JP5238213B2 - Front cover of vehicle lamp - Google Patents

Description

  In the present invention, a runner as a resin passage is disposed along a longitudinal side edge of a front cover molding cavity provided in a mold, and melted from a wide side gate provided between the runner and the cavity side edge. A front cover of a vehicular lamp formed by injecting resin into a cavity, and formed into a shape in which a thin thin string-like gate land remains along a longitudinal side edge of the front cover as a molded body. Regarding the front cover.

  Since a recent automotive headlamp has a tendency to dispose the light source unit for passing beam forming and the light source unit for traveling beam forming adjacent to the left and right in the lamp body as shown in Patent Document 1 below, Is formed in a horizontally long rectangular shape in front view that is longer to the left and right than to the top and bottom.

  In addition, resin products such as the front cover, which is a lamp component, are mainly manufactured by injection molding, but the resin remains efficiently in the entire cavity provided in the mold so that the trace of the gate remaining on the product is not noticeable. In the following Patent Document 2, a side gate provided at a substantially central position of a side edge in the longitudinal direction of a cavity (a general side gate has a gate width of 5 to 10 mm and a gate thickness of 2 to 3 mm). The molten resin is injected into the cavity and molded.

JP-A-9-147604 JP 2004-237586 A

  However, in the headlamps found in Patent Document 1 and the like, not only the lamp body is increased in size but also the front cover assembled on the front side of the lamp body is increased in size, which increases the weight of the entire headlamp. ing.

  Therefore, the inventor has considered reducing the total weight of the headlamps by reducing the thickness of the front cover.

  The thickness of the front cover, which is a resin injection molded product, is a length L2 that allows the resin to flow physically, the maximum flow length L1 being a value unique to the resin (the length that the resin can flow per unit thickness) Since it is determined by the value L1 / L2 divided by 1, conventionally, as shown in Patent Document 2, a gate is provided at a substantially central position of the side edge in the longitudinal direction of the cavity to shorten the maximum flow length L1 from the gate to the end of the cavity. By doing so, the front cover is made thinner, but there is a limit to shortening the maximum flow length L1.

  In addition, if a plurality of gates (for example, a two-point side gate system) is used, the maximum flow length L1 can be shortened and the front cover can be thinned. However, in the two-point side gate system, the average wall thickness is about 3 mm. . Further, the resin flow from each gate collides with each other, and a weld (resin association) occurs, resulting in a new problem that the product appears as a sink mark and looks bad.

  In order to reduce the value L1 / L2 that determines the thickness of the front cover that is an injection molded product of the resin, the inventor reduces the maximum flow length L1 and physically adds the resin, which is a value unique to the resin. We thought it necessary to consider both the expansion of the flowable length L2. That is, the width of the side gate can be increased by arranging the runner along the side edge of the cavity and providing the side gate between the runner and the side edge of the cavity. If the resin flow injected from the entire area of the expanded gate width is rectified, the maximum flow length L1 approaches the length (shortest) of the side edge of the cavity in the short direction, and the weld is generated. No sink marks become apparent because they are not. Also, if the pressure loss at the gate is reduced, the length L2 (the length that the resin can flow per unit thickness), which is a value inherent to the resin, is increased and the thickness is reduced. I thought it was possible.

  And as a result of repeated consideration based on injection molding simulation of the front cover using CAE (computer injection molding simulation technology), the runner is disposed along the side edge in the longitudinal direction of the cavity, and the runner and cavity The gate provided between the side edges of the cavity is formed wide from the center of the side edge in the longitudinal direction of the cavity to the end side so as to expand along the runner arrangement direction, with a predetermined gate thickness and a predetermined The length before and after the gate was confirmed to be effective for reducing the thickness of the front cover, and the present application has been completed.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a front cover for a vehicular lamp that is thin and does not reveal sink marks.

In order to achieve the above object, in the front cover of the vehicular lamp according to claim 1, the side edge in the longitudinal direction of the cavity for molding a resin front cover that is horizontally long when viewed from the front, which is a lamp component member provided in the mold. A front cover of a vehicular lamp formed by arranging a runner along a portion, and injecting molten resin into the cavity from a gate provided between the runner side surface and the cavity side edge,
The gate is formed in a wide and uniform width (the runner side gate width is the same as the cavity side gate width) from the substantially longitudinal center of the cavity to both sides along the runner arrangement direction. The thickness T is configured to be 1.0 to 1.5 mm and the longitudinal length L is configured to be 1.5 to 3 mm. The flow of the molten resin injected from the gate is orthogonal to the gate width direction in the entire gate width. The rectification is such that the cavity is filled.

