DEVICE AND METHOD FOR INJECTION MOLDING OF COMPOSITE MATERIALS COMPRISING AT LEAST ONE INSERTED LAMINATE

Abstract

The present invention relates to a device for injection molding of a composite material comprising at least one laminate (1). The device comprises a mold (2) including a plurality of mold portions (3, 4), each heaving a first side (5, 6) defining a molding surface. At least one of the mold portions (3, 4) is movable such that the mold (2) is movable between an open state and a closed state. One or more retaining arms with the gripper for contacting the laminate are also comprised in the device according to the present invention. Thereby, the retaining arm (7, 7, 8, and 8) is arranged such that it is movable between a retracted position and an extended position. The present invention further relates to an according method for injection molding of a composite material comprising at least one laminate.

Claims

1. A device for injection molding of a composite material comprising at least one laminate, the device comprising: a) a mold including: a plurality of mold portions, each having a first side defining a molding surface, and where at least one of the mold portions is movable relative to at least one other of the mold portions, such that the mold is movable between an open state and a closed state in which the molding surfaces of the mold portions cooperate to define a mold cavity; b) one or more retaining arms with a gripper having a front end surface for contacting the laminate and whereby the retaining arm is arranged such that it is movable between a retracted position and an extended position, wherein the front end surface is configured to receive overmolding material.

2. The device of claim 1, where at least one of the retaining arm(s) is slidably coupled to the respective mold portion.

3. The device of claim 1, where at least one of the retaining arm(s) includes at least one shaft that is coupled to the gripper and is slidably received by the respective mold portion.

4-6. (canceled)

7. The device of claim 1, comprising at least two retaining arms, whereby a first retaining arm is movably coupled to a first mold portion, and a second retaining arm is movably coupled to a second mold portion, such that when the mold is in the closed state, the gripper of the first retaining arm opposes the gripper of the second retaining arm.

8. (canceled)

9. The device of claim 1, where the mold comprises at least one injection gate, in particular a plurality of injection gates, and further in particular at least one of the mold portions comprises an injection gate.

10. The device of claim 1, whereby the retaining arms are individually actuated, in particular are actuated such that at least one retaining arm is capable of performing a multi-level stroke, the retaining arms being actuated by at least one drive chosen from the group consisting of: hydraulic drive, pneumatic drive or electromechanical linear actuator.

11. The device of claim 10, whereby the retaining arms are actuated by at least one hydraulic drive, in particular by two hydraulic drives such that the retaining arms are capable of performing a two-level stroke.

12. A method for injection molding of a composite material comprising: placing a laminate relative to a plurality of mold portions of a mold, where: at least one of the mold portions is movable relative to at least one other of the mold portions such that the mold is movable between an open state and a closed state in which the molding surfaces of the mold portions cooperate to define a mold cavity; and the placing the laminate is such that, when the mold is in the closed state, the laminate is at least partially disposed within the mold cavity; and moving at least one gripper that is movably coupled to a first side of a respective one of the mold portions into contact with the laminate by moving the gripper between a retracted position and an extended position, wherein in the extended position the gripper is further from the molding surface of the respective mold portion than when in the retracted position, contacting the laminate with a front end surface of the gripper, wherein the front end surface has serrations, chamfers or is traversed with furrows; injecting the mold cavity with an overmolding material into the mold cavity and sequentially moving the grippers from the extended position to the retracted position as the overmolding material reaches the grippers or after the overmolding material is in the serrations, chamfers or furrows.

13. The method of claim 12, comprising applying a force in essentially opposed directions to the laminate inside the mold.

14. The method of claim 12, where the overmolding material comprises a thermoplastic material.

15. The method of claim 12, where the overmolding material comprises a plurality of fibers.

16. The method of claim 12, comprising moving the at least one gripper out of contact with the laminate to allow overmolding material to flow between the gripper and the laminate.

