Pressure moulding process and related pressure moulding device

Abstract

Pressure moulding process, and related device (100), for manufacturing an article, the process comprising: providing a substrate (70) made of a composite material comprising a first polymeric material and fibres impregnated with said first polymeric material; providing a coating sheet (71); heating said substrate (70) to a temperature of the substrate (70) greater than 160 C.; subsequently, during a first compression step, compressing under pressure the substrate (70) and the coating sheet (71) between a first conformation surface (1) and a second conformation surface (2) for conforming the substrate (70) and the coating sheet (71) and for firmly fixing the substrate (70) and the coating sheet (71) to each other; during a second compression step subsequent to the first compression step, compressing under pressure the substrate (70) and the coating sheet (71) between the first (1) and second conformation surface (2) and injecting a second polymeric material in an injection cavity (3) having an outlet mouth (4) onto the first conformation surface (1), wherein a first face of the substrate (70) opposite to the coating sheet (71) is in contact with the first conformation surface (1); cooling the second polymeric material for firmly fixing the second polymeric material to the first face of the substrate (70), wherein, during the first compression step, a temperature of the first (1) and second conformation surface (2) is less than 120 C.

Claims

1. A pressure moulding process for manufacturing an article, the process comprising: providing a substrate made of a composite material comprising a first polymeric material and fibres impregnated with said first polymeric material; providing a coating sheet; heating said substrate to a temperature of said substrate greater than 160 C.; subsequently, during a first compression step, compressing under pressure said substrate and said coating sheet between a first conformation surface and a second conformation surface for conforming said substrate and said coating sheet and for firmly fixing said substrate and said coating sheet to each other; during a second compression step subsequent to said first compression step, compressing under pressure said substrate and said coating sheet between said first and second conformation surface and injecting a second polymeric material in an injection cavity having an outlet mouth onto said first conformation surface, wherein a first face of said substrate opposite to said coating sheet is in contact with said first conformation surface; cooling said second polymeric material for firmly fixing said second polymeric material to said first face of the substrate, wherein the process comprises positioning at least one portion of said outlet mouth at a first distance from said second conformation surface during said first compression step, and at a second distance from said second conformation surface during said second compression step, said second distance being smaller than said first distance, and wherein a first half-mould having said first conformation surface and a second half-mould having said second conformation surface are movable relative to each other along a movement direction and respectively have a first and a second main body, which at least in part define respectively said first and second conformation surface.

2. The process according to claim 1, wherein a difference between said first and second distance is greater than or equal to 0.5 mm and/or less than or equal to 4 mm.

3. The process according to claim 1, wherein said positioning said at least one portion of said outlet mouth at the second distance comprises, between the first and the second compression step, reciprocally moving said first and second half-mould along the movement direction for arranging them in the second compression step at a smaller distance from each other along said movement direction than in the first compression step, and wherein the process comprises: during the first compression step, keeping a spacer in a first position in which is interposed in contact between said first and second half-mould thrusted against each other, for keeping said at least one portion of said outlet mouth at said first distance from the second conformation surface; between the first and the second compression step, moving said spacer to a second position; and during the second compression step, keeping said spacer in said second position in which leaves free said first and second half-mould, thrusted against each other, for keeping said at least one portion of said outlet mouth at said second distance from the second conformation surface.

4. The process according to claim 1, wherein said positioning said at least one portion of said outlet mouth at the second distance comprises, between the first and the second compression step, moving away said at least one portion of said outlet mouth from said first main body, wherein said first half-mould comprises an insert integral with a portion of said injection cavity comprising said at least one portion of outlet mouth, and wherein the process comprises: during the first compression step, keeping said insert in a respective first position in which said at least one portion of said outlet mouth is at said first distance from the second conformation surface, between the first and the second compression steps, moving said insert to a respective second position; and during the second compression step, keeping said insert in said respective second position in which said at least one portion of said outlet mouth is at said second distance from the second conformation surface.

