WO2002074674A1

WO2002074674A1 - Improved method for handling yarn intended for supplying circular hosiery and knitting machines

Info

Publication number: WO2002074674A1
Application number: PCT/IT2002/000178
Authority: WO
Inventors: Mariella Crotti
Original assignee: Mariella Crotti
Priority date: 2001-03-20
Filing date: 2002-03-20
Publication date: 2002-09-26

Abstract

A method for handling yarn intended to supply circular hosiery and knitting macines is disclosed, in which a single head drawing-winding frame capable of electronically controlling a thread guide and equipped with an electronically controlled thread guide which moves on a straight line which is parallel to the rotation axis of the spool is used to form yarn spools whose shape is cylindrical in correspondence with one end and frustum of cone shaped in correspondence with the opposite end.

Description

Improved method for handling yarn intended for supplying circular hosiery and knitting machines

DESCRIPTION

Field of the invention The invention refers to an improved method for handling yarn intended to supply circular hosiery and knitwear machines.

Prior art

Very often imperfections are found in items made using circular knitting and hosiery machines, particularly in the thinner and lighter items, such as stockings and tights for women. Such imperfections consist of faulty, irregular distribution of stitches in the fabric and uneven row creating what is known as

"uneven stitch courses", i.e. alternating sequences also in the same row of either sparser stitches and denser stitches or longer stitches and shorter stitches. In relation to knitting technique methods, these imperfections are mainly caused by the tension of the yarn not being constant during the passage from the spool (or bobbin), which contains it to the machine, which it is intended to supply.

Lap machines capable of ensuring correct yarn tension in the various layers of windings forming the spool have been used for approximately thirty years in order to improve the quality of yarn on spools or bobbins intended to feed textile machines; the object being to provide winders with a device, arranged "upstream" with respect to the machine specifically intended to form the spool, capable of ensuring even and constant yam tension before the yarn passes to the machine specifically intended to wind the spool. Such methods are described, among others, in US Patent no. 4,245,794 (inventors Katsumi and Michio), US Patent no. 3,048,448 (inventor Keith), US Patent no.

3,350,022 (inventor Bense) and implemented in machines made by "Leesona

Corporation" based in Warwick, Massachusetts, USA. These yarn handling methods neither eliminated nor appreciably attenuated the shortcoming examined herein which persists and occurs in the current art. This is because the shortcoming does not depend on the tension applied and applicable on the yarn during spool winding. Practical observations have demonstrated that yarn looses the even tension with which it was wound when it is reeled off the spool. This fact essentially depends on the structural and functional characteristics of the spools wound using traditional systems which are currently in use, which:

- present irregular arrangement (i.e. irregular distribution and alignment) of the yarn windings in the various layers of the spool; - due to their conformation make the yarn reel-off travel very wide and very frequent, creating very fast fore-aft movements on the body of the spool during unwinding which makes unwinding less fluent (less flowing); this occurs in the case of perfectly cylindrical spools (also known as "tubes"), due to the considerable diameter and thickness, and in the case of "cops", shaped as a tube with tapered ends (whereby assuming a frustum of cone shape), due to the considerable length related to the need to contain an amount of yarn such to avoid excessively frequent replacement during use of the machine to which the yarn is intended, despite the shape. Object and summary of the invention The object of the invention is to overcome the said shortcomings by totally or almost totally remove the causes thereof.

For this purpose, firstly a single head drawing-winding frame is used for winding the spool or bobbin. The drawing-winding frame provides high yam drawing efficiency and is capable of electronically controlling the thread guide parameters for determining the pitch and the number of windings in each layer of yarn on the spool and capable of automatically either increasing or decreasing the pitch and number to create spools or any shape. By the way of a non-limiting example, a drawing-winding frame presenting such characteristics is described in Italian Industrial Invention Patent no. 01274541 granted 17 July 1997 (inventors Boni and Crotti).

