The disclosure relates to a method for producing an optical element, wherein a blank of transparent material is heated and/or provided and, after heating and/or after being provided between a first mold and at least one second mold, is press molded, for example on both sides, to form the optical element.
Such a method is disclosed, for example, in WO 2019/072325 A1 and WO 2019/072326 A1.
In addition to requirements for special contour fidelity and precise optical properties, the desire to press headlight lenses from borosilicate glass or glass systems similar to borosilicate glass has manifested itself in order to achieve increased weather resistance or hydrolytic resistance (chemical resistance). Standards or assessment methods regarding hydrolytic resistance (chemical resistance) are, for example, Hella standard test N67057 and climatic test/humidity frost test. High hydrolytic resistance, for example, is also classified as type 1. In the light of the requirement for borosilicate glass headlight lenses having corresponding hydrolytic resistance, the task arises of pressing headlight lenses from borosilicate glass or similar glass systems with the same hydrolytic resistance (chemical resistance). In departure from this task, an alternative method is proposed for producing an optical element or headlight lens from non-borosilicate glass and/or from soda-lime glass.
U.S. Pat. No. 7,798,688 B2 discloses a projection headlight having a headlight lens and having a light source, wherein a surface intended to face away from the light source of the projection headlight comprises a layer comprising an aluminum concentration that is greater than an aluminum concentration inside the headlight lens.
DE 10 2006 034 431 A1 discloses a process for the surface finishing of alkali-containing glasses, wherein hot surfaces are brought into contact with aluminum chloride compounds from the vapor phase. According to DE 10 2006 034 431 A1, contacting the hot glass surfaces with aluminum chloride dissolved in organic solvent, such as for example methanol, leads to improved surface properties. It is said to be advantageous if the contact of the glass surfaces with aluminum chloride compounds from the vapor phase takes place at lowered oxygen partial pressure. In contrast to treatment from the vapor phase, high amounts of energy could be removed from the glass surface in a short time by aqueous aluminum chloride solutions when they come into contact with a hot glass surface due to the heat of vaporization of the water at the glass surface, with any side effects that occur, such as strength reduction and stress-induced damage to the surface, leading to unacceptable properties. In addition, organic solvents for aluminum chloride such as methanol or ethanol would be ruled out for the skilled person, since their combustion would considerably reduce the oxygen partial pressure, but oxygen would be required for the incorporation of the aluminum into the glass surface. In a departure from this insight, contacting the hot glass surface with aluminum chloride dissolved in organic solvent, such as methanol, would result in improved surface properties.
Compared to the surface treatment described in DE 10 2006 034 431 A1 for bottles with aluminum chloride and its solution in methanol, the teaching of EP 2 043 962 B1 sets out the need for a more durable surface when producing flat glass in a more efficient manner. This need is met in EP 2 043 962 B1 in that, when producing soda-lime-silicate based glass, the glass strip formed from the melt is passed to an annealing lehr, wherein the main surface of the glass strip being applied with aluminum chloride before the annealing lehr at a temperature between 540° C. and 850° C. by applying a mixture of AlCl3 and at least one solvent to the surface of the glass strip, the mixture comprising 5-10% aluminum chloride and the solvent comprising ethanol.
The disclosure relates to a method for producing an optical element or a headlight lens according to the claims, wherein, among other things, it is provided that a blank of non-borosilicate glass and/or of soda-lime glass (soda-lime silicate glass) is heated and/or provided and, after heating and/or after being provided between a first mold, for example for molding and/or for press molding a first optically effective surface of the optical element, and at least one second mold, for example for molding and/or for press molding a second optically effective surface of the optical element, is press molded, for example on both sides, to form the optical element, wherein the first optically effective surface and/or the second optically effective surface (after the molding) is sprayed with a surface treatment agent.
The disclosure relates to a method for producing an optical element or a headlight lens according to the claims, wherein, among other things, it is provided that a blank of non-borosilicate glass and/or of soda-lime glass (soda-lime silicate glass) is heated and/or provided and, after heating and/or after being provided between a first mold, for example for molding and/or for press molding a first optically effective surface of the optical element, and at least one second mold, for example for molding and/or for press molding a second optically effective surface of the optical element, is press molded, for example on both sides, to form the optical element, wherein the first optically effective surface and/or the second optically effective surface (after the molding) is sprayed with a surface treatment agent. Spraying and/or misting in the sense of the present disclosure comprises for example nebulizing, fogging and/or (the use of) spray. Spraying and/or misting within the meaning of the present disclosure particularly means nebulizing, fogging and/or (the use of) spray.
In contrast to the treatment of hollow glass or flat glass disclosed in DE 10 2006 034 431 A1 and EP 2 043 962 B1, the present disclosure relates to the treatment of optically effective surfaces. Here, special requirements apply to cooling, since not only mechanical damage, such as cracks, could lead to unusability, but also internal stresses caused by too rapid cooling. It is therefore all the more surprising that hot optically effective surfaces can be successfully treated in a suitable manner by nebulizing or fogging or by using a spray in order to increase their hydrolytic resistance.
Soda-lime glass within the meaning of this disclosure comprises for example
60 to 75 wt. % SiO2 and
3 to 12 wt. % CaO,
or
70 to 75 wt. % SiO2 and
3 to 12 wt. % CaO.
Soda-lime glass within the meaning of this disclosure comprises for example
60 to 75 wt. % SiO2,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO,
or
70 to 75 wt. % SiO2,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO.
Soda-lime glass within the meaning of this disclosure comprises for example
60 to 75 wt. % SiO2,
3 to 12 -wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO,
or
70 to 75 wt. % SiO2,
3 to 12 wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO.
