EP1232112B1

EP1232112B1 - Yarn supply device

Info

Publication number: EP1232112B1
Application number: EP00986081A
Authority: EP
Inventors: Paul Gunneman
Original assignee: Te Strake Textile BV
Current assignee: Te Strake Textile BV
Priority date: 1999-11-25
Filing date: 2000-11-22
Publication date: 2004-04-21
Anticipated expiration: 2020-11-22
Also published as: NL1013672C1; DE60010116D1; EP1232112A1; DE60010116T2; CN1399611A; JP2003514738A; CN1162314C; WO2001038216A1; AU2237801A

Abstract

A device for guiding a yarn which is unwound from the front end of a yarn supply drum (2) of a yarn feeder unit for looms, which device comprises a hollow body, which is disposed co-axially and in line with the yarn supply drum, wherein the hollow body (7) has a larger diameter at its entry side facing towards the drum (2) than at its exit side facing away from the drum, and wherein the hollow body includes a first axial zone adjoining the entry side and a second axial zone adjoining the exit side, and wherein the hollow body has an outlet eye (10) at its exit side, wherein one or more axially spaced-apart, inwardly projecting ribs (11), which each lie in a separate plane extending transversely to the central axis of the hollow body, are present at least on the internal surface of the outlet eye (10) and possibly also of said second zone.