5. The process according to claim 1, comprising, previously to said first compression step: arranging said substrate at said first conformation surface and positioning a perimetral portion of the substrate between a first abutment surface of an abutment element and an abutment face of a first abutment support; arranging said coating sheet at a second face of said substrate opposite to the first face, and positioning a perimetral portion of the coating sheet on a second abutment surface of said abutment element, wherein, when said first and second half-mould are thrusted against each other, said perimetral portion of the coating sheet is interposed between said second abutment surface and an abutment face of a second abutment support, wherein, before said second compression step, the process comprises: moving along a cutting direction said abutment element with respect to the first main body for cutting said substrate along a first cutting line through cooperation between an edge of said first abutment surface and a perimetral edge of said first conformation surface, and moving said second abutment support with respect to the abutment element for cutting said coating sheet along a second cutting line through cooperation between the abutment element and the second abutment support, and wherein the first cutting line is more proximal to said edge of the first conformation surface than said second cutting line.

6. The process according to claim 1, wherein said temperature of said substrate is greater than or equal to 170 C. and/or less than or equal to 250 C., wherein the process comprises, previously to the first compression step, heating said coating sheet to a temperature of said coating sheet greater than or equal to 120 C. and less than or equal to 220 C., and wherein during said first and/or second compression step, said temperature of said first and second conformation surfaces is less than or equal to 110 C. and greater than or equal to 30 C.

7. The process according to claim 1, wherein said first polymeric material is selected from the group: polyolefins, polyesters, polyamides, polyurethanes, or mixtures thereof, wherein said fibres are selected from: natural fibres, polymeric fibres, glass fibres, carbon fibres, wherein said composite material is NFPP having a weight per unit area greater than or equal to 300 g/m2 and/or less than or equal to 4000 g/m2, wherein said coating sheet has continuous structure and comprises a first sheet layer having homogeneous structure entirely made of thermoplastic polyolefin and a second layer made of a polymeric foam, and wherein said second layer has a thickness greater than or equal to 0.5 mm and/or less than or equal to 5 mm and a density greater than or equal to 20 kg/m3 and/or less than or equal to 300 kg/m3.

8. A pressure moulding device comprising: a first half-mould having a first conformation surface and a second half-mould having a second conformation surface, said first half-mould comprising an injection cavity having an outlet mouth onto said first conformation surface, wherein said first and second half-mould have a first and a second main body respectively, which at least partly define said first and second conformation surface respectively; an injection unit in fluid communication with said injection cavity, and a spacer movable between: a first position in which is interposed in contact between said first and second half-mould, when thrusted against each other, for keeping at least one portion of said outlet mouth at a first distance from the second conformation surface, and a second position in which leaves free said first and second half-mould, when thrusted against each other, for keeping said at least one portion of said outlet mouth at a second distance from the second conformation surface, said second distance being smaller than said first distance.

9. The device according to claim 8, wherein said first half-mould comprises an insert integral with a portion of said injection cavity comprising a respective portion of said outlet mouth, and movable with respect to said first main body between: a respective first position in which said respective portion of said outlet mouth is at a respective first distance from the second conformation surface, and a respective second position in which said respective portion of said outlet mouth is at a respective second distance from the second conformation surface said respective second distance being smaller than said respective first distance.

10. The device according to claim 8, comprising an abutment element which defines a first and a second abutment surface, wherein said first and second half-mould comprise respectively a first and a second abutment support, having a respective abutment face, wherein said first abutment surface faces the abutment face of the first abutment support and said second abutment surface faces the abutment face of the second abutment support, and wherein said first and second abutment surface and said respective abutment faces are external to said first and second conformation surfaces.

11. A pressure moulding device comprising: a first half-mould having a first conformation surface and a second half-mould having a second conformation surface, said first half-mould comprising an injection cavity having an outlet mouth onto said first conformation surface, wherein said first and second half-mould have a first and a second main body respectively, which at least partly define said first and second conformation surface respectively; an injection unit in fluid communication with said injection cavity, wherein said first half-mould comprises an insert integral with a portion of said injection cavity comprising a respective portion of said outlet mouth, and movable with respect to said first main body between: a respective first position in which said respective portion of said outlet mouth is at a respective first distance from the second conformation surface, and a respective second position in which said respective portion of said outlet mouth is at a respective second distance from the second conformation surface, said respective second distance being smaller than said respective first distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective, schematic and partial view of a moulding device according to one embodiment of the present invention;

(2) FIGS. 2-4 schematically show subsequent steps of one example of moulding process according to the present invention;

(3) FIG. 5 shows a perspective, schematic and partial view of the moulding device of FIG. 1 in a step of the process according to the present invention;

(4) FIG. 6 schematically and partially shows a sectional view of one embodiment of the moulding device according to the present invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

(5) The features and advantages of the present invention will be further clarified by the following detailed description of some embodiments, presented by way of non-limiting example of the present invention, with reference to the attached figures.