  (Operation) The thickness of the front cover, which is an injection molded product, is a length L2 that allows the resin to flow physically, the maximum flow length L1 being a value unique to the resin (the length that the resin can flow per unit thickness) L1 / L2 is reduced by decreasing L1 and increasing L2 (the thickness of the front cover can be reduced).

  As the front cover of a vehicle lamp, the length of the front cover of the headlamp, which is preferred to be large, is 700 mm in length, but the gate extends from approximately the center of the cavity in the longitudinal direction to the runner arrangement direction. Extending to both sides, for example, a wide gate with a width of 15 times or more (W150 mm or more) compared to a conventional side gate (gate width less than 10 mm), the maximum flow length L1 is remarkably shortened, and the molded product This is effective for reducing the thickness of the front cover. From the viewpoint of shortening the maximum flow length L1, it is desirable to increase the gate width W if it is equal to or less than the length of the front cover (cavity) in the longitudinal direction, but this leads to a molded product taken out from the mold. For convenience when removing the cull at the gate land position, it is desirable that the gate width (the length of the gate land) is not so large.

  FIG. 7 shows the result of injection molding simulation using a wide gate whose width W corresponds to the total length of the side edge in the longitudinal direction of the cavity (the thickness of the gate and the flow pattern of the resin with respect to the length before and after the gate). By configuring the thickness T of the gate to be 1.0 to 1.5 mm, the flow of the molten resin injected from the gate is rectified perpendicular to the gate width direction in the entire gate width, as shown in this figure. For this reason, the length in the short side direction of the cavity (minimum value that cannot be considered any more) becomes the maximum flow length L1, L1 / L2 becomes small (the thickness of the front cover can be reduced), and the resin flow collides. Since no weld occurs, sink marks do not appear in the molded product.

  In addition, when the gate thickness T is as small as 0.5 mm, the pressure loss at the gate is naturally large. However, as the gate width direction end portion farther from the resin supply position in the runner, the shear heat generation occurs. The influence of the resulting viscosity reduction of the resin is remarkable, and the resin flow becomes active.

  Further, when the gate thickness T is 1.0 to 1.5 mm, the length L of the gate is set to 3 mm or less so that the pressure loss at the gate is as small as possible (less than 46 MPa). That is, the length L2 that can physically flow the resin (the length that allows the resin to flow per unit thickness) is increased, and the value of L1 / L2 is further decreased (further thinner). ) Note that when the front-rear length L of the gate is less than 1 mm, the flow of the molten resin injected from the gate is not rectified perpendicular to the gate width direction in the entire gate width, and the maximum flow length L1 cannot be shortened.

  In this way, rectification (parallel flow) with the same flow velocity is ensured with low pressure loss at any position in the width direction of the gate having a width W substantially corresponding to the entire length of the longitudinal side edge of the cavity. For this purpose, it is desirable that the gate thickness T is 1.0 to 1.5 mm, and the length L of the gate is 1.5 to 3 mm. In particular, when the gate thickness T is 1.0 mm and the longitudinal length L of the gate is 3 mm, the flow of the molten resin injected from the gate is almost the same speed from the beginning to the end at any position in the gate width direction. This is the optimum condition for thinning the front cover.

  FIG. 7 shows the result of an injection molding simulation using a gate whose width W corresponds to the entire length of the side edge in the longitudinal direction of the cavity (the flow pattern of the resin and the pressure loss with respect to the gate thickness and the length before and after the gate). However, when a gate whose width W is shorter than the total length of the longitudinal side edge of the cavity is used, for example, even when the gate width is 150 mm or more, the longitudinal center of the longitudinal side edge of the cavity is substantially at the center. When the wide gate is disposed in the part, the resin injected from the gate into the cavity spreads almost evenly on the side of the edge in the longitudinal direction of the cavity where the gate is not provided. Although it is assumed that the cavity is somewhat arcuate on the side of the edge in the longitudinal direction of the cavity, it is assumed to have a shape substantially parallel to the gate. In each case above, it is considered to be the same results as in FIG. 7.

