INJECTION UNIT FOR A MOULDING MACHINE AND METHOD FOR INJECTING A PLASTICIZED MASS

Abstract

An injection unit for a moulding machine includes an injection cylinder, and an injection piston is provided in the injection cylinder. During an injection process, the injection piston is configured to push out a plasticized mass—in particular plasticized plastic—from the injection cylinder and to feed it to a moulding tool via an injection nozzle. At least two plasticizing units and two supply channels are provided, and the at least two plasticizing units can be fluidically connected with the injection nozzle by the supply channels. The at least two plasticizing units are configured to supply the injection cylinder with the plasticized mass via the supply channels and the injection nozzle prior to the injection process.

Claims

1. An injection unit for a moulding machine comprises an injection cylinder, and an injection piston is provided in the injection cylinder, which, within the scope of an injection process, is configured to push out a plasticized mass—in particular plasticized plastic—from the injection cylinder and to feed it to a moulding tool via an injection nozzle, wherein at least two plasticizing units and two supply channels are provided, wherein the at least two plasticizing units can be fluidically connected with the injection nozzle by the supply channels and the at least two plasticizing units are configured to supply the injection cylinder with the plasticized mass via the supply channels and the injection nozzle prior to the injection process.

2. The injection unit according to claim 1, wherein a closed-loop or open-loop control device is provided, which preferably is configured to closed-loop or open-loop control the at least two plasticizing units to sequentially supply the injection cylinder.

3. The injection unit according to claim 1, wherein the injection cylinder is movable between two positions by a moving device, preferably along a longitudinal axis of the injection unit, wherein in a first position, the injection cylinder is fluidically connected with a moulding tool, preferably the injection nozzle is indirectly or directly pressed against a moulding tool and/or a stationary mould clamping plate, and/or in a second position, the injection cylinder is fluidically connected with at least one of the at least two plasticizing units.

4. The injection unit according to claim 3, wherein the moving device comprises a linear drive, preferably a piston-cylinder unit.

5. The injection unit according to claim 1, wherein the at least two plasticizing units comprise at least one drive, which at least one drive is configured to fluidically connect the plasticizing units with the injection nozzle by a movement of the plasticizing units—preferably transverse to the longitudinal axis of the injection cylinder.

6. The injection unit according to claim 1, wherein at least one—preferably all—of the at least two plasticizing units comprises a plasticizing screw.

7. The injection unit according to claim 1, wherein at least one of the at least two plasticizing units comprises a recycling device.

8. The injection unit according to claim 1, wherein at least one—preferably all—of the at least two plasticizing units comprise/s a melt reservoir.

9. The injection unit according to claim 1, wherein at least one—preferably all—of the at least two plasticizing units is/are arranged substantially in parallel to the injection cylinder.

10. A moulding machine, preferably an injection moulding machine, including the injection unit according to claim 1.

11. A method for injecting a plasticized mass—in particular plasticized plastic—into a moulding tool of a moulding machine, wherein, within the scope of an injection process, a plasticized mass is pushed out from an injection cylinder by an injection piston and is fed to a moulding tool via an injection nozzle, wherein, for supplying the injection cylinder with the plasticized mass, at least two plasticizing units are used, which supply the injection cylinder with the plasticized mass from the injection nozzle prior to the injection process.

12. The method according to claim 11, wherein, with the at least two plasticizing units, at least two different materials are plasticized and fed to the injection cylinder as the plasticized mass.

