DE102008012283B3 - Process for production of motor vehicle headlight lenses involving melting of the glass to give a blank which is the pressed useful in motor vehicle technology significantly lowers the cost of lens production - Google Patents

Abstract

Process for production of motor vehicle headlight lenses (62) or a lenslike preshaped motor vehicle headlight element, where the glass (35) is melted to give a lens blank which is then pressed. The glass is melted in a melt aggregate (2) of capacity not exceeding 80 kg/h. The glass contains (wt.%):Al2O3 (0.2-2), Li2O (0.1-1), Sb2O3 (0.4-1.5), TiO2 (0.3-2), Er2O3 (0.1-1).

Description

The The invention relates to a method for producing a motor vehicle headlight lens or a lens-like freeform for a motor vehicle headlight, wherein glass is melted, leaving a preform from the glass is formed, and wherein from the preform the motor vehicle headlamp lens or the lenticular freeform for a motor vehicle headlight, especially on both sides, bare is pressed.

A method for producing motor vehicle headlight lenses reveal z. B. the WO 2007/095895 A1 the DE 103 23 989 B4 , the DE 196 33 164 C2 , the DE 10 2004 018 424 A1 , the DE 102 16 706 B4 and the DE 10 2004 048 500 A1 ,

The DE 103 23 989 84 discloses a method for producing bright-pressed glass bodies for optical equipment in which a liquid gob is fed to a levitation preform into which the gob without preforming is preformed into a preform which after a defined time elapses to a separate die is transferred and is pressed therein by means of a pressing tool in the final shape, wherein the transfer of the preform to the mold takes place so that the preform falls in free fall of the preform in the mold, wherein the preform is moved to transfer the gob on the mold , stopped in this transfer position and swung down from the gob.

The DE 101 40 626 B4 discloses a method for producing a molded glass body in which molten glass mass is poured into a mold, pressed in the mold by means of a press die and cooled, and then removed from the mold as the molded glass body, the molten glass mass in the mold being subjected to a plurality of pressing operations is, wherein between the pressing operations, a cooling takes place and at least once between the pressing operations, a heating of the outer regions of the glass mass is made such that the cooling of the glass mass is adjusted in the outer region of the cooling in the core.

The DE 102 34 234 A1 discloses a method for molding a glass body for optical applications using a mold comprising an upper mold and a lower mold and a ring for holding the glass body heated above the deformation temperature, in which an electrical voltage is applied between the upper mold and lower mold and at the latest after matching the temperature of the glass body to the temperature of the mold, a pressing pressure is applied to the glass body.

The DE 103 48 947 A1 discloses a press for hot-forming glass optical elements having means for heating a mold block having an upper mold, a lower mold and a guide ring, which accommodates the glass material, wherein an induction heating is provided as the heating means and the mold block is disposed on a thermally insulating body during heating ,

The DE 196 33 164 C2 discloses a method and a device for at least one-sided molding of optical components for lighting purposes, wherein at least one mechanically portioned glass part of a gripper to at least one annular, extendable from at least one furnace receptacle and moves from the recording in the oven and in the same on the Recording is heated, wherein the heated glass part of the receptacle moves out of the oven and is returned to the gripper, which supplies the heated glass part of a press for at least one-sided molding, and wherein the bright pressed glass part then removed from the press, delivered to a cooling section and is transported away from the same.

The DE 103 60 259 A1 discloses a method of glass blanking of optical elements in which a gob located in a mold block is heated to a temperature T above its transformation temperature T _G , the gob is pressed and cooled to a temperature below T _G , the cooling initially in a first , T _G lying above temperature interval takes place with a first cooling rate and then in a second temperature interval, which includes T _G , with a second cooling rate, and wherein for setting the first and second cooling rate, an active cooling is performed.

The DE 44 22 053 C2 discloses a method for the production of glass moldings in which molten glass is pressed into a mold predetermining its outer shape by means of a press mold which predetermines the inner shape of the glass mold in a pressing station, the press die only in contact with the glass mold in the mold after the pressing process dwells while heat is dissipated from the surface of the glass molding until the glass molding has cooled in its near-surface region to a temperature such that it has sufficient for removal from the mold form stiffness of the surface and wherein the glass molding then removed from the mold and on a cooling station is handed over before it has deformations by partial heating and the glass molding is cooled in the cooling station until its complete solidification.