  The front cover having an average wall thickness of 2.0 mm, which is an injection molded product corresponding to the shape of the cavity, has a length W (150 mm or more) and thickness corresponding to the wide gate along the longitudinal side edge. A thin, thin string-like gate land of T (1.0 to 1.5 mm) and width L (1.5 to 3 mm) is integrally formed, so that a water jet, a rotary blade cutter, an ultrasonic cutter, a hydraulic press, The front cover, which is a product, is configured by cutting and removing the gate land at the boundary with the front cover by a cutting device such as a laser.

  According to a second aspect of the present invention, in the front cover of the vehicular lamp according to the first aspect, the front-rear length of the gate becomes shorter from the vicinity of the resin supply path communicating with the runner toward the end in the gate width direction. It was configured as follows.

  (Operation) The runner provided with the wide gate is supplied with resin through, for example, a sprue portion (another runner), and the injection pressure at the predetermined position in the width direction of the wide gate (from the resin supply position to the runner to the gate) The pressure loss up to a predetermined position in the width direction is inversely proportional (proportional) to the distance from the resin supply position to the runner, but the front and rear length of the gate (gate land width) L is from the sprue portion (other runners) Is set (constituted so as to be inversely proportional to the distance from the sprue portion), that is, the front and rear length (gate land width) L of the gate is shorter as it is farther from the resin supply position to the runner. Since it is configured to be (narrow), the pressure loss due to the distance from the resin supply position to the runner (decrease in injection pressure) and the pressure loss due to the length L of the gate (width of the gate land) L The sum of the drop) in pressure, difference of the injection pressure is relieved in the width direction of the substantially constant and becomes (wider gate at any position in the width direction of the gate).

  According to a third aspect of the present invention, in the front cover of the vehicular lamp according to the first or second aspect, the front cover extends so that a design surface region thereof is inclined rearward and is thinner toward an upper side in a front view (thicker toward a lower side). ) And with the lower side in front view as the runner arrangement side of the cavity.

  (Operation) Compared with the case where the front cover has a nearly vertical shape, the person in contact with the automobile can move upward along the front cover as much as the rear cover is inclined, and there is less impact on the person. Further, since the front cover is formed so as to be thinner toward the upper side when viewed from the front, the front cover is easily deformed and easily broken in the thin region, so that the impact at the time of a collision acting on a person is reduced.

In injection molding, the closer to the gate, the lower the pressure loss (higher injection pressure). The lower the pressure loss (higher injection pressure), the smoother the surface of the molded product and the higher the pressure loss (injection pressure). Although there is a disparity that the surface of the molded product is not smooth on the side far from the gate, the front view lower side, which is the thick side of the front cover, is closer to the gate ( upper side view, which is the thin side of the front cover) Because the pressure is almost proportional to the thickness of the resin in the cavity, the molding surface is smooth on the entire surface of the front cover. Is formed.

  As apparent from the above description, according to the front cover of the vehicular lamp according to the first aspect, the gate width is formed to a size corresponding to substantially the entire length of the longitudinal side edge of the front cover, and the thickness of the gate. Since the length of the gate and the length of the front and rear of the gate are set in such a range that the flow of the resin in the entire width of the gate is rectified, the front cover is reduced in thickness and weight, and a vehicular lamp with a reduced total weight is provided.

  Moreover, since the front cover without sink marks is obtained, the appearance of the vehicular lamp can be improved.

  Further, the thinning of the front cover reduces the impact force at the time of a collision that acts on a person because the front cover is likely to be deformed and easily broken during a car collision.

  According to the second aspect, the injection pressure in the wide gate is substantially constant in the width direction, and the flow of the molten resin is surely rectified in the entire width of the gate, so that the thin front cover as designed with good appearance can be obtained. can get.

