METHOD AND DEVICE FOR PRODUCING INJECTION-MOLDED PARTS

Abstract

A device (6) for producing injection-molded parts (1) is provided, with the device device (6) having at least one cooling device (9) in which pre-molded parts (4) are cooled before the injection-molding of a further material component (3). A method is also provided with improvements in the technical field of the production of injection-molded parts (1), in particular of brushes or toothbrush bodies.

Claims

1. A method for producing injection-molded parts (1), comprising: injection-molding a pre-molded part (4) from at least one first material component (2) in a first injection mold (7); retrieving the pre-molded part (4) from the first injection mold (7) and cooling the pre-molded part (4) outside the injection molds (7, 8, 8a) before further injection-molding; and injection-molding at least one further material component (3) to or around the pre-molded part in at least one further injection mold (8, 8a).

2. The method as claimed in claim 1, further comprising feeding the pre-molded part (4) for cooling to a cooling device (9), actively or passively cooling the pre-molded part (4) in the cooling device (9), and the at least one further material component (3) is injection-molded to or around the cooled pre-molded part (4).

3. The method as claimed in claim 1, wherein the pre-molded part (4) is cooled prior to the injection-molding of each said further material component (3), by being fed in each case to a cooling device (9).

4. The method as claimed in claim 1, wherein the cooling device (9) is disposed outside the injection molds (7, 8, 8a), and the pre-molded part (4) is retrieved from the cooling device (9) and for injection-molding the at least one further material component (3) is incorporated in the injection mold provided therefor.

5. The method as claimed in claim 1, further comprising cooling the pre-molded part (4) at least for the duration of one injection-molding cycle.

6. The method as claimed in claim 1, wherein at least one of polypropylene (PP) or polyethylene terephthalate (PET) are used as the first material component (2), and a thermoplastic elastomer (TPE) is used as the second material component (3).

7. The method as claimed in claim 1, wherein the at least one first material component (2) is injection-molded at a volumetric ratio of at least 1.5 to 1; 2 to 1; 5 to 1, or 10 to 1, in relation to the at least one further material component (3).

8. The method as claimed in claim 1, wherein the method is carried out using a hot runner system

9. The method as claimed in claim 2, wherein the cooling device is an actively cooled cooling device (9).

10. A device for producing injection-molded parts (1), comprising: at least one first injection mold (7) for injection-molding a pre-molded part (4) from at least one first material component (2); at least one further injection mold (8) in which a further material component (3) is adapted to be injected to or around the pre-molded part (4); and at least one cooling device (9) configured to cool the pre-molded parts (4).

11. The device (6) as claimed in claim 10, wherein the at least one cooling device (9) is disposed outside the injection molds (7, 8, 8a), and the at least one cooling device (9) is an active cooling device.

12. The device (6) as claimed in claim 11, wherein the at least one cooling device (9) has a plurality of mountings (12) for the pre-molded parts (4).

13. The device (6) as claimed in claim 10, further comprising at least one of a relocation gripper (19) assigned to the at least one cooling device (9), a manipulation gripper (15) assigned to the at least one cooling device (9), or a retrieval gripper (17).

14. The device as claimed in claim 13, wherein the manipulation gripper (15) is configured for at least one of retrieving or inserting at least one of the pre-molded parts (4) or the molded parts (1) at least one of from or into the first injection mold (7), from or into the at least one further injection mold (8, 8a), or from or into the at least one cooling device (9).

15. The device (6) as claimed in claim 10, wherein each said injection mold has at least one nozzle-side mold half (27) and at least one ejector-side mold half (28) in which mold halves (27, 28) mutually complementary mold cavities (26) are configured.

16. The device (6) as claimed in claim 10, wherein the at least one cooling device comprises a number of cooling devices (9), said number being one less than a number of the injection molds (7, 8, 8a).

17. The device (6) as claimed in claim 10, wherein the at least one cooling device (9) is configured as a cooling tower which has at least two levels (29) which are disposed on top of one another and which have mountings (12) adapted to receive the pre-molded parts (4).

18. The device (6) as claimed in claim 10, wherein the device (6) has at least one cooling apparatus (11) for the at least one cooling device (9), and the at least one cooling device (9) comprises a plurality of cooling chambers which are configured or disposed in or on drawers.