Soda-lime glass within the meaning of this disclosure comprises for example
0.2 to 2 wt. % Al2O3,
60 to 75 wt. % SiO2,
3 to 12 wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO,
Soda-lime glass within the meaning of this disclosure comprises for example
0.2 to 2 wt. % Al2O3,
0.1 to 1 wt. % Li2O,
60 to 75 wt. % SiO2,
3 to 12 wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO,
or
0.2 to 2 wt. % Al2O3,
0.1 to 1 wt. % Li2O,
70 to 75 wt. % SiO2,
3 to 12 wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO,
Soda-lime glass within the meaning of this disclosure comprises for example
0.2 to 2 wt. % Al2O3,
0.1 to 1 wt. % Li2O,
0.3, for example 0.4, to 1.5 wt. % Sb2O3,
60 to 75 wt. % SiO2,
3 to 12 wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO,
such as DOCTAN®, or
0.2 to 2 wt. % Al2O3,
0.1 to 1 wt. % Li2O,
0.3, for example 0.4, to 1.5 wt. % Sb2O3,
70 to 75 wt. % SiO2,
3 to 12 wt. % Na2O,
3 to 12 wt. % K2O and
3 to 12 wt. % CaO.
It may be provided that at least one optically effective surface is fire-polished before the treatment with surface treatment agent. In one embodiment it is for example provided that only the underside is fire-polished. This is provided for example in connection with a configuration of the lower optically effective surface as a planar surface. It has been found suitable, when fire polishing is provided, a waiting time to be allowed to elapse before the surface is exposed to the surface treatment agent. The waiting time is for example at least two seconds, for example at least three seconds, for example at least four seconds. In an embodiment, the fire polishing takes no longer than three seconds, for example no longer than two seconds. Waiting times or holding times can be at least 20 s, for example, but for example no more than 50 s, for example for large lenses.
Surface treatment agent within the meaning of this disclosure comprises for example AlCl3, for example AlCl3*6H2O (dissolved in solvent and/or H2O), suitable mixing ratios being taken from DE 103 19 708 A1 (e.g.
According to one embodiment, the surface treatment agent comprises, based on the total mass of the surface treatment agent, 25 to 65% by weight (for example 35 to 55% by weight) of water, 30 to 70% by weight (for example 40 to 60% by weight) of potassium phosphate, 1 to 8% by weight (for example 2 to 6% by weight) of sodium phosphate and 0.001 to 0.010% by weight (for example 0.002 to 0.006% by weight) of aluminum, the constituents adding up to no more than 100%. In another embodiment, the surface treatment agent comprises 35 to 65% by weight or 25 to 55% by weight water, based on the total mass of the surface treatment agent. According to another embodiment, the surface treatment agent comprises 40 to 70% by weight or 30 to 60% by weight potassium phosphate. According to another embodiment, the surface treatment agent comprises 2 to 8% by weight or 1 to 6% by weight sodium phosphate. According to another embodiment, the surface treatment agent comprises 0.002 to 0.010% by weight or 0.001 to 0.006% by weight aluminum.
In an embodiment, the first optically effective surface and the second optically effective surface are sprayed with the surface treatment agent at least partially simultaneously (overlapping in time).
In an embodiment, the temperature of the optical element and/or the temperature of the first optically effective surface and/or the temperature of the second optically effective surface when sprayed with surface treatment agent is not less than TG or TG+20K, where TG denotes the glass transition temperature.
In an embodiment, the temperature of the optical element and/or the temperature of the first optically effective surface and/or the temperature of the second optically effective surface when sprayed with surface treatment agent is not greater than TG+100K. In contrast to the high temperatures described in EP 2 043 962 B1, the good piece yield could be improved at lower temperatures below TG+100K (but above TG), so that this temperature range is particularly suitable for surface treatment in the aforementioned sense in the context of industrial production.
In an embodiment, the surface treatment agent is sprayed onto the optically effective surface as a spray agent, wherein the surface treatment agent forms droplets whose size and/or whose average size and/or whose diameter and/or whose average diameter is not greater than 50 μm.
In an embodiment, the surface treatment agent is sprayed onto the optically effective surface as a spray agent, wherein the surface treatment agent forms droplets whose size and/or whose average size and/or whose diameter and/or whose average diameter is not smaller than 10 μm.
In an embodiment, the surface treatment agent sprayed is mixed with compressed air. In an embodiment, compressed air is used to generate a spray for the surface treatment agent, for example in conjunction with a mixing nozzle or a two-substance nozzle. In an embodiment, the surface treatment agent is sprayed mixed with gas. In an embodiment, a gas or gas mixture (for example in connection with a pressure of at least two bar), for example in connection with a mixing nozzle or a two-substance nozzle, is used to generate a spray for the surface treatment agent. For example, the gas is mixed with the surface treatment agent under pressure (e.g. at least two bar or at least three bar). For example, the gas is mixed with the gas (immediately) prior to impingement on the optically effective surface. In one embodiment, the gas may be or comprise nitrogen and/or carbon dioxide.
In an embodiment, spraying of the optically effective surface with the surface treatment agent is carried out prior to cooling of the optical element in a cooling path for cooling in accordance with a cooling regime.
For example, it is provided that residues from the surface treatment process are removed, for example washed away. This may for example be carried out using water, without the addition of cleaning agents. The optical elements may have a (white) precipitate, for example the reaction product, after treatment with the surface treatment agent. For example, VE-water can be used to clean the optical elements. VE water is demineralized water. The abbreviation VE stands for “vollentsalzt (fully demineralized)”. Cleaning can be carried out, for example, at a water temperature of 60° C. of the VE-water. There is no need to use a detergent such as CEROWEG, which is known from WO 2019 243 343 A1.