Said single head drawing-winding frame is appropriately and preferably provided with a special thread guide operated by an electrical stepper motor and moving on a perfectly straight stroke along a line which is parallel to the rotation axis of the spool. A thread guide of this kind is described, again by the way of a non-limiting example, in Italian Patent no. 1230882 granted 8 November 1991 , in European Patent no. 0,423,927 following Application dated 12 June 1990 and in US Patent no. 5,082,193 dated 21 January following Application no. 536,364 dated 11 June 1990 (inventor Boni). A thread guide with these characteristics is capable of ensuring even distribution - i.e. regular alignment, perfect arrangement and indispensable density and compactness - during spool winding of the windings of yarn forming the various layers of the spool. A significant factor in obtaining the result which is the object of the invention is in that the use of a single head drawing-winding frame with the special thread guide described above ensures even distribution and correct arrangement and alignment of the windings of the various layers of yam forming the spool. Additionally, said layers of yarn are tightly wound so that the entire yarn complex forming the spool grasps and firmly presses the tube, cone or pirn on which the yarn is wound, to the extent that said tube or cop must be made of highly resistant, stiff material, such as steel, iron or high quality duralumin. This will maintain as long as possible the maximum uniformity of tension of yarn conferred by the drawing-winding frame. As mentioned above in relation to the problems existing in the current art, the shortcoming which the invention aims at solving would be attenuated and not entirely eliminated if the drawing-winding frame with thread guide of the type described above were used to wind spools with either of the aforesaid traditional shapes because the second cause of the shortcoming would still exist.

Consequently, according to the method of the invention, the most suitable shape will be conferred to the spool for supplying circular machines for hosiery and knitting to make yam reeling-off fluent or flowing, by winding the spool so that one end presents a frustum of cone shape for approximately half of its total length and the other end a cylindrical structure for the remaining approximately half of its length, the entire spool presenting the form of a cylinder (right circular cylinder), on one base of which the base of a parallel base frustum of cone is placed, whose larger diameter base is equal to either cylinder base diameter and whose smaller diameter base is either equal to or slightly larger than the external diameter of the tube on which the spool is wound. This conformation is an essential characterising aspect of the invention because the yarn being reeled off the spool and proceeding towards the hosiery or knitting machine slides for a certain length along the frustum of cone portion of the spool, which immediately and gradually assumes a much smaller diameter than the cylindrical portion of the spool. For example, in principle, the height and diameter of the larger base of frustum of cone portion of the spool will be equal to the height and the diameter of the base of the cylindrical portion and the smaller diameter base which is not larger than the external diameter of the tube on which the spool is wound, respectively. The acute generating angle of the conic surface of the frustum of cone portion (i.e. the half opening of the angle at the vertex of the conic surface) will have an amplitude of approximately 20° (twenty degrees); the operator may slightly vary such structural dimensions for practically implementing the invention, providing that said variations do not nullify or reduce the suitability of the invention to pursue the object. The free end of the cylindrical portion of the spool will be equipped with a circular flange whose diameter is not smaller than that of the cylindrical portion. The free end of the frustum of cone portion may, not necessarily, be equipped with a second flange, whose diameter is smaller than that of the cylindrical portion but not exceeding the diameter of the small base of the frustum of cone portion; the size being possibly only slightly larger by the extent which experimentally does not hinder the regular unwinding of the yarn.

The aforesaid spool conformation offers the most effective compromise between the intent of obtaining a more fluent "flow" of yarn being reeled off the spool and the necessity that the spool contains a sufficient amount of yarn to avoid excessively frequent replacement during the circular hosiery machine operation. Brief description of the drawings For an easier understanding of the various phases of the method reference shall be made to the enclosed drawing figures - which are clearly only synthetic and schematic - which are provided solely as a non limiting example. More particularly, in the drawing: - Fig. 1 is a lateral schematic view of a drawing-winding frame which can be used for making spools according to the invention;

- Fig. 2 is a lateral view of the spool, and

- Fig. 3 is schematic representation of the production cycle and use of the spool. Detailed description of a preferred embodiment of the invention

In Fig., 1 , reference numeral 1 indicates the spool or bobbin, reference numeral 2 indicates the skein which contains and supplies the feeding yarn to the drawing-winding frame, reference numeral 3 indicates the supplying and drawing area, reference numeral 4 indicates the thread guide unit and reference numeral 5 indicates the area of the drawing-winding frame where the spool 1 is wound.

More specifically, the yarn F, typically polyester yarn, is unwound by the skein 2 and supplied to the thread guide unit 4 passing through the supplying and drawing area 3 where it is entrained around rollers 3.1 , 3.1 , 3.3, 3.4, 3.5 and where it undergoes a cold-drawing process. The drawn yarn is distributed on the tube to form the spool 1 of the required shape by means of the thread guide unit 4. The latter comprises a thread guide 4.1 , carried by the end of a rod 4.2, whose movement is electronically controlled and determined by a stepper motor, or other equivalent means, and whose travel is straight and parallel to the axis of the tube 7 and, consequently, to the spool 1 being wound. The rod 4.2 will be held by a drive wheel 4.3, which is turned by the stepper motor, and two idle rollers 4.4. The wheel 4.3 and the rollers 4.4 accurately guide the rod 4.2 and, consequently, the thread guide 4.1. The electronic control of the movement is used to program the arrangement of the yarn windings on the spool 1 as desired.

