Abstract:
In the case of an apparatus for a sliver-forming textile machine, especially a draw frame, flat card or the like, a fibre structure (fibre web) coming from the delivery rollers of a drafting system passes through a web guide and a sliver funnel with take-off rollers, the web guide has an inner wall (deflection and/or guide face), and a frictional resistance offered by the inner wall acts on the fibre structure. In order to allow in a simple manner an improved web guidance and sliver quality, and to permit the web guide to be adapted to different technical parameters, such as fibre material properties, working speed, a parameter relating to contact between fibre structure and inner wall is alterable.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from German Patent Application No. 10 2004 028 358.3 dated 11 Jun. 2004, the entire disclosure of which is incorporated herein by reference.  
       BACKGROUND OF INVENTION  
       [0002]     The invention relates to an apparatus for a sliver-forming textile machine, especially a draw frame, flat card or the like.  
         [0003]     In certain sliver-forming textile machines a fibre structure (fibre web) coming from the delivery rollers of a drafting system passes through a web guide and a sliver funnel with take-off rollers, the web guide has an inner wall (deflection and/or guide face, and a frictional resistance offered by the inner wall acts on the fibre structure.  
         [0004]     In the case of a draw frame, the fibre web, which consists of a plurality of drawn fibre slivers, is delivered at high speed from the delivery rollers of the drafting system and is introduced into the entrance opening of the web guide. The fibre web meets the inner wall of the approximately funnel-shaped fleece guide, is condensed and diverted towards the exit opening. The exit opening is arranged downstream of a sliver funnel, through which the fibre material is drawn off in the form of a fibre sliver by take-off rollers.  
         [0005]     In the case of a known apparatus (DE 26 23 400 A), the web guide is provided on its side facing the drafting rollers with a sliding-contact face of concave form. The width of the sliding-contact face is greater than its height. The maximum depth of the sliding-contact face is selected so that it does not exceed 1.5 times the fibre length, measured from the nip of the feed roller. The structural form of the web guide is fixed, especially in operation. The path on which the fibres move from the drafting system through the web guide changes. The fibres of the fibre web along the lateral edges of the approximately triangular web guide and the adjacent fibres have to cover a greater distance than the fibres in the middle of the web, which leads to mutual displacement of the fibres, which adversely affects their parallel position and hence the uniform nature of the fibre fleece; it is even possible for tears to form at the edges thereof, with the result that the fibre sliver often becomes rough and wavy. In addition, it is inconvenient that it is impossible to adapt the web guide to different operating conditions and fibre material qualities.  
         [0006]     It is an aim of the invention to produce an apparatus of the kind described initially, which avoids or mitigates the said disadvantages and which in particular in a simple manner enables the web guidance and sliver quality to be improved and allows the web guide to be adapted to different technical parameters, such as fibre material properties, working speed and the like.  
       SUMMARY OF THE INVENTION  
       [0007]     The invention provides a web guiding assembly for use in a sliver-forming textile machine, comprising: 
        a web guide;     a sliver funnel; and     a take-off mechanism for taking-off fibre from the sliver funnel; 
 
 wherein the web guide includes an inner wall with which the fibre material is, in use, in contact, and the web guide is arranged to permit adjustment of a parameter relating to said contact. 
       
 
         [0011]     The features according to the invention take into account different kinetic and dynamic effects by and on the fibre fleece inside the web guide. The individually acting forces do not occur at all points to the same extent. Consequently, by changing a parameter relating to contact between the inner wall and the fibre material, for example, by changing the interaction and/or the spatial co-ordination between fibre web and inner wall, undesirable or disruptive forces can be partially and individually counteracted. In this way, a substantially improved web guidance and web quality is attained, and a very considerable increase in web running speed of above 1000 m/min can be successfully achieved, especially in the case of draw frames. The web guide improved in accordance with the invention enables the web quality to be enhanced accordingly also at web running speeds of below 1000 m/min, especially in the case of flat cards. The fibre sliver is substantially more uniform, notably in respect of the draft in its different sections or regions. The partial drafts and hence their effect on the sections and regions of the web in the web guide are more uniform and the tension draft as a whole is improved. The invention enables the same web guide to be adapted when there is a change-over, for example, when there is a change in the fibre material being processed, for example in the staple length. In addition, adaptation of the web guidance also in continuous production to changing technical parameters, for example, running speed, variations in thickness and the like, is advantageously rendered possible.  
