METHOD AND DEVICE FOR PRODUCING MOULDED PARTS

Abstract

The present invention relates to a method and a device for producing moulded parts. Moulded parts of this type are used predominantly in automotive construction, for example as interior trim parts. The method and device according to the invention are intended to facilitate the reduction of sizing inaccuracies during high productivity and the flexible design of the cut region of the moulded part that is to be formed.

Claims

1. A method for producing molded parts, in particular decorative parts and/or trim parts for a motor vehicle interior, comprising: inserting and positioning a material blank in an open cavity of a device having a bottom mold and a top mold, at least one of which is displaceable relative to the other; closing the cavity and forming the material blank by relative movement of the bottom mold and the top mold towards one another; separating off a region of the material blank while the cavity is being closed; followed by further forming of the material blank by moving the bottom mold and the top mold towards one another and completing closing of the cavity; and molding onto a region adjacent to the cut region of the material blank by means of injection molding.

2. The method according to claim 1, wherein the separation of the material blank is performed before the cavity is closed completely, in dependence on a material retraction of the material blank that is to be achieved.

3. The method according to claim 1, wherein the separation of the region of the material blank and complete closing of the cavity of the device are performed in one stroke.

4. The method according to claim 1, wherein the material blank comprises a semi-finished fiber product.

5. The method according to claim 4, wherein the semi-finished fiber product is formed from a fiber composite, in particular a fiber/plastics material composite, for example a natural fiber/polypropylene mixture.

6. The method according to claim 1, wherein the cut edge and the rear ribs, dome and retainer are injection molded.

7. A device for producing molded parts, in particular decorative parts and/or trim parts for a motor vehicle interior, comprising: a bottom mold and a top mold for forming a material blank, at least one of which is displaceable relative to the other; a separating device preferably arranged on the top mold for separating the material blank; and wherein the separating device is so configured that, after the top mold and the bottom mold have been closed, an injection molding cavity is formed between the top mold and the bottom mold and the material blank.

8. The device according to claim 7, wherein the bottom mold and/or the top mold can be temperature-controlled.

9. The device according to claims 7, further comprising a clamping frame for positioning the material blank.

10. The device according to claim 9, wherein the clamping frame is in the form of a combined clamping and ejector frame.

11. The device according to claim 7, wherein the material blank comprises a semi-finished fiber product.

12. The device according to claim 11, wherein the semi-finished fiber product is formed from a fiber composite, in particular a fiber/plastics material composite, for example a natural fiber/polypropylene mixture.

13. The device according to claim 7, wherein the separating device for separating the material blank comprises a cutting plate or is formed integrally on the top mold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention is described in greater detail below by means of exemplary embodiments with reference to the accompanying figures.

[0035] FIG. 1 is a schematic cross-sectional side view of a first embodiment of a device for producing molded parts, wherein a tool is shown in an open state.

[0036] FIG. 1a is a detail view of FIG. 1.

[0037] FIG. 2 is a schematic cross-sectional side view of the device according to the first embodiment, wherein the tool is shown in an almost closed state.

[0038] FIG. 2a is a detail view of FIG. 2.

[0039] FIG. 3 is a schematic cross-sectional side view of the device according to the invention according to the first embodiment, wherein the tool is shown in a completely closed state.

[0040] FIG. 3a is a detail view of FIG. 3.

[0041] FIG. 4 is a schematic cross-sectional side view of a second embodiment of a device for producing molded parts, wherein a tool is shown in an open state.

[0042] FIG. 4a is a detail view of FIG. 4.

[0043] FIG. 5 is a schematic cross-sectional side view of the device according to the first embodiment, wherein the tool is shown in an almost closed state.

[0044] FIG. 5a is a detail view of FIG. 5.

[0045] FIG. 6 is a schematic cross-sectional side view of the device according to the first embodiment, wherein the tool is shown in a completely closed state.

[0046] FIG. 6a is a detail view of FIG. 6.

[0047] FIG. 7 is a cross-sectional view of the device according to the first or second embodiment with a gate and ejector system.

[0048] FIG. 8 is a top view of a bottom mold of the device according to the invention for producing molded parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0049] Preferred embodiments of the present invention are described hereinbelow with reference to the accompanying drawings. Individual features of the embodiments and modifications can each be combined with other embodiments in order to form further variants of the invention.

[0050] FIG. 1 is a schematic cross-sectional side view of the device 10 according to the invention for producing molded parts. The device 10 comprises a bottom mold or bottom tool 12 and a top mold or top tool 11 for forming a material blank 5.

[0051] In the case of the device 10 shown in FIG. 1, the device is shown in an open state. The material blank 5 is preferably a semi-finished fiber product, such as, for example, a pre-calibrated NFPP mat. In the embodiment shown, the top mold 11 is displaceable relative to the bottom mold 12. The device 10 further comprises a frame or a substructure 30 as well as a positioning device or displacing unit 20. A clamping frame 21 for positioning the material blank 5 is arranged on the positioning device 20 and is in the form of a combined clamping and ejector frame 21.

[0052] As can be seen in the detail in FIG. 1a, the material blank 5 is inserted into the bottom mold 12 and arranged on the clamping frame 21. The device 10 further comprises a separating device 15 arranged on the top mold 11 for separating off an edge region of the material blank 5.

