Patent Publication Number: US-11047075-B2

Title: Method for the production of portions of manufacture by means of a circular knitting machine with needle cylinder that can be actuated with an alternating rotary motion about its own axis

Description:
The present invention relates to a method for the production of portions of manufacture by means of a circular knitting machine with needle cylinder that can be actuated with an alternating rotary motion about its own axis. 
     As is known, circular hosiery knitting machines comprise a needle cylinder which is arranged so that its axis is vertical and has, on its lateral surface, a plurality of axial slots inside each of which a needle is accommodated which can slide along the corresponding axial slot. Each needle is provided with a heel that protrudes radially from the lateral surface of the needle cylinder and around the needle cylinder there are needle actuation cams which define paths with which the heels of the needles engage. Laterally to the needle cylinder there is at least one feed or drop at which yarn fingers are arranged which have the function of dispensing one or more yarns to the needles. 
     The paths defined by the needle actuation cams are shaped so as to cause, as a consequence of the actuation of the needle cylinder with a rotary motion about its own axis with respect to the needle actuation cams and to the drop or feed, the movement of the needles along the corresponding axial slot in order to grip the yarn or yarns dispensed by the yarn fingers at the feed or drop and the forming of new loops of knitting on the part of the needles. 
     Inside each axial slot of the needle cylinder, below each needle, generally there is a selector and optionally a sub-needle, which is interposed between the selector and the needle. The selector cooperates with one or more selection devices, which face laterally the needle cylinder and have the task of selecting the needles of the machine that must be moved to knit, i.e., to pick up the yarn or yarns, at a given feed or drop. The selectors and often also the sub-needles are provided with corresponding heels which protrude radially from the lateral surface of the needle cylinder and can engage corresponding actuation cams arranged around the needle cylinder in order to cause the movement of the selectors and/or of the sub-needles along the axial slots of the needle cylinder in which they are arranged. The movement of the selectors and/or of the sub-needles has the effect of causing or allowing the movement of the corresponding overlying needle and this movement can be used to actuate directly the needle or to vary the path followed by the heel of the needle and defined by the needle actuation cams. 
     In some types of circular hosiery knitting machine, the needle cylinder can be actuated with a rotary motion about its own axis in the two directions of rotation with respect to the actuation cams and the feeds or drops in order to perform, particular kinds of knitting which indeed require the actuation of the needle cylinder with an alternating rotary motion about its own axis. One of these kinds of knitting is constituted by the execution of the region of the heel and of the region of the toe of hosiery in circular hosiery knitting machines. A similar knitting is performed on circular knitting machines to provide pouches or to obtain contoured portions on the manufactures. 
     In these machines, the set of the actuation cams of the needles and/or of the selectors and/or of the sub-needles defines paths which are capable of actuating the needles to form knitting at at least one feed or drop of the machine both in one direction of rotation of the needle cylinder and in the opposite direction. 
     Generally, for types of knitting that require an actuation with an alternating rotary motion of the needle cylinder about its own axis with respect to the actuation cams of the needles and the actuation cams of the selectors and/or sub-needles, a feed or drop of the machine is used and the needle actuation cams comprise a central cam, which is triangular and arranged at the feed, and two knockover cams, which are arranged on mutually opposite sides with respect to the feed, i.e., with respect to the central cam. 
     For kinds of knitting performed by means of the alternating rotation of the needle cylinder about its own axis, a reduced number of needles is generally used, said needles being arranged in the axial slots formed on the lateral surface of the needle cylinder in a limited sector of the needle cylinder. 
     The limitation of the number of needles used for these kinds of knitting is dictated by production-related requirements, as in the case of the heel or toe of hosiery, and by operating requirements of the machine, since in order to be able to reverse the direction of rotation of the needle cylinder the needles must have their heel in very precise regions of the paths defined by the needle actuation cams, i.e., regions that allow to reverse the motion of the needles with respect to the cams without causing damage to the machine or knitting defects. 
     More particularly, considering the operation of a traditional machine during the execution of the heel of a hosiery item, the knitting is produced by using a group of contiguous needles and by actuating the needle cylinder with an alternating rotary motion about its own axis, i.e., producing in each instance one row of knitting by rotating the needle cylinder clockwise and one row of knitting by rotating the needle cylinder counterclockwise. The yarn, which is fed to the group of needles at the feed or drop assigned to this knitting, upon reversal of the motion of the needle cylinder is taken up by means of adapted devices so that said yarn turns around the last needle that is knitting, i.e., that has taken the yarn, and is ready for the next row of knitting. In order to create the pouch of the heel, the number of needles of the needle group that are moved to knit at the assigned feed is decreased progressively by excluding from knitting, at each reversal of the motion of the needle cylinder, at least one needle located at the end of the group of needles that has knitted to form the last row of knitting and by then progressively returning to knit, in reverse sequence, in each instance, the needles that previously had been excluded from knitting. 
