Cover for a radar sensor for motor vehicles

Abstract

A cover for a radar sensor for motor vehicles, which has a wall provided with a three-dimensional relief structure, in which the wall including the relief structure is made of deep-drawn glass.

Claims

1. A method for producing a cover, the method comprising: reshaping a blank of flexible glass into a relief structure, wherein the blank forms a supporting substrate of the cover; wherein the cover is for a radar sensor for the motor vehicle, and includes a wall provided with a three-dimensional relief structure having multiple depressions and/or projections, the wall having the three-dimensional glass relief structure being made of deep-drawn glass, which is a reshaped flexible glass sheet, wherein a composition of the deep-drawn glass provides high transparency to high-frequency radar waves, wherein the high frequency radar waves are about 77 GHz, and wherein corner edges of the relief structure are rounded at least on the outwardly pointing side in relation to the radar sensor.

2. The method of claim 1, wherein the relief structure is imprinted and/or metallized on at least one side.

3. The method of claim 1, wherein a plastic layer is applied on one side of the blank with the aid of the injection-embossing method.

4. The method of claim 1, wherein a filler layer from a transparent casting compound which cures by cross-linking is formed on one side of the blank in the reaction-injection molding method.

5. The method of claim 1, wherein a filler layer from a transparent casting compound which cures by cross-linking is formed on one side of the blank, which is on a blank and non-metallized side, in the reaction-injection molding method.

6. The method of claim 1, wherein a plastic layer is applied on one side of the blank, which is on the imprinted and/or metallized side, with the aid of the injection-embossing method.

7. The method of claim 1, wherein the relief structure is imprinted on at least one side.

8. The method of claim 7, wherein the wall of deep-drawn glass has a continuous metallization layer on the imprinted side, which covers the imprinting.

9. The method of claim 1, wherein the relief structure is metallized on at least one side.

10. The method of claim 1, wherein a plastic layer is applied on at least one side of the wall of deep-drawn glass.

11. The method of claim 10, wherein the plastic layer forms a frame for the edge of the wall of deep-drawn glass.

12. The method of claim 10, wherein the plastic layer forms at least one mount for fastening the cover to a body shell part.

13. The method of claim 1, wherein a transparent filler layer is applied on one side of the wall of deep-drawn glass.

14. The method of claim 13, wherein the filler layer forms a continuous planar surface, which is provided with a scratch-proof enamel layer.

15. The method of claim 1, wherein a transparent filler layer is applied on one side of the wall of deep-drawn glass, the one side being a blank and non-metallized side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 a schematic section through a device for deep-drawing a transparent glass sheet.

(2) FIG. 2 the device as recited in claim 1, at the end of a deep-drawing step.

(3) FIG. 3 an enlarged section through a part of the deep-drawn glass sheet in the tool according to FIG. 2.

(4) FIG. 4 a section, analogous to FIG. 3, through the glass sheet following additional processing steps.

(5) FIG. 5 a schematic section through a device for injection-embossing a plastic layer on the rear side of the glass sheet.

(6) FIG. 6 a section through a device for applying a casting compound to a front side of the glass sheet.

(7) FIG. 7 a section through a finished cover for a radar sensor.

(8) FIG. 8 a front view of the cover according to FIG. 7.

DETAILED DESCRIPTION

(9) According to FIG. 1, the starting material for producing a cover for a motor vehicle radar sensor is a flexible glass sheet 10, which is drawn off a coil 12 in the form of an endless strip and passes between an upper tool 14 and a lower tool 16 of a punching and deep-drawing device 18. Upper tool 14 has a circumferential punching die 20, with the aid of which a circular blank, for example, is punched out of strip 10. The blanking waste is then wound onto a coil 22 again on the other side of device 18.

(10) On the underside, upper tool 14 has a system of projections 24, while lower tool 16 has a complementary system of depressions 26. When upper tool 14 is lowered, a blank 28 is punched out and deep-drawn by projections 24 and depressions 26, and reshaped in such a way that a three-dimensional relief structure 30 is obtained.

(11) Upper and lower tools 14, 16 are retained in exchangeable fashion in a machine bed 34 of device 18, so that covers that have different relief structures are able to be produced, which, for example, represent the company insignia of the individual motor vehicle manufacturer.

