Method for producing a plastic moulded part
Patent Information
- Application Number
- EP2023710349
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-03-14
- Filing Date
- 2023-03-10
- Publication Date
- 2025-01-22
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for producing a plastic molded part
[0002] The present invention relates to a method for producing a plastic molded part and in particular a plastic molded part for optical applications.
[0003] Such plastic molded parts can be manufactured from a plastic film using high-pressure forming (also known as the Niebling process). During this high-pressure forming process, the plastic film is heated (often above its softening point) and then pressed against a mold using high pressure (up to 300 bar, preferably isostatically). This method allows for reproducible, contour-accurate molds (with tolerances of, for example, less than + / - 0.4 mm). Further details on this high-pressure forming process can be found, for example, in DE 10 2008 050 564 A1.
[0004] Since the plastic films used are typically manufactured using a flat film extrusion process, and the final surface structure (such as gloss and thickness) is created by rolling, anisotropic internal stresses can occur. The heating required for the described high-pressure forming process then has the disadvantage that these intrinsic anisotropic stresses are released due to the heating, which can lead to warping. Even slight waves / wrinkles during the heating process can result in the required accuracy of the mold being lost.
[0005] It is therefore an object of the invention to provide an improved method for producing a plastic molded part in which the disadvantages described above can be avoided as completely as possible.
[0006] The invention is defined in independent claims 1 and 9. Advantageous embodiments are specified in the dependent claims.
[0007] The clamping frame allows the plastic film to be fixed or clamped evenly in the region of the edge zone and in particular along a closed line around the first through-opening, thereby effectively preventing undesired warping during heating. The edge zone can, for example, be defined as the region of the upper side of the base frame that extends from the edge of the through-opening to a predetermined distance from the edge of the first through-opening. The edge zone can also be defined by being the region of the upper side of the base frame on which the plastic film rests and in which it is pressed against the upper side by the clamping frame when the plastic film covers the first through-opening.
[0008] The first and / or second through-opening may, in particular, be circular. However, an oval shape or any other shape is also possible.
[0009] The tensioning frame can press the plastic film against the top of the base frame along a closed path that encloses the first through opening.
[0010] In particular, the clamping frame can have an annular groove that encloses the second through-opening. A seal that presses against the plastic film can be located in the groove. In particular, the annular groove can press against the plastic film in an area that lies above the first through-opening.
[0011] The groove and / or the seal can be circular or any other ring shape, such as square, rectangular, oval, polygonal or the shape of any other closed path curve.
[0012] The base frame can have several protruding pins on its top. The clamping frame can have corresponding holes or adjustment holes. In step a), the clamping frame with its adjustment holes can be slid over the pins and thus placed on the plastic film.
[0013] Alternatively, the clamping frame can be positioned between the pins that serve as a stop for the clamping frame. In this case, the clamping frame can be designed without the corresponding bores or adjustment holes. Instead of pins, the stop function can also be performed with any other type of mechanical stop or stop.
[0014] stop element must be implemented.
[0015] Furthermore, the clamping frame can have a flat or non-flat underside that rests on the plastic film. The design of the non-flat underside can be implemented in such a way that a better fixation of the plastic film is achieved. For example, the clamping frame can have points, teeth and / or a rough surface on the underside in the area of the edge zone to fix the plastic film. The top side of the base frame can be flat or non-flat. The non-flat top side can be implemented with points, teeth and / or a rough surface. This can improve the fixation of the plastic film. Furthermore, a clamping means can be provided that applies a force to the clamping frame that presses the clamping frame against the base frame and thereby increases the clamping effect already exerted on the plastic film due to the weight of the clamping frame. The clamping means can be implemented by clamping elements, such as e.g.by means of a screw connection and / or one or more clamping levers, or also by means of magnetic force.
[0016] In the method according to the invention, in step c) there is a pressure chamber in which the forming of the plastic film is carried out.
[0017] To form the pressure chamber, a wall surrounding the tool presses the base frame against the plastic film and this film against the clamping frame, so that both the clamping frame is part of the pressure chamber and the base frame is part of the pressure chamber.
[0018] With the exception of the plastic film, the elements forming the pressure chamber are preferably made of metal. It is preferable to provide only one (usually annular) seal per parting plane between two metal surfaces of the metal elements (excluding the plastic film) to ensure tightness in this parting plane. Thus, the sequence metal-seal-metal, metal-seal-plastic film-metal, and metal-plastic film-seal-metal can be used to ensure tightness.
