Abstract:
The present invention provides a method and apparatus for forming thin wall sheet into a mechanically locked shell by providing a Mandrel that is shaped the same as the required shell and a set of forming rollers that forms the said sheet around the said mandrel. And providing gathering and forming and center bares that are parallel to the horizontal axis of the said mandrel and are moved to form the two edges of the said sheet over the said center bar. And wherein the said gathering and forming and center bars are moved to open or up position. And providing Lockseaming rollers that are moved along the axis of the said mandrel such that the said Lockseaming rollers will progressively form the said two edges into the said mechanical lock commonly known to those who are skilled in the art as a Lockseam.

Description:
[0001]     This application Claims the benefits of prior filing date of provisional application number US60/590,950-Filing date Jul. 26, 2004-Applicant Mohamed T. Gharib, Brantford, Canada 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION  
       [0002]     Silencer shells (mufflers) such are the ones used in the automotive industries are formed by wrapping a thin sheet around a mandrel that have the same shape as the desired silencer (muffler) shell, then mechanically locking the two sheet edges using a process called Lockseaming. The Lockseaming process involves the use of gathering and Lockseaming rollers and produces drag on the sheet edges. This drag forces sheet material away from the Lockseam and causes the trailing end of the Lockseamed shell to be larger than the leading end. And causes the Lockseam to deteriorate at the trailing end of the Lockseamed shell.  
         [0003]     The current invention uses gathering bars and forming bars to gather the two sheet edges and perform the two edges at the correct location before Lockseaming. This greatly reduces the drag on the sheet edges and keeps the difference between the circumference of the trailing end of the Lockseamed shell and the leading end to a minimum and maintains the quality of the Lockseam along the entire Silencer shell length. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]     The present invention will become more fully understood from the detailed description and the accompanying drawings wherein:  
         [0005]      FIG. 1  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in upper position, gathering and forming bars in the closed position and centre bar in the down position  
         [0006]      FIG. 1   a  and  1   b  are sectional views of forming bars and centre bar showing two different shapes.  
         [0007]      FIG. 2  is showing a Lockseaming apparatus according to prior art showing forming rollers in the down position  
         [0008]      FIG. 3  is showing a Lockseaming apparatus according to prior art showing forming rollers in the up position and the sheet is partially formed around the mandrel.  
         [0009]      FIG. 4  is showing a Lockseaming apparatus according to prior art showing forming rollers in the up position and the roll carriage and gathering rollers are pre forming the two sheet edges.  
         [0010]      FIG. 5  is showing a Lockseaming apparatus according to prior art showing forming rollers in the up position and the roll carriage and gathering rollers are in advanced position of the pre-forming process.  
         [0011]      FIG. 6  is showing a Lockseaming apparatus according to prior art showing forming rollers in the up position and the roll carriage and Lockseaming rollers are Lockseaming the two sheet edges.  
         [0012]      FIG. 7  is showing a typical roll carriage with gathering and Lockseaming rollers.  FIG. 8  is showing an enlargement of the finished Lockseam of an oval and a round Silencer (Muffler) shell.  
         [0013]      FIG. 9  is showing a Lockseaming apparatus according to prior art when Lockseaming large diameter Silencer (Muffler) shell.  
         [0014]      FIG. 10  is showing a Lockseaming apparatus according to prior art when Lockseaming large diameter Silencer (Muffler) shell and the forming rollers are raised higher to form a larger section of the sheet around the mandrel.  
         [0015]      FIG. 11  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in down position, gathering and forming bars in the open position and centre bar in the down position  
         [0016]      FIG. 12  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in upper position, gathering and forming bars in the open position and centre bar in the down position  
         [0017]      FIG. 13  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in upper position, gathering bars in the closed position, forming bars in the open position and centre bar in the down position  
         [0018]      FIG. 14  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in upper position, gathering and forming bars in the closed position and centre bar in the down position  
         [0019]      FIG. 15  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in upper position, gathering bars in the closed position, forming bars in the open position and centre bar in the up position.  
