The present application claims foreign priority based on Japanese Patent Application No. P.2004-185466, filed on Jun. 23, 2004, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing vehicle lamps, and more particularly to a technique for ensuring a connection between a lens and a housing.
2. Related Art
In manufacturing vehicle lamps such as automotive lamps, a process is necessary for attaching a lens to a housing in such a manner as to cover a front side opening of the housing.
There is one method, when attaching a lens to a housing, in which sealing legs are provided at a circumferential edge portion of the lens in such a manner as to protrude therefrom, grooves for receiving the sealing legs are formed in the housing, and the sealing legs on the lens are received in the grooves in the housing via a sealing material or adhesive material. In the attaching method, however, since the sealing legs and the grooves are provided at portions which protrude from the circumferential edge portions of the lens and the housing, portions are produced around the circumferential edge portions thereof which do not transmit light or which look dark, when the lens is viewed from the front, leading to a problem that the light emitting area becomes small for its total size.
Then, there was devised a method for directly joining sealing legs of a lens to a joining surface of a housing. When the sealing legs of the lens are attempted to be joined directly to the housing, there needs a joining margin of only a small width, and hence, the portions around the circumferential edge portion of the lens which look dark can be reduced to an extremely narrow width. Then, there have been generally used hot plate welding, vibration welding and the like as the direct joining method.
In these methods, while the joining portions between the lens and the housing are joined together by being cooled to set in such a state that portions of the lens and the housing where the materials thereof are fused are mixed with each other, the redundant fused materials are pushed aside from the joined locations. This triggers a problem that when these materials are seen through the lens from the front, the external appearance of the lamp is damaged. In addition, since there is imposed a limitation on shapes of lamps (such as limitation on the inclination angle; in the vibration welding, the joining portions need to be flat relative to the direction in which vibrations are generated, and in the hot plate welding, the joining portions cannot be inclined extremely relative to the direction in which the hot plate is brought into press contact with the lens), these methods cannot deal with the currently adopted three-dimensional designs.
In addition, there is a method for joining a lens and a housing together using laser-beam welding. In the laser-beam welding, the fusing state of the materials or irradiation energy at a joining portion can be controlled to be constant by controlling the output of a laser beam, the diameter of a laser beam spot at the joining portion, and the scanning speed. Thus, it is possible to avoid the protrusion of the fused materials due to excessive fusion or joining failure due to fusion failure.
Incidentally, in the laser-beam welding, in the event that a welding portion of a lens and a welding portion of a housing are not in contact with each other in an ensured fashion, a joining failure occurs. Many automotive lamps are large in size, and hence, it becomes difficult to ensure that the welding portions (joining portions), which have a width of on the order of 2 to 5 mm, of the lens and the housing are kept in contact with each other only by placing the lens on the housing.
To cope with this, it is considered that the lens is pressed against the housing using a press holding jig. However, when attempting to press against a portion on the welding portion of the lens with the press holding jig, the press holding jig disturbs the irradiation of the welding portion, and a laser beam cannot be emitted through the lens. However, even in the event that a portion of the lens other than the circumferential edge portion thereof (the portion on the welding portion) is pressed against to avoid the disturbance by the press holding jig, since there exists a space between the portion of the lens excluding the circumferential edge portion thereof and the housing, the pressing of the other portion of the lens than the circumferential edge portion thereof results in an unbalanced application of stress to the entirety of the circumferential edge portion. This may positively trigger a risk that the welding portion of the lens and the welding portion of the housing fail to be kept in contact with each other partially along the full circumference of the circumferential edge portion.
Accordingly, it is considered that a material which can transmit a laser beam is used for the press holding jig so that a laser beam is emitted through the press holding jig. While it was described before that the fusion state of the materials could be controlled by controlling the output of the laser beam, the diameter of the laser beam spot, and the scanning of the laser beam, the spot diameter of the laser beam at the joining portion changes depending on a distance through which the laser beam is transmitted due to the refraction index of the press holding jig. Thus, it is difficult to control the spot diameter to be constant. In particular, it almost never happens with vehicle lamps that the lens exists on the same plane over the full circumference thereof, and on the contrary, the lens typically has a concave surface and/or a convex surface. In such cases, it becomes extremely difficult to maintain constant the irradiation energy at the joining surfaces.
