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EP3089863A1 - Method for compression moulding with set of abutments - Google Patents

Method for compression moulding with set of abutments

Info

Publication number
EP3089863A1
EP3089863A1 EP14833520.1A EP14833520A EP3089863A1 EP 3089863 A1 EP3089863 A1 EP 3089863A1 EP 14833520 A EP14833520 A EP 14833520A EP 3089863 A1 EP3089863 A1 EP 3089863A1
Authority
EP
European Patent Office
Prior art keywords
mold
sheet
reinforcing sheet
stops
reinforcement
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP14833520.1A
Other languages
German (de)
French (fr)
Inventor
Damien BOISSON
Denis Gille
Patrick Bosg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plastic Omnium SE
Original Assignee
Plastic Omnium SE
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 Plastic Omnium SE filed Critical Plastic Omnium SE
Publication of EP3089863A1 publication Critical patent/EP3089863A1/en
Withdrawn legal-status Critical Current

Links

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
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
    • B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
    • B29C70/345—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using matched moulds
    • 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
    • B29C43/20—Making multilayered or multicoloured articles
    • B29C43/203—Making multilayered 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
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
    • 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
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
    • B29C70/461—Rigid movable compressing mould parts acting independently from opening or closing action of the main mould
    • 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
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
    • B29C70/467—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs and impregnating the reinforcements during mould closing
    • 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
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
    • B29C70/541—Positioning reinforcements in a mould, e.g. using clamping means for the reinforcement
    • 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
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
    • B29C70/543—Fixing the position or configuration of fibrous reinforcements before or during moulding
    • 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
    • B29C2043/3602—Moulds for making articles of definite length, i.e. discrete articles with means for positioning, fastening or clamping the material to be formed or preforms inside the mould
    • 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
    • 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
    • B29L2031/3055—Cars

