JP2000113701A - Headlight lens and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a surface sink inevitable in thick resin molding by a comparatively thin secondary molding process, to realize resinification of a projector type headlight lens considered as impossible in the past, and to save weight and lower costs extensively. SOLUTION: In this manufacturing method for a headlight lens 1, the headlight lens 1 is manufactured by injection molding using a transparent resin as a material, and the injection molding is composed of a primary molding process molding the greater part of a concave part 2 with the same material and a secondary molding process molding a remaining part of the concave part 2 and a flat part 3. The maximum thickness in the primary molding process is set thicker than that in the second molding process, and the secondary molding process is carried out after cooling a half-finished product H in the primary molding process. Thereby, a surface sink 4 inevitable when molding the thick resin is compensated by the secondary molding process carried out comparatively thinly, and the surface sink caused by the secondary molding process is set within the allowable range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular lamp for lighting such as a headlamp and a fog lamp, and more particularly to a lens used in a vehicular lamp called a projector type. It is.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional headlamp lens 90 of this kind. This headlamp lens 90 has a convex surface portion 91 having one surface formed into a convex lens shape and the other having a convex surface portion 91. It is formed as a so-called plano-convex lens whose surface is a flat plane portion 92. The convex surface portion 91 is formed as an aspheric surface to correct spherical aberration, and is formed of a glass member so as to withstand heat generated by a light source such as a halogen bulb. The shape of the member is adjusted by pressing the member in a mold, and the member is polished to finish.

[0003] Therefore, in the conventional headlight lens 90, the use of a glass member as a material for forming the headlight lens 90 results in an increase in cost due to an excessive weight and a complicated process such as polishing. Was formed,
The use of a glass member was a necessary choice to withstand the heat from a halogen bulb or the like.

[0004]

However, in recent years, a discharge lamp such as a metal halide discharge lamp has been adopted as a light source as a light source, and the calorific value from the light source has been reduced. Although it became tolerable, the resin member has a significantly higher shrinkage ratio during molding than the glass member, and when a thick shape such as the shape of the headlight lens 90 described above is formed by injection molding or the like. However, there is a problem that the expected optical characteristics cannot be obtained due to sink marks in the thick part, and as a result, it is impossible to cope with the situation in which an environment suitable for cost reduction by the resin member is set.

In recent years, as shown in FIG. 6, a center line is provided at each of the left and right ends of an aspherical cylindrical lens 81 in order to personalize an automobile design with another vehicle or to improve performance. There is also a tendency to adopt an irregularly shaped lens 80 or the like in which a half aspherical lens 82 divided into two is connected, and in this case, the cost increases more and more when the glass member is used, and depending on the shape, There is a problem that the formation itself is impossible.

[0006]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, a difference in thickness in the optical axis direction is not less than 7 mm and a non-conductive structure comprising a convex portion and a flat portion. In a method of manufacturing a headlight lens having at least one portion of a spherical lens portion, the headlight lens is injection-molded using a transparent resin as a material, and the injection molding is performed by using the same material for most of the convex surface portion. It comprises a primary molding step of molding and a secondary molding step of molding the remaining part of the convex surface and the flat part.
In addition to setting the maximum molding thickness in the next molding process,
The present invention solves the problem by providing a method for manufacturing a headlight lens, wherein the secondary molding step is performed after the semi-finished product is cooled in the primary molding step.

[0007]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 and 2 show a method of manufacturing a headlamp lens 1 (see FIG. 3) according to the present invention in the order of steps. At this time, the headlamp lens 1 is similar to a conventional example. The description will be made on the assumption that one surface is constituted by a convex surface portion 2 having a convex lens shape and the other surface is constituted by a flat plane portion 3.

