Abstract:
The present invention of pipe-bending apparatus includes: a frame, a bending shoe having gear teeth and concave groove on its outer circumference, a drive-gear, a gear rack having gear teeth and concave groove on one surface and gear teeth only on opposite surface. The frame pivotally supports bending shoe and drive-gear, positions gear rack engaging bending shoe and drive-gear. When using the pipe-bending apparatus, a straight pipe is laid inside the groove on gear rack with one pipe portion secured to bending shoe. Force is applied to turn drive gear, with all gear components engaged, gear rack and pipe transverse downwards and turns bending shoe. With one pipe portion secured to and turning with bending shoe, the pipe begins bending inside the concave groove on bending shoe.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   Not applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   TECHNICAL FIELD 
   The present invention relates generally to a pipe bending system, and more particularly to an improved pipe bending apparatus. 
   SUMMARY OF THE INVENTION 
   The present invention pipe bending apparatus includes: a U-shaped frame having a front arm and a rear arm; a semicircular bending shoe having a row of gear teeth and a semicircular concave groove on outer circumference of the bending shoe; a cylindrical drive-gear having a row of gear teeth on its outer circular surface; and a rectangular gear rack board with gear teeth and a semicircular concave groove on one side of the board and gear teeth only on the opposite side. With two arms, the frame pivotally supports the bending shoe and the drive-gear, positions the gear rack in-between the bending shoe and the drive gear. When the pipe-bending apparatus is in use, a straight pipe is laid inside the concave groove on the gear rack with one pipe end or portion inserted through a locking ring, formed half by the semicircular concave groove on the bending shoe and half by the matching semicircular concave groove on a U-shaped bracket affixed to the bending shoe. A force is applied to and turns the drive-gear, which is engaged to the gear rack first and then to the bending shoe. By the rotating force, the gear rack moves downward together with the pipe and causes the bending shoe to turn. Since one end or portion of the pipe is locked inside the locking ring and secured to the bending shoe, thus the pipe turns together with the bending shoe, causing the pipe to bend along the concave groove on the bending shoe. 
   The pipe bending apparatus of the present invention has these features and benefits: (1) the pipe to be bent is uniformly supported by semicircular groove on the gear rack for feeding to the bending shoe for bending, there is less concentrated force applied to the pipe therefore less chances of crimping and deforming the pipe; (2) with gear teeth engaged among the components, slippages between the components are minimized, exact and accurate bending angle of the pipe can be achieved; (3) the pipe-bending apparatus is compact and portable, thus operable in shallow and tight spaces; (4) changing the bending shoe and gear rack for pipe of different size is easy. 
   Additional advantages of the present invention will become readily apparent with the following description of the preferred embodiment while referencing to the detailed drawings. The invention illustrated in the drawings should not be viewed as a limitation of the present invention but merely as depicting embodiments thereof. 
   BACKGROUND OF THE INVENTION 
   There are many pipe-bending apparatus in the industries for various applications such as for manufacturing large quantities of pipes in a factory or producing smaller quantities in a machine shop or bending a few pipes needed for repair jobs at job site. Also, different pipe-bending apparatus have different features such as utilizing manual, electrical, or hydraulic powers. Some prior arts of pipe-bending apparatus are disclosed in U.S. Pat. Nos. 4,355,528, 4,926,672, 5,469,730, and 5,499,521, etc. 
   The prior art of U.S. Pat. No. 4,355,528 includes a pressing block for pressing the pipe against the bending shoe, and a long handle attached to the pressing block for rotating the pressing block around the bending shoe for bending the pipes. The long handle, as also required in many other prior arts, demands a bigger operating space, which may not always be available. 
   The prior art of U.S. Pat. No. 4,926,672 has a bending shoe installed on a stand and a handle attached to the bending shoe. By applying force to the handle and rotate the bending shoe, the pipe is bent. However, the portion of the pipe supported by the stand is being dragged and sliding on the stand, creating localized stress on the pipe resulting in deformation or surface damage to the pipe. 
