DE102005035108A1 - Plastic molding machine, especially for fiber reinforced parts, includes a movable dispensing head to distribute components in a controlled pattern into the partly open mold - Google Patents

Abstract

Molten polymer is fed (20) from an extruder (10) through a gear pump (16) to a dispensing head (22), which also receives (28) reinforcing fibers from a fiber supply (26). The dispensing head (22) is moved, e.g. by a robotic arm (24), to place varying amounts of material into different regions of the open mold (34), the proportion of fiber being determined by a controller (38). An independent claim is included for the method of operating the machine so that the composition in various parts of the mold is controlled to achieve the required properties. The mold (34) is made of low heat capacity but high conductivity and can be heated electrically so that the polymer remains molten during the distribution process. When the mold is full it is closed and the temperature changed for the pressing stage.

Description

The The present invention relates to a plastic processing machine and a method of operating such a machine.

Plastics Processing Machines are well known. This is conventionally distinguished between extrusion machines, injection molding machines and polyurethane machines.

at Extrusion machines become a plastic starting material, mostly in Granular form, fed to an extruder device and melted there. At the end of the plasticizing the plastic melt guided by a tool and in a desired Profile shape (e.g., tube, square profile or other profile) brought. At the end, the continuously produced profile is cut to length.

Opposite these Continuously operating extrusion devices operate injection molding machines usually discontinuous. This is done in a plasticizer in turn melted a starting material, and the plastic melt is then cyclically introduced into a cavity (cavity) of an injection mold. The injection mold is mostly in a clamping unit arranged and can in this under building a closing pressure getting closed. A special form of an injection molding machine represents a so-called in-mold compounder, in which a Extrusion device with a piston filling device (also shot pot called) is combined. The extrusion device operates continuously and promotes Material in the shot pot, possibly with the interposition of a memory. From the shot pot, the plasticized material then becomes discontinuous into the cavity spent an injection mold.

In polyurethane machines, two reactants reacting with one another, for example polyol and isocyanate, are conventionally combined in a mixing head and intimately mixed with one another. From the mixing head, the reactive mixture is then introduced into a forming train, where it reacts to the corresponding product. In a special form, an additive is added in the mixing head. These may, for example, be fibers, such as glass fiber or a natural fiber, so that a glass fiber-filled melt material can be introduced into a mold. In this way one can produce a mechanically very stable product. If the fibers introduced into the material have a relatively long length, this is also referred to as an LFI process (LFI = Long Fiber Injection). Such a method is in the EP 0 771 259 described. When filling a mold part of the mixing head is moved in predetermined paths over the mold, wherein the reactive material is introduced into the part of a cavity. When the mold is completely charged, the mixing head is withdrawn and the mold is closed; then the curing phase begins.

The however, the last-mentioned process only occurs in polyurethane processes to the train. For the processing of a thermoplastic material is usually on resorted to the extrusion and / or injection molding.

It However, there have been various demands recently result in the production of products made from fibers Thermoplastic material exist. These requirements can with the previous method could not be solved. That's the way to have it at different fiber reinforced Products found that different areas of a product should have different mechanical strengths. This can be achieved, for example, that Einlegeteile (e.g. Fleeces or mats) in the cavity are inserted, which were then encapsulated accordingly.

Now However, there is a desire to have different sections a product in a different way with a thermoplastic material, possibly a filled Thermoplastic material, wants to manufacture. For example, the mixing ratio of a Fiber in the thermoplastic melt can be changed locally, resulting in the mechanical strength over to change the product.

Indeed is for such a project involves the use of a hitherto practiced injection molding not possible, because in an injection molding process not with a melt material changing within a shot can be controlled, which area within the cavity with which Plastic filled becomes.

task The present invention is a plastic processing Specify a machine in which a cavity of a mold in the desired Way with a changeable one Starting material filled can be so that a product can be produced, its mechanical or physical properties change across the product.

These The object is achieved by the features mentioned in claims 1 and 12 solved device or procedurally.

