preheated to a temperature of 210 0 C.
  • the mould was kept at a temperature of 5O 0 C by means of the circulation of a conditioning fluid.
  • the mould was then closed, exerting a force of W

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
  • Slide Fasteners, Snap Fasteners, And Hook Fasteners (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Process for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure (6), in which a blank sheet (7) is placed between the two parts of a mould, the surface of which corresponds to the negative (2) of said three-dimensional structure. At least one portion of the surface of the mould surrounding said negative possesses a feature intended to form a local reservoir able to supply or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.

Description

Process and mould for moulding structured sheets
The invention relates to a process and to a mould for moulding structured sheets. The term "structured sheet" is understood to mean a part that essentially has two dimensions, and therefore can result from the continuous deformation of a plane part, possessing a thickness substantially smaller (by at least 100 times) than its width and length, but which includes several appendages having a three-dimensional structure. These may for example be fastening ribs or systems, moulded as one part with the sheet. The interior lining of motor vehicles frequently includes such structured sheets, which are made of thermoplastic material.
A known means of producing such structured sheets is the moulding of a molten material in a mould. Examples of any injection moulding of plastics and the casting of aluminium are well known. In the plastics injection moulding process, plastic is heated and mixed in a feed screw and stored in an accumulator. When the latter is full, its content is injected into a temperature-conditioned closed mould where the material is cooled. When the latter has reached a sufficiently low temperature to have a suitable mechanical strength, the mould is opened and the part ejected. However, in particular when the structured sheets are thin, the injection of molten material requires high pressures and therefore heavy and expensive machines.
It is also known to combine compression moulding with injection moulding, such as for example described in EP 1 153 725. In such a process, the two-dimensional part is moulded by compression moulding while the three-dimensional parts are injection moulded. However, an injection moulding machine and a mould capable of withstanding high pressures are still necessary, thereby increasing the cost of the process.
The object of the invention is to provide a simplified process for producing low-cost structured sheets. Consequently, the invention relates to a process for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure, in which a blank sheet is placed between the two parts of a mould, the surface of which corresponds to the negative of said three-dimensional structure, and the mould is closed in order to compress the blank sheet and force it to flow into the three-dimensional structure. According to the invention, at least one portion of the surface of the mould surrounding said negative possesses a projecting or recessed feature intended respectively to expel or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.
The expression "projecting three-dimensional structure" is understood to mean any appendage or accessory, made of the same material as the sheet, which it is desired to be integral with this sheet. Typically, these are stiffening ribs or, for example, fastening systems. They may also be overthicknesses intended to reduce the moulding pressure. A recessed structure is a recess made in the sheet during moulding, allowing any useful accessory to be subsequently introduced into it.
It has been observed that the presence of such features, constituting small "reservoirs", limits the length of the paths that the material must follow during moulding, and therefore reduces the moulding pressure. This results in a lower mould-clamping force, and therefore lighter and less expensive machines. Moreover, when the three-dimensional structure is projecting, better filling of the negative is obtained. When the structure is recessed, uncontrolled overthicknesses or surface flaws ("sink marks") are avoided.
In a first preferred version of the process according to the invention, the three-dimensional structure is projecting and the feature of the mould is a protuberance intended to locally reduce the space provided between the two parts of the mould when it is closed, in order to force the material to penetrate into the negative and to form the three-dimensional structure. The structured sheet will therefore be slightly thinner around the structure. The thickness and the area of the protuberance depend on the volume of the three- dimensional structure, their product having to be close to and if possible slightly greater than this volume (the volume of the reservoir therefore corresponding to the volume of material needed to form the structure). Advantageously, the thickness is greater than 1%, preferably 5% and more preferably 10% of the thickness of the sheet. It is recommended that this reduction remain less than 50%, preferably 30% and more preferably 20% of the thickness of the sheet. For a sheet with a thickness of 2 mm, the thickness of the protuberance will ideally be between 0.2 and 0.4 mm, giving locally a sheet thickness of between 1.6 and 1.8 mm. The process according to the invention is suitable for moulding sheets having thicknesess that vary widely, for example between 0.5 and 10 mm. The process is however particularly advantageous for moulding thin sheets, having a thickness of less than 5 mm, preferably less than 4 mm. It is especially suitable for sheets having a total thickness of between 2 and 3 mm. The negatives are provided, in a known manner, with air venting systems.
In a second preferred version of the process according to the invention, the three- dimensional structure is projecting and the surface of the mould possesses a protuberance that can be retracted when the mould closes, the protuberance locally increasing the area of the blank sheet, thereby providing material for producing the projecting structure. This retractable protuberance may for example be mounted on a spring. When the mould is open, the protuberance raises the blank sheet near the negative. This results in an excess area of blank sheet, corresponding to the flanks of the raised region. When the mould is closed, the spring is compressed and the protuberance retracts into the mould. The excess amount of blank sheet serves to fill the negative, without requiring flow of material over a long distance, the retractable protuberance having been placed in the vicinity of the negative. The height of the protuberance is determined so as to supply, approximately and in slight excess, the amount of material needed to form the three-dimensional structure.
