DEVICE FOR THE POSITIVE FEEDING OF YARN TO A KNITTING MACHINE

Abstract: A device for the positive feeding of yarn to a knitting machine comprises a first yarn feeding wheel (FW1), a first feeding tape (FT1) and a yarn guiding element (11b, 11c) for bringing the yarn (Y1, 2) into engagement with the first feeding wheel and the first feeding tape and out of engagement therewith. For achieving a positive feeding of the yarn (Y1, 2) at two different yarn speeds, the device comprises a second feeding wheel (FW2), a second feeding tape (FT2), wherein said second feeding wheel is arranged close to the first feeding wheel (FW1) and wherein said guiding element (11b, 11c) is also adapted for selectively bringing the yarn into engagement with the second feeding wheel and the second feeding tape and out of engagement therewith as well as for moving the yarn from one feeding wheel to the other.

Description: DEVICE FOR THE POSITIVE FEEDING OF YARN TO A KNITTING MACHINE - The present invention relates to a device for the positive feeding of yarn to a knitting machine, preferably a circular knitting machine, for knitting pieces of goods with a ready-made-up length, in which every knitted piece has portions with a different stitch length or knitting structure. The invention is based on a device which has a yarn feed¬ ing wheel which is freely journalled on a fixed shaft in the device, and a feeding tape synchronously driven by the knitting machine, which tape is adapted to run over a part of the periphery of said yarn feeding wheel with a desired speed. A yarn control element associated with the yarn feeding wheel is also arranged to bring the yarn into engagement with the yarn feeding wheel and the yarn feeding tape ,co-acting therewith for the positive feeding of the yarn to the knitting place with said desired speed and also to guide the yarn out of this engagement into a position outside the feeding tape on the yarn feeding wheel to interrupt the positive feeding thereof. In the case of knitting pieces of goods with ready-made-up lengths, and also in other connections, there is a require- ment for being able to positively feed a yarn in one and the same knitting system with at least two different speeds during the various parts of the knitting cycle for such goods. For example, an instance can be mentioned where one knits a "pullover", where the short, lower-most section in the form of a "waist rib" should be knitted with a first positive yarn speed for generating a first portion in the goods with a first stitch size and character. Immediately thereafter, the long breast and belly section ("body section") is to be knitted with a second, positive yarn speed for generating a second portion in the goods with a second stitch size and character. This case is described in detail in the British Patent Specification No. 1.246.625 (Hosiery and Allied Trade Research Associat¬ ion, Nottingham), which also shows a yarn feeding device consisting of so-called "nip rollers" which enables the desired positive feeding of a yarn with two different speeds in one and the same knitting system during various parts of the knitting cycle. GB-A-2 109 825 already discloses a device for the positive feeding of yarn to a knitting machine. The prior art device comprises two feeding wheels of different diameter which are caused to rotate at different rotational speeds. A number of turns of the yarn to be fed to the knitting machine are wound around the second wheel and a cone and further around the first wheel where the yarn is engaged by the feeding tape. Depending on the yarn tension, the yarn comes into and out of engagement with the feeding tape. Hence, the tension of the yarn can be controlled as desired. However, this prior art apparatus is not adapted for carrying out a positive feeding of the yarn at two different, clearly defined, speeds. The object of the present invention is to accomplish a yarn feeding device adapted for a selective positive feeding of the yarn at different speeds having a less complicated structure than that of the prior art devices In accordance with the present invention, this object is achieved by a device in accordance with the prior art portion of claim 1 having the features indicated in the characterising portion thereof. A further object of the present invention is to ensure a permanently correct positioning of the feeding tapes on the two-yarn feeding