17. (canceled)

18. The device of claim 1, further wherein the front end surface has serrations, chamfers or is traversed with furrows, and wherein the said serrations, chamfers or furrows are adapted to allow an overmolding material to flow through during an injection molding procedure.

19. The device of claim 18, further comprising a drive configured to retract the grippers when the overmolding material is in the serrations, chamfers or furrows.

20. A device for injection molding of a composite material comprising at least one laminate, the device comprising: a) a mold including: a plurality of mold portions, each having a first side defining a molding surface, and where at least one of the mold portions is movable relative to at least one other of the mold portions, such that the mold is movable between an open state and a closed state in which the molding surfaces of the mold portions cooperate to define a mold cavity; b) one or more retaining arms with a gripper for contacting the laminate and whereby the retaining arm is arranged such that it is movable between a retracted position and an extended position; and c) a drive configured to syncrhronize moving each of the retaining arms from the extended position to the retracted position as injected overmolding material reaches the retaining arm or after the overmolding material is in serrations, chamfers or furrows in a front end surface of the gripper.

21. The device of claim 20, wherein the drive is configured to sequentially retract the grippers as the overmolding material reaches the place where the grippers contact the laminate.

Description

[0055] In the following, the present invention shall be illustrated by means of particular examples and schematical illustrations, without being restricted thereto though. For the sake of understanding analogous elements have been provided with same references number in the different schematical drawings.

[0056] The drawings show:

[0057] FIG. 1a Schematically mold for a device according to the present invention;

[0058] FIG. 1b The mold of FIG. 1a with the retaining arms in an extended position;

[0059] FIG. 1c The mold of FIG. 1b with one retaining arm further extended by an additional stroke;

[0060] FIG. 1d A closing step of the mold of FIG. 1a;

[0061] FIG. 1e A further closing step of the said mold;

[0062] FIG. 1f The mold being closed the additional stroke still further extended;

[0063] FIG. 1g The mold closed and ready for overmolding;

[0064] FIG. 1h The closed mold with the overmold injected;

[0065] FIG. 2a-2d Variation of the overmolding of a laminate;

[0066] FIG. 3a Alternative step-up for a mold of a device according to the present invention;

[0067] FIG. 3b The same mold of FIG. 3a with the grippers engaged;

[0068] FIG. 3c The same mold enclosed position and with the overmold injected; and

[0069] FIG. 4a Detail representation of a gripper in a particular embodiment.

[0070] FIG. 1a depicts a mold for a device according to the present invention in its most basic implementation. The mold 2 comprises a plurality of mold portions 3, 4. This mold portions 3, 4 may be fabricated out of a suitable material with standing the wear and temperatures in the injection-molding device, such as for examples steel, alloys or aluminum. Each mold portion 3, 4 is arranged such that it faces the other mold portion 3, 4. A first mold portion 3 is set up such as to form a cavity and has a first side 5 forming a molding surface. The second mold 4 is constructed such that it is essentially complementary to the first mold portion 3 and has also a first side 6 defining a molding surface which bulges essentially into cavity formed by the first side 5 of the first mold portion 3. The two mold portions 3, 4 are movable relative to each other. This is most commonly achieved by a hydraulically machine, but also electric or mechanical ones are frequently used in the art. The mold portions 3, 4 might comprise further injection gates (not shown) and might be equipped with further electronics, such as a preheating system, all depending on the nature of the composite material intended for production. In the present shown embodiment, the first mold portion is designed as the cavity mold portion 3 the second mold portion 4 is designed as a core mold portion 4. Further in the present embodiment, to each mold portion 3,4 a pair of retaining arms 7,7,8,8 is attributed ending each in a gripper 9,10 and each being actuated by a drive 14,13. For the sake of the present example, the retaining arms 7,7 of the cavity mold portion 3 are arranged in parallel and such that they end in a gripper 9 and adapted at moving the said gripper 9 into an extended position. The position picked in the FIG. 1a for both mold portions 3, 4 is the retracted position. For this end, the retaining arms 7, 7, 8, 8 might be fit in a suitable bearing (not explicitly shown) in the respective mold portion 3, 4. Further it is evident from the FIG. of 1a, that the grippers 9, 10 have their own surfaces 11, 12, which form part of the mold surfaces defined by the first sides 5, 6 of the mold portions 3, 4. The cavity side surface 11 of the gripper 9 of the cavity mold portion 3 is concave and flush with the molding surface 5 of the cavity mold portion 3. Analogously, the core gripper surface 12 is convexly shaped and essentially follows the radius of the molding surface 6 of the core mold portion 4 and is essentially complementary to the cavity portion on the opposite side. The placement of the unidirectional fiber enriched compound 1 is shown for illustrative purposes in the middle between the two elements.