         [0012]     It is preferred for the interaction to be adjustable, for example, during operation and/or when the machine is not in operating mode. Advantageously, the interaction is automatically adjustable. Advantageously, the interaction is adjustable in a pre-determinable manner. Advantageously, the frictional resistance is at least partially reducible by altering the interaction and/or the spatial co-ordination between fibre structure and inner wall of the web guide. Advantageously, the frictional resistance is reducible at one or more regions of the inner wall. Advantageously, the frictional resistance is reducible segment-wise at the inner wall. Advantageously, the coefficient of friction p is alterable. Advantageously, the angle of resistance is alterable. Advantageously, the tension draft is alterable. Advantageously, the inner wall is formed at least partially from a low-friction material. Advantageously, the inner wall is coated at least partially with a low-friction material. Advantageously, the inner wall is at least partially of segment-like construction. Advantageously, the size and/or the position of the inlet opening of the web guide is alterable. Advantageously, forces acting on the fibre structure are the same as or greater than the pressure applied by the fibre structure to the inner wall. Advantageously, the frictional resistance at the points of greatest pressure application or frictional resistance of the fibre structure against the inner wall is reducible. Advantageously, the inner wall has a covering, for example, a coating, foil or the like, which has an alterable coefficient of friction in the conveying direction. Advantageously, the web guide has an inner wall surface that is spatially formed in such a way that on this surface all fibres of the fibre web have to cover an approximately equal path until they are combined to form the fibre sliver. Advantageously, the set angle of the lateral surfaces is alterable. Advantageously, the contour of the lateral surfaces is alterable. Advantageously, the inner wall surfaces are of resilient construction. Advantageously, the inner wall surface is at least partially alterable between concave, planar and convex. Advantageously, mobile contour elements are associated with the inner wall surface. Advantageously, the contour elements are displaceable. Advantageously, the resistance to wear of the inner wall is alterable. Advantageously, the tension draft of the fibre structure is alterable, for example, by drive control. Advantageously, a measuring and observing device for the fibre web, for example, an electronic camera, video camera or the like, is associated with the web guide. Advantageously, the inner wall comprises at least lateral inner wall surfaces. Advantageously, the inner wall includes the top surface (upper web guide hinged cover). Advantageously, the inner wall includes the bottom surface (lower web guide hinged cover).  
         [0013]     The invention also provides an apparatus for a sliver-forming textile machine, especially a draw frame, flat card or the like, in which a fibre structure (fibre web) coming from the delivery rollers of a drafting system passes through a web guide and a sliver funnel with take-off rollers, the web guide has an inner wall (deflection and/or guide face), and a frictional resistance offered by the inner wall acts on the fibre structure, characterised in that the interaction and/or the spatial co-ordination between fibre structure and inner wall of the web guide is alterable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a diagrammatic side view a drafting system with an entrance opening of the web guide according to the invention, the web guide being downstream of the delivery rollers of the drafting system, and with a sliver funnel and take-off rollers,  
         [0015]      FIG. 2  is a diagrammatic side view of a drafting system similar to that in  FIG. 1 , with an electronic camera associated with the web guide,  
         [0016]      FIGS. 3   a ,  3   b  are a plan view in section and a front view, respectively, of the web guide of  FIGS. 1 and 2 ,  
         [0017]      FIG. 4  is a diagrammatic side view of a drafting system with a block diagram of an electronic control and regulating device and comprising an apparatus according to the invention,  
         [0018]      FIG. 5  is a schematic view of the interior of a web guide including pivotable lateral walls,  
         [0019]      FIG. 6  is a schematic view of the interior of a second form of web guide having pivotable lateral walls.  
