JP2012254577A - Valve gate type mold apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve gate type mold apparatus which controls forming of a pressing mark caused by a tip of a valve pin remaining on a design surface of a molding to enable the design surface to give few optically adverse influence, when forming a cover lens constituting a lamp for a vehicle by injection molding using the valve gate type mold apparatus.SOLUTION: A design surface forming area 56 of a cavity 55 of a mold for molding a part of the design surface of the cover lens is formed in the inclined state by a determined angle with respect to the vertical surface direction of the mold opening direction of the mold. While a valve gate 60 is arranged on the design surface forming area 56, the insert-pull direction of a valve pin 65, which is inserted into and pulled from a cylinder interior 65 of a gate part 61 of the valve gate 60 to close and open a passage of a melt resin, is set to the same direction of the mold opening direction. The shape of the tip part 69 of the valve pin 65 is convex spherical or convex conical, and also a tip surface 70 is a concave and convex surface, which is structured of a plurality of concave parts and convex parts.

Description

  The present invention relates to a valve gate mold apparatus for injecting molten molding resin through a valve gate into a mold cavity during injection molding.

  As a conventional valve gate type mold apparatus, for example, there is one described in JP-A-2002-36305 (Patent Document 1).

  That is, the tip surface of the valve pin that controls the flow of the molding resin into the cavity is formed into a convex spherical shape by opening and closing the gate through which the molding resin melted during injection molding passes. In this valve pin, the molding material flows into the cavity by opening the gate of the valve gate, and the gate is closed by the valve pin when the cavity is completely filled with the molding material. This prevents the molding material from leaking from the gate when the mold is opened.

  In this case, the gate is opened / closed by inserting / removing the valve pin into / from the internal space of the cylindrical gate, and when the gate is closed, the valve pin is inserted into the gate and the tip is slightly protruded into the cavity. Burr is prevented from being generated on the gate trace of goods.

  Then, when the gate is closed, the portion of the molding material filled in the cavity corresponding to the valve pin is pressed by the tip portion of the valve pin to be pressed. At that time, since the tip of the valve pin has a convex spherical shape, the pressure applied to the molding material by the tip of the valve pin is radially dispersed. Therefore, it is suppressed that excessive pressing is locally applied to the portion of the molding material that is pressed at the tip of the valve pin.

  As a result, the molding material is prevented from sticking firmly to the tip of the valve pin, and the mold release from the valve pin is smoothly performed when the molded product is released after the mold is opened. And peeling are prevented. At the same time, the molding material adhering to the tip of the valve pin does not cause a problem that it becomes an obstacle to the next molding cycle, and the good product yield can be improved.

JP 2002-36305 A

  By the way, in recent years, vehicular lamps (particularly headlamps) have been increased in size and profile by accommodating a plurality of light sources therein, and accordingly, the cover lenses constituting the vehicular lamps have also increased in size. It has a slanted (tilted) shape in the vehicle height direction and the vehicle width direction of the vehicle. Further, the surface (design surface) through which the irradiation light passes is made thinner than the other portions in order to suppress transmission loss and ensure high light transmittance.

  Such a cover lens is formed by injection molding using a polycarbonate resin excellent in various properties such as transparency, impact resistance, weather resistance and heat resistance, but the polycarbonate resin has a high melt viscosity at the time of injection molding. Poor fluidity. Therefore, in order to shorten the molding cycle to increase production efficiency and increase the yield of molded products, the molding material to be filled in the cavity is changed from the portion where the thin wall portion that becomes the design surface of the molded product is formed. It is preferable to flow into the cavity.

  However, if the molding material flows in on the design surface of the cover lens using the above valve gate type mold apparatus, a pressing mark (gate mark) by the tip of the valve pin remains clearly on the design surface of the molded product and is transmitted therethrough. The optical path of the irradiation light will be disturbed, and the light distribution characteristics of the vehicular lamp will be adversely affected optically.