[0071] FIG. 1b shows the same mold to where the retaining arms 7, 7, 8, 8 are in the extended position and thereby the gripper surfaces 11, 10 of the gripper 9, 10 are making contact with the laminate 1. This movement has been achieved by a first stroke enabled by actuators 13, 14 which maybe linear electromechanical, pneumatic or hydraulic actuators.

[0072] To establish full contact with the laminate in a particular embodiment of the present invention shown in FIG. 1c the actuator 13 of the core mold portion is adapted to apply a further second stroke 15,15. This is shown only illustrative purposes as being on the core side, though it can equally well be arranged on the cavity side or on both sides. The grippers 9, 10 now make contact with each other.

[0073] FIG. 1d illustrates the process of the beginning closure of the mold by moving the mold portions 3, 4 towards each other in a linear closing movement A, B. This movement is only shown for illustrative reasons as a linear movement of both the mold portions 3, 4. Most commonly there is only one mold portion being moved towards the other. At the same time the retaining arm and the gripper 9 of the cavity mold portion 3 is being retracted by engagement of the cavity mold portion actuator 14. The stroke 15, 15 and the extension 8, 8 of the retaining arms 8, 8 of the core mold portion 4 are still fully extended at this state.

[0074] FIG. 1b shows the retaining arms of the core mold portion 4 now equally being retracted into the retracted position, whereby the gripper 9, of the cavity mold portion 3 is already in its full retracted position and essentially flush with the molding surface of the mold portion cavity 3. This ends up in FIG. 1f, where the mold portion 3, 4 are fully closed and the mold cavity 16 is thus defined, but the retaining arms 8, 8 are still extended by the additional stroke 15, 15 and extend into mold cavity 16. The gripper surfaces 11, 12 contact each other to retain the laminate in place. FIG. 1g shows how the further stroke is removed the mold portions 3, 4 still closed and the mold cavity 16 formed. This step can be the starting point of the injection of the overmold or it can already be performed synchronically with the injection of the overmold or it can already be performed synchronically with the injection of the overmold. The overmold injection is shown in FIG. 1h, where the laminate and the overmold 17 both fill the mold cavity.

[0075] As it becomes easily evident to a person skilled in the art based on the description of FIGS. 1a-1f, the mold portions, the geometry of the mold cavity and mold surfaces formed can be easily adapted to suit multitude of possible composite material forms. Further, the inclusion of either a further stroke on one or the other of a pair of retaining arms can further allow adaptions of the resulting position of the laminate in the composite material. This is shown exemplarily in FIGS. 2a-2d, where the laminate 1 takes a different position inside the composite material and is either exposed at a side of the overmold 17, as shown in FIG. 2a or 2b or fully encapsulated in the overmold as shown in FIG. 2c. FIG. 2d shows a particular embodiment, where a plurality of laminates is separated by a layer of overmold.

[0076] For the production of even more complex forms the mold 2 can be adapted with arrangements and the required retaining arms to suit such geometry.