wheels, namely that the feeding tape on the respective yarn feeding wheel should always run over the wheel at its edge remote from the crossing between the two wheels. According to one embodiment of the invention, this object is accomplished by the rotation axes of the two-yarn feeding wheels forming a small, acute angle, each with an unequal "sign", to the normal planes of movement for the two feeding tapes. This geometrical relationship is preferably accomplished by the journalling position for the further yarn feeding wheel on the fixed shaft consisting of a hub portion, the centre axis of which forms a small acute, "positive" angle to the centre line of the fixed shaft. The first yarn feeding wheel is journalled on a hub portion concentrically arranged with the centre line of the fixed shaft. Moreover, the whole yarn feeding device is arranged to be mounted on a support ring extending horizontally above the knitting machine and parallel to the feeding tapes in a conventional manner such that the centre line of the fixed shaft on which the two yarn feeding wheels are journalled, forms a small, acute, "negative" angle with a smaller independent value than said "positive" angle with the normal planes of movement for the two feeding tapes. Another object of the present invention is to facilitate the alteration of the speed of the yarn. Therefore, according to the invention, the device has, in one embodiment, an annular guiding flange fixed to the rim of the first yarn feeding wheel facing the further yarn feed¬ ing wheel and extending axially out over a small piece of the further yarn feeding wheel, which flange is adapted to enable the smooth sliding of the yarn over it from its position on the first yarn feeding wheel into a position on the further yarn feeding wheel, and vica versa. A preferred embodiment of the device according to the invention is described below with reference to the drawings, wherein Figs. 1 and 2 show two different views of this embodiment; Fig. 3 shows the same embodiment where vital parts in the device are shown in longitudinal sections; Fig. 4 shows the actuation means for the yarn control element in a more detailed form. As shown at Figs. 1 and 2, a knitting machine has a support ring 1 known per se, which is arranged to carry a number of identical yarn feeding devices. The respective feeding devices are located above the respective knitting places or yarn intakes of the circular knitting machine (not shown here), whereby said number corresponds to the number of knitting systems in the machine. Every yarn feeding device has a hook-formed attachment part 2a on the housing 2 which is intended for fitting the device to the support ring 1 in which a part lock screw 3 is arranged for fixing the yarn feeding device on the support ring 1. On said support ring 1 a flat, electrical cable 4 compris¬ ing five electrical conductors which are principally the same as is shown in the Applicant's own European Patent Application No. 821101173.0 (publication number 78 550) are connected to an electrical, preferably micro-processor- based control unit centrally arranged in the knitting machine. Two of the said conductors (not shown here) are connections connected to respective one of two electro¬ magnets EM. and EM- fixed in the housing 2 of the yarn feeding device, which electro-magnets are more closely shown in Fig. 4. In supporting plate 5 projecting from the housing 2 a vertical, fixed (unrotatable) shaft 6 is attached. A first yarn feeding wheel FW. is by means of a ball bearing 7 (see Fig. 3) pivotably journalled on a hub portion 8 on the shaft 6 concentrically arranged with the centre line 6' of the shaft 6. A further yarn feeding wheel FW via a further ball-bearing 9 is rotatable journalled on a second hub portion 10 on the shaft 6, whereby the centre o line 10' of said second hub portion 10 forms a 2 angle to the centre line 6' of the shaft 6. A first or second feeding tape FT. , FTp is arranged to run over a part of the periphery of the respective yarn feed¬ ing wheel with a first or a second speed v. , v 2 , synchron¬ ous with the drive of the knitting machine. Said speeds correspond to the positive feed speeds with which a yarn Y 1 f r om a yarn supply spool is, according to the present invention, fed by means of the yarn feeding device down to the working needles in the knitting machine as mentioned above so as to knit the "waist rib portion" or