Abstract:
A method of making a gas tank includes hydroforming two halves and welding the halves together. Two types of welds are used in welding the two halves together, tack welds for holding the two halves together, and stitch welds to complete the welding of the two halves. Additional steps are taken prior to the finishing stitch welds. Reinforcement is added where necessary. Double tanks, for both gasoline and oil, are also fabricated by essentially the same method steps.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation-in-part of Ser. No. 09/494,479, filed Jan. 31, 2000, which was a continuation-in-part application of Ser. No. 29/113,069, filed Oct. 29, 1999, now U.S. Pat. No. Des. 432,486, issued Oct. 24, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to gas tanks and, more particularly, to the fabrication of a gas tank for motorcycles.  
           [0004]    2. Description of the Prior Art  
           [0005]    There are primarily two types of gas tanks for motorcycles, one fabricated from aluminum and a second fabricated from steel. The gas tanks, regardless of what material they are made out of, are typically formed or stamped and then welded together. Typically, prior art gas tanks have been lap welded. Prior to the present invention, hydroforming techniques have not been used in fabricating motorcycle gas tanks. Different fabricating approaches are used, depending on a particular motorcycle chassis that the tank will be fitted to. The tanks include a tunnel area which receives part of the motorcycle chassis. This tunnel area may present structural and fabrication problems. Prior art gas tanks may be susceptible to vibration and cracking, which results in gasoline leaking from the tank, and this may result in fire problems.  
           [0006]    Another problem is simply the structural strength of the tank is important, such as in case of an accident where the tank may break, with the resulting loss of gasoline and the potential for fire.  
           [0007]    Welding techniques of the prior art typically use continuous beads and lap welds. This results in heat problems and ultimately results in structural problems in the tanks.  
           [0008]    The method of the present invention overcomes the problems of prior art motorcycle gas tanks. Heavier gauge steel is used in the present method, and the specific steps outlined provide a gas tank for a motorcycle which is strong and which may be adapted to different types of motorcycle chassis. Butt welds are used, and the butt welds are stitch welded.  
         SUMMARY OF THE INVENTION  
         [0009]    The invention described and claimed herein comprises a method for making a gas tank for a motorcycle which includes a series of steps beginning with the forming of two halves by hydroforming techniques. The two halves are butted together and tack welded prior to being stitch welded. A reinforcing plate is welded inside the tank at the juncture of the two halves after a bottom tunnel portion is cut from the joined halves. The resulting gas tank is structurally strong.  
           [0010]    Among the objects of the present invention are the following:  
           [0011]    To provide a new and useful method of making a gas tank;  
           [0012]    To provide a new and useful method of making a gas tank for a motorcycle;  
           [0013]    To provide a new and useful method of making a gas tank for a motorcycle by hydroforming two tank halves;  
           [0014]    To provide a new and useful method of making a gas tank for a motorcycle by stitch welding butted tank halves;  
           [0015]    To provide a new and useful method of making a double tank unit including a gas tank and an oil tank; and  
           [0016]    To provide a new and useful method of forming and welding a motorcycle gas tank.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0017]    [0017]FIG. 1 is a side view of the right half of the gas tank made by the present invention.  
         [0018]    [0018]FIG. 2 is a side view of the left half of the gas tank made by the present method.  
         [0019]    [0019]FIG. 3 is a top view of the two halves showing excess material.  
         [0020]    [0020]FIG. 4 is a top view of the two halves after tack welding.  
         [0021]    [0021]FIG. 5 is a front view of the two tack welded halves with the tunnel area cut out.  
         [0022]    [0022]FIG. 6 is a bottom plan view showing a plate disposed against the top or upper portion of the tank.  
         [0023]    [0023]FIG. 7 is a bottom plan view showing a tunnel piece welded in place.  
         [0024]    [0024]FIG. 8 is a plan view of a rear end piece.  
         [0025]    [0025]FIG. 9 is a bottom plan view sequentially following FIGS. 7 and 8.  
         [0026]    [0026]FIG. 10 is a top view sequentially following FIG. 9.  
         [0027]    [0027]FIG. 11 is a front view sequentially following FIG. 10.  
         [0028]    [0028]FIG. 12 is a perspective view sequentially following FIG. 11 of the completed tank.  
