JP2015185375A - Vehicle lighting - Google Patents

Abstract

A welded portion welded by laser welding is viewed through a light non-absorbing resin member and gives a feeling of strangeness in appearance due to color difference. Providing products for vehicles with a reduced appearance.
A welding portion is irradiated with a laser beam at high speed through a glass pressing plate that transmits the laser beam. The contact surface (welded portion) of the lamp housing is repeatedly irradiated from the laser head using the galvano scanner to the contact surface where the light absorbing resin member and the light transmitting rib are overlapped, through the rib of the outer cover. Carbon black is added to the light transmissive member. When the contact surface is heated using laser light, a part of the carbon black is simultaneously absorbed and the entire rib is heated and slightly softened. After welding, laser irradiation is stopped and cooling is performed. When the heated rib of the outer cover is cooled, a recess is formed on the outer cover surface, making the welded portion inconspicuous.
[Selection] Figure 3

Description

  The present invention relates to a vehicular lamp provided with a colored outer cover that transmits visible light, and more particularly to a vehicular lamp that uses a laser to weld a thermoplastic resin lamp housing and an outer cover.

  In recent years, it has been widely practiced to weld resin products together using laser light. For example, as disclosed in Patent Document 1, laser welding is performed by irradiating laser light in a state where a light-absorbing resin member and a non-absorbing resin member are in contact with each other. Is the method. Patent Document 2 discloses a welding method using laser light for welding an outer cover made of a light non-absorbing resin member and a lamp housing made of a light absorbing resin member of a vehicle lamp.

JP-A-60-214931 JP 2004-349123 A

  However, in the welding method using laser light in Patent Document 1 and the welding method in Patent Document 2, laser light is irradiated to the light-absorbing resin member through the light non-absorbing resin member. Can be easily seen from the outside. Therefore, in a design product visually recognized from the outside, such as a vehicular lamp, there is a problem that the welded part is viewed through a non-light-absorbing resin member, and a discomfort on the appearance due to a difference in color may be felt. There is.

  An object of the present invention is to solve the above-mentioned problems and to provide a laser-welded vehicular lamp whose appearance is a smoke-like design surface. It is another object of the present invention to provide a vehicular lamp that makes it difficult to visually recognize a laser welded portion and reduces a sense of discomfort.

  In order to achieve the above object, the present invention comprises a thermoplastic resin member that absorbs laser light, and can accommodate a light source inside the lamp housing, and covers the lamp housing. This is a vehicular lamp in which an outer cover made of a light-transmitting thermoplastic resin member is joined and integrated by laser welding.

Further, a welding region between the lamp housing and the outer cover is located at least along the periphery of the outer cover,
In the welding area, the back surface of the outer cover located on the front side of the vehicular lamp and the lamp housing located on the rear side of the vehicular lamp are in contact with each other, and laser welding is performed.
The outer cover of the welded portion has a light-transmitting smoke tone to which a laser light absorbing pigment is added,
The outer cover surface corresponding to the welded portion is formed with a welded portion visual inhibition portion,
The welded portion visual inhibition portion is a recess formed by irradiating a laser beam for performing the laser welding.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle lamp using the outer cover which made the external appearance the smoke-like design surface can be manufactured by laser welding. Further, since the laser welded portion is visually recognized through the recessed portion formed on the surface of the smoke-like outer cover, it is difficult to visually recognize the laser welded portion due to the reduction in transmittance and the concave lens effect, and the uncomfortable feeling can be reduced.

When the vehicular lamp of the present invention is provided, for example, at the rear corner of a four-wheeled vehicle, the direction of the reflected light from the headlight of the following vehicle forms the contour of the vehicular lamp on the outer cover surface. The direction of the reflected light can be changed by the recessed portion. Thereby, a recessed part is visually recognized as the outline of a vehicle lamp with respect to the driver | operator of a following vehicle, etc., and it can improve visibility.