  Accordingly, the present invention was devised in view of the above problems, and the object of the present invention is to design a molded product when molding a cover lens constituting a vehicular lamp by injection molding using a valve gate mold apparatus. It is an object of the present invention to provide a valve gate mold apparatus that enables a design surface that suppresses formation of a pressing mark by a tip portion of a valve pin remaining on a surface and hardly causes an adverse optical effect.

  In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention is for a vehicle by filling a cavity formed by a fixed mold and a movable mold with a molten resin through a valve gate. A valve gate mold apparatus for molding a cover lens constituting a lamp, wherein the valve gate is provided in a design surface formation region of the cavity that forms a design surface through which irradiation light in the cover lens is transmitted, The valve pin insertion / removal direction into the gate portion of the valve gate to close and open the flow path of the molten resin is a direction inclined with respect to a direction perpendicular to the surface direction of the design surface forming region of the cavity, and the valve pin The shape of the tip portion is a convex spherical shape or a convex cone shape, and the tip surface is an uneven surface constituted by a plurality of concave portions and convex portions.

  The invention described in claim 2 of the present invention is that in claim 1, the inclination angle θ in the insertion / removal direction of the valve pin with respect to the direction perpendicular to the surface direction of the design surface forming region of the cavity is 0 <θ ≦ 8. It is set in the range of °.

  The invention described in claim 3 of the present invention is characterized in that in claim 1 or claim 2, the molten resin is a polycarbonate resin.

  According to the present invention, a valve gate is disposed in a design surface forming region of a cavity of a molding die that forms a design surface portion of a cover lens, and the molten resin flow path is closed by being inserted into and removed from the gate portion of the valve gate. The insertion / removal direction of the valve pin to be opened was a direction inclined with respect to the direction perpendicular to the surface direction of the design surface formation region of the cavity. In addition, the shape of the tip portion of the valve pin is a convex spherical shape or a convex cone shape, and the tip surface is an uneven surface composed of a plurality of concave portions and convex portions.

  As a result, in particular, when a hard coat treatment is performed after injection molding, the molded product (lens cover) has less noticeable pressing marks due to the tip of the valve pin, and the appearance of the design surface is not impaired. At the same time, it is possible to suppress the pressing mark by the tip of the bulb pin during light transmission from disturbing the optical path of the irradiation light, thereby reducing the adverse effect on the formation of the light distribution pattern. Furthermore, since a biased force due to the valve pin is not applied to the resin injection hole provided in the gate portion of the valve gate or the mold, it is possible to ensure the long life of the mold without impairing the durability.

It is a schematic explanatory drawing of the vehicle lamp. It is explanatory drawing when a vehicle lamp is seen from upper direction. It is sectional explanatory drawing of the injection molding die apparatus of the cover lens which comprises a vehicle lamp. It is explanatory drawing of the front-end | tip part of the valve pin which comprises a valve gate. It is explanatory drawing when the valve pin is removed from the gate part of the valve gate. It is explanatory drawing when a valve pin is inserted in the gate part. It is explanatory drawing of the force which this valve pin receives at the time of obstruction | occlusion of the molten resin flow path by a valve pin. It is explanatory drawing of the press mark by the front-end | tip part of a valve pin. It is explanatory drawing when a hard-coat layer is provided in the molded article. It is explanatory drawing of the press mark by the front-end | tip part of a valve pin. It is explanatory drawing of the front-end | tip part of the other shape of a valve pin.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 11 (the same parts are given the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  1 is a schematic explanatory view of a vehicular lamp, FIG. 2 is an explanatory view of the vehicular lamp attached to the vehicle as viewed from above, and FIG. 3 is a cross-sectional view of a molding die apparatus for injection molding a cover lens constituting the vehicular lamp. It is explanatory drawing.

  For example, as shown in FIG. 1, a vehicular lamp (hereinafter abbreviated as “lamp”) 1 includes a cover lens 3 mounted on a housing 2 to form a lamp chamber 4, and a light source 5 is accommodated in the lamp chamber 4. It has a configuration.

