Multiple-angle scissor blade

Abstract

The invention is directed to a pair of laparoscopic scissors, comprising a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation. The angle formed may be greater at the tip portion which continuously decreases over the length of the blade. The tip portion may have a first body thickness and the body portion may have a second body thickness different from the first body thickness. During the cutting operation, the blades progressively move over each other to provide a point contact along the cutting edges. The blades may be thickened in a number of locations and combinations including: (1) one blade could be thicker than the other to force the opposing blade to flex; (2) both blades could be thicker at the body portions to give more strength when cutting staples; (3) each blade could be thickened on one side or the other to stiffen certain locations; and (4) the tips of each blade could be thicker than the body portions to provide increased tension at the tips. In another aspect of the invention, a process of manufacturing the pair of scissors of the invention is disclosed, comprising the steps of form grinding the blades into a desired shape from a pre-hardened block of material, and sharpening the cutting edges of the blades. The blades may also be formed through other processes including wire EDM, laser cutting, waterjet cutting, machining, cast or metal injection molding, and other independent profile manufacturing processes. The manufacturing process of the invention is beneficial in that each profile can be accurately controlled, and the parts will be exact every time.

1 . A pair of laparoscopic scissors, comprising: 
 a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation.    
   
   
       2 . The pair of scissors of  claim 1 , wherein the angle formed is continuously changing over the length of the blade.  
   
   
       3 . The pair of scissors of  claim 1 , wherein the angle at the tip portion is greater than at the body portion.  
   
   
       4 . The pair of scissors of  claim 3 , wherein the angle progressively decreases from the tip portion to the body portion.  
   
   
       5 . The pair of scissors of  claim 1 , wherein the tip portion has a first body thickness and the body portion has a second body thickness.  
   
   
       6 . The pair of scissors of  claim 5 , further comprising a proximal portion having a third body thickness, wherein the second body thickness is thicker than the first and third body thicknesses.  
   
   
       7 . The pair of scissors of  claim 1 , wherein the tip portion is tapered.  
   
   
       8 . The pair of scissors of  claim 1 , wherein the cutting operation includes cutting at least one of a body tissue, a suture and a surgical staple.  
   
   
       9 . The pair of scissors of  claim 1 , wherein the blades progressively move over each other and provide a point contact along the cutting edges during the cutting operation.  
   
   
       10 . The pair of scissors of  claim 1 , wherein the first blade is thicker than the second blade forcing the second blade to flex during the cutting operation.  
   
   
       11 . The pair of scissors of  claim 5 , wherein the second body thickness is greater than or equal to the first body thickness to provide more tension when cutting a surgical staple.  
   
   
       12 . The pair of scissors of  claim 1 , wherein at least one of the inner surface and outer surface of at least one of the blades is thickened to stiffen that section.  
   
   
       13 . A process of manufacturing a pair of scissors having a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation, comprising the steps of: 
 form grinding the blades into a desired shape from a pre-hardened block of material; and    sharpening the cutting edges of the blades.    
   
   
       14 . The process of  claim 13 , wherein the angle formed is continuously changing over the length of the blade.  
   
   
       15 . The process of  claim 13 , wherein the angle at the tip portion is greater than at the body portion.  
   
   
       16 . The process of  claim 15 , wherein the angle progressively decreases from the tip portion to the body portion.  
   
   
       17 . The process of  claim 13 , wherein the tip portion has a first body thickness and the body portion has a second body thickness different from the first body thickness.  
   
   
       18 . A process of manufacturing a pair of scissors having a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation, comprising the steps of: 
 laser cutting the blades into a desired shape from a pre-hardened block of material; and    sharpening the cutting edges of the blades.    
   
   
       19 . The process of  claim 18 , wherein the angle formed is continuously changing over the length of the blade.  
   
   
       20 . The process of  claim 18 , wherein the angle at the tip portion is greater than at the body portion.  
   
   
       21 . The process of  claim 20 , wherein the angle progressively decreases from the tip portion to the body portion.  
   
   
       22 . The process of  claim 18 , wherein the tip portion has a first body thickness and the body portion has a second body thickness different from the first body thickness.  
   
   
       23 . A process of manufacturing a pair of scissors having a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation, comprising the steps of: 
 waterjet cutting the blades into a desired shape from a pre-hardened block of material; and    sharpening the cutting edges of the blades.    
   
   
       24 . The process of  claim 23 , wherein the angle formed is continuously changing over the length of the blade.  
   
   
       25 . The process of  claim 23 , wherein the angle at the tip portion is greater than at the body portion.  
   
   
       26 . The process of  claim 25 , wherein the angle progressively decreases from the tip portion to the body portion.  
   
   
       27 . The process of  claim 23 , wherein the tip portion has a first body thickness and the body portion has a second body thickness different from the first body thickness.  
   
   
       28 . A process of manufacturing a pair of scissors having a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation, comprising the steps of: 
 forming the blades into a desired shape by cast injection molding; and    sharpening the cutting edges of the blades.    
   
   
       29 . The process of  claim 28 , wherein the angle formed is continuously changing over the length of the blade.  
   
   
       30 . The process of  claim 28 , wherein the angle at the tip portion is greater than at the body portion.  
   
   
       31 . The process of  claim 30 , wherein the angle progressively decreases from the tip portion to the body portion.  
   
   
       32 . The process of  claim 28 , wherein the tip portion has a first body thickness and the body portion has a second body thickness different from the first body thickness.  
   
   
       33 . A process of manufacturing a pair of scissors having a pair of blades connected at a pivot, each of the blades having a length, a tip portion, a body portion, an outer surface, an inner surface and a cutting edge, the cutting edge forming an angle with the outer surface along the length of the blade such that tension during a cutting operation at the tip portion is about the same as tension at the body portion during the cutting operation, comprising the steps of: 
 forming the blades into a desired shape by metal injection molding; and    sharpening the cutting edges of the blades.    
   
   
       34 . The process of  claim 33 , wherein the angle formed is continuously changing over the length of the blade.  
   
   
       35 . The process of  claim 33 , wherein the angle at the tip portion is greater than at the body portion.  
   
   
       36 . The process of  claim 35 , wherein the angle progressively decreases from the tip portion to the body portion.  
   
   
       37 . The process of  claim 33 , wherein the tip portion has a first body thickness and the body portion has a second body thickness different from the first body thickness.