         [0029]    [0029]FIG. 13 is a bottom view of the completed tank.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    The gas tanks made by the method of the present invention are made of sixteen gauge cold rolled steel. This is relatively heavy steel, but it is preferred because of its strength. Even though gas tanks made of sixteen gauge steel are heavier than gas tanks made out of either aluminum or eighteen gauge steel, the strength factor, along with the attendant safety factor, more than overcome the weight disadvantage.  
         [0031]    The following table 1 outlines the steps taken in manufacturing a gas tank by the present method.  
                   TABLE 1                            1.   Stamp both sides        2.   Trim excess material from sides        3.   Tack weld side halves        4.   Cut out bottom tunnel area        5.   Add sheet metal panel to inside of tank top portion        6.   Weld sheet metal panel to tank        7.   Form tunnel        8.   Weld tunnel to tank halves        9.   Form bottom rear end piece       10.   Weld bottom rear end piece to tank halves       11.   Weld tank       12.   Form mounting brackets       13.   Weld mounting brackets       14.   Drill mounting brackets       15.   Drill crossover holes and petcock hole[s]       16.   Position tapped mounting bungs, crossover bungs, and petcock           bung[s]       17.   Tack weld and weld mounting bungs, crossover bungs, and           petcock bung[s]       18.   Turn unit over       19.   Drill gas cap fitting       20.   Clean out unit through gas cap fitting hole       21.   Position gas cap fitting       22.   Tack weld and weld gas cap fitting       23.   Position seat pocket plate       24.   Tack weld and weld seat pocket plate       25.   Grind welds       26.   Pressure test                  
 
         [0032]    It will be noted that the gas tanks are formed in halves, and the halves are longitudinal halves. That is, two longitudinally extending halves are formed of the cold rolled steel. The forming is preferably done by stamping both halves, or sides, by hydroforming. Preferably, sixteen gauge cold rolled steel is used in the fabrication of a gas tank. A right side half  10  is shown in FIG. 1 and a left side half  14  is shown in FIG. 2.  
         [0033]    The second step is trimming the excess material from the formed sides. The two halves are then butted together and tack welded. TIG (Tungsten Inert Gas) welding is preferably used. FIG. 3 shows excess material  12  and  16  on the halves  10  and  14 , respectively.  
         [0034]    [0034]FIG. 4 shows the two trimmed halves  10  and  14  butted together and tack welded by tack welds  18 .  
         [0035]    The tack welded tank is then inverted and a bottom tunnel area  20  is cut from the two tack welded halves. FIG. 5 is a front view of the two halves  10  and  14  with the tunnel area  20  cut from the two halves. With the tunnel area  20  removed from the two halves, a sheet metal panel  22  is added to the inside of the tank top portion. This reinforcing panel  22  is then lap welded to both sides of the tank. The panel  22  is shown in FIG. 6, which is a bottom plan view of the two tank halves  10  and  14 .  
         [0036]    Panels are then added to form the tunnel area and the panels are first tack welded and then welded in place. FIG. 7 shows a formed tunnel  30  secured to the halves  10  and  14  by stitch welds  32  and  34 , respectively.  
         [0037]    The bottom rear of the tank is then formed, butted against the tank, and tack welded to the two halves. The bottom rear end piece is then welded to the tank. A bottom rear end piece  40  is shown in FIG. 8, which is a bottom plan view of the end piece  40 .  
         [0038]    Following the welding step of the rear end piece to the tank halves, the tank halves are then welded together in a permanent weld. Stitch welding is used to make certain that the metal does not overheat in the area of the welds. The stitches are overrun to make certain that there are no voids in the weld beads. The overheating of the metal will result in brittleness, which is highly undesirable. Rather, stitch welding techniques are used so that the tank portions have a chance to cool between stitches. This prevents the overheating of the tank and thus avoids the brittleness problem.  
         [0039]    Mounting brackets are formed next and then the mounting brackets are welded to the bottom of the tank at the tunnel area. The mounting bracket holes are then drilled, and at the same time the crossover holes and a petcock hole are also drilled. Tapped mounting bungs, crossover bungs, and a petcock bung are then positioned in the drilled holes and are tack welded in place. After the tack welding step, the mounting bungs, crossover bungs, and the petcock bung are finish welded.  