In the figure, reference numeral 11 denotes a flat mold which mainly forms the flat portion 3 side of the headlamp lens 1, and reference numeral 12 denotes a headlamp. This is a convex part mold that mainly forms the convex part 2 side of the lens 1. The convex part mold 12 is composed of a fixed part 12a and a moving part 12b, and the moving part 12b is fixed to the fixed part 12a.
The configuration is such that the headlamp lens 1 can be moved in the optical axis Z direction with respect to a.

In forming the headlamp lens 1 with the two dies 11, 12, the moving part 12b of the convex mold 12 is designed to have a headlamp lens having a design size as shown in FIG. The primary molding step by injection molding is performed in a state where the mold is moved toward the plane mold 11 by an appropriate dimension from the thickness of 1.
In addition, as a resin to be injected at this time, for example, methacrylic resin, polycarbonate resin or the like having high transparency, and
Use a material with excellent heat resistance.

In the present invention, the resin is cooled and solidified in the molds 11 and 12 while the injection molding is being performed. As the cooling proceeds, the injected resin has a relatively large shrinkage rate as described above, so that the semi-finished product H present in the molds 11 and 12
Always cause sink marks 4 in an amount corresponding to the contraction rate.

In the present invention, as a subsequent step, as shown in FIG. 2, the moving section 12b is moved to a position where the maximum thickness t of the headlamp lens 1, which is a design dimension, is obtained. Thus, the cavity C including the sink marks 4 is generated on the side of the flat mold 11 due to the movement of the moving portion 12b. Then, the cavity C is subjected to a secondary molding process by the same injection molding with the same resin member as the primary molding process.

Next, the operation and effects of the present invention resulting from the above-described manufacturing method will be described. In order to facilitate understanding, the description will be made on the assumption that the maximum thickness t of the headlight lens 1 is 30 mm and the shrinkage ratio of the resin member at this time is 0.05%. Here, if the headlamp lens 1 is formed by only one molding, the dimension of the sink mark 4 is 3
The value obtained by 0mm x 0.05% is 0.15mm,
With these numerical values, the performance expected as the headlight lens 1 cannot be obtained at all.

In the present invention, since the secondary molding step is performed, the sink marks 4 having a value close to the above value (for example, 0.15 mm) generated in the primary molding step by the secondary molding step are filled, The sink caused by this secondary molding step depends on the thickness at which the secondary molding step was performed. Therefore, by adjusting the thickness at which the secondary molding step is performed, in other words, by adjusting the amount by which the moving portion 12b is moved, the amount of sink generated by the secondary molding step can be freely controlled.

According to the results of the study by the inventor for achieving the present invention, it has been confirmed that the sink 4 needs to be 0.03 mm or less in order to maintain the performance as the headlight lens 1. Was. Calculating back from this confirmed matter, under the condition that the shrinkage of the resin member is 0.05%, 2
The thickness at which the next molding step is performed should be 6 mm or less.

As is apparent from the above description, in order to obtain the headlight lens 1 free of sink marks 4 by the molding method of the present invention, a half of the headlight lens is required after the primary molding step. Product H
In this case, unless the sink marks 4 are generated only on the side where the secondary molding process is performed thereafter, it is impossible to ensure the accuracy.

In order to cope with this, in the present invention, the primary molding step is performed by setting the temperature of the flat mold 11 to be higher than that of the convex mold 12 so that the convex surface of the headlamp lens 1 is formed. The part 2 is cooled first and solidified, and the sink marks 4 are concentrated on the flat part 3 where solidification is delayed. still,
Since the generation of the sink mark 4 is also affected by gravity, it is effective means to install a mold such that the convex surface 2 side faces downward.

By doing so, the thick headlight lens 1 as shown in FIG. 3 can be manufactured even with a resin member, and the headlight lens 1 made of this resin member is employed. , A reflecting mirror 21, a light source 22,
By combining with the light shielding plate 23 and the like, the production of the projector type headlamp 20 becomes possible. Accordingly, the weight of the headlamp 20 can be reduced, and the surface of the injection-molded resin member is beautiful, so that a finishing step such as a polishing step is not required, and the cost can be reduced by reducing the number of steps.

