Device for pneumatic splicing of threads and yarns to be installed on textile machines

Device for pneumatic knotless splicing of ends of thread or yarn, to be installed on automatic spoolers of textile machines which are provided with an electronic computer control system, comprising a splicing chamber with a longitudinal slot for introduction of the ends of thread or yarn, a cover for temporary closure of the longitudinal slot of the splicing chamber, devices for pneumatic preparation of the ends of thread or yarn to be joined, which are disposed spaced from opposite lateral outlets of the splicing chamber, levers to draw the prepared ends of the thread or yarn from the preparation devices, in the direction of the splicing chamber, a control drum adapted to rotate around its own axis and containing a set of peripheral cam tracks to control the synchronised movements of the various movable units of the device, one of said cam tracks having a profile which increases progressively, a profile in steps, to control the drawing levers by means of a lever transmission, and a small, reversible electric stepper motor, which is connected to said drum, adapted to be actuated remotely by means of electrical pulses which are emitted by the said electronic system, characterised in that in its body, there is provided a cylindrical cavity, which is connected to a source of compressed air;

• in that in said cylindrical cavity, a piston rod is displaceable in both directions, the piston rod being actuated by means of an actuation lever, from a cam track of said drum;
• in that said track is divided at one section into two parallel branches, the first of which is used during rotation of the drum in a forward direction to displacement of the said rod in one direction, and the second branch is used during rotation of the drum in a return direction to displacement of the rod in the opposite direction, said cylindrical cavity with said piston rod constituting a slide valve, for controlling the intake of compressed air into the devices for preparation of the ends of thread or yarn to be joined, when said rod is actuated in order to be displaced in said one direction, and to control the intake of compressed air into the splicing chamber, when said rod is actuated in order to be displaced in said opposite direction, for execution of the pneumatic splicing of the two ends of thread or yarn;
• in that a specific amount of free play is provided in the lever transmission between said cam with an increasing profile and the drawing levers;
• and in that the drawing levers are provided with braking means, to keep them stopped in the displaced position, on completion of the forward rotation of the drum which is provided with the peripheral cam tracks.