EP0458078A1

EP0458078A1 - Method and device to tear roving in spinning machines

Info

Publication number: EP0458078A1
Application number: EP91106652A
Authority: EP
Inventors: Mirko Marchiori
Original assignee: S BIGAGLI AND C SpA
Current assignee: S BIGAGLI AND C SpA
Priority date: 1990-05-22
Filing date: 1991-04-25
Publication date: 1991-11-27
Also published as: IT1240889B; IT9083388A1; IT9083388A0

Abstract

Tearing method in spinning machines, the tearing being suitable to break the segment of roving (12) leaving a drafting unit (11) and held by an aspiration intake (15) following upon a breakage of yarn on the respective spinning unit, the tearing being required for piecing-up of the yarn, the tearing of the roving (12) taking place by a drawing action on the segment of roving (12) between the drafting unit (11) and the intake (15), the drawing action being of a value such as to cause separation of the fibres composing the roving (12) and therefore the breakage of the roving (12).

Device to tear roving in spinning machines, the tearing being suitable to break the segment of roving (12) leaving a drafting unit (11) and held by an aspiration intake (15) following upon a breakage of a yarn on the respective spinning unit, the tearing being required for piecing-up of the yarn, the device employing the method cited above, the device consisting of an additional drawing unit (16) for each spinning unit, the drawing unit (16) consisting of a tearing roller (17) and a pressure roller (18) located between the outlet of a drafting roller (13) of the drafting unit (11) and the inlet of the aspiration intake (15), the tearing roller (17) and pressure roller (18) being separated from each other in their inactive positions, one of these rollers (17-18) being secured to means (19) that cause temporary reciprocal approach of the rollers (17-18), one of the rollers (17-18) being powered.

Description

This invention concerns a method and device to tear roving in spinning machines. To be more exact, the invention concerns a method and device suitable to break the continuity of the roving leaving the drafting unit at the moment when the yarn is pieced up after being broken, the piecing-up taking place on one single spinning unit while the spinning machine is working.
The invention is applied to textile materials of any type which possess properties such as will ensure cohesion of the roving leaving the drafting unit and aspirated by the aspiration device.
It is known that in every spinning unit belonging to a spinning machine the relative roving leaving the drafting unit is aspirated by a suitably positioned aspiration device when the yarn is broken.
In the event of the above cited textile materials, such as carded yarns for instance, when it is necessary to piece up the yarn by means of a splice, the segment of roving between the drafting unit, or the zone of the splice, and the aspiration device generally has to be broken; this is required to prevent this segment of roving becoming incorporated in the splice together with a possibly long further segment withdrawn from the aspiration conduit, with a resulting irregularity of the splice or even a breakage of the same.
It is therefore necessary, as we said, at the moment of the piecing-up, to break that segment of roving in synchronization with the formation of the splice.
In the state of the art this operation is done by hand. The machine operator work with both hands, one of them taking the end of the yarn to be spliced into contact with the roving leaving the drafting unit, while the other hand, at the moment of contact between the yarn and the roving, breaks at the same time the segment of roving between the zone of the splice and the aspiration device.
This breakage takes place by tearing, and the faster and better synchronized this tearing is with the contact between the yarn and the roving, the shorter and less visible will be the splice.
Thus the result of the splice is entrusted to the skill of the machine operator, who meets with ever greater difficulties owing to the increase of the output speed of the roving from the drafting unit.
In the case of certain particularly high speeds the piecing-up operation in fact cannot be carried out by hand and auxiliary devices have to be used. Scissors, blades or other devices are employed which operate laterally on the roving; jets of compressed air are also used which are directed along the axis of the roving but only achieve uncertain and not reliable results.
In fact, the roving does not break, or its breakage is not achieved with the required speed and synchronization mentioned above.
It should also be borne in mind that breakage by hand is itself a hard operation to carry out since the operator has to work on a segment of roving which can hardly be controlled, has a low tension and can be readily pulled from the aspiration conduit.
Moreover, the roving is fed continuously from the drafting unit, and therefore a sideways displacement, for instance, of the roving leaving the drafting unit so as to cause its breakage has a scanty effect.
The present applicant has studied, tested and provided a method and relative device suitable to overcome all the problems of the state of the art.
The invention is set forth in the main claims, while the dependent claims describe various features of the invention.
The invention provides for the breakage or tearing of the roving to be achieved by a drawing action exerted between the outlet of the drafting unit and the inlet of the aspiration intake.
By causing a drawing action of a required value, which can be adjusted to suit the properties of the textile material being processed and the operational conditions of the spinning machine, the fibres of the roving are detached from each other and the roving is therefore broken.
To obtain this result, the invention provides for each spinning unit to be equipped with an additional drawing unit positioned at the aspiration intake. The additional drawing unit consists advantageously of a powered tearing roller and a pressure roller which cooperates momentarily with the tearing roller.
The peripheral speed of the tearing roller can be regulated and is normally kept much higher than the speed of the drafting roller of the drafting unit so as to achieve breakage of the roving in a very short time.
The breakage occurs in a short period of time after contact of the pressure roller with the tearing roller.
The additional drawing unit is positioned advantageously behind the path of the yarn on the spinning unit, that is to say, the additional drawing unit is placed towards the inside of the spinning machine. In this way it does not hinder the machine operator performing the piecing-up.
The method and device of the invention accomplish a plurality of advantages. Among these advantages, it should be borne in mind, is the fact that the segment of roving to be broken is held firmly between two nip points, namely the outlet of the drafting unit and inlet of the tearing roller, and therefore there is no possibility of a withdrawal and departure of the segment of roving from the aspiration intake.
Moreover, the existence of the two nip points ensures breakage of the roving even where very strong materials are in question such as, for instance, roving containing long manmade fibres, since very strong forces can be applied to the roving.
Furthermore, the portion of roving located downstream of the breakage point is accompanied by the additional tearing unit towards the inlet of the aspiration intake, thereby enhancing the distancing and discharge of the fibres of the torn roving.
Besides, such a tearing of the roving does not cause any disturbance of the segment of yarn coming from the yarn package being formed and brought by the machine operator below the pressure roller as that segment leaves the drafting unit during the piecing-up operation.
These and other special features of the invention will be made clearer in the description that follows.
The attached figures, which are given as a non-restrictive example, show the following:-