the "belly and breast section" in the pullover. The feeding tapes FT. and FTp are driven from the drive system of the knitting machine via a respective so-called quality adjustment pully with an adjustable drive diameter in order to achieve the desired speeds v. , Vp synchronous with the needle cylinder speed. At point P in the housing 2 in the yarn feeding device, a yarn guiding arm 11 is pivotally journalled, which has a horizontal bearing part 11a and a guiding part 11b essent¬ ially perpendicular thereto which, at its feee end, carries a yarn guiding eyelet 11c for guiding the position of the 1 in-coming yarn Y. p in the yarn feeding device. The yarn guiding arm 11 is an arrangement of two electro¬ magnets EM. and EMp and a common return spring RS adapted 5 to be able to take one of three possible positions through a control command from the above-mentioned, preferably a micro-processor-based electronic control unit, centrally arranged in the knitting machine via two of the conductors in the flat cable 4. 10 When none of the electro-magnets are actuated, the yarn guiding arm 11 will take the "neutral position" shown in Figs. 1, 2 and 4 through the influence of the return spring RS. The yarn Y. 2 running through the yarn 15 guiding eyelet 11c will be in a position outside the feeding tape FT. on the yarn feeding wheel FW 1 in which it will not be subject to any positive feed. The working needles in the machine will, themselves, pull the yarn Y. p from the yarn supply spool via the wheel FW 1 rotating 20 with the speed v.. During actuation of the lower electro-magnet EM^ the yarn guiding arm 11 will pivot in a clockwise direction under the influence of the movement of the armature 12 so that 25 the yarn Y. 2 comes into engagement between the feeding tape FT 1 and the yarn feeding wheel FW. , whereby the yarn Y 1 2 will be subjected to positive feeding with the speed v 1 of the feeding tape FT.. 30 During de-actuation of the lower electro-magnet EM. and directly following actuation of the upper electro-magnet E 2 , the yarn guiding arm 11 swivels in an anti-clockwise direction, whereby the yarn Y 1 2 leaves its engagement between the feeding tape FT 1 and the wheel FW. via its ,35 "neutral position" shown in the Figures. This is utilized for making the first course of stitches in the goods to be knitted and, during adjustment and re-adjustment work in the machine, the yarn is moved over, under the influence of the movement of the armature 13 into an analogous engagement below the further feeding tape FT 1 so that, instead, the yarn Y. 2 will be subjected to positive feed¬ ing with the speed v 2 of the feeding tape FT 2 . By means of an annular guiding flange 14 attached to the lower rim of the wheel FW. and preferably made of highly polished aluminium, which flange extends axially out over a small piece of the wheel FW 2 , the wandering of the yarn Y 1 2 from the one yarn feeding wheel to the other, and vice versa, will be facilitated. As is apparent from Fig. 2, the whole yarn feeding device is mounted such with its attachment portion 2a onto the support ring 1, with which the two feeding tapes FT. and FT 2 are adapted to run parallel by means of the previously mentioned quality wheels and guiding-rollers (not shown here). The centre line 6' of the fixed shaft 6 in the o device forms a 1 "negative" angle to the normal of the planes of movement for the two feeding tapes. Due to this, it will be ensured that the feeding tape FT. always runs over the wheel FW. at its upper rim. As a consequ¬ ence of said "inclined" mounting of the yarn feeding device on the support ring 1 and the previously mentioned angle of 2 between the centre line 10' of the hub portion 10 on the wheel FW ? and also to the centre line 6' of the fixed shaft 6, said centre line 10' will form a 1 "positive angle normal to the planes of movement for the two feeding tapes through which it is analogously ensured that the feeding tape FT 2 will always run over the wheel FW2 at its lower rim. The yarn feeding device comprises fixed guiding eyelets 15a, 15b and 15c for the yarn and a pivotally journalled yarn tensioning arm 16 which is also used for sensing the position of the yarn and for detecting a yarn breakage condition. The pivotable yarn tensioning arm 16 is known per se in the art. 1 In the embodiment of the invention shown in the drawings, the yarn feeding device also comprises a third yarn feeding wheel FW., which, like the wheel FW., is concent¬ rically journalled on the fixed shaft 6. The wheel FW 3 , 5 with respect to the present invention, is irrelevant and, therefore, not described in more detail, co-acts with a feeding tape FT, for the positive- feeding of another yarn Yg which, during certain parts of the knitting cycle, is utilized as strengthening thread, as in the above- 10 described case, during the initial phase of knitting the "waist-rib" in the goods. 15 20 25 30 ,35