7 shows a schematic diagram of a typical motor vehicle headlight 61 , with a light source 70 for generating light, a reflector 72 for reflecting by means of the light source 70 producible light and a diaphragm 74 , The motor vehicle headlight 61 also includes a headlight lens 62 for changing the beam direction of by means of the light source 70 producible light and for imaging an edge 75 the aperture 74 as a light-dark border 95 , The headlight lens 62 includes a lens body 63 made of glass, which is one of the light source 70 facing, substantially planar surface 65 and one of the light source 70 opposite, substantially convex surface 64 includes. The headlight lens 62 also includes a border 66 by means of which the headlight lens 62 in the vehicle headlight 61 is fastened. Headlamp lenses for motor vehicle headlamps are subject to narrow design criteria in terms of their optical properties or photometric guide values. This applies in particular with regard to the cut-off line 95 as exemplified in 10 in a graphic 90 and in a photograph 91 is shown. Important photometric guide values are the gradient G of the cut-off line 95 and the glare value HV of the vehicle headlamp, in which the headlamp lens is installed. Compliance with these tight design criteria poses a particular challenge to cost-effective mass production of automotive headlamp lenses.

It Object of the invention, the cost of producing headlamp lenses for motor vehicle headlights to lower. It is another object of the invention, in a limited way Cost a particularly high quality headlight lens for one Manufacture motor vehicle headlights, in particular lighting technology Specifications regarding gradient and glare value are to be adhered to.

• 0,2 bis 2 Gew.-% Al₂O₃,
• 0,1 bis 1 Gew.-% Li₂O,
• 0,4 bis 1,5 Gew.-% Sb₂O₃,
• 0,3 bis 2 Gew.-% TiO₂ und/oder
• 0,1 bis 1 Gew.-% Er₂O₃

umfasst, wobei ein Vorformling aus dem Glas geformt wird, und wobei aus dem Vorformling die Kraftfahrzeugscheinwerferlinse oder die linsenartige Freiform für einen Kraftfahrzeugscheinwerfer, insbesondere beidseitig, blank gepresst wird.The above object is achieved by a method for producing a motor vehicle headlight lens or a lens-like freeform for a motor vehicle headlight, wherein glass is melted in a melting unit having a capacity of not more than 80 kg / h, wherein the glass

• 0.2 to 2% by weight Al ₂ O ₃ ,
• 0.1 to 1% by weight of Li ₂ O,
• 0.4 to 1.5% by weight of Sb ₂ O ₃ ,
• 0.3 to 2 wt .-% TiO ₂ and / or
• 0.1 to 1% by weight of Er ₂ O ₃

comprising, wherein a preform is formed from the glass, and wherein from the preform, the motor vehicle headlight lens or the lens-like freeform for a motor vehicle headlight, in particular on both sides, blank pressed.

Under capacity should be understood in particular the average on a day-related capacity become.

• 60 bis 75 Gew.-% SiO₂,
• 3 bis 12 Gew.-% Na₂O,
• 3 bis 12 Gew.-% K₂O und/oder
• 3 bis 12 Gew.-% CaO.

In an advantageous embodiment of the invention, the glass comprises

• 60 to 75% by weight of SiO ₂ ,
• From 3 to 12% by weight of Na ₂ O,
• 3 to 12 wt .-% K ₂ O and / or
• 3 to 12% by weight of CaO.

• 0 bis 5 Gew.-% MgO,
• 0 bis 2 Gew.-% SrO und
• 0 bis 3 Gew.-% B₂O₃.

In a further advantageous embodiment of the invention, the glass comprises

• 0 to 5 wt.% MgO,
• 0 to 2 wt .-% SrO and
• 0 to 3 wt .-% B ₂ O ₃ .

• 6 Gew.-% ZnO.

In a further advantageous embodiment of the invention, the glass comprises 0.5 to

• 6% by weight ZnO.