  According to the third aspect of the present invention, the front cover is formed by a pressure that is substantially proportional to the thickness thereof, so that a high-quality front cover having a smooth entire surface can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1-7 shows the Example of the front cover of the vehicle lamp which concerns on this invention, FIG. 1 is the principal part of the injection molding apparatus which shape | molds the front cover of the headlamp for motor vehicles which is one Example of this invention. 2 is a longitudinal sectional view of the mold apparatus (cross-sectional view taken along line II-II shown in FIG. 1), and FIG. 3 is a diagram showing the distance from the first runner and the width of the wide gate. FIG. 4 is a plan view (cross-sectional view taken along line III-III shown in FIG. 1) for explaining the relationship with the front-rear length, and FIG. 4 schematically shows the arrangement of cavities, gates, runners and sprue portions applied to CAE. FIG. 5 is a longitudinal sectional view of the mold apparatus (cross-sectional view taken along line VV shown in FIG. 4), and FIG. 6A is a diagram showing the relationship between the gate thickness and pressure loss. , (B) is a diagram showing the relationship between the longitudinal length of the gate and the pressure loss, and FIG. 7 shows the width of the cavity in the longitudinal direction. FIG. 8 is a view showing a result of injection molding simulation using a gate corresponding to the total length of the part (the thickness of the gate and the flow pattern of the resin with respect to the length of the front and back of the gate). FIG. 8 is a front cover manufactured using the injection molding apparatus. It is the longitudinal cross-sectional view of the headlamp for motor vehicles.

  In FIG. 8, a head lamp for an automobile has a clear front cover 12 assembled to the front opening of a container-like lamp body 10 that opens to the front side to define a lamp chamber S. In the lamp chamber S, A resin reflector 14 in which a discharge bulb 16 as a light source is inserted and integrated is supported so as to be tiltable by an aiming mechanism (one aiming fulcrum and two aiming screws) (not shown), and the optical axis of the headlamp is moved vertically. In addition, it is configured so that tilt adjustment (aiming) can be performed in the left-right direction.

  A resin extension reflector 20 is provided inside the front opening of the lamp body 10 so as to extend around the reflector 14. The extension reflector 20 is provided with an opening 20a that matches the outer shape of the reflector 14 so as not to interfere with the reflected light distribution formed by the reflector 14 disposed behind the extension reflector 20. Further, the front surfaces of the extension reflector 20 and the reflector 14 are each subjected to an aluminum vapor deposition process, so that the entire interior of the lamp chamber S looks like a specular color and the appearance of the headlamp when not lit is good. Reference numeral 18 denotes a shade that is disposed in front of the discharge bulb 16 and shields light that travels outside the effective reflection surface of the reflector 14, and its leg portion 18a is fixed to the peripheral portion of the bulb insertion hole.

  The front opening of the lamp body 10 is formed in a substantially horizontally long rectangular shape when viewed from the front, which is longer in the left-right direction than in the up-down direction. The front opening of the lamp body 10 is assembled to the front opening of the lamp body 10. The front cover 12 is formed to have a substantially horizontally long rectangular shape when viewed from the front, which is longer in the left-right direction than in the up-down direction.

  The front cover 12 is very large although the horizontal length along the horizontal section and the vertical length along the vertical section are about 700 mm and about 340 mm, respectively, and the average thickness is about 2.0 mm. It is thin and light in weight, and functions effectively in reducing the total weight of the headlamp.

  Further, the front cover 12 is largely inclined rearward so as to follow the streamline shape of the vehicle body 22, and the thickness t of the design surface region of the front cover 12 is formed so as to decrease from the lower side 12a to the upper side 12b. That is, the thickness tb on the upper side 12b of the design surface area of the front cover 12 is formed thinner than the thickness ta on the lower side 12a.

  For this reason, compared with the case where the design surface area | region of the front cover 12 is a shape close | similar to the perpendicular | vertical shape, the person who contacted the motor vehicle can move upward along the front cover 12, and acts on a person by the part inclined back. There is little impact. Further, since the front cover 12 is easily deformed and easily broken in the thin region on the upper side 12b when viewed from the front, the impact at the time of a collision acting on a person is reduced.

  The injection molding apparatus shown in FIGS. 1 and 2 is an apparatus that molds the front cover 12 and faces the fixed mold 100 on the side where the resin is injected from the resin injection nozzle 90 of the injection machine and the fixed mold 100. And a movable mold 200 slidable in the approaching / separating direction (the vertical direction in FIGS. 1 and 2). The movable mold 200 can be slid in the direction of the arrows in FIGS. 1 and 2 by a hydraulic cylinder mechanism that is a mold drive mechanism (not shown).

  A cavity C for molding the front cover 12 is formed between the fixed mold 100 and the movable mold 200 constituting the mold apparatus.