  The cover lens 3 has an opening at one end, and has a design surface 6 that transmits light emitted from the light source 5 and radiates the light toward the outside, and an annular leg 7 that rises from the design surface 6. 2 has an opening and is provided with an annular sealing groove 9 at the opening end 8. Then, the sealing material 10 is filled in the sealing groove 9, and the annular sealing rib 11 provided at the tip of the annular leg portion 7 of the cover lens 3 is inserted into the sealing groove 9 and immersed in the sealing material 10. The sealing rib 9 of the cover lens 3 is hermetically fitted and fixed to the sealing groove 9 of the housing 2 via the sealing material 10.

  By the way, as shown in FIG. 2, the cover lens 3 which comprises the lamp 1 comprises a part of external appearance of a vehicle in the state which attached the lamp 1 to the vehicle body 12, and does not impair the external appearance of a vehicle. Thus, it is formed in a design that is integrated with the body 12 so as to bring out a novel design. Therefore, the upper side is an inclined surface inclined toward the rear side of the vehicle with respect to the vehicle height direction, and the curved surface is turned to the side from the front surface of the vehicle with respect to the vehicle width direction.

  Further, as described above, the cover lens 3 has a design surface that transmits light from the light source and irradiates the light toward the outside. Therefore, it is formed by using a polycarbonate resin that is excellent in transparency and in addition to various performances such as impact resistance, weather resistance, and heat resistance.

  Therefore, when the cover lens having such a shape is manufactured using a polycarbonate resin, it is effective to perform the injection molding using the valve gate type molding die apparatus of the present invention. Hereinafter, the valve gate mold apparatus will be described in detail.

  As shown in FIG. 3, a valve gate type molding device (hereinafter abbreviated as “molding device”) 20 includes a stationary mold (cavity mold) 30 and a movable mold (core mold) 40. The cavity 55 formed by the fixed mold 30 and the movable mold 40 is a thin wall that serves as the design surface of the cover lens. A region (design surface forming region) 56 for forming a portion is a surface inclined with respect to the parting surface 50. In other words, the surface is inclined with respect to the vertical plane with respect to the mold opening direction indicated by the arrow.

  The fixed mold 30 is provided with a valve gate 60 for injecting a polycarbonate resin, which is a molding resin, into the cavity 55 in a molten state. The valve gate 60 has a cylindrical gate portion 61 serving as a molten resin injection portion positioned in the design surface forming region 56 of the cavity 55 and is inserted into and removed from the cylinder 62 of the gate portion 61 so that a flow path of the molten resin is provided. The insertion / removal direction of the valve pin 63 to be closed is the same direction as the mold opening direction of the mold apparatus 20.

  That is, the insertion / removal direction (moving direction) of the valve pin 63 is inclined with respect to the vertical direction of the surface direction of the design surface formation region 56 at the position where the gate portion 61 is disposed in the design surface formation region 56 of the cavity 55. It will be a direction.

  The valve pin 63 is movably disposed in a cylinder 65 of a substantially cylindrical valve main body 64 provided on the stationary mold 30 at the tip, and has an outer peripheral surface of the valve pin 63 and an inner peripheral surface of the valve main body 64. A resin flow channel 66 through which the molten resin passes is provided in the gap. Further, as shown in FIG. 4 (an explanatory diagram of the tip of the valve pin constituting the valve gate), the tip of the valve pin 63 has a convex spherical shape, and the tip surface 70 is composed of a plurality of concave portions and convex portions. It is supposed to be an uneven surface. In this case, the depth of the recess is about 10 μm.

  Returning to FIG. 3, in each of the fixed mold 30 and the movable mold 40, a coolant channel 57 through which a coolant 58 for cooling the molten resin filled in the cavity 55 and promoting solidification flows. Are arranged at appropriate positions, thereby shortening the molding cycle of the molded product and increasing the production efficiency.