FIG. 1 is a perspective view and a sectional view showing a vehicular lamp using a fixing method according to an embodiment of the present invention. (A) is a perspective view, (b) shows sectional drawing along the AA line. FIG. 2 is a perspective view schematically illustrating a welding method performed using a laser irradiation apparatus. FIGS. 3A and 3B are enlarged cross-sectional views showing the main part, in which FIG. 3A shows a state before irradiation with laser light, and FIG. 3B shows a state after welding by irradiation with laser light. FIG. 4 is a cross-sectional view schematically illustrating a process of repeatedly irradiating laser light using a laser irradiation apparatus. FIG. 5 is a diagram schematically showing a configuration of a laser irradiation apparatus using a galvano scanner. FIG. 6 is a graph schematically showing a temporal change in temperature at the laser irradiation position. FIG. 7 is a schematic top view for explaining the operation in a state in which the vehicular lamp of the present invention is attached to the vehicle body.

  Hereinafter, a vehicular lamp according to an embodiment of the present invention will be described with reference to the drawings, taking a tail lamp provided at the rear of the vehicle as an example.

  1A and 1B are a perspective view and a cross-sectional view showing a vehicular lamp 25 using a fixing method according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. The tail lamp 25 for a vehicle has a shape suitable for a vehicle to which the tail lamp is attached by a lamp housing 21 made of a thermoplastic resin material formed in a substantially box shape and an outer cover 22 that covers the box-shaped opening of the lamp housing 21. It is formed. In the lamp chamber surrounded by the lamp housing 21 and the outer cover 22, an LED light source (not shown) and its wiring are attached as a light source for the tail lamp. As shown in FIG. 2, the lamp housing 21 and the outer cover 22 are heat-welded by the laser beam 12 emitted from the laser irradiation device 10. FIG. 2 is a perspective view schematically illustrating a welding method performed using a laser irradiation apparatus.

  The lamp housing 21 is formed of a black thermoplastic resin, and the outer cover 22 is formed of a transparent PMMA resin (polymethyl methacrylate resin, acrylic resin) that is a thermoplastic resin. As the resin material of the lamp housing 21, a material excellent in weldability with the material resin of the outer cover 22 is used.

  The outer cover 22 is integrated with the lamp housing 21 by laser welding at an annular welding portion 26 along the edge of the outer cover. FIG. 3 is an enlarged cross-sectional view of the welded portion 26. Note that (a) shows a state before irradiation with laser light, and (b) shows a state after welding by irradiation with laser light. The outer cover 22 is formed with ribs 23 that project in a wall shape toward the lamp housing 21 side. The rib 23 has a T-shaped cross-sectional shape and is formed over the entire circumference along the outer cover edge. The lamp housing 21 is formed with a welding surface 24 that is in surface contact with the tip 231 of the rib 23. The welding surface 24 is a plate thickness surface of the end surface of the peripheral edge of the lamp housing 21. The shape of the welded surface 24 is not limited to the rectangular parallelepiped shape shown in FIG. 3, but may be a flange shape, a U-shaped concave bottom surface, or the like that can form the welded portion 26 in contact with the rib tip 231. However, it is not limited to these shapes.

As shown in FIG. 3A, the welding surface 24 is irradiated with the laser beam 12 through the outer cover 22 in a state where the rib tip 231 and the welding surface 24 are in contact with each other. At this time, a laser light absorbing pigment 27 is added to the outer cover 22 through which the laser light 12 passes. The laser light absorbing pigment 27 is added with carbon black at a concentration that absorbs part of the irradiated laser beam 12, specifically, a concentration of less than 10 wt%. By adding several percent of carbon black, the outer cover 22 can be made a smoke-colored transmissive material. The laser light 12 is irradiated and the laser light reaches the welding surface 24, the welding surface 24 of the outer cover 22 is heated and melted, and the rib tip 231 and the welding surface 24 are welded. When the irradiation of the laser beam 12 is stopped after welding, the temperature of the outer cover 22 through which the laser beam 12 has passed is reduced by the laser beam 12 that has absorbed and heated the conduction heat from the welding surface 24 and the laser beam 12. At this time, the region where the laser beam passes and the vicinity thereof are cooled on the surface that has been heated and softened, and as shown in FIG. A depression 28 is created. The size of the recess 28 can be controlled by appropriately adjusting the laser light irradiation area, the irradiation conditions, the concentration of the laser light absorbing pigment added, the thickness of the outer cover 22, and the like.

  Hereinafter, the laser welding process will be described in order with reference to FIGS.