   The present invention of pipe-bending apparatus includes several features that are different and improved from the prior arts. Benefits from these features will be shown by the detailed description of the present invention thereafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the pipe-bending apparatus according to the first embodiment of the present invention. 
       FIG. 2  is a perspective view of the frame assembly according to the first embodiment of the present invention. 
       FIG. 3  is a perspective view of the bending shoe assembly according to the first embodiment of the present invention. 
       FIG. 3A  is a perspective view of the components of the bending shoe assembly of  FIG. 3 . 
       FIG. 3B  is a perspective view of the bending shoe assembly installed onto the frame assembly according to the first embodiment of the present invention. 
       FIG. 4  is a perspective view of the drive-gear assembly according to the first embodiment of the present invention. 
       FIG. 4A  is a perspective view of the components of the drive-gear assembly of  FIG. 4 . 
       FIG. 4B  is a perspective view of the drive gear assembly installed onto the frame assembly according to the first embodiment of the present invention. 
       FIG. 5  is a perspective view of the gear rack according to the first embodiment of the present invention. 
       FIG. 5A  is a perspective view of the gear rack installed onto the frame assembly according to the first embodiment of the present invention. 
       FIG. 6  is a top view of the bending shoe assembly, the drive-gear assembly and the gear rack installed onto the frame assembly according to the first embodiment of the present invention. 
       FIG. 7  is a cross sectional (along line  6 A- 6 A in  FIG. 6 ) front view of the bending shoe assembly, the drive-gear assembly and the gear rack installed onto the frame assembly according to the first embodiment of the present invention. 
       FIG. 8  is a perspective view of the pipe-bending apparatus with a straight pipe installed therein according to the first embodiment of the present invention. 
       FIG. 9  is a front view of the pipe-bending apparatus with a bent pipe installed therein according to the first embodiment of the present invention. 
       FIG. 10  is a perspective view of the bending apparatus with a bent pipe installed therein according to the first embodiment of the present invention. 
       FIG. 11  is a perspective view of the pipe-bending apparatus according to the second embodiment of the present invention. 
       FIG. 12  is a perspective view of the bending shoe assembly according to the second embodiment of the present invention. 
       FIG. 12A  is a perspective view of the components of the bending shoe assembly of  FIG. 12 . 
       FIG. 12B  is a perspective view of the bending shoe assembly installed onto the frame assembly according to the second embodiment of the present invention. 
       FIG. 13  is a perspective view of the drive-gear assembly according to the second embodiment of the present invention. 
       FIG. 13A  is a perspective view of the components of the drive-gear assembly of  FIG. 13 . 
       FIG. 13B  is a perspective view of the drive-gear assembly installed onto the frame assembly according to the second embodiment of the present invention. 
       FIG. 14  is a top view of the bending shoe assembly, the drive gear assembly and the gear rack installed onto the frame assembly according to the second embodiment of the present invention. 
       FIG. 15  is a cross sectional (along line  14 A- 14 A in  FIG. 14 ) front view of the bending shoe assembly, the drive gear assembly and the gear rack installed onto the frame assembly according to the second embodiment of the present invention. 
       FIG. 16  is a perspective view of the pipe-bending apparatus with a straight pipe installed therein according to the second embodiment of the present invention. 
       FIG. 17  is a front view of the pipe-bending apparatus with a bent pipe installed therein according to the second embodiment of the present invention. 
       FIG. 18  is a perspective view of the pipe-bending apparatus with a bent pipe installed therein according to the second embodiment of the present invention. 
       FIG. 19  is a perspective view of the pipe-bending apparatus according to the third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   As shown in  FIG. 1 , according to the first embodiment of the present invention, the pipe-bending apparatus  10  includes a frame assembly  20 , a bending shoe assembly  30 , a drive-gear assembly  40 , and a gear rack  50 . 