[0019] The annular seal can be circular, oval, square, rectangular, polygonal or the shape of any other closed trajectory curve.
[0020] All seals described can be made of a heat-resistant elastomer (such as fluororubber).
[0021] In step c), the tool can be provided with a contour, whereby the fluid pressure medium presses the plastic film against the contour for forming.
[0022] The forming in step c) is preferably carried out isostatically.
[0023] It is understood that the features mentioned above and those to be explained below can be used not only in the specified combinations, but also in other combinations or on their own, without departing from the scope of the present invention. The invention is explained in more detail below using exemplary embodiments with reference to the accompanying drawings, which likewise disclose features essential to the invention. These exemplary embodiments are for illustrative purposes only and are not to be interpreted as restrictive. For example, a description of an exemplary embodiment with a large number of elements or components should not be interpreted to mean that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components.Elements or components of different embodiments can be combined with one another unless otherwise stated. Modifications and variations described for one of the embodiments can also be applied to other embodiments. To avoid repetition, identical or corresponding elements in different figures are designated by the same reference numerals and are not explained more than once. The figures show:
[0024] Fig. 1 is a sectional view of an embodiment of a fixing unit 1;
[0025] Fig. 2 is a plan view of the fixing unit of Fig. 1;
[0026] Fig. 3 is a view of the underside 13 of the clamping frame 10 of Fig. 1;
[0027] Fig. 4 is a schematic representation of the device 20 according to the invention for
[0028] high pressure forming;
[0029] Fig. 5 is an enlarged sectional view of the fixing unit 1 positioned on a carriage 22 of the high-pressure forming device 20;
[0030] Fig. 6 is a schematic representation of the heating device 25 of the high-pressure forming device 20;
[0031] Fig. 7 to 9 are schematic representations of the high-pressure device 26 of the high-pressure deformation device 20 for explaining the isostatic high-pressure deformation of the plastic film 5;
[0032] Fig. 10 is a sectional view of the manufactured plastic molded part 50;
[0033] Fig. 11 is a sectional view of another embodiment of the fixing unit 1; Fig. 12 is a sectional view of another embodiment of the fixing unit 1, and
[0034] Fig. 13 is a plan view of the fixing unit of Fig. 12;
[0035] In the embodiment shown in Fig. 1, the fixing unit 1 for fixing a plastic film 5 for a device for high-pressure forming comprises a base frame 2 with a first through-opening 3 and an upper side 4.
[0036] The plastic film 5 is positioned on the upper side 4 of the base frame 2 (hereinafter also referred to as the base plate 2) in such a way that it covers the entire first through-opening 3 and rests on an edge zone 6 of the upper side 4 that delimits the first through-opening 3. The first through-opening 3 is circular, as can be seen, for example, from the top view in Fig. 2. Of course, other delimiting contours of the first through-opening 3 are also possible, such as square, rectangular, oval, or polygonal.
[0037] The base frame 2 has eight pins 7 arranged in a rectangle (here in a square) in the edge zone 6, which protrude upwards from the upper side 4, although other arrangements and / or a different number of pins 7 as well as other geometries as pins are also possible.
[0038] In the embodiment described here, the plastic film 5 is square in shape so that it can be placed on the top side 4 of the base frame 2 precisely in the area defined by the pins 7. Clear positioning can also be achieved using additional pins (or other geometries and / or recesses). This can be advantageous, for example, with pre-printed plastic films 5.
[0039] A clamping frame 10 is positioned on the plastic film 5 (Figures 1 and 2), which has a second circular through-opening 11 with a diameter that corresponds to the diameter of the first through-opening 3 of the base frame 2. The two diameters do not have to be the same size, but can also be different. Of course, other boundary contours of the second through-opening 11 are also possible, such as square, rectangular, oval or polygonal. The clamping frame 10 is also square in shape so that it can be positioned exactly in the area on the plastic film 5 delimited by the pins 7. The clamping frame 10 then rests with its underside 13 on the plastic film 5 and thereby presses it flatly onto the edge zone 6 of the top side 4 of the base frame 2.The edge zone 6 is thus the area of the upper side 4 which extends from the edge of the first through-opening 3 to the area delimited by the pins 7 on the upper side 4.
[0040] The pins 7 thus serve, on the one hand, to determine the position of the plastic film 5 on the base frame 2 and to determine the position of the clamping frame 10 on the plastic film 5. On the other hand, the pins 7 serve as a stop and ensure that the positions of the plastic film 5 and the clamping frame 10 relative to the base frame 2 and in particular relative to the first through opening 3 of the base frame 2 are securely maintained, even if the fixing unit 1 is moved in the high-pressure forming device, as described below.