The process according to the invention may apply to any material having sufficient fluidity to allow moulding and formation of three-dimensional structures by flow under pressure. If required, this fluidity may be obtained by heating the material.
In one advantageous method of implementing the process, the blank sheet is made of a fluid plastic. The process according to the invention is particularly advantageous when the plastic includes fibres, as in this case it is difficult for the material to flow onto the three- dimensional structures in the known processes. These may be glass fibres or fibres of any inorganic material, but also organic fibres such as cotton or wood fibres. The plastic may be a thermoset or a thermoplastic. Preferably it is a thermoplastic, for example a polyolefin such as polypropylene. The precise choice of the material will depend on the fluidity needed to form the three-dimensional structures properly and also, for example, on the final coating of the sheet, in order to bond properly thereto. In this case, the required fluidity may be easily obtained by heating the material to above its softening temperature. In this method of implementation, the mould is cooled down to a temperature below this softening temperature, so as to demould a part having good mechanical properties. It is recommended to employ any means for preventing inhomogeneous and premature cooling of the blank sheet before the mould is closed, for example by means of radiation or circulation of hot air.
The process according to the invention may be used for moulding structured sheets having three-dimensional structures on both its faces. However, in one particularly advantageous version, the sheet possesses a three-dimensional structure only on one of its faces. In this version, when the blank sheet is made of a fluid plastic, it is advantageous for that face intended to remain smooth to be covered with a layer of fibres so as to improve its mechanical integrity, and therefore to make it easier to handle and to reduce the risk of the plastic sticking to the equipment. Moreover, in this version, the process according to the invention makes it possible to obtain a smooth face, free of surface flaws. This is especially advantageous when the three-dimensional structures are deep, as in this case the known processes do not allow a smooth sheet "back", free of sink marks, to be obtained. This advantage of the process according to the invention is even more pronounced when the material is a crystalline polymer, the shrinkage of which as it crystallizes causes, in a known manner, sink marks on the reverse side of large ribs or overthicknesses. In this version, the excellent surface finish of the face not having a three-dimensional structure allows it to be coated with a thin flexible layer, conforming to the surface finish of the sheet, the coating being for example for cosmetic purposes. The coating may for example be fabrics, sheets of plastics, such as flexible PVC, or leather. This coating may be advantageously produced during moulding of the sheet. Consequently, in one method of implementing this version, before the mould is closed, a flexible coating is superposed on that face of the blank sheet intended to remain smooth.
In this method of implementation, it is advantageous to place a layer of fibres between the blank sheet and the coating, so as to avoid any deformation of the surface finish of the coating during moulding. It is recommended that the layer of fibres be a fibrous fabric formed from cotton fibres or glass fibres.
In the process according to the invention, a mould having a particular internal surface feature, providing a material reservoir function around the negatives of the three- dimensional structures, is used.
Consequently, the invention also relates to a mould for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure, comprising a negative of said three-dimensional structure, at least one portion of the surface of the mould surrounding said negative possessing a feature intended to form a local reservoir able to supply or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.
According to a recommended version of the mould according to the invention, the three- dimensional structure is projecting and the feature of the mould is a protuberance intended to locally reduce the space left between the two parts of the mould when it is closed, in order to force the material to penetrate into the negative and form the three- dimensional structure.
It is also advantageous in the mould according to the invention for the three-dimensional structure to be projecting and the surface of the mould to possess a protuberance that can retract when the mould closes, the protuberance locally increasing the area of the blank sheet, thereby providing material for producing the projecting structure.
Particular aspects of the invention will emerge from the following description of the appended figures. Figures 1 to 4 are diagrams illustrating various aspects of the process and the mould according to the invention.
Figure 5 shows, at 5a, a known moulding process and at 5b a preferred version of the process and of the mould according to the invention.
Figure 1 illustrates the negatives (2) of the mould and processes according to the invention, and the protuberance (1) of a preferred version.
In Figures 2 to 4 may be seen a glass-fibre fabric placed between the blank sheet made of wood-fibre-filled polypropylene and the flexible PVC coating (4), the smooth face (5) containing no three-dimensional structure, and the three-dimensional structures (6) located on the other face.
Figure 5 shows the coating (4), the blank sheet (7), the retractable protuberance (10) and the negative (2) of the three-dimensional structure. Figure 5b shows that the retractable protuberance, actuated by the spring (8), causes the appearance of flanks (9) on the blank sheet (7), thereby constituting a supply of material for filling the negative (2).
The following example serves to illustrate the invention.
Example
A sheet of polypropylene (BP, HCW1 MFI 20 with the dimensions of 2.5 x 250 x 250 mm) filled with 30% of wood fibres, covered with a fabric of polypropylene and kenaf fibres having a thickness of 1.5 mm and a relative density of 1.06, was taken and placed over the mould illustrated in Figure 1. Around the negative (2), the mould has a protuberance (1) with a thickness of 0.5 mm. A coating, consisting of flexible PVC, having a density of 1200 g/m2, was placed on top of the glass-fibre fabric. The blank sheet was preheated to a temperature of 2100C. The mould was kept at a temperature of 5O0C by means of the circulation of a conditioning fluid. The mould was then closed, exerting a force of W
60 tonnes for a time of 30 seconds. After the mould was opened, a sheet having three- dimensional structures (6) illustrated in Figure 4 was obtained.

