Abstract:
A spring-biased cutting tool for plastic pipes. The tool includes two elongated members pivotally connected to each other in a scissors-like manner. Each elongated member has a handle portion and a jaw portion with one jaw portion including a knife blade and the other an anvil. To assemble the elongated members, one of them is provided with a central aperture or hole through which the other member can be passed to form the scissors-like shape. A leaf spring in then clipped at one end over an edge portion of the aperture and extends across to abut against the other elongated member and bias the handles of the tool apart and the jaws of the tool is open to receive a pipe to be cut.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of cutting tools for plastic pipes and more particularly to the field of manually operated cutting tools with handles that are spring biased apart to open the jaws of the tool. 
     2. Discussion of the Background 
     Cutting tools for plastic pipes are widely used throughout the world and are an essential piece of equipment for virtually anyone who works with plastic pipes. In the typical design, two elongated members are pivotally connected together in a scissors-like manner. In one popular arrangement such as in applicants&#39; U.S. Pat. No. 4,336,652 and D266,736, the handles of the tool are manually manipulated to separate them and open the jaws of the tool to receive the plastic pipe to be cut. In doing so, the handles can be rubbed along the user&#39;s leg to separate them and open the tool&#39;s jaws or the user can extend his or her fingers to separate the handles. Once opened with the pipe received between the jaws of the tool, the handles can then be squeezed together to drive the edge of the knife blade on one of the jaws into the pipe. At the same time, the tool is normally swung relative to the pipe. In doing so, the knife edge continues to be driven into the pipe until the pipe is eventually severed. 
     Such cutting tools can be provided with a spring or springs to bias the handles apart and the jaws into an open position to receive the pipe. When a number of cuts are to be done, many users find it more efficient to have a spring-biased tool rather than one whose handles must be manually opened for each cut. Adding a spring, however, increases the complexity and cost to manufacture and assemble the tool. As for example in U.S. Pat. No. 191,416 to Fetter, U.S. Pat. No. 217,583 to Cannon, U.S. Pat. No. 392,717 to Carson, U.S. Pat. No. 929,749 to Bishop, U.S. Pat. No. 1,261,284 to Phelps, U.S. Pat. No. 1,757,173 to Dingman, U.S. Pat. No. 1,802,903 to Bryant, U.S. Pat. No. 2,006,133 to Fowler, U.S. Pat. No. 3,257,723 to Cercone, and U.S. Pat. No. 4,073,059 to Wallace, rivets or screws are necessary to secure the spring to one of the handles. In other patents, the spring must be welded to the tool as in U.S. Pat. No. 1,702,801 to Smith and U.S. Pat. No. 5,058,277 to Kishimoto or special posts must be designed into the tool itself to secure the spring in place as in U.S. Pat. No. 352,560 to Neff, U.S. Pat. No. 3,562,908 to Rogers, U.S. Pat. No. 5,203,084 to Kuo, U.S. Pat. No. 5,860,568 to Mallalieu, and U.S. Pat. No. 5,946,752 to Parrish. Still others require that even more elaborate structure be designed into the tool as in U.S. Pat. No. 4,400,876 to Brown and U.S. Pat. No. 4,633,587 to Harrison or special structure be added to both handles to support the spring as in U.S. Pat. No. 5,930,900 to Chang and British Patent No. 1,196,023 to Rogers. In many cases, such additional complexity and cost to the manufacture and assembly of the tool prices it out of the market. 
     In contrast, the spring-biased cutting tool of the present invention uses a simple and inexpensive leaf spring with a curved lip on one end that easily clips over a conveniently positioned edge on the tool. In this manner, the spring-biased tool of the present invention can be manufactured and assembled at a cost that is very competitive in the market. 
     SUMMARY OF THE INVENTION 
     This invention involves a spring-biased cutting tool for plastic pipes. The tool includes two elongated members pivotally connected to each other in a scissors-like manner. Each elongated member has a handle portion and a jaw portion with one jaw portion including a knife blade and the other an anvil. To assemble the elongated members, one of them is provided with a central aperture or hole through which the other member can be passed to form the scissors-like shape. 