         [0020]      FIG. 16  is sectional view of Lockseaming apparatus according to current invention showing forming rollers in upper position, gathering bars in the closed position, forming bars in the open position and centre bar in the up position while roll carriage and Lockseaming rollers are performing the Lockseaming operation  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     With reference to  FIGS. 2, 3 ,  4 ,  5 ,  6  and  7   a  description of the prior art technique for forming thin wall sheet into an Automotive Muffler Shell will be described. The forming technique according to the prior art includes providing a Mandrel  1  that is shaped the same as required muffler shell which can be Round or Oval or irregular shape.  
         [0022]     A sheet  2  is placed under the said mandrel  1  and above Forming rollers  3  and  4  and pressure bar  12 . The said rollers  3  and  4  are mounted on arms  5  and  6  and allowed to rotate around centres  7  and  8  that are mounted on platform  11 . Springs  9  and  10  are acting as to apply force against the said arms  5  and  6 .  
         [0023]     The said pressure bar  12  is mounted on pneumatic cylinder  13  and is allowed to move up and down  
         [0024]     The said platform  11  is moved up and down by the use of hydraulic cylinders or other means. As the said platform  11  moves up, the said forming rollers  3  and  4  along with the said arms  5  and  6  are rotated around the said centres  7  and  8  allowing the forces of the said springs  9  and  10  to be exerted on the said sheet  2  such that the said sheet  2  is partially formed around the said mandrel  1  as shown in  FIG. 3 .  
         [0025]     A set of gathering rollers  15  and  16  and vertical rollers  17  are mounted on roll carriage  14  and is allowed to travel on top of the said mandrel  1  and along the horizontal axis of the said mandrel  1  such that the two edges of the said sheet  2  are gathered together by the said rollers sets  15  and  16  and formed against the said vertical rollers set  17  as to form edges  39  and  40 .  
         [0026]     As the said roll carriage  14  travels along the axis of the said mandrel  1 , the said set of rollers  15  and the said set of rollers  16  having different shapes will progressively form the said edges  39  and  40  closer as shown in  FIG. 5 .  
         [0027]     Following the said sets of gathering rollers  15  and  16  and  17  is two sets of Lockseaming rollers  18  and  19 . Each of the said sets of rollers  15 ,  16 ,  17 ,  18  and  19  consists of a number of rollers of different shapes and will progressively form the said two edges  39  and  40  into a Lockseam  41  as shown in  FIG. 8   
         [0028]     The number or rollers in the said sets of rollers  15  and  16  is different depending on design and preference. Typically design includes  7  to  9  rollers in each of the said sets of rollers  15  and  16 . The number or rollers in the said set of rollers  17  is different depending on design and preference. Typically design includes  3  rollers in the said set of rollers  17 .  
         [0029]     Similarly the number or rollers in the said sets of Lockseaming rollers  18  and  19  is different depending on design and preference. Typically design includes  7  to  9  rollers in each of the said sets of rollers  18  and  19 .  
         [0030]      FIG. 7  is showing a typical roll carriage arrangement.  
         [0031]     The means of mounting and moving the said roll carriage  14  will vary and is obvious to those skilled in the art.  
         [0032]     The said springs  9  and  10  can be replaced by hydraulic or pneumatic cylinders or other means that are obvious to those skilled in the art.  
         [0033]     According to prior art the said platform  11  is moved to down position along with the said rollers  3  and  4  and the said arms  5  and  6  and the said pressure bar  12 . The said sheet  2  is placed on top of the said forming rollers  3  and  4  and the said pressure bar  12 .  
         [0034]     The said platform  11  is moved up such that the said forming rollers  3  and  4  will partially form the said sheet  2  around the said mandrel  1 .  
         [0035]     The said pressure bar  12  will hold the said sheet  2  firmly against the said mandrel  1  such that the said sheet  2  will not move in horizontal plane relative to the said mandrel  1  while the said platform  11  is moving upward and the said rollers  3  and  4  are forming the said sheet  2  around the said mandrel  1 .  
         [0036]     The said roll carriage  14  with the said gathering rollers sets  15  and  16  and the said vertical rollers set  17  and the said Lockseaming rollers sets  18  and  19  will travel along the axis of the said mandrel  1 . The said gathering roller set will progressively bring the said sheet edges  39  and  40  together and form the said sheet edges  39  and  40  over the said vertical roller set  17 . Furthermore, the said Lockseamer rollers  18  and  19  will progressively form the said two edges  39  and  40  into the said Lockseam  41  as shown in  FIG. 8   
         [0037]     Other means of forming the said sheet  2  around the said mandrel  1  provide forming shoes or horizontal rollers or other means that are obvious to those who are skilled in the art.  
