Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/16—Making multilayered or multicoloured articles
  • B29C45/1676—Making multilayered or multicoloured articles using a soft material and a rigid material, e.g. making articles with a sealing part
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/16—Making multilayered or multicoloured articles
  • B29C45/1642—Making multilayered or multicoloured articles having a "sandwich" structure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C2045/0093—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor of articles provided with an attaching element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/16—Making multilayered or multicoloured articles
  • B29C45/1642—Making multilayered or multicoloured articles having a "sandwich" structure
  • B29C2045/1651—Independent injection runners or nozzles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/26—Moulds
  • B29C45/27—Sprue channels ; Runner channels or runner nozzles
  • B29C45/2756—Cold runner channels
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/17—Component parts, details or accessories; Auxiliary operations
  • B29C45/26—Moulds
  • B29C45/27—Sprue channels ; Runner channels or runner nozzles
  • B29C45/30—Flow control means disposed within the sprue channel, e.g. "torpedo" construction
• • 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
  • B29K2101/00—Use of unspecified macromolecular compounds as moulding material
  • B29K2101/12—Thermoplastic materials
• • 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
  • B29K2221/00—Use of unspecified rubbers as reinforcement
  • B29K2221/003—Thermoplastic elastomers

Definitions

• the present invention relates to a method of manufacturing an injected part made of at least two thermoplastic materials having different physical characteristics, in which is injected simultaneously or sequentially in a mold cavity corresponding to said workpiece at least a first thermoplastic material to constitute an outer skin of the part and at least a second thermoplastic material to form a core of the part surrounded by said skin, these materials being injected by separate injection nozzles with independent control.
• thermoplastic materials having different physical characteristics, these thermoplastic materials comprising at least a first elastomeric thermoplastic material to form an outer skin of the part and at least one second thermoplastic filling material to constitute a heart of the room surrounded by said skin, according to the method above.
• the so-called sandwich injection technique consists in injecting into a mold simultaneously or sequentially two polymers one of which forms the outer layer called skin and the other the central part called the core of a composite part.
• the polymers may be in a solid form or an expanded form or in a combined form.
• Polymers can be expanded by the addition of a blowing agent or an inert gas or by the combined use of these two types of components.
• the sandwich injection process is usually carried out by means of bi-injection presses.
• the injection units are equipped with a distributor block provided with supply channels.
• the injection nozzle may comprise a single channel which transfers the polymers through the same channel which is then equipped with a three-way valve allowing the injection sequences of a composite part.
• the injection nozzle may also comprise two channels whose opening and closing can be managed by a hydraulic control (so-called hydraulic process), which allows a great freedom of maneuver in the settings, or whose opening and closing can be managed by using the respective injection pressures of the two units (so-called pressure process).
• the injection can be sequential or simultaneous.
• the skin material For the production of thin pieces of relatively large area, such as for example carpets or trim parts for motor vehicles, the skin material must be an elastomeric thermoplastic having specific physical characteristics with regard to appearance, consistency, density, strength, adhesion, flexibility or rigidity, etc. that make this material is expensive and causes an increase in the final part.
• the requirements for this type of part may be such that the final product becomes complex and should, for example, have areas with distinct physical characteristics, such as very soft areas and rigid or semi-rigid areas, areas with good adhesion and areas with a smooth surface.
• known injection methods do not lend themselves to the production of these parts which are both too expensive and do not have the required physical characteristics.
• the publication WO 99/51416 attempts to provide a solution by proposing a sandwich injection method using two distinct injection nozzles, which open directly into the cavity of a mold at different injection points, located either in the face either in the thickness of the room.
• a sandwich injection method using two distinct injection nozzles, which open directly into the cavity of a mold at different injection points, located either in the face either in the thickness of the room.
