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
  • B29C43/32—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
• • 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
  • B29C70/48—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 in the closed mould, e.g. resin transfer moulding [RTM], e.g. by vacuum
• • 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
  • B29C2043/3618—Forming elements, e.g. mandrels or rams or stampers or pistons or plungers or punching devices plurality of counteracting elements
• • 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

Definitions

• the present invention relates to the technical field of manufacturing plastic parts, especially automotive body parts, by a compression molding process.
• a mold provided with a movable element and a fixed element, the two elements, typically made of steel, forming a molding chamber in the closed position of the mold;
• At least one plastic sheet is placed in the compression mold, typically a "SMC" ("sheet molding compound”) composite material consisting of thermosetting resin, reinforcing fibers, and often fillers and / or catalyst (hardener).
• SMC sheet molding compound
• the press applies a given force which, depending on the projected surface of the part, is felt in pressure in the compressed material.
• Such a press is then used as a means of compressing the plastic material, since the latter requires a high pressure (greater than 30 bars) to cause the material to flow into the molding cavity, to polymerize the material ...
• the pressure in the molding chamber must be much lower. Typically, for these small parts the required pressure is less than 30 bar.
• the pressure required to mold the material in the molding chamber may also depend on the type of material used, not just the size of the piece. Thus, it is possible to mold a large piece in a so-called "low pressure" material or a small piece with a difficult to mold material requiring high pressure.
• the object of the invention is to remedy these drawbacks and to allow the use of the same press for manufacturing plastic parts of all sizes, in particular for making small parts on an "oversized" press, since it was originally intended for produce only large pieces ..
• the invention particularly relates to a compression mold for the manufacture of plastic part, comprising a first element (fixed) and a second element (movable), the two elements forming a molding chamber in the closed position of the mold.
• At least one of the elements is equipped with at least one compression system of the plastic material, the compression system comprising at least one movable compression block capable of moving towards the molding chamber to compress the plastic material therein.
• the compression system within one of the elements (fixed or mobile) of the mold makes it possible to apply a molding pressure on a surface greater than that of the material placed in the mold before compression, in order not to start compressing the material during the closing of the mold, and to avoid that the parameters of implementation degrade the final properties of the material of the piece produced.
• This lower power system than the press also allows to guarantee a more constant molding pressure, especially without peak overload.
• the mobile compression block is movably mounted in a wall of at least one of the elements with a piston-type movement, and the mobile compression block has a surface adapted to constitute a molding surface with the plastic material, when the block mobile compression is pushed into the molding chamber of the mold.
• the mold comprises at least a first compression system implanted in the first element and at least a second compression system implanted in the second element.
• the two blocks of the two compression systems can be vis-à-vis, and able to apply the same pressure on the plastic, when pushed into the molding chamber.
• the two pavers of the two compression systems can be facing each other, and able to simultaneously apply a pressure on the plastic, so as to balance forces on either side of the plastic material in the molding chamber. .
• the two blocks can be controlled by at least one moving means, such as a hydraulic cylinder or an electric worm motor.
• At least one of the elements (2, 3) is adapted to compress the plastic material (MP) in the molding chamber (4).
• the invention also relates to a compression molding process in which a mold according to the invention is used.
• FIG. 1 schematically shows a mold according to a first embodiment of the invention, in the open position (top), closed (in the middle) and then in the compression phase (at the bottom), this mold being adapted to a molding process by compression.
• FIG. 2 schematically shows a mold according to one embodiment of the invention, comprising a single compression system on the side of the fixed element.
• FIG. 3 schematically shows a mold according to one embodiment of the invention, comprising two compression systems.
• Figure 4 illustrates a mold and an implementation for overmolding an insert.
• FIG. 5 illustrates a particular embodiment of the mold according to the invention, in which the mold comprises two compression systems which are not facing each other and which do not have molding surfaces of the same dimensions.
• FIG. 6 illustrates a particular embodiment of the mold according to the invention, in which the mold comprises two compression systems facing each other but which do not have molding surfaces of the same size.
• Figure 1 shows an example of mold (1) according to the invention, for the manufacture of a plastic part (MP) by means of a compression molding, the mold being in position opened.
• the mold (1) comprises a first element (2), fixed, and a second element (3), movable and movable in a closing direction of the mold.
• the two elements (2, 3) form a molding chamber (4) when the mold is closed.
• the molding chamber (4) is equipped with at least one compression system (5) of the plastics material (MP).
• At least one of the elements (2, 3) is equipped with at least one compression system