     In the preferred embodiments, the aperture in the one elongated member is defined by a plurality of edges wherein one edge portion is designed to support an end of a leaf spring. The leaf spring then extends across to abut against the other elongated member of the tool and bias the handles of the tool apart to open the jaws. The attached end of the leaf spring has a curve in it forming a lip. To assemble the spring on the one elongated member, the curved lip is flexed open and pinches the edge portion of the aperture between it and a section of the leaf spring immediately adjacent the lip. In this manner, the leaf spring can be easily and quickly clipped over the edge portion of the aperture on the one elongated member of the tool. The aperture edge portion is preferably pinched between the extreme end or edge of the curved lip and a section of the leaf spring immediately adjacent the lip. The force of the pinch including the physical, frictional engagement of the lip with the aperture edge portion securely keeps the leaf spring in place. In a preferred embodiment, a retaining protuberance or step is added to the structure of the edge portion of the aperture to further ensure that the leaf spring cannot be easily disengage from the tool. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the cutting tool of the present invention. 
     FIG. 2 is a side elevational view of the tool with the handle portions of the tool separated by the force of the spring to open the jaws of the tool to receive the pipe to be cut. 
     FIG. 3 is a side elevational view of the tool with its handles squeezed completely together to cut through the pipe. 
     FIG. 4 is a top plan view taken along line  44  of FIG.  3 . 
     FIG. 5 is a top plan view of the elongated member which has the anvil in it and the central aperture through it to receive the other elongated member. FIG. 5 is taken along line  5 — 5  of FIG.  6 . 
     FIG. 6 is a view of the two, elongated members of the tool shown in a pre-assembly position with the one member aligned to be received in the central aperture in the other member. 
     FIG. 7 is an enlarged view taken along line  7 — 7  of FIG. 5 showing one manner in which the leaf spring can be clipped over and retained on one edge portion of the aperture. 
     FIG. 8 shows the leaf spring as positioned just before its lip is flexed open to pinch the edge portion of the aperture and assume the clipped on position of FIG.  7 . 
     FIG. 9 illustrates the preferred design of the edge portion of the aperture in which the edge portion is provided with a protuberance or step to aid in retaining the leaf spring on the aperture edge portion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in the perspective view of FIG. 1, the cutting tool  1  of the present invention includes two elongated members  3  and  5 . The elongated members  3  and  5  are connected at  7  in a scissors-like manner for pivotal movement relative to each other about the axis  9 . The axis  9  as shown is substantially intermediate the respective ends of the members  3  and  5 . Each elongated member  3  and  5  has a jaw portion  3 ′ and  5 ′ and a handle portion  3 ″ and  5 ″. The jaw portion  5 ′ of the elongated member  5  (see also FIG. 2) has a knife blade  11  at one end thereof and the opposing jaw portion  3 ′ of the elongated member  3  has a curved anvil  13  at the end thereof. 
     In operation, the pipe  2  to be cut (see FIG. 2) is first received between the opened jaw portions  3 ′ and  5 ′. The handle portions  3 ″ and  5 ″ are then manually squeezed together as the cutting tool  1  is preferably swung relative to the pipe  2  until the pipe  2  is severed (see FIG.  3 ). In doing so as illustrated in FIG. 1-4, the cutting edge  11 ′ of the knife blade  11  is received in the slot  13 ′ (see also FIG. 5) of the anvil  13 . Additionally, as the handle portions  3 ″ and  5 ″ are squeezed together from the position of FIG. 2 to the position of FIG. 3, the return spring  15  (see FIGS. 1-3) will be compressed from the relaxed position of FIG. 2 to the compressed position of FIG.  3 . Consequently, upon releasing the pressure on the handle portions  3 ″ and  5 ″ in FIG. 3, the compressed return spring  15  will move the handle portions  3 ″ and  5 ″ apart to the position of FIG. 2 to again open and separate the knife blade  11  and anvil  13  to receive another pipe section  2  to be cut. 
     In the preferred embodiments, the return spring  15  is a leaf spring. Additionally, in the preferred embodiments, the parts of the cutting tool  1  including the elongated members  3  and  5  and the leaf spring  15  have been specifically designed to be easily and cost effectively manufactured and assembled. In this regard as illustrated in FIG. 5, the elongated member  3  is molded with a central aperture  21  extending through it. During assembly, the other elongated member  5  can be positioned as in FIG.  6  and then moved as indicated through the aperture  21  to the relative positioning of FIG. 1, where the two elongated members  3  and  5  can then be secured together at  7  to form the scissors-like shape of the cutting tool  1 . 