     The exclusion from knitting and return to knitting of the needles is performed, in many types of machine, by means of the selection devices which, by means of the selectors and/or sub-needles, act on the needles so as to vary the path of the actuation cams with which the heel of the needles engages. Generally, in the set of needle actuation cams there is a path that is lower than the other paths or a path that is higher than the other paths and, by virtue of the action of the selection devices, is engaged by the heel of the needles to be excluded from knitting so that the corresponding needles are located with their tip too low or too high to be able to take up the yarn dispensed at the feed being used. 
     In many machines that use selection devices of the mechanical or electronic type, selection of the needles that must be moved to knit during the rotation of the needle cylinder in one direction is performed during the rotation of the needle cylinder in the directly preceding opposite direction. More particularly, during the rotation of the needle cylinder in one direction, after a needle has formed a new loop of knitting by knocking over the previously formed loop of knitting, i.e., directly downstream or even at the knockover cam used for that direction of rotation, if said needle must be moved to knit during the subsequent rotation of the needle cylinder in the opposite direction, it is selected by the selection device and moved to the tuck-stitch position. If instead said needle must be excluded from knitting during the subsequent rotation of the needle cylinder in the opposite direction, it is retained or moved with its heel in the lower path. 
     In machines of this kind there is a limit to the number of needles that can be used during knitting with an alternating rotation of the needle cylinder, since the number of needles that are always excluded from knitting must be adequately greater, depending on the type of machine and on its actuation system, than the number of needles that lies within the angular distance that exists between the end of the rising ramp, depending on the direction of rotation of the needle cylinder, of the two cams that cause the lifting of the needles in the tuck-stitch position, located on mutually opposite sides with respect to the feed used in knitting with an alternating rotary motion of the needle cylinder. The cams that cause the rise of the needles in the tuck-stitch position can belong to the set of needle actuation cams or to the set of the actuation cams of the selectors and/or sub-needles. 
     One example of a machine of this kind is shown in  FIGS. 18 and 19 , which refer to a machine with a needle cylinder on the lateral surface of which there is a plurality of axial slots, each of which accommodates internally a needle  1 - 144  and, below said needle, a selector  145 , as well as a sub-needle  146 , between the selector  145  and the needle  1 - 144 .  FIGS. 18 and 19  are schematic flat projection views of the needle actuation cams  150 , of the selector actuation cams  160  and of the sub-needle actuation cams  170  of a circular hosiery knitting machine. Laterally to the flat projection view of the cams  150 ,  160 ,  170 , in  FIGS. 18 and 19 , there is a needle  1 - 144 , a sub-needle  146  and a selector  145 , which are rotated through 90° with respect to the actual position and are accommodated in a same axial groove of the needle cylinder. In these figures, the reference numeral  152  designates the central cam, the reference numerals  153  and  154  designate the knockover cams, the reference numerals  201  and  202  designate the direction of motion of the needles  1 - 144 , or of the needle cylinder, with respect to the needle actuation cams  150  and the cams  160 ,  170 , and the reference numeral  180  designates the feed or drop at which the yarn fingers  181  are arranged. The needles are identified by progressive numerals from  1  to  144 , but only some needles required for the comprehension of the described problem have been numbered. The heels  151  of the needles selected to knit at the feed  180  in the subsequent reverse rotary motion are shown in black, while the heels  151  of the needles that must remain excluded from knitting are shown in white. The heels  161  of the selectors  145  and the heels  171  of the sub-needles  146  have been drawn with the same criterion. The other elements of the machine shown in these figures will be described hereinafter. The two  FIGS. 18 and 19  show the situation at the end of a motion in one direction  201  and at the end of the motion in the opposite direction  202  of the needle cylinder or of the needles with respect to the needle actuation cams  150  and the cams  160 ,  170 . As can be seen, the exclusion from knitting of a limited number of needles, twenty-four needles in the illustrated case, does not allow to work correctly, since completion of needle selection, which is performed by means of the selection device  191  directly downstream of the knockover cam  153  in  FIG. 18  and by means of the selection device  192  directly downstream of, or better still at, the knockover cam  154  in  FIG. 19  would move the first needle selected to be moved to knit in the subsequent reverse motion (the needle  13  in  FIG. 18  and the needle  132  in  FIG. 19 ) to again take up the yarn at the feed  180 , producing a knitting error in both directions of rotation. Furthermore, some needles would enter between the knockover cams  153  and  154  incorrectly, causing further knitting errors upon motion reversal. 