Claims: CLAIMS 1. Device for the positive feeding of yarn to a knitting machine, comprising : a first freely rotatable yarn feeding wheel (FW. ); a first feeding tape (FT.) arranged to run over a 10 part of the periphery of said first yarn feeding wheel (FW.), which first feeding tape (FT.) is driven at a first speed in synchronism with the operation of the knitting machine; a yarn guiding element (11) adapted for selectively 15 bringing the yarn into engagement with said first yarn feeding wheel (FW.) and said first feeding tape (FT.) so as to positively feed the yarn at the speed of the first feeding tape (FT.) or bringing the yarn out of engagement with said first yarn feeding wheel (FW.) 20 for terminating the positive feeding of the yarn; c h a r a c t e r i s e d i n t h a t said device comprises -- a second yarn feeding wheel (FW 2 ) adapted to be rotated independent from said first yarn feeding 25 wheel (FW^, -- a second feeding tape (FT 2 ) arranged to run over a part of the periphery of said second yarn feeding wheel (FW 2 ),which second feeding tape (FT 2 ) is driven at a second speed different from said first 30 speed, said second speed being in synchronism with the operation of the knitting machine, said second yarn feeding wheel (FWp) is arranged close to said first yarn feeding wheel (FW. ), and said yarn guiding element (11) is also adapted for ,35 selectively bringing said yarn into engagement with said second yarn feeding wheel (FWp) and said second feeding tape (FT 2 ) so as to positively feed the yarn at the speed of the second feeding tape (FT 2 ) or bringing the yarn out of engagement with said second feeding tape (FTp) for terminating said positive feeding, and for moving the yarn from one yarn feed¬ ing wheel (FW., FW 2 ) to the other yarn feeding wheel (FWp, FW.) and vice versa. 2. Device as claimed in claim 1, c h a r a c t e r i s ¬ e d i n t h a t the rotational axes of said first and second yarn feeding wheels (FW., FWp) are inclined with respect to each other so that the axes together form a small acute angle, and the rotational axes of said first and second yarn feeding wheels (FW., FW 2 ) are arranged such that the respective ends of said yarn feeding wheels (FW 2 , FW 2 ) remote from the respective other yarn feeding wheel are slightly inclined versus the centre of circles defined by said feeding tapes (FT., FT 2 ). 3. Device as claimed in claim 2, c h a r a c t e r i s ¬ e d i n t h a t said second yarn feeding wheel (FW 2 ) is journalled at a hub portion (10) of a fixed shaft (6), the centre axis of said hub portion (10) forming said small acute angle together wi.th the centre line of the fixed shaft (6), said first yarn feeding wheel (FW.) being journalled at a hub portion (8) concentrically arranged with said centre line (6 1 ) of said fixed shaft (6), and said yarn feeding device is adapted to be mounted on a support ring (1) extending horizontally above the knitting machine and in parallel to the feeding tapes (FT^ FT 2 ) such that the centre line (6') of the fixed shaft (6) and a direction vertical on the plane of movement of the feeding tapes (FT^ FT 2 ) form a small acute angle having a smaller absolute value than the angle defined by the centre axis of the hub portion and the centre line of the fixed shaft (6). 4. Device as claimed in one of the claims 1 to 3, c h a r a c t e r i s e d b y an annular guiding flange (14) fixed to a rim of the first yarn feeding wheel (FW.) facing said second yarn feeding wheel (FWp), which flange slightly extends axially over said second yarn feeding wheel, which flange enables a smooth sliding of the yarn from the first yarn feeding wheel (FW.) to the second yarn feeding wheel (FW p ) and vice versa.

Inventors: JACOBSSON KURT ARNE GUNNAR, JACOBSSON, KURT, ARNE, GUNNAR
Applicants: IRO AB, AKTIEBOLAGET IRO
Application year: 1986
Main classification: D04B15
IPC codes: B65H51, D04B15