[0041] The square design of the plastic film 5 and the clamping frame 10 is merely exemplary. Of course, other contours can also be realized. What is essential is the flat and preferably circumferential contact of the plastic film 5 with the upper side 4 of the base frame 2 due to the clamping frame 10 resting on the plastic film 5.
[0042] As can be seen in the sectional view of Fig. 1, the base frame 2 and the clamping frame 10 are designed such that when the plastic film 5 is fixed, the two through openings 3, 11 are aligned coaxially with each other.
[0043] As can be seen in particular from Fig. 3, the underside 13 of the clamping frame 10 has an annular groove 14 with a larger inner diameter than the diameter of the first through-opening 3. An annular seal 15 is located in the groove 14 and protrudes beyond the underside 13. The seal 15 can be made of a heat-resistant elastomer, such as FKM (fluororubber). As shown in Fig. 1, the seal 15 thus rests on the upper side of the plastic film 5 in an area outside the first through-opening 3.
[0044] In the embodiment described here, both the underside 13 and an upper side 16 of the clamping frame 10 are flat. The plastic film 5 is thus fixed by the weight of the clamping frame 10, with which it presses the plastic film 5 against the upper side 4 of the base frame 2. The clamping frame 10 can have a plate thickness of 2 mm - 50 mm, preferably 5 mm - 10 mm. The plate thickness of the clamping frame 10 can be selected in particular such that the weight of the clamping frame 10 is sufficient to ensure the desired fixation of the plastic film 5. The fixing unit 1 is designed for a device 20 for high-pressure forming, as shown schematically in Fig. 4.The high-pressure forming device 20 comprises a conveyor device 21 with a carriage 22 for receiving the fixing unit 1, a conveyor belt or a conveyor chain 23 and a drive 24, a heating device 25, a high-pressure device 26 and a control unit S for controlling the high-pressure forming device 20. The control unit S can, for example, have a processor P and a memory M.
[0045] In the illustration in Fig. 4 and the enlarged partial illustration in Fig. 5, the carriage 22 is in the loading / unloading position, with the complete fixing unit 1 already placed on the carriage 22 or in a recess 27 of the carriage 22. In the area of the recess 27, the carriage has a third through-opening 28 which is larger than the first and second through-openings 3, 11 and completely covers the first and second through-openings 3, 11, as can be clearly seen, for example, in the enlarged illustration in Fig. 5.
[0046] A fixing unit 1 fastened in this way on the carriage 22 can be transported by means of the conveyor device 21 into the heating device 25, in which, as schematically shown in Fig. 4 and 6, two controllable planar heat sources 29i and 292 are arranged. The two heat sources 29i and 292 are preferably arranged and / or designed such that they provide the same heating power. This can be achieved, for example, in the event that the planar heat sources 29i and 292 already provide the same heating power, by having them at the same distance from the plastic film 5 in a direction from one heat source 29i to the other heat source 292. In practice, however, differences can arise, for example due to convection, which are then compensated for by controlling the power of the two planar heat sources 29i and 292.
[0047] The heat sources 29i and 292 heat the plastic film 5 fixed in the fixing unit 1 above its softening point. Due to the clamping frame 10, the plastic film 5 is not heated with the same intensity in the area of the edge zone 6 as in the area of the through-opening 11, so that the film temperature in the edge zone generally remains below the softening point. This results in a circumferentially stabilized plastic film 5.
[0048] The thus heated plastic film 5 is then transported by the conveyor device 21 to the high-pressure device 26, in which high-pressure isostatic forming is performed by applying a fluid pressure medium. For this purpose, the high-pressure device 26 comprises a pressure chamber 30, which can be opened and closed, as described below. The pressure chamber 30 has a first and a second sub-chamber 31 and 32.
[0049] The first sub-chamber 31 forms a pressure bell and is typically arranged at the top, so that the open cavity 33 of the pressure bell 31 points downwards. Furthermore, the first sub-chamber 31 comprises a downward-facing, annular contact surface 34, the inner contour of which is circular here and preferably has the same diameter as the second through-opening 11 of the clamping frame 10. However, it is also possible for the diameter of the inner contour of the annular contact surface 34 to be slightly smaller or slightly larger than the diameter of the second through-opening 11 of the clamping frame 10. The inner contour of the annular contact surface can alternatively have a diameter that is larger than the diameter of the second through-opening 11. An annular seal 35 is arranged on the contact surface 34 (e.g., in an annular groove not shown), which protrudes from the contact surface 34. The annular seal 35 can, for example,It can be circular, oval, polygonal or have the shape of any other closed trajectory curve.
