Scissors assembly
View Patent ↗An endoscopic scissor instrument includes an elongate hollow member, an actuator that moves axially through the hollow member, and first and second scissor blades with respective cutting surfaces. At least one of the scissor blades is rotatably coupled to the hollow member adjacent its distal end. At least one of the scissor blades includes a base supporting a resilient leaf-spring portion that includes a respective cutting edge. The resilient leaf-spring portion extends from the base in a cantilevered arrangement and generates a spring force acting on the respective cutting edge such that in a loaded state there is an automatic preload force imparted between the cutting edges of the scissor blades to maintain a consistent and continuous mating force between the two opposed sharpened cutting edges preferably over the complete range of rotational movement of the scissor blades.
1. A set of scissors blades mounted relative to each other such that at least one of the scissors blades is movable relative to the other between open and closed positions, comprising:
a first scissors blade including a first feature with a first cutting edge; and
a second scissors blade including
a longitudinally extending rigid supporting base having a midline and a longitudinally extending lateral side offset relative to the midline, and
a resilient leaf-spring portion substantially thinner than the base and having a deflectable second cutting edge that extends along a length of the leaf-spring portion, the leaf-spring portion extending from the lateral side of the base in a laterally cantilevered arrangement such that the leaf-spring portion is laterally offset from the midline of the base, and
wherein as the at least one of the first and second scissors blades is moved relative to the other between open and closed positions,
(i) the first and second cutting edges are brought into contact with each other at a contact point in an interference plane, the contact point moving along the length of the leaf spring portion as the at least one of the first and second scissors blades are moved relative to the other, and the second cutting edge resiliently deflects against the first cutting edge at the contact point,
(ii) the leaf-spring portion generates a lateral spring force in a direction transverse to the interference plane and against the first feature of the first blade, and
(iii) the leaf-spring portion is flat when not subject to deflection.
2. A set of scissors blades according to claim 1 , wherein:
the leaf-spring portion is formed discrete from the base and coupled to the base along the length of the base.
3. A set of scissors blades according to claim 2 , wherein:
the leaf-spring portion is welded to the blade support.
4. A set of scissors blades according to claim 1 , wherein:
the first scissors blade includes a longitudinally extending rigid supporting base and an immediately laterally adjacent resilient, leaf-spring portion substantially thinner than the base, the leaf-spring portion forming the first feature, and the first cutting edge being deflectable, the leaf-spring portion extending laterally from the base of the first scissors blade in a laterally cantilevered arrangement along a length of the base, and longitudinally coextending with the base,
wherein the first and second cutting edges of the first and second scissors blades resiliently deflect about each other at the contact point.
5. A set of scissors blades according to claim 1 , wherein:
the spring force maintains an unchanging and continuous mating force between the first and second cutting edges as the at least one of the first and second scissors blades is moved relative to the other between the open and closed positions.
6. A set of scissors blades according to claim 1 , wherein:
the resilient leaf-spring portion has a thickness between 0.05 mm and 0.5 mm.
7. A set of scissors blades according to claim 1 , wherein:
the resilient leaf-spring portion has a tapered profile along its lengthwise dimension.
8. A set of scissors blades according to claim 1 , wherein:
the leaf-spring portion extends at both a bias angle and a relief angle, each defined relative to a rotational plane through which at least one of the first and second scissors blades is moved as at least one of the scissors blades is moved relative to the other between the open and closed positions.
9. A set of scissors blades mounted relative to each other such that at least one of the scissors blades is rotatable relative to the other between open and closed positions, comprising:
a first scissors blade including a first feature with a first cutting edge,
a second scissors blade including a longitudinally extending rigid supporting base and a laterally offset, resilient leaf-spring portion substantially thinner than the base,
the leaf-spring portion extending from and immediately laterally adjacent a lateral side of the base in a laterally cantilevered arrangement along a length of the base, and longitudinally extending with the base,
the leaf-spring portion having a second cutting edge that extends along a length of the leaf-spring portion, and
the leaf spring portion extending at a bias angle and a relief angle relative to a rotational plane through which one of the first and second scissors blades is rotational relative to the other to generate a lateral mating force between the first and second cutting edges at a contact point.
10. A set of scissors blades according to claim 9 , wherein:
the leaf-spring portion is formed discrete from the base and is coupled to the base along the length of the base.
11. A set of scissors blades according to claim 9 , wherein:
the leaf-spring portion is welded to the blade support.
12. A set of scissors blades according to claim 9 , wherein:
the first scissors blade includes a longitudinally extending rigid supporting base, and the first feature is a resilient leaf-spring portion substantially thinner than the base, the leaf-spring portion extending from a lateral side of the base of the first scissors blade in a laterally cantilevered arrangement along a length of the base.