For example, it is envisaged that the optical element or lens has a transmission of greater than 90% after washing and/or removal of residues from the surface treatment process.
In an embodiment, an optically effective surface is sprayed with the surface treatment agent for no longer than 4 seconds. For example, an optically effective surface is sprayed with the surface treatment agent for no longer than 3 seconds, for example no longer than 2 seconds, for example no longer than one second. For example, spraying is carried out until the optically effective surface is sprayed with no less than 0.05 ml of surface treatment agent and/or with no more than 0.5 ml, for example 0.2 ml of surface treatment agent.
It is for example provided that the headlight lens or a headlight lens according to the disclosure on the surface after being sprayed with surface-treatment agent consists of at least 90%, for example at least 95%, for example (substantially) 100%, of quartz glass, produced by crosslinking of oxygen ions with silicon ions on the optically effective surface. It is for example provided that the amount of crosslinking of oxygen ions to silicon ions on the optically active surface of the headlight lens or the optical element after the spraying can be represented by the relationship
and in further example, can be represented by the relationship
In the above, Q(3) denotes 3 oxygen ions crosslinking at tetrahedron corners of a silicon ion and Q(4) denotes 4 oxygen ions crosslinking at tetrahedron corners of a silicon ion. The proportion of quartz glass decreases from the optically effective surface towards the interior of the headlight lens or optical element, wherein, at a depth (distance from the surface) of 5 μm, it is for example provided that the proportion of quartz glass is at least 10%, for example at least 5%. It is for example provided that the amount of the crosslinking of oxygen ions to silicon ions at a depth of 5 μm below the optically effective surface of the headlight lens or the optical element can be represented by the relationship:
and in further example, can be represented by the relationship:
It is for example provided that the proportion of quartz glass at a depth (distance from the surface) of 5 μm is no greater than 50%, for example no greater than 25%. It is for example provided that the amount of the crosslinking of oxygen ions to silicon ions at a depth of 5 μm below the optically effective surface of the headlight lens or the optical element after the spraying can be represented by the relationship:
and in further example, can be represented by the relationship:
It may be provided that (in addition) the concentration of sodium ions in the interior of the lens is higher than in the near-surface region. Near-surface in the sense of the present disclosure may for example mean a depth of no greater than 5 μm. It may be provided that (in addition) the concentration of aluminum ions is lower inside the lens than in the near-surface region. It may be provided that during the treatment with surface treatment agent, ion exchange between ions in the glass or its near-surface region and the surface treatment agent occurs to some extent.
In an embodiment the first mold is moved by means of an actuator for moving the first mold by the first mold and the actuator being connected by means of a first movable guide rod and at least one second movable guide rod, for example at least one third movable guide rod, wherein the first movable guide rod is guided in a recess of a fixed guide element and the second movable guide rod is guided in a recess of the fixed guide element and the optional third movable guide rod is guided in a recess of the fixed guide element, wherein it is for example provided that the deviation of the position of the mold orthogonally to the movement direction of the mold from the target position of the mold orthogonally to the movement direction of the mold is no greater than 20 μm, for example no greater than 15 μm, for example no greater than 10 μm.
In an embodiment, the at least second mold is moved by means of an actuator for moving the second mold in a frame, which comprises a first fixed guide rod, at least one second fixed guide rod and, for example, at least one third fixed guide rod, wherein the first fixed guide rod, the at least second fixed guide rod and the optional at least third fixed guide rod are connected at one end by an actuator-side fixed connector and at the other end by a mold-side fixed connector, wherein the at least second mold is fixed to a movable guide element which comprises a recess through which the first fixed guide rod is guided, a further recess through which the at least second fixed guide rod is guided and optionally a further recess through which the optional third fixed guide rod is guided, wherein it is for example provided that the deviation in the position of the mold orthogonally to the movement direction of the mold from the target position of the mold orthogonally to the movement direction of the mold is no greater than 20 μm, for example no greater than 15 μm, for example no greater than 10 μm.
In an embodiment, it is for example provided that the first mold is moved by means of an actuator for moving the first mold in that the first mold and the actuator for moving the first mold being connected by means of a first movable guide rod and at least one second movable guide rod, for example at least one third movable guide rod, wherein the first movable guide rod being guided in a recess of a fixed guide element, the second movable guide rod being guided in a recess of the fixed guide element, and the optional third movable guide rod being guided in a recess of the fixed guide element.
In an embodiment it is provided that the fixed guide element is identical to the mold-side fixed connector, or is indirectly or directly fixed thereto.
In an embodiment the first mold is a lower mold and/or the second mold is an upper mold.
In an embodiment it is provided that, before pressing, the blank is placed on an annular or free-form support surface of a carrier body having a hollow cross section, and is heated on the carrier body, for example such that a temperature gradient is established such that the blank is cooler in its interior than on its outer region. It is for example provided that the support surface is cooled by means of a cooling medium flowing through the carrier body, wherein it is for example provided that the support surface spans a base surface which is not circular. In this case, a geometry of the support surface or a geometry of the base surface of the support surface is for example provided which corresponds to the geometry of the blank (which is to be heated), wherein the geometry is selected such that the blank rests on the outer region of its underside (underside base surface). The diameter of the underside side or the underside base surface of the blank is at least 1 mm greater than the diameter of the base surface spanned (by the carrier body or its support surface). In this sense, it is for example provided that the geometry of the surface of the blank facing the carrier body corresponds to the support surface or the base surface. This for example means that, after the forming process or press molding, the part of the blank resting on the carrier body or contacting the carrier body during heating is arranged in an edge region of the headlight lens which lies outside the optical path and which rests for example on a transport element (see further below) or its (corresponding) support surface.
