Device for monitoring metal wires in a tire

A method of monitoring or checking a tire or a ply comprising reinforcing threads which are made of a magnetic material and laid parallel to one another at a given angle to the circumferential direction of the tire or to the longitudinal direction of the ply, using a checking device comprising:

• at least one induction member that induces a magnetic flux in the thread that is to be checked;
• a support made of magnetic material supporting the induction member, the support having the overall shape of a U and comprising first and second legs that conduct the magnetic flux into the thread for checking, the ends for conducting the magnetic flux into the thread for checking of the first and second legs defining a direction of alignment of the device;
• and
• at least one receiver member that receives the magnetic flux flowing through the thread for checking between the first and second legs;
• wherein the dimensions of the receiver member are arranged so as to measure only the magnetic flux flowing through the thread for checking when, in operation, the direction of alignment of the device is substantially parallel to the direction in which the thread for checking runs, and
• wherein the receiver member comprises a core around which is arranged a receiver coil that receives the magnetic flux flowing through the thread for checking, and is movable and comprises means for keeping the core in contact with a radially internal surface of the tire;
• and
• wherein each thread of the tire or of the ply is checked in succession independently of one another.

A method of monitoring or checking a tire or a ply comprising reinforcing threads which are made of a magnetic material and laid parallel to one another at a given angle to the circumferential direction of the tire or to the longitudinal direction of the ply, using a checking device comprising:

• at least one induction member that induces a magnetic flux in the thread that is to be checked;
• a support made of magnetic material supporting the induction member, the support having the overall shape of a U and comprising first and second legs that conduct the magnetic flux into the thread for checking, the ends for conducting the magnetic flux into the thread for checking of the first and second legs defining a direction of alignment of the device;
• at least one receiver member that receives the magnetic flux flowing through the thread for checking between the first and second legs;
• wherein the dimensions of the receiver member are arranged so as to measure only the magnetic flux flowing through the thread for checking when, in operation, the direction of alignment of the device is substantially parallel to the direction in which the thread being checked runs,
• the method comprising:
• moving the tire or the ply with respect to the checking device;
• measuring a signal representative of the condition of the or each thread as a function of the relative movement of the tire or of the ply with respect to the checking device;
• comparing the value of the measured signal against a reference value so that any defect with the or each thread can be detected;
• determining a geometric characteristic of the or each thread as a function of a variation in the measured signal;
• rotating the checking device about an axis substantially perpendicular to a surface, called the circumferential surface, of the tire or a surface, called the longitudinal surface, of the ply;
• measuring the variation in the signal as a function of the angle of rotation of the checking device;
• determining the angle formed by each thread with the circumferential direction of the tire or with the longitudinal direction of the ply;
• and
• checking each thread of the tire or of the ply in succession independently of one another.