• This compression system (5) comprises at least one mobile compression block
• This moving block (6) thus makes it possible to apply the required pressure to the plastics material present in the molding chamber (4).
• the movable compression pad (6) is movably mounted in the thickness of one or the other of the elements (2, 3) with a piston-like movement. According to the example of Figure 1, the movable compression pad (6) moves (see arrow) in the closing direction of the mold (1).
• the mobile compression block (6) has a surface (7) adapted to constitute a molding surface with the plastic material (MP), when the mobile compression pad (6) is in contact with the plastic material, that is to say say when the keypad is in the compression position.
• MP plastic material
• the compression system (5) comprises displacement means (8) for the movable compression pad (6). It can be a mechanical means, such as a hydraulic cylinder connected to the mobile compression pad (6) by a rod, or an electric worm motor.
• Such a compression system makes it possible to finely manage the pressure applied to the plastic material. Indeed the local management at the mold of the movement of the block is more accurate than the overall level of the press (item 3 according to the example of Figure 1).
• the mold is adapted to apply a pressure on either side of the plastic material (on the side of the movable element and the side of the fixed element).
• the movable element (3) of the mold can also be used to compress the plastic material (MP) in the molding chamber (4), on the side of the element (3) movable .
• the other side of the plastic material (MP) being pressed by the compression system (5).
• This configuration offers the advantage of providing a more homogeneous pressure in the plastics material (MP), whether the molding is large or small. Indeed, the pressure experienced by the plastic material on its lower and upper surfaces is directly transmitted to them, unlike a conventional mold, in which the pressure received by the surface opposite the movable member undergoes a pressure transmitted through the plastic material. from its opposite surface. This results in a loss of pressure, creating a differential between the top and the bottom of the room.
• the mold (1) comprises two compression systems (5).
• the molding chamber (4) is equipped with at least one first compression system (5) implanted in the first element (1) and at least one second compression system (5) implanted in the second element ( 2).
• the two compression systems (5) may have substantially the same molding surfaces, as shown in Figures 3 and 4. But as illustrated in Figures 5 and 6, the molding surfaces may have different dimensions.
• the two compression systems (5) can be positioned vis-a-vis (FIGS. 3, 4 and 6) or offset relative to one another (FIG. 5).
• the two compression systems (5) are controlled by at least one moving means (8), such as hydraulic cylinders or an electric worm motor.
• the movable pavers (6) represent most of the finished surface of the piece (high and low) resulting from the molding. This area is calculated according to the loading plan and the recovery rate of the latter.
• the two moving blocks (6) of the two compression systems (5) are facing each other, and they are able to apply the same pressure to the plastics material (MP) when they are pushed into the molding chamber (4).
• the two blocks (6) of the two compression systems (5) are vis-à-vis, and able to simultaneously apply a pressure on the plastic material (MP), so as to balance forces of both sides. other of the plastics material (4).
• Such a compression system allows to finely manage the pressure applied to the plastic material, and to apply an identical pressure on both sides of the plastic material (MP).
• the mold according to the invention can be used for the manufacture of composite parts comprising an insert, by allowing the overmolding of an insert (9) as illustrated in FIG. 4.
• the insert (9) is placed in a compression mold between two sheets of plastic material, typically a composite material called "SMC". Then we close the mold. Then, the press is used to transmit a molding pressure to the plastic material above the insert (on the press side). Then the insert (9) transmits the pressure to the plastic material located under the insert (the opposite side to the insert).
• SMC composite material
• the mold (1) preferably comprises two compression systems vis-à-vis ( Figure 4). These make it possible to apply a simultaneous and balanced pressure on the two vertical faces of the insert to guarantee a thickness chosen for the finished part.
• the mold (1) preferably comprises a system for holding the insert (5) in the mold (1).
• the holding system is a system also ensuring the sealing of the molding chamber (4), preventing the plastic material (MP) from flowing out of the molding chamber (4) of the insert (9) .
• the invention also relates to a compression molding method using a mold (1) according to the invention.
• the method may comprise at least the following steps:
• the plastic material (MP) is positioned on the punch (2);
• the press (3) closes the mold (1) and is positioned in position 0 (thickness of the finished part);
• the two displacement means (8) of the compression systems (5) are controlled simultaneously and the blocks (6) apply a pressure to flow the plastic material (MP);
• the mold (1) being at a temperature between 145 ° C and 160 ° C, the plastic (MP) polymerizes and baked according to its technical characteristics; Both moving means (8) are recalled;

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

Applications Claiming Priority (2)

Publications (1)

Family

ID=51659904

Family Applications (1)

Country Status (3)

Family Cites Families (7)

• 2014
  • 2014-08-01 FR FR1457548A patent/FR3024387B1/fr not_active Expired - Fee Related
• 2015
  • 2015-07-24 EP EP15753126.0A patent/EP3174697A2/de not_active Withdrawn
  • 2015-07-24 WO PCT/FR2015/052061 patent/WO2016016559A2/fr not_active Ceased

Non-Patent Citations (1)

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