Bobbin utilized for making yarn packages in textile machines

Disclosed is a cone bobbin utilized for making a yarn package thereon. The bobbin is provided with a main portion having a shape of a frustum of a cone, whereon the yarn package can be formed. From the bottom end of the main portion, a cylindrical bottom end portion of the bobbin is coaxially extended toward the outside, and a reserve winding can be formed on this bottom end portion.

SUMMARY OF THE INVENTION 
The present invention relates to a bobbin utilized for making yarn packages 
in textile machines such as a winding or rewinding machine or a twisting 
machine. 
In textile factories, when rewound yarn packages are produced by each unit 
of a winding machine by a plurality of yarn packages, such as parallel 
cheeses or cone cheeses, it is quite common to use a plurality of yarn 
packages in such a way that an end of a wound yarn of a second yarn 
package is connected to a reverse winding of a first yarn package from 
which a material yarn is being supplied to produce a rewound yarn package, 
and an end of a wound yarn of a third yarn package is connected to a 
reserve winding of the second yarn package, an end of a wound yarn of a 
fourth yarn package is connected to a reverse winding of the third yarn 
package, and so on. Therefore, the yarns of these yarn packages are 
connected so as to form a continuous yarn. The above-mentioned reserve 
winding is formed at a bottom portion of a bobbin whereon the main portion 
of the yarn package is formed. When the above-mentioned connection between 
two yarn packages is formed, it is usual to take off the reserve winding 
from the bobbin by manually displacing the reserve winding along the 
longitudinal axis thereof toward the bobbin end. 
In a case of utilizing cone cheeses as the material yarn packages, the cone 
cheese is formed on a cone bobbin. The above-mentioned reserve winding is 
formed on the bottom portion of the cone bobbin where the cross-sectional 
diameter thereof gradually increases along the longitudinal axis thereof 
toward the bottom end. Therefore, when the reserve winding is removed from 
the bottom portion of the cone bobbin, since the cross-sectional diameter 
of the bobbin is gradually increased toward the bobbin end, it is 
necessary to provide a strong force to remove the reserve winding from the 
bottom portion of the bobbin. If a yarn of small extendability, such as a 
cotton yarn, is used as a material yarn, the above-mentioned manual 
operation for removing the reserve winding from the cone bobbin is a very 
troublesome job so that the overall working efficiency is remarkably 
lowered. Such problem is particularly realized in the case of utilizing 
the cone bobbin having a larger taper. 
The purpose of the present invention is to provide a cone bobbin having a 
particularly shaped bottom portion which solves the above-mentioned 
problem. 
To attain the purpose of the present invention, the cone bobbin according 
to the present invention is provided with a bottom portion having a 
cylindrical shape and the remaining portion thereof having a conical shape 
so that the cross-sectional diameter thereof is gradually decreased toward 
the tip end of the bobbin.

DETAILED EXPLANATION OF THE INVENTION 
For the sake of a better understanding of the characteristic feature of the 
present invention, the problem related to the utilization of the 
conventional cone bobbin, which was previously discussed, is hereinafter 
explained again with reference to FIGS. 1 and 2. The yarn package 1 is 
formed on a conventional cone bobbin 2 provided with a cone shaped 
surface. In this yarn package 1, a reserve winding 1a composed of a 
plurality of windings is formed on a bottom portion 2a of the cone bobbin 
2 and an end 1b of the wound yarn is placed on the most outside layer of 
the yarn package 1. When it is required to connect the yarn of three 
adjacent yarn packages 1 of a group of yarn packages, the reserve winding 
1a of a first yarn package 1 is connected to the end 1b of the wound yarn 
of a second yarn package 1, while the reserve winding 1a of the second 
yarn package 1 is connected to the end 1b of the wound yarn of a third 
yarn package 1. Therefore, when the yarns of three adjacent yarn packages 
1 are connected as shown in FIG. 2, it is necessary to displace the 
reserve winding 2a of each yarn package 1 toward the end of its cone 
bobbin 2 having the largest cross-sectional diameter. Since the windings 
of the reserve winding 1a are tightly formed on the bottom end portion 2a 
of the cone bobbin 2, it is very difficult to smoothly remove the reserve 
winding 1a from the cone bobbin 2. 
The cone bobbin 2 according to the present invention, shown in FIG. 3, is 
composed of a main portion 2b having a shape of a frustum of a cone, 
wherein the cross-sectional diameter thereof is gradually decreased along 
the lengthwise direction toward the tip end thereof, and a cylindrical 
bottom portion 2a. The main portion 2b is a portion whereon the yarn 
layers of the cone cheese is formed, while the reserve winding is formed 
on the cylindrical bottom portion 2a of the bobbin 2. Therefore, when it 
is required to remove the reserve winding from the bottom portion 2a of 
the bobbin 2, since the cross-sectional diameter of the bobbin 2 is not 
changed in this bottom portion 2a, the reserve winding can be easily 
displaced toward the end of the bottom portion 2a. As a result, the 
above-mentioned problem observed in the utilization of the conventional 
cone cheese can be completely eliminated. 
In addition to the above-mentioned advantage of the cone bobbin according 
to the present invention, the following advantage can be expected. That 
is, in the case of utilizing a conventional cone bobbin, when the reserve 
winding 1a is formed on the bobbin 2, the bottom end portion 2a of the 
bobbin 2 frictionally contacts a driving roller of a winding mechanism 
(not shown). Therefore, the bottom end portion 2a works to transmit the 
driving force from the driving roller to the bobbin 2. When the yarn is 
introduced into the range of the transverse guide motion of the winding 
mechanism, the contact point of the bobbin with the driving roller is 
changed to the position in the range of the transverse guide motion and, 
therefore, the tension of the winding yarn varies during the initial stage 
of forming the yarn package 1. However, in the case of utilizing the cone 
bobbin 2 according to the present invention, since the main portion 2b of 
the bobbin contact the driving roller, while the bottom end portion 2a of 
the bobbin 2 does not contact the driving roller, the above-mentioned 
possible variation of the yarn tension during the yarn package forming 
operation on the cone bobbin can be completely avoided so that a cone 
cheese having an excellent cone shape can be produced. 
In the embodiment shown in FIG. 4, a plurality of ring shaped grooves 3 are 
formed on the cone surface of the main portion 2b of the bobbin 2, and a 
plurality of grooves 4 are formed on the cylindrical surface of the end 
portion 2a in parallel condition to the longitudinal axis of the cone 
bobbin 2. The ring shaped grooves 3 have been also applied to the 
conventional cone bobbin so as to prevent the possible displacement of a 
bottom yarn layer in the longitudinal direction of the bobbin. However, it 
must be noted that, in the conventional cone bobbin, the above-mentioned 
ring shaped grooves are also formed on the surface of the bottom end 
portion of the bobbin and, therefore, the abovementioned problem observed 
when the reserve winding is removed from the bobbin is aggravated. 
However, in this embodiment, the grooves 4 do not interfere with the 
removing motion of the reserved winding 1a from the bobbin 2 but, rather, 
allow a smoother removal the reserve winding 1a from the bobbin 2 compared 
with the first embodiment shown in FIG. 3.