         [0020]      FIG. 7   a  is a schematic view of the interior of a third form of web guide with lateral walls of variable contour,  
         [0021]      FIG. 7   b  shows the web guide of  FIG. 7   a  with the lateral walls formed into a second contour,  
         [0022]      FIG. 7   c  shows the web guide of  FIG. 7   a  with the lateral walls formed into a third contour,  
         [0023]      FIG. 7   d  shows schematically a mechanism for enabling the contour of the lateral walls to be altered,  
         [0024]      FIG. 8  us a schematic view of the interior of a fourth form of web guide with displaceable contour elements,  
         [0025]      FIG. 9  is a schematic view of the interior of a fifth form of web guide,  
         [0026]      FIG. 10  is a schematic view of the interior of a sixth form of web guide,  
         [0027]      FIG. 11  is a diagrammatic side view of a further drafting system according to the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0028]     Referring to  FIG. 1 , a draw frame, for example, a draw frame TD 03 made by Trützschler GmbH &amp; Co. KG, comprises a drafting system  1  with a drafting system inlet and a drafting system outlet. The fibre slivers  2 , coming from cans, enter a sliver guide and, drawn by take-off rollers, are transported past a measuring element  28  (cf.  FIG. 4 ). The drafting system is designed as a 3-over-4 drafting system, that is, it consists of three bottom rollers I, II, III (I being the bottom delivery roller, II being the middle feed roller and III being the bottom feed roller) and four top rollers  3 ,  4 ,  5 ,  6 . Drafting of the fibre sliver  2  comprising several fibre slivers takes place in the drafting system  1 . The draft is made up of the preliminary draft and the main draft. The roller pairs  6 /III and  5 /II form the preliminary draft zone and the roller pairs  5 /II and  3 ,  4 /I form the main draft zone. The drawn fibre slivers (fibre web  14 ) reach a web guide  7  at the drafting system outlet and are drawn by means of the take-off rollers  8 , 9  through a sliver funnel  10 , in which they are condensed to a fibre sliver  11 , which is subsequently laid by way of a can coiler  12  in cans (not illustrated). The letter A denotes the running direction in the drafting system  1  of the fibre structure  14 ′ comprising several fibre slivers.  
         [0029]     In the embodiment of  FIG. 2 , in the top surface  7   e  (see  FIG. 3   b ) and in the bottom surface  7   f  of the web guide  7  there is a transparent window  17  and  18  respectively. Externally at a distance from the top surface  7   e , a CCD camera  15  and two light-emitting diodes (LED)  19 ,  20  are arranged opposite the window  17 . Externally at a distance from the bottom surface  7   f , a light-emitting diode (LED)  21  is arranged opposite the window  18 . In this way, the fibre web  14  that has entered the interior  7 ′ of the web guide  7  is optically detected between entrance opening  7   a  and exit opening  7   b . The optical axis of the camera  15  lies perpendicular to the running direction B of the fibre web  14 . The top and bottom surfaces  7   e ,  7   f  respectively are hinged; recordings are taken through the windows  17  and  18  with the top and bottom surfaces  7   e ,  7   f  closed. Because light-emitting diodes  19 ,  20  are located on the side with the camera  15  and a light-emitting diode  21  is located on the side of the web guide  7  remote from the camera  15 , recordings of reflected light and transmitted light are possible. The recordings are effected both at delivery speed (900 m/min and above) and also when accelerating and decelerating the speed of the fibre web  14 . A CCD camera (charge coupled device camera) is present as electronic camera  15 , which communicates with an electronic evaluation circuit  16  (image-processing unit) that is connected to an electronic control and regulating device  38  (see  FIG. 4 ).  
         [0030]     As shown in  FIG. 3   a , the web guide  7  is of funnel-like form and has an open side  7   a  (entrance-side opening) and a through-opening  7   b . The interior  7 ′ of the web guide  7  is formed by two concavely converging lateral surfaces  7   c ,  7   d , and a respective planar top surface  7   e  and bottom surface  7   f  (cf.  FIG. 3   b ). The top surface  7   e  and the bottom surface  7   f  are hinged. The entrance-side opening  7   a  is larger than the through-opening  7   b . Adjoining the through-opening  7   b  are transfer tubes  22  and  23 , which guide the condensed fibre web  14  into the web funnel  10  (see  FIGS. 1 and 4 ). On the lateral inner wall surfaces  7   c  and  7   d  there is arranged an exchangeable coating  40   a  and  40   b  respectively, each of which has varying coefficients of friction in the respective running directions C and D.  
         [0031]     In operation, the fibre web  14  leaving the roller pair  3 /I passes through the entrance opening  7   a  into the interior  7 ′, meets the coated inner surfaces  7   c  and  7   d , is caused to converge by the coated inner surfaces and directed in the direction of arrows C and D to the exit opening  7   b . As this happens, the fibre web  14  is condensed, air being expelled and escaping in the direction of arrows E and F opposite to the running direction B through the entrance opening  7   a  to the atmosphere.  
