Background of the invention.

The present mvention relates to a method for manufacturing a cover for the protection of substantially cylindrical bobbins from the reeling of the yam, duπng the succeeding treatment and transportation of the bobbin to the user

A need exists to protect yarns which are wound on bobbins, so that duπng the succeed¬ ing treatment and transportation, the bobbins are not damaged in such a way that the yam or at least the extreme part of the yam in a bobbin will be unfit for use

In particular, it is advisable to protect bobbins duπng the dyeing process of the yams

The yarns are wound onto special dyeing tubes, suitable for injectionspears in the dye- ing machine The dyeing process is effected by pressing the dyestuff with great pres¬ sure through the spears and out through the bobbin Hereby, there is a πsk that the extreme layers are damaged This will obstruct a subsequent unspooling Therefore, it will be necessary to discard a large or small part of the yams, which are on the extreme of the bobbin The dyestuff which is used, is a so called dye bath, meaning water, pig- ments, chemicals, etc

By the mounting of a protection cover on a bobbin, it is very important that the cover does not slide over the extreme layer of the bobbin, as this will also damage the ex¬ treme layers of yarn in the bobbin and thereby obstruct a subsequent unspooling At the same time, it is a requirement that a protection cover, after mounting, must afford great strength against the yarns, in order to ensure that said yarns he correctly in the bobbin, especially duπng the dyeing process After dyeing and transportation of a bobbin to a user, as e g a knitting mill, a weaving mill, or the like, the cover must be removable from the bobbin without the risk of damaging the extreme yam layers in the bobbin

Accordingly, there exist different requirements for a protection cover Duπng the mounting, the cover must be expandable to a considerably larger diameter than the

diameter of the bobbin in order to avoid a mutual sliding between the cover and the bobbin, whereas a large elastical contraction intensity is requested during the subse¬ quent treatment and transportation It is the object of the present invention to provide a method for manufacturing a protection cover which satisfies the above requirements

According to the invention this is obtained by means of a method of the type mentioned above, characterized in that a tubular cover is knitted, said cover being provided for being loosely arranged on a bobbin, in that the cover is shrunk while arranged on the bobbin in order to shrink the cover around the bobbin in order to bear against the cyl- inder surface of the bobbin and an edge area of the end surfaces of the bobbin.

As the cover is manufactured by knitting, it will be possible, according to prior art, in itself, to obtain an elastical contractional intensity of such a cover, either because of the knitting itself, or by the use of knitted-in elastic threads The tubular cover can be manufactured by the cutting up of an endless tube into suitable lenghts or by the manufacturing of individual tubular covers of lengths necessary for the cover to lie around the cylinder surface of the bobbin and at least the edge areas of the end surfaces of the bobbin

After the knitting, the knitted tubular cover will appear very loose In this condition the tubular cover can be arranged over the bobbin It is noted that prior to this placing a steam treatment of the yarn could be carried out, in order to achieve a better firmness of the meshes which can facilitate the cutting up of an endless tube into suitable lengths When the tubular cover is arranged onto the bobbin the shrinking process takes place The shrinking process itself, or the fixation, is in itself a known finishing treatment of knitted fabric which is carried out before the knitted fabric is being used By starting to use the knitted fabric and placing the non-finished cover around the bobbin and thereby carrying out a finishing treatment of the cover, while it is arranged on the bobbin, the loosely mounted cover will be shrunk to such an extent that it can be brought into close contact with the bobbin This takes place without a mutual sliding between bobbin and cover, whereby there is no risk of damaging the outer layers of the bobbin.

The protection cover can be used in connection with any bobbins for successive treat¬ ment and transportation. However, the protection cover will be especially advanta¬ geous for the purpose of bobbins which are to be dyed, subsequently. When the yam in the bobbin is to be dyed, it is common procedure to pre-treat the yams by carrying out a shrinking process, e.g. by means of autoclaving. If the yarns are not given such a pre¬ treatment and do not shrink until during the dyeing, there is a risk that discoloration occur in the dyed yarn. Therefore, the procedure according to the invention is espe¬ cially advantageous in situations, in which the yam in the bobbin is to be dyed, as one then finalizes the protection cover and pre-treats the yarn in the bobbin, in one and the same process When the bobbin is to be used, the cover can easily be removed, e.g. by being lifted off in an area of the bobbin and being cut up in the longitudinal direction.

