EP0426030A2

EP0426030A2 - Process and device for producing patterns on stockings with double-cylinder circular knitting machines

Info

Publication number: EP0426030A2
Application number: EP90120580A
Authority: EP
Inventors: Francesco Lonati
Original assignee: Lonati SpA
Current assignee: Lonati SpA
Priority date: 1989-11-03
Filing date: 1990-10-26
Publication date: 1991-05-08
Also published as: IT8922260A0; JPH03152250A; CS516690A2; EP0426030A3; IT1237120B; IT8922260A1

Abstract

The process consists in moving all the needles of the machine into the lower cylinder before the forming of the pattern begins. The pattern is produced by moving a preset number of needles to knit at a feed of the machine so as to engage at least one pattern thread (3) which differs in color with respect to the background thread (5) used to form the region of the sock or stocking which is proximate to the pattern, so as to obtain a first pattern portion on a row of the sock or stocking. During the rotation of the lower needle cylinder, the pattern thread (3), engaged on the last needle moved to knit at this feed, is tensioned and progressively recovered and is then fed again to the same needles, or to contiguous needles, which are moved to knit at the same feed to form a new portion of the pattern row. When the pattern is complete, the pattern thread (3) is cut.

Description

The present invention relates to a process and device for producing patterns on stockings with double-cylinder circular knitting machines.
As known, patterns on socks or stockings produced with double-cylinder circular knitting machines are provided by means of hand-made embroidery or by sewing the ornamental pattern on the sock or stocking or by printing.
On socks or stockings manufactured with single-cylinder machines, the patterns are generally produced directly by the machine during the forming of the sock or stocking by feeding a preset number of needles with a thread which differs in color with respect to the thread which constitutes the remaining part of the sock or stocking, i.e. the background of the pattern. At the end of the knitting of the portion of row affected by the pattern, the thread is cut by a rotary saw which is arranged coaxially to the needle cylinder in the needle work area.
In double-cylinder machines, the obtainment of a pattern with one or more colors differing from the background color of the sock or stocking directly during the forming of said sock or stocking is extremely difficult, since it is not possible to place a rotary saw between the two cylinders due to the fact that said saw would interfere with the product being formed.
The aim of the present invention is to solve the above described problem by providing a process which allows, in a simple manner, to produce patterns, with a thread which differs in color with respect to the remaining part of the sock or stocking, on socks or stockings directly during their formation on double-cylinder machines.
Within the scope of this aim, an object of the invention is to provide a process for producing patterns on socks or stockings with double-cylinder circular knitting machines even for patterns which affect a very small number of stitches of knitting, eliminating the risk of ladders on the finished sock or stocking.
Another object of the invention is to provide a process which allows to obtain patterns with a good degree of finish.
A further object of the invention is to provide a process which does not excessively penalize the productive potentiality of modern double-cylinder machines.
Still another object of the invention is to provide a device which allows to carry out the process according to the invention and which can be installed without problems on a wide range of conventional double-cylinder machines.
This aim, these objects and others which will become apparent hereinafter are achieved by a process for producing patterns on stockings with double-cylinder circular knitting machines, characterized in that it consists in: moving all the needles of the machine into the lower needle cylinder before forming of the pattern begins; moving a preset number of needles to knit at a feed of the machine to engage at least one pattern thread which differs in color with respect to the background thread used to form the region of the sock or stocking which is proximate to the pattern, so as to obtain a first portion of pattern on a row of the sock or stocking; tensioning and progressively recovering said pattern thread engaged on the last needle moved to knit at said feed during the rotation of the lower needle cylinder about its axis; feeding said pattern thread again to the same needles, or to contiguous needles, moved to knit at said feed to form a new portion of the pattern row; cutting said pattern thread at the end of the forming of the pattern.
The process according to the invention can be easily performed by appropriately programming a known double-cylinder machine equipped with a device which is characterized in that it comprises a thread guide arranged proximate to a feed of the machine and an element for tensioning and recovering the thread fed by said thread guide upon the slackening of said thread.
Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the process according to the invention and of the device for carrying out said process, which are illustrated only by way of non-limitative example in the accompanying drawings, wherein:

figures 1 to 4 are schematic views of the sequences of the process according to the invention for producing a portion of pattern on a row of knitting;
figure 5 is a schematic view of an enlarged portion of a sock or stocking affected by the pattern produced with the process according to the invention;
figures 6 to 9 are schematic lateral elevation views of a device for carrying out the process according to the invention during the various steps of said process; and figure 10 is a schematic view of an enlarged portion of a sock or stocking affected by the pattern produced according to another embodiment of the process according to the invention.