         [0032]     In the embodiment of  FIG. 4 , at the drafting system outlet  25  the drawn fibre slivers reach the web guide  7  and are drawn by means of the take-off rollers  8 ,  9  through the sliver funnel  10  in which they are condensed to the fibre sliver  11 , which is subsequently deposited in cans. A central processing unit  38  (control and regulating device), e.g. a microcomputer and microprocessor, delivers a setting of the desired variable for an actuating element  30 , which changes the inner wall surfaces  7   c  and  7   d . The control value for the actuating element  30  is determined in the central processing unit  38  from the measurements of the camera  15  and/or from the desired value for the cross-section of the emerging fibre sliver  11 .  
         [0033]     The camera  15  is connected by way of the image-processing device  16  to the electronic control and regulating device  38 . In this way, the results of the image analysis can be used in a closed loop system to optimise the web guide  7 . The results of the image analysis of the fibre web  14  can be filed in a memory  39 .  
         [0034]     According to the exemplary embodiment, the CCD camera  15  can be used to take images of the web  14 . Images of the web  14  can also be taken by means of digitised photodiodes. Evaluation of the digital image information is effected online by means of image analysis software. The camera axis lies preferably perpendicular to the web  14 . The camera  15  can be moved along the inside frame width (IW) of the machine, in order to record images across the working width of the draw frame. Advantageously, the camera  15  can be moved automatically away from the web  14  or a wide-angle setting can be used on the camera in order to record the entire web width at one time. The camera  15  can also be pivotable, in order to record images across the working width of the draw frame. The web guide hinged members  7   e ,  7   f  are transparent, so that recordings of the web  14  are produced with the web guide  7  closed. The recordings are made of reflected light and transmitted light. For that purpose, LEDs are located on the camera side and on the draw frame side respectively. It is possible to record images of the web at delivery speed and when accelerating and decelerating. Advantageously, recordings are made in the middle region of the web in order to examine the web for uneven patches. The cause for this can include: poor short fibre guidance, poor gripping of the web, wrong drafting system settings. Furthermore, recordings of this web area can be used to analyse the degree of parallelization of the fibres, the number and size of neps, the structure influence of the material and dust formation that occurs. Using all these influences, the quality of the drafting process can be determined. Preferably, recordings are also made specifically of the edge region, in order to be able to analyse the guidance of the edge fibres in the drafting process (closed or incomplete web structure at the edges). It is thus possible, when removing the web, to determine whether there will be striations (along the fibres) across the working width. These occur because the slivers do not enter the web guide properly, that is, slivers enter one on top of the other or with too much distance between each other. By analysing the entire web width, an assessment of the tension draft in this region can also be made. A further advantage is that the alignment of the slivers or fibres is analysed. The number and the position of the obliquely-running or straight-running slivers is a measure of the effective tension draft. The take-off roller tension draft is dependent on the parameters: delivery speed, draft, friction, number of slivers, material, contamination etc.). Thus the real take-off roller tension draft is objectively determined. At the control and regulation device  38 , images relating to fibre orientation at optimum tension draft can be stored. In particular, by means of a closed loop system the take-off roller tension draft can be fully automatically or semi-automatically (manual gear changing) specifically optimised.  
         [0035]     The control and regulating device is connected via drive control  33  to drive motor  31  for the rollers  27 , III and II and via drive control  34  to drive motor  32  for the rollers I,  8  and  9 . Reference numeral  37  represents a processing device for processing signals from a sensing device (not shown) in funnel  10 .  
         [0036]     All available line scan sensors, such as LED line scan cameras  15 , X-ray and infrared line cameras can be installed.  
         [0037]     The invention was explained with reference to the example of an autoleveller draw frame. A non-regulated draw frame is also covered.  
         [0038]     In  FIG. 5  is shown one form of web guide  7  for use in an apparatus of the invention. In the region of the exit  7   b  each of the lateral walls  7   c  and  7   d  is associated with a swivel joint  41   a ,  41   b  respectively, so that the lateral walls  7   c ,  7   d  are pivotable in the direction of the arrows G, H and I, K respectively.  
         [0039]      FIG. 6  shows another form of web guide  7  for use in an apparatus of the invention. Swivel joints  42   a  and  42   b  are provided in the region of the entrance  7   a , the effect being that the lateral walls  7   c ,  7   d  are pivotable in the direction of the arrows L, M and N, O.  