Fig.1: is a partial frontal diagram of two neighbouring spinning units together with the device of the invention during a normal spinning step;
Fig.2: is a partial three-dimensional view of Fig.1 during the step following a breakage of the yarn, with the roving from the drafting unit aspirated by the aspiration intake;
Fig.3: shows a front view of the step of positioning the yarn brought from the take-up package for piecing-up with the roving;
Fig.4: is a front view of the step of tearing the roving and the successive splicing of the yarn.

A part of a spinning machine is referenced with 10 in Fig.1 and includes two spinning positions or spinning units at a zone of output of a drafting unit 11.
An intake 15 to aspirate roving 12 normally cooperates with the roving 12 leaving the last drafting assembly of the drafting unit 11, this assembly consisting of a drafting roller 13 and relative pressure roller 14.
The intake 15 has the task of aspirating and retaining the roving 12 when a spinning breakage takes place.
According to the invention a device 16 to tear the roving 12 is provided between the exit from the drafting unit 11 and the entry to the twisting-winding means (for instance, the spindle of a ring spinning machine, which is not shown in the figures) of the spinning machine in correspondence with the zone of activity of the roving aspiration intake 15.
The tearing device 16 consists of a drawing unit formed by a tearing roller 17 and a relative pressure roller 18.
The pressure roller 18, which is equipped with a resilient coating, is solidly fixed to a resilient plate 19 secured to the structure of the spinning machine, whereas the tearing roller 17, which too is secured to the structure of the spinning machine, is suitably powered.
According to a preferred embodiment of the invention two pressure rollers 18 are solidly fixed to each resilient plate 19 and act at the same time on two adjacent spinning positions when the respective resilient plate 19 is thrust downwards.
This embodiment offers the advantage of ensuring a good support of the pressure rollers 18 on the relative tearing rollers 17, thereby achieving an efficient gripping of the roving 12 and a simplified structure of the drawing unit 16.
The tearing roller 17 extends advantageously along the whole side of the spinning machine and may include in correspondence with the pressure rollers 18 a knurled area, referenced with 17 in the figures, so as to enhance the gripping of the roving 12.
When the spinning machine is working, the tearing roller 17 is kept in continual rotation, and its speed of rotation can be regulated by a suitable control system and be varied in relation to the speed of output of roving 12 by the drafting unit 11.
The pressure rollers 18 in their inactive position are separated from the tearing roller 17 and are halted.
The tearing roller 17 and pressure roller 18 are located behind the path of the yarn 20 towards the interior of the spinning machine. The purpose of this is to make possible the piecing-up, which requires the end of the yarn 20 coming from the yarn package to be brought to the drafting roller 13 solidly fixed to the drafting unit 11.
The tearing roller 17 is positioned in correspondence with the aspiration intake 15 and immediately thereunder; the pressure roller 18 in its inactive position is always in the neighbourhood of the aspiration intake 15 but is immediately thereabove.
With such an arrangement, when the yarn breaks, the roving 12 is aspirated by the intake 15 and is positioned between the tearing roller 17 and pressure roller 18; in this way it is already ready to be torn by the device 16.
Fig.1 shows the position of the roving tearing device 16 during a normal spinning step, while Fig.2 shows a spinning unit after breakage of the yarn, the roving 12 having been aspirated by the intake 15 while the tearing device 16 is still in its inactive position.
Fig.3 shows an operational step in which the machine operator positions with one hand the end of the yarn 20 to be pieced up in correspondence with the drafting unit 13-14 and prepares to actuate the tearing device 16 with his other hand.
Fig.4 shows the final step of the piecing-up, in which the end of the yarn 20 has been inserted under the pressure roller 14 of the drafting unit 11 and piecing-up has taken place, while the segment of roving 12 has been torn by the pressure roller 18 being brought down into contact with the tearing roller 17.
Only at the moment when the machine operator brings the pressure roller 18 into contact with the rotating tearing roller 17 by applying pressure to the resilient plate 19 is there an instantaneous acceleration of the pressure roller 18, which grips and draws the fibres of the roving 12 until the roving breaks.
The resilient plate 19 is positioned advantageously at the space between two neighbouring spinning units, thereby keeping the space occupied by the device 16 to a minimum and making easy the operation of the device by the operator.
Many variants of the idea of the embodiment are possible without departing thereby from the scope of the invention as claimed. For instance, a solution can be embodied in which the pressure rollers 18 of the device are powered, while the tearing rollers 17, individually or in pairs, are momentarily brought up to and thrust against the pressure rollers 18.
According to a variant the tearing can also be obtained by means of two small pressure rollers of which one is powered or driven.
A variant is also possible in which the tearing roller 17 is coated with a resilient material, while the pressure rollers 18 have knurled surfaces.
Moreover, the tearing roller 17 may not extend along the whole spinning machine but may, for instance, be single or in a powered pair; it can also be arranged that the tearing roller or rollers is/are normally halted and only actuated by the operator during a piecing-up step.

