JP4060141B2 - Resin molded parts and molds for resin molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transparent resin molded part such as a through cover used in a vehicular lamp, and more particularly to a resin molded part that prevents a clouding phenomenon in the vicinity of a gate mark caused by resin molding and a resin molding metal for manufacturing the resin molded part. It relates to types.
[0002]
[Prior art]
In recent years, automotive lamps have been proposed in which a front lens is configured with a through cover because of design requirements. For example, after incorporating a high beam lamp, a low beam lamp, a clearance lamp, and a turn signal lamp in an integrated lamp body in a state of planar arrangement, the front surface of these lamps is covered with a single through cover as an outer lens, There has been proposed a front combination lamp in which these lamps are integrated. The combination lamp having such a configuration is effective in reducing the number of parts because it is only necessary to provide one through cover for a plurality of lamps.
[0003]
In such a lamp, the through-hole cover needs to be formed to have a planar size covering a plurality of lamps, and therefore it is necessary to produce a lamp having a relatively large area. This type of through cover is formed by injection molding using a transparent resin. However, if a gate that injects resin into the cavity of the injection mold is arranged at the edge of the through cover or a location close to this, the cavity The time difference between the time when the resin pumped inside reaches the vicinity of the edge and the time until it reaches the opposite edge increases, and there is also a difference in the cooling time of the resin in the cavity and the pressure applied to the resin. As a result, striae (weld line), deformation, and the like are likely to occur in the formed through cover, which is a factor of deteriorating product quality. Therefore, it is considered that the gate is arranged near the center of the through cover. By arranging the gate near the center, the time of the resin reaching each end of the through cover is made uniform, and the pressure applied to the resin Therefore, the generation of striae and deformation can be suppressed and quality can be improved. In addition, it is possible to reduce the thickness of the through cover without lowering the mechanical strength due to striae.
[0004]
[Problems to be solved by the invention]
By the way, in the resin molded part formed by injection molding, a gate mark which is a trace of the gate of the mold is generated, which is a factor of deteriorating the appearance, but this gate mark is processed by polishing or the like. Thus, it is possible to perform processing so that it is not visible to some extent from the outside. On the other hand, in this type of resin molded part, the gas generated in the vicinity of the gate when the resin is injected into the cavity from the gate is a factor. FIGS. 9B and 9C are schematic views of a plan view and a CC line cross-sectional view. As shown specifically, the resin in the vicinity region including the gate mark 202 formed on the surface of the resin molded part 201 becomes cloudy on the resin surface or inside, and the transparency of the resin molded part 201 is lowered by the cloudy portion 203. A phenomenon may occur. If this white turbidity occurs, even when the gate mark is processed in a molded resin molded part, for example, the aforementioned through cover, it is difficult to remove the white turbidity if it occurs inside the resin. . Therefore, if the gate is arranged near the center of the combination lamp through cover in order to prevent the striae as described above, a cloudy area is left in the center area of the lamp, and the appearance of the through lens decreases in appearance. In addition, the appearance of the entire combination lamp is deteriorated, and the quality of the lamp is deteriorated.
[0005]
An object of the present invention is to provide a resin molded part that realizes high quality by preventing deterioration in appearance due to white turbidity in a transparent resin molded part such as a through cover, and a resin molding die for molding the resin molded part. It is.
[0006]
[Means for Solving the Problems]
The present inventor studied the clouding phenomenon that occurs in transparent resin molded parts, and estimated that clouding occurs for the following reasons. That is, FIG. 9A is a sectional view of the vicinity of a gate of a conventional resin molding die for resin molding a transparent resin molded part, for example, a through-hole cover. In the conventional resin molding die, the cavity surfaces of the pair of fixed mold 101 and movable mold 102 constituting the cavity 103 are formed in a substantially flat surface in order to form the through-hole cover with a substantially uniform thickness. Then, a gate 105 is disposed on the fixed mold 101, and the transparent resin X is injected into the cavity 103 through the gate 105, and the through-hole cover 201 as shown in FIGS. 9B and 9C is resin-molded. . At this time, the opening diameter of the gate 105 is approximately 2.8 mm, and the thickness of the formed through cover 201, that is, the gap dimension of the cavity 103 is approximately 4.0 mm. In this situation, when the resin X is injected from the gate 105 into the cavity 103, the internal pressure suddenly increases when the resin X that is compressed when passing through the thin gate 105 is released into the cavity 103. It decreases, and the low molecule (monomer) in the resin is gasified. This gas is confined in the resin in the circular region of the required range centering on the gate 105 in the vicinity of the gate 105, and the light transmittance of this portion is reduced, so that the cloudy portion 203 is generated. .