An annular support surface may comprise small discontinuities. Within the meaning of this disclosure, a base surface is for example an imaginary surface (in the region of which the blank resting on the carrier body is not in contact with the carrier body), which lies in the plane of the support surface and is surrounded by this support surface, plus the support surface. It is for example provided that the blank and the carrier body are coordinated with one another. This is for example understood to mean that the edge region of the blank rests on the carrier body on its underside. An edge region of a blank can be understood to mean the outer 10% or the outer 5% of the blank or its underside, for example.
In the sense of the disclosure, a blank is for example a portioned glass part or a preform or a gob.
An optical element in the sense of the disclosure is for example a lens, for example a headlight lens or a lens-like freeform. An optical element in the sense of the disclosure is, for example, a lens or a lens-like free-form comprising a, for example, circumferential, interrupted or interrupted circumferential supporting edge. An optical element in the sense of the disclosure may be, for example, an optical element as described, for example, in WO 2017/059945 A1, WO 2014/114309 A1, WO 2014/114308 A1, WO 2014/114307 A1, WO 2014/072003 A1, WO 201 3/1 7831 1 A1, WO 2013/170923 A1, WO 2013/159847 A1, WO 2013/123954 A1, WO 2013/135259 A1, WO 2013/068063 A1, WO 2013/068053 A1, WO 2012/130352 A1, WO 2012/072187 A2, WO 2012/072188 A1, WO 2012/072189 A2, WO 2012/072190 A2, WO 2012/072191 A2, WO 2012/072192 A1, WO 2012/072193 A2, PCT/EP2017/000444. Each of these documents is incorporated by reference in its entirety. The claimed method is for example applicable to non-symmetrical headlight lenses or to non-rotationally symmetrical headlight lenses. For example, the claimed method is applicable to headlight lenses with non-symmetrical contours or non-rotationally symmetrical contours. For example, the claimed method is applied to headlight lenses with deterministic surface structures, such as disclosed in WO 2015/031925 A1, and for example with deterministic non-periodic surface structures, such as disclosed in DE 10 2011 114 636 A1.
In an embodiment, the base surface is polygon-shaped or polygonal, but for example with rounded corners, wherein it is for example provided that the underside base surface of the blank is also polygon-shaped or polygonal, but for example with rounded corners. In an embodiment, the base surface is triangle-shaped or triangular, but for example with rounded corners, wherein it is for example provided, that the underside base surface of the blank is also triangle-shaped or triangular, but for example with rounded corners. In an embodiment, the base surface is rectangle-shaped or rectangular, but for example with rounded corners, wherein it is for example provided that the underside base surface of the blank is also rectangle-shaped or rectangular, but for example with rounded corners. In an embodiment, the base surface is square, but for example with rounded corners, wherein it is for example provided that the underside base surface of the blank is also square, but for example with rounded corners. In an embodiment, the base surface is oval, wherein it is for example provided that the underside base surface of the blank is also oval.
In an embodiment, the carrier body is tubular at least in the region of the support surface. The carrier body consists (at least substantially), for example, of steel or high-alloy steel (i.e., for example, a steel in which the average mass content of at least one alloy element is 5%) or of a tube of steel or high-alloy steel. In an embodiment, the diameter of the hollow cross-section of the carrier body or the internal tube diameter, at least in the region of the support surface, is no less than 0.5 mm and/or is no greater than 1 mm. In an embodiment, the external diameter of the carrier body or the external tube diameter, at least in the region of the support surface, is no less than 2 mm and/or no greater than 4 mm, for example no greater than 3 mm. In an embodiment, the radius of curvature of the support surface orthogonally to the flow direction of the coolant is no less than 1 mm and/or no greater than 2 mm, for example no greater than 1.5 mm. In an embodiment, the ratio of the diameter of the hollow cross-section of the carrier body at least in the region of the support surface to the external diameter of the carrier body at least in the region of the support surface is no less than ¼ and/or no greater than ½. In an embodiment, the carrier body is uncoated at least in the region of the support surface. In an embodiment, coolant flows through the carrier body in accordance with the counterflow principle. In an embodiment, the coolant is additionally or actively heated. In an embodiment, the carrier body comprises at least two flow channels for the coolant flowing therethrough, which each only extends over a section of the annular support surface, wherein it is for example provided that two flow channels are connected in a region in which they leave the support surface by means of metallic filler material, for example solder.
In a further embodiment it is provided that, after press molding, the optical element is placed on a transport element, is sprayed with surface-treatment agent on the transport element and, thereafter or subsequently, passes through a cooling path on the transport element without an optical surface of the optical element being touched. In the sense of the disclosure, a cooling path is for example used for the controlled cooling of the optical element (for example with the addition of heat). Exemplary cooling regimes may e.g. be found in “Werkstoffkunde Glas” [Glass Materials Science], 1st edition, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig VLN 152-915/55/75, LSV 3014, editorial deadline: 1.9.1974, order number: 54107, e.g. page 130 and “Glastechnik—BG 1/1—Werkstoff Glas” [Glass Technology—vol. 1/1—Glass: The Material], VEB Deutscher Verlag für Grundstoffindustrie, Leipzig 1972, e.g. page 61 ff (incorporated by reference in its entirety). It is necessary to comply with a cooling regime of this kind in order to prevent any internal stresses within the optical element or the headlight lens, which, although they are not visible upon visual inspection, can sometimes significantly impair the lighting properties as an optical element of a headlight lens. These impairments result in a corresponding optical element or headlight lens becoming unusable. It has surprisingly been found that, although according to the disclosure spraying the hot optical element or headlight lens after press molding or after removal from the mold following the press molding changes the cooling regime, the resulting optical stresses are negligible. It is also surprising that a corresponding headlight lens ranges between the above-mentioned optical tolerances in relation to its optical property, although the refractive index is reduced by the proportion of quartz glass on the surface.