19. The device (6) as claimed in claim 10, wherein the device for is configured for producing at least one of brush or toothbrush bodies.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention will now be described in more detail by using exemplary embodiments but is not limited to these exemplary embodiments. Further exemplary embodiments of the invention are derived by mutually combining the features of individual or a plurality of claims and/or by combining individual or a plurality of features of the exemplary embodiments. In the figures, in part in a highly schematic illustration:

[0035] FIG. 1: shows a plan view of an injection-molded part in the form of a toothbrush body, produced according to the method described in detail above;

[0036] FIG. 2: shows a sectional view of the toothbrush body along the line identified by II-II in FIG. 1;

[0037] FIG. 3: shows the detail marked by A in FIG. 2, in an enlarged illustration;

[0038] FIG. 4: shows a first exemplary embodiment of a device for producing injection-molded parts in a highly schematic illustration, wherein a total of two injection-molding apparatuses for injection-molding two dissimilar material components or colors, a cooling device for the external cooling of pre-molded parts, and a retrieval device for retrieving finished injection-molded parts can be seen;

[0039] FIG. 5: shows a highly schematic view of a further device according to the invention for producing injection-molded parts, wherein the device has a total of three injection-molding apparatuses for injection-molding three dissimilar material components or colors, two external cooling devices, a manipulation gripper, a relocation gripper, as well as a retrieval device having a retrieval gripper;

[0040] FIG. 6: shows a further exemplary embodiment of a device according to the invention for producing injection-molded parts, wherein the device makes use of the concept of the device illustrated in FIG. 5, and has two injection-molding apparatuses as well as a cooling device;

[0041] FIG. 7: shows the detail marked by the rectangle B in FIG. 6, in an enlarged illustration;

[0042] FIG. 8: shows the detail marked by the rectangle C in FIG. 6, in an enlarged illustration;

[0043] FIG. 9: shows the device for producing injection-molded parts illustrated in FIGS. 6 to 8, wherein pre-molded parts, or completed injection-molded parts, respectively, injection-molded by way of the two injection-molding apparatuses have been removed from both injection molds and moved to the respective transfer position with the aid of a manipulation gripper of the device;

[0044] FIG. 10: shows the detail marked by the rectangle D in FIG. 9, in an enlarged illustration, wherein the receiving spaces or mountings of the cooling device for pre-molded parts are occupied by pre-molded parts; and

[0045] FIG. 11: shows the detail marked by the rectangle E in FIG. 9, in an enlarged illustration, wherein mold cavities of the two injection molds for producing pre-molded parts, on the one hand, and for producing injection-molded parts from the pre-molded parts, on the other hand, can be seen here.

DETAILED DESCRIPTION

[0046] In the description hereunder of different embodiments of the invention, elements which in terms of the function thereof are identical, are provided with identical reference signs, even in the case of a deviating design or shape.

[0047] FIGS. 1 to 3 show an injection-molded part which as an entity is identified by the reference sign 1 and which in the present case is configured as a toothbrush body. The injection-molded part 1 illustrated in FIGS. 1 to 3 is injection-molded from two dissimilar material components or colors 2 and 3. The material components 2 and 3 can be particularly readily seen in the sectional illustrations according to FIGS. 2 and 3.

[0048] The first material component 2 of the two material components 2 and 3 herein forms a main body 4 of the injection-molded part 1.

[0049] The second material component 3 forms an overmolding 5 of the main body 4 of the injection-molded part 1 and is injection-molded in a dedicated injection-molding step. The overmolding 5 of the injection-molded part 1 which is composed of the second material component 3 has a significantly smaller volume than the main body 4 which is injection-molded from the first material component 2 and which also can be referred to as the pre-molded part 4. Since the first material component 2 is injection-molded so as to have a larger volume than the second material component 3, the second material component 3 for the production of the overmolding 5 can be more expensive than the first material component 2.

[0050] The dissimilar volumes of the main body 4, on the one hand, and of the overmolding 5 of the main body 4 of the injection-molded part 1, on the other hand, are associated with cooling times of dissimilar length after the injection-molding of the respective material components 2 and 3, the adherence to said cooling times in the case of the methods and the device known to date overall leading to extended cycle times in the injection-molding of the two material components 2 and 3.

[0051] In order for the cycle times in the production of injection-molded parts 1 which are injection-molded from at least two material components 2 and 3 at dissimilar volumes to be adjusted and to overall be kept as short as possible, it is proposed for the pre-molded parts 4 to first be cooled externally, that is to say outside the injection-molds 7 and 8, before the second or else a further material component or color 3 is injection-molded. The device 6, explained in detail hereunder, is provided and specified to this end.