• we bet a "full skin” injection which has the major disadvantage of creating on the part of the appearance defects in the form of bright halos at the injection points, which is not acceptable for a finishing piece.
• This injection method also allows the possibility of simultaneously making fasteners integral to the workpiece by means of a movable drawer system inside the mold cavity.
• this technique is complex to implement in a co-injection process, the movement of the drawer generating appearance defects in the skin material of the room. The aesthetic result is therefore more than uncertain, uncontrolled and non-reproducible.
• the present invention proposes to overcome these drawbacks by offering a simple, economical and very flexible injection method which makes it possible to produce relatively economic parts in terms of their manufacture, and meeting the requirements of users both in terms of technical characteristics differentiated according to the areas of the room in question, in terms of surface appearance of high aesthetic quality.
• the injection nozzles are made to open in at least one cold supply channel which is in communication with said cavity, or in two cold channels of water. which are in communication with two distinct areas of said footprint.
• thermoplastics are injected indirectly via this cold supply channel, which makes it possible to avoid all the appearance defects encountered with the known direct injection processes and to achieve ratios. heart / skin much higher than those currently possible.
• Said outer skin may advantageously be made of at least one or more elastomeric thermoplastics having distinct physical characteristics.
• Said second material for forming said core may advantageously comprise at least one or more different thermoplastics having different physical and economic characteristics. Of the said different thermoplastic materials constituting said core, at least one may be expanded.
• Said core may also comprise at least one elastomeric thermoplastic material.
• Said outer skin of the piece may be made during at least a first injection sequence of at least a first elastomeric thermoplastic material. In some cases, said first sequence may be split into several partial subsequences.
• Said outer core of the part is preferably made during at least a second injection sequence of at least a second thermoplastic material.
• a device for implementing this method characterized in that it comprises at least one cold supply channel into which said injection nozzles open, said cold supply channel being in communication with said footprint.
• the device may also comprise a first cold supply channel and a second cold supply channel into which said injection nozzles respectively open, said cold supply channels being in communication with two distinct zones of said cavity, which can advantageously correspond to a process of retro-injection.
• the device may be completed by at least one open or closed flyweight, connected to a restriction of said footprint to optimize the filling of the core material in specific areas of the room.
• an injected part characterized in that it comprises zones having different physical characteristics made by means of said injected thermoplastics.
• FIG. 2 is a schematic and partial view showing a second embodiment of an injection device according to the invention.
• FIG. 3 is a schematic and partial view showing a third embodiment of an injection device according to the invention.
• FIG. 4 is a schematic and partial view showing a fourth embodiment of an injection device according to the invention.
• FIGS. 5A and 5B are diagrammatic views from above and in section of a first part according to the invention.
• FIG. 6 is a schematic view showing an axial section of a second part according to the invention.
• FIGS. 7A and 7B are diagrammatic views from above and in section of a third part according to the invention.
• FIGS. 8A, 8B and 8C are schematic views from above and in cross-section along BB of a fourth part according to the invention.
• FIGS. 9A and 9B are schematic sectional views of a fifth part according to the invention in two positions of use
• FIG. 10 is a schematic and partial view of an alternative embodiment of the injection device of FIG. 1,
• FIGS. 11A and 11B are detailed views of two forms of injection threshold
• FIGS. 12A and 12B are detailed views of the mold corresponding to a fastening clip integrated into an injected part, respectively without and with the use of an open feeder, and
• Figures 13A to 13C are detailed views of a feeder mold closed respectively in three phases of operation.
• the device 10 shown schematically and partially comprises a first injection block 11 and a second injection block 12 each having an injection nozzle respectively 11a and 12a which open into two hot injection channels respectively 11b and 12b.
• the hot injection channels 11b and 12b are equipped with an independent shut-off device 11c and 12c, respectively, which are arranged to stop or let through the thermoplastic material, which is fed by the two injection blocks 11 and 12 and which corresponds to the skin material for one and to the heart matter for the other.