Description

The invention relates to a device for guiding a yarn which is unwound from the front end of a yarn supply drum of a yarn feeder unit for looms, which device comprises a hollow body, which is disposed co-axially and in line with the yarn supply drum, wherein the hollow body has a larger diameter at its entry side facing towards the drum than at its exit side facing away from the drum, and wherein the hollow body includes a first axial zone adjoining the entry side and a second axial zone adjoining the exit side, and wherein the hollow body has an outlet device at its exit side.
Devices of the kind referred to above are generally known, for brevity's sake they are also called antiballoon devices. Devices of this kind are used with looms, wherein the weft thread is fed from a bobbin to the weft section of the loom via a yarn feeder. In the yarn feeder, a specific amount of yarn is wound onto a yarn supply drum, which may or may not take place in separate windings. From said supply drum the yarn runs over the front end of the drum to the weft section of the loom, whereby the yarn is transported at a high velocity, for example by means of air jet injectors.
A problem which occurs thereby is that the yarn, upon being unwound from the drum at a high velocity, tends to form a so-called balloon, which leads to all kinds of problems. In the first place there is a spatial problem, since the balloon, once it becomes too large, tends to strike against other parts of the device. A second problem is the fact that the balloon, as a result of the centrifugal forces occurring therein, causes the tension in the weft thread to increase, which eventually has an adverse effect on the quality of the woven product and on the feeding capacity of the loom.
In order to overcome these problems at least in part, many embodiments of this type of devices have been proposed already. A large number of embodiments of this type of devices are for example disclosed in WO-A-95/18059. From said publication it is known, among other things, to design the device in question as a hollow body in the form of a truncated cone having a smooth internal surface. The internal surface may thereby be made up of a truncated cone, which is in one piece, or of a combination of two conical surfaces having different apex angles. The drawback of such a hollow body having a smooth internal surface is the fact that the yarn encounters a lot of friction due to its contact with said smooth internal surface, which leads to a high yarn tension. In another prior art embodiment the truncated cone comprises a number of inwardly projecting interrupting and braking means in the form of studs or ribs on its internal surface provided. Said studs or ribs indeed reduce the degree to which the yarn and the inside surface of the cone are in contact with each other, which leads to a lower yarn tension, but the effect achieved by means of these devices is still unsatisfactory.
The object of the present invention is to provide a device of the kind referred to above which exhibits an improved operation, and to this end it is characterized in that one or more axially spaced-apart, inwardly projecting ribs, which each lie in a separate plane extending transversely to the central axis of the hollow body, are present on the internal surface of the outlet device eye. In another embodiment one or more axially spaced-apart ribs, which project inwardly and which each lie in a separate plane extending transversely to the central axis of the hollow body, are present on the internal surface of the aforesaid second zone of the hollow body as well.
Surprisingly, it has become apparent that the aforesaid ribs, which lie in planes that extend transversely to the central axis of the hollow body, have a positive effect on the operation of the device, in the sense that the tension in the weft thread running through the device is further reduced, whilst also the forming of a balloon is further prevented.
In looms the yarn can be wound onto the supply drum by means of a winding arm which rotates in clockwise or in anti-clockwise direction. This means that the yarn windings on the supply drum can lie in planes which extend obliquely in a direction opposed to the direction of the central axis of the supply drum. This means also that the unwound yarn windings can lie in planes which extend obliquely in a direction opposed to the direction of the central axis of the hollow body.
When the aforesaid ribs each lie in a plane extending at a specific angle with respect to the central axis of the hollow body, such a device can only be used either for a yarn which has been wound onto the supply drum in clockwise direction or for a yarn which has been wound onto the supply drum in anti-clockwise direction. The consequence of this is that a different kind of unwinding device will be needed for each winding direction of the yarn onto the supply drum. In order to overcome this problem, another embodiment of the device according to the invention is characterized in that each of said ribs lies in a plane which extends at least substantially perpendicularly to the central axis of the hollow body. When the ribs lie in such a plane extending perpendicularly to the central axis of the hollow body, such ribs will have an influence on the yarn being unwound, which influence is the same for each winding direction of the yarn onto the yarn supply drum. Consequently this means that the unwinding direction need not be changed when the winding direction is being changed.
Although the ribs may have an interrupted shape in their associated planes, so that a number of segments of a circle are formed in each plane, it has become apparent that it is advantageous according to the invention to have the ribs form a continuous, closed circular ring over the inner circumference of the hollow body in their associated planes.
In another advantageous embodiment of the device according to the invention said first and said second zone are each made up of a frustoconical surface, wherein the exit side of the first zone adjoins the entry side of the second zone. The apex angle of the conical surface of the first zone may be smaller thereby than that of the second zone.
According to the invention the hollow body may have a smooth internal surface in the aforesaid first axial zone, but it is also possible to form inwardly projecting unevennesses, which function as interrupting and braking means for the yarn, on the internal surface of the first zone of the hollow body. Said unevennesses may thereby be made up of corrugations or ribs extending substantially along the generating line of the conical surface.
The invention will now be explained in more detail with reference to the drawing, wherein a few embodiments of the device according to the invention are shown by way of example.
Figure 1 is a schematic view, not to scale, of a yarn feeder device.
Figures 2 and 3 are schematic, sectional views, not to scale, of two embodiments of the device according to the invention.
Figure 4 is a schematic, sectional view, not to scale, of another embodiment of the device according to the invention.
Figures 5 and 6 are sectional views of two possible embodiments of the device shown in Figure 4.
In Figure 1, numeral 1 indicates a frame carrying a winding drum 2. Yarn 4 is wound from a bobbin 3 onto yarn winding drum 2 by means of a winding arm 5, from which drum the yarn 4 is unwound by an air jet injector (not shown) of a loom. Frame 1 furthermore carries a stop element 6, which comes into operation the moment the unwinding of yarn 4 from the winding drum 2 is co be stopped. Disposed in line with the winding drum 2, co-axially therewith, is an unwinding device 7, which unwinding device 7 is frustoconical in shape and which has a smooth internal surface and a schematically indicated outlet device 10. Winding arm 5 winds a supply of windings 8 onto winding drum 2, after which the yarn 4 is led to the loom over the front end of winding drum 8. A balloon 9 forms in the yarn thereby, which balloon has the aforesaid adverse effect on the yarn tension and which needs to be reduced as much as possible by unwinding device 7. It is not possible to achieve an optimum result with an unwinding device 7 having a smooth internal surface as shown in Figure 1. In order to bring about improvement in this regard, the unwinding device 7 that is schematically shown in Figure 2 is provided with an outlet eye 10, which is made of a wear-resistant material having good yarn guiding properties, and whose internal surface is provided with projecting ribs 11, which each lie in a separate plane, which extends perpendicularly to the central axis. It has become apparent that such ribs have a positive influence both on the yarn tension and on the dimensions of the balloon 9. A further improvement can be achieved by forming the second zone 29 of the hollow body, which adjoins the exit side, with three ribs 30, as is schematically indicated in Figure 3, which ribs project inwardly and which each lie in a plane which extends practically perpendicularly to the central axis 31 of the device. Although the embodiment is shown to comprise three ribs 30, it will be apparent that the number of ribs may vary, depending on the conditions of operation. In the drawing the ribs are shown to be disposed in axially spaced-apart relationship on the conical surface, but it is also possible to arrange the ribs so closely together that they adjoin each other to form a corrugated pattern. Furthermore the ribs may have mutually different heights. Surprisingly it has become apparent that such ribs 30 have a further positive influence both on the yarn tension and on the dimensions of the balloon 9. Although the device according to Figure 2 is made up of one frustoconical surface, it will be apparent that, as is schematically shown in Figure 4, zones 28 and 29 may also be made up of frustoconical surfaces having different apex angles.
In the devices according to Figures 2 and 3, zone 28 is in the form of a hollow frustoconical surface having a smooth internal surface. It has become apparent that a further improvement of the device can be achieved by forming projecting interrupting and braking means, which may for example consist of ribs 32, on the internal surface of first zone 28, as is shown in Figure 5. Said ribs 32 thereby extend approximately along the generating line of the frustoconical surface, and they may be distributed separately over the internal surface of the hollow cone, as is shown in Figure 5, whereby the ribs may be spaced a constant or a varying distance apart.
As is shown in Figure 7, it is also possible, however, to distribute the ribs 32 in a corrugated pattern over the internal surface, with one corrugation directly adjoining the other. Instead of being arranged in a corrugated pattern, the ribs 32 may also be arranged in a zig-zag pattern with slightly rounded peaks. It is noted that for the sake of clarity the cut outlet device eye 10 of the devices that are shown in Figures 3, 4 and 5 is not shown.