[0077] FIG. 3a shows a particular embodiment where a composite material comprising a multitude of laminates 1, 1, and 1 is to be produced. The respective mold portion 3, 4 is comprised a multitude of retaining arms 7, 7, 7, 8, 8, 8, 8. The mold portion on the left is constructed as a cavity mold portion 3 and comes equipped with three retaining arms 7, 7, 7, 7 each of them ending in a differently shaped gripper 9, 9, 9 with an alternative gripper surface 11, 11, 11. Still these gripper surfaces 11, 11, 11 are made such as to be essentially flush with the mold surface 5 of the cavity mold portion 3. For the sake of simplicity, the retaining arms 7, 7, 7 are shown as being actuated by a single actuator 14. In fact, each of the different retaining arms 7, 7, and 7 can be equipped with an individual actuator. Even further, each retaining arm 7, 7, 7 can be actuated by a multitude of actuators by itself, for instants than when a multiple stroke is wished or required.

[0078] The arrangement is analogous in the core mold portion 4. There four retaining arms 8, 8, 8 and 8 each and in an individually shaped gripper 10, 10, 10, 10 with each and building an individual gripper surface 12, 12, 12, 12. Analogously, each of the retaining arms 8, 8, 8, 8 are shown as being actuated by a single actuator 13, which has already explained for the cavity mold portion 3 can be replaced by a multitude of actuators for each retaining arm.

[0079] FIG. 3b shows the retaining arms now being fully extended and contacting the laminate of the grippers 9, 9, 9, 10, 10, 10, 10. This has been achieved by extending the retaining arms by one stroke from the actuators 13, 14.

[0080] FIG. 3c shows the fully closed mold and the retaining arms now for both mold portions 3, 4 being fully retracted. The mold cavity has been formed and the overmold 17 is injected such that the complex shape with partial laminate reinforcement has been produced.

[0081] The materials used in compass as a laminate a material that has one or more layers of material in itself. For instants a laminate can be unidirectional fibre either continues or uncontinuous that is joined together using a matrix material. Suitable matrix materials are epoxy, resin or other thermoplastic materials. The fibres can comprise layers of carbon fibres, glass fibres, basaltic fibres, fabric, textile, natural fibres or any combination of these types of fibres.

[0082] Further details of the grippers are shown in FIGS. 4a and 4b. The gripper 10, 11 shown in FIG. 4a has an end surface which is depicted in top view in FIG. 4a that is separated by canals 10.2. The gripper surfaces 10.1, 10.3 are formed by two different elements. The innermost gripper surfaces 10.1 are formed of essentially rectangular surfaces, wherein the side surfaces 10.3 are in an essentially trapezoid form. The adapted geometry of the sides of the grippers can help in directing the overmold flow in the mold cavity. Further, the side surfaces 10.3 can come at an angle in respect to the inmost surfaces 10.1. The angle can be either positive or negative, depending on weather a clamping or an analogous counterpart to a clamp is to be formed by the gripper 10, 11.

[0083] The same embodiment of FIG. 4a is shown in FIG. 4b in a profile cut view. The gripper 10, 11 is attached to two retaining arms 7. And the innermost surface 10.1 are separated from each other by a canal 10.2 and further by further canals 10.2 from the end side surfaces 10.3.

[0084] The canals can further help at insuring a flow of overmold material during the injection molding. Further it can help with increasing the grip on the laminate.

[0085] Set forth below are some embodiments of the device and method disclosed herein.

[0086] Embodiment 1: A device for injection molding of a composite material comprising at least one laminate, the device comprising: a) a mold including: a plurality of mold portions, each having a first side defining a molding surface, and where at least one of the mold portions is movable relative to at least one other of the mold portions, such that the mold is movable between an open state and a closed state in which the molding surfaces of the mold portions cooperate to define a mold cavity; and b) one or more retaining arms with a gripper for contacting the laminate and whereby the retaining arm is arranged such that it is movable between a retracted position and an extended position.

[0087] Embodiment 2: The device of Embodiment 1, where at least one of the retaining arm(s) is slidably coupled to the respective mold portion.

[0088] Embodiment 3: The device of any of the preceding embodiments, where at least one of the retaining arm(s) includes at least one shaft that is coupled to the gripper and is slidably received by the respective mold portion.