Definitions

  • SMC Sheet Molding Compound
  • the SMC is in the form of a sheet of resin-impregnated fiber mat that is cut to desired dimensions before being deposited in an open mold.
  • the closing of the mold causes the compression of the resin, its creep until filling of the mold cavity and finally its vulcanization under the effect of the temperature increase resulting from the compression (and possibly a heating of the mold ).
  • Compression-molded SMC offers the possibility of local reinforcements by ribs or bumps, either by thickening the molded part in some places or by occasionally superimposing other pre-impregnated sheets having other proportions of fibers and of resin than the main SMC leaf.
  • the methods of adding local reinforcements currently used involve either unimpregnated resin reinforcement sheets or impregnated sheets.
  • the impregnation of the reinforcement is done by the resin of the main SMC sheet, also called base sheet.
  • the reinforcement used is a non-impregnated resin sheet
  • the amount of resin present on the SMC sheet to be reinforced is low (especially in the case of high-performance SMC loaded with 50% cut glass fibers)
  • the total amount of resin is insufficient to properly impregnate the reinforcement and it may arise including moisture penetration problems in the finished parts.
  • the mechanical properties of the assembly are not improved, or even they are degraded compared to the properties of SMC high performance alone.
  • the mechanical properties of the assembly are then only slightly improved, except to provide oversized reinforcements so as to ensure that their extent is sufficient to continue to cover the area to be reinforced, even after a displacement of the reinforcement in the mold.
  • the subject of the invention is a process for molding a part by compression of at least a first sheet containing plastics material, the compression causing the plastic material to flow in flow directions, in a mold in at least two parts closing one against the other, characterized in that the following steps are carried out:
  • the reinforcing sheet is immobilized against a set of stops.
  • the term "stop assembly” is understood to mean at least one stop.
  • the set of stops may therefore consist of one or more stops.
  • a set of abutments according to the invention can be obtained for example either by creating in the mold an extra thickness localized to the dimensions of the reinforcement, or by cutting in the first sheet, also designated base sheet, a cavity to the dimensions of the reinforcement for the integrate directly, before molding, to the molding structure. Thanks to the invention, the creep of resin resulting from the compression of the base sheet does not cause the displacement of the reinforcing sheet. By “does not cause displacement", it is meant that the reinforcing sheet does not move or moves very little in the mold during creep of the resin.
  • the invention does not aim at a total immobilization of the reinforcing sheet but a holding position in the mold so that the area to be reinforced of the molded part is covered by the reinforcing sheet.
  • the holding in position of the reinforcing sheet must above all be effective during the molding phase during which most of the creep of the plastic material occurs, that is to say at the beginning of the compression.
  • the invention consists in providing means for maintaining the reinforcing sheet in position during the molding phase during which the plastic material, or resin, is distributed in the mold to fill it.
  • the invention therefore makes it possible to use, as a reinforcing sheet, a sheet impregnated with plastic without encountering the problem of moving the reinforcing sheet during compression molding.
  • the stop or stops of the set of abutments does not necessarily have a vocation to be durable. It suffices that the stop or stops of the set of stops fulfill their function of maintaining the reinforcing sheet during the massive creep phase of the resin. Beyond this phase, it is irrelevant that the stop or stops remain or disappear.
  • the set of stops results from cutting the first sheet. This cutout shows the slice of the first cut sheet and this slice constitutes a set of stops to prevent the reinforcing sheet from moving during molding.
  • the backing sheet is placed against the cut edge of the first sheet or base sheet.
  • the resin that flows into the mold from the base sheet penetrates the reinforcing sheet in a plurality of opposite directions, so that the backing sheet experiences opposing transverse forces that reduce its tendency to move.
  • the reinforcing sheet is blocked transversely by the cut edge of the base sheet.
  • the base sheet loses its stiffness and its slices from the cut form less rigid barriers. But at this later stage of molding, the resin has almost completely filled the mold and the risk of movement of the backing sheet has disappeared.
  • the set of stops is formed by at least one transverse wall of the mold. This wall may be permanent or temporary.
  • a fixed transverse wall may result from the realization in the mold of a recessed housing for receiving the reinforcing sheet before closing the mold.
  • a transverse wall may also result from the presence of a rib in the mold, against which the reinforcing sheet is placed to wedge it transversely.
  • the molded part has a shape that reflects the presence of this transverse wall.
  • this form is not a problem.
  • the piece may comprise a boss that corresponds to the hollow recess made in the mold.
  • the transverse wall is designed to be temporary.
  • the mold may comprise a movable part which can take a retaining position in which the transverse wall is formed and makes it possible to retain the reinforcing sheet and a molding position in which the transverse wall disappears.
  • the moving part is positioned in the molding position when the creep of the plastic material in the mold has reached a stage where the risk of driving the reinforcement sheet is considered to have been eliminated.
  • a first example of a moving part is a core whose section is that of a recessed housing in which it is desired to deposit the reinforcing sheet.
  • the core When the core is recessed, the hollow recess is formed, while when the core is flush with the surface of the surrounding wall of the mold, the housing disappears.
  • the core is set back while the mold is still open.
  • the reinforcement sheet is then deposited in the recessed housing.
  • the base sheet intended to constitute the remainder of the part is then placed on top of the reinforcing sheet, then the mold is closed (the positions can be reversed if the housing is above and not below the sheet of based).
  • the core just before the end of the molding, the core is moved to flush in the mold to remove any relief on the part due to the presence of the reinforcing sheet.
  • a second example of a moving part is a retractable rib.
  • the rib When the mold is open, the rib is out and the reinforcing sheet may be arranged against the rib, acting as a transverse wall which retains the reinforcing sheet during creep of the resin.
  • the mold is closed until the resin has almost completely filled the mold.
  • the rib is then retracted and the closure of the mold is completed.
  • the reinforcing sheet no longer moves because the movements of material due to creep are very small and the removal of the rib avoids leaving traces on the part obtained.
  • the first plastic material consists of SMC TD (30% FV + UP) or SMC HP (50% FV + VE).
  • the reinforcement sheet is made of continuous fiberglass reinforcements, impregnated or non-impregnated.
  • the invention also relates to a part obtained by the implementation of the method described above, as well as to a motor vehicle part, characterized by the presence, in at least one location of the part, of a thickening of a plastic material reinforced with reinforcing fibers and whose fiber content or the orientation of the fibers differs from the fiber content or the orientation of the fibers of the material of which the piece is made to said location.
  • FIG. 1 represents rolls of impregnated fiber mat sheets used in an embodiment of FIG. the invention
  • FIG. 2 is a sectional view of an open mold in which the pre-cut sheets have been deposited for molding purposes;
  • - Figure 3a is a sectional view of an open mold and empty in the matrix of which was dug a set of stops, here in the form of a cavity
  • - Figure 3b is a sectional view of an open mold and empty in the punch of which was dug a set of stops, here in the form of a cavity;
  • FIG. 3c is a sectional view of an open mold and empty in the punch of which was dug a set of stops, here in the form of protruding ribs;
  • - Figure 4a is a set of sectional views illustrating the closure of the mold (empty) in case of movable stops;
  • FIG. 4b is a set of sectional views illustrating the closure of the mold (empty) in case of movable stops.
  • FIG. 1 shows two rolls 1 and 2 of resin-impregnated fiber mat sheets (uncooked SMC), the use of which is common in the manufacture of parts made of compression-molded reinforced material.
  • the roll 1 represents a roll of a first sheet containing plastic, the main material of which will be made the piece to be molded.
  • the cutting of the mat of the roll 1 will give the (or) main sheet (s) 3.
  • the roll 2 represents a roll of a second sheet containing the reinforced plastic fiberglass material, said reinforcement.
  • the cutting of the mat of the roll 2 will give the reinforcing sheet 4 which will be used to strengthen punctually the piece formed by the main sheet 3.
  • a first embodiment is that the set of stops is obtained by cutting the or (they are here three) base sheets 3.
  • the cutout thus shows the slices of the sheets of base 3 which will form the set of abutments 5-1.
  • the reinforcing sheet 4 precut according to the shape given to the set of abutments 5-1, is then placed in the recess formed by the set of abutments 5-1.
  • the reinforcing sheet 4 is immobilized against the slices of the base sheets 3 during the start of the molding, ie while the movements of the material due to creep are the most important.
  • the resin indeed flows into the mold 6 from the base sheets 3 and penetrates the reinforcing sheet 4 in several opposite directions, so that the reinforcing sheet 4 undergoes antagonistic transverse forces which reduce its tendency to move.
  • the reinforcing sheet 4 is blocked transversely by the cut edge of the base sheets 3.
  • the set of abutments 5-1 will finish, at a later stage of the molding, by softening and the cut slices by forming less rigid barriers, it will not be a disadvantage because, at this stage of the molding, the resin will have almost completely filled the mold 6 and the risk of displacement of the reinforcing sheet 4 will be zero.
  • other embodiments have been designed to remedy this eventuality.
  • FIG. 3a shows an embodiment in which the set of stops 5-2 is cut in the die 7a of the mold 7. This is a case where the set of stops 5-2 is permanent.
  • the molding results in a thickening localized to the reinforced zone of the molded part.
  • the reinforcing sheet 4 is placed in the recess formed by the set of abutments 5-2 in the die 7a of the mold 7 (under the base sheet (s) 3) and will thus be prevented from flow during molding.
  • FIG. 3b shows an embodiment in which the set of stops 5-3 is cut into the punch 8b of the mold 8. This is a case where the set of stops 5-3 is permanent and it will result from this molding an extra thickness localized to the reinforced zone of the molded part.
  • the reinforcing sheet 4 is placed in the recess formed by the set of stops 5-3 in the die 8b of the mold 8 (over the base sheet (s) 3) and will thus be prevented. to flow during the molding process.
  • FIG. 3c shows an embodiment in which the set of abutments 5-4 is formed of a set of ribs 10 projecting from the punch 9b of the mold 9.
  • the set of abutments 5-4 is permanent and it will result from this molding localized hollows on the edges of the reinforced zone of the molded part.
  • the reinforcing sheet 4 is placed in the area delimited by the set of ribs 10 projecting from the punch 9b, forming the set of stops 5-4 of the mold 9 (under the sheet (s) base 3) and will thus be prevented from flowing during molding.
  • FIG. 4a A first variant of this embodiment is illustrated in FIG. 4a.
  • the punch 11b of the mold 11 has a movable portion.
  • a first example of a moving part is a core 12 whose section is that of a recessed housing in which it is desired to deposit the reinforcing sheet 4.
  • the core 12 When the core is in removal, the hollow recess is formed and provides the set of stops 5-5, while when the core is flush with the surface of the surrounding wall of the mold, the housing disappears, causing the disappearance of the set of stops 5- 5.
  • the core 12 is set back while the mold 11 is still open. The reinforcing sheet 4 is then deposited in the recessed housing.
  • the base sheet (s) 3 (s) intended to form the remainder of the piece are then placed on top of the reinforcing sheet 4, then the mold 11 is closed. Before the die 11a is completely lowered, the movable portion 12 is raised, resulting in the disappearance of the set of stops 5-5 which held the reinforcing sheet 4 in place. However, as for the first embodiment, at this stage of the molding, the resin will already have almost completely filled the mold 11 and the risk of displacement of the reinforcing sheet 4 will have disappeared.
  • FIG. 4b A second variant of this embodiment is illustrated in FIG. 4b.
  • the punch 13b of the mold 13 comprises a movable part.
  • the moving part is a set of retractable ribs 14 which form, when the mold is open, the set of stops 5-6.
  • the reinforcing sheet 4 may be disposed against said ribs, and the set of ribs 14 then acts as a transverse wall which retains the reinforcing sheet 4 during creep of the resin.
  • the mold 13 is closed until the resin has almost completely filled.
  • the set of ribs 14 is then retracted, making the set of abutments 5-6 disappear and the closure of the mold 13 is completed.
  • the reinforcing sheet 4 no longer moves because the movements of material due to creep are very small and the removal of the rib assembly 14 avoids leaving traces on the piece obtained.
  • the invention thus provides an advantageous and economical solution to the production of locally reinforced parts, without the disadvantage of using oversized reinforcements.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Textile Engineering (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)

Abstract

The invention relates to a method for moulding a part by compression of at least one first sheet (3) containing plastic material, the compression leading to the creeping of the plastic material in flow directions, in a mould (6) with at least two portions closing against one another, characterised in that the following steps are executed: targeted reinforcement of at least one specific area of the part to be moulded by means of a reinforcement sheet (4) cut to the required dimensions in a material other than that of the first sheet; accurate positioning of the reinforcement sheet (4) in the mould; retention of the reinforcement sheet against a set of abutments (5-1) which are transverse to the flow directions; and closing the mould.

