Abstract:
A pipe bender includes first and second handles pivotably secured together wherein the second handle includes first and second rotatable pipe receiving grooves at both ends of a forward U; a support member threadedly fastened between a forward bifurcation of the first handle, the support member comprising a spring depressible detent on the bottom, and a plurality of markings on the top; and a slide member comprising a plurality of parallel arcuate pipe receiving channels of different arcuate perimeters on a lower surface, a central U-shaped trough on the top for receiving a lower portion of the support member, retaining holes on the bottom of the U-shaped trough, each retaining hole being aligned with one pipe receiving channel and one retaining hole adapted to lockingly receive the detent for positioning. The slide member is slidably retained by the support member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to pipe benders and more particularly to a hand-held pipe bender with improved characteristics including capable of cutting one of four pipes of different sizes. 
         [0003]    2. Description of Related Art 
         [0004]    Because stock conduit typically is provided in linear portions, it often must be bent into various shapes to suit these purposes. However, when bending the conduit, it is important to avoid collapsing, crimping or deforming the conduit sidewalls to preserve the lumen within. This is necessary to prevent forming obstructions in the conduit and to avoid creating breaks or sharp angles in the conduit&#39;s interior surfaces. 
         [0005]    Construction workers frequently find it necessary to use many different sizes of conduit in any given construction project. In some instances, small conduit may be needed to carry relatively few wires through a narrow or tightly restricted area. In another application, however, an electrician may find that he needs to use a large diameter section of conduit to accommodate a large number of wires. In recognition of this need, commercial manufacturers provide electrical conduit in several standard sizes having various diameters and sidewall thicknesses. It is desirable that a pipe bender be versatile to accommodate the requirements of each type of conduit. 
         [0006]    Pipe benders having multiple pipe receiving channels for cutting pipes of different sizes have been described in many patents and non-patent literatures. Notwithstanding the prior art, the invention is neither taught nor rendered obvious thereby. 
       SUMMARY OF THE INVENTION 
       [0007]    It is therefore one object of the invention to provide a pipe bender comprising a first handle comprising a first yoke arm and a parallel second yoke arm; a second handle pivotably secured to the first handle and comprising a U-shaped member under the first and second yoke arms, the second handle including a first roller at one end, the first roller having a first pipe receiving groove, and a second roller at the other end, the second roller having a second pipe receiving groove; a support member having a longitudinal section of inverted T, the support member being threadedly fastened between the first yoke arm and the second yoke arm, the support member comprising a spring depressible detent on the bottom, and a plurality of markings on the top; and a slide member comprising a plurality of parallel arcuate pipe receiving channels of different arcuate perimeters on a lower surface, a lengthwise U-shaped trough on a central portion of a top surface, the U-shaped trough being adapted to receive a lower portion of the support member, a plurality of retaining holes on the bottom of the U-shaped trough, each retaining hole being aligned with one of the pipe receiving channels and one of the retaining holes being adapted to lockingly receive an end of the spring depressible detent for positioning; wherein the slide member is frictionally retained by the support member by threadedly fastening the slide member and the support member together so that the slide member is adapted to slide relative to the support member for aligning one of the pipe receiving channels with both the first and second pipe receiving grooves. 
         [0008]    The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a pipe bender according to a first preferred embodiment of the invention; 
           [0010]      FIG. 2  is an exploded view of  FIG. 1 ; 
           [0011]      FIG. 3  is a top view of the yoke arms, the slide member, and the support member of  FIG. 1 ; 
           [0012]      FIG. 4  is a front end view of  FIG. 3 ; 
           [0013]      FIGS. 5 and 6  are perspective view showing a pipe bending operation of the pipe bender according to a first preferred embodiment of the invention; 
           [0014]      FIG. 7  is an exploded view of a pipe bender according to a second preferred embodiment of the invention; 
           [0015]      FIG. 8  is a top view of the yoke arms and the sliding mechanism of  FIG. 7 ; 
           [0016]      FIG. 9  is a front end view of  FIG. 8 ; 
           [0017]      FIG. 10  is an exploded view of a pipe bender according to a third preferred embodiment of the invention; 
           [0018]      FIG. 11  is a top view of the yoke arms and the sliding mechanism of  FIG. 10 ; and 
           [0019]      FIG. 12  is a front end view of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring to  FIGS. 1 to 6 , a pipe bender in accordance with a first preferred embodiment of the invention comprises the following components as discussed in detail below. 
