PRESS FOR MAKING A PART FROM FIBER COMPOSITE

Abstract

The invention relates to a press for producing a component from a fibre-composite material, which is designed as a membrane press, comprising a press frame (15), a press lower part (3) on which a mould (4) is arranged, a press upper part (5) having a pressure chamber (6) that can be sealed against the press lower part (3), one or more press cylinders (9) which are supported on the press frame and act on the press upper part (5) and/or the press lower part (3), a membrane (11) that can be tensioned over the mould (4), a vacuum pump (12) with which a vacuum can be generated on a side of the membrane (11), for example on the underside, characterised in that the press frame is designed as a C-frame with an upper horizontal C-arm, a lower horizontal C-frame and a vertical C-base.

Claims

1. A press for making a part from fiber composite, further comprising: a C-shaped press frame having an upper horizontal leg, a lower horizontal leg, and a vertical C-base extending between the legs, a mold, a press lower element on one of the legs and against/on mold is supported, a press upper element on the other of the legs and having a pressure case that can be sealed against the press lower element, press cylinders supported on the press frame and acting on the press upper element or on the press lower element, a membrane stretchable over or against the mold, and a vacuum pump that can create a subatmospheric pressure on one side of the membrane.

2. The press defined in claim 1, wherein the C-shaped frame consists of a plurality of C-frames provided one behind the other and each being C-shaped.

3. The press defined in claim 2, further comprising: clamping elements securing together the C-frames.

4. The press defined in claim 1, wherein the press cylinders are supported on the upper C-leg and act upon the movable press upper element as a throughgoing beam, and that the press lower element is mounted fixedly on the lower C-leg as a press table.

5. The press defined in claim 1, wherein the press lower element or the press upper element are heatable.

6. The press defined in claim 1, wherein the mold or a base plate having the mold or forming the mold is heatable.

7. The press defined in claim 1, wherein the pressure case is heatable.

8. The press defined in claim 1, wherein the membrane is made of silicone.

9. The press defined in claim 1 wherein the membrane is secured to the press upper element in an elastically biased manner so as to be clamped into the pressure case.

Description

[0044] The invention is described in further detail below with reference to a schematic drawing that illustrates only one embodiment. In the figures:

[0045] FIG. 1 is a simplified view of a membrane press according to the invention,

[0046] FIG. 2 shows the press of FIG. 1 in another functional position,

[0047] FIG. 3 shows a modified embodiment of the press according to FIG. 1,

[0048] FIG. 4 shows the press of FIG. 3 in another functional position,

[0049] FIG. 5 shows a first embodiment of a process for shaping a multilayer organic sheet, and

[0050] FIG. 6 shows a second embodiment of a process for shaping a multilayer organic sheet,

[0051] FIG. 7 is a perspective view of a press according to the invention with C-frame,

[0052] FIG. 8 is a front view of the object according to FIG. 7, and

[0053] FIG. 9 is a side view of the press according to FIG. 7.

[0054] The figures show a membrane press 1 for making a part from fiber composite. In such a membrane press, a part is manufactured from fiber composite by shaping a thermoplastic semifinished product, for example an organic sheet 2. Here, the membrane press 1 has a lower element 3 formed as a press table supporting a mold 4 that is a negative of the part to be manufactured. Moreover, the press 1 has an upper element 5 that has a hood-like pressure case 6 that can be sealed against the lower element 3. For this purpose, the lower, annular front edge 7 of the pressure case 6 that can be placed on the press table is provided with a circumferential seal 8. A press cylinder 9 acts on the upper element 5; here, the piston 10 of the press cylinder 9 is connected to the pressure case 6 so that the pressure case 6 is pressed by the cylinder 9, more particularly the piston 10 thereof, against the lower element 3. Moreover, the membrane press 1 is equipped with an elastic membrane 11 that can be stretched over the mold 4. Furthermore, a vacuum pump 12 is provided that here is connected to the lower element 3. Moreover, a superatmospheric pressure pump 13 can be optionally provided that here is connected to the upper element 5 and/or to the pressure case 6.

[0055] To shape an organic sheet 2, it is placed on the mold 4, and the membrane 11 is flexed and stretched over the mold 4 on top of the organic sheet 2.

[0056] The organic sheet is deformed so as to deform the part by applying a subatmospheric pressure by the vacuum pump 12 to the face of the membrane 11 facing the mold 4 and by applying a superatmospheric pressure by a superatmospheric pressure pump 13 to the face turned away from the mold 4, so that the organic sheet 2 is shaped against the mold to form the part.

[0057] The organic sheet 2 is heated before being placed into the press 1. Moreover, the mold 4 or at least its surface facing the organic sheet 2 is heated before and/or during the deformation. Finally, it is advantageous if the fluid medium that applies superatmospheric pressure to the membrane is heated. To achieve this, a heater 14 is shown schematically in the figures. Heaters for heating the organic sheet and for heating the mold are not shown.