(Step 1)
First, a lamp housing 21 and an outer cover 22 molded into a predetermined shape are prepared. The lamp housing 21 has a substantially box-like container shape formed of a coloring material that absorbs laser light. The outer cover 22 is a transparent member that is transparent to laser light and has a three-dimensional curved surface formed of PMMA resin (see FIG. 1). A laser light absorbing pigment 27 is added to the outer cover 22. As shown in FIG. 4, the lamp housing 21 is fixed to the work table 31. In FIG. 4, for easy understanding of the drawing, the shape of the vehicular lamp 25 is shown in a simplified plan shape, and only the vicinity of the rib 23 that becomes the joint portion 26 is schematically enlarged and illustrated. . The outer cover 22 is overlapped and set at a predetermined position so as to face the lamp housing 21.

  A pressing plate 32 made of a translucent material, for example, glass is positioned above the work table 31 so as to face the lamp housing 21 on which the outer cover 22 is stacked. The pressing plate 32 is provided at a predetermined distance from the laser head. The pressure device 33 is connected so that the distance between the pressing plate 32 and the work table 31 can be shortened and extended. In this embodiment, the work table 31 is attached to the pressing plate 32 by a movable arm (not shown). Move towards. Since the pressing plate 32 is made of a material that transmits the laser beam 12, the laser beam 12 can be irradiated to the lamp housing 21 through the pressing plate 32.

(Step 2)
Next, as shown in FIG. 4, the outer cover 22 is pressed against the pressing plate 32 by using the pressing device 33 against the lamp housing 21 on which the outer cover 22 on the work table 31 prepared in Step 1 is overlapped. The force for applying pressure so as to reduce the distance between the pressing plate 32 and the work table 31 is continuously applied during the heating process using the next laser irradiation device. Instead of moving the work table 31 to the pressing plate 32 and pressurizing it, the pressing plate 32 may be moved to the working table 31 side.

(Step 3)
Next, as shown in FIGS. 2 and 4, the laser beam 12 is repeatedly irradiated using the laser irradiation apparatus 10. As shown in FIG. 4, the laser beam 12 is irradiated toward the tip of the rib 23 through the pressing plate 32 and the outer cover 22. The repeated irradiation of the laser beam 12 will be described in detail later, but the laser beam 12 is repeatedly irradiated so as to circulate around the outer cover 22 as shown in FIG. The temperature of the ribs 23 and the welded surface 24 can be gradually raised each time irradiation is performed repeatedly, and the whole can be heated and softened almost simultaneously. Note that, when heating by repeated irradiation of the laser beam 12 is performed, pressurization using the pressurizer 33 is performed. The laser beam 12 is emitted through the transparent pressing plate 32 and the outer cover 22 and mainly through the tip 231 of the rib 23. The laser beam 12 emitted from the rib 23 reaches the welding surface 24 made of black resin and is absorbed.

(Step 4)
In step 3, heating and pressurization of the welding surface 24 through the rib 23 by the laser beam 12 are performed simultaneously. Softening starts when the temperature of the welding surface 24 exceeds the softening temperature of the thermoplastic resin material. The laser beam irradiated on the welding surface 24 through the rib tip 231 heats and softens the welding surface 24. At this time, since pressure is applied to the contact surface between the welding surface 24 and the rib tip 231, the softened welding surface 24 is pushed by the rib tip 231, and a gap is generated between the rib tip 231 and the welding surface 24. Even if it moves, it moves so that the gap disappears. When this state is reached, heating of the laser beam is stopped and cooling is performed. After cooling, the rib 23 and the welding surface 24 are welded together to form a welded portion 26. Therefore, the lamp housing 21 and the outer cover 22 are permanently fixed.

  During this cooling, a recess 28 is formed on the side of the design surface opposite to the side on which the rib 23 of the outer cover 22 is provided. The recess 28 is a recess and is generated along with the volume shrinkage of the rib 23, and thus is formed over the entire week of the outer cover 22 in the same manner as the rib 23. The recess 28 is a recess recessed on the rib 23 side. Thereby, when the tail lamp 25 is viewed from the design surface side, that is, the outer cover 22 surface side, a refractive surface is formed. Since the recess 28, which is a concave refracting surface, is formed on the surface of the outer cover 22 opposite to the rib 23, the welded portion 26 is difficult to view. In particular, when a black material is used for the lamp housing 21, the weld surface 24, which is a black material, becomes the weld portion 26. Therefore, the weld surface 24 observed through the rib 23 has a high contrast and is conspicuous. 26 can be made inconspicuous. That is, the recess 28 becomes a welded portion visual inhibition portion.