(12) As FIG. 3 illustrates, the surfaces of upper tool 14 and lower tool 16 facing the blank have coatings 36 made of PTFE (Teflon). This facilitates the deep-drawing operation. The edges of depressions 26 in lower tool 16 are rounded, so that no ugly marks are produced on the side of the blank that later forms the outside of the cover.

(13) When upper tool 14 is lifted up, deep-drawn blank 28 is ejected or possibly transferred together with lower tool 16 serving as workpiece support to an imprinting station (not shown here), where the raised parts of relief structure 32 are imprinted using a color enamel on the rear side facing the radar sensor of the subsequent cover (the top side in FIGS. 2 and 3), for instance in a pad printing process. One part of enamel layer 38 formed in this manner is illustrated in FIG. 4.

(14) In a further step, an opaque uninterrupted metallization layer 40 is applied to the entire rear side (top side) of blank 28, which, for example, has a thickness of at least 50 nm and may be made of indium, gold or tin, for reasons of radar transparency.

(15) For a subsequent processing step, the imprinted and metal-coated blank 28 is transferred to an injection-molding machine 42 having an embossing functionality, which is shown in FIG. 5 in a sectional view. In this step blank 28 may optionally also remain on lower tool 16 of the stamping and deep-drawing device serving as workpiece support, whereupon the injection-molding device is repositioned and suitably positioned with ejectors 44 in a bed 46 of the injection-molding device. Heating ducts 52 run through bed 46, a circumferential wall 48 as well as an embossing stamp 50 of the injection-molding machine, so that the injection-molding machine together with blank 28 are able to be heated to a temperature of 120 to 140 C., for example.

(16) Circumferential wall 48 and embossing stamp 50 form the boundary of a mold cavity 54 above blank 28, into which a preheated plastic melt is injected via a sprue 56, which may be at a pressure of less than 500 MPa. The plastic, for example, may be a polycarbonate or a duroplastic resin material.

(17) Punch 50 is set apart from the circumferential wall of injection-molding machine 42 by a punch gap 58 and drives deeper into the mold cavity during the injection-molding operation, so that the plastic melt is firmly pressed against the metallization layer of blank 28. This achieves a full-surface adhesion of the plastic to the metallization layer of the blank without air inclusions. The adhesion can be improved further by subjecting metallization layer 40 to a plasma treatment prior to the injection-molding procedure.

(18) Mold cavity 54 is configured in such a way that the circumferential edge of the blank is embedded in the plastic mass, and plastic layer 60 produced by the injection molding (FIGS. 6 and 7) forms radially projecting mounts 62 including fastening holes 64 at its edge, which make it possible to fix the cover in place on a radiator grille or some other body part of the motor vehicle (see also FIG. 8).

(19) After plastic layer 60 has cooled in injection-molding machine 42, cover 66 created by plastic layer 60 together with adhering blank 28 (FIGS. 7 and 8) is demolded, and lower tool 16 is ejected as well with the aid of ejectors 46 and returned for further use to stamping and deep-drawing device 18.

(20) Cover 66 may be used in the condition in which it leaves injection-molding machine 42. However, in a further step using the same or some other injection-molding machine, it is optionally possible to apply a filler layer to the front side (underside) of the blank by an injection-molding step, similar to filler layer 68 illustrated in FIGS. 6 and 7. As a minimum, this filler layer fills the depressions of the relief structure, but may form a continuous planar surface on the outer side of the cover; it is made of transparent plastic, such as a transparent polycarbonate, so that the relief structure remains visible. If needed, the planar surface of the filler layer is able to be coated by scratch-proof transparent enamel.

(21) FIG. 6 illustrates a further specific embodiment, in which filler layer 68 is produced in a casting machine 70 with the aid of a simple casting tool 72 by the reaction-injection molding method (RIM). Low-viscosity casting compounds, such as on the basis of polyurethane or acrylate, may be used for this purpose. An isocyanate and a polyol, for example, are combined in a mixer head 74, and injected into the heated tool at a pressure of less than 500 MPa. A cross-linked resin, which is very stable with regard to temperature and shape and which forms a scratch-proof planar surface that no longer needs to be enameled, is then produced in the mold cavity by way of a chemical reaction.

(22) Finished cover 66 obtained in such a manner is shown in a sectional view in FIG. 7 and in a front view in FIG. 8.