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Title:
METHOD OF CONTROLLING THE DRAFTING OF A FIBRE WEB IN A CARD APPARATUS
Document Type and Number:
WIPO Patent Application WO/2014/125401
Kind Code:
A1
Abstract:
A method of controlling the drafting (S) of a fibre web in a card apparatus provides for a drafting change step (t1-t2) at minimum speed (VA') and a subsequent constant drafting step (t3-t4) and a speed increase (VA").

Inventors:
MASCHERETTI MARIO (IT)
GIAVARINI MATTEO (IT)
Application Number:
PCT/IB2014/058833
Publication Date:
August 21, 2014
Filing Date:
February 06, 2014
Export Citation:
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Assignee:
MARZOLI MACHINES TEXTILE SRL (IT)
International Classes:
D01G15/36
Foreign References:
EP1001058A12000-05-17
GB2273508A1994-06-22
US4089232A1978-05-16
GB2273508A1994-06-22
Attorney, Agent or Firm:
PULIERI, Gianluca Antonio et al. (Piazza della Vittoria 11, Brescia, IT)
Download PDF:
Claims:
Claims

1. Method of controlling the drafting of a fibre web or sliver between an upstream rotatable drafting body (18; 20; 22,24; 26; 30,32; 202,204; 206,208; 210,212; 44,46) and a downstream rotatable drafting body, situated in the extraction zone of a card apparatus (1) , wherein

- in a drafting change step, the drafting value increases from a lower value (S') to a higher value (S") while keeping the rotation of the upstream drafting body (Va') constant and varying the speed of rotation of the downstream drafting body (Vb) and subsequently

- in a constant drafting step, increasing the speed of rotation of the upstream drafting body and the downstream drafting body from a lower value (Va ' , Vb ' ) to a higher value (Va'1), (Vb'') while the drafting value remains constant .

2. Method according to claim 1, wherein the drafting change step takes place prior to a pre-processing step in which the speed of rotation of the upstream body and the speed of rotation of the downstream body increases, while the drafting remains constant.

3. Method according to claim 1 or 2, wherein between the drafting change step and the constant drafting step, an intermediate step is conducted, in which the speed of rotation of the upstream drafting body and the downstream drafting body remains constant and equal to the lower value and the drafting value remains constant and equal to the upper value.

4. Method according to any of the previous claims, in which the web is channelled to a can (48) of a coiler group (40) of the card apparatus (1) only when the drafting value is equal to the upper value or the speed of rotation of the upstream drafting body and of the downstream drafting body is equal to the upper value. 5. Method according to any of the previous claims, in which the lower and/or upper value of the drafting and/or the lower and/or upper value of the speed of rotation of the upstream drafting body and of the downstream drafting body are manually set by an operator in a control unit (100) of the card apparatus (1) or in which the lower and/or upper value of the drafting and/or the lower and/or upper value of the speed of rotation of the upstream drafting body and of the downstream drafting body are supplied to a control device (50) from a storage unit (54) .

6. Method according to any of the previous claims, wherein the increase of the drafting from the lower value to the upper value starts by intervention of the operator.

7. Method according to any of the previous claims, wherein the increase of the drafting from the lower value to the upper value starts automatically, for example by means of a timer signal (58) or a sensor (56) .

8. Method according to any of the previous claims, wherein

- between an initial drafting body and a final drafting body a total drafting (St) is defined ; and

between said initial drafting body and said final drafting body intermediate drafting bodies are provided so that the final drafting value is defined as the product of the intermediate drafting values; and in which

- at least one of said intermediate drafting values (Si) is automatically identified by a control unit (100) .

9. Control unit (100) for performing a control method according to any of the previous claims.

10. Method of controlling the drafting of a fibre web between a rotatable upstream drafting body (6, 8) and a rotatable downstream drafting body, situated in the feed area of a card apparatus (1), wherein

- in a drafting change step, the drafting value increases from a lower value (S") to a higher value (S") while keeping the rotation of the upstream drafting body (Va') constant and varying the speed of rotation of the downstream drafting body (Vb) and wherein

- in a subsequent constant drafting step, increasing the speed of rotation of the upstream drafting body and the downstream drafting body from a lower value (Va1, Vb 1 ) to a higher value (Va'', Vb ' 1 ) while the drafting value remains constant.

Description:
DESCRIPTION

"METHOD OF CONTROLLING THE DRAFTING OF A FIBRE WEB IN A

CARD APPARATUS"

[0001] The present invention relates to a method of controlling the drafting in a card apparatus on a yarn spinning line. Furthermore, the present invention relates to a control unit of the drafting of the card apparatus for performing the control method.

