JP3814169B2 - Molding method and molding die for vehicle lamp lens - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens molding method and a molding die for a novel vehicle lamp. Specifically, the present invention relates to a technique for improving the appearance and strength of a lens.
[0002]
[Prior art]
A lens for a vehicle lamp is usually formed by injection molding of a thermoplastic resin. Therefore, a lens for a vehicular lamp is provided that is excellent in transparency and shape reproducibility, and is lightweight and inexpensive.
[0003]
[Problems to be solved by the invention]
However, due to the injection molding of the thermoplastic resin, there is a problem that a weld line is formed on the surface of the lens and the appearance is impaired. Further, since the weld line is a fine streak-like groove, there is a problem that the mechanical strength is inferior in a portion where the weld line is present.
[0004]
In general, it is known that a weld line in a resin molded product is generated at a meeting portion of molten resin injected into a cavity of a mold. For example, as shown in FIG. In the case of the lens a, there are openings b and c into which lenses of other colors are fitted, and the obstacles for forming the openings b and c are located in a floating island shape in the cavity. Therefore, the flow of the molten resin becomes complicated, and a plurality of weld lines d, e, and e are generated. Note that the positions and lengths where the weld lines d, e, and e are generated are determined by the number and positions of the injection gates f and f in addition to the shape of the lens a. The approximate positions when two are provided are shown. Of the weld lines d, e, and e, d is an inter-gate weld line formed between the gates f and f, and e and e are floating islands in the cavity for forming the openings b and c. It is an opening part weld produced by a molten resin detouring an obstacle part of a shape.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the appearance and the mechanical strength by preventing a weld line from being generated on the lens surface.
[0006]
[Means for Solving the Problems]
The method for molding a lens of a vehicle lamp according to the present invention comprises an injection step of injecting a molten resin into a cavity of a mold, and a cooling step of cooling the injected molten resin in the cavity. A heating derivative disposed in a cavity formed on the back side of the side cavity surface is brought into contact with the back side of the lens surface side cavity surface during the injection step to heat the lens surface side cavity surface, and in the cooling step, the heating derivative is provided. the is obtained as Rutotomoni is separated from the rear side of the lens surface side cavity surface, it is allowed to flow a cooling medium to the cooling passages the lens surface side cavity surface is cooled.
[0007]
Therefore, in the method for molding a lens of a vehicle lamp according to the present invention, the molten resin injected into the cavity comes into contact with the cavity surface heated by the heated derivative on the lens surface side of the meeting portion. Cooling is prevented, so the skin layer formed on the lens surface side of the meeting part becomes extremely thin, and the high-temperature molten resin suddenly comes into contact with the steel material, which is the mold material, and is instantly cooled. The generation of weld lines, which can be caused by the association of the layers, is prevented. Therefore, the appearance of the lens surface is improved, and the mechanical strength at the meeting portion of the lens is also improved.
[0008]
Further, in the molding die for the lens of the vehicle lamp of the present invention, a cavity is formed on the back side of the lens surface side cavity surface of the meeting portion of the molten resin in the cavity. Rutotomoni are disjunctive freely arranged on the back side, in which the cooling passage so as to surround the vicinity bottom of the cavity is formed.
[0009]
Therefore, in the molding die for the lens of the vehicular lamp according to the present invention, in the injection step of injecting the molten resin into the cavity, the heating part is brought into contact with the back side of the lens surface side cavity surface of the meeting part. As a result, the molten resin that has contacted the heated cavity surface is prevented from instantaneous cooling, and the skin layer formed on the lens surface side of the meeting portion becomes extremely thin. The formation of a weld line, which is formed when a high-temperature molten resin suddenly comes into contact with the steel material, which is the material of the mold, and a thick skin layer formed by instantaneous cooling, is prevented. Therefore, the appearance of the lens surface is improved, and the mechanical strength at the meeting portion of the lens is also improved.
[0010]
Further, in the cooling step, Rutotomoni is separated heating derivative from the rear side of the lens surface side cavity face of the meeting part, by Rukoto by circulating a cooling medium to the cooling passage, the cavity surface is cooled as well as other cavity surface The
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a lens molding method and a molding die for a vehicle lamp according to the present invention will be described below with reference to the accompanying drawings.
[0012]
In the illustrated embodiment, the present invention is applied to the molding of a lens a molded by a multi-color molded lens as shown in FIG. In FIG. 4, as described above, the openings b and c are portions into which a lens of a different color from the lens a is fitted, and the so-called multicolor molding method is adopted as the fitting structure of the other lens. There are a case where the lens is molded integrally and a case where the lens molded separately from the lens a is mechanically coupled.
[0013]
A molding die 1 for molding the lens a includes a fixed mold plate 2 and a movable mold plate 3. When the movable mold plate 3 is clamped to the fixed mold plate 2, a cavity 4 is formed. Further, floating island-like obstacles 5 (only one is shown in FIGS. 1 and 2) for forming the openings b and c shown in FIG.