In accordance with one or more embodiments of the present invention, a vehicle lamp manufacturing method comprises the steps of bringing a lens, around a full circumference of which a laser beam transmitting portion and a welding portion are formed, into abutment with a housing, around a full circumference of which a welding portion is formed, at the welding portions pressing the lens with a press holding jig having a laser beam transmitting portion to bring the welding portion of the lens into abutment with the welding portion of the housing, and emitting a laser beam to a location where the welding portion of the lens is in abutment with the welding portion of the housing while the laser beam so emitted is made to be transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens at at least part of the location, wherein in a segment where the part of the location continues where the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens, a sum of the thickness of the laser beam transmitting portion of the press holding jig and the thickness of the laser beam transmitting portion of the lens remains substantially constant in a direction in which the laser beam is scanned.
In addition, in accordance with one or more embodiments of the present invention, a vehicle lamp manufacturing apparatus comprises a press holding jig for bringing a lens, around a full circumference of which a laser beam transmitting portion and a welding portion are formed, into abutment with a housing, around a full circumference of which a welding portion is formed, at the welding portions, wherein, when emitting a laser beam to a location where the welding portion of the lens is in abutment with the welding portion of the housing, the press holding jig allows the laser beam so emitted to be transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens at at least part of the location; and wherein in a segment where the part of the location continues where the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens, a sum of the thickness of the laser beam transmitting portion of the press holding jig and the thickness of the laser beam transmitting portion of the lens becomes substantially constant in a direction in which the laser beam is scanned.
Consequently, in one or more embodiments, in the segment where the part of the location continues where the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens, the distance over which the laser beam transmits through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens becomes substantially constant in a direction in which the laser beam is scanned.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
1: vehicle lamp; 2: housing; 3: lens; 8: welding surface (welding portion) ; 9: laser beam transmitting portion; 10: welding surface (welding portion); 11: press holding jig; 12: surface abutment portion; 13: front surface; 14: positioning protruding edge (positioning portion); 16: laser beam transmitting portion; 18: laser beam; T9: thickness of the laser beam transmitting portion of the lens; T16: thickness of the laser beam transmitting portion of the press holding jig; tT: sum of the thickness of the laser beam transmitting portion of the lens and the thickness of the laser beam transmitting portion of the press holding jig.
Next, embodiments of the invention will be described with reference to the accompanying drawings.
Referring to
The housing 2 and the lens 3 are integrated into a single structure by virtue of laser-beam welding. Namely, as viewed from the front (referring to
A welding surface 8, which is made to be substantially a horizontal surface, is formed on a lower surface of a circumferential edge portion of the lens 3 excluding the lower edge portion thereof. A portion 9 of the lens circumferential edge portion which is situated above the welding surface 8 is made to be a laser beam transmitting portion. A portion of the front-end edge of the housing 2 which faces the welding surface 8 of the lens 2 is made to be substantially a horizontal surface. The surface 10 is made to constitute a welding surface (referring to
The housing 2 and the lens 3 are joined together by virtue of laser-beam welding in such a state that the welding surfaces 6 and 7 and the welding surfaces 8 and 10 are, respectively, brought into contact with each other.
When laser-beamwelding the housing 2 and the lens 3 together around the circumferential edge portions thereof, the lens 3 is pressed towards the housing 2 by means of a press holding jig 11 so as to ensure that the welding surfaces 6, 8 are brought into abutment with the welding surfaces 7, 10 of the housing 2, respectively.
The press holding jig 11 is formed into something like a thick plate-in such a size that can cover the entirety of a front side of the lens 3. A lower surface 12 of the press holding jig 11 is made as a surface abutment portion, and this surface abutment portion 12 is designed to be brought into abutment with the whole surface of a front surface 13 of the lens 3. Thus, since the surface abutment portion 12 of the press holding jig 11 is brought into abutment with the whole of the front surface 13 of the lens 3, even in the event that a warp or deflection occurs on the front surface portion of the lens 3 during molding, the warp or deflection can be eliminated, whereby it can be ensured that the whole of the welding surfaces 6, 8 of the lens 3 are brought into abutment with the welding surfaces 7, 10 of the housing 2.
