Double-bed circular knitting machine with device for correcting automatically variations of the distance between the needle cylinder and the dial

Abstract

A double-bed circular knitting machine with device for correcting automatically variations of the distance between the needle cylinder and the dial, comprising a supporting structure which supports, so that it can rotate about its own vertically oriented axis, a needle cylinder and a dial, which is arranged above and coaxially to the needle cylinder. Elements are provided for feeding threads to the needles, the machine comprising a device for correcting automatically the variations of the distance between the needle cylinder and the dial.

1 - 11 . (canceled) 
     
     
         12 . A double-bed circular knitting machine with device for correcting automatically variations of the distance between the needle cylinder and the dial, comprising a supporting structure which supports, so that it can rotate about its own vertically oriented axis, a needle cylinder and a dial which is arranged above and coaxially to said needle cylinder, said needle cylinder having, on its lateral surface, a plurality of axial slots, each of which accommodates slidingly a needle that can be actuated with an alternating motion along the corresponding axial slot to form knitting and said dial having a plurality of radial slots, each of which accommodates slidingly a needle that can be actuated with alternating motion along the corresponding radial slot to form knitting, means being provided for feeding threads to said needles, further comprising a device for correcting automatically the variations of the distance between the needle cylinder and the dial, comprising:
 means for detecting the tension of n threads fed to the needles of the machine to form knitting;   movement means, which are connected to said dial and can be actuated to actuate the movement of said dial along its axis with respect to said needle cylinder;   an actuation and control element of the electronic type, which is functionally connected to said tension detection means and is adapted to actuate said movement means as a function of the tension of the threads detected by said tension detection means.   
     
     
         13 . The machine according to  claim 12 , wherein said dial is supported, so that it can rotate about its own axis, by a central supporting element which lies around the axis of said dial and rests on a fixed supporting element which is integral with the supporting structure of the machine and is extended around said central supporting element; said movement means being interposed between said fixed supporting element and said central supporting element. 
     
     
         14 . The machine according to  claim 13 , wherein said fixed supporting element has a supporting ring which is extended coaxially to said dial and defines a supporting surface that is substantially perpendicular to the axis of said dial; said central supporting element having a flange in which one face is substantially perpendicular to the axis of said dial and faces said supporting surface in an upper region; said movement means comprising bushes which are accommodated in said supporting ring and are oriented so that their axis is parallel to the axis of said dial; said bushes being coupled, by means of a coupling of the screw-and-nut type, to pivots which are arranged so that their axes are parallel to the axis of said dial and are fixed to said central supporting element. 
     
     
         15 . The machine according to  claim 14 , wherein said bushes are mutually evenly spaced around the axis of said dial and have a portion that is provided as a gear, which meshes with a same ring gear which is arranged coaxially to said dial and is accommodated so that it can rotate about its own axis in said supporting ring; said movement means comprising a gearmotor, which is connected to a pinion that meshes with said ring gear and can be actuated for the simultaneous rotation of said bushes. 
     
     
         16 . The machine according to  claim 12 , wherein said means for detecting the tension of n threads comprise load cells which are arranged along the path of a corresponding thread to be controlled. 
     
     
         17 . The machine according to  claim 14 , wherein said central supporting element comprises an external element which is provided with said flange that faces said supporting ring and an internal element which is arranged inside said external element; said internal element and said external element being coaxial to said dial and said internal element supporting, so that it can rotate about its own axis, a main shaft which is connected coaxially, by means of its lower end, to said dial; said internal element and said external element being prevented from rotating about their own axis with respect to said supporting structure; said internal element being movable with respect to said external element along the axis of said dial. 
     
     
         18 . The machine according to  claim 17 , wherein it comprises means for manually adjusting the distance of said dial from said needle cylinder along the common axis, said manual adjustment means comprising: an actuation ring, which is arranged coaxially around said internal element and rests on the upper end of said external element, said actuation ring mating, by means of a coupling of the screw-and-nut type, with said internal element and being manually rotatable to lift or lower said internal element with respect to said external element. 
     
     
         19 . The machine according to  claim 18 , wherein said actuation ring is connected, by means of a chain or belt-type connection, to an actuation shaft, which is oriented so that its axis is parallel to the axis of said dial and is supported so that it can rotate about its own axis by said external element. 
     
     
         20 . The machine according to  claim 17 , further comprising means for detecting the axial movement of said internal element with respect to said external element. 
     
     
         21 . The machine according to  claim 12 , further comprising means for detecting the temperature of the dial, which are functionally connected to said actuation and control element. 
     
     
         22 . The machine according to  claim 12 , wherein values of the movement of said dial with respect to said needle cylinder, correlated to preset temperature values of the dial, are preset in said actuation and control element in order to actuate, by means of said actuation and control element, the movement of said dial with respect to said needle cylinder as a function of the temperature of the dial detected during machine startup.