Claims

1. Process for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure (6), in which a blank sheet (7) is placed between the two parts of a mould, the surface of which corresponds to the negative (2) of said three- dimensional structure, and the mould is closed in order to compress the blank sheet (7) and force it to flow into the three-dimensional structure, characterized in that at least one portion of the surface of the mould surrounding said negative possesses a projecting or recessed feature intended respectively to expel or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.
2. Process according to the preceding claim, in which the three-dimensional structure is projecting and the feature of the mould is a protuberance (1) intended to locally reduce the space provided between the two parts of the mould when it is closed, in order to force the material to penetrate into the negative (2) and to form the three- dimensional structure (6).
3. Process according to either of the preceding claims, in which the three-dimensional structure is projecting and the surface of the mould possesses a protuberance (10) that can be retracted when the mould closes, the protuberance locally increasing the area of the blank sheet by the appearance of flanks (9), thereby providing material for producing the projecting structure.
4. Process according to any one of the preceding claims, in which the blank sheet is made of a fluid plastic.
5. Process according to the preceding claim, in which the fluid plastic is a thermoplastic that has been preheated to above its softening point and in which the mould is conditioned at a temperature below the softening point.
6. Process according to any one of the preceding claims, in which the sheet possesses a three-dimensional structure only on one of its faces.
7. Process according to the preceding claim, in which, before the mould is closed, a flexible coating is superposed on that face of the blank sheet intended to remain smooth.
8. Process according to the preceding claim, in which a layer of fibres is placed between the sheet and the coating.
9. Process according to the preceding claim, in which the layer of fibres is a fibrous fabric.
10. Mould for moulding sheets possessing, locally, a three-dimensional projecting or recessed structure, comprising a negative of said three-dimensional structure, at least one portion of the surface of the mould surrounding said negative possessing a feature intended to form a local reservoir able to supply or receive material of the three-dimensional structure depending on whether it is projecting or recessed, respectively.
11. Mould according to the preceding claim, in which the three-dimensional structure is projecting and the feature of the mould is a protuberance intended to locally reduce the space left between the two parts of the mould when it is closed, in order to force the material to penetrate into the negative and form the three-dimensional structure.
12. Mould according to either of Claims 10 and 11 , in which the three-dimensional structure is projecting and the surface of the mould possesses a protuberance that can retract when the mould closes, the protuberance locally increasing the area of the blank sheet, thereby providing material for producing the projecting structure.
PCT/EP2006/004712 2005-05-20 2006-05-18 Process and mould for moulding structured sheets WO2006122801A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
KR1020077029542A KR101051215B1 (en) 2005-05-20 2006-05-18 Processes and Molds for Forming Structured Sheets
AT06753703T ATE474702T1 (en) 2005-05-20 2006-05-18 METHOD AND MOLDING TOOL FOR SHAPING STRUCTURED SURFACES
PL06753703T PL1899132T3 (en) 2005-05-20 2006-05-18 Process and mould for moulding structured sheets
DE602006015645T DE602006015645D1 (en) 2005-05-20 2006-05-18 METHOD AND TOOL TOOL FOR FORMING STRUCTURED SURFACES
CN2006800175404A CN101180169B (en) 2005-05-20 2006-05-18 Process and mould for moulding structured sheets
EP06753703A EP1899132B8 (en) 2005-05-20 2006-05-18 Process and mould for moulding structured sheets
US11/914,134 US7794642B2 (en) 2005-05-20 2006-05-18 Process and mold for molding structured sheets