  Next, laser irradiation apparatus 10 and repeated irradiation of laser beam 21 using laser irradiation apparatus 10 will be described.

(Laser irradiation device 10)
FIG. 5 is a diagram schematically showing the configuration of the laser irradiation apparatus 10 using a galvano scanner. A focus adjustment optical system 13 is arranged for laser light emitted from the tip of an optical fiber 17 connected to a laser oscillator 18 included in the control device 16. The focus adjustment optical system includes a movable lens and can adjust the focus position on the optical path. A first galvano mirror 14 is arranged for the laser beam emitted from the focus adjustment optical system 13 and performs, for example, x-direction scanning within the irradiated surface. A second galvano mirror 15 is arranged with respect to the laser beam reflected by the first galvano mirror 14 and, for example, scans in the y direction within the irradiated surface.

  The control device 16 controls the laser oscillator 18, the galvano mirrors 14 and 15, and the focus adjustment optical system 13. The emitted laser light can be two-dimensionally scanned in the xy plane by the galvano mirrors 14 and 15, and can be moved in the z direction by controlling the focal length by adjusting the focus adjusting optical system 13. That is, the focusing position of the laser beam can be scanned three-dimensionally. Galvanomira is lightweight and can be scanned at high speed. The laser head 11 incorporates a focus adjustment optical system 13 and galvano mirrors 14 and 15, and the laser head 11 can also be made small and light.

  As the laser oscillator 18, for example, a YAG second to third harmonic laser oscillator, a semiconductor laser, a fiber laser, or the like can be used. If only two-dimensional scanning is used, a scan head having an fθ lens can be used instead of the focus adjustment optical system.

  The laser head 11 is installed above the work table 31 and the pressing plate 32 as shown in FIG. The laser head 11 uses a galvano scanner using a plurality of galvano mirrors as described above, and can be reduced in size and weight, so that the entire fixing device using the laser irradiation device 10 can be reduced in size.

  The laser beam 21 can be scanned at high speed while three-dimensionally scanning the laser beam 21 from the laser irradiation device 10 using a galvano scanner toward the welding surface 24 of the lamp housing 21 formed of a light absorbing resin. At this time, the lamp housing 21 is irradiated through the translucent pressing plate 32 and the outer cover 22. The scanning in this specification includes not only scanning that changes the irradiation direction while performing continuous irradiation, but also scanning that changes the irradiation direction while performing intermittent irradiation.

  FIG. 6 is a graph schematically showing a temporal change in temperature at the laser irradiation position. The temperature rises with respect to one laser beam irradiation, and starts decreasing after the end of irradiation. Before the temperature is lowered to the temperature before irradiation, the next laser beam is irradiated and the temperature rises. The average temperature gradually rises due to repeated laser beam irradiation. Laser beam irradiation is performed while sequentially scanning a plurality of ribs 23 extending around the outer cover 22. It is obvious that by performing irradiation of one unit by a plurality of units, the entire plurality of projections irradiated by one unit can be heated almost uniformly and almost simultaneously. Note that in this specification, “1 unit” is described as one unit in which laser irradiation performed by sequential scanning is performed once, and two units in which laser irradiation is performed twice.

  Laser irradiation is performed through an annular rib 23 formed around the outer cover 22. The irradiation area of the laser beam 12 is moved at high speed using a galvano scanner so as to make one round of the annular bonding area. One week corresponds to one unit described above. The joint area of the vehicular lamp 25, that is, the position of the surface where the tip 231 of the rib 23 and the recess bottom surface 241 are in contact with each other does not lie on a two-dimensional plane but forms a three-dimensional structure. Therefore, laser irradiation is performed by controlling the x direction, y direction, and z direction with respect to the position of the laser head 11. Specifically, in the configuration of FIG. 5, the first galvano mirror 14 performs scanning in the x direction, and the second galvano mirror 15 performs scanning in the y direction. The focus adjustment optical system 13 controls the focal length and moves the focus position in the z direction.