13. The method according to claim 1, wherein the injection cylinder is sequentially supplied by the at least two plasticizing units prior to the injection process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Further details and embodiments of the invention are apparent from the figures as well as the associated description of the figures, in which:

[0059] FIG. 1 illustrates a first embodiment according to the invention,

[0060] FIG. 2 is a detailed view from FIG. 1,

[0061] FIG. 3 is a further detailed view from FIG. 1,

[0062] FIG. 4 illustrates a first embodiment of a moulding machine according to the invention,

[0063] FIG. 5 illustrates a second embodiment of a moulding machine according to the invention,

[0064] FIG. 6 illustrates a further embodiment according to the invention, and

[0065] FIG. 7-9 illustrate an injection process of an injection unit according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0066] FIG. 1 illustrates a first embodiment of an injection unit 1 according to the invention. The injection unit 1 of this embodiment comprises an injection cylinder 2, in which an injection piston 3 is movably mounted along the longitudinal axis 11 of the injection unit 1.

[0067] Via an injection nozzle 4, a plasticized mass can be injected from the injection cylinder 2 into a mould cavity 5 of the moulding tool 6 by means of the injection piston 3.

[0068] In this embodiment, the moulding tool 6 is arranged at a stationary mould clamping plate 12.

[0069] A first plasticizing unit 7 and a second plasticizing unit 8 are provided for plasticizing the material. In this embodiment, the first plasticizing unit 7 and the second plasticizing unit 8 are arranged in parallel to the injection cylinder 2.

[0070] The first plasticizing unit 7 and the second plasticizing unit 8 respectively comprise a plasticizing screw 13 arranged in a cylinder, which plasticizes material—for example plastic granules—fed via the feeding devices 15 and can feed it to the injection cylinder 2 via the first supply channel 9 and the second supply channel 10.

[0071] The enlarged rotary slide valve 16 of FIG. 1 shown in FIG. 2 can be utilized to shut off the first supply channel 9 in front of the connecting flange 18 shown by rotating the rotary slide valve 16.

[0072] When the injection nozzle 4 of the plasticizing unit 7, 8 is lifted off from the connecting flange 18 and is not fluidically connected therewith—this rotary slide valve 16 can be used to shut off the supply channel 9, 10, so that plasticized mass cannot exit in an uncontrolled manner.

[0073] Thus, the plasticizing units 7, 8 continue working during the injection of the injection cylinder 2 and plasticized mass for the next work cycle is already be prepared during the injection.

[0074] Furthermore, with the diverter valve 17 (of FIG. 1), shown enlarged in FIG. 3, the supply channels 9, 10 can be shut off in front of the plasticizing units 7, 8 or part of the material plasticized by the plasticizing units 7, 8 is diverted, resp.

[0075] This diverter valve 17 can guide the material flow outside, before this can get into the injection cylinder 2.

[0076] The advantage of this diverter valve consists in the fact that upon using compounded material or recycled material, the material quality can be set as best as possible upon starting up the moulding process, and only when this is guaranteed (by material testing at the exit of the diverter valve 17), a switchover into the actual production operation can be performed.

[0077] Furthermore, in case of a/an (brief) interruption of production (incident), plasticized material can exit by opening the diverter valve 17, so that no inadmissible pressure builds up or no other disruptions occur, resp. Then, there can be a very fast switchover back to the production sequence, without having to put the plasticizing units 7, 8 into standstill during the disruption.

[0078] The embodiments according to the invention can be used for different moulding machines 20.

[0079] Thus, for example, the embodiment of FIG. 1 is illustrated in FIG. 4 for a moulding machine 20 with a horizontal clamping unit 21.

[0080] In FIG. 5, the embodiment of FIG. 1 is combined with a vertical clamping unit 21 for a moulding machine 20.

[0081] FIG. 6 illustrates a similar embodiment as FIG. 1 already does, wherein a melt reservoir 14 is respectively provided along the supply channels 9, 10, which reservoir can be shut off in the direction of the injection nozzle 4 by the rotary slide valve 16 (illustrated in more detail in FIG. 2) and in the direction of the plasticizing unit 7, 8 by means of a diverter valve 17 (illustrated in more detail in FIG. 3).

[0082] These melt reservoirs 14 are volumes, which are arranged between the plasticizing units 7, 8 and the injection nozzle 4 (of the injection cylinder 2) and are configured to temporarily store a plasticized mass.