         [0038]     Other means of gathering the said two sheet edges  39  and  40  and progressively forming the said two sheet edges  39  and  40  into the said Lockseam  41  provide perform rollers to form said sheet edges  39  and  40  followed by gathering rollers or gathering bars followed by a set of Lockseaming Rollers or other means that are obvious to those who are skilled in the art.  
         [0039]     The process of gathering the said sheet edges  39  and  40  together causes drag on the said muffler sheet  2  and causes the trailing end of the said muffler shell to be larger in circumference that the starting end. This problem is increased when forming large muffler cross-sections such as large round muffler and asymmetric shapes as illustrated in  FIG. 9 .  
         [0040]     As shown in  FIG. 9  the said forming rollers  3  and  4  are placed at larger distance from the said gathering rollers  15  and  16  and from the said Lockseaming rollers  18  and  19 . That cusses a large section  42  and  43  of the said sheet  2  to be unsupported between the said gathering and Lockseaming rollers  15 , 16 ,  17 ,  18  and  19  and the said forming rollers  3  and  4 . The drag on the said muffler sheet edges  39  and  40  will force the said sheet material into the said areas  42  and  43  causing the trailing end of the said muffler to be larger than the said start end and will cause deterioration of the said Lockseam  41  at the said trailing end.  
         [0041]     By forming a larger section of the said sheet  2  around the said mandrel  1  as shown in  FIG. 10 , the said forming rollers  3  and  4  are closer to the said gathering rollers  15 , 16  and  17  and the said Lockseaming rollers  18  and  19 , however the said sheet edges  39  and  40  are folded over each other making it impossible for the said vertical roller set  17  to separate the said two sheet edges  39  and  40  and to form the said two sheet edges  39  and  40  as shown in  FIG. 5 .  
         [0000]     Present Invention  
         [0042]     The present invention provides a Mandrel  1  that is shaped the same as required muffler shell which can be Round or Oval or irregular shape.  
         [0043]     A sheet  2  is placed under the said mandrel  1  and above forming rollers  3  and  4  and pressure bar  12 . The said forming rollers  3  and  4  are mounted on arms  5  and  6  and are allowed to rotate around centres  7  and  8  that are mounted on platform  11 . Springs  9  and  10  are acting as to apply force against the said arms  5  and  6 .  
         [0044]     The said pressure bar  12  is mounted on pneumatic cylinder  13  and is allowed to move up and down  
         [0045]     The said platform  11  is moved up and down by the use of hydraulic cylinders or other means. As the said platform  11  moves up, the said forming rollers  3  and  4  along with the said arms  5  and  6  are rotated around the said centres  7  and  8  allowing the forces of the said springs  9  and  10  to be exerted on the said sheet  2  such that the said sheet  2  is partially formed around the said mandrel  1  as shown in  FIG. 1 .  
         [0046]     The said springs  9  and  10  can be replaced by hydraulic or pneumatic cylinders or other means that are obvious to those skilled in the art.  
         [0047]     The present invention also provides for gathering bars  20  and  21  that are placed parallel to the horizontal axis of the said mandrel  1 . Further, the said gathering bars  20  and  21  are mounted on arms  22  and  23 . The said arms  22  and  23  are allowed to swivel around axis  30  and  31 . Further, the said gathering bars  20  and  21  and the said arms  22  and  23  are powered by cylinders  32  and  33  such that the said arms  22  and  23  along with the said gathering bars  20  and  21  are rotated between an open and closed position.  
         [0048]     The invention also provides for forming bars  24  and  25  that are placed parallel to the horizontal axis of the said mandrel  1  and mounted on arms  26  and  27  that swivel around the said axis  30  and  31  and powered by a toggle  34  and  35  and slide  38 . The said slide  38  is powered by cylinder  36  such that the said arms  26  and  27  along with the said forming bars  24  and  25  are rotated between and open and closed position.  
         [0049]     The said arms  24  and  25  can have same said axis  30  and  31  as the said arms  22  and  23  or can have different axis.  
         [0050]     The said arms  24  and  25  can be powered directly or through a toggle.  
