The present invention concerns the manufacture of tires. More precisely, it refers to the manufacture of reinforcement armatures which are found in belted tires and, in general, so-called radial carcass tires.
By "manufacture of a tire", there is understood complete manufacture or else partial manufacture comprising at least the reinforcements produced by the process which will be explained below, the manufactured tire, for example, having no tread.
U.S. Pat. No. 4,952,259 discloses a proposal for manufacturing such reinforcements no longer in the form of semi-finished products which are incorporated subsequently upon the assembly of the tire, but directly on the tire during the course of manufacture, and this from a single cord. This proposal, which is based on the projecting of a cord in the manner of a whiplash, makes it possible to cover the current angles of so-called crown plies. However, it permits the obtaining of small angles only with difficulty.
The teaching of said patent does not make it possible either to produce a carcass ply in which the cord extends continuously from one bead of the tire to the other.
The object of the present invention is to propose a method of manufacture which makes it possible to produce all crown reinforcements from a single cord, namely the reinforcements which are found below the tread, whatever the angle which the cords of these reinforcements form with respect to the median plane perpendicular to the axis of rotation of the tire. The expression "cord" is to be understood in a very broad sense, covering a single cord proper or a cable or equivalent assembly, and this whatever the material constituting the cord.
In accordance with the invention, the method of manufacture of a tire, at least one reinforcement of which is formed from a single cord, successive lengths of which are deposited on a rigid support defining the shape of the inner surface of the tire and on which all or part of the tire is progressively built, is characterized by the fact that:
the cord necessary to constitute a length is removed by cord feed means permitting the feeding of a given amount of cord intended to constitute a length, PA1 each successive length is laid by at least one laying head which describes an orbital path surrounding the support, said path comprising a laying zone for the length of cord, said orbital path being contained in a plane which intersects the axis of rotation of the support by an adjustable angle, PA1 the said support is imparted a rotary movement the angular speed of which depends on the angular speed of the laying head, the laying angle, the number of laying heads, and the laying pitch of the cords. PA1 a frame, PA1 a displaceable rigid rotary core constituting said support, PA1 unwinding means for removing the given quantity of cord necessary to constitute a length, PA1 at least one laying head describing an orbital path around the core, said path comprising a laying zone and being contained within a plane which intersects the axis of rotation of the core along an adjustable angle, PA1 drive means for the laying head or heads and means for the driving in rotation of the core, the speed of said latter means depending on the drive speed of the laying head or heads, their number and said angle, and on the pitch.
Two basic embodiments will be explained with machines which comprise a laying head describing a circular orbital path. The laying head can, in addition to its basic function, by its movement cause the feeding of the cord necessary or else the feeding of the cord and the presentation of a length in front of the laying head are assured by parts independent of the head.
The invention extends also to machines for the manufacture of tire reinforcement machines having a laying head capable of describing any suitable path of encirclement of the core around a rigid core, permitting the employment of this process. This rigid core constitutes the rigid support which defines the inner surface of the tire.
In general, such machines comprise:
The following description, read in conjunction with the accompanying drawings, will make it possible better to understand the invention and to note all of its advantages.