Description

Procédé de moulage par compression à ensemble de butées  Compression molding process with abutment assembly
Le matériau connu sous l'acronyme SMC, pour Sheet Molding Compound, est un matériau au rapport résistance/poids élevé, ce qui en fait un matériau idéal pour des pièces de grande taille.  The material known by the acronym SMC, for Sheet Molding Compound, is a high strength / weight ratio material, making it an ideal material for large parts.
Par ailleurs, sa stabilité thermique, ses propriétés mécaniques et électriques en font un des matériau clé de nombreuses industries, notamment du secteur automobile. Moreover, its thermal stability, its mechanical and electrical properties make it a key material for many industries, particularly in the automotive sector.
Le SMC se présente sous forme de feuille constituée d'un mat de fibres imprégnées de résine que l'on découpe aux dimensions souhaitées avant de la déposer dans un moule ouvert. La fermeture du moule provoque la compression de la résine, son fluage jusqu'à remplissage de l'empreinte du moule et finalement sa vulcanisation sous l'effet de l'augmentation de température résultant de la compression (et éventuellement d'un chauffage du moule). The SMC is in the form of a sheet of resin-impregnated fiber mat that is cut to desired dimensions before being deposited in an open mold. The closing of the mold causes the compression of the resin, its creep until filling of the mold cavity and finally its vulcanization under the effect of the temperature increase resulting from the compression (and possibly a heating of the mold ).
Le SMC mis en forme par moulage par compression offre la possibilité de renforcements locaux par nervures ou par bosses, soit en épaississant la pièce moulée à certains endroits, soit en superposant ponctuellement d'autres feuilles pré- imprégnées ayant d'autres proportions de fibres et de résine que la feuille de SMC principale. Compression-molded SMC offers the possibility of local reinforcements by ribs or bumps, either by thickening the molded part in some places or by occasionally superimposing other pre-impregnated sheets having other proportions of fibers and of resin than the main SMC leaf.
Ceci est notamment le cas dans les processus de moulage de pièces tels que les hayons ou des portes de coffres par exemple, pour renforcer mécaniquement les zones de poignées où les zones charnières et serrures. Ce procédé est également utilisé pour toute pièce nécessitant un renfort mécanique anti-fissuration. This is particularly the case in the molding process of parts such as tailgates or doors of boxes for example, to mechanically strengthen the areas of handles where the hinges and locks. This process is also used for any part requiring mechanical anti-cracking reinforcement.
Les procédés d'ajouts de renforts locaux utilisés actuellement mettent en jeu soit des feuilles de renfort non imprégnées de résine, soit des feuilles imprégnées. Dans le premier cas, l'imprégnation du renfort se fait par la résine de la feuille de SMC principale, aussi appelée feuille de base. Ces deux cas soulèvent cependant des difficultés. The methods of adding local reinforcements currently used involve either unimpregnated resin reinforcement sheets or impregnated sheets. In the first case, the impregnation of the reinforcement is done by the resin of the main SMC sheet, also called base sheet. These two cases, however, raise difficulties.
Dans le cas où le renfort utilisé est une feuille non-imprégnée de résine, si la quantité de résine présente sur la feuille de SMC à renforcer est faible (notamment dans les cas de SMC haute performance chargé à 50% de fibres de verres coupées), la quantité totale de résine est insuffisante pour imprégner correctement le renfort et il peut se poser notamment des problèmes de pénétration d'humidité dans les pièces finies. De plus, les propriétés mécaniques de l'assemblage ne sont pas améliorées, voire, elles sont dégradées par rapport aux propriétés de SMC haute performance seul. Pour y remédier, on peut donc tenter d'utiliser des renforts sous forme de feuilles imprégnées. Mais dans ce cas de l'utilisation de renforts imprégnés, on se retrouve confronté à un fluage important de la résine lors de la compression. Ce fluage de la résine peut éloigner la feuille de renfort de la zone à renforcer. Les propriétés mécaniques de l'ensemble ne sont alors que faiblement améliorées, sauf à prévoir des renforts surdimensionnés de manière à garantir que leur étendue est suffisante pour continuer à couvrir la zone à renforcer, même après un déplacement du renfort dans le moule. In the case where the reinforcement used is a non-impregnated resin sheet, if the amount of resin present on the SMC sheet to be reinforced is low (especially in the case of high-performance SMC loaded with 50% cut glass fibers) , the total amount of resin is insufficient to properly impregnate the reinforcement and it may arise including moisture penetration problems in the finished parts. In addition, the mechanical properties of the assembly are not improved, or even they are degraded compared to the properties of SMC high performance alone. To remedy this, we can try to use reinforcements in the form of impregnated sheets. But in this case of the use of impregnated reinforcements, one is faced with a significant creep of the resin during compression. This creep of the resin can move the reinforcement sheet away from the zone to be reinforced. The mechanical properties of the assembly are then only slightly improved, except to provide oversized reinforcements so as to ensure that their extent is sufficient to continue to cover the area to be reinforced, even after a displacement of the reinforcement in the mold.
La présente invention propose de résoudre ce problème. A cet effet, l'invention a pour objet un procédé de moulage d'une pièce par compression d'au-moins une première feuille contenant de la matière plastique, la compression entraînant le fluage de la matière plastique dans des directions d'écoulement, dans un moule en au-moins deux parties se fermant l'une contre l'autre, caractérisé en ce qu'on exécute les étapes suivantes: The present invention proposes to solve this problem. To this end, the subject of the invention is a process for molding a part by compression of at least a first sheet containing plastics material, the compression causing the plastic material to flow in flow directions, in a mold in at least two parts closing one against the other, characterized in that the following steps are carried out:
- renforcement ciblé d'au moins un zone spécifique de la pièce à mouler à l'aide d'au moins une feuille de renfort découpée aux dimensions voulues dans un matériau différent de celui de la première feuille,  targeted reinforcement of at least one specific zone of the part to be molded using at least one reinforcement sheet cut to the desired dimensions in a material different from that of the first sheet,
- positionnement précis dans le moule de la feuille de renfort,  precise positioning in the mold of the reinforcing sheet,
- rétention de la feuille de renfort contre un ensemble de butées transversales aux directions d'écoulement,  retention of the reinforcing sheet against a set of abutments transverse to the flow directions,
- fermeture du moule.  - closing the mold.