Preferably textured high-elasticity yarns are used for the knitting of the cover, prefera¬ bly yarns of polyester type. Said yams are especially suitable for creating the loose mounting and subsequently a high elasticity after shrinkage. In order to facilitate the removal of the cover, when the bobbin is being used, a tearing thread is knitted up in the longitudinal direction of the cover. This tearing thread is preferably placed in im¬ mediate connection to a coloured thread or a thread of e.g. nylon which is not dyed, if dyeing of the bobbin is to be carried out. In this way it will be easy to detect the tearing thread. The tearing thread which preferably has a thickness less than 25 Dtex, and which is particularly less than 20 Dtex is very easily broken by an outwards directed traction in the area around the tearing thread. Hereby, a particularly easy method to remove the protection cover is achieved. As the tearing thread is easily broken by an outwards directed traction, the risk of damaging the outer layers of the bobbin does not arise, and the cover can be removed easily, without the need to be displaced along the cylinder surface of the bobbin which will give rise to a risk of damaging of the outer layers of the bobbin.

In order to obtain a sufficiently high elasticity in the end surfaces bearing against the end surfaces of the bobbins, it is preferred that a more dense knitting is made in said areas than in the central part of the cover. In stead or in addition, it is also possible to knit elastic threads into said areas. Said elastic threads are knitted across more needle

rows in order to establish a larger elastic force in the end parts of the cover Such a force in the end parts of the cover is particularly advantageous when the bobbin is to be dyed As the dyestuff is pressed out through the bobbin at great force, there will be a risk that the end parts of the bobbin are pressed free off the end parts of the bobbin, where the force of the dyestuff is not reduced by passing through the layers of the bobbin

The cover is preferably manufactured by knitting on double Raschel machines Hereby it is possible to use the front and the reverse sides for making the tubular cover. After the manufacturing of the cover, it is exposed to a shrinkage of between 50% and

100%. preferably approx 75% Between 30% and 50%, preferably 40% of the shrink¬ age takes place during the autoclaving when the protection cover is arranged on the bobbin

Description of the drawing.

The invention will be described in more detail below, with reference to the attached drawing, on which fig 1 and 2 schematically show a protection cover before and after the shrinking around a bobbin, fig 3 is a partial knitting diagram which is illustrative of the knitting of a pro¬ tection cover on a double Raschel machine, and fig 4 shows another partial knitting diagram which is illustrative of the knitting of a protection cover on a double Raschel machine

In figure 1 a protection cover 1 is seen, said cover is placed loosely around a bobbin 2

The bobbin is substantially cylindrical around a central axis 3 The bobbin 2 has a cylin¬ der surface 4, and end surfaces 5 (only one is visible) In figure 2 the protection cover 1 is seen arranged on the bobbin 2, after shrinkage has taken place In this situation the yam cover 1 is bearing against the cylinder surface 2 and edge areas 6 of the end sur- faces 5

Furthermore, in figures 1 and 2, a tearing thread 7 is schematically illustrated. The tearing thread 7 is knitted into the protection cover 1 in the longitudinal direction thereof. When an outwards directed traction is performed in the cover in the area at the tearing thread 7, said thread will be torn, and hereby the tubular protection cover 1 will be divided in the longitudinal direction. Subsequently, the protection cover 1 can be removed from the bobbin 4, without the risk of damaging the extreme yam layers in the bobbin.

In figure 3 a partial knitting diagram is seen. It is noted that the shown knitting diagram only shows the front of a double Raschel machine. A similar knitting will be made on the reverse side of the machine.

At area 8 the area of the end parts of a cover 1 is indicated. In the area 8 elastic threads 9 have been included, said threads are sequenced across a number of needle rows. In area 10, which illustrates a central part of a cover 1, the elastic threads extend substan¬ tially rectilinear. Due to said knitting, a larger amount of elastical contraction force is obtained in the end parts of the cover 1, which are arranged for being drawn around the end surfaces 5 of the bobbin 4. The elastic threads 9 are preferably elastane threads.

In figure 3 a tearing thread 1 1 is seen. A dyed yam 12 is knitted up in immediate con¬ nection with the tearing thread 11. Hereby it is easy to identify the tearing thread 11 , when a cover 1 is to be removed from a bobbin 4 when the user starts using the yam.

The knitting in the areas 8 of the end parts of each cover 1 is knitted more dense than the knitting in the area 10 of the central part of the cover. This does not show directly from the knitting diagram but is established by controlling the knitting machine in a known way.

In figure 4 another knitting diagram is shown. In said knitting diagram knitting is shown both at the front 13 of the machine and at the reverse side 14 of the machine.

Said knitting diagram illustrates areas 8 and 10 of the end parts of the cover 1 and the central part, respectively. In said figure yams 15, 16 are illustrated, which are used

when knitting together the front and the reverse sides in order to form the tubular cover 1 For the sake of clearness the threads 9 have been left out

In practice, it will also be possible to leave out the elastic threads 9, provided that a sufficiently dense knitting is used in the areas 8 of the end parts of the cover 1