  Therefore, when the molten resin 67 of polycarbonate resin is filled into the cavity 55, the valve pin 63 is attached to the valve main body portion 64 as shown in FIG. 5 (an explanatory diagram showing a state where the valve pin is detached from the gate portion of the valve gate). The in-cylinder 65 is moved in the direction opposite to the gate portion 61 along the longitudinal direction of the valve main body portion 64. Then, the valve pin 63 is detached from the cylinder 62 of the gate portion 61 and the cylinder 62 is opened, and the cylinder 62 is secured as the resin flow path 68 of the molten resin 67.

  Then, the molten resin 67 injected from the valve gate 60 through the resin flow path 66 of the valve main body 64 and the resin flow path 68 of the gate part 61 passes through the resin injection hole 31 provided in the fixed mold 30. It is injected into the cavity 55, and the entire inside of the cavity 55 is filled with the molten resin 67.

  Thereafter, as shown in FIG. 6 (an explanatory diagram showing a state in which the valve pin is inserted into the gate portion of the valve gate), the valve pin 63 is inserted into the cylinder body 65 of the valve main body portion 64 along the longitudinal direction of the valve main body portion 64. Move in the direction of 61. Then, the valve pin 63 is inserted into the cylinder 62 of the gate portion 61, the cylinder 62 is closed, and the resin flow path 68 is closed. At the same time, the valve pin 63 is further inserted through the resin injection hole 31 provided in the fixed mold 30, and the tip portion 69 projects into the cavity 55.

  At this time, the molten resin 67 filled in the cavity 55 has started to be cooled and solidified by the cooling liquid 58 flowing through the cooling liquid flow path 57, and the molten resin 67 in the portion from which the tip 69 of the valve pin 63 protrudes is in a semi-solid state. It has become.

  Therefore, as shown in FIG. 7 (an explanatory diagram showing the force received by the valve pin when the valve pin closes the flow path of the molten resin), the tip portion 69 of the valve pin 63 that is in contact with the molten resin 67 in a semi-solidified state. The force in the direction of arrow C is applied by the combined force of the projecting output in the projecting direction of the valve pin 63 indicated by arrow A and the sliding force in the surface direction of the semi-solidified molten resin 67 indicated by arrow B.

  If the sliding force applied in the direction of the arrow C cannot prevent the sliding force applied in the direction of the arrow C, a part of the inner surface 84 of the gate portion 61 of the valve gate 60 and / or the fixed mold 30 is provided. This acts on a part of the inner side surface 85 of the resin injection hole 31 as a biased force by the valve pin 63, and the durability of the valve gate 60 and / or the fixed mold 30 is impaired and the life is shortened.

  On the other hand, in the present invention, as described with reference to FIG. 4, the distal end portion 69 of the valve pin 63 has a convex spherical shape, and the distal end surface 70 is an uneven surface. Therefore, the distal end portion 69 of the valve pin 63 pushed into the semi-solidified molten resin 67 has a spherical shape in which the pressure against the molten resin 67 is evenly distributed and the uneven surface of the distal end surface 70 is in contact with the uneven surface. The part 67 is in a state of being bitten.

  Therefore, the tip portion 69 of the valve pin 63 pushed into the molten resin 67 in a semi-solidified state is restrained from sliding force in the surface direction of the molten resin 67, and a force only in the protruding direction due to the protruding output of the valve pin 63 is applied. Since a biased force due to the valve pin 63 is not applied to a part of the inner side surface 84 of the gate portion 61 of the gate 60 and / or a part of the inner side surface 85 of the resin injection hole 31 provided in the fixed mold 30, the valve The longevity of the mold can be ensured without impairing the durability of the gate 60 and / or the fixed mold 30.

  At the same time, for the molded product after molding, a predetermined concave-shaped pressing mark by the tip portion 69 of the valve pin 63 is formed at a predetermined position with good reproducibility.

