Title of Invention

A MOTOR VEHICLE WHEEL AND A METHOD OF MANUFACTURING SAME

Abstract

ABSTRACT (293/MAS/97) A motor vehicle wheel and a method of manufacturing a motor vehicle wheel The present invention relates to a motor vehicle wheel comprising a joined assembly of a rim a spoke and a boss, said rim and said spoke having a joint region, and said spoke and said boss having a joint region, characterized in that each of said joint regions is laser-be am-welded by each of laser beams applied respectively in a predetermined single direction. The present invention also relates to a method of manufacturing a motor vehicle wheel.

Full Text

Field of the Invention The present invention relates to a motor vehicle wheel.made up of a plurality of parts joined together and a method of manufacturing such a motor vehicle wheel. Description of the Prior Art Heretofore, as shown in FIGS. 5 and 6 of the accompanying drawings, one conventional motor vehicle wheel comprises four parts, i.e a boss 51 through which an axle extends, a hub 52 mounted on and joined to the boss 51, a plurality of spokes 53, and a rim 54 which is connected to the hub 52 by the spokes 53. Another conventional motor vehicle wheel (not shown) comprises three parts, i.e., a boss 51, spokes 53, and a rim 54 connected to the boss 51 by the spokes 53. The conventional motor vehicle wheel which com¬prises four parts is manufactured as follows: As shown in FIG. 8 of the accompanying drawings, the outer ends of spokes 53 which have been pressed to shape are spot-welded at regions "a" (see FIG. 5) to an inner circumferential surface of a rim 54 which has been rolled to shape and then flash-butt-welded. A hub 52 which has been pressed to shape and a boss 51 which has been forged to shape and then roughly machined at its inner circumferential surface are MIG-welded at their axially opposite regions "b", "c" (see FIG. 6) . Thereafter, the inner ends of the spokes 53 and the outer circumferential surface of the hub 52 are MIG-welded at regions "d" along the full outer circumferential surface of the hub 52. Then, the boss 51 and the hub 52 are machine-finished and corrected out of imbalance to remove thermal strains which have been caused by the welding steps. The above manufacturing process is basically applied to the manufacture of a motor vehicle wheel which comprises three parts as shown in FIG. 7 of the accompanying drawings. The conventional manufacturing process is time-consuming because regions of the wheel which require a desired level of bonding strength, e.g., the regions "b", "c", have to be welded in axially opposite directions. Furthermore, since the welding steps thermally affect the parts of the wheel greatly, they have to be corrected out of imbalance to remove thermal strains after the welding steps. It is therefore an object of the present invention to provide a motor vehicle wheel which can be manufactured in a reduced period of welding time while desired tolerances are maintained, by a reduced number of manufacturing steps or simplified manufacturing steps. To achieve the above object, there is provided in accordance with the present invention a motor vehicle wheel comprising a joined assembly of a rim, a spoke, a hub and a boss, the rim and the spoke having a joint region and the spoke and the boss having a joint region characterized in that each of the joint regions is laser-beam-welded by each of laser beams applied respectively in a predetermined single direction. Since each of the joint regions is laser-beam-welded by a laser beam applied in the single direction, the time required to weld the joint regions is relatively short. The laser beam welding process produces less thermal effect in a very limited area, and hence the welded wheel does not require machine-finishing to remove thermal strains and correct imbalance. The number of steps required to manufacture the motor vehicle wheel can be reduced and the steps can be simplified because the welded joint regions achieve a desired level of mechanical strength even though each of the laser beams is applied to each of the joint regions respectively in the single direction. The joint region of the spoke and the boss is laser-beam-welded by a laser beam applied substantially parallel to an axis of the motor vehicle wheel, and the joint region of the rim and the spoke is laser-beam-welded by a laser beam applied substantially parallel or perpendicular to the axis of the motor vehicle wheel. The laser beam applied in the above direction may contribute to maintain a desired level of mechanical strength and also facilitate the. laser beam welding process. According to the present invention, there is also provided a method of manufacturing a motor vehicle wheel, comprising the steps of forming a rim, a spoke and a boss, assembling the rim, the spoke and the boss