     In machines that perform selection of the needles that must be moved to knit at the feed being considered during the rotation of the needle cylinder in one direction while the needle cylinder is performing the rotation in the same direction, this problem of the limitation of the needles that can be used in the alternating rotary motion of the needle cylinder does not exist and therefore with these machines there is greater versatility in use as regards the kinds of knitting that require an alternating rotation of the needle cylinder about its own axis. 
     In view of this prior art, the need is felt to be able to produce portions of manufactures produced by actuating the needle cylinder with an alternating rotary motion about its own axis with rows of knitting that have a large number of stitches, in an extreme case equal to the number of needles of the machine, even with circular machines that perform selection of the needles to be moved to knit during the rotary motion of the needle cylinder in one direction, during the rotation of the needle cylinder in the immediately preceding opposite direction. 
     The aim of the present invention is to meet this requirement, by devising a method for the production of portions of manufacture by means of a circular knitting machine with needle cylinder that can be actuated with an alternating rotary motion about its own axis that allows to use a large number of needles, in an extreme case equal to the number of needles of the machine, even in machines of this kind. 
     Within this aim, an object of the invention is to provide a method that can be performed without requiring substantial modifications of machines that are already commercially available. 
     Another object of the invention is to propose a method that does not penalize excessively the production potential of the machines. 
     This aim, as well as these and other objects which will become better apparent hereinafter, are achieved by a method for the production of portions of manufacture by means of a circular knitting machine with needle cylinder that can be actuated with an alternating rotary motion about its own axis, wherein said needle cylinder has, on its lateral surface, a plurality of axial slots, in each of which a needle is accommodated, a drop or feed being arranged around said needle cylinder and at least one yarn being dispensed thereat which can be engaged by the needles in order to form knitting, means being provided for the actuation of the needles along the corresponding axial slot in order to grip the yarn at said drop or feed and form loops of knitting, selection devices being provided for selecting the needles to be moved to knit at said at least one feed, said selection devices comprising a first selection device and a second selection device, which are arranged on mutually opposite sides with respect to said feed, said selection devices being adapted to select the needles downstream of said feed depending on the direction of rotation of the needle cylinder about its own axis, characterized in that it comprises the following steps:
         identifying a group of contiguous needles in the needle cylinder;   dividing said group of needles into two contiguous needle subgroups, respectively a first needle subgroup and a second needle subgroup;   moving to knit at said feed a needle subgroup of said two needle subgroups during the rotation of the needle cylinder in one direction and in the subsequent rotation in the opposite direction to form two partial rows of knitting in succession;   moving to knit at said feed the other needle subgroup of said two needle subgroups during the rotation of the needle cylinder in one direction of rotation and in the subsequent rotation in the opposite direction to form two partial rows of knitting in succession;   proceeding in this manner by alternating, every two partial rows of knitting, the needle subgroup that is moved to knit at said feed for a preset number of partial rows of knitting;       

     at least one needle of a needle subgroup of said needle subgroups, located proximate to the other needle subgroup, being moved to knit in the forming of at least one of the two partial rows of knitting formed in each instance by the other needle subgroup for the interconnection of the partial rows of knitting formed by a needle subgroup with the partial rows of knitting formed by the other needle subgroup. 
     Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of the method according to the invention, illustrated by way of nonlimiting example in the accompanying drawings, wherein: 
       FIGS. 18 and 19  are schematic flat projection views of the actuation cams of the needles, of the sub-needles and of the selectors and of the heels of the needles, of the sub-needles and of the selectors in the production of portions of manufacture with a method of the traditional type which uses the possibility of alternating rotary motion of the needle cylinder about its own axis; 
    
    
     
         FIGS. 1 to 14  are schematic flat projection views of the actuation cams of the needles, of the sub-needles and of the selectors and of the heels of the needles, of the sub-needles and of the selectors in the execution of the various steps of the method according to the invention; 
         FIG. 15  is a diagram of the selection of the needles in the execution of the various steps of the method according to the invention; 
         FIG. 16  is a schematic view of the behavior of the yarn knitted by the needles in the forming of a portion of manufacture by means of the to method according to the invention; 
         FIG. 17  is a schematic view of an enlarged-scale part of a portion of a manufacture produced by means of the method according to the invention. 
         FIGS. 18 and 19  illustrate a conventional machine. 
     
    
    
       FIGS. 18 and 19  and  FIGS. 1 to 14  show, laterally to the flat projection view of the needle actuation cams  150 , of the selector actuation cams  160  and of the sub-needle actuation cams  170 , and rotated through 90° with respect to their actual position, a needle  1 - 144 , a sub-needle  146  and a selector  145 , which are accommodated in each one of the axial slots formed on the lateral surface of the needle cylinder. 
