German patent document 4,431,254 of Tennie describes such a wiring apparatus to which is fed a continuous length of wire from which the insulation has been stripped at spaced locations to reveal the conductor. The wire is fed downward through the wiring apparatus and then is deflected horizontally through a guide head so that a stripped leading end of the wire projects from a front face of this head. The leading wire end is gripped just back of the stripped leading end by the head which can be moved relative to a first terminal to insert the wire into this terminal to form the desired connection. Then the wire is advanced through the head until the next stripped portion is immediately downstream of the head which again grips the wire as a cutter severs the conductor in the center of the stripped portion and the length of wire from the supply is displaced out of the way, leaving a stripped conductor projecting from the back of the gripper head. This head is then displaced to engage this trailing end of the cut-off piece with a second terminal and the wire is released from the head. The wire-feed system is lowered to insert the leading end of the wire through the head and the cycle is repeated.
Obviously this piece of equipment is fairly complex and therefore quite prone to failure. The wire follows a nonstraight path through the device so it can jam or kink. Refeeding the wire through the guide eye after each cycle is problematic since it requires all the parts to realign themselves perfectly, otherwise the wire will jam and bring the production line down.
This system envisions turning the gripper head about a vertical axis so that the wire can be advanced in any horizontal direction, that is along a horizontal plane or a plane perpendicular to the normally vertical rotation axis of the gripper head. It is impossible, however, to insert the wire vertically or at an oblique angle between the vertical and horizontal. Thus even though the device may be mounted on a robot arm movable fully in x, y, and z directions, it cannot be used for certain types of installations.