into a completed wheel shape on a setting jig,, and laser-beam-welding a joint region of the rim and the spoke and a joint region of the spoke and the boss with each of laser beams applied in a predetermined single direction. Inasmuch as the rim, the spoke, and the boss are set on the setting jig and then laser-beam-welded in the above method, it is not necessary to set them on respective dedicated jigs in different welding modes as is the case with the conventional manufacturing process . Consequently, the method is highly simplified. In the above method, the setting jig is arranged to keep the rim, the spoke and the boss fast while the joint regions thereof are being pressed together. According to the present invention, there is also provided a motor vehicle wheel comprising a joined assembly of a rim, a spoke, a hub and a Boss, the rim and the spoke having a joint region, the spoke and the hub having a joint region, and the hub and the boss having a joint region, characterized in that each of the joint regions is laser-beam-welded by each of laser beams applied in a predetermined single direction. As mentioned in conjunction with the motor vehicle wheel of three parts, the rim, the spoke, the hub and the boss are joined with a desired level of mechanical strength and welded in a relatively short time. The welded wheel does not need machine-finishing to remove thermal strains and correct imbalance. Each of the joint region of the spoke and the hub and the joint region of the hub and the boss is laser-beam-welded by a laser beam applied substantially parallel to an axis of the motor vehicle wheel, and each of the joint region of the rim and the spoke is laser-beam-welded by a laser beam applied substantially parallel or perpendicular to the axis of the motor vehicle wheel. The laser beam for welding each of the joint regions is applied in the above direction may contribute to maintain a desired level of mechanical strength and also simplify the manner in which a laser beam welding machine is handled. According to the present invention there is further provided a method of manufacturing a motor vehicle wheel, comprising the steps of forming a rim, a spoke, a hub and a boss, assembling the rim, the spoke, the hub and the boss into a completed wheel shape on a setting jig, and laser-beam-welding a joint region of the rim and the spoke, a joint region of the spoke and the hub, and a joint region, of the hub and the boss respectively with laser beams each applied in a predetermined single direction. The above-mentioned method does not require such complexity as setting each of parts on respective dedicated jigs in different welding modes. Consequently, the method is highly simplified. In the method, the setting jig is arranged to keep the rim, the spoke and the boss fast while the joint regions thereof are being pressed together. The above and further objects, details and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment thereof, when read in conjunction with the accompanying drawings. FIG. 1 is a plan view of a motor vehicle wheel which comprises four parts according to the present invention, set on a setting jig; FIG. 2 is a fragmentary vertical cross-sectional view of the motor vehicle wheel shown in FIG. 1; FIG. 3 is a flowchart of a process of manufacturing a motor vehicle wheel which comprises three parts according to the present invention; FIG. 4 is a flowchart of a process of manufacturing a motor vehicle wheel which comprises four parts according to the present invention; FIG. 5 is a plan view of a conventional motor vehicle wheel which comprises four parts, showing the manner in which the parts are welded; FIG. 6 is a fragmentary vertical cross-sectional view of the conventional motor vehicle wheel shown in FIG. 5; FIG. 7 is a flowchart of a process of manufacturing a conventional motor vehicle wheel which comprises three parts; and FIG 8 is a flowchart of a process of manufacturing the conventional motor vehicle wheel which comprises four parts. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The principles of the present invention are applied to motor vehicle wheels such as steel wheels for use as front and rear wheels of motorcycles. Usually, the front wheel of a motorcycle is made up of three parts and the rear wheel is four parts. FIGS. 1- and 2 show the four parts of the rear wheel which are set on a setting jig. An embodiment of the present invention will be described below basically with reference to FIGS. 1, 2, and 4 which show the rear wheel. The rear wheel, generally designated by the reference numeral 1 in FIGS. 1 and 2, comprises a boss 2 through which a wheel axle extends, a hub 3 having a central fitting hole a diameter of which is substantially the same as the outside diameter of the boss 2, a spoke 4 in the form of a substantially triangular plate