     FIG. 2  shows frame assembly  20 , which includes a U-shaped frame  21  and firmly affixed U-channels  22  and  23  with U-shaped grooves  22   a  and  23   a . Frame  21  includes a front arm  21   a  and a rear arm  21   b , both having openings  24  and  25 , through holes  26  and  27 , and protrusions  24   a ,  24   b ,  25   a  and  25   b  (protrusions on frame rear portion  21  are not visible in this view). 
     FIG. 3  shows bending shoe assembly  30  having two circumferential cavities  37   a  and  37   b.    
   As shown in  FIG. 3A , the components in bending shoe assembly  30  include: a bending shoe  31  with semicircular grooves  31   a  and  31   b  on the outer circumferential peripheral, holes  31   c  and  31   d , a circumferential gear sector  32  with holes  32   a , a U bracket  33  with semicircular grooves  33   a  and  33   b , and holes  33   c , a pin  34  with a hole  34   a , a spring pin  34   b , a bolt pin  35  with a hole  35   a , a spring pin  35   b , and two bearings  36  in the form of flange bushings. 
   When bending shoe assembly  30  is fully assembled, bearings  36  are firmly affixed into bending shoe hole  31   c , bolt  35  is placed through bearings  36 , and spring pin  35   b  is placed through hole  35   a  on bolt pin  35 , gear sector  32  is firmly affixed to bending shoe  31  by bolts (not shown) placing through holes  32   a  and holes (not shown) on bending shoe  31 , holes  33   c  on U bracket  33  are aligned with hole  31   d  on bending shoe, and pin  34  is inserted through hole  33   c  and  31   d , and spring pin  34   b  is inserted through hole  34   a  on pin  34  to keep pin  34  in place, such that bracket  33  is pivotally attached to bending shoe  31  with grooves  33   a  and  33   b  on bracket  33  aligned with grooves  31   a  and  31   b  on bending shoe  30 . 
   Referring to  FIG. 3  again, when bending shoe assembly  30  is assembled together, semicircular grooves  33   a ,  33   b  on U-bracket  33  and semicircular grooves  31   a ,  31   b  on bending shoe  31  jointly form two circumferential cavities  37   a  and  37   b  for insertion of at least one circumferential pipe to be bent. 
   Referring to  FIG. 3B , when bending shoe assembly  30  is installed onto frame assembly  20 , bending shoe assembly  30  is fitted between front frame arm  21   a  and rear frame arm  21   b  with bending shoe hole  31   c  aligned with frame holes  26 , and bolt pin  35  is inserted through them and spring pin  35   b  is insert through hole  35   a  on bolt pin  35  to keep pin  35  in place, such that bending shoe assembly  30  is able to rotate around bolt pin  35 . Holes  27  on frame  21  allows a bigger circumferential bending shoe to be installed onto frame assembly  20 . 
     FIG. 4  shows drive-gear assembly  40  having two identical gears  41  engaged to each other. 
     FIG. 4A  shows the components in drive-gear assembly  40  includes: two gears  41 , four bearings  42  in the form of flange bushings, and two end caps  43 , each having two holes  43   c  and a protruding portion  43   a  with two holes  43   b . Each gear  41  has circumferential gear teeth  41   a , cylindrical surfaces  41   b  and  41   c  of reduced diameters, and hexagonal ends  41   d.    
   When drive-gear assembly  40  is assembled together, bearings  42  are firmly affixed to corresponding holes  43   b , and drive-gear surfaces  41   c  fit inside holes of corresponding bearings  42  such that gear  41  can rotate inside end caps  43 . Same installation is applied to both drive-gear  41 . Gear teeth  41   a  on two drive-gears  41  are engaged to each other. 