[0007]
Then, this inventor considered suppressing white turbidity phenomenon by suppressing the gasification of a monomer, when resin is inject | emitted in a cavity from a gate. That is, the volume of the nearby cavity including the gate is prevented so that the resin pressure injected into the cavity from the gate is not suddenly released to suppress a rapid decrease in the internal pressure of the resin that causes gasification. Is reduced, that is, the cavity gap size is reduced. Specifically, as a configuration of the resin molding die in the present invention, a gate is arranged on one mold surface facing the cavity, and protrudes toward the gate in a portion facing the gate on the other mold surface. Convex portions are provided to make the gap size of the cavity equal to the opening size of the gate .
[0008]
Further, in the resin molded part of the present invention molded by such a resin molding die, a gate mark is formed on one surface of the resin molded part, and a recess is formed in a portion facing the gate mark on the opposite side. becomes configurations, Ru etc. Intrinsics the wall thickness of the portion where the recess is formed in the opening diameter size of the gate.
[0009]
When the resin molded part of the present invention is molded with such a resin molding die, when the resin is injected from the gate into the cavity, the gap size of the cavity in the vicinity including the gate is reduced. Since the volume of the cavity is reduced, the resin injected into the cavity from the gate is suddenly released and the internal pressure is suppressed from being reduced, and the gasification of the monomer in the resin is suppressed. The white turbidity phenomenon due to the conversion is suppressed or prevented.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view of an embodiment in which the present invention is applied to a front combination lamp, and FIG. 2 is a sectional view taken along line AA in FIG. In these drawings, illustration of an aiming mechanism for adjusting the optical axis of a reflector, which will be described later, and other structures is omitted. The front combination lamp FCL includes a high beam lamp HHL, a low beam lamp LHL, and a turn signal lamp TSL arranged in one lamp body 1 and a front cover of these lamps collectively as an outer lens. It is the structure covered with 2.
[0011]
That is, the lamp body 1 formed over the entire area of the front combination lamp FCL has a seal groove 11 formed along the periphery of the front opening, and the lamp body 1 includes the high beam lamp HHL, the low beam lamp LHL, the turn The reflectors 3, 4 and 5 of the signal lamp TSL are arranged. Here, the reflectors 3 and 4 of the high beam lamp HHL and the low beam lamp LHL are integrally formed, and light bulb socket mounting holes 31 and 41 are opened on the back surfaces of the reflectors 3 and 4, respectively. Light bulbs 33 and 43 are attached. Further, waterproofing between the lamp body 1 and the rubber caps 34 and 44 is achieved. These reflectors 3 and 4 are supported in the lamp body 1 in a state in which the reflectors 3 and 4 are integrally deflected up and down and left and right by an aiming mechanism not shown in the drawing. Further, the inner surface of the lamp body 1 is not exposed to the outside by covering the gap between the edges of the reflectors 3 and 4 of the high beam lamp HHL and the low beam lamp LHL and the edge of the front opening of the lamp body 1. Further, an extension 6 having an aluminum film formed on the surface thereof is disposed, and the reflector 5 of the turn signal lamp TSL is formed integrally with the extension 6, and a light bulb socket insertion hole 51 is opened on the back of the reflector 5. The amber-colored light bulb 53 is attached by the light bulb socket 52. A shade 45 for obtaining required light distribution characteristics is disposed on the front surface of the light bulb 43 of the low beam lamp LHL.