         [0040]    [0040]FIG. 9 is a bottom plan view showing a pair of right side mounting brackets  50  and  54  in place, with a pair of mounting bungs  52  and  56  welded to the brackets  50  and  54 , respectively. A pair of left side mounting brackets  60  and  64  are also shown with their bungs  62  and  64 , respectively. Also shown are crossover bungs  70  and  72 , and a petcock bung  74 , all welded in place. Finished welds  36  and  38  for the tunnel  30  are also shown.  
         [0041]    The gas tank unit is then turned over and a gas cap fitting hole  76  is drilled. The unit is then cleaned through the gas cap fitting hole. FIG. 10 shows finished welds  42  and  44  and the gas cap fitting hole  76 .  
         [0042]    After the interior of the unit is cleaned, a gas cap fitting  78  is positioned in place in the hole, is tack welded, and then is welded in place. This is shown in FIG. 11.  
         [0043]    A seat pocket plate  80 , shown in FIG. 10, is then positioned, tack welded, and welded in place. FIG. 10 also shows finished welds  42  and  44  for the end piece  40  and the halves  10  and  14 .  
         [0044]    All of the welds are then ground down as desired and the finished unit is pressure tested. If the pressure test is successful, the gas tank is considered finished and is then ready for shipment, painting, and installation on a motorcycle.  
         [0045]    [0045]FIG. 12 is a perspective front view of finished tank  90 , with the welds ground down, and FIG. 13 is a bottom plan view of the finished tank  90 .  
         [0046]    In making a double tank unit, that is, a unit that includes a gas tank in the forward portion and an oil tank in the rear portion, the same essential steps illustrated in table 1 are employed, as illustrated in FIGS.  1 - 13 , with the additional steps illustrated in Table 2. However, the steps outlined in Table 2 are added prior to the pressure test step.  
                           TABLE 2                                       27.   Repeat steps 1-26 (from Table 1)           28.   Cut off oil portion           29.   Clean out unit           30.   Cut off side panel for recessed panel           31.   Drill holes for return fittings in recessed panel           32.   Position, tack weld return fittings           33.   Position and tack weld recessed panel           34.   Drill fitting holes and oil cap holes           35.   Position and weld breather tube           36.   Weld plates onto the two portions           37.   Weld two portions together           38.   Weld recessed panel           39.   Weld fittings           40.   Position, tack weld, and weld oil cap bung           41.   Grind welds           42.   Pressure test                      
 
         [0047]    The first step in making a dual tank unit, after the steps outlined in Table 1, is to cut off the oil portion of the finished tank. The unit is then cleaned out. That is, both the front portion and the rear portion are cleaned out. A side panel is then cut off the rear or oil portion to provide for a recessed panel.  
         [0048]    Holes are drilled in the recessed panel for return oil fittings and the return oil fittings are positioned and tack welded onto the recessed panel. The recessed panel is the positioned in the side of the oil tank portion and tack welded in place.  
         [0049]    Fitting holes and an oil cap hole are then drilled in the oil tank portion. Next, a breather tube is positioned and welded in place on the inside of the oil portion.  
         [0050]    Next, plates are welded onto the two portions. That is, a rear plate is welded onto the gas tank portion and a front plate is welded onto the oil tank portion. The two portions are then welded together. Note that there are two plates or panels that separate the gas tank portion from the oil tank portion.  
         [0051]    Following the welding of the two portions together, the recessed panel is welded in place and the fittings are then welded in place in the recessed panel.  
         [0052]    Next, the fittings and oil cap bung are welded to the oil tank portion. Then, all of the welds are ground down and a pressure test of the unit is then accomplished.  
         [0053]    Once again, if the pressure test is satisfactory, the double tank is considered completed and is ready for shipment, painting, and installation on a motorcycle.  
         [0054]    It will be noted, that, if desired, the fabrication of the double tank, the gasoline and oil tank, may omit step  23  of Table 1 before cutting the oil tank portion from the gas tank. If such is done, that step, positioning and welding the seat pocket plate, is then accomplished after step  14  of table 2. That is, the seat pocket plate is positioned and welded prior to grinding off the welds.  
         [0055]    While the principles of the invention have been made clear in illustrative embodiments, without departing from those principles there may occur to those skilled in the art modifications of structure, arrangement, proportions, the elements, materials, and components used in the practice of the invention, or otherwise, which are particularly adapted to specific environments and operative requirements. The appended claims are intended to cover and embrace any and all such modifications, within the limits only of the true spirit and scope of the invention.