13. A set of scissors blades mountable relative to each other such that at least one of the scissors blades is rotatable relative to the other in a scissoring action between open and closed positions, comprising:
a first scissors blade including a first feature with a first cutting edge; and
a second scissors blade including
a longitudinally extending rigid supporting base having a midline and a longitudinally extending lateral side offset relative to the midline, and
a resilient leaf-spring portion substantially thinner than the base and having a deflectable second cutting edge that extends along a length of the leaf-spring portion, the leaf-spring portion extending from the lateral side of the base in a laterally cantilevered arrangement such that the leaf-spring portion is laterally offset from the midline of the base, and extends from the lateral side of the base at both a bias angle and a relief angle relative to a rotational plane through which the mounted leaf-spring portion is rotatable, and
wherein as the at least one of the first and second scissors blades is moved relative to the other between open and closed positions,
(i) the first and second cutting edges are brought into contact with each other at a contact point in an interference plane, the contact point moving along the length of the leaf spring portion as the at least one of the first and second scissors blades are moved relative to the other, and the second cutting edge resiliently deflects against the first cutting edge at the contact point,
(ii) the bias and relief angles of the leaf-spring portion generate a lateral spring force in a direction transverse to the interference plane and against the first feature of the first blade, and
(iii) the leaf-spring portion is flat when not subject to deflection.
14. In a scissors device including first and second blade supports mounted relative to each other such that at least one of the blade supports is rotable relative to the other in a scissoring action between open and closed positions, the first blade support provided with a first feature having a first cutting edge, and the second blade support provided with a longitudinally extending rigid supporting base having a midline and a longitudinally extending lateral side offset relative to the midline, the scissors device comprising:
a resilient leaf-spring portion substantially thinner than the base and having a deflectable second cutting edge that extends along a length of the leaf-spring portion, the leaf-spring portion coupled to the second blade support to extend from the lateral side of the base in a laterally cantilevered arrangement such that the leaf-spring portion is laterally offset from the midline of the base, such that when at least one of the first and second scissors blade supports are rotated relative to the other between the open and closed positions,
(i) the first and the second cutting edges are brought into contact with each other at a contact point, the contact point moving along the length of the leaf spring portion as the first and second blade supports are rotated, and the second cutting edge resiliently deflects against the first cutting edge at the contact point,
(ii) the leaf-spring portion extends from the second blade support at both a bias angle and a relief angle relative to a rotational plane through which one of the first and second blade supports are rotatable, and thereby generates a lateral spring force in a direction transverse to the rotational plane, and
(iii) the laterally cantilevered leaf-spring portion is flat when not subject to deflection.
15. The scissors device according to claim 14 , wherein:
the leaf-spring portion is formed discrete from the base.
16. The scissors device according to claim 14 , wherein:
the leaf-spring portion is coupled to the base along the length of the base.
17. The scissors device according to claim 14 , wherein:
the first feature of the first blade comprises a second resilient leaf-spring portion and the first cutting edge is a sharpened deflectable cutting edge of the second leaf-first portion, the second leaf spring portion coupled to extend from a lateral side of the first blade in a laterally cantilevered arrangement.
18. The scissors device according to claim 17 , wherein:
the second leaf-spring portion is formed discrete from the first blade.
19. A scissors blade cutting feature for a scissors device which has first and second blade supports mounted relative to each other such that at least one of the blade supports is rotatable relative to the other in a scissoring action between open and closed positions, the first blade support provided with a first feature having a first cutting edge, and the second blade support provided with a longitudinally extending rigid supporting base having a midline and a longitudinally extending lateral side offset relative to the midline, the cutting feature comprising:
a resilient leaf-spring portion substantially thinner than the base and having a sharpened deflectable second cutting edge that extends along a length of the leaf-spring portion, the leaf-spring portion adapted to be coupled to the second blade support to extend from the lateral side of the base in a laterally cantilevered arrangement such that the leaf-spring portion is laterally offset from the midline of the base, such that when at least one of the first and second blade supports are rotated relative to the other within a rotational plane between the open and closed positions,
(i) the first and the second cutting edges are brought into contact with each other at a contact point, and the second cutting edge is adapted to resiliently deflect against the first cutting edge at the contact point, with the contact point moving along the length of the leaf spring portion as the first and second blade supports are rotated, and
(ii) the leaf-spring portion generates a lateral spring force in a direction transverse to the rotational plane, and
(iii) the leaf-spring portion is flat when not subject to deflection.
20. The scissors blade cutting feature of claim 19 , wherein:
the leaf-spring portion extends at both a bias angle and a longitudinal relief angle relative to the rotational plane through which the one of the first and second blade support are rotatable.
21. The scissors blade cutting feature of claim 19 , wherein:
the leaf-spring portion is formed discrete from the base.
22. The scissors blade cutting feature of claim 19 , wherein:
the leaf-spring portion is coupled to the base along the length of the base.
23. The scissors blade cutting feature of claim 19 , wherein:
the first feature of the first blade comprises a second resilient leaf-spring portion and the first cutting edge is a sharpened deflectable cutting edge of the second leaf-first portion, the second leaf spring portion coupled to extend from a lateral side of the first blade in a laterally cantilevered arrangement.
24. The scissors blade cutting feature of claim 23 , wherein:
the second leaf-spring portion is formed discrete from the first blade.