With reference to the above figures, the process according to the invention consists in moving, prior to the production of the first row of knitting affected by the pattern, all the needles into the lower needle cylinder 1. Upstream of a feed 2 of the machine, a selection of the needles is performed so as to move to knit, i.e. engage the thread 3 fed to this feed, only a preset number of needles 4 according to the width of the portion of row being formed which is to be occupied by the pattern. A thread 3 of a different color with respect to the thread 5 used for the knitting of the remaining part of the sock or stocking which constitutes the background of the pattern is fed to the needles 4 at the feed 2.
During rotation of the lower needle cylinder 1 about its axis 1a, the thread 3 remains engaged with the last of the needles which have been moved to knit at the feed 2. The feeding of the thread 3 continues during the fraction of turn of the cylinder 1 which moves the needles away from the feed 2, but when the needles 4 move again toward the feed 2 in the subsequent fraction of turn, the thread 3 is kept under tension and is progressively recovered so as to avoid interferences with the other elements of the machine.
When the same needles 4, or needles which are contiguous thereto, are again selected upstream of the feed 2 and again moved to knit at said feed, the previously recovered thread 3 is again fed to said needles, which thus form a further portion of pattern on a subsequent row of knitting.
The last stitch of the pattern portion of the preceding row is connected to the first stitch of the pattern portion of the subsequent row by a portion 3a of thread on the reverse side of the knitting.
When the pattern has been completed, the thread 3 is cut in a known manner, for example by means of a conventional clamping and cutting device.
The remaining part of the sock or stocking is formed without problems with the thread 5 fed at another feed of the machine which is angularly spaced from the feed 2 with respect to the axis 1a of the lower needle cylinder.
The needles intended to engage the pattern thread 3 at the feed 2, or at least some of said needles, do not engage the thread 5 at the related feed, and said thread 5 remains floating on the side of the needles which is directed toward the axis la of the lower needle cylinder.
If interweaving between the thread 3 and the thread 5 is required at the edge of the pattern or even in the pattern itself, the needles intended to perform said interweaving are moved to also knit at the feed which dispenses the thread 5 so as to engage both threads 3 and 5 (figure 10).
A known thread guide 10 is used to perform the process according to the invention; said thread guide is arranged with its feed end 10a at a feed of the machine, and the thread 3 for forming the pattern is fed through it. Said thread guide 10 is fitted with an element 11 for tensioning and recovering the fed thread 3 when slackening thereof occurs.
More particularly, the tensioning element 11 is substantially constituted by an arm 12 which is hinged, at an intermediate portion thereof, to a supporting frame 13 so that an end 12a of said arm 12, at which a passage 14 for the thread 3 is defined upstream of the end 10a of the thread guide 10, can move closer or away from said end 10a.
Elastic means, two springs 15 and 16 in the illustrated case, act on the arm 12 to bias the motion of the end 12a toward the feed end 10a of the thread guide 10.
Means 17 for locking the arm 12 in its position of maximum approach to the feed end 10a of the thread guide 10 are furthermore mounted on the supporting frame 13. Said locking means 17 are substantially constituted by a movable shoulder 18 which can be controllably moved by means of a double-action pneumatic cylinder 19 mounted on the supporting frame 13. The shoulder 18 is movable from a locking position, in which it hinders the oscillation of the arm 12 away from the feed end 10a of the thread guide, to a release position in which it does not interfere with the oscillation of the arm 12.
The operation of the element for tensioning and recovering the thread when carrying out the process according to the invention is as follows.
When the pattern is not produced, the shoulder 18 is kept in locking position (figure 6). When the knitting of the pattern begins, the shoulder 18 is moved to the release position (figure 7) by virtue of the actuation of the pneumatic cylinder 19. While the needles which form the pattern move away from the thread guide 10 due to the rotation of the lower needle cylinder, the tension to which the thread 3 is subjected keeps the arm 12 close to the end 10a of the thread guide, overcoming the force exerted thereon by the springs 15 and 16.
When the needles 4 move again toward the end 10a of the thread guide 10, the thread 3 is kept under tension and is partially recovered by the oscillation of the arm 12 away from the end 10a performed by the springs 15 and 16 (figure 8). When the feeding of the thread 3 to the needles which form the pattern resumes, on the subsequent row of knitting, due to the rotation of the lower needle cylinder, the arm 12 is again moved toward the end 10a of the thread guide 10 and the cycle continues (figure 9).
In practice it has been observed that the process according to the invention fully achieves the intended aim, since it allows the production of patterns on socks or stockings directly during their formation on double-cylinder circular knitting machines.
Since the thread which is knitted to form the pattern is cut only at the end of the pattern, it is furthermore possible to produce patterns which affect a small number of needles without accidental unthreadings of the thread.
The process thus conceived, as well as the device for carrying out said process, are susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with technically equivalent elements.
In practice, the materials employed, as well as the dimensions, may be any according to the requirements and to the state of the art.
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 scope of each element identified by way of example by such reference signs.

Claims

1. Process for producing patterns on stockings with double-cylinder circular knitting machines, characterized in that it consists in: moving all the needles of the machine into the lower needle cylinder before forming of the pattern begins; moving a preset number of needles to knit at a feed of the machine to engage at least one pattern thread which differs in color with respect to the background thread used to form the region of the sock or stocking which is proximate to the pattern, so as to obtain a first portion of pattern on a row of said sock or stocking; tensioning and progressively recovering said pattern thread engaged to the last needle moved to knit at said feed during the rotation of the lower needle cylinder about its axis; feeding said pattern thread again to the same needles, or to contiguous needles, moved to knit at said feed to form a new portion of a row of pattern; cutting said pattern thread at the end of the forming of the pattern.

2. Process according to claim 1, characterized in that the background thread is fed to the needles at another feed which is angularly spaced from said feed with respect to the axis of the lower needle cylinder and in that said background thread is kept floating on the side of the needles which is directed toward the axis of the lower needle cylinder at the needles intended to engage the pattern thread.

3. Device for producing patterns on stockings with a double-cylinder circular knitting machine, characterized in that it comprises a thread guide arranged proximate to a feed of the machine and an element for tensioning and recovering the thread fed by said thread guide upon the slackening of said thread.

4. Device according to claim 3, characterized in that said tensioning element comprises a movable arm which defines, upstream of said thread guide, a passage for the thread to be fed through said thread guide, said arm being movable with said passage toward or away from the feed end of said thread guide.

5. Device according to claims 3 and 4, characterized in that said arm is movable with said passage toward the feed end of said thread guide in contrast with elastic return means.

6. Device according to one or more of the preceding claims, characterized in that it comprises controllably activatable means for locking said arm in the position of maximum approach of said passage to the feed end of said thread guide.