[0050] The first subchamber 31 contains a channel 36 that opens into the cavity 33 and through which a fluid pressure medium can be supplied and removed again, as indicated by the arrows P1 and P2. For this purpose, a schematically illustrated valve 37 is arranged to supply and discharge the fluid pressure medium.
[0051] The second sub-chamber 32 comprises a base plate 38, which supports the tool 39 (or mold 39) with the desired contour 40 for the plastic film 5. Furthermore, the second sub-chamber 32 comprises a chamber wall 41, which is spring-mounted on the base plate 38 and laterally encloses the tool 39. The springs 42 shown schematically are provided for the spring-mounted support.
[0052] The chamber wall 41 has an upwardly facing end 43 with a contact surface 45. An annular seal 18 is arranged on the contact surface 45 (e.g., in an annular groove not shown) and protrudes from the contact surface 45. The annular seal 18 can, for example, be circular, oval, polygonal, or can have the shape of another self-contained trajectory curve.
[0053] In the illustration shown in Fig. 7, the pressure chamber 30 is shown in its open position, in which the carriage 22 with the fixing unit 1 can be positioned between the two sub-chambers 31 and 32. As soon as the carriage 22 is accordingly positioned, the second sub-chamber 32 can be moved upwards in the direction of the first sub-chamber 31 via a lifting device 47, whereby the second sub-chamber 32 presses against the underside 17 of the base frame 2 by means of the contact surface 45 and thus lifts the base frame 2 with the plastic film 5 and the clamping frame 10 from the carriage 22 and presses it against the contact surface 34 of the first sub-chamber 31. This provides the desired sealing of the closed pressure chamber 30, as indicated by the arrows D1 and D2.At the same time, the tool 39 is moved upward relative to the chamber wall 41 by means of the lifting device 47, in that the base plate 38 is brought into contact with an underside of the wall 41 against the force of the springs 42. As a result, the tool 39, with its contour 40, is already in contact with the plastic film 5 (as shown in Fig. 8) or is at a slight distance from the plastic film 5.
[0054] In this closed position of the pressure chamber 30 shown in Fig. 8, the fluid pressure medium is guided into the cavity 33 via the channel 36, so that an overpressure is created which leads to an isostatic deformation of the plastic film 5, which is thereby pressed against the contour 40 of the tool 39.
[0055] Thereafter, the fluid pressure medium is discharged from the cavity 33 and, if necessary, the pressure chamber 30 is closed until the deformed plastic film 5 has cooled sufficiently.
[0056] After this deformation of the plastic film 5 has been carried out, the desired plastic molded part 50 is present and the pressure chamber 30 is brought back into its open position (Fig.
[0057] 9). The fixing unit 1 is then placed back on the carriage 22 and is transported back to the loading / unloading position together with the deformed plastic film 5. Thus, a plastic molded part 50 (Fig. 1) was formed from the plastic film 5 in the manner described.
[0058] 10) were manufactured.
[0059] During all movements of the carriage 22, the pins 7 serve to ensure that the plastic film 5 and the clamping frame 10 maintain their position.
[0060] Since the plastic film 5 is positioned in the fixing unit 1 both during heating and during deformation, the plastic film 5 is always fixed or clamped in the edge zone 6 around the entire first through-opening 3, so that distortion of the shape of the plastic film 5 during heating above the softening point and during deformation can be prevented as well as possible. When the plastic film 5, as shown in Fig. 8, is raised lying on the base frame 2, the desired fixation is achieved by the contact surface 45, which presses the plastic film 5 against the underside 13 of the clamping frame 10 by means of the base plate 2. Such distortion would occur in particular because the plastic films 5 used are usually produced via an extrusion process (e.g.
[0061] Flat film extrusion process) and further processed using rollers to adjust film thickness and surface quality. This leads to intrinsic anisotropic stresses in the material, which are released upon heating and would then lead to the undesirable warping in a previously known variant in which the plastic film 5 is merely placed on the base frame 2 and no clamping frame 10 is provided.