[0053] The separating device 15 is in the form of a cutting tool, such as, for example, a cutting ring or a cutting plate (shown here), and has an overrun edge 15a. Since the cutting plate 15 in the present embodiment is removably fixed to the upper tool, the thicknesses of the cutting plate are variably adjustable, the time at which the cutting plate 15 engages with the region of the material blank 5 that is to be cut (here the edge region) depending on the thickness of the cutting plate 15. That is to say, when the cutting plate 15 has a greater thickness, the cutting plate (separating device) 15 cuts the material blank 5 at an earlier point in time during the operation of closing the upper and bottom mold 11, 12 than when the cutting plate 15 has a smaller thickness.

[0054] After the material blank 5 has been inserted into the bottom mold 12, the top mold 11 is moved towards the bottom mold 12 and the cavity of the tool 10 is thereby partially closed (see FIG. 2). The closing operation is carried out continuously according to the present embodiment but, from a technical point of view, it can also be carried out stepwise.

[0055] The material blank 5 is already partially formed during the closing operation. Before the cavity is completely closed, and thus also before forming of the material blank is complete, an edge region of the material blank 5 is separated off.

[0056] In FIG. 2a, the device (tool) 10 is shown in an almost closed state. It can clearly be seen here that the cavity of the device 10 is not yet completely closed, that is to say the top mold 11 has not yet been moved completely down onto the bottom mold 12. It is likewise apparent from FIG. 2a that the material blank 5 is separated at an overrun edge 15a when the device 10 is closed further and the overrun edge 15a runs over a trimming edge 12a of the lower tool 12. The cutting operation is apparent from considering FIG. 2/2a and the following FIG. 3/3a together.

[0057] In FIG. 3, the device 10 is shown in a completely closed state. In this state, a region of the material blank 5 that is to be cut has already been separated off. As can be seen in FIG. 3a in particular, the material blank 5 has retracted towards the center of the tool. As a result of the material retraction, an additional space forms between the edge of the material blank 5 and the bottom mold 12, so that it is possible to overmold the entire edge region of the material blank 5 around the cut edge 5a in an injection molding cavity or injection molding recess 17 arranged in the bottom mold.

[0058] A second embodiment of the present invention is shown in FIGS. 4, 4a, 5, 5a, 6 and 6a. Corresponding or similar components as in the first embodiment are identified by the same reference numerals, and reference is made to the above comments for a more detailed explanation of these components.

[0059] The second embodiment differs from the first embodiment substantially in that, instead of a cutting plate 15, a corresponding region of the top mold 11 is in the form of the separating device 15 so that an overrun edge 15a is formed as in the cutting plate of the first embodiment. In this case, the assembly outlay in producing the device was reduced because the separate separating device shown in the first embodiment is already integrated into the top mold 11. The further procedure when using the device 10 of the second embodiment corresponds to that of the first embodiment.

[0060] FIG. 7 is a sectional view of the device 10/10 according to the first or second embodiment. In the state shown, the tool is closed. Furthermore, an injection molding material S has already been injected behind the material blank 5 via the sprue runner 18. In a subsequent method step, the component so produced is pushed out of the bottom mold 12 by means of one or more ejector pins 40, so that it can be removed.

[0061] Finally, FIG. 8 shows a schematic top view of the bottom mold 12 of the device 10 according to the invention for producing molded parts. As can be seen in FIG. 8, the clamping frame 21 is arranged on the bottom mold 12. The size of the material blank 5 to be processed preferably corresponds approximately to the size of the clamping frame 21.

[0062] A plurality of sprue runners 18 are shown in the bottom mold 12, only some of these sprue runners being provided with reference numerals. A plurality of sprue runner ribs 18a are in communication with the sprue runners 18, which sprue runner ribs extend towards the trimming edge 12a, which comes into engagement with the overrun edge 15a, 15a, so that the injection molding material is fed to the injection molding cavity 17 (see e.g. FIG. 3).

[0063] In order to produce a molded part, a material blank 5 is inserted into the bottom mold 12. The cavity of the device 10 is then closed and the material blank 5 is thereby already partially formed. Before the cavity is closed completely, and thus also before forming of the material blank 5 is complete, a region (edge region) of the material blank 5 is separated off by the separating device 15, 15. Separation of the (edge) region of the material blank 5 is performed, in dependence on the material retraction of the material blank 5 that is to be achieved, before the cavity of the device 10 is closed completely.

[0064] Because the material blank 5 retracts towards the center of the tool as a result of the forming of the (edge) region, a peripheral gap forms between the trimming edge 12a and a recess end of the bottom mold 12. The region of the cut-off region of the material blank 5a is then overmolded with an injection molding material in the injection molding cavity 17.

LIST OF REFERENCE NUMERALS

[0065] 10, 10 Device for producing molded parts (tool)

[0066] 5 Material blank

[0067] 11 Top mold

[0068] 12 Bottom mold

[0069] 12a Trimming edge

[0070] 15, 15 Separating device

[0071] 15a, 15a Overrun edge

[0072] 17 Injection molding cavity

[0073] 18 Sprue runner for injection molding

[0074] 18a Sprue runner ribs

[0075] 20 Positioning device

[0076] 21 Clamping and ejector device

[0077] 30 Frame

[0078] 40 Ejector pin