[0012]
In addition, the through cover 2 is attached to the front opening of the lamp body 1. The transparent cover 2 is formed by injection molding a white (colorless) transparent resin, and seal legs 21 provided along the periphery of the transparent cover 2 are inserted into the seal groove 11 of the lamp body 1 and fixed by a sealant 11a. Thus, attachment to the lamp body 1 is performed in a state where the gap between the seal groove 11 and the seal leg 21 is sealed.
[0013]
The pass-through cover 2 is formed with a substantially uniform thickness of about 4 mm over almost the entire front surface serving as the light emitting surface of the lamp, and a gate mark 22 is formed on the surface in the vicinity of the center thereof. 3A and 3B are an enlarged perspective view and a cross-sectional view taken along the line BB of the transparent cover in the region including the gate mark. The gate mark 22 is formed on the surface of the through-hole cover 2 as a thin convex part having a circular or annular shape, and is formed as a polishing residue obtained by polishing a gate mark generated when the through-hole cover 2 is resin-molded as will be described later. . The gate mark 22 has a diameter of approximately 2.8 mm. In addition, a circular shallow dish-shaped concave portion 23 is formed on the opposite surface, that is, the inner surface of the through-hole cover 2 at a location facing the gate mark 22. The recess 23 is slightly larger than the gate mark 22 and has a diameter of about 5 mm. The depth of the recess 23 is approximately 1.2 mm so that the thickness of the through-hole cover 2 where the recess 23 is formed is about 2.8 mm, which is substantially equal to the diameter dimension of the gate mark 22. It is formed to a depth of about.
[0014]
FIG. 4 is a cross-sectional view of a mold for resin-molding the through cover, and particularly shows an enlarged cross-sectional view of a vicinity including a gate. The mold 100 has a cavity 103 for resin-molding the transparent cover 2 between a fixed mold 101 arranged on the upper side and a movable mold 102 arranged on the lower side and driven up and down by a driving mechanism (not shown). Is formed. The gap of the cavity 103 in the thickness direction of the through cover is formed to 4 mm. Further, the fixed mold is provided with a circular gate 105, which communicates with a runner (not shown) and is configured to inject resin fed through the runner into the cavity 103 through the gate 105. Has been. In addition, the movable plunger 104 is arrange | positioned inside the said gate 105, and it is the same as the conventional gate that it is comprised so that a gate opening can be opened and closed. Further, the movable mold 102 is provided with a convex portion 106 having a circular mesa shape toward the cavity 103 at a position facing the gate 105. As schematically shown in FIG. 5, the gate 105 has an opening diameter r of 2.8 mm, and the protrusion 106 has a diameter R of about 5 mm with the opening of the gate 105 as the center. The height h is approximately 1.2 mm. Accordingly, the gap dimension d of the cavity 103 immediately below the gate 105 is 2.8 mm which is substantially equal to the opening diameter dimension r.
[0015]
The method of resin-molding the transparent cover 2 using the resin molding die 100 having such a configuration is the same as heretofore. That is, when the molten colorless transparent resin is injected into the cavity 103 through the gate 105, the injected resin flows to and fills each part in the cavity 103. Then, the gate 105 is closed by the plunger 104, the movable mold 102 is moved downward after the resin is cured, and the molding cover 2 is taken out from the movable mold 102, thereby completing the molding. Since the gate 105 is disposed at a substantially central position on the surface of the cavity 103, the resin cover 2 formed in this way is flowed and molded at a substantially uniform speed to each edge around the cavity 103. As a result, striae hardly occur in the through-hole cover 2, and a high-quality through-hole cover 2 can be formed.
[0016]
At the time of molding, a convex portion 106 is formed on the surface of the movable mold 102 facing the gate 105 to reduce the volume of the cavity 103 in this portion. In this example, the gap d between the portions of the cavity 103 is reduced. Is made smaller than the other portions and substantially equal to the opening diameter r of the gate 105, the resin injected into the cavity 103 from the gate 105 is prevented from being suddenly opened in the cavity 103. . As a result, a decrease in the internal pressure in the resin is suppressed and gasification of the monomer is suppressed, and the white turbidity phenomenon in the through cover near the gate due to the gasification is suppressed or prevented.