     The method according to the invention can be performed with a circular hosiery knitting machine of the known type which comprises a needle cylinder, having a vertical axis, which can be actuated with an alternating rotary motion about its own axis. Said machine has a feed or drop  180  to be used when the needle cylinder is actuated with an alternating rotary motion about its own axis and which, during the rotation of the needle cylinder about its own axis in one direction of rotation, performs the selection of the needles that must knit at the feed  180  during the subsequent rotary motion of the needle cylinder in the opposite direction. 
     The needle cylinder has, on its lateral surface, a plurality of axial slots, in each of which a needle  1 - 144  is accommodated. 
     Around the needle cylinder there is a drop or feed  180  at which at least one yarn is dispensed, by means of one or more yarn fingers  181 , and can be engaged by the needles  1 - 144  in order to form knitting. The machine is provided with means for the actuation of the needles  1 - 144  along the corresponding axial groove in order to take up the yarn at the mentioned drop or feed  180  and form loops of knitting. 
     The machine is further provided with selection devices for selecting the needles  1 - 144  to be moved to knit at the mentioned feed  180  and these selection devices comprise a first selection device  191  and a second selection device  192 , which are arranged on mutually opposite sides with respect to the feed  180 . These selection devices  191 ,  192  are adapted to select the needles  1 - 144  downstream of the feed  180  depending on the direction of rotation of the needle cylinder about its own axis. 
     More particularly, each needle  1 - 144  is provided, in a per se known manner, with a heel  151  which protrudes radially from the corresponding axial groove of the needle cylinder and the needle actuation means comprise needle actuation cams  150  which are arranged around the needle cylinder and define paths inside which the heels  151  of the needles  1 - 144  engage. 
     In the machine shown schematically in  FIGS. 1 to 14 , the needle actuation means comprise, inside each one of the axial grooves of the needle cylinder, below each needle  1 - 144 , a selector  145  and a sub-needle  146 , which is interposed between the needle  1 - 144  and the selector  145 . Each selector  145  is provided, proximate to its lower end, with a heel  161  and can oscillate, on its plane of arrangement or on a plane that passes through the axis of the needle cylinder, with respect to the needle cylinder in order to pass from an active position, in which the heel  161  protrudes radially from the corresponding axial slot of the needle cylinder, to an inactive position, in which the heel  161  is retracted into the corresponding axial slot of the needle cylinder. 
     The ability of each selector  145  to oscillate for its transition from the active position to the inactive position and vice versa is obtained by means of an elastic portion  166  of the selector  145  which rests on the bottom of the corresponding axial slot of the needle cylinder and contrasts elastically the transition of the selector  145  from the active position to the inactive position. Each selector  145  is provided with one or more selection tabs  164  on which the selection devices  191 ,  192  act, in a per se known manner, to cause the transition of the selector  145  from the active position to the inactive position. In the illustrated embodiment, each selector  145  is also provided with a heel  165  in an intermediate region of its extension, proximate to the sub-needle  146 . 
     Each sub-needle  146  also is provided with a heel  171  which protrudes radially from the corresponding axial slot of the needle cylinder. 
     Around the needle cylinder, at the level of the selectors  145 , there are selector actuation cams  160  which can be engaged by the heels  161  of the selectors  145  when they are in the active position. Likewise, around the needle cylinder, at the level of the sub-needles  146 , there are sub-needle actuation cams  170  which can be engaged by the heels  171  of the sub-needles  146 . The needle actuation cams  150 , the sub-needle actuation cams  170  and the selector actuation cams  160  define, for the heels  151 ,  171  and  161  that engage with them, paths which are contoured to cause, as a consequence of the rotation of the needle cylinder about its own axis with respect to the cams  150 ,  170 ,  160 , the movement of the needles  1 - 144 , of the sub-needles  146  and of the selectors  145  along the corresponding axial slots of the needle cylinder or the retention of the needles  1 - 144 , of the sub-needles  146  and of the selectors  145  in a given position. More particularly, as regards the needles  1 - 144 , their movement inside the corresponding axial slot of the needle cylinder can be achieved by means of the needle actuation cams  150  or by means of the movement of the corresponding sub-needle  146  and/or of the corresponding selector  145  produced by the sub-needle actuation cams  170  or by the selector actuation cams  160 . 