One The essential idea of the present invention is that a plastic melt is produced in a plasticizing unit, supplied to a discharge device and with this discharge device due to their ability to move locally controlled in the cavity a mold can be introduced. This is a requirement that to a desired one Position of the cavity Can spend starting material, which after curing a certain, desired mechanical Property defined. In this way you can the mold cavity in total so fill, that also the finished product in certain areas mechanical or has physical properties that are different to the properties of other areas.

According to one embodiment For example, the plastic melt may contain a filler, e.g. a reinforcement or pulp or a pure filler as well as a dye, be taught. Especially with the supply of fiber is then possible the mechanical strength in different areas of a finished product in desired Influence meadow. An influence on the mechanical properties can then be achieved when the filling content in the plastic melt locally changed can be. This is possible by that the discharge device and / or the introduction device and / or the supply device are designed such that the relationship the fillers in relation to change to plastic melt, in particular can be controlled or regulated.

Of course, in the plasticizer also different starting materials, such as For example, different thermoplastic materials, mixed together become. As a plasticizer, for example, is a Single or twin screw extruder. Alternatively, any other plasticizing could used, which is a starting material in a plastic melt transforms. Should be a desired Pressure build-up in an extruder would not be possible so could be between the extruder and the discharge device a gear pump interposed be, which accomplished the pressure build-up.

The Discharge device is over a mold half, in which at least partially the cavity is formed to position. Preferably, the movement should be over the entire area of a to be filled mold possible be, with the positioning also controlled or regulated is feasible.

Just at big or large parts be problematic if the thermoplastic material over relative long time in the cavity is filled and hardens on the cavity surface. at a filling process, which may be about one Period extending up to a 1 min, this could lead to the melt at least in the surface area hardened, and in a subsequent embossing step the plastic material is no longer distributed in the desired manner can. That leads to qualitative disadvantages of the product such as the training of visible Flow fronts. For this reason, the melt should be filled in the desired manner on a specific Temperature are kept. For this it should be possible, at least the part of the mold that with the einzufüllenden plastic melt in touch comes to heat at times.

A first version for Such a mold is characterized in that the mold comprises an insert made from the molding tool or the clamping unit Removable or reusable. Such a use could with a low heat capacity and one high thermal conductivity be educated. This could be this use in a heater quickly to a desired temperature of for example 180 ° C heat. After heating of the deployment would the plastic melt is filled in the insert and with the use in the mold or the clamping unit are spent. So could one Partial solidification of the melt can be avoided as the corresponding surfaces the plastic melt no heat revoke. A pressing after inserting the insert in the closing unit would be without qualitative problems possible.

alternative can However, all other known heaters provided be with which the surface of the cavity on the desired Temperature can be brought. For example, it is possible the Cavity surface in shape an electrically conductive To form ceramics, which are subject to a tension and the resulting resulting flow of a corresponding stream to a desired temperature is heatable.

In usually, plastic processing machine have a control and Control device on. This can also be the movement here control the discharge. In addition, such a tax and control device through the feed and throughput of the starting material the plasticizing, the possible pressure build-up with a Gear pump or the desired Addition of a filler, For example, of fibrous materials, controlled.

In the claims are these and other advantages of the present invention device or procedurally formulated.

The The present invention will now be described with reference to the accompanying figures explained in more detail. The Figures show in:

1 : a very schematic representation of a part of a plastic processing machine according to the invention with plasticizing and discharging device,

2 in a highly schematic way another part of a plastic processing machine with mold halves and insert and

3 a further embodiment of a mold half for such a plastic processing machine.

In 1 is in the very highly schematic representation of a plasticizer 10 shown a funnel 14 has, in which a plastic granules is supplied. In the plasticizing unit designed as a twin-screw extruder 10 two plasticizing screws are arranged by an electric drive device 12 are rotationally driven. During operation of the plasticizing device 10 A plastic melt is formed in the plasticiser 10 is conveyed forward and into a connecting pipe 18 leaking, which is the plasticizer 10 with a gear pump 16 combines. The gear pump 16 serves to build up pressure for the plastic melt and promotes this further via the connecting line 20 to a discharge device 22 ,

The discharge device 22 is to hold the plastic melt 20 and designed for discharge into a mold. In the present case, the discharge device 22 a glass fiber roving over the supply hose 28 from a storage container 26 fed. For this purpose, the discharge 22 as known in the art, a Einbringeinheit with a cutting device (not shown here), which the Glasfaserroving in the discharge 22 promotes and cuts there.