Claims

Tearing method in spinning machines, the tearing being suitable to break the segment of roving (12) leaving a drafting unit (11) and held by an aspiration intake (15) following upon a breakage of yarn on the respective spinning unit, the tearing being required for piecing-up of the yarn, the method being characterized in that the tearing of the roving (12) takes place by a drawing action on the segment of roving (12) between the drafting unit (11) and the intake (15), the drawing action being of a value such as to cause separation of the fibres composing the roving (12) and therefore the breakage of the roving (12).
Method as claimed in Claim 1, in which the breakage of the roving (12) takes place in the segment of roving (12) between the output drafting roller (13) of the drafting unit (11) and the inlet of the aspiration intake (15).
Method as claimed in Claim 1 or 2, in which the breakage of the roving (12) takes place in a zone behind the path of the yarn during normal spinning.
Method as claimed in any claim hereinbefore, in which the breakage of the roving (12) takes place in conjunction with the insertion of the end of the yarn (20), brought from a yarn take-up package, between a pressure roller (14) of the drafting unit (11) and the drafting roller (13) of the drafting unit (11) in making a splice.
Method as claimed in any claim hereinbefore, in which the breakage of the roving (12) takes place by a temporary approach and contact of a pressure means (18) against a tearing means (17).
Method as claimed in any of Claims 1 to 4 inclusive, in which the breakage of the roving (12) takes place by a temporary approach and contact of a tearing means (17) against a pressure means (18).
Method as claimed in any claim hereinbefore, in which the speed of tearing the roving (12) can vary according to the properties of the textile material being processed and the operational spinning conditions.
Device to tear roving in spinning machines, the tearing being suitable to break the segment of roving (12) leaving a drafting unit (11) and held by an aspiration intake (15) following upon a breakage of a yarn on the respective spinning unit, the tearing being required for piecing-up of the yarn, the device employing the method of the claims hereinbefore and being characterized in that it consists of an additional drawing unit (16) for each spinning unit, the drawing unit (16) consisting of a tearing roller (17) and a pressure roller (18) located between the outlet of a drafting roller (13) of the drafting unit (11) and the inlet of the aspiration intake (15), the tearing roller (17) and pressure roller (18) being separated from each other in their inactive positions, one of these rollers (17-18) being secured to means (19) that cause temporary reciprocal approach of the rollers (17-18), one of the rollers (17-18) being powered.
Device as claimed in Claim 8, in which the tearing roller (17) and pressure roller (18) are positioned behind the path of the yarn during normal spinning.
Device as claimed in Claim 8 or 9, in which the tearing roller (17) is located immediately below the aspiration intake (15), whereas the pressure roller (18) in its inactive position is located immediately above the aspiration intake (15).
Device as claimed in any of Claims 8 to 10 inclusive, in which the tearing roller (17) is one single roller that extends along the whole side of the spinning machine.
Device as claimed in any of Claims 8 to 11 inclusive, in which the tearing roller (17) is equipped with its own motor possessing the capability of changing its speed as required.
Device as claimed in any of Claims 8 to 11 inclusive, in which the pressure roller (18) is equipped with its own motor possessing the capability of changing its speed as required.
Device as claimed in any of Claims 8 to 13 inclusive, in which the tearing roller (17) has a knurled surface, whereas the pressure roller (18) is coated with a resilient material, or viceversa.
Device as claimed in any of Claims 8 to 14 inclusive, in which pressure rollers (18) are arranged in pairs and connected to one single, common, resilient actuation means (19).
Device as claimed in any of Claims 8 to 15 inclusive, in which the resilient actuation means (19) is located in a position between two neighbouring spinning units.
Device as claimed in any of Claims 8 to 16 inclusive, which consists of two small pressure rollers of which one is driven or powered.