• 0,3 bis 0,8 Gew.-% Al₂O₃,
• 0,1 bis 0,4 Gew.-% Li₂O,
• 0,3 bis 2 Gew.-% BaO und/oder
• 0,1 bis 0,3 Gew.-% Er₂O₃.

In a further advantageous embodiment of the invention, the glass comprises

• 0.3 to 0.8% by weight of Al ₂ O ₃ ,
• 0.1 to 0.4% by weight of Li ₂ O,
• 0.3 to 2 wt .-% BaO and / or
• 0.1 to 0.3% by weight of Er ₂ O ₃ .

In Furthermore advantageous embodiment of the invention is the glass melted in the melter from a batch. In continue Advantageous embodiment of the invention, the glass in the smelting unit melted at a temperature of not more than 1500 ° C. In continue Advantageous embodiment of the invention, the glass in the smelting unit melted at a temperature not lower than 1000 ° C. In further advantageous Embodiment of the invention is based on that in the melting unit melted glass a carpet of mats with a thickness between 2 cm and 7 cm.

In a further advantageous embodiment of the invention, the temperature gradient of the preform is reversed, wherein the preform advantageously (for reversing its temperature gradient) lying on a cooled lance (in particular substantially continuously) by a tempering (for cooling and / or heating of the preform) moves or in a temperature control is maintained. A suitable cooled lance is in the DE 101 00 515 A1 disclosed. In a further advantageous embodiment of the invention, the lance is traversed in the countercurrent principle of coolant. In a further advantageous embodiment of the invention, the coolant is additionally or actively heated.

In a further advantageous embodiment of the invention, the temperature gradient of the preform is adjusted so that the temperature of the core of the preform is at least 100 ° C above room temperature. In a further advantageous embodiment of the invention, the preform for reversing its temperature gradient initially, in particular with the addition of heat, cooled and then heated, it being advantageously provided that the preform is heated so that the temperature of the surface of the preform after heating at least 100th ° C, in particular at least 150 ° C, is higher than the transformation temperature T _{G of} the glass. The transformation temperature T _{G of} the glass is the temperature at which the glass becomes hard. In the context of the invention, the transformation temperature T _{G of} the glass should in particular be the temperature of the glass at which it has a viscosity log in a range of 13.2 (corresponding to 10 ^13.2 Pas), in particular between 13 (corresponds to 10 ¹³ Pas) and 14.5 (equivalent to 10 ^14.5 Pas).

In a further advantageous embodiment of the invention, the preform at a temperature between 300 ° C and 500 ° C, in particular between 350 ° C and 450 ° C, cooled. In a further advantageous embodiment of the invention, the preform is cooled at a temperature between 20 K and 200 K, in particular between 70 K and 150 K, below the transformation temperature T _{G of} the glass of the preform. In a further advantageous embodiment of the invention, the preform is heated at a temperature between 1000 ° C and 1250 ° C.

In a further advantageous embodiment of the invention, the gradient of the viscosity of the preform before pressing at least 10 ⁴ Pa · s, in particular at least 10 ⁵ Pa · s. The gradient of the viscosity of the preform should be understood to mean, in particular, the difference between the viscosity of the core of the preform and the viscosity of the surface of the preform.

In Further advantageous embodiment of the invention is the mass of the preform (approximately) 50 g to 250 g.

motor vehicle in the context of the invention is in particular an individual on the road usable land vehicle. Motor vehicles in the context of the invention especially not on land vehicles with internal combustion engine limited.

advantages and details will become apparent from the following description of exemplary embodiments. Showing:

1 a device shown in a schematic representation for the production of a motor vehicle headlight lens or a lenticular freeform for a motor vehicle headlight,

2 an exemplary sequence of a method for producing a motor vehicle headlight lens or a lens-like freeform for a motor vehicle headlight,

3 an embodiment of a melting unit shown in a schematic diagram

4 an exemplary preform before entering a tempering device,

5 an exemplary preform with an inverted temperature gradient after leaving a tempering device,

6 a device for pressing a headlight lens,

7 a schematic representation of a typical motor vehicle headlight,

8th an embodiment of a lens-like freeform for a motor vehicle headlight,

9 Another embodiment of a lens-like freeform for a motor vehicle headlight and

10 a light distribution of a headlamp.