         [0051]     The invention also provides for centre bar  28  mounted on rods  29  and powered by cylinder  37  such that the said centre bar  28  is moved between an upper and down position.  
         [0052]     The said forming bar  24  will further have a shape  44  that matches the shape  45  of the right hand side of the said centre bar  28 . The said forming bar  25  will further have a shape  46  that matches the shape  47  of the left hand side of the said centre bar  28  as illustrated in  FIGS. 1   a  and  1   b.    
         [0053]     According to the current invention as shown in  FIG. 11 , the said platform  11  is moved to down position along with the said rollers  3  and  4  and the said arms  5  and  6  and the said pressure bar  12 . The said gathering bars  20  and  21  and the said forming bars  24  and  25  along with the said arms  22 ,  23 ,  26  and  27  are rotated to an open position. The said centre bar  28  and the said rod  29  are moved to down position. The said sheet  2  is placed on top of the said forming rollers  3  and  4  and the said pressure bar  12 .  
         [0054]     As shown in  FIG. 12 , the said platform  11  is moved up such that the said forming rollers  3  and  4  will partially form the said sheet  2  around the said mandrel  1  and such that said centre bare  28  is placed between the said two sheet edges  39  and  40 .  
         [0055]     The said pressure bar  12  will hold the said sheet  2  firmly against the said mandrel  1  such that the said sheet  2  will not move in horizontal plane relative to the said mandrel  1  while the said platform  11  is moving upward and the said rollers  3  and  4  are forming the said sheet  2  around the said mandrel  1 .  
         [0056]     As shown in  FIG. 13 , the said gathering bars  20  and  21  along with the said arms  22  and  23  are rotated to a closed position such that the said gathering bars  20  and  21  further form the said sheet  2  around the said mandrel  1  and partially form the said sheet edges  39  and  40  over the said centre bar  28 .  
         [0057]     As shown in  FIG. 14 , the said forming bars  24  and  25  along with the said arms  26  and  27  are rotated to a closed position such that the said forming bar  24  forms the said sheet edge  39  to match the said shapes  44  and  45  of the said forming bar  24  and the said centre bar  28 . Similarly, the said forming bar  25  forms the said sheet edge  40  to match the said shapes  46  and  47  of the said forming bar  25  and the said centre bar  47 .  
         [0058]     As shown in  FIG. 15  the said forming bars  24  and  25  along with the said arms  26  and  27  are rotated around the said centres  30  and  31  to open position and the said centre bar  28  and the said rod  29  are moved to upper position. The said sheet  2  will spring back between the said gathering bars  20  and  21  however the said sheet edges  39  and  40  will maintain its form as illustrated in  FIG. 15 .  
         [0059]     As shown in  FIG. 16  the said roll carriage  14  with the said Lockseaming rollers sets  18  and  19  will travel along the axis of the said mandrel  1 . Each set of the said Lockseaming rollers sets  18  and  19  consists of a number of rollers of different shapes and will progressively form the said two edges  39  and  40  into the said Lockseam  41  as shown in  FIG. 8   
         [0060]     The means of mounting and moving the said roll carriage  14  will vary and is obvious to those skilled in the art.  
         [0061]     The motion of the said gathering bars  20  and  21  and the said forming bars  24  and  25  can be a sliding motion or any other motion that is obvious to those skilled in the art.  
         [0062]     As shown in  FIG. 16 , the said parts  44  and  45  of the said sheet  2  between the said gathering bars  20  and  21  and the said Lockseaming rollers sets  18  and  19  are much smaller than the said parts between the said rollers  3  and  4  and the said Lockseaming rollers sets  18  and  19 . Hence the said sheet  2  is better supported and the circumference difference between the said trailing end of the muffler and the said leading end is kept to a minimum.  
         [0063]     And hence the said sheet edges  39  and  40  are formed using the said forming bars  24  and  25 , there is no need for the said gathering rollers  15  and  16  and the said vertical rollers  17 , hence the said drag on the said sheet edges  39  and  40  is kept to a minimum, hence the circumference difference between the said trailing end of the muffler and the said leading end is kept to a minimum.  
         [0064]     As a result the said Lockseam  41  remain consistent along the entire said muffler length.  
         [0065]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of this invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.