Method and apparatus for forming carved groove of green tire

A method for producing an off-the-road radial tire, including the step of forming carved grooves each for a lug groove with a cutter on an outer circumferential surface of a green tire for the off-the-road radial tire before curing, in such a manner that each of said carved grooves is formed in an area from a middle portion of the outer circumferential surface to a shoulder portion on one side of the outer circumferential surface in a direction substantially along a central axis of the green tire and that each carved groove is given different predetermined depths, as each carved groove is being formed, in accordance with cut shape data for the green tire having an ideal shape, stored in a memory beforehand, said method comprising the steps of:

• moving a distance sensor along said area on said outer circumferential surface of the green tire to measure outer diameters of said area;
• revising said cut shape data in accordance with the measured diameters of said area;
• moving said cutter in accordance with the revised cut shape data for carving each of said carved grooves;
• introducing the green tire that has been formed with said carved grooves in a mold having an inner surface formed with projecting lug groove ribs, with the lug groove ribs fitted in the carved grooves of the introduced green tire, respectively;
• and
• applying inner pressure to the green tire within the mold to press the green tire against said inner surface of the mold to thereby deform the green tire into a shape of a true circle.

A method for forming a carved groove for a lug groove with a cutter on an outer circumferential surface of a green tire before curing, in such a manner that the carved groove is formed in an area from a middle portion of the outer circumferential surface to a shoulder portion on one side of the outer circumferential surface in a direction substantially along a central axis of the green tire and that the carved groove is given different predetermined depths along the length of the carved groove, as the carved groove is being formed, in accordance with cut shape data for the green tire having an ideal shape, stored in a memory beforehand, comprising:

• moving a distance sensor along said area on said outer circumferential surface of the green tire to measure outer diameters of said area, to thus detect a difference between a measured outer diameter of said area and an outer diameter of the green tire having an ideal shape, at plural points on said area;
• revising said cut shape data in accordance with said difference in diameter at said plural points on said area;
• and
• moving said cutter in accordance with the revised cut shape, thus carving the groove to have the different predetermined depths.

An apparatus for forming a carved groove for a lug groove on an outer circumferential surface of a green tire before curing, such that the carved groove is formed in an area from a middle portion of the outer circumferential surface to a shoulder portion on one side of the outer circumferential surface in a direction substantially along a central axis of the green tire and that the carved groove is given different required depths along the length of the carved groove, as the carved groove is being formed, in accordance with cut shape data for the green tire having an ideal shape, stored in a memory beforehand, comprising:

• a cutter for carving said outer circumferential surface of said green tire to form said carved groove;
• a cutter moving means for moving said cutter;
• a distance sensor for detecting distance from itself to said area of the outer circumferential surface of said green tire at plural points on said area, to thus detect a difference between a measured outer diameter of said area and an outer diameter of the green tire having an ideal shapes at each of said plural points;
• a sensor moving means for moving said distance sensor;
• and
• a control means including said memory storing said cut shape data and controlling said cutter moving means and said sensor means;
• said control means controlling said sensor moving means so that said distance sensor moves along said area to measure outer diameters of said area, revising said cut shape data stored beforehand on the basis of the measured outer diameters of said area to obtain revised cut shape data, controlling said cutter moving means in accordance with said revised cut shape data so that said cutter carves said outer circumferential surface of said green tire to form said carved groove.

An apparatus for forming a carved groove for a lug groove on an outer circumferential surface of a green tire before curing, such that the carved groove is formed in an area from a middle portion of the outer circumferential surface to a shoulder portion on one side of the outer circumferential surface in a direction substantially along a central axis of the green tire and that the carved groove is given different required depths, as the carved groove is being formed, in accordance with cut shape data for the green tire having an ideal shape, stored in a memory beforehand, comprising:

• a cutter for carving said outer circumferential surface of said green tire to form said carved groove;
• a cutter moving means for moving said cutter;
• a distance sensor for detecting distance from itself to said area of the outer circumferential surface of said green tire;
• a sensor moving means for moving said distance sensor;
• and
• a control means including said memory storing said cut shape data and controlling said cutter moving means and said sensor means;
• said control means controlling said sensor moving means so that said distance sensor moves along said area to measure outer diameters of said area, revising said cut shape data stored beforehand on the basis of the measured outer diameters of said area to obtain revised cut shape data, controlling said cutter moving means in accordance with said revised cut shape data so that said cutter carves said outer circumferential surface of said green tire to form said carved groove.