[0014]
Then, a position where a weld line is likely to be generated in advance by flow analysis or the like, that is, the meeting portion 6 of the molten resin is predicted (for example, d, e, assuming that injection gates are provided at two locations indicated by f and f in FIG. (Part indicated by e) A cavity 8 is formed in the stationary mold plate 2 so as to reach the back side of the lens surface side cavity surface 7 of the meeting portion 6, and the heating derivative 9 is formed in the cavity 8 on the lens surface side cavity surface 7. A back side 10 (hereinafter referred to as “cavity bottom surface”) is detachably disposed. The heating derivative 9 only needs to be capable of heating the lens surface side cavity surface 7 of the fixed mold plate 2 by contacting or approaching the cavity bottom surface 10. For example, the heating derivative 9 itself may be a heater or the like. Even if heated and heated, the bottom surface 10 of the cavity is heated by radiation or conduction and the heat is conducted to the cavity surface 7 on the lens surface side, or the heating derivative 9 itself is heated, such as a coil. Even if not, an eddy current is generated in the portion from the cavity bottom surface 10 to the lens surface side cavity surface 7 of the fixed mold plate 2 by contacting the cavity bottom surface 10, and the eddy current causes the portion of the fixed mold plate 2 to move. Various types of systems such as a heating system can be applied. The heating derivative 9 obtains a signal from a timer and a molding machine and comes into contact with the cavity bottom surface 10 at an appropriate time, and is separated from the cavity bottom surface 10 at an appropriate time.
[0015]
In addition, a cooling passage 11 is formed in the fixed mold plate 2 so as to surround the vicinity of the bottom surface 10 of the cavity 8 so that a cooling medium such as cooling water and cooling air is circulated through the cooling passage 11 in a timely manner. It has become.
[0016]
The lens is molded using the molding die 1 as follows.
[0017]
The movable mold plate 3 is clamped to the fixed mold plate 2 to form the cavity 4. Then, the molten resin 12 (see FIG. 3) is injected into the cavity 4 in a state where the heated derivative 9 is brought into contact with the cavity bottom surface 10 (see FIG. 1) and the lens surface side cavity surface 7 is heated. Since the cavity surface 7 is heated at the associated portion 6 of the molten resin 12, that is, the lens surface side cavity surface 7 where the cavity 8 is formed on the back side, the cavity surface 7 of the molten resin 12 The cooling rate of the molten resin 12 in the vicinity of the contact interface is slowed down, and the skin layer 13 formed along the contact interface with the cavity surface 7 is formed in a place where the cavity bottom surface 10 is not formed (weld line is formed). Therefore, no weld line appears on the surface of the completed lens.
[0018]
After the injection of the molten resin 12 into the cavity 4 is completed and a predetermined injection pressure is applied to the injected molten resin, the heating derivative 9 is separated from the cavity bottom surface 10 (see FIG. 2), and further, the cooling passage 11, when a cooling medium such as cooling water is circulated, the lens surface side cavity surface 7 heated during the injection process is cooled to the same temperature as the other cavity surfaces, and the molten resin is cooled and solidified. Then, the movable mold plate 3 is separated from the fixed mold plate 2 and the completed lens is taken out.
[0019]
When a lens for a vehicle lamp is molded by the molding die 1 described above, a lens for a vehicle lamp having a good appearance and excellent mechanical strength that does not cause a weld line on the lens surface can be molded.
[0020]
In the above-described embodiment, the present invention is applied to the multi-color molded lens batch mold, but the scope of the present invention is not limited to the multi-color molded lens batch mold. However, the present invention can be widely applied in the case of having an association part of molten resin.
[0021]
In addition, the shape or structure of each part shown in the above-described embodiment is merely an example of the embodiment performed when the present invention is carried out, and the technical scope of the present invention is limited by these. There should be no interpretation of it.
[0022]
【The invention's effect】
As is apparent from the above description, the method for molding a lens for a vehicle lamp according to the present invention is a method for molding a lens for a vehicle lamp having a meeting portion of a molten resin in a cavity of a mold, And the cooling process of cooling the injected molten resin in the cavity, and arranged in a cavity formed on the back side of the cavity surface on the lens surface side of the meeting part. heating derivative is brought into contact with the back side in the injection process the lens surface side cavity surface heating the lens surface side cavity surface, the heating derivative is separated from the rear side of the lens surface side cavity surface in the cooling step Rutotomoni The lens surface side cavity surface is cooled by circulating a cooling medium in the cooling passage .