     FIG. 4B  shows drive-gear assembly  40  assembled into frame assembly  20 . Drive-gear assembly  40  (without end caps  43 ) is place between front frame arm  21   a  and rear frame arm  21   b . End caps  43  each having protruding portions  43   a  are inserted toward and fitted into rectangular holes  24  (also shown in  FIG. 2 ), and protrusions  24   a  and  24   b  on frame  21  protrude through the holes on end caps  43 . Four spring pins  45  are individually inserted through a hole on protrusions  24   a ,  24   b  on front frame arm  21   a  and rear frame arm  21   b  to keep end caps  43  attached to frame assembly  20 . Drive gears  41  are able to rotate inside frame assembly  20 . 
     FIG. 5  shows gear rack  50  having two roles of gear teeth  51  and  52 , two semicircular grooves  53  and  54  on one side, and one row of gear teeth  55  (not visible in this view) on the opposite side. Gear rack  50  also has two custom shaped edges  56  and  57  for fitting into the grooves  22   a  and  23   a  of frame assembly  20  (as shown in  FIG. 2 ). 
   Referring to  FIG. 5A , when gear rack  50  is installed onto frame assembly  20 , gear rack edges  56  and  57  each is fitted into grooves  22   a  and  23   a  respectively on U-channels  22  and  23  on frame assembly  20 . Gear rack  50  is able to slide inside grooves  22   a  and  23   a.    
     FIG. 6  shows a top view of frame assembly  20  when bending shoe assembly  30 , drive-gear assembly  40 , and gear rack  50 , are installed onto frame assembly  20 . The semicircular grooves on gear rack  50  are concentric with the two circumferential cavities  37 A and  37 B (also show in  FIG. 3 ) when bending shoe assembly is in this position, such that circumferential straight pipes can be inserted along semicircular grooves  53  and  54  and into cavities  37   a  and  37   b.    
     FIG. 7  shows a view taken from  FIG. 6  along arrows  6 A to  6 A. The gear teeth are engaged from drive gear  41  to gear rack  50 , and to bending shoe assembly  30 , such that when drive gear  41  is being rotated, the rotating motion will transmit to gear rack  50 , and to bending shoe assembly  30 . As shown, gear rack  50  is at its transverse upper limit location, and bending shoe assembly  30  is at its clockwise rotation limit, such that at these settings, a straight circumferential pipes (not shown) can be inserted along semicircular grooves (shown in  FIG. 6 ) on gear rack  50  and through cavities  37   a  or  37   b  (shown in  FIG. 3 ) formed between U-bracket  33  and bending shoe  31 . For this reason, the settings of gear rack  50  and bending shoe assembly  30  shown are used as the beginning settings for bending a straight pipe. 
     FIG. 8  shows pipe-bending apparatus  10  with a straight pipe  71  inserted along semicircular groove  53  on gear rack  50  and into circumferential cavity  37   a  on bending shoe assembly  30 . 
     FIG. 9  shows pipe-bending apparatus  10  with a bent pipe  72  after a pipe bending process, such that drive-gear  41  was rotated clockwise by an applied rotating motion (not shown), and through the gear teeth engagement from drive-gear  41  to gear rack  50  and to bending shoe  31 , gear rack  50  had been transverse downwards, bending shoe  31  was rotated counter clockwise. With bending shoe  31  having pipe  72  lower portion held by bracket  33  close to bending shoe  31 , pipe  72  was bent along semicircular grooves on bending shoe  31 . 
   Pipe-bending apparatus  10  has a pipe-bending process similar to a rolling mill action because the pipe is supported and fed to bending shoe  31  by gear rack  50  and rolled by the rotating bending shoe into shape. Because pipe  72  to be bent portion entirety is supported by semicircular groove on gear rack  50 , there are less concentrated force applied to the pipe and thus has less tendencies of deforming and crimping the pipe. 
     FIG. 10  shows two forces  73   a  and  74   a  are being applied to two ratchets  73  and  74  with sockets  75  and  76  connected to the hexagonal end of each drive-gears  41  respectively for applying torque to drive-gears  41  for bending the pipe. When ratchets  73  and  74  are turned by both hands at the same time, the applied torque to the tool is doubled, and it is easier for a person to apply the forces too. 