  The concave pressing mark 81 on the molded product (cover lens) 80 is formed by transferring the concave / convex surface of the tip surface 70 of the valve pin 63 as shown in FIG. 8 (description of the pressing mark by the tip portion of the valve pin). Is an uneven surface. Therefore, in this state, the uneven surface of the bottom surface 82 of the press mark 81 disturbs the optical path of the irradiated light during light transmission, and adversely affects the formation of the light distribution pattern.

  However, the molded article 80 is generally provided with a transparent hard coat layer 83 in order to improve mechanical properties such as scratch resistance and impact resistance. Therefore, as shown in FIG. 9 (an explanatory diagram showing a state when the hard coat layer is provided on the molded product), the concave press marks 81 including the concave and convex surfaces of the bottom surface 82 are filled with the hard coat layer 83 and hardened. A step between the portion of the press mark 81 and the other portion on the surface of the coat layer 83 is suppressed, and a substantially uniform surface is formed. Further, by making the bottom surface 82 an uneven surface, the hard coat layer 83 can be kept thicker than the adjacent flat surface in an uncured coating film state when the hard coat layer is formed by a wet method.

  As a result, it is suppressed that the press mark 81 disturbs the optical path of the irradiation light during light transmission, and the adverse effect on the formation of the light distribution pattern is reduced.

  Further, as shown in FIG. 10 (an explanatory diagram of a pressing mark by the tip portion of the valve pin), the insertion / removal direction (movement direction) of the valve pin 63 with respect to the gate portion 61 of the valve gate 60 is set to When the direction is perpendicular to the surface direction (in the figure, the central axis is indicated by V) and when the direction is inclined with respect to the direction perpendicular to the surface direction of the design surface forming region 56 (in the figure, the central axis The following difference occurs in the concave pressing mark 81.

That is, when the center axis of the valve pin 63a is positioned at the position V, the angle of inclination of one side of the pressing mark 81a with respect to the surface of the molded product 80 is α ₁ , and the angle of inclination of the other side is α ₂ , the angle of inclination of one side of the press mark 81 b against the surface of the molded product 80 when the central axis of the valve pin 63 _b is positioned at the position U is β ₁ , and the angle of inclination of the other side is Assuming β ₂ , α ₁ > β ₁ and α ₂ > β ₂ are satisfied. Incidentally, there is a relationship of α ₁ = α ₂ and β ₁ <β ₂ .

  That is, the design surface is formed when the insertion / removal direction (movement direction) of the valve pin 63 with respect to the gate portion 61 of the valve gate 60 is inclined with respect to the direction perpendicular to the surface direction of the design surface formation region 56. The inclination angle of the press mark 81 with respect to the surface at the surface position of the molded product 80 becomes smaller than when the direction is perpendicular to the surface direction of the region 56.

  As a result, the conspicuousness of the portion of the press mark 81 that becomes a stepped portion with respect to the surface of the molded product 80 is reduced, and the appearance of the design surface is not impaired. Therefore, by providing a hard coat layer on this, further improvement in appearance and further adverse effects on the adverse effect on the formation of the light distribution pattern can be achieved.

  In particular, when the refractive index of the molded product is different from the refractive index of the hard coat layer, light is refracted at the interface between the two, so that the stepped portion is easily noticeable. Therefore, by reducing the inclination angle of the press mark 81 with respect to the surface at the surface position of the molded product 80, the degree of conspicuousness of the stepped portion can be reduced.

  The angle range θ in the insertion / removal direction (moving direction) of the valve pin 63 with respect to the direction perpendicular to the surface direction of the design surface formation region 56 of the cavity 63 is 0 <θ ≦ 8 °, that is, greater than 0 ° and 8 ° or less. Preferably there is. When θ> 8 °, that is, greater than 8 °, the tip portion slips in the surface direction of the semi-solidified molten resin when the valve pin protrudes, thereby forming an appropriate pressing mark as in the present invention. Can not.

  In addition, a biased force due to the valve pin is applied to the resin injection hole provided in the gate portion of the valve gate and the fixed mold, and the durability of the mold is impaired and the life is shortened.