     The machine shown in  FIGS. 1 to 14  is provided with ten selection devices, but only two of these devices, designated by the reference numerals  191 ,  192 , are used for the execution of the method according to the invention. More particularly, the selection device  191 , arranged directly downstream of the knockover cam  153  along the direction of rotation of the needle cylinder or of movement of the needles  1 - 144  with respect to the actuation cams  150 ,  160 ,  170  indicated by the arrow  201 , is used to perform the selection of the needles that will have to knit at the feed  180  being considered when the needle cylinder is actuated along the opposite direction of rotation, indicated by the arrow  202 , while the selection device  192 , arranged at or directly downstream of the knockover cam  154 , along the direction of rotation of the needle cylinder or of movement of the needles  1 - 144  with respect to the actuation cams  150 ,  160 ,  170  indicated by the arrow  202 , is used to perform the selection of the needles that will have to knit at the feed  180  being considered when the needle cylinder is actuated along the opposite direction of rotation, indicated by the arrow  201 . 
       FIGS. 1 to 14  are schematic flat projection views of the needle actuation cams  150 , of the sub-needle actuation cams  160  and of the selector actuation cams  170  of the same machine shown in  FIGS. 18 and 19 . A machine with a single feed  180  and with one hundred and forty-four needles is shown, but the number of feeds, as well as the number of needles, may vary according to the requirements. 
     A reference numeral from  1  to  144  has been assigned to the needles, and for the sake of simplicity and greater clarity, only the needles required to explain the method according to the invention have been numbered. 
     In  FIGS. 1 to 14 , in a manner similar to  FIGS. 18 and 19 , the reference numeral  152  designates the central cam arranged at the feed  180 , where one or more yarn fingers  181  are arranged to dispense at least one yarn which must be taken up by the needles that are moved to knit at the feed  180 . In  FIGS. 1 to 14 , in addition to the cams already identified in  FIGS. 18 and 19 , the reference numerals  155  and  156  further designate two lifting cams which are arranged above and laterally with respect to the knockover cams  153 ,  154 , and the reference numerals  157  and  158  designate the contrast cams arranged below the knockover cams  153  and  154 . 
     Between the selector actuation cams  160  there is a lifting cam  162 , which causes the rise of the selectors  145  that are in the active position and consequently the rise of the needles  1 - 144  that are in the same axial slots of the needle cylinder up to the tuck-stitch position, when the needle cylinder rotates about its own axis in the direction indicated by the arrow  201 , and two lifting cams  163 ,  167 , which cause the rise of the selectors  145  that are in the active position and consequently the lifting of the sub-needles  146  that are in the same axial slots of the needle cylinder when the needle cylinder rotates about its own axis in the direction indicated by the arrow  202 . The other selector actuation cams  160  that do not have a significant role in the execution of the method according to the invention have not been numbered and are not described further. 
     Between the sub-needle actuation cams  170  there is a lifting cam  172 , which can be engaged by the sub-needles  146  that have been raised due to the rise of the underlying selector  145  when the selector has engaged the lifting cam  163 . The sub-needle lifting cam  172  is such as to cause correspondingly the lifting of the overlying needles  1 - 144  in the tuck-stitch position. Between the sub-needle actuation cams  170  there are also lowering cams  173  and  174  in order to cancel previous rises of the sub-needles  146  and of the selectors  145 . 
     The other cams that are present in  FIGS. 1 to 14 , which do not perform a significant role in the execution of the method according to the invention, are not numbered and are not mentioned in the description that follows. 
     The cams that during the various steps of the method according to the invention are in the inactive position, i.e., spaced from the needle cylinder so as to not interfere with the heels  151 ,  161 ,  171  of the needles  1 - 144  and/or of the selectors  145  and/or of the sub-needles  146  are shown with a profile in dashed lines. 
     The method according to the invention comprises the following steps:
         identifying a group of contiguous needles in the needle cylinder;   dividing said group of needles into two contiguous needle subgroups, respectively a first needle subgroup and a second needle subgroup;   moving to knit at a feed or drop one of the two needle subgroups during the rotation of the needle cylinder in one direction and in the subsequent rotation in the opposite direction so as to form two partial rows of knitting in succession;   moving to knit at the feed being considered the other needle subgroup of the two needle subgroups during the rotation of the needle cylinder in one direction of rotation and in the subsequent rotation in the opposite direction so as to form two partial rows of knitting in succession;   proceeding in this manner by alternating, every two partial rows of knitting, the needle subgroup that is moved to knit at the feed being considered for a preset number of partial rows of knitting;       

     at least one needle of one of the needle subgroups located proximate to the other needle subgroup is moved to knit in the forming of at least one of the two partial rows of knitting formed in each instance by the other needle subgroup so as to provide the interconnection of the partial rows of knitting formed by a needle subgroup with the partial rows of knitting formed by the other needle subgroup. 