The structure of the machine and the thread guide can be either similar or equivalent to those disclosed in Italian Patent no. 1 ,274,541 and European Patent no. 403927, to which reference is made for greater details.

Winding of the yarn of the spool 1 is controlled so to obtain a spool whose shape is shown in Fig. 2. It presents a total height H and comprises a first portion 1C, with height HC, whose development is essentially cylindrical, with diameter D. The cylindrical portion 1 C is topped by a second frustum of cone portion 1T, with height HT, a larger diameter base D equal to the diameter of the cylindrical portion 1C and a smaller base with diameter d, either equal to or slighter larger than the diameter of the tube 7 on which the spool is wound. Reference numeral 9 indicates a lower flange integral with the tube 7, whose diameter is either equal to or slightly larger than the diameter D of the cylindrical part of the spool, while reference numeral 11 indicates an upper flange, whose diameter is either equal to or smaller than the diameter d of the smaller base of the frustum of cone portion 1 T of the spool 1.

The two heights HT and HC are approximately equivalent, i.e. the cylindrical and frustum of cone portions each occupy approximately half of the total axial development of the spool.

The frustum of cone portion 1T is delimited by a cone surface whose vertex aperture is approximately equal to 40°, i.e. with a generating angle of the cylindrical surface equal to approximately 20°, as shown in Fig. 2. The spool 1 can present a total height comprised in the range from 280 and 350 mm, preferably in the range from 300 to 320 mm. The diameter D can be advantageously comprised in the range from 120 to 200 mm, preferably in the range from 150 to 180 mm, while the minimum diameter can advantageously be comprised in the range from 30 to 60 mm, preferably in the range from 45 to 55 mm. The yarn is wound on the spool in windings, ensuring adequate tension, e.g. comprised in the range from 1 to 2 grams on the yarn. The windings of yarn present a winding pitch which may vary according to the diameter and be comprised in the range from 0.2 mm to 1 mm, preferably in the range from 0.4 to 0.9 mm. These parameters ensure adequate tension of the yarn and high compactness of the spool. The final compactness is due to the lengthways retraction to which the yarn is subjected after being wound on the spool in addition to the winding tension and to the pitch.

The special shape of the spool and its high level of compactness ensure yarn unwinding or reeling-off. This is because the windings on which the yarn slides as it is progressively unwound off the spool do not come loose thanks to their high compactness, thus avoiding irregularity in yarn supply to the machine for which the yarn is intended.

Fig. 3 schematically indicates the total processing cycle according to the invention. The spool is wound by the drawing-winding frame according to the method described above and fed to the user machine, consisting of a knitting or hosiery machine, more specifically a circular knitting or hosiery machine, generically indicated with reference numeral 20.

The characteristics and advantages of the improved method for handling the yarn intended to supply hosiery and knitting machines clearly appear in the description. Naturally, numerous changes can be implemented to the above described method without departing from the scope of the present invention; obviously the materials, shapes and dimensions of the details illustrated herein may be replaced with others providing the same technical characteristics according to needs deriving from the practical implementation of the product deriving from this method.

Claims

1. Method for handling yarn intended to supply circular knitting and hosiery machines, characterised in that a single head drawing-winding frame which in addition to drawing the yarn is capable of electronically controlling the parameters of the thread guide to automatically determine the pitch and the number of windings in each of the yarn layers forming the spool designed to feed the hosiery or knitting machine, and increase or decrease the pitch and number, for forming spools of any shape, and in that it is equipped with an electrically controlled guide thread operated by a dedicated stepper motor, which moves on a straight line parallel to the rotation axis of the spool, being supported by a rod accurately guided by a drive wheel and by opposed counteracting rollers, and whose operating parameters are managed the electronic control unit of the drawing-winding machine to form a spool or bobbin of yarn intended to supply the circular hosiery or knitting machine on a tube or cop of validly resistant and stiff material, such as steel, iron or high quality duralumin, so that the spool presents a frustum of cone shape at one end and a cylindrical conformation at the other end (so that the entire spool presents the form of a cylinder, one base of which coinciding with the base of a parallel base frustum of cone), having the generating acute angle of the conic surface of the frustum of cone an amplitude of approximately 20° (twenty degrees), the larger diameter of the frustum of cone base being equal to the diameter of the bases of the cylindrical portion and a Height being approximately equal to the height of the cylindrical portion.