         [0021]    A bent first lever  10  and a bent second lever  20  are provided. The second lever  20  comprises a rear second handle  21  and the first lever  10  comprises a rear first handle  11 . The first lever  10  further comprises a first yoke arm  12   a  and a parallel second yoke arm  12   b  both extending forward from the first handle  11 . A forward portion of the second lever  20  extending from the second handle  21  passes an elongated gap between the first and second yoke arms  12   a  and  12   b.  A pivot joint  30  is driven through the first yoke arm  12   a,  the elongated gap between the first and second yoke arms  12   a  and  12   b,  and the second yoke arm  12   b  to pivotably join the first and second levers  10 ,  20  together. Two spaced through holes  121  are formed adjacent to a lower straight edge of each of the first and second yoke arm  12   a  and  12   b  respectively. The forward portion of the second lever  20  is formed as a U-shaped member  22  having a first roller  23  and a second roller  24  rotatably attached to both ends respectively. The first roller  23  has a concave, circumferential surface on an intermediate portion served as a first pipe receiving groove  231  and the second roller  24  has a concave, circumferential surface on an intermediate portion served as a second pipe receiving groove  241 . 
         [0022]    A sliding mechanism  40  comprises a support member  41  and a slide member  42 . The support member  41  has a longitudinal section of inverted T and comprises a cylindrical hole  414  open to the flat bottom surface, a torsion spring  412  disposed in the hole  414 , a steel ball  411  engaged with one end of the spring  412  proximate to the mouth of the hole  414 , a vertical part  415  having a rectangular longitudinal section, two L-shaped shoulders  413  between a lower horizontal portion of the support member  41  and the vertical part  415 , two spaced threaded holes  4151  on each side of the vertical part  415 , and a plurality of markings  16  indicating pipe sizes 3/16, ¼, 5/16, and ⅜ respectively. A plurality of threaded fasteners (e.g., screws)  122  can be driven through the through holes  121  into the threaded holes  4151  to fasten the support member  41  in the gap between the first and second yoke arms  12   a  and  12   b.    
         [0023]    The slide member  42  has a longitudinal section of about half disc. The slide member  42  comprises a plurality of (four are shown) parallel arcuate pipe receiving channels  421  of different arcuate perimeters formed on a lower surface, a lengthwise U-shaped trough  423  on a central portion of a top surface, a plurality of (four are shown) retaining holes  422  on the bottom of the trough  423 , each retaining hole  422  being aligned with the corresponding pipe receiving channel  421 , two sets of two threaded holes  426  on the top surface, each set of the two threaded holes  426  being between the trough  423  and either end of the pipe receiving channel  421 , two elongated mounting plates  424  each having two spaced through holes  4241 , and four threaded fasteners  425 . The trough  423  is complimentarily engaged with the lower horizontal portion of the support member  41  with the portion of the flat top surface of the slide member  42  other than the trough  423  being flush with the bottom of the L-shaped shoulders  413 . Each mounting plate  424  is placed on the joining portion of the flat top surface of the slide member  42  and the bottom of the L-shaped shoulders  413 . The threaded fasteners  425  are driven through the through holes  4241  into the threaded holes  426  to frictionally retain the slide member  42  with the steel ball  411  being pushed by the spring  412  to lockingly engage with one of the retaining holes  422 . Outer edge of the mounting plate  424  has two adjacent arcuate indents (not numbered) each corresponding to and longitudinally aligned with a portion of either arcuate end of the pipe receiving channel  421 . 
         [0024]    The markings  16  indicating 3/16, ¼, 5/16, and ⅜ represent sizes (i.e., outer diameter) of four different pipes respectively. That is, the sizes of the pipe receiving channels  421  increase from forward to rearward. Prior to a bending operation, an operator may pull the slide member  42  forward to remove it from the support member  41 . Alternatively, the operator may push the positioned slide member  42  toward the transverse part of the U-shaped member  22 . And in turn, the steel ball  411  clears the retaining hole  422 . The operator can stop the pushing if a desired pipe receiving channel  421  is transversely aligned with both the first pipe receiving groove  231  and the second pipe receiving groove  241 . The steel ball  411  thus lockingly engages with another retaining hole  422 . Preferably, the pushing will be stopped by the transverse part of the U-shaped member  22  for preventing the slide member  42  from disengaging from the support member  41 . Also, the steel ball  411  automatically lockingly engages with the rear retaining hole  422  when the pushing is stopped by the transverse part of the U-shaped member  22 . 