[0058] FIG. 1 shows a first embodiment of such a membrane press in which the membrane 11 is secured to the lower element 3 and stretched over the mold 4. FIG. 1 shows the press after the organic sheet 2 has been placed onto the mold 4 and the membrane 11 has been stretched over the mold 4 with interposition of the organic sheet 2. Moreover, after placement of the organic sheet 2 and after the stretching of the membrane 11 on the lower element 3, the upper element 5 is lowered and sealed off. The subatmospheric pressure can be generated using the vacuum pump 12 before and/or after lowering of the upper element. After the upper element 5 has been lowered and sealed against the lower element 3, the superatmospheric pressure is applied to the interior of the pressure case 6. The compressive force that holds the membrane press closed as the internal pressure increases is increased successively with rising of the internal pressure and thus adapted thereto. FIG. 2 shows the press after superatmospheric pressure and subatmospheric pressure have built up, with the deformed organic sheet 2.

[0059] FIGS. 3 and 4 show a modified embodiment of such a membrane press in which the membrane is not secured to the lower element 3, but rather to the upper element 5, namely to the pressure case 7 [6] thereof, and elastically biased. After placement of the organic sheet 2 onto the mold 4, the pressure case 6 is lowered and, at the same time, the membrane is stretched over the mold with interposition of the organic sheet 2 (FIG. 4). After the press has been closed, the subatmospheric pressure and the superatmospheric pressure are built up so that the organic sheet 2 is deformed and the part made.

[0060] The organic sheet 2 can be composed of a plurality of individual organic sheet layers 2a that are placed together to form the organic sheet 2 and deformed in the press. The geometry of the layers 2a can be coordinated with one another such that the individual layers 2a are offset relative to one another during deformation, thereby altering the edge geometry of the part. This option is illustrated in FIGS. 5 and 6. According to FIG. 5, the individual layers 2a are placed together to form an organic sheet 2 with square edges. During deformation, the individual layers are offset relative to one another, so that a part with beveled edges is made.

[0061] By contrast, FIG. 6 shows an embodiment in which the individual layers 2a of the organic sheet 2 are not flush with one another, but rather form an angled edge so that a part with a square edge without a bevel is then created during deformation.

[0062] The invention will be explained particularly with reference to FIGS. 7 to 9. These figures show that the press frame 15 is C-shaped and has an upper C-leg 16, a lower C-leg 17, and a vertical C-base 18 that connects the horizontal legs 16, 17 to one another. The press frame 15 has a frame construction consisting of a plurality of C-shaped press frames 19, with each C-frame 19 also being C-shaped. Each C-frame 19 consists of one or more (one-piece) frame plates. The individual C-frames 19 are clamped together by clamping elements, such as tension rods 20, so as to be one behind the other in the longitudinal direction L.

[0063] FIGS. 7 to 9 show an embodiment of such a membrane press as a downstroke press. The press upper element 5 is thus designed as a throughgoing beam to which the pressure case 6 is secured. The press lower element 3 is formed as a press table, with this press table 3 spanning over the lower C-leg 16 and/or the C-frame thereof. A plurality of press cylinders 9 are provided that are secured to and supported on the upper C-leg 16 and operate on the movable throughgoing beam 5, by virtue of the fact that the plungers 10 of the press cylinder 9 are connected to the press upper element 5 and thus for example to the throughgoing beam.

[0064] In the illustrated embodiment, the press cylinders 9 are in a matrix or in a grid composed of several rows, with three rows provided in this embodiment, each of which extends over the entire length of the press. A plurality of press cylinders 9, for example three press cylinders, are associated with each C-frame 19. In this embodiment, three press cylinders 9 are supported on each C-frame 19. Moreover, it can be seen in the figures that, in addition to the press cylinders 9, retraction cylinders 21 can also be provided.

[0065] The press cylinders 9 can thus be formed in principle as single-acting cylinders that apply the pressing forces. The press cylinders can then be retracted by the retraction cylinders 21 and the press thus opened. Optionally, however, the pressing cylinder 9 can also be formed as a double-acting cylinder, in which case retraction cylinders can be omitted. However, the use of retraction cylinders can also be advantageous when double-acting cylinders are used.

[0066] In the embodiments shown in FIG. 9, the unillustrated membrane 11 is clamped to the pressure case 6. The throughgoing beam 5 is heatable, as is the press table 3. Furthermore, the pressure case 6 and also the base plate are heatable, with the base plate constituting the die and thus the mold 4 in the illustrated embodiment. In principle, however, it also lies within the scope of the invention for the mold or the die to be on such a base plate.

[0067] The figures have been described with reference to the preferred use of organic sheets and/or organic sheet layers. However, other thermoplastic, semifinished (fiber composite) products and, in particular, semifinished products composed of a plurality of individual layers placed loosely (in non-consolidated form) into the press can also be processed in the manner shown.