     The leaf spring  15  can be mounted on the elongated member  3  either before the members  3  and  5  are assembled as in FIG. 6 or after the members  3  and  5  are secured together In both cases, the leaf spring  15  only needs be clipped over the edge portion  25  (see FIGS.  5  and  7 - 8 ) that defines in part the aperture  21  of FIG.  5 . That is, the aperture  21  in FIG. 5 is defined by a plurality of edges including the edge portion  25 . This edge portion  25  (see FIG. 7 which is a view taken along line  7 — 7  of FIG. 5) is specially molded so the leaf spring  15  can be easily and quickly clipped over it. 
     More specifically, the leaf spring  15  has first and second end portions  15 ′ and  151 ″ (see FIGS.  2  and  7 - 8 ). The end portion  15 ′ as best seen in FIGS. 7 and 8 has a relatively flat section  27  and a curved lip  29  with an end or edge  31 . The curved lip or rolled eye  29  in this regard is dimensioned to clip over the edge portion  25  of the aperture  21  in a pinching manner. In assembling the leaf spring on the edge portion  25 , the curved lip  29  of FIG. 8 flexes or expands outwardly to receive the tip or end  25 ′ of the edge portion  25  between the lip edge  31  and the relatively flat section  27  of the leaf spring  15  (see FIGS.  7  and  8 ). In this manner, the curved lip  29  is flexed to pinch the edge portion  25  (see FIG. 7) between the lip edge  31  and the leaf spring section  27  to thereby retain the leaf spring  15  on the edge portion  25 . To aid in the flexing or wedging open of the curved lip  29  during assembly, the end  25 ′ of the edge portion  25  as shown in FIGS. 7 and 8 is preferably tapered. This tapered end  25 ′ preferably has a relatively flat, inclined surface  35  (see FIG. 8) against which the flat section  27  of the leaf spring  15  abuts once the leaf spring  15  is clipped and retained on the edge portion  25  as shown in FIG.  7 . 
     In this retained position as best illustrated in FIGS. 1 and 2, the second end portion  15 ″ of the leaf spring  15  is supported to extend toward and abut against the inner or upper surface (see FIGS. 1 and 2) of the opposing handle portion  5 ′ of the elongated member  5  to bias the two handle portions  3 ″ and  5 ″ apart into the open position of FIG.  1 . In this relaxed position of FIGS. 1 and 2, the main body of the leaf spring  15  between the end portions  15 ′ and  15 ″ assumes essentially a C-shape as shown. Thereafter, when the handle portions  3 ″ and  5 ″ are squeezed together as discussed above, the leaf spring  15  will assume the substantially flatten and compressed shape of FIG.  3 . The free end portion  15 ″ of the leaf spring  15  in this regard has a slight curve or roll as shown. In this manner, the end portion  15 ″ will more easily slide along the handle portion  5 ″ of the elongated member  5 , both when the handle portions  3 ″ and  5 ″ are manually squeezed together and when the compressed spring  15  in FIG. 3 returns the elongated members  3  and  5  of the cutting tool  1  to the open position of FIGS. 1 and 2. 
     In the embodiment of FIG. 7, the lip edge  31  of the leaf spring  15  preferably frictionally engages the surface  37  of the edge portion  25 . The frictionally engaged lip edge  31  will then help to retain the leaf spring  15  on the edge portion  25  by digging into the surface  37  in response to forces tending to dislodge the curved lip  29  from the position of FIG. 7 on the edge portion  25 . Additionally, the lip edge  31  will physically drag along the surface  37  should a strong enough force be applied to the leaf spring  15  to overcome the pinching force on the edge portion  25  between the lip edge  31  and the opposing, leaf spring section  27 . 
     To more securely clip the leaf spring  15  in place, the edge portion  25  can be modified as in the preferred embodiment of FIG. 9 to include a second surface  39  intersecting the first surface  37  to form a retaining protuberance or step. In this modified design of FIG. 9, the lip end or edge  31  of the leaf spring  15  is then positioned during assembly substantially at the intersection of the two surfaces  37  and  39 . Consequently, any force on the leaf spring  15  tending to dislodge the leaf spring  15  from the edge portion  25  will cause the lip edge  31  to abut against the surface  39  of the step or stop and effectively resist any such dislodgement. It is noted this retaining step or stop where surfaces  37  and  39  intersect at approximately 90 degrees acts in addition to the already existing pinching force being applied on the edge portion  25  between the lip edge  31  and the opposing, leaf spring section  27 . 
     While several embodiments of the present invention have been shown and described in detail, it to be understood that various changes and modifications could be made without departing form the scope of the invention.