• 60 bis 75 Gew.-% SiO₂,
• 3 bis 12 Gew.-% Na₂O,
• 3 bis 12 Gew.-% K₂O,
• 3 bis 12 Gew.-% CaO,
• 0,2 bis 2 Gew.-% Al₂O₃, vorteilhafterweise 0,3 bis 0,8 Gew.-% Al₂O₃,
• 0 bis 1 Gew.-% Li₂O, insbesondere 0,1 bis 0,4 Gew.-% Li₂O,
• 0 bis 5 Gew.-% MgO,
• 0 bis 2 Gew.-% SrO,
• 0,5 bis 6 Gew.-% ZnO,
• 0 bis 3 Gew.-% B₂O₃, vorteilhafterweise 0 bis 2 Gew.-% B₂O₃,
• 0 bis 2 Gew.-% TiO₂, vorteilhafterweise 0,3 bis 2 Gew.-% TiO₂,
• 0,3 bis 2 Gew.-% BaO,
• 0,4 bis 1,5 Gew.-% Sb₂O₃ vorteilhafterweise 0,4 bis 1,2 Gew.-% Sb₂O₃,
• 0 bis 1 Gew.-% Er₂O₃, vorteilhafterweise 0 bis 0,3 Gew.-% Er₂O₃, insbesondere 0 bis 0,2 Gew.-% Er₂O₃.

1 shows a - shown in a schematic diagram - device 1 to carry out an in 2 illustrated method for producing motor vehicle headlight lenses such as in 7 shown motor vehicle headlight lens 62 or of lens-like freeforms for motor vehicle headlights such. B. the in 8th and 9 illustrated lens-like freeforms 250 and 260 for motor vehicle headlights. The device 1 includes a - in 3 detailed - Melting unit 2 with a capacity of not more than 80 kg / h, in one process step 20 Glass is melted. The glass includes

• 60 to 75% by weight of SiO ₂ ,
• From 3 to 12% by weight of Na ₂ O,
• From 3 to 12% by weight of K ₂ O,
• From 3 to 12% by weight of CaO,
• 0.2 to 2% by weight Al ₂ O ₃ , advantageously 0.3 to 0.8% by weight Al ₂ O ₃ ,
• 0 to 1 wt .-% Li ₂ O, in particular 0.1 to 0.4 wt .-% Li ₂ O,
• 0 to 5 wt.% MgO,
• 0 to 2% by weight of SrO,
• 0.5 to 6% by weight ZnO,
• 0 to 3% by weight B ₂ O ₃ , advantageously 0 to 2% by weight B ₂ O ₃ ,
• 0 to 2% by weight of TiO ₂ , advantageously 0.3 to 2% by weight of TiO ₂ ,
• 0.3 to 2% by weight of BaO,
• 0.4 to 1.5% by weight of Sb ₂ O _3, advantageously 0.4 to 1.2% by weight of Sb ₂ O ₃ ,
• 0 to 1 wt .-% Er ₂ O ₃ , advantageously 0 to 0.3 wt .-% Er ₂ O ₃ , in particular 0 to 0.2 wt .-% Er ₂ O ₃ .

It is advantageously provided that the glass does not comprise more than 0.3, in particular not more than 0.2,% by weight of Er ₂ O ₃ .

In addition, the glass comprises no (ie in particular not more than 0.1% by weight) iron, ZrO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ and F. In addition, the glass comprises no, if possible no more than 0 , 2% by weight, NiO. In addition, the glass comprises as possible no, in particular not more than 0.05 wt .-% Se. In addition, the glass comprises as little as possible, in particular not more than 2 wt .-%, MnO ₂ .