In a kind of mixing chamber (not shown) of the discharge 22 the glass fiber material is fed to the plastic melt and mixed with it. The plastic melt loaded with the glass fiber is then transferred via a discharge pipe 30 in a receiving device 34 discharged. This is in 1 with the melt jet 32 shown.

The discharge device 22 is with an actuator 24 coupled, which is embodied here as a robot arm and the discharge at least two-dimensional (see arrows) on the receiving device 34 can carry.

In addition, a control and control device 38 provided, in the present case both via lines 39 . 42 and 44 with the discharge device 22 , the gear pump 16 as well as the drive unit of the plasticizing device 10 connected is. The control and control device 38 is also over the line 41 with the actuator for the robot arm 24 coupled. Due to the stored in the control and control program now both the operation of plasticizing 10 as well as the gear pump 16 as well as the collection device in the discharge 22 and the robotic arm 24 operated in coordination in such a way that the plastic melt 32 in a predefined manner and composition in the receiving device 34 can be initiated.

In 2 is the recording device 34 , which is at least partially filled and just further filled, shown. The recording device 34 is on a hot plate 40 arranged and was heated by this before the start of filling to a temperature of about 180 ° C. The discharge device 22 is from the robot arm 24 by means of the robot operating device 36 in a predetermined manner via the receiving device 34 moved, taking over the supply lines 20 and 28 the corresponding materials of the discharge 22 be supplied.

The recording device 34 is presently designed as an insert for a mold and forms with its inner surface at least a portion of the cavity of the mold.

The mold is in 2 in the form of a lower mold half 50 and an upper tool half 52 shown, which are arranged in a closing unit, not shown. The upper tool half 50 can be moved up and down with the corresponding platen. The closing unit is designed to carry out an embossing step. In the lower half of the mold 52 is a recess 54 arranged, which is just so big that the receiving device 34 can be used accurately. Is the recording device 34 filled accordingly with the fiber-laden plastic melt, it will (see arrow in 2 ) by means of a handling device, not shown in the recess 54 spent. Subsequently, an embossing step is performed by closing the mold and formed the product to be produced.

Since the trained as an insert receiving device 34 is heated prior to filling with plastic melt, the plastic melt does not cool down directly, but remains in a plastic state, so that it can be imprinted properly without quality degradation.

An alternative embodiment for heating the mold in the present invention is shown in FIG 3 to recognize, in the Kavitätsbereich in the lower mold half 60 with a layer of electrically conductive ceramic 66 is formed, which over the connecting wires 68 can be supplied with electrical energy and thereby heated. In this case, after a corresponding heating of the cavity surface, the plastic melt by means of the discharge device 22 directly into the cavity 64 are introduced, where they are not cooled or partially cured due to the heating of the Kavitätsoberfläche (see 69 ). After the introduction of the plastic melt, the embossing step takes place again, as a result of which the product to be manufactured is produced, which can be removed from the molding tool after curing and opening of the molding tool.

The present invention enables due to the controllable filling the cavity a positionally accurate introduction of different plastic material. So can the loading of the plastic material with fibers or fillers depending on the position in the cavity chosen differently be. It can also used plastics with different properties for filling become. Thus, the plasticizing unit with one, two or more Plastics are supplied with paints etc., which are then in local given way into the cavity be introduced.

On this way is the production of products possible that otherwise in an injection molding process are not easy to produce.