• These hot injection channels 11b and 12b open into a cold feed channel 13 of the thermoplastic materials which is in communication with a cavity 14 for the production of a single piece 15 having a closed skin 16 and a central core 17 completely surrounded by the skin 16. It is said that the filling of the impression 14 takes place in the core in the flow, the core material being injected in the same direction of injection as the skin material.
• the device 10 shown makes it possible to perform a sequenced or simultaneous sandwich injection called co-injection.
• sequenced injection the skin material is first injected and then, before the end of the injection of the volume of skin, the core material is injected to finish the filling of the impression 14.
• the beginning of the injection core material starts before the end of the injection of the skin material to ensure continuity of the material flow and avoid appearance defects.
• simultaneous injection we first inject the skin material, then almost simultaneously, we inject the core material.
• the injection rate of the skin material should be slightly greater than the flow rate of the core material. In both cases, the compaction of the injected materials is carried out on the core material.
• the device 20 shown schematically and partially comprises a first injection block 21 and a second injection block 22 each having an injection nozzle respectively 21a and 22a which open into two hot injection channels respectively 21b and 22b.
• the hot injection channels 21b and 22b are equipped with an independent shutter device 21c and 22c, respectively, which are arranged to stop or let the thermoplastic material which is fed by the two injection blocks 21 and 22 and which corresponds to the skin material for one and to the heart matter for the other.
• These hot injection channels 21b and 22b respectively open into a first cold supply channel 23a and a second cold supply channel 23b of the thermoplastic materials, which are in communication with two distinct zones of a cavity 24 for the purpose of making a simple piece 25 comprising a skin 26 partially surrounding a localized central core 27 or a reinforcement inserted into the cavity 24.
• the device 20 allows a back-injection, during which we begin by injecting the skin material until complete filling of the impression 24, then the heart material is injected locally into the selected area, the core material driving the skin material. In this case, compaction is performed on both materials or on the core material. This method makes it possible to stiffen very locally or to obtain localized zones having specific characteristics.
• FIGs 12A and 12B illustrate the injection of the fastening clip 38 in a cavity 34 closed and an impression 34 communicating with an open weight 39.
• the skin material is trapped in the end regions of the impression 34 and clip 38 preventing the core material from advancing and accessing the center of the fastener clip 38.
• the end zone of the cavity 34 corresponding to the head of the fastening clip 38 communicates with a counterweight 39 opened by a threshold of the submarine type, squash S2 or direct, and by a channel whose volume corresponds substantially to volume of trapped skin.
• These hot injection channels 41b and 42b respectively open into a cold feed channel 43 of the thermoplastics material which is in communication with an impression 44 for the production of a more complex piece 45 comprising a skin 46 surrounding a heart 47
• the impression 44 is connected via a channel equipped with a shutter cylinder 48 to a counterweight said closed weight 49.
• the closed weight 49 has the same function as the simple counterweight 39 of the previous example. . The only difference is that the closed weight 49 is controlled by a jack 48 which closes the arrival of the material when the process requires it.
• FIGS. 13A, 13B and 13C illustrate the various stages of operation of this closed weight 49. During the injection of the skin material, the jack 48 closes the access to the weight 49 (phase 1).
• the ram 48 opens this access to allow the core material 47 to expel the trapped skin material 46 and fill the center of the workpiece (phase 2). Then, the cylinder closes the access again (phase 3).
• This technique makes it possible to optimize the relatively large volume filling zones and also allows the flyweight 49 to be cut directly integrated into the tooling.
• the flyweight 49 may be coupled to the footprint 44 by a threshold of submarine type S1 or squash S2.
• the peculiarity of the method of the invention and the device for implementing this method is related to the fact that the injection of the thenmoplastic materials of skin and heart can be controlled independently in selected areas of the room and is performed indirectly by a cold feed channel that achieves heart / skin ratios much higher than those obtained by current methods.
• the other feature of the method of the invention and the device for implementing this method lies in the simplicity and flexibility of the proposed technical solutions, allowing the use of standard presses.