In FIGS. 2 and 3, a joining line J between the portion where the primary molding process is performed and the position where the secondary molding process is performed is indicated by a broken line for easy understanding. However, in an actual product, since the primary molding step and the secondary molding step are performed with the same resin member, the joining line J as shown in the drawing does not occur visually or optically.

FIG. 3 shows an example of the headlamp lens 1 having a circular front shape and a single convex lens shape. For example, a front shape other than a circular shape, or a plurality of convex lenses is used. The present invention can be implemented in any shape such as a connected shape, and the present invention does not limit the shape in which the molding is performed.

[0020]

As described above, according to the present invention, the headlight lens is formed by injection molding using a transparent resin as a material, and the injection molding is performed by primary molding in which most of the convex portion is formed from the same material. And a secondary molding step of molding the remaining portion of the convex portion and the flat portion. The maximum thickness of the primary molding process is set to be larger than the maximum molding thickness of the secondary molding process. With the method of manufacturing a headlight lens in which the secondary molding step is performed after cooling the semi-finished product by the primary molding step, the occurrence of sink marks that cannot be avoided when performing thick resin molding, The problem is solved by the secondary molding process performed with a relatively thin wall, and this type of projector type headlamp lens, which has been impossible in the past, can be made of resin, and has an extremely excellent effect of weight reduction and cost reduction. Things.

[Brief description of the drawings]

FIG. 1 shows a method 1 of manufacturing a headlight lens according to the present invention.
It is explanatory drawing which shows a next shaping | molding process.

FIG. 2 is an explanatory view showing a secondary molding step of the method for manufacturing a headlight lens according to the present invention.

FIG. 3 is a sectional view showing a completed state of the headlight lens according to the present invention.

FIG. 4 is a schematic sectional view showing a headlamp employing the headlight lens according to the present invention.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is a front view showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Headlight lens 2 ... Convex part 3 ... Flat part 4 ... Sink 11 ... Flat part mold 12 ... Convex part mold 12a ... Fixed part 12b ... Moving part 20 ... Head Lamp H ... Semi-finished product

Claims (7)

[Claims] 1. A method according to claim 1, wherein the thickness difference in the optical axis direction is at least 7 mm, and at least one of the aspherical lens portions comprising a convex portion and a flat portion is provided.
In the method for manufacturing a headlight lens having a portion, the headlight lens is injection-molded using a transparent resin as a material, and the injection molding is a primary molding step of molding most of the convex portion with the same material. And a secondary molding step of molding the remaining portion of the convex portion and the flat portion. The maximum thickness of the primary molding process is set to be larger than the maximum molding thickness of the secondary molding process. The method for manufacturing a headlight lens, wherein the secondary molding step is performed after cooling the semi-finished product in the next molding step. 2. A mold is prepared for each of the primary molding step and the secondary molding step, and the semi-finished product obtained by the mold in the primary molding step is subjected to secondary molding. 2. The method for manufacturing a headlight lens according to claim 1, wherein insert molding is performed by attaching to a mold in a molding step. 3. The primary molding step and the secondary molding step are performed in the same mold provided with a moving part, and the secondary molding step operates the moving part after completion of the primary molding step. 2. The method for manufacturing a headlight lens according to claim 1, wherein the method is performed by forming a corresponding cavity. 4. The method for manufacturing a headlight lens according to claim 1, wherein a maximum forming thickness in the secondary forming step is 6 mm or less. 5. The method according to claim 1, wherein the primary molding step is performed in a state where the mold temperature on the flat surface portion side is higher than the mold temperature on the convex surface portion side. A method for manufacturing the headlight lens according to the above. 6. The headlight lens according to claim 1, wherein the secondary molding step is performed in a state in which pressure is applied from the flat surface side. Production method. 7. A headlight lens manufactured by the method for manufacturing a headlight lens according to any one of claims 1 to 6.