     In the example of execution of the method according to the invention, a circular hosiery knitting machine is used which is provided with one hundred and forty-four needles, of which one hundred and twenty are used for the execution of pouch or heel knitting by actuating the needle cylinder with an alternating motion about its own axis. The group of one hundred and twenty needles is divided into two subgroups, each with sixty needles. The needles of the machine have been designated by the reference numerals  1  to  144 . The needles  1  to  12  and the needles  133  to  144  are always excluded from knitting. The needles designated by the reference numerals  72  and  73  are the needles that knit alternately with the needles of their own subgroup or of the other subgroup, so as to provide the interconnection of the partial rows of knitting formed by a needle subgroup with the partial rows of knitting formed by the other needle subgroup, as highlighted in the selection diagram of  FIG. 15 . 
     Hereinafter, the rotations of the needle cylinder about its own axis in one direction of rotation or in the opposite direction, which are performed according to center angles of preset breadth, which can vary as a function of the knitting requirements, are also termed oscillations. 
     In greater detail, the method according to the invention preferably comprises a first step, in which the needle cylinder is actuated in a first direction of rotation or forward direction, designated by the arrow  201 , selecting, downstream of the feed  180 , the needles of the first subgroup to be moved to knit at the same feed  180  when the needle cylinder is actuated in the second direction of rotation or return direction, which is opposite with respect to the first direction of rotation  201  and is designated by the arrow  202 . 
     In this first step, shown in  FIG. 5 , by means of the selection device  191 , the needles, from the needle  13  to the needle  73  included, except for needle  72 , are selected and raised, as a consequence of the engagement of the selectors  145  with the lifting cam  162 , in the tuck-stitch position. Essentially, the needles from needle  13  to needle  73  included, except for the needle  72 , are selected according to the selection shown in line D of the diagram shown in  FIG. 15 , in which the selected needles are represented by a black rectangle and the unselected needles are represented by a white rectangle. During this oscillation of the needle cylinder about its own axis, the needles  1 - 144  do not form knitting. 
     In a second step of the method according to the invention, the needle cylinder reverses its direction of rotation, forming a first partial row of knitting  301  at the feed  180  with the needles that have been selected and moved to the tuck-stitch position in the first step, as shown in  FIG. 6 . In practice, the needles from needle  13  to needle  73 , with the exclusion of needle  72 , engage the lifting cam  156 , therefore the central cam  152 , taking the yarn at the feed  180  being considered, and form new loops of knitting, knocking over the loops formed previously when their heel  151  engages the knockover cam  154 . Directly downstream of the knockover cam  154  or thereat, the needles or rather the selectors  145  undergo a new selection, according to the selection shown in line E of the diagram shown in  FIG. 15 , on the part of the selection device  192  and the needles from needle  72  to needle  13 , this time excluding needle  73 , are raised to the tuck-stitch position as a consequence of the engagement of the heel  171  of the sub-needles  146  with the lifting cam  172 , as shown in  FIGS. 6 and 7 . 
     In a third step of the method according to the invention, the needle cylinder is actuated again in the first direction of rotation  201 , moving to knit at the feed  180  the needles that have been selected in the second step so as to form a second partial row of knitting  302  with the first needle subgroup, with the needles from needle  13  to needle  72 , as an extension of the first partial row of knitting  301  produced with the same first needle subgroup, as shown in  FIG. 8 . During this oscillation of the needle cylinder in the first direction of rotation  201 , no needle selection is performed, as shown in line F of the diagram shown in  FIG. 15 . In this manner, at the end of this oscillation of the needle cylinder all the needles are in the inactive position, as shown in  FIG. 9 . 
     When, in this oscillation of the needle cylinder, the needle  131  has moved beyond the selection device  192 , i.e., has passed, to the left in the figures, the selection device  192 , the direction of rotation of the needle cylinder is reversed again and the needle cylinder is rotated in the second direction of rotation  202 , beginning a fourth step of the method according to the invention. The needles of the second subgroup from the needle  131 , except for the needle  73 , and together with the needle  72  of the first subgroup, are selected by the selection device  192  and raised to the tuck-stitch position by the engagement of the sub-needles with the lifting cam  172 . Essentially, in this step, a selection of the needles is performed as indicated in line G of the diagram shown in  FIG. 15 . In this fourth step there is no forming of knitting, as shown in  FIG. 10 . 
     In a fifth step, the direction of rotation of the needle cylinder is reversed again and the needles that had been moved to the tuck-stitch position by means of the selection performed in the fourth step, i.e., the needles from needle  72  to needle  131  with the exclusion of needle  73 , form a corresponding first partial row of knitting  303  at the feed  180 . Downstream of the knockover cam  153 , the needles are selected by means of the selection device  192  as indicated in line H of the diagram shown in  FIG. 15 . In practice, the needles from needle  73  to needle  131  are moved to the tuck-stitch position, as shown in  FIG. 11  and in  FIG. 12 , which shows the situation of the needles at the end of the oscillation of the needle cylinder in the first direction of rotation  201 . 