In an embodiment, the transport element is made of steel. For clarification, the transport element is not part of the lens (or headlight lens), or the lens (or headlight lens) and the transport element are not part of a common one-piece body.
In an embodiment, the transport element is heated, for example inductively, before receiving the optical element. In an embodiment, the transport element is heated at a heating rate of at least 20 K/s, for example at least 30 K/s. In an embodiment, the transport element is heated at a heating rate of no greater than 50 K/s. In an embodiment, the transport element is heated by a current-carrying winding/coil winding which is arranged above the transport element.
In an embodiment, the optical element comprises a support surface which lies outside the intended light path for the optical element, wherein the support surface, for example only the support surface, is in contact with a corresponding support surface of the transport element when the optical element is placed on the transport element. In an embodiment, the support surface of the optical element is located at the edge of the optical element. In an embodiment, the transport element comprises at least one limiting surface for aligning the optical element on the transport element or for limiting or preventing movement of the optical element on the transport element. In one embodiment, the limiting surface or limiting surfaces are provided above the corresponding support surface of the transport element. In a further embodiment, (at least) two limiting surfaces are provided, wherein it may be provided that one limiting surface is below the corresponding support surface of the transport element and one limiting surface is above the corresponding support surface of the transport element. In an embodiment, the transport element is adapted, manufactured, for example milled, to the optical element or to the support surface of the optical element.
The transport element or the support surface of the transport element is for example annular but for example not circular.
In an embodiment, the preform is produced, cast and/or molded from molten glass. In an embodiment, the mass of the preform is 20 g to 400 g.
In an embodiment, the temperature gradient of the preform is set such that the temperature of the core of the preform is above 10K+TG.
In an embodiment to reverse its temperature gradient, the preform is first cooled, for example with the addition of heat, and then heated, wherein it is for example provided that the preform is heated such that the temperature of the surface of the preform after heating is at least 100 K, for example at least 150 K, higher than the glass transition temperature TG. The glass transition temperature TG is the temperature at which the glass becomes hard. Within the sense of this disclosure, the glass transition temperature TG is for example intended to be the temperature of the glass at which it has a viscosity log in a range around 13.2 (corresponding to 1013.2 Pas), for example between 13 (corresponding to 1013 Pas) and 14.5 (corresponding to 1014.5 Pas). In relation to the glass type B270, the transition temperature TG is approximately 530° C.
In an embodiment, the temperature gradient of the preform is set such that the temperature of the upper surface of the preform is at least 30K, for example at least 50K, above the temperature of the lower surface of the preform. In an embodiment, the temperature gradient of the preform is set such that the temperature of the core of the preform is at least 50K below the temperature of the surface of the preform. In an embodiment, the preform is cooled such that the temperature of the preform before heating is TG-80K to TG+30K. In an embodiment, the temperature gradient of the preform is set such that the temperature of the core of the preform is 450° C. to 550° C. The temperature gradient may be set such that the temperature of the core of the preform is below TG or near TG . In an embodiment, the temperature gradient of the preform is adjusted such that the temperature of the surface of the preform is 700° C. to 900° C., for example 750° C. to 850° C. In an embodiment, the preform is heated in such a way that its surface (for example immediately before pressing) assumes a temperature corresponding to the temperature at which the glass of the preform has a viscosity log between 5 (corresponding to 105 Pas) and 8 (corresponding to 108 Pas), for example a viscosity log between 5.5 (corresponding to 105.5 Pas) and 7 (corresponding to 107 Pas).
For example, it is provided that the preform is removed from a mold for forming or producing the preform before the temperature gradient is reversed. It is for example provided that the reversal of the temperature gradient takes place outside a mold. For the purposes of the disclosure, cooling with the addition of heat is intended to mean for example that cooling is carried out at a temperature of more than 100° C.
For the purposes of the disclosure, the term “press molding” is to be understood for example as pressing a (particularly optically effective) surface in such a way that subsequent finishing of the contour of this (particularly optically effective) surface can be omitted or is omitted or is not provided for. It is thus particularly intended that a press molded surface is not ground after the press molding. Polishing, which does not affect the contour of the surface but the surface finish of the surface, may be provided. By press molding on both sides it is to be understood for example that a (for example optically effective) light exit area is press molded and a (for example optically effective) light entrance area for example opposite the (for example optically effective) light exit area is also press molded.
In one embodiment, the blank is placed on an annular support surface of a carrier body with a hollow cross section and is heated on the carrier body, for example in such a way that a temperature gradient is set in the blank in such a way that the blank is cooler in the interior than in its outer region, the support surface being cooled by means of a cooling medium flowing through the carrier body, wherein the blank of glass is press molded after heating to the optical element, for example on both sides, wherein the carrier body comprises at least two flow channels for the cooling medium flowing through, each extending only over a portion of the annular support surface, and wherein two flow channels are connected with metallic filler material, for example solder, in a region in which they leave the support surface.
A guide rod as defined in the present disclosure may be a rod, tube, profile, or the like.
Fixed in the sense of this disclosure means for example directly or indirectly fixed to a foundation of the pressing station or the press or a base on which the pressing station or the press stands. Two elements in the sense of this disclosure are fixed to each other for example if for pressing it is not intended that they are moved relative to each other.
