Portable machine designed for the automatic installation of wire ties on concrete reinforcing steel frames and operation thereof

A method for tying a wire tie about two crossed reinforcing steel sections comprising the steps of:

• placing the fixed upper stop piece of a wire tying machine above the crossing of the reinforcing steel sections to be tied;
• pivoting upward and forward two lower jaws to lock said jaws in a shut position and clamp the reinforcing steel sections against the fixed upper stop piece, said two lower jaws including a wire guide section having a spiraling channel which is automatically positioned around said reinforcing steel sections when said two lower jaws are locked in said shut position;
• activating a wire feeding device in response to said two lower jaws being locked in said shut position to force a preset length of wire tie inside the spiraling channel of said wire guide section;
• feeding the wire into said spiraling channel to guide the wire around the crossing of the reinforcing steel sections in the shape of an elongated coil;
• pulling the free end of the wire, coming out of the spiraling channel, with hinged tongs to tighten the coiled wire tie about the reinforcing steel sections and to introduce the free end of the wire being pulled inside one of the two channels of a rotating tongs;
• reversing the feed direction of the wire feeding device in response to said hinged tongs reaching the limit of its pulling motion to pull back the wire further tightening the wire around the reinforcing steel sections;
• activating a cutting edge to introduce the wire tie into the other channel of said rotating tongs and to cut the wire tie in response to said feeding device exerting a preset tensile stress on said wire;
• activating a clamping nut of the rotating tongs to slide axially and lock both ends of the wire tie which were previously introduced in said channels of said rotating tongs;
• rotating the rotating tongs around a fixed axis so as to twist the wire tie until the ends of the wire tie locked in the rotating tongs break off under the strain at the upper portion of the twist;
• reversing the direction of rotation of said rotating tongs to activate a breakaway type lug provided on said machine to interpose itself and cause the upper portion of the wire tie which may have remained in said rotating tongs to fall off;
• and
• resetting all the mechanisms of said tying machine at the end of the cycle for the next wire tie.