Selon l'invention, on immobilise la feuille de renfort contre un ensemble de butées. Selon l'invention, on entend par ensemble de butées au moins une butée. L'ensemble de butées peut donc être constitué d'une seule ou de plusieurs butées. Un ensemble de butées selon l'invention peut être obtenu par exemple soit en créant dans le moule une surépaisseur localisée aux dimensions du renfort, soit en découpant dans la première feuille, également désignée feuille de base, une cavité aux dimensions du renfort pour l'intégrer directement, avant moulage, à la structure à mouler. Grâce à l'invention, le fluage de résine résultant de la compression de la feuille de base ne provoque pas le déplacement de la feuille de renfort. Par "ne provoque pas le déplacement", on entend que la feuille de renfort ne se déplace pas ou ne se déplace que très peu, dans le moule, pendant le fluage de la résine. Bien entendu, l'invention ne vise pas une totale immobilisation de la feuille de renfort mais un maintien en position dans le moule de manière que la zone à renforcer de la pièce moulée soit couverte par la feuille de renfort. Le maintien en position de la feuille de renfort doit surtout être effectif pendant la phase de moulage au cours de laquelle se produit l'essentiel du fluage de la matière plastique, c'est à dire au début de la compression. Une fois que la matière plastique a presque complètement rempli le moule, il ne se produit plus alors dans le moule que de faibles déplacements de matière plastique et un déplacement significatif de la feuille de renfort n'est plus à craindre. According to the invention, the reinforcing sheet is immobilized against a set of stops. According to the invention, the term "stop assembly" is understood to mean at least one stop. The set of stops may therefore consist of one or more stops. A set of abutments according to the invention can be obtained for example either by creating in the mold an extra thickness localized to the dimensions of the reinforcement, or by cutting in the first sheet, also designated base sheet, a cavity to the dimensions of the reinforcement for the integrate directly, before molding, to the molding structure. Thanks to the invention, the creep of resin resulting from the compression of the base sheet does not cause the displacement of the reinforcing sheet. By "does not cause displacement", it is meant that the reinforcing sheet does not move or moves very little in the mold during creep of the resin. Of course, the invention does not aim at a total immobilization of the reinforcing sheet but a holding position in the mold so that the area to be reinforced of the molded part is covered by the reinforcing sheet. The holding in position of the reinforcing sheet must above all be effective during the molding phase during which most of the creep of the plastic material occurs, that is to say at the beginning of the compression. Once the plastic has almost completely filled the mold, then there is no longer any movement of plastic material in the mold and a significant displacement of the reinforcement sheet is no longer to be feared.
Ainsi, l'invention consiste-t-elle à prévoir des moyens pour maintenir la feuille de renfort en position pendant la phase de moulage au cours de laquelle la matière plastique, ou résine, se répartit dans le moule pour le remplir. Thus, the invention consists in providing means for maintaining the reinforcing sheet in position during the molding phase during which the plastic material, or resin, is distributed in the mold to fill it.
L'invention permet donc d'utiliser, comme feuille de renfort, une feuille imprégnée de matière plastique, sans rencontrer le problème du déplacement de la feuille de renfort pendant le moulage par compression. Conformément aux explications ci-dessus, la ou les butées de l'ensemble de butées n'a pas nécessairement vocation à être durable. Il suffit que la ou les butées de l'ensemble de butées remplissent leur fonction de maintien de la feuille de renfort pendant la phase de fluage massif de la résine. Au-delà de cette phase, il est indifférent que la ou les butées perdurent ou s'effacent. Ainsi, dans un premier mode de réalisation de l'invention, l'ensemble de butées résulte- t-il d'une découpe de la première feuille. Cette découpe fait apparaître la tranche de la première feuille découpée et cette tranche constitue un ensemble de butées pour empêcher la feuille de renfort de se déplacer pendant le moulage. Dans ce mode de réalisation, la feuille de renfort est placée contre la tranche découpée de la première feuille ou feuille de base. La résine qui flue dans le moule à partir de la feuille de base pénètre dans la feuille de renfort dans plusieurs directions opposées, de sorte que la feuille de renfort subit des forces transversales antagonistes qui réduisent sa tendance à se déplacer. De plus, la feuille de renfort est bloquée transversalement par la tranche découpée de la feuille de base. Au bout d'un certain temps, la feuille de base perd de sa raideur et ses tranches issues de la découpe forment des barrières moins rigides. Mais à ce stade plus avancé du moulage, la résine a presque entièrement rempli le moule et le risque de déplacement de la feuille de renfort a disparu. Dans un autre mode de réalisation, l'ensemble de butées est formé par au moins une paroi transversale du moule. Cette paroi peut être permanente ou provisoire. The invention therefore makes it possible to use, as a reinforcing sheet, a sheet impregnated with plastic without encountering the problem of moving the reinforcing sheet during compression molding. In accordance with the explanations above, the stop or stops of the set of abutments does not necessarily have a vocation to be durable. It suffices that the stop or stops of the set of stops fulfill their function of maintaining the reinforcing sheet during the massive creep phase of the resin. Beyond this phase, it is irrelevant that the stop or stops remain or disappear. Thus, in a first embodiment of the invention, the set of stops results from cutting the first sheet. This cutout shows the slice of the first cut sheet and this slice constitutes a set of stops to prevent the reinforcing sheet from moving during molding. In this embodiment, the backing sheet is placed against the cut edge of the first sheet or base sheet. The resin that flows into the mold from the base sheet penetrates the reinforcing sheet in a plurality of opposite directions, so that the backing sheet experiences opposing transverse forces that reduce its tendency to move. In addition, the reinforcing sheet is blocked transversely by the cut edge of the base sheet. After a while, the base sheet loses its stiffness and its slices from the cut form less rigid barriers. But at this later stage of molding, the resin has almost completely filled the mold and the risk of movement of the backing sheet has disappeared. In another embodiment, the set of stops is formed by at least one transverse wall of the mold. This wall may be permanent or temporary.
Une paroi transversale fixe peut résulter de la réalisation dans le moule, d'un logement en creux destiné à recevoir la feuille de renfort avant fermeture du moule. Une paroi transversale peut également résulter de la présence d'une nervure dans le moule, contre laquelle on place la feuille de renfort pour la caler transversalement. A fixed transverse wall may result from the realization in the mold of a recessed housing for receiving the reinforcing sheet before closing the mold. A transverse wall may also result from the presence of a rib in the mold, against which the reinforcing sheet is placed to wedge it transversely.
