Process and apparatus for building tyres for vehicle wheels

A process for building a tyre for vehicle wheels, comprising:

• forming at least one component of the tyre on a forming drum, wherein said component is formed by:
• supplying a continuous rubber-covered belt;
• cutting to size said continuous rubber-covered belt;
• and
• laying the continuous rubber-covered belt, cut to size, on the forming drum,
• wherein cutting to size comprises:
• carrying a knife formed by a first half-part and by a second half-part above the continuous rubber-covered belt, in proximity to a central portion of a cutting zone;
• lifting a lifting element placed below the continuous rubber-covered belt and at the cutting zone, until a portion of rubber-covered belt is lifted to form a bump placed at the cutting zone;
• lowering only the first half-part of the knife, making only the first half-part slide with respect to the second half-part, until only the first half-part obtains an opening in said rubber-covered belt, and inserting the first half-part in the aforesaid opening;
• jointly moving the first half-part and the second half-part along a cutting direction and in a cutting sense for generating a notch in the rubber-covered belt by the first half-part;
• lowering the second half-part, making the second half-part slide with respect to the first half-part until said second half-part is inserted in said notch;
• and
• symmetrically moving said first half-part and second half-part synchronously away from each other, in opposite senses and along said cutting direction;
• wherein the first half-part is lowered in an offset position with respect to a center of the rubber-covered belt to cut the rubber-covered belt on a tilted portion of the bump;
• wherein the tilted portion is tilted with respect to a horizontal plane.