AT AN AXIAL END THEREOF

The present invention relates to a method for closing a knitted tubular manufacture at an axial end thereof, at the end of its production cycle on a circular hosiery knitting machine or the like.

As is known, knitted tubular manufactures, such as for example hosiery items, are generally produced by means of circular hosiery knitting machines and are unloaded from the machine with both their axial ends open.

In the case of hosiery items, after being unloaded from the machine that has made them, it is necessary to close the toe, an operation that is performed by means of sewing or linking machines.

Since this operation requires the use of additional machines and labor, which affects in a significant manner the total production costs of the hosiery items, various techniques have been proposed in order to automate the closure of the toe of hosiery items or, more generally, the closure of an axial end of tubular knitted manufactures produced with circular hosiery knitting machines or the like.

The various techniques proposed so far can be divided into two main categories: a first category which comprises the techniques based on the execution of the closure directly on the machine that produces the manufacture, at the beginning or at the end of its production, and a second category which comprises the techniques based on the execution of the closure in a sewing or linking station provided for this purpose, which is spaced from the machine for producing the manufacture.

The first category has the drawback of limiting significantly the productivity of the machines, since the closing operation requires a certain amount of time during which the machine cannot produce a new manufacture.

The second category, to which for example the technique described in patent IT 1,300, 622 belongs, can at least partially obviate this problem since the productive potential of the machines is penalized only in terms of the time required to remove the manufacture from the machine that produced it, after which the machine can start producing a new manufacture while the previous manufacture undergoes sewing or linking.

On the other hand, the operations for transferring the manufacture from the production machine to the linking station often require the use of complex apparatuses which must ensure extremely precise operation.

In the use of these apparatuses, it has been found that the pickup of the manufacture from the needles of the machine that have produced it, is particularly critical, since it affects in a significant manner the total transfer time of the manufacture and since it is not always capable of ensuring the required precision.

From EP2250305 in the name of the same Applicant it is known a method for performing the closure of a tubular knitted manufacture at one of its axial ends, at the end of its production cycle on a circular hosiery knitting machine or the like, which comprises an initial step of production of the manufacture up to the execution of the last course of knitting, at the axial end of the manufacture that is opposite with respect to the axial end at which knitting began, retaining the loops of knitting of said last course of knitting in the head of the needles of the machine that formed them.

The aim of the present invention is to provide a method for performing the closure of a tubular knitted manufacture that is capable of improving the background art in one or more of the above mentioned aspects.

Within this aim, an object of the invention is to provide a method for closing a knitted tubular manufacture which allows to increase significantly the productivity of the method and of the apparatus.

Another object of the invention is to provide a method for closing a knitted tubular manufacture that is capable of reducing the cycle time while maintaining the transfer operations extremely precise.

Another object of the invention is to provide a method for closing a knitted tubular manufacture that is highly reliable, relatively easy to provide and at competitive costs.

This aim and these and other objects which will become better apparent hereinafter are achieved by a method for closing a knitted tubular manufacture according to claim 1 , optionally provided with one or more of the characteristics of the dependent claims.

Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of the method for closing a knitted tubular manufacture according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a front view of a circular hosiery knitting machine or the like;

Figure 2 is a front view of a portion of the circular machine of Figure 1 during the initial step of production of the manufacture;

Figure 3 is a top view of a portion of the circular machine of Figure 1 in a step that is intermediate between the initial step of production of the manufacture and the step of individual gripping of the loops of knitting by virtue of pickup elements;

Figure 4 is a front view of the machine portion of Figure 3;

Figure 5 is a front view of a portion of the circular machine of Figure 1 during the step of individual gripping of the loops of knitting by virtue of pickup elements;

Figure 6 is a front view of a portion of the circular machine of Figure 1 during the step of removal of the manufacture from the machine;

Figure 7 is a view of the machine in the condition of Figure 6 from a different and partially sectional viewpoint;

Figure 8 is a top view of a portion of the circular machine of Figure 1 during a step of positioning the manufacture at a sewing or linking station 102;

Figure 9 is a front view of the machine portion of Figure 8.