[0052] All of the devices 6 illustrated in the figures for producing injection-molded parts 1 have at least one first injection mold 7 for injection-molding a pre-molded part 4 from at least one first material component 2 and at least one further or second injection-mold 8. One further material component, specifically the second material component 3 already mentioned above, can be injection-molded to or around the pre-molded part 4 in the second injection mold 8, so as to complement the pre-molded part 4 and to thus complete the injection-molded part 1, for example a toothbrush body.

[0053] To this end, the pre-molded part 4 produced in the first injection mold 7 is transferred into the second injection mold 8. The second material component 3 for generating an overmolding 5 of the toothbrush body 4 is then injected in the second injection mold 8, and either an already completed injection-molded part 1 is generated or a further pre-molded part which is still complemented in a further injection-molding step is produced.

[0054] Each of the devices 6 illustrated in the figures has in each case one cooling device 9 for pre-molded parts 4. Each cooling device 9 illustrated in the figures herein is disposed on a frame 10 of the device 6 so as to be outside the at least two injection molds 7 and 8.

[0055] The cooling devices 9 illustrated in the figures are so-called active or actively cooled cooling devices 9 which are in each case equipped with one cooling apparatus 11. With the aid of the respective cooling apparatus 11, a plurality of pre-molded parts 4 can be simultaneously cooled and thus prepared for at least one subsequent injection-molding step. The illustrations 7 and 10 of cooling devices 9 highlight in particular that said cooling devices 9 have in each case a plurality of mountings 12 for receiving pre-molded parts 4.

[0056] The mountings 12 are configured on a rotatable drum 13 of the respective cooling device 9. The mountings 12 and the pre-molded parts 4 disposed thereon are positionally variable by rotating the drum 13 about the rotation axis R thereof and by displacing the drum 13 along linear guides 14 of the cooling devices 9.

[0057] Each of the devices 6 illustrated in the figures furthermore has a manipulation gripper 15. With the aid of the respective manipulation gripper 15, pre-molded parts 4 injection-molded in the first injection mold 7 can be retrieved from said first injection mold 7 and first fed to the cooling device 9 which is assigned to the first injection mold 7. By way of a gripper module 22 of the manipulation gripper 15, pre-molded parts 4 that have been cooled in the cooling device 9 can be retrieved from the cooling device 9 and fed to the subsequent second injection mold 8, so as to overmold the cooled pre-molded parts 4 with an overmolding 5 from the second material component 3.

[0058] The respective manipulation gripper 15 ultimately also serves for retrieving completed injection-molded parts 1 from the last injection mold 8 of a series of injection molds 7 and 8 and to transport said completed injection-molded parts 1 to a transfer position 16. The completed injection-molded parts 1 in said transfer position 16 can be retrieved by way of the manipulation gripper 15 and, with the aid of a retrieval gripper 17, be deposited on a depositing face 18 of the device 6 and/or be transferred to a downstream processing station.

[0059] In the case of the device 6 according to FIG. 5 a relocation gripper 19 is moreover provided. Said relocation gripper 19 serves for retrieving the pre-molded parts 4 of a first material component or color 2 from the manipulation gripper 15 and to feed said pre-molded parts 4 to a first cooling device 9 which is downstream of and assigned to the first injection mold 7. Once the pre-molded parts 4 in the case of this device 6 according to FIG. 5 have been correspondingly cooled in the first cooling device 9, said pre-molded parts 4 can be fed to the downstream further injection mold 8. The pre-molded parts 4 in this downstream injection mold 8 are provided with a first overmolding 5. The overmolded pre-molded parts 4 with the aid of the manipulation gripper 15 subsequently make their way to a further cooling device 9 of the device 6, said cooling device 9 being assigned to the second injection mold 8. Said pre-molded parts 4 at the cooling device 9 are again cooled so as to be subsequently fed in the cooled state to a third downstream injection mold 8a.

[0060] The pre-molded parts 4 here are imparted a further overmolding 5 from a third material component, and can then be retrieved as completed injection-molded parts 1 from said last injection mold 8a in the series of three injection molds. Said completed injection-molded parts 1, with the aid of the retrieval gripper 17 of said device 6, are transferred by the manipulation gripper 15 to the depositing face 18, or to a downstream processing station, respectively.