10

plasticizing

12

electrical drive

14

hopper

16

gear pump

18

connection between plastifier and gear pump

20

connection between gear pump and discharge

22

discharge

24

actuating arm for discharge device

26

Fiber reservoir

28

feeding for fiber supply

30

discharge pipe

32

melt jet

34

When Use trained tool molding / receiving device

36

Robot arm actuator

38

inspection and control device

39

electrical connecting line

40

heating plate

41

electrical connecting line

42

electrical connecting line

44

electrical connecting line

50

Lower Mold half First Embodiment

52

Upper Mold half First Embodiment

54

recess for use

60

Lower Mold half Second Embodiment

62

Upper Mold half Second Embodiment

64

cavity

66

electrical conductive Ceramic as cavity surface

68

electrical supply line

69

Melt partial filling

Claims (17)

Plastic processing machine comprising - a plasticizing device ( 10 ) for producing a plastic melt from a starting material, - a discharge device ( 22 ), with the plasticizer ( 10 ) is fluidly connected and receives from the plastic melt, - an actuator ( 24 . 36 ) associated with the discharge device ( 22 ) is coupled to the discharge device ( 22 ) and - a closing unit ( 50 . 52 ; 60 . 62 ) for receiving a mold, wherein the closing unit ( 50 . 52 ; 60 . 62 ) is designed to carry out an embossing step, characterized in that the discharge device and the closing unit are designed to be able to bring the plastic melt in a not completely closed or located in the closed position tool. Plastics processing machine according to claim 1, characterized in that in the discharge device ( 22 ) or fluidly in front of the discharge device ( 22 ) a delivery unit ( 26 ) is provided for introducing filling, reinforcing and / or fibrous materials into the plastic melt, wherein the introduction device ( 26 ) the filling, reinforcing or fibrous materials from a supply device ( 28 ) receives. Plastics processing machine according to claim 2, characterized in that the discharge device ( 22 ) and / or the introduction unit ( 28 ) and / or the supply device ( 26 ) are formed such that the ratio of the fillers in relation to the plastic melt changeable, in particular controllable or regulated. Plastics processing machine according to one of the preceding claims, characterized gekenn characterized in that the plasticizing device ( 10 ) comprises a single or twin screw extruder. Plastics processing machine according to one of the preceding claims, characterized in that the actuating device ( 24 . 36 ) is designed such that the discharge device ( 22 ) is movable over the entire region of a mold half to be filled, in particular controlled or regulated movable. Plastics processing machine according to one of the preceding claims, characterized in that an insertable into the clamping unit molding tool ( 34 . 50 . 52 ) comprises at least two parts, and at least one part ( 34 ) can be removed as an insert from the closing unit or inserted into it. Plastics processing machine according to claim 6, characterized in that the removable molded part ( 34 ) is formed with a low heat capacity and a high thermal conductivity. Plastics processing machine according to one of the preceding claims, characterized in that the molding tool ( 60 ) is formed itself heated, in particular by applying an electrical voltage is heated. Plastics processing machine according to claim 8, characterized in that the molding tool ( 60 ) comprises an electrically conductive ceramic, which serves for heating when applying an electrical voltage. Plastics processing machine according to one of the preceding claims, characterized in that a control and monitoring device ( 38 ) and designed such that the filler content in the plastic melt can be changed depending on the position of the discharge to the mold. Plastics processing machine according to one of the preceding claims, characterized in that a position device for determining the position of the discharge device ( 22 ) is provided in relation to the mold. Method of operating a plastics processor Machine with the steps: - Making a plastic melt from a plastic starting material, - Spend the plastic melt to a discharge device, - Introduce a filler in the plastic melt on the way to the discharge or in the discharge device, - bring in the plastic melt in a not completely closed mold and - Pressing the plastic melt in a mold cavity by closing a Closing device. Method according to claim 12, characterized in that that the discharge device over a mold with simultaneous application of the plastic melt is moved. Method according to claim 12 or 13, characterized that the filler content while of the discharge process is varied. Method according to claim 14, characterized in that that the filler content in dependence of the position of the discharge device is changed to the mold. Method according to one of claims 12 to 15, characterized that the molding tool to a predetermined before filling Temperature is heated. Method according to one of claims 12 to 16, characterized that the temperature of the mold also after filling and during the embossing step changed becomes.