  In the first scanning time, the temperature is raised in a short time during which the laser beam irradiation is performed as shown in FIG. The temperature starts to decrease after the irradiation of the laser beam to the target protrusion in the first scanning until the second laser beam irradiation is performed. Repeated irradiation is performed before the start of irradiation by the next scanning is lowered to the temperature at the time of the previous scanning start. Thereby, the welding surface 24 is gradually heated by the repeated irradiation of the laser light, reaches a temperature sufficiently higher than the softening temperature, and becomes deformable. It is cured when the laser beam irradiation is stopped.

  As described above, according to the vehicular lamp of the present embodiment, the welded portion 26 and the recess 28 can be formed simultaneously by irradiation with laser light. When a tensile test was performed in order to confirm the strength of the welded portion 26, bonding was performed with a strong bonding strength that became a material fracture mode rather than interface peeling.

  As described above, the recess 28 serves as a welded portion viewing inhibition portion. Also, it acts as an accent line for the tail lamp 25. For example, as shown in FIG. 7, consider a case where a driver 42 of a succeeding vehicle 40 located at the rear views a vehicle with the tail lamp 25 attached to the vehicle body B. When the tail lamp 25 is irradiated by the head lamp 41 of the following vehicle 40, the tail lamp 25 is reflected on the surface of the outer cover 22, and the driver 42 of the following vehicle 40 recognizes the tail lamp 25 as a whole (see the light beam L1 and the light beam L2). At this time, the light beam L3 that irradiates the concave surface of the recess 28 becomes diffused light beams L4 and L4 on the concave surface. Therefore, the direction of the reflected light of the reflected light beam L4 in the recess 28 is made different from that of the reflected light beam L2 on the other design surface, that is, the main surface of the outer cover 22. Therefore, it functions as an annular accent line located around the tail lamp 25. The accent line can enhance the design of the tail lamp 25.

  The above embodiment is merely an example in all respects. For example, although the outer cover 22 is a transparent material to which a laser light absorbing pigment is added, a red light transmitting resin material to which a laser light absorbing pigment is added may be used. Further, the rib 23 is also described as having a wall shape with a high height. However, a thick portion having a thicker plate than the surrounding portion is also included in the rib in this specification. The lamp housing 22 is also a black thermoplastic resin, but may be a light absorbing material of another color. The present invention is not construed as being limited to the specific examples of the embodiments described above.

In the above-described embodiment, the thermoplastic resin member has been described with respect to the tail lamp as an example of the present invention. However, other vehicle lamps may be used, and the present invention is not limited to vehicle lamps, and other general lighting and outdoor lighting. It can be used for various electronic devices and various cases.

DESCRIPTION OF SYMBOLS 10 Laser irradiation apparatus 11 Laser head 12 Laser beam 13 Focusing optical system 14 1st galvanometer 15 2nd galvanometer 16 Control apparatus 17 Optical fiber 18 Laser oscillator 21 Lamp housing 22 Outer cover 23 Rib 231 Rib tip 24 Welding surface 25 For vehicles Lamp (tail lamp)
26 Welding Section 27 Laser Absorbing Pigment 28 Dimple 31 Mounting Table (Work Table)
32 Pressing plate 33 Pressurizing device P Pressure 40 Subsequent vehicle 41 Subsequent vehicle headlight 42 Subsequent vehicle driver

Claims (1)

A lamp housing made of a thermoplastic resin that absorbs laser light, and an outer housing made of a thermoplastic resin member that covers the lamp housing and is transparent to the laser light. The cover is a vehicle lamp united and integrated by laser welding,
A welding region between the lamp housing and the outer cover is located along at least the periphery of the outer cover;
In the welding area, the back surface of the outer cover located on the front side of the vehicular lamp and the lamp housing located on the rear side of the vehicular lamp are in contact with each other, and laser welding is performed.
The outer cover of the welded portion has a light-transmitting smoke tone to which a laser light absorbing pigment is added,
The outer cover surface corresponding to the welded portion is formed with a welded portion visual inhibition portion,
The vehicular lamp according to claim 1, wherein the welded portion visual inhibition portion is a recessed portion formed by irradiating a laser beam for performing the laser welding.

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