     In a sixth step, the direction of rotation of the needle cylinder is reversed again so that the needles that have been moved to the tuck-stitch position in the fifth step, i.e., the needles from needle  131  to needle  72 , form a corresponding second partial row of knitting  304 , as shown in  FIG. 13 . In this sixth step, no selection is performed, as indicated by the line I of the diagram shown in  FIG. 15 . At the end of this oscillation of the needle cylinder in the second direction of rotation  202 , all the needles are in the inactive position, as shown in  FIG. 14 . 
     At this point the process is repeated as already described from the first step to the sixth step for a preset number of times depending on the extension of the manufacture that one wishes to obtain. 
     As can be noticed in  FIGS. 16 and 17 , the two subgroups into which the group of needles used for the production of knitting with actuation of the needle cylinder with an alternating rotary motion about its own axis produce, in each instance, two partial rows of knitting  301 ,  302  and  303 ,  304 , which are produced in succession during an oscillation of the needle cylinder in one direction and during the subsequent oscillation of the needle cylinder in the opposite direction. The partial rows of knitting produced by a needle subgroup are interconnected with the partial rows of knitting produced by the other needle subgroup, making at least one needle of one subgroup knit alternately with the needles of the other subgroup. 
     In  FIG. 16 , the partial rows of knitting produced by the respective needle subgroups have been shown uncoupled and spaced vertically in order to better illustrate the execution of the method according to the invention. Of course, in reality the rows of loops of knitting produced by a same needle will be mutually knitted in, as occurs normally in knitting. In said  FIG. 16 , the lines shown in dots and dashes indicate the oscillations of the needle cylinder without knitting production. 
     Conveniently, in the transition from the continuous rotation, shown in  FIG. 1 , to the alternated rotation of the needle cylinder about its own axis, before the first step of the method, the following are performed:
         a first preliminary step, in which the needle cylinder is actuated in the first direction of rotation  201 , selecting, downstream of the feed  180 , the needles of the second subgroup that must be moved to knit at the feed  180  upon the actuation of the needle cylinder in the second direction of rotation  202 ;   a second preliminary step, in which the needle cylinder is actuated in the second direction of rotation  202 , moving to knit at the feed  180  the needles that have been selected during the first preliminary step so as to form a preliminary partial row of knitting  305  by means of the second needle subgroup and selecting, downstream of the feed  180 , the needles of the first subgroup that must be moved to knit at the feed  180  when the needle cylinder is again rotated in the first direction of rotation  201  in the subsequent first step of the method already described.       

     More particularly, after the continuous rotary motion of the needle cylinder about its own axis, in which the needles of the group of needles to be used in knitting with actuation of the needle cylinder with an alternating rotary motion about its own axis are all moved to knit at the feed  180 , as shown in line A of the selection diagram of  FIG. 15 , in the first preliminary step, with the needle cylinder actuated in the first direction of rotation  201  downstream of the knockover cam  153 , the needles of the second subgroup, i.e., the needles from needle  73  to needle  132 , and the needle  72  are selected by the selection device  191  according to line B of the diagram of  FIG. 15  and are raised to the tuck-stitch position by the engagement of the heels of the corresponding selectors  145  with the lifting is cam  162 , as shown in  FIG. 2 . 
     In the second preliminary step, the needle cylinder is actuated with a rotary motion in the second direction of rotation  202  and the needles of the second subgroup, which in the first preliminary step had been selected and moved to the tuck-stitch position, form a first preliminary partial row of knitting  305  at the feed  180 . During this oscillation of the needle cylinder about its own axis, no selection is performed, as shown in line C of the selection diagram of  FIG. 15 . At the end of this oscillation, all the needles are in the inactive position, as shown in  FIG. 4 . After these preliminary steps, the first step of the method according to the invention begins and knitting continues as already described and illustrated in  FIGS. 5 to 14 . 
     As explained above, in some steps of the method according to the invention the oscillation of the needle cylinder performed in these steps is not aimed at producing knitting. This occurs, for example, in the first step and in the fourth step of the method as well as in the subsequent steps that constitute a repetition of these steps. 