[0002] On a yarn spinning line, the fibre, for example in tufts, is first taken from bales, subjected to cleaning and opening operations and forwarded for carding.

[0003] Carding, as known, is an operation of primary importance, in that the fibre fed in tufts, is further cleaned and parallelised, coming out in the form of a web for subsequent processing.

[0004] A carding machine generally comprises an introduction cylinder or briseur, a main cylinder and an extraction cylinder or doffer. The introduction cylinder is positioned in a feed area upstream of the main cylinder, while the extraction cylinder is positioned in an extraction area downstream of the main cylinder. The fibre to be carded passes from the introduction cylinder to the main cylinder, while the carded fibre passes from the main cylinder to the extraction cylinder, it comes out of this in the form of a sliver, further compacted and drafted and stored in the form of a web in a can. The web then moves on for further processing.

[0005] Generally, the sliver coming out of the extraction cylinder is subjected to drafting operations, to obtain a web having a predefined gauge, suitable for the subsequent processing. Such operations generally take place by means of the passage of the web through pairs of calenders having different rotation speeds.

[0006] During the functioning of a carding machine, the cylinder speed is not constant for a variety of reasons; for example it is often necessary to vary the speed to regulate the height of the web coming out of the extraction cylinder or depending on the type of fibre being processed or simply on account of the different of functioning phases of the machine.

[0007] For example, when starting processing, a threading step takes place, during which the fibre begins to be fed from the main cylinder and begins to come out in the form of a web from the extraction cylinder; the threading step is conducted at a particularly reduced speed. A starting step generally follows, at a higher speed. Lastly, a processing step takes over, conducted at an even higher speed and according to functioning parameters which are able to ensure the desired quality and/or production of the web. [0008] A drafting control method is known of for controlling drafting according to speed, for example from the document GB-A-2273508.

[0009] However, it has been seen that the drafting control methods of the prior art have numerous drawbacks. For example, it has been seen how increasing the drafting concurrently with the speed considerably increases the risk of tearing the sliver or web and often leads to a web of unsatisfactory quality being obtained or, on account of the continuous work interruptions, insufficient production.

[0010] The purpose of the present invention is to overcome the drawbacks of the prior art and at the same time to satisfy the needs spoken of.

[0011] Such purpose is achieved by a drafting control method according to claim 1. In addition, such purpose is achieved by a control unit of the drafting according to claim 9.

[0012] The advantages of the control unit and method according to the present invention will be evident from the description given below, made by way of a non- limiting example, according to the appended drawings, wherein:

[0013] - figure 1 shows a diagram of a card apparatus comprising a silo unit, a carding machine and a coiler group;

[0014] - figure 2 shows a diagram of the extraction area of the card apparatus in figure 1, showing the references for the drafting devices;

[0015] - figure 3 shows a diagram of the extraction area of the card apparatus in figure 1, in which a control unit of the drafting is highlighted;

[0016]- figure 4 is a graph showing the upstream speed, downstream speed and drafting trend according to the method of the present invention; and

[0017] - figure 5 shows a drafting device of the carding machine for performing the drafting method according to the present invention.

[0018] According to the appended drawings, a card apparatus 1 comprises a silo group 2 provided with collection chamber 4 for the fibre in tufts, generally coming from blowroom machinery.

[0019] Preferably, the silo group 2 comprises a pair of counter-rotating extraction cylinders 6, 8', acting in conjunction to extract the fibre in tufts from the collection chamber 4.

[0020] The card apparatus 1 further comprises a feed chamber 10 fed by the extraction cylinders 6, 8, and a feed cylinder 12, placed at the end of the feed chamber 10. [0021] Furthermore, the carding machine comprises an introduction cylinder or briseur 14, a main cylinder 16 and an extraction cylinder or doffer 18.

[0022] The fibre extracted from the feed chamber 10 by the feed cylinder 12 moves onto the introduction cylinder 14 and from thence to the main cylinder 16, where it is carded.

[0023] The carded fibre moves from the main cylinder 16 to the extraction cylinder 18, placed in an extraction area downstream of the main cylinder 16.

[0024] Furthermore, in the extraction area, the carding machine comprises a stripper cylinder 20 and a pair of coupled pressure calenders 22, 24. The stripper cylinder 20 works on the fibre web transported by the extraction cylinder 18 so as to detach it therefrom, directing it towards the pair of pressure cylinders 22, 24 between which it generally undergoes a reduction of the thickness .