[0023]
Therefore, in the method for molding a lens of a vehicle lamp according to the present invention, the molten resin injected into the cavity comes into contact with the cavity surface heated by the heated derivative on the lens surface side of the meeting portion. Cooling is prevented, so the skin layer formed on the lens surface side of the meeting part becomes extremely thin, and the high-temperature molten resin suddenly comes into contact with the steel material, which is the mold material, and is instantly cooled. The generation of weld lines, which can be caused by the association of the layers, is prevented. Therefore, the appearance of the lens surface is improved, and the mechanical strength at the meeting portion of the lens is also improved.
[0024]
In the invention described in claim 2, since the molten resin is injected into the cavity from a plurality of gates, an association portion of the molten resin always occurs, so that the effect of eliminating the weld line is remarkable.
[0025]
In the invention described in claim 3, since the floating island-like obstacle portion is formed in the cavity, an association portion of the molten resin is inevitably generated, so that the effect of eliminating the weld line is remarkable.
[0026]
The molding die for the lens of the vehicle lamp of the present invention is a molding die for a lens of a vehicle lamp having a meeting portion of molten resin injected in the cavity of the die, and the lens surface of the meeting portion. cavity is formed on the back side cavity surface, that the air heated derivative sinuses are disjunction freely arranged on the back side of the lens surface side cavity surface Rutotomoni, the cooling passages so as to surround the vicinity bottom surface of the cavity formed It is characterized by.
[0027]
Therefore, in the molding die for the lens of the vehicular lamp according to the present invention, in the injection process of injecting the molten resin into the cavity, the heated part is brought into contact with the back side of the lens surface side cavity surface of the meeting part. As a result, the molten resin that has contacted the heated cavity surface is prevented from instantaneous cooling, and the skin layer formed on the lens surface side of the meeting portion becomes extremely thin. The formation of a weld line, which is formed by the contact of a high-temperature molten resin suddenly with the steel material, which is the material of the mold, and the instantaneous cooling of the thick skin layer, is prevented. Therefore, the appearance of the lens surface is improved, and the mechanical strength at the meeting portion of the lens is also improved.
[0028]
Further, in the cooling step, Rutotomoni is separated heating derivative from the rear side of the lens surface side cavity face of the meeting part, by Rukoto by circulating a cooling medium to the cooling passage, the cavity surface is cooled as well as other cavity surface The
[0029]
According to the fifth aspect of the present invention, since a plurality of gates for injecting the molten resin into the cavity are provided, an association portion of the molten resin always occurs, so that the effect of eliminating the weld line is remarkable.
[0030]
In the invention described in claim 6, since the floating island-like obstacle portion is provided in the cavity, an association portion of the molten resin is inevitably generated, and the effect of eliminating the weld line is remarkable.
[Brief description of the drawings]
FIG. 1 shows a lens molding method and a molding die of a vehicle lamp according to the present invention together with FIG. 2, and is a schematic sectional view showing an injection process.
FIG. 2 is a schematic sectional view showing a cooling process.
FIG. 3 is a diagram schematically showing the flow of molten resin in a cavity.
FIG. 4 is a diagram showing a problem of a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Molding die, 4 ... Cavity, 5 ... Obstacle part, 6 ... Meeting part, 7 ... Lens surface side cavity surface, 8 ... Cavity, 9 ... Heating derivative, 10 ... Cavity bottom surface (back side of lens surface side cavity surface) 11 ... Cooling passageway, 12 ... Molten resin

Claims (6)

A molding method for a lens of a vehicle lamp having a meeting portion of a molten resin in a cavity of a mold,
An injection process for injecting molten resin into the mold cavity;
A cooling process for cooling the injected molten resin in the cavity,
A heating derivative disposed in a cavity formed on the back side of the lens surface side cavity surface of the meeting part is brought into contact with the back side of the lens surface side cavity surface during the injection step to heat the lens surface side cavity surface;
The cooling step is to separate the above heating derivative from the rear side of the lens surface side cavity surface Rutotomoni, vehicles by circulating the cooling medium in the cooling passage, characterized in that as the lens surface side cavity surface is cooled A method for forming a lens for a lamp. The method for molding a lens for a vehicle lamp according to claim 1, wherein the molten resin is injected into the cavity from a plurality of gates. The method for molding a lens for a vehicle lamp according to claim 1 or 2, wherein a floating island-like obstacle is formed in the cavity. A molding die for a lens of a vehicle lamp having a meeting part of a molten resin injected in a cavity of the die,
A cavity is formed on the back side of the cavity surface on the lens surface side of the meeting part,
Molding of the air sinuses heating derivative is disjunction freely arranged on the back side of the lens surface side cavity surface Rutotomoni, the vehicle lamp, wherein the cooling passage is formed so as to surround the vicinity bottom of the cavity lens Mold. The molding die for the lens of the vehicle lamp according to claim 4, comprising a plurality of gates for injecting molten resin into the cavity. 6. A mold for molding a lens for a vehicle lamp according to claim 4 or 5, wherein a floating island-shaped obstacle is provided in the cavity.

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