[0062] In the embodiment described so far, the plastic film 5 is fixed primarily by means of the weight of the clamping frame 10 lying on top. However, it is additionally or alternatively possible to achieve the desired fixation by means of points, teeth and / or a rough surface, wherein the points, teeth and / or the rough surface can be formed on the upper side 4 of the base frame 2 and / or on the underside 13 of the clamping frame 10. Furthermore, a mechanical screw connection or clamping (by means of, for example, a clamping lever, springs, etc.) can be implemented additionally or alternatively. Fixation by magnetic forces is also additionally or alternatively possible.
[0063] The plastic film can be, for example, a PC film (polycarbonate film). For example, the PC film can be Makrofol DE 1-1 from Covestro Deutschland AG in Germany. The layer thickness of the plastic film 5 (or the film piece 5) can, for example, be in the range from 10 pm to 3000 pm, from 12 pm to 2000 pm, from 100 pm to 2000 pm, from 150 pm to 1000 pm, from 125 pm to 1000 pm (or 175 pm to 1000 pm), from 125 pm to 750 pm, from 125 pm to 600 pm, from 150 pm to 650 pm, and from 250 pm to 600 pm, or from 200 pm to 500 pm. In particular, the layer thickness of the plastic film 5 can be in the range from 350 pm to 650 pm or from 375 pm to 500 pm.
[0064] During deformation in the high-pressure device 26, the fluid pressure medium can be supplied at 2 to 300 bar and preferably at 10 to 100 bar.
[0065] Further details on high-pressure forming can be found, for example, in DE 10 2008 050 564 A1, the content of which is hereby included.
[0066] The softening temperature of the PC plastic film 5 used can be in the range from 144 to 146°C. When heated above the softening temperature, a temperature of greater than 146°C and preferably less than 190°C is generated in the heating device 25. Thermoplastic polymers, such as polycarbonate, PMMA (polymethyl methacrylate), PA (polyamide), PS (polystyrene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), TAC (cellulose acetate), COP / COC (cycloolefin polymer or copolymer), can be used as material for the plastic film. Furthermore, reactive polymer precursors can also be used, which are partially or fully cured thermally or by radiation curing during the forming process or in a downstream process step. Examples of this can be found, among others, in the field of polyurethane chemistry.Furthermore, coated and / or pretreated films, coextrusion films, hybrid and / or composite films can be used.
[0067] After the described forming step, further steps can be performed to obtain a desired end product from the plastic molded part 50. In particular, a punching step, a coating step, etc., can be performed. Of course, it is also possible for the plastic molded part 50 itself to be the desired end product.
[0068] Since the fixing unit 1 is provided as a separate unit that is to be placed on the carriage 22 in the loading / unloading position, the fixing unit 1 can be loaded externally and then inserted as a unit into the high-pressure forming device 20 and removed again after forming. If the clamping frame 10 is designed as a pure support frame (e.g., with a sealing ring 15), installation into the fixing unit 1 and removal from the fixing unit 1 can be carried out quickly and easily without significantly affecting the existing process. The handling steps relating to the plastic film 5 are minimized, which also leads to less contamination.
[0069] However, it is also possible to arrange the base frame 2 already in the carriage 22 in the loading / unloading station and simply place the plastic film 5 and the clamping frame 10 in the manner described. After forming, the clamping frame 10 can be lifted off, and the resulting plastic molded part 50 can be removed.
[0070] Afterwards, a new plastic film 5 and the clamping frame 10 can be placed on top of it so that a further forming process can be carried out.
[0071] Furthermore, it is possible to automate the process, for example, by automating the placement of the plastic film 5 and the clamping frame 10 onto the base frame and the removal of the formed plastic molded part 50 after the forming process has been completed after the clamping frame 10 has been lifted off. Fig. 11 shows a modification of the fixing unit 1. In this modification, the plastic film 5 and the clamping frame 10 are placed onto the pins 7. For this purpose, the plastic film 5 has through-openings, and the clamping frame 10 has corresponding blind holes or through-bores.
[0072] Figures 12 and 13 show a modification of the fixing unit 1 in the same way as in Figures 1 and 2. In this modification, the base frame 2 has two through-openings 3i and 32. Similarly, the clamping frame 10 has two through-openings 111 and 112 as well as two seals 15i and 152. With such a fixing unit 1, the throughput during forming can be doubled, since two plastic molded parts 50 can always be produced. The device 20 for high-pressure forming is, of course, adapted accordingly for this purpose. Thus, the plastic film 5 can be heated in the heating device 25 such that the areas in both through-openings 111 and 112 of the plastic film are heated in the manner described. In the high pressure device 26, two pressure chambers 30 are then provided (one for each pair of through openings 3i, 111 and 32 and 112).