This in 3 Detailed in a schematic diagram shown melting unit 2 includes a melting tank 30 with a support structure 31 and a refractory lining 32 , By means of the melting tank 30 becomes the glass 35 from one by means of a batch feed 38 supplied mixture melted, not provided for supplying energy electrodes are provided. The batch feed 38 is controlled or regulated so that on the molten glass 35 a mixed carpet 36 formed with a thickness between 2 cm and 7 cm. The smelting unit 2 also includes a, z. B. adjustable, spout 33 ,

From the smelting unit 2 becomes liquid glass in one process step 21 in a preforming device 3 for producing a, in particular a mass of 50 g to 250 g, having preform, such as. As a gobs or near-net shape preform (a near-net shape preform has a contour that is similar to the contour of the pressed motor vehicle headlight lens or lens-like freeform for motor vehicle headlights) spent. This can, for. B. include forms into which a defined amount of glass is poured. By means of the preforming device 3 becomes the preform in a process step 22 produced.

The process step 22 follows a process step 23 in which the preform by means of a transfer station 4 to one of the cooling facilities 5A . 5B or 5C passed and by means of the cooling devices 5A . 5B or 5C is cooled at a temperature between 300 ° C and 500 ° C. In a subsequent process step 24 is the preform by means of one of the heaters 6A . 6B or 6C heated at a temperature between 1000 ° C and 1250 ° C, wherein it is advantageously provided that the preform is heated so that the temperature of the surface of the preform after heating at least 100 ° C, in particular at least 150 ° C, higher than T _G. A combination of the cooling device 5A with the heater 6A , a combination of the cooling device 5B with the heater 6B or a combination of the cooling device 5C with the heater 6C is an example of a tempering device for adjusting the temperature gradient in the sense of the claims.

The process steps 23 and 24 - as explained below with reference to 4 and 5 explained - coordinated so that a reversal of the temperature gradient is achieved. It shows 4 an exemplary preform 40 before entering one of the cooling facilities 5A . 5B or 5C and 5 the preform 40 with an inverted temperature gradient after leaving one of the heaters 6A . 6B or 6C , While the blank before the process step 23 (with continuous temperature profile) inside warmer than outside, he is after the process step 24 (at continuous temperature) outside warmer than inside. The symbolize with reference numerals 41 and 42 designated wedges the temperature gradients, where the width of a wedge 41 respectively. 42 a temperature symbolizes.

For reversing its temperature gradient, a preform in an advantageous embodiment lying on a cooled lance, not shown, (in particular substantially continuously) by a one of the cooling devices 5A . 5B or 5C and one of the heaters 6A . 6B or 6C comprehensive tempering moved or in one of the cooling devices 5A . 5B or 5C and / or one of the heaters 6A . 6B or 6C held. A suitable cooled lance is in the DE 101 00 515 A1 disclosed. The lance is advantageously flowed through in the counterflow principle of coolant.

alternative or additionally can be provided that the coolant additionally or actively heated becomes.

This is followed by a process step 25 in which the preform 40 - by means of an in 6 illustrated device, which is part of the press 8th is - between a first form 50 and a second mold, which is a first part mold 51 and one the first part form 51 enclosing annular second part form 52 to a motor vehicle headlight lens 62 or lens-like freeform for motor vehicle headlights with a molded lens edge 66 is blank, being replaced by one of the volume of the preform 40 dependent offset 53 between the first part form 51 and the second part form 52 a step in the vehicle headlight lens 62 or lenticular freeform for motor vehicle headlight is pressed. The pressing is carried out in particular not under vacuum or significant negative pressure. The pressing takes place in particular under atmospheric air pressure. The first part form 51 and the second part form 52 are by means of springs 55 and 56 coupled with each other. It is pressed so that the distance between the first part 51 and the first form 50 from the volume of the preform 40 or the motor vehicle headlamp lens pressed therefrom 62 or lens-like freeform for motor vehicle headlights and the distance between the second part form 52 and the first form 50 from the volume of the preform 40 or the motor vehicle headlamp lens pressed therefrom 62 or lenticular freeform is independent for motor vehicle headlights.

Subsequently, the vehicle headlight lens 62 or lens-like freeform for motor vehicle headlights by means of a transfer station 9 to a cooling track 10 to hand over. By means of the cooling track 10 is the motor vehicle headlight lens or lens-like freeform for motor vehicle headlights in a pressing step 26 cooled. In the 1 illustrated device 10 also includes a computing device 15 for the control of the in 1 illustrated device 1 , The computing device 15 ensures advantageously for a continuous linkage of the individual process steps.