With reference to the figures, the method for closing a knitted tubular manufacture at an axial end thereof, at the end of its production cycle on a circular hosiery knitting machine 100 or the like, according to the present invention, comprises:

- an initial step of production of the manufacture up to the execution of the last course of knitting, at the axial end of the manufacture that is opposite with respect to the axial end at which knitting began, retaining the loops of knitting of the last course of knitting in the head 123c of the needles 123 of the machine 100 that formed them;

- a step of individual gripping of the loops of knitting by virtue of pickup elements 29 arranged against the region of the stem 123b of each needle 123 located proximate to the latch 123d on the opposite side with respect to the head 123c;

- a step of removal of the manufacture from the machine 100 that produced it, retaining each loop of knitting of the last course of knitting formed by means of said pickup elements 29;

- a step of positioning the manufacture at a sewing or linking station 102;

- a step of individual transition of the loops of knitting from the pickup elements 29 to spikes of an annular handling device which is composed of two semiannular portions, one of which can be turned over with respect to the other about a diametrical axis;

- a step of inverting the manufacture retained by the handling device;

- a step of superimposing each one of the loops of knitting of one half course of knitting on a corresponding loop of knitting of the other half course of the last course of knitting on a same spike of the handling device by means of the overturning, through an arc of substantially 180° about the diametrical axis, of one of the two semiannular portions of the handling device with respect to the other semiannular portion;

- a step of sewing or linking the pairs of loops of knitting that are mutually superimposed;

- a step of disengagement of the manufacture from the handling device, the step of removal of the manufacture comprising a first extraction preparation step, a second manufacture extraction step, and a third manufacture transfer step.

The machine 100 has a yarn guiding plate that can be lifted and lowered, a cylinder 101, a step motor for the movement on command of an internal tube in order to bring the knitting to the working position, a cylinder locking piston, a knitting pusher piston, a pickup arm 43 with corresponding piston, a yam guiding plate, an internal knitting lifting tube, an inverting piston, a dial.

The method is characterized in that the first extraction preparation step comprises the following commands:

- an extraction start command;

- a command for stopping the machine;

- a command for lifting the yam guiding plate;

- a command for restarting the machine;

- a command for waiting for the positioning of the cylinder 101 of the machine 1;

- a command for the actuation of the step motor of the internal tube in order to bring the knitting to the working position;

- a command for setting that positioning has occurred;

- a command for the actuation of the cylinder locking piston in the working condition;

- a command for the actuation of the knitting pusher piston of the cylinder in the working condition; - a command for the actuation of the piston of the pickup arm in the working condition;

- a command for moving the pickup arm 43 to an intermediate condition;

- a command for moving the pickup arm 43 to the height for entry in the machine;

- a command for waiting for the yarn guiding plate to be in the extraction position;

- a command for the angular movement of the pickup arm 43 for entry in the machine;

- a command for the vertical movement of the pickup arm 43 for the release of the knitting pusher of the cylinder;

- a command for the vertical movement of the pickup arm 43 in an intermediate position;

- a command for the pickup piston in the inactive condition if the cylinder locking piston is in the working condition;

- a wait command;

- a command for the vertical movement of the pickup arm 43 to the pickup height.

The commands comprising

- the command for stopping the machine;

- the command for restarting the machine;

- the command for waiting for the positioning of the cylinder;

- the command for the actuation of the step motor of the internal knitting lifting tube in the working position;

- the command for setting that positioning has occurred;

- the command of the cylinder locking piston in the working condition being performed substantially simultaneously.

Conveniently, the commands comprising - the command for the actuation of the pickup piston in the working condition;

- the command for moving the pickup arm 43 to an intermediate condition;

- the command for moving the pickup arm 43 to the height for entry in the machine; are performed substantially simultaneously.

Conveniently,

- the command for the angular movement of the pickup arm 43 for entry in the machine;

- the command for the vertical movement of the pickup arm 43 for the release of the knitting pusher of the cylinder;

- the command for the vertical movement of the pickup arm 43 in an intermediate position; are performed after the yarn guiding plate lifting command has brought the yarn guiding plate to a preset height.

The machine furthermore has a knitting pusher of the cylinder, a step motor and an electric throttling valve associated with a suction apparatus, a step motor for the movement of the sinkers, a step motor associated with the internal knitting lifting tube.