[0025] In addition, preferably, the carding machine comprises, in the extraction area, a compacting device 26, for example belt-operated, which transversally compacts the fibre web, until now substantially as wide as the width of the main cylinder, to obtain a cord- shaped web.

[0026] Furthermore, the carding machine comprises, in the extraction area, a funnel 26 and a pair of output calenders 30, 32 downstream of the funnel 26. The web first passes through the funnel 26 and then through the output calenders 30, 32.

[0027] In addition, the card apparatus 1 comprises a coiler group 40 for collecting the web in output from the carding machine, positioned in the extraction area.

[0028] Preferably, the coiler group 40 comprises several rollers 42 for guiding the web in output, a pair of input calenders 44, 46 and a can 48, usually rotatable. The web in output from the output calenders 30, 32 is appropriately deviated towards the rollers 42 and made to pass through the input calenders 44, 46 to then deposit itself in the rotating can 48.

[0029] The extent of the drafting is defined by a "drafting" parameter, defined by the ratio of the rotation speed of a downstream body, such as a cylinder, a pair of calenders or the compacting device belt, and the rotation speed of a body upstream of the previous, for example a cylinder, a pair of calenders or the compacting device belt.

[0030] In the extraction area of the carding machine, it is thus possible to define multiple draftings, depending on the drafting bodies taken into consideration.

[0031] For example (figure 2), the drafting Si between the stripper cylinder 20 and the extraction cylinder 18 is defined as the ratio of the rotation speed V(20) of the stripper cylinder 20 to the rotation speed V(18) of the extraction cylinder 18, in particular S1=V (20) /V (18) .

[0032] In the same way, the drafting S2 is defined between the pair of pressure calenders 22, 24 and the stripper cylinder 20; the drafting S3 between the compacting device 26 and the pair of pressure calenders 22, 24; the drafting S4 between the pair of output calenders 30, 32 and the compacting device 26; the drafting S5 between the pair of input calenders 44, 46 of the coiler group 40 and ' the pair of output calenders 30, 32 of the carding machine .

[0033] With reference to figure 4, for clarity of description, let Va be the rotation speed of an upstream drafting body (for example the extraction cylinder 18, the stripper cylinder 20, the pair of pressure calenders 22, 24, the compacting device 26, the pair of output calenders 30, 32), and Vb the rotation speed of a downstream body (for example the stripper cylinder 20, the pair of pressure calenders 22, 24, the compacting device 26, the pair of output calenders 30, 32, the pair of input calenders 44, 46) and let S be the drafting between them (S=Vb/Va) .

[0034] According to the invention, in an initial preparation step, for example when starting up the carding machine (moment tO) , the upstream speed Va assumes a preparation value Va 1 ; between upstream and downstream a drafting S exists equal to the preparation value S 1 ; consequently the downstream speed Vb assumes a preparation value V 1 . Such state persists until an end of preparation moment tl.

[0035] In a drafting change step, subsequent to the preparation step, the drafting increases, for example in a ramp trend, up to a processing value S 1 ', reached in a drafting change end moment t2; in said drafting change step, the upstream speed Va remains constant and equal to the preparation value Va 1 ; consequently the downstream speed Vb increases, substantially following the increase pattern of the drafting S, up to an intermediate value Vb*=S ' ' Va' .

[0036] In a possible intermediate step, subsequent to the drafting change step, the upstream speed Va ' , the drafting S'' and the downstream speed Vb* remain constant, up to an intermediate step end moment t3.

[0037] In a pre-processing step, subsequent to the intermediate step or to the drafting change step, the upstream speed Va increases, for example in a ramp pattern, u to a processing value Va 1 ' , in a pre- processing end moment t4; the drafting S remains constant at processing value S ' 1 ; consequently, the downstream speed Vb increases, substantially following the pattern of the upstream speed Va, up to a processing value V 11 = Va' ' x S' ' .

[0038] Advantageously, the drafting only increases when the upstream speed is lower (the minimum) , while it remains constant when the upstream speed increases; this makes it possible, among other things to overcome the drawbacks mentioned in relation to the prior art.

[0039] To perform the drafting control method described above, the card apparatus comprises a control unit 100, comprising a control device 50 comprising, preferably, a PLC or microprocessor.

[0040] Preferably, the control unit 100 comprises an input interface 52, operatively connected to said control device 50, suitable for the manual input of functioning parameters of the card apparatus or for the input of commands, for example by means of a keypad or touch screen .