having a central fitting hole a diameter of which is substantially the same as the outside diameter of the hub 3, and a rim 5 to which the outer circumferential surface of the spoke 4 is joined. The hub 3 is fitted over the boss 2, and the spoke 4 is fitted over the hub 3. The boss 2, the hub 3, the spoke 4, and the rim 5 are assembled into a completed wheel shape on a setting jig 6, and then welded together at their joint regions by laser beam welding. The setting jig 6 has an upwardly extending central boss rest 6a for being inserted into a hole in the boss 2, the central boss rest 6a having a circumferential step for supporting the lower surface of the boss 2. The setting jig 6 also has three hub rests 6b angularly spaced at equal angular intervals on a circle extending around and concentric with the boss rest 6a. The hub rests 6b serve to support the lower end of an outer circumferential edge of the hub 3. The setting jig 6 has three spoke rests 6c posi¬tioned radially outwardly of the respective hub rests 6b for being inserted in respective through holes 4a defined in the spoke 4 to bear a lower surface of the spoke 4. The setting jig 6 further has three rim rests 6d disposed in its radially outermost positions for bearing the lower end of the rim 5. When the boss 2, the hub 3, the spoke 4, and the rim 5 are set on the setting jig 6, .they are supported respectively on the boss rest 6a, the hub 'rests 6b, the spoke rests 6c, and the rim rests 6d and positioned such that the joint regions thereof are held in tight contact. The boss rest 6a, the hub rests 6b, the spoke rests 6c, and the rim rests 6d have respective upper ends which do not project upwardly beyond the upper ends of the boss 2, the hub 3, the spoke 4, and the rim 5 which they support. The boss 2 set on the setting jig 6 has been forged to shape and then machine-finished at its inner circumferential surface. The hub 3 and the spoke 4 set on the setting jig 6 have been pressed to shape. To form the rim 5 set on the setting jig 6, a web is rolled and then wound into a drum, with its ends joined to each other by flash butt welding. The boss 2 is not roughly machined, but is machine-finished- in its initial manufacturing stage. After the boss 2, the hub 3, the spoke 4, and the rim 5 are set on the setting jig 6, laser beams are applied thereto in a direction substantially parallel to the axis of the wheel 1 as indicated by the arrows in FIG. 2, thereby laser-beam-welding the boss 2, the hub 3, the spoke 4, and the rim 5 together. Specifically, the rib 5 and the spoke 4 are laser-beam-welded at two spots on each of the joint regions thereof. The joint regions of the spoke 4 and the hub 3, and the joint regions of the hub 3 and the boss 2 are laser-beam-welded substantially along their full circumferential surfaces. Since a desired level of mechanical strength can be achieved even if those joint regions are not laser-beam-welded along their full circumferential surfaces, they may be la¬ser-beam-welded along limited ranges of the full circumferential surfaces. In view of the spreading of weld beads and in order to avoid interference of laser beams, it is necessary to apply laser beams in a direction slightly oblique to the axis of the wheel 1. Since the upper ends of the boss rest 6a, the hub rests 6b, the spoke rests 6c, and the rim rests 6d do not project upwardly to a position which would-otherwise interfere with the laser beams, it is not necessary to pay attention to avoid interference between the setting jig 6 and the laser beams. The laser beams for welding the rim 5 and the spoke 4 to each other may be applied to spots on the outer circumferential surface of the rim 5 substantially perpendicularly to the axis of the wheel 1 as indicated by the broken-line arrows in FIG. 2. FIG. 4 shows a process of manufacturing the motor vehicle wheel 1 shown in FIGS. 1 and 2. As shown in FIG. 4, the spoke 4 and the hub 3 which have been pressed to shape, the rim 5 which has been rolled to shape and flash-butt-welded, and the boss 2 which has been forged to shape and machine-finished at its inner circumferential surface are assembled into a completed wheel shape on the setting jig 6, and then laser-beam-welded by laser beams applied in the directions indicated by the arrows in FIG. 2. The joint regions of these parts develop a desired level of mechanical strength simply by being laser-beam-welded with each of laser beams applied respec¬tively in a single direction at one side of the setting jig 6. The laser-beam-welding of the joint regions can be done in a relatively short time of about 10 seconds, which is about one-tenth of the time required by the conventional process of welding the parts of a motor vehicle wheel. According to the above-mentioned process, the parts of the motor vehicle wheel are not significantly thermally