• the solutions described in devices 10 to 40 implement so-called hot injection channels. This technique is mainly suitable for single-stamped tools, centered with a material feed on the periphery of the part.
• hot runner configurations There are three types of hot runner configurations: separate and superimposed hot runners, separate and side-by-side hot runners, or a common double-feed hot runner.
• the devices 10 to 40 are shown schematically with a common hot block Bc traversed by the two injection channels 11b, 12b; 21b, 22b; 31b, 32b; 41b, 42b, this example not being limiting.
• the device for implementing the method of the invention can also use the so-called cold injection channels technique.
• This technique is particularly suitable for multi-cavity tooling and for small series tools for which the investment in hot blocks would be too important.
• An example is shown schematically and partially in FIG. 10.
• the device 100 comprises two cold injection channels 110b and 120b respectively, commonly called “cores”, fed by two thermoplastic injection blocks (not shown) each having a injection nozzle that corresponds to the material of skin for one and heart matter for the other.
• These cold injection channels 110b and 120b open into a cold feed channel 130 of the thermoplastic materials which is in communication with a footprint 140 for the production of a part.
• the cold feed channel 130 is equipped with a valve 140 arranged to stop or pass the core material from the cold channel 110b.
• the skin material is stopped by the valve 150 and will fill the impression 140.
• the material of injection is injected. heart.
• the pressure exerted by the core material on the slope of the valve 150 will cause its opening and allow the passage of the core material in the cold feed channel 130 and in the footprint 140.
• the restriction R of the channel section supply 130 in the area of the valve 150 optimizes the filling by the heart.
• the stiffening element 61 consists of a central core 62 which occupies part of the length of the wall the thickest of the steering bellows 60 and a fastening clip 63.
• the central core 62 and the fastening clip 63 are surrounded by a skin 64 which is preferably made of an elastomeric thermoplastic material. The technique of the weights optimizes the filling of the core material in the fastening clip 63.
• FIGS. 8A, 8B and 8C illustrate a top view and two sectional views of a park brake console mat 80 for a motor vehicle.
• This belt 80 comprises, for example, a zone 81 corresponding to the park handbrake, an area corresponding to a pocket space 82 and a zone corresponding to electric control buttons 83.
• FIG. 8B in particular represents the cross-sectional view BB of FIG. the control button area 83, which has a skin 83a and a central core 83b.
• FIG. 8C shows a cross-section BB of the belt 80 through the parking brake zone 81.
• a central portion comprises a rigid core 81a and two core elements 81b and 81c disposed on either side of this core 81a, together being surrounded by a skin 81d.
• the different areas have different physical characteristics.
• the appearance, the coloring, the rigidity are varied according to the different zones.
• the skin 83a and 81d form a flexible zone allowing the mobility of the rigid zones 83b, 81a.
• This piece 80 can be obtained using the technique of retro-injection.
• FIGS. 9A and 9B show a carpet 90 or a covering part for a motor vehicle which has fastening clips 91 and a hinge 92 which makes it possible to access a storage compartment or a storage compartment.
• the carpet 90 has a core 90a which extends over the entire surface of the room and a closed skin 90b which completely surrounds the heart 90a. The end zones of the carpet are made with the skin material 90b.
• the fastening clips 91 contain rigid thermoplastic material in their central portion to provide stiffening. A reinforcing member may be included in the fastening clips 91.
• the flyweight technique is used to optimize the filling of the core material in the fastening clips 91.
• the present invention is not limited to the embodiments described, but can be extended to all kinds of embodiments of the injected parts type bimaterial or thermoplastic multi-material, especially thermoplastic elastomer, in a manner obvious to those skilled in the art, without departing from the scope of the present invention. Shapes and physical characteristics can be varied indefinitely according to needs and applications.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Materials For Medical Uses (AREA)

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Related Child Applications (1)

Publications (1)

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Family Cites Families (14)

• 2006
  • 2006-05-29 FR FR0604768A patent/FR2901504B1/fr not_active Expired - Fee Related
• 2007
  • 2007-05-29 WO PCT/FR2007/000887 patent/WO2007138186A2/fr not_active Ceased
  • 2007-05-29 EP EP07765962A patent/EP2026943A2/de not_active Withdrawn
  • 2007-05-29 EP EP11004006.0A patent/EP2371514B1/de not_active Not-in-force

Non-Patent Citations (3)

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