Dans le cas où la paroi transversale est permanente, la pièce moulée possède une forme qui traduit la présence de cette paroi transversale. Dans un certain nombre d'applications, cette forme n'est pas gênante. Par exemple, la pièce peut comporter un bossage qui correspond au logement en creux réalisé dans le moule. La présence, en au moins un emplacement de la pièce, d'une surépaisseur d'une matière plastique renforcée en fibres de renfort et dont le taux de fibres ou l'orientation des fibres diffère du taux de fibres ou de l'orientation des fibres du matériau dont est faite la pièce audit emplacement ou dans le reste de la pièce, caractérise la pièce comme ayant été obtenue par mise en œuvre de l'invention. In the case where the transverse wall is permanent, the molded part has a shape that reflects the presence of this transverse wall. In a number of applications, this form is not a problem. For example, the piece may comprise a boss that corresponds to the hollow recess made in the mold. The presence, in at least one location of the part, of an extra thickness of a plastic material reinforced with reinforcing fibers and whose fiber content or the orientation of the fibers differs from the fiber content or the orientation of the fibers of the material of which the piece is made at said location or in the rest of the room, characterizes the piece as having been obtained by implementation of the invention.
Mais dans certaines applications, il peut être problématique de laisser sur la pièce moulée des formes résultant de la présence de la paroi transversale dans le moule. Dans ce cas, selon une variante particulière, la paroi transversale est conçue pour être provisoire. A cet effet, le moule peut comporter une partie mobile qui peut prendre une position de retenue dans laquelle la paroi transversale est formée et permet de retenir la feuille de renfort et une position de moulage dans laquelle la paroi transversale disparait. Dans ce cas, on positionne la partie mobile en position de moulage lorsque le fluage de la matière plastique dans le moule a atteint un stade où le risque d'entraînement de la feuille de renfort est considéré comme écarté. Un premier exemple de partie mobile est un noyau dont la section est celle d'un logement en creux dans lequel on souhaite déposer la feuille de renfort. Lorsque le noyau est en retrait, le logement en creux est formé, tandis que lorsque le noyau affleure à la surface de la paroi environnante du moule, le logement disparait. Pour mettre en œuvre l'invention, on place le noyau en retrait alors que le moule est encore ouvert. On dépose alors la feuille de renfort dans le logement en creux. On place ensuite la feuille de base destinée à constituer le reste de la pièce par-dessus la feuille de renfort, puis on ferme le moule (les positions peuvent être inverses si le logement se trouve au-dessus et non en dessous de la feuille de base). Pendant la compression, juste avant la fin du moulage, on déplace le noyau pour le mettre à affleurement dans le moule pour faire disparaître tout relief sur la pièce dû à la présence de la feuille de renfort. But in some applications, it may be problematic to leave on the molded shapes resulting from the presence of the transverse wall in the mold. In this case, according to a particular variant, the transverse wall is designed to be temporary. For this purpose, the mold may comprise a movable part which can take a retaining position in which the transverse wall is formed and makes it possible to retain the reinforcing sheet and a molding position in which the transverse wall disappears. In this case, the moving part is positioned in the molding position when the creep of the plastic material in the mold has reached a stage where the risk of driving the reinforcement sheet is considered to have been eliminated. A first example of a moving part is a core whose section is that of a recessed housing in which it is desired to deposit the reinforcing sheet. When the core is recessed, the hollow recess is formed, while when the core is flush with the surface of the surrounding wall of the mold, the housing disappears. To implement the invention, the core is set back while the mold is still open. The reinforcement sheet is then deposited in the recessed housing. The base sheet intended to constitute the remainder of the part is then placed on top of the reinforcing sheet, then the mold is closed (the positions can be reversed if the housing is above and not below the sheet of based). During the compression, just before the end of the molding, the core is moved to flush in the mold to remove any relief on the part due to the presence of the reinforcing sheet.
Un deuxième exemple de partie mobile est une nervure rétractable. Lorsque le moule est ouvert, la nervure est sortie et la feuille de renfort peut être disposée contre la nervure, agissant comme paroi transversale qui retient la feuille de renfort lors du fluage de la résine. On ferme le moule jusqu'à ce que la résine ait presque complètement rempli le moule. On rétracte alors la nervure et on achève la fermeture du moule. La feuille de renfort ne se déplace plus car les mouvements de matière dus au fluage sont très faibles et la suppression de la nervure évite de laisser des traces sur la pièces obtenue. A second example of a moving part is a retractable rib. When the mold is open, the rib is out and the reinforcing sheet may be arranged against the rib, acting as a transverse wall which retains the reinforcing sheet during creep of the resin. The mold is closed until the resin has almost completely filled the mold. The rib is then retracted and the closure of the mold is completed. The reinforcing sheet no longer moves because the movements of material due to creep are very small and the removal of the rib avoids leaving traces on the part obtained.
Suivant d'autres caractéristiques particulières de l'invention, qui peuvent être prises seules ou en combinaison : According to other particular features of the invention, which can be taken alone or in combination:
- La première matière plastique est constituée de SMC TD (30%FV+UP) ou de SMC HP (50%FV+VE). - La feuille de renfort est faite de renforts à fibres de verre continues, imprégnées ou non imprégnées. - The first plastic material consists of SMC TD (30% FV + UP) or SMC HP (50% FV + VE). - The reinforcement sheet is made of continuous fiberglass reinforcements, impregnated or non-impregnated.
L'invention a également pour objet une pièce obtenue par la mise-en-œuvre du procédé décrit ci-dessus, ainsi qu'un pièce de véhicule automobile, caractérisée par la présence, en au moins un emplacement de la pièce, d'une surépaisseur d'une matière plastique renforcée en fibres de renfort et dont le taux de fibres ou l'orientation des fibres diffère du taux de fibres ou de l'orientation des fibres du matériau dont est faite la pièce audit emplacement. The invention also relates to a part obtained by the implementation of the method described above, as well as to a motor vehicle part, characterized by the presence, in at least one location of the part, of a thickening of a plastic material reinforced with reinforcing fibers and whose fiber content or the orientation of the fibers differs from the fiber content or the orientation of the fibers of the material of which the piece is made to said location.
Dans le but de mieux faire comprendre l'invention, on va maintenant en décrire des modes de réalisation, en référence aux dessins annexés dans lesquels : - la figure 1 représente des rouleaux de feuilles de mat de fibres imprégnées utilisés dans un mise en œuvre de l'invention ; In order to better understand the invention, embodiments will now be described with reference to the accompanying drawings, in which: FIG. 1 represents rolls of impregnated fiber mat sheets used in an embodiment of FIG. the invention;