     FIG. 11  shows a pipe-bending apparatus  110  according to the second embodiment of the present invention. 
   As shown in  FIG. 11 , pipe-bending apparatus  110  includes a frame assembly  20 , a bending shoe assembly  130 , two of drive-gear assemblies  140 , and a gear rack  50 . Frame assembly  20  and gear rack  50  are the same as were described in the first embodiment of the present invention, so that these components will not be illustrated again. 
     FIG. 12  shows bending shoe assembly  130  having two circumferential cavities  137   a  and  137   b.    
     FIG. 12A  shows the components in bending shoe assembly  130  including: a bending shoe  131  having semicircular grooves  131   a  and  131   b  on the outer circumferential peripheral, two rows of circumferential internal gear teeth  137  and  138 , holes  131   c  and  131   d , a circumferential gear sector  132  having holes  132   a , a U bracket  133  having semicircular grooves  133   a  and  133   b , and holes  133   c , a pin  134  having a hole  134   a , a spring pin  134   b , a pin  135  having a hole  135   a , a spring pin  135   b , and two bearings  136  in the form of flange bushings. 
   When the components in bending shoe assembly  130  are being assembled, bearings  136  are firmly affixed into bending shoe hole  131   c , bolt  135  is placed through bearings  136 , and spring pin  135   b  is placed through hole  135   a  on bolt  135 , gear sector  132  is firmly affixed to bending shoe  131  by bolts (not shown) placing through holes  132   a  and holes (not shown) on bending shoe  131 , holes  133   c  on U bracket  133  are aligned with hole  131   d  on bending shoe, and bolt  134  is inserted through hole  133   c ,  131   d , and  133   c , and spring pin  134   b  is inserted through hole  134   a  on pin  134  to keep pin  134  in place, such that bracket  133  is pivotally attached to bending shoe  131  with grooves  133   a  and  133   b  on bracket  133  aligned with grooves  131   a  and  131   b  on bending shoe  130 . 
   Referring also back to  FIG. 12 , when the components in bending shoe assembly  130  are assembled together, semicircular grooves on U-bracket  133  and semicircular grooves on bending shoe  131  have formed two circumferential cavities  137   a  and  137   b , such that circumferential pipes can be inserted through therein. 
   Referring to  FIG. 12B , when bending shoe assembly  130  is installed onto frame assembly  20 , bending shoe assembly  130  is fitted between front frame arm  21   a  and rear frame arm  21   b , hole  131   c  on bending shoe aligned with holes  26  on frame  21 , and pin  135  is inserted through the holes, spring pin  135   b  is insert through hole  135   a  on pin  135  fixing pin  135  in place, such that bending shoe assembly  130  is able to rotate around pin  135 . Hole  27  on frame  21  allows a bigger circumferential bending shoe to be installed onto frame assembly  20 . 
     FIG. 13  shows drive-gear assembly  140  having gears  141  and  144 . 
     FIG. 13A  shows drive-gear assembly  140  components, which includes: drive gears  141  and  144 , four bearings  142  in the form of flange bushings, an end cap  143  having two holes  143   c  and a protruding rectangular portion  143   a  having two holes  143   b , and two of retaining rings  145 . Drive-gear  141  includes a circumferential gear teeth  141   a , a reduced circumferential diameter surfaces  141   b , a groove  141   c , and a hexagonal end  141   d . Drive gear  144  is identical to drive gear  141 . 
   When drive-gear assembly  140  is assembled, bearings  142  are firmly affixed to holes  143   b , surface  141   b  of gear  141  fits inside bearings  142 , such that drive gear  141  is able to rotate inside end cap  143 , and retaining ring  145  is placed onto groove  141   c  to keep drive gear  141  therein. Gear  144  is installed the same way. Teeth on gear  141  and gear  144  are engaged. 