The elements in 1 . 3 . 4 . 5 . 6 and 7 are drawn in the light of simplicity and clarity and not necessarily to scale. So z. For example, the magnitudes of some elements are exaggerated over other elements to enhance understanding of the embodiments of the present invention.

1

contraption

2

smelting unit

3

preforming device

4, 7, 9

Transfer station

5A, 5B, 5C

cooling device

6A, 6B, 6C

heater

8th

Press

10

lehr

15

computing device

20 21, 22, 23, 24, 25, 26

process step

30

melting furnace

31

support structure

32

refractory lining

33

outlet

35

Glass

36

mixture carpet

38

batch feeder

40

preform

41 42

wedge

50

shape

51 52

part form

53

offset

55, 56

feather

61

Motor vehicle headlamps

62

headlight lens

63

lens body

64

convex surface

65

plans surface

66

edge

70

light source

72

reflector

74

cover

75

edge

90

graphic

91

photography

95

Light-off

250 260

freeform

G

gradient

HV

blend value

Claims (13)

Method for producing a motor vehicle headlight lens ( 62 ) or a lenticular freeform ( 250 . 260 ) for a motor vehicle headlight ( 61 ), whereby glass ( 35 ), whereby a preform ( 40 ) from the glass ( 35 ), and wherein from the preform ( 40 ) the motor vehicle headlight lens ( 62 ) or the lenticular freeform ( 250 . 260 ) for a motor vehicle headlight ( 61 ), especially on both sides, is pressed blank, characterized in that the glass ( 35 ) in a smelting unit ( 2 ) is melted with a capacity of not more than 80 kg / h, the glass ( 35 ) 0.2 to 2 wt .-% Al ₂ O ₃ , 0.1 to 1 wt .-% Li ₂ O, 0.4 to 1.5 wt .-% Sb ₂ O ₃ , 0.3 to 2 wt % TiO ₂ and / or 0.1 to 1% by weight Er ₂ O ₃ . Method according to claim 1, characterized in that the glass ( 35 ) 60 to 75 wt .-% SiO ₂ , 3 to 12 wt .-% Na ₂ O, 3 to 12 wt .-% K ₂ O and / or 3 to 12 wt .-% CaO comprises. Method according to claim 1 or 2, characterized in that the glass ( 35 ) 0 to 5 wt .-% MgO, 0 to 2 wt .-% SrO and 0 to 3 wt .-% B ₂ O ₃ comprises. Method according to claim 1, 2 or 3, characterized in that the glass ( 35 ) Comprises 0.5 to 6% by weight of ZnO. Method according to one of the preceding claims, characterized in that the glass ( 35 ) 0.3 to 0.8 wt .-% Al ₂ O ₃ , 0.1 to 0.4 wt .-% Li ₂ O, 0.3 to 2 wt .-% BaO and / or 0.1 to 0 , 3 wt .-% Er ₂ O ₃ includes. Method according to one of the preceding claims, characterized in that the glass ( 35 ) in the smelting unit ( 2 ) is melted from a mixture. Method according to one of the preceding claims, characterized in that the glass ( 35 ) in the smelting unit ( 2 ) is melted at a temperature of not more than 1500 ° C. Method according to one of the preceding claims, characterized in that the glass ( 35 ) in the smelting unit ( 2 ) is melted at a temperature not lower than 1000 ° C. Method according to one of the preceding claims, characterized in that on the in the melting unit ( 2 ) molten glass ( 35 ) a batch carpet ( 36 ) is kept at a thickness between 2 cm and 7 cm. Method according to one of the preceding claims, characterized in that the temperature gradient of the preform ( 40 ) is turned over. Method according to claim 10, characterized in that the preform ( 40 ) for reversing its temperature gradient on a cooled lance lying by a tempering device ( 5A . 6A ) or in a temperature control device ( 5A . 6A ) is held. Method according to one of the preceding claims, characterized in that the gradient of the viscosity of the preform ( 40 ) before pressing at least 10 ⁴ Pa · s, in particular at least 10 ⁵ Pa · s, is. Method according to one of the preceding claims, characterized in that the mass of the preform ( 40 ) Is 50 g to 250 g.