[0017]
In addition, after taking out the pass-through cover molded from the resin molding die 100, the gate trace protruding from the surface is polished and processed to a nearly flat state, so that the gate trace appears as the gate mark 22 in appearance. Therefore, it becomes possible to make it almost inconspicuous. Therefore, by the above method, it is possible to form the high-quality through cover 2 in which the gate mark 22 is not conspicuous and white turbidity is suppressed or prevented by resin molding.
[0018]
Here, as shown in FIG. 5, the present inventor conducted various experiments on the height dimension h of the convex portion 106 disposed opposite to the gate 105 of the resin molding die. The dimension h is most preferably set so that the gap d of the cavity 103 at the gate 105 portion is substantially equal to the opening diameter dimension r of the gate 105 as in the above embodiment, but the ratio d between the gap dimension d and the gate opening diameter dimension r. It was confirmed that if / r is smaller than 1.1, that is, if the gap dimension d is smaller than 1.1 times the gate opening diameter dimension, white turbidity can be suppressed to an inconspicuous level. Therefore, the mold 100 may be designed by obtaining the height of the convex portion 106 from the gap dimension d and the thickness dimension of the through-hole cover to be molded.
[0019]
In the above embodiment, an example of a through cover with a nearly flat surface is shown. However, depending on the type of the through cover, a step is formed on the inner surface of the cover to adjust the light distribution characteristics of the lamp light emitted from each lamp. There is something to do. The present invention can also be applied to such a through cover (strictly speaking, it cannot be called a through cover because light is refracted, but is referred to as a through cover including such a cover in this specification). It is.
[0020]
FIGS. 6A and 6B are configuration examples for forming the through-hole cover 2A in which concave cylindrical (kamaboko-type) steps 24 are arranged in parallel on the inner surface. FIG. 6A is a sectional view of the through-hole cover. As shown in the figure, the bottom 107 a of the arc-shaped convex surface 107 formed on the cavity surface of the movable mold 102 for forming the cylindrical step 24 is disposed opposite to the gate 105 in the mold. In this manner, the cylindrical step 24 is used to reduce the gap dimension d1 in the vicinity of the cavity 103 including the gate 105, thereby suppressing the white turbidity phenomenon during resin molding as described in the above embodiment. It becomes possible. Therefore, in the through cover 2A, the concave bottom surface 24a of the cylindrical step 24 is configured as a concave portion in the present invention.
[0021]
FIG. 7 is a structural example of forming the through-hole cover 2B in which convex cylindrical steps 25 are arranged in parallel on the inner surface. FIG. 7A is a sectional view of the through-hole cover. Here, the mold has a configuration in which the boundary edge portion 108 a of the arc-shaped concave surface 108 formed on the cavity surface of the movable mold 102 for forming the cylindrical step 25 is disposed opposite to the gate 105. In this way, similarly, the cylindrical step 25 is used to reduce the gap dimension d2 in the vicinity of the cavity 103 including the gate 105, thereby suppressing the cloudiness phenomenon during resin molding. Therefore, in this through-hole cover 2B, the adjacent edge portion 25a of the cylindrical step 25 is configured as a recess in the present invention.
[0022]
FIG. 8 shows an example of a structure for forming a through-hole cover 2C having a convex cylindrical step 26 as in FIG. 7, wherein (a) is a mold, and (b) is a cross-sectional view of the through-hole cover. In the embodiment of FIGS. 6 and 7, the gap size of the cavity in the vicinity region including the gate is reduced by one cylindrical step. Therefore, the region having a small gap size in the cavity 103 is the width of the cylindrical step in the direction along the paper surface. In the case of a cylindrical step having only a size and a small width, it is difficult to obtain the white turbidity suppressing effect in the configuration of the above embodiment. In this embodiment, when the width of the arcuate concave surface 109 forming the cylindrical step 26 is small, the cavity surface of the movable mold 102 forming the cavity 103 is tapered, and the gap dimension d3 in the vicinity region including the gate 105 is obtained. Is minimized, and the gap dimension gradually increases according to the arrangement period of the arcuate concave surfaces 109 as the distance from the distance increases. By doing so, it is possible to suppress white turbidity in the through cover 2C as in the above-described embodiments, and the formed through cover has a smaller thickness in the vicinity of the gate than the other parts. The difference in thickness is not noticeable by the narrow cylindrical step, and the appearance is not deteriorated. Therefore, in this through-hole cover 2C, the concave portion 26a formed by the envelope surface enveloping the convex portion of the cylindrical step 26 is configured as the concave portion in the present invention.