         [0025]    The operator may pivot the handles  11 ,  21  away from each other to open the mouth of the pipe bender (i.e., pivot the slide member  42  away from the U-shaped member  22 ). Next, place a straight pipe  50  across the first pipe receiving groove  231  and the second pipe receiving groove  241 . It is noted that the size (i.e., circular perimeter) of the pipe  50  corresponds to the desired pipe receiving channel  421  and the pipe  50  is in alignment therewith. Next, pivot the handle  11 ,  21  toward each other to decrease the mouth of the pipe bender in order to force the pipe  50  to bend around an arc from the first pipe receiving groove  231 , the desired pipe receiving channel  421 , and the second pipe receiving groove  241 . The operator may stop the bending if a desired curved shape of the pipe  50  has been obtained. An operation of pivoting the handles  11 ,  21  away from each other can open the mouth again so as to remove the bent pipe  50 . It is envisaged that four pipes  50  having outer diameters of 3/16 inch, ¼ inch, 5/16 inch, and ⅜ inch can be bent respectively by the invention. 
         [0026]    Referring to  FIGS. 7 ,  8  and  9 , a pipe bender in accordance with a second preferred embodiment of the invention is shown. The characteristics of the second preferred embodiment are substantially the same as that of the first preferred embodiment except the following: The sliding mechanism  40  comprises a slide member  44  which is an integral member. That is, the support member and the slide member of the first preferred embodiment are formed integrally. The slide member  44  does not have scale markings. An elongated slot  441  having both sides open is formed on a vertical part of the slide member  44 . Each threaded fastener  43  is implemented as a bolt  431  and a nut  432  combination. An operator may push or pull the slide member  44  so as to align a desired pipe receiving channel  421  with both the first pipe receiving groove  231  and the second pipe receiving groove  241 . Next, the operator may drive the bolts  431  through the through holes  121  of the second yoke arm  12   b,  the slot  441 , the through holes  121  of the first yoke arm  12   a,  and the nuts  432  to retain the slide member  44  which is allowed to frictionally move a distance no more than a maximum distance from either end of the slot  441  to the adjacent through holes  121  relative to the first handle  11  for aligning a desired pipe receiving channel  421  with both the first pipe receiving groove  231  and the second pipe receiving groove  241  prior to pipe bending operation. 
         [0027]    Referring to  FIGS. 10 ,  11 , and  12 , a pipe bender in accordance with a third preferred embodiment of the invention is shown. The characteristics of the third preferred embodiment are substantially the same as that of the first preferred embodiment except the following: The first yoke arm  12   a  and the second yoke arm  12   b  are engaged. A front bottom edge of each of the first yoke arm  12   a  and the second yoke arm  12   b  extends outward to form a rectangular extension  451 . The two extensions  451  are served as a rail  45 . Two bolts  452  each can be driven through the through hole  121  into a nut  453  so as to fasten the first and second yoke arms  12   a,    12   b  together. The sliding mechanism  40  comprises a slide member  46  with no scale markings. The slide member  46  has a longitudinal section of about half disc. The slide member  46  comprises a plurality of (four are shown) parallel arcuate pipe receiving channels  421  of different arcuate perimeters formed on a lower surface, a lengthwise U-shaped trough  461  on a central portion of a top surface, two sets of two threaded holes  464  on the top surface, each set of the two threaded holes  464  being between the trough  461  and either end of the pipe receiving channel  421 , two elongated mounting plates  462  each having two spaced through holes  4621 , and four threaded fasteners  463 . The trough  461  is complimentarily engaged with the rail  45  with the portion of the flat top surface of the slide member  46  other than the trough  461  being flush with the top of either extension  451 . Each mounting plate  462  is placed on the joining portion of the flat top surface of the slide member  46  and the top of the extension  451 . The threaded fasteners  463  are driven through the through holes  4621  into the threaded holes  464  to frictionally retain the slide member  46  which is allowed to frictionally move relative to the rail  45  for aligning a desired pipe receiving channel  421  with both the first pipe receiving groove  231  and the second pipe receiving groove  241  prior to pipe bending operation. 
         [0028]    While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.