         [0040]     In the web guide of  FIGS. 7   a  to  7   c , the contour of the lateral walls  7   c ,  7   d  and consequently the deflection or guide surfaces for the fibre web  14  is variable from convex ( FIG. 7   a ) through planar ( FIG. 7   b ) to concave ( FIG. 7   c ). The lateral walls  7   c .  7   d  can be of resilient construction, as shown in  FIG. 7   d , for example, in the form of leaf springs or similar. In order to change the contour of the leaf spring  7   c  and hence the deflection or guide surface, the leaf spring can be fixedly mounted at one end  7 ′, whereas an adjustment device  43  acts in the region of its other end  7 ″. The adjustment device  43  can be adjusted manually, for example, by an adjusting screw or the like, or by motor, or can be in the form of a pneumatic cylinder  49 . The push rod  49   a  of the pneumatic cylinder  49  is displaceable in the direction of the arrows X, X′ and with one end is in rotatable engagement with the end region  7 ″ of the leaf spring. The cylinder body  49   b  is mounted so as to be displaceable by way of a guide element  50 , for example, a sliding block, in a curved guide  51  in the direction of the arrows Y, Y′. Depending on the position of the pressure cylinder  49 , that is, on the one or the other side of the neutral axis of the leaf spring  7   c , then with respect to the fibre sliver  14  the leaf spring  7   c , and hence its deflecting and guide surface, is curved concavely in the direction of arrow Z ( FIGS. 7   c ,  7   d ) or convexly in the direction of arrow Z′ ( FIG. 7   a ). The adjustment device  43  can be in the form of an actuator  30  connected to the control and regulating device  38  (see  FIG. 4 ).  
         [0041]     In a further web guide shown in  FIG. 8 , on the surface of the lateral walls  7   c  and  7   d  respective contour elements  44   a  and  44   b  are arranged, which are displaceable in direction P,Q and R,S respectively.  
         [0042]     In a web guide of  FIG. 9 , a foil or similar  45   a ,  45   b  is associated with a respective one of the surfaces of the lateral walls  7   c  and  7   d , which is displaceable in the direction of the arrows T,U and V, W respectively around winding up and unwinding rolls  46   a ,  46   b ,  47   a ,  47   b . The foil  45   a ,  45   b  has different coefficients of friction, roughness or frictional resistance or the like in the direction of the arrows T, U, V, W with respect to the fibre web  14 . The foils  45   a ,  45   b  can alternatively be in the form (not illustrated) of endless belts around associated, driven belt guide rollers.  
         [0043]     In the web guide of  FIG. 10 , the surfaces of the lateral walls  7   c  and  7   d  are each in the form of three zones or regions a, b and c, which are different in respect of surface structure and/or surface frictional resistance. The zones or regions can be in the form of exchangeable or displaceable regions.  
         [0044]     In the web guide of  FIG. 11 , separate drive motors  32  and  48  which, in connection with the electrical control and regulating device  38 , are associated with the delivery rollers  3 ,  4 /I of the drafting system  1  and the take-off rollers  8 ,  9  respectively. In this way, the tension draft of the fibre structure is adjustable between the outlet of the drafting system  1  and the take-off rollers  8 ,  9 .  
         [0045]     The interaction and/or the spatial co-ordination between the fibre structure  14  and inner wall (lateral walls  7   c ,  7   d  and/or top wall  7   e  and/or bottom wall  7   f ) of the web guide  7  can advantageously be altered in operation, for example automatically as per the arrangement shown in  FIG. 4  using actuating element  30 . They can also be altered manually during or outside of operation, for example, by adjusting elements (adjusting screws or the like).  
         [0046]     The invention encompasses arrangements in which the manner in which the inner wall contacts the fibre material can be changed. Thus the invention includes arrangements in which the web guide can be so adjusted that the spatial relationship between, on the one hand, the fibre material coming into contact with the inner wall and, on the other hand, the inner wall is changed. For example, the contour or position of at least a part of the inner wall may be variable such that the relative orientation of the fibre material and the inner wall surface is variable. The invention also includes arrangements in which the web guide can be so adjusted that the manner in which the inner wall physically interacts with the fibre material may be changed independently of any change in relative orientation. For example, the surface characteristics of the inner wall, such as frictional characteristics may be modifiable. The invention further includes arrangements in which both the spatial relationship is adjustable, and the interaction between the inner wall and the fibre is adjustable especially by varying the surface characteristics of the inner wall.  
         [0047]     Although the foregoing invention has been described in detail by way of illustration and example for purposes of understanding, it will be obvious that changes and modifications may be practised within the scope of the appended claims.