(6) In the figures, the reference number 100 indicates a pressure moulding device according to the present invention, which can be used for example for the moulding of articles for motor-vehicles, such as for example interior trims.

(7) The moulding device 100 comprises a mould formed by a first half-mould 91 having a first conformation surface 1 and a second half-mould 92 having a second conformation surface 2 (visible in FIG. 3). Typically, the first 91 and the second half-mould 92 have respectively a first 101 and a second main body 102 which at least partially define respectively the first 1 and the second conformation surface 2.

(8) Typically, the moulding device 100 also comprises a movement system of the two half-moulds 91 and 92 in order to open/close the mould, which is not shown as for example of known type. The first 91 and the second half-mould 92 are exemplarily mutually movable along the (e.g., vertical) movement direction 400.

(9) The first half-mould 91 also comprises an injection cavity 3 having an outlet mouth 4 on the first conformation surface 1.

(10) The injection cavity 3 (only schematically shown in the figures) can consist of sub-portions, each sub-portion being an interconnected structure (i.e., each part is in fluid communication with every other part), for example forming a reticular structure. In the example of FIG. 1, a first 3 and a second sub-portion 3 of the injection cavity 3 are shown.

(11) Exemplarily (for illustrative purposes) the first sub-portion 3 has the outlet mouth entirely on a portion of the first conformation surface 1 having development transversal to the movement direction 400 (i.e., in the shown example, substantially horizontal development), and the second sub-portion 3 has a part of the respective outlet mouth on a portion of the first conformation surface 1 having development parallel to the movement direction 400 (i.e., in the shown example, on a wall with substantially vertical development). One or more sub-portions of the injection cavity can have the respective outlet mouth having only vertical development (not shown).

(12) Exemplarily the outlet mouth 4 is peripherally surrounded by a sealing element 10 (schematically and not to scale shown in FIG. 6) protruding from the first conformation surface 1. For example, every overall outlet mouth of each sub-portion of the injection cavity is completely surrounded by a continuous element 10 in slight relief (e.g., a few tenths of a millimetre) with respect to the rest of the conformation surface. In FIG. 6 the relief is shown in a purely schematic and accentuated way for illustrative purposes.

(13) In one embodiment, the outlet mouth is (in whole or in part) without the sealing element. In other words, the perimeter of the outlet mouth 4 is at the same level as the rest of the first conformation surface.

(14) Exemplarily the first sub-portion 3 of the injection cavity 3 and the respective outlet mouth 4 (and, if present, the respective sealing element 10) are integral with the first main body 101.

(15) Exemplarily the first half-mould 91 comprises one or more inserts 20 movable with respect to the main body 101. In the example of FIG. 1 the movable insert 20 is integral with the second sub-portion 3 of the injection cavity 3.

(16) FIG. 6 schematically shows an insert 20, movable with respect to the first main body 101, exemplarily along a direction 401 perpendicular to the local development of the first conformation surface (horizontal in the example). The insert 20 is movable between a first position (shown in FIG. 6) in which keeps the respective outlet mouth 4 (and also the respective sealing element 10) at a first distance from the second conformation surface 2, and a second position (not shown) in which keeps the outlet mouth 4 at a second distance from the second conformation surface 2, which is smaller than the first distance (i.e., it is slightly more to the left than shown in FIG. 6). Exemplarily the moulding device 100 comprises a movement system (not shown) of the insert 20, for example of the mechanical type (e.g., a plate sliding along a direction parallel to the movement direction 400 which abuts against the bottom surface of the insert 20 and determines its movement along the direction 401) or electrical type (e.g., a linear electric actuator), herein not further described as for example of known type.

(17) The present invention also contemplates solutions, not shown, in which one or more inserts are movable with respect to the first main body along any direction, for example parallel to the movement direction 400 of the two half-moulds.