[0089] Embodiment 4: The device of any of the preceding embodiments, where, for at least one of the retaining arm(s), the molding surface of the respective mold portion defines a recess configured to receive at least a portion of the gripper when the retaining arm is in the retracted position.

[0090] Embodiment 5: The device of any of the preceding embodiments, where, for at least one of the retaining arm(s), the molding surface of the respective mold portion defines a recess configured to receive the gripper when the retaining arm is in the retracted position such that an outer surface of the gripper is substantially flush with a portion of the molding surface that borders the recess.

[0091] Embodiment 6: The device of any of the preceding embodiments, where the retaining arms are arranged in pairs, with each retaining arm having an opposite retaining arm, such that the grippers of the pair of retaining arms are adapted at holding a laminate in place.

[0092] Embodiment 7: The device of any of the preceding embodiments, comprising at least two retaining arms, whereby a first retaining arm is movably coupled to a first mold portion, and a second retaining arm is movably coupled to a second mold portion, such that when the mold is in the closed state, the gripper of the first retaining arm opposes the gripper of the second retaining arm.

[0093] Embodiment 8: The device of any of the preceding embodiments, where the gripper of at least one of the retaining arm(s) defines one or more channels extending through the gripper and configured to receive overmolding material.

[0094] Embodiment 9: The device of any of the preceding embodiments, where the mold comprises at least one injection gate, in particular a plurality of injection gates, and further in particular at least one of the mold portions comprises an injection gate.

[0095] Embodiment 10: The device of any of the preceding embodiments, whereby the retaining arms are individually actuated, in particular are actuated such that at least one retaining arm is capable of performing a multi-level stroke, the retaining arms being actuated by at least one drive chosen from the group consisting of: hydraulic drive, pneumatic drive or electromechanical linear actuator.

[0096] Embodiment 11: The device of Embodiment 10, whereby the retaining arms are actuated by at least one hydraulic drive, in particular by two hydraulic drives such that the retaining arms are capable of performing a two-level stroke.

[0097] Embodiment 12: A method for injection molding of a composite material comprising at least one laminate, comprising: in particular, providing a device according to any of the preceding embodiments; placing a laminate relative to a plurality of mold portion of a mold, where: at least one of the mold portions is movable relative to at least one other of the mold portions such that the mold is movable between an open state and a closed state in which the molding surfaces of the mold portions cooperate to define a mold cavity; and the placing the laminate is such that, when the mold is in the closed state, the laminate is at least partially disposed within the mold cavity; and moving at least one gripper that is movably coupled to the first side of a respective one of the mold portions into contact with the laminate by moving the gripper between a retracted position and an extended position in which the gripper is further from the molding surface of the respective mold portion than when in the retracted position, injecting the mold cavity with an overmolding material and moving the grippers from the extended position to the retracted position, in particular sequentially moving the grippers from the extended position to the retracted position.

[0098] Embodiment 13: The method of Embodiment 12, comprising applying tension to the laminate inside the mold.

[0099] Embodiment 14: The method of any of Embodiment 12 or 13, where the overmolding material comprises a thermoplastic material.

[0100] Embodiment 15: The method of any of Embodiments 12-14, where the overmolding material comprises a plurality of fibers.

[0101] Embodiment 16: The method of any of Embodiments 12-15, comprising moving the at least one gripper out of contact with the laminate to allow overmolding material to flow between the gripper and the laminate.

[0102] Embodiment 17: Use of a device according to any of Embodiments 1-11 for the overmold injection molding of a strand of unidirectional fibre material, in particular a laminate comprising a strand of unidirectional fibre material.

[0103] For a person are skilled in the art it is perfectly evident, that all the shown particular embodiments and examples are in no way limiting to the scope of the present invention and you can easily adopt the general disclosure to the particular embodiments, such that further advantages embodiments maybe realised. The present application claims priority to Application No. CH: 00291/16, filed on Mar. 7, 2016, by Georg Kaufmann Formenbau AG, which is incorporated herein in its entirety.