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0505111A FR2885840B1 (en) 2005-05-20 2005-05-20 METHOD AND MOLD FOR MOLDING STRUCTURED PLATES
FR0505111 2005-05-20

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EP (1) EP1899132B8 (en)
KR (1) KR101051215B1 (en)
CN (1) CN101180169B (en)
AT (1) ATE474702T1 (en)
DE (1) DE602006015645D1 (en)
ES (1) ES2349308T3 (en)
FR (1) FR2885840B1 (en)
PL (1) PL1899132T3 (en)
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WO2011001454A1 (en) * 2009-07-01 2011-01-06 Renolit Ag Process and mould for moulding structured sheets.
WO2016207309A1 (en) * 2015-06-23 2016-12-29 Hexcel Reinforcements SASU Improvements in or relating to three dimensional mouldings
CN110461563A (en) * 2016-12-21 2019-11-15 赫克赛尔加固材料公司 Improvement or improvement related with three dimensional molded part in three dimensional molded part

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ITGE20100013A1 (en) 2010-02-01 2011-08-02 Renolit Ag SLAB WITH THREE-DIMENSIONAL PERFORMANCE PROVIDED WITH THREE-DIMENSIONAL STRUCTURES OVERLAPPING AND METHOD FOR ITS REALIZATION

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JPH09174566A (en) * 1995-12-25 1997-07-08 Fujitsu Ltd Stamper for reproducing optical element
EP1019232B1 (en) * 1997-10-02 2003-01-15 Borealis GmbH Differentiated pressing process
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Cited By (4)

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Publication number Priority date Publication date Assignee Title
WO2011001454A1 (en) * 2009-07-01 2011-01-06 Renolit Ag Process and mould for moulding structured sheets.
WO2016207309A1 (en) * 2015-06-23 2016-12-29 Hexcel Reinforcements SASU Improvements in or relating to three dimensional mouldings
CN110461563A (en) * 2016-12-21 2019-11-15 赫克赛尔加固材料公司 Improvement or improvement related with three dimensional molded part in three dimensional molded part
CN110461563B (en) * 2016-12-21 2021-11-16 赫克赛尔加固材料公司 Improvements in or relating to three-dimensional moulded articles

Also Published As

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KR20080031867A (en) 2008-04-11
PL1899132T3 (en) 2011-04-29
EP1899132A1 (en) 2008-03-19
FR2885840A1 (en) 2006-11-24
ES2349308T3 (en) 2010-12-29
EP1899132B8 (en) 2010-08-25
ATE474702T1 (en) 2010-08-15
CN101180169B (en) 2010-10-13
EP1899132B1 (en) 2010-07-21
KR101051215B1 (en) 2011-07-21
CN101180169A (en) 2008-05-14
DE602006015645D1 (en) 2010-09-02
FR2885840B1 (en) 2007-08-10
US20080246184A1 (en) 2008-10-09
US7794642B2 (en) 2010-09-14

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