Circular knitting machine with device for producing tubular...

Textiles: knitting – Fabric manipulation – Transferring fabric

Reexamination Certificate

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Reexamination Certificate

active

06286342

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a circular knitting machine for knitting hosiery or the like, with a device for producing tubular items closed at an axial end and to a method for producing tubular items.
It is known that hosiery items, according to the conventional method of production with circular hosiery knitting machines, are unloaded from the machine that produces them with their toe open and must then be subjected to stitching or looping on appropriate machines in order to obtain the finished product.
In view of the fact that the toe stitching or looping operation significantly affects the overall production costs of hosiery items, methods and machines which allow to obtain closed-toe hosiery items directly on the machine that produces them have been studied and improved in recent years.
One of these methods is disclosed in Italian Patent no. 1,286,604 and substantially consists in forming the hosiery item on a single-cylinder circular machine by starting from the toe and formation initially a pocket by using the needles that belong substantially to one half of the needle cylinder. The initial border of the pocket, at the end of its formation, remains free inside the needle cylinder, while the final border of the pocket is retained on the needles of the half of the needle cylinder that formed it. The initial free border of the pocket is subjected to suction in a region located inside the needle cylinder. Substantially, a region of concentrated air suction is provided inside the needle cylinder and gradually affects the initial free border of the pocket as a consequence of the rotation of the needle cylinder about its own axis with respect to said concentrated air suction region. In this manner, the initial free border of the pocket is captured and gradually engaged by appropriately provided elements being constituted by particular lowering sinkers which have a point at the upper end of their nose. By the action of these lowering sinkers, the initial border of the pocket is gradually transferred above the needles of the half of the needle cylinder that did not form the pocket, so that through subsequent lifting of the needles said initial border of the pocket is crossed by the needles that did not take part in the formation of the pocket. At the end of this operation of transferring the initial border of the pocket onto the needles of the half of the needle cylinder that lies opposite the half used to form the pocket, the entire border that delimits the pocket is engaged with the needles of the needle cylinder, which are actuated so as to continue formation of the item in the conventional manner, thereby forming a hosiery item which is closed at its toe.
The concentrated air suction region, in known types of machines that perform this method, is generally constituted by a suction port, the intake whereof is located proximate to the upper end of the needle cylinder and has a profile which, according to the rotation of the needle cylinder about its own axis with respect to the suction port, gradually approaches the cylindrical wall of the needle cylinder, so that the initial border of the pocket, by engaging said profile, is gradually moved toward the needles designed to receive said initial border of the pocket, in order to allow the lowering sinkers, provided with said point, to engage said initial border in order to transfer it above said needles.
For the successful transfer of the initial border of the pocket to the needles designed to receive it, such initial border must remain constantly engaged with the profile of the suction port. If the initial border, as a consequence of the knitting process and of the yarns used for its production, is not sufficiently resilient, said initial border can disengage from the profile of the suction port, and therefore the initial border of the pocket, instead of moving gradually toward the needles that must engage it, escapes toward the axis of the needle cylinder, making it impossible for the lowering sinkers to engage it and thus making it impossible to transfer one or more parts of the initial border onto the needles that are designed to receive it.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a single-cylinder circular knitting machine for hosiery which can produce tubular items being closed at an axial end and which solves this problem effectively. Within the scope of this aim, an object of the invention is to provide a machine which can effectively transfer the initial border of a pocket, formed by using the needles that belong substantially to one half of the needle cylinder, to the needles that belong to the other half of the needle cylinder, even without having to use a region of concentrated suction inside the needle cylinder.
Another object of the invention is to devise a method which allows to produce, on a single-cylinder circular knitting machine for hosiery, tubular items which are closed at an axial end with fully satisfactory results both from a functional and from an aesthetic point of view.
This aim and these and other objects which will become better apparent hereinafter are achieved by a circular knitting machine for hosiery or the like with a device for producing tubular items closed at an axial end, comprising a needle cylinder which has a vertical axis and has, on its cylindrical wall, a plurality of axial slots, each of which accommodates a needle which can be actuated, by way of actuation cams arranged around the cylindrical wall of the needle cylinder, in order to form knitting; a sinker ring being arranged proximate to the upper end of the needle cylinder, being rigidly coupled to the needle cylinder and having a plurality of radial slots, each of which accommodates a lowering sinker; cams being provided for actuating the lowering sinkers which face said sinker ring and can be engaged by said sinkers, said needle cylinder being actuatable with a rotary motion about its own axis with respect to said needle actuation cams and to said sinker actuation cams; characterized in that it comprises a diverter which is accommodated inside the needle cylinder and is disengaged from the rotation of the needle cylinder about its own axis with respect to said actuation cams; said diverter having a profile which protrudes from an internal region of the needle cylinder gradually toward the cylindrical wall of the needle cylinder, said profile being engageable by an end portion of the item which lies inside the needle cylinder between two needles which are mutually angularly spaced around the axis of the needle cylinder for the sliding of said portion of the item along said profile as a consequence of the rotation of the needle cylinder about its own axis with respect to said diverter; means being provided for retaining said portion of the item against said profile during its sliding along said profile.
Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the machine according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:


REFERENCES:
patent: 5617744 (1997-04-01), Conti
patent: 5647229 (1997-07-01), Conti
patent: 6044668 (2000-04-01), Conti
patent: 1635992 (1971-07-01), None
patent: 0592376 (1994-04-01), None
patent: 2045000 (1971-02-01), None

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