2. Method for winding a spool of yarn intended to supply a knitting or hosiery machine wherein a spool with a frustum of cone portion and a cylindrical portion is formed, characterised in that the cylindrical portion and the frustum of cone portion of the spool each occupy approximately half of the total axial development of the spool and in that the aperture angle of the frustum of cone portion is approximately 40°, the diameter of the larger base of the frustum of cone being equal to the diameter of bases of the cylindrical portion.

3. Method according to claim 1 or 2, characterised in that the free end of the cylindrical portion of the spool is equipped with a circular flange whose diameter is not smaller than that of the cylindrical portion.

4. Method according to claim 1 , 2 or 3, characterised in that the frustum of cone free end of the spool is equipped with a flange whose diameter is smaller than that of the cylindrical portion of the spool and is not larger than the diameter of the smaller base of the frustum of cone portion, and in any way whose diameter neither prevents nor obstructs regular reeling- off of the yarn.

5. Method according to one or more of the claims above, characterised in that said spool is formed so that the smaller base of the frustum of cone portion is equal to the diameter of the tube on which it is wound.

6. Method according to one or more of the claims above, characterised in that said spool is made with cold-drawn polyester yarn.

7. Method according to one or more of the claims above, characterised in that the yarn is wound on the spool according to windings whose pitch is included in the range from 0.2 mm to 1 mm, and preferably in the range from 0.4 mm to 0.9 mm.

8. Method according to one or more of the claims above, characterised in that said spool presents a total height included in the range from 280 mm to 350 mm, and preferably in the range from 300 to 320 mm.

9. Method according to one or more of the claims above, characterised in that the diameter of the cylindrical portion of the spool is included in the range from 120 mm to 200 mm, and preferably in the range from 150 mm to 180 mm.

10. Method according to one or more of the claims above, characterised in that the diameter of the smaller base of the frustum of cone portion of said spool is included in the range from 30 mm to 60 mm, and preferably in the range from 45 mm to 55 mm.

11. Method according to one or more of the claims above, characterised in that the yarn is kept at a tension included in the range from 0.5 to 3 grams, and preferably in the range from 1 to 2 grams, during winding on said spool.

12. Spool of yarn intended to supply a knitting or hosiery machine including a cylindrical portion and a frustum of cone portion, characterised in that the cylindrical portion and the frustum of cone portion of the spool each occupy approximately half of the total axial development of the spool and that the aperture angle of the frustum of cone portion is approximately 40°, the larger diameter base of the frustum of cone being equal to the diameter of the basis of the cylindrical portion.

13. Spool according to claim 12, characterised in that the free end of the cylindrical portion is equipped with a circular flange whose diameter is not smaller than that of said cylindrical portion.

14. Spool according to claim 12 or 13, characterised in that the frustum of cone free end of the spool is equipped with a flange whose diameter is smaller than the diameter of the cylindrical portion and is not larger than the diameter of the smaller base of the frustum of cone portion and any way whose diameter neither prevents nor obstructs regular reeling-off of the yarn.

15. Spool according to one or more of the claims from 12 to 14, characterised in that said spool is formed so that the smaller base of the frustum of cone portion is equal to the diameter of the tube on which it is wound.

16. Spool according to one or more of the claims from 12 to 15, characterised in that said spool is made with cold-drawn polyester yarn.

17. Spool according to one or more of the claims from 12 to 16, characterised in that the yarn is wound on the spool according to windings whose pitch is included in the range from 0.2 mm to 1 mm, and preferably in the range from 0.4 mm to 0.9 mm.

18. Spool according to one or more of the claims from 12 to 17, characterised in that said spool presents a total height included in the range from 280 mm to 350 mm, and preferably in the range from 300 to 320 mm.

19. Spool according to one or more of the claims from 12 to 18, characterised in that the diameter of the cylindrical portion of the spool is included in the range from 120 mm to 200 mm, and preferably in the range from 150 mm to 180 mm.

20. Spool according to one or more of the claims from 12 to 19, characterised in that the diameter of the smaller base of the frustum of cone portion is included in the range from 30 mm to 60 mm, and preferably in the range from 45 mm to 55 mm.