  The movable mold 200 includes a movable mold body 200A and a slide mold 200B that can slide (slide) in the arrow direction with respect to the movable mold body 200A. That is, as described above, since the front cover 12 is configured to largely wrap around from the vehicle front side to the side, the front cover 12 wraps around the vehicle side (the side of the cavity C corresponding to the side). An undercut portion C1 that cannot be formed by a corresponding pair of mold structures is formed on the edge side), and a slide mold 200B for forming the undercut portion C1 is provided.

  On the other hand, the fixed mold 100 is provided with a sprue bush 91 provided with a resin injection hole 93 that opens to the nozzle engaging portion 92. The resin injection hole 93 and the cavity C are vertically connected to the sprue. A first runner 94 extending from the inner bottom portion of the bush 91 at right angles to the sprue portion 91a, a second runner 95 extending perpendicularly to the first runner 94 and along the side edge of the cavity C, and a second The runner 95 and the cavity C are connected via a wide gate 96. The first runner 94, the second runner 95, and the wide gate 96 are disposed along a parting line PL between the fixed mold 100 and the movable mold body 200A.

  Specifically, the cavity C defined by the molding surfaces corresponding to the outer and inner surfaces of the front cover 12 formed on the molds 100 and 200, respectively, is formed in a shape that matches the front cover 12 that is horizontally long when viewed from the front. The longitudinal direction (short direction) of the cavity C corresponds to the left and right direction (vertical direction) of the front cover 12. 1 is the lateral direction (longitudinal direction) of the cavity C, and the vertical direction (perpendicular direction of the paper plane) in FIG. 8 is the lateral direction (longitudinal direction) of the front cover 12. The cavity C is formed so that the seal leg of the front cover 12 which is a molded product is in the vertical direction, and the gate 96 is formed so that a gate mark remains on the flange portion between the side wall of the front cover 12 and the seal leg. Has been placed. That is, the second runner 95 is disposed along the longitudinal side edge of the cavity C (the flange between the side wall of the front cover 12 and the seal leg), and the gate 96 is disposed on the longitudinal side edge of the cavity C. The short direction of the cavity C along the second runner 95 disposition direction (the flange portion extending direction between the side wall of the front cover 12 and the seal leg) from the substantially central portion (the position where the first runner 94 is connected) in the longitudinal direction. The width of the runner 95 and the width of the wide gate 96 are set to about 330 mm.

  Then, after the molds 100 and 200 are clamped, the molten resin is injected from the resin injection nozzle 90 of the injection machine into the resin injection hole 93 of the fixed mold 100. The injected molten resin is injected and filled into the cavity C from the wide gate 96 through the sprue bush 91 (sprue portion 91a) and runners 94 and 95 which are resin supply paths provided in the molds 100 and 200. When filling of the cavity C with resin is completed, the molded product (front cover 12) is taken out through a pressure holding process, a cooling process, and a mold opening process.

  Since the molded product taken out from the mold has a form in which cal (gate land, runner portion and spool portion molded body) is integrally connected to the front cover 12, such as laser, water jet, rotary blade cutter, etc. By cutting and removing this cull at the boundary with the front cover 12 (gate land root position of the front cover 12) by the cutting device, the front cover 12 which is a product is configured.

  Each of the first and second runners 94 and 95 has a diameter of 14 mm, and the wide gate 96 has a width W (length in the direction perpendicular to the plane of FIG. 1) W along the longitudinal side edge of the cavite C. In addition, the longitudinal side edge of the Cavite C is approximately 700 mm in the longitudinal center and is configured to have a width of 330 mm, which is more than 30 times the width of the conventional side gate (less than 10 mm), and its thickness. Since the length T is 1.0 mm and the average longitudinal length (length in the left-right direction in FIG. 1) L is about 3 mm, the flow of the molten resin injected from the gate 96 is substantially orthogonal to the gate width direction. It can be estimated from the simulation results shown in FIG. 7 that the rectification (parallel flow) is filled in the cavity C and the pressure loss in the gate 96 is kept low.

  For this reason, compared with the conventional side gate, the maximum flow length L1 is remarkably shortened, and L1 / L2 which determines the thickness of the front cover 12 is reduced (the thickness of the front cover can be reduced). The resin flow is substantially rectified over the entire width in the longitudinal direction of the cavity, so that there is no weld where the resin flow collides (there is no occurrence of sink marks in the molded product). Further, since the pressure loss at the gate 96 is low, the flow length of the resin becomes long, and the length L2 (flow length ÷ unit thickness inherent to the resin) that allows the resin to flow physically increases. The value of becomes smaller (can be made thinner). As a result, the front cover 12 having an average wall thickness of 2.0 mm that cannot be achieved by the conventional side gate method is formed.