     FIG. 13B  shows when two of drive-gear assembly  140  are assembled into frame assembly  20 , such that each drive-gear assembly  140  end cap  143  protruding rectangular portion is inserted toward and fitted into holes  25  (also shown in  FIG. 2 ) on frame  21 , and protrusions  25   a  and  25   b  on frame  21  protrude through the holes on end caps  143 . Four of spring pins  145  are inserted through holes on protrusions  25   a  and  25   b  on both the front arm  21   a  and rear arm  21   b  in order to keep end caps  143  attached to frame assembly  20 . Gears  141  and  144  are able to rotate inside frame assembly  20 . 
     FIG. 14  shows a top view of frame assembly  20  when bending shoe assembly  130 , drive-gear assemblies  140 , and gear rack  50 , are installed onto frame assembly  20 . The semicircular grooves  53  and  54  on gear rack  50  are concentric with two semicircular grooves  131   a  and  131   b  of forming two circumferential cavities  137   a  and  137   b  (also show on  FIG. 12 ) when bending shoe assembly is in this position, such that circumferential straight pipes can be inserted along semicircular grooves  53  and  54  on gear rack  50  and into cavities  137   a  and  137   b.    
     FIG. 15  shows a view taken from  FIG. 14  along arrows  14 A to  14 A. The gear teeth are engaged from drive-gear  141 , drive-gear  144 , bending shoe assembly  130 , and to gear rack  50 , such that when drive-gear  141  is being rotated, the rotating motion will transmit through drive-gear  144 , bending shoe assembly  130 , and to gear rack  50 . As shown, gear rack  50  is at its transverse upper limit location, and bending shoe assembly  130  is at its clockwise rotation limit, such that at these settings, straight circumferential pipes (not shown) can be inserted along semicircular grooves  53  and  54  (shown in  FIG. 14 ) on gear rack  50  and through cavities  137   a  or  137   b  (also shown in  FIG. 12 ) formed between the U-bracket and the bending shoe. For this reason, the positions settings of gear rack  50  and bending shoe assembly  130  shown are used as the beginning settings for bending a straight pipe. 
     FIG. 16  shows pipe-bending apparatus  110  with a straight pipe  171  inserted along semicircular groove  53  on gear rack  50  and into circumferential cavity  137   a  on bending shoe assembly  130 . 
     FIG. 17  shows pipe-bending apparatus  110  with a bent pipe  172  after a pipe bending process, such that drive gear  141  was rotated clockwise by an applied rotating motion (not shown), and through the gear teeth engagement from drive gear  141  to drive gear  144  to bending shoe  131  and to gear rack  50 , bending shoe  131  was rotated counterclockwise. With bending shoe  131  having the lower portion of pipe  172  held by bracket  133  close to bending shoe  131 , pipe  172  was bent along semicircular grooves on bending shoe  131 , and gear rack  50  was transverse downwards of feeding pipe  172  into bending shoe  131 . 
     FIG. 18  shows two forces  173   a  and  174   a  are being applied to two ratchets  173  and  174  with sockets  175  and  176  connected to hexagonal ends of drive-gear  141  and  144  respectively for applying torque to drive-gear  141  and  144  for bending the pipe. When ratchets  173  and  174  are applied by both hands at the same time, the applied torque to the tool is doubled, and it is easier for a person to apply the forces too. 
     FIG. 19  shows a pipe-bending apparatus  210  according to the third embodiment of the present invention. 
   Pipe bending apparatus  210  including the installation of drive-gear assembly  40  (shown in  FIG. 4  of the first embodiment of the present invention) into the pipe-bending apparatus  110  that was shown in  FIG. 11 . Ratchet  174  is used to drive drive-gear assembly  40  which in turn drives gear rack  50 ; and ratchet  173  is used to drive bending shoe  130 , such that forces are applied more uniformly to the tool, thus causing less stresses and strains to the tool.