The second step of extraction of the manufacture comprises the following commands:

- a command for the actuation of the step motor of the internal knitting lifting tube in the inactive condition;

- a command for the actuation of the step motor to a working height for picking up the manufacture;

- a command for the knitting pusher of the cylinder in the working position;

- a wait command;

- a command for the actuation of the step motor and of the electric throttling valve of the suction apparatus;

- a command for the movement of the pickup arm 43 vertically to an extraction height;

- a command for setting the manufacture on the pickup elements;

- a command for the actuation of the step motor for the movement of the sinkers to a safety height;

- a command for the actuation of the step motor of the internal knitting lifting tube in the working condition;

- a command for the actuation of the cylinder locking piston in the inactive condition;

- a command for the actuation of the machine for leveling the needles from the heel exclusion position to the tuck stitch position.

In particular,

- the command for the actuation of the step motor of the internal knitting lifting tube in the inactive condition; and

- the command for the actuation of the step motor to a working height to pick up the manufacture; are performed substantially simultaneously.

Conveniently,

- the command for the actuation of the step motor of the internal knitting lifting tube in the working condition; and

- the command for the actuation of the cylinder locking piston in the inactive condition; are performed substantially simultaneously.

The machine furthermore has a piston associated with a lower inverting unit, a sensor for transferring the manufacture, a step motor and an electric throttling valve of the sewing machine, and a blower device for the extraction of the tubular manufacture.

The third step of transfer of the manufacture comprises the following commands: - a command for waiting for the end of the leveling of the needles;

- a command for actuating the lower inverting piston;

- a command for lowering the dial in the working condition;

- an actuation command for the angular movement of the pickup arm 43 to bring it to an intermediate position;

- a command for controlling the sensor for the transfer of the tubular manufacture;

- an actuation command for the angular movement of the pickup arm 43 to a predefined height;

- a command for the actuation of the step motor and of the electric throttling valve of the sewing machine from the lower inverting unit in order to bring it to the first throttling height;

- a command for the actuation of the step motor to incline the inverting unit at a preset height;

- a command for the actuation of the step motor and of the electric throttling valve of the intake to zero;

- a command for the actuation of the step motor for tilting the lower inverting unit at a preset height;

- a wait command;

- a command for the actuation of the step motor to incline the lower inverting unit at zero height;

- a command of the blower device to facilitate the extraction of the tubular manufacture;

- a command for the actuation of the step motor and of the electric throttling valve of the sewing machine for the suction of the lower inverting unit to the second throttling height;

- a command of the step motor for the inclination of the inverting unit at zero height;

- a command for the angular actuation of the pickup arm 43 at zero height; - an actuation command for locking the inverting unit 130 in the inactive condition;

- an actuation command for lowering the dial in the inactive condition;

- a wait command.

Advantageously,

- the actuation command for the angular movement of the pickup arm to bring it to an intermediate position;

- the command for controlling the sensor for the transfer of the tubular manufacture; and

- the actuation command for the angular movement of the pickup arm to a predefined height are performed substantially simultaneously.

In particular, the steps that comprise:

- the extraction start command;

- the command for stopping the machine;

- the command for lifting the yarn guiding plate; and the steps that comprise:

- the command for the pickup piston in the working condition;

- the command for moving the pickup arm to an intermediate condition;

- the command for moving the pickup arm to the height for entry in the machine; in relation to the first step of extraction overlap at least partially during execution.

The movements of the machine to prepare the manufacture for extraction are performed simultaneously with the steps described above.

The adoption of the step motors with closed-loop driver has allowed to increase the movement speed of the affected devices.

The adoption of the closed-loop driver on the yarn guiding plate lifting device has allowed furthermore to remove from the hosiery program some idle turns which were necessary to wait for the yarn guiding plate lifting device to go back to the starting conditions. With reference to the third step of transfer of the manufacture, if a video camera or an alternative control sensor is mounted, the restarting of the machine immediately after the passage of the hosiery item is optimized, without waiting for the control step by means of a mechanical sensor.

In practice it has been found that the invention achieves the intended aim and objects, providing a method capable of increasing significantly the productivity of the machine.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. 102020000023137 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.