[0041] According to one embodiment, the control unit 100 comprises a storage unit 54, operatively connected to the control device 5.0, for the permanent storage of functioning parameters of the card apparatus.

[0042] For example, said storage unit 54 has memorised the drafting preparation value S' and/or the drafting processing value S' ' and/or the preparation speed value Va' and/or the processing speed value Va' ' .

[0043] According to yet a further embodiment, the control unit 100 comprises at least one sensor 56, operatively connected to the control device 50, for detecting a functioning condition of the card apparatus, for example so as to detect the presence of the web in a predefined position of the extraction area or to detect the speed of rotation of a cylinder or of a calender, or of the compacting device of the extraction area.

[0044] For example, the sensor 56 is suitable to detect the presence of the web at the pair of input calenders 44, 46 of the coiler group.

[0045] According to yet a further embodiment, the control unit 100 comprises a timer 58, operatively connected to the control device 50.

[0046] In addition, ' the card apparatus 1 comprises one or more separate electric motors 60, controllable in speed, each dedicated to the movement of one or more of the drafting bodies of the extraction area.

[0047] Said motors 60 are operatively connected to the control device 50 and can be speed controlled by the same.

[0048] Consequently, according to one embodiment of the invention, the drafting preparation value S' and/or the drafting processing value S' ' and/or the preparation speed value Va' and/or the processing speed value Va' ' are entered manually by an operator by means of the input means 52.

[0049] Alternatively, such values are supplied to the control device 50 by the storage unit 54.

[0050] According to a preferred embodiment of the invention, the increase of the drafting value S' to the processing value S'' begins and proceeds through intervention of the operator by entering a command in the input means 52.

[0051] According to a further embodiment of the invention, the increase of the drafting begins and proceeds automatically, for example upon receipt by the control device 50 of a preparation end signal for example received from the timer 58 or on the basis of the detection of the sensor 56.

[0052] According to one embodiment of the invention, the web in output from the pair of input calenders 44, 46 is channelled to the rotating can 48 only if the drafting S has assumed the processing value S' 1 or if the downstream speed Vb has assumed the processing speed Vb 1 '.

[0053] Advantageously, this makes it possible to collect in the can only the web having the desired drafting or quality characteristics. [0054] According to a preferred embodiment (figure 5), the carding machine comprises a drafting device 200, positioned in the extraction area, for example downstream of the funnel 28 and/or of the compacting device 26 and upstream of the pair of input calenders 44, 46 of the coiler group 40.

[0055] Said drafting device 200 comprises at least two pairs of drafting calenders, for example three pairs in succession 202, 204; 206, 208; 210, 219.

[0056] In the same way as described above, the drafting control method is applicable to the drafting device 200, and in particular to one or more of the pairs of drafting calenders .

[0057] In particular, a drafting Zl is definable for the drafting device 200 as the ratio between the speed of rotation of the second pair of drafting calenders 206, 208, and the speed of rotation of the third pair of drafting calenders 202; 204; in other words, Z1=V(206, 208) /V(202,204) ; a drafting Z2 as the ratio between the speed of rotation of the first pair of drafting calenders 210, 212, and the speed of rotation of the second pair of drafting calenders 206; 208; in other words, Z2=V(210,212) /V(206,208) .

[0058] Moreover, considering all the drafting bodies operating in the extraction area and positioned in succession, or the groups of such bodies, an initial drafting body and a final drafting body are identified, between which one or more intermediate drafting bodies are positioned.

[0059] Between the initial drafting body and a final drafting body a total drafting (St) is defined , while between the intermediate bodies, intermediate drafting bodies are defined Si, Si+1, ...,Sn.

[0060] The final drafting value St is identified by the product of the intermediate drafting values, according to the formula St = Si x Si+1 x ... x Sn.

[0061] In one embodiment of the control method according to the invention, at least one of said intermediate drafting values Si is automatically identified by the control unit 100, for example by the control device 50, and consequently imposed on the respective' drafting bodies.

[0062] For example, said intermediate drafting values are determined or calculated by the control unit, on the basis of the technological limits of the drafting possible between the relevant intermediate drafting bodies or on the basis of optimal experimental values stored, for example in the storage unit 54.

[0063] Innovatively, the drafting control method according to the present invention makes it possible to overcome the drawbacks of the prior art, and in particular makes 58833

it possible to significantly reduce the risk of tearing the web or sliver.

J

[0064] According to one embodiment variation, the control method described above is applicable in the feed area of the carding machine, for example between the extraction cylinders 6, 8 and the feed cylinder 12.