(18) With reference to FIG. 1, exemplarily the moulding device 100 also comprises four spacers 6, exemplarily plate-like shaped and having a thickness (along the direction 400) equal for example to about 2 mm. Exemplarily the spacers 6 are movable between a first position (shown in FIG. 1) in which they are interposed in contact between the first 91 and the second half-mould 92, when thrusted against each other (not shown), and a second position (shown in FIG. 5) in which they leave free the first 91 and the second half-mould 92, when thrusted against each other. Exemplarily the moulding device 100 comprises a (respective) movement member (not shown) of the spacers 6, for example of mechanical or electrical type (e.g., a hydraulic or pneumatic cylinder, or a linear electric actuator).

(19) Therefore, with the spacers 6 in the respective second position, the distance between the conformation surfaces 1 and 2 taken along the thickness of the spacers is smaller than when the spacers 6 are in the respective first position.

(20) Exemplarily the moulding device 100 also comprises an abutment element 7 which defines a first 11 and a second abutment surface 12 (exemplarily shown in section in FIGS. 2-4).

(21) Exemplarily the first 91 and the second half-mould 92 respectively comprise also a first 81 and a second abutment support 82 having a respective abutment face 83, 83 (FIGS. 2-4).

(22) Exemplarily the first 81 and second abutment support 82 are integral (e.g., in single piece) respectively with the first 101 and the second main body 102. Alternatively, the first 81 and the second abutment support 82 can be (physically) distinguished from respectively the first 101 and second main body 102, and for example can be connected to a respective movement system of mechanical type (e.g., a respective cylinder) or electrical type (e.g., a respective linear electric actuator) which allows their independent movement along a respective movement direction parallel to the movement direction 400.

(23) As shown in FIGS. 3-4, exemplarily the first abutment surface 11 faces the abutment face 83 of the first abutment support 81 and the second abutment surface 12 faces the abutment face 83 of the second abutment support 82.

(24) The first 11 and second abutment surface 12 and the respective abutment faces 83 and 83 are external to the two conformation surfaces 1 and 2.

(25) The moulding device 100 comprises also an injection unit 5 in fluid communication with the injection cavity 3. The injection unit 5 exemplarily comprises (not shown) a helical extruder equipped with a hopper for feeding the polymeric material to be injected, a heating system of the extruder, and an injection cylinder. This injection cylinder is connected (e.g., by a fluid line 201) to a hot chamber 15 located for example in the first main body 101 and which, in turn, is in fluid communication with the injection cavity 3 (e.g., with specific injection points of the injection cavity, for example via a duct system 200). For example, the injection of the polymeric material from the chamber 15 to the injection cavity 3 is controlled by a plurality of valve elements (e.g., shutters, placed along each duct 200).

(26) With reference to FIGS. 1-6, some steps of an example of pressure moulding process according to the present invention are schematically shown, which can be implemented with the device 100 described above.

(27) First of all, the moulding process comprises providing: a substrate 70 made of a composite material, for example NFPP comprising polypropylene as first thermoplastic polymeric material, and natural fibers (e.g., cotton) impregnated with the first polymeric material; and a coating sheet 71, for example having a homogeneous and continuous structure and exemplarily made of thermoplastic polyolefin (TPO).

(28) Optionally, it is possible to provide an adhesive layer (e.g., a heat-activable adhesive or a pressure sensitive adhesive) between the substrate 70 and the coating sheet 71.

(29) Subsequently, the process comprises heating the substrate 70 (and optionally also the coating sheet 71) to a temperature for example of about 200 C. (and respectively about 180 C.), for example by hot plates and/or by infrared exposure.

(30) At the end of the heating, the substrate 70 is positioned on the first conformation surface 1, so that a perimetral portion 70 of the substrate 70 is located between the first abutment surface 11 and the abutment face 83 of the first abutment support 81. The coating sheet 71 is exemplarily positioned superimposed on the substrate 70, so that a perimetral portion 71 of the coating sheet 70 is positioned on the second abutment surface 12. Typically (as shown in FIG. 3), when the first 91 and the second half-mould 92 are approaching and/or are thrusted against each other, the perimetral portion 71 of the coating sheet 71 is (partially) interposed between the second abutment surface 12 and the abutment face 83 of the second abutment support 82.