[0073] Of course, it is also possible to provide only one pressure chamber 30 for both pairs of through-holes 3i, 111 and 32, 112. Furthermore, identical or different tools 39 with identical or different contours 40 can be provided. Of course, more than two pairs of through-holes can also be provided.
Claims
Claims: A method for producing a plastic molded part, in which a) a plastic film (5) is placed on a base frame (2) having a first through-opening (3) such that the plastic film (5) completely covers the first through-opening (3) and lies on an edge zone (6) of a top surface (4) of the base frame (2) that limits the first through-opening (3), b) the plastic film (5) lying on the base frame (2) is heated, and c) the plastic film (5) lying on the base frame (2) and heated in step (b) is subjected to a fluid pressure medium such that the plastic film (5) is pressed against a tool (39) and thereby formed into the plastic molded part (50), characterized in that in step a) a clamping frame (10) having a second through-opening (1 1 ) is positioned on the plastic film (5) lying on the base frame (2) such thatthat the clamping frame (10) presses the plastic film (5) in the area of the edge zone (6) against the top (4) of the base frame (2) and thereby fixes it, and that the second through-opening (1 1 ) of the clamping frame (10) is at least partially opposite the first through-opening (3) of the base frame (2), wherein step b) is carried out with the plastic film (5) fixed between the base frame (2) and the clamping frame (10), and wherein in step c) a pressure chamber (30) is present in which the forming of the plastic film (5) is carried out, wherein to form the pressure chamber (30) a wall (41 ) surrounding the tool (39) presses the base frame (2) against the plastic film (5) and thereby presses the plastic film against the clamping frame (10), so that both the clamping frame (10) is part of the pressure chamber (30) and the base frame (2) is part of the pressure chamber (30). The method of claim 1, wherein in step c) the forming is carried out isostatically. The method of claim 1 or 2,in which, in steps a) and b), the tensioning frame (10) presses the plastic film (5) along a closed path that encloses the first passage opening (3) against the top (4) of the base frame (2).
4. Method according to one of the above claims, wherein the tensioning frame (10) has an annular groove (14) enclosing the second through-opening (11) in which a seal (15) is seated which presses against the plastic film (5) in steps a) and b).
5. Method according to one of the above claims, wherein the base frame (2) has several stop elements projecting from its upper surface (4). (7) and in step a) both the plastic film (5) and the tension frame (10) are positioned between the protruding stop elements (7).
6. Method according to one of the above claims, wherein the tensioning frame (10) has a flat underside (13) which rests on the plastic film (5) after step a) has been carried out.
7. Method according to any one of claims 1 to 5, wherein the tensioning frame (10) and / or the base frame (2) has points, teeth and / or a rough surface in the area of the edge zone (6) for fixing the plastic film (5).
8. Method according to one of the above claims, wherein a clamping means is provided which applies a force to the clamping frame (10) which presses the clamping frame (10) against the base frame (2) and thereby increases the clamping effect already exerted on the plastic film (5) due to the weight of the clamping frame (10).
9. High-pressure forming device (20) with a conveying device (21), a heating device (25) and a high-pressure device (26), wherein the conveying device (21) can transport a fixing unit (1) into the heating device (25) and the high-pressure device (26), wherein the fixing unit (1) comprises a base frame (2) having a first through-opening (3) and a top surface (4), and a clamping frame (10) having a second through-opening (11), wherein a plastic film (5) is placed on the base frame (2) such that it completely covers the first through-opening (3) and lies on an edge zone (6) of the top surface of the base frame (2) that delimits the first through-opening (3), and the clamping frame lies on the plastic film (5) such that the film is pressed against the top surface (4) of the base frame (2) in the area of the edge zone (6) and thereby fixed in place, and that the second through-opening (11) of the clamping frame (10) is at least partially opposite the first through-opening (3) of the base frame (2), and wherein the high-pressure device (26) is configured to pressurize the plastic film (5) heated by means of the heating device (25) in a pressure chamber (30) with a fluid pressure medium such that the plastic film (5) is pressed against a The tool (39) is pressed and thereby transformed into a plastic molded part (50), wherein, to form the pressure chamber (30), a wall (41) surrounding the tool (39) presses the base frame (2) against the plastic film (5) and thereby presses the film against the clamping frame (10), so that both the clamping frame (10) is part of the pressure chamber (30) and the base frame (2) is part of the pressure chamber (30).