  Further, the longitudinal length Ld of the gate 96 is, as shown in FIG. 3, a distance from the first runner 94 communicating with the second runner 95 (distance from the sprue portion 91a communicating with the runners 94, 95) d. The width of the wide gate 96 (in the vertical direction in FIG. 3) is adjusted so that substantially the same injection pressure is obtained at any position.

That is, the runner 95 provided with the wide gate 96 is supplied with resin through the sprue portion 91a and the first runner 94, but the injection pressure at the predetermined position in the width direction of the wide gate 95 (from the runner 94 to the gate). 96 (pressure loss up to a predetermined position in the width direction) is inversely proportional to the distance d from the runner 94, and the longitudinal length of the gate 96 (the width of the gate land) Ld takes the distance d from the runner 94 into account. It is set (configured to be inversely proportional to the distance d from the runner 94). In other words, as illustrated in FIG. 3, the front-rear length (gate land width) L of the gate 96 is configured to be shorter (narrower) as it is farther from the runner 94 (front-rear length Ld2 <distant from the runner 94 < Since the front-rear length Ld1 in the vicinity of the runner 94 is set, the pressure loss due to the distance from the runner 94 (reduction in injection pressure) and the pressure loss due to the front-rear length of the gate 96 (width of the gate land) L (reduction in injection pressure). ) Is substantially constant at any position in the width direction of the gate 96 (the disparity in the injection pressure in the width direction of the wide gate 96 is alleviated), and the flow of the molten resin is reliably rectified over the entire width of the gate 96. Therefore, the thin front cover 12 having a good appearance as designed can be obtained.

  Further, the front cover 12 is formed such that the thickness t of the design surface region is thinner as the upper side 12b in the front view (thickness as the lower side 12a) (ta> tb), but the lower side 12a in the front view is formed in the cavity C. Since molding is performed on the runner 95 side, molding pressure almost proportional to the thickness acts on the resin filled in the cavity C, and a high-quality front cover 12 having a smooth entire surface is molded. The

That is, in the injection molding, the pressure loss is lower (injection pressure is higher) as the side is closer to the gate 95, and the surface of the molded product is smoother and pressure loss is larger (injection) as the pressure loss is lower (injection pressure is higher). Although there is a disparity that the surface of the molded product is not smooth on the side far from the gate 96 (the pressure is small), the front view lower side 12a, which is the thick side of the front cover 12, is closer to the gate 96 (the thin wall of the front cover 12). Since the injection molding is performed such that the upper side 12b in the front view is the side far from the gate 96), the resin in the cavity C is subjected to a pressure substantially proportional to the thickness thereof, and the front surface of the molded product. A smooth molding surface is formed on the entire surface of the cover 12.
Next, based on FIGS. 4 to 7, a description will be given of appropriate gate dimensions effective for thinning the front cover obtained by using CAE (computer injection molding simulation technique).

  As shown in FIGS. 4 and 5, the injection molding apparatus is substantially the same as the apparatus shown in FIGS. 1 and 2, and only the different configuration will be described, and the other components will be denoted by the same reference numerals, and redundant description thereof will be omitted. To do.

  Between the molds 100 and 200, a cavity C corresponding to a flat front cover having a horizontally long rectangular shape in front view and having a horizontal direction of 500 mm, a vertical direction of 200 mm, and a thickness of 2.5 mm is provided. Direction) corresponds to the left-right direction (up-down direction) of the front cover. A second runner 95 having a diameter of 14 mm is disposed along the longitudinal side edge of the cavity C, and a first runner 94 having a diameter of 14 mm is orthogonal to the longitudinal center of the second runner 95. So connected. The length of the second runner 95 is substantially the same as the length of the cavity C in the longitudinal direction, and a wide gate 96 is provided between the cavity C and the runner 95. The width of the gate 96 (length in the vertical direction in FIG. 4) corresponds to the size (length) of the side edge in the longitudinal direction of the cavity C, the thickness of the gate 96 is T, and the length of the gate 96 is L Change in pressure loss with respect to the thickness T (0.5 to 2.5 mm) of the gate 96, change in pressure loss with respect to the length L (1.5 to 6.0 mm) of the gate, and the thickness T of the gate. As a result of analyzing the flow pattern of the resin with respect to the longitudinal length L, the following was found.