(31) Exemplarily (as shown in FIG. 3-4) during the mutual approach of the first 91 and second half-mould 92 (e.g., by lowering of the second half-mold) along the movement direction 400, the abutment element 7 is lowered with respect to the first main body 101 along a, exemplarily vertical, cutting direction 402 and the second abutment support 82 is lowered with respect to the abutment element 7. The movement of the abutment element 7 allows cutting the substrate 70 along a first cutting direction 301 by cooperation between an edge 50 of the first abutment surface 11 and a perimetral edge 51 of the first conformation surface 1. The movement of the second abutment support 82 allows cutting the coating sheet 71 along a second cutting line 302 by cooperation between the abutment element 7 and a respective edge of the second abutment support 82.

(32) Exemplarily the first cutting line 301 is more proximal to the perimetral edge 51 of the first conformation surface 1 than the second cutting line 302. The first cutting line 301 exemplarily follows (at least in part) the perimeter of the first conformation surface 1.

(33) In one alternative not shown embodiment, in which the first and the second abutment supports are distinct from the first and second main body, it is possible to firstly thrust the two half-moulds against each other and subsequently moving along the respective movement direction (e.g., parallel to the movement direction 400) also the first (and second) abutment support, by activation of the (respective) movement system (e.g., mechanical cylinders).

(34) In one alternative not shown embodiment, one or both of the aforesaid cuts are performed, alternatively to the cooperation between two sharp edges as described above, by the pression of a respective blade against a respective abutment surface.

(35) In one alternative not shown embodiment, when the two half-moulds are thrusted against each other, the perimetral cut of the substrate and of the coating sheet takes place along a same cutting line.

(36) Exemplarily during all the steps of the moulding process described above and below, the two main bodies 101 and 102 of the half-moulds 91 and 92, including the first 1 and the second conformation surface 2, are thermostated (at a temperature for example of about 60 C. in the case of TPO, or of about 100-120 C. in case the coating sheet is made of polypropylene and has a thickness in the order of a few tenths of millimetre), for example by a cooling system comprising one or more cooling ducts that entirely pass through the respective main body and inside of which a cooling fluid flows (e.g., air or water).

(37) The process comprises a first compression step, in which the first 91 and second half-mould 92 are thrusted against each other, and the substrate 70 and the coating sheet 71 are compressed under pressure between the first 1 and the second conformation surface 2 for forming and firmly fixing to each other the substrate 70 and the coating sheet 71.

(38) Exemplarily during the first compression phase, the spacers 6 are kept in the first position and the one or more inserts 20 are kept in the respective first position.

(39) At the end of the first compression step, the second half-mould 92 is slightly raised and the spacers 6 are moved in the second position (schematically shown in FIG. 5). In this way, when the second half-mould 92 is thrusted again against the first half-mould 91, the sub-portion of the outlet mouth 4 having horizontal development (and more generally having development substantially transversal to the horizontal plane, for example with slope between 0 and 45) is in a position closer to the second conformation surface 2 than that in the first step.

(40) Furthermore, the one or more inserts 20 are moved in the respective second position. In this way, the sub-portion of the outlet mouth 4 having vertical development (and more generally having development substantially vertical, for example with slope between 450 and 90 with respect to the horizontal) is in a position closer to the second conformation surface 2 than that in the first step.

(41) With the spacers 6 and the one or more inserts 20 in the respective second position, the second half-mould 92 is again lowered and thrusted against the first half-mould 91 to carry out a second compression step in which the substrate 70 and the coating sheet 71 are compressed between the first 1 and the second conformation surface 2 to a generally greater extent with respect to the first compression step.

(42) In this situation, the perimeter of the outlet mouth 4 (i.e., the transition area from a solid of the first conformation surface to a void of the outlet mouth) and, if present, the sealing element 10, penetrates in the substrate 70 to a greater extent than in the first compression step. Typically, the substrate 70 is sufficiently soft to accommodate the perimeter of the outlet mouth 4 and the eventual sealing element without being damaged.

(43) During the second compression step, a second molten polymeric material, for example polypropylene, is injected (through the injection unit 5) into the injection cavity 3 up to contact the face of the substrate 70 opposite to the coating sheet 71.

(44) Finally, the injected second polymeric material is cooled for firmly fixing itself to the substrate 70 and thus creating rigid functional structures, such as reinforcing/stiffening ribs or members to facilitate the assembly of the article on the vehicle.

(45) Once the cooling of the second polymeric material is ended, it is possible to extract the finished article from the moulding device 100.