For pressing, the first and the second mold are for example moved towards each other in such a way that they form a closed mold or cavity or a substantially closed mold or cavity. Moving towards each other in the sense of this disclosure means for example that both molds are moved. However, it can also mean that only one of the two molds is moved.
A recess in the sense of the disclosure comprises for example a bearing which couples or connects the recess with the corresponding guide rod. A recess in the sense of the present disclosure can be extended to a sleeve or be designed as a sleeve. A recess in the sense of the present disclosure can be extended to a sleeve with an inner bearing or can be designed as a sleeve with an inner bearing.
In a matrix headlight, the optical element or a corresponding headlight lens is used, for example, as a secondary lens for imaging a front optics. A front optics in the sense of this disclosure is arranged for example between the secondary optics and a light source arrangement. A front optics in the sense of the present disclosure is for example arranged in the light path between the secondary optics and the light source assembly. A front optics in the sense of this disclosure is for example an optical component for shaping a light distribution depending on light that is generated by the light source assembly and is directed therefrom into the front optics. Here, a light distribution is generated or formed, for example, by TIR, i.e., by total reflection.
The optical element according to the disclosure or a corresponding lens is also used, for example, in a projection headlight. In the configuration as a headlight lens for a projection headlight, the optical element or a corresponding headlight lens forms the edge of a shield in the form of a bright-dark-boundary on the road.
Motor vehicle in the sense of the disclosure is for example a land vehicle which can be used individually in road traffic. Motor vehicles within the meaning of the disclosure are for example not limited to land vehicles with internal combustion engines.
The thickness r of the lens edge 206 according to
In an embodiment, the (optically effective) surface 204 to be turned away from the light source and/or the (optically effective) surface 205 to be turned toward the light source has a light-scattering surface structure (produced/pressed by molding). A suitable light-scattering surface structure comprises, for example, a modulation and/or a (surface) roughness of at least 0.05 μm, for example at least 0.08μ or is designed as a modulation optionally with an additional (surface) roughness of at least 0.05 μm, for example at least 0.08μ. Roughness in the sense of the disclosure is to be defined for example as Ra, for example according to ISO 4287. In an embodiment, the light-scattering surface structure may comprise a structure mimicking a golf ball surface or be configured as a structure mimicking a golf ball surface. Suitable light scattering surface structures are disclosed, for example, in DE 10 2005 009 556 A1, DE 102 26 471 B4 and DE 299 14 114 U1. Further embodiments of light scattering surface structures are disclosed in German patent specification 1 099 964, DE 36 02 262 C2, DE 40 31 352 A1, U.S. Pat. No. 6,130,777 A, US 2001/0033726 A1, JP 10123307 A, JP 09159810 A, DE 11 2018 000 084 A5 and JP 01147403 A.
Within the meaning of this disclosure, matrix headlights may also be matrix SSL HD headlights. Examples of headlights of this kind are found at the links www.springerprofessional.de/fahrzeug-lichttechnik/fahrzeugsicherheit/hella-bringt-neues-ssl-hd-matrix-lichtsystem-auf-den-markt/17182758 (retrieved on 28.5.2020), www.highlight-web.de/5874/hella-ssl-hd/ (retrieved on 28.5.2020) and www.hella.com/techworld/de/Lounge/Unser-Digital-Light-SSL-HD-Lichtsystem-ein-neuer-Meilenstein-der-automobilen-Lichttechnik-55548/ (retrieved on 28.5.2020).
Another suitable field of application for lenses produced according to the disclosure is for example disclosed in DE 10 2017 105 888 A1 or the headlight described with reference to
The light module M20 comprises a controller denoted by reference sign M3, which actuates the light-emission unit M4 depending on the values from a sensor system or surround sensor system M2. The concave lens M5 comprises a concave curved exit surface on the side facing away from the light-emission unit M4. The exit surface of the concave lens M5 deflects light ML4 directed into the concave lens M5 from the light-emission unit M4 at a large emission angle towards the edge of the concave lens by means of total reflection, such that said light is not transmitted through the projection optics M6. According to DE 10 2017 105 888 A1, light beams that are emitted from the light-emission unit M4 at a “large emission angle” are referred to as those light beams which (without arranging the concave lens M5 in the beam path) due to optical aberrations would be imaged poorly, for example in a blurred manner, on the carriageway by means of the projection optics M6 and/or could result in scattered light, which reduces the contrast of the imaging on the carriageway (see also DE 10 2017 105 888 A1). It may be provided that the projection optics M6 can only image light in focus at an opening angle limited to approximately +/−20°. Light beams having opening angles of greater than +/−20°, for example greater than +/−30°, are therefore prevented from impinging on the projection optics M6 by arranging the concave lens M5 in the beam path.
The light-emission unit M4 may be designed differently. According to one configuration, the individual punctiform light sources of the light-emission unit M4 each comprise a semiconductor light source, for example a light-emitting diode (LED). The LEDs may be actuated individually or in groups in a targeted manner in order to activate or deactivate or dim the semiconductor light sources. The light module M20 e.g. comprises more than 1,000 individually actuatable LEDs. For example, the light module M20 may be designed as what is known as a pAFS (micro-structured adaptive front-lighting system) light module.
According to an alternative option, the light-emission unit M4 comprises a semiconductor light source and a DLP or micromirror array, which comprises a large number of micromirrors which can be actuated and tilted individually, wherein each of the micromirrors forms one of the punctiform light sources of the light-emission unit M4. The micromirror array for example comprises at least 1 million micromirrors, which may for example be tilted at a frequency of up to 5,000 Hz.