affected by the laser beam welding, and hence do not need to be finished or machined to reduce thermal strains after the laser beam welding. Specifically, the drum of the hub 3 does not need to be finished, the inner bearing section of the boss 2 does not need to be finished, and the wheel does not need to be corrected out of imbalance. Consequently, the number of steps required to manufacture the motor vehicle wheel is reduced or simplified. The conventional process of manufacturing a motor vehicle wheel has a large number of steps and hence makes it necessary to take care in ensuring a tolerance in each of the steps in order to minimize an accumulation of tolerances. According to the present invention, however, no such tolerance ensuring process is required because a tolerance may be ensured in only one step, i.e., the step of setting the parts on the setting jig. The above description has been addressed to the manufacture of a rear wheel which comprises four parts. However, a front wheel which comprises three parts may be manufactured similarly as illustrated in a flowchart shown in FIG. 3 by assembling a spoke, a rim and a boss into a completed wheel shape on a setting jig, and laser-beam-welding them each with a laser beam applied in a single direction from one side of the setting jig. The step of laser-beam-welding those three parts is similar to the laser-beam-welding step in FIG. 2 except that the welding of the spoke 4 and the hub 3 is dispensed with. Although there has been described what is at present considered to be the preferred embodiment of the present invention, it will be understood that the invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative, and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description. WE CLAIM: 1. A motor vehicle wheel comprising a joined assembly of a rim, a spoke, a hub and a boss said rim and said spoke having a joint region, and said spoke and said boss having a joint region, characterized in that each of said joint regions is laser-beam-welded by each of laser beams applied respectively in a predetermined single direction. 2. The motor vehicle wheel according to claim 1, wherein said joint region of the spoke and the boss is laser-beam-welded by a laser beam applied substantially parallel to an axis of the motor vehicle wheel, and said joint region of the rim and the spoke is laser-beam-welded by a laser beam applied substantially parallel or perpendicular to the axis of the motor vehicle wheel. 3. A method of manufacturing a motor vehicle wheel, comprising the steps of forming a rim, a spoke and a boss; assembling the rim, the spoke and the boss into a completed wheel shape on a setting jig; and laser-beam-welding a joint region of the rim and the spoke and a joint region of the spoke and the boss with each of laser beams applied respectively in a predetermined single direction. 4. A motor vehicle wheel comprising a joined assembly of a rim, a spoke, a hub and a boss, said rim and said spoke having a joint region, said spoke and said hub having a joint region, and said hub and said boss having a joint region, characterized in that each of said joint regions is laser-beam-welded by each of laser beams applied respectively in a predetermined single direction. 5. The motor vehicle wheel according to claim 4, wherein each of said joint region of the spoke and the hub and said joint region of the hub and the boss is laser-beam-welded by a laser beam applied substantially parallel to an axis of the motor vehicle wheel, and said joint region of the rim and the spoke is laser-beam-welded by a laser beam applied substantially parallel or perpendicular to the axis of the motor vehicle wheel. 6. A method of manufacturing a motor vehicle wheel, comprising the steps of: forming a rim, a spoke, a hub and a boss; assembling the rim, the spoke, the hub and the boss into a completed wheel shape, on a setting jig; and laser-beam-welding a joint region of the rim and the spoke, a joint region of the spoke and the hub, and a joint region of the hub and the boss with each of laser beams applied respectively in a predetermined single direction. 7. A motor vehicle wheel, substantially as herein described with reference to figures 1 to 4 of the accompanying drawings. 8. A method of manufacturing a motor vehicle wheel, substantially as herein described with reference to figures 1 to 4 of the accompanying drawings.

Documents:

293-mas-1997 abstract duplicate.pdf

293-mas-1997 abstract.pdf

293-mas-1997 claims duplicate.pdf

293-mas-1997 claims.pdf

293-mas-1997 correspondence others.pdf

293-mas-1997 correspondence po.pdf

293-mas-1997 description (complete) duplicate.pdf

293-mas-1997 description (complete).pdf

293-mas-1997 drawings.pdf

293-mas-1997 form-1.pdf

293-mas-1997 form-26.pdf

293-mas-1997 form-4.pdf

293-mas-1997 petition.pdf