In addition, a positioning protruding edge 14, which protrudes downwards, is provided on a lower surface of the press holding jig 11 in such a manner as to extend along a full circumference of a circumferential edge portion thereof, and the positioning protruding edge 14 is brought into abutment with the circumferential edge portion of the lens 3 from the outside, whereby the lens 3 is positioned relative to the press holding jig 11. Consequently, in the event that the housing 2 is disposed in such a state that the housing 2 is positioned relative to the press holding jig 11, the lens 3 is positioned relative to the housing 2, whereby it is ensured that the welding surface 6 of the lens 3 is brought into abutment with the welding surface 7 of the housing 2 and that the welding surface 8 of the lens 3 is brought into abutment with the welding surface 10 of the housing 2. Note that, in one or more embodiments, the housing 2 is placed on a table 15 which has been positioned relative to the press holding jig 11 to thereby position housing 2 relative to the press holding jig 11.
A circumferential edge portion 16 of the press holding jig 11 which excludes a lower edge portion thereof is made to be a laser beam transmitting portion. Namely, the circumferential edge portion 16 is made into a portion which is transparent and which transmits a laser beam. In one or more embodiments, the press holding jig 11 may be formed transparent only at the laser beam transmitting portion 16, however, in one or more embodiments, the whole of the press holding jig 11 may be formed of a transparent material.
As has been described above, after the housing 2, the lens 3 and the press holding jig 11 all have been set, a laser beam is emitted to the welding surfaces 6, 7, 8, 10 to perform laser-beam welding.
In one or more embodiments, the laser-beam welding of the welding surface 8 of the lens 3 with the welding surface 10 of the housing 2 is performed by scanning a laser beam as indicated by an arrow A shown in
When laser-beam welding the welding surface 10 of the housing 2 and the welding surface 8 of the lens 3 together, in one or more embodiments, a sum tT of the thickness T16 of the laser beam transmitting portion 16 of the press holding jig 11 and the thickness T9 of the laser beam transmitting portion 9 of the lens 3 (=T16+T9) is preferably substantially constant throughout a whole area in a direction A in which the laser beam is scanned. This is because since the diameter of the laser beam 18 is controlled such that the laser beam 18 starts and continues to be contracted from the state where the beam is emitted from the laser head 17 until it produces the predetermined spot diameter on the welding surface 10 of the housing 2, in the event that the distance over which the laser beam transmits through the two laser beam transmitting portions 16, 9 changes, the spot diameter at the welding surface 10 also changes, resulting in a change in irradiation energy from the laser beam 18 received by the welding surface 10, whereby the fusing conditions becomes uneven. Due to this, in the event that the sum tT remains even throughout the whole area in the scanning direction A, there is provided an advantage that the teaching of a robot is facilitated. However, it is not vital that the tT be constant throughout the whole area in the scanning direction, and in the event that the tT can be even at at least a segment of the whole area, the robot teaching for that specific segment can be facilitated.
It is preferable from the above-mentioned fact that, in one or more embodiments, the refraction index of the laser beam transmitting portion 9 of the lens 3 is approximate to that of the laser beam transmitting portion 16 of the press holding jig 11. For example, in the event that the lens is made of acrylic resin, it is preferable that the laser beam transmitting portion 16 of the press holding jig 11 is formed of acrylic resin or a material having a refraction index approximate to that of the acrylic resin.
On the contrary, hypothetically speaking, if the thickness of the laser beam transmitting portion 16 and the thickness of the laser beam transmitting portion 9 are different in the laser beam scanning direction A, while the sum tT of the thicknesses of the two laser beam transmitting portions 16, 9 is the same in the laser beam scanning direction A, and if the refraction indices of both the laser beam transmitting portions 16, 9 are different, the spot diameter on the welding surface 10 becomes different in the scanning direction A. Thus, the irradiation energy resulting on the welding surface 10 needs to be controlled to become uniform in the laser beam scanning direction A by adjusting the irradiation energy of the laser beam 18, the scanning speed thereof and the like. As a result, the needed control have to become complex.
Next, the laser welding of the welding surface 6 of the lens 3 and the welding surface 7 of the lens 2 together is carried out, as shown in
The circumferential edge portion of the lens 3 is joined to the circumferential edge portion of the opening in the housing 2 in such a manner as has been described above.
