Wire twisting device for use in a reinforcement binding machine

A wire twisting device for use in a reinforcement binding machine, comprising:

• a sleeve having a slot formed in a leading end portion of said sleeve;
• a shaft located in said sleeve and having a slot formed in a leading end portion of said shaft;
• a guide pin provided in the slot of the shaft;
• a pair of hook levers pivotally mounted in the slot of the sleeve, said hook levers including guide grooves engaged with the guide pin, thereby forming a hook lever opening and closing mechanism, whereby when the sleeve is driven to move forward to thereby rotate the two hook levers in their closing directions, a wire wound around the peripheries of reinforcements by a wire feed device can be gripped by and between the two hook levers and the sleeve and shaft can be subsequently driven or rotated integrally to thereby bind the wire;
• wherein said shaft (33) having said guide pin (41) is mounted on the leading end of a screw shaft (32) included in a feed screw mechanism that includes said screw shaft (32) and a sleeve nut (37) in such a manner that said shaft (33) can be rotated freely and can be freely slid in a given range, said shaft (33) also being energized in its extending direction by a spring (34), said sleeve (38) located in said shaft (33) is connected to said sleeve nut (37) and said sleeve and sleeve nut are kept from rotating in conjunction and simultaneously with said screw shaft by a rotation prevention mechanism (40,44), said screw shaft (32) can be rotationally driven to thereby move said sleeve nut, sleeve and hook levers back and forth, and when moving said sleeve nut, sleeve and hook levers forward said shaft (33) can be simultaneously and in conjunction with said screw shaft moved forward by a given distance to thereby delay the start of the closing operation of said hook levers (39), the rotation prevention mechanism permits said sleeve and sleeve nut to rotate in conjunction and simultaneously with said screw shaft after said wire is gripped by said hook levers to thereby bind said wire.

A wire twisting device for use in a reinforcement binding machine, comprising:

• a screw member;
• a sleeve member engaged with said screw member to move axially with respect to said screw member when said screw member is rotated with respect to said sleeve member;
• a shaft rotatably attached to said screw member and coupled for relative axial movement with respect to said screw member along a first predetermined distance;
• first and second hooks pivotally mounted to said sleeve member and engaged with said shaft for rotational movement between an opened position and a closed position;
• and
• a rotation prevention mechanism engageable with said sleeve member to prevent said sleeve member from rotating with to said screw member over said first predetermined distance,
• whereby rotation of said screw member advances said sleeve member and said shaft with respect to said screw member for said first predetermined distance, advances said sleeve with respect to said shaft and screw member over a second predetermined distance thereby rotating said hooks to said closed position, and disengages said rotation prevention mechanism from said sleeve member after said sleeve member advances with respect to said shaft and screw member over said second predetermined distance to permit said sleeve member and hooks to rotate and twist wire engaged by said hooks.

A method for twisting wire using a wire twisting device that includes a screw shaft, a shaft mounted adjacent to said screw shaft for axial movement relative to said screw shaft, a sleeve member mounted to said screw shaft for axial movement relative to said screw shaft, hook levers mounted to said sleeve and rotatable between an opened position and a closed position, and a wire feed device, said method comprising the steps of:

• feeding wire from the wire feed device around an object that is to be bound by wire;
• driving the screw shaft while preventing rotation of the sleeve member, thus advancing the shaft forward a given distance while holding the hook levers in the opened position;
• closing the hook levers about the wire after the shaft has traveled said given distance and as the screw shaft is continued to be driven;
• and
• rotating the hook levers and screw shaft as one, thus rotating the closed hook levers and twisting the wire.