- la figure 2 est une vue en coupe d'un moule ouvert dans lequel on a déposé les feuilles pré-découpées en vue de leur moulage ; FIG. 2 is a sectional view of an open mold in which the pre-cut sheets have been deposited for molding purposes;
- la figure 3a est une vue en coupe d'un moule ouvert et vide dans la matrice duquel a été creusé un ensemble de butées, ici sous la forme d'une cavité ; - la figure 3b est une vue en coupe d'un moule ouvert et vide dans le poinçon duquel a été creusé un ensemble de butées, ici sous la forme d'une cavité ; - Figure 3a is a sectional view of an open mold and empty in the matrix of which was dug a set of stops, here in the form of a cavity; - Figure 3b is a sectional view of an open mold and empty in the punch of which was dug a set of stops, here in the form of a cavity;
- la figure 3c est une vue en coupe d'un moule ouvert et vide dans le poinçon duquel a été creusé un ensemble de butées, ici sous la forme de nervures en saillie ; - la figure 4a est un ensemble de vues en coupe illustrant la fermeture du moule (vide) en cas de butées mobiles ; - Figure 3c is a sectional view of an open mold and empty in the punch of which was dug a set of stops, here in the form of protruding ribs; - Figure 4a is a set of sectional views illustrating the closure of the mold (empty) in case of movable stops;
- la figure 4b est un ensemble de vues en coupe illustrant la fermeture du moule (vide) en cas de butées mobiles. - Figure 4b is a set of sectional views illustrating the closure of the mold (empty) in case of movable stops.
On a représenté, sur la figure 1 , deux rouleaux 1 et 2 de feuilles de mat de fibres imprégnées de résine (SMC non cuits), dont l'utilisation est courante dans la fabrication de pièces en matière renforcée par moulage par compression. Le rouleau 1 représente un rouleau d'une première feuille contenant de la matière plastique, la matière principale dont sera faite la pièce à mouler. La découpe du mat du rouleau 1 donnera la (ou les) feuille(s) principale(s) 3. Le rouleau 2 représente un rouleau d'une seconde feuille contenant de la matière plastique renforcée en fibres de verre, dite de renfort. La découpe du mat du rouleau 2 donnera la feuille de renfort 4 qui servira à renforcer ponctuellement la pièce formée par la feuille principale 3. FIG. 1 shows two rolls 1 and 2 of resin-impregnated fiber mat sheets (uncooked SMC), the use of which is common in the manufacture of parts made of compression-molded reinforced material. The roll 1 represents a roll of a first sheet containing plastic, the main material of which will be made the piece to be molded. The cutting of the mat of the roll 1 will give the (or) main sheet (s) 3. The roll 2 represents a roll of a second sheet containing the reinforced plastic fiberglass material, said reinforcement. The cutting of the mat of the roll 2 will give the reinforcing sheet 4 which will be used to strengthen punctually the piece formed by the main sheet 3.
Comme représenté sur la figure 2, un premier mode de réalisation consiste en ce que l'ensemble de butées soit obtenu par découpe de la ou des (elles sont ici trois) feuilles de base 3. La découpe fait ainsi apparaître les tranches des feuilles de base 3 qui formeront l'ensemble de butées 5-1 . La feuille de renfort 4, prédécoupée selon la forme donnée à l'ensemble de butées 5-1 , est alors placée dans le creux formé par l'ensemble de butées 5-1 . Ainsi la la feuille de renfort 4 est immobilisée contre les tranches des feuilles de base 3 pendant le début du moulage, à savoir alors que les mouvements de la matière dus à son fluage sont les plus importants. La résine flue en effet dans le moule 6 à partir des feuilles de base 3 et pénètre dans la feuille de renfort 4 dans plusieurs directions opposées, de sorte que la feuille de renfort 4 subit des forces transversales antagonistes qui réduisent sa tendance à se déplacer. De plus, la feuille de renfort 4 est bloquée transversalement par la tranche découpée des feuilles de base 3. Il est vrai que l'ensemble de butées 5-1 finira, à un stade plus avancé du moulage, par se ramollir et les tranches découpées par former des barrières moins rigides, ce ne sera plus un inconvénient car, à ce stade du moulage, la résine aura presque entièrement rempli le moule 6 et le risque de déplacement de la feuille de renfort 4 sera nul. Il n'est cependant pas toujours possible de découper la (ou les) feuille(s) de base 3 en vue de créer l'ensemble de butées 5-1 . Ainsi, d'autres modes de réalisation ont-ils été conçus pour remédier à cette éventualité. As shown in Figure 2, a first embodiment is that the set of stops is obtained by cutting the or (they are here three) base sheets 3. The cutout thus shows the slices of the sheets of base 3 which will form the set of abutments 5-1. The reinforcing sheet 4, precut according to the shape given to the set of abutments 5-1, is then placed in the recess formed by the set of abutments 5-1. Thus, the reinforcing sheet 4 is immobilized against the slices of the base sheets 3 during the start of the molding, ie while the movements of the material due to creep are the most important. The resin indeed flows into the mold 6 from the base sheets 3 and penetrates the reinforcing sheet 4 in several opposite directions, so that the reinforcing sheet 4 undergoes antagonistic transverse forces which reduce its tendency to move. In addition, the reinforcing sheet 4 is blocked transversely by the cut edge of the base sheets 3. It is true that the set of abutments 5-1 will finish, at a later stage of the molding, by softening and the cut slices by forming less rigid barriers, it will not be a disadvantage because, at this stage of the molding, the resin will have almost completely filled the mold 6 and the risk of displacement of the reinforcing sheet 4 will be zero. However, it is not always possible to cut the (or) base sheet (s) 3 to create the set of stops 5-1. Thus, other embodiments have been designed to remedy this eventuality.
Sur la figure 3a, on voit illustré un mode de réalisation dans lequel l'ensemble de butées 5-2 est découpé dans la matrice 7a du moule 7. Il s'agit d'un cas où l'ensemble de butées 5-2 est permanent. Il résulte du moulage une surépaisseur localisée à la zone renforcée de la pièce moulée. En effet, la feuille de renfort 4 est placée dans le creux formé par l'ensemble de butées 5-2 dans la matrice 7a du moule 7 (sous la (ou les) feuille(s) de base 3) et sera ainsi empêchée de fluer pendant le moulage. Sur la figure 3b, on voit illustré un mode de réalisation dans lequel l'ensemble de butées 5-3 est découpé dans le poinçon 8b du moule 8. Il s'agit d'un cas où l'ensemble de butées 5-3 est permanent et il résultera de ce moulage une surépaisseur localisée à la zone renforcée de la pièce moulée. En effet, la feuille de renfort 4 est placée dans le creux formé par l'ensemble de butées 5-3 dans la matrice 8b du moule 8 (par dessus la (ou les) feuille(s) de base 3) et sera ainsi empêchée de fluer pendant le processus de moulage. FIG. 3a shows an embodiment in which the set of stops 5-2 is cut in the die 7a of the mold 7. This is a case where the set of stops 5-2 is permanent. The molding results in a thickening localized to the reinforced zone of the molded part. Indeed, the reinforcing sheet 4 is placed in the recess formed by the set of abutments 5-2 in the die 7a of the mold 7 (under the base sheet (s) 3) and will thus be prevented from flow during molding. FIG. 3b shows an embodiment in which the set of stops 5-3 is cut into the punch 8b of the mold 8. This is a case where the set of stops 5-3 is permanent and it will result from this molding an extra thickness localized to the reinforced zone of the molded part. Indeed, the reinforcing sheet 4 is placed in the recess formed by the set of stops 5-3 in the die 8b of the mold 8 (over the base sheet (s) 3) and will thus be prevented. to flow during the molding process.