[0083] Thus, it is possible that, for example, at least one plasticizing unit 7, 8 continues plasticizing during the injection process, and this plasticized mass is temporarily stored in the melt reservoir 14, until the injection cylinder 2 is connected and the stored plasticized mass can be transferred from the melt reservoir 14 into the injection cylinder 2.

[0084] In particular in case of applications with plasticizing units 7, 8 having an extruder, this has the advantage that the extruder can continuously plasticize without interruption.

[0085] During the injection process, the plasticized mass is temporarily stored in the melt reservoir 14, and is then passed on to the injection cylinder 2 in the subsequent supply process.

[0086] FIGS. 7 to 9 illustrate an injection process of an embodiment of an injection unit 1 according to the invention (the embodiment of FIG. 1).

[0087] In a first step (illustrated by FIG. 7), the injection cylinder 2 is moved away from the moulding tool 6 along the longitudinal axis 11 of the injection unit 1 and the first plasticizing unit 7 is displaced transverse thereto, so that the injection nozzle 4 lies against a previously described connecting flange 18 of the first plasticizing unit 7 (or is pressed against it).

[0088] With the fluidical connection between the first plasticizing unit 7 and the injection cylinder 2 thus generated, plasticized mass from the plasticizing unit 7 can now be transferred into the injection cylinder 2 by pushing out plasticized mass with the plasticizing screw 13 of the first plasticizing unit 7 and simultaneously retracting the injection piston 3, so that the injection cylinder 2 is gradually filled.

[0089] Once a defined quantity of plasticized mass from the first plasticizing unit 7 was fed to the injection cylinder 2, the first plasticizing unit 7 can be distanced from the injection cylinder 2 transverse to the longitudinal axis 11, and the second plasticizing unit 8 can be approached to the injection cylinder 2 transverse to the longitudinal axis 11.

[0090] As illustrated by FIG. 8, now, plasticized mass can be fed to the injection cylinder 2 from the second plasticizing unit 8 in the same manner, whereby a second area is formed in the injection cylinder 2 with a plasticized mass from the second plasticizing unit 8.

[0091] Once a defined quantity of plasticized mass from the second plasticizing unit 8 has been fed, too, the second plasticizing unit 8 can now be distanced from the injection cylinder 2 transverse to the longitudinal axis 11, and the injection cylinder 2 can be approached to the moulding tool 6, or more precisely, the injection nozzle 4 can be pressed against the moulding tool 6.

[0092] With a movement of the injection piston 3 along the longitudinal axis 11 of the injection unit 1, the plasticized masses can now be pushed out from the injection cylinder 2 and via the injection nozzle 4 fed to a mould cavity 5 of the moulding tool 6 (as illustrated by FIG. 8).

[0093] With a respective embodiment, as shown by the figures, a core material is generated by the first plasticizing unit 7 and then fed to the injection cylinder 2, whereas a skin material is generated by the second plasticizing unit 8 and then fed to the injection cylinder 2.

[0094] However, configurations are also quite conceivable, in which even further plasticized masses from further plasticizing units are fed via the injection nozzle 4, whereby several layers (for example, a layered structure) of a finished moulded part can be generated.

LIST OF REFERENCE SIGNS

[0095] 1 Injection unit [0096] 2 Injection cylinder [0097] 3 Injection piston [0098] 4 Injection nozzle [0099] 5 Mould cavity [0100] 6 Moulding tool [0101] 7 First plasticizing unit [0102] 8 Second plasticizing unit [0103] 9 First supply channel [0104] 10 Second supply channel [0105] 11 Longitudinal axis of the injection unit [0106] 12 Stationary mould clamping plate [0107] 13 Plasticizing screw [0108] 14 Melt reservoir [0109] 15 Feeding device [0110] 16 Rotary slide valve [0111] 17 Diverter valve [0112] 18 Connecting flange [0113] 19 Switch [0114] 20 Moulding machine [0115] 21 Clamping unit