  As shown in FIG. 6A, the thickness T of the gate 96 is inversely proportional to the pressure loss in the gate 96, and the pressure loss increases (over 50 MPa) when T is less than 1.0 mm. Accordingly, the length L2 (flow length ÷ unit thickness inherent to the resin) that allows the resin to flow physically decreases, and the value of L1 / L2 increases (cannot be thinned). Furthermore, if the pressure loss at the gate 96 is large, a large injection pressure (large molding apparatus) is required to secure the flow length of the resin, and the cost is increased accordingly. On the other hand, as shown in FIG. 7, when T exceeds 1.5 mm, the same is true when T is less than 1.0 mm. Is not effective for shortening the maximum flow length L1. Specifically, as shown in FIG. 7, when T is less than 1.0 mm (for example, T is 0.5 mm), in addition to the large pressure loss in the gate 96, the flow pattern of the molten resin injected from the gate 96 is Since the flow is faster at the end in the gate width direction (the flow is slower at the center in the gate width direction), not to be rectified, of course, the two flows from both ends in the gate width merge and weld (resin Meeting) may occur. When T exceeds 1.5 mm (for example, when T = 2.5 mm), the flow pattern of the molten resin is an arc-shaped pattern that is slower toward the end in the gate width direction (the flow pattern in the case of a conventional side gate). Of course, the rectification does not occur and the maximum flow length L1 is not shortened.

  Therefore, in order that the pressure loss in the gate 96 is about 46 MPa or less and the flow of the molten resin in the entire width of the gate is rectified (the maximum flow length L1 is shortened), the thickness T of the gate 96 is 1.0 to It is desirable to be in the range of 1.5 mm.

On the other hand, the front-rear length (gate land length) L of the gate 96 is proportional to the pressure loss in the gate 96 as shown in FIG. 6B , and the pressure loss exceeds 46 MPa when L is 6.0 mm or more (L When the pressure exceeds 3.0 mm, the pressure loss exceeds about 46 MPa), the flow length of the resin is shortened accordingly, and the length L2 (the resin per unit wall thickness) can physically flow the resin, which is an inherent value of the resin. The length that can flow is also reduced, and the value of L1 / L2 is increased (cannot be thinned). Further, if the pressure loss in the gate 96 is large (for example, exceeding 46 MPa), a large injection pressure (large molding apparatus) is required to secure the flow length of the resin, and the cost increases accordingly. Therefore, the front-rear length (gate run length) L of the gate 96 is desirably 3.0 mm or less. Further, although not shown when L is less than 1.5 mm, the pressure loss is smaller, but there is more disparity in the flow rate of the resin in the gate width direction than when L is 1.5 mm (rectification and rectification). It is estimated that

  Accordingly, a flow pattern (rectification, parallel flow) is formed in which the pressure loss at the gate 96 is about 46 MPa or less and the flow of the molten resin injected from the gate 96 is almost the same speed at any position in the gate width direction. In order to shorten the maximum flow length L1, it is desirable that the longitudinal length (gate land length) L of the gate 96 is in the range of 1.5 to 3 mm.

  Thus, in order to ensure rectification (parallel flow) with the same flow velocity at any position in the gate width direction under low pressure loss, the thickness T of the gate 96 is 1.0 to 1.5 mm. The length L of 96 is preferably in the range of 1.5 to 3 mm. Within this predetermined range, in particular, when the thickness T of the gate 96 is 1.0 mm and the front-rear length L of the gate 96 is 3 mm, the flow of the molten resin injected from the gate 96 can be determined in the gate width direction. Even in the position, rectification (parallel flow) having substantially the same speed from the beginning to the end is formed, which is an optimum condition for thinning the front cover.