Sur la figure 3c, on voit illustré un mode de réalisation dans lequel l'ensemble de butées 5-4 est formée d'un ensemble de nervures 10 en saillie par rapport au poinçon 9b du moule 9. Il s'agit d'un cas où l'ensemble de butées 5-4 est permanent et il résultera de ce moulage des creux localisés sur les bords de la zone renforcée de la pièce moulée. En effet, la feuille de renfort 4 est placée dans la zone délimitée par l'ensemble des nervures 10 en saillie du poinçon 9b, formant l'ensemble de butées 5-4 du moule 9 (sous la (ou les) feuille(s) de base 3) et sera ainsi empêchée de fluer pendant le moulage. Si les surépaisseurs ou les creux localisés ne sont pas forcément un inconvénient pour certaines pièces moulées, il peut arriver que de telles déformations, même ponctuelles, de la pièce originale, ne puissent être acceptables. Dans le cas où il ne serait pas non plus possible de découper la (ou les) feuille(s) de base 3, il est possible de créer l'ensemble de butées 5-4 selon un autre mode de réalisation dans lequel ces butées n'existent dans le moule que de façon provisoire. FIG. 3c shows an embodiment in which the set of abutments 5-4 is formed of a set of ribs 10 projecting from the punch 9b of the mold 9. This is a case where the set of abutments 5-4 is permanent and it will result from this molding localized hollows on the edges of the reinforced zone of the molded part. Indeed, the reinforcing sheet 4 is placed in the area delimited by the set of ribs 10 projecting from the punch 9b, forming the set of stops 5-4 of the mold 9 (under the sheet (s) base 3) and will thus be prevented from flowing during molding. If the overthicknesses or localized hollows are not necessarily a disadvantage for certain molded parts, it may happen that such deformations, even punctual, of the original part, can not be acceptable. In the case where it is also not possible to cut the (or) sheet (s) base 3, it is possible to create the set of stops 5-4 according to another embodiment in which these stops 'exist in the mold only temporarily.
Une première variante de ce mode de réalisation est illustrée par la figure 4a. Sur cette figure, on voit que le poinçon 11 b du moule 11 comporte une partie mobile. Un premier exemple de partie mobile est un noyau 12 dont la section est celle d'un logement en creux dans lequel on souhaite déposer la feuille de renfort 4. Lorsque le noyau est en retrait, le logement en creux est formé et fournit l'ensemble de butées 5-5, tandis que lorsque le noyau affleure à la surface de la paroi environnante du moule, le logement disparait, entraînant la disparition de l'ensemble de butées 5-5. Pour mettre en œuvre l'invention, on place le noyau 12 en retrait alors que le moule 11 est encore ouvert. On dépose alors la feuille de renfort 4 dans le logement en creux. On place ensuite la (ou les) feuille(s) de base 3 destinée(s) à constituer le reste de la pièce par-dessus la feuille de renfort 4, puis on ferme le moule 11 . Avant que la matrice 11 a ne soit complètement abaissée, la partie mobile 12 est remontée, entraînant la disparition de l'ensemble de butées 5-5 qui maintenait la feuille de renfort 4 en place. Cependant, comme pour le premier mode de réalisation, à ce stade du moulage la résine aura déjà presque entièrement rempli le moule 11 et le risque de déplacement de la feuille de renfort 4 aura disparu. A first variant of this embodiment is illustrated in FIG. 4a. In this figure, we see that the punch 11b of the mold 11 has a movable portion. A first example of a moving part is a core 12 whose section is that of a recessed housing in which it is desired to deposit the reinforcing sheet 4. When the core is in removal, the hollow recess is formed and provides the set of stops 5-5, while when the core is flush with the surface of the surrounding wall of the mold, the housing disappears, causing the disappearance of the set of stops 5- 5. To implement the invention, the core 12 is set back while the mold 11 is still open. The reinforcing sheet 4 is then deposited in the recessed housing. The base sheet (s) 3 (s) intended to form the remainder of the piece are then placed on top of the reinforcing sheet 4, then the mold 11 is closed. Before the die 11a is completely lowered, the movable portion 12 is raised, resulting in the disappearance of the set of stops 5-5 which held the reinforcing sheet 4 in place. However, as for the first embodiment, at this stage of the molding, the resin will already have almost completely filled the mold 11 and the risk of displacement of the reinforcing sheet 4 will have disappeared.
Une deuxième variante de ce mode de réalisation est illustrée par la figure 4b. Sur cette figure, on voit que le poinçon 13b du moule 13 comporte une partie mobile. Dans cet exemple, la partie mobile est un ensemble de nervures rétractables 14 qui forment, lorsque le moule est ouvert, l'ensemble de butées 5-6. Quand l'ensemble de nervures est sorti, la feuille de renfort 4 peut être disposée contre lesdites nervures, et l'ensemble de nervures 14 agit alors comme paroi transversale qui retient la feuille de renfort 4 lors du fluage de la résine. Après avoir placé la feuille de renfort 4 et la (ou les) feuille(s) de base 3 dans le moule 13, on ferme le moule 13 jusqu'à ce que la résine l'ait presque complètement rempli. On rétracte alors l'ensemble de nervures 14, faisant disparaître l'ensemble de butées 5-6 et on achève la fermeture du moule 13. La feuille de renfort 4 ne se déplace plus car les mouvements de matière dus au fluage sont très faibles et la suppression de l'ensemble nervure 14 évite ainsi de laisser des traces sur la pièce obtenue. A second variant of this embodiment is illustrated in FIG. 4b. In this figure, we see that the punch 13b of the mold 13 comprises a movable part. In this example, the moving part is a set of retractable ribs 14 which form, when the mold is open, the set of stops 5-6. When the set of ribs is out, the reinforcing sheet 4 may be disposed against said ribs, and the set of ribs 14 then acts as a transverse wall which retains the reinforcing sheet 4 during creep of the resin. After placing the reinforcing sheet 4 and the base sheet (s) 3 in the mold 13, the mold 13 is closed until the resin has almost completely filled. The set of ribs 14 is then retracted, making the set of abutments 5-6 disappear and the closure of the mold 13 is completed. The reinforcing sheet 4 no longer moves because the movements of material due to creep are very small and the removal of the rib assembly 14 avoids leaving traces on the piece obtained.
L'invention procure donc une solution avantageuse et économique à la réalisation de pièces renforcées localement, sans présenter l'inconvénient d'utiliser des renforts surdimensionnés. The invention thus provides an advantageous and economical solution to the production of locally reinforced parts, without the disadvantage of using oversized reinforcements.
L'invention n'est pas limitée aux modes de réalisation qui viennent d'être décrit. Elle pourra recevoir toute modification désirable à la portée de l'homme du métier, sur la base de ses connaissances générales. The invention is not limited to the embodiments which have just been described. It may receive any desirable modification within the reach of the person skilled in the art, on the basis of his general knowledge.