     Execution of these oscillations, which for the sake of simplicity will be referenced as “idle oscillations”, is necessary because at the end of the two partial rows of knitting  301 ,  302  or  303 ,  304  formed in succession and produced, in the illustrated example, by the needles of the first subgroup that range from needle  13  to needle  72  or of the second subgroup that ranges from needle  73  to needle  132 , the yarn is engaged with the needle  73  in the case of the first needle subgroup  13 - 72  and with the needle  72  in the case of the second needle subgroup  73 - 132 , as shown in  FIG. 16  and in the diagram of  FIG. 15 , lines D and G. In the illustrated example, the needles  72  or  73  are at the center of the group of needles  13 - 132  used to form the pouch or heel; these needles must provide the interconnection between the two partial rows of knitting  301 ,  302  formed in succession by the first needle subgroup  13 - 72  and the two partial rows of knitting  303 ,  304  formed in succession by the second needle subgroup  73 - 132 . This causes the knitting in of the first partial row of knitting  301  or  303  of the two partial rows of knitting formed in succession by both needle subgroups  13 - 72  and  73 - 132  to always begin necessarily at the center of the pouch, i.e., at the needles  72  and  73 . Considering for example the sequence of the two partial rows of knitting  301 ,  302  performed by the first needle subgroup  13 - 72 , as shown in the diagram of  FIG. 15 , lines E and F, in the second partial row of knitting  302  formed by the first needle subgroup  13 - 72  the needles that range from needle  13  to needle  72  (diagram of  FIG. 15 , line E) are selected and moved to the tuck-stitch position with the return rotation direction  202  of the needle cylinder. These needles will form the second partial row of knitting  302  during the subsequent direction of rotation  201  of the needle cylinder (diagram of  FIG. 15 , line F). At this point, the yarn to be recovered is engaged with the needle  72 . If, during the oscillation according to the diagram of  FIG. 15  line F, the machine selected the needles of the second subgroup  73 - 132 , the yarn engaged with the needle  72  would not be picked up by the needles, with consequent broken meshes, since, due to the direction of rotation of the needles of the needle cylinder, the needles of the second subgroup  73 - 132  would have been actuated at the feed being considered before the needle  72 , making it impossible to knit in the yarn engaged with the needle  72 . 
     For the sake of greater clarity,  FIG. 16  shows the arrows  201  and  202  which indicate the direction of rotation of the needle cylinder, and the lines that correspond to lines A to I of  FIG. 15  have been indicated. 
     Essentially, in the method according to the invention, in the execution of the first partial row of knitting of the sequence of two partial rows of knitting formed by each needle subgroup, the needle cylinder must have the same direction of rotation that it has during the execution of the last partial row of knitting by means of the other needle subgroup; in order to do this, it is necessary to perform an idle oscillation between the end of the sequence of two partial rows of knitting formed by a needle subgroup and the beginning of the sequence of two partial rows of knitting formed by the other needle subgroup. 
     If the pouch to be formed must begin after a step of continuous rotary motion of the needle cylinder, the last needle that forms the knitting of the last row of knitting formed in continuous motion must be the last one of the group of needles that will form the pouch; in the illustrated example, the pouch is formed by using a group of needles that ranges from needle  13  to needle  132 , therefore the last needle that knits in the yarn on the last row of knitting in continuous motion will be needle  132 . 
       FIG. 17  shows schematically a portion of a manufacture produced with the method according to the invention. For the sake of greater simplicity, the rows of knitting have been designated by the numeral of the needle that produced them. 
     As can be noticed, the manufacture is composed of partial rows of knitting  301 ,  302  which are produced by the needle subgroup  13  to  72  and by partial rows of knitting  303 ,  304  produced by the needle subgroup  73  to  132 . The partial rows of knitting  301 ,  302  produced by the needle subgroup  13  to  72  are interconnected with the partial rows of knitting  303 ,  304  produced by the other needle subgroup  73  to  132 , by causing the knitting alternately of at least one needle, in the illustrated case the needles  72 ,  73  of the needle subgroup respectively  13 - 72  and  73 - 132 , with the needles respectively  74 - 132  and  13 - 71  of the other needle subgroup. 
     The diagram of  FIG. 15  shows a decrease of the needles of the second needle subgroup that are moved to knit during the fourth step of the method. This decrease is a knitting choice which can also be absent, without thereby abandoning the protective scope of the present invention. 
     Furthermore, preferably, the two needle subgroups have a same number of needles, although the method according to the invention can be performed with two groups of needles that have a different number of needles. 
     In practice it has been found that the method according to the invention fully achieves the intended aim, since it allows to provide portions of manufacture by means of a circular knitting machine with a needle cylinder that can be actuated with an alternating rotary motion about its own axis by using a large number of needles, in an extreme case equal to the number of needles of the machine, even with circular machines that perform selection of the needles to be moved to knit during the rotary motion of the needle cylinder in one direction, during the rotation of the needle cylinder in the directly preceding opposite direction. 
     The method thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements. 
     In practice, the materials used, as well as the dimensions, may be any according to the requirements and to the state of the art. 
     The disclosures in Italian Patent Application No. 102018000002290 from which this application claims priority are incorporated herein by reference. 
     Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.