  As described above, the present invention adopts a valve gate type molding die as an injection molding die for forming a cover lens of a vehicle lamp by injection molding of polycarbonate resin, and includes a fixed die and a movable die. The gate portion of the valve gate is positioned in a region (design surface formation region) that serves as a design surface of the lens cover in the cavity formed in (1).

  In addition, the design surface formation region of the cavity is located at a predetermined angle with respect to the vertical surface in the mold opening direction of the mold, and the cylinder of the gate portion of the valve gate with respect to this design surface formation region. The insertion / removal direction of the valve pin that is inserted into and removed from the inside and closes the flow path of the molten resin was the same as the mold opening direction of the mold.

  Furthermore, when the resin flow path of the valve gate is closed, the tip portion of the valve pin that is pushed into the molten resin filled in the design surface formation region of the cavity has a convex spherical shape, and the tip surface has a plurality of concave portions and convex portions. An uneven surface composed of

As a result, the molded product (lens cover) that has been hard-coated after injection molding has less noticeable marks from the tip of the valve pin, and the appearance of the design surface is not impaired.
At the same time, it is possible to prevent the traces of the tip of the bulb pin from disturbing the optical path of the irradiated light during light transmission, thereby reducing the adverse effect on the formation of the light distribution pattern.

  At the same time, since a biased force due to the valve pin is not applied to the resin injection hole provided in the gate portion of the valve gate or the fixed mold, it is possible to ensure the long life of the mold without impairing the durability.

  The tip shape of the valve pin 63 is not limited to the convex spherical shape described above, but may be a conical shape as shown in FIG. 11 (an explanatory diagram of the tip portion of another shape of the valve pin). Also in this case, it is preferable that the front end surface 70 is an uneven surface composed of a plurality of concave portions and convex portions.

  Thereby, the same effect | action and effect as the case where the front-end | tip shape of the said valve pin is made into a convex spherical shape can be acquired.

DESCRIPTION OF SYMBOLS 1 ... Vehicle lamp 2 ... Housing 3 ... Cover lens 4 ... Light chamber 5 ... Light source 6 ... Design surface 7 ... Leg part 8 ... Open end 9 ... Seal groove 10 ... Sealing material 11 ... Seal rib 12 ... Body 20 ... Mold Apparatus 30 ... Fixed mold (cavity mold)
31 ... Resin injection hole 40 ... Movable mold (core mold)
50 ... Butting surface (parting surface)
55 ... Cavity 56 ... Design surface formation region 57 ... Coolant flow path 58 ... Coolant liquid 60 ... Valve gate 61 ... Gate part 62 ... In-cylinder 63 ... Valve pin 64 ... Valve body part 65 ... In-cylinder 66 ... Resin channel 67 ... Molten resin 68 ... Resin channel 69 ... Tip 70 ... Tip surface 80 ... Molded article 81 ... Press mark 82 ... Bottom surface 83 ... Hard coat layer 84 ... Inside surface 85 ... Inside surface

Claims (3)

A valve gate mold apparatus for molding a cover lens constituting a vehicular lamp by filling molten resin through a valve gate into a cavity formed by a fixed mold and a movable mold,
The valve gate is provided in a design surface forming region that forms a design surface of the cavity through which irradiation light in the cover lens is transmitted,
The insertion and removal direction of the valve pin that inserts and removes into the gate portion of the valve gate to open and close the flow path of the molten resin is a direction inclined with respect to the vertical direction of the surface direction of the design surface forming region of the cavity,
The valve gate mold apparatus is characterized in that the tip portion of the valve pin has a convex spherical shape or a convex conical shape, and the tip surface is an uneven surface composed of a plurality of concave portions and convex portions.   2. The valve gate according to claim 1, wherein an inclination angle θ of a valve pin insertion / removal direction with respect to a direction perpendicular to a surface direction of a design surface forming region of the cavity is set in a range of 0 <θ ≦ 8 °. Mold device.   3. The valve gate mold apparatus according to claim 1, wherein the molten resin is a polycarbonate resin.

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