Another example of a headlight system or light module (DLP system) is disclosed by the link www.al-lighting.com/news/article/digital-light-millions-of-pixels-on-the-road/ (retrieved on 13.4.2020).
A controller G4 is provided for actuating the system G6 comprising movable micro-mirrors. In addition, the headlight G20 comprises a controller G3 both for synchronizing with the controller G4 and for actuating the illumination device G5 depending on the surround sensor system G2. Details of the controllers G3 and G4 can be found at the link www.al-lighting.com/news/article/digital-light-millions-of-pixels-on-the-road/ (retrieved on 13.4.2020). The illumination device G5 may for example comprise an LED assembly or a comparable light-source assembly, optics such as a field lens (which, for example, has likewise been produced according to the above-described method) and a reflector.
The vehicle headlight G20 described with reference to
Sensors for the above-mentioned headlights for example comprise a camera and analysis or pattern recognition for analyzing a signal provided by the camera. A camera for example comprises an objective or a multiple-lens objective as well as an image sensor for imaging an image generated by the objective on the image sensor. In a particularly suitable manner, an objective is used as disclosed in U.S. Pat. No. 8,212,689 B2 (incorporated by reference in its entirety) and shown by way of example in
Another embodiment for the use of the method described in the following is the production of microlens arrays, for example microlens arrays for projection displays. A microlens array of this kind or its use in a projection display are shown in
The device 1 according to
The process step 122 is followed by a process step 123, in which the preform is transferred to the cooling apparatus 5 by means of a transfer station 4 and is cooled by means of the cooling apparatus 5 at a temperature of between 300° C. and 500° C., for example of between 350° C. and 450° C. In the present embodiment, the preform is cooled for over 10 minutes at a temperature of 400° C., such that its temperature in the interior is approximately 500° C. or greater, for example 600° C. or greater, for example TG or greater.
In a subsequent process step 124, the preform is heated by means of the heating apparatus 6 at a temperature of no less than 700° C. and/or no greater than 1600° C., for example of between 1000° C. and 1250° C., wherein it is for example provided that the preform is heated such that the temperature of the surface of the preform after the heating is at least 100° C., for example at least 150° C., greater than TG and is for example 750° C. to 900° C., for example 780° C. to 850° C. A combination of the cooling apparatus 5 with the heating apparatus 6 is an example of a temperature-control apparatus for setting the temperature gradient.
In one configuration, this temperature-control apparatus and/or the combination of the heating apparatuses 5 and 6 is designed as a hood-type annealing furnace 5000, as shown in
The protective covers 5002, 5202, 5302 for example have the purpose of protecting the heating coils 5001 positioned in the furnace against glass bursting open. If a gob bursts open in the furnace without this protective cover, a part of the glass or a large part of the glass clings to the heating coils 5001 and thus significantly impairs the heating process for the next gob or even destroys the heating coils 5001 and thus destroys the entire functional capability of the furnace. The protective covers 5002, 5202, 5302 are removed after a gob has burst open and are replaced by other protective covers. The protective covers 5002, 5202, 5302 are adapted to the size of the furnace.
The heating coils 5001 may consist of or comprise a plurality of independently actuatable heating coils 5001A and 5001B. Because said coils are independently actuatable, a particularly suitable, for example homogeneous, temperature (distribution) can be obtained inside the furnace or inside the protective covers 5002, 5202, 5303. In addition to their function of reducing the severity of a gob bursting open, the protective covers 5002, 5202, 5303 contribute to this desired temperature distribution. The protective covers consist of or comprise silicon carbide, for example.
As explained below with reference to
In order to reverse its temperature gradient, in one configuration, a preform resting on a cooled lance (not shown) is moved through the temperature-control device comprising the cooling apparatus 5 and the heating apparatus 6 (for example substantially continuously) or is held in one of the cooling apparatuses 5 and/or one of the heating apparatuses 6. A cooled lance is disclosed in DE 101 00 515 A1 and in DE 101 16 139 A1. Depending on the shape of the preform,
For the term “lance”, the term “support device” is also used in the following. The support device 400 shown in
The support device 500 shown in
It may be provided that, after passing through the cooling apparatus 5 (in the form of a cooling path), preforms are removed and are supplied by means of a transport apparatus 41, for example, to an intermediate storage unit (e.g. in which they are stored at room temperature). In addition, it may be provided that preforms are conducted to the transfer station 4 by means of a transport apparatus 42 and are phased into the continuing process by heating in the heating apparatus 6 (for example starting from room temperature).
In a departure from the method described with reference to
In the subsequent process step 123′ according to
Flat gobs, wafers or wafer-like preforms can also be used to produce microlens arrays. Wafers of this kind may be square, polygonal or round, for example having a thickness of from 1 mm to 10 mm and/or a diameter of 4 inches to 5 inches. In a departure from the previously described method, these preforms are not heated on support devices, as shown in
A press 8, onto which a preform is transferred by means of a transfer station 7, is provided behind the heating apparatuses 6 or 5000. The preform is press molded, for example on both sides, to form an optical element, such as the headlight lens 202, in a process step 125 by means of the press 8. A suitable mold set is disclosed e.g. in EP 2 104 651 B1.
The pressing unit PO comprises an actuator O10, which moves the mold OF and is connected to a movable guide element O12. The pressing unit PO also comprises a frame, which is formed by an actuator-side fixed connector O11 and a mold-side fixed connector O14 as well as fixed guide rods O51 and O52, which connect the actuator-side fixed connector O11 to the mold-side fixed connector O14. The fixed guide rods O51 and O52 are guided through recesses in the movable guide element O12, such that they prevent, reduce or avoid any movement or displacement of the mold OF orthogonally to the movement direction of the actuator O10 or mold OF.