[0061] In the case of all exemplary embodiments of the devices 6 which are illustrated in the figures, the manipulation gripper 15 is mounted so as to be displaceable along a guide rail 20 on the frame 10 of the device 6. In this way, the manipulation gripper 15 can be repositioned between the transfer position 16 on the retrieval gripper 17 and an insertion and retrieval position 21 neighboring the at least two injection molds 7 and 8.

[0062] The manipulation grippers 15 of each of the devices 6 illustrated in the figures herein are specified for retrieving and inserting pre-molded parts 4, and moreover for retrieving injection-molded parts 1 from the respective injection mold 7 or 8, respectively. To this end, the manipulation grippers 17 have respective gripper modules 22.

[0063] With the aid of the manipulation grippers 15 and the respective gripper modules 22, it is furthermore possible for the cooling devices 9 of the respective devices 6 to be supplied with pre-molded parts 4 to be overmolded. According to the figures, each injection mold 7, 8, and 8a is in each case assigned one dedicated injection-molding apparatus 23, 24, or 25, respectively. One of the material components 2 and 3, by way of each injection-molding apparatus 23, 24 and 25, can in each case be injected into the respectively assigned injection mold 7 or 8, respectively, and 8a.

[0064] Each injection mold 7, 8, and 8a has in each case one nozzle-side mold half 27 as well as one ejector-side mold half 28 in which mold halves 27, 28 mutually complementing mold cavities 26 are configured. With the aid of the injection-molding apparatuses 23, 24, and 25, the dissimilar material components or colors 2 and 3 can be injected into the mold cavities 26 for initially producing the pre-molded parts 4 and subsequently for producing the injection-molded parts 1. The infeeding of the material components herein can be performed by way of a hot runner system (not specifically illustrated in the figures).

[0065] In the case of all of the exemplary embodiments illustrated in the figures of devices 6 for producing injection-molded parts 1 a number of cooling devices 9 is provided, said number being one less than the number of the injection molds 7, 8, and 8a, and also one less than the number of injection-molding apparatuses 23, 24, and 25. In this way, each injection mold 7, 8, and 8a, and thus each injection-molding apparatus 23, 24, and 25, which are/is provided for producing pre-molded parts 4, is in each case assigned one cooling device 9 for cooling the pre-molded parts 4 produced therewith.

[0066] Specifically, the cooling devices 9 of the devices 6 for producing injection-molded parts 1 illustrated in the figures are configured as cooling towers. Each of the cooling devices 9 has in each case two levels 29 having mountings 12 for pre-molded parts 4. As has already been explained above, the cooling devices 9 have rotatable drums 13 which are moreover height-variable along the linear guides 14. In this way, the cooling devices 9 can be vertically adjusted so as to correspond to the pre-molded parts 4 that are held ready for transfer on the manipulation gripper 15. FIGS. 6 and 8, as well as 9 and 11, highlight that the injection molds 7, 8 or 8a, respectively, are mutually disposed at a certain offset in height.

[0067] This is caused by the dissimilar injection points by way of which the first material component 2 and the second or third, respectively, material component 3 are injected into the injection molds 7 and 8, as well as optionally 8a. In order for injection nozzles of the injection-molding apparatuses 23, 24, and 25 to be able to be disposed at the same height, it is necessary for the injection molds 7, 8, and 8a to be mutually disposed at a corresponding vertical offset. Said offset which can be seen in FIGS. 6 and 8, as well as 9 and 11, can be equalized either by way of a corresponding kinematic system of the manipulation gripper 15 or else, this being preferable, by way of the height adjustability of the respective cooling device 9, described above. In this way, the manipulation gripper 15 can be designed to be of simpler construction and lighter. This in turn facilitates high acceleration values, on account of which the manipulation gripper 15 can be repositioned more rapidly and the cycle times can overall be shortened.

[0068] The method described hereunder for producing injection-molded parts 1 can be carried out on the devices 6 for producing injection-molded parts 1, described in detail above.

[0069] It is provided herein that pre-molded parts 4 from at least one first material component 2 are injection-molded in a first injection mold 7, whereupon at least one further material component 3 is injection-molded to or around the previously produced pre-molded parts 4 in at least one further injection mold 8, 8a.

[0070] The pre-molded parts 4 are retrieved from the first injection mold 7 and are cooled outside the two or else three injection molds 7, 8, and optionally 8a, before the at least one further material component 3 is injection-molded to or around the pre-molded parts 4 in order for the injection-molded parts 1 to be completed.