Claims

A device for guiding a yarn which is unwound from the front end of a yarn supply drum (2) of a yarn feeder unit for looms, which device comprises a hollow body (7), which is disposed co-axially and in line with the yarn supply drum (2), wherein the hollow body (7) has a larger diameter at its entry side facing towards the drum than at its exit side facing away from the drum, and wherein the hollow body includes a first axial zone (21) adjoining the entry side and a second axial zone (29) adjoining the exit side, and wherein the hollow body (7) has an outlet device (10) at its exit side, characterized in that one or more axially spaced-apart, inwardly projecting ribs (11), which each lie in a separate plane extending transversely to the central axis of the hollow body (1), are present at least on the internal surface of the outlet device (10).
A device according to claim 1, characterized in that one or more axially spaced-apart ribs (30), which project inwardly and which each lie in a separate plane extending transversely to the central axis of the hollow body, are present on the internal surface of the aforesaid second zone (29) of the hollow body (7).
A device according to claim 1 or 2, characterized in that each of said ribs (11,30) lies in a plane which extends at least substantially perpendicularly to the central axis of the hollow body (7).
A device according to claim 1, 2 or 3, characterized in that each of the ribs (11, 30) form a continuous, closed circular ring over the inner circumference of the hollow body (7) in their associated planes.
A device according to claim 1 , 2, 3 or 4, characterized in that said first and said second zone (28, 29), are made up of a frustoconical surface, wherein the exit side of said first zone adjoins the entry side of the second zone.
A device according to claim 5, characterized in that the apex angle of the conical surface of the first zone (28) is smaller than that of the second zone (29).
A device according to any one or more of the preceding claims, characterized in that the hollow body (7) in said first axial zone has a smooth internal surface.
A device according to any one or more of the claims 1 - 6, characterized in that inwardly projecting unevennesses (32) are present in said first zone (28) of the hollow body, which unevennesses (32) function as interrupting and braking means for the yarn.
A device according to claim 8, characterized in that said unevennesses (32) are made up of corrugations or ribs extending substantially along the generating line of the conical surface.