[0023]
In the above-described embodiment, an example in which the present invention is applied to a front cover lamp through cover is shown, but the present invention can also be applied to a through cover applied to other vehicle lamps. Further, the present invention is not limited to the through cover, and the present invention can be similarly applied to any transparent resin molded part formed by an injection molding method.
[0024]
【The invention's effect】
As described above, the resin molded part of the present invention has a configuration in which a gate mark is formed on one surface and a recess is formed on the opposite surface. In a mold for molding this resin molded part, A gate is disposed on one mold surface facing, and a protrusion is provided on a part of the other mold surface so as to protrude toward the gate direction, and a cavity is formed so that the gap dimension of the cavity is equal to the opening diameter dimension of the gate. The volume of the cavity in the vicinity region including the gate is reduced, the resin injected into the cavity from the gate during resin molding is suddenly released and the internal pressure is suppressed from being reduced, and the monomer gasification in the resin is suppressed. The clouding phenomenon due to the gasification is suppressed or prevented. Thereby, it is possible to obtain a high-quality resin molded product in which white turbidity does not occur or is inconspicuous.
[Brief description of the drawings]
FIG. 1 is a front view of an embodiment in which the present invention is applied to a front combination lamp.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIGS. 3A and 3B are an enlarged perspective view and a cross-sectional view taken along line BB of a main part of the transparent cover.
FIG. 4 is a cross-sectional view of a resin molding die and an enlarged view of a main part.
FIG. 5 is a schematic diagram for explaining the dimensions of the vicinity including the gate.
FIG. 6 is an enlarged cross-sectional view of a main part of a mold and a through cover according to another embodiment of the present invention.
FIG. 7 is an enlarged cross-sectional view of a main part of a mold and a through cover according to another embodiment of the present invention.
FIG. 8 is an enlarged cross-sectional view of a main part of a mold and a through cover according to still another embodiment of the present invention.
FIG. 9 is a partial cross-sectional view of a mold for explaining the clouding phenomenon in a transparent resin molded part, a schematic plan view of the resin molded part, and a CC line cross-sectional view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lamp body 2 Through cover 3, 4, 5 Reflector 22 Gate mark 23 Recess 24, 25, 26 Cylindrical step 100 Resin molding die 101 Fixed mold 102 Movable mold 103 Cavity 105 Gate 106 Convex part 107 Arc-shaped convex surface 108 Arc shape Concave surface 109 Arc-shaped concave surface FCL Front combination lamp LHL Low beam lamp HHL High beam lamp TSL Turn signal lamp

Claims (3)

A transparent resin molded part molded by injecting resin into a cavity of the mold from a gate provided in the mold, wherein a gate mark is formed on one surface of the resin molded part, and the opposite side A resin molded part characterized in that a recess is formed in a portion of the surface facing the gate mark, and the thickness of the portion where the recess is formed is equal to the opening diameter of the gate . The resin molded part according to claim 1 , wherein the resin molded part is a through cover for a vehicular lamp, and the gate mark and the recess are arranged in a region near the center of the surface of the through cover. A resin molding die for producing a transparent resin molded part by constitutes a cavity in a region surrounded by the pair of molds surfaces, for injecting resin into the cavity from the gate, to the cavity A gate is arranged on one facing mold surface, and protrudes toward a part of the other mold surface facing the gate toward the gate direction so that the gap dimension of the cavity is equal to the opening diameter dimension of the gate. A mold for resin molding characterized by comprising a portion.

Images