[0071] The pre-molded parts 4 for cooling are fed to a cooling device 9. The pre-molded parts 4 are actively cooled in the cooling device 9. The at least one further material component 3 is then injection-molded to or around the cooled pre-molded parts 4. Since the pre-molded parts 4 have a larger volume than the overmolding 5 that has been injection-molded to the pre-molded parts 4, said pre-molded parts 4 at room temperature would require a longer time to cool to a temperature required for injection-molding the further material component 3 to or around said pre-molded parts 4. Without the external cooling devices 9, the pre-molded parts 4 would thus have to dwell longer in the first injection mold 7, which overall would lead to a prolongation of the cycle times or production rates when carrying out the injection-molding method for producing the injection-molded parts 1.

[0072] When the pre-molded parts 4 in further injection-molding steps are to be provided with further overmoldings 5 from further material components 3, the pre-molded parts 4 are cooled by the cooling devices 9 before the injection-molding of each further material component 3. To this end, the pre-molded parts 4 can in each case be fed to a cooling device 9 that is downstream of and assigned to the respective injection mold 7 or 8, or else only to one cooling device 9 which in this instance is provided for cooling all of the pre-molded parts 4. Said cooling device 9 in this instance is thus assigned to two or a plurality of injection molds 7 and 8 by way of which the pre-molded parts 4 are generated.

[0073] Each cooling device 9 is disposed outside the injection molds 7 and 8. In this way, the cooling of the pre-molded parts 4 in temporal terms can be decoupled from the injection-molding of the pre-molded parts 4 and the injection-molded parts 1. After cooling, the pre-molded parts 4 are retrieved from the respective cooling device 9 and for injection molding the at least one further material component 3 is incorporated in the downstream injection mold 7, 8, or 8a provided to this end.

[0074] For example, the pre-molded parts 4 can dwell and cool in or on the cooling device 9 for the duration of one injection-molding cycle. In particular when the volumes at which the dissimilar material components 2 and 3 are injection-molded deviate heavily from one another, thus when the volume of the first material component 2 on the injection-molded part 1 is significantly larger than the volume of the second material component 3 which forms the overmolding 5, for example, it can be expedient for the pre-molded part 4 to be cooled for a plurality of injection-molding cycles or operating cycles in or on the cooling device 9 provided to this end.

[0075] Polypropylene (PP) and/or polyethylene terephthalate (PET) can be injection-molded as the first material component 2, for example. Thermoplastic elastomer (TPE) can be used as the second, typically more expensive, material component 3 for producing the overmolding 5 of the pre-molded parts 4.

[0076] The volumetric ratio at which the first material component 2 is injection-molded in relation to the at least one further material component 3 for producing the injection-molded part 1 can be, for example, at least 1.5 to 1; 2 to 1; 5 to 1, or else at least 10 to 1.

[0077] As has already been mentioned above, an actively cooled cooling device 9 which possesses a cooling apparatus 11 is preferably used as the cooling device 9. In principle however, the use of passively cooled cooling devices 9 which, for example by virtue of the material of which said cooling devices 9 are composed, are particularly well suitable for the dissipation of heat, is also conceivable. A simple cooling section or cooling face onto which the pre-molded parts 4 can be deposited for cooling can also be used as the cooling device 9.

LIST OF REFERENCE SIGNS

[0078] 1 Injection-molded part

[0079] 2 First material component

[0080] 3 Second material component

[0081] 4 Main body/Pre-molded part

[0082] 5 Overmolding

[0083] 6 Device for producing injection-molded parts

[0084] 7 First injection mold

[0085] 8 Second injection mold

[0086] 8a Further/third injection mold

[0087] 9 Cooling device

[0088] 10 Frame of 6

[0089] 11 Cooling apparatus of 9

[0090] 12 Mounting on 9

[0091] 13 Drum of 9

[0092] 14 Linear guide of 9

[0093] 15 Manipulation gripper

[0094] 16 Transfer position

[0095] 17 Retrieval gripper

[0096] 18 Depositing face

[0097] 19 Relocation gripper

[0098] 20 Guide rail

[0099] 21 Insertion and retrieval position

[0100] 22 Gripper modules

[0101] 23 Injection-molding apparatus

[0102] 24 Injection-molding apparatus

[0103] 25 Injection-molding apparatus

[0104] 26 Mold cavity

[0105] 27 Nozzle-side mold half

[0106] 28 Ejector-side mold half

[0107] 29 Levels

[0108] R Rotation axis of 13