In the embodiment shown, the pressing units PO and PU are linked in that the fixed guide element UO is identical to the mold-side fixed connector O14. By linking or chaining the two pressing units PO and PU of the pressing station PS together, particularly high quality (for example in the form of contour accuracy) of the headlight lenses to be pressed is achieved.
The pressing station 800 comprises a lower pressing unit 801 and an upper pressing unit 802 (see
The lower pressing unit 801 comprises a press drive 840 corresponding to the actuator U10, by means of which drive three rods 841, 842, 843 are movable, in order to move a lower press mold 822 that is coupled to the rods 841, 842, 843 and corresponds to the mold UF. The rods 841, 842, 843 are guided through bores or holes (not shown) in the plate 817 and a plate 821, which prevent or considerably reduce a deviation or movement of the press mold 822 in a direction orthogonal to the movement direction. The rods 841, 842, 843 are embodiments of the movable guide rods U51 and U52 according to
The upper pressing unit 802 shown in
Reference sign 870 denotes a movement mechanism by means of which an induction heater 879 comprising an induction loop 872 can be moved towards the lower mold 822 in order to heat it by means of the induction loop 872. After the heating by means of the induction loop 872, the induction heater 879 is moved back into its starting position again. A gob or preform is placed onto the press mold 822 and, by moving the press molds 822 and 823 towards one another, is press molded (on both sides) to form a head-light lens.
The components are, for example, coordinated with one another and/or dimensioned such that the maximum tilting ΔKIPOF or the maximum angle of the tilting of the mold OF (corresponding to the angle between the target pressing direction ACHSOF* and the actual pressing direction ACHSOF), as shown in
The components are, for example, coordinated with one another and/or dimensioned such that the maximum tilting ΔKIPUF or the maximum angle of the tilting of the mold UF (corresponding to the angle between the target pressing direction ACHSUF* and the actual pressing direction ACHSUF), as shown in
Additionally or alternatively, it may be provided that the actuator O10 is decoupled with regard to torsion from the movable guide element O12 with the mold OF. In addition, it may be provided that the actuator U10 is also decoupled with regard to torsion from the mold-side movable connector U12 with the mold UF.
The method described may also be carried out in connection with pressing under vacuum or near vacuum or at least under negative pressure in a chamber, as disclosed by way of example in JP 2003-048728 A. The method described may also be carried out in connection with pressing under vacuum or near vacuum or at least under negative pressure by means of a bellows, as explained in the following on the basis of the pressing station PS in
In another exemplary configuration, before pressing the optical element, such as a head-light lens (or between step (d) and step (e)), a predetermined waiting time is allowed to elapse. In an embodiment, the predetermined waiting time is no greater than 3 seconds (minus the duration of step (d)). In an embodiment, the predetermined waiting time is no less than 1 second (minus the duration of step (d)).
Following the pressing, the optical element (such as a headlight lens) is placed on a transport element 300 as shown in
In addition, before placing the headlight lens 202 on the transport element 300, the transport element 300 is heated such that the temperature of the transport element 300 is approximately +−50 K the temperature of the headlight lens 202 or the edge 206. For example, the heating is carried out in a heating station 44 by means of an induction coil 320, as shown in
In a suitable configuration, it is provided that the support 310 is designed as a rotatable plate. The transport element 300 is thus placed on the support 310 designed as a rotatable plate by hydraulic and automated movement units (e.g. by means of the gripper 340).
Centering is then carried out by two centering jaws 341 and 342 of the gripper 340 and specifically such that the transport elements are oriented in a defined manner by means of the marker slot 303, which is or can be detected by means of a position sensor. Once this transport element 300 has reached its linear end position, the support 340 designed as a rotatable plate begins to rotate until a position sensor has detected the marker slot 303.
In a process step 126, an optical element or the headlight lens 202 is moved through a surface-treatment station 45 according to
By means of the proposed method for producing an optical element or a headlight lens, a weathering resistance or hydrolytic resistance comparable to borosilicate glass is achieved. In addition, the costs for the manufacturing process increase only slightly compared to the manufacturing process of optical elements or headlight lenses with a weathering resistance or hydrolytic resistance corresponding to soda-lime glass.
The transport element 300 together with the headlight lens 202 is then placed on the cooling path 10. In a process step 127, the headlight lens 202 is cooled by means of the cooling path 10.
At the end of the cooling path 10, a removal station 11 is provided, which removes the transport element 300 together with the headlight lens 202 from the cooling path 10. In addition, the removal station 11 separates the transport element 300 and the headlight lens 202 and transfers the transport element 300 to a return transport apparatus 43. From the return transport apparatus 43, the transport element 300 is transferred by means of the transfer station 9 to the heating station 44, in which the transport element 300 is placed on the support 310 designed as a rotatable plate and is heated by means of the induction heating 320.
A process step 128 lastly follows, in which residues of the surface-treatment agent on the lens are washed away in a washing station 46.
It is for example provided that the optical element or lens has a transmission of greater than 90% after washing.
It may be provided that, with reference to the heating of a flat gob, microlens arrays are pressed, which are not used as an array, but instead their individual lenses are used. An array of this kind is for example shown in
The device shown in
The elements in
The claimed or disclosed method makes it possible to expand the range of applications for press molded lenses, for example, with respect to lenses, projection displays, microlens arrays and/or, for example, adaptive vehicle headlights.
Number | Date | Country | Kind |
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10 2019 132 406.8 | Nov 2019 | DE | national |
PCT/DE2020/100905 | Oct 2020 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/DE2020/101007 | 11/27/2020 | WO |