Claims

REVENDICATIONS
1 . Procédé de moulage d'une pièce par compression d'au-moins une première feuille (3) contenant de la matière plastique, la compression entraînant le fluage de la matière plastique dans des directions d'écoulement, dans un moule (6, 7, 8, 11 , 13) en au- moins deux parties se fermant l'une contre l'autre, caractérisé en ce qu'on exécute les étapes suivantes:  1. A method of molding a workpiece by compressing at least a first plastic-containing sheet (3), the compression causing the flow of the plastic material in flow directions, in a mold (6, 7, 8, 11, 13) in at least two parts closing one against the other, characterized in that the following steps are carried out:
- renforcement ciblé d'au moins un zone spécifique de la pièce à mouler à l'aide d'au moins une feuille de renfort (4) découpée aux dimensions voulues dans un matériau différent de celui de la première feuille,  targeted reinforcement of at least one specific zone of the workpiece with at least one reinforcement sheet cut to the desired dimensions in a material different from that of the first sheet,
- positionnement précis dans le moule de la feuille de renfort (4),  precise positioning in the mold of the reinforcing sheet (4),
- rétention de la feuille de renfort contre un ensemble de butées (5-1 , 5-2, 5-3, 5- 4, 5-5, 5-6) transversales aux directions d'écoulement,  retention of the reinforcing sheet against a set of stops (5-1, 5-2, 5-3, 5-4, 5-5, 5-6) transverse to the flow directions,
- fermeture du moule.  - closing the mold.
2. Procédé selon la revendication précédente, dans lequel un ensemble de butées ceint la feuille de renfort (4).  2. Method according to the preceding claim, wherein a set of stops surrounds the reinforcing sheet (4).
3. Procédé selon les revendications 1 ou 2, dans lequel l'ensemble de butées (5-1 ) est découpé dans la première feuille (3). 3. Method according to claims 1 or 2, wherein the set of stops (5-1) is cut in the first sheet (3).
4. Procédé selon les revendication 1 et 2, dans lequel l'ensemble de butées (5-2, 5-3, 5-4) est formé par au moins une paroi transversale du moule. 4. The method of claim 1 and 2, wherein the set of stops (5-2, 5-3, 5-4) is formed by at least one transverse wall of the mold.
5. Procédé selon la précédente revendication, dans lequel la paroi transversale résulte de la réalisation dans le moule, d'un logement en creux (5-2, 5-3) destiné à recevoir la feuille de renfort avant fermeture du moule. 5. Method according to the preceding claim, wherein the transverse wall results from the embodiment in the mold, a recessed housing (5-2, 5-3) for receiving the reinforcing sheet before closing the mold.
6. Procédé selon la revendication 4, dans lequel la paroi transversale résulte de la présence d'une nervure (5-4) dans le moule. 6. The method of claim 4, wherein the transverse wall results from the presence of a rib (5-4) in the mold.
7. Procédé selon l'une quelconque des revendications 4 à 6, dans lequel le moule comporte une partie mobile (5-5, 5-6) qui peut prendre une position de retenue dans laquelle la paroi transversale est formée et permet de retenir la feuille de renfort et une position de moulage dans laquelle la paroi transversale disparaît, et dans lequel on positionne la partie mobile (5-5, 5-6) en position de moulage lorsque le fluage de la matière plastique dans le moule a atteint un stade où le risque d'entraînement de la feuille de renfort est considéré comme écarté. 7. A method according to any one of claims 4 to 6, wherein the mold comprises a movable portion (5-5, 5-6) which can take a retaining position in which the transverse wall is formed and allows to retain the reinforcing sheet and a molding position in which the transverse wall disappears, and in which the moving part (5-5, 5-6) is positioned in the molding position when the creep of the plastic material in the mold has reached a stage where the risk of training of the reinforcement sheet is considered to be rejected.
8. Procédé selon l'une quelconque des revendications précédentes, dans lequel la matière plastique de la première feuille (3) est constituée de SMC TD (30%FV+UP) ou de SMC HP (50%FV+VE). A method according to any one of the preceding claims, wherein the plastics material of the first sheet (3) consists of SMC TD (30% FV + UP) or SMC HP (50% FV + VE).
9. Procédé selon l'une quelconque des revendications précédentes, dans lequel la feuille de renfort (4) est faite de renforts à fibres de verre continues, imprégnées ou non imprégnées. 9. A method according to any one of the preceding claims, wherein the reinforcing sheet (4) is made of continuous fiberglass reinforcements, impregnated or non-impregnated.
10. Pièce obtenue par la mise-en-œuvre du procédé selon l'une quelconque des précédentes revendications. 10. Part obtained by the implementation of the method according to any one of the preceding claims.
11 . Pièce de véhicule automobile, caractérisée par la présence, en au moins un emplacement de la pièce, d'une surépaisseur d'une matière plastique renforcée en fibres de renfort et dont le taux de fibres ou l'orientation des fibres diffère du taux de fibres ou de l'orientation des fibres du matériau dont est faite la pièce audit emplacement. 11. Motor vehicle part, characterized by the presence, in at least one location of the part, of an extra thickness of a plastic material reinforced with reinforcing fibers and whose fiber content or the orientation of the fibers differs from the fiber content or the orientation of the fibers of the material of which the piece is made to said location.
EP14833520.1A 2013-12-31 2014-12-23 Method for compression moulding with set of abutments Withdrawn EP3089863A1 (en)

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FR1363747A FR3015923B1 (en) 2013-12-31 2013-12-31 COMPRESSION MOLDING METHOD WITH STOP ASSEMBLY
PCT/FR2014/053524 WO2015101741A1 (en) 2013-12-31 2014-12-23 Method for compression moulding with set of abutments

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US10183421B2 (en) * 2016-09-16 2019-01-22 General Electric Company Molding method
IT201900023139A1 (en) * 2019-12-05 2021-06-05 Sacmi METHOD AND MOLDING APPARATUS

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EP1340610A1 (en) * 2002-02-28 2003-09-03 Matra Venture Composites Method for producing composite parts with locally reduced thickness

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FR2699498B1 (en) * 1992-12-23 1995-03-10 Eurocopter France Blade made of thermoplastic composite, in particular for a faired tail rotor of a helicopter, and its manufacturing process.
US5863365A (en) * 1997-04-30 1999-01-26 Scaled Composites, Inc. Method of manufacturing composite articles
EP1547756A1 (en) * 2003-12-24 2005-06-29 Airbus UK Limited Method of manufacturing aircraft components
WO2007013385A1 (en) * 2005-07-29 2007-02-01 The Doshisha Method for molding fiber-reinforced thermoplastic composite material, intermediate thereof and composite sheet

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EP1340610A1 (en) * 2002-02-28 2003-09-03 Matra Venture Composites Method for producing composite parts with locally reduced thickness

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