One or more embodiments of the present invention may include one or more following advantages.
When applied to joining together a housing and a lens of a vehicle lamp, in particular, a large vehicle lamp, one or more embodiments of the present invention can ensure the required joining of the components without damaging the external appearance of the vehicle lamp.
The vehicle lamp manufacturing method according to one or more embodiments of the present invention for fixing a lens to a housing that is opened in a front side thereof via laser-beam welding in such a manner as to cover the front side opening, includes the steps of bringing a lens, around a full circumference of which a laser beam transmitting portion and a welding portion are formed, into abutment with a housing, around a full circumference of which a welding portion is formed, at the welding portions, pressing the lens with a press holding jig having a laser beam transmitting portion to bring the welding portion of the lens into abutment with the welding portion of the housing, and emitting a laser beam to a location where the welding portion of the lens is in abutment with the welding portion of the housing while the laser beam so emitted is made to be transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens at at least part of the location, wherein in a segment where the part of the location continues where the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens, a sum of the thickness of the laser beam transmitting portion of the press holding jig and the thickness of the laser beam transmitting portion of the lens remains substantially constant in a direction in which the laser beam is scanned.
In addition, in one or more embodiments of the present invention, the vehicle lamp manufacturing apparatus for fixing a lens to a housing made to open in a front side thereof via laser-beam welding in such a manner as to cover the front side opening, comprises a press holding jig for bringing a lens, around a full circumference of which a laser beam transmitting portion and a welding portion are formed, into abutment with a housing, around a full circumference of which a welding portion is formed, at the welding portions, wherein, when emitting a laser beam to a location where the welding portion of the lens is in abutment with the welding portion of the housing, the press holding jig allows the laser beam so emitted to be transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens at at least part of the location, and wherein in a segment where the part of the location continues where the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens, a sum of the thickness of the laser beam transmitting portion of the press holding jig and the thickness of the laser beam transmitting portion of the lens becomes substantially constant in a direction in which the laser beam is scanned.
Consequently, in one or more embodiments of the present invention, in the segment where the part of the location continues where the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens, the distance at which the laser beam is transmitted through the laser beam transmitting portion of the press holding jig and the laser beam transmitting portion of the lens becomes substantially constant in a direction in which the laser beam is scanned. Due to this, in the event that the output and scanning speed of the laser beam are constant, the diameter of the spot at the joining portion between the lens and the housing becomes constant. Namely, the irradiation energy at the joining portion between the lens and the housing becomes constant. Consequently, the control is facilitated of the irradiation energy at the joining portion between the lens and the housing, whereby a laser-beam welding with good quality can be implemented. In addition, the teaching of a robot is also facilitated when attempting to perform the laser beam emitting process using the robot.
According to one or more embodiments of the present invention, since the lens is pressed towards the housing, so that the welding portion of the lens is brought into abutment with the welding portion of the housing in such a state that a surface contact portion of the press holding jig is brought into surface contact with substantially the whole of a lens surface, which is curved, the welding portion of the lens and the welding portion of the housing are brought into abutment with each other in an ensured fashion.
According to one or more embodiments of the present invention, since the welding portion of the lens is brought into abutment with the welding portion of the housing in such a state that a circumferential edge portion of the lens is positioned by a positioning portion formed around a full circumference of a circumferential edge portion of the press holding jig, there occurs no positional deviation between the welding portion of the lens and the welding portion of the housing, so that the welding portions of these components are brought into abutment with each other in an ensured manner.
According to one or more embodiments of the present invention, since the press holding jig is formed of a material having an approximate refraction index to that of a material for the lens, even when the thickness of the laser beam transmitting portion of the press holding jig and the thickness of the laser beam transmitting portion of the lens changes relatively, in the event that the sum of the thicknesses of the two components is substantially the same, the spot of the laser beam at the joining portion between the lens and the housing becomes substantially the same. Therefore, the control of irradiation energy at the joining portion between the lens and the housing can be facilitated.
It will be apparent to those skilled in the art that various modifications and variations can be made to the described preferred embodiments of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover all modifications and variations of this invention consistent with the scope of the appended claims and their equivalents.
Number | Date | Country | Kind |
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JP2004-185466 | Jun 2004 | JP | national |