  In the above-described embodiment, the horizontal section formed by injection molding using a wide gate having a width of the gate 96 of about 330 mm, a gate thickness T of 1.0 mm, and an average longitudinal length L of the gate 96 of about 3 mm. The front cover 12 having a horizontal length of about 700 mm, a length of about 340 mm, and an average thickness of about 2.0 mm has been described. In injection molding using a wide gate having a thickness of 150 mm, a gate thickness T of 1.0 mm, and an average longitudinal length L of the gate 96 of about 3 mm, the front cover (e.g. Front cover whose horizontal length along the horizontal section and vertical length along the vertical section are about 300 mm and about 150 mm, respectively, and whose average wall thickness is less than 2.0 mm. In the prior art, injection molding using a wide gate having a gate 96 width of about 150 mm or more, a gate thickness T of 1.0 to 1.5 mm, and an average longitudinal length L of the gate 96 of about 1.5 to 3 mm. A thin front cover for a headlamp having an average thickness of less than 2 mm that could not be achieved can be formed.

  In the above embodiment, the entire width of the wide gate 96 and the entire length of the runner 95 are configured to be the same. However, the entire width of the wide gate 96 may be shorter than the entire length of the runner 95. However, it is desirable to make the entire width of the wide gate 96 and the entire length of the runner 95 the same length in order not to eliminate useless pressure loss in the resin passage or increase the volume of the cull removed after molding.

  In the above-described embodiment, the first runner 94 communicates with the central portion in the longitudinal direction of the runner 95 provided with the wide gate 96. However, the position where the first runner 94 communicates is the first position. The runner 94 is not limited to the substantially central portion in the longitudinal direction.

  Alternatively, the sprue portion 91a may directly communicate with the runner 95 provided with the wide gate 96 without the first runner 94 interposed.

  In the above-described embodiment, the configuration of the front cover 12 of the headlamp for automobiles has been described. However, the present invention is not limited to the front cover 12 of the headlamp, and the configuration of the front cover of a sign lamp or other vehicle lamps. Needless to say, it can be widely applied.

It is a longitudinal cross-sectional view of the metal mold | die apparatus which is the principal part of the injection molding apparatus which shape | molds the front cover of the headlamp for motor vehicles which is one Example of this invention. It is a longitudinal cross-sectional view (cross-sectional view which follows the line II-II shown in FIG. 1) of the metal mold apparatus. It is a top view for demonstrating the relationship between the distance from a 1st runner, and the front-back length of a wide gate (sectional drawing which follows the line III-III shown in FIG. 1). It is a top view of the mold apparatus which shows typically arrangement of a cavity, a gate, a runner, and a sprue part applied to CAE. It is a longitudinal cross-sectional view (sectional view which follows the line VV shown in FIG. 4) of the metal mold | die apparatus. (A) is a figure which shows the relationship between the thickness of a gate, and pressure loss, (b) is a figure which shows the relationship between the gate front-back length and pressure loss. It is a figure which shows the result (flow pattern of the resin with respect to the thickness of a gate, and the length before and behind a gate) of the injection molding using the gate whose width | variety corresponds to the full length of the longitudinal direction edge part of a cavity. It is a longitudinal cross-sectional view of the headlamp for motor vehicles which assembled | attached the front cover manufactured using the injection molding apparatus shown in FIG.

Explanation of symbols

12 resin front cover 12a front cover lower surface thickness area in front cover design surface area 12b front cover upper surface thickness area in front view t thickness of front cover C cavity 91a sprue portion 95 runner 96 wide gate 100 , 200 Die W Gate width T Gate thickness L, Ld Length of front and rear of gate d Distance from sprue part

Claims (3)

A runner is disposed along a side edge in the longitudinal direction of a cavity for molding a front cover made of resin that is horizontally long when viewed from the front, which is a lamp component provided in a mold, and is provided between the side surface of the runner and the side edge of the cavity. A front cover of a vehicular lamp formed by injecting molten resin into a cavity from a gate,
The gate is formed to be wide and uniform in width along the direction in which the runner is disposed on both sides of the gate from substantially the center in the longitudinal direction of the cavity, and the thickness T is 1.0 to 1.5 mm. The front and rear length L is configured in the range of 1.5 to 3 mm, and the flow of the molten resin injected from the gate is rectified perpendicular to the gate width direction in the entire gate width and filled into the cavity. A front cover of a vehicular lamp characterized by   2. The vehicular lamp according to claim 1, wherein the front-rear length of the gate is configured to be shorter from the vicinity of the resin supply path communicating with the runner toward the end in the gate width direction. Front cover. The front cover has a design surface region extending rearwardly and is formed so that the upper side in the front view is thinner (the lower side is thicker), and the lower side in the front view is the side facing the gate of the cavity. The front cover of the vehicular lamp according to claim 1 or 2, wherein the front cover is molded.

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